This is a process and method by which a paving grade asphalt material, having normal penetration of from 40 to 300, may be reduced without sacrifice of other significant properties, to less than 25 penetration by the proportioning and blending of a very hard, high softening point, solvent extracted resin-asphaltene residuum
The proportioning and blending is accomplished without use of further refining processes, i.e., using steam, vacuum or solvent refining. The proportioned and blended product may then be diluted with evaporative petroleum solvents to produce a penetrative binder suitable for the stabilization of pavement surface layers.
On Nov. 9, 1965, U.S. Pat. No. 3,216,336 was granted to J.R. Benson on "ASPHALT PENETRATIVE GROUND STABILIZER", hereinafter referred to as "BENSON PATENT". The invention related to soil stabilizing by use of an asphaltic binder mixture. The mixture made use of a selected, single, hard asphalt, resulting from the propane extraction process used in oil refining. However, the sources of suitable hard asphalt were discovered to be somewhat limited. This suitable asphaltic material could also be used to improve the quality of regular paving asphalt cements for which there was greater demand. As a result, the ASPHALT PENETRATIVE GROUND STABILIZER, covered by the "Benson Patent", never obtained wide general acceptance in the United States.
Further, due to the crude oil shortages that occurred in the early 1970's in the United States, and the necessity of producing maximum energy products and lubricating oils from the available crude oils, many oil refineries in the United States, stopped producing not only soft normal asphalt of 40 to 300 penetration, but also the 3 to 25 penetration asphalts required for use with the Benson patent. Instead, new more efficient solvent refining methods were accepted, by which even greater proportions of lubricating oils were extracted from the crude oil, from which only extremely hard or even dry powderous residues were obtained, very different from the original solvent extracted 3 to 25 penetration described by Benson. With the new (liquid separation of oil and residuum versus the previous liquid separation processes) more efficient systems, production and availability of the original 3 to 25 penetration, low softening point solvent extracted asphalts became less and less available. As a result, the use of the Benson material (marketed under the trademark "Peneprime") diminished to the point of non-use and relinquishment of the trademark "Peneprime".
An important part of the Benson Patent related to the character of the hard base asphalt. Previous attempts to utilize hard asphalt materials (within 3 to 25 penetration range) were unsuccessful, due to brittleness of the treated surfaces. Rapid breakup and ravelling occurred under exposed traffic. The asphalts produced in these trials were usually air-blown asphalts, asphalts where consistency (penetration) had been reduced from soft asphalts (50 penetration and above) by heating and blowing with air. While the treatment succeeded in obtaining hard asphalts, such asphalts had high softening points and very low normal ductilities. Benson discovered, however, that when soft asphalts and distillation residuals were hardened by a propane extraction process, the asphalts so produced not only had desired penetration (in the 3 to 25 range) but these asphalts also had low softening points. Benson ascribed his successful use of such materials, in a penetrative binder, to the properties of low penetration and low softening points. In only one known case (due to the peculiarity of the crude oil from which the soft asphalt was produced) could a soft asphalt be reduced by blowing with air at high temperatures, to below 25 penetration, while still retaining low softening point. All other known materials were propane extracted. Benson further patented (U.S. Pat. No. 3,399,608 - granted Sept. 3, 1968) an emulsion which also could be successfully used as a cementing binder, consisting of the hard base (solvent extracted hard asphalt) and a small quantity of suitable distillates. In still later developments (U.S. Pat. Nos. 4,268,318--granted May 19, 1981 and 4,373,961--granted Feb. 15, 1983 both to Stone) a blend of soft asphalt and a hard solvent extracted asphalt was invented, having penetrations below 50, a high ductility, and low softening points.
Prior to discontinuing the use of the Benson penetrative binder, a number of schemes were "improvised" to produce satisfactory basic asphalt to meet the requirements of the Benson discoveries. Straight reduction of soft asphalts to penetrations below 25, by use of high temperatures and steam, proved to be impractical. The cost of the required equipment for such operation could not be justified. It was apparent that in order to obtain an asphaltic material equal to the propane extracted asphalts generally used under Benson's patent, a simple process utilizing locally and immediately available normal paving grades asphalts had to be developed. Also, it was essential that such asphalts be economically reduced to penetrations below 25, while retaining high ductilities and low softening points. Further, it was apparent that all necessary components of an asphaltic material meeting the requirements of the Benson Patent must be readily and economically available in all parts of the United States, using simple, low-cost equipment.
During recent years, new oil refining processes have been developed. One of these processes is the ROSE process (Residuum Oil Supercritical Extraction) developed by Kerr-McGee Corporation Another, a similar process, has been engineered by Universal Oil Products (U.O.P.), INC. for Diamond Shamrock Refining and Marketing Company at its oil refinery at Three Rivers Texas. All of these oil refineries produce a resin-asphaltene residuum that is very hard. The penetration is zero at 77.degree. F., with a softening point above 175.degree. F. In some instances, due to these and other undesirable characteristics, including such materials as ash and various metals which make the residuum frequently unacceptable for blending into normal paving grade asphalt, the residuum is sometimes regarded as a "waste" product, even having negative value with the product makketed at substantially less than normal paving grades asphalt prices. However, it has been found that such resin-asphaltene residuum may be proportioned and blended with normal paving grades asphalt (40 to 300 penetration--hereinafter called "Normal paving grades asphalt"), the resultant asphalt being proportioned to give minus 25 penetration. This material exhibits good ductility and softening points, characteristics suitable for the purpose of stabilizing absorptive granular materials. In this use, the ash and metals in the resin-asphaltene residuum pose no problem since they are completely encapsulated in the absorbed cured material in the road surface.
Whereas only propane extracted asphalt or similar products were usable under the Benson Patent, the present invention's composite product, which uses a minor part of such residuum and a major part of normal paving grades of asphalt, results in a suitable product for all of the purposes set forth in the Benson Patent. The usual proportions of residuum and diluent are less than one-third residuum and more than two-thirds normal paving grades of asphalts. Since normal paving grades of asphalts are universally available throughout the United States, it is now possible by use of these residuums, to economically produce an asphalt cement for stabilizing of highway and road building surfaces of soil and aggregates (sand and gravel). Roadway driving surfaces can be produced at one-half the cost or less of normal asphalt pavements. In addition, the new stabilizer product can be produced without expensive and complicated refining equipment. It can be produced by simple processes of blending, involving only low-cost equipment and operated by personnel having very limited technical training. The blending process consists essentially of heating the normal paving grades asphalts to temperatures of 300.degree. F. and above, proportioning, injecting or adding molten (liquid) or dry residuum until the penetration of the resultant blend is below 25 penetration. The resultant product is blended with a naptha-kerosene solvent as used in the Benson stabilization process. The napthakerosene solvent may be added to the normal paving grades asphalt before or after the injection of the residuum.
The end product, a blend of normal paving grades asphalts and residuum, diluted with solvent sufficient to make a fluid blend at ambient temperature, penetrates well into earthen or slightly porous highway, road or other surface. The resultant product then cures into a hard, durable surface as described in the Benson Patent. The process of blending the composite asphalt, as described above results in an increase in the polar activity of the resultant composite micelle, permitting a more complete penetration and bonding into the highway, road or other surfaces.
Whereas normal paving grades asphalts have a substantial percentage of oily constituents, including malthenes, the resin-asphaltene residuum is essentially an asphalt residue from which nearly all oily constituents and much of the resins have been extracted. The remaining material consists of a micelle, comprising a carbonaceous core encompassed in a hard resinous material. The micellian structure of the original asphalt is thereby retained. Electrical resistivity tests indicate the retention of the resinous material since the carbonaceous core material in the center of the micelle is more or less conductive. It is this fact that accounts for the ability of the residue to disperse and dissolve in the basic asphalt. By blending these products in the disclosed proportions, the resultant mixture has a larger percentage of asphaltenes and hence greater cementing and load bearing capacities than normal paving grades asphalts. Such characteristics provide longer life roadway surfaces with greater resistance to weathering.
The unexpected results and advantages of blending composite asphalts from residuums and normal paving grades asphalts according to the present invention are as follows:
1. The resin-asphaltene residuum is soluble in, and easily dispersed into, regular paving asphalts.
2. The blend is congenial, with no significant separation.
3. Penetration of less than 25 can be obtained.
4. The composite of residuum and normal paving grades asphalts has an equal or greater ductility than normal paving grades asphalts.
5. The composite blend can be diluted with a naptha-kerosene blend without precipitation of asphaltenes.
6. The composite asphalt, when diluted with a naptha-kerosene blend, readily penetrates earthen highway, road and other surfaces, to depths equal to or greater than the diluted propane extracted asphalt as covered by the Benson patent.
7. The treated granular material hardens and cures into a surface suitable for traffic with good durability (due to high ductility), and has weathering characteristics superior to previously used propane extracted asphalts.
8. The resin-asphaltene residuum can be moderately diluted with kerosene or the like and shipped in tank cars to distant locations, thereafter being diluted to required viscosities.
9. The residuums can also be shipped in containers similar to conventional shipment of roofing asphalts. It can then be melted, blended into a composite, and further blended with the required solvent to the required viscosities.
In the present invention, a process has been discovered which produces a material with the desired properties for use as a penetrative binder. Wide availability of residuum, from ROSE and U. O. P., locally available paving grade asphalts, and simple low-cost processing equipment now permits products equal to or better than the previously available propane extracted asphalts used by Benson.


Prior to the present invention, methods for determining ions in solution included flame photometry, atomic absorption photometry and ion-specific electrodes. The use of certain compounds and compositions which selectively isolate certain ions from the sample solution has become popular in ion-specific electrodes. These substances, known as ionophores, have the capability of selectively isolating ions from their counterions thereby causing a charge separation and a corresponding change in electrical conductivity in the phase containing the ionophore. Illustrative of the ion/ionophore phenomenon include ion assays utilizing membrane electrodes, liquid/liquid partitioning and fluorescence.


The present invention relates to a drive system for a variable vacuum capacitor.
Variable vacuum capacitors often comprise a first set of electrodes movably arranged with respect to a second set of electrodes. The electrodes may be arranged, for example, as concentric rings. Principally, in a variable vacuum capacitor, a first set of concentric rings may be moved into a second set of concentric rings. Due to such a movement, the area is increased of parts of the first concentric rings and of parts of the second concentric rings that lie opposite to each other. This leads to an increase of the relevant active area and therefore to an increase of the capacitance of the variable vacuum capacitor. The relative movement of the first and the second electrodes is performed by means of a mechanical drive system. Such a mechanical drive system may comprise a drive screw and a nut. The drive screw may be manufactured out of stainless steel and the nut may be manufactured out of lead bronze. Apart of the electrodes and the drive system, a variable vacuum capacitor includes further elements. These further elements may comprise, for example, a housing bottom, an insulator, a housing top and a spring bellow. A first set of electrodes may be arranged in the housing bottom. Together with the spring bellow and the drive system, a second set of electrodes may be arranged in the housing top. By means of the drive system, the second set of electrodes can be moved in a given direction. The insulator may be arranged between the housing bottom and the housing top. The vacuum of the vacuum capacitor is basically surrounded by parts of the housing top and the bellows on one side, and by parts of the housing top, the insulator and the housing bottom on the other side.
Variable vacuum capacitors are used in a wide variety of industrial applications. Such applications comprise radio broadcasting systems, manufacturing systems for flat panel displays, manufacturing systems for semiconductors, or other industrial applications. For such applications, variable vacuum capacitors are needed capable of withstanding currents of about 50 A to 200 A, or currents of up to 900 A, or higher currents, and voltages of up to 90 kV, or higher voltages. The range of the variable capacitance of a variable vacuum capacitor may be 20 pF for the lowest value and
5000 pF for the highest value. Depending on the application, a variable vacuum capacitor may be constructed to provide other ranges of a variable capacitance. Further requirements for variable vacuum capacitors may comprise operating conditions as, for example, a certain nominal frequency, a temperature range for running the capacitor, and other requirements.
Variable vacuum capacitors have to be constructed for a long lasting operational life. Therefore, the parts of a variable capacitor have to be manufactured in a high quality. In recent years, the requirements regarding the speed for changing the capacitance of a variable vacuum capacitor have increased. Basically, a change of the capacitance of a variable vacuum capacitor is performed by rotating the drive screw. By means of such a rotation, the capacitance of the variable vacuum capacitor is changed accordingly. If a last change of the capacitance is needed, a high rotation speed of the rotating screw is needed equally well. In recent years, the required rotation speed has increased from about 100 rpm to 600 rpm or higher. These demands have led the manufacturers to introduce new hardening techniques for the drive screw and to introduce new lubricants. However, the results achieved by these techniques have not fully satisfied the needed requirements, especially with respect to the durability of the drive system.
It is desirable to propose a new drive system for a variable vacuum capacitor, which drive system does not have the drawbacks of the prior art. In particular, the new drive system should have an improved life expectancy, while increasing the allowable speed for changing between different capacitance values of the variable vacuum capacitor. Preferably, the mechanical drive system comprises a drive screw and a nut, wherein the nut is arranged in a housing of the vacuum capacitor, wherein the drive screw is screwed through the nut, wherein a first electrode is arranged on one side of the drive screw, wherein, by means of a rotation of the drive screw, the first electrode is movable relative to a second electrode.
According to an aspect of the present invention the nut of the mechanical drive system of a vacuum capacitor is at least partially manufactured from plastic material. In particular, such a drive system has the advantage that a high speed in the change of the capacitance of the variable vacuum capacitor can be achieved and that the durability of the drive system can be improved significantly.
In an embodiment variant, the nut is substantially manufactured fully out of plastic material. In particular, such a drive system has the advantage that the number of needed parts can be minimized.
In another embodiment variant, the part of the nut for screwing the drive screw through the nut is manufactured out of plastic material and the part of the nut for arranging the nut in the housing of the vacuum capacitor is manufactured out of metallic material. Such an embodiment has the advantage that the physical properties of the nut can be adapted to the physical properties of the material contacting the nut when installed.
In a further embodiment variant, the plastic material comprises a high performance plastic material. Such an embodiment has the advantage that a high performance plastic material with well known physical properties can be used for achieving desired results with respect to durability and speed of operation of the mechanical drive system.
In another embodiment variant, the plastic material comprises a high performance and high temperature up to 250° Celsius polymer plastic material with a friction factor of <0.1 @ 100° Celsius. Such an embodiment variant has the advantage that well known products may be used for achieving the desired results with respect to durability and speed of operation of the mechanical drive system.
In a further embodiment variant, the metallic material comprises a stainless steel. Such an embodiment has the advantage that a well known material for achieving durability and speed of operation can be used.
In another embodiment variant, the drive screw comprises a PVD (PVD: Physical Vapor Deposition) coating or a coating of a similar process, with a Vickers hardness of 6,000 HV or higher. Such an embodiment has the advantage that durability and speed of operation can be significantly improved.
In FIG. 1, the reference numeral 1 refers to a variable vacuum capacitor. The variable vacuum capacitor comprises a housing and insulator. A first electrode (not shown) and a second electrode (not shown) are arranged inside the housing and the insulator of the variable vacuum capacitor. For example, the first electrode may be attached to a drive screw, which has reference numeral 2 in FIG. 1, and the second electrode may be arranged opposite the first electrode in a fixed position relative to the housing of the variable vacuum capacitor. The capacitance of the variable vacuum capacitor is adjusted by means of a change of distance between the first electrode and the second electrode. In order to increase the active area, the first electrode and the second electrode may comprise ring electrodes or helical electrodes. The change in distance between the electrodes is performed by means of a mechanical drive system. In FIG. 1, the reference numeral 3 relates to a nut. The nut 3 is arranged in a fixed position relative to the housing of the variable vacuum capacitor. For example, the nut 3 may be attached to the housing by means of several screws. The drive screw 2 is screwed through the nut. Therefore, when the screw 2 is turned in one direction or the other, the first electrode is moved with respect to the housing and equally well with respect to the second electrode, leading to an increase or a decrease of the capacitance of the variable vacuum capacitor. In FIG. 1 the reference numeral 4 refers to a cap and the reference numeral 5 refers to a ball bearing. The cap 4 may be manufactured out of aluminium, for example. The ball bearing may be a standard ball bearing. The cap 4 and the ball bearing 5 may improve the quality of the mechanical drive system. The nut 3 comprises plastic material which, in contact with the drive screw 2, provides preferred physical properties, especially with respect to durability and speed of operation of the mechanical drive system.
In FIG. 2, a first embodiment of the nut is shown. In FIG. 2, the reference numeral 1 refers to a plastic cylinder of the nut and the reference numeral 2 refers to a metallic cylinder of the nut. The plastic cylinder 1 is arranged inside the metallic cylinder 2. The outer diameter of the plastic cylinder 1 may be a little bit larger, for example 1/10 mm, than the inner diameter of the metallic cylinder 2. The plastic cylinder 1 may be pressed into the metallic cylinder 2. The plastic cylinder 1 comprises a screw thread adapted to house the drive screw. The metallic cylinder 2 may comprise means, for example holes for housing screws, for arranging the nut in a housing of the variable vacuum capacitor.
In FIG. 3, a second embodiment of the nut is shown. In FIG. 3, the reference numeral 1 refers to a plastic component of the nut and reference numeral 2 refers to a metallic part of the nut. The metallic part 2 of the nut may be adapted to protect the plastic part 1 of the nut from forces applied by screws when the nut is arranged in a housing of the variable vacuum capacitor.
When the mechanical drive system is installed, a lubricant may be applied to the drive screw, such that the friction between the drive screw and the nut is reduced further. Such a lubricant may comprise synthetic oil.
The drive screw may comprise a PVD (PVD: Physical Vapor Deposition) coating, which coating may be manufactured by means of well known methods and procedures.
The plastic material may be manufactured in such a manner that the variable vacuum capacitor may be operated in a temperature range from about 0° Celsius to about 125° Celsius. For example, the plastic material may comprise a high performance and high temperature polymer plastic material, which may have the following properties: maintenance free, wear-resistant, low friction, impact-resistant, vibration-resistant, well-priced, easy to process (e.g. chipping, grinding, burnishing), adapted to be glued or to be welded, anti-adhesive. The features of the plastic material may comprise: usable in a temperature range of −50° Celsius to 140° Celsius, maximal permissible temperature of 250° Celsius, dynamic coefficient of friction of <0.1 (for dry run @ a temperature of 100° Celsius), and wear factor of <0.15 mm/100 km.


An automatic transmission of a vehicle commonly includes a torque converter for coupling the transmission to the vehicle's engine. The torque converter provides a fluid coupling which allows the engine to spin somewhat independently of the transmission so that the transmission can slow or stop without stalling the engine. Beneficially, the torque converter also provides a magnification of torque from the engine to the transmission when accelerating from a halt. However, at higher vehicle speeds where the speed of the transmission catches up to the speed of the engine the fluid coupling is less efficient than a rigid coupling between the transmission and the engine, and results in increased fuel consumption.
It has been proposed to provide a torque converter with a lockup clutch which provides a selectively operable direct connection between the engine and the transmission to eliminate slippage and to improve fuel efficiency. The lockup clutch has a driving part which is driven by the engine and a driven part which is in direct connection with the transmission. The driving part and the driven part are able to be brought selectively into frictional engagement so as to provide the direct driving connection between the engine and the transmission, and are able to be brought selectively out of frictional engagement when the direct connection is not desired, for example when the vehicle is at a standstill.
The applicant has determined that by providing more accurate control of the lockup clutch better fuel economy may be achieved.


A need exists for a method for therapeutic treatment of afflicted tissue and cells of animals that is non-invasive, easy to apply, and quick to provide relief.
The present embodiments meet these needs.
The present embodiments are detailed below with reference to the listed Figures.


Noroviruses are non-cultivatable human Caliciviruses that have emerged as the single most important cause of epidemic outbreaks of nonbacterial gastroenteritis (Glass et al., 2000; Hardy et al., 1999). The clinical significance of Noroviruses was under-appreciated prior to the development of sensitive molecular diagnostic assays. The cloning of the prototype genogroup I Norwalk virus (NV) genome and the production of virus-like particles (VLPs) from a recombinant Baculovirus expression system led to the development of assays that revealed widespread Norovirus infections (Jiang et al. 1990; 1992).
Noroviruses are single-stranded, positive sense RNA viruses that contain a non-segmented RNA genome. The viral genome encodes three open reading frames, of which the latter two specify the production of the major capsid protein and a minor structural protein, respectively (Glass et al. 2000). When expressed at high levels in eukaryotic expression systems, the capsid protein of NV, and certain other Noroviruses, self-assembles into VLPs that structurally mimic native Norovirus virions. When viewed by transmission electron microscopy, the VLPs are morphologically indistinguishable from infectious virions isolated from human stool samples.
Immune responses to Noroviruses are complex, and the correlates of protection are just now being elucidated. Human volunteer studies performed with native virus demonstrated that mucosally-derived memory immune responses provided short-term protection from infection and suggested that vaccine-mediated protection is feasible (Lindesmith et al. 2003; Parrino et al. 1997; Wyatt et al., 1974).
Although Norovirus cannot be cultivated in vitro, due to the availability of VLPs and their ability to be produced in large quantities, considerable progress has been made in defining the antigenic and structural topography of the Norovirus capsid. VLPs preserve the authentic confirmation of the viral capsid protein while lacking the infectious genetic material. Consequently, VLPs mimic the functional interactions of the virus with cellular receptors, thereby eliciting an appropriate host immune response while lacking the ability to reproduce or cause infection. In conjunction with the NIH, Baylor College of Medicine studied the humoral, mucosal and cellular immune responses to NV VLPs in human volunteers in an academic, investigator-sponsored Phase I clinical trial. Orally administered VLPs were safe and immunogenic in healthy adults (Ball et al. 1999; Tacket et al. 2003). At other academic centers, preclinical experiments in animal models have demonstrated enhancement of immune responses to VLPs when administered intranasally with bacterial exotoxin adjuvants (Guerrero et al. 2001; Nicollier-Jamot et al. 2004; Periwal et al. 2003). Collectively, these data suggest that a vaccine consisting of properly formulated VLPs represents a viable strategy to immunize against Norovirus infection.


1. Field of the Invention
The present invention generally relates to a control circuit for a DC motor driving circuit. In particular, the invention is concerned with a control circuit for ensuring safety in operation of an H-bridge circuit employed for driving and controlling a DC (Direct Current) motor, and more particularly a control circuit which is capable of preventing occurrence of a through-current flow upon turning on/off of switching elements constituting the H-bridge circuit.
2. Description of the Related Art
For better understanding of the present invention, description will first be made in some detail of the background technique. FIG. 6 is a block diagram showing a hitherto known DC motor driving circuit which includes an H-bridge switching circuit for driving and controlling a DC motor, FIG. 7 is a circuit diagram showing a predriver circuit serving as a control circuit for driving and controlling the H-bridge switching circuit shown in FIG. 6, and FIG. 8 is a circuit diagram showing in detail a major portion of the predriver circuit shown in FIG. 6.
Referring to FIG. 6, a DC motor 1 is electrically connected in the form of an H-bridge circuit together with four switching elements 3a, 3b, 3c and 3d which serve for controlling the rotation speed of the DC motor 1 by controlling the duty cycle of a pulse current supplied to the DC motor 1 as well as for reversing the direction of rotation of the DC motor 1 by changing the flow direction of the current supplied to the motor 1.
As can be seen, the first and second switching elements 3a and 3b are connected to a power supply source V.sub.B, while the third and fourth switching elements 3c and 3d are connected to the ground potential. The DC motor 1 has one terminal connected to the junction between the first and third switching elements 3a and 3c and the other terminal connected to the junction between the second and fourth switching elements 3b and 3d. Further, the switching elements 3a, 3b, 3c and 3d have electrodes connected to output terminals of driving circuits 5a, 5b, 5c and 5d, respectively, which in turn have input terminals connected to a control unit 9 constituted by a computer or the like via a predriver circuit 7 which also serves as a control circuit for controlling the driving circuits 5a to 5d under the command of the control unit 9.
FIG. 7 shows a circuit configuration of the driving circuit 5a and the first switching element 3a, being understood that the other driving circuits 5b to 5d and the switching elements 3b to 3d are also implemented in substantially equivalent configurations, respectively. As can be seen in the figure, the first switching element 3a is constituted by an N-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor), while the switch driving circuit 5a is constituted by an emitter-grounded transistor 51 having a base connected to a corresponding output terminal of the predriver circuit 7 and a collector connected to the power supply source V.sub.B via a resistor 52, a transistor 53 having a base connected to the collector of the transistor 51, an emitter connected to the ground potential similarly to the transistor 51 and a collector connected to the power supply source V.sub.B via a resistor 54, and a transistor 55 having a base connected to a junction between a resistor 54 and the collector of the transistor 53, an emitter connected to an input terminal of the first switching element 3a and additionally connected to the collector of the transistor 53 via a diode 56 and a collector connected to the power supply source V.sub.B. The configurations and connection mentioned above apply similarly to the other switching elements 3b, 3c and 3d and the other switch driving circuits 5b, 5c and 5d, as mentioned above.
In operation, when the output of the predriver circuit 7 is at a low level, the transistor 51 is in the non-conducting state (OFF) with the transistor 53 conducting (ON), as a result of which the output level of the output transistor 55 is low. Consequently, the switching element 3a (3b, 3c or 3d) is in the non-conducting or OFF-state. On the other hand, when the output of the predriver circuit 7 becomes high, the transistor 51 is turned on while the transistor 53 is turned off, which results in that the output transistor 55 is turned off. Consequently, a high level output of the transistor 55 is applied to the switching input terminal of the switching element 3a (3b, 3c or 3d) which is thus turned on.
By combining appropriately the ON/OFF operations of the switching elements 3a, 3b, 3c and 3d, each controlled in the manner described above, speed control, reversing of rotational direction of the DC motor 1 as well as braking and stoppage thereof can be realized with the current supply to the DC motor 1 being correspondingly controlled.
More specifically, referring to FIG. 6, when the first and fourth switching elements 3a and 3d are in the OFF-state, a current flows from the power supply source V.sub.B to the ground by way of the second switching element 3b, the DC motor 1 and the third switching element 3c, whereby the DC motor 1 is caused to rotate in a forward direction.
On the other hand, when the first and fourth switching elements 3a and 3d are turned on with the second and third switching elements 3b and 3c being off, a current flows from the power supply source V.sub.B to the ground via the first switching element 3a, the DC motor 1 and the fourth switching element 3d, causing the DC motor 1 to rotate in the backward or reverse direction.
Further, when the first and second switching elements 3a and 3b are turned on with the third and fourth switching element 3c and 3d being turned off, both ends of the DC motor 1 are electrically coupled through the first and second switching elements 3a and 3b, whereby the DC motor 1 is braked. Furthermore, when the first to fourth switching elements 3a to 3d are all turned off, the DC motor 1 is caused to stop. Parenthetically, in practical applications, the second and third switching elements 3b and 3c are mutually interlocked to be turned on and off in combination.
In the switching circuit composed of the switching elements 3a, 3b, 3c and 3d connected in the H-bridge form as described above, a short-circuit fault may take place between the power supply source V.sub.B and the ground if the first and third switching elements 3a and 3c or the second and fourth switching elements 3b and 3d should simultaneously be turned on, which may occur in dependence on erroneous timing at which operations of these switching elements are changed over. Such being the circumstances, the predriver circuit 7 is provided and dedicated to the control of the switching elements 3a, 3b, 3c and 3d with a view to preventing the occurrence of such short-circuit fault.
Description will now turn to the predriver circuit 7. FIG. 8 is a circuit diagram showing an exemplary configuration of a predriver circuit known heretofore. As can be seen in the figure, the predriver circuit 7 includes first to third input terminals 70a, 70b and 70c and four NOR circuits 71a, 71b, 71c and 71d provided at the output side and connected to the switch driving circuits 5a, 5b, 5c and 5d, respectively, wherein the input sides of the four NOR circuits 71a, 71b, 71c and 71d are connected in such a manner as illustrated in FIG. 8.
More specifically, the first input terminal 70a is connected to one input terminal of the first and fourth NOR circuits 71a and 71d, respectively, via an amplifier 72a and at the same time connected to one input terminal of the second NOR circuit 71b via an inverter 73a. On the other hand, the second input terminal 70b is connected to another one of the input terminals of the second NOR circuit 71b and one of the input terminals of the third NOR circuit 71c, respectively, and additionally connected to another input terminal of the first NOR circuit 71a via an inverter 73b.
Further, the first to third terminals 70a, 70b and 70c are connected to input terminals of a flip-flop circuit 74 via amplifiers 72a, 72b and 72c and inverters 73a, 73b and 73c, respectively, wherein output terminals of the flip-flop circuits 74 are connected to other input terminals of the third and fourth NOR circuits 71c and 71d, respectively.
Additionally, the first and second input terminals 70a and 70b are connected to input terminals of a delay circuit 75 via the amplifiers 72a and 72b and the inverters 73a and 73b, respectively, wherein output terminals of the delay circuit 75 are connected to the other input terminals of the first to fourth NOR circuits 71a, 71b, 71c and 71d via inverters 76a, 76b, 76c and 76d, respectively,
The delay circuit 75 is comprised of four series connections, each of which includes a transistor 10, a constant current circuitry 11 and a capacitor 12 connected in parallel to the transistor 10, wherein the four series connections are connected in parallel with one another. In response to the state change (i.e., from ON-state to OFF-state or from OFF-state to ON-state) of the input signal supplied from the control unit 9 to the first and second input terminals 70a and 70b of the predriver circuit 7, the output levels of the NOR circuits 71a, 71b, 71c and 71d constituting the output stage of the predriver circuit 7 are caused to change, whereby the switching elements 3a, 3b, 3c and 3d are correspondingly turned on and off. In that case, the delay circuit 75 serves to delay the operations of the switching elements 3a, 3b, 3c and 3d such that the first and third switching elements 3a and 3c or the second and fourth switching elements 3b and 3d are positively prevented from being simultaneously turned on for the purpose of excluding the short-circuit fault mentioned hereinbefore. As a consequence, when the operating state of the DC motor 1 is to be changed over, the power supply to the DC motor 1 is temporarily or transiently cut off.
FIG. 9 shows signal waveforms at various circuit points in the predriver circuit 7 shown in FIG. 8 for illustrating operation thereof on the assumption that operation state of the DC motor 1 is changed over in the sequence of stop, forward rotation, braking, backward (reverse) rotation, braking, forward rotation and backward rotation in this order. More specifically, in FIG. 9, waveforms S1 to S3 illustrate changes in the output signals (control signals) of the control unit 9 which are applied to the first to third input terminals 70b, 70a and 70c, respectively, of the predriver circuit 7, while A to H represent signal waveforms at circuit points A to H shown in FIG. 8, respectively. Further, waveforms S5a to S5d represent output signals supplied from the first to fourth NOR circuits 71a, 71b, 71c and 71d to the first to fourth switch driving circuits 5a, 5b, 5c and 5d respectively.
The period during which the electric power supply to the DC motor 1 is cut off is referred to as the dead time. Usually, this dead time is optimally selected in dependence on the type of the DC motor 1, the switching elements 3a, 3b, 3c and 3d and other elements employed actually. With the circuit arrangement shown in FIG. 8, the dead time may be selectively determined by varying the capacity of the capacitor 12.
In the predriver circuit 7 for the switching elements 3a, 3b, 3c and 3d which constitute the H-bridge switching circuit known heretofore, at least two capacitors 12 (four capacitors in the case of the illustrated example) are required to be incorporated in the delay circuit 75 for preventing the short-circuit fault from occurring in the H-bridge switching circuit. In this conjunction, it is noted that when the predriver circuit 7 is to be implemented in the form of an integrated circuit, the capacitors 12 will have to be provided externally so that the individual capacitances can be adjusted by exchanging the capacitors in conformance with the switching elements used in the H-bridge circuit as well as the DC motor. In that case, the number of terminals of the integrated circuit for electrical connection of the capacitors 12 will necessarily be increased in dependence on the number of the capacitors to be externally attached, which provides a great obstacle to miniaturization of the integrated predriver circuit. Needless to say, increase in the number of circuit elements involves a problem that high operation reliability of the whole circuit can not be ensured.


Commercial hardening techniques for ferrous metal components typically involve the steps of heating the components in a furnace or a bath of molten salt, such as a chloride, quenching the components in a bath of another molten salt such as a nitrate, nitrite, or mixture thereof, and thereafter causing the parts to be passed through one or more rinse baths to clean off salts which cling to the parts as a result of the heating and quenching steps. A certain amount of each of the molten salts is transferred by drag-out to the rinse bath, thus requiring occasional replenishment of the molten salts, as well as replacement of the rinse water.
It is desirable to recover the salts from the rinse water and return them to the heat treating baths. However, a number of problems have heretofore prevented such recycling on a straightforward and economical basis. First, it is difficult to justify economically the installation of recovery apparatus unless the quantities of reclaimed salts are very high, and the recovery process can be carried out without shut-down of the heat treating system. Secondly, it has been found that the impurities which typically find their way into heat treating baths tend to build up to unacceptable levels particularly fast when the salts are recovered from the rinse and recycled into the heat treat bath. For example, chloride salts from a heating bath are dragged into the quench bath and thence into the rinse where recycling tends to return them to the quench bath. Recycled chloride impurities quickly reach insolubility levels in the quench, and crystallize out as a sludge which must be removed from time to time. In addition, chloride tends to substantially reduce the quench efficiency of a nitrate/nitrite bath and, thus, removing the chlorides is highly desirable.
Another impurity which will build up quickly as a result of salt recycling is carbonate, a reaction product of decomposition of the salt itself. For example, a sodium nitrate/nitrite salt tends to form Na.sub.2 CO.sub.3, the carbon being taken out of the CO.sub.2 present in the air. The sodium carbonate is quite soluble in the rinse water but only sparingly soluble in the nitrate/nitrite quench bath and, thus forms a precipitate in the bath which impairs quenching efficiency and coats mechanical components in contact with the bath.
It should be understood that both the chloride and carbonate impurities, as well as many other impurities such as hard water ions, are typically present in the heat treating salt baths of prior art systems. However, the levels of concentration of such impurities are kept reasonably and acceptably low for longer periods of use by reason of the fact that impurities as well as desirable salts are continuously lost by drag-out. Lost salt, of course, is replaced by fresh salt which does not contain the impurities. Where salt is recycled, however, undesirable impurities dragged into the rinse and which are soluble in the rinse water are retained in the recycled materials and, after a short time, reach unacceptable concentrations.


In web offset printing, a desired image is repeatedly printed on a continuous web or substrate such as paper. In a typical printing process, the continuous web is slit in the longitudinal direction (the direction of web movement) to produce a plurality of continuous ribbons. The ribbons are aligned one on top of the other, folded longitudinally, and cut laterally to produce a plurality of multi-page, approximately page-length segments, each of which is termed a signature. The term signature also encompasses a single printed sheet that has or has not been folded. Because more than one different signature can be printed at one time, it is often desirable to separate the different signatures by transporting successive signatures in different directions or paths.
One way to accomplish the sorting of a single stream of signatures is to use a diverter mechanism, such as a diverter wedge, to divert successive signatures to one of two paths. Once diverted, the signatures typically are transferred to a conveyor using rotating buckets (also known in the art as fans, fan wheels, paddle fans, or rotary flywheels).
Typically, two sets of rotating buckets assemblies are utilized, one set to deliver signatures traveling along a first path to a first conveyor and the other set to deliver signatures traveling along the second path to a second conveyor. Each set of bucket assemblies includes several individual buckets arranged at a spaced distance from one another along a common axis or shaft. Each bucket has multiple aligned blades that define pockets or slots between them for receiving signatures and transferring the signatures to the respective conveyor.
It is desirable to increase the operating speed of a printing press in order to increase the printed product output. However, as the rotational speed of the buckets is increased, it is more difficult to ensure the reliable operation of the buckets and to ensure that signatures are not damaged. For example, signature quality problems that can occur at higher press speeds include ink offset, dog-eared edges, and defects to both the leading and trailing edges of the signatures. These and other defects can lead to paper jams in the folder, resulting in press downtime and expense.
When the signatures are not snugly held between guide belts, the signatures may flutter or, when the signatures are folded signatures, the signatures may open partially. Signature fluttering and/or opening can result in damage to the signatures in the folder. Signatures may also “free fall ” (i.e. travel without any belt guidance whatsoever) as they move through the folder, resulting in the potential for the signatures to flutter and/or opening.


1. Technical Field
The invention relates to a back-illuminated type imaging device in which light is illuminated from a back-surface side of a semiconductor substrate and charges that are generated in the semiconductor substrate in response to the light are read from a front-surface side of the semiconductor substrate to perform imaging.
2. Description of the Related Art
The following back-illuminated type imaging device has been proposed. That is, light is illuminated from a back-surface side of a semiconductor substrate. The back-illuminated type imaging device stores charges that are generated in the semiconductor substrate in response to the light, into charge storage areas formed on a front-surface side of the semiconductor substrate. The back-illuminated type imaging device outputs signals corresponding to the charges stored in the charge storage areas to the outside by a CCD or CMOS circuit formed on the front-surface side of the semiconductor substrate so as to perform imaging.
In order to absorb almost all of visible light, the semiconductor substrate (a photoelectric conversion area) the back-illuminated type imaging device, the semiconductor substrate (a photoelectric conversion area) is required to have a thickness of about 10 μm. For this reason, when the back-illuminated type imaging device is fabricated, at first structures such as the charge storage areas and the CCD are first formed on the front surface of the thick semiconductor substrate. Thereafter, a wiring layer is thereafter formed on the structures, and a supporting substrate is bonded thereto via an adhesive layer. Then, the semiconductor substrate is etched from the back-surface side until the thickness becomes 10 μm, for example. After the etching, structures such as color filters and microlenses are formed on the back surface of the semiconductor substrate so as to be aligned with the structures formed on the front-surface side of the semiconductor substrate.
In the back-illuminated type imaging device formed in such a manner, it is necessary to form a pad on the back-surface side or front-surface side of the semiconductor substrate so as to be connected to the wiring layer formed on the front-surface side of the semiconductor substrate. A general image sensor that is presently in wide use has such a structure that a pad opening is provided on a light incidence side. In accordance with this structure, test equipments for testing the functions of chips in the wafer are installed in a fabrication line. For this reason, if the pad opening is formed on the front-surface side of the semiconductor substrate in the back-illuminated type imaging device, it becomes necessary to drastically change or modify the test equipments, which may increase the fabrication cost.
Therefore, similarly to the general image sensor, various methods for providing the pad opening on the light incidence side (the back-surface side) have been proposed for the back-illuminated type imaging device. One method of them is to form a through hole from the back-surface side of the semiconductor substrate, thereby exposing from the back surface the pad connected to the wiring layer formed on the front-surface side (for example, see JP 2005-285814 A and JP 2006-19653 A). However, such a method has the following problems. That is, if the through hole is formed before the color filter or the microlens are formed on the back-surface side, a material for the color filter or the microlens may be left in the through hole and cannot be removed in subsequent steps. Or, since the substrate on which the material is to be deposited has a large step formed thereon, the thickness of the deposited material is not even, which may cause a fixed pattern noise that appears as oblique lines in an image. Moreover, even if the through hole is formed after the color filter or the microlens is formed, it is necessary to remove a photoresist that defines the through hole without causing any harm to the color filter or the microlens, which is very troublesome. In particular, as described above, in the semiconductor substrate having a thickness of 10 μm, the above problems may become conspicuous, and it becomes more difficult to perform such a removal work.
In light of the above, as disclosed in JP 2006-339566 A, the following method may be conceived. That is, a trench is formed in the semiconductor substrate so as to extend from the front surface of the semiconductor substrate to reach the back surface thereof; the trench is filled with a conductive material, and a pad is formed on the conductive material. It can be said that in principle, it is possible to fill the trench corresponding to the pad with the conductive material. However, usually, the pad has a size of 100 μm×100 μm; therefore, in order to form a trench having substantially the same size and fill the trench with conductive material, if a CVD process is used, it is necessary to form a layer of the conductive material to a thickness equal to or larger than 50 μm and then to remove the same thickness by an anisotropic etching process. Such a process step cannot be said to be practical as a semiconductor fabrication process.
If the size of the trench is decreased, it may not cause any problem in view of a fabrication process. However, in such a case, there arises a problem that the resistance of the conductive material filled in the trench may increase, which may affect the device characteristics.


1. Field of the Invention
This invention relates to an actuator unlocking apparatus and a method of releasing an actuator from magnetic attraction during power-on operation, in a disk storage apparatus. An actuator for moving a transducer head on a disk storage medium is locked by a magnetic locking apparatus to prevent the actuator and the disk storage medium from being damaged by unintentional movement of them when the disk storage apparatus is not powered. This invention relates to an improved method of and apparatus for releasing an actuator from magnetic locking apparatus at power-on operation.
2. Description of the Prior Art
In a disk storage apparatus, it is necessary to prevent an actuator (a voice coil motor (VCM), etc.) for moving a transducer head on a recording medium from moving due to external force and from damaging data on a recording surface and the actuator itself, by locking the actuator when the disk storage apparatus is not powered. In a small disk storage apparatus, the magnetic attraction of a permanent magnet is used to lock the actuator.
In this prior art configuration, owing to the magnetic attraction of -the permanent magnet, power is not consumed except when locking is released during a power-on operation. Further, in this configuration, the dimensions of the disk storage apparatus can be reduced because there is mechanically no movable part. Since the power of the actuator is used to unlock, a dedicated electric circuit for unlocking is not needed. Still further, in the configuration, component parts are merely the permanent magnet and its attaching members. Therefore, the configuration is generally adopted because of the advantage that the number of parts is small and a cost can be reduced. The present invention relates to an unlocking apparatus and method of a disk storage apparatus which unlocks an actuator from the permanent magnet.
In prior art, in order to release the actuator from the permanent magnet, positional information (servo information) written between a zone where the actuator is locked (parking zone) and a zone where data is recorded (data zone) on a disk recording medium is used and a seek operation is used for releasing. That is, during a releasing operation, a position of the actuator is detected by reading the positional information and the current which is supplied to the actuator is controlled. The actuator is surely released from the permanent magnet and moved to the data zone. The situation in which the releasing cannot be completed because of insufficient movement or in which the actuator collides with a crash stop due to the excess movement of the actuator is avoided by reading positional information on the disk.
However, the servo information written between the parking zone and the data zone on the disk medium may disappear due to the friction between the transducer head and the disk medium if the actuator is locked and released many times, because the parking zone is a zone on which the transducer head attached to the actuator slides when the rotational rate of the disk is below a predetermined value (contact start and stop). Once the servo information is lost, releasing cannot be completed because the positional information for the releasing cannot be obtained any more. In the prior art, there is therefore a problem in terms of reliability.


Conventional computer equipment and, in particular networking equipment, employ air deflectors to direct and/or deflect the generated or exhausted warm air away from the equipment (e.g., in an upwards direction due to the natural flow of heated air). Some equipment manufacturers offer air deflectors that are specific to a certain model of equipment (i.e., specific to the dimensions of the equipment and/or placement of the exhaust system) and are fastened to the equipment itself. However, not all equipment manufacturers offer an air deflector associated with their products. Generally, when air deflectors are not included with equipment, generic air deflectors (e.g., curved plastic) may be used that attach to the equipment via a magnetic coupler and/or mechanism. Such a magnetic coupler can add an undesirable magnetic field near the equipment to which it is attached. Additionally, the magnetic coupler not have sufficient magnetism to keep the air deflector attached to the equipment while enduring the force of the air exhaust. Additionally, since many data center aisles are rather narrow, magnetically coupled air deflectors jutting into the aisle are easy to dislodge if bumped.
It is with these issues in mind, among others, that various aspects of the present disclosure were conceived.


Methods for electroplating articles with metal coatings generally involve passing a current between two electrodes in a plating solution where one of the electrodes is the article to be plated. A typical acid copper plating solution includes dissolved copper, usually copper sulfate, an acid electrolyte such as sulfuric acid in an amount sufficient to impart conductivity to the bath, a source of halide, and proprietary additives to improve the uniformity of the plating and the quality of the metal deposit. Such additives include levelers, accelerators and suppressors, among others.
Electrolytic copper plating solutions are used in a variety of industrial applications, such as decorative and anticorrosion coatings, as well as in the electronics industry, particularly for the fabrication of printed circuit boards and semiconductors. For circuit board fabrication, typically, copper is electroplated over selected portions of the surface of a printed circuit board, into blind vias and trenches and on the walls of through-holes passing between the surfaces of the circuit board base material. The exposed surfaces of blind vias, trenches and through-holes, i.e. the walls and the floor, are first made conductive, such as by electroless metallization, before copper is electroplated on surfaces of these apertures. Plated through-holes provide a conductive pathway from one board surface to the other. Vias and trenches provide conductive pathways between circuit board inner layers. For semiconductor fabrication, copper is electroplated over a surface of a wafer containing a variety of features such as vias, trenches or combinations thereof. The vias and trenches are metallized to provide conductivity between various layers of the semiconductor device.
It is well known in certain areas of plating, such as in electroplating of printed circuit boards (“PCBs”), that the use of levelers in the electroplating bath can be crucial in achieving a uniform metal deposit on a substrate surface. Electroplating a substrate having irregular topography can pose difficulties. During electroplating a voltage drop typically occurs within apertures in a surface, which can result in an uneven metal deposit between the surface and the apertures. Electroplating irregularities are exacerbated where the voltage drop is relatively extreme, that is, where the apertures are narrow and tall. Consequently, depositing a metal layer of substantially uniform thickness is frequently a challenging step in the manufacture of electronic devices. Leveling agents are often used in copper plating baths to provide substantially uniform, or level, copper layers in electronic devices.
The trend of portability combined with increased functionality of electronic devices has driven the miniaturization of PCBs. Conventional multilayer PCBs with through-hole interconnects are not always a practical solution. Alternative approaches for high density interconnects have been developed, such as sequential build up technologies, which utilize blind vias. One of the objectives in processes that use blind vias is the maximizing of via filling while minimizing thickness variation in the copper deposit between the vias and the substrate surface. This is particularly challenging when the PCB contains both through-holes and blind vias.
Leveling agents are used in copper plating baths to level the deposit across the substrate surface and to improve the throwing power of the electroplating bath. Throwing power is defined as the ratio of the through-hole center copper deposit thickness to its thickness at the surface. Newer PCBs are being manufactured that contain both through-holes and blind vias. Current bath additives, in particular current leveling agents, do not always provide level copper deposits between the substrate surface and filled through-holes and blind vias. Via fill is characterized by the difference in height between the copper in the filled via and the surface.
Another problem encountered in copper plating is the formation of nodules on the copper deposit. Nodules are believed to be crystals of the metal being plated and grow out of the plated surface. Nodules may range in diameter from less than 1 micron to as large as several millimeters. Nodules are undesirable for a variety of electrical, mechanical, and cosmetic reasons. For example, nodules are readily detached and carried by cooling air flows into electronic assemblies, both within and external to electronic article housings, where they may cause short-circuit failure. Therefore, the nodules have to be removed before the plated substrates are assembled into electronic articles. Conventional methods of removing the nodules involve laser inspection of each copper plated substrate followed by manual removal of the nodules by workers using microscopes. Such conventional methods leave room for worker error and are inefficient.
Accordingly, there remains a need in the art for leveling agents for use in copper electroplating baths for the manufacture of PCBs that provide level copper deposits while bolstering the throwing power of the bath and reducing nodules.


1. Field of the Invention
The present invention relates to a dispensing apparatus and more particular to a dispensing apparatus having a dispensing assembly and a slidable locking cap for restraining the dispensing assembly in a closed position.
2Description of the Related Art
Dispensing devices, especially those for lawn care products such as a combination of lawn fertilizer and weed control, are known, as exemplified by U.S. Pat. No. 5,996,858. Lawn products are often particulate or granular, but may be liquid, and these are spread by a consumer holding the device in an open condition while walking at a prescribed rate along a predetermined path. These devices have rotatable spouts fitted to a plastic molded container having an integral handle. Some have covers, other breakaway tabs and some have both.
The lawn product must be handled in a recommended manner and the dispensing devices ought to be tightly closed and kept in a safe place. Cost, ease of use and reliable structure are also of concern when designing such dispensing devices.


Wireless Body Sensor Nodes (WBSNs) are miniaturized, wearable systems able to measure and wirelessly transmit biological signals of patients. A major field of application of WBSNs is the ambulatory acquisition of electrocardiograms (ECGs), which evaluates the electrical activity of the heart. In this context, these devices allow long time monitoring of subjects producing little discomfort and requiring minimal medical supervision.
A recent trend in WBSNs, driven by the progress in semiconductor technologies, has been the emergence of “smart” wireless nodes [1]. These smart WBSNs (FIG. 1) can, in addition to acquiring and transmitting data wirelessly, perform advanced digital signal processing filtering noise typically corrupting the signals and/or executing an automated diagnosis.
In the field of ambulatory electrocardiography, an important early diagnosis step is to separate normal and pathological heartbeats. The benefit of this separation is two-fold: first, it can provide helpful information for speeding up the visual inspections of lengthy recordings by medical staff; second, it can be used to activate a more detailed analysis of only those beats presenting pathological characteristics.
The second scenario can lead to two non-obvious, yet substantial, benefits. On the one hand, if a detailed diagnosis is performed off-node, it can be desirable to transmit or store only pathological beats on the WBSN, greatly reducing either the energy employed for wireless transmission or the data storage requirements, respectively. On the other hand, even if the analysis of beats is executed on the wireless node, computation effort can be reduced by activating it only when abnormal beats are detected, increasing energy efficiency.
While off-line algorithms have been proposed to classify the different heartbeat morphologies [2][3], their real-time implementation poses a considerable challenge on WBSN platforms, due to their high computational requirements.
A neuro-fuzzy classifier (NFC) approach [4] is instead potentially a good candidate for this application. Its simple feed-forward structure makes it eligible to be optimized for, and executed on, the constrained resources typically present on WBSNs.
An important factor to consider is the high dimensionality of the heartbeat representation problem as, for every beat, tens of samples before and after the R peak of the QRS complex peak have to be considered to perform a reliable classification.
To effectively address this problem, in the method according to the invention enables to classify ECG beats using a method based on random projections (RPs) that can lead to reduction in input size. The approximation error introduced by random projections is theoretically bounded, nonetheless empirical evidence shows that certain projections perform better than others. Our experiments show that even a rather simple optimization, such as the one performed by a genetic algorithm in few generations, can find a proper projection to obtain optimal classification results. In one embodiment of the invention, the method includes the RP-classifier, a filtering stage and a peak detector, used to isolate beats. In one embodiment, three-lead delineation is used instead adopted as an example of detailed analysis, and is activated by the classifier only for beats identified as pathological.
Test heartbeats were retrieved from the MIT-BIH Arrhythmia database [5], considering all beats presenting three different morphologies: normal sinus rhythms, left bundle branch blocks and premature ventricular contractions. Experimental results show that the proposed methodology can identify more than 97% of abnormal beats, while using a small fraction of the available SoC memory and computing resources.
Neuro-fuzzy classifiers (NFCs) [6] have been extensively studied in the literature. Their ability to explicitly express uncertainty in classification, given by the employed fuzzy values, makes them particularly well suited to the problem of heartbeat classification, as proposed in [7].
NFCs can be effectively trained using established methods, the most common being the gradient descent algorithm described in [6] and the scale conjugate gradient introduced in [8] and [9], which is employed in this work. The approach is both computationally simpler and presenting lower memory requirements than comparable methods, like the ones based on support vector machines [2] and linear discriminants [10]. Therefore, it is more suitable for execution in embedded WBSNs.
Several state-of-the-art strategies for neuro-fuzzy classification of ECGs can be distinguished based on the methodology employed to extract the features of individual heartbeats generating the classifier input. Solutions to the features extraction problem include the ones based on Independent or Principal component analysis (ICA [11]/PCA, [3]), Discrete Wavelets Transform (DWT [12]) and Discrete Cosine Transform (DCT [4]). As opposed to the method disclosed in this invention, these methods demand a computation effort not compatible with WBSN resources.
A different approach, based on detection of morphological features, is presented in [13]; it nevertheless requires a detailed analysis of heartbeats before classification, conversely to our goal of early identification of pathological beats.


Fabric care, particularly cleaning, can be divided into two basic theoretical approaches, namely, water-based cleaning or dry/powder cleaning. Dry cleaning can be perceived by customers as raising certain concerns regarding solvent residue and volatile organic content (VOC), however, water-based cleaning also has disadvantages.
For one example, in a conventional water cleaning process, significant amounts of clean water are required for both washing and rinsing cycles. Typically, the weight ratio of consumed water to fabric is around 12:1 to 20:1. As can be appreciated, this is a challenge for clean water supply infrastructure, especially those facing water shortage issues. Moreover, many forecast water-saving as a mega-trend in sustainability. Accordingly, consumers desire to conserve water is likely to increase over time.
Thus, it is desirable to provide a fabric care composition that achieves excellent washing performance with water, whilst requiring less water than conventional water-based cleaning processes. It is also desirable to provide an efficient and environmentally friendly cleaning method compared to conventional cleaning processes.


1. Field of the Invention
The proposed invention relates to the field of pipeline transportation of liquid hydrocarbons, in particular to methods for decreasing their hydrodynamic resistance or method of drag reduction.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
Recently, polymeric anti-turbulent additives (ATAs) or polymeric drag reducing additives (DRAs) are used for increasing capacity of oil and products pipelines. They represent a polymer solution or a polymer suspension in a liquid medium. A polymer should be soluble in a transported liquid and have a high molecular weight. Another pre-requisite for the effect of drag reduction (Toms Effect) is the turbulent mode of a hydrocarbon liquid flowing in a pipeline.
The introduction of a DRA into a crude oil flow in an amount from 10 to 50 grams per one ton results in increasing the pipeline capacity for 15-25%. The higher a polymer molecular weight, the lower is its concentration that is required for achieving said value of drag reduction.
Ultra-high molecular (co)polymers of higher α-olefins, which are synthesized on Ziegler-Natta catalysts, are most commonly used as a polymeric component of DRA. As to their price-quality relation, they have no match among other oil-soluble polymers. Monomers having from 6 to 16 carbon atoms are used.
Initially, DRAs were produced as a polymer solution in gasoline (kerosene). However, injection-related problems due to its high viscosity, especially in winter, caused the present use of suspension-type DRAs. A suspension is produced, as a rule, by comminuting a product of block-polymerization of higher α-olefins, which is a rubber-like material, at a temperature below its glass-transition point, and thus-obtained polymer particles are mixed with a liquid medium that does not dissolve the polymer. The liquid medium is selected so that its density does not greatly differ from that of the polymer, in order to avoid irreversible suspension layering during storage. The polymer content of a suspension-type DRA may be up to 25% and even more, which exceeds the polymer content of a solution-type additive greatly. The DRA solid phase may comprise surfactants or other anti-agglomerator agents that prevent polymer particles from agglomerating as well as additives for inhibiting polymer oxidative destruction.
Polymerization in a solution medium has been replaced by block polymerization also from the point of a polymer molecular weight that is significantly higher at block polymerization; consequently, a polymer thus produced is of higher quality.
The conventional technology of a suspension agent for decreasing hydrodynamic resistance may be divided into three steps:
1. Block polymerization of a monomer (co-monomers)
2. Comminution of a rubber-like co-polymer
3. Production of a suspension stable against layering (sedimentation)
Many patents relating to methods of producing suspension-type DRAs describe cryogenic comminution of polymers (U.S. Pat. No. 4,826,728, U.S. Pat. No. 4,720,397, U.S. Pat. No. 4,340,076). Since polymers and co-polymers of higher α-olefins are rubber-like materials with low glass-transition temperatures (for example, poly-1-octene has glass-transition temperature below −70° C.), their mechanical comminution is carried out in the liquid nitrogen medium, i.e. below their glass-transition temperatures.
It is well known, however, that operations employing liquefied gases are associated with higher risks and require special expensive equipment as well as certain safety measures for personnel. Furthermore, liquid nitrogen itself is an expensive material. Therefore, recently many companies started to work on creating non-cryogenic technologies of comminuting polyalphaolefins (U.S. Pat. No. 6,946,500, U.S. Pat. No. 6,894,088, U.S. Pat. No. 7,271,205, US Patent Application No. 0276566, US Patent Application No. 0287568). Preliminary impregnation with moistening agents is used for which purpose heavy alcohols, solid and liquid separating agents (derivatives of stearic acid, higher linear alcohols) as well as special equipment (homogenizers, abrasive mills, rotor-stator type grinders) are applied.
Here, it should be noted that a suspension-type additive must comprise a finely comminuted polymer, or the process of dissolving the polymer in an oil pipeline will be too long, which affects the resulting efficiency of a DRA. On the other hand, mechanical comminution of polymers, especially fine comminution to particles having a size of 100-300 microns, leads to partial mechanical destruction of macro molecules and poorer quality of the polymer.
Mechanical destruction can be avoided by, for example, capsulated polymerization of higher α-olefins (U.S. Pat. No. 6,126,872, U.S. Pat. No. 6,160,036, U.S. Pat. No. 4,693,321, US Patent Application No. 20030013783). It consists in that catalyst-comprising monomer droplets are enclosed in a polymeric coating and suspended in a medium that does not dissolve any capsulated component. Micro-block polymerization is carried out in this way, and a dispersed polymer is produced in one step in the synthesis process. A significant disadvantage is low productivity of this process.
An alternative method for producing fine dispersions, which does not affect the length of a polymer molecule, consists in precipitating a polymer from a solution by adding a precipitating agent (U.S. Pat. No. 5,733,953). This method is the closest one to the present invention and is taken as a prototype.
Said method consists in that a polymer is precipitated, which has a high molecular weight and is synthesized by co-polymerization of higher α-olefins with a Ziegler-Natta catalyst in a solvent medium.
The sequence of producing such a suspension is as follows (a citation): “a low-viscosity highly concentrated polymer suspension is produced by slowly adding a liquid not dissolving a polymer (e.g., isopropyl alcohol) to a polymer solution in a solvent (e.g., kerosene). When a non-solvent is added in a sufficient quantity, a polymer precipitates from the solution in the form of small particles. A liquid is separated from the precipitate, the latter is once again washed with the non-solvent. The resulting concentrated suspension, when introduced into a flow of a hydrocarbon liquid, dissolves quickly and causes a decrease in hydrodynamic resistance.”
The prototype disadvantages are:                Poor quality of the polymer component        Necessity of regenerating a big volume of solvents        Pollution of the environment.


Although humans are extremely good at classifying gender from facial images, experiments have shown that most people have difficulty in classify gender from images were the faces are hairless. Furthermore, error rates in gender classification using low resolution facial images increases almost ten fold.
It would represent a major commercial advantage if computers could have reliable vision capabilities for classifying a person's gender, particularly from low resolution images. Although gender classification has been investigated from both a psychological and computational perspective, relatively few learning based vision methods are known for gender classification.
Golomb et al. in “SEXNET: A neural network identifies sex from human faces,” Advances in Neural Information Processing Systems, pp. 572–577, 1991, described a fully connected two-layer neural network to identify gender from human face images consisting of 30×30 pixel images.
Cottrell et al. in “Empath: Face, emotion, and gender recognition using holons,” Advances in Neural Information Processing Systems, pp. 564–571, 1991 also applied neural networks for face emotion and gender recognition. They reduced the dimensionality of a set of 4096×4096 images to 40×40 via an auto-encoder network. Those vectors were then given as inputs to another one layer network for training and recognition.
Brunelli et al, in “HyperBF networks for gender classification,” Proceedings of the DARPA Image Under-standing Workshop, pp. 311–314, 1992 developed HyperBF networks for gender classification in which two competing RBF networks, one for male and the other one for female, were trained using sixteen geometric features, e.g., pupil to eyebrow separation, eyebrow thickness, and nose width, as inputs.
Instead of using a raster scan vector of gray levels to represent face images, Wiskott et al. in “Face recognition and gender determination,” Proceedings of the International Workshop on Automatic Face and Gesture Recognition, pp. 92–97, 1995 described a system that used labeled graphs of two-dimensional views to describe faces. The nodes were labeled with jets which are a special class of local templates computed on the basis of wavelet transform, and the edges were labeled with distance vectors. They used a small set of controlled model graphs of males and females to encode the general face knowledge.
More recently, Gutta et al. in “Gender and ethnic classification of Face Images,” Proceedings of the IEEE International Automatic Face and Gesture Recognition, pp. 194–199, 1998 proposed a hybrid method which consists of ensemble of neural networks (RBFs) and inductive decision trees.
Using computer vision to determine the gender of subject faces can be used in various application areas, such as the gathering of population gender-statistics from patrons at entertainment/amusement/sports parks. Gender classification can also be used by television network viewer-rating studies. Gender specific computer vision can further have application in such fields as automated security/surveillance systems, demographic studies, safety monitoring systems, and human interfaces to computers.


Ion implantation is an important process in semiconductor/microelectronic manufacturing. The ion implantation process is used in integrated circuit fabrication to introduce controlled amounts of dopant ions into semiconductor wafers. An ion-source is used to generate a well-defined ion beam for a variety of ion species from a dopant gas. Ionization of the dopant gas generates the ion species which can be subsequently implanted into a given workpiece.
Carbon has emerged as a widely used dopant in the semiconductor industry for a variety of material modification applications such as inhibiting diffusion of co-dopants or enhancing stability of the doped region. In this regard, carbon dioxide (CO2) and carbon monoxide (CO) are two commonly used dopant gas sources for carbon implantation. However, CO2 and CO are prone to accumulation of deposits along surfaces of the ion chamber. Additional deposits can form along surfaces of electrodes of the ion source apparatus. The deposits may form directly from the dopant gas or from interaction of the dopant gas and/or its ionization product with the chamber components.
Such deposit formation is problematic. Deposits along surfaces of the electrodes of an ion implantation system create conditions susceptible to energetic high voltage discharge. Voltage discharge results in momentary drops in the beam current, commonly referred to as “beam glitching”. Deposits on the extraction aperture degrade the beam uniformity and hence the uniformity of dopant levels in the doped region. Beam uniformity and the number of beam glitches (i.e., glitch rate) during the operation of an ion source can be key metrics for the performance of an ion implantation system, such as, for example, a ribbon beam ion implantation system as commonly known in the art.
Based on the process sensitivity, there may be an upper threshold to the glitch rate and/or beam non-uniformity beyond which the implant process cannot operate with acceptable efficiency. In the event the ion source performance degrades beyond the upper threshold, the user must stop the implant operation and perform maintenance or replace the ion source. Such downtime results in productivity loss of the ion implantation system. Hence, it is desirable to maintain proper functioning of the ion source for extended periods of time in order to perform an efficient implant process.
As will be discussed, among other advantages of the present invention, an improved method and system for minimizing deposits and beam glitching during an ion implantation process is desired.


Often components need to have coupling male and female matched pairs. The invention described herein comprises a rigidizing latch assembly (“LAR”) which, in embodiments, is a robotically compatible aerospace attachment mechanism designed to rigidly attach avionics boxes or any orbital replaceable unit to the structure of a vehicle or other structure.
However, its use is not limited to aerospace or to a male/female pair which must be robotically maneuvered.


Portable electronic devices and tokens have become an integrated part of the regular day to day user experience. There is a wide variety of common portable and handheld devices that users have in their possession including communication, business and entertaining devices such as cell phones, music players, digital cameras, smart cards, memory token and variety of possible combinations of the aforementioned devices and tokens. All of these devices share the commonality that consumer are accustomed to carrying them with them most of the time and to most places. This is true across the various demographics and age groups regardless of the level of the sophistication of the consumer, their age group, their technical level or background.
These common handheld devices offer options for expandable memory. Micro Secure Digital (microSD) is the popular interface across high-end cellphones while SD and MultiMediaCard (MMC) interfaces are also available in limited models. MicroSD is the least common denominator supported by the majority of these devices and tokens (in terms of size). In addition, adaptors are available to convert a MicroSD into MiniSD, SD, MMC and USB Although most popular MP3 player (iPOD) offer's a proprietary interface, competing designs do offer standard interfaces. Digital cameras offer mostly SD and MMC while extreme Digital (xD) is another option. Micro and Mini versions of these interfaces are also available in several models. Mini-USB is increasingly available across cellphones, digital cameras and MP3 players for synchronization with laptops.


The present invention relates generally to a novel technique for limiting the accumulation of surface charge on a sample which is being bombarded by a primary beam and from which charged particles are being extracted. More particularly, the present invention relates to a method and apparatus for preventing the accumulation of surface charge beyond a predetermined limit by alternating during successive periods the extraction from the bombarded surface of charge of opposite signs.
Surface analysis of a material sample by processes such as secondary ion mass spectrometry (SIMS), Auger electron spectroscopy (AES) or their equivalents involve bombarding a sample with a primary beam and removing charged particles from the sample.
Secondary ion mass spectrometry involves bombarding a sample material with a high energy primary beam of neutral and/or charged particles (positive or negative ions, atoms or molecules). These particles impact the surface of the sample causing the emission of secondary neutral and charged particles (e.g. electrons, positive and negative ions, atoms, and molecules) some of which are subsequently mass analyzed to determine the composition of the sample. Similarly, AES involves bombarding the surface of a sample with high energy electrons which then result in the emission of Auger electrons, which are then energy analyzed to provide information on the composition of the sample.
If the net flux of positive and negative charges, i.e. ions and electrons, entering and leaving the sample is not perfectly balanced the sample will tend to become charged. Sample charging can destroy primary beam characteristics, interfere with the extraction of charged particles, and shift the energy of the extracted charged particles, making analysis difficult or impossible.
In electrically conducting samples charge accumulation may be prevented by electrically grounding the sample. The ground assures that the net charge flux of the sample will always be zero and, consequently, no charge accumulation will occur. Preventing or limiting charge accumulation in electrically non-conducting or poorly conducting materials (such as polymers, ceramics, glasses, and biospecimens) presents a more difficult problem.
The charge cycles commonly encountered during SIMS analysis of an electrically nonconducting sample exemplify the conditions toward which the present invention is directed:
(a) The most common mode of SIMS analysis is to use a primary beam of positive ions which results in emission of secondary positive and negative ions and secondary electrons from the sample. For known materials, the positive primary beam creates fewer secondary positive ions than primary ions. Use of an electric field of negative potential to extract positive secondary ions consequently causes the sample to accumulate a positive charge. Use of an electric field of positive potential to extract negative secondary ions and electrons causes the sample to accumulate a positive charge at an even greater rate.
(b) A neutral primary beam for SIMS analysis causes charge accumulation at a rate that is significantly less than that of the positive primary beam, but the imbalance between positive ion and negative ion and electron production and extraction can still cause charge accumulation on the sample.
(c) A negative primary ion beam has been used for SIMS analysis to create positive and negative secondary ions. Extraction of positive secondary ions will cause the sample to accumulate negative charge. Charge accumulation on the sample due to extraction of negative secondary ions will depend upon the material and bombardment energy. The secondary negative charge yield under keV energy negative ion primary bombardment is greater than the charge flux of the primary beam for many materials. Extraction of negative particles will cause such materials to accumulate positive charge.
In the prior art, conducting grids and electron flooding have been used to reduce accumulation of positive charge in non-conducting samples during SIMS analysis.
U.S. Pat. No. 4,680,467 issued July 14, 1987, to Bryson III et. al. discloses the use of an electrically conductive grid comprised of intersecting wires or vanes positioned in closely spaced relationship to the surface of the sample for smoothing the gradients in the electrical potential in the region of the beam spot during electron spectroscopy. However, conducting grids are known to add a background signal to the mass spectrum of the sample. In addition, conducting grids have a high probability of introducing contaminants to the surface of the sample and may cause chemical changes in the surface of the sample.
U.S. Pat. No. 4,818,872 issued Apr. 4, 1989, to Parker et al. discloses an electron gun which floods the sample with low energy electrons neutralizing charge accumulation. Electron flood guns are effective in many cases but may damage the sample, particularly polymers. Electron stimulated desorption and resulting noise may also be caused by electron flood guns.
Therefore, in view of the above, it is an object of the present invention to provide an apparatus and method for maintaining a neutral surface potential for a sample of electrically nonconducting or poorly conducting material that is being analyzed by a method causing extraction of charged particles from the sample.
It is another object of the present invention to provide a non-intrusive apparatus and method for maintaining a neutral surface potential so that sample integrity is maintained.
A yet further object of this invention is to present a method for limiting surface charge accumulation within predetermined values.
It is another important object of this invention to present an apparatus and method which enables the near simultaneous collection of both positive and negative secondary ion spectra.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.


The present invention relates to thermally stable polycrystalline diamond compacts and more particularly to brazing such compacts to cemented carbide supports and to themselves.
Well known in the super abrasive art are compacts of polycrystalline abrasive particles typified by polycrystalline diamond and polycrystalline cubic boron nitride (CBN) compacts. Such compacts are represented by U.S. Pat. Nos. 3,745,623 and 3,608,818 with respect to polycrystalline diamond compacts and U.S. Pat. Nos. 3,767,371 and 3,743,489 with respect to polycrystalline CBN compacts. While such polycrystalline compacts represent a significant contribution to the art in many fields of use, thermal degradation at an elevated temperature, e.g. above about 700.degree. C., did limit their usefulness, especially in metal matrix bond applications. Thermal stability of such polycrystallline compacts was improved with the advent of thermally-stable porous self-bonded diamond and CBN compacts containing less than about 3 percent non-diamond phase, hereinafter termed "porous compacts". Compacts of this type are the subject of U.S. Pat. Nos. 4,224,380 and 4,288,248.
European Patent Publication No. 116,403 describes a thermally-stable diamond compact comprising a mass of diamond particles present in an amount of 80 to 90% by volume of the body and a second phase present in an amount of 10 to 20% by volume of the body, the mass of diamond particles contain substantially diamond-to-diamond bonding to form a coherent skeletal mass and the second phase containing nickel and silicon, the nickel being in the form of nickel and/or nickel silicide and the silicon being in the form of silicon, silicon carbide, and/or nickel silicide. British patent application No. 8508295 describes a thermally stable diamond compact comprising a mass of diamond particles present in an amount of 80 to 90% by volume of the compact and a second phase present in an amount of 10 to 20% by volume of the insert, the mass of diamond particles containing substantially diamond-to-diamond bonding to form a coherent skeletal mass and a second phase consisting essentially of silicon, the silicon being in the form of silicon and/or silicon carbide.
Diamond, synthetic or natural, is very difficult to wet, making the attachment of diamond to a variety of substrates difficult. Since porous compacts essentially are composed only of diamond, they are difficult to bond to cemented carbide supports, for example. In order to successfully bond porous compacts to cemented carbide supports, a bonding agent that is able to wet and/or adhere to both the diamond surface and the support is required. The bond between the diamond and carbide support must be sufficiently strong so as to provide a useful implement. Temperature conditions required to form the bond must be below those that cause graphitization of the diamond and/or damage to the carbide support system. The bonding agent also must be chemically and physically compatible during and after the bonding operation with both the porous diamond compact and carbide support.
The formation of a bond between porous compacts and carbide supports is inhibited by gaseous/liquid/solid films. The inhibiting films can be non-carbon material as well as adsorbed species including water vapor or oxygen. The inhibiting films, by preventing the wetting of the compact and/or carbide support by the bonding agent, reduces the strength of adhesion. Further, blocking of pores in the porous compact by impurities prevents penetration of the bonding agent into the core and reduces the ultimate bond strength.
A wide variety of bonding agents, or brazing alloys, have been proposed in the art. With respect to thermally stable diamond compacts, British Pat. No. 2,163,144 reognizes the difficulties encountered in brazing such compacts and, thus, proposes to bond a variety of thermally stable diamond compacts to carbide supports utilizing a silver or gold-based alloy containing between about 1 and 10 percent by weight of an active metal selected from the group of tungsten, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, and molybdenum. The alloy has a liquidus above 700.degree. C. Data, however, only is given for diamond compacts containing a second phase of silicon, nickel, or their carbides. When the present inventors utilized brazing alloys containing carbide-forming active metals as proposed in this British patent, but when bonding porous compacts (as defined herein), bonding was erratic. Moreover, relatively low bond strengths were realized even when bonding did occur. U.S. Pat. Nos. 3,894,673 and 4,018,576 propose to bond signle crystals of diamond to metal using nickel/chromium or cobalt/chromium braze alloys.


This invention relates to chip pads, and in particular to circuitry associated with chip pads.
FIG. 1 is a schematic diagram of an integrated circuit (IC). The IC is formed as a set of electrical components on a semiconductor die 1. The components include a main processing section of active components 2. Around the periphery of the die is a set of bonding pads 3, known collectively as a pad ring. The bonding pads serve to allow the die to be connected to other devices. For example, when the die is packaged, wire bond connections may be made from the pads 3 to solder pads on the exterior of the package. Those solder pads may then be soldered or clamped to a circuit board.
Each bonding pad 3 has interface circuitry 4 located between it and the active components 2. FIG. 2 shows a simple example of the form the interface circuitry may take. In this example the interface circuitry 4 provides electrostatic discharge (ESD) protection and level shifting. Diodes 5, 6 are arranged between the pad 3 and voltage supply rail 7 and ground 8. They resist ESD interference being passed to the line 10 that connects the pad to the active components 2. A level shifter 9 converts between the voltage level used to represent “high” in the domain of the active circuitry 2 and the voltage level used to represent “high” in the domain of the pads. In this example the voltage level used to represent “high” in the domain of the active circuitry is slightly lower than the voltage level used to represent “high” in the domain of the pads, so for output signals the level shifter converts a “high” signal input from the active components 2 into a slightly higher voltage that will be passed to the pad 3, and for input signals the level shifter converts a “high” signal input from the pad 3 into a slightly lower voltage that will be passed to the active components 2.
One trend in modern IC design is to drastically reduce the power consumption of ICs. One way to reduce power is to divide the IC into a set of power domains. A power domain is a set of components on the IC that can together be placed in a low power mode independently of the other components on the IC. Dividing the IC into multiple power domains allows parts of the IC that are not being used to be powered down, so that they are using little or no power, whilst other parts of the IC continue to function. Normally the IC will be equipped with a power controller which determines which power domains need to be turned on to satisfy the current requirements on the IC, and arranges for the other power domains on the IC to be powered down.
The IC might be intended to generate outputs that will be read by other devices. Those outputs will be presented as high or low voltages, representing binary ones or zeros, at its output pads. The state of an output pad will be determined by active circuitry on the IC. That active circuitry will generate a logical output, and the appropriate output pad will be set to high or low accordingly.
Once the active circuitry has generated the logical output, e.g. at point 10 in FIGS. 1 and 2, the active circuitry has completed its task. Assuming no more work is required of the active circuitry, the active circuitry could in principle be powered down to reduce energy consumption. However, if the chip pad has a simple driver circuit as shown in FIG. 2, if the active circuitry is powered down then the pad will no longer carry an output, or could revert to a default state. It is generally not known when the external device that is intended to consume the output has actually read the state of the pad. Therefore, it is normally desirable to keep the active circuitry powered up for some time after it has completed its processing, just to maintain an output at a pad that can at some stage be accessed by a consumer of that output. Keeping the active circuitry alive in that way consumes power that could otherwise be saved.
One way to address this is to make the entire pad ring, including those latch circuits, a separate power domain from the active circuitry, and to provide a buffer as part of that power domain into which the pad state can be written when the active circuitry is to be shut down. This provides advantages over keeping the active circuitry powered up, but the requirement to store the pad state into the buffer increases the time taken to power down the active circuitry, and it can be complex to lay out the IC to that the buffer can communicate with the pads and share their power domain.