Conventionally, as a method for forming quantum dots, the forming method based on Stranski-Krastanow mode (S-K mode) is known.
S-K mode is a mode in which a semiconductor crystal to be epitaxially grown grows two-dimensionally (film growth) at the start of the growth and grows three-dimensionally on the stage where the semiconductor crystal has exceeded the elastic limit of the film. A film having a larger lattice constant than the base material is epitaxially grown, whereby quantum dots of three-dimensionally grown islands are self-assembled.
S-K mode can easily make quantum dots self-assembled, and is widely used in the field of photosemiconductor devices, etc.
Recently, techniques in the fields of quantum information and quantum computation attract a great deal of attention. In these fields it is very important to form a quantum dot in a prescribed position in a prescribed size.
However, the conventional method for forming quantum dots described above makes positions and sizes of the formed quantum dots random.
As techniques of controlling positions for quantum dots to be formed in, the following techniques have been proposed.
For example, Japanese published unexamined patent application No. 2000-315654, the specification of U.S. Pat. No. 5,229,320 and Appl. Phys. Lett., Vol. 76, No. 2, p. 167-169, (2000) propose techniques of controlling positions for quantum dots to be formed in by forming in advance by means of electron beams concavities in the surface of a semiconductor substrate in positions for quantum dots to be formed in. When a semiconductor layer is grown on a semiconductor substrate with concavities formed in, the semiconductor layer tends to grow at a higher rate in the concavities, whereby quantum dots can be formed in the concavities.
Appl. Phys. Lett., Vol. 75, No. 22, p. 3488-3490, (1999) and Phys. Stat. Sol. (b) 224, No. 2, p. 521-525, (2001) propose a technique of forming in advance by means of an STM (Scanning Tunneling Microscope) deposits in positions for quantum dots to be formed in to thereby control the positions for the quantum dots to be formed in. When a semiconductor layer is grown on a substrate with deposits formed on, concavities are formed in the semiconductor layer surface above the deposits. When another semiconductor layer is grown on the semiconductor layer with the concavities formed in, quantum dots are formed in the concavities because said another semiconductor layer grows in the concavities at a faster growth rate.
Appl. Phys. Lett., Vol. 77, No. 16, p. 2607-2609, (2000) proposes a technique of forming trenches in the surface of a semiconductor substrate by means of an AFM (Atomic Force Microscope) to form quantum dots in the trenches.
However, in the above-described technique of forming the concavities by means of electron beams, the surface of the semiconductor substrate is contaminated with carbon when the concavities are formed by means of electron beams, which makes it difficult to form quantum dots of good quality.
In the above-described technique of controlling positions of quantum dots by using an STM, crystal defects take place in the semiconductor layer with the concavities formed in. It is difficult to form quantum dots of good quality on the semiconductor layer having the crystal defects. Furthermore, the diameter of the concavities are somewhat enlarged, and it is difficult to form fine quantum dots of a below 40 nm (including 40 nm)-diameter.
In the technique of controlling positions of quantum dots by using an AFM, the trenches are formed in the substrate surface by mechanically scraping the substrate surface with the probe of the AFM. Therefore, the configurations of the trenches are non-uniform. It is difficult to form quantum dots in a uniform size. The trenches are formed by mechanically scraping the substrate surface, which causes crystal defects in the trenches. It is difficult to form quantum dots of good quality without crystal defects in the trenches with such crystal defects.
Recently techniques in the fields of quantum information and quantum computation attract a great deal of attention as described above, and possibilities of applications of quantum dots attract attention. However, for further fundamental studies and application development of quantum dots, various technical barriers which have to be overcome are present.
For example, quantum dots have small sizes, and the quantum dots self-assembled by using S-K mode are distributed at random. No method that makes the self-assembled quantum dots distributed at random electrically accessible has been so far proposed.
On the other hand, conductor pads of an about 100 nm-size can be formed by using processes, such as electron beam lithography, reactive ion etching, etc., which can make submicron processing. Accordingly, in a case that the density of quantum dots is very low, it will be possible to form an electrode above a single quantum dot by using such process. That is, electrodes are formed suitably above the regions where quantum dots are expected to have been formed, by using a process which can make submicron processing. Then, whether or not the quantum dots are present below the electrodes is checked. The electrode formation and the following check are repeated many times, whereby the presence of a single quantum dot below the electrode could be often found. However, it is almost impossible to capture a single quantum dot in a case that the density of the quantum dots is high. Such method depending on the probability is inefficient to fabricate devices.
Japanese published unexamined patent application No. Hei 07-297381 (1995) proposes a method of electrically accessing quantum dots by means of electrodes in the form of a fine probe shape. However, in this case, in order to arrange electrodes above quantum dots, a special process for forming the quantum dots in an array or others is necessary. In Patent Reference 1, electric fields of the probe-shaped electrodes will be distributed far more widely than a size of the quantum dots. Accordingly, the electric fields of the electrode arranged above a certain quantum dot will influence quantum dots adjacent to said certain quantum dot.
As described above, the conventional techniques have established no method of making accurate electric access to each of quantum dots which have self-assembled at random.
It is very significant in various aspects of the fundamental studies, application developments, etc. of quantum dots to realize the accurate electric access to each of self-assembled quantum dots.
An object of the present invention is to provide a method for forming a quantum dot which can form a quantum dot of good-quality in a prescribed position and in a prescribed size.
Another object of the present invention is to provide a quantum semiconductor device which can make accurate electric access to a quantum dot and a method for fabricating the quantum semiconductor device.


Nowadays, a conventional antenna cannot be used in an electronic device with a full metal shell, since a signal of the antenna may be shielded and thus the antenna cannot work normally. Furthermore, the conventional antenna of the electronic device cannot cover WWAN (Wireless Wide Area Network).


Reclosable plastic bags are used for many purposes, including transporting and storing food products and other materials. Reclosable bags are often preferred over other available bags because of numerous advantages, including that they are easy to close and reopen for access without compromise of integrity when closed.
Typically, such bags are reclosable using a zip-action, locking reclosable closure. Unfortunately, when using such a bag for a first time, there is currently no way of knowing if the bag is sanitary, has been used, tampered with or otherwise contaminated. This is particularly important if the contents to be stored in the bag are perishable or easily contaminated. Exemplary of such is breast milk.
Likewise, currently available bags are typically difficult to fill (E.G., with a liquid substance) without obstruction from the lips and/or spilling along the sides of the bag. At least one reason it is difficult to fill currently available bags is that the edges are typically heat-sealed along their entire length from the bottom of the bag to the top of the bag. These heat-sealed edges typically make it somewhat difficult to pull the lips apart, as well as impede the ability of the bag to remain open during filling.
Yet another disadvantage of using currently available bags to store liquids is that the zipper may not remain sealed. This is particularly true when, for instance, the bag lies on its side—the bag thus situated is more likely to seep some of the liquid contents.
The present invention avoids these and other difficulties by providing a tamper evident reclosable bag that ensures that the bag is being used for the first time. The present invention further provides a bag that is easier to open, easier to fill, seals better, and has less leakage than currently available bags.


The present invention relates to a solid state image sensor comprising a plurality of pixels formed by static induction transistors having both a photoelectric converting function and a switching function.
Heretofore, there have been proposed various solid state image sensors comprising a charge transfer device such as CCD and BBD, and MOS transistors. However, such known image sensors have drawbacks in that electric charges are leaked during the charge transfer and the photodetection sensitivity is low. In order to avoid such drawbacks, there has been proposed a solid stage image sensor comprising static induction transistors (hereinafter abbreviated as SIT). For instance, in an European Patent Application No. 83900059.3 (Publication No. 96725), there is described a solid state image sensor comprising SITs each of which serve as a photodetecting element and a switching element. The inventor of the instant application has also proposed in U.S. patent application Ser. No. 647,169 filed on Sept. 4, 1984, a solid state image sensor comprising SITs., which solid state image sensor has a higher sensitivity and is easily manufactured. This solid state image sensor can read out an image signal while stored charges remain undestroyed and can have a high sensitivity by prolonging the time period of accumulating photocarriers.
FIGS. 1A and 1B show an embodiment of the solid state image sensor comprising SITs as proposed in the above mentioned Patent Application. A SIT shown in FIG. 1A comprises an n.sup.+ substrate 1 which serves as a drain of the SIT, a lightly doped n.sup.- epitaxial layer 2 which is grown on the substrate 1 and serves as a channel, an n.sup.+ source region 3 and p.sup.+ gate regions 4 formed in the epitaxial layer 2 by means of, for example, a thermal diffusion, source electrode connected to the source region 3 and gate electrodes 6 arranged above the gate regions 4 via an insulating film 5 such as SiO.sub.2 to form a gate capacitor 7. The SIT is isolated from adjacent SITs by means of an isolation region 9 formed by a burried insulating substance. A number of SITs are arranged in a matrix on the same substrate.
FIG. 1B is a circuit diagram illustrating a whole construction of the solid state image sensor comprising normally-on type SITs shown in FIG. 1A. Drains (substrate) of SITs 10-11 to 10-mn forming pixels arranged in a matrix are commonly connected to ground, and to gate electrodes of SITs 10-11 to 10-1n; . . .; 10-m1 to 10-mn arranged in the X direction, i.e. in a row, are connected row lines 11-1 to 11-m, respectively, which lines are then connected to a vertical scanning circuit 16 to receive row selection signals .phi.G1 to .phi.Gm. Source electrodes of SITs 10-11 to 10-m1; . . .; 10-1n to 10-mn arranged in the Y direction, i.e. in a column are connected to column lines 12-1 to 12-n, respectively, whose first ends are connected to a video voltage source Vs via respective column selection transistors 13-1 . . . 13-n, a common video line 14 and a load resistor 15. To gates of the column selection transistors 14-1 to 14-n are applied column selection signals .phi.S1 to .phi.Sn, respectively from a horizontal scanning circuit 17.
In the SIT having the construction explained above, when a light input is given, electron-hole pairs are induced in the channel region 2 and a gate depletion region. Electrons are conducted away into the drain 1 connected to ground, and holes are stored in the signal storing gate region 4 and thus the gate capacitance 7 connected thereto is charged to vary a gate potential by .alpha.V.sub.G. Now it is assumed that an amount of electrostatic charges stored in the gate region 4 is represented by Q.sub.L and the capacitance of the gate capacitor 7 is denoted by C.sub.G, then .alpha.V.sub.G =Q.sub.L /C.sub.G is obtained. After a certain accumulation time, when a readout pulse V.sub..phi.G is applied to the gate terminal 8, the gate potential is changed into a sum of V.sub..phi.G and .alpha.V.sub.G. Then, a potential difference between the signal storing gate region 4 and source region 3 is lowered to decrease the depletion layer and a drain current having an amplitude corresponding to the light input begins to flow between the source and drain. Due to the amplifying function of SIT, the drain current is multiplied by the amplification factor of the SIT. It should be noted that even if the source and drain of the SIT are exhanged, a similar operation to that explained above may be effected.
FIGS. 2A to 2F illustrate waveforms of the signals applied to the row lines 11-1 to 11-m and column selection transistors 14-1 to 14-n. As illustrated in FIGS. 2A to 2F, in this solid state image sensor, the successive pixels are readout by successively selecting the row lines 11-1 to 11-m as well as by successively selecting the column lines 13-1 to 13-n while a row line has been selected. Each of the signals applied to the row lines has a lower voltage V.sub..phi.G, and a higher voltage V.sub..phi.R. During the line scanning period t.sub.H the row selection signal has the voltage V.sub..phi.G and during a horizontal blanking period t.sub.BL the row selection signal assumes the voltage V.sub..phi.R. Each of the column selection signals .phi.S1, .phi.S2 . . . applied to the gates of the column selection transistors has a low level for cutting off the transistor and a high level for making the transistor conductive.
When the vertical scanning signal .phi.G1 is increased to the high voltage V.sub..phi.G, SITs connected to the first row line 11-1 are selected and the SITs are successively read out while the column selection transistors 13-1, 13-2 . . . 13-n are successively made conductive by means of the horizontal scanning signals .phi.S1, .phi.S2 . . . .phi.Sn. In this manner, a video signal of one line is derived on the video line 14. Then, the SITs in the first row are simultaneously reset when the vertical scanning signal .phi.G1 is increased to the higher level V.sub..phi.R.
Next, when the vertical scanning signal .phi.G.sub.2 is changed to the voltage V.sub..phi.G, all SITs 10-21, 10-22 . . . .phi.-2n connected to the second row line 11-2 are selected and are successively readout by means of the horizontal scanning signals .phi.S1, .phi.S2 . . . .phi.Sn.
In this manner, successive pixels are readout to derive a video signal of one frame.
The inventor has found that the known solid state image sensor mentioned above has the following drawbacks. In the image sensor, the accumulation of photocarriers induced by the incident light is effected in the channel region 2 and gate depletion layer in each SIT. The accumulating regions correspond to portions in the channel region which situated between the gate regions and isolating region, and underneath the gate regions. It is apparent that the portions between the gate regions and isolating region are liable to be small as the dimension of pixels is made smaller. Then, a major portion which serves to accumulate the photocarriers would be the portion in the channel region situated underneath the gate region 4, and thus, the incident light has to transmit through the gate regions 4. In order to obtain a large amplification of the SIT, a depth Xj of the gate region 4 has to be relatively thick such as 2 to 4 .mu.m. Therefore, the incident light, particularly components of short wavelengths (blue light) is abosrbed in the gate region 4 and cannot penetrate to the portion of channel region underneath the gate region.
FIG. 3 is a graph showing a light absorption coefficient .alpha. of silicon in dependence upon wavelength .lambda. of incident light. If it is assumed that .lambda.=0.4 .mu.m and the thickness of the P.sup.+ gate region is 3 .mu.m, then .alpha.=6.times.10.sup.-4 cm.sup.-1, and a light transmittivity becomes a very small value such as e.sup.-6.times.10.spsp.4.sup..times.3.times.10.spsp.4 =1.5.times.10.sup.-8. In this manner, the known solid state image sensor has a very low sensitivity especially for blue light and thus a color camera comprising the solid state image sensor having a high sensitivity over a whole sepectrum of visible light can not be realized.


The present invention relates to a teletext converter which is external to a television receiver ("set-top" converter), and more particularly, to such converters having a "transparent mode".
Teletext is a service that broadcasts digital information within the vertical blanking interval (VBI) of a standard broadcast television signal and at the receiver presents the information as digitally generated text and/or pictures on a display screen. In the most commonly considered mode of operation, the standard TV picture is completely replaced by the digitally generated picture. "Transparent mode" refers to the situation in which some region of the screen, rather than being defined by the teletext signal, is occupied by the regular video signal. One example is a regular video picture having a teletext generated sub-title or caption. Ideally, the teletext converter, which converts the digital signals into video signals, is located within the receiver. However, almost all existing receivers do not have such an internal converter. Thus an external set-top converter is used if teletext signal reception is desired on most existing sets. A set-top converter receives the antenna signal, converts the digital teletext signal into a video signal, and then provides an output signal for connection to the receivers antenna input terminal.
One prior art method of producing a transparent mode set-top converter is to decode the regular video to baseband red, green and blue signals, combine these signals with R, G, and B signals derived from the decoded teletext, re-encode to composite NTSC, and then modulate with the composite NTSC signal an output carrier having a selected channel frequency. This approach suffers the deficiencies of high cost and significant signal quality degradation.
In particular, the decoding of composite video to baseband color signals, involving the separation of luminance and chrominance, band-limiting these signals and various other distortion producing processes degrades the fidelity of the standard TV picture produced after re-encoding and finally decoding again in the TV receiver.
It is therefore desirable to provide a set-top teletext decoder with transparent mode that does not cause signal degradation and has accurate color fidelity.


Recently, the technique for reducing mounting costs is studied and developed by use of a coupling system called a direct optical coupling (butt joint) system. In the coupling system, an optical fiber and optical semiconductor element are arranged in close positions to face each other and optically coupled without using a lens. When the direct optical coupling system is used, it is important to arrange an optical semiconductor element and optical fiber in close positions and prevent light from reaching an unwanted portion. Therefore, there is proposed a method for directly forming an electrical interconnection on the main surface of an optical transmission line holding member (a so-called optical fiber ferrule) that holds the optical fiber and the like and mounting an optical semiconductor element on the main surface to set the light receiving/transmitting region thereof in opposition to the optical fiber (Jpn. Pat. Appln. KOKAI Publication No. 2001-159724).
In this type of method, it is desired to fill resin in between the optical semiconductor element and the optical transmission line so as to suppress reflection light caused by discontinuity of the refractive index. Specifically, resin having a role as a refractive index matching material and an under-filling function for protection of the electrical connecting portion of the optical element is filled in between the optical semiconductor element and the end face of the optical transmission line. Further, resin used to mechanically fix the optical transmission line on a ferrule is filled.
As a method for forming the above resins, a method for performing an under-filling process before fixing the optical transmission line and a method for fixing the optical transmission line and then performing an under-filling process are considered. When the optical transmission line is first fixed, there occurs a possibility that fixing resin flows into holding holes for the optical transmission line to reach the end face on the optical element side. Further, since the fixing resin fills in the holding holes, the holes via which air escapes when under-fill resin is injected are closed or blocked. This means that the holes via which a solvent produced at the curing time of the under-fill resin is extracted are closed. Therefore, there occurs a possibility that bubbles remain in the resin at the curing time of the under-fill resin and this may prevent the optical coupling. When the under-filling process is first performed, there occurs a problem that high mechanical precision cannot be attained.


Coplanar waveguides (CPW) generally comprise a conductive line placed between two ground lines, and allow components such as antennas operating at frequencies of, for example, about several tens of gigahertz, to be electrically connected. When a high-frequency signal is passed through such a waveguide, losses can lead to the signal being attenuated. These losses are in particular due to the resistance and inductance of the line, to capacitive coupling to the substrate, and to conductance allowing ground return.
In order to reduce these losses, it has been suggested, by Gamble, “Low-loss CPW lines on surface stabilized high-resistivity silicon,” IEEE Microwave and Guided Wave Letters, Vol. 9, No. 10, October 1999, that these coplanar waveguides be fabricated using metal lines on high-resistivity silicon substrates. Thus low conductance is obtained between the conductive line and the ground lines. The diffusion of metals, for example gold or copper, into the silicon, and the possibility that charge trapped in a passivation layer placed in contact with the conductive lines will induce a conductive channel in the substrate, between the signal and ground, are the drawbacks of this solution.
Superposing the conductive lines of the coplanar waveguides on insulating lines, for example silicon-dioxide (SiO2) lines, on a high-resistivity silicon substrate has also been suggested. This solution has the drawback of forming capacitive coupling between the conductive lines and the substrate. Moreover, charge trapped in a passivation layer, placed in contact with the conductive lines, can also induce a conductive channel in the high-resistivity silicon substrate, between the regions under the conductive lines.
It has also been suggested that the conductive lines of the coplanar waveguides be formed on an insulating layer, placed on a polycrystalline-silicon layer, itself placed on a high-resistivity silicon substrate. This solution allows current flowing under the insulating layer to be captured in the polycrystalline-silicon layer.
The reader may also refer to Ojefors, “Micromachined loop antennas on low resistivity silicon,” IEEE Transactions on Antennas and Propagation, 2006, Vol. 54, No. 12, pages 3593-3601, describing the formation of trenches in the silicon substrate under the oxide layer and located substantially between the conductive lines of an antenna and a ground plane. This solution in particular has the drawback of being complicated to implement.
Finally, Wojnowski, “Package Trends for Today's and Future mm-Wave Applications,” Infineon, 38th European Microwave Conference, 2008, describes the formation of a cavity matrix under the coplanar waveguides. This solution does not sufficiently limit losses, in particular because of parasitic conductivity in the silicon. The formation of the cavities described in this document also has the drawback of being implemented before metal lines have been formed on the frontside of the integrated circuits.
Moreover, it may be necessary to use through-silicon vias in integrated circuits, for example in order to form three-dimensional stacks or in order to form electrical contacts on a side opposed to that comprising the metal lines of the integrated circuit.


1. Field of the Invention
The present invention relates to controllers for servomechanisms, and in particular, to a digital servomechanism controller that includes both a "dumb" servomechanism controller and a neural network based servomechanism controller working in conjunction with one another.
2. Description of the Related Art
Computer disk drive servomechanisms are electromechanical devices which require control systems for controlling their rotational velocity and the positioning of their read, write and position sensing heads. Such control systems, commonly referred to as servo controllers, are well known in the art. As illustrated in FIG. 1, a servo controller and the servomechanism to be controlled are typically interconnected in a classical feedback control system design.
The servo controller provides a servo control signal to the "plant," i.e. the disk drive servomechanism, for controlling the performance thereof, e.g. to rotate the storage media and position the read, write and position sensing heads. The plant generates feedback signals which represent actual performance parameters of the plant, e.g. the actual velocity of the storage media and the actual position of the heads. Each actual performance signal is combined with a reference signal which represents the desired performance of the plant. This produces an "error" signal (representing the difference between the desired and actual performance signals) which is used to drive the servo controller.
The servo controller adjusts its servo control signal output in accordance with its error signal input. As the performance of the plant changes in accordance with its servo control signal input, the actual performance feedback signal more closely resembles the reference signal, thereby causing the error signal to decrease. Once the error signal has decreased below a predetermined threshold value, the servo controller ceases to modify its servo control signal output, and instead simply maintains its servo control signal output until such time as the error signal once again rises above the predetermined threshold.
The simplest servo controller is a "dumb" (e.g. non-programmable, or with a fixed or static program) analog network which accepts an analog error signal and provides an analog servo control signal to the plant in accordance with a substantially fixed design or algorithm. In turn, the actual performance feedback signal and reference signal are analog signals as well. Typical control characteristics provided by analog servo controllers are referred to as "proportional," "integral," "derivative" and "proportional-integral-derivative" ("PID").
A "proportional" type of servo controller produces a servo control signal which is proportional to the error signal and can be described as follows:
U=K.sub.p E PA1 U=servo control signal PA1 E=error signal PA1 K.sub.p =proportional feedback coefficient PA1 dt=time differential
where:
An "integral" type of servo controller produces a servo control signal based upon the integral of the error signal and can be described as follows: ##EQU1## where: T.sub.I =integral feedback coefficient
A "derivative" type of servo controller produces a servo control signal which is based upon the derivative of the error signal and can be described as follows: ##EQU2##
A "PID" type of servo controller produces a servo control signal which can be proportional to the error signal, while simultaneously containing components based upon the integral or derivative of the error signal, or both. Such a servo control signal can be described as follows: ##EQU3##
The relative simplicity of analog servo controllers, however, renders them inadequate for controlling today's high performance disk drive systems having increasingly denser storage capabilities. This has resulted in the widespread use of digital servo controllers.
Digital servo controllers, particularly those using microprocessors, allow for more sophisticated control characteristics. By properly programming its microprocessor, a digital servo controller can also be a "proportional," "integral," "derivative" or "PID" type of servo controller. But, the flexibility afforded by the programmability of the digital servo controller allows more precise control to be exercised.
However, digital servo controllers have limitations of their own. Even with their programmability, their design, whether with respect to hardware or software, is essentially fixed. In other words, the control characteristics are fixed in the sense that they cannot anticipate and compensate for the varying control environment and system nonlinearities which inevitably exist but cannot be precisely predicted or modeled.
As will be appreciated, variances in the control environment can arise and system nonlinearities can be introduced in a number of ways. For example, variances in the control environment can arise due to changes in the operating characteristics or tolerances of the hardware components used to construct the system. Such changes can be induced by factors such as changes in temperature, humidity, shock, vibration, power supply voltages, etc. System nonlinearities can be introduced by system hardware components which vary randomly from their nominal rated values, and yet are still within their rated tolerances.
To overcome the limitations of a simple digital servo controller, "adaptive controllers" have been developed. As illustrated in FIG. 2, an adaptive controller is used in conjunction with a digital servo controller. Two error signals are produced, error signals "A" and "B," for use by the digital servo controller and adaptive controller, respectively.
The actual performance signal produced by the plant, in addition to being compared with the reference signal directly, is also compared to the output signal of the "reference model." The reference model is a preprogrammed digital circuit, or software model, which receives the reference signal and produces an output signal based upon a desired copy of the servomechanism system. In other words, the reference model is a mathematical model based upon historical data regarding the control environment and system nonlinearities of the system, including the plant and servo controller. This model is then used to generate a desired model output signal.
The result of this comparison between the actual performance signal and the modified reference signal, i.e. error signal B, is used to drive the adaptive controller. In accordance therewith, the adaptive controller provides a signal to the servo controller which is used to adjust the parameters of the control characteristics used by the digital servo controller in producing the servo control signal for the plant.
For example, the signal from the adaptive controller can be used to adjust the "proportional," "integral" or "derivative" constants or coefficients used by the servo controller in generating the servo control signal. By using the adaptive controller in this manner, the otherwise fixed design or algorithm of the servo controller can be adapted in accordance with the reference model to more closely compensate for the varying control environment and system nonlinearities. In other words, using the adaptive controller in this way allows the overall system operation to track the operation model stored as the reference model.
However, adaptive controllers tend to be quite complex and typically require large amounts of computation time. Furthermore, mathematical models (e.g. for the reference model) which give good representations of the servomechanism control environment and the disk drive system are very difficult, if not impossible, to achieve.
The overall operating environment sought to be controlled is inherently nonlinear. Therefore, the requisite mathematical models should ideally also be nonlinear so as to more closely approximate that environment. However, such nonlinear models provide ad hoc control solutions and are unique for each application to avoid introducing excessive errors of their own. Further, they are generally quite complex and difficult to redesign for use in other applications.
Linearized models, i.e. models which are based upon linear mathematical models, have been used with some success. However, while linear models are simpler and may be more easily redesigned for use in other applications, their performance outside of the relatively narrow regions for which they are optimized has been disappointing.
To meet this need for servo controllers which can adaptively control inherently nonlinear servomechanisms in a varying control environment, intelligent servo controllers have been proposed. An advantage of intelligent servo controllers is their ability to provide more reliable generalized solutions for controlling servomechanisms over wider ranges of operating conditions and uncertainties. This is in contrast to the ad hoc control solutions provided by adaptive controllers using nonlinear models which tend to be application specific.
One type of proposed intelligent servo controller uses artificial intelligence. Another proposed type, which offers better performance, is referred to as "fuzzy." However, the artificial intelligence or "fuzzy" controllers are still computation intensive and based upon rules or algorithms. Therefore, their generalization capabilities are poor. Thus, they have not been widely accepted.
A third type of proposed intelligent servo controller, which has offered the best performance so far, is that which uses a neural network. Its advantage is that a neural network is not reliant upon algorithms and is capable of adapting to virtually all parameter or system variations. Therefore, it has better generalization capabilities.
Using a neural network servo controller to control a disk drive servomechanism requires that the neural network servo controller be coupled to the plant in two distinct configurations, as shown in FIGS. 3A-3B. As shown in FIG. 3A, the initial configuration establishes the general learning phase for the neural network servo controller. The neural network servo controller receives the actual performance signal from the plant and adjusts its adaptive weights in accordance with the error signal produced by the comparison of the reference signal with the output signal of the neural network servo controller. In this configuration, the neural network servo controller learns the inverse model of the plant broadly.
The second configuration, shown in FIG. 3B, is the specialized learning phase for the neural network servo controller. The reference signal drives the neural network servo controller directly, and is also compared to the actual performance signal output of the plant to produce the error signal. The error signal is then used to further train the neural network. Therefore, in this configuration, the neural network servo controller controls the plant via the servo control signal, while simultaneously learning and adapting to variations in the control environment and system nonlinearities.
However, the use of a neural network based servo controller has limitations with respect to its practicality. The general learning phase, as illustrated in FIG. 3A, is very broad. A large number of hardware neurons, or software based calculations, are needed to take advantage of the higher resolution and accuracy capabilities provided by the neural network. Furthermore, to achieve maximal generalized learning, rigorous learning in the form of using many sets of input patterns, i.e. reference signals, is required.
Therefore, it would be desirable to have a disk drive servo controller which provides the resolution, accuracy and adaptability of a neural network, but which does not require an impractically large number of hardware neurons or software based calculations, nor require extensive input learning patterns.


The method and the apparatus of the present invention are applicable to a hot-dip coating of a ferrous base metal strip with zinc, zinc alloys, aluminum, aluminum alloys, terne, lead and those coating metals or coating metal alloys which have oxide forming characteristics such that optimum finishing cannot be accomplished by conventional jet practice or by conventional exit rolls. While not intended to be so limited, for purposes of an exemplary showing the method of the present invention will be described as applied to galvanizing. The method can be practiced on various types of galvanizing lines. For example, the method of the present invention is applicable to fluxless, hot-dip metallic coating of ferrous base metal strip where it is necessary to subject the strip surfaces to a preliminary treatment which provides the strip with oxide free surfaces and preferably brings the strip to a temperature approximating that of the molten zinc or zinc alloy coating bath at the time the strip is caused to pass beneath the surface thereof. One of the principal types of anneal-in-line, fluxless, preliminary treatments is the so-called Sendzimir process or oxidation-reduction practice disclosed in U.S. Pat. Nos. 2,110,893 and 2,197,622. Another anneal-in-line, fluxless, preliminary treatment in common use is the so-called Selas process or high intensity direct fired furnace practice disclosed in U.S. Pat. No. 3,320,085.
In the Selas process the ferrous base metal strip is passed through a direct fired preheat furnace section. The strip is heated by direct combustion of fuel and air producing gaseous products of combustion containing at least about 3% combustibles in the form of carbon monoxide and hydrogen. The strip reaches a temperature of about 535.degree. C. to about 760.degree. C. while maintaining bright surfaces completely free of oxidation. The strip is then passed into a reducing section which is in sealed relation to the preheat section and which contains a hydrogen and nitrogen atmosphere, wherein it may be further heated by radiant tubes to from about 650.degree. C. to about 925.degree. C. and thereafter cooled approximately to the molten coated metal bath temperature. The strip is then led beneath the bath surface while surrounded by the protective atmosphere.
Other related pretreatment techniques are taught in U.S. Pat. No. Re 29, 726--U.S. Pat. Nos. 3,837,790--4,123,291--4,123,292 and 4,140,552. The above mentioned prior art patents constitute non-limiting examples of fluxless, continuous galvanizing processes to which the method of the present invention is applicable. When such conventional strip preparation techniques as are taught in the above mentioned prior art are used, it is necessary that the base metal strip be maintained in a protective atmosphere at least until it passes beneath the surface of the bath of molten zinc or zinc alloy.
Such a protective atmosphere is not a requirement when flux or chemical strip preparation techniques of the type taught in U.S. Pat. Nos. 2,824,020 and 2,824,021 are employed. Briefly, when such chemical strip preparation techniques are used, the ferrous base metal strip is caused to pass through a flux bath and through means to assure the proper thickness of the flux coating on the strip. The ferrous base metal strip is then conducted through a heating chamber wherein the strip is heated to evaporate the water in the flux solution. Thereafter, the ferrous base metal strip is further heated to raise it to that temperature approaching the maximum temperature of stability of the flux coating on the strip. The strip is then caused to pass beneath the surface of the bath of molten zinc or zinc alloy so as to be coated. The method of the present invention is equally applicable to galvanizing lines utilizing such flux or chemical pretreatment systems.
From the above it will be evident that the method of the present invention is not limited to the use of any particular pretreatment of the ferrous base metal strip in the galvanizing line and the terms "pretreatment" or "pretreated" (as used herein and in the claims with reference to the ferrous base metal strip) are to be interpreted broadly to include any of the conventional pretreatment systems exemplified by the above noted prior art. In general, these terms refer to any appropriate pretreatment technique, the result of which is such that, during the actual coating step wherein the ferrous base metal strip passes through the molten bath of zinc or zinc alloy, it will be at or will achieve the proper coating temperature and its surface will be oxide-free.
In conventional continuous hot dip galvanizing, it is usual to cause the two-side coated strip to exit the molten coating metal bath into the ambient atmosphere. The most widely used finishing and coating weight control technique is to direct the coated strip between jet knives or nozzles which cause a blast of air or steam to impinge upon both sides of the coated strip, returning excess coating metal to the bath. This finishing technique, however, has a number of definite drawbacks. Some of these drawbacks include coating ripples, oxide curtains and, bath surface oxide problems, including the necessity for top skimming. All of these defects are real, but are reasonably controllable by known methods.
U.S. Pat. Nos. 4,107,357 and 4,114,563 and German Pat. No. 2,656,524 are exemplary of patents teaching methods for coating one side only of a ferrous base metal strip. In the practice of these processes, the coated strip after contact with the coating bath is maintained in a protective, non-oxidizing atmosphere and is jet finished with nitrogen or non-oxidizing gas. However, the primary purpose of these steps is to prevent oxidation of that side of the ferrous base metal strip not coated or, if the uncoated side has an oxide film thereon, to prevent adherence of the coating metal to the oxide film. Nevertheless, U.S. Pat. No. 4,114,563 mentions in passing that the above noted defects are controlled or eliminated when finishing in a protective atmosphere.
A major problem area encountered with conventional jet finishing is that of coating control at the edges of the strip. One edge problem is that of zinc coating thickness over a narrow band immediately adjacent each edge of the coated strip. The coating thickness of these bands is greater than the coating thickness over the rest of the strip width. If this coating thickness differential is great enough, edge buildup or spooling will occur when the continuous strip is coiled under tension.
Edge berries (small balls of oxide) which are attached to the strip edge and are pulled through the jet blast constitute another troublesome problem. Furthermore, an edge defect commonly known as "feathered oxide" occurs during low speed jet finishing. Feathered oxide is characterized by discontinuous patches of heavy coating metal oxide which pull through the jet blast. They appear much like feathers which extend inwardly from the strip edges with the tips thereof pointing toward the center of the strip.
Many methods have been used by prior art workers to reduce build-up and oxide control problems at the strip edges. Tapered jet nozzle slot openings are commonly used where the slot opening of the jet finishing nozzle continuously increases in width from the center of the jet nozzle to its ends. Such a contoured jet finishing nozzle is taught in U.S. Pat. No. 4,137,347.
Other methods to control edge coating include curving the jet nozzles so that the nozzle is closer to the strip at the strip edges than at the strip center. Also, vanes or nozzle extensions have been used at the strip edges to bring the nozzle closer to the edges than to the center of the strip. Still other methods include the use of shutters and auxiliary jets, both internal and external to the main jet nozzles, to alter the jet wiping force at the strip edges as compared to the jet wiping force at the strip center.
All prior art methods fall short of producing optimum edge control with a minumum of operator attention, maximum coating metal economy, and proper edge control over a wide range of strip widths and line speeds.
Edge build up in a one-side coating process differs from that encountered in a conventional two-side coating process. This is true because, when jet finishing is employed, it is normally performed with a single jet nozzle, preferably with a back-up roll on the uncoated side of the strip. As a result, edge build-up is less severe, since the back-up roll serves as an extension of the strip edges.
Yet another major hot-dip zinc coating defect is commonly referred to as "spangle relief". Spangle relief has two aspects. One is the variation of surface profile (zinc thickness) across the zinc crystal from one boundary to the opposite boundary. The other is a depressed spangle boundary which surrounds each spangle or crystal. Spangle relief can be reduced by such methods as purposely causing part of the zinc coating to alloy with the ferrous base metal, or by antimony additions to the zinc bath. However, none of these methods is entirely satisfactory.
As a result, many methods have been developed to suppress spangle formation. That is, to minimize final spangle size to such an extent that the spangles are hardly visible to the naked eye. For example, U.S. Pat. Nos. 3,322,558; 3,379,557 and 3,756,844 teach spangle minimizing methods. Most methods involve spraying water or water solutions against the molten coating to quench the coating and create many nucleation sites. However, the results achieved by these spangle minimizing methods are not always consistent.
While spangle relief can be reduced or masked by temper (skin-pass) rolling such temper rolling causes these defects to become imprinted in the base metal. As a result of this non-uniform cold working of the base metal, the defects may reappear when critical surface items such as automotive body parts and appliance parts are stamped or formed. These defects may not be completely masked after the parts are painted.
Coating irregularity problems constituted a major reason why prior art workers have recently turned their attention to a one-side coated product (as exemplified by U.S. Pat. No. 4,082,868) wherein the uncoated side is the side to be painted on critical surface items made therefrom, even at the sacrifice of corrosion resistance on the non-galvanized side.
Yet another problem area encountered with conventional jet finishing involves coating weights and line speeds. The viscous interaction between the coating metal and the strip is proportional to strip speed. At slow speeds, the prior art was faced with the problem of ripple formation. To combat this, it was found that minimizing jet nozzle to strip distance and reducing the jet finishing pressure will minimize the prominence of coating ripples. However, low jet finishing pressure and close positioning of the jet finishing nozzles at the same time create an edge build-up problem. Prior art workers therefore have had to adjust the parameters to control edge build-up and ripples and this has necessitated higher line speeds. As an example, it has been common practice to use conventional jet finishing only with strip speeds above about 100 feet per minute (30 meters per minute) to produce commercial class coating weight (ASTM A525, G90). Edge build-up problems on G-90 coating commonly occur at speeds below about 150 feet per minute (45 meters per minute). Heavier coatings are even more difficult to control edge-to-edge uniformly.
Another essential practice in most prior art jet finishing operations is to position the jet nozzles virtually directly opposed, such that the jet streams are in direct interference beyond the edges of the strip. This interference results in extremely high and objectionable noise levels. Vertically offset jet nozzles cause a wrap-around effect with a bead of heavy coating metal along the edge on the side opposite the last nozzle operating on the strip. In addition to the noise problem and the need for precise adjustment of the jet nozzles by the operator, opposed operation can result in coating metal splatter being blown off of the strip edge by one nozzle and into the nozzle opening of the opposed nozzle.
Prior art workers have hitherto jet finished hot-dipped, two-side coated galvanized and aluminized strip with nitrogen. Such jet finishing, however, has been performed in an ambient atmosphere. In jet finishing, less nitrogen is required when nitrogen is used than air when air is used. However, the results achieved by such finishing are more nearly like those achieved in jet finishing with air in an ambient atmosphere than like the results achieved by the present method.
U.S. Pat. Nos. 3,505,042 and 3,505,043 teach hot dip coating of a ferrous metal with magnesium-zinc alloy and magnesium-aluminum-zinc alloy respectively. The first of these references utilized coating rolls for coating control and nitrogen gas solely for cooling after finishing between exit rolls. The second of these references does not disclose specific finishing means, but does enclose the coating apparatus in an atmosphere of 10% hydrogen with the balance nitrogen. The reference also mentions blowing nitrogen gas over the coated strip being withdrawn from the bath to rapidly cool the coating and to control coating weight, the nitrogen gas having a temperature below 100.degree. F. (40.degree. C.) and preferably about 50.degree. F. (10.degree. C.).
The present invention is based upon the discovery that if, in a conventional, continuous, hot-dip, two-side galvanizing process, the coating metal as it exits the coating bath is surrounded by an enclosure in which a substantially oxygen-free atmosphere is maintained and if within the enclosure the coated strip is jet finished with non-oxidizing or inert gas, the finishing problems encountered with conventional finishing methods are markedly reduced or eliminated. The finishing method of the present invention enables the practice of any of the above noted spangle minimizing techniques, greatly enhancing the results achieved and the uniformity of spangle minimization throughout the width of the strip. Furthermore, the markedly improved results are consistent.
The most significant aspect of the present invention, however, is the discovery that all coating control problems at the strip edges are completely eliminated with the substantial exclusion of oxygen from the finishing process. Minimum operating speeds are no longer limited by edge build-up problems, but rather only by the desired coating weight relative to the amount of coating metal naturally pulled up by the strip to the finishing jet nozzles. It has been found, for example, that excellent quality G-90 coatings can be produced without difficulty at speeds as low as 30 feet per minute (9 meters per minute).
Coating control at the strip edges is a very real problem in a two-side coating process where jet finishing cannot be accomplished against a back-up roll as in one-side coating processes. In the practice of the teachings of the present invention, heavy coating at the strip edges does not occur. Jet nozzles can be vertically offset, eliminating the need for precise positioning, greatly reducing noise, and eliminating the hazard of zinc splatter plugging opposed nozzles. Jet nozzle design may be simplified to utilize a slot-like nozzle opening of uniform width throughout its length, rendering unnecessary the multitude of special jet nozzle designs, methods and accessories which have been used for controlling edge build-up. Superior uniform coating thickness results edge-to-edge for all coating weights because the center profile need no longer be distorted to compensate for heavy edges. As a result, coils can be wound under high tension without spooling. Furthermore, with uniform coating weight edge-to-edge, less coating metal is used. The greatly reduced noise, by virtue of vertically offsetting the jet nozzles in an enclosure, represents a major step in safety and environment improvement. The simplified jet nozzle design results in more uniform coating, more uniform cooling and a flatter strip.
Heretofore, in the practice of conventional two-side jet finishing, neither the mechanism for ripple formation nor that causing edge build-up problems was completely understood. In the process of conventional jet finishing, a pneumatic dam effect is created whereby the desired amount of coating metal is metered through the jet barrier to form the finished coating. At this metering point the excess coating metal pulled up with the strip, beyond that required for the finished coating, is returned to the coating bath. This process is described in detail in U.S. Pat. No. 4,078,103.
While applicants do not wish to be bound by theory, it appears as a result of the present invention that the coating ripples and heavy edge coating in conventional jet finishing are caused entirely by coating metal oxide. At some point in the jet interaction region, probably just above the point of zero surface velocity , fresh (unoxidized) coating metal is being exposed and, as it is exposed, it immediately forms a very light oxide skin. The continuity of flow or distribution of this very light oxide skin onto the finished coating determines the occurrence of coating ripples. In conventional practice, the jet periodically restrains the oxide film. The film builds up until the jet no longer can restrain it. At this time a segment of relatively heavy oxide breaks off and passes with the finished coating. The segment as it passes carries with it coating beneath which is heavier than that which is metered on when the oxide film is restrained. This process is repeated many times each second as ripples are formed.
A similar mechanism is believed to be operable in creating heavy coating metal along the strip edges. However, at the edges, geometry becomes an additional important factor in that there is no wiping force directed against the edge surfaces. Relatively heavy oxide is permitted to pass through the jet interaction area more or less continuously carrying with it heavy coating beneath. This oxide envelope around each strip edge surface is the "container" which permits zinc wrap-around to occur when the jet nozzles are vertically offset.
Edge build-up of the molten coating metal is eliminated by the practice of the present invention by avoiding oxidation.
The zinc coated product produced by the method of the present invention (including spangle minimization) has such excellent surface qualities after temper rolling that it is suitable for use in exposed automotive body panels, appliance applications and the like.


The invention relates to a multilayer film or sheet structure containing at least one barrier layer, at least one predominantly propylene-based layer and at least one predominantly ethylene-based layer, and at least one predominantly ethylene-based adhesive layer.
Packaging films and sheets are increasingly manufactured by coextrusion systems of growing sophistication. Whereas many years ago, it was common to have machines capable of coextruding three to five layers, such systems today can routinely coextrude nine layers or more, using an equal number of extruders to feed these layers. The new systems allow many types of polymers to be used for better tailoring of multiple properties required in packaging structures, such as barrier, toughness, sealability, gloss, transparency, impact resistance, while lowering overall raw material cost by using less of the expensive components. The polymers themselves many be further blended with other polymers. Additives may be added to the polymers, such as slips or antiblocks, antifog, anti-oxidants, color masterbatches, and the like. Further, the increasing complexity of the material combinations also requires more complicated logistics and handling to ensure that the right materials are delivered to the right extruders during production and to maintain proper inventory economically.
Many packaging films and laminates contain layers of polar polymers such as polyamide and ethylene vinyl alcohol to provide gas and flavor barriers. With the increasing number of extruders in coextrusion systems it is not uncommon to not only have an ethylene vinyl alcohol layer or a polyamide layer, but also combinations of these layers. Tri-layer combinations of barrier cores or barrier sandwiches comprising a coextrusion of polyamide-ethylene vinyl alcohol-polyamide are widely employed as a method to improve formability in films and sheets. In many cases, the sealant side of the coextrusion construction, that is, the layers between the barrier core and the packaged product are frequently ethylene polymer-based to make use of their good sealing properties. Examples of such sealants are ethylene ionomers, ethylene acid copolymers, ethylene vinyl acetate copolymers, ethylene α-olefin copolymers. In many cases, the exterior side of the coextrusion construction, that is, the layers between the barrier core and the outer layer of the package that does not contact the packaging contents, is composed of propylene polymers. The propylene polymers provide stiffness, moisture barrier, and they also provide a higher temperature resistance that prevents the film laminate from being deformed when contacted against a sealing bar during heat sealing of such laminates. The temperatures of the seal bars can be very high, particularly for thicker laminates, as heat must be transferred from the seal bar to the internal sealant layer within the short contact times necessary for profitable commercial production. For that reason, it can also be common for polyamide to be employed as the outermost exterior layer of the film laminate with polypropylene layers internal to that layer on the exterior side of the coextrusion construction. Consequently, as many as three or more tie layers may be employed in nine or higher layer coextrusions. It would be ideal if a single adhesive resin could be used for all adhesive layers to avoid mistakes with charging the wrong adhesive into the extruder hoppers, and to minimize inventory complications with maintaining multiple resins.
Generally speaking, high crystallinity polypropylene (PP) and polyethylene (PE) polymers are not compatible with each other. Most crystalline polyethylene resins do not adhere well to polypropylene and vice-versa. Ethylene copolymer-based adhesives may be employed, such as ethylene vinyl acetate and ethylene methyl acrylate adhesives, but these adhesives do not have sufficient high temperature resistance and may fail when packages are subject to cooking conditions, particularly those at high temperatures and long times. Lower density ethylene-α-olefin copolymer or higher comonomer propylene-α-olefin copolymer based adhesives may also be used, but they suffer from the same temperature issues as they are also lower crystallinity resins because of their high comonomer. They are also more expensive than their lower or no-comonomer polyethylene and polypropylene resin counterparts.
U.S. Pat. No. 4,405,667 discloses a retortable packaging pouch where the sealant layer is polyethylene and the outer layer is a polyamide. Internal layers of polyamide and ethylene vinyl alcohol are described. The pouch can contain up to 9 layers where one or more of the layers is polypropylene-based. The sealant PE is bonded to the propylene layers by a blend of linear low density polyethylene and a propylene ethylene copolymer. The layer directly adhering to the nylon is an anhydride-modified polypropylene.
U.S. Pat. No. 4,735,855 discloses a thermoformable film laminate in which the sealant layer is an ionomer or ethylene copolymer and is directly adhered to both a nylon, ethylene vinyl alcohol, nylon barrier core and a polypropylene outer layer. The tie layers bonding to the barrier, the sealant and the outer polypropylene layers may be identical or different from each other and may include a wide range of anhydride grafted polyolefins. The examples demonstrate only anhydride modified ethylene vinyl acetate polymers as adhering the sealant and polypropylene to the barrier polymer.
U.S. Pat. No. 5,643,999 discloses a coextrudable adhesive composition, for bonding polyolefin film to ionomer film, produced by blending polyethylene with a very low density polyethylene (VLDPE) together with a hydrocarbon elastomer. However, such adhesive composition does not adequately bond polyolefin film layer to barrier layer, for water, oxygen or other substances, such as polyamide or ethylene vinyl alcohol (EVOH) layer.
U.S. Pat. No. 6,184,298 discloses an adhesive composition of an anhydride modified polyethylene, an unmodified polyethylene and a styrene-based elastomer as being useful in multilayer structures containing nylon or EVOH as the barrier, and having polypropylene as one substrate and polyethylene as another.
U.S. Pat. No. 7,713,636 discloses a multilayer film comprising a PP core layer, an outer barrier skin layer and an optional second skin layer on the opposite side of the core layer than the barrier skin layer, where the optional second skin layer is selected from the group consisting of a PE polymer or copolymer, a PP polymer or copolymer, an ethylene propylene copolymer and an ethylene vinyl acetate polymer. A tie layer is disposed between the skin and core layers, and comprises at least 10 w % grafted propylene-based polymer containing 5 to 24 weight % ethylene and having a DSC melting temperature of 120° C. or less and a heat of fusion of 75 J/g or less.
More recent commercial advances in α-olefin copolymerizations using single site or metallocene catalysts in C2 to C8 α-olefins have resulted in copolymers that have a more blocky characteristic, where the block segments themselves are ethylene α-olefin copolymers and different blocks are distinguished by different comonomer content to tailor the block crystallinity. Such copolymers have been found to improve adhesion between polypropylene and high density polyethylene when used as the tie layer material in experiments conducted by Case Western University. (P Dias et al, Polymer 2008; 49:2937-2946 and Y. Lin et al, Polymer 2011; 52:1635-1644). Here, the polymers are used at 100% in the tie layer on a lab line extruding a small tape of about 2 mm thick and 12 mm wide. Line speeds were not disclosed.
It is particularly desired that an adhesive composition that provides high bond strength to multilayer barrier films where one tie layer type can be used to bond polypropylene polymers and copolymers to a polar barrier substrate as well as to polyethylene polymers, ethylene α-olefin copolymers and ethylene copolymers such as ethylene acid ionomers, ethylene acid copolymers, ethylene vinyl acetate and ethylene acrylate copolymers. In particular, it is challenging to find a common tie layer to bond polypropylene and ethylene acid ionomers of sodium and highly neutralized ethylene acid ionomers within a multilayer barrier structure.


This invention relates generally to tools and relates, more particularly, to means for use when pounding, or driving, a post into the ground.
In my earlier U.S. Pat. No. 6,719,261, I described an apparatus for supporting a post, such as a metal t-post, which is to be driven into the ground by an individual. Briefly, that apparatus includes a platen base upon which an individual can stand while the post is being driven into the ground, and the base defines a through-opening which is disposed between the feet of the individual when the individual stands upon the base. A cavity-providing guide is mounted upon the base for slidably receiving a post inserted endwise therein and so that the cavity of the guide means is positioned in registry with the through-opening of the base. When an individual stands upon the base with his feet disposed on opposite sides of the through-opening and a post is positioned within the guide means, the post is supported by the guide means in a steady condition for being driven into the ground.
A limitation associated with the apparatus of my earlier patent relates to the fact that once the platen base of the apparatus is positioned upon the ground, the orientation of the post which is desired to be driven into the ground relative to the surface of the ground cannot be appreciably altered. In other words, in order to make a significant adjustment in the orientation of a post desired to be driven into the ground once the platen base of my patented apparatus is placed upon the ground, the position of the base will have to be re-adjusted.
Accordingly, it is an object of the present invention to provide a new and improved post support apparatus which is capable of supporting a post while it is being driven into the ground and which accommodates a substantial adjustment in the orientation of a post desired to be driven into the ground without requiring that the base of the apparatus be moved.
Another object of the present invention is to provide such an apparatus which is uncomplicated in structure, yet effective in operation.


1. Field of the Invention
The invention relates to a process for bending glass sheets and a device for supporting a glass sheet heated to the forming temperature in a horizontal position, said device consisting of an enclosure in which a partial vacuum can be established and of a contact surface provided with suction orifices directed downward and against which the glass sheet is held by a suction effect.
2. Discussion of the Background
Various processes for producing bent glass sheets are known, in particular automobile glazings, which use a support device consisting of an enclosure in which a partial vacuum is established and of a contact surface provided with suction orifices directed downward. The support device is used to lift the glass sheets, heated to the bending temperature in a tunnel furnace, above the horizontal conveyor belt and deposit them on a bending tool or on another conveying device. Various embodiments of these support devices, for example, have been proposed in the patent publication Nos. DE-2 000 271, EP-3391, EP-3392 and EP-182 638. In all known embodiments, the contact surface--against which the glass sheet is held by a suction effect--is a plate, of flat surface or slightly bent, provided with vertical bores or ducts leaving the contact surface and ending in an enclosure under a partial vacuum that can be regulated. As a general rule, the partial vacuum is obtained by means of a fan placed directly on this support device. The support device is mobile along the vertical plane and optionally in a horizontal plane.
The plate provided with suction orifices that the support devices according to the art comprise is generally of a specific ceramic. The ceramic plates are rather expensive, because all the ducts must be provided.
When these support devices are used, the entire top face of the glass sheet comes in contact with the lower face of the suction plate. The feel of the top face of the glass sheet is always unfavorable if the glass sheets are sensitive to direct contact. When the top face is provided with a sensitive overlayer, for example, with a layer of printed enamel which is then in the molten state considering the temperature of the glass, these support devices cannot be used because the layer of molten enamel sticks to the contact surface and is then destroyed or at least damaged by the mechanical contact.
It is also known how to shape a glass sheet conducted by a roller conveyor under an upper bending form and lifted by an ascending current of hot air which flattens the glass sheet against the upper bending form. The glass sheet is then retrieved by a tempering frame which transfers it between blowing boxes. This process is described in a detailed manner in French Patent No. 2 567 508. The upper bending form, in this case, does not need to be pierced and is therefore less expensive. Moreover, the current of hot air acts on the entire lower face of the glass, therefore, in a way there is a pneumatic pressing which assures a very good shaping quality. However, in this process the energy expenditures are rather great because the hot air current is established for a long period of time.


It has long been known that a plurality of nanocrystallites in silicon carbide (SiC) would give rise to an enlargement of the energy gap of the SiC shifting any emitted light towards the UV region because of quantum confinement, which allows the relaxation of momentum selection rules by confining the charge carriers spatially, thus allowing direct band gap transitions. See U.S. Pat. No. 5,376,241 entitled, “Fabricating Porous Silicon Carbide” by A. D. Kurtz et al., which issued on Dec. 27, 1994 and is assigned to Kulite Semiconductor Products, Inc, the assignee herein. In that particular patent, it teaches the formation of porous SiC, which is formed under electrochemical anodization. The patent also describes the production of the semiconductor through the use of ultraviolet light to illuminate the surface of the semiconductor. In this manner, by controlling the light intensity, the potential and THE doping level, a porous layer is formed in the semiconductor and thus one produces porous SiC. The porous SiC can be employed for UV light sources, such as LEDs and diode lasers. Porous SiC can be utilized as a filtering chemical process to be used to provide heterojunction devices.
See U.S. Pat. No. 5,376,818 entitled, “Large Area P-N Junction Devices Formed from Porous Silicon” issued on Dec. 27, 1994 to A. D. Kurtz et al. and assigned to the assignee herein. That patent shows the formation of porous SiC, which is produced under electrochemical anodization. The patent teaches that when a potential is applied to the semiconductor and ultra-violet light illuminates the surface of semiconductor, one can control the light intensity, the potential in doping level, to form a microporous structure in the semiconductor to thus produce porous SiC. The structure enhances the quantum confinement of energetic carriers and which device is highly sensitive to stress.
Reference is also made to U.S. Pat. No. 5,834,378 entitled, “Passivation of Porous Semiconductors for Improved Optoelectronic Device Performance and Fabrication of Light-Emitting Diode Bases on Same”. The patent issued on Nov. 10, 1998 to A. D. Kurtz et al. and is assigned to the assignee herein. That patent describes a method which improves the photoluminescent performance of a porous semiconductor. According to the method, a monolayer of passivating material is generated on a pore wall of the porous semiconductor to passivate the porous semiconductor. This layer substantially eliminates dangling bonds and surface states which are associated with the porous semiconductor layer. The resulting passive porous semiconductor layer exhibits a quantum efficiency of approximately five percent. It is indicated that one monolayer of passivating material can be an oxide which is generated by placing the bulk semiconductor substrate into a furnace. Also described is a heterojunction light emitting device which employs a passivated porous semiconductor layer.
U.S. Pat. No. 5,939,732 issued on Aug. 17, 1999 and is entitled, “Vertical Cavity Emitting Porous Silicon Carbide Light Emitting Diode Device and Preparation Thereof” and is assigned to the assignee herein and is invented by A. D. Kurtz et al. That patent teaches a multi-layered light emitting device, which has an active light emitting layer of porous silicon carbide and a sequence of layers of porous SiC underneath which serve as a quarter wavelength multi layer mirror. In this manner, one obtains electroluminescent emission of narrow visible light in the deep blue to UV range in a highly directed pattern. Thus, as indicated above, the nanocrystallites in SiC give rise to an enlargement of the energy gap and shifts emitted light towards the UV region. The same effect has also been demonstrated in silicon. Moreover, when LEDs are made from such materials, the emitted light is shifted towards the UV, the shifting inversely proportional to the size of the nanostructure. It is also well-known that the width of the energy gap may also be effected by the application of stresses (see for instance, deformation potentials). The use of deformation potentials as effecting the energy gap is well-known and is text book material. Thus, it is indicated and known that the effect of stress can cause a change in the frequency of emitted light of an LED or the light resonance of the structure.
In graphite, a similar effect can occur. Normal graphite is a semi-metal, but in a nanostructure it can be a conductor or a semiconductor. For example, see an article entitled, “Nanotubes for Electronics”. This article appeared in Scientific American in the December 2000 issue. The article describes nanotubes and is written by Phillip G. Collins and Phaedon Avouris. In that article it is clear that nanotubes are utilized because of their unique electronic properties. Carbon nanotubes essentially can be used to perform the same function as silicon does in electronic circuits, but at a molecular scale, where silicon and other semiconductors do not work. In particular, when the dimensions of the nanotube are of the same order of magnitude as the electron wavelength, then these quantum effects can occur at those dimensions.
See also an article entitled, “Cavity Quantum Electrodynamics” which appeared in Scientific American in April, 1993 by Serge Haroche and Jean-Michel Raimond. This article explains the operation of atoms and photons and their behavior in small cavities. The article shows that new sensors can be developed utilizing such techniques.
In any event, because of the function and operation of nanotubes, it has been determined that application of stress can change a conductor to a semiconductor by changing the energy gap where the quantum confinement leads to a large change in the electrical properties. Essentially, the electrical properties of nanostructures, such as nanotubes, which exhibit quantum confinement can be changed by the application of various stresses, thus leading to a means of measuring such stresses.
Therefore, the present invention contemplates the formation of a high frequency, high temperature sensor which employs nanotubes and where the nanotubes are subjected to pressure or other external conditions to vary the electrical properties of the nanotubes according to a desired application.
The nanotubes, which are conductive, will respond to an applied pressure to produce an output voltage or current proportional to the amount of pressure applied. These devices, because of their high temperatures properties, as well as because of the electrical properties provide improved transducer structures or sensor structures useful in generating sensors in the optical and microwave ranges.


I. Field of the Invention
The present invention generally relates to material structures that include ductile, lightweight, high fatigue strength and high fracture strength characteristics. More particularly, this invention relates to a system and method for providing ease of mobility and protecting a host against an impacting ballistic element.
II. Detailed Description of the Prior Art
Many typical examples of systems, such as airplanes, spacecraft, cars, tanks, boats, buildings and personnel are subjected to ballistic impact by projectiles. For example, among others, a ballistic element includes a bullet directed at personnel, an artillery shell impacting a tank, a missile fired at a ship, a high speed particle hitting a satellite, and flying debris impacting an automobile or window. Impacts by ballistic elements often result in catastrophic or terminal damage to these systems. To mitigate or prevent impact damage, structural systems are often armored with laminates, i.e. protective layers of material deposited on the system, or are structurally composed of an anti-ballistic material.
Unfortunately, armored systems are often heavy and slow moving in that the mass density of armor typically increases with increasing ballistic protection. Thus, there exists an increased risk of detrimentally compromising the overall performance of a system as more armor is added to the system. For example, to adequately protect military aircraft from potential ballistic threats, weight from added armor protection could prevent an aircraft from maneuvering, mobilizing over long distances, or even limit the performance of basic flight operations such as taking off and landing for example. In another example, to protect a satellite system from impacts from celestial projectile particles, satellite components are often plated with armor but any increased weight from the armor would dramatically increase the cost for delivering that satellite payload into space.
All of these existing types of armor suffer from the inability to provide a lightweight material having high fatigue and fracture strength. Many typical examples that provide protection against ballistic elements include either a thick and heavy armor-type or a lighter armor type that provides easy mobility but with less ability to sustain a ballistic impact than heavy armor. Heavy armor types typically provide greater fatigue and fracture strength whereas lightweight composites provide greater mobility while often compromising fracture and fatigue strength.
Illustratively, tanks, ships, and armored personnel vehicles typically include armor often having metallic or other high density components that render such devices as bulky, heavy, and slow moving. However, to provide greater requisite mobility, lightweight armor often includes composite materials that are brittle and sacrifice the fatigue and fracture strength provided by heavy armor. Some examples of lightweight armor include protective material for aerospace applications and for personnel such as bulletproof vests and helmets.
For example, a typical tank includes heavy, bulky armor for sustaining engagement with a wide range of ballistic elements in combat. However, the weight associated with the armor often makes the tank difficult to move. For example, a tank may encounter difficulty during military maneuvers or as the tank is mobilized to the theatre front. For one specific example, a US-made M1 Abrahams tank, although ideal for sustaining projectiles at high speeds, incorporates a uranium-based armor. During mobilization to the theatre front, this armor prohibits the M1 tank from transport through ideal avenues of air and truck transport exclusively to the slower options of by ship or rail due to the extreme weight of the uranium armored tank. On the other hand, lightweight armor provides for ease of movement but often compromises the ability to sustain a greater range of projectile sizes and/or projectile speeds as that of heavier armor. Armored aircraft, such as for example tactical or strategic aircraft, require lightweight armor for optimal maneuverability through the air. For tactical aircraft, graphite-epoxy composites provide lightweight armored protection against a narrow range of projectile sizes and/or speeds.
In short, existing types of armor do not provide for the aspects of lightweight as well as high fatigue and fracture strength. Many other problems and disadvantages of the prior art will become apparent to one skilled in the art after comparing such prior art with the present invention as described herein.


The present invention pertains to an improved irrigator aspirator tip component of the type inserted into the lens capsule of an eye, such as for removing cortical material, washing, cleaning and/or polishing.


An internal combustion engine may be equipped with an air charging system designed for supplying air into the combustion chambers. The air charging system generally includes an intake pipe that conveys air from the ambient environment to an intake manifold in fluid communication with the combustion chambers. An intake valve is generally disposed in the intake pipe. The intake valve has an actuator arranged to move a valve member that regulates the mass flow rate of the air that flows towards the intake manifold.
The air charging system may also comprise a turbocharger provided for increasing the pressure of the air in the intake manifold. The turbocharger comprises a compressor located in the intake pipe and a turbine that rotates the compressor by receiving exhaust gasses from an exhaust manifold in fluid communication with the combustion chambers. To regulate the rotational speed of the compressor, the turbine may be a variable geometry turbine (VGT) having an actuator arranged to alter the angular position of the turbine inlet vanes. The air charging system may comprise an additional air compressor located in the intake pipe and driven by an electric motor.
The air charging system may further comprise one or more exhaust gas recirculation (EGR) pipes for recirculating a portion of the exhaust gasses from the exhaust manifold back into the intake manifold. Each EGR pipe is generally provided with an EGR valve having an actuator arranged to move a valve member that regulates the mass flow rate of the recirculated exhaust gasses.
During the operation of the engine, the actuators of the air charging system, such as the EGR valve actuator(s), the VGT actuator, the intake valve actuator and the electric motor of the air compressor, are used to regulate a number of output parameters of the air charging system, for example the pressure inside the intake manifold, the oxygen concentration inside the intake manifold and the pressure inside the exhaust manifold, according to performance and emissions requirements.
To perform this function, these actuators are conventionally controlled according to separated and uncoordinated control strategies, which enable each individual actuator to be operated in any desired or required position, independently from one another.
Accordingly, it is desirable to provide improved control strategies for an air charging system. In addition, it is desirable to coordinate the control strategies of the actuators in the air charging system. Furthermore, other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.


A PWM converter is known as a device which performs switching control performed by PWM to thereby suppress a harmonic current included in a load current for an AC power source driving a motor driving device in order to improve power.
A PWM converter outputs a square wave AC voltage including high frequencies of several kHz or more on a path between the AC power supply and the PWM converter to perform switching control by the PWM. As the square wave AC voltage includes high frequency components not included in the power supply frequency, this type of PWM converter is generally configured to provide a low pass filter (LC filter) which allows a high frequency square wave AC voltage to pass between the AC power source and the converter in order to remove the high frequency waves.
FIG. 1 illustrates an example of a basic configuration of an LC filter. FIG. 1 illustrates a configuration where the LC filter 1001 is positioned between the PWM converter 1002 and a three-phase AC power supply 1000.
The LC filter 1001 for the PWM converter is configured to be equipped with a so called T-filter which comprises capacitors C1 to C3 whose ends have an inductance of La1 to La3 and Lb1 to Lb3 respectively. Generally two AC reactors 1010 and 1020 for realizing two inductances have similar configurations (the cores are positioned in the same direction). Further, in general, AC reactors are of a natural air cooling type (for example Japanese unexamined patent publication No. 2007-221858 (JP 2007-221858 A)).
Regarding the inductances L of the two AC reactors 1010 and 1020, in order to suppress the peak of the high frequency current flowing in from the PWM converter 1002 side, the L of the PWM converter side increases and the L of the AC power source 1000 side decreases. Therefore, in general, the volume of the AC reactor B (1020) on the PWM convertor side is comparatively larger than that of the AC reactor A (1010) of the AC power source side. Further, in general, the outer shape of the AC reactor is a parallelepiped about which the coil is wound.
Further, a large part of the loss generated in inductance is on the PWM convertor side where high frequency current flows. Therefore, high frequency current only flows through the AC reactor B on the convertor side (1020) which further increases the temperature rise.
Conventionally, due to AC reactors being large and heavy, two AC reactors and a capacitor, etc., constituting an LC filter were not housed in the same casing.
If these two AC reactors were to be housed in the same casing, there would be a problem that a useless space would be created due to the difference in the height between the small AC reactor on the power source side and the large AC reactor on the convertor side and the volume of the casing would be large.
The object of the present invention is to enable efficient cooling of the AC reactors and provide an LC filter which allows miniaturization and reduction in weight of a casing which houses the LC filter part.


The grinding of wooden frames causes problems since the grain fiber directions of the longitudinal and transverse wooden parts of the frame are different, and it is desirable that the upper surface of a frame wooden part not be ground transversely to its fiber direction.
To avoid this disadvantage, band grinding machines are already known in which for a cross-grinding, a transverse band assembly and a broad band assembly are arranged behind one another in the advancement direction. The transverse band first grinds the top of the entire frame. The broad band assembly has two pressure shoes or pressure bars arranged parallel to the advancement direction which are adjustable transversely to the advancement direction so that the broad band can targetly be pressed against the longitudinal wooden parts of the frames to be ground. Therefore, the grinding tracks produced on the wooden longitudinal parts by the transverse band can be removed. A disadvantage of this solution is, however, that the grinding band of the broad band assembly is worn only locally.
In a further known cross-grind grinding machine, the broad band by means of an electronically controlled multiple member pressure bar is pushed downwardly in areas corresponding to the longitudinal wooden pieces. Also in this case, there arises the disadvantage that the broad band is only locally worn. Moreover, problems arise in the adjustment of the grinding width to the actual longitudinal wooden piece width, since the individual pressure elements of the pressure bar cannot be made as small as desired and, therefore, the danger exists that the longitudinal wood pieces are either not ground up to their longitudinal edges or that the longitudinal edges are ground round.
The invention has as its object the provision of a band grinding machine of the aforementioned kind which permits a desired grinding of the work piece parts parallel to their grain fiber directions with optimal utilization of the used grinding means.