The present invention relates to a peach tree, Prunus persica, and more particularly to a new and distinct variety characterized by a medium size, vigorous, hardy, self-fertile, productive and regular bearing tree. The fruit matures under the ecological conditions described in the latter part of June, with first picking on Jun. 22, 2005. The fruit is uniformly large in size, sub-acid and sweet in flavor, globose in shape, freestone in type, firm in texture, yellow with only minor red streaking in flesh color, and mostly red in skin color.

In a continuing effort to improve the quality of shipping fruits, I, the inventor, typically hybridize a large number of peach, nectarine, plum, apricot, and cherry seedlings each year. The present invention relates to a new and distinct variety of peach tree, which has been denominated varietally as 'Diamond Candy'. The present variety was hybridized by me in 1996, grown as a seedling on its own root in my greenhouse, and transplanted to a cultivated area of my experimental orchard near Le Grand, Calif., in Merced County (San Joaquin Valley).
The variety was developed as a first generation cross using 'Diamond Ray' (U.S. Plant Pat. No. 8,948) yellow flesh nectarine as the selected seed parent and an unnamed peach (unpatented) as the selected pollen parent. A single tree from the stated cross was selected as the claimed variety. Subsequent to origination of the present variety of nectarine tree, I asexually reproduced it by budding and grafting in the experimental orchard described above, and such reproduction of plant and fruit characteristics were true to the original plant in all respects. The reproduction of the variety included the use of 'Nemaguard' (unpatented) rootstock upon which the present variety was compatible and true to type.
The present variety is similar to its selected seed parent, 'Diamond Ray' (U.S. Plant Pat. No. 8,948) nectarine, by producing fruit that is globose in shape, firm in texture, full red in skin color, yellow in flesh color, and that ripens in the latter part of June, but is very distinguished therefrom by producing fruit that is freestone instead of clingstone, that is sub-acid instead of acid in flavor, and that is peach instead of nectarine in type.
The present variety is similar to 'Spring Candy' (U.S. Plant Pat. No. 14,677) peach by producing freestone peaches that are yellow in flesh color, sub-acid in flavor, globose in shape, and firm in texture, but is distinguished therefrom by producing peaches that have much less red bleeding around the stone and that mature eight days later, extending the season for this type of fruit. It is to be noted that in 2005 fruit matured earlier in the season than most years, with 'Spring Candy' beginning harvest on Jun. 14, 2005.


A nonvolatile memory device including a memory cell; a word line coupled to the memory cell; a drive line; a switch coupled between the word line and the drive line, and configured to electrically connect the word line and the drive line; and a voltage generator coupled to the drive line and configured to charge the drive line to a precharge voltage. The precharge voltage is higher than a bias voltage applied to the word line during a corresponding operation on the memory cell.

This disclosure relates to semiconductor devices and, more particularly, to nonvolatile memory devices and methods of driving word lines.
A nonvolatile memory device can include floating gate transistors as memory cells. A variety of voltages are applied to the gates of the floating gate transistors during operation of the memory device. The time taken applying these voltages to the gates of the floating gate transistors can affect the time of an operation of the memory device.

Non-volatile memory device, computing system and wordline driving method


A rotary throttle member for an internal combustion engine comprises a shaft and a butterfly valve member secured to a central length of the shaft. The shaft and butterfly valve member are single pieces of synthetic material. End portions of the shaft straddle the said central length. The central length has a uniform non-circular cross-section greater than that of the full end portion of the shaft situated on one side of the length. The shaft includes a cam for connection with and winding of a control cable, situated on the other end portion of the shaft. The butterfly valve member has a central hole of complementary cross-section of said central length and is fixed onto the central length.

The present invention relates to a rotary throttle member for a fuel admission system of an internal combustion engine, the throttle member being of the type comprising a shaft having cylindrical bearing surfaces straddling a section for receiving a butterfly valve member. An application that is particularly important, but not exclusive, lies in throttle body assemblies for fuel injection systems.
Conventionally, a rotary throttle member for an admission system consists of a shaft and a butterfly in the form of a flat disk, both being made of metal. The butterfly is held in a slot or on a flat of the shaft by means of screws. The manufacture of such a member by machining and assembling is expensive.
In addition, experience has shown that under unfavorable atmospheric conditions frost is prone to attach to the metal parts and in particular to the connection zones between the butterfly and the shaft.

Rotary throttle member and a throttle body for an internal combustion engine


An electrostatic ink jet record head of the present invention includes an ink chamber storing ink consisting of a carrier liquid and charged toner particles dispersed therein. An ejection port communicates the ink chamber to the outside of the head. An ejection electrode is disposed in the ejection port and electrically insulated from the ink. An electrophoresis electrode is positioned at the opposite side to the ejection electrode with respect to the ink chamber and electrically insulated from the ink. A control electrode is provided between the electrophoresis electrode and the ejection electrode and contacts the ink. Also, an electrostatic ink jet recorder of the present invention has, in addition to the head, a counter electrode facing the ejection port with the intermediary of a recording medium, and voltage controller for applying a particular preselected voltage to each of the discharge electrode, electrophoresis electrode, and control electrode. The voltage applied to the electrophoresis electrode is higher than a threshold voltage causing the toner particles to fly by themselves, while the voltage applied to the control electrode is lower than the threshold voltage.

The present invention relates to an electrostatic ink jet record head and an ink jet recorder using the same. More particularly, the present invention is concerned with an electrostatic ink jet record head of the type using ink consisting of a carrier liquid and toner particles dispersed therein, and causing only the toner particles to fly electrostatically so as to print an image on a recording medium, and an ink jet recorder using the same.
Nonimpact recording methods are attracting increasing attention because they produce only a negligible degree of noise ascribable to operation. Particularly, an ink jet recorder which is a specific form of a nonimpact recorder has a simple construction and high-speed recording capability and is operable with plain papers. The ink jet recorder with such advantages has been proposed in various forms in the past. One of conventional ink jet recorders uses ink consisting of a carrier liquid and toner particles dispersed therein. In this type of recorder, a voltage is applied to between a needle-like ejection electrode and a counter electrode facing it with the intermediary of a paper. The resulting electric field causes the toner particles of the ink to fly with an electrostatic force and form a dot on a paper or similar recording medium.
Specifically, the above ink jet recorder has an ejection port in the form of a gap small enough to form an ink meniscus. An ejection electrode is positioned in the ejection port and slightly protrudes to the outside from the end of the port. An electrophoresis electrode surrounds an ink chamber. A counter electrode is connected to ground and positioned on the imaginary extension of the ejection electrode. A paper intervenes between the ejection electrode and the counter electrode. Therefore, in the event of recording, an electric field is formed between the two electrodes. The electric field concentrates on the sharp tip of the ejection electrode and extends toward the paper with high intensity. To effect high-speed recording with the above recorder, it is necessary to replenish the toner particles at a high speed, i.e., to increase the speed of electrophoresis of the toner particles. To increase the speed of electrophoresis speed, it is necessary to apply a great potential difference between the ejection electrode and the electrophoresis electrode. However, because the electrophoresis electrode remains in electrical contact with the ink, even the ink around the ejection electrode has the same potential as the electrophoresis electrode in an equilibrium condition. Therefore, if the high voltage is applied to the electrophoresis electrode excessively, then the potential of the ink around the ejection electrode becomes high enough for the toner particles to fly. As a result, the toner particles fly by themselves even when no drive pulses are applied to the ejection electrode.
To better understand the present invention, a brief reference will be made to a conventional electrostatic ink jet recorder, shown in FIGS. 1-3. Briefly, the recorder uses ink consisting of a carrier liquid and toner particles dispersed therein, and includes a needle-like ejection electrode and counter electrode facing it with the intermediary of a paper or similar recording medium. A voltage is applied to between the ejection electrode and the counter electrode so as to generate an electric field. The toner particles of the ink are caused to fly by the electrostatic force of the electric field forming an image on the paper.
As shown, a head 50 has an ink chamber 52 delimited by a lower plate 63, a side wall 64, and an upper plate 65. A pump, not shown, constantly circulates ink 51 in the chamber 52 via circulation ports 59 and 60. The ink 51 has the above-mentioned composition. An ejection port 54 is formed in a part of the side wall 64 and has a gap small enough to form an ink meniscus Me. An ejection electrode 55 is positioned in the ejection port 54 and slightly protrudes to the outside from the end of the port 54. The surface of the electrode 55 is coated with an insulator to be insulated from the ink 51 thereby. An electrophoresis electrode 58 delimits the other three sides of the ink chamber 52 where the ejection port 54 is absent. The electrode 58 is partly positioned in the chamber 52 and held in contact with the ink 51.
The ejection electrode 55 is connected to a driver, not shown. In the event of recording, a high-voltage pulse of the same polarity as the toner particles is applied to the electrode 55. A high voltage of the same polarity as the toner particles is continuously applied to the electrophoresis electrode 58 from a voltage controller 62. A counter electrode 61 is connected to ground and positioned on the imaginary extension of the electrode 55. A paper P intervenes between the electrodes 55 and 61. Therefore, in the event of recording, an electric field is formed between the electrodes 55 and 61. Because the electrode 55 has a sharp tip, the electric field concentrates on the tip of the electrode 55 and extends toward the paper P with high intensity. The toner particles dispersed in the ink 51 have been charged by zeta potential beforehand, so that they are pulled toward the paper P by a Coulomb's force derived from the above electric field. When the Coulomb's force overcomes the surface potential of the ink 51, the toner particles are caused to fly toward the counter electrode 61 in the form of a drop 53. The drop 53 deposits on the paper P and forms a dot thereon. In this type of recorder, the high-voltage pulse to be applied to the ejection electrode 55 is controllable in accordance with an image to be printed on the paper P.
Just after the flight of the toner particles, i.e. drop 53, the toner content of the ink 51 becomes low in the vicinity of the ejection electrode 55 because only the toner particles are mainly consumed. However, the high-potential continuously applied to the electrophoresis electrode 58 causes the toner particles in the ink 52 to electrophoretically migrate toward the electrode 55 away from the electrode 58. Consequently, only the toner particles are replenished to a portion around the electrode 55. Particularly, because the electrode 55 is electrically insulated from the ink 51, the migration of the charged toner particles toward the electrode 55 ends as soon as the potential distribution in the chamber 52 reaches equilibrium. Therefore, the recordable frequency of the head 50 is determined by the period of time necessary for the toner particles to migrate.
To effect high-speed recording with the above recorder, it is necessary to replenish the toner particles at a high speed, I.e., to increase the speed of electrophoresis of the toner particles. Assume that the amount of charge deposited on the toner particles is q, that the electric field is E, that the ink has a viscosity of .eta., and that the toner particles have a diameter of r. Then, an electrophoresis speed .nu. is expressed as: EQU .nu.=qE/6.pi..eta.r
Because the above factors q, .eta. and r are fixed values particular to the ink, E must be increased in order to increase the electrophoresis speed .nu.. That is, it is necessary to apply a great potential difference between the discharge electrode 55 and the electrophoresis electrode 58. However, because the electrode 58 remains in contact with the ink 51, even the ink 51 around the electrode 55 has the same potential as the electrode 58 in the above equilibrium condition. Therefore, if the high voltage is applied to the electrode 58 excessively, then the potential of the ink 51 around the electrode 55 becomes high enough for the toner particles to fly. As a result, the toner particles fly by themselves even when no drive pulses are applied to the electrode 55.

Electrostatic ink jet record head having a control electrode for equalizing the electric field of an ink chamber an ink jet recorder using same


A pneumatic control valve system has a modulating valve and a piston. When the operator depresses the piston, pressure is communicated to a switching piston moving that piston to a switched position so that pressure is communicated to a switching outlet. The switching piston retains this switched position when the first piston is released. When the modulating valve is opened to communicate pressure to a work port, pressure is also communicated to the switching piston in order to move the switching piston back to its unswitched position whereat the switching outlet is vented. The switching piston allows the control of another function.

1. Field of the Invention
This invention relates to a pneumatic control valve system.
2. Description of the Related Art
A pneumatic control valve system for the control of a hydraulic system, such as a dump truck hoist, is known. For control of a dump truck hoist, one pneumatic valve typically controls the raising of the dump body and a second pneumatic valve controls the lowering of the body. Typically, a lever associated with the valves and may be pivoted in one direction to depress one of the pneumatic valves and in an opposite direction to depress the other pneumatic valve. In controlling a hydraulic system, the pneumatic control valve system must typically provide a further function. For example, with a dump truck hoist, it is necessary to engage the power take-off (referred to as the "PTO") in order to raise the hoist. As is well understood by those skilled in the art, the PTO is a gear in the transmission which must be engaged to run the hydraulic oil pump. In known pneumatic control valve systems, a separate lever or switch is typically employed to engage the PTO. However, the operator must remember to disengage the PTO prior to driving off as, otherwise, the oil pump will be driven at destructive high speeds.
This invention seeks to overcome drawbacks in the known prior art.


A temperature sensing system for a flange mounted device is provided. The temperature sensing system (100) can be comprised of a flexible wiring board (102). The temperature sensing system can be further comprised of a temperature sensing device (122) mounted to the flexible wiring board. The flexible wiring board can have one or more conductive traces (114a, 114b, 114c) disposed thereon. The conductive traces can form an electrical connection with the temperature sensing device. The temperature sensing system can also comprise a thermal pad directly connected to the temperature sensing device. The thermal pad can be formed of a thermal conductor. The thermal pad can also have a thermal contact surface. The thermal contact surface can be sized and shaped for direct physical contact with a portion of the device (302), wherein thermal energy is communicated directly from the thermal pad to the temperature sensing device. A method for sensing a temperature of a flange mounted device is also provided.

1. Statement of the Technical Field
The invention concerns sensor equipment, specifically, flexible circuits wherein the flexible circuit serves as a substrate for a contact temperature sensor.
2. Description of the Related Art
Temperature sensing devices are well known in the art. For example, thermocouples and thermistors have been used for many years to perform temperature sensing functions. Notwithstanding their widespread use, thermocouples and thermistors are known to suffer from certain limitations. For example, thermocouples are non-linear devices that have a low sensitivity to small temperature changes and are relatively inaccurate. Errors of less than ±1.0° C. are difficult to achieve. A thermocouple's life span depends on the operating temperature, the operating environment, the thermocouple wire size, and the thermocouple insulation type. A thermocouple's accuracy also decreases as a function of time. For example, the heating and cooling of thermocouple wires causes physical and chemical changes to the wires, such as metallurgical structure changes and reactions with oxygen. As a result, the thermocouple's accuracy range becomes more inefficient over time. Thermistors tend to be more accurate than thermocouples, but they have a much more limited temperature range because of their marked non-linearity.
In recent years, various manufacturers have developed integrated circuit temperature sensing devices. Such devices offer a number of advantages as compared to temperature sensing systems that are based on conventional thermocouple or thermistor technology. For example, integrated circuit temperature sensors can be designed to produce either voltage or current output. The also produce a very linear output that can simplify system design.
Notwithstanding the advantages of integrated circuit temperature sensors, they can also create some practical design problems. For example, such design problems can occur when a sensing device is used to measure a case surface temperature of an electronic device, such as a flange mounted transistor.
Temperature sensors can come in various packages useful for mounting the sensor device to a printed circuit board (PCB) or a printed wiring board (PWB). PCBs and PWBs are rigid insulated boards on which interconnected circuits and components are mounted. However, such sensor architectures often do not provide suitable mechanisms for transporting thermal energy to the sensor from the heat source in order to take an accurate temperature measurement. Some types of sensors, such as thermocouples are offered in a bolt on configuration that is well suited for attachment to certain electronic devices, such as a flange mounted transistor. Such configurations can offer good thermal performance, but still suffer from all of the various disadvantages commonly associated with thermocouple devices.
Alternative solutions to the temperature sensing problem include arrangements that attach a thermal conductor to the device which is to be measured. The thermal conductor can be connected to one or more other thermally conductive elements, which are ultimately connected to the temperature sensing device. The thermally conductive elements can be used to transport heat energy from the device undergoing measurement, to the temperature sensing device. While such arrangements have been used in the past, they also have some disadvantages.
For example, such arrangements typically comprise a large number of parts. These parts can include one or more metal studs or plates, and electrical wiring for powering the sensor and communicating measured data. If a board mounted integrated circuit temperature measuring device is used, then an auxiliary printed wiring board can also be required to accommodate the integrated circuit package and pin-outs. Due to the large number of components and associated assembly labor, this sensor architecture is very costly to manufacture. In addition, thermal performance in these arrangements can be compromised because of the rather long thermal conduction path. This can lead to inaccurate or delayed sensing of temperature variations occurring on the device to be measured.
Despite the various configurations known in the art there remains a need for a more accurate, real time temperature sensing system having an improved mechanical connection between a sensor and a heat source. A flexible, miniaturized temperature sensing system is also needed that is cost efficient by minimizing assembly labor and part count.

Flexible circuit temperature sensor assembly for flanged mounted electronic devices


The present invention is directed to a vacuum including a dust extraction system. The system includes a filter assembly, an airflow generation assembly, and valve assembly. The airflow generation assembly is configured to draw contaminated air toward the filter assembly and exhaust filtered air as a discharge stream. The filter assembly is configured to remove contaminants from the contaminated airflow by capturing particulate material suspended within the airflow. The valve assembly is configured to selectively direct filtered airflow into the filter assembly such that the filtered air stream cleans the filter.

Tool shop vacuum cleaners (e.g., wet-dry vacuums) are designed to collect debris from a work area or connected tool via suction. Such vacuums typically include a tank and motor that drives an impeller to generate an airstream within the tank. Since the airstream includes debris, care must be taken to prevent the debris from reaching the motor and causing damage. In light of this, conventional systems further include a filter positioned upstream from the motor to capture debris as the contaminated airflow passes through the tank. Over time, however, the debris accumulates on the filter, restricting airflow and hampering performance. For example, a filter initially enabling airflow of approximately 80 cfm may begin degrading within minutes of operation, diminishing airflow capacity to approximately 10 cfm. Consequently, conventional vacuum systems require regular cleaning or replacement of the filter. This process requires a user to stop vacuum operation, open the tank, and remove the filter for cleaning or replacement. This is a time-intensive process that interrupts workflow.
Thus, it would be desirable to provide an airflow arrangement configured to clean a filter during operation, thereby increasing filter life and extending time between manual cleaning of the filter, as well as filter replacement.


An animal carrier device used in conjunction with a vehicle occupant restraint and a vehicle seat. The device includes a base member having a bottom and a wall extending from the bottom. The wall includes a projection which extends further out than other portions of the wall from the base. The base also forms an open chamber. An enclosure fits into the open chamber and connects to the same through one or more latches, a flange is linked to the projection of the wall of the base member and interacts with the vehicle occupant restraint to confine the base member and the latch enclosure to the vehicle seat.

Animals must often be transported from place to place in vehicles. To prevent an animal from moving about and distracting the driver and occupants of the vehicle, cages have been developed that are hand carried to hold the animal during a vehicle trip or journey.
In the past, like apparatuses and systems have been proposed to transport animals in a vehicle. For example, U.S. Pat. Nos. 5,615,640, 6,539,895, US Patent Publication US2008/0245313, and U.S. Design Pat. No. 346,676 show pet and animal transportation carriers which are portable in that they are hand held and may be moved manually.
U.S. Pat. Nos. 6,155,206 and 7,036,458 describe animal travel carriers which include an enclosure and wheels that extend from the same to allow the carrier to roll on a surface.
U.S. Pat. No. 7,392,764 shows an animal restraint and carrier that is portable and includes an insert to carry medical supplies and other storage items.
United States Publication number US 2005/0284399 illustrates an animal enclosure which may be suspended to an upright arm with a cover that is movable between a stored position and a deployed position.
U.S. Pat. No. 4,943,105, US Patent Publication 2008/0245311, and PCT Application WO 89/08386 teach pet enclosures which are generally opened at the top and may be fitted on to a vehicle seat.
U.S. Pat. Nos. 5,810,227, 6,250,529, and 7,152,554 show animal carriers which may be affixed to the exterior of vehicles, including two-wheeled vehicles.
U.S. Pat. Nos. 4,803,951, 5,941,195, 6,223,691, and US Publication Number US 2006/0278173 describe enclosure for pets that may be placed on a vehicle seat and affixed to portions of the vehicle using a vehicle seatbelt.
An animal carrier which includes a portable enclosure and a protective base portion relative to a vehicle seat would be a notable advance in the art of animal husbandry.


There is provided a silicon carbide semiconductor device allowing for increased switching speed with a simpler configuration. A silicon carbide semiconductor device includes: a gate electrode provided on a gate insulating film; and a gate pad. The gate electrode includes a first comb-tooth shaped electrode portion extending from outside of the gate pad toward a circumferential edge portion of the gate pad and overlapping with the gate pad at the circumferential edge portion of the gate pad when viewed in a plan view. A p+ region includes: a central portion overlapping with the gate pad when viewed in the plan view; and a peripheral portion extending from the central portion toward the outside of the gate pad, the peripheral portion being provided to face the first comb-tooth shaped electrode portion of the gate electrode with a space interposed therebetween.

Silicon carbide (SiC) is a semiconductor having a band gap larger than that of silicon (Si), which has been conventionally widely used as a material for semiconductor devices, and is a so-called wide band gap semiconductor. By adopting silicon carbide as a material for a semiconductor device, the semiconductor device can have a high breakdown voltage, reduced on resistance, and the like. Further, the semiconductor device thus adopting silicon carbide as its material has characteristics less deteriorated even under a high temperature environment than those of a semiconductor device adopting silicon as its material, advantageously.
For example, WO 2010/098294 (Patent Document 1) discloses a silicon carbide semiconductor device including a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) cell. The silicon carbide semiconductor device includes: a silicon carbide semiconductor substrate; a drift layer provided on a main surface of the silicon carbide semiconductor substrate and having a first conductivity type; and a well layer provided to extend from an upper surface of the drift layer to inside of the drift layer, the well layer having a second conductivity type. The silicon carbide semiconductor device further includes a semiconductor layer having the second conductivity type. This semiconductor layer is formed on the upper surface of the well layer or an upper layer portion of the well layer.


The invention relates to a method for the recognition of natural skin (5), wherein the skin surface (4) is illuminated at an irradiation point (1) with light from the visible spectrum or the adjacent spectrum, wherein that part of the light entering through the skin surface (4) at the irradiation point (1), scattered in the skin (5), and exiting from the skin surface (4) again, is detected at a detection point (9), using a detector (20), and wherein the signal determined by the detector (20) is passed to a comparator and compared with stored data. Furthermore, a device for carrying out the method is an object of the invention.

1. Field of the Invention
The invention relates to a method for the recognition of natural skin during contact-free biometric identification of a person, as well as to a device for carrying out the method.
2. Description of Related Art
In the checking of authorization with regard to access to closed systems, which can be represented by room complexes or data networks, for example, biometric checks are being performed, to an increasing degree, for identification of the person authorized for access, since there is no risk that the individual biometric characteristics of an individual can be lost or passed on, as is the case with passwords or keys. In practice, the use of the papillary line patterns of the palms or the fingertips, as a biometric characteristic that is different for every individual and does not change, has proven itself, whereby methods are known with which these papillary line patterns can be optically detected in contact-free manner. In the case of these measurements, the papillary line pattern is evaluated as such, in other words the topology of the skin surface or, to state it differently, the pattern of the relief formed by the papillary ridges, is evaluated. In this connection, there is the problem that when the papillary line pattern is known, the measurement apparatus for detecting the biometric data can, in principle, be deceived by means of false copies that contain a reproduction of the papillary line pattern in accordance with the three-dimensional original, and which are possible, for example, in the form of two-dimensional reproductions, three-dimensional reproductions, or coverings on natural fingers.
WO 01/34 027 A2 discloses a method that serves not for biometric identification, but rather for the diagnosis of skin diseases, with a related device, wherein the skin is illuminated by means of an illumination ring during the examination of skin lesions, in order to take pictures of the skin lesion, to digitalize them and evaluate them, which images are generated by means of scattered light.
EP 0 359 554 A2 describes a method for the identification of persons, wherein optical fingerprints are determined, which are brought into contact with a glass plate, in other words the method of working is not contact-free, and the glass plate is exposed to manipulation attempts and attempts to damage it, because of the accessibility that is absolutely required. In addition to the fingerprints, in order to prevent forgeries, an evaluation takes place, at the same time, as to whether there is an offset between the irradiation point and the point at which the light enters into the measurement apparatus.
U.S. Pat. No. 5,598,843 describes a device with which light is radiated in by direct contact with the skin, by means of a first emitter, which light is detected by a second emitter, which is separated from the first emitter by means of a non-transparent wall.
U.S. Pat. No. 5,419,321 also shows a non-invasive but contact-requiring sensor for optical, quantitative determination of a substance in living tissue.

This patent is subject to a terminal disclaimer.

Method and device for recognition of natural skin


A digital watermark embedding apparatus comprises an acquisition unit configured to acquire a topological invariant as digital watermark information, key information corresponding to the digital watermark information, and a target content in which the digital watermark information is to be embedded, function generation unit configured to generate a topological function corresponding to the topological invariant, a randomizing-function generation unit configured to generate a randomizing function based on the key information, and compute a composite function by composition of the randomizing function and the topological function, and a function-embedding unit configured to embed the composite function in the target content.

1. Field of the Invention
The present invention relates to a digital watermark embedding apparatus, method and program for embedding digital watermark information in content, such as digitized still image data, moving picture data, voice data, and music data, and a digital watermark detection apparatus, method and program for detecting digital watermark information in content.
2. Description of the Related Art
(Digital Watermarking)
Digital watermarking is a technique for embedding certain information in digital content (digital literary work data), such as digitized still image data, moving picture data, voice data, and music data, by varying the content to a degree in which its quality is not greatly degraded. For example, the identification information of a copyright holder or content user, information concerning the rights of a copyright holder, the conditions for using content, secret information needed to use content, or copy control information, etc. (hereinafter referred to as "watermark information") is embedded so that it is not easily perceived. When necessary, the thus-embedded watermark information is detected in the content and used for controlling the use of the content or for promoting the secondary use of the content. Further, it has been proposed to use watermark information for such purposes as identification or certification of a copyright holder, fingerprinting, certification of content, and monitoring of broadcasts.
(Requirements for Digital Watermarking)
For watermark information to be used to prevent illegal use of digital content, it is necessary to make the information robust (preventing the content from being lost or being illegally altered) against various operations or attack attempts that may be made on the content.
(Geometrical Distortion)
If the digital content is image data (still images or moving pictures), there is an attack attempt to erase the digital watermark embedded therein by geometrical distortion. Geometrical distortion means coordinate transformation of an image. That is, geometrical distortion changes the positions of pixels. Following a change in pixel position, some types of digital watermark information cannot be correctly detected.
Geometrical distortion is mainly classified into global transformation and local transformation. Global transformation means the scaling, rotation and parallel displacement of the whole image. Global transformation is expressed as an affine transformation. On the other hand, local transformation includes both transformation expressed by a local parameter, and transformation, such as global transformation, expressed by a parameter that does not relate to the position. In other words, global transformation is a special case of local transformation.
(Topological Digital Watermarking)
It is known that homeomorphic spaces have a constant property called "a topological invariant". Homotopy classes are examples of the amount (see, for example, Iwanami Mathematic Dictionary 3rd Edition, Topological Space, pp. 22-34; Homotopy Theory, pp. 1142-1150).
Digital watermarking may be related to the topological invariant by regarding local geometrical distortion as a homeomorphic mapping. A topological digital watermarking system is a technique for realizing robustness against local geometrical distortion (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 2002-142094). In topological digital watermarking, the digital watermark is a topological invariant (e.g., a homotopy class), which is invariant under local geometrical distortion, and is expressed by a function ψb corresponding to a predetermined homotopy class b. The digital watermark is detected by computing the homotopy class b from the detected function ψ′b.
In conventional digital watermarking techniques, digital watermark information is embedded as a topological invariant into content in a simple manner.

Digital watermark embedding apparatus, method and program, and digital watermark detection apparatus, method and program


The metal housing of the case of a contactor includes an annular rib extending continuously opposite the cylindrical periphery of the main stationary core, the rib having an internal diameter respectively greater than that of the ferrule and smaller than that of the housing, so as to ensure the locking of the different parts of the case and the crimping of the housing on the stationary magnet following local deformations exerted on the reduced diameter of the swaged part defining the rib.

1. Field of the Invention
The invention relates to an electromagnetic contactor for an electric starter motor, said contactor comprising:
connection terminals intended for connection to the battery and to the electric motor,
a movable core,
a main stationary core,
an axial air gap provided between the movable core and the main stationary core,
a tubular coil to produce a magnetic current in the air gap provided between the movable core and a main stationary core during excitation,                a magnetic circuit provided with a case constructed with magnetic frame attached to the stationary core,
an insulating cap enclosing the contacts of the electric power circuit and having connection terminals,                said case being composed of a metal bell-shaped housing, an internal ferrule made of magnetic material surrounding the coil, and a washer acting as an additional stationary core through which the movable core passes, and arranged opposite the main stationary core.
2. Background Art
Starters generally comprise an electromagnetic contactor, the purpose of which is to make it possible for:                the pinion to engage in the drive ring gear at the moment of starting, as well as its disengaging after starting, and        the electric motor to be supplied with current.
The contactor is generally composed of an electromagnet actuating a plunger core which, by moving, closes an electrical circuit for supplying power to the electric motor, and pulls an actuator lever that drives the pinion into the starter ring gear.
According to the document FR-A-2795884, a motor vehicle starter (see FIG. 5) has a rotary electric motor M and an output shaft equipped with a pinion 1 to drive a starter ring gear C, integral in rotation with the flywheel of the vehicle to start the combustion engine of the vehicle. The pinion 1 is slidably mounted, by means of complementary splines, on the output shaft between a rest position in which it is disengaged from the ring gear, and an active working position in which it engages with said ring gear.
The output shaft is driven in rotation by the electric motor when said motor is electrically powered. This shaft is different from the shaft of the motor M in FIG. 6 because speed-reduction gearing is located between the two shafts. As a variation, the output shaft is the shaft of the motor M.
The electric motor of the starter is also associated with an electromagnet power contactor 2 placed above the electric motor. This contactor 2 comprises a tubular coil 2a held by a support, the bottom of which constitutes a bearing 2c to guide a movable core 2b.
This contactor 2 has the dual function of supplying the electric motor M with current, and of moving the movable pinion 1 between the two positions of rest and work. The excitation of the electromagnet is controlled, for example, by activating the contact key, which establishes the electrical circuit to the battery, after the closing of the contactor's main power circuit.
The movable core 2b of the contactor 2 is mechanically connected by a mechanical connection 4, comprising a control lever, to a starter drive assembly equipped with a freewheel transmission device. The pinion 1 pertains to the starter drive assembly.
The fork-shaped control lever is pivotably mounted on a spindle and the output shaft is mounted in rotation in a housing by means of bearings.
The housing is intended to be attached to a fixed part of the vehicle and is open for the passage of the ring gear C. This housing is thus used to attach the starter to the engine of the vehicle.
The main power circuit of the contactor is provided with a pair of fixed contacts, and a bridge-shaped movable contact 3 which is attached to a pushrod actuator intended to be moved in translation by the movable core during excitation of the coil.
More specifically, the pushrod is intended to be moved by the movable core 2b after the axial clearance is closed up, and a second return spring acts on the movable core to draw it back to the rest position.
A first return spring, called cutoff spring, pulls the movable contact and pushrod assembly to an open position in order to make an axial interval with the fixed contacts.
This rest position of the pushrod is determined by contact of the movable contact 3 with a stationary core having a central hole to guide the pushrod provided with a flange for mounting a spring, called contact pressure spring, acting between this flange and the movable contact. The stationary core is flanged and has a centering seat for centering the support of the coil 2a.
Also provided is a spring 5, called gear engagement spring, housed inside the movable core 2b and engaged with a rod connected by a spindle to the upper end of the fork-shaped control lever to couple this lever to the movable core 2b.
The contactor, generally cylindrical in shape, is situated near the electric motor while extending parallel thereto. It is attached to the above-mentioned housing that supports the output shaft and the pinion slidably mounted on said shaft. In a known way the housing also has the frame of the electric motor M closed by a rear bearing for the mounting in rotation of the shaft of the electric motor M. The housing has a front bearing for the mounting in rotation of the output shaft as an extension of the shaft of the electric motor M by means of a bearing between the ends of the said shafts.
In addition to the movable core, the contactor comprises a fixed part of magnetic material, and a cap of insulating material and having connection terminals connected to the fixed contacts. The fixed part of the contactor is composed of a dish-shaped frame designed to be mounted on the housing, and the stationary core separated from the movable core by an axial air gap. The tubular coil coaxially surrounds the movable core with a slight radial clearance, and is housed inside the case.
The movable core, under the action of the second return spring, is in a position separated from the stationary core when the coil is not excited.
When power is supplied to the coil, i.e., during excitation of the coil, the movable core moves by magnetic attraction toward the stationary core at first against the retraction force of the first return spring. After the closing up of the axial clearance between the movable core and the pushrod, the movable core then moves the pushrod against the force exerted by the second and first return springs. This first return spring is stiffer than the second return spring and is less stiff than the contact pressure spring.
This movement continues until the movable contact makes contact with the fixed contacts and power is supplied to the electric motor. The contact pressure spring is then compressed until the movable core comes into contact with the stationary core.
At the same time the starter drive assembly is moved, under action from the control lever, toward the ring gear C.
In the event the pinion 1 does not directly penetrate the ring gear C, the spring 5 is compressed to allow the fixed contacts to close and supply power to the electric motor, which then turns the pinion so that it can penetrate the ring gear C.
The structure of the magnetic circuit of such a contactor is well known, for example from the document DE 101 55 103 or by the above-mentioned document FR A 2 795 884.
In FIG. 1, the stationary core 10 of the contactor is generally immobilized in rotation with respect to the case 11 attached by one or more deformations of the case's side wall so as to form serrations 12 that are embedded in cavities 13 made on the periphery or behind the stationary core 10. When the case is produced by stacking several elements, careless handling of the case can result in a risk of the assembly coming apart.
In FIG. 2, the cap 14 must also be blocked from rotation with respect to the case 11 in order to withstand a certain tightening torque C on the connection terminals. The serrations 12a provided for that purpose are also made by deformation of the material of the end of the case 11, which are then inserted into the cavities 13a of the cap 14. When a certain tightening torque on the cap 14 is exceeded, said cap can undergo the beginning of rotation movement, with the risk of the serrations 12a escaping. This situation could occur in the event of insufficient mechanical rigidity of a case obtained by stamping a thin (0.5 to 1.5 mm) sheet of metal. The risk of ovalization of the case due to the action of a heavy rotation torque is then possible, and the function of immobilizing the case from rotation is no longer ensured.

Electromagnetic contractor for controlling an electric starter


A wind turbine park (242) connected to a transmission system (234). The wind turbine park includes a component (230) for determining a short circuit ratio and based thereon for determining a parameter adjustment recipe, and a controller (238) for controlling an output of the wind turbine park, the controller (238) executing a control algorithm using a determined parameter adjustment recipe, the determined parameter adjustment recipe responsive to the short circuit ratio and determined within the component (230) or within the controller (238).

Due to current efforts to reduce consumption of natural resources, the conversion of wind energy to electrical energy using wind turbine generators is becoming more prevalent. Wind turbines exploit wind energy by converting the wind energy to electricity for distribution to end users.
A fixed-speed wind turbine is typically connected to the grid through an induction (asynchronous) generator for generating real power. Wind-driven blades drive a rotor of a fixed-speed wind turbine that in turn operates through a gear box (i.e., a transmission) with a fixed rotational speed output. The fixed-speed gear box output is connected to an induction generator for generating real power.
The rotor and its conductors rotate faster than the rotating flux applied to the stator from the grid (i.e., higher than the synchronous field frequency). At this higher speed, the direction of the rotor current is reversed, in turn reversing the counter EMF generated in the rotor windings, and by generator action (induction) causing current (and real power) to be generated in and flow from the stator windings.
The frequency of the generated stator voltage is the same as the frequency of the applied stator voltage providing the excitation. The induction generator may use a capacitor bank for reducing reactive power consumption (i.e., the power required to generate the stator flux) from the power system.
The fixed-speed wind turbine is simple, reliable, low-cost and proven. But its disadvantages include uncontrollable reactive power consumption (as required to generate the stator rotating flux), mechanical stresses, limited control of power quality and relatively inefficient operation. In fact, wind speed fluctuations result in mechanical torque fluctuations that then result in fluctuations in the electrical power on the grid.
In contrast to a fixed-speed wind turbine, the rotational speed of a variable speed wind turbine can continuously adapt to the wind speed, with the blade speed maintained at a relatively constant value corresponding to a maximum electrical power output through the use of a gear box disposed between the wind turbine rotor and the generator rotor.
The variable speed wind turbine may be of a doubly-fed induction generator (DFIG) design or a full converter design. The doubly-fed induction generator uses a partial converter to interchange power between the wound induction generator rotor and the power system. The full converter wind turbine is typically equipped with a synchronous or asynchronous generator (the output of which is a variable frequency AC based on the wind speed) and connected to the grid through a power converter that rectifies the incoming variable-frequency AC to DC and inverts the DC to a fixed-frequency 60 Hz AC. Variable-speed wind turbines have become widespread due to their increased efficiency over fixed-speed wind turbines and superior ancillary service capabilities.
FIG.1 illustrates components of an exemplary variable speed wind turbine 8, including rotor blades 12 for converting wind energy to rotational energy for driving a shaft 16 connected to a gearbox 18. The wind turbine also includes a structural support component, such as a tower and a rotor pointing mechanism, not shown in FIG.1. The gearbox 18 converts low speed rotation to high speed rotation, as required for driving a generator 20 to generate electricity.
Electricity generated by the generator 20 is supplied to a power electronics system 24 to adjust the generator output voltage and/or frequency for supply to a grid 28 via a step-up transformer 30. The low-voltage side of the transformer is connected to the power electronics system 24 and the high-voltage side to the grid 28. Generally, the power electronics system imparts characteristics to the generated electricity that are required to match electricity flowing on the grid, including controllable active power flow and voltage regulation and improved network voltage stability.
One embodiment of the power electronics system 24 includes a generator-side converter for converting the generated AC electricity to DC and an output capacitor for filtering the DC current. DC current is supplied to a line side converter (inverter) for producing 60 Hz AC power supplied to the grid 28. The amount of power available from the wind turbine is determined by operation of the generator-side converter.
One type of converter employed in a variable speed wind turbine, referred to as a full converter or a back-to-back converter, comprises a power converter connected to the generator side, a DC link and a power converter connected to the grid. The full converter converts an input voltage, i.e., a fixed frequency alternating current, a variable frequency alternating current (due to the variable wind speed) or a direct current, as generated by the wind turbine, to a desired output frequency and voltage as determined by the grid that it supplies. Typically using thryistors, the full converter converts the electricity produced by the generator to DC and transfers this energy to the DC link.
From the DC link the electricity is supplied to the grid-side active converter where it is transformed to fixed frequency AC electricity and supplied to the grid.
FIG.2 illustrates a wind park or wind farm 50 comprising a plurality of wind turbines 54 (such as the variable speed wind turbine 8 illustrated in FIG.1 or a fixed speed wind turbine) connected through a feeder or collector 56, which serves as a distribution system within the wind turbine park. Several feeders may be required for an average size wind turbine park.
The wind park 50 further comprises a wind park controller 60 and a wind park transformer 64. The wind park controller 60 controls operation of the wind turbines 54. The transformer 64 connects the wind park collector 56 to a utility system or grid 68 via a point of common coupling (PCC) 72.
The wind turbines 54 bidirectionally communicate with the controller 60 via control lines 78. The signals carried over the control lines 78 relate to wind turbine output power, wind turbine status, a reference power, wind turbine operational commands, etc. The controller 60 is also connected to the PCC 72 via a control line 80. This connection allows the controller 60 to detect power parameters, such as voltage and current, at the PCC 72.
The wind park controller 60 generally fulfills a plurality of control functions related to the individual wind turbines 54 and therefore the output of the wind park 50. For example, the wind park controller 60 collects data characterizing the current state of each wind turbine 54 and in response thereto independently controls operation of each wind turbine 54.
The wind park 50 is only an example of a conventional wind turbine park. The teachings of the present are not restricted to the depicted layout of FIG.2.

Method and apparatus for adaptively controlling wind park turbines


Stabilization systems for high pH, aqueous liquid detergent compositions containing detergent enzyme and peroxygen bleaches are disclosed.. The detergent compositions contain magnesium salts as an enzyme stabilizing system.

EP 88-201009.3 discloses aqueous liquid detergent compositions containing a peroxygen bleach. The compositions are designed to limit the amount of available oxygen in solution. Enzyme-containing compositions are disclosed. The patent document does not disclose stabilization systems for the enzymes. At the time of filing of the present patent application, no publication of EP 88-201009.3 has taken place.
EP 28 865 discloses a stabilization system for enzymes in a liquid detergent composition comprising formic acid or a salt thereof and calcium ions. The disclosed composition have a pH of from 6.5 to 8.5.
U.S. Pat. No. 4,381,247 discloses a dry, powdered, enzyme containing, bleaching compositions; stabilizers including magnesium sulphate are disclosed.
Liquid detergent compositions containing enzymes and stabilization agents including magnesium salts are disclosed in U.S. Pat. Nos. 3,676,374; 4,443,355 and GB-A-2,794,826

Stabilized alkaline liquid detergent compositions containing enzyme and peroxygen bleach


The aircraft applicable current imbalance detection and circuit interrupter interrupts an electrical circuit when a current imbalance is sensed. The current imbalance detection and circuit interrupter includes a housing, power supplies, a sensor system for sensing a current imbalance at the line side of the electrical circuit, a logic controller and a power controller including a power relay having contacts capable of surviving carry-break and make-carry-break types of ground fault conditions at anticipated current levels. At power up, the device performs a test to confirm that none of the relay contacts have failed in a closed position, and to check whether a switching FET which controls the relay coil has shorted.

This invention relates generally to electrical control systems, and more specifically to an aircraft electrical control system which disconnects power to a load when a current imbalance is sensed.
In the electromechanical arts, current imbalances are indicative of serious problems that can lead to disastrous results, such as arcing within fuel pumps. Since fuel pumps are often housed within a fuel vessel to directly pump fuel out of the vessel, arcing within a fuel pump can lead to an explosion of fuel-air mixture and a subsequent breach of the fuel vessel, which can be catastrophic. In light of the seriousness of such an event, a device or methodology is needed which can suppress this type of arcing, as well as other associated problems. Presently, a common type of circuit protection device being utilized in aircraft is a thermal circuit breaker. However, arcing typically does not cause thermal circuit breakers to activate. Thus, there has been a long-felt need for the function of current imbalance detection in an aircraft. One very important form of current imbalance is a ground fault in which current is flowing between a circuit or electrical device to ground, when such current flow is not desired. In the prior art, ground fault detection has been addressed by a separate ground fault interruption unit. However, such prior art systems have had limitations, including the necessity of rewiring the aircraft. In addition to the requirement to rewire the aircraft, additional space had to be found to accommodate the ground fault interruption system.
One currently available ground fault interruption unit made by Autronics (model 2326-1) has been used in large commercial aircraft for the purpose of ground fault protection for fuel pumps. The Autronics unit detects a ground fault and outputs a signal indicative of a fault by use of a current transformer and acts by removing power to the fuel pump control relay.
Two different types of ground fault conditions can occur. The first type of ground fault condition occurs during normal ground fault interruption (GFI) operation (Control Voltage On state), in which the ground fault occurs after the relay contacts are closed, and power is being provided to the load. In relay terminology, this is known as "carry-break," i.e., the relay contacts are fully closed and carrying the current when a contact has to interrupt the fault current. Many conventional 25 Amp relays can interrupt as much as a 500 Amp current without failure. However, the second type of ground fault condition is a more severe condition for relay contacts. This second type of ground fault condition occurs when the GFI is just powered and the relay contacts close into an existing ground fault. In relay terminology, this is known as "make-carry-break," i.e., the relay contacts have just closed and the relay is immediately commanded to open and interrupt the fault current. In this second type of ground fault condition, severe arcing can occur at the relay contacts as a result of "contact bounce," in which moving contacts make and break electrical contact several times due to their inherent mass and springiness before the contacts come to rest. Unfortunately, severe arcing can occur during contact bounce in this type of ground fault condition which can also result in the welding together of the relay contacts. Tests performed with relays have shown that in this second type of ground fault condition, 25 Amp conventional relay contacts can become welded together with an arcing ground fault current as low as 150 Amps.
A need therefore exists for an improved circuit protection device for aircraft that can handle both carry-break and make-carry-break types of ground fault conditions, and fault current amplitudes, so as to insure that ground fault interruption can always be carried out without failure of the ground fault circuit interrupter. It would also be desirable to provide a ground fault circuit interrupter that at power up will perform a test to confirm that none of the relay contacts have failed in a closed position, and to check that the switching FET which controls the relay coil has not shorted.
It would further be desirable for the circuit protection device to be included within an existing device in the aircraft, or to be packaged with an existing device, sharing the same connections to existing electrical circuits, since space for avionics is limited in any aircraft and adding wiring to accommodate a new device is very difficult. The present invention addresses these and other concerns.

Aircraft applicable circuit imbalance detection and circuit interrupter and packaging thereof


A multiport DRAM having a DRAM cell array; a sequential access memory (SAM) for inputting data of a specific length to the DRAM cell array and transmitting that data to an external device; a SAM address counter for counting the addresses of the data in the SAM; a serial port connected to the SAM for transmitting the data in the SAM to an external device; a data transfer address counter, the contents of which is cleared by inputting an external reset signal and is counted up by inputting an overflow signal which is output from the SAM address counter; and a data transfer controller for outputting a data transfer status signal which indicates that data transmission is in progress when data of a specific length in the DRAM cell array designated by the input of the overflow signal by the data transfer address counter is transmitted to the SAM.

1. Field of the Invention
The present invention relates to a display memory for storing data to be displayed by a monitor, and, in particular, to a display memory such as a multiport DRAM comprising a frame buffer.
2. Description of the Prior Art
A conventional multiport DRAM, as shown in FIG. 1, for example, is provided with two ports, a serial port PS and a random port PR, and is constructed so that access to a desired address is obtained by an address signal SA.
In a multiport DRAM 101 of this type it is necessary to input an address value from an external source as the address signal SA for specifying a row to be transmitted from a DRAM cell array 3 to a SAM 9 during data transfer.
In addition, in a display system using the multiport DRAM 101 as shown in FIG. 2, when the address value is input to the multiport DRAM 101, an address ADT for data transfer transmitted from a display control unit 73 and an image address ADR for random access transmitted from an image control unit 71 must be selected by a multiplexer 111 because the random access address input signal terminal PR is used.
Accordingly, a multiplexer is required for the data transfer address and the random access address and a circuit is required for control and the like of the multiplexer. A large system is therefore required.
In addition, a delay, specifically, a gate delay is produced in the signal transmission in the multiplexer or multiplexer control system.
This is an obstacle to high speed memory access of the image control unit 71. Specifically, it is difficult to process the image. As outlined above, in order to use one address input signal terminal for both random access and data transfer with a conventional multiport DRAM when the DRAM is incorporated in a display system, a circuit and a multiplexer are necessary to multiplex and control a display system address ADT and an image control address ADT. For this reason the scale of the system is large and, in addition, it is difficult to convert to high speed image processing.


A solid-state imaging apparatus, comprising: a pixel section including a matrix having a plurality of pixels, each pixel including photoelectric conversion means, a storage section, transfer means, amplification means, and reset means, on a column basis, an output signal line whose one end is coupled to a constant-current source, and in which the area carrying thereon the matrix of the pixels includes a light-shielding area, a read area, and a transition area disposed between the light-shielding area and the read area; and control means for performing control to keep the potential difference between the one end and the other end of the constant-current source in a range with which the constant-current source can be operated by using the pixel signal to be output to the output signal line at the time of resetting the pixel of the transition area, when outputting the pixel signal corresponding to the incident light from the pixel of the read area.

The present invention relates to a solid-state imaging apparatus for use in a camcorder, a digital still camera, and others and, more specifically, to a solid-state imaging apparatus using an amplified solid-state imaging device that has an amplifier capability in an imaging area.
Imaging apparatuses such as digital cameras have recently started using MOS (Metal Oxide Semiconductor) image sensors. The MOS image sensors each have an active element in a pixel as an imaging device, thereby allowing on-chip peripheral circuits. FIG. 1 shows the circuit configuration of a MOS image sensor of a general type. The general MOS image sensor usually carries a plurality of pixels arranged two dimensionally, but for simplification, FIG. 1 shows only three pixels P11, P12, and P13 arranged in a row. These pixels P11, P12, and P13 are configured to each include a photodiode PD, a transfer transistor M1, a reset transistor M2, and a selection transistor M4, and respectively include floating diffusion sections FD11, FD12, and FD13, and amplification transistors M311, M312, and M313. The floating diffusion sections FD11, FD12, and FD13 are those each having a capacitance. The pixels P11, P12, and P13 are coupled to each corresponding correlated double sampling circuit (CDS circuit) 10 respectively via vertical signal lines 31, 32, and 33. The vertical signal lines 31, 32, and 33 are respectively coupled to bias transistors M51, M52, and M53 at their each one end. The bias transistors M51, M52, and M53 each serve as a constant-current source with their other ends being-grounded. These bias transistors M51, M52, and M53 are under the control of a bias current adjusting voltage Vbias.
The CDS circuits 10 are each configured to include a clamp transistor M11, a sample hold transistor M12, a clamp capacitor C11, and a sample hold capacitor C12. The CDS circuits 10 are coupled to a horizontal signal line 7 via their corresponding column selection transistors M6, and are so configured as to output image signals via an output amplifier 5. Various types of pulses are provided respectively from a vertical scanning section 2 and a horizontal scanning section 4 under the control of a timing control section 6. The various types of pulses include a transfer pulse φTR1, a reset pulse φRST1, and a row selection pulse φROW1, which are respectively related to the control of the transistors in each of the pixels, i.e., the transfer transistor M1, the reset transistor M2, and the selection transistor M4. The various types of pulses also include column selection pulses φH1, φH2, and φH3, which are related to the control of the column selection transistors M6. Other pulses related to the control of the clamp transistor M11 and the sample hold transistor M12, i.e., a clamp pulse φCL, and a sample hold pulse φSH, are to be output from the timing control section 6.
The MOS image sensor configured as above suffers from image quality deterioration due to the varying threshold value of the amplification transistors M311 to M313, and the reset noise of the reset transistor M2 in every pixel. However, such noise can be removed by finding a pixel-output difference in each of the CDS circuits 10, i.e., a difference between the pixel output after the resetting and the pixel output after the transferring of the signal charges of the photodiode PD. With the noise favorably removed as such, only optical signals serving as image signals can be output.
The MOS image sensor provided with the CDS circuits is known to generate, when a high-luminance light enters thereinto, a completely black image that looks like a result of no entry of light. Such a phenomenon is hereinafter referred to as black sun phenomenon. Described next is such a black sun phenomenon in the MOS image sensor. FIG. 2 is a timing chart for illustrating the operation of causing the black sun phenomenon when a high-luminance object is imaged. Exemplified here is a case where a high-luminance light is being directed to the center pixel P12 of FIG. 1, but a light is hardly entered to the remaining pixels P11 and P13.
(1) First of all, in a reset period T1, when a row selection pulse φROW1 is in the state of H (High) level, a reset pulse φRST1 is set to the H level, and the floating diffusion sections FD11, FD12, and FD13 of each pixel are fixed to a power supply voltage VDD. In the CDS circuits 10, a clamp pulse φCL and a sample hold pulse φSH are both set to the H level.
(2) In the next reset sampling period T2, the reset pulse φRST1 is set to the L (Low) level. In this period, in the pixels P11 and P13 not being exposed to a high-luminance light, the floating diffusion sections FD11 and FD13 respectively show no change of their voltages VFD11 and VFD13 (VFD13 is not shown), but in the pixel P12 being exposed to a high-luminance light, the floating diffusion section FD12 drops its voltage VFD12 as shown in the drawing due to the leakage of charge from the photodiode PD, for example. This resultantly causes the reduction of a potential V32(Rst) of the vertical signal line 32 that is coupled with the pixel P12, thereby deriving (VFD12−VGS-M312). Note here that this term of VGS-M312 denotes the gate-source voltage of the amplifier transistor M312 of the pixel P12. At the end of the reset sampling period T2, the potential of each of the vertical signal lines 31 to 33 are clamped with the clamp pulse φCL being set to the L level in the CDS circuits 10.
(3) In the following signal transfer period T3, with a transfer pulse φTR1 being set to the H level, the signal charges of the photodiode PD in each of the pixels P11 to P13 are transferred to their corresponding floating diffusion sections FD11 to FD13. At this time, the voltage VFD12 of the floating diffusion section FD12 in the pixel P12 being exposed to the high-luminance light is already reduced in the reset sampling period T2. Therefore, even if the charges of the photodiode PD are transferred, the resulting voltage change is not that much from the value in the reset sampling period T2, i.e., no voltage change is observed when the voltage VFD12 of the floating diffusion section FD12 has reached its bottom value due to the leakage of charge. As a result, the vertical signal 32 also shows a slight change of the potential V32(Sig). Note here that, at this time, because the pixels P11 and P13 are assumed as being hardly exposed to a light, the remaining vertical signal lines 31 and 33 also hardly show a change of potential.
(4) In the following signal sampling period T4, with the processing operation of the CDS circuits 10, the potential difference [V32(Rst)−V32(Sig)] is retained at the sample hold capacitor C12. The potential difference being the processing result in each of the CDS circuits 10 are output as image signals via the column selection transistors M6 and the output amplifier 5. At this time, in the pixel P12 being exposed to the high-luminance light, a black sun phenomenon is observed due to the variation of the potential V32(Rst) of the vertical signal line 32 in the reset sampling period T2, i.e., the potential difference [V32(Rst)−V32(Sig)] being the CDS processing result is small, and thus the output looking black is output as an image signal.
Such a problem of black sun phenomenon can be solved with still image shooting if a mechanical shutter is provided. However, with moving image shooting not using a mechanical shutter, for example, the black sun phenomenon is inevitable.
There is another concern that the entering of the high-luminance light may affect any pixel areas other than the pixel being exposed thereto. FIG. 3 is a timing chart for illustrating the operation of causing a highlight transverse stripe phenomenon to be observed around the pixel being exposed to a high-luminance light. Exemplified here is also a case where a high-luminance light is being directed to the center pixel P12 of FIG. 1, but a light is hardly entered to the remaining pixels P11 and P13. This example is with an assumption that no black sun phenomenon is to be observed.
(1) First of all, in the reset period T1, similarly, when a row selection pulse φROW1 is in the state of H level, a reset pulse φRST1 is set to the H level, and the voltages of the floating diffusion sections FD11, FD12, and FD13 of each of the pixels, i.e., voltages VFD11 to VFD13, are all fixed to the power supply voltage VDD. In the CDS circuits 10, a clamp pulse φCL and a sample hold pulse φSH are both set to the H level.
(2) In the next reset sampling period T2, at the end thereof, the clamp pulse φCL is set to the L level in the CDS circuits 10, and the voltages of the floating diffusion sections FD11 to FD13 of each of the pixels are clamped to the CDS circuits 10 respectively via the vertical signal lines 31 to 33.
(3) In the following signal transfer period T3, with a transfer pulse φTR1 being set to the H level, the signal charges of the photodiode PD in each of the pixels P11 to P13 are transferred to their corresponding floating diffusion sections FD11 to FD13. At this time, the voltage VFD12 of the floating diffusion section FD12 in the pixel P12 being exposed to the high-luminance light is largely reduced from the power supply voltage VDD due to the large amount of signal charges therein. Therefore, the potential V32 of the vertical signal line 32 coupled with the pixel P12 is largely reduced down to (VFD12−VGS-M312). This accordingly reduces the drain-source voltage of the bias transistor M52 coupled to the vertical signal line 32, thereby reducing the current flowing to the bias transistor M52. This reduction of the current thus reduces any possible voltage drop to be caused by the GND resistance of a GND line coupled to all of the sources of the bias transistors M51 to M53 so that the gate-source voltage is increased in the bias transistors M51 and M53 respectively coupled to the vertical signal lines 31 and 33. As a result, the current flowing to the vertical signal lines 31 and 33 is increased. This increase of the current then increases the gate-source voltage in the amplification transistors M311 and M313 of the pixels P11 and P13, respectively, so that the potentials V31 and V33 of the vertical signal lines 31 and 33 will be in the level lower by ΔV than the reset level output (VDD).
(4) In the following signal sampling period T4, with the processing operation of the CDS circuits 10, the difference between the reset potential and the optical-signal-reading potential after the transferring of the signal charges in the vertical signal lines 31 to 33 is output as an image signal via the column selection transistors M6 and the output amplifier 5. At this time, in the pixels P11 and P13 in the vicinity of the pixel P12 being exposed to the high-luminance light, the potential difference ΔV from the reset level is detected due to the variation of the current via the GND line coupled to the bias transistor M52 as described above. Thus detected potential difference ΔV will look a white float-like image, thereby causing the highlight transverse stripe phenomenon in the image signal.
In the MOS image sensor as such, when a window chart is imaged, such images as shown in FIGS. 4A to 4D may be derived due to the black sun phenomenon and the highlight transverse stripe phenomenon. FIG. 4A shows the pattern of an object with a high-luminance light at the center, and FIG. 4B shows the state in which the black sun phenomenon is observed due to the variation of the reset potential. FIG. 4C shows the state in which the highlight transverse stripe phenomenon is observed due to the variation of the signal potential, and FIG. 4D shows the state in which the black sun phenomenon is observed together with the highlight transverse stripe phenomenon.
JP-A-2007-20156 describes the previous technique as below not to cause the black sun phenomenon and the highlight transverse stripe phenomenon in the MOS image sensor described above. That is, with the technique, as shown in FIG. 5, clipping circuits 71 to 73 are provided respectively to the vertical signal lines 31 to 33 to selectively restrict the potentials thereof to be the value of a first or second potential. With such a configuration, the pixel output after the resetting of the pixels is so controlled as not to be the value of the first potential or lower, and the pixel output after the transferring of the signal charges is so controlled as not to be the value of the second potential or lower. Note here that the clipping circuits 71 to 73 are respectively configured to include clipping transistors M71 to M73, and clipping selection transistors M81 to M83. In the configuration, the gates of the clipping transistors M71 to M73 are coupled to a clipping voltage Vclip, and the drains thereof are coupled to the power supply voltage VDD. The gates of the clipping selection transistors M81 to M83 are applied with a clipping selection pulse φROWD, and the sources thereof are respectively coupled to the vertical signal lines 31 to 33. The clipping voltage Vclip and the clipping selection pulse φROWD are to be output from the timing control circuit 6.
Described next is the operation of the MOS image sensor provided with the clipping circuits as in the above configuration by referring to the timing chart of FIG. 6. Exemplified also here is a case where a high-luminance light is being directed to the center pixel P12 of FIG. 5, but a light is hardly entered to the remaining pixels P11 and P13 therearound.
(1) First of all, in the reset period T1, a row selection pulse φROW1 is set to the H level, and the clipping voltage Vclip is set to a first level VclipH, i.e., the level being lower than the power supply voltage VDD but not causing the black sun phenomenon. A reset pulse φRST1 is set to the H level, and the floating diffusion sections FD11, FD12, and FD13 of each of the pixels are fixed to the power supply voltage VDD. In the CDS circuits 10, a clamp pulse φCL and a sample hold pulse φSH are both set to the H level.
(2) In the next reset sampling period T2, in the pixel P12 being exposed to a high-luminance light, the floating diffusion section FD12 shows a considerable reduction of its voltage VFD12 due to the leakage of charge from the photodiode PD, for example. As a result, when there is no clipping circuit provided, the potential V32 of the vertical signal line 32 is also reduced to a considerable degree. In this example, however, with the clipping circuit 72 provided, the potential V32(Rst) of the vertical signal line 32 will not be reduced to or below the potential of (VclipH−VGS-M72) as is clipped thereto. This accordingly prevents any possible black sun phenomenon from occurring also by the differential processing to be executed next by the CDS circuits 10. Note here that the term of VGS-M72 denotes the gate-source voltage of the clipping transistor M72. At the end of the reset sampling period T2, the potentials of the vertical signal lines 31 to 33 are clamped with the clamp pulse φCL being in the L level in the CDS circuits 10.
(3) In the following signal transfer period T3, the level of the clipping voltage Vclip is changed to a second level VclipL in which no highlight transverse stripe phenomenon is to be caused, and by setting the transfer pulse φTR1 to the H level, the charges of the photodiode PD in each of the pixels P11 to P13 are transferred to the corresponding floating diffusion sections FD11 to FD13. At this time, the voltage VFD12 of the floating diffusion section FD12 in the pixel P12 being exposed to the high-luminance light is largely reduced. As such, when there is no clipping circuit provided, the potential V32 of the vertical signal line 32 is also largely reduced, and the drain-source voltage of the bias transistor M51 is reduced down to a value outside of the range of operating the bias transistor M51, thereby causing highlight transverse stripe. However, if the voltage of the clipping circuit, i.e., voltage VDD2, is set to the second clipping level VclipL, the voltage V32 of the vertical signal line 32 will not down to or below the value of (VclipL−VGS-M72) as is clipped thereto, thereby operating the bias transistor M51. This accordingly prevents any possible highlight transverse stripe from occurring.
(4) In the following signal sampling period T4, with the processing operation of the CDS circuits 10, the potential difference of the vertical signal lines 31 to 33, i.e., the difference between the reset potential and the optical-signal-reading potential after the transferring of the signal charges, is retained at the sample hold capacity C12. The potential difference is then output, via the column selection transistors M6 and the output amplifier 5, as an image signal free from the black sun phenomenon and the highlight transverse stripe phenomenon.
As described above, with the clipping circuits provided as such, any possible black sun phenomenon and highlight transverse stripe phenomenon can be both favorably prevented.


A semiconductor laser element having an advantageous vertical light confinement efficiency, a low threshold current and a low element resistance is provided. The semiconductor laser element has a substrate and a stacked structure formed thereon, where the stacked structure comprises a buffer layer, an n-Al0.6Ga0.4As cladding layer, an n-Al0.47Ga0.53As cladding layer, an active layer, a p-Al0.47Ga0.53As first cladding layer, an Al0.55Ga0.45As etching stop layer, a p-Al0.47Ga0.53As second cladding layer, a p-Al0.6Ga0.4As third cladding layer, and a p-GaAs contact layer. The second and third cladding layers, and the contact layer are formed as a stripe-patterned ridge, and serve as a current injection regions. Both lateral portions of the ridge are filled with an n-type current blocking layer and serve as non-current-injection regions. Because the cladding layers on the active-layer-section side have a refractive index larger than that of the cladding layers disposed outward thereof, light leaked from the active layer section can efficiently be confined within the cladding layers on the active-layer-section side.

1. Field of the Invention
The present invention relates to a semiconductor laser element and a method of fabricating the same, and more particularly to a AlGaAs-based ridge-stripe semiconductor laser element withlow operational voltage and low element resistance, and a method of fabricating the element.
2. Description of the Related Art
In recent years, AlGaAs-based infrared wavelength semiconductor laser elements are used as light sources for reading devices, rewriting devices and initializers for optical disks. In particular, infrared high-output semiconductor laser elements of a broad-stripe type capable of oscillating lateral multi-mode laser light are expected as light sources for exciting solid lasers such as Nd:YAG and Nd:YVO4 having absorption band of the crystals at around 808 nm. Also processing tools such as welders based on use of the infrared high-output semiconductor lasers are becoming increasingly popular.
In these fields, the high-output semiconductor laser elements have particularly been on demand for realizing a still higher light confinement efficiency and a still lower threshold current.
Referring to FIG. 10, a configuration of a conventional AlGaAs-base semiconductor laser element having a buried-ridge-type structure will be described. FIG. 10 is a cross-sectional view of a conventional AlGaAs-base semiconductor laser element having the buried-ridge-type structure.
As shown in FIG. 10, a conventional buried-ridge-type AlGaAs-base semiconductor laser element 200 includes a double-hetero-stacked structure formed on an n-GaAs substrate 201, where the stacked structure comprises an n-GaAs buffer layer 202, an n-Al0.47Ga0.53As cladding layer 203, an active layer section 204, a p-Al0.47Ga0.53As first cladding layer 205, an etching stop layer 206, a p-Al0.47Ga0.53As second cladding layer 207 and a p-GaAs contact layer 208, all of which are epitaxially grown sequentially in this order.
The p-second cladding layer 207 and p-contact layer 208 are formed as a ridge so as to constitute a current injection region 220. Both lateral sections of the ridge composing the current injection region 220 are filled with an n-GaAs current blocking layer 211 to thereby form non-current-injection regions 221.
A p-side electrode 212 is formed on the upper surfaces of the p-contact layer 208 and the n-GaAs current blocking layer 211, and an n-side electrode 213 is formed on the back surface of the n-GaAs substrate 201.
In the semiconductor laser element 200, filling of both lateral sections of the ridge-stripe-patterned current injection region 220 with a semiconductor material of a conduction type opposite to the current injection region 220 is successful in realizing narrowing of both the current and refractive-index-based waveguide at the same time.
It can thus be said that the aforementioned semiconductor laser element 200 has a configuration capable of effectively confining both injected carriers and laser light.
The following paragraphs will describe a method of fabricating the conventional semiconductor laser element 200 referring to FIG. 11A to FIG. 13F. FIGS. 11A and 11B, FIGS. 12C and 12D, and FIGS. 13E and 13F are cross-sectional views showing layer structures in the individual process steps in the fabrication of the conventional semiconductor laser element 200.
First, as shown in FIG. 11A, the n-GaAs buffer layer 202, the n-Al0.47Ga0.53As cladding layer 203, the active layer section 204, the p-Al0.47Ga0.53As first cladding layer 205, the etching stop layer 206, the p-Al0.47Ga0.53As second cladding layer 207, and the p-GaAs contact layer 208 are epitaxially grown sequentially in this order on the n-GaAs substrate 201 in the first epitaxial growth step by an organometallic vapor phase growth process such as the MOVPE process and MOCVD process, to thereby form a stacked structure 210 having a double hetero-structure.
In the epitaxial growth, Si, Se and so forth are used as the n-type dopant, and Zn, Mg, Be and so forth as the p-type dopant.
Next, as shown in FIG. 11B, an SiO2 film 214 is formed on the top surface of the stacked structure 210, that is, the upper surface of the p-GaAs contact layer 208, by a CVD (Chemical Vapor Deposition) process or the like, and further on the SiO2 film 214, a stripe-patterned resist mask 215 is formed by photolithography.
Next, the SiO2 film 214 is mask-patterned with the resist mask 215, and the resist mask 215 is then removed, to thereby form an SiO2 mask 214 on the p-GaAs contact layer 208, as shown in FIG. 12C.
Next, the p-GaAs contact layer 208 and the p-Al0.47Ga0.53As second cladding layer 207 are etched by wet etching technique under masking with the SiO2 mask 214, to thereby form a ridge.
The etching is carried out using an etchant which is capable of completely removing the p-GaAs contact layer 208 and the p-Al0.47Ga0.53As second cladding layer 207, and having an etching selectivity enough to terminate the etching on the surface of the etching stop layer 206. This makes it possible to selectively remove the p-Al0.47Ga0.53As second cladding layer 207 without affecting the etching stop layer 206.
Next, as shown in FIG. 13E, the process advances to a second epitaxial step, where the n-GaAs current blocking layer 211 is grown on both lateral potions of the ridge. Because the SiO2 mask 214 resides on the ridge, the GaAs current blocking layer 211 does not grow on the ridge.
Next as shown in FIG. 13F, the SiO2 mask 214 is removed, the p-side electrode 212 is formed on the p-contact layer 208 and the n-GaAs current blocking layer 211, and the n-side electrode 213 is formed on the back surface of the n-GaAs substrate 201.
The aforementioned conventional semiconductor laser element 200 is obtained after all of the above-mentioned process steps.

Semiconductor laser element and method of fabrication thereof


An electrical connector includes an insulative housing (1) and an electrical contact (2) received in the insulative housing. The electrical contact includes a planar main portion (20), a soldering portion (21) extending horizontally from a lower end of the main portion and first and second elastic arms (23, 24) extending from an upper end of the main portion. The first elastic arm has a first connecting portion (232) connecting to the main portion. The second elastic arm has a first curved portion (243) connecting to the main portion, a second curved portion (244) connecting with the first curved portion and a connecting portion (242) vertically extending from the second curved portion. Two contact portions (230, 240) extend respectively and laterally from the first and second connecting portions. A first distance defined between the connecting portions is larger than a second distance defined between the contact portions taken from a side view.

1. Field of the Invention
The present invention relates generally to a socket connector, and more particularly to a Zero Insertion Force (ZIF) socket connector for electrically interconnecting a Central Processing Unit (CPU) with a Printed Circuit Board (PCB).
2. Description of Related Arts
U.S. Pat. No. 6,267,615 issued to Lin on Jul. 31, 2001 discloses an electrical contact comprising a main portion, a soldering portion, a pair of wing portions extending laterally and forwardly from two edges of the main portion and a pair of contact portions each formed at a free end of the wing portion. However, such kind of electrical contact consumes a large quantity of material in manufacture because the electrical contact takes a large width in a plane view before the wing portions are folded. Therefore, each two adjacent electrical contacts have a larger distance therebetween before the contacts are cut off from the belt. Usually, the adjacent electrical contacts usually have double pitch which is two times of a distance defined between the adjacent passageways of the insulative housing. In an assembling of the electrical contacts into the insulative housing, two or three times are usually needed to insert the same row of electrical contacts, which is rather troublesome and time-using.
U.S. Pat. No. 6,471,534 issued to Lee on Oct. 29, 2002 discloses an electrical contact includes a retention portion, a soldering portion extending from the retention portion, a first arm and a second arm extending upwardly from the retention portion and beside each other. The first arm has a beam section, a curved section and a free end. The second arm includes a leg section and a curved contacting section. The free end and the curved contacting section cooperate with each other to press therebetween and electrically connect with a pin of an electronic package received on the cover. However, the first arm has only one curved section that it makes a cut-off section of the material contacting with the inserted pin of the CPU. The pin of the CPU is easily scraped by the cut-off section because of the cut-off section is rough. After several times of insertion and removal, the pin of the CPU may be damaged and unable to use.
Hence, an electrical connector with a material-saving electrical contact for preventing damage to the pin of the CPU are desired.

Socket connector with improved electrical contact


Aspects of performing single frame backwards playback in a DVD system are described. The aspects include receiving a signal indicating selection of a single frame reverse function. Frame data for a preceding frame of an original playback is then reconstructed while utilizing memory sufficient to support the reconstruction. The reconstructed frame data of the preceding frame is then displayed.

The DVD (Digital Versatile Disk) format was designed by various members of the consumer electronics industry as a means of storing high quality audio-video content (e.g., a feature length film) on a single disk. To facilitate such efficient storage, the DVD format uses contemporary compression technologies to reduce the sizes of the video and audio bit streams comprising the content.
The DVD format employs the ISO MPEG-2 standard to compress video. MPEG-2 represents video content as a compressed series of frames. Each frame is a rectangular array of picture elements (pixels) depicting the content at a particular instant in time. Thus playback consists of decompressing and then displaying this series of frames.
In conventional DVD players, the playback of DVD content is typically implemented in one of three ways: using dedicated hardware, using a software implementation, or using a combination of software and hardware. The most common or conventional implementation takes the form of a consumer electronics components with limited resources targeted exclusively at DVD playback. Less common or conventional implementations take the form of PC-based implementations or Game Consoles (e.g., Sony PLAYSTATION2 and Microsoft X-BOX) which, because they target multiple functions, tend to have more extensive resources.
Although the user primarily plays DVD content forwards and at the display rate of the original content, there are circumstances where a user may want to display frames either backwards or at a rate other than the normal display rate or both backwards and at a rate other than the normal display rate. These include playback features popularized by VCRs, e.g., slow motion, backwards play, single frame stepping forwards and backwards, as well as fast forward and rewind at various rates. The realization of alternate forms of playback, however, is hindered by both the nature of MPEG-2 compression and of typical DVD players.
The MPEG-2 video standard employs three types of compressed frames: intra-frames (I-frames), predictive frames (P-frames), and bi-directionally predictive frames (B-frames). I-frames have no dependencies. Thus, an I-frame is self-contained and includes all information necessary to reproduce the associated original frame. P-frames may have forward dependencies, i.e., a P-frame is not self-contained. It may re-use information from the preceding decompressed reference frame (where a reference frame is either an I-frame or another P-frame). Thus, a playback implementation must decode reference frame preceding a P-frame before it decodes the P-frame itself and must keep the preceding reference frame resident in memory throughout the decoding of a P-frame. For the B-frames, B-frames are not self-contained and may have forward and backward dependencies, such that it may re-use information from either the preceding or the subsequent decompressed reference frame. Thus, a playback implementation must decode the reference frames both preceding and following a B-frame before it decodes the B-frame itself and must keep both the preceding and subsequent reference frames resident in memory throughout the decoding of a B-frame.
In summary, a playback implementation respects the dependencies between frames by decoding a frame's references before decoding the frame itself. It also keeps the required references in memory until all frames requiring the references are decoded.
Normally, a playback implementation maintains four frame buffers (i.e., arrays of memory) of MPEG-2 video at any one time:
(1) currently decoded frame
(2) forwards reference. The reference preceding the currently decoded frame. Sometimes co-incident with the currently displayed frame.
(3) backwards reference. The reference following the currently decoded frame.
(4) currently displayed frame. This is distinct from the currently decoded frame to prevent the player from updating a frame while it is being displayed which causes an undesirable visual artifact called "tearing".
The maintenance of only four or five frame buffers helps to limit the memory resources used in a DVD player, while providing sufficient forwards playback. Four (or even five) frames, however, is normally not sufficient for smooth backwards playback of MPEG-2. Rather, DVD players currently avoid decoding P or B frames when playing backwards, and only decode the self-contained I-frames. This leads to decoding less than 10% of the frames and subsequently to jerky, low frame-rate, backwards play. Further, decoding only the I-frames prevents DVD players from single stepping frames backwards. While an implementation could repeat a process of starting from the last I-frame and progressing forward using only four frames, the process is laborious, requiring repetition for every new backwards frame at the normal playback speed, which requires decoding capacity far in excess of even current PC-based implementations.
Furthermore, most DVD players output to televisions or other displays with fixed display rates. For instance, the PAL and NTSC television standards mandate display rates of 25 and 29.97 frames per second. This is sufficient for normal speed playback which is limited, by the DVD standard, to PAL and NTSC rates. This limitation, however, prevents higher frame rate display during fast forward or rewind. For instance, if the player produces 60 frames of video per second in a 2× fast forward mode only 30 (i.e., every other frame decoded) may be displayed on an NTSC television. Further, given fixed frame rates, these players cannot smoothly vary the rate in a transition from one rate (say normal speed) to another (say 2× speed).
Accordingly, what is needed are a system and method for smooth rewind, single frame stepping backwards, and smooth search transitions in a DVD implementation. The present invention addresses such a need.

Method and system for DVD single frame stepping backwards