Sony Corporation

Nec Corporation

Other

Takayoshi Chiba

Junichi Horigome

Shigeo Yamaguchi

Yutaka Ishikawa

Hideki Kobunaya

Yoshimori Yamasaki

Masayoshi Nagata

Yasuo Tone

Hiroshi Aoki

Masatoshi Nishino

Atsushi Watanabe

Takao Yamaguchi

Hideo Tada

Shiro Suzuki

An information reproduction device capable of a more appropriate frequency monitoring of a read clock, as compared to conventional devices, is realized. By providing the information reproduction device with a frequency difference detection means which detects a difference in frequencies between a read clock, obtained by applying PLL to a reproduction signal read from a recording medium, and a reference clock; an information processing means which performs signal processing on the reproduction signal and outputs a processing status information indicating whether or not the information processing is performed normally; and a frequency monitoring means which monitors whether or not the frequency of the read clock is normal based on the frequency difference and the processing status information; wherein the frequency monitoring means makes a transition to an OK status which indicates that the frequency of the read clock is normal when the processing status information is indicating a normal status; and makes a transition to a NG status which indicates that the frequency of the read clock is abnormal when the processing status information is indicating an abnormal status and the difference of the frequencies exceeds a first threshold; and returns to an OK status when the difference of the frequencies is below a second threshold during the NG status.

Information reproduction device and read clock monitoring method

To enable a physically rewritable disc to be appropriately used as a write-once type. When the rewritable disc is used in rewritable application, the position where writing of a predetermined data unit (for example, an ECC block) in data is started is set to a first position with respect to a reference position to record or play back the data. In contrast, when the rewritable disc is used in write-once application, the position where writing of the predetermined data unit in the data is started is set to a second position different from first position to record or play back the data. The position where writing of the data is started in the rewritable application is shifted from the position where writing of the data is started in the write-once application to disable rewriting of the data recorded on a rewritable recording medium when the rewritable recording medium for the write-once application is loaded in a recording-playback apparatus that does not assume the use of the rewritable recording medium in the write-once application.

Recording device, recording method, reproducing device, and reproducing method

An optical disk apparatus for a phase-change optical disk detects the boundary between a first region and a second region prior to detecting a synchronization mark. The synchronization mark is detected in accordance with the position of the detected boundary between the first region and the second region. User data is read from a data region in accordance with the detected synchronization mark.

Phase-change optical disk and optical disk apparatus

In a magneto-optic disc apparatus corresponding to six-value four-status Viterbi decoding method, an RAA has 12 registers so as to separately adapt amplitude reference values for an address portion and amplitude reference values for a data portion on a magneto-optic disc. Normally, stored values of the registers at the time a reproducing operation has been just completed are used for initial values for an adapting process in the next reproducing operation. On the other hand, when data cannot be correctly reproduced and thereby a read-retry operation or the like is preformed, predetermined values that are stored in 12 registers in the RAA are used as initial values. In this case, the adapting process for amplitude reference values is not performed.

Information reproducing apparatus and reproducing method

An A/D converter ( ) samples an analog signal synchronously with a sampling clock from a VCO ( ). These sampled values are stored in a shift register ( ). A code judging section ( ) detects the positive/negative sign pattern (time-series code pattern) of the sampled values held in storage elements (S to S ) of the shift register ( ) and stores the sampled values in predetermined register ( to ) according to the detected sign pattern. According to this, a calculating section ( ) determines the phase difference between the analog signal and the sampling clock. The phase difference is fed to a VCO ( ) through a D/A converter ( ) and a loop filter ( ).

PLL circuit

An ACS of a Viterbi decoder generates status data that an SMU represents a status transition corresponding to the maximum likelihood status transition selected corresponding to each read clock pulse. A merge block generates decoded data corresponding to status data. A timing generator generates timings of a leading edge and a trailing edge of a reproduced RF signal corresponding to status data. A PEC generates a phase error signal PE corresponding to a reproduced signal value sampled at these the timings (namely, sampling values of an A/D converter). With the phase error signal PE, a VCO is controlled. The memory length of the SMU that generates the timings is smaller than the memory length for a decoding process. One of the memory lengths can be selected depending on whether data is reproduced from a header area or a data area.

In a Viterbi decoder, an SMU is used instead of a PMU. The SMU has four status memories that process a status data value composed of a plurality of bits that represent a status at a time. The status memories generate a sequence of four status data values. A merge block generates decoded data corresponding to the four status data values, detects mismatches of four status data values, and generates a mismatch detection signal NM. The number of mismatches is counted corresponding to the mismatch detecting signal NM. The quality of decoded data and reproduced signal are evaluated corresponding to the count value.

A structure for detecting a phase error for causing a PLL of an information reproducing apparatus to be locked and for selecting Viterbi determination mode, MSB determination mode (for obtaining a phase error detection timing corresponding to MSB of output data of an A/D converter disposed on the preceding stage of a Viterbi decoder) is disclosed. One of the three modes is selected corresponding to the state of the PLL. A Viterbi timing generating circuit, an MSB timing generating circuit, and a frequency lock mode timing generating circuit are provided. Phase error detection timings generated by the three circuits are selectively supplied to a phase error detecting circuit by a sampling pulse selecting switch. The selected phase error detection timing is switched between the acquisition mode and the tracking mode.

A magneto-optical disc recording and reproducing apparatus has the distinction of ID signal reproducing ability in read (reproducing) mode and in write (recording) mode. The disc recording format is based on sectors each including two identifiers in the address field. The apparatus analyzes a command from the host computer (step ST1). It sets the control parameter of write mode for the write command or the control parameter of read mode for the read command (steps ST4, ST5) so as to impose the distinction on the ID signal reproducing (readout) ability between read mode and write mode. Following the seek operation to the target track, it determines based on the ID signal detection as to whether a correct ID signal has not been retrieved from any of two identifiers in the target address field indicative of the error of ID signal reproduction (step ST7). It proceeds to the information writing or readout operation unless the ID signal reproduction ends in error (step ST8).

Recording and reproducing apparatus including read/write mode

In an optical information accessing system for an optical disc including a plurality of tracks forming one helix, a counter counts sectors, and a comparator compares a value of the counter with a predetermined value. When the value of the counter reaches the predetermined value, a coincidence signal is generated from the comparator. A gate circuit passes the coincidence signal as a jump-back signal. When data processing upon the optical disc is abnormally interrupted and the coincidence signal is generated, the predetermined value is switched from a first value to a second value larger than the first value.

Optical information accessing system capable of reliable jump-back

In an optical information accessing system for an optical disk including a plurality of sectors each having sector mark, a read operation is carried out by a sector mark detection signal when this signal is generated, and is carried out by a sector mark interpolation signal when the sector mark detection signal is not generated. When the sector mark detection signal is generated, the sector mark interpolation signal is masked, while, when the sector mark interpolation signal is not masked, the sector mark detection signal is invalidated.

Optical information accessing system capable of generating one sector

An improved apparatus for detecting address information recorded on a recording medium such as an optical-magnetic disc is disclosed. The header information is recorded on each sector of the disc recording medium and is constituted by a sector mark indicating a head position of the corresponding sector, a plurality of address marks, and subsequent address information data. In a first preferred embodiment, a number of bytes starting from an end position of the address information and ending at a head position of the address information is counted and an address information recognition circuit is provided so as to provide an address information recognition start signal for the address information recognition signal at a predicted position of the head position. The address information recognition circuit extracts and recognizes the address information in accordance with the address information recognition start signal supplied from a recognition start signal generator when the address mark detecting circuit does not supply a head position detection signal. In a second preferred embodiment, a window signal used to detect the address mark is selectively changed according to the result of detection of the preceded sector mark and/or address information data.

Apparatus for using window signal generators to enable detection of

An optical disc apparatus includes a rotary encoder (14) for detecting a rotation of a spindle motor (12) that rotates an optical disc (11). A counter (16) generates a timing pulse (P.sub.3) per rotation of the optical disc (11) in synchronism with an output timing pulse (P.sub.1) of the rotary encoder (14). When the timing pulse (P.sub.3) is generated, in other words, one revolution of the optical disc (11) is specified, an optical pickup (21) is returned by one track amount in an inner peripheral direction (Ri) of the optical disc (11) in synchronism therewith. Therefore, even when an optical disc is an optical disc having tracks in which a length of one track is made different from a length of physical one round, the optical pickup (21) can be maintained in a still condition (also called on-track condition).

Optical pickup control apparatus

A disc drive such as an optical magnetic disc drive latches status information IDS, and IDOST to DATST for operational status at a timing when an abnormality occurs, and repeats recording based upon latched status information IDS, and ID0ST to DATST, thereby reducing retry time.

Growing community of inventors

Tokyo, Japan

Takayoshi Chiba