The present invention provides an overpower-protection circuit and a power supply apparatus having the same. The power supply apparatus comprises a rectifier, a transformer and an overpower-protection circuit The overpower-protection circuit comprises a converter having a converter input electronically coupled to the rectifier and a converter output, a photo coupler having at least a first terminal coupled with the converter output, and having an output terminal, and a clipper electrically coupled across said terminals of the photo coupler for keeping the converter output below a predetermined voltage.

Nowadays, electronic devices such as DVD players, PCs, and TVs have become absolutely necessary in people's life. However, an unexpected power break in such electronic devices occurs when power supplied to the electrical devices exceeds a threshold value. In order to protect electronic devices from damage by power break, an overpower-protection circuit is usually provided in an electronic device to shut the power down when it exceeds a threshold value. With the power's shutting down, the electronic devices are hung up and not resumed until they are restarted or plugged out/in the power supply. Such a power break not only probably damages the devices, but also scares the users. Especially, when the power break occurs, it might result in undesired data loss in the data processing device such as PCs.
FIG. 1A shows a circuit diagram of the power supply apparatus 1 having a conventional overpower-protection circuit 10.
As shown in FIG. 1A, the power supply apparatus 1 includes a rectifier 12 for rectifying the current from a power supply (AC POWER) 18. A switch transformer 14 is electrically coupled to the rectifier 12 to transform the rectified current from the rectifier 12 into a predetermined current, which is in turn applied to the load 20 via a load protection circuit 108 that is formed of a capacitor C1, a Zener diode ZD1 and resistors R1, R2, R3, and R5.
The power supply apparatus 1 is also equipped with a conventional overpower-protection circuit 10, including a photo coupler 104 and a DC-DC converter 102 providing a switching voltage for the operation of the switch transformer 14. The converter 102 has its first input electrically coupled with the rectifier 12 and second input (pin FB) 102a. The photo coupler 104 is formed of a LED 104a optically coupled to a transistor 104b. The transistor 104b has its collector electrically coupled with second input (pin FB) 102a of the converter 102 and its emitter be grounded.
The LED 104a has its anode electrically coupled with the load 20 via resistor R1 and its cathode electrically coupled with the load 20 too, via capacitor C1 and two resistors R2 and R3, as shown in FIG. 1A.
FIG. 1B shows the circuit of the power supply apparatus 1 in detail. As shown in FIG. 1B, the power supply (AC POWER) 18 has the voltage in a range of 85˜265V and the frequency of 50/60 Hz. The rectifier 12 includes a bridge of diodes BD, which rectifies the current from the power supply (AC POWER) 18 from AC current to DC current, and outputs the rectified current to the switch transformer 14 and to the DC-DC converter 102 via a pair of resistors (R101, R102) coupled in parallel. The switch transformer 14 includes transforming coils T101 for transforming the voltage corresponding to the rectified current from the rectifier 12 into a predetermined voltage, and applying the predetermined voltage to a load 20. In FIG. 1B, the input voltage and current of the load 20 are 12V and 3.5 A respectively. The DC-DC converter 102 is an IC chip of eight pins, whose model number is FAN7554, manufactured by Fairchild Semiconductor Corporation in U.S.A., and available in market since 2003.
FIG. 1C shows the circuit diagram of the FAN7554 as shown in FIG. 1B.
The FAN7554 has many built-in protection circuits that do not need additional components, providing reliability without cost increase. These protection circuits have the auto-restart configuration. In this configuration, the protection circuits reset when Vcc is below UVLO stop threshold (9V) and restarts when Vcc is above UVLO start threshold voltage (15V).
Abnormalities may occur in the SMPS secondary side feedback circuit. First, when the feedback pin is short to the ground, the feedback voltage is zero and the FAN7554 is unable to start switching. Second, when the feedback circuit is open, the secondary voltage generally becomes much greater than the rated voltage as the primary side continues to switch at the maximum current level. This may cause the blowing off the fuse or, in serious cases, fires. It is possible that the devices directly connected to the secondary output without a regulator could be destroyed. Even in these cases, the over voltage protection circuit operates. Since Vcc is proportional to the output, in an over voltage situation, it also will increase. In the FAN7554, the protection circuit operates when Vcc exceeds 34V. Therefore, in normal operation, Vcc must be set below 34V.
An overload is the state in which the load is operating normally but in excess of the preset load. The overload protection circuit can force the FAN7554 to stop its operation. The protection can also operate in transient states such as initial SMPS operation.
Because the transient state returns to the normal state after a fixed time, the protection circuit need not to operate during this time. That is, the FAN7554 needs the time to detect and decide whether it is an overload condition or not. The protection circuit can be prevented from operating during transient states by ensuring that a certain amount of time passes before the protection circuit operates. The above operations are executed as follows: Since the FAN7554 adopts a current mode, it is impossible for current to flow above a maximum level. For a fixed input voltage, this limits power. Therefore, if the power at the output exceeds this maximum, Vo, becomes less than the set voltage, and the KA431 pulls in only the given minimum current. As a result, the photo-coupler's secondary side current becomes zero. The same goes for the photo-coupler's primary side current. Consequently, when the full current 1 mA flows through the internal resistor (2R+R=3R), Vfb becomes approximately 3V and from that time, the 5 uA current source begins to charge Cfb, the photo-coupler's secondary current is almost zero. The FAN7554 shuts down when Vfb reaches 6V.
The pin definitions of the FAN 7554 are listed in the below table.
Pin NumberPin NamePin Function Description1FBInverting (−) input of pwm comparator,on/off control &  OLP sensing terminal.2S/SSoft start3ISNon-inverting (+) input of PWMcomparator, OCL sensing terminal4Rt/CtOscillator time constant(Rt/Ct)5GNDGround6OUTOutput of gate driver7VccPower supply8VrefOutput of 5 V reference
FIG. 2 is a schematic diagram showing the operational principle of power supply apparatus 1 having a conventional overpower-protection circuit 10, as shown in FIG. 1A.
As shown in FIG. 2, P1 represents an expected power and P2 a threshold power from power supply apparatus 1. When P1 does not exceed P2, voltage on the load 20 linearly varies as the current. However, when P1 exceeds P2, as shown in FIG. 2, the overpower-protection circuit 10 works to initiate the overpower protection, bringing the power on the load 20 to zero. This might not only scare the user but also damage the device and/or the data in processing.
To solve the problems, what is needed is an overpower-protection circuit and a power supply apparatus having the same, which can output voltage declines smoothly when current rises continuously, avoiding or eliminating the damage to the devices.

Overpower-protection circuit and power supply apparatus having the same


A viewing system or imaging system is disclosed that includes optical pieces for viewing a subject. The viewing system may include features that allow an augmented mixed view through eyepieces of the viewing system. The mixed view may include graphical representations that are acquired or determined with information separate from the viewing system.

This section provides background information related to the present disclosure which is not necessarily prior art.
During a procedure, such as a procedure viewing the internal portions of an object, various visualization and viewing systems may be used. For example, a microscope or visualization enhancement system may be used to view internal components of an object. The viewing system generally allows for a direct and magnified viewing of the internal component through various optical lenses during a procedure.


A gas turbine engine comprises a fan includes a plurality of fan blades rotatable about an axis. A compressor section includes at least a first compressor section and a second compressor section, wherein components of the second compressor section are configured to operate at an average exit temperature that is between about 1000° F. and about 1500° F. A combustor is in fluid communication with the compressor section. A turbine section is in fluid communication with the combustor. A geared architecture is driven by the turbine section for rotating the fan about the axis.

A gas turbine engine typically includes a fan section, a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-speed exhaust gas flow. The high-speed exhaust gas flow expands through the turbine section to drive the compressor and the fan section. The compressor section typically includes low and high pressure compressors, and the turbine section includes low and high pressure turbines.
The high pressure turbine drives the high pressure compressor through an outer shaft to form a high spool, and the low pressure turbine drives the low pressure compressor through an inner shaft to form a low spool. The fan section may also be driven by the low inner shaft.
A speed reduction device such as an epicyclical gear assembly may be utilized to drive the fan section such that the fan section may rotate at a speed different than the turbine section so as to increase the overall propulsive efficiency of the engine. In such engine architectures, a shaft driven by one of the turbine sections provides an input to the epicyclical gear assembly that drives the fan section at a reduced speed such that both the turbine section and the fan section can rotate at closer to optimal speeds.
Under certain operational conditions, the compressor section of geared turbofan engines can be subjected to high exit temperatures. Although geared turbofan architectures have provided improved propulsive efficiency at high temperatures, turbine engine manufacturers continue to seek further improvements to engine performance including improvements to thermal, transfer and propulsive efficiencies.

This patent is subject to a terminal disclaimer.

Geared turbofan engine with high compressor exit temperature


A sensing system (10) for a vehicle (12) includes a single vision sensor (14) that has a position on the vehicle (12). The single vision sensor (14) detects an object (40) and generates an object detection signal. A controller (16) is coupled to the vision sensor (14) and generates a safety system signal in response to the position of the vision sensor (14) and the object detection signal.

The present invention relates to vehicle sensing systems. More particularly, the present invention relates to a method and system for performing object detection utilizing a single vision sensor.
Various sensing systems currently exist for performing collision warning and countermeasure system operations, such as detection, classification, tracking, and relative distance and velocity estimation of objects within a close proximity of a host vehicle. Sensing systems also exist for performing other sensing system operations, such as occupant related operations and adaptive cruise control operations.
Collision warning and countermeasure system operations include providing a vehicle operator knowledge and awareness of vehicles and objects that are within a close proximity of the host vehicle to prevent colliding with those objects. Countermeasure systems exist in various passive and active forms. Some countermeasure systems are used to aid in the prevention of a collision, others are used to aid in the prevention of injury to a vehicle operator.
Certain collision warning and countermeasure systems are able to sense an object within a close proximity of the host vehicle and warn the host vehicle operator such that the operator can take precautionary steps to prevent a collision or injury. Other collision warning and countermeasure systems activate passive or active countermeasures such as airbags, load limiting seatbelts, or brake control whereby the system itself aids in the prevention of a collision or an injury.
Occupant related operations include the detection of occupant characteristics, the determination of which safety system countermeasures to perform, and the adjustment of deployment or enablement times and rates of the countermeasures. Example countermeasures that may be enabled are seat belt pretensioners and airbags. Occupant characteristics may include occupant positioning within a seat, occupant size, or other known occupant characteristics.
Adaptive cruise control operations include adjusting a host vehicle traveling speed to maintain a safe operating distance between the host vehicle and a target vehicle. Other similar sensing systems also exist, such as lane departure and lane-keeping systems, which monitor lane markers or roadway lane designating lines and provide warnings when the host vehicle is not maintaining travel within a current operating lane.
The various sensing systems may be ultrasonic, radar, lidar, or vision-based. In order to perform each of the various sensing system tasks many of the stated sensors are distributed throughout the host vehicle. Not only does each of the sensors increase vehicle manufacturing and maintenance costs, but in order to perform object detection and assessment multiple sensors are needed.
Also, various techniques have been utilized, such as triangulation, in determining range, velocity, acceleration, and identification of objects in relation to a host vehicle. Typically, two or more cameras are used to determine the stated parameters, potentially further increasing the number of sensors used.
One technique, that is used to reduce the number of sensors within a host vehicle, uses vision sensors and performs optical flow visual image processing to estimate range of a target. In essence the technique infers three-dimensional characteristics from two-dimensional information. Other image processing techniques assume target size, based on a known range of vehicle sizes, and estimate range, based on the assumed size or an apparent two-dimensional size and image pixel intensity. The stated techniques tend to be inaccurate due to the assumptions and estimations contained therein.
Thus, there exists a need for an improved sensing system that decreases the number of sensors to perform object detection and determines object parameters associated with the detected objects. Reduction in the number of sensors can aid in reducing the number of related vehicle components, system complexity, and vehicle manufacturing and maintenance costs.

Single vision sensor object detection system


A wear resistant, heat resistant conveyor chain comprising a series of links, each having a heat resistant roller rotatably fitted onto a bush between inner plates. The links are interconnected in the longitudinal direction of the chain by outer plates, and connecting pins rotatably inserted into the bush. A wear resistant, heat resistant sleeve-shaped spacer protrudes beyond the end surfaces of the heat resistant rollers toward the right and left inner plates to eliminate any sliding contact between the end surface of the heat resistant roller and the inner side surface of the inner plate.

As a conveyor chain used under severe use environment required for heat resistance and the like, a conveyor chain in which a number of link plates are continuously connected to each other through link pins and a roller is attached to said link pin through a bush, characterized in that said bush is composed of stainless steel and said roller is composed of at least a PEEK resin (polyetheretherketone resin) in at least an inner diameter portion, has been known (see, for example, Japanese Laid-Open Patent Publication No. He1. 6-227632 (see column 1, FIG. 3)).
However, in the above-mentioned conveyor chain, a metallic wear powder produced due to sliding contact between an end surface of a roller and an inner side surface of an inner link plate enters between an inner circumferential surface of the roller and an outer circumferential surface of the bush, and such metallic wear powder functions as a polishing agent and generates abnormal one side wear between the roller and the bush. As a result there were troublesome problems in handling of the chain in that a chain wear elongation is not only increased (to markedly decrease the life of the chain) but also the sliding contact sound during a chain operation is markedly increased.
Accordingly, the present invention is made to solve the above-mentioned related art problems; that is, the object of the present invention is to provide a wear resistant, heat resistant conveyor chain, in which chain wear elongation due to one side wear between an inner circumferential surface of a roller and an outer circumferential surface of a bush is significantly suppressed even under environment of a heat resistant operation, so that the life of the chain can be maintained, and in which sliding contact noise between the inner circumferential surface of the bush and the outer circumferential surface of the bush is reduced so that quiet chain operation environment can be ensured.

Wear resistant, heat resistant conveyor chain


An audio segmentation method based on an attention mechanism is provided. The audio segmentation method according to an embodiment obtains a mapping relationship between an “inputted text” and an “audio spectrum feature vector for generating an audio signal”, the audio spectrum feature vector being automatically synthesized by using the inputted text, and segments an inputted audio signal by using the mapping relationship. Accordingly, high quality can be guaranteed and the effort, time, and cost can be noticeably reduced through audio segmentation utilizing the attention mechanism.

To segment an audio, an operation of classifying audio data is required. This operation may be performed manually or may be performed by utilizing unsupervised learning.
However, the audio segmentation by a manual operation requires an expert to mark a point of time for classifying audio data, while directly listening to audio data. Therefore, there is a problem that the effort, time and cost required to perform the manual operation increase.
In addition, the audio segmentation by unsupervised learning may cause a segmentation error to frequently occur and may degrade a quality of a final product.
Accordingly, there is a need for an audio segmentation method which can reduce the effort, time, and cost while guaranteeing quality.

Audio segmentation method based on attention mechanism


An apparatus for driving a tape-shaped optical recording medium, which comprises a supply reel (41) for supplying an optical tape (40), a take-up reel (42) for taking-up the optical tape (40), a friction capstan (43) for driving the optical tape (40) to run to the take-up reel (42) from the supply reel (41) and a running guide member (46) for guiding the optical tape (40) running between the supply reel (41) and the take-up reel (42). The running guide member (46) has a flat portion forming a guide face portion (70) for facing to the optical tape (40) is operative to cause the optical tape (40) to run along the flat portion. Thereby, an area on the guide face portion (70) of the running guide member (46) where an incident position on the optical tape (40) of a light beam is fixed invariably can be stably maintained to be relatively wide.

In the field of information recording on a recording medium and information reproduction from a recording medium on which the information is recorded, under the circumstances wherein recording and reproduction of data representing moving pictures performed with a relatively small-scale recording and reproducing instrument are desired, it is strongly required more than before to have arrangements for recording information on a recording medium with high data density, increasing data rate of information to be recorded on or reproduced from a recording medium and so on. Accordingly, with the intention of meeting such requirements, there has been proposed an optical recording and reproducing technology for causing a single or a plurality of light beams to be incident upon an optical recording medium on which information can be recorded with light so as to record information on the optical recording medium and to reproduce information from the optical recording medium on which the information is recorded.
With the optical recording and reproducing technology, in addition to the advantage that noncontact information recording wherein information is subjected to noncontact recording on an optical recording medium or noncontact information reproduction wherein information recorded on an optical recording medium is subjected to noncontact reproduction from the optical recording medium is carried out, further advantages that a laser light beam is used for recording information on an optical recording medium so that the information is recorded with high data density on the optical recording medium and a plurality of independent laser light beams are used for recording information on and reproducing the information from an optical recording medium so that the data rate of the information to be recorded on or reproduced from the optical recording medium is increased, are obtained. As one of information recording and reproducing apparatus, to each of which such optical recording and reproducing technology as mentioned above is applied, an optical tape recording and reproducing apparatus in which a tape-shaped optical recording medium, namely, an optical tape is used, has been proposed as disclosed in the paper of "Novel digital optical tape recorder", Oakley, William S., LaserTape Inc., SPIE Proceedings Vol. 2604, pp. 256–262.
FIG. 1 shows a light beam controlling and signal processing portion of an example of the optical tape recording and reproducing apparatus proposed previously. In the light beam controlling and signal processing portion shown in FIG. 1, a laser light source 1 is provided for generating continuously a single laser light beam as a parallel light beam. The single laser light beam emitted from the laser light source 1 enters into a beam producing hologram 2.
In the beam producing hologram 2, the single laser light beam which is the parallel light beam emitted from the laser light source 1 is divided into a plurality of laser light beams each being a parallel light beam. That is, the beam producing hologram 2 is operative to produce a plurality of parallel light beams by dividing the single parallel light beam.
The laser light beams obtained from the beam producing hologram 2 enter into a polarized light beam splitter 3 and are reflected from the polarized light beam splitter 3 to be directed downward in FIG. 1 to pass through a quarter wavelength plate 4 and then enter into a converging lens 5. The converging lens 5 is operative to converge the laser light beams having passed through the quarter wavelength plate 4 on a two-dimensional light-modulator 6.
The two-dimensional light-modulator 6 is constituted with a plurality of reflection type light-modulating elements which are arranged two-dimensionally with predetermined spaces. The laser light beams converged by the converging lens 5 come respectively to the reflection type light-modulating elements so arranged two-dimensionally as to form the two-dimensional light-modulator 6. A back surface of each of the reflection type light-modulating elements, which is opposite to an incident surface of the reflection type light-modulator upon which one of the laser light beams is incident, forms a light reflector. Therefore, the laser light beam incident upon each of the reflection type light-modulating elements is reflected from the light reflector in the form of the back surface of the reflection type light-modulator.
In relation to the two-dimensional light-modulator 6, a modulation control signal generator 7 is provided. The modulation control signal generator 7 is operative to produce a plurality of modulation control signals SM corresponding to information which are to be recorded and supply the reflection type light-modulating elements constituting the two-dimensional light-modulator 6 with the modulation control signals SM, respectively. Each of the reflection type light-modulating elements constituting the two-dimensional light-modulator 6 is operative to modulate the laser light beam which is incident thereupon and reflected therefrom in response to the modulation control signal SM. The modulation of the laser light beam in the two-dimensional light-modulator 6 is carried out by varying the reflection amount of the laser light beam at each of the reflection type light-modulating elements in response to the modulation control signal SM. Incidentally, if the modulation control signals SM require, the laser light beam which is incident upon each of the reflection type light-modulating elements constituting the two-dimensional light-modulator 6 is reflected from the reflection type light-modulating elements substantially without being modulated.
As a result of this, the laser light beams which are modulated in response to the modulation control signals SM at and reflected from the reflection type light-modulating elements arranged two-dimensionally with predetermined spaces, respectively, or reflected respectively from the reflection type light-modulating elements arranged two-dimensionally with predetermined spaces substantially without being modulated, are obtained from the two-dimensional light-modulator 6 to be directed to the converging lens 5.
The laser light beams from the two-dimensional light-modulator 6 pass through the converging lens 5 and the quarter wavelength plate 4 to enter into the polarized light beam splitter 3. Since the laser light beams entering into the polarized light beam splitter 3 from the quarter wavelength plate 4 have passed through the quarter wavelength plate 4 twice in the direction to the converging lens 5 and in the opposite direction to the polarized light beam splitter 3, a plane of polarization of each of the laser light beams entering into the polarized light beam splitter 3 from the quarter wavelength plate 4 has been rotated by 90 degrees in comparison with that of each of the laser light beams entering into the polarized light beam splitter 3 from the beam producing hologram 2 and therefore the laser light beams entering into the polarized light beam splitter 3 from the quarter wavelength plate 4 pass through the polarized light beam splitter 3 without being reflected.
The laser light beams thus having passed through the polarized light beam splitter 3 further pass through a quarter wavelength plate 8 and a light beam control optical system 9 to be incident upon an optical tape 10 which is an optical recording medium. The light beam control optical system 9 is operative to subject each of the laser light beams passing through there to the optical tape 10 to focus control for focusing properly each of the laser light beams on the optical tape 10 and tracking control for causing each of the laser light beams to be incident upon a proper position on the optical tape 10. Further, the optical tape 10 is driven by an optical tape driving device not shown in FIG. 1 to run in the direction indicated with an allow T (hereinafter, referred as the T direction).
With the movement of the optical tape 10 in the T direction, a plurality of recording tracks, on each of which information is recorded, are formed on the optical tape 10 along the moving direction of the optical tape 10.
When the laser light beams which have been reflected without being modulated from the two-dimensional light-modulator 6 are incident upon the optical tape 10, these laser light beams are modulated in response to information recorded on the optical tape 10 and simultaneously reflected from the optical tape 10 to be directed to the light beam control optical system 9. The laser light beams obtained from the optical tape 10 pass through the light beam control optical system 9 and the quarter wavelength plate 8 and then enter into the polarized light beam splitter 3. Since the laser light beams entering into the polarized light beam splitter 3 from the quarter wavelength plate 8 have passed through the quarter wavelength plate 8 twice in the direction to the light beam control optical system 9 and in the opposite direction to the polarized light beam splitter 3, a plane of polarization of each of the laser light beams entering into the polarized light beam splitter 3 from the quarter wavelength plate 8 has been rotated by 90 degrees in comparison with that of each of the laser light beams entering into the polarized light beam splitter 3 from the quarter wavelength plate 4 and therefore the laser light beams entering into the polarized light beam splitter 3 from the quarter wavelength plate 8 are reflected from the polarized light beam splitter 3 to be directed to the right in FIG. 1.
The laser light beams reflected to the right in FIG. 1 from the polarized light beam splitter 3 enter into a light beam splitter 11. A part of each of the laser light beams having entered into the light beam splitter 11 is reflected from the light beam splitter 11 to be directed downward in FIG. 1 to pass through an optical element 12, such as a cylindrical lens or the like, and then enters into a focus and tracking detector 13 and another part of each of the laser light beams having entered into the light beam splitter 11 passes through the light beam splitter 11 further to pass through an optical element 14, such as a converging lens or the like, and then enters into a light detector 15.
The focus and tracking detector 13 is operative to produce output signals SF and ST which represent respectively the focus condition and the tracking condition of the laser light beams incident upon the optical tape 10 in response to the laser light beams incident upon the focus and tracking detector 13 through the optical element 12. The output signals SF and ST thus obtained from the focus and tracking detector 13 are used for focus control and tracking control to which each of the laser light beams to be incident upon the optical tape 10 is subjected in the light beam control optical system 9.
The light detector 15 is operative to produce a plurality of output signals SI which vary in response to variations in each of the laser light beams incident upon the light detector 15 through the optical element 14 and supply an information reproducing portion 16 with the output signals SI. The information reproducing portion 16 is operative to reproduce the information recorded on the optical tape 10 based on the output signals SI obtained from the light detector 15.
In the optical tape recording and reproducing apparatus thus shown in FIG. 1, when information is newly recorded on the optical tape 10, the modulation control signals SM which are produced to vary in response to the information to be recorded are supplied from the modulation control signal generator 7 to the reflection type light-modulating elements constituting the two-dimensional light-modulator 6, respectively. As the result, the laser light beams which are modulated in response to the modulation control signals SM by the reflection type light-modulating elements and simultaneously reflected from the reflection type light-modulating elements are obtained from the two-dimensional light-modulator 6 to be directed to the converging lens 5.
The laser light beams modulated in response to the modulation control signals SM and obtained from the two-dimensional light-modulator 6 pass through the converging lens 5, the quarter wavelength plate 4, the polarized light beam splitter 3 and the quarter wavelength plate 8 to enter into the light beam control optical system 9 and then are subjected to the focus control and the tracking control in the light beam control optical system 9 so as to be incident upon the optical tape 10. As a result of this, the recording of the information on the optical tape 10 is carried out with the laser light beams modulated in response to the modulation control signals SM and the recording tracks, on each of which the information is recorded, are formed on the optical tape 10.
When information recorded on the optical tape 10 is reproduced from the optical tape 10 in the optical tape recording and reproducing apparatus shown in FIG. 1, the modulation control signals SM, each of which is predetermined to be constant, are supplied from the modulation control signal generator 7 to the reflection type light-modulating elements constituting the two-dimensional light-modulator 6, respectively. As the result, the laser light beams which are reflected with a constant reflecting amount without being modulated from the reflection type light-modulating elements are obtained from the two-dimensional light-modulator 6 to be directed to the converging lens 5.
The laser light beams having not been modulated and obtained from the two-dimensional light-modulator 6 pass through the converging lens 5, the quarter wavelength plate 4, the polarized light beam splitter 3 and the quarter wavelength plate 8 to enter into the light beam control optical system 9 and then are subjected to the focus control and the tracking control in the light beam control optical system 9 so as to be incident upon the optical tape 10. The laser light beams thus incident upon the optical tape 10 are modulated in response to the information recorded on the optical tape 10 and simultaneously reflected from the optical tape 10 to be directed to the light beam control optical system 9. The laser light beams modulated in response to the information recorded on the optical tape 10 and obtained from the optical tape 10 pass through the light beam control optical system 9 and the quarter wavelength plate 8 and then are reflected from the polarized light beam splitter 3 to enter into the light beam splitter 11. The laser light beams thus entering into the light beam splitter 11 are partially reflected from the light beam splitter 11 to enter into the focus and tracking detector 13 and simultaneously partially pass through the light beam splitter 11 to enter into the light detector 15 through the optical element 14.
As a result of this, the output signal SF which represents the focus condition of the laser light beams incident upon the optical tape 10 and the output signal ST which represents the tracking condition of the laser light beams incident upon the optical tape 10 are obtained from the focus and tracking detector 13 and the output signals SI which vary in response to variations in each of the laser light beams modulated in response to the information recorded on the optical tape 10 are obtained from the light detector 15 to be supplied to the information reproducing portion 16. Then, in the information reproducing portion 16, the information recorded on the optical tape 10 is reproduced based on the output signals SI obtained from the light detector 15.
The optical tape 10 on which the information is recorded or from which the information recorded thereon is reproduced in the optical tape recording and reproducing apparatus shown in FIG. 1, is driven to run by the optical tape driving device.
FIG. 2 shows an example of the optical tape driving device. In the optical tape driving device shown in FIG. 2, a supply reel 21 on which the optical tape 10 is wound to be derived therefrom and a take-up reel 22 onto which the optical tape 10 is wound are provided. The optical tape 10 between the supply reel 21 and the take-up reel 22 is driven by a friction capstan 23 to run in the T direction from the supply reel 21 to the take-up reel 22.
Further, in the optical tape driving device shown in FIG. 2, a plurality of positioning members 24, a pair of tension regulators 25 and a running guide member 26 are provided for causing the optical tape 10 driven by the friction capstan 23 to run stably though a predetermined position. The positioning members 24 determine a running path for the optical tape 10 and tension regulators 25 are operative to provide the optical tape 10 between the supply reel 21 and the take-up reel 22 with predetermined tensile force brought about by springs 27. The running guide member 26 serves for guiding the optical tape 10 so that the laser light beams obtained from a light beam controlling and signal processing portion 28, such as shown in FIG. 1, are incident upon the optical tape 10 on the running guide member 26.
As shown in FIG. 3, the running guide member 26 has a guide face portion 29 facing to the optical tape 10 and a flange portion 30 for restricting the position of the optical tape 10 running thought the guide face portion 29. The guide face portion 29 is formed into a partial cylindrical surface as shown in FIG. 4.
The main function required to be performed by the running guide member 26 in the optical tape driving device mentioned above is to maintain a space between the optical tape 10 and the guide face portion 29 to be extremely small, for example, 10 to 100 nm (nanometer) for stabilizing the position of the optical tape 10 running through the guide face portion 29 so that the incident position on the optical tape 10 of each of the laser light beams obtained from the light beam controlling and signal processing portion 28 is fixed invariably.
However, with the running guide member 26 in the optical tape driving device mentioned above, the optical tape 10 comes into concentrative contact with a portion of the guide face portion 29 which is very narrow in the T direction and extends along the width of the optical tape 10 because the guide face portion 29 is formed into the cylindrical surface as shown in FIG. 4 and therefore the space between the optical tape 10 and the guide face portion 29 which is required to be extremely small, for example, 10 to 100 nm, is formed only on the very narrow portion of the guide face portion 29. This means that an area on the guide face portion 29 where the incident position on the optical tape 10 of each of the laser light beams which are obtained from the light beam controlling and signal processing portion 28 is fixed invariably is limited to be very narrow. Further, the portion of the guide face portion 29 with which the optical tape 10 comes into concentrative contact is subjected to abrasion to be deformed and thereby it is feared that a disadvantage wherein the space between the optical tape 10 and the guide face portion 29 required to be extremely small, for example, 10 to 100 nm, is varied is brought about.
Accordingly, it is an object of the invention disclosed in each of claims of the present application to provide an apparatus for driving a tape-shaped optical recording medium which is provided with running guide means having a guide face portion for facing to a tape-shaped optical recording medium and capable of maintaining continuously a space between the tape-shaped optical recording medium and the guide face portion to be extremely small over a relatively wide area on the guide face portion and thereby is able to maintain stably an area on the guide face portion where the incident position on the tape-shaped optical recording medium of each of laser light beams obtained from a light beam controlling and signal processing portion is fixed invariably to be relatively wide.

Drive apparatus for tape-like optical recording medium


A system and method for performing seismic prospecting and monitoring during drilling of a well are disclosed. The system generates energy, such as acoustic vibrations and electromagnetic energy, at a downhole location and imparts the same into the surrounding earth. The energy may be imparted by the drilling operation itself, or may be generated by a downhole apparatus. Downhole sensors are provided which sense the energy after it has passed through the earth surrounding the wellbore. The sensed energy is either communicated to the surface, or is communicated to a downhole computer for analysis, with the results of the analysis communicated to the surface. Due to the use of both downhole generation and sensing of the energy, high frequency energy may be used. As a result, the resolution of the resulting survey is improved over techniques which utilize surface detectors for energy traveling through the earth.

While the drilling of wells for the production of hydrocarbons, such as oil and natural gas, has always been quite expensive, even more attention has been paid to drilling costs in recent years. This is due in part to the increasing depth and difficulty of location of remaining hydrocarbon reserves, considering that many shallow and large reservoirs have already been heavily exploited. As drilling costs increase at least linearly with the depth of the well being drilled, newer wells are becoming increasingly expensive. Drilling in hostile surface or sub-surface environments increases the drilling costs. Furthermore, the volatility of prices in the oil and gas markets in recent years has reduced operating profit margins, and thus has placed significant pressure on producers to drill only where the likelihood of paying production is high.
Faster and more efficient drilling, in distance drilled per unit time, is of course highly desired to contain these costs. However, overpressurized sub-surface zones present significant problems to drilling in many locations, as drilling into such a zone causes a blow-out if the pressure of the hydrocarbon (generally natural gas) in the zone exceeds the pressure in the wellbore to such an extent that the hydrocarbon explodes out of the well. In locations where overpressurized zones are expected, drilling must be performed using heavy drilling mud to increase the pressure in the wellbore to hold the hydrocarbon in the overpressurized zone in place when the zone is reached. As is well known in the art, however, drilling with such heavier muds is significantly slower than drilling with lighter muds. Due to the limited accuracy with which conventional seismic surveys can predict the depth of such zones, heavy mud is used over relatively long distances to provide sufficient safety margin. As a result, drilling efficiency is significantly impacted by such conventional drilling and exploration techniques.
In addition, while the use of heavy muds reduces the likelihood of a blow-out, excessively heavy mud used during drilling can damage surrounding formations if the mud pressure is significantly greater than the so-called pore pressure in the earth. Therefore, the weight of the drilling mud has both an upper and a lower limit, outside of which drilling failure can occur.
Inaccuracies in the conventional surface geophysical surveys of course also add uncertainty to the success of the well in reaching any hydrocarbon reservoir. Particularly in many regions of the earth where exploration is currently taking place, reservoirs are limited in size, or may have a narrow cross-section in the plan view. A well drilled according to a conventional survey may narrowly miss the reservoir, where small deviations in the drilling direction would have resulted in success for the well.
For these and other reasons, it is therefore beneficial to acquire accurate information about the physical properties of the formations being drilled during the drilling operation, particularly concerning formations which are ahead of the drill bit. Such information can supplement that which was previously acquired by conventional surface geophysical surveys, and allow for control of the drilling to adjust for any differences between previously acquired information and the actual formations encountered. Furthermore, it is also beneficial to acquire accurate real-time information concerning certain drilling parameters, such as weight-on-bit, RPM, direction of the drill bit, and the like. This information, particularly in combination with surface survey information and information acquired during the drilling about the formations through which drilling has taken place and also into which drilling is about to take place, can allow for intelligent drilling, with parameters modified and adjusted on a real-time basis for maximum efficiency and the highest chances for successful production therefrom. The ability to acquire and utilize this type of real-time data is the goal of the invention described hereinbelow.
By way of background relative to the current state of the art, one type of exploration while drilling method which is known in the art is the "TOMEX" method presently offered by Western Atlas International, Inc. According to this method, energy imparted into the earth by the drill bit, during the drilling operation, is considered as the source energy for seismic surveying, with reflections of this source energy detected by geophones deployed at surface locations away from the drilling location. The "TOMEX" survey method is described in numerous publications, including Rector III, et al., "Extending VSP to 3-D and MWD: Using the drill bit as downhole seismic source", Oil and Gas Journal, (Jun. 19, 1989), pp. 55-58, and in Rector, Marion and Widrow, "Use of Drill-Bit Energy as a Downhole Seismic Source", 58th International Meeting of SEG, paper DEV 2.7, pp. 161-164, U.S. Pat. Nos. 4,363,112 and 4,365,322, and PCT publication WO 88/04435.
However, certain limitations are believed to be present relative to the use of downhole seismic sources in conjunction with surface receivers, such as in the "TOMEX" survey method. Firstly, due to the distance traveled by the seismic energy through the earth, only relatively low frequency (and long wavelength) energy is useful. As a result, the resolution of such surveys is necessarily limited. Secondly, it is quite difficult to obtain an accurate source signature, or pilot signal, from vibrations transmitted along the drill string from the bit to the surface. For example, in the "TOMEX" survey where the source signal is detected by monitoring drill string vibrations, noise of significant amplitude couples into the source vibrations detected at the surface, making determination of the source signature (for purposes of later correlation with the geophone-detected vibrations) difficult and inaccurate. Such difficulties with the noise in drill string vibrations are described in copending application Ser. No. 564,621, filed Aug. 8, 1990, assigned to Atlantic Richfield Company and incorporated herein by reference, in J. P. DiSiena et al., "VSP While Drilling: Evaluation of TOMEX", Exploration Technology Reiort (Atlantic Richfield Company, Fall 1989), pp. 13-20, and also in U.S. Pat. No. 4,954,998.
By way of further background, other known analysis methods utilize energy that is generated downhole (for example by the drill bit) and detected at the surface, besides that described hereinabove for seismic surveying. For example, the vibrations in the drill string which are generated by the interaction of the drill bit with the formation can be detected at the surface and analyzed to provide real-time monitoring of drilling conditions and parameters. U.S. Pat. No. 4,715,451, issued Dec. 29, 1987, assigned to Atlantic Richfield Company and incorporated herein by reference, describes a method and system for monitoring drilling parameters by way of spaced apart subs at the upper end of the drill string, such subs including accelerometers and strain gauges. The monitored parameters include axial and torsional loading on the drill bit, axial and torsional drillstring vibrations, and bending modes of the drillstring.
By way of further background, other "measurement-while-drilling", or "MWD", techniques utilize downhole sensors of various parameters, in combination with one of several approaches for telemetry of the detected parameters. Various examples of such approaches are described in Honeybourne, "Measurement While Drilling", Symposium on the 75th Anniversary of the Oil Technology Course at the Royal School of Mines (1988), particularly relative to mud pulse telemetry.
U.S. Pat. No. 4,992,997, issued Feb. 12, 1991, assigned to Atlantic Richfield Company and incorporated herein by reference, describes a stress wave telemetry system for monitoring downhole conditions during drillstem testing, or during wellbore stimulation or fracturing; this system includes accelerometers or strain gauges mounted onto the drillstem near the surface, for sensing torsional, axial or bending vibrations in the drillstem which may be correlated to downhole conditions. The above-referenced related copending applications Ser. No. 554,022 and 554,030, both filed Jul. 16, 1990, both assigned to Atlantic Richfield Company, and both incorporated herein by this reference, describe another example of a telemetry system, where a transducer disposed within the drill string provides high data rate telemetry from downhole to the surface by way of acoustic axial or torsional vibrations. These techniques communicate data on a real-time basis, without requiring that drilling be stopped as in the case of conventional well log tools and techniques.
By way of additional background, conventional wireline logging tools are used to evaluate the properties of formations surrounding wellbores, in conjunction with drilling operations. These logging tools are lowered into the wellbore periodically in the operation, with the actual drilling and excavation stopping during the logging operation. These downhole logging tools include radioactive and electromagnetic instrumentation, of various types.
A first type of electromagnetic logging tool is the direct coupled, or galvanic, logging tool. An example of a currently available galvanic logging tool are those of the well-known "Laterolog" type, available from Schlumberger. Such galvanic logging tools source a current into the earth from one electrode, for example the upper portion of the drill string, and measure a potential difference with other electrodes in the logging tool. Conventional galvanic logging tools have a relatively shallow depth of investigation (on the order of inches to several feet), as the information of interest is the resistivity of the formation immediately outside of the so-called invaded zone; accordingly, the distance between a potential-measuring electrode and one of the current electrodes is quite small. Logging tools of the Laterolog type include an opposing current, to focus the investigation into the formation within a narrow plane perpendicular to the borehole. The Laterolog principles are also used in "measurement-while-drilling" galvanic tools, such as available as the "FCR" measurement system from EXLOG.
The second type of electromagnetic wireline logging tool is often referred to as an electromagnetic induction tool. In this tool, two coils are lowered into the wellbore, separated along the axial length of the wellbore. One of the coils is energized to produce electromagnetic waves of known frequency and amplitude, and the other coil measures the electromagnetic energy it receives from the first coil, after the waves have traveled through the formation. Analysis of the amplitude attenuation and phase shift of the received waves from the transmitted waves will be indicative of the impedance of the surrounding formation.
In the case of these induction tools, it should be noted that the measurement is directed substantially perpendicular to the axis of the wellbore (at the location of the tool), but only for a limited distance. This is due to the purpose of this tool of determining the local resistivity of the surrounding formation, assuming homogeneity of the formation. The distance of interest from the wellbore is preferably far enough away so that the effects of drilling mud packing into the near-wellbore layer of the formation are minimized, but not far enough away that another formation type is encountered by the waves. Since the logging by this tool assumes (and relies upon) homogeneity of the measured layer, the readings and analysis of the received energy from multiple formation types is undesired. Typical distances over which the waves of interest travel are on the order of 10 feet from the wellbore, in substantially a perpendicular plane therefrom.
"Logging-while-drilling" tools, which provide surrounding formation analysis by monitoring certain types of radioactivity (such radioactive measurements conventional for wireline logging tools) and which apparently may be used during drilling, are known to have been developed by Magnetic Pulse, Inc. The measurements available from this tool include the passive measurements of gamma ray emission from the surrounding formation, including spectral analysis of the gamma ray emission to determine the presence of certain elements in the formation. The tool is also apparently capable of neutron density measurements, as the tool has a neutron source (such as AmBe) and detector, such that the density of the formation can be determined by the number of neutrons detected after back-scattering by the formation to the neutron detector. A Cesium gamma ray source in such a tool is also known, such that density measurements may also be made by detecting gamma ray back-scatter from the formation.
By way of further background, Bradley, et al., "Microprocessor-Based Data-Acquisition System for a Borehole Radar", IEEE Trans. Geoscience & Remote Sensing, Vol. GE-25, No. 4 (IEEE, 1987) describes the use of a downhole radar tool for evaluating the formations surrounding the wellbore. By way of still further background, van Popta et al., "Use of Borehole Gravimetry for Reservoir Characterisation and Fluid Saturation Monitoring", Publication 988 (Shell Internationale Research Maaschappij B. V., 1990) describes a method of measuring secondary gas saturations in a fractured reservoir using borehole gravimetry.
By way of further background, U.S. Pat. Nos. 4,929,896, 4,906,928, 4,843,319, 4,839,593 and 4,929,898, all assigned to Atlantic Richfield Company and all incorporated herein by reference, describe systems for the measurement of the thickness of a conductive container, such as a pipe, by way of current induction. This method is commonly referred to as transient electromagnetic probing, or "TEMP". In these systems, a transmitting antenna generates a magnetic field, which in turn produces eddy currents in the conductive container being measured. These eddy currents produce a magnetic field, which is measured by a receiving antenna. The rate of decay of the measured current corresponds to the rate of decay of the eddy currents in the container being measured, which corresponds to the thickness of the conductive walls or coating of the container. Accordingly, these systems allow for non-contact measurement of the thickness of containers such as petroleum pipelines, so that the effects of corrosion may be monitored.
It is an object of this invention to provide a method and system for obtaining accurate seismic data, with high spatial resolution, which looks ahead of the drill bit during the drilling operation into nearby formations.
It is a further object of this invention to provide such a method and system which utilizes acoustic vibrations generated by the drill bit as the source for such data.
It is a further object of this invention to provide such a method and system which utilizes electromagnetic energy, both DC and induction, generated downhole.
It is a further object of this invention to provide such a method and system which can detect approaching overpressurized zones, so that drilling efficiency may be maximized by use of heavier drilling muds only in those regions at and near such overpressurized zones.
It is a further object of this invention to provide such a method and system which can provide for optimized casing design, relative to the heavy weight mud which must be used once such an overpressurized zone is reached.
It is a further object of this invention to provide such a method and system which includes downhole sensors of downhole-generated source energy, to provide for improved accuracy in the resulting data analysis.
It is a further object of this invention to provide such a method and system which includes high data rate telemetry for communication of the downhole sensed energy, to provide improved resolution look-ahead analysis.
It is a further object of this invention to provide such a method and system which includes downhole computing capability sufficient to provide real-time analysis of the downhole-sensed information, such that the results of the analysis can be communicated to the surface with even relatively low data rate telemetry.
It is a further object of this invention to provide such a method and system which utilizes downhole computing capability of sufficient performance as to allow conventional low data rate downhole-to-surface telemetry to communicate the results.
It is a further object of this invention to provide such a method and system which includes spaced apart downhole sensors for purposes of reduction of noise, and so that the resulting analysis can determine the location of certain sub-surface structures.
It is a further object of this invention to provide such a method and system which can provide information regarding the temperature and pressure near the bottom of the wellbore at data rates high enough so that pressure dynamics of flow and reservoir recovery can be used to assist in characterization of the reservoir.
It is a further object of this invention to provide such a method and system which can provide information regarding wellbore pressure, time rate of change of pressure, and pH of the surrounding fluid, in order to monitor the progress of acid treatment completion of oil and gas wells, and in order to monitor the extent of formation fracturing in completing oil and gas wells.
It is a further object of this invention to provide such a method and system which provides real-time drilling parameter monitoring capability in an improved manner.
It is a further object of this invention to provide such a method and system which can detect the presence of faults and interfaces which are at angles other than perpendicular to the direction of drilling.
It is a further object of this invention to provide such a method and system which can monitor parameters of formations through which drilling has already taken place, and to use this monitored information in providing a survey relative to formations into which drilling has not yet taken place.
It is a further object of this invention to provide such a method and system which utilizes spaced apart detection locations along the drill string so that drillstring interaction and distributed operator response characteristics can be measured.
Other objects and advantages of this invention will be apparent to those of ordinary skill having reference to the following specification together with the claims.

Method for executing an instruction where the memory locations for data, operation to be performed and storing of the result are indicated by pointers


A computer system is formed using a right angle processor connector assembly and a right angle add-on card connector. The right angle processor connector assembly includes a right angle processor connector and a complementary support member. Each of the right angle processor package and add-on card connectors includes an L-shaped body having an inner cavity defined a number of inner walls extending from one end to the other end. Each connector is mechanically attached to a motherboard, upside down and in a direction orthogonal to the motherboard. Each connector receives its constituent component (i.e. the processor package or the add-on card) through one end, with the constituent components and the motherboard occupying parallel planes. Each connector further includes a number of L-shaped pins disposed on the inner walls extending from one end through the other to electrically couple the constituent component to the motherboard. The processor connector further includes bracing features that cooperate with like features of the complementary support member to support the processor package.

1. Field of the Invention
The present invention relates to the field of computer systems. More specifically, the present invention relates to the art of coupling a processor and add-on cards to a motherboard of a computer system.
2. Background Information
Microprocessor based personal computers are known in the art, including personal computers employing low profile form factors. Conventional low profile personal computers employ a riser card to facilitate coupling of an add-on card to a motherboard. The add-on card and the motherboard occupy parallel planes (as oppose to orthogonal planes in the case of the AT form factor), to provide the low profile. [Note that the AT form factor includes the desktop as well as the tower variation, where one is basically a 90 degree rotation of the other.] Conventional low profile personal computers suffer from a number of disadvantages. One of these disadvantages is the inability to place high performance components on the add-on cards, as the distance to the motherboard is too far to meet the signal requirements of the high performance components. An example of such high performance component is a Peripheral Component Interconnect (PCI) agent. Thus, an alternate approach that can achieves the low profile and at the same time accommodates the signal requirements of high performance components is desired.
Additionally, low profile personal computers traditionally have employed zero insertion force (ZIF) sockets to couple processors to the motherboards. Historically, the manner in which processors are coupled to the motherboards has not been an issue that needs to be addressed in achieving low profile, as the processors generally have a very low profile. However, recent advances in microprocessor have led to certain high performance microprocessors to employ a "cartridge" approach to packaging, and single edge card connector (SECC) technology to connect the processor packages to the motherboards. Because of the high performance nature of these processors, typically heat sinks with substantial masses have to be employed to dissipate the heat generated by these processors. The first generation SECC processor packages are coupled to the motherboards with the two components occupying orthogonal planes, as a result constraining the low profile that can be achieved. Thus, a new non-orthogonal approach to coupling these new high performance SECC processor packages and motherboards is desired.

Computer system including right angle processor and add-on card connectors


Apparatus and method of recording coded picture data on a recording medium which operates to receive the picture data (e.g., a video data), code the picture data using intra-picture coding and/or predictive coding to provide one I-picture and one succeeding P-picture, generate positional information representing the positions of the I-picture and the P-picture relative to the I-picture, and record the I-picture, the P-picture, and the positional information on the recording medium. The coded picture data is reproduced from the recording medium in a special reproduction mode by selectively reading the data using the positional information.

The present invention relates to a data coding method and apparatus capable of coding video and audio data for special reproduction, to a data decoding method and apparatus for reading recorded video and audio data from an optical disk, a magnetic disk or the like and reproducing the read data in a special mode, and further relates to a recording medium where coded data is recorded in a manner so as to be reproducible in a special mode.
Digital picture signals or the like to be recorded on a disk in a digital video disk (hereinafter referred to as DVD) system, are compressed and coded using the MPEG (Motion Picture coding Experts Group) method.
FIG. 14A is a schematic representation of the structure of inter-frame prediction structure used in the MPEG system. In this example, one GOP (Group of Pictures) is composed of, e.g., fifteen frames, which include one frame of an I-picture (intraframe encoded picture), four frames of P-pictures (forward interframe prediction encoded pictures), and the remaining ten frames consisting of B-pictures (forwarded and backward, bidirectional prediction encoded pictures).
As used herein, the I-picture is an intra-picture coded picture in which either one frame or one field is data compressed using intra-frame or intra-field coding consistent with the MPEG system; the P-picture is an inter-picture forward predictive coded picture in which either a frame or a field is compression encoded using inter-frame or inter-field coding with reference to the temporally preceding frame or field (I-picture or P-picture) already coded; and the B-picture is a bidirectionally predictive coded picture in which either a frame or a field is compression encoded using inter-frame or inter-field coding with reference to the temporally preceding and succeeding frames or fields.
More specifically, as indicated by arrows in the diagram, an I-picture I.sub.0 is coded by intra-frame processed by itself and without references to any other frame; a P-picture P.sub.0 is coded by inter-frame prediction with reference to the I-picture I.sub.0 ; and a P-picture P.sub.1 is coded by inter-frame prediction with reference to the P-picture P.sub.0. Further, B-pictures B.sub.0, and B.sub.1 are coded by inter-frame prediction with reference to both the I-picture I.sub.0 and the P-picture P.sub.0 ; and B-pictures B.sub.2 and B.sub.3 are coded by inter-frame prediction with reference to both the P-picture P.sub.0 and the P-picture P.sub.1. Similarly, subsequent pictures are coded by such prediction in the manner indicated by arrows.
In decoding the predictive-coded pictures mentioned, the I-picture is decoded alone since it is not coded with reference to any other frame. However, a preceding I-picture or a preceding P-picture is required to decode a given P-picture because a P-picture is predictive-coded with reference to the temporally preceding I-picture or P-picture. Similarly, preceding and succeeding I-pictures or P-pictures are required to decode a given B-picture because a B-picture is coded with reference to the temporally preceding and succeeding I-pictures or P-pictures.
For this reason, to provide proper decoding, positions of the pictures on a record medium are changed from FIG. 14A to the positions illustrated in FIG. 14B so that the pictures required for decoding are decoded in advance.
As illustrated in the diagram, such positional changes are made so that the I-picture I.sub.0 precedes the B-pictures B.sub.-1 and B.sub.-2 since the I-picture I.sub.0 is required to decode the B-pictures B.sub.-1 and B.sub.-2 and also the position of the P-picture P.sub.0 is changed to precede the B-pictures B.sub.0 and B.sub.1 since the decoding of B-pictures B.sub.0 and B.sub.1 requires the I-picture I.sub.0 and the P-picture P.sub.0. Similarly, other pictures are positionally changed so that the P-picture P.sub.1 precedes the B-pictures B.sub.2 and B.sub.3 since the P-pictures P.sub.0 and P.sub.1 are required to decode the B-pictures B.sub.2 and B.sub.3, and also the P-picture P.sub.2 precedes the B-pictures B.sub.4 and B.sub.5 since the decoding of the B-pictures B.sub.4 and B.sub.5 requires the P-pictures P.sub.1 and P.sub.2. In the same manner, positional changes are made so that the P-picture P.sub.3 precedes the B-pictures B.sub.6 and B.sub.7.
The video data composed of the I-picture, P-pictures and B-pictures arranged in the order of FIG. 14B, and other data including audio data and subtitle (captions) data, are packetized (multiplexed) and recorded on a recording medium such as a disk or are transmitted on a transmission channel. The code quantity of each frame in the picture data is not fixed among pictures and depends on the complexity or flatness of the individual picture. Typically, an I-picture is represented by more data than a P-picture which is represented by more data than a B-picture.
FIGS. 15A to 15C show one example of how the data is packetized. In these diagrams, FIG. 15A represents an MPEG2 system stream which is multiplexed after packetization; FIG. 15B represents the content of a video packet in the multiplexed stream; and FIG. 15C represents an MPEG2 video stream of a video layer.
In each of picture data V, V+1, V+2, . . . and so forth constituting the video layer of FIG. 15C, picture header information and picture coding extension information are affixed at the leading position. In the example shown, a video stream ranging from the position identified as D1 to the position identified as D3 of the video layer forms one video packet with a packet header affixed at its leading position, and a video stream ranging from the position D3 to the position identified as D5 of the video layer forms another video packet with a packet header affixed at its leading position.
Video packets thus packetized are multiplexed with audio packets and subtitle packets to thereby form the MPEG2 system stream shown in FIG. 15A.
FIG. 16 shows the contents of a picture header, and FIG. 17 shows the contents of a picture coding extension.
In the picture header, there are items of information such as a unique picture.sub.-- start.sub.-- code, temporal.sub.-- reference (TR) (which is a time-series serial number given per picture), and picture.sub.-- coding.sub.-- type (I-, P- or B-picture).
In the picture coding extension, there are items of information such as a unique extension.sub.-- start.sub.-- code, a unique extension.sub.-- start.sub.-- code.sub.-- identifier, picture.sub.-- structure, top.sub.-- field.sub.-- first, progressive.sub.-- frame, etc.
As for the picture data, two data structures may coexist: a frame structure where one picture is composed of one frame and a field structure where one picture is composed of two fields. Whether the picture data has a frame structure of one frame per picture or a field structure of two fields per picture can be identified from the following three items of information, i.e., (1) presence of GOP header, (2) temporal.sub.-- reference (TR) in picture header, and (3) picture.sub.-- structure in picture coding extension.
FIG. 18 is a block diagram illustrating one example of data decoding apparatus adapted to perform special reproduction of data, such as slow picture playback, fast playback, reverse playback and the like. An optical disk 1 is rotatable by a spindle motor (not shown) at a predetermined rotation rate, and a laser beam is projected from a pickup 2 to a track on the optical disk 1, so that the MPEG compressed digital data recorded on the track is read therefrom. The digital data is processed by a demodulator circuit 3 which demodulates eight to fourteen modulation (EFM) and supplied to a sector detection circuit 4. The output of the pickup 2 also is supplied to a phase-locked loop (PLL) circuit 9, where a clock signal is reproduced and supplied to the demodulator circuit 3 and to the sector detection circuit 4.
The digital data recorded on the disk 1 includes multiplexed streams recorded in units of a fixed-length sector, with a sector sync and a sector header affixed to the beginning of each sector. The sector detection circuit 4 detects each of the sectors from the sector sync and the sector address from the sector header; and this information is supplied to a control circuit 6.
The demodulated digital data is supplied via the sector detection circuit 4 to an ECC (error correction) circuit 33 which executes error detection and correction. The ECC circuit 33 supplies error-corrected data to a ring buffer 5 to be written therein under control of the control-circuit 6.
The output of the ECC circuit 33 also is supplied to a stream detector 50, which determines the picture type from the data stream picture header read from the disk 1 in a special reproduction mode and then supplies picture type information to the control circuit 6. In response to this information, the control circuit 6 executes its control operation in such a manner that, in the special reproduction mode, the data of the I-picture and the data of the succeeding two P-pictures are written in the ring buffer 5.
A focus control circuit (not shown) and a tracking servo circuit 8 control focusing and tracking of the pickup 2, respectively, under the control of a system controller (not shown) in response to a focus error signal and a tracking error signal obtained from the information read by the pickup 2.
In accordance with the sector address of each sector detected by the sector detection circuit 4, the control circuit 6 designates, by a write pointer WP, a write address for writing the corresponding sector in the ring buffer 5. Moreover, in accordance with a code request signal obtained from a video code buffer 10 (FIG. 18B), the control circuit 6 further designates, by a read pointer RP, a read address of the data written in the ring buffer 5. The control circuit 6 is adapted to read the data from the position of the read pointer RP and supplies the read data to a demultiplexer 32.
Since the coded data recorded on the disk 1 comprises multiplexed video, audio and subtitle data, the demultiplexer 32 separates the data read thereto from ring buffer 5 into the video data, the audio data and the subtitle data, and then supplies the respective data to a video decoder 20 (FIG. 18B), an audio decoder (not shown), and a subtitle decoder (not shown). The video decoder 20 stores the video data in the video code buffer 10.
Thereafter, the data stored in the video code buffer 10 is supplied to a picture header detector 34 which detects the picture header. The detected picture header information is further used to identify the picture type (I, P or B picture) of the video data and the temporal reference (TR) which signifies the frame order in the GOP. A picture data selection circuit 35 selects only the I-picture and the P-picture as identified by the picture type information supplied from the picture detector 34 in the special reproduction mode, and supplies the selected picture data to an inverse VLC (variable length coding) circuit 11. In a normal reproduction mode, the picture data selection circuit 35 is controlled to deliver all of the picture data to inverse VLC circuit 11 without any pre-selection.
The data supplied to the inverse VLC circuit 11 is processed using inverse VLC; and then is supplied to a dequantizer 12. Code request signals are returned to the video code buffer 10 from the inverse VLC circuit to permit new data to be transferred from the video code buffer 10.
Further, the inverse VLC circuit 11 outputs a quantization step size to the dequantizer 12 and outputs motion vector information to a motion compensator 15. The quantization step size and motion vector information are included with the video data. The dequantizer 12 dequantizes the input data in accordance with the designated quantization step size and outputs the dequantized data to an inverse DCT (discrete cosine transform) circuit 13. The inverse DCT circuit 13 processes the dequantized data using inverse DCT to recover video information, and supplies the recovered video information to an adder 14.
The adder 14 adds the output of the inverse DCT circuit 13 and the output of the motion compensator 15 in accordance with the picture type (I, P or B) and supplies the result, i.e., motion-compensated video data, to a frame memory bank 16.
Thereafter, the data read from the frame memory bank 16 is rearranged in the original frame order (as shown in FIG. 14A by switch 16E). The rearranged data is supplied to a digital-to-analog (D/A) converter 17 which converts the data into an analog video signal to be displayed on a display device 18.
Returning to FIG. 18A, the output of the ECC circuit 33 is supplied to a stream detector 50 which detects the picture type from the stream data read from the disk 1 and supplies the picture type information to the control circuit 6. In response to this information, the control circuit 6, in the special reproduction mode, writes into the ring buffer 5, the data of the I-picture and the succeeding two P-pictures.
Accordingly, three frames corresponding to the I- and two P-pictures at the beginning of each GOP are written at high speed into the ring buffer 5, and this data can be acquired and decoded by the decoder 20 at any desired timing, thereby enabling efficient decoding of data in the special reproduction mode.
For example, suppose that a reverse reproduction is started with the P-picture P.sub.3 of the original frame order shown in FIG. 14A. It is necessary to display the decoded pictures in the following order:
P.sub.3 .fwdarw.B.sub.7 .fwdarw.B.sub.6 .fwdarw.P.sub.2 .fwdarw.B.sub.5 .fwdarw.B.sub.4 .fwdarw.P.sub.1 .fwdarw.B.sub.3 .fwdarw.B.sub.2 .fwdarw.P.sub.0 .fwdarw.B.sub.1 B.sub.0 .fwdarw.I.sub.0 .fwdarw.. . .
However, since each P-picture is coded by inter-picture prediction as described, the pictures I.sub.0, P.sub.0, P.sub.1 and P.sub.2 need to be decoded before decoding the P-picture P.sub.3. Similarly, the P-pictures P.sub.2 and P.sub.3 need to be decoded prior to decoding the B-picture B.sub.7. Therefore, if reverse reproduction is to be performed by decoding each picture merely once, as in normal reproduction, it becomes necessary to employ a frame memory bank 16 of great capacity which is capable of storing as many frames as there are pictures constituting a GOP.
The storage capacity of the frame memory bank 16 must be increased beyond what is required in a normal reproduction mode to meet such requirement. Further, the decoded data must be sequentially stored in the frame memory bank to deliver the pictures in the proper order of reverse reproduction.
Although other techniques of reverse reproduction may be adopted to perform merely with the I- and P-pictures thus skipping the B-pictures, the necessity of storing more frames than what is required for normal reproduction still exists.
For this reason, the data decoding apparatus of FIG. 18 operates to perform reverse reproduction using the same frame memory bank as utilized in normal reproduction, i.e., using three memory elements in the example of FIG. 18 to store one I-picture and two temporally succeeding P-pictures. The stream detector 50 provided for this purpose writes the I-picture and the two succeeding P-pictures in the ring buffer 5. However, this makes the construction and operation of the steam detector 50 for detecting the I-picture and the two succeeding P-pictures more complicated.
FIG. 15A shows the packetized (multiplexed) MPEG2 system stream. When a packet of the MPEG2 video stream is defined at a position D3 as shown in FIG. 15C during the packetization process, the picture header and the picture coding extension of the picture data (V+2) are spread over two packets, as shown in FIG. 15B.
If the picture header and the picture coding extension are spread over two video packets, it becomes necessary to detect two video packets to obtain the requisite items of information of the picture. Further, and as shown in FIG. 15A, another packet (e.g., audio packet) may exist between the two video packets to complicate the detection process, thereby complicating the construction and operation of the stream detector 50.
According to the MPEG2 technique, video data in a frame structure where one picture is composed of one frame, and video data in a field structure, where one picture is composed of two fields, can be intermingled. Since a picture header is affixed to every field, the picture headers and the picture coding extensions of two consecutive pictures must be read to determine the data structure of the video data.
Therefore, a determination is made to ascertain whether the picture data is formed in the frame structure or the field structure on the basis of the aforementioned three items of information, i.e., (1) presence of GOP header; (2) temporal reference (TR) in the picture header; and (3) picture.sub.-- structure information in picture coding extension.
A detailed explanation will be given below with regard to a method of differentiating between a frame structure and a field structure.
FIGS. 19A and 19B show video data in the field structure and frame structure formats, respectively. In the field structure format, one frame of video data is composed of two fields of picture data, to each of which are affixed a picture header and a picture coding extension. In the frame structure format, one frame of video data is composed of one frame of picture data to which a picture header and a picture coding extension are affixed.
In the field structure format, the numerical values of the TR information in the respective picture headers of the picture data pair are set equal to each other. The picture.sub.-- structure information in the picture coding extension is "01" and "10" for Top Field and Bottom Field, respectively, as shown in FIG. 20. Further, the picture.sub.-- structure information in the picture coding extension of the frame structure is "11" as shown in FIG. 20.
The format (field or frame structure) of the picture data may be ascertained by first reading the GOP header at the GOP start position and then reading the picture.sub.-- structure information of the picture coding extension at the beginning of that picture data.
Although the picture data in the frame structure can be loaded into the ring buffer 5 (FIG. 18A) by detecting a single frame, it is difficult to similarly load the video data in the field structure, where a pair of picture data constitutes one frame of video data, because the paired picture data must be detected before it can be properly loaded. Consequently, the TR information in each picture header is read to find two picture data units with numerically equal values of TR. When such a pair is found, they are identified as paired picture data and then are loaded.
The paired field-structure picture headers are arranged in either of two different orders: top/bottom and bottom/top. Such arrangements will now be described with reference to FIG. 21. A GOP header (GOP H), an I-picture of frame structure, a B-picture of field structure, another B-picture of field structure, a GOP header spaced apart therefrom, and an I-picture of field structure, a GOP header, another I-picture of field structure . . . and so forth are sequentially recorded.
For example, where a total of three frames (one I-picture and two succeeding P-pictures) are loaded into ring buffer 5 (FIG. 18A), the I-picture in frame structure next to the top (first) GOP header is detected and identified from the GOP header, the picture.sub.-- coding.sub.-- type in the picture header, and the picture.sub.-- structure information ("11" in the case of frame structure) in the picture coding extension at the beginning of the picture data.
When access is made for playback at the position identified as random access 1 in the bit stream, the picture header and the picture coding extension of the first field-structure B-picture are read out. At this time, the TR expressed as "0" is also read out. Subsequently the picture header and the picture coding extension of the second field-structure B-picture are read out as well as the TR expressed as "0". Since the TR value of the two field-structure B-pictures are equal, they are detected as paired data.
When access is made at the position identified as random access 2 in the bit stream, the picture header and the picture coding extension of the first picture are read along with the TR expressed as "0". Subsequently the picture header and the picture coding extension of the next picture are read out along with the TR expressed as "1". Since the respective numerical values of the TR are not coincident with each other, the data of the two field-structure pictures are not detected as paired data.
If access is made at the position identified as random access 3 in the bit stream, the respective numerical values of the TR in the two picture headers are coincident (TR=1) with each other as in the foregoing case of random access 1, thus the pictures are detected as a pair. If a picture structure in the picture coding extension of "01" or "10" is detected, it is regarded as a field structure, and a paired data is detected.
If access is made at the position identified as random access 4 in the bit stream, the picture header and the picture coding extension of the first picture are read out along with the TR expressed as "0". This picture data is regarded as a field-structure I-picture in accordance with the picture coding type information in the picture header and the picture.sub.-- structure information in the picture coding extension.
After subsequent detection of the GOP header, the picture header and the picture coding extension of the next picture are read out along with the TR expressed as "0". Here, the respective numerical values of the TR of the two consecutive pictures are coincident with each other, but these two pictures are not considered as paired because there exists a GOP header between the two pictures. It should be noted that the TR is reset to "0" if a GOP header exists and no GOP header is interposed between a paired picture.
As described, the stream detector 50 executes a process of detecting various items of information relative to the pictures in accordance with the GOP header, the picture headers, and a plurality of flags of the picture coding extensions, to load the picture data into the ring buffer 5. However, this processing routine is extremely complex making it difficult to construct the stream detector 50.
The manner in which the stream detector 50 detects the completion of the loading process is explained in conjunction with the flow chart shown in FIG. 22. It is assumed in this flow chart that a random access is made to an entry sector written immediately anterior to an I-picture so that a proper picture can be obtained instantly in response to the random access.
At step S10, the stream detector searches for the picture.sub.-- start.sub.-- code in the picture.sub.-- header to detect the picture header of the I-picture and inquiry is made at step S12 to determine whether the picture.sub.-- start.sub.-- code has been detected. If the inquiry at step S12 is answered in the affirmative, that is, if the picture.sub.-- start.sub.-- code is detected, the operation proceeds to step S14. However, if the inquiry at step S12 is answered in the negative, that is, if no picture.sub.-- start.sub.-- code is detected, the process at step S12 is repeated until the picture.sub.-- start.sub.-- code is detected.
At step S14, the temporal reference is read from the detected picture header and its numerical value is stored in a register as TR0.
At step S16, another search (SRCH) for the picture.sub.-- start.sub.-- code in the picture header is made to detect the next picture and inquiry is made at step S18 to determine whether the picture.sub.-- start.sub.-- code has been detected. If the inquiry at step S18 is answered in the affirmative, that is, if the picture.sub.-- start.sub.-- code is detected, the operation proceeds to step S20. However, if the inquiry at step S18 is answered in the negative, the process at step S18 is repeated until the picture-start-code is detected.
Inquiry is made at step S20 to determine whether a GOP header has been detected in the picture start code, thereby to determine if the detected picture data is part of a pair. If the inquiry at step S20 is answered in the negative, that is, if no GOP header is detected, the operation proceeds to step S22. However, if this inquiry is answered in the affirmative, that is, if the GOP header is detected, the operation advances to step S26 because the existence of a GOP header between the picture data eliminates the possibility that these picture units are paired.
When the temporal reference is read from the detected picture header, its numerical value is stored in a register as TR1 as represented by step S22, and the operation advances to the inquiry at step S24 to determine whether the numerical values of the TR stored respectively in the register TR0 and TR1 are equal. If the inquiry at step S24 is answered in the affirmative, that is, if there is a coincidence of the two numerical values, the operation returns to step S16 and the processes discussed above in conjunction with steps S16 to S24 are repeated. It will be appreciated that the coincidence of two numerical values signifies that a picture data pair has been detected.
However, if the inquiry at step S24 is answered in the negative, that is, if the numerical values of the TR are not equal, the operation proceeds to step S26. Here, the picture header of the next picture is detected; and the picture coding type read from the picture header is stored in the register. The operation then advances to the inquiry at step S28 to determine whether the stored picture coding type represents a B-picture. If the inquiry at step S28 is answered in the affirmative, that is, if the detected picture is a B-picture, the operation returns to step S16 because the B-picture is not being sought; and the processes discussed above in conjunction with steps S16 to S28 are repeated to detect the next picture.
However, if the inquiry at step S28 is answered in the negative, that is, if the detected picture is not a B-picture, the temporal reference in the detected picture header is read and its numerical value is stored in the register as TR2, as represented by step S30. It will be appreciated that this detected picture is the first P-picture appearing after the I-picture.
At step S32, another search (SRCH) for the picture.sub.-- start.sub.-- code in the picture header is made to detect the next picture and inquiry is made at step S34 to determine whether the picture.sub.-- start.sub.-- code has been detected. If the inquiry at step S34 is answered in the affirmative, the operation proceeds to step S36. However, if inquiry at step S34 is answered in the negative, that is, if no picture.sub.-- start.sub.-- code has been detected, the process at step S34 is repeated until the picture.sub.-- start.sub.-- code is detected.
Inquiry is made at step S36 to determine whether a GOP header has been detected during the search for the picture.sub.-- start.sub.-- code, thereby to determine if the detected picture data is part of a pair. If the inquiry at step S36 is answered in the negative, that is, if no GOP header is detected, the operation proceeds to step S38. However, if the inquiry at step S36 is answered in the affirmative, that is, if a GOP header is detected, the operation advances to step S42 because the existence of a GOP header between picture units eliminates the possibility that these picture units are paired.
When the temporal reference is read from the detected picture header at step S38, its numerical value is stored in the register as TR3 and the operation advances to the inquiry at step S40 to determine whether a coincidence is attained between the numerical values of the TR stored respectively in the register as TR2 and TR3. If the inquiry at step S40 is answered in the affirmative, that is, if the two numerical values are equal, the operation returns to step S32 and the processes discussed above in conjunction with steps S32 to S40 are repeated. It will be appreciated that the coincidence of two numerical values signifies that a picture data pair has been detected.
However, if the inquiry at step S40 is answered in the negative, that is, if the numerical values of the TR are not coincident, the operation proceeds to step S42 to read the picture type. The operation then advances to the inquiry at step S44 to determine whether the stored picture coding type represents a B-picture. If the inquiry at step S44 is answered in the affirmative, that is, if the detected picture is a B-picture, the operation returns to step S32 because the B-picture is not being sought; and the processes discussed above in conjunction with steps S32 to S44 are repeated to detect the next picture.
However, if the inquiry at step S44 is answered in the negative, that is, if the detected picture is not a B-picture, the temporal reference detected in the picture header is read and its numerical value is stored in the register as TR4, as represented by step S46. It will be appreciated that this detected picture is the second P-picture appearing after the I-picture.
Proceeding to step S48, another search (SRCH) for the picture.sub.-- start.sub.-- code in the picture header is made to detect the next picture and inquiry is made at S50 to determine whether the picture.sub.-- start.sub.-- code has been detected. If the inquiry at step S50 is answered in the affirmative, that is, if the picture.sub.-- start.sub.-- code is detected, the operation proceeds to step S52. However, if the inquiry at step S50 is answered in the negative, the process at step S50 is repeated until the picture.sub.-- start.sub.-- code is detected.
Inquiry is made at step S52 to determine whether a GOP header has been detected during a search for the picture.sub.-- start.sub.-- code, thereby to determine if the detected picture data is part of a pair. If the inquiry at step S52 is answered in the negative, that is, if no GOP header is detected, the operation proceeds to step S54. However, if the inquiry at step S52 is answered in the affirmative, that is, if a GOP header is detected, the loading of the picture data into the ring buffer is completed and the process is terminated.
When the temporal reference is read from the detected picture header and its numerical value is stored in the register as TR5, as represented by step S54, the operation advances to the inquiry at step S56 to determine whether a coincidence is attained between the numerical values of the TR stored respectively as TR4 and TR5. If the inquiry at step S56 is answered in the affirmative, that is, if there is coincidence in the two numerical values, the operation returns to step S48 and the processes discussed above in conjunction with steps S48 to S56 are repeated. However, if the inquiry at step S56 is answered in the negative, that is, if the two numerical values of the TR are not equal, the loading of the picture data is complete and the process is terminated.
Thus, the stream detector 50 can load a bit stream by executing the above processing routine to load an I-picture and two succeeding P-pictures. However, as indicated by its lengthy description, it is quite onerous to execute this complex processing routine.

Data coding/decoding method and apparatus and coded data recording medium