1. Technical Field
The present invention relates to data processing and, in particular, to scripts in a network data processing system. Still more particularly, the present invention provides a method, apparatus, and program for evaluating scripts.
2. Description of Related Art
The worldwide network of computers commonly known as the “Internet” has seen explosive growth in the last several years. Mainly, this growth has been fueled by the introduction and widespread use of so-called “web browsers,” which enable simple graphical user interface-based access to network servers, which support documents formatted as so-called “web pages.” These web pages are versatile and customized by authors. For example, web pages may mix text and graphic images. A web page also may include fonts of varying sizes.
A browser is a program that is executed on a graphical user interface (GUI). The browser allows a user to seamlessly load documents from the Internet and display them by means of the GUI. These documents are commonly formatted using markup language protocols, such as hypertext markup language (HTML). Portions of text and images within a document are delimited by indicators, which affect the format for display. In HTML documents, the indicators are referred to as tags. Tags may include links, also referred to as “hyperlinks,” to other pages. The browser gives some means of viewing the contents of web pages (or nodes) and of navigating from one web page to another in response to selection of the links.
Browsers may also read and interpret pages including scripts, such as JAVAScript or JScript. JAVAScript is a popular scripting language that is widely supported in Web browsers and other Web tools. JAVAScript adds interactive functions to HTML pages, which are otherwise static, since HTML is a display language, not a programming language. JScript is similar to JAVAScript, but has extensions specifically for the Microsoft Windows environment.
Different Web browser software applications support scripts to different degrees. In fact, different versions of a browser application may support scripts differently. The rivalry between browsers in the market, such as Netscape Navigator by Netscape Communications and Internet Explorer by Microsoft Corporation, has led to a disparity between standards. Netscape uses different syntax with JAVAScript than Internet Explorer uses with JScript.
Browser and platform dependent script functions can cause a nightmare for script development, testing, and maintenance. Therefore, it would be advantageous to provide an improved script evaluator for determining browser support.


Titanium-aluminium (Ti—Al) alloys and alloys based on titanium-aluminium (Ti—Al) inter-metallic compounds are very valuable materials. However, they can be difficult and expensive to prepare, particularly in the powder form. This expense of preparation limits wide use of these materials, even though they have highly desirable properties for use in aerospace, automotive and other industries.
Reactors and methods for forming titanium-aluminium based alloys have been disclosed. For example, WO 2007/109847 discloses a stepwise method for the production of titanium-aluminium compounds and titanium alloys and titanium-aluminium inter-metallic compounds and alloys.
WO 2007/109847 describes the production of titanium-aluminium based alloys via a two stage reduction process, based on reduction of titanium tetrachloride with aluminium. In stage 1, TiCl4 is reduced with Al in the presence of AlCl3 to produce titanium subchlorides according to the following reaction:TiCl4+(1.333+x)Al→TiCl3+(1+x)Al+0.333AlCl3 or  (1)TiCl4+(1.333+x)Al→TiCl2+(0.666+x)Al+0.666AlCl3  (1)
In stage 2, the products from reaction (1) are processed at temperatures between 200° C. and 1300° C. to produce a powder of titanium-aluminium based alloys, according to the following (simplified) reaction scheme:TiCl3+(1+x)Al→Ti—Al+AlCl3 or  (2)TiCl2+(0.666+x)Al→Ti—Alx+0.666AlCl3  (2)


The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Fuel cells are useful as a power source for electric vehicles and other applications. An exemplary fuel cell has a membrane electrode assembly (MEA) with catalytic electrodes and a proton exchange membrane (PEM) formed between the electrodes. Water is generated at the cathode electrode based on the electrochemical reactions between hydrogen and oxygen occurring within the MEA. Gas diffusion media plays an important role in PEM fuel cells. Generally disposed between catalytic electrodes and flow field channels that introduce reactant gases into the fuel cell, the gas diffusion media provide pathways for reactant to diffuse to the electrode and pathways for removal of the product water, electronic conductivity, and heat conductivity, as well as mechanical strength needed for proper functioning of the fuel cell.
During operation of the fuel cell, water is generated at the cathode based on electrochemical reactions involving hydrogen and oxygen occurring within the MEA. Efficient operation of a fuel cell depends on the ability to provide effective water management in the system. For example, the diffusion media prevent the electrodes from flooding (i.e., filling with water and severely restricting O2 access) by removing product water away from the catalyst layer while maintaining reactant gas flow from gas flow channels of the bipolar plate through to the catalyst layer.
Fuel cell stacks can contain a large number of fuel cells depending on the power requirement of the application. For example, typical fuel stacks have up to 400 individual fuel cells and more. Because the fuel cells in the stacks operate in series, a weakness or poor performance in one cell can translate into poor performance of the entire stack. For this reason, it is desirable for every fuel cell in the stack to operate at high efficiency.
Typical manufacturing steps for gas diffusion media include manufacturing a carbon fiber paper, impregnating the paper with resin or a mixture of resin and fillers, molding the impregnated paper, and carbonization or graphitization of the resin-impregnated carbon fiber paper. The steps of manufacturing paper and impregnation are continuous, while the molding, carbonization and graphitization steps may be either batch or continuous.
Because typical fuel stacks contain so many individual fuel cells, it is important for the manufacturing process of the diffusion media to have a high degree of reliability. Improvements in the manufacturing process that reduce cost, simplify the process, or enhance performance of the media are thus desirable.


Many implanted medical devices that are powered by electrical energy have been developed. Most of these devices comprise a power source, one or more conductors, and a load.
When a patient with one of these implanted devices is subjected to high intensity magnetic fields, currents are often induced in the implanted conductors. The large current flows so induced often create substantial amounts of heat. Because living organisms can generally only survive within a relatively narrow range of temperatures, these large current flows are dangerous.
Furthermore, implantable devices, such as implantable pulse generators (IPGs) and cardioverter/defibrillator/pacemaker (CDPs), are sensitive to a variety of forms of electromagnetic interference (EMI). These devices include sensing and logic systems that respond to low-level signals from the heart. Because the sensing systems and conductive elements of these implantable devices are responsive to changes in local electromagnetic fields, they are vulnerable to external sources of severe electromagnetic noise, and in particular to electromagnetic fields emitted during magnetic resonance imaging (MRI) procedures. Therefore, patients with implantable devices are generally advised not to undergo magnetic resonance imaging (MRI) procedures, which often generate static magnetic fields of from between about 0.5 to about 10 Teslas and corresponding time-varying magnetic fields of about 20 megahertz to about 430 megahertz, as dictated by the Lamor frequency (see, e.g., page 1007 of Joseph D. Bronzino's “The Biomedical Engineering Handbook,” CRC Press, Hartford, Conn., 1995). Typically, the strength of the magnetic component of such a time-varying magnetic field is about 1 to about 1,000 microTesla.
One additional problem with implanted conductors is that, when they are conducting electricity and are simultaneously subjected to large magnetic fields, a Lorentz force is created which often causes the conductor to move. This movement may damage body tissue.
In U.S. Pat. No. 4,180,600, there is disclosed and claimed a fine magnetically shielded conductor wire consisting of a conductive copper core and a magnetically soft alloy metallic sheath metallurgically secured to the conductive core, wherein the sheath consists essentially of from 2 to 5 weight percent of molybdenum, from about 15 to about 23 weight percent of iron, and from about 75 to about 85 weight percent of nickel. Although the device of this patent does provide magnetic shielding, it still creates heat when it interacts with strong magnetic fields.
It is an object of this invention to provide a sheath assembly, which is shielded from magnetic fields.


1. Field of the Invention
This invention pertains to the general field of optical filters and, in particular, to temperature-stable and tunable high-performance etalon filters.
2. Description of the Prior Art
Etalons are well known optical devices that consist of two reflective surfaces parallel to one another and spaced apart by solid spacers to produce a predetermined optical length (the “cavity length”). They may consists simply of a solid parallel plate with reflective surfaces (so called “solid etalons”) or of two plates with an air gap between them that defines the cavity (so called “air-spaced etalons”), as illustrated in FIG. 1. A hybrid form of etalon (so called “re-entrant etalon”) utilizes an additional solid structure with a reflective surface (a “riser”) between the two plates in order to achieve narrower cavity lengths than practically obtainable with the use of spacers.
When illuminated with a broadband collimated light, etalons produce a transmission beam and a reflection beam with periodic spectra characterized by very narrowband spikes centered at wavelength determined by the physical properties and dimensions of the etalon. A typical etalon transmission spectrum is illustrated in FIG. 2. With reference to air-spaced etalons, in particular, the specific center wavelength λ′ of the passband (the spectral spike) and the period between spectral spikes (commonly referred to in the art as channel spacing or free spectral range—FSR—of the device) are a function of the optical length of the etalon's cavity. This disclosure is limited to a discussion of transmission operation because those skilled in the art would readily understand that it is similarly applicable to reflection operation.
In particular, referring for example to the etalon 10 and the intensity spectrum 12 of FIGS. 1 and 2, respectively, minor changes in the optical length L (corresponding to the geometric length L′ shown in the figures) of the cavity 14 will cause a shift of the periodic spectrum along the wavelength axis, as indicated by arrows 16. As is well understood by those skilled in the art, varying the optical length L of the cavity also produces a change in the width of the spectral spike and in the free spectral range of the etalon.
These properties of etalons are very advantageous for many optical applications. In particular, etalons are used as high-performance filters to isolate light of a very a precise frequency, as may be needed for a particular application. In telescopic astronomy, for instance, such filters are particularly useful for observing objects at specific wavelengths. Since the exact wavelength of each peak is a function of the exact optical length L of the cavity, it has been most important in the art to build etalon filters with precise and uniform spacing between the two plates (18,20) constituting the etalon (FIG. 1). To that end, very precisely machined spacers 22,24 of equal thickness L′ are used, typically uniformly distributed around the annular periphery of the plates in a sufficient number to separate the plates and produce a cavity of uniform optical length L. Moreover, these spacers are typically made of materials having a low coefficient of thermal expansion. (It is noted that L′ is the physical cavity length corresponding to the desired optical path length L, the two quantities being related by the equation L=nL′, where n is the index of refraction of the medium in the cavity.).
In practice it has been difficult and expensive to achieve the desired degree of perfection because of the very narrow tolerances (in the order of nanometers) required for the level of performance associated with extremely narrowband applications. U.S. Pat. Nos. 6,181,726 and 6,215,802 disclosed several advances over the prior art whereby the uniformity of the etalon's optical length was improved. According to one approach described in the patents, all the spacers used to form the etalon are selected from a common local area of a spacer substrate produced by standard-precision optical manufacturing techniques. It was discovered that, as a result of this selection, the spacers tend to have substantially more uniform thickness and, therefore, they produce a more uniform etalon cavity. According to another, complementary approach, an additional spacer from the same local substrate area is used at the center of the etalon, thereby providing a correction to plane deformations produced by the optical contact of the peripheral spacers with the etalon plates.
While the techniques described in these patents provide a significant improvement over the etalons previously known in the art, they are very labor-intensive and therefore expensive to practice. In addition, the resulting etalons, while more uniform in the optical length of the cavity, are not necessarily tuned to the precise desired wavelength. Copending U.S. Ser. No. 10/795,167 discloses a solution to this problem based on the use of counterbalanced forces applied to the etalon elements. This approach constitutes another significant advance in the art, but it does not address the problem of changes in performance (in terms of center wavelength and FSR) produced by thermal variations. Therefore, there is still a need for an etalon structure that is relatively insensitive to thermal effects and that produces extremely accurate tuning of the optical length of the etalon cavity. The present invention provides a solution to this remaining challenge that also produces a greater range of angular acceptance and a mechanism for thermally tuning the etalon to a precise level of performance.


In general, this invention relates to photographic film cassettes and, more particularly, an improved pressure pad spring and cassette arrangement therefor which avoids diminishing spring effectiveness and improves overall cassette assembly.
Multipurpose film cassettes have been developed in which a strip of photographic film is operated so as to be exposed, processed and projected without leaving the cassette. Film cassettes of this type are disclosed in several U.S. patents assigned in common with the present invention.
In film cassettes of this category, a supply of light sensitive photographic film can be selectively exposed in a camera particularly adapted to receive and operate the cassette. To process or develop the exposed film, the cassette is removed from the camera and placed in a player or processing and viewing apparatus capable of activating a cassette contained processor for depositing a desired uniform layer of processing fluid on the film's exposed emulsion surface. During such processing a conventional series of successive, positive transparent images on the exposed film is developed. Following processing in the manner indicated, the player apparatus is operated as a projector. During projection, the film is incrementally advanced, frame-by-frame, past a light source. Accordingly, the series of positive transparent images of the scenes to which the film were exposed are capable of being successively viewed while being projected onto a screen.
Towards the end of achieving the desired and critical fluid thickness on the film strip, as well as for avoiding blemishes in the developed transparent images, the cassette contains a spring-biased pressure pad yieldably supporting the film strip between the pad and a fluid processor nozzle structure.
The current state-of-the art with respect to achieving this uniform and substantially blemish free coating is represented by the disclosure of U.S. Pat. No. 3,951,530 issued Apr. 20, 1976 to Frank M. Czumak, Paul B. Mason and Joseph A. Stella, which patent is commonly assigned with the present invention. In the disclosure of this patent, the film's emulsion surface is yieldably urged into sliding engagement with the processor nozzle so that a uniform and predetermined gap exists between the emulsion surface and a doctoring surface formed on the nozzle. Formation of the desired fluid thickness is effected after the fluid has been deposited onto the film and passes the doctoring surface positioned downstream, in the direction of film advancement during processing, of a nozzle opening. This formation is facilitated by the doctoring surface being configured to develop positive hydrodynamic pressures in the deposited fluid which force the film strip into sliding engagement with the pressure pad. To resist this tendency, the pressure pad spring must be constructed to retain the desired gap spacing despite the presence of these hydrodynamic pressures. Also, the biasing force of the spring is selected to provide a net balance of forces on the film strip. This is accomplished by selecting the spring biasing force to be substantially equal and opposite to the hydrodynamic pressures. As a result foreign particles, such as dust or the like, on the emulsion surface of the film will effect a slight instantaneous increase in the gap between the doctoring surface and such emulsion surface and be permitted to pass therebeneath. Consequently, foreign particles will not be trapped and the possibility of blemishes occurring on the developed film is substantially eliminated, it being understood that these particles, in themselves, are inconsequential to either processing or developing because of their minute size. It will be appreciated, therefore, the spring force of the spring must be carefully controlled, otherwise the foregoing functions of the spring will result in significant operational problems. The type of spring described in the foregoing identified patent, which is the kind typically used in cassettes of this category, is a thin leaf spring having one end staked to the cassette, and the other end contacting and biasing the pressure pad. While the leaf spring performs satisfactorily there is potential for problems arising from the fact that the spring can be overstressed and thereby have adversely altered the noted preselected biasing force. Usually the problems of overstressing arise by virtue of the cassette assembly operations wherein an operator must periodically bend and thereby possibly overstress the spring in order to produce the completed film cassette. Aside from this potential problem use of the conventional leaf spring in its present embodiment necessitates relatively costly assembly procedures because of the staking operation.
It follows, therefore, that avoidance of overstressing the spring biasing the pressure pad during assembly is a major focal point of attention to overall film cassette development.
Moreover, the potential of the foregoing problems is further compounded by the requirement the cassette and its components including the pressure pad spring must be capable of mass production manufacturing techniques as well as be within tolerance levels incident to such techniques for the system to be acceptable in a competitive commercial market. Accordingly, the structural organization of components by which the film is supported in predetermined relationship to the doctoring surface is important to the overall system.


1. Field of the Invention
This invention is related to laser systems. In particular, this invention deals with adjusting alignment of laser beams in laser systems.
2. Description of the Related Art
When fabricating memory circuits, a laser repair system can be used to selectively sever conductive links, effectively removing faulty memory cells from the circuit.
As the size and spacing of link elements decreases, laser repair systems have had to increase in accuracy in order to perform their intended function. The complexity of a laser repair system capable of such accurate operation is significant. Multiple mirrors and other optical elements are used to generate and position a laser beam spot for severing a conductive link. Like the circuit fabrication process itself, laser repair systems are subject to many complex factors. For example, thermal expansion may lead to changes in the orientation or position of optical elements in the path of a laser beam. These changes to the elements that affect the laser beam can cause the laser beam spot to drift away from its intended location and can cause errors when trying to repair a circuit. Although the beam spot position is aligned with reference to wafer alignment markers with every new wafer processed, a misaligned laser beam path that deviates from a normal orientation to the work surface can still produce beam spots of unintended location, shape and/or size which adversely affect operation of the repair system.
U.S. Pat. No. 6,483,071 (hereinafter referred to as the '071 patent) entitled “Method and system for precisely positioning a waist of a material-processing laser beam to process microstructures within a laser-processing site” is assigned the assignee of the present invention. The disclosure of the '071 patent is hereby expressly incorporated by reference in its entirety. The '071 patent discloses many features of a laser based system for memory repair, and is particularly related to accurate (sub-micron) and high-speed positioning of a laser beam waist relative to a link or similar target structure. In the '071 patent, an air-bearing based assembly was disclosed for positioning of optical components (e.g: an objective lens) along the optical (Z) axis. In addition to noise and reliability issues (ie: wearing mechanical parts) it was recognized that X,Y displacement errors during Z axis motion are much better controlled or eliminated with an air bearing system. Such displacements, even if a fraction of a micron, can lead to link severing results which are incomplete (e.g. contamination) or possibly cause damage to surrounding structures. Hence, a displacement of a laser beam from a target location by a fraction of one-micron, corresponding to a fraction of one spot diameter, may generally lead to reduced yield.
Traditionally, laser repair systems have undergone periodic, manual adjustment to correct problems with alignment. For example, every month, a trained technician may have to manually adjust optical elements in order to correct alignment problems that have developed since the last adjustment. In the M430 laser link blowing machine from GSI, coarse adjustments to laser beam alignment were made by manually adjusting the laser beam orientation while viewing the laser beam spot with a “thru-lens viewing system” (TTLV). The TTLV is essentially a camera and TV monitor arrangement coupled to the laser beam path. The spot position was determined relative to a crosshair. The beam was first aligned to be centered in the lens aperture. Then the beam was aligned for zero spot translation during zoom expansion. Zoom adjustments corresponded to a range of spot sizes. If the beam was properly aligned along the Z-axis, the beam would appear stationary on the monitor for all zoom settings. Finer beam alignment was carried out by adjusting the spot size to a minimum, placing a calibration grid on the work surface, and performing iterative manual adjustments of turning mirrors to align the optical system and reduce any lateral (X-Y) displacement to within a specified tolerance.
This traditional approach to adjusting the alignment of a laser beam has several drawbacks. For example, the means used by the technician to determine beam alignment may itself be subject to error. Alignments based on erroneous alignment data may augment alignment problems in the system. Other problems may include the significant time expense involved in manual adjustment. Delays arising from manual alignment can represent a serious cost for businesses operating laser repair systems. For these reasons and others, automated methods of static laser beam alignment have been developed. Such methods are described for example in U.S. Pat. Nos. 5,011,282 to Ream, et al., 5,315,111 to Burns, et al., 5,923,418 to Clark et al., and 6,448,999 to Utterback et al. Of these prior patents, Burns, Clark, and Utterback split off portions of the laser beam to optical detectors placed adjacent to the laser beam path. Alignment of the beam with respect to the detectors is used to deduce alignment of the beam to the workpiece. In the '282 patent to Ream, changes in laser beam spot position on a target are used to determine a laser beam deviation angle, which can then be used to correct the laser beam path alignment.


Ocular hypotensive agents are useful in the treatment of a number of various ocular hypertensive conditions, such as post-surgical and post-laser trabeculectomy ocular hypertensive episodes, glaucoma, and as presurgical adjuncts.
Glaucoma is a disease of the eye characterized by increased intraocular pressure. On the basis of its etiology, glaucoma has been classified as primary or secondary. For example, primary glaucoma in adults (congenital glaucoma) may be either open-angle or acute or chronic angle-closure. Secondary glaucoma results from pre-existing ocular diseases such as uveitis, intraocular tumor or an enlarged cataract.
The underlying causes of primary glaucoma are not yet known. The increased intraocular tension is due to the obstruction of aqueous humor outflow. In chronic open-angle glaucoma, the anterior chamber and its anatomic structures appear normal, but drainage of the aqueous humor is impeded. In acute or chronic angle-closure glaucoma, the anterior chamber is shallow, the filtration angle is narrowed, and the iris may obstruct the trabecular meshwork at the entrance of the canal of Schlemm. Dilation of the pupil may push the root of the iris forward against the angle, and may produce pupillary block and thus precipitate an acute attack. Eyes with narrow anterior chamber angles are predisposed to acute angle-closure glaucoma attacks of various degrees of severity.
Secondary glaucoma is caused by any interference with the flow of aqueous humor from the posterior chamber into the anterior chamber and subsequently, into the canal of Schlemm. Inflammatory disease of the anterior segment may prevent aqueous escape by causing complete posterior synechia in iris bombe and may plug the drainage channel with exudates. Other common causes are intraocular tumors, enlarged cataracts, central retinal vein occlusion, trauma to the eye, operative procedures and intraocular hemorrhage.
Considering all types together, glaucoma occurs in about 2% of all persons over the age of 40 and may be asymptotic for years before progressing to rapid loss of vision. In cases where surgery is not indicated, topical .beta.-adrenoreceptor antagonists have traditionally been the drugs of choice for treating glaucoma.
It has long been thereof that one of the sequelae of glaucoma is damage to the optic nerve head. This damage, referred to as "cupping", results in depressions in areas of the nerve fiber of the optic disk. Loss of sight from this cupping is progressive and can lead to blindness if the condition is not treated effectively.
Unfortunately lowering. intraocular pressure by administration of drugs or by surgery to facilitate outflow of the aqueous humor is not always effective in obviating damage to the nerves in glaucomatous conditions. This apparent contradiction is addressed by Cioffi and Van Buskirk [Surv. of Ophthalmol., 38, Suppl. p. S107-16, discussion S116-17, May 1994] in the article, "Microvasculature of the Anterior Optic Nerve". The abstract states:
The traditional definition of glaucoma as a disorder of increased intraocular pressure (IOP) oversimplifies the clinical situation. Some glaucoma patients never have higher than normal IOP and others continue to develop optic nerve damage despite maximal lowering of IOP. Another possible factor in the etiology of glaucoma may be regulation of the regional microvasculature of the anterior optic nerve. One reason to believe that microvascular factors are important is that many microvascular diseases are associated with glaucomatous optic neuropathy.
Subsequent to Cioffi, et al., Matusi published a paper on the "Ophthalmologic aspects of Systemic Vasculitis" [Nippon Rinsho, 52 (8), p. 2158-63, August 1994] and added further support to the assertion that many microvascular diseases are associated with glaucomatous optic neuropathy. The summary states:
Ocular findings of systemic vasculitis, such as polyarteritis nodosa, giant cell angitis and aortitis syndrome were reviewed. Systemic lupus erythematosus is not categorized as systemic vasculitis, however its ocular findings are microangiopathic. Therefore, review of its ocular findings was included in this paper. The most common fundus finding in these diseases is ischemic optic neuropathy or retinal vascular occlusions. Therefore several points in diagnosis or pathogenesis of optic neuropathy and retinal and choroidal vaso-occlusion were discussed. Choroidal ischemia has come to be able to be diagnosed clinically, since fluorescein angiography was applied in these lesions. When choroidal arteries are occluded, overlying retinal pigment epithelium is damaged. This causes disruption of barrier function of the epithelium and allows fluid from choroidal vasculatures to pass into subsensory retinal spaces. This is a pathogenesis of serous detachment of the retina. The retinal arterial occlusion formed non-perfused retina. Such hypoxic retina released angiogenesis factors which stimulate retinal and iris neovascularizations and iris neovascularizations may cause neovascular glaucoma.
B. Schwartz, in "Circulatory Defects of the Optic Disk and Retina in Ocular Hypertension and High Pressure Open-Angle Glaucoma" [Surv. Ophthalmol., 38, Suppl. pp. S23-24, May 1994] discusses the measurement of progressive defects in the optic nerve and retina associated with the progression of glaucoma. He states:
Fluorescein defects are significantly correlated with visual field loss and retinal nerve fiber layer loss. The second circulatory defect is a decrease of flow of fluorescein in the retinal vessels, especially the retinal veins, so that the greater the age, diastolic blood pressure, ocular pressure and visual field loss the less the flow. Both the optic disk and retinal circulation defects occur in untreated ocular hypertensive eyes. These observations indicate that circulatory defects in the optic disk and retina occur in ocular hypertension and open-angle glaucoma and increase with the progression of the disease.
Thus, it is evident that there is an unmet need for agents that have neuroprotective effects in the eye that can stop or retard the progressive damage that occurs to the nerves as a result of glaucoma or other ocular afflictions.
Prostaglandins were earlier regarded as potent ocular hypertensives; however, evidence accumulated in the last two decades shows that some prostaglandins are highly effective ocular hypotensive agents and are ideally suited for the long-term medical management of glaucoma. (See, for example, Starr, M. S. Exp. Eye Res. 1971, 11, pp. 170-177; Bito, L. Z Biological Protection with Prostaglandins Cohen, M. M., ed., Boca Raton, Fla., CRC Press Inc., 1985, pp. 231-252; and Bito, L. Z., Applied Pharmacology in the Medical Treatment of Glaucomas Drance, S. M. and Neufeld, A. H. eds., New York, Grune & Stratton, 1984, pp. 477-505). Such prostaglandins include PGF.sub.2.alpha., PGF.sub.1.alpha., PGE.sub.2, and certain lipid-soluble esters, such as C.sub.1 to C.sub.5 alkyl esters, e.g. 1-isopropyl ester, of such compounds.
In the U.S. Pat. No. 4,599,353 certain prostaglandins, in particular PGE.sub.2 and PGF.sub.2.alpha. and the C.sub.1 to C.sub.5 alkyl esters of the latter compound, were reported to possess ocular hypotensive activity and were recommended for use in glaucoma management.
Although the precise mechanism is not yet known, recent experimental results indicate that the prostaglandin-induced reduction in intraocular pressure results from increased uveoscleral outflow [Nilsson et al., Invest. Ophthalmol. Vis. Sci. 28 (suppl), 284 (1987)].
The isopropyl ester of PGF.sub.2.alpha. has been shown to have significantly greater hypotensive potency than the parent compound, which was attributed to its more effective penetration through the cornea. In 1987 this compound was described as "the most potent ocular hypotensive agent ever reported." [See, for example, Bito, L. Z., Arch. Ophthalmol. 105, 1036 (1987), and Siebold et al., Prodrug 5, 3 (1989)].
Whereas prostaglandins appear to be devoid of significant intraocular side effects, ocular surface (conjunctival) hyperemia and foreign-body sensation have been consistently associated with the topical ocular use of such compounds, in particular PGF.sub.2.alpha. and its prodrugs, e.g. its 1-isopropyl ester, in humans. The clinical potential of prostaglandins in the management of conditions associated with increased ocular pressure, e.g. glaucoma, is greatly limited by these side effects.
Certain phenyl and phenoxy mono, tri and tetra nor prostaglandins and their 1-esters are disclosed in European Patent Application 0,364,417 as useful in the treatment of glaucoma or ocular hypertension.
In a series of co-pending United States patent applications assigned to Allergan, Inc. prostaglandin esters with increased ocular hypotensive activity accompanied by no or substantially reduced side-effects are disclosed. The co-pending U.S. Ser. No. 386,835 (filed Jul. 27, 1989), relates to certain 11-acyl-prostaglandins, such as 11-pivaloyl, 11-acetyl, 11-isobutyryl, 11-valeryl, and 11-isovaleryl PGF.sub.2.alpha.. Intraocular pressure reducing 15-acyl prostaglandins are disclosed in the co-pending application U.S. Ser. No. 357,394 (filed May 25, 1989). Similarly, 11,15- 9,15- and 9,11-diesters of prostaglandins, for example 11,15-dipivaloyl PGF.sub.2.alpha. are known to have ocular hypotensive activity. See the co-pending patent applications U.S. Ser. No. 385,645 filed Jul. 27, 1990, now U.S. Pat. Nos. 4,494,274; 584,370 which is a continuation of U.S. Ser. Nos. 386,312, and 585,284, now U.S. Pat. No. 5,034,413 which is a continuation of U.S. Ser. No. 386,834, where the parent applications were filed on Jul. 27, 1989. The disclosures of these patent applications are hereby expressly incorporated by reference.
Finally, certain EP.sub.2 -receptor agonists are disclosed in Nials et al, Cardiovascular Drug Reviews, Vol. 11, No. 2, pp. 165-179, Coleman et al, Comprehensive Medicinal Chemistry, Vol. 3, pp. 643-714, 1990 and Woodward et al, Prostaglandins, pp. 371-383, 1993.


A system for integrating a third generation (3G) cellular network with a WLAN has been proposed by the 3rd Generation Partnership Project (3GPP) in the standards document 3GPP TS 23.234, entitled “3GPP system to Wireless Local Area Network (WLAN) Interworking; System Description (Release 6),” which is incorporated herein by reference.


Example computer applications are the so-called “business applications.” A business application may be any software or set of computer programs that are used by business users to perform various business functions by processing and analyzing data stored in databases. Available business applications relate to different business functions including, for example, customer relationship management, enterprise asset management, enterprise resource planning, financials, human capital management, procurement, product lifecycle management, supply chain management, and sustainability, etc. Other business applications may relate to functions such as business intelligence, data warehousing, enterprise information management, enterprise performance management, governance, risk, and compliance.
Business applications may be interactive. A business application may provide a user interface (UI) through which a user can query data and view query results. A user's queries may be directed to diverse or large databases (e.g., business information warehouses). Use of some business applications (e.g., business analytics applications) may involve numerous queries and extensive query data analysis and processing. As today's computing environments evolve, business applications are becoming more and more complex. In a distributed environment, business applications critical to an enterprise may be spread across multiple systems and access multiple databases. At least in large system implementations, query result display processes may be relatively slow.
Consideration is now being given to aspects of displaying query results to users.


An exhaust bypass valve is often used to control operation of serial turbocharger systems. Such a valve may be operated to physically divert exhaust or alter pressures in exhaust pathways, for example, to direct exhaust flow partially or fully to one of multiple turbines in a system. During operation, a typical exhaust bypass valve experiences high exhaust pressure on one side and lower pressure on the other side. To effectively seal the high pressure environment from the low pressure environment, considerable force is required to maintain contact between a valve and a valve seat. In a sealed state of a valve and valve seat, pressure differentials may challenge one or more inter-component seals and result in detrimental exhaust leakage. Various technologies described herein have potential to reduce cost as well as provide for effective exhaust bypass valve sealing.


The block diagram of FIG. 1 shows one example of a prior art cordless telephone. A battery 1, which is chargeable through a charging terminal 2, supplies power to a power source circuit 3 by closing a power switch 4. Power source circuit 3, under control of a control circuit 5, converts the voltage from battery 1 to an appropriate voltage, and supplies this voltage to control circuit 5, to a transmitter 6 and to a receiver 7.
In a waiting state, i.e., awaiting an incoming call, the converted voltage from power source circuit 3, controlled by circuit 5, is intermittently applied to receiver 7. Upon receipt of a group signal, the receiver is synchronized with the transmitted signal from a base station for receipt of further intermittent signals. Consequently, receiver 7 carries out reception operation intermittently as shown in FIG. 2, thereby saving power consumption of the cordless telephone.
A significant problem in these prior art systems is the inability of the user of the battery powered radio to detect whether the system is operating properly. In particular, it has become necessary for the user to determine whether the communication link from the base station to the radio receiver is operating properly. Any defect in the base transmitter, or in the radio receiver, or due to interference could prevent the reception and processing of the data at the receiver. Not only is it important to identify the existence of a problem but to indicate it to the user in a manner which will avoid a large consumption of power.
The synchronized operation of several battery powered radio devices incorporating the prior art battery saving function is shown in FIGS. 3(a)-(c).
Referring to FIG. 3(b), all devices in a system are divided into M groups, for example, 3 groups. A base unit repeatedly broadcasts a frame signal consisting of M group signals. Each group signal includes preamble words and N calling words (FIG. 3(a)). The preamble word includes a predetermined synchronization signal for synchronization of received signals and a group identification signal for showing that the following paging words are addressed to pagers belonging to the group designated by the group identification signal. In response to a calling request, an identification signal of the device to be called is assigned to one of calling words 1 to N.
Referring to FIG. 3(c), if a device is turned on, the device examines the received signals to detect the synchronization signal. Once detecting the synchronization signal, the device performs intermittent reception so that only a group signal to the device is received.
In fact, prior art radio devices such as the cordless devices mentioned above have not even provided any indication whether the power source switch was closed. Apparently, if such an indicator was used to display the activation of the source, the display would emit light continuously thereby increasing power consumption and shortening the active life of the radio devices. It would be possible to increase the capacity of the battery, but this would necessarily result in high cost, increased weight and longer charging times.


In developments of emerging technology, such as new wireless standards or Artificial Intelligence, the amount of data required to be processed is increasing substantially. With the profusion of data, more computational requirements are placed on general purpose CPUs, specialized CPUs (i.e. GPU, TPU) and/or specialized Hardware Accelerators to expeditiously process the data.
As the computational requirement placed on the processors increases, the performance of the processors is often inadequate to handle computationally intensive tasks on large amount of data. In some cases, even if specialized processors are capable of handling the computational requirements, the cost of such processors is often prohibitive for many applications.
There are various factors which limit the computational capabilities of a processor. Traditionally, the processors use internal registers to temporarily hold the source input data which are loaded from the data memory. The processor then performs an arithmetic or other programmed operation using the values stored in the temporary registers as the operands, and writes the result of the operation to another temporary register. Finally, the processor stores the result in the temporary register back to the data memory.
For performing such operations, many instructions are required. For example, ADD Immediate instructions to calculate the operand addresses; LOAD Instructions to load the operands; MULTIPLY instruction to multiply the operands; ADD Immediate instruction to calculate the destination address; and STORE instruction to write the result to the destination memory location.
During the execution of these instructions, due to the inherent load/store latency associated with the data memory and the limited availability of the temporary registers, the instruction executions are often blocked by pipeline stalls resulting in degraded processor performance. The problem of pipeline stall is compounded when the processor operates on large sets of data.
Other common techniques employed in the industry, such as SIMD and Vector Instruction Extensions, try to address the performance issue by parallel data processing. However, these techniques, even though they obtain performance increase through parallelism, are still subject to the aforementioned limitations.
Therefore, it is desirable to have a flexible solution capable of processing large amount of data, which can also be quickly programmed, deployed, and modified as the product matures.


This invention concerns mechanical connections between control rod ends and a pivot pin, as are commonly used to connect control rods to a pin in transmission linkages for automobiles.
In these connections, it is now usual to incorporate a soft elastomeric isolator between the rod and the pin to minimize the transmission of vibrations to a shift lever for example which is gripped by the hand of the driver of an automobile. A disadvantage of such isolators has been the looseness or lash introduced into the connection by the pin contact compressing the isolator material.
Such looseness has also been introduced by the clearances necessary to assemble the component parts of the connection.
Labor costs are also incurred by the need to fit together complex components to complete the connection when the automobile is assembled, and the need to insure proper assembly.
Another difficulty has been involved in attempting to reduce the force necessary to fit the pin to the connection to simplify assembly while still insuring that an adequately high separation force would be required to disconnect the pin after the connection is made to prevent unintended disconnection.
It is the object of the present invention to provide an arrangement and method for connecting one end of a rod to a headed pin which incorporates a vibration isolator without introducing excessive looseness in the connection.
It is another object of the present invention to provide such an arrangement and method in which there are minimal clearances necessary for assembly purposes.
It is yet another object of the present invention to provide such an arrangement and method which requires only low installation forces while insuring that separation forces are sufficiently high to preclude unintended disconnection of the components.


U.S. Pat. No. 2,070,263 describes a method for obtaining aqueous solutions of hydrobromic acid which consists, in a first step, in passing hydrogen through liquid bromine maintained at a temperature of between 37.degree. C. and 42.degree. C. in order to form a mixture of bromine and hydrogen gas which is burnt at a temperature of between 600.degree. C. and 850.degree. C. By working in this way, it is difficult to have an intimate mixture of bromine and hydrogen in stoichiometric amounts on account of the difficulties in rigorously maintaining the temperatures and the thermodynamic equilibria.
An instability of the combustion flame has also been observed, in devices based on the direct combustion of bromine in hydrogen according to an H.sub.2 /Br.sub.2 molar ratio of greater than 1, and for which no technique for mixing the reactants is mentioned, this instability being manifested in particular by strong vacillation of the flame at the burner outlet, going as far as a detachment of the flame ("blow off") from the said burner, which may entail a risk of explosion and a fluctuating quality of the hydrogen bromide gas produced.
Furthermore, such flames become extended forming cones at the base of which are regions from which the reactants are liable to escape without being burnt.
This disrupts the combustion of the bromine in the hydrogen and results especially in residual bromine in the combustion gases, this being of a nature to bring about a considerable decrease in the lifetime of the burners, limit the range of materials which may be used and degrade the quality of the hydrogen bromide gas, thereby preventing it from being used as a reactant for downstream syntheses (secondary reactions, colorations of the products) or for the preparation of hydrobromic acid solutions.
Patent FR 2,365,516 proposes a process which improves the stability of the flame resulting from the combustion of bromine in hydrogen by establishing a helical stream of bromine in a cylindrical chamber, then injecting the hydrogen radially towards the outside in the helical stream of bromine and continuously supplying a flame close to the chamber with the helical stream of bromine and hydrogen.
This process, using a molar excess of hydrogen of 2.6%, leads to an HBr gas containing 300 ppm of bromine by volume, which still gives rise to colorations of the downstream synthesis products as well as the drawbacks mentioned above.
In addition, the complexity of the burner entails a lack of flexibility. Thus, in particular, when it is desired to increase the capacity of the said device, several burners are arranged side-by-side in the same chamber. In such an arrangement, it cannot be avoided that the flames from different burners mounted in parallel will interfere with each other, and furthermore this arrangement is unacceptable with regard to obtaining good distribution of the reactants. This configuration inevitably leads to a lowering in the degree of conversion of the bromine, complicates the control of the cooling of the HBr formed and increases the risks of explosion.


This invention relates in general to fire resistant structures and, more particularly, to a fire resistant door.
Fire barriers are included within the design of many types of buildings in order to block the spread of a fire once it has been ignited within the building. Because the placement of door openings in the walls of the building provides an avenue for the fire to spread from room to room, much attention has been focused on the designing of doors which are fire resistant and can impede the spread of the fire.
Panel doors have a plurality of flat or raised panels interconnected with vertically extending stiles and horizontal rails. Although panel doors are widely utilized because of their visually pleasing appearance, they generally have poor resistance to fire because air is able to infiltrate the door at the juncture of the panels with the stiles and rails. The fire is fed by the oxygen present in the air which seeps through the panel joints and can quickly burn through the door at those joints. In an effort to increase their fire resistance, some panel doors are available which have segments of fire resistant material inserted within grooves milled into the edges of the stiles, rails and panels at the junctures of those components. The placement of the fire resistant material at those locations is generally effective to slow the rate at which the fire can burn through the panel joints, but the fire is still able to burn through the wooden portions of the door at a faster rate than is desired in many instances.
Another type of conventional fire resistant door mimics the appearance of a panel door by applying half panels to a core of fire resistant material. The core comprises a solid sheet of material which is milled on both faces to form recesses at the intended location of the panels. Half panels are then positioned within the recesses and veneer and trim are applied to the exposed surfaces of the core. The resulting door can be very resistant to fire because the solid core blocks any air infiltration through the door. The milling operation, however, may reduce the structural integrity of the door and result in warping, sagging or other deformation of the door.
A need thus exists for a panel door which has an enhanced fire resistance but maintains the desired structural and visual appearance.


This invention is generally directed to layered photoresponsive imaging devices, and more specifically to photoconductive devices having incorporated therein certain novel bisazo compounds. Therefore, in one embodiment of the present invention there are provided photoconductive layered imaging members comprised of certain bisazo compounds and arylamine hole transport layers. In one important embodiment of the present invention, there is provided a photoresponsive device comprised of various specific bisazo compounds, including 4,4'-bis(1"-azo-2"-hydroxy-3"-naphthanilide)-1,1'-dianthraquinonylamine; 4,4'-bis(1"-azo-2"-hydroxy-3"-naphtho-p-trifluoromethylanilide-1,1'-dianth raquinonylamine; and the derivatives thereof; and wherein the member further includes therein a charge, or hole transport layer. The aforementioned photoconductors possess a number of advantages indicated hereinafter inclusive of high photosensitivity, excellent photosensitivity to wavelengths of from about 400 to 750 nanometers, and high cyclic stability; and further, are very economical enabling these devices to be readily disposable. Accordingly, the photoresponsive imaging members of the present invention are useful in various electrophotographic and electrostatographic imaging processes wherein, for example, latent images are formed thereon followed by development and transfer to a suitable substrate. More specifically, the imaging members of the present invention with photosensitivity of from about 400 to about 750 nanometers enabled such members to be useful for electrophotographic imaging devices, and also these members can be incorporated into light emitting diode printers as well as multifunctional printer electrophotographic apparatuses.
Numerous different xerographic photoconductive members are known including, for example, a homogeneous layer of a single material such as vitreous selenium, or a composite layered device containing a dispersion of a photoconductive composition. An example of one type of composite xerographic photoconductive member is described, for example, in U.S. Pat. No. 3,121,006 wherein there is disclosed finely dispersed divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. These members contain, for example, coated on a paper backing, a binder layer containing particles of zinc oxide uniformly dispersed therein. The binder materials disclosed in this patent comprise a material such as polycarbonate resins, polyester resins, polyamide resins, and the like, which are incapable of transporting for any significant distance injected charge carriers generated by the photoconductive particles.
There are also known photoconductive members comprised of inorganic or organic materials wherein the charge carrier generating, and charge carrier transport functions are accomplished by discrete continuous layers. Additionally, layered photoconductive members are disclosed in the prior art which include an overcoating layer of an electrically insulating polymeric material.
Recently, there have been disclosed other layered photoresponsive devices including those comprised of separate generating layers, and transport layers as described in U.S. Pat. No. 4,265,990, and overcoated photoresponsive materials containing a hole injecting layer overcoated with a hole transport layer, followed by an overcoating of a photogenerating layer, and a top coating of an insulating organic resin, reference U.S. Pat. No. 4,251,612. Examples of photogenerating layers disclosed in these patents include trigonal selenium and phthalocyanines, while examples of transport layers include certain diamines as mentioned herein. The disclosures of each of these patents, namely U.S. Pat. Nos. 4,265,990 and 4,251,612, are totally incorporated herein by reference.
Many other patents are in existence describing photoresponsive devices including layered devices containing generating substances, such as U.S. Pat. No. 3,041,167 which discloses an overcoated imaging member containing a conductive substrate, a photoconductive layer, and an overcoating layer of an electrically insulating polymeric material. This member is utilized in an electrophotographic copying system by, for example, initially charging the member with an electrostatic charge of a first polarity, and imagewise exposing to form an electrostatic latent image which can be subsequently developed to form a visible image.
Furthermore, there are disclosed in U.S. Pat. Nos. 4,232,102 and 4,233,383 photoresponsive imaging members comprised of trigonal selenium doped with sodium carbonate, sodium selenite, and trigonal selenium doped with barium carbonate, and barium selenite or mixtures thereof. Moreover, there are disclosed in U.S. Pat. No. 3,824,099 certain photosensitive hydroxy squaraine compositions. According to the disclosure of this patent, the squaraine compositions are photosensitive in normal electrostatographic imaging systems.
Also known are photoconductive members containing therein various squaraine compositions. Thus, for example, there are illustrated in U.S. Pat. No. 4,508,803, the disclosure of which is totally incorporated herein by reference, photoconductive devices containing novel benzyl fluorinated squaraine compositions. Specifically, in one embodiment illustrated in the '803 patent there is described an improved photoresponsive device comprised of a supporting substrate, a hole blocking layer, an optional adhesive interface layer, an inorganic photogenerating layer, a photoconducting composition layer comprised of benzyl fluorinated squaraine compositions, and a hole transport layer. Other representative patents disclosing photoconductive devices with squaraine components therein, or processes for the preparation of squaraines include U.S. Pat. No. 4,507,408; 4,552,822; 4,559,286; 4,507,480; 4,524,220; 4,524,219; 4,524,218; 4,525,592; 4,559,286; 4,415,639; 4,471,041; and 4,486,520. The disclosures of each of the aforementioned patents are totally incorporated herein by reference.
Further, disclosed in the prior art are composite electrophotographic photosensitive materials with various bisazo compounds. For example, there are illustrated in Japanese Ricoh Patent Publication No. 6064354, published Apr. 12, 1985, composite photoconductors wherein one of the photoconductor layers contain a bisazo compound of the formulas as illustrated. Further, there are illustrated in several U.S. patents layered organic electrophotographic photoconductor elements with bisazo, trisazo, or related compounds. Examples of these U.S. pat. Nos. include 4,596,754; 4,555,567; 4,555,667; 4,440,845; 4,486,522; 4,486,800; 4,299,896; 4,551,404; 4,309,611; 4,418,133; 4,293,628; 4,427,753; 4,495,264; 4,359,513; 3,898,084; 4,400,455; 4,390,608; 4,327,168; 4,299,896; 4,314,015; 4,486,522; 4,486,519; and Konishiroku Japanese Patent Laid Open Publication No. 60111247.
Also of interest is U.S. Pat. No. 4,713,307, which illustrates photoconductive imaging members containing a supporting substrate, certain azo pigments of 2,7-bis(1'-azo-2'-hydroxy-3'-naphthanilide) naphthalene, and the derivatives thereof; and a charge transport layer.
Although photoconductive imaging members with bisazo compounds are known, there remains a need for novel bisazo photoconductor devices with extended red or near-IR photoresponses thereby enabling their selection in imaging apparatus with light emitting diodes. Additionally, there continues to be a need for layered photoresponsive imaging members have incorporated therein certain bisazo compounds, which members will enable the generation of acceptable high quality images, and wherein these members can be repeatedly used in a number of imaging cycles without deterioration thereof from the machine environment or surrounding conditions. Moreover, there is a need for improved layered photoresponsive imaging members wherein the bisazo compounds selected for one of the layers are substantially inert to the users of such members. Additionally, there is an important need for layered photoconductors with bisazo compounds, which photoconductors are of low cost, high sensitivity, and possess high cyclic stability. There also is a need for bisazo photoconductors that possess photosensitivity in the wavelength region of from about 650 to about 750 nanometers enabling these photoconductors to be selected for electrophotographic, particularly xerographic, imaging processes; light emitting diode printers; and multifunctional printer electrophotographic apparatuses.


Telephony has advanced dramatically with the advancement of technology. Telephone communication was once limited to an analog public switched telephone network (PSTN), where the PSTN has been traditionally formed of two types of telephone carriers, local and long distance. The local carriers established local networks for subscribers to communicate within local regions, and the long distance carriers created networks between the local networks to enable subscribers of different local carriers to communicate with one another.
Over time, mobile telephone networks were developed to enable subscribers to use mobile telephones. At first, the wireless networks and handsets were analog. Technology for the wireless networks was developed to provide digital wireless communications, which provided a clearer signal than analog wireless communications.
About the same time that the digital wireless networks were developing, the Internet was also developing. The International Standards Organization (ISO) developed an Open Systems Interconnection (OSI) basic reference model in 1977 that currently includes seven different layers. Each of the layers provides protocols for certain types of operations. More specifically, the seven layers include: physical layer (Layer 1), data link layer (Layer 2), network layer (Layer 3), transport layer (Layer 4), session layer (Layer 5), presentation layer (Layer 6), and application layer (Layer 7). Each entity interacts directly with the layer immediately beneath it and provides facilities for use by the layer above it. The protocols on each layer enable entities to communicate with other entities on the same layer. The Internet initially provided for simple digital data to be communicated between users. One of the early communication application included email. However, as communications standards and protocols developed, the Internet matured to include more advanced communication applications, including voice over Internet protocol (VoIP).
FIG. 1 is an illustration of a legacy telecommunications network that includes class 4 and 5 switches 102a-102n (collectively 102) and 104a-104n (collectively 104), respectively, connected to a signaling system #7 (SS7) network 106 (indicated as dashed lines). Historically, the class 5 switches 104 were generally configured to communicate via in-band signaling verses the use of SS7 signaling and operate to form a local network of subscribers within the network to place telephone calls to one another. The class 4 switches 102 were developed for long distance connections between the class 5 switches 104 at end offices (not shown). The class 4 switches 102, which are monolithic, are generally formed of multiple components, including a port, port cross-connect matrix, switch messaging bus with external signaling units, and call processing unit, as understood in the art. Class 4 switches are circuit based and utilize time division multiplexing (TDM) and are capable of terminating higher high-speed communications, including T1, T3, OC-3, and other four-wire circuit connections. As understood in the art, TDM is a synchronous communications protocol.
The SS7 network 106, which includes signal transfer points (STPs) 108a-108n (collectively 108), service switching points (SSs) on the class 4 and class 5 switches, and service control points (SCPs—not shown). The SS7 network is connected to the class 4 and 5 switches for providing and maintaining inter-switch call services between the switches. The SS7 network is used to signal out-of-band call setup, as out-of-band signaling is more secure and faster than in-band signaling. The call state changes of the inter-switch trunks of the class 4 switch are communicated to the adjoining switches via the SS7 network via a connection to the STP. To manage and route calls, the STPs 108 are used as an Inter-Switch messaging network whereby two switches control the trunking between the switches via messaging over the SS7 network provided by the STP switches that act as the inter-switch message bus. A call state machine of the class 4 switch provides control for routing traffic within the cross-connect matrix of the monolithic switch. The call state machine also provides call control signaling information to other switches via the connections to the STPs. The call control signaling information is routed via the STPs to other switches for call setup and tear-down. The call control information routed by the STPs contains pertinent information about the call to allow the terminating switch to complete various calls.
Telephony has benefited from the development of the OSI model in a vast number of ways. One way has been through separating the call controller into a distributed cross-connect on an asynchronous network, such as asynchronous transfer mode (ATM or a Internet Protocol (IP) network. FIG. 2 is an illustration of a conventional telephony network 200 that includes a packet network 202. In one embodiment, the packet network 202 is an ATM network. Media gateways (MGs) 204a-204n (collectively 204) are media translation or conversion devices that modify and convert protocols between disparate communication networks. The media gateways 204, which are in communication with class 5 switches 206a-206n (collectively 206) are located at the edge of the packet network 202. The media gateways 204 convert TDM packets or streams 208 into packets, frames, or cells (collectively referred to hereinafter as “packets”) 210 and vice versa.
The packet network 202 operates independently as a distributed virtual media gateway port cross-connect for voice calls primarily due to one or more call control managers (CCMs) 212 located on the packet network 202. The call control manager 212 is in communication with the media gateways 204 and operates to control the media gateways 204 and provide instructions on how to rotate the packets 210 via far-end address allocations. By separating the call controller from the class 4 switches, the packet network 202 becomes, in effect, the virtual cross-connect of the switching system. The packet network 202 enables packets 210 that include voice data, commonly known as bearer packets, to be tagged with a destination address 214a and origination address 214b for enabling content data 214c to be properly routed from the origination media gateway 204b to the destination media gateway 204a. The media gateways 204 use of the packet network 202 is controlled by the CCM 212 and may communicate the packets 210 over the packet network 202 via IP addresses and virtual circuit (VC) or virtual path (VP) between the media gateways 204 to appropriately route the packets to the correct destination network node through the packet network 202. CCM 212 receives call state processing information from the media gateways 204 and signaling points, and processes the call state changes by using look up tables (not shown). The CCM 212 thereafter communicates packet addressing and state changes to the media gateways 204 to process the call.
Ethernet protocol was developed to provide for a computer network that enables multiple computers to share a common external inter-communication bus. Ethernet is generally used to provide for local area networks (LANs). Ethernet operates by communicating frames of data. While Ethernet operates well within a local environment (e.g., within a building) because Ethernet assumes that there is an known capacity of bandwidth associated with the bus standards set forth in the IEEE 802.3 standard that defines Ethernet. Ethernet is a shared environment, where co-utilization creates transmission errors called collisions. These collisions are detected by Ethernet cards in computers and a random re-transmission timer is used to avoid the next collision. Ethernet poses special problems for use in communications systems given it lacks dedicated bandwidth and time slots. The shared nature of an Ethernet network creates additional complexities in that the amount of available bandwidth can vary when used with wireless technologies.
Communication protocols transmitted over packet networks, such as ATM or IP networks, may utilize TDM based transmission facilities, which are synchronous as compared to Ethernet transmission facilities, which are asynchronous. Synchronous transmission protocols utilize a common clock and channel schema so that each device on the network operates synchronously with a dedicated path. Two types of “connection” state knowledge are present in a dedicated system, such as a TDM. Each channel has a dedicated amount of bandwidth and an error rate that is calculated from a common clock to determine path errors. The two types of connection state awareness functionality are provided by the channel itself and the common clock and data within a TDM header. The common clock provides for a determination of (i) a communications data rate from one end-point to another end-point and (ii) the data quality. Additionally, the TDM protocol includes “far end state” data in a header of a TDM frame to indicate whether there is a connection at the far end, thereby providing an indication of continuity along the communications path. Specifically, in-band end-to-end alarming allows the cross-connect devices to receive indications of continuity problems with other end-points. The in-band alarming is also provided for connection quality, where Bit Error Rate (BER) allows each end-point to know the quality of the data being received. Furthermore, bandwidth is always in use meaning that packets are synchronous, which that the far end knows exactly how many packets are to be sent and received in a given time period (e.g., one second). Computation of utilization is easily made by using the known bandwidth and multiplying it by the “seizure” time or the amount of time in use.
Packet-based communications sessions lack circuit based connection state awareness indicators and clocking functionality to provide a session controller the ability to know the path connectivity state to efficiently manage making call handling decisions with anything other than ample bandwidth to setup and use sessions. This lack of connection path state awareness with the communications protocols, such as Ethernet and Internet protocol (IP) technologies, result in “gaps” in terms of being able to react to decaying transmission path quality and be sensitive to shared use of bandwidth. Most IP call controller solutions are founded on enterprise applications, where a single entity owns the network and scale of the network is relatively small. IP and Ethernet protocols lack the in-band path signaling, quality and use metrics to allow for this scale, or the ability to perform enhanced call handling with paths outside the governance of the packet network. Because packet communications are asynchronous, there is no common clock, and, thus, there is no way to know how many packets were transmitted, which, in turn, removes the ability to characterize transmission quality of the entire path, the amount of bandwidth available, or the amount in use. Further, packet networks are “converged” meaning they have both real-time and non-real-time bandwidth use. Currently, there is no in-band mechanism for determining real-time and non-real-time bandwidth use; having such information would allow for handling calls. It is commonly understood that proper connection operational assumptions are made by call control engines when the SS7 signaling path is properly operating (e.g., provisioned bandwidth is available) between end-points within the SS7 network. These operational assumptions are problematic as Ethernet, IP, and other data networks become oversubscribed and cause the packet network to become congested and prevent throughput. In cases where an end-point, such as a WiFi telephone, is mobile and bandwidth changes with signal strength (e.g., a WiFi telephone losing bandwidth as an individual walks away from a connection point antenna), the connection operation assumptions also fail to provide graceful call handling.
One available technique in packet networks to prevent oversubscription of real-time media traffic is through the use of call admission control (CAC) or the IP equivalent known as Resource Reservation Protocol (RSVP). CAC is primarily used to prevent congestion in voice traffic and is applied in the call setup phase to ensure there is enough bandwidth for data flow by reserving resources. To reserve bandwidth through the entire packet network, a CAC requires that the CAC procedure be performed at each point along a virtual circuit between two media gateways on which a call is to be routed, and often in a bi-directional fashion. While CAC functionality exists, the use of such CAC functionality is almost never applied because of the amount of time needed by the CAC procedure during call set up. For example, currently, CAC typically cannot operate over 40 calls per second and typical call set-ups on media gateways or class 4 switches may be 200 calls per second or higher.
One technique used to monitor the performance of IP session performance (i.e., after a call session has been established) is the use of the real-time control protocol (RTCP) as defined in IETF RFC 3550. RTCP collects statistics on a media connection, including bytes sent, packets sent, lost packets, jitter, feedback, and round trip delay. Other information may be provided in the RTCP packet using profile specific extensions. RTCP, which operates on a per session basis, is used for quality of service (QoS) reporting after termination of a session. The statistics information may be used, for example, to improve the quality of service by limiting data flow or changing CODEC compression. Utilization of the real-time QoS statistics, however, is limited to the specific session associated with the RTCP stream.
An emerging standard that is being developed for Ethernet performance measures is 802.1AG. This standard operates by generating and communicating an 802.1AG packet or “heart beat” over an Ethernet network segment. The 802.1AG packets are communicated via a Layer 2 Ethernet Virtual Circuit, such as a VLAN or Ethernet tunnel. At the ends and mid-points in Ethernet tunnels, 802.1AG packets are transmitted periodically over the Ethernet network to the far end. The Y.1731 protocol is utilized to calculate the number of data frames communicated between the 802.1AG packets. This configuration enables a performance measures (PM) to compute certain information about the performance of the path between the end-points on an Ethernet network. This combination of 802.1AG and Y.1731 enables the end points to be knowledgeable about the Frame Loss Rate (FLR), packet delay, and jitter in the path. This configuration is helpful to assist in monitoring performance of an Ethernet network path and diagnosing connectivity faults. However, the configuration falls short of providing the amount of real-time bandwidth in use or the total bandwidth in use. This information is useful to the proper management by a session controller handling calls during periods of flux in the packet transmission path, or the management of the real-time traffic.
Service providers often have trouble isolating and diagnosing network problems. To attempt to locate a packet loss problem along a node segment (i.e., a path between two network communications devices) over a network a probe that may be used to trace data packets being communicated over the node segment. This probe, however, is typically an external device from the network communications devices and operates to run a trace over an instant of time to determine network performance information, such as packet loss, jitter, and delay. An operator using the external probe may view results of a trace to diagnose the network communications problem. These results are not accessible to the network communications devices and cannot be accessed by network communications devices to alter network communications.
Telecommunications switching systems today provide for Internet protocol (IP) communications between two end-points within a network or a different network to be terminated to a far end-point. Calls between two end-points are routed to the terminating end-point based on the address input at the originator. This address information is then relayed to a Call Control Manger (CCM) that screens, translates, and routes the call to the terminating subscriber or to another network to be terminated at a far end subscriber's end-point. The basic functionality of this process is widely known within the art and is used throughout telecommunications networks for voice calling.
Within the architecture of this switching system, calls to and from end-points are controlled by the CCM. The CCM may be located within a monolithic device in a TDM switch architecture or provided by an outboard computing device that controls the calls by using signaling that controls network based routing and switching devices located within the network. The latter device is known as soft-switch architecture.
The soft-switch architecture within an IP network controls call processing through use of signaling to and from the end devices and media gateways. One example of a protocol used for this IP signaling is Session Initiation Protocol (SIP). This protocol is currently used mainly with IP telephony, such as VoIP, and can be used as an access protocol between the end-user and the CCM and/or between the CCM of one network and the CCM of another network.
Another protocol used mainly between the CCM and a media gateway is the ITU-T H.248 protocol, commonly known as Megaco. This protocol is a control protocol that allows the CCM to control ingress and egress from/to the media gateway as calls are set up using a media gateway. Within a packet network framework, IP communications between two end-points (both access end-points and media gateways) are controlled by the signaling of the end-point to/from the CCM. The CCM provides authentication, screening, translations and routing based on information that is stored in the CCM and from the state of the end-points that the CCM controls.
Within the soft-switch architecture, call control can only be accomplished based on information possessed by the CCM or the on/off state of the devices that has an association with the CCM. While this configuration is fine in a static environment, packet networks are in a state of change at all times since the network itself can carry different types of information besides voice calls. One skilled in the art knows that a packet network is a converged network that can carry voice, data, and video all in a single path, and routing of calls within a packet network is not static and can vary significantly from call to call.
Because of packet network content communications variables, calls may encounter congestion and loss of voice quality based on latency, jitter, and packet loss. These content communications variables can affect any portion of a call at anytime based on the network elements usage at the time of the call. Unlike a TDM system where dedicated channels and circuits are provided, the CCM only has control of it own end-points. Other end units may attempt calls, computers may send/receive data without talking to the CCM, and other devices may require bandwidth while the original call is progressing, thus causing voice quality problems for the participants. In addition to these basic gaps, many physical layer 1 systems that are poor in regulating bandwidth, are being used for transmission facilities. WiFi, EVDO, 4G (Wax), DSL, and cable systems are all physical layer 1 technologies that demonstrate different bandwidth rates and management of their ability to modify available bandwidth as the Signal-to-Noise (SNR) ratios change.
Conventional soft-switching has not been designed to provide relief for callers when congestion, jitter or delay problems, such as those described above, are encountered. Since conventional CCMs can only determine call success based on connectivity to and from the calling parties, voice quality between two parties is not taken into consideration for call success.
Communication problems of in-band signals over packet networks are difficult to isolate. Currently, if a communication problem exists over a transmission path, there are few techniques to isolate the problem. One technique includes using an external probe to capture and decode packets, commonly know as a trace, traversing over a communications path to help isolate the problem. However, technicians generally only run the trace in response to a customer notifying a communications carrier of a communications problem. If a problem exists across packet networks operated by different carriers, a typical response by a carrier is to contact the other to determine if the other carrier can locate a problem in its network. In other words, locating an in-band communications problem over one or more packet networks is difficult as troubleshooting tools for such problems are limited to out-of-band performance metrics (PM) and are not available as in-band information via control or signaling paths.
A problem that exists with current implementations of telephony over packet networks is that a call control manager does not have information about the bearer path. Traditionally, there was a linkage between transmission path state and the monolithic switch that essentially owned one end of that path where the in-band signaling and line characteristics were available and was an integral part of the information used by the CCM for call processing. As demonstrated in current implementations of VoIP, without knowledge of the bearer path, the call control manager may establish calls that result in poor voice quality or call setup failure.
In addition, IP Service gateways, such as a broadband remote access server (BRAS), functions to limit, commonly known as traffic rate shaping, each customer's DSL traffic to their purchased speed. There is no end-to-end signaling, outside of the embedded TCP flow control mechanism, used to adjust the bursting to eliminate packet loss. Rate shaping is a statically forced bandwidth constraint that alters the nature of a transmission path in the packet networks. This shaping coupled with commonly shared or “over-subscribed” bandwidth normally associated with trunking facilities between networks results in unknown transmission path states between media gateways servicing VoIP and other real-time services, such as Video on Demand (VOD).
Traffic Quality of Service (QoS) management of packets is performed, where multiple flows aggregate into a smaller flows or channels. The application of Internet Protocol QoS is performed at the egress point where traffic is transmitted over a single link. Current traffic engines use the following information to make QOS traffic decisions. The decisions are assigning a Class of Service (CoS) and then acting upon that service to shape, restrict, or pass traffic to an egress point. The variables used to assign priority to traffic flows can be based on: entrance port (assign a whole port a CoS), virtual circuit in a port (assign a CoS to an Ethernet Virtual Circuit, LSP, etc.), priority bit marking of each packet (P bit), protocol type (assigning a CoS to specific types of packets or traffic), IP address and port (assigning a CoS to a whole IP address, or its port addresses), session identification (a HTTP, UDP, or other session addressed call), or otherwise. This priority marking information is used by service points, and shared links to implement QoS for the shared traffic flows. QoS and CoS types of information are made available at the point of aggregation where traffic management or QoS functions occur. However, the number of packets transmitted or lost in the packet stream elsewhere in the network is currently unavailable without the use of a session or path based protocol. These packet loss functions are generally not tracked by QoS mechanisms.
In current traffic rate shaping designs, the Internet may burst a packet stream to a DSL user when the packet network or Digital Subscriber Line Access Multiplexer (DSLAM) itself may not have sufficient bandwidth to accommodate the packet session. In a TCP-based session, the transmission rate is throttled down after packet loss is detected in the session. In VoIP, the packet loss is not counted by the use of Real Time Control Protocol (RTCP) signaling, but it is captured as the call progresses by the end points. RTCP, however, only considers performance of its own sessions and not the transmission path performance as a whole. In both cases, packets are sent over the packet network that get dropped in mid-path and will not make it to the customer premises equipment (CPE) and user. More importantly, there is no cross-session information about the packet loss and no whole path information available in-band.
Also, packet loss can be due to available bandwidth transmission rate fall-off, such as when a WiFi user walks away from a WiFi Access Point (AP) and loses RF signal strength, signal-to-noise ratio increases, or congestion increases due to many users concurrently accessing the AP. All of these types of conditions in the transmission paths can have severe impacts upon the ability to accomplish call processing and call management.
An Internet Service Provider (ISP) may provide different Internet connectivity speeds or data transfer rates based upon their service plans. For example, a user may purchase 1.5 Mbits/sec data transfer rate for a predetermined amount, such as 10 Mbits/sec data transfer rate or higher. In general, the transmission path is between the shared (trunked) BRAS resource and the DSLAM that is supplying. The normal amount of bandwidth consumption in the download direction from the network to the user is high as compared to the upstream direction. However, there is no correlated throttling mechanism in the IP web-server linked to user's ISP service plan that can be used to shape the packet transmissions. So, all of the network traffic is shaped at the BRAS typically based on the user's purchased data transfer rates. Depending upon network conditions, some of this traffic may not make it to the DSL user since the BRAS has no knowledge of the IP service path from itself to the customer.
A problem occurs when the BRAS does realize congestion on a packet network where packets are being dropped due to insufficient bandwidth. Some packets could be dropped in the packet network or at an aggregation device somewhere in the packet network. Currently, there is little intelligence that recognizes the dropped packets in the packet network. In fact, packet networks are designed to discard traffic based on QoS markings. This problem is made worse because transporting packets that will ultimately be dropped adds to congesting the network. The packets consume bandwidth until dropped.
Transmission Control Protocol (TCP) was designed to work in a best-effort, packet store-and-forward environment characterized by the possibility of packet loss, packet disordering, and packet duplication. Packet loss can occur, for example, by a congested network element discarding a packet. Here, a microprocessor or memory of a network element may not have adequate capacity to address all packets routing into and out of the element. Packet disordering can occur, for example, by routing changes occurring during a transmission. Here, packets of TCP connection may be being arbitrarily transmitted partially over a low bandwidth terrestrial path and as routing table changes occur partially over a high bandwidth satellite path. Packet duplication can occur, for example, when two directly-connected network elements use a reliable link protocol and the link goes down after the receiver correctly receives a packet but before the transmitter receives an acknowledgement for the packet.
An embedded capability within TCP protocol is the TCP sliding window technique. The sliding window was developed and deployed as a flow control mechanism used to minimize the inefficiencies of packet-by-packet transmission. The sending of data between TCP enabled end-devices on a connection is accomplished using the sliding window technique. TCP requires that all transmitted data be acknowledged by the receiving host. The sliding windows method is a process by which multiple packets of data can be affirmed with a single acknowledgement.


Modern application-specific integrated circuits (ASICs) integrate greater and greater security and data protection functionality into the hardware (HW). The integrated functionality provides more reliable and more efficient hardware security for both conventional “Data At-Rest” and conventional “Data In-Flight” protection.
Data storage systems are moving to distributed storage models that are based on storage networking. The move has an impact for enterprise data protection: the distributed models increase the vulnerability of stored data (i.e., Data At-Rest) to various attacks, both external and internal and both malicious and accidental. For Internet traffic and other moving data (i.e., Data In-Flight), the move provides such protection as sender and recipient mutual authentication, key exchange, data confidentiality, authenticated encryption (which is a type of encryption/decryption that additionally providing a way to check data integrity and authenticity) and replay protection.
In contemporary applications, the speed/throughput of the traversing data is up to 10 Gb/s (gigabits per second) and beyond. For some storage applications, the speed/throughput of the traversing data is even 10× higher: up to 100 Gb/s and beyond. The high speeds alone make security support of the data in software (SW) almost infeasible as far as security transformations are usually incorporated into the main data path and appear as bottlenecks from efficiency and performance standpoints.
Many cryptographic protocols use an encryption process and message authentication and data integrity services independently with each process using an independent key. To speed up overall computations, new cryptographic modes that combine and provide both crypto services using a single “combined” mode were proposed and became accepted by both the National Institute of Standards and Technology (NIST) and the Institute of Electrical and Electronics Engineering (IEEE) and other technical professional organizations and committees working in network and data storage security areas.
To prevent data lost and breach, IEEE P1619 “Standard Architecture for Encrypted Shared Storage Media” suggests using the XTS-AES (Advanced Encryption Standard) (XOR-Encrypt-XOR (XEX)-based Tweaked Electronic Code Book (ECB) mode with Cipher Text Stealing (CTS)). The P1619.1 “Standard for Authenticated Encryption with Length Expansion for Storage Devices” uses the Galois/Counter mode (GCM), Counter mode (CTR) with Cipher-Block Chaining (CBC)-Message Authentication Code (MAC) (CCM) and other cryptographic processes. Both drafts are now accepted standards: IEEE Std. 1619-2007 and IEEE Std. 1619.1-2007.
Among the new AES-based modes is the NIST approved (see NIST Special Publication SP800-38D defining Galois/Counter Mode (GCM) and Galois Message Authentication Code (GMAC)) GCM mode and IEEE P1619 legacy mode Liskov, Rivest, and Wagner (LRW), that both use Galois Field multiplication for processing 128-bit blocks of data. Besides memory and storage applications, GCM-AES is becoming more widely used in various Internet security protocols and was suggested/submitted as an Internet-draft to the Internet Engineering Task Force (IEFT) to use in the Secure RTP (SRTP) protocol (see Internet-Draft for GCM in Secure RTP (SRTP)), MACsec (see IEEE 802.1AE), Internet Key exchange version 2 (IKEv2), and in the IPsec (see RFC 4106 and RFC 4543).
A feature of the GCM mode is that the message authentication is performed in parallel with encryption/decryption of the main data payload by applying multiplication in a Galois Field (GF). Multiplications in finite fields have been used for fast (i.e., insecure) message hash computations. To make such computed massage hash values secure, application of the GCM GHASH process adds a pseudorandom vector, a so called “whitening” vector, at the end. The pseudorandom vector is generated by encrypting a preset value (i.e., Initialization Vector IV) with a secret AES key (i.e., vector W). Use of the GF multiplier for Message Authentication Code (MAC) computation permits higher throughput than the authentication process for computing a conventional MAC. The conventional MAC processes use slower chaining modes, like AES-CBC, or use a separate stand-alone secure hash process from the Secure Hash Algorithm (SHA) family.


The present invention relates generally to retention of one or more expansion cards installed within a computer chassis.
Peripheral Component Interface (PCI) cards are often used to add functions and capabilities to computers. These cards include card edge contacts and are installed in a computer by insertion into a mating slot on a circuit board of the computer. These cards may extend perpendicularly from the circuit board and some means of support the card may be provided by an adjacent portion of the computer chassis. The PCI cards may be releasably attached to the means of support to prevent the cards from being disturbed from the slot and to prevent adjacent cards from contacting each other. Often, the releasable attachment is accomplished by the use of tools and typically some sort of removable fastener, such as a screw. A bracket may be attached to one end of the card and screwed to a card support or a wall of the chassis. Improvements to the attachment and release of expansion cards from slots within a computer chassis are desirable.
PCI cards and the computers which receive them have been configured to permit hot swapping or plugging. This allows a card to be removed or installed from a slot in the computer without shutting the computer down. To accomplish this hot plug, the power supplied to the slot must be turned off prior to the removal or insertion of a card. Improvements to the powering or depowering of card slots for the insertion or removal of cards from the slots are desirable.
Each card slot for receiving a PCI card within a computer chassis may have a first LED indicating whether the slot is currently powered up, and a second LED indicating the fault status of the slot. Often, these LEDs are mounted to the circuit board to which the slot is mounted and are located adjacent the card slot. Space on the circuit board may be crowded adjacent the card slot, making relocation of the LEDs desirable. Further, LEDs placed on the circuit board may be difficult to see from outside the chassis. It is desirable to improve the visibility of these LEDs while keeping them adjacent to the card slot they are associated with.
The present invention relates to a card retention device which includes a frame, a slider and a flap. The frame defines an opening through which an expansion card may be inserted into or removed from an expansion slot. The flap is hingedly mounted to the frame and movable between a captive position where the flap covers the opening and a free position where the flap does not cover the opening. The slider is slidably mounted to the frame and movable between a locked position where the slider holds the flap in the captive position and an unlocked position where the flap is free to move from the captive to the free position.
The present invention further relates to a computer chassis including an expansion slot for receiving an expansion card and a card support extending adjacent the slot. A card retention device is mounted to card support and includes a frame, a slider and a flap. The frame defines an opening through which an expansion card may be inserted into or removed from an expansion slot. The flap is hingedly mounted to the frame and movable between a captive position where the flap covers the opening and a free position where the flap does not cover the opening. The slider is slidably mounted to the frame and movable between a locked where the slider holds the flap in the captive position and an unlocked position where the flap is free to move from the captive to the free position.


1. Field of the Invention
The present invention relates to a digital camera having autofocus capability and continuous shooting capability.
2. Description of the Related Art
A continuous shooting mode in which a series of photos are taken while the release button is held fully depressed (i.e., while the release switch is held ON) is known in the art as a shooting mode of a digital camera (see Japanese Unexamined Patent Publication 2007-017787). In conventional digital cameras, the camera is in an AF lock state (in which autofocus (AF) process is suspended) during continuous shooting. Therefore, even if the camera is in an in-focus state upon the commencement of continuous shooting, the camera sometimes becomes out of focus in the middle of continuous shooting when, e.g., shooting a moving object.
To keep the camera in focus during continuous shooting, an AF process only needs to be performed each time a picture is taken, i.e., each time the main mirror (quick-return mirror) moves down to the photographing position. However, a problem exists with this control slowing down the continuous shooting speed by the amount of time required to perform the AF process.


An auto document feeder (ADF) is a paper feeding mechanism for a photocopying machine. The ADF can convey a whole stack of paper sheets one by one to make them pass through a scanner of the photocopying machine for scanning operations. A common photocopying machine can only scan one side of the paper sheet. By adding another scanner in the ADF, the other side of the paper sheet can also be scanned, so both sides of the paper sheet can be scanned in one paper feeding operation.
A simple configuration method, like disclosed in U.S. Pat. No. 7,457,006, U.S. Pat. No. 5,280,368, U.S. Pat. No. 7,411,704 and U.S. Pat. No. 8,730,537, is to include another scanner adjacent to the scanner of the photocopying machine. Generally, the scanner is a contact image sensor (CIS) scanner, so the paper sheet has to be in flat contact with the scanner for precise focus operations and better scanning quality. The two scanners are usually disposed opposite to each other. Therefore, after passing through one scanner, the paper sheet has to turn over instantly to come into flat contact with the other scanner. This motion can be achieved by utilizing a block for pressing paper sheets. However, this tends to cause twisting of the paper sheets and paper jams.
As a result, the target of the inventor is to solve the above-mentioned problems, on the basis of which the present invention is accomplished.