When the degree of reliability of a motion vector is equal to or higher than a threshold, an interpolated image is generated, and the image of a frame of interest and the interpolated image are output to a panel in the order named. Every time the image is output, a backlight is turned on. When the degree of reliability is lower than the threshold, the image of the frame of interest is output twice to the panel. Every time the image is output, the backlight is controlled to alternately set its light amount to the first light amount and the second light amount smaller than the first light amount.

1. Field of the Invention
The present invention relates to an image display technique.
2. Description of the Related Art
Recently, liquid crystal display apparatuses have been used as a TV receiver and a PC display apparatus. The liquid crystal display apparatuses can have a flat panel, can save the space and power, and thus are widely used.
When pursuit of a moving object (viewing of tracking a moving object with a line of sight on a moving image display) is performed on a hold type display apparatus typified by a liquid crystal display apparatus, a motion blur corresponding to the light output period in the liquid crystal display apparatus is observed.
As a technique for reducing the motion blur, there is proposed a method of performing an impulse display by flickering the backlight of a liquid crystal display apparatus to perform a black display within one frame period.
In patent literature 1 (Japanese Patent Laid-Open No. 2001-183622), a light emitter is arranged to increase the intensity of light irradiating a pixel in synchronism with scanning of a liquid crystal display panel by increasing the intensity of light irradiating the pixel after scanning, and then decrease the light intensity, or to irradiate the pixel with light and then stop the emission. The method in patent literature 1 can reduce a motion blur.
The method of flickering the backlight in synchronism with scanning of the liquid crystal panel can reduce a motion blur by shortening the lighting period of the backlight and shortening the black display period within one frame period. However, the flicker is visually recognized.

Image display apparatus and image display method


A discharge valve (30) is provided in a high-pressure fuel passage (31) to allow fuel to pass through the discharge valve (30) only in a direction from a high-pressure fuel pump (20) toward a delivery pipe (50). A communication passage (41) with an orifice (42) is formed integrally with the discharge valve (30) in parallel with the discharge valve (30) to connect areas upstream and downstream of the discharge valve (30). When a fuel pressure in the delivery pipe (50) is increased to a target pressure using the high-pressure fuel pump (20), an amount of the fuel, which does not interfere with an increase in the fuel pressure, flows through the orifice (42). A check valve (40) is provided in the communication passage (41), and opened to allow the fuel to pass through the check valve (40) only in the direction from the delivery pipe (50) toward the high-pressure fuel pump (20), when the fuel pressure is higher than a first predetermined pressure.

1. Field of the Invention
The invention relates to a high-pressure fuel supply apparatus for an internal combustion engine.
2. Description of the Related Art
For example, in a fuel system for an in-cylinder injection internal combustion engine, a high-pressure fuel pump, which increases a pressure of fuel, is employed to inject the fuel directly into a cylinder. In the fuel system, the fuel supplied from a fuel tank by a low-pressure fuel pump is pressurized by the high-pressure fuel pump so that the fuel is delivered under pressure to a fuel injection valve through a high-pressure fuel passage and a delivery pipe. A fuel pressure in the delivery pipe is adjusted, and maintained at a predetermined high pressure by, for example, a high-pressure regulator.
In the configuration in which the pressure in the delivery pipe is maintained at a high pressure, after the engine is stopped, the pressure in the delivery pipe may not be decreased, that is, the pressure in the delivery pipe may be maintained at a high pressure. Therefore, the fuel may leak from the fuel injection valve. The fuel that leaks from the fuel injection valve is accumulated in the cylinder, and the accumulated fuel, which remains unburned, is discharged when the engine is started next time. This may result in deterioration of emissions at an engine start time. For example, Japanese Patent Application Publication No. 2006-90222 describes a configuration in which a discharge valve with a leak function is provided between the high-pressure fuel pump and the delivery pipe to suppress the leakage of the fuel. The discharge valve with the leak function is provided in the high-pressure fuel passage. The discharge valve allows the fuel to pass through the discharge valve only in the direction from the high-pressure fuel pump toward the delivery pipe. Pores, which are constantly open, are provided in the discharge valve. In the configuration, when the engine is stopped while the pressure at the side where the delivery pipe is provided is higher than the pressure at the side where the high-pressure fuel pump is provided, the high-pressure fuel at the side where the delivery pipe is provided is returned toward the high-pressure fuel pump through the pores. As a result, the fuel pressure in the delivery pipe is decreased. Thus, it is possible to suppress the leakage of the fuel.
The fuel is returned toward the high-pressure fuel pump through the discharge valve with the leak function described in the publication No. 2006-90222, until the pressure at the side where the delivery pipe is provided is equal to the pressure at the side where the high-pressure fuel pump is provided. Therefore, it is difficult to appropriately adjust the pressure at the side where the delivery pipe is provided.
If the pressure in the delivery pipe decreases after the engine is stopped, a temperature at which the fuel is vaporized (i.e., a vaporization temperature) also decreases. Further, the temperature of the fuel in the delivery pipe increases because a temperature in an engine room increases, for example, due to stop of an engine cooling system. As a result, the temperature of the fuel in the delivery pipe may exceed the vaporization temperature at which the fuel is vaporized. Thus, vapor (bubbles) may be generated in the delivery pipe. That is, in the configuration described in the publication No. 2006-90222, although the leakage of the fuel from the fuel injection valve is suppressed, the vapor may be generated in the delivery pipe. If the vapor is generated in the delivery pipe, the vapor is retained in the delivery pipe, or discharged from the fuel injection valve together with the fuel. This may result in deterioration of startability of the internal combustion engine.

High-pressure fuel supply apparatus for internal combustion engine


The present invention provides a system and methods for assaying nucleic acid molecules with reduced levels of background signal and enhanced specificity and sensitivity. In particular, the present invention provides a system and methods for detecting, sorting, tracking and characterizing nucleic acid molecules using hybridization assays with reduced levels of undesirable cross hybridization and reduced levels of intramolecular secondary structure.

Numerous analytical methods in molecular biology, biochemistry and biophysics rely on the hybridization of a nucleic acid molecule to a complementary nucleic acid molecule. These methods include Southern and Northern blot hybridization, fluorescence in situ hybridization (FISH), gene-chip array technologies, and polymerase chain reactions (PCR). One goal of these methods is to determine the presence and/or amounts of nucleic acid molecules containing a particular nucleotide sequence(s) of interest. In general, nucleic acid molecules are labeled with a detectable marker such as a radioactive or a fluorescent marker. After sequence-specific hybridization of two nucleic acid molecules, the presence and/or level is measured using the marker.
The development of DNA "chips" which are arrays of nucleic acid molecules on a solid support such as a glass surface, has greatly increased the number of nucleotide sequences that can be assayed simultaneously within a given sample (Chee, M., et al., (1996) Science 274, 610-614). In particular, array-based hybridization assays can simultaneously monitoring of thousands of hybridization reactions from one sample allowing researchers to obtain information on the presence and quantities of numerous nucleic acids having numerous sequences of interest (Solas et al. Proc. Natl. Acad. Sci. USA 91:5022-5026, 1994; Blanchard and Hood. Nature Biotechnology. 14:1649, 1996; and DeRisi et al. Science. 278:680-686, 1997). These assays may be applied to a wide range of applications such as single-nucleotide polymorphism (SNP) genotyping, gene expression profiling, and resequencing DNA.
A typical DNA array consists of a set of oligonucleotides bound to a solid support surface such as silicon or glass. A fluorescently labeled target sample mixture of DNA or RNA fragments is brought in contact with the array and allowed to hybridize with the synthesized oligonucleotides. In theory, the conditions only allow hybridization between a region of a target molecule and a complementary oligonucleotide on the surface. Therefore, detecting areas of fluorescence on the surface provides information about the nucleic acid content in the sample. However in practice, cross-hybridization is a significant source of error in a standard array-based hybridization assay, and reduces the sensitivity and selectivity of the assay and/or introduces background signals.
In general, cross-hybridization is the undesired binding of two or more nucleic acid molecules, and depends on the specific protocol of the method employed. For DNA array based assays, one form of cross hybridization which produces experimental error and limits the power of the assay, occurs when regions of target nucleic acids in a sample hybridize to an improper site on the DNA array. Such cross hybridization may result in false positive and negative signals in the assay. Additional cross hybridization occurs when nucleic acid molecules in a sample (target) hybridize to themselves or to other nucleic acid molecules in the sample.
The control of cross-hybridization is particularly important for methods that employ massively parallel arrays of hybridization probes such as for DNA chips. Such arrays depend solely upon hybridization for specificity since there is no enzyme-based proofreading of duplexes as in methods based upon Sanger dideoxy sequencing or the polymerase chain reaction. In addition, the large number of probes reduces the ability to verify the specificity of all probe-target interactions that are detected in a given assay. Thus, the accuracy of data obtained using DNA microarrays is greatly improved by minimizing cross-hybridization. Therefore, a particularly problematic form of cross-hybridization occurs in DNA gene chip technology when a nucleic acid in a sample hybridizes to the wrong probe on the DNA chip.
Fragmentation of the target reduces cross hybridization to some degree since shorter targets offer fewer secondary sites for binding by another target molecule. However, fragmentation also decreases signal for detection of target molecules (e.g. if the target has been randomly labeled with a reporter molecule), and increases the complexity of sample preparation protocols. Fragmentation is particularly problematic in differential expression studies where two samples labeled with different reporter molecules must be reproducibly and identically fragmented.
Therefore, there is a need for methods of analyzing nucleic acid molecules that reduce undesired hybridization between two or more nucleic acid molecules.

Use of unstructured nucleic acids in assaying nucleic acid molecules


A turbine blade with a squealer pocket formed by a tip rail extending along the pressure side and suction side of the tip. A row of diffusion notches are spaced along the inner sides of the pressure side tip rail and the suction side tip rail, each notch formed by a peak and a valley and opening into the pocket to function as a diffuser. Each notch is supplied with cooling air through a tip convective cooling hole that opens into the bottom of each notch. The pocket floor is without tip cooling holes so that the cooling air discharged into the notches function to push away the vortex flow that would form along the inner side of the tip rails to improve the cooling effectiveness and reduce the tip rail metal temperature.

1. Field of the Invention
The present invention relates generally to a turbine blade, and more specifically to a turbine blade with tip cooling.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
In a gas turbine engine, especially an industrial gas turbine engine, the turbine includes stages of turbine blades that rotate within a shroud that forms a gap between the rotating blade tip and the stationary shroud. Engine performance and blade tip life can be increased by minimizing the gap so that less hot gas flow leakage occurs.
High temperature turbine blade tip section heat load is a function of the blade tip leakage flow. A high leakage flow will induce a high heat load onto the blade tip section. Thus, blade tip section sealing and cooling have to be addressed as a single problem. A prior art turbine blade tip design is shown in FIGS. 1-3 and includes a squealer tip rail that extends around the perimeter of the airfoil flush with the airfoil wall to form an inner squealer pocket. The main purpose of incorporating the squealer tip in a blade design is to reduce the blade tip leakage and also to provide for improved rubbing capability for the blade. The narrow tip rail provides for a small surface area to rub up against the inner surface of the shroud that forms the tip gap. Thus, less friction and less heat are developed when the tip rubs.
Traditionally, blade tip cooling is accomplished by drilling holes into the upper extremes of the serpentine coolant passages formed within the body of the blade from both the pressure and suction surfaces near the blade tip edge and the top surface of the squealer cavity. In general, film cooling holes are built in along the airfoil pressure side and suction side tip sections and extend from the leading edge to the trailing edge to provide edge cooling for the blade squealer tip. Also convective cooling holes also built in along the tip rail at the inner portion of the squealer pocket provide additional cooling for the squealer tip rail. Since the blade tip region is subject to severe secondary flow field, this requires a large number of film cooling holes that requires more cooling flow for cooling the blade tip periphery. FIG. 1 shows the prior art squealer tip cooling arrangement and the secondary hot gas flow migration around the blade tip section, FIG. 2 shows a profile view of the pressure side and FIG. 3 shows the suction side each with tip peripheral cooling holes for the prior art turbine blade of FIG. 1.
The blade squealer tip rail is subject to heating from three exposed side; 1) heat load from the airfoil hot gas side surface of the tip rail, 2) heat load from the top portion of the tip rail, and 3) heat load from the back side of the tip rail. Cooling of the squealer tip rail by means of discharge row of film cooling holes along the blade pressure side and suction peripheral and conduction through the base region of the squealer pocket becomes insufficient. This is primarily due to the combination of squealer pocket geometry and the interaction of hot gas secondary flow mixing. The effectiveness induced by the pressure film cooling and tip section convective cooling holes become very limited.
FIG. 4 shows a prior art turbine blade with a tip rail cooling design. A pressure side film cooling hole located on the pressure side wall of the blade and below the pressure side tip rail discharges a film layer of cooling air slightly upward and out onto the surface of the pressure side wall to flow over the pressure side tip rail. A similar suction side film cooling hole is located on the suction side wall. Two tip convective cooling holes discharge cooling air into the squealer pocket and produce a vortex flow of the cooling air as represented by the swirling arrows. These two holes are located adjacent to the inner sides of the tip rails. In the FIG. 4 tip rail design of the prior art, the vortex flow develops on the inner sides of both tip rails and travels along the inner side from the leading edge to the trailing edge of the tip pocket.
This problem associated with turbine airfoil tip edge cooling can be minimized by incorporation of a new and effective blade tip cooling geometry design of the present invention into the prior art airfoil tip section cooling design.


An improved semiconductor construction and method of fabrication having a luminous element for emitting light is provided composed of a layer having a pn junction formed with a first semiconductor layer of a first conductivity type and a second semiconductor layer of a second conductivity type on an upper portion of a luminescent layer. In one portion of the above-described layer, an area for a current path consisting of the second conductivity type is formed extending from the second semiconductor layer to the first semiconductor layer. An ohmic contact electrode is then created covering substantially the entire upper surface of the second semiconductor layer with the exception of the area defined for the current path.

1. Technical Field
This invention relates to a semiconductor element having an ohmic contact construction and a method of producing that element.
2. Background of the Prior Art
As an example of a semiconductor element, the following discussion will focus on a luminous element emitting light from its upper surface, having a very short path of emission, and composed of materials of the AlGaAs family.
In the AlGaAs family, the ohmic contact resistance can be easily reduced by using GaAs without the Al, and an n-type material. Accordingly, an n-type GaAs material is widely used as the cap layer to achieve electrode and ohmic contact.
FIGS. 7A through 7E show a process used to produce a luminous element emitting light from its upper surface. More particularly, FIGS. 7D and 7E show, respectively, a cross section of the completed luminous element and an overhead view of its upper surface.
As shown in FIG. 7A, a p-type AlGaAs lower cladding layer 41, a GaAs active layer 42, an n-type AlGaAs upper cladding layer 43 and an n-type GaAs cap layer 44 are successively grown on a p-type GaAs substrate 40. A circular pattern is then created in FIG. 7B in the center portion of the upper surface of cap layer 44 for the luminescent area. The pattern is formed by photolithography using an AZ-resist 45 as a mask. The unmasked area is then removed by etching down to the depth of the lower cladding layer 41. After etching, the entire surface is covered with an insulating film consisting primarily of SiO.sub.2 46.
As shown in FIG. 7C, the AZ resist 45 and the insulating film above it are then removed. Next another circular pattern, smaller than the aforementioned AZ resist 45, is formed on cap layer 44, again using AZ resist as a mask (not pictured). This AZ resist allows an electrode 47 for the n-side to be fused by vapor deposition to the periphery of cap layer 44 and the entire surface of insulating film 46. The aforementioned AZ resist is then removed. By this process, light emission window 47a is formed, and the n-side electrode 47 is brought into ohmic contact with cap layer 44 in an annulus 47b around window 47a.
Because the n-type GaAs cap layer 44 functions as an absorption layer for the emitted light, the central portion of cap layer 44 is removed as seen in FIG. 7D by etching, leaving only the peripheral portion lying beneath the ohmic contact annulus 47b. Thus, as shown in top view in FIG. 7E and by cross-section in FIG. 7D, the light emission window 44a is extended through cap layer 44.
In order to shorten the path of emission in this type of element, which emits light from its upper surface, the area surrounding the portion emitting light is etched away with the result that the current flow is confined to a constricted region. Correspondingly, the ohmic contact with the electrode is restricted to the portion 47b of the uppermost layer.
For the crystal in the uppermost layer, a material must thereby be chosen which can minimize the contact resistance, and the surface of the element must be covered with this material. However, since this material will absorb light, it will reduce the output of the light emitting element. Thus, it is necessary to use a process (i.e., the creation of window 44a) which will remove, by etching or some similar procedure, the portion of the surface which overlies the area of emission.
If the path of emission is made shorter, the area of the ohmic resistance portion will also be reduced. As a result, the driving voltage will increase, and because of increased heat dissipation, an anticipated improvement in light output will not occur.
In order to judge the quality of ohmic contact, the contact resistance (.OMEGA..multidot.cm.sup.2) is evaluated as to whether it is larger or smaller than 10.sup.-5 ; the smaller the contact resistance, the better the contact. With the aforementioned luminous element which emits light from its upper surface, Rc=5.times.10.sup.-6 (.OMEGA..multidot.cm.sup.2), the inner diameter of ohmic contact portion 47b is 80 .mu.m. and its outer diameter is 100 .mu.m. Thus, the area of contact is approximately 3.times.10.sup.-5 cm.sup.2, and the contact resistance is approximately 0.17 .OMEGA..
If the area of light emission is made even smaller, the ohmic contact area will be further reduced, resulting in an additional further increase in contact resistance. Any increase in the resistance component is expressed as a greater production of heat, which lowers the output of the luminous element.
Several examples of luminous elements exist which emit light from their edges. These elements use a diffusion process to form the constricted region in which current can flow.
FIG. 8 shows an example of a Channeled Substrate Planar laser ("CSP laser") design. A CSP laser is constructed by first forming a groove on an n-type GaAs substrate 50 by photolithography or another similar process. To this substrate are then added, successively: an n-type AlxGa.sub.1-x As lower cladding layer 51; a p-type AlyGa.sub.1-y As active layer 52; a p-type Al.sub.x+ Ga.sub.1-x As upper cladding layer 53; and an n-type GaAs cap layer 54. The p+-type Zn diffusion area 55 is formed in cap layer 54 and upper cladding layer 53; the p-side electrode 57 is formed on the growth surface, and an n-side electrode 56 is formed on the substrate's undersurface.
In this way, a portion of the uppermost n-type layer, such as cap layer 54, and a portion of the p-type layer are interchanged through the use of a Zn diffusion process, thus forming a restricted region in which current can flow. Further, the entire surface of cap layer 54 is covered by a p-type electrode 57, which makes ohmic contact with the narrow area 55 where the p-layer and n-layer are interchanged.
As stated previously, the quality of ohmic contact is judged by the Rc. For example, if Rc=5.times.10.sup.-6 (.OMEGA..multidot.cm.sup.2), the area of region 55 where the p-layer replaces the n-layer will be 1.5.times.10.sup.-5 cm.sup.2, and the contact resistance will be approximately 0.33 .OMEGA.. If the area where the p-layer replaces the n-layer is made even smaller, in order to reduce the luminous area, the resistive component resulting from the contact resistance will increase.
FIG. 9 is a graph illustrating how the forward voltage and current characteristics depend on the Rc in a luminous element. As the contact resistance increases, it causes the driving voltage to increase. The increase in contact resistance becomes evident as an increase in the calorific value which causes a decrease in the output of the luminous element.
When a diffusion process is used, the conductivity types are interchanged on a portion of the uppermost layer. This construction yields a luminous element with a constricted current path which emits light from its edges. Some other examples of this type of luminous element are Terraced Substrate lasers ("TS lasers") and Transverse Junction Stripe lasers ("TJS lasers"). However, these elements, too, are constructed by directly covering an area of reversed polarity with an ohmic electrode. This gives rise to problems in minimizing the contact resistance. If the area of reversed polarity is reduced, the increase in contact resistance will cause the driving voltage to increase, and the increased generation of heat will prevent any improvement of luminous output.

Semiconductor element and its method of manufacturing


In an electrocardiography measurement method and device, a signal processor determines a baseline value, a maximum wave amplitude value, and a minimum wave amplitude value in an electrocardiogram signal. When the signal processor determines that a difference of the maximum wave amplitude value minus the baseline value is less than a difference of the baseline value minus the minimum wave amplitude value, the signal processor performs a correction process for correcting the electrocardiogram signal.

1. Field of the Invention
The present invention relates to an electrocardiography measurement method and an electrocardiography measurement device applying the same.
2. Description of the Related Art
FIG. 1 shows a conventional basic portable card-type electrocardiography measurement device 1. For user convenience, this type of measurement device uses 1-Lead electrocardiography for reading a cardio electrical signal of a subject, i.e., the subject's right and left hands respectively contact (press on) first and second electrodes 11, 12 of the electrocardiography measurement device 1 for obtaining an electrocardiogram of the subject. By design, the right hand has to contact the first electrode 11, and the left hand has to contact the second electrode 12. If the right and left hands contact the first electrode 11 and the second electrode 12 in a reversed manner (electrode inversion), the electrocardiography measurement device 1 will output an inverse electrocardiogram, which affects a reading on the electrocardiogram. However, not every subject is always careful enough to contact the first and second electrodes 11, 12 correctly.
Therefore, if an electrocardiography measurement device is able to automatically detect for electrode inversion and perform a correction process for obtaining a correct electrocardiogram, it would be more convenient for the subject using the electrocardiography measurement device.

Electrocardiography measurement method and an electrocardiography measurement device applying the same


A nozzle device includes three or more rail members, three or more slider members, three or more arm members, a nozzle portion, and a drive mechanism. The three or more rail members each includes rails parallel with each other. The three or more slider members are connected to the rail members to be movable along the rails, respectively. The three or more arm members are connected to the slider members, and movably and rotatably supported in the rail members through the slider members, respectively. The nozzle portion is rotatably connected to the three or more arm members to inject a material and emit an energy beam. The drive mechanism includes at least five actuators that set one of a relative position and a relative angle between each of combinations of two mutually connected elements among the rail members, the slider members, the arm members, and the nozzle portion.

Conventionally, an additive manufacturing apparatus for manufacturing an object by adding layers has been known. The additive manufacturing apparatus forms a material layer by feeding a powder material and emitting a laser beam from a nozzle to melt the powder, and adds layer upon layer of the material to manufacture an object. A known additive manufacturing apparatus of this kind includes a movable stage on which a manufactured object is mounted.
For this kind of additive manufacturing apparatus, it is significant to attain a nozzle device and an additive manufacturing apparatus with a novel nozzle-moving structure, for example. In particular, it is desirable to realize a nozzle drive mechanism with a simple structure and good mobility.

Nozzle device and additive manufacturing apparatus


This invention relates to a method of measuring mass flow of a first gas component in a gas consisting of one or more known gas components. Typically such methods assume that certain parameters were constant, such as the gas composition, pressure and/or temperature, and likewise the heat capacity, density, etc., of the gas were presumed to be such that they could be determined to have a constant value. However, it has been found that the determination of the mass flow is associated with a comparatively high degree of measurement uncertainty, when it is assumed that the parameters are constant. The core of the invention relies on this discovery and on a method wherein all of the gas parameters that are used in the determination of the mass flow of the first gas component and that may vary considerably as a function of the gas composition, pressure and/or temperature are determined continually.

When determining the mass flow of one or more gas components in a gas composed of one or more gas components it is common to assume that some of the gas parameters, such as temperature, gas composition, density, etc, are unchanged in order to enable determination of the mass flow of individual gas components in the composite gas.
However, this may give rise to high measurement uncertainties, since typically such gas parameters may vary over time and hence influence the determination of the mass flow of one or more of the individual gas components. Of course, it is inconvenient since, eg in fermentation processes in breweries, putrefaction processes in putrefaction tanks, gas outlets from biogas plants, etc, it is expedient to be able to determine the individual gas mass flows accurately—either to enable monitoring of the process or to be able to impose users, if any, a tax in response to the mass flow of the one or more of the gas components.
Therefore there is a need for a method of measuring the mass flow of a first gas component in a composite gas, wherein the method is associated with considerably reduced measurement uncertainties compared to the known methods.

Method for measuring mass flow of a multi-component gas


A first organic resin layer is formed over a first substrate; a first insulating film is formed over the first organic resin layer; a first element layer is formed over the first insulating film; a second organic resin layer is formed over a second substrate; a second insulating film is formed over the second organic resin layer; a second element layer is formed over the second insulating film; the first substrate and the second substrate are bonded; a first separation step in which adhesion between the first organic resin layer and the first substrate is reduced; the first organic resin layer and a first flexible substrate are bonded with a first bonding layer; a second separation step in which adhesion between the second organic resin layer and the second substrate is reduced; and the second organic resin layer and a second flexible substrate are bonded with a second bonding layer.

A technique by which a transistor is formed using a semiconductor film formed over a substrate having an insulating surface has been attracting attention. The transistor is applied to a wide range of electronic devices such as an integrated circuit (IC) or an image display device (display device). A silicon-based semiconductor material is widely known as a material for a semiconductor thin film applicable to a transistor. As another material, an oxide semiconductor has been attracting attention.
For example, a transistor whose active layer includes an amorphous oxide semiconductor containing indium (In), gallium (Ga), and zinc (Zn) is disclosed in Patent Document 1.
For a display device, it is required to improve the flexibility or impact resistance besides a reduction in the thickness and weight. For example, Patent Document 2 discloses a flexible active matrix light-emitting device in which an organic EL element and a transistor serving as a switching element are provided over a film substrate.

Display device and method for manufacturing the same

Semiconductor Energy Laboratory Co., Ltd.


Methods of varying the stiffness of polymeric medical tubes.

Catheters are used to treat several different types of medical conditions and typically include an elongated shaft or tube that is inserted into and through a passageway or lumen of the body. Catheters, and in particular intermittent urinary catheters, are commonly used by those who suffer from various abnormalities of the urinary system, such as urinary incontinence. With the advent of intermittent urinary catheters, individuals with urinary system abnormalities can self-insert and self-remove intermittent catheters several times a day to drain the bladder.
In some applications, it may be desirable for a catheter to vary in flexibility along the catheter tube so that the catheter includes the benefits of both a stiff and soft catheter in a single catheter device. That is, it may be desirable for one or more sections of the catheter tube to be more pliable or flexible than other sections. For example, because of the natural contours of the urethra, it may be desirable for a urinary catheter tube to have a softer, more flexible proximal insertion end portion that enables easier insertion of the catheter tube into the urethra. The more flexible proximal end portion also may aid in the navigation of the catheter tube through the natural contours of the urinary system. A more flexible proximal end portion may be especially beneficial to male users wherein the more flexible proximal end portion may aid in advancement and navigation through the curved path of the urethra of a male user. It may also be desirable for the catheter to have a stiffer rear section that facilitates the user's handing and maneuverability of the catheter.
Therefore, there is a need for catheters having varying flexibility and methods for making the same.

Methods of selectively modifying the flexibility of medical tubes


For a first feature of a dataset having a plurality of features, training a classifier to predict the first feature in terms of other features in the data set to obtain a trained classifier; scrambling the values of a second feature in the data set to obtain a scrambled data set, executing the trained classifier on the scrambled data set, determining predictive importance of the seconds feature in predicting the first feature based at least in part on the accuracy of the trained classifier in predicting the first feature when executed with the scrambled data set and creating a graph of the data set in which each of the first and the second features is a node of the graph and a label on an edge between the first node and the second node is based at least in part on the predictive importance of the first feature in terms of the second feature.

A data set may be thought of as a collection of data elements or data points, each with a set of several features. A feature, in turn, may be thought of as a variable having a specific value for a specific data point. Thus, for example, a data set comprising car data may have a data point for each car model in current use, and each data point, corresponding to a particular car, may have features such as make, model, year, type, weight, fuel consumption, original price, color and engine capacity. For instance, a particular vehicle, the Runabout, manufactured by the CarCo company might have a data point with the following values for the listed feature set: (CarCo, Runabout, 1999, Minivan, 4900 lbs, 18 mpg, $23,000, navy blue, 3.0 liters).
A supervised data set is a data set in which each data point has been labeled with an identifying or a predictive label. Thus for the car data set, a label such as "family car" may be applied to cars with the feature type having a value Minivan, Sedan, or SUV; a label such as "fuel efficient" may be applied to cars with a fuel consumption value greater than 27 mpg. These labels are examples of identifying labels. Other labels may be numerical values, such as annual cost to insure, which may be turn out to depend primarily on, for example, on a car's type, weight, engine capacity, and year.
Machine learning is a field which, in a relevant aspect, includes trainable classifiers. A trainable classifier is in one instance a processor-based system that is trained using a supervised dataset; the same phrase may also be used to refer to a software program or programs that reside on storage in the processor based system or in a passive data storage medium and may be executed to operate the classifier. Once trained on a set of supervised data, a classifier may then predict a label for a new data point that is not in the dataset that was used for training. Thus, a classifier for car data that is trained on a data set with insurance costs as predictive labels may then be able to predict insurance costs for a car that is not in the training data set by being able to determine the closeness of the new data point corresponding to the new car to other data points on which the classifier has previously been trained. Thus, by determining a likely value for the label, the classifier is able to predict an insurance cost estimate for the car.
Trainable classifiers are known in the art and include tree-based and forest-based classifiers. A well known tree-based classifier is the Classification and Regression Tree (CART), from Breiman L., Classification and regression trees. (Wadsworth, 1984), based on a binary decision tree. A well known forest-based classifier is one based on a regression forest of trees, such as MART, described in Elements of Statistical Learning, by Hastie, Tibshirani and Friedman (Springer-Verlag, 2001). Many other classifiers are known in the art.
Dependency networks consist of a data set where the dependency of each feature on all the others is measured and sometimes visualized. Dependency networks are used as "collaborative filtering" networks and may be applied, as is known in the art, in such applications as predicting which book a customer may buy, given the books that the customer has purchased previously from a vendor and the dependencies those books had for previous customers. Manufacturers have used dependency networks to detect multiple joint causes of failure in factory systems. Dependency networks are mostly derived from statistical decision trees (Hastie et al., supra) where the first several decision split variables are considered the main dependencies. As is known in the art, split variables generally are variables which separate the data into consistent classes most efficiently. Decision split variables are not very stable in regards to adding or subtracting data points to the data set from which the dependency network is derived.

Decision forest based classifier for determining predictive importance in real-time data analysis


Disclosed herein is a multi-axle component for a constant-velocity drive type driveshaft joint system, comprising: a rotation shaft comprising an end distal to a joint region, and an end proximate to the joint region; a generally cylindrical ball receiving housing located at the proximate end, comprising a cylindrical wall adapted to receive at least a partially spherically shaped shaft end; at least two holes provided in the cylindrical wall that are axially displaced from one another along a rotation axis of the multi-axle component; and a pin that extends through only one of the axially displaced holes at a time to join the shaft end with the multi-axle component. Furthermore, a wheel axle system for a constant-velocity drive type driveshaft joint, is provided that uses the multi-axle component

Disclosed herein is a wheel axle for constant-velocity drive (CVD) type driveshaft joint and an associated system utilizing such a joint. Constant-velocity joints, also called homokinetic joints, allow a drive shaft to transmit power through a variable angle, at constant rotational speed. This is done while keeping friction and play at a minimum.
In known such devices, the location of the joint itself remains at a fixed axial distance from a shaft to which a wheel hex used to mount the shaft, and thus, the characteristics of the CVD joint system cannot be readily varied.

Wheel axle for a constant-velocity drive type driveshaft joint with adjustable axial positions


The present invention provides a scintillator panel which is provided with a narrow-width barrier rib with high accuracy in a large area, and also has high luminous efficiency and realizes clear image quality. The present invention provides a scintillator panel including a sheet-like substrate, a barrier rib provided on the substrate, and a scintillator layer made of a phosphor filled in cells divided by the barrier rib, wherein a reflecting layer is formed on only one side of the barrier rib.

Heretofore, X-ray images using films have widely been used in medical settings. However, the X-ray image using a film provides analog image information, and thus digital radiation detection devices such as computed radiography (CR) and flat panel radiation detection devices (flat panel detectors: FPDs) have recently been developed.
In a flat panel X-ray detector (FPD), a scintillator panel is used for converting radiation into visible light. The scintillator panel contains an X-ray phosphor such as cesium iodide (CsI) and the X-ray phosphor emits visible light in response to applied X-ray, and the emitted light is converted into an electric signal by a thin film transistor (TFT) or a charge-coupled device (CCD) to thereby convert X-ray information into digital image information. However, the FPD has a problem such as a low S/N ratio. In order to increase the S/N ratio, there have been proposed methods of irradiating with X-ray from a light detector side (Patent Literatures 1 and 2), and also there have been proposed methods of filling cells divided by a barrier rib with an X-ray phosphor, so as to reduce an influence of the scattering of visible light due to the X-ray phosphor (Patent Literatures 3 to 6).
The method which has hitherto been used as a method for forming the barrier rib is a method of etching a silicon wafer, or a method in which a glass paste as a mixture of a pigment or a ceramic powder and a low melting point glass powder is pattern-printed in multiple layers using a screen printing method, and then fired to form a barrier rib. However, in the method of etching a silicon wafer, the size of a formable scintillator panel is limited by the size of the silicon wafer, and a scintillator panel having a large size of 500 mm square could not be obtained. A plurality of small-size panels should be arranged for making a large-size panel. However, it is difficult to produce the scintillator panel in view of accuracy, and a large-area scintillator panel was scarcely produced.
In the multi-layer screen printing method using a glass paste, it is difficult to process with high accuracy due to a dimensional variation of a screen printing sheet, or the like. When multi-layer screen printing is performed, a definite barrier rib width is required for increasing the strength of a barrier rib in order to prevent destructive defects of the barrier rib. However, if the width of the barrier rib increases, a space between barrier ribs becomes relatively small, so that a volume available for filling an X-ray phosphor decreases, and the filling amount is not uniform. Therefore, a scintillator panel obtained in this method has a disadvantage such as a decrease in luminescence or occurrence of luminous unevenness because of too small amount of an X-ray phosphor. This disadvantage of flexibility is an obstacle to formation of clear images in photographing at a low dose.


A method, device, and system for controlling power delivered to a power-consuming device. The device can harvest power from a conductor carrying a high voltage using a power harvesting device. The device can include a power storage device to power a hardware processor and a communication component when there is no voltage flowing through the conductor. The device can determine when a control event is to occur. At such time, the device terminates control power delivered to the power-consuming device and continues to withhold the control power until the control event expires. When the control event has ended, the device allows control power to flow to the power-consuming device. The device uses a timer and the communication component to send and receives signals associated with a control event to a user. The device can also operate in a limited mode to conserve power when the device is not in use.

LCSs (sometimes referred to as load control receivers (LCRs)) are used as part of a demand-side management scheme to control the operation of certain power-consuming devices. Examples of such power-consuming devices include, but are not limited to, an air conditioning unit, a water heater, a heater, and a circulation fan. Controlling such power-consuming devices involves determining when a control event (i.e., preventing power from flowing to such devices) occurs and for how long.
At times, a LCS is installed with an existing power-consuming device. In such a case, the LCS is installed by electrically coupling different components of the existing power-consuming device to various portions of the LCS. For example, a power source from the power-consuming device is electrically coupled to the LCS. Such work often requires a licensed electrician because the power required by the LCS is at least 110 V alternating current (AC), and so applicable regulations often require a licensed electrician when working with wiring at such voltages. Consequently, the installation of LCSs can be expensive and inconvenient.


A computational efficient algorithm for compression analysis of free-hand static elasticity imaging performed using medical diagnostic ultrasound imaging equipment offers tissue compression quality and quantity feedback to the operator. The algorithm includes a criterion for automatic selection of the most advantageous pre- and post-compression frame pairs delivering elasticity images of optimal dynamic ranges (DR) and signal-to-noise ratios (SNR). The use of the algorithm in real time eases operator training and reduces significantly the amount of artifact in the elasticity images while lowering the computational burden.

1. Field of the Invention
The present invention relates to a computational efficient algorithm for tissue compression analysis for free-hand static elasticity imaging. More specifically, this invention relates to an elasticity imaging system that employs medical diagnostic ultrasound imaging equipment to produce strain images.
2. Description of Related Art
It has been proved that pathological conditions often produce changes in biological tissue stiffness. Tumor tissues, for example, are known to exhibit mechanical properties different from the surrounding tissue, as indicated by the use of palpation as a diagnostic tool. Breast and prostate tumors are especially susceptible to changes in mechanical properties, as indicated in an article by T. A. Krouskop, T. M. Wheeler, F. Kallel, B. S. Garra, and T. Hall, entitled "Elastic moduli of breast and prostate tissues under compression.", Ultrasonic Imaging, 20:260–274, 1998, which is incorporated by reference herein.
Many cancers, such as scirrhous carcinoma of the breast, appear as extremely hard nodules. However, a lesion may or may not possess echogenic properties that would make it detectable with conventional diagnostic ultrasound imaging systems. Tumors of the prostate or the breast may thus be difficult to distinguish with conventional ultrasound techniques, yet may still be much stiffer than the surrounding tissue, as reported in an article by B. S. Garra, I Cespedes, J. Ophir, S. Spratt, R. A. Zuurbier, C. M. Magnant, and M. F. Pennanen, entitled "Elastography of breast lesions; initial clinical results," Radiology, 202:79–86, 1997, which is incorporated by reference herein. As the echogenity and the stiffness of tissue are in general uncorrelated, Garra et al. observe it is expected that imaging the hardness of the biological tissue will provide new information related to the pathological conditions, facilitating the diagnosis process.
The experimentally obtained elastic modulus data in normal and abnormal breast tissues at different frequencies and precompression strain levels was reported in the aforementioned article "Elastic moduli of breast and prostate tissues under compression." The data in the article shows that the differences between the elastic moduli of the various tissues of the breast may be useful in developing methods to distinguish between benign and malignant tumors. Tissues of the prostate were also examined as cancers of the prostate are also significantly stiffer than normal tissue. Similar data indicating differences between the elastic moduli for normal and abnormal prostate tissues were also reported.
The imaging modality that facilitates the display of mechanical properties of biological tissue is called elastography. The purpose of elastography is to display an image of the distribution of a physical parameter related to the mechanical properties of the tissue for clinical applications. In addition to the aforementioned breast and prostate applications of elastography, successful results have been reported for muscle and myocardial applications by F. Kallel, J. Ophir, K. Magee, and T. A. Krouskop, entitled "Elastographic imaging of low-contrast elastic modulus distributions in tissue.", Ultrasound in Med. & Biol, (409–425), 1998; E. E. Konofagou, J. D'Hooge, and J. Ophir, entitled "Myocardial elastography—a feasible study in vivo.", Ultrasound in Med. & Biol. 28(4):475–482, 2002, which is incorporated by reference herein.
Elasticity imaging consists of inducing an external or internal motion to the biological tissue and evaluating the response of the tissue using conventional diagnostic ultrasound imaging and correlation techniques. Depending on the imaging mode and on the nature of tissue motion, elasticity imaging applications are divided into three distinct categories: a) static elasticity (also known as strain-based, or reconstructive) that involves imaging internal motion of biological tissue under static deformation; b) dynamic elasticity (also known as wave-based) that involves imaging shear wave propagation through the tissue; and, c) mechanical elasticity (also known as stress-based and reconstructive) that involves measuring surface stress distribution of the tissue.
Each of the three elasticity imaging applications comprises three main functional components. First, the data are captured during externally or internally applied tissue motion or deformation. Second, the tissue response is evaluated, that is, displacement, strain, and stress are determined. Lastly, the elastic modulus of the tissue is reconstructed using the theory of elasticity. The last step involves implementing the theory of elasticity into modeling and solving the inverse problem from strain and boundary conditions to elastic modulus. As the boundary conditions and the modeling of theory of elasticity are highly dependent on the structure of the biological tissue, the implementation of the last step is rather cumbersome and typically not performed. Moreover, the evaluation and display of tissue strain in the second step is considered to deliver an accurate reproduction of the tissue's mechanical properties.
Static elasticity imaging application is the most frequently used modality. In this application, a small quasi-static compressive force is applied to the tissue using the ultrasound imaging transducer. The force can be applied either using motorized compression fixtures or using freehand scanning. The RF data before and after the compression are recorded to estimate the local axial and lateral motions using correlation methods. The estimated motions along the ultrasound propagation direction represent the axial displacement map of the tissue and are used to determine the axial strain map. The strain map is then displayed as a gray scale or color-coded image and is called an elastogram.
While the majority of the elasticity imaging work has been concentrated so far on off-line processing, proof of concept and method optimization, real-time oriented applications have been only recently reported by Y. Zhu and T. J. Hall, entitled "A modified block matching method for real-time freehand strain imaging.", Ultrasonic Imaging, 24:161–176, 2002, which is incorporated by reference herein; and by T. Shiina, M. Yamakawa, N. Nitta, E. Ueno, T. Matsumura, S. Tamano, and T. Mitake, entitled "Clinical assessment of real-time, freehand elasticity imaging system based on the combined autocorrelation method.", 2003 IEEE Ultrasonics Symposium, pages 664–667, which is incorporated by reference herein. The need for real-time elasticity imaging applications in clinical environment is primarily of a practical nature. However, real-time elasticity imaging is indeed needed to acquire and process the ultrasonic echo data in such a way that patient-scanning time is relatively low and diagnostically relevant elasticity images are produced immediately during the scan. Thus, such real-time elasticity imaging systems are capable of displaying ultrasonic B-mode images and strain images on the same screen in real-time. Such a display also facilitates the assessment of the clinical relevance of the strain images being obtained.
Furthermore, the real-time processing of the ultrasonic echo data allows for freehand compression and scanning of the biological tissue rather than utilizing bulky and slow motorized compression fixtures. Freehand compression, as opposed to motorized compression facilitates a more manageable and user-friendly scanning process and allows for a larger variety of scanning locations. Its disadvantage, however, consists of exhaustive operator training, as the sonographer constantly needs to adjust the compression technique to obtain strain images of good quality. In more detail, to obtain strain images of consistent dynamic range ("DR") and signal-to-noise ratio ("SNR"), the sonographer needs to maintain a constant compression rate while avoiding lateral and out-of-plane tissue motions. Moreover, the compression has to be performed exclusively on the axial direction of the imaging transducer while maintaining a certain speed and repetition period.
In short, due to the extremely complex nature of the tissue compression, obtaining elasticity images of consistent quality using free-hand strain imaging is neither trivial nor as expeditious as obtaining good quality B-mode images, thus real-time compression feedback is necessary to ensure proper operator training.
In an attempt to overcome the limitations discussed above, a few research groups proposed and implemented real-time static elasticity imaging systems as reported by Y. Zhu and T. J. Hall, entitled "A modified block matching method for real-time freehand strain imaging.", Ultrasonic Imaging, 24:161–176, 2002, which is incorporated by reference herein; and, by T. Shiina, M. Yamakawa, N. Nitta, E. Ueno, T. Matsumura, S. Tamano, and T. Mitake, entitled "Clinical assessment of real-time, freehand elasticity imaging system based on the combined autocorrelation method.", 2003 IEEE Ultrasonics Symposium, pages 664–667, which is incorporated by reference herein. In addition, U.S. Pat. No. 6,508,768 B1 to Hall et al. ("'768 patent") describes in detail a real-time static elasticity imaging procedure and implementation. However, those implementations disclosed by the '768 patent and the Zhu et al. and Shiina et al. articles do not account completely for all the limitations mentioned above.
More particularly, neither the articles by Zhu et al. and Shiina et al. nor the teachings of the '768 patent provide a quantitative indication of the compression quality being achieved by the operator. Moreover, the operator does not receive guidance in order to improve the compression quality when s/he is only provided strain images that may contain artifacts and poor SNR. One of several drawbacks being that possible artifacts present in the strain image cannot be qualitatively linked to poor compression quality. Additionally, the current implementations calculate and display strain images continuously, independently of the quality of the compression, or even in the absence of compression. Therefore the computational burden placed upon the imaging system is extremely high while only select sets of strain images faithfully indicate the mechanical properties of the imaged tissue and are artifact-free. Moreover, depending on the applied compression rate, strain images are displayed with variable (and less than optimal) DR and SNR, allowing for artifacts.
There exists a need for a computational efficient algorithm capable of providing real-time tissue compression quality and quantity feedback to the operator. There also exists a need for a computational efficient algorithm that automatically selects the most advantageous pre- and post-compression frame pairs for delivering elasticity images of optimal dynamic ranges and signal-to-noise ratios. There further exists a need for a computational efficient algorithm that generates compression quality feedback independently of the quality of the compression being achieved. There exists still yet a need for a computational efficient algorithm that measures, analyzes and visually displays both the axial and lateral displacements (negative and positive) of the decompression of tissue. There exists further still a need for a computational efficient algorithm that captures and archives all information utilized in generating the elasticity images for off-line analysis.

Method and apparatus for elasticity imaging


A toner process comprising aggregating or coagulating a latex emulsion comprising a resin, a colorant and wax particles using an amount of polymetal ion coagulant to provide core particles; heating the core particles to provide micron size aggregates; optionally adding a second resin emulsion; adding a sequestering or complexing component and a base to remove the polymetal ion in a controlled manner; further heating the mixture to provide toner particles; and optionally, isolating the toner particles.

The present disclosure is generally related to toner processes, and more specifically, to aggregation and coalescence processes for the preparation of toner compositions wherein a complexing or sequestering agent is added during the aggregation process.
Provided are toner processes for the economical chemical in situ preparation of toners without the utilization of the known pulverization and/or classification methods, and wherein in embodiments toner compositions with a volume average diameter of about 1 to about 25 and more specifically about 1 to about 10 microns, and a narrow geometric size distribution (GSD) of, for example, about 1.14 to about 1.25 as measured on the Coulter Counter, can be obtained. The resulting toners can be selected for known electrophotographic imaging, digital, printing processes, including color processes, and lithography.
In reprographic technologies, such as xerographic and ionographic devices, toners with volume average diameter particle sizes of form about 9 microns to about 20 microns are effectively utilized. Moreover, in xerographic technologies, such as the high volume Xerox Corporation 5090 copier duplicator, high resolution characteristics and low image noise are highly desired, and can be attained utilizing the small sized toners as disclosed herein having, for example, a volume average particle diameter of from about 2 to about 11 microns, or less than about 7 microns, and with a narrow geometric size distribution (GSD) of from about 1.14 to about 1.25 or about 1.16 to about 1.20. Additionally, in xerographic systems wherein process color is utilized, such as pictorial color applications, small particle size colored toners, for example from about 3 to about 9 microns, are desired to avoid paper curling. Also, small toner particle sizes can be selected, such as from about 1 to about 7 microns, and with higher colorant loading, such as from about 5 to about 12 percent by weight of toner, such that the mass of toner layers deposited onto the substrate such as paper is reduced to obtain the same quality of image and resulting in a thinner plastic toner layer on paper after fusing, thereby minimizing or avoiding paper curling.
Toners prepared in accordance with the present disclosure provide desired fusing characteristics including, for example, desired release characteristics such as stripping force, for example of less than about 30 grams of force to less than about 5 grams of force, desired blocking characteristics such as for example, a high blocking temperature of about 45° C. to about 65° C., desired document offset characteristics, such as a document offset of about 2.0 to about 5.0 desired vinyl offset characteristics, such as a vinyl offset of about 3.0 to about 5.0 and desired triboelectrical charging characteristics. Further, toners prepared in accordance with the present disclosure enable in embodiments, the use of lower minimum imaging fusing temperatures, such as from about 120° C. to about 170° C., enable high speed printing such as for machines running at greater than about 35 pages per minute. Further, the present toner processes and toners enable high image gloss, such as in an oil-less fuser system while still retaining a high blocking temperature, high image gloss comprising for example from about 30 to about 60 gloss units (GGU) as measured by the Gardner Gloss metering unit, a high image gloss of greater than about 30 GGU, greater than about 40 GGU, or greater than about 50 GGU, for example on a coated paper, such as Xerox 120 gsm Digital Coated Gloss papers.
Numerous processes are known for the preparation of toners, such as, for example, conventional polyester processes wherein a resin is melt kneaded or extruded with a pigment, micronized and pulverized to provide toner particles with a volume average particle diameter of from about 9 microns to about 20 microns and with broad geometric size distribution of from about 1.26 to about 1.5. In these processes, it is usually necessary to subject the aforementioned toners to a classification procedure such that the geometric size distribution of from about 1.2 to about 1.4 is attained. Also, in the aforementioned conventional processes, low toner yields after classifications may be obtained. Generally, during the preparation of toners with average particle size diameters of from about 11 microns to about 15 microns, toner yields range from about 70 percent to about 85 percent after classification. Additionally, during the preparation of smaller sized toners with particle sizes of from abut 7 microns to about 11 microns, lower toner yields can be obtained after classification, such as from about 50 percent to about 70 percent. With the present processes, small average particle sizes of, for example, from about 3 microns to about 9 microns, and more specifically, about 4 to about 6 microns or about 5 microns, are attained without resorting to classification processes, and wherein narrow geometric size distributions are attained, such as from about 1.14 to about 1.30, or from about 1.14 to about 1.25. High toner yields are also attained such as from about 90 percent to about 98 percent. In addition, by the present toner processes, small particle size toners of from about 3 microns to about 7 microns can be economically prepared in high yields such as from about 90 percent to about 98 percent by weight based on the weight of all of the toner ingredients, such as toner resin and colorant.
In U.S. Pat. No. 6,132,924, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner comprising mixing a colorant a latex, and a coagulant, followed by aggregation and coalescence, wherein the coagulant may be a polyaluminum chloride.
In U.S. Pat. No. 6,268,102, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of toner comprising mixing a colorant, a latex, and a coagulant, followed by aggregation and coalescence, wherein the coagulant may be a polyaluminum sulfosilicate.
Illustrated in U.S. Pat. No. 5,994,020, the disclosure of which is totally incorporated herein by reference, are toner preparation processes, and more specifically, a process for the preparation of toner comprising: (i) preparing, or providing a colorant dispersion; (ii) preparing, or providing a functionalized wax dispersion comprised of a functionalized wax contained in a dispersant mixture comprised of a nonionic surfactant, an ionic surfactant, or mixtures thereof; (iii) shearing the resulting mixture of the functionalized wax dispersion (ii) and the colorant dispersion (i) with a latex or emulsion blend comprised of resin contained in a mixture of an anionic surfactant and a nonionic surfactant; (iv) heating the resulting sheared blend of (iii) below about the glass transition temperature (Tg) of the resin particles; (v) optionally adding additional anionic surfactant to the resulting aggregated suspension of (iv) to prevent, or minimize additional particle growth of the resulting electrostatically bound toner size aggregates during coalescence (iv);heating the resulting mixture of (v) above about the Tg of the resin; and optionally, (vii) separating the toner particles.
With respect to the references, only a small part thereof has been selected and this part may or may not be fully representative of the prior art teachings or disclosures.
Emulsion/aggregation/coalescence processes for the preparation of toners are illustrated in a number of Xerox patents, the disclosures of each of which are totally incorporated herein by reference, such as U.S. Pat. No. 5,290,654, U.S. Pat. No. 5,278,020, U.S. Pat. No. 5,308,734, U.S. Pat. No. 5,370,963, U.S. Pat. No. 5,344,738, U.S. Pat. No. 5,403,693, U.S. Pat. No. 5,418,108, U.S. Pat. No. 5,364,729, and U.S. Pat. No. 5,346,797; and also of interest may be U.S. Pat. Nos. 5,348,832; 5,405,728; 5,366,841; 5,496,676; 5,527,658; 5,585,215; 5,650,255; 5,650,256; 5,501,935; 5,723,253; 5,744,520; 5,763,133; 5,766,818; 5,747,215; 5,827,633; 5,853,944; 5,804,349; 5,840,462; 5,869,215; 5,863,698; 5,902,710; 5,910,387; 5,916,725; 5,919,595; 5,925,488; 5,977,210; 5,994,020; 6,020,101; 6,130,021; 6,120,967 and 6,628,102.
In addition, the following U.S. patents relate to emulsion aggregation processes of forming toner compositions, the disclosures of each of which are totally incorporated herein by reference.
U.S. Pat. No. 5,922,501 describes a process for the preparation of toner comprising blending an aqueous colorant dispersion and a latex resin emulsion, and which latex resin is generated from a dimeric acrylic acid, an oligomer acrylic acid, or mixtures thereof and a monomer; heating the resulting mixture at a temperature about equal, or below about the glass transition temperature (Tg) of the latex resin to form aggregates; heating the resulting aggregates at a temperature about equal to, or above about the Tg of the latex resin to effect coalescence and fusing of the aggregates; and optionally isolating the toner product, washing, and drying.
U.S. Pat. No. 5,945,245 describes a surfactant free process for the preparation of toner comprising heating a mixture of an emulsion latex, a colorant, and an organic complexing agent.
U.S. Pat. No. 5,482,812 describes a process for the preparation of toner compositions or toner particles comprising (i) providing an aqueous pigment dispersion comprised of a pigment, an ionic surfactant, and optionally a charge control agent; (ii) providing a wax dispersion comprised of, wax, a dispersant comprised of nonionic surfactant, ionic surfactant or mixtures thereof; (iii) shearing a mixture of the wax dispersion and the pigment dispersion with a latex or emulsion blend comprised of resin, a counterionic surfactant with a charge polarity of opposite sign to that of said ionic surfactant, and a nonionic surfactant; (iv) heating the above sheared blend below about the glass transition temperature (Tg) of the resin to form electrostatically bound toner size aggregates with a narrow particle size distribution; (v) adding additional ionic surfactant to the aggregated suspension of (iv) to ensure that no, or minimal additional particle growth of the electrostatically bound toner size aggregates occurs on further increasing the temperature to coalesce the aggregates into toner particles (vi); (vi) heating the mixture of (v) with bound aggregates above about or at the Tg of the resin; and optionally (vii) separating the toner particles from the aqueous slurry by filtration and thereafter optionally washing.
U.S. Pat. No. 5,622,806 describes a process, for example, for the preparation of toner compositions with controlled particle size comprising (i) preparing a pigment dispersion in water, which dispersion is comprised of a pigment, an ionic surfactant in amounts of from about 0.5 to about 10 percent by weight to water, and an optional charge control agent; (ii) shearing the pigment dispersion with a latex mixture comprised of a counterionic surfactant with a charge polarity of opposite sign to that of the ionic surfactant, a nonionic surfactant, and resin particles, thereby causing a flocculation or heterocoagulation of the formed particles of pigment, resin, and charge control agent; and (iii) stirring.
The appropriate components and process aspects of the each of the foregoing U.S. Patents may be selected for the present disclosure in embodiments thereof


Polymerization of fluoroolefin monomers proceeds in a supercritical carbon dioxide solvent at high monomer loading levels to provide a high molecular weight polymer with low polydispersity and/or a unimodal molecular weight distribution.

1. Field of the Invention
The invention relates generally to fluoropolymers and methods of polymerizing fluoroolefins in a supercritical fluid reaction medium.
2. Description of the Related Art
Polymerized fluoroolefins are conventionally manufactured via emulsion polymerization processes. These processes are conceptually straightforward; however, significant complications are associated with heat and/or mass transfer control in the reactor. From an operational standpoint, the process is very sensitive to heat and mass transfer conditions which, if improperly controlled, can potentially lead to temperature runaway and pressure aborts. Accordingly, the product has a limited range of molecular weight—typically lower than 300,000—with a wide molecular weight distribution that is indicated by a polydispersity index higher than 5. It is further problematic that the reaction product contains a large amount of gel and microgel. Gel formation may necessitate cleaning of the solids, in additional process steps with commensurate reduction of process efficiency. Due to the emulsifying medium, which is typically water, the wet polymer product must proceed through complex finishing processes that include filtration and drying.
The polydispersity index is a measure of the distribution of molecular weights. The polydispersity index is calculated as the weight-average molecular weight divided by the number average molecular weight. As polymer chains approach a uniform chain length, the polydispersity index approaches unity or a value of one. Typical polydispersity indexes vary based on the mechanism of polymerization and can be affected by a variety of reaction conditions. A low polydispersity index indicates a uniform polymer material and a reaction mechanism does not have a tendency to chain-terminate.
To address the foregoing problems with emulsified reaction systems, some efforts have been made to synthesize polymers from their monomeric reactants in supercritical media. Fluids existing at states above critical temperature and pressure are called supercritical fluids. Any fluid may exist and function as a supercritical fluid, provided the temperature and pressure conditions exceed the critical values.
Most of the supercritical polymerization efforts involve polymerization of fluoropolymers and acrylics. For example, U.S. Pat. No. 6,340,722 issued to Lee et al. reports the production of polymethacrylate in supercritical media.
For example, liquid or supercritical CO2 is used in a reaction media with tetrafluoroethylene (TFE) as reported in U.S. Pat. Nos. 5,618,894; 5,674,957; 5,939,501; 5,939,502; and 5,981,673 issued to DeSimone et al. The process conditions exist over a wide range of temperatures and pressures without regard to consequent effects on polymer molecular weight and polymer morphology. While the reactions proceed fairly well for TFE, copolymers of VF2 are typically gummy. Japanese Patents 45,003,390 and 46,015,511 describe polymerization of TFE in CO2 media with use of 60Co γ-rays to initiate polymerization, as opposed to using a chemical-type free radical initiator. The radiation-initiated TFE polymerization reaction may be carried out at temperatures between −70° C. and +80° C.
Other fluoropolymers have been made in CO2 media, for example, as reported in U.S. Pat. No. 5,496,901 issued to DeSimone. A 1,1-dihydroperfluorooctyl acrylate material is polymerized and co-polymerized using aazobisisobutyronitrile (AIBN) as a free radical initiator. In addition, low molecular weight amorphous fluoroolefins are polymerized in the presence of C4F9I and UV light. All polymerizations are carried out in homogeneous solutions comprised of CO2, monomers, and resultant polymer. The process conditions exist over a wide range of temperatures and pressures without regard to consequent effects on polymer molecular weight and polymer morphology.
U.S. Pat. No. 5,496,901 describes polymerization of water-insoluble polymers in aqueous phase in the presence of CO2. Different monomers are polymerized using different initiators in the presence and in the absence of fluoro-surfactant with emphasis on preserving a ratio where TFE:CO2 is 50:50. The monomer is polymerized using K2S2O8. However, polymerization of water-insoluble polymers in aqueous media in the presence of CO2 results in a dispersion of resin in the aqueous media, which circumstance is ultimately similar to the conventional emulsion or suspension polymerization and provides no apparent advantage over the art.
U.S. Pat. No. 5,739,223 issued to DeSimone describes a method of making fluoropolymers using a two-stage reaction process with each stage conducted at a different temperature. The process conditions exist over a wide range of temperatures and pressures without regard to consequent effects on polymer molecular weight and polymer morphology.
U.S. Pat. No. 6,051,682 issued to Debrabander et al. proposes a continuous polymerization system to replace batch polymerization using CO2 as the polymerization media. In the proposed process, polymerization is carried in a continuously stirred tank reactor and the resultant polymer is collected in downstream filters. All examples pertain to TFE/PPVE with no teaching about VF2 polymerization. Moreover, no information is reported or claimed regarding molecular weight or molecular weight distribution of resultant polymers. The process conditions exist over a wide range of temperatures and pressures without regard to consequent effects on polymer molecular weight and polymer morphology.
WO0190206 to DeSimone et al. describes production of fluoropolymers with a multimodal molecular weight distribution. There is no teaching of how to make high molecular weight polymer with a unimodal molecular weight distribution. U.S. Patent Application 2002/0040118 A1 to DeSimone describes similar production of fluoropolymers with a multimodal molecular weight distribution. The polymer has a low average molecular weight typically lower than 200,000, a multimodal molecular weight distribution, and non-controllable morphology. The process utilizes very few initiators, which incidentally do not work particularly well as indicated in part by a monomer conversion of less than 20%.
U.S. Pat. Nos. 5,674,957 and 5,618,894 issued to DeSimone et al. disclose the use perfluorinated free radical initiators, mainly hexafluoropropylene (HFPO) dimer, in making fluoropolymers. Monomer may be dissolved in CFC-113, to produce polymers in CO2 media with stable (fluorinated) chain ends. The polymerization yields and average molecular weights of the resultant polymers are very low, except for the case when TFE is used as a co-monomer. When VF2 is used as co-monomer, a gummy polymer of very low molecular weight is obtained with yields less than 10%.
U.S. Pat. No. 6,103,844 issued to Brothers describes the use of dialkyl(2,2′-azobisisobutyrate) as an initiator in polymerization of TFE and also of VF2 in CO2 media. Other azo compounds, such as 2,2′-azobisisobutyronitrile(AIBN) or 2,2′-azobis(2,2-dimethylpentanitrile) are generally not effective initiators for fluoropolymers. These azo compounds are solids at ambient conditions; however, no information about their states under polymerization conditions is provided.
WO0146275 to Brown et al. describes a process of making oligomers and telomers of fluoromonomers in CO2. The fluoromonomers are principally TFE. The reaction occurs in the presence of a chain transfer agent, such as HBr and/or HCl. The initiator for telomerization is principally HFPO dimer, which is an ineffective initiator for VF2 polymerization.
Some patents describe the synthesis of polyvinylidine difluoride (PVDF) in a supercritical medium, for example, as in U.S. Pat. Nos. 5,496,901; 5,688,879; 5,739,223; 5,863,612; 5,922,833 issued to DeSimone. Analysis of prior processes for VF2 polymerization with use of supercritical CO2 reveals the following problems:                Pressure. Use of very high pressure results from attempts to synthesize polymers above or near the resultant polymer's cloud point in supercritical carbon dioxide. The required pressures are sometimes commercially impracticable, e.g., as in the case of a 45,000 psi process or a 10,000 psi process.        Monomer concentration. VF2 monomer loading is low—typically less than only a few percent of the supercritical fluid medium. With a low monomer loading in supercritical carbon dioxide at excessively high pressures, the chances for interactions of monomer-oligomer, monomer-monomer and monomer-initiator are significantly lowered by the dominating population of carbon dioxide molecules in the system. There is premature termination of free radicals.        Ratio of monomer to solvent. Because of the pressure and monomer concentration issues discussed immediately above, the relative concentration ratio between the fluoromonomer and the solvent is kept low, which in turn affects the product quality as well as the process efficiency, as is also explained above.        Supercritical solvent effects. There is a failure to understand and implement the use of reagents as cosolvents at supercritical reactions conditions, especially to investigate the possible effects of CO2 and VF2 as cosolvents to solubilize polymer reaction product and initiator when VF2 is a reagent. Therefore, the processes are operated more strictly as a precipitation polymerization from the beginning to the end of the reaction.        Initiator choices. There is a very narrow selection among initiator choices, and the initiators do not work particularly well. There is initiator involvement in reaction mechanism with consequent chain branching and chain termination effects leading to less desirable products. Selections do not include use of free radical initiators that are more common and less expensive. The choice of initiator is not based on reaction kinetics or mechanisms.        Polymer weight. Low molecular weight polymers result from these processes. The average molecular weight of product polymer is substantially lower than that of the conventional emulsion polymerization process.        Use of a stabilizer chemical or a fluoro-surfactant. These materials are unable to sustain continuing chain growth in CO2—VF2 systems. There may be formation of undesirable foam. The art commonly uses stabilizers and/or fluoro-surfactants for polymer chain growth as well as for product particle morphology.        Gummy product. There is formation of gels and microgels, such that the reactions do not directly result in gel-free free-flowing powder and additional process steps are required to harvest clean solids. The existence of gel or microgel is an indirect proof of the negative effect of melt processing or solution processing of product polymer. Further, it also provides an indirect proof for entrapment of inhomogeneous species inside the polymeric matrix/phase, e.g., solvent initiator, its fragmented derivatives, unreacted monomer, and interpenetrating network of oligomers and low weight fluoropolymers. Therefore, the product is impure and inferior not only from the material property standpoint, but also from the further processing aspect.        Product morphology controls. The references do not describe a control strategy to benefit product morphology.        Molecular weight controls. Besides the low molecular weight polymers, there is poor control over polymer molecular weight distribution. The processes are not selectively controllable to produce polymer with a desired molecular weight.        Inferior polydisperse product. The molecular weight distribution is multimodal, proving that the degree of polymerization is never under control. The resultant product is, therefore, significantly inferior.        Inability to achieve high molecular weight polymer. The references do not describe how to make polymer with high or medium molecular weight. The molecular weights, even in the best possible cases, are substantially lower than those of the conventional emulsion polymerization products. Thus, the polymer products are inferior to hose produced by emulsion processes.        Low process yields. The polymerization yield is low and the monomer conversion is also low, thus making the process operate in a high recycle mode and worsening the process economics.

Polymerization of vinylidene fluoride (VF


The present invention relates to An N-acetylglucosamine derivative represented by the following formula (1), and a hyaluronic acid production promoting agent containing the same and a skin external preparation containing the same:

Hyaluronic acid is a high molecular weight polysaccharide having a high water retention capability and has drawn attention as a very important extracellular matrix component in the skin (Shingo SAKAI, Shintaro INOUE, Metabolism of Hyaluronic Acid and Wrinkle Formation, Fragrance Journal, Fragrance Journal Ltd., vol. 26, no. 4, 49-58, Apr. 15, 1998).
Further, hyaluronic acid has been known to have many functions such as maintaining cells, retaining smoothness and suppleness of the skin, rendering the skin resistant to external force such as mechanical force and preventing the infection with pathogenic bacteria (BIO INDUSTRY, CMC Co., Ltd, vol. 8 no. 5, 66(346)-68(346), May 1, 1991).
On the other hand, it is reported that the intensity of the hyaluronic acid staining observed in the intercellular part of the epidermis decreases with aging (Ludger J. M. Meyer and Robert Stern, Age-Dependent Changes of Hyaluronan in Human Skin, The Journal of Investigative Dermatology, The society for Investigative Dermatology, Inc, Vol. 102, No. 4, pp. 385-389, April 1994), and that hyaluronic acid is hardly detected in the part affected by solar elastosis caused by ultraviolet radiation (Takuo TSUJI, Physiological Aging of Skin: Difference from Photo-aging, Clinical Dermatology, Igaku-Shoin Ltd., Special Edition, vol. 51, no. 5, 53-57, Apr. 15, 1997) and accordingly it is considered that the drying and the deterioration of the vital properties and the elasticity of the skin are caused and consequently wrinkles are increased. For the improvement of such conditions, cosmetics containing hyaluronic acid has been applied to keep the moisture retention capability of the skin surface; however, hyaluronic acid, which is a high molecular weight molecule, is hard to penetrate into the skin, and thus, the fundamental improvement cannot be expected. Accordingly, it is highly expected to develop a substance which can fundamentally improve the skin function by increasing the hyaluronic acid synthesizing capability of the cells by themselves.
Retinoic acid has been known as a hyaluronic acid production-promoting substance in the epidermis. Retinoic acid originally exists in the epidermis and is a substance involved in the proliferation and the differentiation of the epidermal cells. However, retinoic acid has the skin irritation properties. From this point of view, it is desired to find a hyaluronic acid production-promoting substance with which such problems can be avoided.
On the other hand, it has been reported that N-acetylglucosamine, which is a saccharide constituting hyaluronic acid, can promote hyaluronic acid production in the cultured epidermal cells about 1.5-times at a concentration of 5 mmol/L independently from the cell proliferation (Fine Chemical, CMC Co., Ltd., vol. 30, no. 22, 5-11, Dec. 15, 2001). However, a high concentration of N-acetylglucosamine is required to exert the hyaluronic acid production-promoting effect and accordingly, it is desired to develop a material which has an sufficient effect even at lower concentrations in order to apply in the broader fields such as the field of cosmetics and pharmaceuticals.

N-acetylglucosamine derivatives and use thereof

Abstract: wherein R1 is a hydrogen atom or an alkyl group having 2 to 18 carbon atoms; R2, R3, and R4 are hydrogen atoms or acyl groups having 2 to 18 carbon atoms and may be all the same or different from others; the steric structure at position 1 may be α or β; provided that R1, R2, R3, and R4 must not be all hydrogen atoms.

Abstract: It is intended to provide an easily available hyaluronic acid production promoting agent and a skin external preparation whereby the production of hyaluronic acid can be promoted in the skin and thus the skin can be maintained in a vital and moist state so that it is expected that the human skin can be prevented from age.


A Hall effect thruster including a downstream end of its annular channel presenting a cross-section that is variable to vary a thrust and a specific impulse of the thruster.

The present invention relates to the field of Hall effect thrusters.
The invention relates more particularly to a Hall effect thruster having an annular channel, an anode, an injection circuit, a magnetic circuit, and a cathode. The annular channel is defined by an outer wall and an inner wall that are coaxial around a central axis, and it presents a downstream end that is open and an upstream end that is closed. The anode is situated at the upstream end of the annular channel. The injection circuit is suitable for injecting a propulsion gas, e.g. xenon, into the annular channel. The magnetic circuit is suitable for generating a magnetic field at the downstream end of the annular channel. The cathode is situated at the outside of the downstream end of the annular channel.
In the present context, the terms "upstream" and "downstream" are defined relative to the normal flow direction of the propulsion gas in the direction defined by the central axis of the annular channel.
Typically, in the operation of such a Hall effect thruster, electrons are emitted by the cathode and attracted towards the anode at the end of the annular channel, which electrons are trapped by the magnetic field in spiral trajectories between the two walls, thereby forming a virtual cathode grid. Electrons escaping towards the anode from this magnetic enclosure enter into collision with atoms of the propulsion gas that is injected into the annular channel by the injection circuit, thereby creating an ionized plasma.
The positive ions of the plasma are accelerated by the electric field that exists between the anode and the virtual cathode grid formed by the cloud of electrons trapped by the magnetic field at the open end of the annular channel. Since the mass of each positive ion is much greater than the mass of an electron, the trajectory of the positive ions is hardly affected by the magnetic field. The ions of this plasma jet are finally neutralized downstream from the magnetic field by electrons emitted by the cathode or that have been produced by ionizing the plasma.
Hall effect thrusters were initially used in attitude and orbit control systems (AOCSs) for space vehicles, and in particular for the AOCSs of geostationary satellites. Hall effect thrusters enable a specific impulse (Isp) to be obtained that is very high, being of the order of 1500 seconds (s), thus enabling the attitude and/or the position of the vehicle to be controlled very accurately with mass and complexity that are significantly smaller than when using conventional systems relying on inertial devices such as reaction wheels, for example, in combination with chemical thrusters for desaturating them.
Nevertheless, a Hall effect thruster with high specific impulse can normally only achieve thrust that is very low. Consequently, AOCSs incorporating Hall effect thrusters are conventionally associated with chemical thrusters for performing certain fast maneuvers, such as positioning or orbit transfer. That nevertheless presents the drawback of increasing the overall cost and complexity of the space vehicle, to the detriment of its reliability.
When performing characterization tests, and also in the SMART-1 experiment, it has been established that Hall effect thrusters can operate not only in a high specific impulse mode using the propulsion gas at a low flow rate and using a high electric voltage between the anode and the cathode, but that they can also be used, alternatively, in a high thrust mode, with a flow rate that is large and an electric voltage that is moderate. Nevertheless, the stability of the plasma jet and the efficiency of the thruster depend, amongst other things, on the density of the plasma in the annular channel. Consequently, present thrusters are optimized for a single mode of operation. Thus, replacing chemical thrusters for positioning and for orbit transfer would normally require Hall effect thrusters that are designed to operate in a high thrust mode, in addition to Hall effect thrusters of high specific impulse in the AOCS. The complexity of the space vehicle would thus not be reduced significantly.
In U.S. Pat. No. 7,500,350 B1, a Hall effect thruster is disclosed that has an annular channel presenting a downstream end that is open and an upstream end that is closed, an electric circuit, an injection circuit for injecting a flow of propulsion gas into the annular channel, and a magnetic circuit for generating a magnetic field at the downstream end of the annular channel. The electric circuit comprises an anode situated at the upstream end of the annular channel, a cathode downstream from the downstream end of the annular channel, and an electric voltage source between said anode and said cathode. The annular channel is defined by an inner wall and an outer wall that are coaxial around a central axis. In order to maintain a gap that is approximately constant between the inner and outer walls in spite of them being gradually eroded away during the operation of the thruster, the inner wall and/or the outer wall are movable in the axial direction, and the thruster also has an actuator for moving said inner wall and/or said outer wall. Nevertheless, that document does not mention how to operate the Hall effect thruster both in high thrust mode and in high specific impulse mode.


An SRAM array with a dummy cell row structure in which the SRAM array is divided into segments isolated by a row pattern of dummy cells. The dummy cell structure provides a continuous cell array at the lower cell patterning levels. The SRAM array includes a first and second array block each including an SRAM cell having a first layout configuration, one or more of the dummy cells having a second layout configuration arranged along the row pattern associated with a wordline of the SRAM array, a first power supply voltage line connected to the first array block, and a second different power supply voltage line connected to the second array block. The first and second power supply voltage lines of the array blocks are further connected to the one or more dummy cells.

Current trends in the semiconductor and electronics industry require memory devices to be made smaller, faster and require less power consumption. One reason for these trends is that more personal devices are being manufactured that are relatively small and portable, thereby relying on battery power. In addition to being smaller and more portable, personal devices are also requiring increased memory and more computational power and speed. In light of all these trends, there is an ever increasing demand in the industry for smaller, faster, and lower power dissipation memory cells and transistors used to provide the core functionality of these memory devices.
Semiconductor memories can, for example, be characterized as volatile random access memories (RAMs) or nonvolatile read only memories (ROMs), where RAMs can either be static (SRAM) or dynamic (DRAM) differing mainly in the manner by which they store a state of a bit. In SRAM, for example, each memory cell includes transistor-based circuitry that implements a bistable latch, which relies on transistor gain and positive (e.g., reinforcing) feedback so that it can only assume one of two possible states, namely on (state 1) or off (state 2). The latch can only be programmed or induced to change from one state to the other through the application of a voltage or other external stimuli. This arrangement is desirable for a memory cell since a state written to the cell will be retained until the cell is reprogrammed.
DRAMs on the other hand implement a capacitor that is either charged or discharged to store the on (state 1) or off (state 2) state of a cell. Capacitors discharge over time, however, and DRAMs must therefore be periodically 'refreshed'. Also, a bistable latch can generally be switched between states much faster than the amount of time it takes to charge or discharge a capacitor. Accordingly, SRAMs are a desirable type of memory for certain types of applications.
SRAM is typically arranged as a matrix of memory cells fabricated in an integrated circuit chip, and address decoding in the chip allows access to each cell for read/write functions. SRAM memory cells use active feedback from cross-coupled inverters in the form of a latch to store or "latch" a bit of information. These SRAM memory cells are often arranged in rows so that blocks of data such as words or bytes can be written or read simultaneously. Standard SRAM memory cells have many variations.
The basic CMOS SRAM cell generally includes two n-type (nMOS) pull-down or drive transistors and two p-type (pMOS) load transistors in a cross-coupled inverter configuration, with two additional nMOS select or pass-gate transistors added to make up a six-transistor cell (a 6T cell). Additionally, application specific SRAM cells can include an even greater number of transistors. A plurality of transistors are utilized in SRAM requiring matched electrical characteristics to provide predictable cell switching characteristics, reliable circuit performance, and minimize array power dissipation. As transistor feature sizes are continually reduced, however, achieving good, consistent cell patterning that maintains this transistor matching to avoid increased power dissipation is becoming more difficult in SRAM, despite the use of optical pattern correction (OPC) in the photolithographic process.
In operation of SRAM memory arrays, power is generally dissipated in the entire array and peripheral drive/access circuitry even as the array stands idle. This is because in the highest density arrays, power supply lines are shared row to row in common to keep real estate to a minimum. Power dissipation may be reduced while retaining data, by lowering the voltage (e.g., Vss, Vdd) to the array, such as in a data retention mode or sleep mode. In normal operations of the cells, however, a higher voltage is usually again applied to the array, and the cells are accessed via a wordline one row at a time.
Accordingly, for minimum static power dissipation in an SRAM device, it would be desirable to apply full voltage to only the row(s) being accessed, with all other rows of the array in the lower voltage data retention mode. However, the switching between the rows of such an array configuration would add latency and dynamic power. In a prior art, for example, the control of the supply voltage is provided along with the wordline access of a row, keeping the other rows of the array at the lower dissipation voltage. Another problem with this solution is that a significant amount of additional power distribution switching circuitry and wafer real estate must be provided to isolate the power lines between each row of the entire array.
An attractive compromise may be to segment the memory array into relatively small groups of rows wherein the voltage to a group is raised for access and lowered for retention. However, segmenting an array into these relatively small groups of rows may result in inconsistent patterning of the edge rows relative to rows central to the array, and may require significantly more peripheral decoder circuitry and the associated additional area penalty.
Accordingly, there is a need for an area efficient means of isolating power between relatively small groups of rows of an SRAM array while maintaining good pattern uniformity of the cells row to row, equivalent device performance, and minimal power dissipation in the fabrication of SRAM memory devices.

Area efficient implementation of small blocks in an SRAM array