Abstract: A record carrier has substantially parallel tracks having first variations of a first physical parameter and second variations of a second physical parameter of the track. The first variations represent information recorded on the record carrier, this information being recoverable by a controllable type of data processing. A modulation pattern of the second variations represents a code for controlling the type of data processing. In respect of a code track that includes the modulation pattern, the modulation pattern in the left neighboring track is aligned to the modulation pattern in the right neighboring track. Thereby crosstalk due to the second variations is decreased, and at least two tracks have the same modulation pattern. The playback device has a demodulator (50) and a control unit (56) for retrieving the code from at least two tracks.

Abstract: The present invention relates to a modulated signal generator capable of carrying out signal processing at a higher speed or capable of supporting a special format and a new format with ease. A modulation processing storing unit 130 has a modulation processing program required for producing an optical disc master 320 stored therein in advance. Information data recorded in an master optical disc 310 is reproduced by an information reproducing unit 110 and is outputted to a modulation controller 120. The modulation controller 120 carries out the signal modulation processing onto the reproduced information data in accordance with the signal modulation processing program so as to generate a data stream and stores the data stream in a modulated information storing unit 140 as necessary.

Abstract: The invention relates to a playback apparatus for retrieving information from an information carrier (2). The information has been recorded on the information carrier (2) in the form of variations of a first physical parameter. The playback apparatus scans the information carrier by means of a transducer (4), which is responsive to said variations of said physical parameter. An information recovering circuit (5) recovers the information from a first detection signal (D1) received from the transducer (4). The information recovering circuit (5) comprises a phase-locked loop (51). The information carrier (2) exhibits a second variation of a second physical parameter, which differs from said first physical parameter but which is detectable by means of said transducer (4). A detection circuit (6) detects the presence of the second variation on the basis of a second detection signal (D2) received from the transducer (4).

Abstract: A record carrier (1) has a servo track (4) indicating an information track (9) intended for recording information blocks represented by marks. The servo track (4) has a periodic variation of a physical parameter at a predetermined frequency and modulated parts for encoding position information at regular intervals. The modulated parts start with a bit sync element and are of a data type having a data bit element or of a word sync type having a word sync element. The bit sync element and the data bit element are modulated according to a same predetermined type of modulation of the periodic variation. The modulated parts further include modulated parts (40, 41) of an isolated bit sync type only having the bit sync element.

Abstract: Described herewith is an optical disk manufacturing apparatus for reading recorded digital data from an optical disk, comprising an encryption unit (22, 23) for encrypting entered digital data according to a plurality of key information; an optical disk substrate manufacturing unit 2 for manufacturing an optical disk substrate 4 on which the encrypted digital data and key information are recorded in the form of physical form changes; a reflection film forming unit 41 for forming a reflection film on the optical disk substrate 4; and a key information recording unit 7 for recording key information on the optical disk substrate on which the reflection film is formed. The reflection factor of the optical disk is changed locally, thereby giving a jitter to the position information of each pit edge, and desired data is recorded additionally according to this jitter. Pits, etc.

Abstract: A discontinuous position detecting device for detecting a discontinuous position at which date and time information indicative of date and time of recording on a recording medium is discontinuous, the discontinuous position detecting unit including, a scanning unit that scans the recording medium in a first direction and in a second direction that is different from the first direction, a first detecting unit that detects a temporary discontinuous position located in a vicinity of the actual discontinuous position while the scanning unit scans the recording medium in the first direction, a second detecting unit that detects the actual discontinuous position while the scanning unit scans the recording medium in the second direction, and a scan controller that controls the scanning unit to scan the recording medium at a first scan speed except while the second detecting unit detects the actual discontinuous position, and to scan the recording medium at a second scan speed while the second detecting unit detects

Abstract: Described herewith is an optical disk manufacturing apparatus for reading recorded digital data from an optical disk, comprising an encryption unit (22, 23) for encrypting entered digital data according to a plurality of key information; an optical disk substrate manufacturing unit 2 for manufacturing an optical disk substrate 4 on which the encrypted digital data and key information are recorded in the form of physical form changes; a reflection film forming unit 41 for forming a reflection film on the optical disk substrate 4; and a key information recording unit 7 for recording key information on the optical disk substrate on which the reflection film is formed. The reflection factor of the optical disk is changed locally, thereby giving a jitter to the position information of each pit edge, and desired data is recorded additionally according to this jitter. Pits, etc.

Abstract: First and second synchronous words having respective numbers of times of inversion different from each other in NRZI conversion are generated in a synchronous word generation portion, and first and second code word series data are generated by arranging code word data generated making reference to a run-length coding table after these two synchronous words. With respect to the first and second code word series data, DSV calculation results stored in two DSV calculation peak value memories corresponding to these data are compared with each other by a peak value comparison portion. Based on a comparison result, the code word series data having a smaller direct-current component generated in NRZI conversion is selected.

Abstract: Described herewith is an optical disk manufacturing apparatus for reading recorded digital data from an optical disk, comprising an encryption unit (22, 23) for encrypting entered digital data according to a plurality of key information; an optical disk substrate manufacturing unit 2 for manufacturing an optical disk substrate 4 on which the encrypted digital data and key information are recorded in the form of physical form changes; a reflection film forming unit 41 for forming a reflection film on the optical disk substrate 4; and a key information recording unit 7 for recording key information on the optical disk substrate on which the reflection film is formed. The reflection factor of the optical disk is changed locally, thereby giving a jitter to the position information of each pit edge, and desired data is recorded additionally according to this jitter. Pits, etc.

Abstract: An information playback apparatus of the present invention is provided with: a first detecting unit for supplying a difference between respective output signals optically obtained by a pair of detectors for reading the information of the first track; a second detecting unit for supplying a difference between respective output signals optically obtained by a pair of detectors for reading the information of the second track adjacent to the first track; a first demodulating unit for demodulating a detected signal supplied from the first detecting unit, a second demodulating unit for demodulating a detected signal supplied from the second detecting unit. A coefficient controlling unit extracts the crosstalk caused by the second track, which is included in a demodulation signal obtained by the first demodulating unit, from the same signal and controls a coefficient based on the extracted crosstalk, and cancels the crosstalk by the calculated coefficient.

Abstract: A laser waveform generation function is provided in a laser driving waveform generator 2 near a laser 3. A recording clock generator 9 is included in the laser driving waveform generator 2 to generate a clock with a frequency higher than that of a synchronizing clock 202. This allows a recording laser current (waveform) to be generated without transmission of a high frequency signal from the modulator 6. Further, because the synchronizing clock 202 is stopped upon a reproduction operation including reproduction operation in an ID unit, undesired effects on a reproduction operation such as ID reproduction can be reduced. Because the response speed of the recording clock generator 9 can be changed, a high precision clock can be generated. Thus, a high-precision recording laser current (waveform) can be generated.

Abstract: A method of encoding and decoding data involving the simultaneous application of pulse width modulation and pulse position modulation systems to data intended for storage on a magnetic disk medium.

Abstract: An optical disk is provided for recording data of a signal modulated according to a predetermined modulation method in a form of concavo-convex pits. The optical disk includes a first area having a reflecting film partly removed, and a second area for recording pits which are different from pits satisfying requirements of the predetermined modulation method. The first area having the reflecting film partly removed includes a portion which is formed by removing the reflecting film, and has a length longer than a maximum pit length determined by the modulation method in a circumferential direction of the optical disk. When the pits recorded on the optical disk are physically copied as they are, physical copying of the optical disk can be prevented by utilizing such a difference that the authorized optical disk differs from a pirated copy in a combination of the respective reproduced signals of the first and second areas.

Abstract: Disclosed are a compatible type optical pick-up device for writing/reading data at a high density and a method for operating the optical pick-up device, thereby allowing the optical pick-up device to be easily assembled and improving optical efficiency. The compatible type optical pick-up device includes a laser beam source for outputting a laser beam having a writing mode power level for writing data from a disk, a collimator lens for collimating the laser beam outputted from the laser beam source, an optical attenuator located on an optical route of the laser beam passing through the collimator lens for attenuating the power of the laser beam, and an objective lens for converging the laser beam, incident thereon, onto the disk.

Abstract: A hologram recording apparatus and method, a hologram reproduction apparatus and method and a hologram recording medium by which recording and reproduction of address information and clock information on and from a recording medium can be performed without application of an optical disk mastering process. Signal light is spatially modulated based on address information corresponding to a relative position on a hologram recording medium being rotated and is recorded as a hologram on the rotating hologram recording medium. Since the address information is recorded as a hologram, recording of the address information on the hologram recording medium can be performed without application of an optical mastering process.

Abstract: A decoder circuit of the present invention, mounted on an integrated circuit, decodes input voltage Vin supplied to a single external input terminal into three or more control outputs, and an object of the present invention is to reduce the size of a chip. The foregoing decoder circuit includes: a P-type transistor in which an emitter is connected to a power source line of high level, a base is connected to the external input terminal, and a collector is an output terminal of a first control output; and an N-type transistor in which an emitter is connected to a power source line of low level, a base is connected to the external input terminal, and a collector is an output terminal of a second control output, and decodes the control outputs to three or more sets of data by carrying out logic operations.

Abstract: The present invention relates to a method for the demodulation of the ADIP data of a wobble signal of an optical recording medium, whereby the wobble signal is modulated using two different methods, and to an apparatus for reading from and/or writing to optical recording media using such method.

Abstract: Four ECC blocks are recorded in a burst cutting area of an optical disc. Each ECC block is constituted by a BCA content code of 1 byte, content data length of 1 byte, and content data of 14 bytes. Of the BCA content data, the leading 6 bits are used for application ID and the remaining 2 bits are used for block number. Disc ID is stored in the content data. Since the four ECC blocks exist, the optical disc can be managed individually by four applications at the maximum. Thus it becomes possible to manage the same optical disc by a plurality of applications.

Abstract: A recording medium having a data structure for managing additional content data of main data recorded thereon in accordance with the present invention comprises a data area storing at least one clip file including main data and/or additional content data of the main data; and a navigation area storing a clip information file including information to indicate whether the clip file includes additional content data.

Abstract: A processing scheme for digital storage media using multi-user detection to separate tracks of data or remove interference from neighboring tracks. In one embodiment, data is written on a plurality of tracks positioned sufficiently close together so that multiple tracks are detected simultaneously by the read access sensor. Upon scanning the surface for data, the read element simultaneously receives the data signals from a plurality of tracks. Joint detection signal processing resolves the interference and data bits from the multiple sensed tracks, enabling closer packing of data with minimal guard space.

Abstract: A method of encoding and decoding data involving the simultaneous application of pulse amplitude modulation, pulse width modulation, and pulse position modulation systems to data intended for storage on a magnetic disk medium.

Abstract: A record carrier (1) is described comprising a servo track (4) indicating an information track (9) intended for recording information blocks represented by marks having lengths expressed in channel bits, which servo track (4) has a periodic variation of a physical parameter. The periodic variation is modulated for encoding record carrier information, such as addresses. The modulation is a bi-phase modulation in which a data bit of the record carrier information is encoded by a first predetermined number of variations of a first phase followed by the same number of variations of a second phase inverse to the first phase. A recording and/or playback device has a demodulator for retrieving data bits of the record carrier information from a first predetermined number of variations of a first phase followed by the same number of variations of a second phase inverse to the first phase.

Abstract: A method for managing copy protection information of a recording medium is disclosed. Copy protection information for decrypting A/V data encrypted and recorded in a data area of an optical disc such as a CD, a DVD or a BD is recorded in a key locker in the optical disc. A first key value for reading the copy protection information is recorded in a specific area of the optical disc, and a second key value for reading the copy protection information is managed in an optical disc drive or in an application. To reproduce the A/V data in the optical disc, the copy protection information recorded in the key locker is read and decrypted by a combination of a hidden code (having the first key value) recorded in the optical disc and a drive or application key (having the second key value) managed in the optical disc drive or application. This significantly improves the security of the copy protection information.

Abstract: A method for managing copy protection information of a recording medium is disclosed. A data stream encrypted using copy protection information is recorded in a data area of an optical disc such as a write once optical disc or a rewritable optical disc, while the copy protection information and a drive ID are recorded together in a key locker of the optical disc. When a data stream of an optical disc is reproduced, reading and decryption of the copy protection information is selectively performed depending on whether the drive ID recorded in the key locker and a drive ID managed in an optical disc drive, into which the optical disc is inserted, are identical. This prevents contents such as broadcast programs recorded in an optical disc from being illegally duplicated.

Abstract: A method for managing copy protection information of a recording medium is disclosed. Copy protection information for decrypting A/V data encrypted and recorded in a data area of an optical disc is recorded in a key locker of the disc. Information of makers that have manufactured optical disc drives, drive maker keys of each maker and flags indicating whether drive keys are valid or not is included in association with each other in the key locker. To reproduce the A/V data, the copy protection information is read and decrypted by comparing a drive key managed in the optical disc drive with the key renewal information recorded in the optical disc. Accordingly, illegally duplicated optical disc drives can no longer perform a normal playback operation, thereby effectively suppressing illegal duplication of optical disc drives, which also prevents optical disc drives of all makers from being duplicated at once.

Abstract: In order to evaluate the quality of a signal recorded on an optical recording medium, a target signal is obtained based on a predetermined data string and a predetermined partial response characteristic, and for each clock cycle, an equalization error is calculated that is a difference between the target signal and a signal reproduced each clock cycle. Further, the product of the equalization errors calculated at different times is obtained, and based on the obtained product, the quality of a signal is evaluated.

Abstract: A recording apparatus for use with a read-only optical information storage medium having a plurality of areas, including: a recording and/or reading unit which records data on and/or reads data from the plurality of areas; and a controller which: controls the recording and/or reading unit to record data in at least one of the plurality of areas in the form of pits in a first pit pattern, and controls the recording and/or reading unit to record data in others of the plurality of areas in the form of pits in a second pit pattern different from the first.

Abstract: Systems and methods are provided for caching media data to thereby enhance media data read and/or write functionality and performance. A multimedia apparatus, comprises a cache buffer configured to be coupled to a storage device, wherein the cache buffer stores multimedia data, including video and audio data, read from the storage device. A cache manager coupled to the cache buffer, wherein the cache buffer is configured to cause the storage device to enter into a reduced power consumption mode when the amount of data stored in the cache buffer reaches a first level.

Abstract: Conventionally, as in the case of switching between a DVD-R and a DVD-RAM, when the method of record mark arrangement in a track is changed, the physical format of the disk is also changed. This makes it difficult to ensure compatibility between pieces of data recorded by a plurality of different methods of record mark arrangement. According to the present invention, sector address data and block address data are recorded in each sector by using wobbling or deformation of a recording groove. Then, depending on which address is used, sector data structure is modified, thereby making it possible to select an address data detection and a data structure on a disk in a single physical format depending on the purpose.

Abstract: An optical disk according to the present invention is the optical disk on which secret information on unique information given to a specific optical disk manufacturer or a specific optical disk and information recorded on an infringement disk list of identifying an illegitimate optical disk manufacturer or an illegitimate optical disk are recorded in advance, and the optical disk has an area in which reproduction-only encrypted data encrypted based on the secret information and the information on the infringement disk list is recorded in advance or an area capable of recording the encrypted data to be encrypted based on the secret information and the information on the infringement disk list.

Abstract: An optical disk drive capable of securing reliable reproduction of a wobble signal even under a constant angular velocity control of a recordable or rewritable optical disk is disclosed. The optical disk has a guide track wobbled to produce a constant frequency when the optical disk is driven under a constant linear velocity control. An optical pickup unit detects the light reflected from the optical disk, and a wobble signal reproducing section takes out a wobble signal. The wobble signal reproducing section has two band-pass filters; a first band-pass filter detects a center frequency of the wobble signal, which is caused to vary under the constant angular velocity control, and a second band-pass filter has a center frequency set to the detected center frequency whereby the wobble signal is extracted by the second band-pass filter. The extracted wobble signal is subsequently demodulated address information.

Abstract: Audio data of 20 bits is separated into first data of upper 16 bits and second data of lower 4 bits. EFM modulation data is formed from the first data. A laser beam is on/off controlled in correspondence to the logic level of channel data obtained by NRZI modulating a serial data train. The first data, therefore, is recorded in a manner similar to the case of a compact disc. Each pit is controlled so as to have a displacement in the right/left direction for the track center in accordance with the second data and the deviated pit is formed. When data is recorded by the displacement of the pit, since a high frequency component of a tracking error signal changes upon reproduction, the second data can be extracted from the tracking error signal.

Abstract: In a disk drive for compensating the tilt between a disk including a first identification information area shifted radially outward by a predetermined distance from the center of a track, and a second identification information area shifted radially inward by the same distance, and a head for forming a light spot on the disk, there are provided a unit for determining a sum signal of an output signal from a photodetector obtained when the light spot traces the first identification information area and an output signal obtained when the light spot traces the second identification information area, and a tilt control unit for using the sum signal as an index to control the relative tilt between the disk and the head so as to cause the index to approach an extreme value.

Abstract: Accordingly, an improved method for recording data on an optical medium is disclosed which includes receiving and encoding a first set of data frames by a CIRC encoder to generate a second set of data frames. A control byte is then added to each of the second set of data frames to generate a third set of data frames. The third plurality of frames of data are received and encoded at an EFM encoder to generate a section comprising a plurality of Channel frames. The control byte of a sequentially first one of the third set of data frames is replaced with a SYNC 0′ byte selected from the limited group of previously unassigned fourteen-bit combinations. The control byte of a sequentially second one of the third set of data frames is also replaced with a SYNC 1′ byte selected from the same group.

Abstract: A system and method are disclosed for carrying additional information data on multiplexed signals which are modulated on different wavelengths. An information code such as an address or control data for a particular data signal at a selected wavelength is overlaid on the parallel multiplexed signals. The information code may be overlaid by attenuation or changing the amplitude of the different signals. A separate marker channel at a separate wavelength is also multiplexed with the data signals to indicate the presence of an information code. An optical data detector array is used to optically determine the encoded address by comparing the signals with light levels and producing an output when a matching code is detected. The optical data detector array uses a series of detectors each corresponding to the wavelength of light signals carrying the information data.

Abstract: The present invention provides a device and method for an optical disc such as a DVD which can keep proper edge position of a recording pulse to record data of high quality without depending on a fluctuation in a supply voltage and a fluctuation in a temperature. The optical disc device according to the present invention comprises a laser driver for driving a laser to record data on an optical disc, a recording pulse generator for generating a recording pulse signal by using a predetermined delay circuit, to control the switching of the laser power of the laser driver, a delay amount measuring section for measuring the delay amount of a delay circuit in the recording pulse generator, and a recording pulse position correction section for correcting the predetermined edge position of the recording pulse based on the result of the measurement.

Abstract: A modulation/demodulation method of a run length limited method and a modulation/demodulation apparatus relate to converting a bit stream of a recording data into a bit stream proper to a recording phase when recording a data onto an optical recording medium. In the present data modulation and demodulation method, modulation data consist of partly consecutive 0s or 1s which are quantized in length, satisfying the given minimum and maximum run lengths of RLL at the same time. Therefore, a reproducing error is checked and corrected based on whether the quantizing condition is violated or not during the demodulation. This error recovery capability makes it possible to enhance a recording density of a recording medium and to reduce a judgement error possibility due to a jitter component of a reproducing signal, so that provides a high reliability for high density recording medium compared to a conventional modulation method.

Abstract: The present invention provides an integrated controller to process both optical reads and optical writes of multiple optical media. The integrated controller includes a host interface; a buffer manager coupled to the host interface; an embedded memory coupled to the buffer manager; an integrated encoding/decoding engine coupled to the buffer manager; a data channel interface coupled to the integrated encoding/decoding engine; and an integrated servo/recording processor coupled to the integrated encoding/decoding engine and the data channel interface, where the integrated servo/recording processor includes a set of write strategies. The present invention provides a controller which integrates the functionality of the conventional controllers into an integrated processor. With the controller in accordance with the present invention, a single drive may be provided which can read CD-based and DVD-based formats, read and write to Write Once Media, and read and write to Rewritable Media.

Abstract: Presently, almost all commercially available data storage systems use saturation recording and binary signaling schemes. Earlier data channels for storage systems utilized various forms of bit by bit peak detection. More recently, various forms of PRML (partial response maximum likelihood) or DFE (decision feedback equalization) have appeared in products. These improvements are still limited by the fact that the storage data channel is a saturation channel, and as such, has a significantly reduced information handling capacity compared to a linear data channel. Recording media defects are currently mapped out at the factory and skipped under normal device usage, while remaining errors are corrected by error correction code. However, at higher aerial densities, defects in the media tend to become a greater problem. The above-incorporated applications teach a linearization technique for linearizing magnetic recording channels without suffering signal to noise loss and not suffering bandwidth loss.

Abstract: In an information recording method and apparatus, a sequence of sync frames indicative of data is recorded onto tracks of an optical recording medium. In the recording medium, prepits are formed on lands between the tracks at given intervals, and sync patterns, providing synchronization on a sync-frame basis, are inserted in the sync frames such that each sync pattern has a length in a track direction larger than a length of one of the prepits and a position of each sync pattern matches with a position of at least one of the prepits. Codes that represent sync patterns for the sync frames are selected such that each sync pattern is formed as a space on the recording medium. Modulation codes are generated based on the sync frames in which the selected codes are inserted, by modulating the sync frames containing the selected codes in accordance with a predetermined modulation scheme. A sequence of recording pulses is generated by converting the modulation codes through a predetermined conversion scheme.

Abstract: A simplified optical disc writing apparatus that is connectable to a host system is provided in which at least one part of a digital signal processing portion (123, 124, 131, 132) is carried out in the host system (200) by using software (300). Picked up from a first optical disc (11) by a pickup (110), amplified by an RF amplifier (121), and binary coded by a binary coding circuit (122), a binary coded signal is supplied to the host system (200) through a host interface (210). The software (300) carries out a processing for EFM demodulating the binary coded signal, a processing for decoding the EFM demodulated signal, a processing for encoding user data, and a processing for EFM modulating the encoding processed signal. The EFM modulated signal is added with a strategy in a strategy adding circuit (133), and is converted into a laser driving signal in a laser driver (134). Responsive to the laser driving signal, the pickup (110) writes data in a second optical disc (12).

Abstract: A record carrier (1) is described which has a servo track (4) indicating an information track (9) intended for recording information blocks represented by marks. The servo track (4) has a periodic variation of a physical parameter at a predetermined frequency and modulated parts for encoding position information at regular intervals. The modulated parts start with a bit sync element and are of a data type having a data bit element or of a word sync type having a word sync element. The bit sync element and the data bit element are modulated according to a same predetermined type of modulation of the periodic variation. The modulated parts further comprise modulated parts (40,41) of an isolated bit sync type only having the bit sync element. Further a device for reading and/or writing the record carrier is described.

Abstract: A data modulation method resistant to channel distortion and a method of correcting error in data coded by the modulation method. The data modulation method uses a run length limited (RLL) modulation code applied to write data to an optical storage medium, the RLL modulation code being expressed as RLL (d, k, m, n, s) with s=2 or greater, where d is minimum run length, k is maximum run length, m is a data bit length before modulation, n is a codeword bit length after modulation, and s is a space length between codewords. Further, the data modulation method provides run lengths expressed as in+1=in+s (n=1, 2, . . . ), where i1=d.

Abstract: An optical disk signal processing apparatus retains compatibility with the conventional continuous servo recording technique, and reduces the amount of noise included in a signal played back from the optical disk without the need to decrease the size of the area for recording data, resulting in a drastically increased signal-to-noise ratio. The optical disk signal processing apparatus has a light source, an optical system for leading a light beam generated by the light source, an optical device for converging the light beam output by the optical system and applying the converged beam to the rotating optical disk, a signal detecting optical system for detecting a signal reflected by the rotating disk through the optical device, and a light detecting instrument for converting light produced by the signal detecting optical system into an electrical signal and a data detecting circuit.

Abstract: A record carrier has substantially parallel tracks, which exhibit first variations of a first physical parameter and second variations of a second physical parameter of the track. The first variations represent information recorded on the record carrier, which information is recoverable by means of a controllable type of data processing. A modulation pattern of the second variations represents a code for controlling the type of data processing. With respect to a code track that includes the modulation pattern, the modulation pattern in the left neighboring track is aligned to the modulation pattern in the right neighboring track. Thereby crosstalk due to the second variations in decreased, and at least two tracks have the same modulation pattern. The playback device has a demodulator and a control unit for retrieving the code from at least two tracks.

Abstract: Apparatus and method for writing data to an optical disc, and for subsequently reading the data therefrom. A first modulation encoding scheme (MES1) is defined to encode input data as data symbols having nominal symbol lengths over a first range. A second modulation encoding scheme (MES2) different from the MES1 is further defined to encode input data as data symbols having nominal symbol lengths over a second range. Each symbol length of the second range appears in the first range. The MES1 is used to encode primary data written to the disc while the MES2 is used to encode secondary data inserted at selected locations for disc authentication purposes. A readback system includes a primary decoder which decodes and outputs the primary data, and a secondary decoder which searches for a leading synchronization pattern which, when detected, allows remaining portions of the secondary data to be decoded.

Abstract: An apparatus and method are disclosed for optimizing the writing of data to an optical disc to improve readback characteristics and minimize the effects of errors. An optimization circuit generates an optimized modulation signal which is used to modulate a writing beam of a laser beam recorder, the optimized modulation signal comprising a series of data symbols that correspond to resulting pits and lands on the optical disc. The optimization circuit optimizes the locations of pit and land transitions on the optical disc by individually adjusting leading and trailing edges of the data symbols, as well as amplitudes of the data symbols. In this manner, the particular length of each pit and land on the disc can be individually selected based on nominal symbol length, as well as other factors including radial and angular locations of the pits and lands on the disc.

Abstract: A laser waveform generation function is provided in a laser driving waveform generator 2 near a laser 3. A recording clock generator 9 is included in the laser driving waveform generator 2 to generate a clock with a frequency higher than that of a synchronizing clock 202. This allows a recording laser current (waveform) to be generated without transmission of a high frequency signal from the modulator 6. Further, because the synchronizing clock 202 is stopped upon a reproduction operation including reproduction operation in an ID unit, undesired effects on a reproduction operation such as ID reproduction can be reduced. Because the response speed of the recording clock generator 9 can be changed, a high precision clock can be generated. Thus, a high-precision recording laser current (waveform) can be generated.

Abstract: A data recording and reproducing method for an optical disk data storage system to record data compressed at different data compression rate according to an operator's specification, and to reproduce the recorded data by decompressing. According to the operator's indication, the data is recorded at certain data compression rate in indicated area. The information of the data compression rate and the recorded area is stored as a table of contents (TOC) data. The TOC data is reproduced and stored in a memory after the optical disk is loaded. The recorded data is reproduced by selecting a decoding circuit to decompress the data. The decoding circuit is selected by referring the TOC data to identify data compression rate of the recorded data. Also the TOC data is referred to identify read-in and read-out region of the recorded data. The position of a pick-up when the data recording is started and ended, is recorded as the TOC data to provide random access capability for the data reproduction.

Abstract: An optical disc apparatus has a demodulation circuit performing an FSK demodulation by being provided with a binary signal which is obtained by binarizing a signal reproduced from an optical disc on which an FSK modulation signal is previously recorded. An edge interval of the binary signal is measured. An FSK modulation component is obtained from a difference between a measured edge interval value and a previously determined edge interval reference value. A demodulation value is obtained based on a moving average of the FSK modulation component. A moving average of the demodulation value is compared with a reference value so as to obtain a binary FSK demodulation signal. Additionally, the optical disc apparatus includes a decode circuit for decoding binary data from a biphase code signal which is reproduced from an optical disc and to be inverted at an end of each bit.