Provided is a fuel cell separator that has excellent resistance to heat and hot water and has a glass transition temperature between 140° C. and 165° C. Said fuel cell separator is formed by curing a composition containing a graphite material and a binder component resin. The binder component resin contains a cresol novolac epoxy resin having a hydrolysable chlorine content of at most 450 ppm and an epoxy equivalent weight of 192-210 g/eq, a phenol resin having a hydroxyl equivalent weight of 103-106 g/eq, and an imidazole compound having a molecular weight between 140 and 180.

One role of the fuel cell separator is to confer each unit cell with electrical conductivity. In addition, separators provide flow channels for the supply of fuel and air (oxygen) to the unit cells and also serve as boundary walls separating the unit cells. Characteristics required of a separator thus include a high electrical conductivity, a high impermeability to gases, chemical stability and heat resistance. In household fuel cell applications in particular, long-term chemical stability is required.
Techniques for achieving these characteristics include the methods disclosed in Patent Documents 1 to 9.
However, in the methods of Patent Documents 1 and 2, because a resin having ester bonds is used in the fuel cell separator composition, hydrolysis may arise in the resin during power generation by the fuel cell, making the resistance of the fuel cell separator to hot water problematic. Moreover, curing of the composition takes a long time, and so these methods are also unsuitable for mass production.
In the methods of Patent Documents 3 to 7, because an epoxy resin having a high content of hydrolyzable chlorine is used in the fuel cell separator composition, the hydrolyzable chlorine lowers the crosslink density of the cured product, as a result of which the resulting fuel cell separator has insufficient heat resistance.
In the method of Patent Document 8, when triphenylphosphine is used as the cure accelerator, the resulting fuel cell separator has insufficient heat resistance. When 2-phenyl-4-methyl-5-hydroxymethylimidazole is used as the cure accelerator, owing to the poor compatibility between the accelerator and the epoxy resin, the curing reactions have difficulty proceeding, and so the resulting fuel cell separator has insufficient strength and heat resistance.
In the method of Patent Document 9, because triphenylphosphine is used as the cure accelerator, the resulting fuel cell separator has insufficient heat resistance.
Fuel cell separators are generally located in a working environment that is repeatedly subjected to wet heat and dry heat. When a fuel cell separator lacks adequate resistance to heat and hot water as in the case of the separators disclosed in each of the above patent documents, deformation and cracking sometimes arise during power generation within such an environment.


The present invention relates to a film preparation having both rapid solubility and flexibility at the same time. The film preparation is characterized by comprising: an active-ingredient-containing layer comprising an active ingredient, a water-soluble polymer selected from the group consisting of methyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methyl cellulose, and a disintegrating agent; and an active-ingredient-free layer comprising methyl cellulose and/or hydroxypropyl methyl cellulose. It is further characterized in that the amount of the active ingredient is 0.1-75.0 mass % of a total mass of the film preparation and a total content of the active ingredient and the water-soluble polymer in the active-ingredient-containing layer is 15.0-95.0 mass % of a total mass of the active-ingredient-containing layer.

A film preparation made by formulating an active ingredient such as a drug and a food component into a film shape has been known to have advantages that the film preparation can be taken without water and has high solubility (rapid solubility), and so forth.
For example, the followings are known as the film preparation.
A monolayer film preparation including gelatin, pectin, glycerin and a sucrose fatty acid ester (Patent Document 1).
A monolayer film preparation including a drug, an edible polymer and a saccharide as main components (Patent Document 2).
A monolayer film preparation including a medical substance and a water soluble polymer (Patent Document 3).
A monolayer film preparation including a medical drug and hydroxypropyl cellulose (Patent Document 4).
A monolayer film preparation including a drug and pullulan (Patent Document 5).
A monolayer film preparation including a food material or the like, a pregelatinized starch and/or pullulan, and a plasticizer (Patent Document 6).
A non-rapidly-soluble multilayer film preparation including an active ingredient-containing layer whose base is a water soluble polymer and a non-adhesive layer having a poor solubility to water (Patent Document 7).
A film preparation made by laminating a coating layer a including a water-soluble and non-water-absorbing polysaccharide and a softener, a drug layer b including a drug and an edible water soluble polymer substance, and a drug layer c including a drug, an edible water soluble polymer substance and a tannin substance, in the order of a, b, c, b and a (Patent Document 8).
A monolayer film preparation including a film forming agent, a water swelling gel forming agent, an active substance, a filler and a polar solvent (Patent Document 9).    Patent Document 1: Japanese Unexamined Patent Application Publication No. Hei 6-105660    Patent Document 2: Japanese Patent No. 3460538    Patent Document 3: Published Japanese Translation of PCT Application No. 2002-525306    Patent Document 4: Japanese Unexamined Patent Application Publication No. Sho 62-63513    Patent Document 5: Japanese Unexamined Patent Application Publication No. Sho 63-109865    Patent Document 6: Japanese Unexamined Patent Application Publication No. 2005-21124    Patent Document 7: Japanese Unexamined Patent Application Publication No. Hei 9-235220    Patent Document 8: Japanese Patent No. 3730081    Patent Document 9: Japanese Patent No. 2559301

Film preparation with rapidly dissolving property and flexibility


The invention relates to an apparatus for assessing the condition of at least one circulating band in a papermaking machine including a permeability measuring device, a moisture measuring device, a fiber web moisture measuring device, an evaluator, a reel-up and an other moisture measuring device. The permeability measuring device measures the permeability of the at least one circulating band. The moisture measuring device measures the moisture contained in the at least one circulating band. The fiber web moisture measuring device measures the moisture of the fiber web. The evaluator combines the permeability, the moisture of the at least one circulating band and the moisture of the fiber web to determine the condition of the at least one circulating band. The other moisture measurement device is coupled to the reel-up, and takes a moisture measurement of the fiber web made by the papermaking machine.

1. Field of the Invention
The invention relates to an apparatus for assessing the condition of at least one circulating band, in particular of a water-absorbing dewatering band and/or a transfer band in a papermaking machine.
2. Description of the Related Art
In general, the prior art discloses apparatuses which permit a permeability measurement on the circulating dewatering band. However, such apparatuses have a disadvantage in that they measure a high permeability at holes, cracks or the like, a high permeability being an indication of a satisfactory quality of the dewatering band. Thus, those apparatuses, which measure only the permeability, supply erroneous information about the condition of the quality of the dewatering band, in particular at holes, cracks or the like.
In addition, the prior art discloses handheld devices for measuring the permeability and handheld devices for measuring the moisture of a dewatering band in a papermaking machine. In using these handheld devices, it is not possible for any continuous monitoring of the permeability and of the moisture of the dewatering band to be carried out during operation. In addition, such handheld devices have only a limited accuracy, with which frequently no satisfactory statements can be made about the condition of the dewatering band. However, in order to be able to ensure a satisfactory quality of a fibrous web to be produced, it is necessary to be able to measure the permeability and the moisture of the dewatering band during operation, the quality of the fibrous web to be produced also depends on the quality of the permeability measurement and the moisture measurement.

Apparatus and method for assessing the condition of at least one circulating band in a paper machine


When original image data obtained by reading an original document is to be joined with watermark data associated with a watermark for copy control which appears as a result of making a copy, whether the original document includes a chromatic color or not is determined on the basis of the original image data. When the original document includes a chromatic color, the original image data is joined with chromatic watermark data. When the original document includes an achromatic color, the original image data is joined with achromatic watermark data.

1. Technical Field
The present invention relates to an image processing apparatus, an image forming apparatus, an image processing method, a computer program and a recording medium, in which a determination result of ACS (Auto Color Selection) is allowed to be reflected in formation of a watermark for copy control that appears as a result of making a copy.
2. Description of Related Art
Certified copies (e.g., family registers and certificates of residence) published by official agencies on the basis of original documents containing personal information are widely used as papers for authenticating individuals. In order to ensure the function as papers for authenticating individuals, certified copies are required to be distinguished clearly from duplications thereof. Moreover, certified copies published by official agencies require measures to protect privacy, since personal information is contained therein.
Documents printed on the basis of original documents in companies also require measures to protect privacy as well as the certified copies described above, since personal information such as customer information is sometimes contained therein. Moreover, when commercial or technical confidential information is contained in documents created in companies, it is necessary to prevent leakage of the documents to a third party who is under no obligation to keep secrets.
Japanese Patent Application Laid-Open No. 2007-88763 discloses a print control unit for causing a computer to join contents data (original image data) indicative of information contained in an original document with watermark data indicative of a watermark for copy control (e.g., a text or a mark for warning such as "Copy", "Copy Prohibited" or "Confidential"), which is invisible in a certified copy or a document but appears in a duplication of a certified copy or a document made by a copying machine, and printing a certified copy or a document on the basis of obtained composite data. The print control unit can cause a computer to join original image data with watermark data and print an image associated with the watermark data and the original image data on a normal paper, eliminating the need to use an anti-copying and anti-counterfeiting paper having the above-described watermark for copy control printed thereon in advance. Moreover, the user is allowed to select easily a watermark appropriate for the information contained in a certified copy or a document.
In recent years, an image forming apparatus for causing an image reading unit to read an original document printed on a paper to generate original image data and joining the generated original image data with watermark data has also been proposed in view of a case where the original document is not digitized. The apparatus creates an image showing a certified copy or a document. Some image forming apparatuses enable formation of a chromatic (color) image showing a certified copy or a document and advance specification of a chromatic color to be used for a watermark for copy control.

Image processing apparatus, image forming apparatus, recording medium and image processing method


A lens system having at least one front movable lens group and a rear movable lens group which are movable in an optical axis direction. The lens system includes a position detector for determining whether the rear movable lens group is positioned in a predetermined normal moving range thereof; and a lens control device which stops the front movable lens group and moves the rear movable lens group rearward into the predetermined normal moving range if the rear movable lens group is in an abnormal moving range thereof in front of the normal moving range during a forward movement of the front movable lens group from a predetermined initial position thereof.

This application is a divisional application of U.S. application Ser. No. 11/202,088, filed on Aug. 12, 2005, the contents of which are expressly incorporated by reference herein in their entirety.
1. Field of the Invention
The present invention relates to a movable lens control device for controlling movements of a plurality of movable lens groups of a lens system.
2. Description of the Related Art
In retractable zoom lens barrels having a plurality of zooming lens groups (movable lens groups) which are moved to perform a zooming operation and a focusing lens group (movable lens group) positioned behind the zooming lens groups which is moved to perform a focusing operation, it is generally the case that firstly only the zooming lens groups are moved forward from respective initial positions (retracted positions) thereof with the focusing lens group remaining stationary at an initial position (retracted position) thereof, and subsequently the focusing lens group is moved forward upon the zooming lens groups reaching predetermined respective positions thereof (e.g., positions at wide-angle extremity of a zooming range) when the retractable lens barrel is extended from a retracted position to an extended position thereof.
However, there is a possibility of the focusing lens group having moved forward from the initial position unintentionally for some reason before the zooming lens groups are moved forward to respective extended positions from the initial positions. If this happens, a malfunction may occur in forward movements of the zoom lens groups toward the extended positions from the initial position.


A blowing agent blend for making thermoplastic polymer foams comprises methyl formate. The blowing agent blend can further comprise at least one co-blowing agent. The co-blowing agent is either a physical co-blowing agent (e.g. an inorganic agent, a hydrocarbon, a halogenated hydrocarbon, a hydrocarbon with polar, functional group(s), water or any combination thereof), or a chemical co-blowing agent, or combinations thereof. The thermoplastic polymer foam can be an alkenyl aromatic polymer foam, e.g. a polystyrene foam. The blowing agent blend can comprise any combination of methyl formate and one or more co-blowing agents. The methyl formate-based blowing agent blends produce stable foams for various applications, including containers, packaging systems, as well as insulation boards and building materials. A process for the preparation of such foams is also provided.

Thermoplastic foams made from alkenyl aromatic polymers (e.g, polystyrene) or polyolefin polymers (e.g. polyethylene) have found extensive use, particularly as insulating materials. Generally, insulating foams are produced in thicknesses greater than about one-half inch. The insulating value of such foams is measured in terms of heat conduction resistance or R-value, per one inch of foam thickness. Adequate insulating foams typically have R-values of about 4.0 per inch or greater. It is also desirable for such insulating foams to be dimensionally stable.
These and other polymer foams are commonly made by using a blowing agent with molten resin under pressure and, after thorough mixing, extruding the combination through an appropriate die into a lower pressure atmosphere.
In the past, physical blowing agents widely used for making foams were chlorofluorocarbons, which, because of their high ozone depletion potential (ODP), were subsequently replaced with hydrochlorofluorocarbons (HCFCs). The use of HCFC blowing agents, however, will likely be banned in the near term, again because of high ODP. Some of these blowing agents can be replaced with hydrofluorocarbons (HFCs), which have zero ODP, so as to minimize damage to the ozone layer. Furthermore, HFCs have a thermal conductivity lower than most polymers or blowing agents, so HFC residuals in a polymeric foam can lower the foam's thermal conductivity.
Presently, physical blowing agents more commonly used for making thermoplastic polymer foams such as alkenyl aromatic polymer (e.g, polystyrene) or polyolefin polymer (e.g. polyethylene) foams, are hydrocarbons, chlorinated hydrocarbons, hydrochlorofluorocarbons, or combinations thereof. Hydrocarbons with three or more carbons atoms are considered volatile organic compounds (VOCs) that can lead to the formation of smog. Halogenated hydrocarbons often are either VOCs or have high ODP or are hazardous air pollutants (HAPs), and, at times, may fall into more than one of these categories. Therefore, the use of such blowing agents for preparing polymeric foams is not preferred environmentally and imposes many limitations on the manufacturing process, thus complicating and significantly increasing the cost of manufacturing.
Methyl formate is classified as a non-VOC (Federal Register, Volume 69, Number 228, Nov. 29, 2004), is non-HAP, and has zero ODP. U.S. Pat. No. 6,753,357 describes the use of methyl formate to produce stable, rigid isocyanate/polyol based polyurethane foams. It is noted, however, that such polyurethane foams are thermoset, so as to be made via a cross-linking and curing process. The dimensional stability or instability imparted to the final polyurethane foam product by the nature of the blowing agent therefore is quite different than in the case of melt processed thermoplastic polymer foams.
Therefore, a need exists for blowing agents employing methyl formate as one of the components of the blowing agent blend to produce stable thermoplastic foams without compromising the product quality in terms of appearance, mechanical or compressive strength and insulation value, and that enable a cost-effective and versatile manufacturing process.

Insulating thermoplastic foams made with methyl formate-based blowing agents


A method for testing a server. A component (2) captures a session consisting of requests of and responses from a server (3). The captured session is stored as script files (4, 5). A GUI component (6) facilitates the identification of variable data (30) within the script files. Variable data is data which may vary from session to session. The identification process generates a database (14) with field headers (18) corresponding to the types of data identified (15). A component populates database (13). A driver component (9) uses the script files (11, 12) and the database (13) to test the server (3) by running multiple threads (10) each directing their own session with the server. Where data within the script files has been identified as variable data (13) the thread may substitute data from the database (13). A server testing apparatus and software for implementing the method is also disclosed.

Standard approaches to testing web servers involve creating scripts using a programming language and using a driver program to run these scripts to test a server. A disadvantage to this approach is that the individuals who are testing the web server must be competent in using a programming language.
Another approach involves the capture of traffic between a user and the server. This captured script can be then used to load test the web server by running multiple simultaneous instances using a driver program. Programs that implement this approach include LoadRunner and Astra SiteTest. This approach has a number of disadvantages. Firstly it can be difficult to thoroughly test a server as the script when used by multiple instances is unchanged, therefore only one type of user is tested. Secondly, a problem arises if the server to be tested requires unique data, for example unique simultaneous users. The only way for this approach to overcome the difficulty is by capturing multiple user sessions and having each instance use the script from a different session. This can be time-consuming for the user.

Method of and apparatus for testing a server


A mechanical ventilation device (10) includes a mechanical ventilator. At least one airway sensor (24, 26) is configured to measure at least one of airway pressure and airway air flow as a function of time for a patient on the mechanical ventilator. At least one microprocessor (28, 30) is programmed to analyze at least one of airway pressure and airway air flow measured by the airway sensor to detect a spontaneous respiration anomaly in respiratory muscle pressure as a function of time generated by a patient on the mechanical ventilator. A display component (22) is configured to display an indication of a spontaneous respiration anomaly detected by the anomaly detection component.

In a spontaneously breathing patient receiving mechanical ventilation, the goal is to configure the mechanical ventilator to support the patient's spontaneous respiration. To this end, it is desirable to minimize patient-ventilator dyssynchrony. Some examples of potentially problematic patient-ventilator dyssynchrony include early cycling off and double effort. In early cycling off, the ventilator cycles off, so as to begin the expiration phase, before the patient completes his or her inspiration effort. In double effort, the patient makes two distinct inhalation efforts in a single inspiration period. Active exhalation is another condition that is useful to detect. During normal respiratory effort, the patient's diaphragm operates to expand the lungs to cause inhalation; the exhalation phase is normally passive and relies upon the elastance of the respiratory system to expel air from the lungs. In active exhalation, the patient's respiratory muscles actively operate to compress the lung volume during exhalation. These and other respiratory anomalies are difficult to assess for a patient on mechanical ventilation because the patient's respiratory effort is normally not measured.
The need for estimation of the respiratory system parameters (e.g., resistance R and elastance E) and patient inspiratory efforts (e.g., respiratory muscle pressure Pmus) is well-known in the medical community. Estimating Pmus as a function of time (Pmus(t)) is especially important in patient-ventilator support modalities of mechanical ventilation, such as a Pressure Support Ventilation (PSV) mode, where a patient and a ventilator share the mechanical work performed on the respiratory system. A quantitative assessment of Pmus(t) can be used to select the appropriate level of ventilation support delivered by the ventilator in order to prevent both atrophy and fatigue of patient respiratory muscles. The clinical parameter commonly used to assess the effort made by the patient per breath is known as Work of Breathing (WoB) and can be computed once the estimate of Pmus(t) is available for the breath. WoB can be obtained from Pmus(t) by integration of the latter over the inhaled volume. However, respiration anomalies can occur during mechanical ventilation, which can result in an inaccurate estimation of Pmus(t) R, and/or E. Detecting such anomalies can improve the estimation of these parameters.
The following provides new and improved systems and methods which overcome the foregoing problems and others.

Anomaly detection device and method for respiratory mechanics parameter estimation


A relation between a twist pitch p of twisted nematic liquid crystal and a thickness d of a liquid crystal layer is set to p/d<8, and polymer stabilization is carried out. In this way, torque to recover from alignment upon application of a voltage to alignment without application of the voltage is increased and response speed of the liquid crystal at decay time is thereby increased. By applying the present technique to a liquid crystal display device which is driven by a reset operation, an overdrive operation or common modulation, high response speed is obtained even when the twisted nematic liquid crystal is used. As a result, the liquid crystal display device can deal with field sequential display mode where higher response speed is required.

1. Field of the Invention
The present invention relates to a liquid crystal panel, a liquid crystal display device using this liquid crystal panel, and electronic equipment incorporating this liquid crystal display device.
2. Description of the Related Art
Liquid crystal display devices ranging from small-sized devices used in projectors, cellular telephones, and the like to large-sized devices used in laptop personal computers, monitors, televisions, and the like are spreading rapidly along with the development of the multimedia age. In the meantime, medium-sized liquid crystal display devices are indispensable for electronic equipment such as viewers or personal digital assistants (PDAs) and for amusement machines such as portable game players and pachinko (Japanese pinball machines). In addition, liquid crystal display devices are used in many other devices including home electric appliances such as refrigerators, microwave ovens, and the like.
Today, most of liquid crystal display elements adopt the twisted nematic (TN) display mode. The liquid crystal display elements of the TN display mode apply nematic liquid crystal compositions, and driving methods for the liquid crystal are roughly divided into two methods. One of the methods is a simple matrix driving method. The other one is an active matrix method in which each pixel is provided with a switching element such as a thin-film transistor (TFT). At present, the TN-TFT mode which is a combination of the TN display mode and the active matrix method using TFTs is generally applied, for example.
Apart from the TN display mode, another mode for the liquid crystal display elements is called a super twisted nematic (STN) mode. Although contrast and viewing angle dependency are improved in this STN mode as compared to the conventional simple matrix method using the TN mode, the STN mode is not suitable for motion image displays due to slow response speed. In addition, the STN mode has another disadvantage which is low display quality as compared to the active matrix method using the TFTS. Accordingly, the liquid crystal display devices adopting the TN-TFT mode are now predominant in the market.
In the meantime, to meet the demand for higher image quality, various methods for improving the viewing angle have been developed and put to practical use. As a result, TFT active matrix liquid crystal displays adopting any of the following three modes, namely, a mode applying a compensating film to the TN mode, the in-plane switching (IPS) mode, and the multi-domain vertical aligned (MVA) mode, are now becoming mainstream for high-performance liquid crystal displays.
These active matrix liquid crystal display devices normally apply positive and negative writing of an image signal at a cycle of 30 Hz. Accordingly, an image is rewritten at a cycle of 60 Hz and time for one field is approximately equal to 16.7 ms (milliseconds). In this case, total time of both positive and negative fields is called one frame, which is approximately equal to 33.3 ms. In this context, the response speed of the current liquid crystal is almost equivalent to this frame time at the shortest.
There are two major demands for the liquid crystal display devices, namely, higher definition of images and improvement in response speed for images. The demand for the improvement in response speed reflects growing opportunities for liquid crystal display screens to display not only conventional still images but also motion images. Among those motion images, images particularly associated with high speed image changes such as sports videos and computer graphics in games require higher response speed than the current frame time.
Meanwhile, concerning the higher definition, 100 ppi (pixels per inch) is the current mainstream definition. There are two methods for achieving higher definition. One of the methods is to increase processing accuracy and reduce sizes of pixel elements, and the other one is to switch a backlight for illuminating a display device among red, green, and blue by time division and achieve multicolor displays by each pixel element. The latter method is referred to as the field sequential (time division) method and is now under consideration for application to color liquid crystal display devices. In this method, it is not necessary to divide the pixels into three groups and to spatially arrange corresponding color filters. Therefore, this method is deemed capable of achieving three times higher definition than conventional display devices and of improving light use efficiency due to an increase in numerical apertures. On the other hand, a field sequential liquid crystal display device is required to display one color within one-third of the time for one field, which is approximately equal to 5 ms. Therefore, the liquid crystal applied thereto must have the response speed less than 5 ms. After all, the improvement in response speed is also essential for achieving higher definition of images.
Various techniques have been studied to meet requirements for a liquid crystal display device which can respond to the above-described high speed images, and techniques concerning high speed liquid crystal display modes have been developed to date. These techniques concerning high speed liquid crystal display modes are categorized into two major trends. One of the trends is a technique to increase response speed of twisted nematic liquid crystal. The other one is a technique to use different liquid crystal which offers high speed response.
In general, the response time of liquid crystal is given by the following two formulae (see "Liquid Crystal Dictionary", edited by Liquid Crystal Section, The 142-nd Committee for Organic Materials for Information Science, Japan Society for the Promotion of Science, Baifukan Co., Ltd, pp. 24-25). Specifically, the following Formula 1 holds true for response at rise time when a voltage higher than a threshold voltage is applied to create an on-state. Meanwhile, the following Formula 2 holds true for response at decay time when the applied voltage higher than the threshold voltage is suddenly reduced to 0. In this case, d denotes a thickness of a liquid crystal layer, η denotes rotational viscosity, Δ∈ denotes dielectric anisotropy, V denotes the applied voltage, Vc denotes the threshold voltage, and K denotes a Frank elastic constant.
                              τ          rise                =                                            d              2                        ×            η                                Δ                                                                                ɛ                                            (                                                      V                    2                                    -                                      V                    c                    2                                                  )                                                                        (                  Formula                                                              1                )                                          τ          dcay                =                                            d              2                        ×            η                                              π              2                        ×            K                                              (                  Formula                                                              2                )
In the meantime, the following Formula 3 holds true for the TN mode. In this case, K11 denotes a splay elastic constant, K22 denotes a twist elastic constant, and K33 denotes a bend elastic constant.
                    K        =                              K            11                    +                                    1              4                                                  (                                                K                  33                                -                                  2                                                        K                    22                                                              )                                                          (                  Formula                                                              3                )
As it is apparent from the Formula 1, in terms of the response at rise time, the response time of liquid crystal is proportional to the reciprocal of the squared size of the applied voltage. In other words, the response time of liquid crystal depends on the squared reciprocals corresponding to voltage values which vary from one tone level to another. For this reason, the response time varies largely depending on the tone level. For example, a 10 times voltage differential causes a 100 times differential in the response time. On the contrary, whereas the differential in the response time depending on the tone level also exists in the response at decay time, the differential falls in the range of about 2 times.
From these aspects, the speed of the response at rise time is increased by an overdrive effect which is obtained by applying an extremely high voltage. In the meantime, the response used in an actual image display always corresponds to the response at decay time. Accordingly, the dependency on the tone level is extremely small. As a result, substantially equal response time is obtained throughout all the tones.
In light of the Formulae 1 to 3, conceivable measures for increasing the response speed of the nematic liquid crystal, which is the first technical trend, mainly include:    (1) reducing a cell gap and increasing electric field intensity while maintaining a constant voltage;    (2) increasing the electric field intensity by applying a high voltage to the liquid crystal to promote a state change of the liquid crystal (the overdrive method);    (3) increasing the dielectric anisotropy for sensitizing the response to the electric field;    (4) reducing the viscosity; and    (5) reducing the splay elastic constant (K11) and the bend elastic constant (K33) out of the elastic constants while increasing the twist elastic constant (K22) to speed up the response at decay time.
Generally speaking, the following problem arises when drive speed of twisted nematic liquid crystal is simply increased. When the drive speed of the nematic liquid crystal is increased, a capacity of the liquid crystal varies largely depending on the dielectric anisotropy and on a difference in alignment directions of the liquid crystal. For example, in case of liquid crystal known by the product name DLC-43002, the dielectric constant in the parallel direction is equal to 11.8 and the dielectric constant in the vertical direction is equal to 3.7. Accordingly, the capacity change is immense when the drive speed is increased and a holding voltage to be written in and held by a liquid crystal layer is thereby reduced. Such reduction in the holding voltage, or reduction in an effective applied voltage, causes deterioration in contrast because insufficient writing occurs and the liquid crystal is not shifted to a desired position. Moreover, when the same signal is repeated as in a still image, luminance continues to fluctuate until the holding voltage stops decreasing and several frames are required for obtaining the stable luminance.
To prevent the response which requires several frames, it is essential that a signal voltage to be applied and a transmittance to be obtained establish a one-on-one correlation. In the active matrix drive, the transmittance after the response of the liquid crystal is not determined by the applied signal voltage but by electric charges accumulated in a capacitor of the liquid crystal after the response thereof. This is because the active matrix drive adopts a drive mode based on constant electric charges, in which the liquid crystal makes a response by use of the accumulated electric charges.
The electric charges supplied from an active element are determined by the accumulated electric charges prior to writing a given signal and by newly written electric charges while disregarding small leaks and the like. Moreover, the accumulated electric charges after the response of the liquid crystal also vary depending on pixel design values such as physical constants of the liquid crystal, electric parameters, or storage capacitance.
For this reason, the following are required for establishing the proper correlation between the signal voltage and the transmittance, namely:    (1) a correlation between the signal voltage and the written electric charges;    (2) the accumulated electric charges prior to writing; and    (3) information required for calculation of the accumulated electric charges after the response, and actual calculation based on the information, and the like.As a result, it is necessary to install a frame memory for storing the values concerning (2) in terms of the entire screen, and a calculation unit for executing calculations concerning (1) and (3). Such installation invites an increase in the number of components in a system, and is therefore undesirable.
As a method of solving this problem, the reset pulse method configured to apply a reset voltage for resetting liquid crystal to a predetermined state before writing new data is often applied. As an example, the technique disclosed in International Display Research Conference (IDRC) 1997, pp. L-66 to L-99 will be described below.
The optically compensated birefringence (OCB) mode configured to align nematic liquid crystal into a pie-shape and to add a compensating film is applied in this document. The OCB mode is one of wide viewing angle modes. The OCB mode adopts a cell structure in which a phase compensating film (a biaxial retardation film) is provided to an antiparallel cell having a pretilt angle. A bias voltage is applied to homogeneous alignment to form bend alignment, and switching is performed by applying another voltage. The OCB mode has advantages of a wide viewing angle and short response time. The response speed of this liquid crystal mode ranges from approximately 2 ms to 5 ms, which is dramatically shorter than the conventional TN-TFT mode. Accordingly, the response is supposed to be completed within one frame. However, as described above, the holding voltage is considerably reduced by the variation in the dielectric constant attributable to the response of the liquid crystal, and several frames are required for obtaining the stable transmittance as similar to the conventional mode. Accordingly, there is proposed a method of writing a black display every time after writing a white display within one frame.
FIG. 1 is a graph showing variation in luminance according to the reset pulse method, in which the lateral axis indicates the time and the longitudinal axis indicates the luminance. In FIG. 1, a broken line indicates luminance variation in the case of normal drive, and a solid line indicates luminance variation when the reset pulse method is applied. As shown in FIG. 1, according to the normal drive method, the luminance is low at first two frames and reaches a stable level at the third frame. On the contrary, according to the reset pulse method, the luminance is always reset to a given state before writing new data and a one-on-one correlation equivalent to a certain written signal voltage to a certain transmittance is observed therein. Due to the one-on-one correlation, generation of driving signals is considerably simplified and means for storing the previous writing information such as a frame memory is not required therein.
Next, a configuration of a pixel in an active matrix liquid crystal display device will be described. FIG. 2 is a circuit diagram showing an example of a pixel circuit equivalent to one pixel in a conventional active matrix liquid crystal display device. As shown in FIG. 2, the pixel in the active matrix liquid crystal display device includes: an n-type metal oxide silicon (MOS) transistor (hereinafter referred to as an n-type transistor (Qn)) 904 of which a gate electrode is connected to a scan line 901, another one of electrodes is connected to a signal line 902, and the other electrode is connected to a pixel electrode 903; a storage capacitor 906 formed between the pixel electrode 903 and a storage capacitor electrode 905; and liquid crystal 908 interposed between the pixel electrode 903 and a counter electrode Vcom 907.
At present, liquid crystal display devices for laptop PCs and cellular telephones shaping the large application market for the liquid crystal display devices usually apply either an amorphous silicon thin film transistor (hereinafter referred to as an a-SiTFT) or a polysilicon thin film transistor (hereinafter referred to as a p-SiTFT) as the transistor (Qn) 904. Moreover, twisted nematic liquid crystal (hereinafter referred to as TN liquid crystal) is used as the liquid crystal material therein.
FIG. 3 is a circuit diagram showing an equivalent circuit of the TN liquid crystal. As shown in FIG. 3, the equivalent circuit of the TN liquid crystal can be expressed by a circuit in which a capacitance component C3 (its capacitance Cpix) of the liquid crystal, and, a value Rr of a resistance R1 as well as a capacitor C1 (its capacitance Cr), are connected in parallel. In this case, the resistance value Rr and the capacitance Cr are components which determine a response time constant of the liquid crystal.
FIG. 4 is a timing chart showing variations in a gate scan voltage Vg, a data signal voltage Vd, and a voltage at the pixel electrode 903 (hereinafter referred to as a pixel voltage) Vpix when the TN liquid crystal shown in FIG. 3 is driven by the pixel circuit shown in FIG. 2, in which the lateral axis indicates the time and the longitudinal axis indicates the voltage and the light transmittance. As shown in FIG. 4, the gate scan voltage Vg is set to a high level VgH in a period when this pixel is selected for horizontal scanning, whereby the n-type MOS transistor (Qn) 904 is set to on-state and the data signal voltage Vd inputted to the signal line 902 is transferred to the pixel electrode 903 through the n-type transistor (Qn) 904. The TN liquid crystal normally operates in the mode that allows light transmission when no voltage is applied thereto, or a so-called normally white mode.
At this time, a voltage for increasing the light transmittance of the light transmitted through the TN liquid crystal is applied for a period of several fields as the data signal voltage Vd. When the horizontal scanning period is over and the gate scan voltage Vg is set to a low level, the n-type transistor (Qn) 904 is set to off-state and the data signal voltage Vd transferred to the pixel electrode 903 is held by the storage capacitor 906 and by the capacitance Cpix of the liquid crystal. In this case, the pixel voltage Vpix causes voltage shifts called feedthrough voltages through source-gate capacitance of the n-type transistor (Qn) 904 at the time when the n-type transistor (Qn) 904 is set to off-state. The voltage shifts are indicated by Vf1, Vf2, and Vf3 in FIG. 4, and amounts of the voltage shifts Vf1 to Vf3 can be reduced by designing a large value for the storage capacitor 906.
The pixel voltage vpix is held in the subsequent field period until the gate scan voltage Vg is set to the high level again and the transistor (Qn) 904 is selected. In response to the pixel voltage Vpix thus held, the TN liquid crystal performs switching and the light transmitted through the liquid crystal transits from a dark state to a bright state as indicated by light transmittance T1. At this time, as shown in FIG. 4, the pixel voltage Vpix is shifted only by ΔV1, ΔV2, and Δ3 in the respective fields during the holding period. Such an aspect is attributable to variation in the capacitance of the liquid crystal which occurs in accordance with the response of the liquid crystal. To reduce such variation, the size of the storage capacitor 906 is normally designed at least two or three times larger than the pixel capacitance Cpix. In this way, it is possible to drive the TN liquid crystal by use of the pixel circuit shown in FIG. 2.
Meanwhile, as a technique having combined effects of the overdrive method and the reset method, Japanese Patent Publication No. 2001-506376 discloses a technique to modulate a common voltage which is a voltage at a common electrode (such as a counter electrode) disposed opposite to a pixel electrode. This technique will be described with reference to FIG. 5. FIG. 5 is a graph showing an operation of the technique to modulate the common voltage, in which the lateral axis indicates the time and the longitudinal axis indicates the voltage and the current.
The common voltage has been conventionally driven at a constant value for a period of one frame cycle (a period from t0 to t2 (or a period from t2 to t4) in FIG. 5 will be defined as one frame cycle), or alternatively, subjected to common inversion drive where the one frame cycle was further divided into two sub-periods and the voltage value was inverted between these two sub-periods. On the contrary, in the technique to modulate the common voltage, the common voltage which is the voltage at the common electrode disposed opposite to the pixel electrode is modulated as shown in FIG. 5. An upper part of FIG. 5 shows variation of the common voltage (VCG) with time and a lower part thereof shows variation of the light transmittance (I) with time which is caused by the response of the liquid crystal. Specifically, a voltage waveform 151 represents a voltage waveform to be applied to the common electrode, an optical intensity waveform 152 represents an optical intensity waveform in a time scale corresponding to the waveform 151, and lines 153 to 156 represent pixel optical intensity curves.
One frame cycle is divided into two sub-periods and a voltage having approximately the same amplitude as in the conventional common inversion drive is applied for a sub-period from t1 to t2 (or a sub-period from t3 to t4). On the contrary, a voltage having higher amplitude than the amplitude in the common inversion drive (such as a voltage higher than the amplitude in the common inversion drive by an amount equivalent to performing a black display) is applied for a sub-period from t0 to t1 (or a sub-period from t2 to t3). According to this technique, it is possible to change the entire display area into the black display at high speed by an effect of an increased voltage differential between the pixel electrode and the common electrode in the sub-period from t0 to t1 when the high voltage is applied to the common electrode. In other words, a driving operation corresponding to the reset drive takes place. In addition, even when image data are written in the pixel electrode in the sub-period from t0 to t1, such data are not observed as a display image because a potential difference from the common electrode is sufficiently large (by an amount of the voltage for the black display, for example). The voltage at the common electrode is set back to the amplitude for the common inversion at the timing of t1 after completion of writing the image data in the entire display area. As a consequence, the liquid crystal layer starts the response equivalent to the transmittance corresponding to each tone level in accordance with the voltage memorized in the pixel electrode. In other words, the voltage differential always changes from the high level to the level corresponding to the voltage value that represents each tone when starting the response. In this context, a sort of overdrive operation takes place in the sub-period from t0 to t1.
As a method of improving the response speed of the TN liquid crystal, there is also a method of increasing the speed by applying a different display mode using nematic liquid crystal. The method includes a method utilizing the electrically controlled birefringence (ECB) mode by taking advantage of birefringence, and a method utilizing the above-described optically compensated birefringence (OCB) mode, for example.
In addition, as the second trend, i.e. as the method of using liquid crystal other than the twisted nematic liquid crystal which can achieve high speed response, there is a technique to use spontaneous polarization type smectic liquid crystal.
However, the above-described conventional techniques have the following problems. First of all, as described previously, the conceivable measures for improving the response speed of the twisted nematic liquid crystal include (1) the measure to reduce the cell gap, (2) the measure to apply the high voltage to the liquid crystal, (3) the measure to increase the dielectric anisotropy, (4) the measure to reduce the viscosity, and (5) the measure to reduce the splay and bend elastic constants and to increase the twist elastic constant.
Of these measures, the cell gap (the thickness of the liquid crystal layer) in the measure (1) can be changed only within a certain relation with refractive index anisotropy Δn so as to obtain a sufficient optical effect. In the meantime, the viscosity in the measure (2), the dielectric anisotropy in the measure (3), and the elastic constants in the measure (5) are all physical values. Accordingly, the values depend largely on the nature of materials and it is therefore extremely difficult to change only the physical values of each material. As a consequence, it is hard to achieve high speed effects as estimated from the formulae. For example, whereas K11, K22, and K33 are mutually independent elastic constants, a correlation defined as K11:K22:K33=10:5:14 is satisfied in many cases according to results of measurement of actual materials (oral disclosure by Merck). Therefore, it is not always appropriate to treat these constants as the independent constants. For instance, it is possible to derive a formula K=11×K22/5 by use of the above-mentioned correlation and the Formula 3. In this case, only K22 is deemed independent.
Meanwhile, the applied voltage in the measure (4) is also restricted because an increase in the voltage causes an increase in power consumption as well as a cost increase in a drive circuit. Moreover, when active elements such as thin film transistors are provided and driven in a display device, the applied voltage is also restricted by withstanding voltage of the elements. Accordingly, the conventional efforts to increase the response speed are almost marginal.
In the meantime, the above-described reset pulse method disclosed in the IDRC 1997 pp. L-66 to L-69 can improve the response speed of the TN type display device to some extent. However, as shown in FIG. 1, the reset pulse method can only achieve a display screen which hardly realizes the original degree of luminance the device is designed for. As a result, there still remains the problem of low light use efficiency and a failure to acquire sufficient light transmittance.
The reason is the fact that the response speed of the typical nematic liquid crystal is slow, and that the response speed of the most widely used TN liquid crystal is slow in particular. Due to the slow response speed, the display device cannot rise sufficiently from the black display at the reset state to the image display mode within a required period, and thereby fails to obtain the required light transmittance. That is, when switching from the black display into the white display, the display device fails to achieve the complete white display and ends up with gray display. On the other hand, when switching from the white display to the black display, the display device fails to achieve the complete black display and ends up with the gray display similarly. Moreover, in a tone display, the response speed may be even slower as described previously. Accordingly, the device cannot achieve expected tone levels when displaying motion images or the like.
In addition, in this reset method the slow response speed also causes the following problem. For example, there is a case where the liquid crystal does not respond sufficiently to achieve the complete black display upon resetting. In this case, the same transmittance may not be obtained by writing the same piece of data for several times. Such an aspect is attributable to a failure to establish the complete predetermined state of alignment of the liquid crystal as a reset operation is imperfect. In this case, the liquid crystal exhibits the transmittance as the response after resetting which reflects a hysteresis of a previous frame. As a consequence, the one-on-one correlation between the applied voltage and the transmittance is not satisfied any longer.
Furthermore, there are problems concerning a slow start of optical response of the liquid crystal after resetting and observation of abnormal optical response prior to the start of the normal optical response. The reason is that the direction of action of the liquid crystal is not definite at the point when the liquid crystal transits from the predetermined state of alignment achieved by resetting to the normal response, and the liquid crystal may perform uneven or unstable response instead.
It is considered that the response time of the TN liquid crystal is equivalent to several tens of milliseconds as a sum of the response time for rising and the response time for decaying, and that the response time becomes much longer and would reach a hundred milliseconds or more as the response during the tone display. As shown in the Formula 1 described above, the response time for rising is normally proportional to a squared value of the thickness. Therefore, a transmissive display device requires four times more response time than a reflective display device. As a result, light use efficiency is significantly deteriorated in the transmissive display device.
Meanwhile, the method of driving the TN liquid crystal in the OCB mode or the like has a problem of stringent demands for production accuracy and uniformity, and a resultant decline in yields. This is because the thickness of the liquid crystal layer requires higher accuracy, or because it is necessary to use optical elements such as compensating films or retardation films that satisfy a high degree of uniformity.
For example, in the case of the electrically controlled birefringence (ECB) mode utilizing the birefringence, the demand for the accuracy of the thickness of the liquid crystal layer is about 3% of the thickness of the liquid crystal layer in order to achieve the contrast equal to 100. In that case, when the thickness is equal to or less than 3 μm, the unevenness in the thickness must be equal to or less than 90 nm. When higher display conditions such as the contrast are required, the demand for the accuracy of the thickness will be even more stringent.
Similarly, the OCB mode also has problems that it is generally difficult to obtain the uniform and stable bend alignment, and moreover, that a high degree of stability is required in the manufacturing process because the cell gap (the thickness of the liquid crystal) and properties of compensating films must be highly uniform.
In either case, the demand for the accuracy of the thickness of the liquid crystal layer is about 3% of the thickness of the liquid crystal layer in order to achieve the contrast equal to 100. In that case, when the thickness is equal to or less than 3 μm, the unevenness in the thickness must be equal to or less than 90 nm. When higher display conditions such as the contrast are required, the demand for the accuracy of the thickness will be even more stringent.
Furthermore, the technique to use the spontaneous polarization type smectic liquid crystal, which can achieve high-speed response, also has the following problems. Specifically, the spontaneous polarization type smectic liquid crystal is also associated with stringent demands for production accuracy and uniformity, and with a resultant decline in yields. This is because, when a smectic liquid crystal mode is used instead of the TN mode in order to increase the response speed, the thickness of the liquid crystal layer requires a higher accuracy. Another reason is that it is necessary to use optical elements such as compensating films or retardation films that satisfy a high degree of uniformity. In the meantime, the spontaneous polarization type smectic liquid crystal requires an extremely high level of flatness of a substrate surface as compared to the nematic liquid crystal of the TN type and the like. In this case, even tiny irregularities on a surface of an indium tin oxide (ITO) electrode, which is a transparent electrode, become problematic.
In this way, all the above-described conventional methods have difficulties in further improving the response speed while maintaining practical yields.

This patent is subject to a terminal disclaimer.

Liquid crystal panel, liquid crystal display device, and electronic equipment


A check valve for gas lift applications can be attached externally to a side pocket mandrel or can be a gas lift valve used in the mandrel. The valve has a seat with a non-elastomeric element and a metal element. A biasing element resiliently biases the non-elastomeric element to provide resiliency to the seal produced. A metal dart moves in the bore relative to the seat and allows or prevents flow through the valve body. When exposed to a first differential pressure, the dart engages the non-elastomeric element resiliently biased by the biasing element. When exposed to a greater differential pressure, the dart engages the metal element, which can be part of the valve in the bore. In one arrangement, the non-elastomeric element can be a thermoplastic component with a metal spring energized seal as the biasing element. Alternatively, the non-elastomeric element can be the jacket of metal spring energized seal with a coil spring as the biasing element.

Operators use gas lift valves in side pocket mandrels to lift produced fluids in a well to the surface. Ideally, the gas lift valves allow gas from the tubing annulus to enter the tubing through the valve, but prevent flow from the tubing to the annulus. A typical gas lift completion 10 illustrated in FIG. 1 has a wellhead 12 atop a casing 14 that passes through a formation. Tubing 20 positioned in the casing 14 has a number of side pocket mandrels 30 and a production packer 22. To conduct a gas lift operation, operators install gas lift valves 40 by slickline into the side pocket mandrels 30. One suitable example of a gas lift valve is the McMurry-Macco® gas lift valve available from Weatherford—the Assignee of the present disclosure. (McMURRY-MACCO is a registered trademark of Weatherford/Lamb, Inc.)
With the valves 40 installed, compressed gas G from the wellhead 12 is injected into the annulus 16 between the production tubing 20 and the casing 14. In the side pocket mandrels 30, the gas lift valves 40 then act as one-way valves by allowing gas flow from the annulus 16 to the tubing string 20 and preventing gas flow from the tubing 20 to the annulus 16. Downhole, the production packer 22 forces produced fluid entering casing perforations 15 from the formation to travel up through the tubing 20. Additionally, the packer 22 keeps the gas flow in the annulus 16 from entering the tubing 20.
The injected gas G passes down the annulus 16 until it reaches the side pocket mandrels 30. Entering the mandrel's ports 35, the gas G must first pass through the gas lift valve 40 before it can pass into the tubing string 20. Once in the tubing 20, the gas G can then rise to the surface, lifting produced fluid in the tubing 20 in the process.
As noted above, the installed gas lift valves 40 regulate the flow of gas from the annulus 16 to the tubing 20. To prevent fluid in the tubing 20 from passing out the valve 40 to the annulus 16, the gas lift valve 40 can use a check valve that restricts backflow.
One type of side pocket mandrel 30 is shown in more detail in FIGS. 2A-2B. This mandrel 30 is similar to a Double-Valved external (DVX) gas-lift mandrel, such as disclosed in U.S. Pat. No. 7,228,909 incorporated herein by reference in its entirety. The mandrel 30 has a side pocket 32 in an offset bulge from the mandrel's main passage 31. This pocket 32 holds the gas lift valve 40 as shown in FIG. 2B. The pocket's upper end has a seating profile 33 for engaging a locking mechanism of the gas lift valve 40, while the pocket's other end has an opening 34 to the mandrel's main passage 31.
Lower ports 36 in the mandrel's pocket 32 communicate with the surrounding annulus (16) and allow for fluid communication during gas lift operations. As shown in FIGS. 2A-2B, these ports 36 communicate along side passages 37 on either side of the pocket 32. When these passages 37 reach a seating area 39 of the pocket 32, these passages 37 communicate with the pocket 32 via transverse ports 38. In this way, fluid entering the ports 36 can flow along the side passage 37 to the transverse ports 38 and into the seating area 39 of the pocket 32 where portion of the gas lift valve 40 positions. As shown in FIG. 2B, the gas lift valve 40 has packings 43 that straddle and packoff the exit of the ports 38 in the mandrel's seating area 39. This is where inlets 42 of the gas lift valve 40 position to receive the flow of gas.
In the current arrangement, the ports 36 on the mandrel 30 can receive external check valves 50 that dispose in the ports 36. The check valves 50 allow gas G flow from the annulus (16) into the mandrel's ports 36, but prevent fluid flow in the reverse direction to the annulus (16). In general, the check valve 50 has a tubular body having two or more tubular members 52, 54 threadably connected to one another and having an O-ring seal 53 therebetween.
The upper end of the valve 50 threads into the mandrel's port 36, while the lower end can have female threads for attaching other components thereto. Internally, a compression spring 58 or the like biases a check dart 55 in the valve's bore against a seat 56. To open the one-way valve 50, pressure from the annulus (16) moves the check dart 55 away from the seat 56 against the bias of the spring 58. If backflow occurs, the dart 55 can seal against the seat 56 to prevent fluid flow out the check valve 50.
During gas lift, for example, the injected gas G can flow through the check valves 50, continue through separate flow paths in the ports 36 and passage 37, and then flow from the transverse ports 38 toward the inlets 42 of the gas lift valve 40. In turn, the gas lift valve 40 allows the gas G to flow downward within the valve 40, through a check valve 45, and eventually flow out through outlets 44 and into the side pocket 32. From there, the gas G flows out through the slot 34 in the mandrel 30 and into the production tubing (20) connected to the mandrel's main passage 31.
Because the gas lift valve 40 and the separate check valves 50 both prevent fluid flow from the tubing 20 into the annulus 16, they can act as redundant backups to one another. Moreover, the check valves 50 allow the gas lift valve 40 to be removed from the mandrel 30 for repair or replacement, while still preventing flow from the tubing 20 to the annulus 16. This can improve gas lift operations by eliminating the time and cost required to unload production fluid from the annulus 16 as typically encountered when gas lift valves are removed and replaced in conventional mandrels.
Various types of check valves can be used with gas lift valves or with other downhole components. For example, FIGS. 3A-3C illustrates types of prior art check valves for use with gas lift valves and mandrels. In particular, FIGS. 3A and 3B respectively show a CV-1 check valve 60A and a CV-2 check valve 60B from Weatherford's McMurry-Macco®CV series of reverse-flow check valves. These check valves 60A-B can attach to the bottom of a gas lift valve, to ports of a side pocket mandrel, or other flow-control device.
As shown, the check valves 60A-B each have an upper housing 62 threadably coupled to a lower housing 64 with an O-ring seal 63 therebetween. Disposed in the bore of the valves 60A-B, a dart 66 is biased by a spring 68 toward a seat 70. As shown in FIGS. 3A-3B, the seat 70 has an elastomeric component 72 and a retainer 74.
Another example of a check valve 60C is shown in FIG. 3C. This check valve 60C is similar to the DVX check valve available from Weatherford. This particular check valve 60C is well suited for a Double-Valved External (DVX) gas-lift mandrel described previously with reference to FIGS. 2A-2B. As shown, this check valve 60C includes an upper body 62 coupled to a lower body 64 by a port housing 65 and O-rings 63. As before, the check dart 66 can move in the port housing 65 against the bias of a spring 68 relative to a seat 70. Here, the seat 70 has a check seal 72 typically composed of elastomer (i.e., elastic polymer), such as nitrile butadiene rubber, hydrogenated nitrile butadiene rubber, fluorocarbon rubber, tetra-fluoro-ethylene-propylene, and perfluoroelastomers.
During a gas lift operation, upstream pressure typically from the surrounding annulus acts against the check valve 60A-C and is higher than the downstream pressure from the tubing. The pressure differential depresses the spring-loaded dart 66 in the valve 60A-C, allowing injection gas to flow through the check valve 60A-C and into the production tubing. If the downstream pressure is greater than the upstream pressure, flow across the check dart 66 forces the dart 66 against the seat 17, which prevents backflow. In the seating process, an elastomeric seal is first established between the dart 66 and elastomeric component 72. As the differential pressure increases, a metal-to-metal seal is then formed for additional protection between the dart 66 and portion of the lower housing 64 forming part of the seat 70.
As seen in FIGS. 3A-3C, check valves 60A-C for gas lift valves use elastomeric resilient seals 72 to provide a secondary seal to the metal-to-metal seal between the check dart 66 and the seat 70. As expected, such a dual seal protects against backflow, prevents casing from damage, and avoids costly workover operations. Unfortunately, the elastomeric seal 72 can be prone to explosive decompression during use.
In explosive decompression, the seal 72 is exposed to gas laden fluid at high pressure, and the compressed gas enters the interstices of the seal's elastomer. As long as operating pressures remain high, the seal 72 remains intact. Whenever the pressure falls, however, the gas in the elastomer of the seal 72 expands and can cause the seal 72 to rupture.
Explosive decompression has been a recognized problem in valve seals, and two solutions have been developed for handling it. In a first solution, specific types of elastomers have been developed that are more resistant than others to explosive decompression. An example of such an elastomer is FKM XploR V9T20, which is available from Trelleborg Sealing Solutions. Although these types of elastomers may be useful, even seals with such elastomers can still have issues with explosive decompression in check valves used for gas lift operations.
Another solution developed in the art has been to use only metal-to-metal sealing with no resilient seal in check valves. An example of such a check valve with only metal-to-metal sealing is the 15K Severe Service MTM Check Valve available from Halliburton. Although exclusive metal sealing may solve problems related to explosive decompression, a check valve utilizing only a metal-to-metal seal can be less reliable in sealing, especially if there is any debris present in the injection fluid. Moreover, the exclusive metal-to-metal seal can be costly to manufacture and maintain.
The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.

Self-boosting, non-elastomeric resilient seal for check valve


A communication connector assembly including a wire board, and a number of elongated terminal contact wires extending above a top surface of the board. The contact wires have free end portions for making electrical contact with a mating connector, and base portions formed opposite the free end portions for supporting the contact wires on the board and for connecting the wires to conductors on or within the board. The base portions project normal from the top surface of the board. Pairs of the contact wires are coupled to one another along a first coupling region between their free end portions and their base portions and horizontal with respect to the top surface of the wire board, so that crosstalk introduced by the mating connector of a given polarity, is reduced over the first coupling region. The base portions are also configured to enter the wire board with a pattern defining one or more second coupling regions wherein the base portions are coupled to one another with a polarity opposite the given polarity, so that the introduced crosstalk is further reduced over the second coupling regions.

1. Field of the Invention
This invention relates to communication connectors that are configured to compensate for crosstalk produced between different signal paths through the connector.
2. Discussion of the Known Art
There is a need for a durable, high-frequency communication connector assembly that compensates for (i.e., cancels or reduces) crosstalk produced between different signal paths carried through the connector. As defined herein, crosstalk occurs when signals conducted over a first signal path, e.g., a pair of terminal contact wires associated with a communication connector, are partly transferred by inductive or capacitive coupling into a second signal path, e.g., another pair of terminal contact wires in the same connector. The transferred signals define "crosstalk" in the second signal path, and such crosstalk degrades any signals that are being routed over the second path.
For example, an industry type RJ-45 communication connector typically includes four pairs of terminal wires defining four different signal paths. In the conventional RJ-45 plug and jack connectors, all four pairs of terminal wires extend closely parallel to one another over the lengths of the connector bodies. Thus, signal crosstalk may be induced between and among different pairs of terminal wires, particularly in a mated RJ-45 plug and jack combination. The amplitude of the crosstalk becomes stronger as the coupled signal frequencies or data rates increase.
Applicable industry standards for rating the degree to which communication connectors exhibit crosstalk, do so in terms of near-end crosstalk or "NEXT". Moreover, NEXT ratings are typically specified for mated plug and jack combinations, wherein the input terminals of the plug connector are used as a reference plane. Communication links using unshielded twisted pairs (UTP) of copper wire are now expected to support data rates up to not only 100 MHz or industry standard "Category 5" performance, but to meet proposed "Category 6" performance levels which call for at least 46 dB crosstalk loss at 250 MHz.
U.S. Pat. No. 5,186,647 to Denkmann, et al (Feb. 16, 1993), which is assigned to the assignee of the present invention and application, discloses an electrical connector with crosstalk compensation for conducting high frequency signals. The connector has a pair of metallic lead frames mounted flush with a dielectric spring block, with connector terminals formed at opposite ends of the lead frames. The lead frames themselves include flat elongated conductors each of which includes a spring terminal contact wire at one end for contacting a corresponding terminal of a mating connector, and an insulation displacing connector (IDC) terminal at the other end for connection with an outside insulated wire lead. The lead frames are placed one over the other on the spring block, and three conductors of one lead frame have cross-over sections formed to overlap corresponding cross-over sections formed in three conductors of the other lead frame. All relevant portions of the '647 patent are incorporated by reference herein. U.S. Pat. No. 5,580,270 (Dec. 3, 1996) also discloses an electrical plug connector having crossed pairs of contact strips.
Crosstalk compensation circuitry may also be provided on or within layers of a printed wire board, to which spring terminal contact wires of a communication jack are connected within the jack housing. See U.S. patent application Ser. No. 08/923,741 filed Sep. 29, 1997, and assigned to the assignee of the present application and invention. All relevant portions of the '741 application are incorporated by reference herein. See also U.S. Pat. No. 5,299,956 (Apr. 5, 1994).
U.S. patent. application Ser. No. 09/264,506 filed Mar. 8, 1999 (now U.S. Pat. No. 6,116,964 issued Sep. 12, 2000), and assigned to the assignee of the present invention and application, discloses a communication connector assembly having generally co-planar terminal contact wires. Certain pairs of the contact wires have opposed cross-over sections near their line of contact with a mating connector, and a coupling region along the wires beyond the cross-over sections compensates for crosstalk introduced by the mating connector. All relevant portions of the '506 application are also incorporated by reference herein.
In the connector assembly of the above '506 application, the terminal contact wires have base portions that enter a wire board alternatingly along two rows which are perpendicular to the direction of the contact wires, thus defining a staggered wire board entry pattern or "footprint". Coupling of a polarity opposite to that needed for crosstalk compensation may be introduced among the base portions of the contact wires, however, and the amount of crosstalk compensation needed elsewhere (e.g., on the wire board) to achieve Category 6 performance may need to be increased as a result.
A so-called "MAX 6" modular jack outlet available from The Siemon Company has a printed wire board and four pairs of contact wires that extend generally normal to the board. No cross-over is formed in any of the wire pairs, and the contact wires enter the wire board along three rows.
A communication jack connector which, when mated with a typical RJ-45 plug, provides such crosstalk compensation that the mated connectors will meet or exceed the proposed Category 6 performance levels, is highly desirable.

Communication connector assembly with crosstalk compensation


It is an object of the present invention to prevent a sheet of continuous-form paper from slackening when it is fed back in a printer capable of feeding both sheets of continuous-form paper and cut-form paper. According to the method for feeding back a sheet of continuous-form paper (6) of the present invention, in a paper feed unit including a pin feed device (7) arranged in an upstream of the continuous-form paper feed passage and also including a friction feed device (4, 5) in which both the pin feed device (7) and the friction feed device (4, 5) feed the sheet of continuous-form paper (6) and a circumferential speed of the friction feed device (4, 5) is a little higher than that of the pin feed device (7), a first amount of feed is set by which the sheet of continuous-form paper is not loosened between the friction feed device (4, 5) and the pin feed device (7) and also a second amount of feed is set which is larger than a difference between an amount of feed of the friction feed device (4, 5) and an amount of feed of the pin feed device (7) when the sheet of continuous-form paper is fed back by the first amount of feed, and the sheet of continuous-form paper is fed back by the first amount of feed when both the friction feed device (4, 5) and the pin feed device (7) are simultaneously reversed, and the friction feed device (4, 5) is normally rotated by the second feed amount under the condition that the pin feed device is stopped. The sheet of continuous-form paper (6) is fed back by repeating the above reverse and the normal rotation.

When a large amount of data is outputted from a printer provided in an information processor, sheets of continuous-form paper are usually used, because there is little possibility of the occurrence of a paper jam or a failure in feeding sheets of paper. On the other hand, sheets of cut-form paper are used in usual office work. Various documents, the amount of data of which is small, are output on the sheets of cut-form paper. When a sheet of continuous-form paper is to be changed in the printing process, the sheet of paper is reversely fed. In this case, it is necessary to prevent the sheet of paper from slackening.
There is provided a paper feed mechanism of a printer in which a drive roller is mounted on a printer body, and an idle roller is mounted on a paper guide detachably attached to the printer body, and the idle roller comes into pressure contact with the drive roller so as to feed sheets of paper. Since the sheet of continuous-form paper is fed by a tractor, that is, by the action of pins, it is sufficient to give a weak force to the idle roller so as to pull the sheets of paper. When the pushing force is strong, sprocket holes are damaged and the tractor is disengaged from holes. When thick sheets of cut-form paper such as postcards are used, it is necessary to increase a pushing force of the idle roller so as to prevent the occurrence of a slippage. Concerning the pushing force of the idle roller, sheets of continuous-form paper and cut-form paper are incompatible with each other. Therefore, it is necessary to change over the pushing force according to the type of sheets of paper.
When a line feed operation is conducted in a conventional printer, in order to ensure a sheet passage for feeding sheets of paper stably, an amount of the gap formed between a printing head and a platen is increased to a predetermined value. However, when sheets of continuous-form paper are processed, on which perforations are formed in the boundary between pages, the perforations protrude from a surface of the sheet of paper. In this case, the printing head is caught by the perforations in the process of line feed, and the accuracy of line feed is deteriorated.
When sheets of cut-form paper are fed, sheets of paper stacked on the paper feed tray are sent out one by one. As a means for sending out sheets of paper one by one, there is provided a paper feed roller which comes into contact with a surface of the stacked sheet of paper and rotates to send them one by one. This type paper feed roller is commonly used. In a business machine, sheets of paper of various widths are used. Accordingly, in order to feed sheets of paper of various widths by one paper feed unit, a plurality of relatively short roller pieces are mounted on one roller shaft in accordance with the widths of the sheets of paper.
In the case of a printer, an OCR (optical character reader) or an image scanner in which the printing position and reading position of information must be accurately set, and all sheets of paper of different widths are guided by a reference side guide arranged at a stationary position on the paper feed tray. In this case, the positions of the roller pieces mounted on the roller shaft are determined in accordance with the widths of the sheets of paper while the reference side guide is used as a reference. Accordingly, intervals of the roller pieces mounted on the roller shaft are not equal. In the paper feed unit arranged as described above, when sheets of paper of the maximum width are fed, all roller pieces come into contact with the sheet surface. When sheets of paper of small width are fed, only the roller pieces within the width come into contact with the sheet surface. In order to feed sheets of paper by the above paper feed unit without causing a skew feed, it is necessary for the plurality of roller pieces to come into contact with the sheet surface with the same pressure.
The sheets of recording paper stacked on a hopper of the printer are fed one by one as follows. The uppermost sheet of recording paper in the stack is fed by the paper feed roller provided at an upper portion of the hopper. In order to prevent the second and later sheets of paper from advancing together with the first sheet of paper at this time, a separating pad is usually arranged opposite to the paper feed roller. When the second sheet of paper advances between the paper feed roller and the separating pad together with the first sheet of paper, the second sheet of paper is blocked by friction force due to the separating pad. In this way, the uppermost first sheet of paper is separated from the second sheet of paper and successively conveyed by the paper feed roller. Then the first sheet of paper is received from the paper feed roller by the conveyance roller, and a printing operation is conducted on the first sheet of paper by the printing section. After the completion of the printing operation, when a printing command is given to the second sheet of paper, the paper feed roller is rotated again, and paper feed operation is conducted in the same manner as that of the first sheet of paper. This operation is repeated and printing is conducted on a predetermined number of sheets of paper.
However, from a time when the first sheet of paper is sent to the printing section by the paper feed roller to a time when the second sheet of paper starts to be fed by the paper feed roller, a leading end of the next sheet of paper is interposed between the paper feed roller and the separating pad. Accordingly, when printing operation is continuously conducted on the next sheet of paper, no problems may be encountered. However, when the sheets of paper are replaced with sheets of paper of different size after the completion of a printing job, the hopper must be removed from the printer. In this case, it is difficult to pick up the sheet of paper, the leading end of which is interposed between the paper feed roller and the separating pad.
In general, when sheets of paper stacked on a tray are separated from each other and automatically fed one by one, a phenomenon of double feed tends to occur in the case where thin sheets of paper are fed, and a failure in feeding tends to occur in the case where thick sheets of paper are fed. When copy sheets composed of a plurality of layers are fed, layers tend to be separated from each other by an increased paper feeding force. Therefore, in order to prevent the occurrence of double feed and separation between layers, the conventional automatic paper feed unit adopts the following means. A paper feed force to be used as a reference force is set at a low value. When thick sheets of paper are fed, it is impossible to feed the sheets by the force of low intensity. In this case, the intensity of the paper feed force is increased.
However, in the conventional structure, the pushing force of the paper feed roller given onto sheets of paper is changed by a plurality of steps. Therefore, a plurality of springs are required for adjusting the pushing force of the paper feed roller, and it is necessary to set the spring force for each spring. When the paper feed resistance is high, the paper feed roller is raised due to the high paper feed resistance. Therefore, it is necessary to provide a space in which the paper feed roller can to be raised upward. When sheets of paper of high paper feed resistance are fed, the following operation is required. After the paper feed roller has been stopped, the paper tray is further raised, and then the paper feed roller is started again to feed the sheets of paper. Therefore, the throughput of sheets of paper is lowered.
In the case of an impact printer having a noise source, noise is mainly caused by an impact head for printing in the printing operation. This noise caused by the impact head leaks outside the printer from the sheet entrance. Therefore, an operator and others feel uncomfortable. In order to solve the above problems, it is necessary to reduce a leakage of noise from the printer as much as possible. In order to attain the above object, the following countermeasures are taken. The sheet feed entrance is made to be small; sound absorbing material is arranged around the sheet entrance; and the impact head is covered with sound absorbing material.
However, problems may be encountered by the above counter measures. When the sheet feed entrance is made to be small and sound absorbing material is arranged close to the sheet feed entrance, the sheet passage becomes narrow, so that the occurrence of a sheet jam tends to occur. In order to solve the above problems, the following countermeasures are taken. There is provided a sound insulating cover attached to the sheet feed entrance, and this cover is made to be opened and closed. Therefore, when sheets of paper pass through the sheet feed entrance, a clearance of the passage is reduced so as to prevent noise from leaking outside. In the case of a sheet jam, the sound insulating cover is opened for jam clearance. However, the above countermeasure is disadvantageous in that the structure is complicated, and a highly sophisticated operation is required.


When a segmented region SAi of a sheet S is scan-exposed, a stage SST1 adsorbs, at a standby position at the +X end portion of a scan region AS, a rear surface portion corresponding to the segmented region SAi of the sheet S onto a holding surface of a sheet holder SH1, and moves in the X axis direction (the −X direction) with a predetermined stroke in synchronization with a mask (a mask stage). At this time, illumination beams corresponding to the parts of a pattern of the mask are irradiated onto the sheet S via projection optical systems. Thereby, the pattern is transferred (formed). After scan-exposure on the segmented region SAi, a stage SST2 moves to a standby position within the XY plane. After the stage SST2 adsorbs a rear surface portion corresponding to the next segmented region SAi+1 of the sheet S onto a holding surface of a sheet holder SH1, an exposure is performed by the scan-exposure method similarly to the above, to thereby form the pattern.

1. Field of the Invention
The present invention relates to a pattern formation apparatus, a pattern formation method, and a device manufacturing method. More particularly, the present invention relates to a pattern formation apparatus and a pattern formation method that form a pattern on a plurality of regions on the surface of a long sheet material by means of scanning exposure, and to a device manufacturing method that uses the pattern formation method to manufacture electronic devices.
2. Description of Related Art
Flat display panels such as liquid display panels and plasma display panels are increasingly growing in size. For example, in the case of liquid display panels, glass substrates (large substrates) with edges more than 3 m long have come to be used for their manufacture in order to efficiently produce a plurality of screen segments in a batch. As a result, in stage apparatuses that hold a substrate, the larger the substrate is, the larger the stage apparatus becomes. In stage apparatuses that process substrates that weigh tens of kilograms, the weight of the movable portions has come to be nearly 10 tons, and the weight of the entire apparatus has come to be over 100 tons. Therefore, in the near future, the substrates are expected to be further larger, resulting in difficulty in their manufacture and transfer. In addition, it is certain that the stage apparatuses will become further larger, requiring heavy investment in building an infrastructure.
On the other hand, there is known an exposure apparatus that uses a rolled-sheet-like recording medium as a substance to be exposed. The exposure apparatus is adopted mainly in the manufacturing field of printed wiring boards. If such an exposure apparatus is used in the manufacture of, for example, liquid display elements, a variety of problems involved in the aforementioned enlarging of the glass substrates are eliminated. Therefore, the exposure apparatus is expected to be one of the options for the future exposure apparatuses for manufacturing liquid crystal elements.
Exposure apparatuses for a conventional sheet-like recording medium include those disclosed Patent Documents (U.S. Pat. No. 5,652,645, U.S. Patent Application No. 2006/0066715, and U.S. Pat. No. 6,243,160). However, if any of the exposure apparatuses is used as it is for manufacturing liquid display elements, it is difficult to achieve desired accuracy and throughput.

Pattern formation apparatus, pattern formation method, and device manufacturing method