JP2006324009A - Method for tracking control and storage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure a desired recording/reproducing margin and realize a high density recording without providing a tilt correction mechanism or the like, in a method for tracking control and a storage device. <P>SOLUTION: The device is so composed to measure the state of irradiation with light beam while the tracking target position of the light beam on a recording medium is offset and to measure an optimum offset so that the state of irradiation with light beam is made at an optimum tracking target position, and to control the tracking by setting the measured optimum offset. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tracking control method and a storage device, and more particularly to a tracking control method for recording and / or reproducing information on an optical recording medium with a desired recording and / or reproducing margin, and such a tracking control method. The present invention relates to a storage device such as an optical disk device to be employed.

  In the magneto-optical disk apparatus, in addition to the structure for recording and / or reproducing (recording / reproducing) information with respect to the land of the magneto-optical disk, the structure for recording / reproducing information on both the land and the groove of the magneto-optical disk Things have been proposed. The recording density can be increased by adopting a so-called land / groove recording method in which information is recorded / reproduced on both the land and the groove of the magneto-optical disk.

  In an optical recording medium having a narrow track pitch that employs a land / groove recording system, typified by a magneto-optical disk, signal reproduction performance of a target track is degraded due to signal interference caused by a signal written in an adjacent track. there is a possibility.

  As one of the factors at the time of reproduction of this signal interference, a radial tilt of the optical axis with respect to the medium recording surface (reflection surface), that is, a radial tilt is known. When there is a radial tilt, an aberration occurs in the light beam, and it becomes easy to receive the interference of the signal of the adjacent track. Normally, when the radial tilt is small, the center of the tracking error signal (TES) is the minimum point of the reading error rate, so the tracking target position may be the center of TES. On the other hand, it is known that when the radial tilt is large, the point at which the tracking target position is shifted to either one from the center of the TES is the minimum point of the reading error rate.

  Since the conventional optical recording medium has a relatively large track pitch, there is a sufficient recording and / or reproduction margin (recording / reproduction margin) even when the tracking target position remains at the center of the TES. However, as the capacity of the optical recording medium is increased and the track pitch is reduced, it is expected that the influence of the radial tilt is further increased.

As means for solving these problems, research has been conducted on a tilt correction mechanism that mechanically corrects the relative position and angle between the optical head and the optical recording medium. However, adding a new mechanism such as a tilt correction mechanism complicates the configuration and control of the storage device, which makes the storage device expensive.
JP-A-8-45081 JP-A-6-84173 JP 2000-132855 A JP 2000-357337 A

  As the optical recording medium has a narrower track pitch, it is more susceptible to radial tilt, and the conventional storage device has a problem that the recording / reproducing margin may be significantly impaired. Also, the provision of the tilt correction mechanism complicates the configuration and control of the storage device and increases the cost of the device.

  Therefore, an object of the present invention is to provide a tracking control method and a storage device that can ensure a desired recording / reproducing margin without providing a tilt correction mechanism or the like.

  The above object can be achieved by the first method of the present invention. That is, in a storage device having means for offsetting the tracking target position and means for measuring the number of test write bit errors (read error rate), data is written over three or more tracks in the test write area. The reading error rate is measured while offsetting the tracking target position in the central track between the tracks where data has been written. The reading error rate is deteriorated by increasing the offset of the tracking target position positively or negatively around the optimum tracking target position. Then, if the relationship between the tracking target position and the error rate is plotted, a substantially U-shaped curve is drawn. For example, the center of two tracking target positions exceeding a specified error rate is detected, and the result is stored in the memory as the optimum offset of the tracking target position. In subsequent reproduction processing, reproduction is performed by giving the optimum offset of the tracking target position to the servo loop.

  In the first method, data is written over three or more continuous tracks, but the signal power is increased by setting the write power at that time to a power increased by a specified amount with respect to the optimum write power obtained by the test write. Can be easily generated, and a substantially U-shaped curve can be narrowed to make the center more prominent. In this case, at least the both side tracks sandwiching the reading error are written with the increased power.

  In order to easily generate signal interference as described above, the specified amount power may be increased with respect to the optimum reproduction power.

  The power increased by the specified amount with respect to the optimum write power can be in the vicinity of the optimum write power difference between the write test track and the user track, which are known in advance. Alternatively, the write power may be increased or decreased by the write retry process, and the optimum write power may be increased by the increased width. As a result, the optimum write power can also be used for checking the amount of signal leakage in the adjacent track in the user track where user data is actually written.

  Conventional test write processing is performed to determine the optimum write power, and a substantially U-shaped curve of write power vs. read error rate is detected by measuring the write power vs. read error rate on a test track. . Here, the center of the substantially U-shaped curve is set as the optimum writing power, and the power immediately before the error rate starts to increase when the writing power is reduced with respect to the optimum writing power is stored as the minimum writing power. Also, when the optimum tracking target position is obtained with the data recorded with the write power increased by a specified amount, the width of the substantially U-shaped curve is narrower than the specified width or does not fall below the specified error rate. In such a case, the optimum write power may be reduced, the data may be written with a write power obtained by increasing the specified amount power relative to the power, and the measurement may be performed again. The optimum write power can be reduced to the minimum write power obtained by the test write process. On the other hand, if the width of the substantially U-shaped curve is too wider than the specified width, the specified amount power to be increased at the time of both-side track writing is further increased, the data is written, and the measurement is performed again.

  When measuring the reading error rate, the specified amount power is increased with respect to the optimum reproduction power, but the width of the substantially U-shaped curve when the optimum tracking target position is obtained is narrower than the prescribed width or If the error rate does not fall below the specified error rate, it is possible to reduce the reproduction power. Conversely, if the width of the substantially U-shaped curve is too wide than the specified width, the reproduction power can be increased.

  The optimum tracking target position obtained by the measurement as described above is the optimum condition at the time of reproduction, but the optimum tracking target position at the time of reproduction is obtained by performing the write operation in a state offset in advance to the opposite sign side of the same result. Can be set more centrally. As the offset amount at the time of writing, it is preferable to add a predetermined ratio or a value obtained by subtracting a predetermined amount instead of adding the reverse sign of the optimum tracking target position obtained by the first method as it is.

  The optimum tracking target position is measured for each zone of the optical recording medium or in units of areas with multiple zones as one area, and the measurement results corresponding to each zone or area are stored in memory during writing or playback processing. Alternatively, it may be read and used.

  Further, the optimum offset of the tracking target position corresponding to each rotation angle in one rotation of the optical recording medium may be stored in the memory for correction. In this case, a sector unit corresponding to the same rotation angle or a plurality of sectors is managed as a sector group (specified rotation angle unit), and an optimum offset is measured for each sector or sector group, so that one rotation of the optical recording medium is performed. Store in memory in corresponding table format. In the correction process for one rotation of the optical recording medium, it is possible to perform control so that the optimum offset of the stepwise tracking target position stored in the memory in a table format is smoothly and continuously corrected.

  The transition of the optimum offset of the tracking target position corresponding to each rotation angle in one rotation of the optical recording medium can be estimated from the surface shake of the optical recording medium. In this case, it is possible to detect the displacement amount of the focus actuator corresponding to the focus control amount and estimate the optimum offset from the transition state of the displacement amount. The displacement amount of the focus actuator can be obtained by calculating from the drive current of the focus actuator during focus control using the focus actuator characteristic, for example, the drive current versus displacement amount characteristic. In the correction process in one rotation of the optical recording medium, correction is performed using a preset optimum offset correction coefficient of the tracking target position with respect to the surface deflection of the optical recording medium. In this case, the measurement / correction operation as described above becomes unnecessary, and the measurement time is shortened. Further, the center value of the correction amount in this case is the measurement result when the optimum offset measurement of the tracking target position is measured over a multiple of one rotation of the optical recording medium. Alternatively, the center of the correction amount may be the absolute position of the focus actuator that can be obtained by calculation from a DC drive current of the focus actuator during focus control. In this case, it is necessary to measure and store calibration data measured in advance using an optical recording medium serving as a reference when the storage device is started up at a factory or the like.

  In the process of measuring the optimum offset of the tracking target position, the time and temperature are managed in each area, and when the elapsed time and / or temperature change amount from the previous execution reaches a specified value or more, the measurement is performed again. It is desirable. Since the temperature may not be measured correctly immediately after loading the optical recording medium, the reference value for elapsed time management should be set short, and readjustment should be performed relatively frequently immediately after loading. .

  If an error occurs during playback, it is possible to change the offset of the tracking target position from the optimum value to the positive side or the negative side by a specified amount and perform the playback process again. In such a retry process, the number of times when the reproduction is successful by offsetting to the positive side or the negative side is counted, and statistical processing is performed, and the optimum offset of the tracking target position is set to the positive side according to the success rate. Alternatively, a learning process for shifting to the negative side can be performed. Note that the learning process does not count in the confirmation (verify) process after writing so that it is not reflected in the statistical process.

  In the confirmation process after writing, the optimum offset may be corrected by an offset reduced by a certain amount or an offset reduced by a certain ratio with respect to the optimum offset of the tracking target position.

  When the reproduction process is performed using the optimum offset of the tracking target position, the optimum offset of the tracking target position of the area corresponding to the seek target track address can be set. Note that the offset is added by gradually increasing the offset until reaching the specified offset after the seek is completed, so that the tracking control does not become unstable. Also, at the start of seeking, an offset is given within the range that does not impair the seek pull-in performance, and the offset up to the optimum offset of the tracking target position can be gradually increased until the specified offset is reached after the seek operation is completed. It is. In this case, if the optimum offset of the tracking target position of the target track is within a range that does not impair the seek pull-in performance, the optimum offset of the tracking target position is added at the start of seek, and the addition of the offset after seek is unnecessary. Note that by gradually increasing the offset after seeking, the time from the start of seeking until the offset addition ends increases, and the apparent seek time becomes longer. Therefore, it is desirable to add the time during the addition of the optimum offset of the tracking target position to the actual seek time and use it for the rotation correction calculation.

  Therefore, according to the present invention, it is possible to realize a tracking control method and a storage device that can secure a desired recording / reproducing margin and realize high-density recording without providing a tilt correction mechanism or the like.

  According to the present invention, it is possible to realize a tracking control method and a storage device capable of ensuring a desired recording / reproducing margin without providing a tilt correction mechanism or the like. In addition, by measuring the optimum offset, even if tilt occurs, it is possible to position at the optimum tracking target position, and recording / reproducing processing can be performed at a highly accurate position, so that high-density recording / reproducing is possible. Become.

  Embodiments of the tracking control method according to the present invention and the storage device according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of the first embodiment of the storage device. As shown in the figure, the optical disc apparatus generally includes a control unit 110 and an enclosure 111. The control unit 110 is used to read / write data to / from an optical disk (not shown), an MPU 112 that performs overall control of the optical disk device, an interface 117 that exchanges commands and data with a host device (not shown). An optical disk controller (ODC) 114, a digital signal processor (DSP) 116, and a memory 118 that perform necessary processing are included. The memory 118 is shared by the MPU 112, the ODC 114, and the interface 117, and includes, for example, a dynamic random access memory (DRAM), a nonvolatile memory that stores a control program, flag information, and the like. The crystal unit 301 is connected to the MPU 112.

  The ODC 114 is provided with a formatter 114-1 and an error correction code (ECC) processing unit 114-2. At the time of write access, the formatter 114-1 generates a recording format by dividing the NRZ write data into sectors of the optical disk, and the ECC processing unit 114-2 generates and adds ECC for each sector write data. In response, a cyclic redundancy check (CRC) code is generated and added. Further, the ECC processing unit 114-2 converts the sector data after the ECC encoding into, for example, a 1-7 run length limited (RLL) code.

  At the time of read access, 1-7 RLL reverse conversion is performed on the sector data, and then the ECC processing unit 114-2 performs CRC, and then performs error detection and error correction by ECC. Further, the formatter 114-1 connects the NRZ data in units of sectors and transfers it to the host device as a stream of NRZ read data.

  A read / write large-scale integrated circuit (LSI) 120 is provided for the ODC 114, and the read / write LSI 120 includes a write modulator 121, a laser diode control circuit 122, a read demodulator 125, and a frequency synthesizer 126. The control output of the laser diode control circuit 122 is supplied to the laser diode unit 130 provided in the optical unit on the enclosure 111 side. The laser diode unit 130 integrally includes a laser diode 130-1 and a monitor detector 130-2. The write modulation unit 121 converts the write data into a data format in pit position modulation (PPM) recording (also referred to as mark recording) or pulse width modulation (PWM) recording (also referred to as edge recording).

  In this embodiment, data is recorded according to the presence or absence of a mark edge on the optical disk as an optical disk that records and reproduces data using the laser diode unit 130, that is, a rewritable magneto-optical (MO) cartridge medium. PWM recording is employed. The recording format of the optical disc is a 2.3 GB format using super-resolution technology (MSR) and adopts the ZCAV method. When an optical disk is loaded into the optical disk apparatus, the identification (ID) portion of the optical disk is first read, and the type of the optical disk (3.5 inch size, 128 MB, 230 MB, 540/640 MB, 1.3 GB,. 3GB,... Storage capacity, type, etc.), the type recognition result is notified to the ODC 14, and various parameters are set according to the type.

  As a read system for the ODC 114, a read / write LSI 120 is provided, and the read / write LSI 120 incorporates the read demodulator 125 and the frequency synthesizer 126 as described above. With respect to the read / write LSI 120, the received light signal of the return beam of the laser beam from the laser diode 130-1 by the ID / MO detector 132 provided in the enclosure 111 is sent via the head amplifier 134 to the ID signal (emboss pit signal). ) And the MO signal.

  The read demodulation unit 125 of the read / write LSI 120 is provided with circuit functions such as an automatic gain control (AGC) circuit, a filter, and a sector mark detection circuit. The read demodulation unit 125 reads a read clock from the input ID signal and MO signal. The read data is generated and the PWM data is demodulated into the original NRZ data. In addition, since the zone CAV is adopted, the MPU 112 performs frequency division ratio setting control for generating a clock frequency corresponding to the zone from the frequency synthesizer 126 built in the read / write LSI 120.

  The frequency synthesizer 126 is a phase-locked loop (PLL) circuit having a programmable frequency divider, and generates a reproduction reference clock having a specific frequency predetermined according to a zone position on the optical disc as a read clock. That is, the frequency synthesizer 126 is configured by a PLL circuit including a programmable frequency divider, and in the normal mode, the reference for recording / reproducing the frequency fo according to the frequency division ratio m / n set by the MPU 112 according to the zone number. The clock is generated according to fo = (m / n) · fi.

  Here, the frequency division value n of the denominator of the frequency division ratio m / n is a specific value corresponding to the type of the optical disc. The frequency division value m of the numerator of the frequency division ratio m / n is a value that changes in accordance with the zone position of the optical disc, and is prepared in advance as table information having a value corresponding to the zone number for each optical disc. . Further, fi represents the frequency of the recording / reproducing reference clock generated outside the frequency synthesizer 126.

  The read data demodulated by the read / write LSI 120 is supplied to the read system of the ODC 114, subjected to 1-7 RLL inverse conversion, and then subjected to CRC and ECC processing by the encoding function of the ECC processing unit 114-2. Restored to sector data. Next, the formatter 114-1 converts the NRZ sector data into a stream of NRZ read data, which is transferred from the interface 117 to the host device via the memory 118.

  A detection signal from a temperature sensor 136 provided on the enclosure 111 side is supplied to the MPU 112 via the DSP 116. The MPU 112 controls the read, write, and erase light emission powers in the laser diode control circuit 122 to optimum values based on the environmental temperature inside the optical disk device detected by the temperature sensor 136.

  The MPU 112 controls the spindle motor 140 provided on the enclosure 111 side by the driver 138 via the DSP 16. In this embodiment, since the recording format of the optical disk is the ZCAV system, the spindle motor 140 is rotated at a constant speed of 3637 rpm, for example.

  The MPU 112 controls the electromagnet 144 provided on the enclosure 111 side via the driver 142 via the DSP 116. The electromagnet 144 is disposed on the side opposite to the beam irradiation side of the optical disk loaded in the optical disk apparatus, and supplies an external magnetic field to the optical disk during recording and erasing. In a 1.3 GB or 2.3 GB format MSR optical disk using MSR, an external magnetic field is supplied even during reproduction.

  The DSP 116 has a servo function for positioning the beam from the laser diode 130 with respect to the optical disc, and functions as a seek control unit and an on-track control unit for seeking to the target track and performing on-track. This seek control and on-track control can be executed simultaneously in parallel with the write access or read access for the upper command by the MPU 112.

  In order to realize the servo function of the DSP 116, a focus error signal (FES) detector 145 for receiving beam return light from the optical disk is provided in the optical unit on the enclosure 111 side. The FES detection circuit 146 generates FESE 1 from the light reception output of the FES detector 145 and inputs the FESE 1 to the DSP 116.

  The optical unit on the enclosure 111 side is also provided with a tracking error signal (TES) detector 147 for receiving the beam return light from the optical disk. The TES detection circuit 148 generates TSE2 from the light reception output of the TES detector 147 and inputs it to the DSP 116. TSE2 is also input to the track zero cross (TZC) detection circuit 150, and a TZC pulse E3 is generated and input to the DSP.

  A lens position sensor 154 that detects the position of the objective lens that irradiates the optical disk with the laser beam is provided on the enclosure 111 side, and a lens position detection signal (LPOS) E4 from the lens position sensor 154 is input to the DSP 116. Is done. The DSP 116 controls and drives the focus actuator 160, the lens actuator 164, and the voice coil motor (VCM) 168 via the drivers 158, 162, and 166 in order to control the position of the beam spot on the optical disc.

  FIG. 2 is a cross-sectional view illustrating a schematic configuration of the enclosure 111. As shown in FIG. 2, a spindle motor 140 is provided in the housing 167. By inserting the MO cartridge 170 from the inlet door 169 side, the hub of the optical disk (MO disk) 172 housed in the MO cartridge 170 becomes the spindle. The optical disc 172 is loaded on the optical disc apparatus by being mounted on the turntable of the motor 140.

  Below the optical disk 172 in the loaded MO cartridge 170, a carriage 176 is provided that is movable in the direction crossing the track of the optical disk 172 by the VCM 164. An objective lens 180 is mounted on the carriage 176, and a beam from a laser diode 130-1 provided in the fixed optical system 178 enters through a rising mirror 182 to form a beam spot on the recording surface of the optical disk 172. Image.

  The objective lens 180 is controlled to move in the optical axis direction by the focus actuator 160 of the enclosure 111 shown in FIG. 1, and can be moved within the range of, for example, several tens of tracks in the radial direction across the track of the optical disk 172 by the lens actuator 164. is there. The position of the objective lens 180 mounted on the carriage 176 is detected by the lens position sensor 154 in FIG. The lens position sensor 154 sets the lens position detection signal to zero at a neutral position where the optical axis of the objective lens 180 is directly above, and moves with different curvatures for the movement of the optical disk 172 toward the outer side and the movement toward the inner side, respectively. A lens position detection signal E4 corresponding to the amount is output.

  FIG. 3 is a block diagram showing the main part of the first embodiment of the storage device according to the present invention. In the first embodiment of the storage device, a retry process is performed in which the present invention is retried until the writing succeeds by increasing / decreasing the recording (write) power as proposed in Japanese Patent Laid-Open No. 11-16251. It is applied to a magneto-optical disk device having a function. Further, the first embodiment of the storage device employs the first embodiment of the tracking control method according to the present invention.

  In FIG. 3, the magneto-optical disk apparatus is roughly composed of an MPU 112, a digital signal processor (DSP) 116, an optical head 3 including a laser diode, a photodetector section 4, amplifier / filter / offset adding circuits 5, 6, a binarizing circuit 7, It comprises drivers (drive circuits) 162 and 158, actuators 164 and 160, a memory 118 and a temperature sensor 136.

The MPU 112 controls the entire magneto-optical disk device. The memory 118 includes a ROM area for storing various data such as programs and tables executed by the MPU 112 and a RAM area for storing intermediate results of calculations executed by the MPU 112. The temperature sensor 136 detects the temperature in the magneto-optical disk device and supplies a temperature detection signal to the MPU 112.
The DSP 116 generally includes an analog / digital converter (ADC) 21, an amplifier 22, an offset addition circuit 23, a tracking control unit 24, a switch circuit 25, a digital / analog converter (DAC) 26, a counter 27, a speed detection unit 28, a seek. The control unit 29 includes a tracking error signal (TES) amplitude / offset detection circuit 31, a DAC 32, an ADC 41, an amplifier 42, a focus control unit 43, a focus actuator displacement detection unit 44, a sensitivity correction circuit 45, a switch 46, and a DAC 27. The magneto-optical disk 172 may be detachable. For convenience of explanation, FIG. 3 shows only the portion of the hardware and firmware of the DSP 116 that is directly related to the tracking control according to the present invention.

  Note that the magneto-optical disk drive system, the read / write (read / write) signal processing system, etc. are not directly related to the gist of the present invention, and therefore are not shown in FIG. The basic configuration of the magneto-optical disk apparatus is not limited to the basic configuration shown in FIG. 3, and various known basic configurations may be used as long as the processor such as the DSP 116 can perform an operation equivalent to the operation described later. Can do. 3, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 3, the component used for tracking control in the light beam irradiated from the optical head 3 onto the magneto-optical disk 9 and reflected from the magneto-optical disk 172 is detected by the TES detection unit of the photodetector unit 4. The detected tracking error signal (TES) is supplied to the binarization circuit 7 and the ADC 21 in the DSP 116 via the amplifier / filter / offset addition circuit 5. The optical head 3 and the photodetector 4 correspond to the laser diode unit 130, the ID / MO detector 132, the head amplifier 134, the FES detector 145, and the TES detector 147 shown in FIG. The amplifier / filter / offset addition circuit 5 has an amplifier (amplification) function, a filter function, and an offset addition function. The ADC 21 supplies the TES converted into the digital signal to the amplifier 22 and the TES amplitude / offset detection circuit 31. The TES amplitude / offset detection circuit 31 detects the positive-side peak value and the negative-side peak value of the TES and supplies them to the MPU 112.

  The MPU 112 performs an offset via the DAC 32 in the DSP 116 so that tracking control is performed near the center of the TES based on the positive peak value and the negative peak value of the TES obtained from the TES amplitude / offset detection circuit 31. Is supplied to the amplifier / filter / offset adding circuit 5 to correct the offset of the TES and to control the gain of the amplifier 22 in the DSP 116 so that the amplitude of the TES becomes a specified amplitude. As a result, a normalized TES in which the displacement amount with respect to the level of TES is normalized is obtained from the amplifier 22 and supplied to the offset adding circuit 23.

  The normalized TES from the amplifier 22 is added with an offset as described later in the offset adding circuit 23, and then supplied to the tracking control unit 24 including the function of the phase compensation filter. The tracking control unit 24 performs tracking control of the optical head 3, that is, the light beam, by controlling the track (lens) actuator 164 via the switch circuit 25, the DAC 26, and the driver 162 by a known method.

  The TES from the amplifier / filter / offset adding circuit 5 is binarized by the binarizing circuit 7 and supplied to the counter 27 in the DSP 116. The speed detector 28 detects the seek speed based on the output of the counter 27, and the seek controller 29 is supplied to the switch 25 as a signal for seek speed control based on the detected seek speed. Based on the signal from the MPU 112, the switch 25 is controlled to output a signal from the seek control unit 29 when the seek speed is controlled, and to output a signal from the tracking control unit 24 when tracking is on. At the time of tracking off, both signal outputs are cut off.

  On the other hand, of the light beam reflected from the magneto-optical disk 172, the component used for focus control is detected by the FES detection unit of the photodetector unit 4, and the focus error signal (FES) is supplied to the amplifier / filter / offset addition circuit 6. To the ADC 41 in the DSP 116. The amplifier / filter / offset addition circuit 6 has an amplifier (amplification) function, a filter function, and an offset addition function, similar to the amplifier / filter / offset addition circuit 5. The ADC 41 supplies the FES converted into the digital signal to the focus control unit 43 via the amplifier 42.

  The focus actuator displacement detection unit 44 detects the displacement of the focus actuator 160 during the focus control based on the output of the focus control unit 43, that is, the surface shake amount of the magneto-optical disk 172, and supplies it to the sensitivity correction circuit 45. The sensitivity correction value corresponding to the surface shake amount from the sensitivity correction circuit 45 is supplied to the offset addition circuit 23. The output of the focus control unit 43 controls the focus of the optical head 3, that is, the light beam, by controlling the focus actuator 160 via the switch circuit 46, the DAC 47 and the driver 158 by a known method. Based on the signal from the MPU 112, the switch circuit 46 is controlled so as not to supply the output of the focus control unit 43 to the DAC 47 when focus control is not performed.

  Next, an outline of tracking control of the present embodiment using the optimum offset of the tracking target position will be described. The process for obtaining the optimum offset of the tracking target position described later identifies the medium type of the loaded recording medium, and synchronizes with the test write process when the recording medium is a high-density recording medium of 3.5 inches 2.3 GB or more. Done. In the case of a low density recording medium of less than 2.3 GB, the optimum offset of the tracking target position is not obtained.

  First, the tracking target position offset is detected as follows. First, the test is performed with the optimum recording (write) power obtained by the test write processing as proposed in, for example, JP-A-9-293259, JP-A-11-73669, JP-A-11-16251, and the like. Write data to one write test track of the track. The test track on the magneto-optical disk 172 is at least one area provided for adjusting the power of the light beam by the test write process and the test read process, and no user data is written therein.

  Next, multiply the adjacent tracks where data is written with the optimum recording power by a count that increases the power by the specified ratio with respect to the optimum recording power, and use a recording power larger than the obtained optimum recording power, Write data under write conditions that are more likely to affect adjacent tracks. At this time, all three tracks may be written with a large recording power for the purpose of shortening the processing time. In the case of the magneto-optical disk 172 adopting the land / groove recording method, it is necessary to write data for at least four tracks so that the data written track exists on both sides in both the land reproduction and the groove reproduction. There is.

  The increase in recording power at this time is set to a level corresponding to the difference in optimum recording power between the write test track and the user track, or to an increase when the recording power is increased or decreased in the write retry process. Through the processing as described above, it is possible to confirm the amount of signal leakage in the adjacent track in the user track where user data is actually written.

  Next, the offset data supplied to the offset addition circuit 23 is reproduced while gradually increasing the offset data to be tracked to the positive side of the TES (for example, the outer direction of the magneto-optical disk 172), and the ECC processing unit 14 of the ODC 14 -2 is used to calculate the read data obtained by reading the write data written to the magneto-optical disk 172 from the result of bit comparison or byte comparison, and the number of bits or the number of byte errors or bits when the respective offsets are added Alternatively, the byte error rate or the number of ECC corrected bytes is measured. At this time, if the reproduction (read) power is increased by a specified amount or a specified ratio and measured in a state where it is more susceptible to the influence of adjacent tracks, the offset amplitude (the amount to be changed) of the tracking target position can be reduced. it can.

  For convenience, the following description describes the case where the number of bit errors is measured.

  FIG. 4 is a diagram showing the relationship between the offset of the tracking target position obtained by the measurement as described above and the number of bit errors. In the figure, the vertical axis indicates the number of bit errors in arbitrary units, the horizontal axis indicates the position on the magneto-optical disk 172, the left direction is the inner direction of the magneto-optical disk 172, and the right direction is the outer direction of the magneto-optical disk 172. Indicates. Also, in the figure, the point where the number of bit errors becomes greater than a specified value is defined as an offset a. Further, the offset data supplied to the offset adder circuit 23 is reproduced while gradually increasing the offset data to be tracked to the negative side of the TES (for example, the inner direction of the magneto-optical disk 172). A point that is equal to or greater than the value is set as an offset b. Then, the midpoint of the offset a and the offset b is set as the minimum point of the number of bit errors, and the optimum offset of the tracking target position.

  In FIG. 4, the measurement result is substantially U-shaped, but the minimum point of the number of bit errors may be detected as follows, assuming that the measurement result is, for example, substantially L-shaped. That is, the respective measurement results when the number of bit errors is measured by adding an offset to the positive side and the negative side are stored in the memory 118, and the time when the offset is the largest on the negative side is used as a reference for the offset 0. By integrating the number of bit errors from offset 0 to the positive offset maximum value, that is, offset n, and obtaining the average Ave of the number of bit errors, “(offset addition value at offset 0) + (measurement time) Offset change width × Ave) = offset that is the minimum number of bit errors ”.

  Regardless of the above, an offset of the tracking target position where the data reproduction characteristic seems to be optimized by some method may be used as the optimum offset of the tracking target position.

  If the number of bit errors is greater than the specified value even when the offset is changed, or if the number of bit errors is smaller than the specified value but the offset width that satisfies the specified value is narrow, the recording power or the reproduction power is reduced. Reduce and repeat measurement. The lower limit of the reproduction power is set to the optimum reproduction power, and a remeasurement process for measuring the number of bit errors in the offset addition state is performed. The lower limit of the recording power is the re-measurement process from the re-writing with the recording power increase or the recording power increase ratio, the recording power increased with respect to the minimum writable power obtained by the test write process. Do.

  On the other hand, if the offset with the number of bit errors smaller than the specified value is too wide than the specified value of a certain offset width, the recording power or the reproduction power is increased and the measurement process is performed again. Even if the recording power and the reproduction power are increased to a certain level, if the offset with the number of bit errors smaller than the specified value is too wide than the specified value of the offset width, the optimum offset of the tracking target position is set to zero.

  The above processing is managed and executed for each zone or each zone group of the magneto-optical disk 172. Since the above processing depends on the temperature change of the magneto-optical disk 172, the execution time and / or execution temperature is stored in the memory 118 for these zones, and the current time and / or current temperature is executed in the past. If there is a difference of more than the specified value from the time when the measurement is performed, the measurement process is performed again. Immediately after loading the magneto-optical disk 172 into the magneto-optical disk apparatus, the temperature change amount of the magneto-optical disk 172 with respect to time is relatively steep, so the execution time interval is set short and the elapsed time from loading is long. The longer is the execution time interval.

  The optimum offset of the tracking target position at the time of reproduction is obtained by the above processing, but the measurement result can be used also at the time of recording. At the time of recording, the optimum offset of the tracking target position at the time of reproduction obtained by the above measurement process can be reduced by setting the offset of the tracking target position with the opposite polarity to the optimum offset of the tracking target position at the time of reproduction. it can. When correcting the offset of the tracking target position at the time of writing, the influence of the offset is less empirically at the time of playback, and the risk is less when writing near the track center. The offset is smaller than the optimum offset.

  If the tracking target position is offset during writing, the optimum offset of the tracking target position during reproduction should be smaller than the optimum offset of the tracking target position added by the offset adding circuit 23. Therefore, it is necessary to correct the optimum offset of.

  In the above, the optimum offset of the tracking target position of one rotation unit of the magneto-optical disk 172 has been described. That is, in the measurement in units of one rotation of the magneto-optical disk 172, data is written to a track that is an integral multiple of one rotation (in this case, one time), and the data reproduction error of an integral multiple of one rotation of the magneto-optical disk 172 is offset. Is measured step by step to the positive / negative side to determine the optimum offset of the tracking target position.

  Hereinafter, a case where measurement is performed in units corresponding to the rotation angle within one rotation of the magneto-optical disk 172 will be described. In this case, the data reproduction error with respect to the offset is measured in sector units or sector group units divided in such a manner as to divide the rotation angle within one rotation of the magneto-optical disk 172. The actual writing process may be the same as in the case of the measurement for one rotation unit. That is, it is only necessary to set the management target in units of sectors or units of sectors. At this time, each data is discontinuous on the staircase, but if it is used at the time of playback, etc., if the data is corrected to continuous data and the offset is added smoothly. good.

  FIG. 5 is a diagram for explaining a case where measurement is performed in units corresponding to the rotation angle within one rotation of the magneto-optical disk 172. In the figure, (a) is a rotation synchronization signal synchronized with the rotation of the magneto-optical disk 172, (b) is a sector number, (c) is a data measurement result within one rotation, and (d) is after correction within one rotation. The data is shown.

  As another method for obtaining the optimum offset of the tracking target position, a characteristic that the surface shake amount and the tilt amount within one rotation of the magneto-optical disk 172 are in a proportional relationship may be used. The operation when the focus actuator 160 has the characteristics shown in FIG. 6 will be described with reference to FIG. In FIG. 6, (a) shows the relationship between the displacement of the focus actuator 160 and the actuator drive current frequency, that is, the actuator drive transfer function (spring support type), and the vertical axis and the horizontal axis are shown in arbitrary units. 6B is a diagram showing the relationship between the phase of the focus actuator 160 and the resonance frequency, and the vertical axis and the horizontal axis are shown in arbitrary units.

  The surface shake amount of the magneto-optical disk 172 can be known by detecting the displacement amount of the focus actuator 160 during focus control, that is, the focus control amount. The displacement amount of the focus actuator 160 can be obtained by calculating the drive current instruction value for the focus actuator 160 during focus servo by using the actuator drive transfer function. In the case of the spring-supported focus actuator 160, the drive current instruction value can be calculated using the following actuator drive transfer function. Here, Xf is a displacement amount of the focus actuator 160, Gf is an actuator drive transfer function of the focus actuator 160, If is a drive current of the focus actuator 160, Cf is a coil thrust coefficient of the focus actuator 160, mf is a mass of the focus actuator 160, Df is a damper coefficient of the focus actuator 160, and Kf is a spring coefficient of the focus actuator 160. Further, s is an operator generally used when solving a differential equation by Laplace transform, and when obtaining its frequency characteristic, s = jω = j2πf (ω is an angular frequency (rad / s), f is Frequency (Hz)).

Xf = Gf · If = Cf / (mf · s ² + Df · s + Kf)
The amount of displacement of the focus actuator 160 may be always calculated during one rotation of the magneto-optical disk 172, and the output multiplied by a certain coefficient may be corrected as the optimum offset of the tracking target position.

  In FIG. 7, (a) is a rotation synchronization signal synchronized with the rotation of the magneto-optical disk 172, (b) is a surface shake amount within one rotation, (c) is a drive current of the focus actuator 160, and (d) is one rotation. The data after correction is shown.

  At this time, an AC component of the displacement amount of the focus actuator 160 is detected, and the optimum offset transition of the tracking target position corresponding only to the AC component is averaged over one rotation obtained by the measurement in the unit of one rotation described above. Correction may be made by adding to the optimum offset of the target tracking target position. Alternatively, the measurement may not be performed in units of one rotation but may be corrected only by the optimum offset of the tracking target position corresponding to the displacement amount of the focus actuator 160 itself. At this time, it is necessary to calibrate the offset in a state where the distance between the neutral point of the focus actuator 160 and the magneto-optical disk 172 is known. When the offset is calibrated and stored in the memory 118 at the time of starting the magneto-optical disk device at the factory, the relative change amount from the stored value is corrected.

  As described above, it can be seen that there is a close relationship between the tracking target position offset and the data reproduction error. Here, in the retry process when a read error occurs during reproduction, there is a possibility that the sector in which the read error has occurred can be read by increasing or decreasing the offset of the tracking target position in the positive direction / negative direction. Therefore, it is desirable to set a mode in which the offset of the tracking target position is increased / decreased in the positive / negative directions during retry processing when a reading error occurs during reproduction. Then, it counts in each case whether the offset was successful when it was swung in the positive direction or when it was swung in the negative direction, and the count result was statistically processed at a certain specified timing, and the success ratio It is effective to perform a learning process in which the optimum offset of the tracking target position is memorized so that the direction becomes higher. Regarding the concept of the learning process, for example, a recording / reproducing power learning method is proposed in Japanese Patent Laid-Open No. 2000-182292, and the recording / reproducing power parameter may be replaced with an offset of the tracking target position.

  In the confirmation process after writing (verification), it is desirable to add the optimum offset of the tracking target position by reducing the specified amount. Also, during the retry process, it is desirable not to increase or decrease the offset of the tracking target position, or to make the increase / decrease amount smaller than that during normal playback. Further, it is desirable that the increase / decrease in the offset of the tracking target position is not a learning process target.

  The processing described above can be realized by the means shown in FIG. FIG. 8 is a functional block diagram showing the main part of FIG.

  8, the light emission adjusting unit 200 corresponds to the MPU 112 shown in FIG. 1, the optimum focus point detecting unit 207 corresponds to the DSP 116 shown in FIG. 3, and the in-device temperature detecting unit 208 corresponds to the temperature sensor 136 shown in FIG. To do. The light emission adjustment unit 200 includes a program or firmware having processing functions of an adjustment timing determination unit 202, a light emission power adjustment unit 203, an adjacent track and optimum tracking position confirmation unit 204, an optimum tracking position table creation unit 205, and a power table creation unit 206. Become.

  The adjustment timing determination unit 202 is activated by determining the recording power adjustment timing by the light emission power adjustment unit 203 based on the temperature detection signal from the apparatus temperature detection unit 208. The adjustment timing determination unit 202 does not start the recording power adjustment process immediately after the magneto-optical disk 172 is loaded into the magneto-optical disk apparatus, and the initialization process of the magneto-optical disk apparatus ends and the host device (not shown). When the first write command is issued from (), the light emission power adjustment unit 203 is activated in response to the first write command to perform the first light emission power adjustment process accompanied by the test write process. If the type is a high-density type of 2.3 GB or more, the adjacent track confirmation / optimum tracking position confirmation unit 204 is subsequently activated to check the presence / absence of data destruction in the adjacent track by the test write process using the determined recording power. At the same time, the optimum tracking position, that is, the optimum offset of the tracking target position is confirmed.

  Once the recording power adjustment processing by the light emission power adjustment unit 203 and the adjacent track confirmation / optimum tracking position confirmation unit 204 is completed, the effective time of the recording power adjustment result is calculated, and the elapsed time from the end of the adjustment is calculated. When the time (for example, increasing every 10 seconds, every 2 minutes, every 10 minutes according to the elapsed time) is reached, the light emission power adjustment unit 203 and the adjacent track confirmation and optimum tracking position confirmation unit for the next recording power adjustment The process 204 is sequentially activated. Also, when the in-device temperature T obtained from the in-device temperature detection unit 208 exceeds, for example, ± 3 ° C. until the elapsed time reaches the valid time, the light emission power adjustment unit 203 and the adjacent track are forcibly checked and optimized. The recording power adjustment process is performed by starting the tracking position confirmation unit 204.

  The light emission power adjusting unit 203 designates an arbitrary test write area of the loaded magneto-optical disk 172 which is not used by the user, and reads out a predetermined test pattern after writing the test power while gradually decreasing the recording power. Then, the process of counting the number of data mismatches is repeated in comparison with the original test pattern. In this test write process, the recording power when the counted number of mismatches exceeds a predetermined maximum number is detected as the limit recording power.

  When the limit recording power is detected while gradually reducing the recording power in this way, a value obtained by adding a predetermined offset to the limit recording power is determined as the optimum recording power. The setting of the recording power in the light emission power adjusting unit 203 is performed using a default ratio based on the recording power default value at that time. Therefore, the limit recording power is also detected as a default ratio indicating the limit recording power, and a value obtained by adding a predetermined offset value to this is determined as the default value of the optimum recording power.

  The adjacent track confirmation / optimum tracking position confirmation unit 204 performs test write processing in the test write region of the magneto-optical disk 172 by driving the laser diode using the recording power and erasing power determined by the light emission power adjustment unit 203. After performing the above, it is confirmed whether or not the data can be reproduced by reproducing the adjacent track, and whether or not the data is destroyed or deteriorated. When there is no data destruction or deterioration, the recording power and erasing power used for the test write process are set as the optimum recording power. The adjacent track confirmation / optimum tracking position confirmation unit 204 obtains the optimum tracking position based on the result of the optimum tracking position detection process. The optimum tracking position table creation unit 205 creates an optimum tracking position table based on the optimum tracking position obtained by the adjacent track confirmation and optimum tracking position confirmation unit 204. The power table creation unit 206 creates a power table based on the recording power determined by the light emission power adjustment unit 203 and the optimum recording power set by the adjacent track confirmation and optimum tracking position confirmation unit 204.

The processing procedure of the adjacent track confirmation / optimum tracking position confirmation unit 204 can be configured by the following steps (1) to (3). When the adjacent track confirmation process is normally completed, the test write area is erased.
(1) Test write the first test pattern to all tracks in the test write area,
(2) Test-write the second test pattern to the specific sector position of the specific track in the test write area a specified number of times,
(3) The sector adjacent to the sector on which the second test pattern is test-written is reproduced to check for the presence or absence of data corruption and to obtain the optimum tracking position.

  As described above, in this embodiment, the adjacent track confirmation and optimum tracking position confirmation unit 204 in the light emission adjustment unit 200 performs the optimum tracking position confirmation process in addition to the adjacent track confirmation process, and the optimum tracking position table creation unit 205 performs the optimum operation. Except for the creation of the tracking position table, the operation is basically the same as the operation of the functional block shown in FIG. 1A of the above-mentioned Japanese Patent Application Laid-Open No. 11-16251.

  Therefore, the disk activation process prior to the light emission power adjustment, the recording power adjustment process including the confirmation of the adjacent track, the necessity determination of the recording power adjustment, the recording power adjustment process by the test light and the adjacent track confirmation process are respectively described in This is the same as the flowchart shown in FIGS. 11, 12, 13, 14, and 20 of Japanese Patent No. 16251. However, in this embodiment, during the recording power adjustment process including the confirmation of the adjacent track shown in FIG. 12 of the above-mentioned JP-A-11-16251, step S5 ′ is performed by a test write as shown in FIG. In addition to the adjacent track confirmation process, the optimum tracking position confirmation process is performed. In FIG. 9, the same steps as those in FIG.

  The recording power obtained by the adjacent track confirmation process shown in FIG. 20 of the above Japanese Patent Laid-Open No. 11-16251 is set as the optimum power, and then the process shown in FIG. 10 is performed. FIG. 10 shows the minimum point of the number of bit errors by obtaining the midpoint of the increase point of the bit error number, that is, the midpoint of the offset a and the offset b in FIG. 4 from the measurement result of the bit error number having a substantially U-shaped curve. It is a flowchart explaining the process made into a point.

  In FIG. 10, step S11 performs test write processing on the measurement track with the optimum power, and step S12 performs test write processing on both adjacent tracks of the measurement track with power obtained by adding the offset to the optimum power. In step S13, data read processing is performed to reproduce data (test data) from the measurement track and its adjacent tracks. In step S14, the number of inconsistencies in the reproduced data is converted into, for example, a word unit, and in step S15, it is determined whether or not the number of data inconsistencies is equal to or less than a specified value. If the decision result in the step S15 is YES, a step S16 moves the tracking position to the inner side of the magneto-optical disk 172, and the process returns to the step S13.

    On the other hand, if the decision result in the step S15 is NO, a step S17 stores the tracking position (offset b), and a step S18 initializes the tracking position to the center value. Thereafter, in step S19, data read processing is performed in the same manner as in step S13, and in step S20, the number of data mismatches is converted into, for example, a word unit as in step S14. In step S21, as in step S15, it is determined whether the number of data mismatches is equal to or less than a specified value. If the decision result in the step S21 is YES, a step S22 moves the tracking position to the outer side of the magneto-optical disk 172, and the process returns to the step S19.

  If the decision result in the step S21 is NO, a step S23 saves the tracking position (offset a), a step S24 detects the midpoint of the saved tracking positions (offset a and b), and the process is ended. To do. The detected midpoint is the minimum point of the number of bit errors, that is, the optimum offset of the tracking target position.

  FIG. 11 is a diagram for explaining a recording format on the magneto-optical disk 172. As shown in the enlarged view at the bottom of the figure, one zone on the inner side of the magneto-optical disk 172 has a buffer 0 area A, a buffer 1 area B, a spare area C, a data track area (user Track area) DATA, buffer 2 area D, test write area E, buffer 3 area F, and buffer 4 area G are provided. When obtaining the optimum offset of the tracking target position, the test write area E is used as in obtaining the optimum power.

  Next, a process for adding the optimum offset of the tracking target position during actual reproduction or recording will be described with reference to FIGS. FIG. 12 is a flowchart for explaining the addition processing of the optimum offset of the tracking target position in the present embodiment. FIG. 13 is a diagram for explaining the optimum offset addition processing.

  The process shown in FIG. 12 is started when the MPU 112 receives a seek command for reproduction or recording from the host device. In step S31, it is determined whether or not a jump instruction associated with the received seek command has been issued. If the determination result is YES, step S32 reads the identification information (ID) portion on the magneto-optical disk 172. . In step S33, it is determined whether or not the reading of the ID portion is successful. If the determination result is NO, the process returns to step S32. On the other hand, if the decision result in the step S33 is YES, a step S34 decides whether or not it is necessary to add an offset of the tracking target position for the purpose of processing the seek command. If the decision result in the step S34 is NO, a step S35 sets an offset to 0 and an offset addition time to 0, and the process advances to a step S37.

  On the other hand, if the decision result in the step S34 is YES, the optimum offset of the tracking target position is read from the memory 118, an offset corresponding to either the reproduction or recording process is calculated and set, and the offset addition time is set. Calculate and set, and the process proceeds to step S37. A step S37 decides whether or not a seek has been executed. If the decision result in the step S37 is NO, the process advances to a step S40 described later. If the decision result in the step S37 is YES, a step S38 adds the set offset, and the step S38 decides whether or not the target track included in the seek command has been reached.

  If the decision result in the step S39 is NO, a step S40 calculates the number of tracks to be jumped to reach the target track, and the step S41 executes a jump of the calculated number of tracks. In step S42, it is determined whether or not the jump is successful. If the determination result is NO, step S43 executes redrawing to the track, and the process returns to step S32. If the decision result in the step S42 is YES, the process returns to the step S32. If the decision result in the step S39 becomes YES, the process ends.

  Therefore, if it is determined in step S34 that no offset is required, the current track is confirmed and the distance to the target track is calculated. In this case, rotation correction is performed and an optimal number of jumps is set. Then, the jump is started. When the jump is finished, it is confirmed whether the target track has been reached. If not, the jump is performed again, and finally the target track is positioned as in the conventional case.

  On the other hand, if it is determined in step S34 that an offset needs to be added, the current track is confirmed and the distance to the target track is calculated. Also in this case, rotation correction is performed, an optimal number of jumps is set, and the time required for offset addition processing after the end of seek is added to the correction processing. Thereafter, when the jump starts and ends, the offset is gradually added and increased to the target offset. Then, it is confirmed whether or not the target track has been reached, and if not, a process of jumping again is performed, and finally the target track is positioned. When correcting for one rotation of the magneto-optical disk 172, data corresponding to one rotation is transferred, the offset is added to the average value of the offset for one rotation, and then the data for one rotation is rotated. Automatically output in sync with.

  FIG. 13A shows a tracking error signal during seek, and FIG. 13B shows an offset added by the addition processing of the optimum offset of the tracking target position accompanying the seek.

  The target track confirmation process and the offset addition process can be executed in parallel as described above.

  Next, the optimum offset addition processing for the tracking target position during actual reproduction or recording in the second embodiment of the storage device according to the present invention will be described with reference to FIGS. The basic configuration of the second embodiment of the storage device is the same as the configuration shown in FIG. FIG. 14 is a flowchart for explaining the addition processing of the optimum offset of the tracking target position in this embodiment. FIG. 15 is a diagram for explaining the optimum offset addition process. 14, the same steps as those in FIG. 12 are denoted by the same reference numerals, and the description thereof is omitted.

  In FIG. 14, if the decision result in the step S37 is YES, a step S51 proceeds to the process of the step S39 after adding the remaining offset. Further, after step S41, step S52 adds the set offset, and step S53 proceeds to the processing of step S42 after finishing the jump.

  Therefore, if the offset does not impair the seek operation margin, the offset is already added at the time of seeking. If the target offset, that is, the optimum offset registered in a memory such as the memory 118 is large, the difference from the offset added at the time of seek pull-in is gradually added after the seek is completed.

  FIG. 15 (a) shows a tracking error during seeking, and FIG. 15 (b) shows an offset added by the optimum offset addition processing of the tracking target position accompanying the seek.

  FIG. 16 is a diagram showing the relationship between the radial tilt at the time of recording on the land of the magneto-optical disk 172 and the amount of movement of the actuator 164 that minimizes the bit error rate (BER) (BERmin). In the figure, the vertical axis shows the movement amount (μm) of the track actuator 164 with the BER being the minimum (BERmin), the plus side is the movement amount in the outer direction of the magneto-optical disk 172, and the minus side is the movement amount in the inner direction. The horizontal axis indicates the radial tilt (min) at the time of reading. In addition, □ indicates a radial tilt during writing of −10 min, ● indicates a radial tilt during writing of 0 min, and Δ indicates a case where the radial tilt during writing is +10 min.

  FIG. 17 is a diagram showing the relationship between the radial tilt at the time of recording in the groove of the magneto-optical disk 172 and the amount of movement of the actuator 164 that minimizes the BER (BERmin). In the figure, the vertical axis shows the movement amount (μm) of the track actuator 164 with the BER being the minimum (BERmin), the plus side is the movement amount in the outer direction of the magneto-optical disk 172, and the minus side is the movement amount in the inner direction. The horizontal axis indicates the radial tilt (min) at the time of reading. In addition, □ indicates a radial tilt during writing of −10 min, ● indicates a radial tilt during writing of 0 min, and Δ indicates a case where the radial tilt during writing is +10 min.

  FIG. 18 is a diagram showing the relationship between the radial tilt and the intensity distribution of the light beam. (A) in the figure shows a radial tilt of -10 min during writing, (b) shows a radial tilt during writing of 0 min, and (c) shows the intensity of the light beam when the radial tilt of writing is +10 min. Each distribution is shown. In the figure, the upper side shows the magneto-optical disk 172, the objective lens 300 of the optical head 3, and the light beam 301, and the lower side shows the intensity distribution of the light beam 301 on the magneto-optical disk 172. The arrow indicates the direction of movement of the actuator 164 that minimizes the BER (BERmin). Here, the optical head 3 uses a laser diode that emits a light beam 310 having a wavelength of 660 nm, and the numerical aperture (NA) of the objective lens 300 is 0.55. In addition, a double mask rear aperture detection (RAD) method is adopted.

  As can be seen from FIGS. 16 to 18, the influence of the radial tilt at the time of writing seems to be smaller than the influence at the time of reading. Further, it was confirmed that the tracking target position was offset (detracked) in the direction in which the intensity of the light beam 301 was increased.

  In the above case, it is assumed that an offset is injected in advance so that the track center becomes the tracking target position at the factory, and this tracking target position is set as offset 0. Further, if there is a tilt, there is a possibility that the position is shifted from the track center. Therefore, the optimum target position is searched and a corresponding offset is given.

  As described above, in addition to obtaining the optimum offset based on the error rate, the optimum offset may be obtained by monitoring the reproduction signal amplitude or the like.

  The measurement result obtained in the above embodiment is cleared when the magneto-optical disk 172 is ejected (unloaded).

  In the above embodiment, considering the compatibility with the conventional apparatus, the function of the present invention is not operated for a low-density recording medium of less than 2.3 GB, for example. If this is not considered, the function of the present invention may be operated on a low-density recording medium. At this time, as a method for determining the type of the recording medium, in addition to the method for determining the type from the pits in the ID section as described above, a method of reading the medium information in the control information area can be adopted.

  The present invention is not limited to the application to the magneto-optical disk device, but uses other types of optical recording media such as magneto-optical and phase-change type optical recording media and magneto-optical properties using optical beams. Needless to say, the present invention can also be applied to a storage device using a magnetic recording medium that records information in accordance with this change.

  The present invention includes the inventions appended below.

(Supplementary note 1) A measurement step of measuring the light beam irradiation state while offsetting the tracking target position of the light beam on the recording medium and measuring the optimum offset so as to be the tracking target position of the optimum light beam irradiation state;
And a control step of performing tracking control by setting the optimum offset measured in the measurement step.

    (Additional remark 2) It further includes the discrimination | determination step which discriminate | determines the classification of the said recording medium, The said measurement step is performed when it is discriminate | determined in the said discrimination | determination step that the said recording medium is a high-density recording medium, It is characterized by the above-mentioned. The tracking control method according to (Appendix 1).

    (Supplementary Note 3) The tracking according to (Supplementary Note 1) or (Supplementary Note 2), wherein the measurement step detects an irradiation state of the light beam based on a reading error situation, a reproduction signal amplitude, or a focus control amount. Control method.

    (Appendix 4) The tracking control method according to any one of (Appendix 1) to (Appendix 3), wherein the measurement step is executed in a state in which waveform interference from an adjacent track is likely to occur.

    (Appendix 5) Any one of (Appendix 1) to (Appendix 4), wherein the measurement step is executed for each radial position of the recording medium and / or for each rotation angle of the recording medium. The tracking control method according to claim 1.

    (Additional remark 6) The said measurement step is performed when the difference of the measurement execution time of last time and this time is more than regulation time, and / or when the temperature difference of the measurement execution time of the last time and this time is more than regulation temperature. The tracking control method according to any one of (Appendix 1) to (Appendix 5).

    (Additional remark 7) When the error generate | occur | produces at the time of the reproduction | regeneration processing of the said recording medium, the reproduction | regeneration processing step which changes the optimal offset of a tracking target position to the positive side or a negative side, and performs reproduction | regeneration processing again is characterized by the above-mentioned. The tracking control method according to any one of (Appendix 1) to (Appendix 6).

    (Supplementary Note 8) The tracking control according to (Appendix 7), wherein in the reproduction processing step, the optimum offset of the tracking target position is changed to a positive side or a negative side according to a success rate of the reproduction processing to be performed again. Method.

    (Supplementary Note 9) The tracking control method according to any one of (Supplementary Note 1) to (Supplementary Note 8), further comprising a setting step of setting an optimum offset according to the purpose of the seek process and the target address.

(Supplementary note 10) Offset measurement control means for measuring the light beam irradiation state while offsetting the tracking target position of the light beam on the recording medium and measuring the optimum offset so as to be the tracking target position in the optimum light beam irradiation state;
And a tracking control unit configured to perform tracking control by setting the updated optimum offset.

    (Additional remark 11) It further has a discriminating unit for discriminating the type of the recording medium, and the offset measurement control unit measures the optimum offset when the discriminating unit discriminates that the recording medium is a high-density recording medium. The storage device according to (Appendix 10), wherein:

(Supplementary note 12) Measuring means for measuring the light beam irradiation state while offsetting the tracking target position of the light beam on the recording medium and measuring the optimum offset so as to be the tracking target position of the optimum light beam irradiation state;
A storage device comprising: control means for performing tracking control by setting the optimum offset measured by the measuring means.

    (Additional remark 13) It further has a discriminating means for discriminating the type of the recording medium, and the measuring means measures the optimum offset when the discriminating means discriminates that the recording medium is a high density recording medium. The storage device described in (Appendix 12).

    (Supplementary Note 14) The memory according to (Supplementary Note 12) or (Supplementary Note 13), wherein the measurement unit detects an irradiation state of the light beam based on a reading error situation, a reproduction signal amplitude, or a focus control amount. apparatus.

    (Supplementary Note 15) The storage according to any one of (Supplementary Note 12) to (Supplementary Note 14), wherein the measurement unit measures the optimum offset in a state where waveform interference from an adjacent track is likely to occur. apparatus.

    (Supplementary Note 16) The measurement means measures the optimum offset for each radial position of the recording medium and / or for each rotation angle of the recording medium (Appendix 12) to (Appendix 15) The storage device according to any one of the above.

    (Supplementary Note 17) The measurement unit measures the optimum offset when the difference between the previous and current measurement execution times is equal to or greater than the specified time and / or when the temperature difference between the previous and current measurement executions is equal to or greater than the specified temperature. The storage device according to any one of (Appendix 12) to (Appendix 16).

    (Additional remark 18) When the error generate | occur | produced at the time of the reproduction | regeneration processing of the said recording medium, it further provided with the reproduction | regeneration processing means which changes the optimal offset of a tracking target position to a positive side or a negative side, and performs a reproduction | regeneration process again. The storage device according to any one of (Appendix 12) to (Appendix 17).

    (Supplementary note 19) The storage device according to (Appendix 18), wherein the reproduction processing means changes the optimum offset of the tracking target position to a positive side or a negative side according to a success rate of a reproduction process to be performed again. .

    (Appendix 20) The storage device according to any one of (Appendix 12) to (Appendix 19), further comprising setting means for setting an optimum offset in accordance with the purpose of the seek process and the target address.

  As mentioned above, although this invention was demonstrated by the Example, this invention is not limited to the said Example, It cannot be overemphasized that various deformation | transformation and improvement are possible.

It is a block diagram which shows 1st Example of the memory | storage device which becomes this invention. It is sectional drawing which shows schematic structure of an enclosure. It is a block diagram which shows the principal part of 1st Example of the memory | storage device which becomes this invention. It is a figure which shows the relationship between the offset of a tracking target position, and the number of bit errors. It is a figure explaining the case where a measurement is performed by the unit equivalent to the rotation angle within 1 rotation of a magneto-optical disk. It is a figure which shows the characteristic of a focus actuator. It is a figure explaining operation | movement in case a focus actuator has the characteristic shown in FIG. It is a functional block diagram which shows the principal part of FIG. It is a flowchart explaining the recording power adjustment process including confirmation of an adjacent track. It is a flowchart explaining the process which calculates | requires the midpoint of the increase point of the number of bit errors. It is a figure explaining the recording format on a magneto-optical disk. It is a flowchart explaining the addition process of the optimal offset of a tracking target position. It is a figure explaining the addition process of optimal offset. It is a flowchart explaining the addition process of the optimal offset of the tracking target position in 2nd Example of the memory | storage device which becomes this invention. It is a figure explaining the addition process of optimal offset. It is a figure which shows the relationship between the radial tilt at the time of recording on a land, and the moving amount | distance of the actuator which makes bit error rate the minimum. It is a figure which shows the relationship between the radial tilt at the time of recording on a groove | channel, and the moving amount | distance of the actuator which makes bit error rate the minimum. It is a figure which shows the relationship between radial tilt and intensity distribution of a light beam.

Explanation of symbols

23 Offset addition circuit 31 TES amplitude / offset detection circuit 44 Focus actuator displacement detection unit 112 MPU
116 DSP
118 Memory 172 Magneto-optical disk 200 Light emission adjustment unit 204 Adjacent track and optimum tracking position confirmation unit 205 Optimal tracking position table creation unit

Claims (6)

A measurement step of measuring the light beam irradiation state while offsetting the tracking target position on the recording medium of the light beam and measuring the optimum offset so as to be the tracking target position of the optimum light beam irradiation state;
And a control step of performing tracking control by setting the optimum offset measured in the measurement step.   The tracking control method according to claim 1, wherein the measuring step detects an irradiation state of the light beam based on a reading error situation, a reproduction signal amplitude, or a focus control amount.   The tracking control method according to claim 1, wherein the measuring step is executed for each radial position of the recording medium and / or for each rotation angle of the recording medium.   The measurement step is performed when the difference between the previous and current measurement execution times is greater than or equal to a specified time and / or when the temperature difference between the previous and current measurement executions is greater than or equal to a specified temperature. Item 4. The tracking control method according to any one of Items 1 to 3.   2. The reproduction processing step according to claim 1, further comprising a reproduction processing step of changing the optimum offset of the tracking target position to the positive side or the negative side and performing the reproduction processing again when an error occurs during the reproduction processing of the recording medium. The tracking control method of any one of -4.   6. The tracking control method according to claim 5, wherein in the reproduction processing step, the optimum offset of the tracking target position is changed to a positive side or a negative side according to a success rate of a reproduction process to be performed again.

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