Abstract: To realize a disk drive device capable of setting optimum recording power by obtaining amplitude information of a reproduced signal even when low recording power is used. A disk drive device for recording and reproducing data on/from an optical disk is provided with: a Viterbi decoding means for performing Viterbi decoding on a reproduced signal reproduced from an optical disk to decode data and creating status data representing a status transition in the Viterbi decoding; and a quality index creation means for calculating a differential value between an amplitude reference value corresponding to the status transition recognized from the status data and a reproduced signal value created by digitizing the reproduced signal and creating a quality index value representing quality of the reproduced signal based on the differential value.

Abstract: There are provided an optical disk, a magneto-optical disk, a disk apparatus therefor, and a data recording method which can provide improved recording/reproducing characteristics and record durability without linear velocity dependency even if the data access speed is increased by increasing the channel clock frequency. In a disk device for recording data on an optical disk by using a phase change recording scheme, erasing means for erasing data on the optical disk, and recording means for recording other data on the optical disk after the data is erased are provided.

Abstract: 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.

Abstract: There are provided an optical disk, a magneto-optical disk, a disk apparatus therefor, and a data recording method which can provide improved recording/reproducing characteristics and record durability without linear velocity dependency even if the data access speed is increased by increasing the channel clock frequency. In a disk device for recording data on an optical disk by using a phase change recording scheme, erasing means for erasing data on the optical disk, and recording means for recording other data on the optical disk after the data is erased are provided.

Abstract: In an information reproducing apparatus employing a maximum likelihood decoding method such as Viterbi decoding, there is a problem such that power consumption increases because a maximum likelihood decoding circuit is complicated, and many circuit elements must be used. A clock output control means is provided on a read clock transmission line of a maximum likelihood decoder, and no read clock is supplied to the maximum likelihood decoder in operation modes other than a specific operation mode when an input data is decoded by a Viterbi decoder, and thereby, it is possible to greatly reduce a power consumption. More specifically, in operation modes other than the read mode, the supply of read clock is stopped by the clock output control means based on a control signal from a controller for controlling an operation mode such as decoding or the like.

Abstract: 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.

Abstract: A recording medium comprising a data-recording surface is formed of plural tracks, with a respective track having a data section in which units of data are to be recorded. Only one header section is provided before the data section, the header section serving as a reference position for dividing said track into sectors. The header section is defined by prepits formed in the data-recording surface. As a result, data is recorded in the header section at such a high density that the header data is reproduced with super resolution.

Abstract: 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.

Abstract: A disk recording medium has reliability of address reading which is maintained equivalently to the conventional disk recording medium by recording a first address and a second address that are identical in a header area. By arranging the first and second addresses to be reversely displaced from the center line of a groove track or a land track to the radial direction of the medium, the distance between the first and second addresses when they are adjacent is increased, which eliminates the influence of crosstalk. This avoids redundancy of the header area and enables high-density recording to the disk recording medium.

Abstract: An A/D converter (30) samples an analog signal synchronously with a sampling clock from a VCO (70). These sampled values are stored in a shift register (410). A code judging section (420) detects the positive/negative sign pattern (time-series code pattern) of the sampled values held in storage elements (S0 to S5) of the shift register (410) and stores the sampled values in predetermined register (431 to 434) according to the detected sign pattern. According to this, a calculating section (430) determines the phase difference between the analog signal and the sampling clock. The phase difference is fed to a VCO (70) through a D/A converter (50) and a loop filter (60).

Abstract: There are provided an optical disk, a magneto-optical disk, a disk apparatus therefor, and a data recording method which can provide improved recording/reproducing characteristics and record durability without linear velocity dependency even if the data access speed is increased by increasing the channel clock frequency. In a disk device for recording data on an optical disk by using a phase change recording scheme, erasing means for erasing data on the optical disk, and recording means for recording other data on the optical disk after the data is erased are provided.

Abstract: In an information reproducing apparatus employing a maximum likelihood decoding method such as Viterbi decoding, there is a problem such that power consumption increases because a maximum likelihood decoding circuit is complicated, and many circuit elements must be used. A clock output control means is provided on a read clock transmission line of a maximum likelihood decoder, and no read clock is supplied to the maximum likelihood decoder in operation modes other than a specific operation mode when an input data is decoded by a Viterbi decoder, and thereby, it is possible to greatly reduce a power consumption. More specifically, in operation modes other than the read mode, the supply of read clock is stopped by the clock output control means based on a control signal from a controller for controlling an operation mode such as decoding or the like.

Abstract: 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.

Abstract: 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.

Abstract: A magneto-optical disk having a data-recording surface with a data section in which units of data are to be recorded and a header section which is provided before the data section and serves as a reference position of the data section. As shown at B in FIG. 2, data is recorded in the header section at a magnetically induced super resolution, whereas pre-pits are formed, defining a header section as shown at A in FIG. 2 in the conventional magneto-optical disk. Thus, the header section has increased recording density and reduced redundancy.

Abstract: A disk recording medium has reliability of address reading which is maintained equivalently to the conventional disk recording medium by recording a first address and a second address that are identical in a header area. By arranging the first and second addresses to be reversely displaced from the center line of a groove track or a land track to the radial direction of the medium, the distance between the first and second addresses when they are adjacent is increased, which eliminates the influence of crosstalk. This avoids redundancy of the header area and enables high-density recording to the disk recording medium.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: By an output signal from a four-section detector, arithmetic is done to generate a tracking error signal TE, a focus error signal FE, and on a total light amount signal Y. The signals are submitted to time division multiplexing, and are entered as a reference voltage of a D/A converter. As a digital input of the D/A converter, data DB from a reciprocal table is supplied. The DB is a reciprocal of the data DA which is a digitalized total light amount signal Y. In the D/A converter, the error signal and data DB are multiplied together so as to generate an error signals of which amplitude is constant against variation in laser power. By the error signal, a servo drive signal is generated in a signal processing circuit.