Abstract: A multi-output power supply device (1) comprises a first power supply (10) for outputting a first output voltage (VDCO1); a second power supply (30) for outputting a second output voltage (VDCO3); and a reset circuit (40) for detecting an abnormality of the first output voltage (VDCO1) and for outputting a first reset signal (XRESET) to forcibly stop the output operation of the second power supply (30).

Abstract: The invention provides a method for data recording of an optical disk drive. First, raw data is encoded to obtain a plurality of recording units of encoded data to be stored in a memory. The encoded data stored in the memory is then recorded to an optical disk. A predetermined number of recording units of the encoded data is then reserved in the memory as reserved data without being recorded onto the optical disk. The recorded data read from the optical disk is then compared to the corresponding encoded data stored in the memory to verify correctness of the recorded data. The reserved data is then recorded to the optical disk after correctness verification of the recorded data is completed. Finally, the aforementioned steps are repeated until there is no more raw data left as a source for encoding.

Abstract: A recorded area is reproduced during a suspension of a recording operation; when degradation of the recorded signal is detected (S4, S5) by the signal quality detection means (16), a tilt adjustment is performed in the recorded area, the signal quality of the recorded signal is detected after the tilt adjustment (S6), and if it is still degraded, a recording parameter is altered (step S7). The need to obtain tilt adjustment values for tilt corrections at a plurality of radial positions in advance is eliminated, resulting in reduced apparatus overhead and better recording quality.

Abstract: A method of writing data to and reading data from a storage medium includes cycle slip detection and correction. An LDPC matrix includes a first area for cycle slip detection and correction. The first area satisfies a set of conditions such that a cycle slip at a particular position creates a pattern of parity check errors indicative of the position and polarity of the cycle slip. Writing user data to the storage medium includes encoding the user data with parity data according to the LDPC matrix. Reading the user data and the parity data from the storage medium includes decoding the user data and the parity data according to the LDPC matrix. Decoding includes, upon detecting a pattern of parity check errors indicative of the position and polarity of a detected cycle slip, correcting the detected cycle slip.

Abstract: A disc drive system provides increased reliability by detecting and correcting errors associated with bit-patterned media. Write synchronization errors associated with bit-patterned media are addressed by including data storage for temporarily storing data that is being written to the disc drive. The data is read from both the disc drive and the storage medium and compared to detect write synchronization errors. The disc drive system utilizes the identified write synchronization errors for at least one of timing recovery, equalizer training detection, error correction code application, and error recovery.

Abstract: According to the present invention, a first error pattern caused by a shift of a bit relating to a recording mark or a space of a shortest length and a second error pattern caused by an edge shift of the recording mark are used. For each of a plurality of error patterns, a pattern shift obtained by normalizing a difference between a square of a Euclidean distance between the error pattern and a reproduction signal and a square of a Euclidean distance between a correct pattern and the reproduction signal, using a square of a Euclidean distance between the correct pattern and the error pattern is detected. Length and phase errors are calculated by a sum of, or a difference between, a first pattern shift amount obtained by normalization performed using the first error pattern and a second pattern shift amount obtained by normalization performed using the second error pattern.

Abstract: An optical disc recording device includes: an optical disc device to record optical recording data onto an optical disc; a recording data assigning unit to divide a recording region on the optical disc into multiple divisions, part as a data region, assign optical recording data thereto; a redundancy data calculating unit to calculate redundancy data for restoring recorded data; a redundancy data assigning unit to take divided regions other than the data region as a redundancy region, and assign the corresponding redundancy data thereto; a recording/playing device having a recording capacity greater than the data region; and a recording control unit configured to record optical recording data in the data region and also at least a part thereof in the recording/playing device, cause the recording/playing device to play the optical recording data recorded therein at the time of calculating redundancy data, and record calculated redundancy data in the redundancy region.

Abstract: In one embodiment, an apparatus for a remote monitoring device is disclosed. The apparatus includes a casing to fit at least one of a storage location for storage media and handling mechanisms for the storage media, the storage location and the handling mechanisms being part of a media storage library, one or more monitoring devices within the casing to obtain from the media storage library at least one of environmental measurements and images of components in the media storage library, and a communication transmitter within the casing and communicatively coupled to the one or more monitoring devices to transmit at least one of data signals representing the at least one of environmental measurements and images of the components in the media storage library. Other embodiments are also disclosed.

Abstract: A disc drive system provides increased reliability by detecting and correcting errors associated with bit-patterned media. Write synchronization errors associated with bit-patterned media are addressed by including data storage for temporarily storing data that is being written to the disc drive. The data is read from both the disc drive and the storage medium and compared to detect write synchronization errors. A disc drive system for correcting write synchronization errors includes an encoder, non-volatile storage, and decoder device for implementing a parity-based scheme for increased reliability. Data strings being written to the disc drive are combined in an encoder to generate a parity string. The address of the data being written to the disc drive, along with the updated parity string is stored to the non-volatile storage. The data strings are read from the disc drive by the decoder.

Abstract: A method for field error checking begins by decoding a predetermined pattern of a field of a frame to produce a decoded pattern. The method continues by determining, for the decoded pattern, a path metric distance of a predetermined state of a plurality of states of the decoding. The method continues by comparing the path metric distance with an excepted path metric distance for the predetermined state. The method continues by indicating a field error when the path metric distance compares unfavorably with the excepted path metric distance.

Abstract: The present invention is directed to a method and a system to evaluate operational characteristics of an electronic circuit. The method includes generating a visual display, on a monitor, of an eye diagram viewer. The eye diagram viewer is used to establish a test parameter for the circuit. Accessed is data that includes a graphical file containing eye diagram information corresponding to the test parameter. A visually perceivable image of the eye diagram information is provided in response to the test parameter. Specifically, the eye diagram viewer is used to establish an eye diagram information identifier by displaying in a plurality of test condition selector screens one of a multiple condition values for the test condition parameters. The graphical file containing the eye diagram information corresponding to the eye diagram information identifier is obtained from the server and displayed.

Abstract: An information recording apparatus (1) is provided with: a first judging device (191) for judging whether or not a tracking error signal is greater than or equal to a first threshold value; a detecting device (192) for detecting, as a detection angle, a rotation angle of an information recording medium (100) when it is judged that the tracking error signal is greater than or equal to the first threshold value; and a second judging device (193) for judging whether or not the judgment that the tracking error signal is greater than or equal to the first threshold value is performed in synchronization with rotation of the information recording medium and at the same detection angle in a row.

Abstract: A data storage apparatus, which can format a recording medium in the background, that verifies data written in a designated region of the recording medium if the designated region has not yet been certified in the background, and writes the data in an alterative region of the recording medium if the designated region is found defective. Since the data storage apparatus either certifies the designated region of the recording medium or verifies the data written in the designated region, the data storage apparatus can enhance the reliability of the data written in the recording medium, but the data storage apparatus does not waste time by verifying the designated region of the recording medium two times or more.

Abstract: A method of performance monitoring and a processor for performance monitoring in a communications network are provided. A signal is monitored over time by allocating a current signal quality characterization to the signal, selected from at least two such signal quality characterizations, such as perfect time, errored time and unavailable time. A plurality of time intervals making up a continuous succession of such time intervals are identified, such that a current time interval is terminated and a next time interval is initiated each time the signal quality characterization allocated to the signal changes. Then, a record of each identified time interval is generated and can be used to generate a performance log. Selected records may be manipulated to reduce the amount of memory required to store the records while intelligently degrading their accuracy.

Abstract: A method for verifying sectors on an optical disc is provided. The method includes writing user data to unverified sectors of the optical disc and verifying the sectors of the optical disc with the user data. The sectors of the optical disc are verified by reading the user data on the unverified sectors of the optical disc and comparing the user data read from the unverified sectors of the optical disc with user data stored on a system buffer. The sectors of the optical disc are verified to determine whether any one of the unverified sectors having user data is defective. Also, the verifying of the unverified sectors establishes verified sectors having user data. The sectors of the optical disc that have been verified are tracked with a bitmap that is continually updated as the sectors are verified.

Abstract: The invention relates to a method of writing data to a disc (OD). The method comprised: a) performing a plurality of writing actions in which a plurality of data portions are written to the disc, b) performing a plurality of verification actions in which written data portions are at least partly verified and at least part of the data portions are replaced if needed. The method further comprises a2) performing a decision action for each writing action in which a decision whether or not to perform the verification action for a specific written data portion is taken.

Abstract: An optical disc controller of the present invention servo-controls an optical disc device which comprises a disc motor rotating an optical disc and an optical head emitting a light beam for recording data on the optical disc and/or reproducing data from the optical disc. The optical disc controller comprises: a variable clock output section for outputting a plurality of clock signals of different frequencies, and a control section which receives from the optical head a signal indicating a deviation from a predetermined target value to servo-control the light beam of the optical disc device and performs an operation according to the signal indicating the deviation so as to obtain and output a signal indicating a control amount.

Abstract: A disc drive system provides increased reliability by detecting and correcting errors associated with bit-patterned media. Write synchronization errors associated with bit-patterned media are addressed by including data storage for temporarily storing data that is being written to the disc drive. The data is read from both the disc drive and the storage medium and compared to detect write synchronization errors. A disc drive system for correcting write synchronization errors includes an encoder, non-volatile storage, and decoder device for implementing a parity-based scheme for increased reliability. Data strings being written to the disc drive are combined in an encoder to generate a parity string. The address of the data being written to the disc drive, along with the updated parity string is stored to the non-volatile storage. The data strings are read from the disc drive by the decoder.

Abstract: A write once disc allowing management of a data area, includes a lead-in zone, a data area, and a lead-out zone. The write once disc includes a predetermined area storing area allocation information which indicates whether at least one section of the data area is allocated for disc defect management. In the disc and method, area allocation information specifying a structure of the data area is recorded on the disc, thus allowing a recording/reproducing apparatus to recognize the data area structure. Therefore, allocating areas, such as a spare area, for disc defect management other than an area for storing user data, to the data area is possible. The allocation of the areas for disc defect management to the data area enables effective use of the write once disc.

Abstract: A write once disc allowing management of a data area, a method of managing the data area of the write once disc, an apparatus recording data on the write once disc, an apparatus and method of reproducing data from a write once disc. The write once disc, includes a lead-in zone, a data area, and a lead-out zone. The write once disc includes a predetermined area storing area allocation information which indicates whether at least one section of the data area is allocated for disc defect management. In the disc and method, area allocation information specifying a structure of the data area is recorded on the disc, thus allowing a recording/reproducing apparatus to recognize the data area structure. Therefore, allocating areas, such as a spare area, for disc defect management other than an area for storing user data, to the data area is possible. The allocation of the areas for disc defect management to the data area enables effective use of the write once disc.

Abstract: A write once disc allowing management of a data area, includes a lead-in zone, a data area, and a lead-out zone. The write once disc includes a predetermined area storing area allocation information which indicates whether at least one section of the data area is allocated for disc defect management. In the disc and method, area allocation information specifying a structure of the data area is recorded on the disc, thus allowing a recording/reproducing apparatus to recognize the data area structure. Therefore, allocating areas, such as a spare area, for disc defect management other than an area for storing user data, to the data area is possible. The allocation of the areas for disc defect management to the data area enables effective use of the write once disc.

Abstract: Temporary lock-out is provided while programming a group of non-volatile memory cells to more accurately program the memory cells. After successfully verifying that the threshold voltage of a memory cell has reached the level for its intended state, it is possible that the threshold voltage will subsequently decrease to below the verify level during additional iterations of the programming process needed to complete programming of other memory cells of the group. Memory cells are monitored (e.g., after each iteration) to determine if they fall below the verify level after previously verifying that the target threshold voltage has been reached. Cells that pass verification and then subsequently fail verification can be subjected to further programming. For example, the bit line voltage for the memory cell of interest may be set to a moderately high voltage to slow down or reduce the amount of programming accomplished by each subsequent programming pulse.

Abstract: An optical disc has spatial features (notches, bumps, etc.) that intentionally distort the analog Read Data signal. For a mark or space that is centered on a spatial feature, the distortion does not affect the resulting binary Read Data signal. If an edge of a mark or space is near the spatial feature, the resulting binary Read Data signal is altered. For calibration, marks or spaces are written adjacent to spatial features, with a range of times for initiating the writes. The result is a range of write times that do not alter the binary Read Data signal. From these known times and spatial locations, it is known when a mark or space must be written to ensure accurate spatial placement.

Abstract: A reading method for finding if a disc is placed reversely used in an optical disc drive is provided. The optical disc drive has a spindle motor, an optical pickup head having a lens, a fine actuator and a sled actuator. Firstly, a disc is placed into the optical disc drive. Next, the spindle motor rotates the disc. After that, a laser light of the optical pickup head is shot on the disc. Next, the lens is moved such that the laser light follows a single data track. Then, a central error signal of the lens is measured continuously. Afterwards, if the central error signal increases progressively, the optical disc drive finds the disc placed reversely, and the disc is ejected from the optical disc drive.

Abstract: A write once disc with at least one record layer includes a temporary defect management area in which temporary defect information regarding only defect detected during a corresponding recording operation, and temporary defect management information for managing the temporary defect information are recorded; and defect management areas in which the temporary defect information and temporary defect management information recorded in the temporary defect management area are recorded as defect information and defect management information, respectively.

Abstract: A write once disc, a disc drive therefor, and a method of managing disc defects on the write once disc using the disc drive in consideration of the compatibility of the write once disc with a rewritable disc drive, the write once disc includes a single record layer disc in which a lead-in area, a data area, and a lead-out area are sequentially formed and a first spare area and a second spare area are sequentially formed in the data area. The write once disc includes a defect management area (DMA) formed in at least one of the lead-in area and the lead-out area; a first temporary defect management area (TDMA) formed in at least one of the lead-in area and the lead-out area; and a second TDMA formed between the first spare area and a user data area or between the user data area and the second spare area.

Abstract: A write once disc allowing management of a data area, a method of managing the data area of the write once disc, an apparatus recording data on the write once disc, an apparatus and method of reproducing data from a write once disc. The write once disc, includes a lead-in zone, a data area, and a lead-out zone. The write once disc includes a predetermined area storing area allocation information which indicates whether at least one section of the data area is allocated for disc defect management. In the disc and method, area allocation information specifying a structure of the data area is recorded on the disc, thus allowing a recording/reproducing apparatus to recognize the data area structure. Therefore, allocating areas, such as a spare area, for disc defect management other than an area for storing user data, to the data area is possible. The allocation of the areas for disc defect management to the data area enables effective use of the write once disc.

Abstract: Temporary lock-out is provided while programming a group of non-volatile memory cells to more accurately program the memory cells. After successfully verifying that the threshold voltage of a memory cell has reached the level for its intended state, it is possible that the threshold voltage will subsequently decrease to below the verify level during additional iterations of the programming process needed to complete programming of other memory cells of the group. Memory cells are monitored (e.g., after each iteration) to determine if they fall below the verify level after previously verifying that the target threshold voltage has been reached. Cells that pass verification and then subsequently fail verification can be subjected to further programming. For example, the bit line voltage for the memory cell of interest may be set to a moderately high voltage to slow down or reduce the amount of programming accomplished by each subsequent programming pulse.

Abstract: There is realized an alarm information display unit capable of enabling a message relating to an error of a hardware placed in a predetermined managing environment to be displayed on a display screen together with normal alarm information. In the alarm information display unit for collecting alarm information from external equipment and displaying it on a display screen of a monitoring means, and mounting thereon a hardware placed in a predetermined managing environment, the alarm information display unit comprises an error retrieval means for retrieving newly occurred error while gaining access to a system log in which error information of the hardware is written, an error message generation means for generating an error message relating to the error information detected when retrieved by the error retrieval means, and a display control means for causing the generated error message to be displayed on the display screen together with the alarm information.

Abstract: A recording medium storing a write protection information, and a write protection method for protecting data recorded on a recordable and/or rewritable disc from unwanted overwriting or erasing. In order for write protection of a disc in a bare state that is usually used in a cartridge having a recognition switch for write-protection, such as a DVD-RAM, write protection information is recorded in a Lead-in area, a Lead-out area or a recording information area other than a user data area of the disc, and the data is protected from unwanted overwriting or erasing using the write protection information. Also, even though the write protection information stored on a disc does not match the state of a recognition switch of a case for write-protection, the data can be prevented from unwanted overwriting or erasing. Thus, the write protection can be ensured when a recordable and/or rewritable recording medium, such as DVD-RAM, DVD-R and DVD-RW, is used in a bare state.

Abstract: An information reproducing apparatus, in which a disk having correction data recorded thereon is placed, acquires region information indicative of a region corresponding to the correction data after load processing is performed by a ROM loader. Then, under the control of a CPU, the apparatus determines the correction data to be used for correcting a reproducing program based on the region information, reads the correction data from a lead out area or its outer region on the disk, temporarily retains the read correction data in a first RAM or a second RAM, and then stores the correction data to be resident in a nonvolatile first flash memory or a second flash memory, to correct the reproducing program based on the correction data. The information reproducing apparatus thereafter reproduces user data recorded on the disk according to the corrected reproducing program.

Abstract: A circuit for generating tracking error signal using differential phase detection, comprising a quadrant photodetector for receiving optical signal and inducting splitting signal A, splitting signal B, splitting signal C and splitting signal D, two adders for generating group signal (A+C) and group signal (B+D). A plurality of equalizers for receiving, equalizing and amplifying splitting signal A, splitting signal B, splitting signal C, splitting signal D, group signal (A+C) and group signal (B+D). A plurality of phase detectors for receiving the output of equalizers and comparing phase difference of splitting signal A and group signal (A+C), group signal (A+C) and splitting signal B, splitting signal C and group signal (B+D), and group signal (B+D) and splitting signal D, and outputting a plurality of adjustment signals respectively. A circuit for eliminating the phase difference by adding and subtracting some adjustment signals with same phase difference.

Abstract: A method for verifying sectors on an optical disc is provided. The method includes writing user data to unverified sectors of the optical disc and verifying the sectors of the optical disc with the user data. The sectors of the optical disc are verified by reading the user data on the unverified sectors of the optical disc and comparing the user data read from the unverified sectors of the optical disc with user data stored on a system buffer. The sectors of the optical disc are verified to determine whether any one of the unverified sectors having user data is defective. Also, the verifying of the unverified sectors establishes verified sectors having user data. The sectors of the optical disc that have been verified are tracked with a bitmap that is continually updated as the sectors are verified.

Abstract: A data storage apparatus, which can format a recording medium in the background, that verifies data written in a designated region of the recording medium if the designated region has not yet been certified in the background, and writes the data in an alterative region of the recording medium if the designated region is found defective. Since the data storage apparatus either certifies the designated region of the recording medium or verifies the data written in the designated region, the data storage apparatus can enhance the reliability of the data written in the recording medium, but the data storage apparatus does not waste time by verifying the designated region of the recording medium two times or more.

Abstract: In a data recording apparatus, values of parity bits to be additionally provided every one predetermined length block in data obtained by demodulating the original data are determined so as to satisfy a part of or an entire the predetermined run length limitation rule in ranges of a current predetermined length block, the plurality of parity bits, and a next predetermined length block that is positioned next to the current block. The parity bits having the values are additionally provided to the current block.

Abstract: A method for verifying sectors on an optical disc is provided. The method includes writing user data to unverified sectors of the optical disc and verifying the sectors of the optical disc with the user data. The sectors of the optical disc are verified by reading the user data on the unverified sectors of the optical disc and comparing the user data read from the unverified sectors of the optical disc with user data stored on a system buffer. The sectors of the optical disc are verified to determine whether any one of the unverified sectors having user data is defective. Also, the verifying of the unverified sectors establishes verified sectors having user data. The sectors of the optical disc that have been verified are tracked with a bitmap that is continually updated as the sectors are verified.

Abstract: A recording medium storing a write protection information, and a write protection method for protecting data recorded on a recordable and/or rewritable disc from unwanted overwriting or erasing. In order for write protection of a disc in a bare state that is usually used in a cartridge having a recognition switch for write-protection, such as a DVD-RAM, write protection information is recorded in a Lead-in area, a Lead-out area or a recording information area other than a user data area of the disc, and the data is protected from unwanted overwriting or erasing using the write protection information. Also, even though the write protection information stored on a disc does not match the state of a recognition switch of a case for write-protection, the data can be prevented from unwanted overwriting or erasing. Thus, the write protection can be ensured when a recordable and/or rewritable recording medium, such as DVD-RAM, DVD-R and DVD-RW, is used in a bare state.

Abstract: An intelligent MP3 error check detection method and apparatus. The claimed invention discloses an apparatus and method where all MP3 files are initially assumed to have compatible error checksums. A parameter W is initialized to zero. The parameter W is not constant and conceptually represents a state of the error check method. The destructive value of a first predefined constant is added to the parameter W each time the integrity of the data within the frame cannot be verified. The constructive value of a second predefined constant is subtracted from the parameter W each time the integrity of the data within the frame is successfully verified. If the value of the parameter W equals or exceeds a predefined threshold, the remainder of the MP3 file is decoded and played without error check protection.

Abstract: A system for monitoring a telecommunication link includes a computer which has a first processor, a first connection to a host storage medium and a first system bus interface, a measurement board which has a second processor, a second system bus interface and a first line interface for linking to a telecommunication link, and a system bus with which the first system bus interface and the second system bus interface are connected. The measurement board also has a measurement storage medium and an I/O interface linking the measurement board to the second storage medium. The measurement board with the measurement storage medium and the I/O interface form an embedded system. Data acquired from the telecommunication link via the line interfaces is stored directly in the measurement storage mediums rather than being passed in realtime over a system bus to the host storage medium.

Abstract: An information recording apparatus and method for recording information of a recording block including a plurality of sectors as one verifying unit into an optical information recording medium, a recording area of the optical information recording medium including a plurality of zones, and wherein each zone is different in a sector number per round of a track. A recorder records information of a plurality of recording blocks into the optical information recording medium and a verification conductor conducts a verify control. A number of the recording block included in the verifying unit is determined to be a minimal number in a rotation waiting sector number.

Abstract: An optical disc has spatial features (notches, bumps, etc.) that intentionally distort the analog Read Data signal. For a mark or space that is centered on a spatial feature, the distortion does not affect the resulting binary Read Data signal. If an edge of a mark or space is near the spatial feature, the resulting binary Read Data signal is altered. For calibration, marks or spaces are written adjacent to spatial features, with a range of times for initiating the writes. The result is a range of write times that do not alter the binary Read Data signal. From these known times and spatial locations, it is known when a mark or space must be written to ensure accurate spatial placement.

Abstract: In one embodiment, a storage device includes a controller, an integral storage medium that includes one or more stacks, where each stack includes multiple storage locations that are distributed throughout a portion of the volume of the integral storage medium, and an access mechanism that is configured to access the integral storage medium. The controller is configured to receive a command to write a unit of primary data to a first storage location. The controller is configured to generate a unit of redundant data corresponding to the unit of primary data and to control the access mechanism so that the unit of primary data is written to the first storage location in a first stack and the unit of redundant data is written to a second storage location within the integral storage medium.

Abstract: An information playback apparatus is provided, which can provide a sound which sounds natural by controlling an abrupt change in a tempo in the case of random access playback. When a cue point is registered, audio data which makes seamless playback possible is stored into a cue point memory, and further, the beat density of a playback sound being played when the cue point is registered is measured and stored. When the cue point is specified to start random access playback later, a ratio of the beat density (&agr;×DBPM) of a playback sound being played when the cue point is specified and the beat density (DBPMreg) stored in advance is found. Then, the random access playback is started after the beat density of a playback sound to be played after random access playback is started is corrected to be equal to the beat density when a start of the random access playback is specified.

Abstract: A disk apparatus 10 includes a DSP 36. The DSP 36 controls each circuit component under the instruction from an MCU 44. When a braking pulse is applied to a driver 38b at the end of a jump, a corresponding tracking actuator control voltage is supplied to a tracking actuator 16. Then a DSP core 36a determines whether the TE signal level becomes equal to or below the predetermined value within a predetermined period shorter than the zero crossing cycle of the TE signal. In case the TE signal level does not become equal to or below the predetermined value within the predetermined period, the DSP core 36a determines that the travel direction of an objective lens 14 with respect to a disk 22 is reversed and applies a correction pulse having a polarity opposite to that of the braking pulse thus accelerating the objective lens 14.

Abstract: A data compensating method and apparatus for compensating a block from which data cannot be read due to the presence of a scratch or dust when reproducing an optical disk are provided. The data compensating method includes the steps of: (a) setting a first block region for storing a block of data currently being reproduced and a second block region for storing the previous block of data, and reproducing the disk according to a read command; (b) determining the type of data block from a header in a sought block when the number of seek operations is greater than a predetermined value in reproducing the disk in step (a); (c) substituting an address of a block of data in the second block region, corresponding to a data block determined in step (b), for an address requested by a host; and (d) transmitting to the host the block of data in the second block region substituted in step (c).

Abstract: A reproduction apparatus for reproducing digital information recorded on an optical disc, comprises an optical pickup for reading said digital information recorded on said optical disc to have said digital information converted into electric signals, said digital information containing errors appearing when said digital information is read by said optical pickup; signal amplifying means for amplifying said electric signals converted from said digital information read by said optical pickup; signal processing means for processing said electric signals in one or more times of retry routines to correct said errors outputted as said electric signals from said signal amplifying means; a buffer memory for storing said electric signals outputted from said signal processing means; signal decoding means for decoding said electric signals stored in said buffer memory and outputted from said buffer memory; pickup driving means for driving said optical pickup to move on said optical disc, said errors being associated wit

Abstract: A circuit for generating tracking error signal using differential phase detection, comprising a quadrant photodetector for receiving optical signal and inducting splitting signal A, splitting signal B, splitting signal C and splitting signal D, two adders for generating group signal (A+C) and group signal (B+D). A plurality of equalizers for receiving, equalizing and amplifying splitting signal A, splitting signal B, splitting signal C, splitting signal D, group signal (A+C) and group signal (B+D). A plurality of phase detectors for receiving the output of equalizers and comparing phase difference of splitting signal A and group signal (A+C), group signal (A+C) and splitting signal B, splitting signal C and group signal (B+D), and group signal (B+D) and splitting signal D, and outputting a plurality of adjustment signals respectively. A circuit for eliminating the phase difference by adding and subtracting some adjustment signals with same phase difference.