WO2002061744A1 - Disc recorder/reproducer - Google Patents

Disc recorder/reproducer Download PDF

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Publication number
WO2002061744A1
WO2002061744A1 PCT/JP2002/000612 JP0200612W WO02061744A1 WO 2002061744 A1 WO2002061744 A1 WO 2002061744A1 JP 0200612 W JP0200612 W JP 0200612W WO 02061744 A1 WO02061744 A1 WO 02061744A1
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WO
WIPO (PCT)
Prior art keywords
power
temperature
signal
laser power
laser
Prior art date
Application number
PCT/JP2002/000612
Other languages
French (fr)
Japanese (ja)
Inventor
Kenji Asano
Shuji Sakai
Hideharu Baba
Original Assignee
Sanyo Electric Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sanyo Electric Co., Ltd. filed Critical Sanyo Electric Co., Ltd.
Publication of WO2002061744A1 publication Critical patent/WO2002061744A1/en

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
    • G11B7/126—Circuits, methods or arrangements for laser control or stabilisation
    • G11B7/1267—Power calibration
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
    • G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
    • G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
    • G11B11/10595—Control of operating function

Definitions

  • the present invention relates to a disk recording / reproducing apparatus which irradiates a disk with laser light from an optical head to record a signal on the disk or reproduce a signal from the disk.
  • the land (17) and the group (18) meander (opple) as shown in the figure.
  • the meandering frequency is FM-modulated at a predetermined center frequency, and this signal is detected by signal reproduction.
  • the linear velocity constant control is realized by adjusting the rotation of the magneto-optical disk so that the wobble signal always has the center frequency.
  • the fobble signal is subjected to FM modulation as described above, and contains various information (fobble information) such as address information. At the time of signal reproduction, various control operations are realized based on the fobble information. Is done.
  • a disk recording / reproducing apparatus of a laser pulse magnetic field modulation type when reproducing a signal, the magneto-optical disk is irradiated with laser light, and at the time of recording a signal, the magneto-optical disk is irradiated with laser light.
  • the disk is locally heated.
  • the laser power for signal reproduction is reduced.
  • the signal reading is started when the temperature of the beam spot area reaches a predetermined value, but the laser power during signal reproduction is set lower than the laser power during signal recording. Therefore, there is no possibility that the recorded signal is damaged by the signal reproduction.
  • the laser temperature gradually increases due to the irradiation of the laser beam, and the optimum recording power and the optimum reproducing power change accordingly. Therefore, even if the laser power is optimal at the time of starting the system, the laser power deviates from the optimal value in the normal operation thereafter, and there is a problem that normal signal recording and signal reproduction become difficult.
  • This problem can be solved by a method of constantly monitoring the temperature and optimizing the laser power every time a temperature change occurs.However, arithmetic processing for the optimization is frequently performed. Since this method needs to be repeated, there is a problem that this method is difficult to realize.
  • An object of the present invention is to provide a disk recording / reproducing apparatus which can always set an optimum laser power according to a change in disk temperature.
  • a disk recording / reproducing apparatus includes a laser driving circuit capable of supplying a driving signal to an optical head and adjusting the power of laser light emitted from an optical head; It has an evaluation data detection circuit for detecting evaluation data indicating the quality of the signal reproduction state, and a control circuit for controlling the operation of the laser drive circuit based on the output of the evaluation data detection circuit.
  • the control circuit includes: a temperature detecting means for detecting a temperature of the disk; a laser power optimizing means for optimizing a laser beam power at the time of signal recording or signal reproduction so that the evaluation data does not exceed a specified value; Table means for storing the relationship between temperature and optimum laser power, table registration means for registering disk temperature and optimum laser power in the table means, and optimum laser power for deriving optimum laser power according to disk temperature from the table means Deriving means.
  • the optimization of the laser power is performed at the time of startup and during the normal operation, and the relationship between the disk temperature and the optimum laser power is stored in the table means. If the optimum laser power is already registered in the table, it is no longer necessary to optimize the laser power, but only the optimum laser power at that temperature is read from the table means and set. Therefore, the processing load is reduced compared to a disk recording / reproducing apparatus that optimizes the laser power every time a temperature change occurs.
  • the optimum value is calculated according to the above, the amount of arithmetic processing required to register all data (relationship between temperature and optimum laser power) in the table means is greatly reduced.
  • the signal It is possible to find a substantially optimal laser power that does not hinder recording and reproduction of signals.
  • the table registration means further includes, for a temperature at which optimization by the laser power optimization means or interpolation by the arithmetic processing means has not been performed, a nearby temperature already determined by optimization or interpolation.
  • an approximate value calculating means for calculating an approximate value of the optimum laser power based on the optimum laser power and predetermined temperature gradient data indicating a ratio of the change of the optimum laser power to the temperature change.
  • the temperature of the neighboring temperature obtained by the optimization or the interpolation is calculated.
  • An approximate value of the optimum laser power is calculated based on the optimum laser power and predetermined temperature gradient data indicating a rate of change of the optimum laser power with respect to the temperature, and the relationship between the temperature and the approximate value of the optimum laser power is calculated. Is stored in the table means.
  • the temperature becomes a temperature at which the laser power has not been optimized by optimization or interpolation, and when the optimum laser power is calculated at that temperature, the approximate value is replaced by the optimum laser power.
  • an interpolation process using the optimum laser power at that temperature is further performed, and the table means is updated. Therefore, the optimal laser power at each temperature or its approximate value is always registered in the table means, and the approximate value is gradually replaced with the optimal value.
  • the reproduction power changes as shown in Fig. 15 to change the error rate of the reproduction signal in a quadratic curve.
  • the error rate becomes the minimum value.
  • the laser power at the time of signal reproduction is the lower limit reproducing power P r min and the upper limit reproducing power P r max, which are two limit values at which the error rate falls below the specified value.
  • the reproduction power Pr at which the error rate falls below the specified value depends on the recording power P w at which the error rate falls below the specified value, as shown in FIG.
  • the limit reproduction power Pr at which the error rate falls below the specified value varies according to the recording power. Therefore, if the average value of the lower limit recording power P wmin and the upper limit recording power P wmax at which the error rate falls below the specified value within this recording power range is defined as the optimum reproduction power, The value is a position that is greatly deviated from the center position of the range shown in Fig. 17, and if the characteristics shown in Fig. 17 fluctuate, the playback rate greatly deviates from the optimum value, and the error rate is specified.
  • the error rate must be lower than a specified value. After searching for the lower limit reproduction power P r min, by adding a predetermined value to the searched lower limit reproduction power P r min, The optimum reproduction power was calculated.
  • the predetermined value is an area where the reproduction power does not depend on the recording power in the relationship shown in FIG. 17, that is, the maximum reproduction power of 2.58 mW and the minimum reproduction power of 1.84 when the recording power is 8.OmW or more. 0.36 mW, which is one half of the difference in mW, or a value close to it (for example, 0.4 mW) can be adopted. As a result, an optimum value can be obtained for the reproduction power that does not depend on the recording power.
  • the lower limit reproduction power Prmin also changes to Prmin 'or Prmin ", and the optimum values Pr, Pr' and Pr" and the lower limit reproduction power P rmin, Prmin 'and Prmin "have a substantially constant value N.
  • N By adding this difference N to the lower limit reproduction power Prmin, Prmin' and Prmin" It is possible to obtain the optimum reproduction powers Pr, Pr ′ and Pr ′′, respectively.
  • P rtnin instead of adding the predetermined value N to the lower limit reproduction power P rtnin, by multiplying by the predetermined value ⁇ . In this case, it is also possible to similarly obtain accurate optimum reproduction powers Pr, Pr 'and Pr ".
  • FIG. 1 is a block diagram showing a configuration of a disk recording / reproducing apparatus according to the present invention.
  • FIG. 2 is a flowchart showing a procedure of laser power control in the apparatus.
  • FIG. 3 is a flowchart of the test read Z write and management table update routine.
  • FIG. 4 is a flowchart showing a control procedure of the recording / reproducing operation in the normal operation.
  • FIG. 5 is a chart for explaining the data structure of the management table.
  • FIG. 6 is a chart showing a specific example of updating the management table.
  • FIG. 7 is a graph showing the relationship between the temperature of the management table and the laser power at the time of startup.
  • Fig. 8 is the same graph as the management table for the first test read / write.
  • Figure 9 shows the same draft of the management table in the second test read / write.
  • FIG. 10 is a flowchart showing the procedure of the reproduction power optimization.
  • FIG. 11 is a flowchart showing a procedure for optimizing the recording power.
  • FIG. 12 is a flowchart showing another procedure of the recording power optimization.
  • FIG. 13 is a graph for explaining the procedure of reproducing power optimization.
  • FIG. 14 is a graph showing the relationship between the reproduction power and the error rate.
  • FIG. 15 is a graph illustrating the principle of read power optimization.
  • FIG. 16 is a graph illustrating the principle of recording power optimization.
  • FIG. 17 is a diagram showing the relationship between the recording power and the reproduction power satisfying the specified value.
  • FIG. 18 is a waveform diagram of two reference signals written in the header part of the reproduction signal.
  • FIG. 19 is a graph showing the relationship between the amplitude ratio of the reproduction signals of both reference signals and the reproduction power.
  • FIG. 20 is an enlarged perspective view showing lands and groups formed on the magneto-optical disk.
  • a disk recording / reproducing apparatus comprises a spinning device for rotating a magneto-optical disk (1). It has a dollar motor (2). A temperature sensor (16) is mounted near the magneto-optical disk (1).
  • the signal reproduction system includes a laser drive circuit (15), an optical head (4), a reproduction signal amplification circuit (5), a reproduction signal detection circuit (7), and an error correction circuit (11).
  • the optical head (4) is driven by the laser drive circuit (15), and the magneto-optical disk (1) is irradiated with laser light.
  • a magnetic head drive circuit (14) and a magnetic head (3) are provided as a signal recording system.
  • the laser drive circuit (15) and the optical head (4) correspond to the magneto-optical disk (1). Operates to locally heat the.
  • the control system includes a servo circuit (6), an external synchronization signal generation circuit (8), a system controller (10), a memory (9), a delay circuit (12), and a timing pulse generation circuit (13). I have.
  • the optical head (4) irradiates the laser beam to the magneto-optical disk (1) and detects the reflected light as an optical signal and a magneto-optical signal.
  • the reproduction signal amplification circuit (5) amplifies the optical signal and magneto-optical signal obtained from the optical head (4), and then supplies the focus error signal and tracking error signal included in the optical signal to the servo circuit (6). I do.
  • the reproduction signal amplification circuit (5) supplies an optical signal detected due to the discontinuous area formed at a constant interval in the group of the magneto-optical disk (1) to the external synchronization signal generation circuit (8). At the same time, the magneto-optical signal is supplied to the reproduction signal detection circuit (7).
  • the external synchronizing signal generation circuit (8) generates an external synchronizing signal and supplies it to the servo circuit (6) and the delay circuit (12).
  • the servo circuit (6) executes a focus servo and a tracking servo for an actuator (not shown) provided in the optical head (4) based on the focus error signal and the tracking error signal, and generates an external synchronization signal. Based on the control of the rotation of the spindle motor (2).
  • the reproduction signal detection circuit (7) supplies the detected reproduction signal to the error correction circuit (11), and the error correction circuit (11) demodulates the reproduction signal and generates an error in the reproduction data obtained thereby. , And after correcting the error, playback to the subsequent circuit after correction Output data.
  • the delay circuit (12) generates a synchronization signal in which the phase of the external synchronization signal is delayed for a fixed time, and outputs it to the timing pulse generation circuit (13).
  • the timing pulse generator circuit (13) When recording a signal, receives recording data modulated by a predetermined method and a synchronization signal from the delay circuit (12), and applies an alternating magnetic field to the magneto-optical disk (1). A pulse signal (write clock) for irradiating the magneto-optical disk (1) with pulse light is generated, and a pulse signal (write clock) for irradiating the magneto-optical disk (1) with pulse light is generated. ).
  • the reproduced signal detection circuit (7) converts the reproduced analog signal into a digital signal based on the synchronization signal (read clock) from the delay circuit (12).
  • the magnetic head drive circuit (14) creates a drive signal for the magnetic head (3) based on the pulse signal from the timing pulse generation circuit (13).
  • the magnetic head (3) applies an alternating magnetic field to the magneto-optical disk (1) based on a drive signal from a magnetic head drive circuit (14).
  • the laser drive circuit (15) drives a semiconductor laser (not shown) provided in the optical head (4) based on a pulse signal from the timing pulse generation circuit (13).
  • the optical head (4) generates a laser beam based on a drive signal from the laser drive circuit (15) and irradiates the magneto-optical disk (1).
  • the system controller (10) controls the operation of the delay circuit (12) based on the external synchronization signal obtained from the external synchronization signal generation circuit (8).
  • the system controller (10) calculates the bit error rate based on the error correction information obtained from the error correction circuit (11), and controls the operation of the laser drive circuit (15) according to the result. . Further, the system controller (10) compares the temperature data obtained from the temperature sensor (16) with the optimum read power and the optimum write power obtained by the test read and test write described later in the memory (9). The information is accumulated in a management table, and at the time of signal reproduction and signal recording, the laser power is controlled with reference to the management table.
  • the laser drive circuit responds to a laser power control signal Cp supplied from the system controller (10) to emit laser light from the optical head (4) during signal reproduction. Is adjusted as described below.
  • a laser power control signal Cp supplied from the system controller (10) to emit laser light from the optical head (4) during signal reproduction. Is adjusted as described below.
  • the management table as shown in FIG. 5, for each temperature, the read power Pr, the write power Pw, the flag TestRW indicating whether the test read / write has been executed, and the interpolation processing described later. A flag indicating whether the temperature has been actually experienced and a flag indicating whether the temperature has actually been experienced are stored.
  • Fig. 2 shows the overall flow of the procedure executed by the system controller (10). First, when a new magneto-optical disk is inserted in step S1, in step S2, after clearing the previous management table, the relationship between the temperature and the laser power (Pr or Pw) is determined.
  • step S3 the initial temperature T-initial is detected.
  • step S4 the starting temperature is determined from the predetermined reference temperature Tdef, the reference laser powers Pwdef and Prdef, and the initial temperature T-initial. Ask for laser power.
  • step S5 the initial temperature T—initial is set to the current temperature T and the internal temperature held by the system, and the test read Z write and management table update routine in step S6 is executed.
  • the test read / write and management table update routine as shown in FIG. 3, in step S21, a test read and a test write (Test RW) are performed using a predetermined test track to optimize the test. Calculate the laser power Pr, Pw. Then, in step S23, based on the calculation result, the laser powers Pr and Pw at the temperature T specified in the management table are updated.
  • step S24 the Test RW term for the temperature at which the laser power was optimized is checked. Subsequently, in step S25, using the data for the two temperatures for which the Test RW term is checked, the optimum laser power Pr, Pr for each temperature between these two temperatures is obtained by interpolation. derive w. Then, in step S26, a check is made for the captured term relating to the temperature at which the interpolation processing has been performed, and the procedure for updating the management table is completed.
  • the relationship between the disk temperature and the initial value of the laser power When the slope of the change in laser beam temperature with respect to the disk temperature (hereinafter referred to as the temperature slope) is specified, the temperature at startup is 25 ° C, and the optimum laser power calculated by performing a test read Z write is If it is "6 2", update "6 4" to "6 2".
  • the laser powers for the other temperatures are all reduced by the same value “2” to perform interpolation while maintaining the temperature gradient. It updates the management table.
  • FIG. 7 shows an example in which the relationship between the disk temperature and the initial value of the laser power is updated by a test read / write at 25 ° C. In this way, the management table is updated while keeping the temperature gradient constant.
  • step S7 of FIG. 2 the disk temperature T is detected in step S7 of FIG. 2, and in step S8, it is determined whether the disk temperature has risen by 5 ° C. or more.
  • step S9 the system temperature T—sys is updated to the temperature T in step S9.
  • step S10 it is determined whether or not the temperature is the temperature which has already been experienced in the management table. If the determination is no, the process proceeds to step S11. Execute the test read no-write and management table update routine shown in (1).
  • FIG. 9 shows a state in which the management table has been updated by the test read / write.
  • a test read Z-write is performed to determine the optimum laser power at that temperature, and an interpolation process using that data is performed to perform management.
  • the table will be updated.
  • the read power Pr and the write power are referred to by referring to the relationship between the temperature and the laser power stored in the management table.
  • the power P w is set, and signal recording and reproduction are performed.
  • step S32 After detecting the disk temperature in step S31, it is determined in step S32 whether a recording / reproducing request has been issued, and the determination is yes here. If so, the control table is referred to in step S33, and in step S34, the laser power Pr and Pw according to the temperature at that time are set. Then, in step S35, the recording and reproducing operations are executed, and the procedure ends.
  • the lower limit value P rain of the smaller value is set.
  • the procedure shown in Figure 13 and Figure 14 is adopted. That is, assuming the three states shown in Fig. 13 according to the initial value of the reproduction power, when the reproduction power is below the lower limit value as in A, the reproduction power is increased, and as shown in B, the reproduction power is lower.
  • the playback power is reduced by the lower limit shown in FIG.
  • the value is changed to the value Pr min or a value close to the value Pr min. afterwards, By adding a predetermined value N to the reproduction power, the optimum reproduction power Pr is obtained.
  • the present embodiment employs a procedure using the following principle. That is, the signal recorded on the magneto-optical disk has a data format in which a plurality of frames are arranged in chronological order, a header portion is provided in each frame, and each header portion has the format shown in FIG.
  • the first reference signal of a single frequency having a short period (2 T) and the second reference signal of a single frequency having a long period (8 T) are recorded, and the reproduction of the first reference signal is performed.
  • the ratio (W 2 ZW 1) between the amplitude W 1 of the signal and the amplitude W 2 of the reproduced signal of the second reference signal increases as the reproduction power Pr increases. Therefore, when the ratio is lower than the predetermined set value, it is determined to be the state of A in FIG. 13, and when the ratio is higher than the predetermined setting, it is determined to be the state of C in FIG. You can do it.
  • FIG. 10 shows a specific procedure for optimizing the reproduction power by the test read for a group of test tracks provided in advance on the magneto-optical disk.
  • an initial value is set as the write power Pw, and recording on the test track is performed in step S43.
  • an initial value is set as the reproduction power Pr, and in step S45, the test track is reproduced, and depending on whether the error rate at that time exceeds the threshold value or not.
  • the quality of the reproduction is determined.
  • the reproducing power Pr is reduced by the unit power ("1") in step S46, and in step S47.
  • the test track is reproduced again, and the quality of the reproduction is determined. Then, the process returns to step S46 to repeat the same procedure.
  • step S47 the process proceeds to step S48, in which the value obtained by increasing the reproduction power Pr by the unit power ("1") is set as the lower limit value Prl.
  • the optimal playback power In determining P r — opt a method of multiplying the lower limit reproduction power P rl by a predetermined value may be adopted.
  • the predetermined value ⁇ can be determined in advance as a value depending on the system.
  • step S45 when it is judged as NG in step S45, it is the state of ⁇ or C in FIG. 13 and therefore, based on the principle described in FIGS. 18 and 19, which state is Is determined. That is, in step S50 of FIG. 10, it is determined whether or not the ratio (W 2 / W 1) of the above-described reference signal exceeds the set value A, thereby changing the reproduction power. Recognize direction. It should be noted that instead of the ratio of the reference signal (W2 / W1), the direction in which the playback power is changed is recognized based on whether or not the difference (W2-W1) between the reference signals exceeds the set value. It is also possible.
  • step S50 determines whether or not the reproduction power Pr is larger than the set lower limit Pr-min. If the determination is yes here, the process proceeds to step S53, where the test track is reproduced, and the quality of the reproduction is determined. If NG is determined in step S53, the process returns to step S51 to repeat the process of reducing the reproduction power Pr by the predetermined value n. As a result, if it is determined to be OK in step S53, the state changes to B in FIG. 13 and the process proceeds to step S46 to execute the above-described procedure to obtain the optimum reproduction power Pr-opt. And end the procedure.
  • step S50 When it is determined NO in step S50, it is in the state of A in FIG. 13, so the process proceeds to step S57, and the reproduction power Pr is increased by the unit power ("1"). Thereafter, in step S58, it is determined whether or not the reproduction power Pr is smaller than the set upper limit value Pr-max. If the determination is yes here, the process proceeds to step S59, where the test track is reproduced, and the quality of the reproduction is determined. If it is determined as NG in step S59, the process returns to step S57 to repeat the process of increasing the reproduction power Pr.
  • step S43 the process proceeds to the test track write procedure. If it is determined in step S56, an alarm "NG" is issued and the test track is registered as NG in step S56. Note that the optimum reproduction power Pr-opt can be obtained by the same procedure for the test read for the land of the test track.
  • FIG. 11 shows a specific procedure for optimizing the recording power by the method.
  • the recording power P w is set to the initial value.
  • step S64 recording and reproduction on the test track are performed to determine the quality of reproduction. If it is determined to be NG here, an alarm "NG" is issued in step S65 and the test track is registered as NG.
  • the recording power is kept at the initial value.
  • step S64 the recording power Pw is reduced by the unit power "1", and then the recording power Pw is reduced from the set lower limit Pwjin in step S67. Is determined to be larger, the process proceeds to step S65 to issue an alarm "NG" and register the test track as NG. During operation, the recording power is kept at the initial value. If the answer is yes in step S67, recording and playback are performed on the test track in step S68 to determine the quality of playback. If it is judged OK here, step Proceeding to S69, after changing the write data or shifting the write position, the process returns to step S66, and the procedure for lowering the recording power is repeated.
  • step S68 the process proceeds to step S70, and the unit power "1" is added to the recording power Pw at that time to obtain the lower limit value Pwl. Then, the flow shifts to step S71, where a predetermined value N is added to the lower limit recording power Pr1, thereby obtaining the optimum recording power Pw-opt, and the procedure is ended.
  • a predetermined value N is added to the lower limit recording power Pr1, thereby obtaining the optimum recording power Pw-opt
  • the procedure is ended.
  • determining the optimum recording power Pw-opt it is also possible to adopt a method of multiplying the lower limit recording power Pwl by a predetermined value ⁇ .
  • the predetermined value ⁇ can be determined in advance as a value depending on the system.
  • a method of approximating the relationship between the recording power and the bit error rate by a quadratic curve as shown in FIG. 16 can be further employed. For example, using a test track provided in advance on a disk, recording a signal on the test track with a different laser power, and then reproducing the signal with an appropriate laser power and reproducing the signal. Detect the error rate of the signal. As a result, the relationship between the laser power (recording power) and the error rate at the three points P l, ⁇ 2 and ⁇ 3 is plotted as shown in FIG. The relationship can be approximately represented by a quadratic curve, and the quadratic curve is uniquely determined if coordinate values at least at three points are determined.
  • a quadratic curve representing the relationship between the laser power and the error rate can be obtained by using the values of the laser power and the error rate at the three points Pl, ⁇ 2, and ⁇ 3, as shown in FIG.
  • the laser power corresponding to the apex of the quadratic curve is the optimum laser power P wo that minimizes the error rate.
  • FIG. 12 shows a procedure of recording power optimization based on quadratic curve approximation.
  • step S84 the recording power P wl and the bit error rate BER at that time are stored in the memory.
  • step S87 the recording power Pw is reduced by a predetermined value n, and then recording and reproduction are performed on the test track in step S88 to determine the quality of reproduction.
  • the procedure returns to step S87, and the procedure for lowering the recording power is repeated.
  • the process proceeds to step S89, and the NG recording power Pw2 and the bit error rate BER are stored in the memory.
  • step S90 after increasing the recording power Pw by a predetermined value n, recording and reproduction with respect to the test track are performed in step S91, and the quality of reproduction is determined.
  • the process returns to step S90, and the procedure for increasing the recording power is repeated.
  • the process proceeds to step S92, and the NG recording power Pw3 and the bit error rate BER are stored in the memory.
  • step S93 the relationship between the laser power and the bit error rate is determined using the three data points (Pwl, BER1), (Pw2, BER2), and (Pw3, BER3) stored in the memory.
  • step S94 Approximate by a quadratic curve, and calculate the recording power as the central axis of the curve as the optimum value Pw__opt. Then, in step S94, the optimum value Pw-opt is set as the recording power Pw, and the procedure ends.
  • the optimum reproducing power independent of the recording power is reduced in a state where the optimum recording power is unknown. It can be determined by the number of steps, and in the subsequent test write to determine the optimum recording power, Using the obtained optimum reproduction power, the optimum recording power can be determined with a smaller number of steps. Throughout the entire procedure, it is possible to set a high-precision optimum reproduction power and optimum recording power by a simple procedure. is there. As a result, after starting the system, signal reproduction or signal recording can be started in a short time, and signal reproduction and signal recording can be performed accurately.

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  • Optics & Photonics (AREA)
  • Optical Head (AREA)
  • Optical Recording Or Reproduction (AREA)
  • Semiconductor Lasers (AREA)

Abstract

A disc recorder/reproducer comprising a laser drive circuit (15) which can regulate the power of laser light by supplying a drive signal to an optical head (4), an error correction circuit (11) for detecting the error rate of a reproduced signal, and a system controller (10) for controlling operation of the laser drive circuit based on the output from the error correction circuit. The system controller registers the relation between an optical laser power where the error rate does not exceed a predetermined value and the disc temperature on a management table. At the time of setting a laser power, an optimal laser power can be set depending on the variation of disc temperature by reading out an optimal laser power corresponding to the of disc temperature from the management table.

Description

明 細 書 ディスク記録再生装置 技術分野  Description Disc recording / reproducing device Technical field
本発明は、 ディスクに光学ヘッドからレーザ光を照射して、 該ディスクに信号 を記録し、 若しくは該ディスクから信号を再生するディスク記録再生装置に関す るものである。  The present invention relates to a disk recording / reproducing apparatus which irradiates a disk with laser light from an optical head to record a signal on the disk or reproduce a signal from the disk.
背景技術 Background art
従来、 この種ディスク記録再生装置の記録媒体として、 書き換え可能であって、 記憶容量が大きく、 然も信頼性の高い光磁気ディスクが開発されており、 コンビ ユータゃオーディオ ' ビジュアル機器の外部メモリとして広く用いられている。 特に近年においては、 '図 2 0に示す如く光磁気ディスク（ 1 )の信号面に、 ランド (17)とグループ（18)を交互に形成し、 ランド（17)とグループ（18)の両方に信号を 記録して、 記録密度を上げる技術が開発されている。  Hitherto, rewritable, large-capacity, and highly reliable magneto-optical disks have been developed as recording media for this type of disk recording / reproducing device, and as external memory for combination audio / visual equipment. Widely used. Particularly in recent years, as shown in FIG. 20, lands (17) and groups (18) are alternately formed on the signal surface of the magneto-optical disk (1), and both lands (17) and groups (18) are formed. Techniques have been developed to record signals and increase the recording density.
ランド（17)及びグループ（18)は図示の如く蛇行（ゥォプリング）しており、 蛇行 の周波数は、 所定の中心周波数に F M変調がかけられており、 信号再生によって、 このゥォプル信号が検出され、 ゥォブル信号が常に中心周波数となる様に光磁気 ディスクの回転を調整することによって、 線速度一定制御が実現される。 又、 ゥ ォブル信号には前述の如く F M変調がかけられて、 アドレス情報等の各種の情報 (ゥォブル情報）が含まれており、 信号再生時には、 このゥォブル情報に基づいて 各種の制御動作が実現される。  The land (17) and the group (18) meander (opple) as shown in the figure. The meandering frequency is FM-modulated at a predetermined center frequency, and this signal is detected by signal reproduction. The linear velocity constant control is realized by adjusting the rotation of the magneto-optical disk so that the wobble signal always has the center frequency. In addition, the fobble signal is subjected to FM modulation as described above, and contains various information (fobble information) such as address information. At the time of signal reproduction, various control operations are realized based on the fobble information. Is done.
尚、 レーザパルス磁界変調型のディスク記録再生装置においては、 信号の再生 時に、 光磁気ディスクにレーザ光が照射されると共に、 信号記録時にも、 光磁気 ディスクにレーザ光が照射されて、 光磁気ディスクが局所的に加熱される。 又、 磁気超解像を利用した光磁気ディスクにおいては、 信号再生用のレーザパワーを 上げていって、 ビームスポット領域の温度が所定値に達したときから信号の読出 しを開始するのであるが、 信号再生時のレーザパワーは、 信号記録時のレーザパ ヮ一よりも低く設定されるので、 信号再生に伴つて記録信号が破損してしまう虞 はない。 In a disk recording / reproducing apparatus of a laser pulse magnetic field modulation type, when reproducing a signal, the magneto-optical disk is irradiated with laser light, and at the time of recording a signal, the magneto-optical disk is irradiated with laser light. The disk is locally heated. In the case of a magneto-optical disk using magnetic super-resolution, the laser power for signal reproduction is reduced. The signal reading is started when the temperature of the beam spot area reaches a predetermined value, but the laser power during signal reproduction is set lower than the laser power during signal recording. Therefore, there is no possibility that the recorded signal is damaged by the signal reproduction.
ところで、 ディスク記録再生装置においては、 信号記録時のレーザ光のパワー (記録パワー）及び信号再生時のレーザ光のパワー（再生パワー）にはそれぞれ最適 値が存在し、 パワーが最適値からずれると、 再生信号のビットエラーレートが増 大し、 ビッ トエラーレートが一定の規定値を越えると、 正常な再生動作が困難と なる（図 1 4参照）。 そこで従来、 システムの起動時に、 光磁気ディスクに予め設 けられているテストトラックを対象として、 再生パワーを徐々に変えながら信号 を再生すると共にエラーレートを算出し、 或いは、 記録パワーを徐々に変えなが ら信号を記録すると共にその再生信号のエラーレートを算出し、 エラーレートが 最小となる最適な再生パヮ一及び記録パヮ一を検索する方法が提案されている。  By the way, in a disk recording / reproducing apparatus, there is an optimum value for the laser beam power at the time of signal recording (recording power) and the power of the laser beam at the time of signal reproduction (reproduction power), and if the power deviates from the optimum value. However, when the bit error rate of the reproduction signal increases and the bit error rate exceeds a certain specified value, normal reproduction operation becomes difficult (see Fig. 14). Conventionally, at the time of system startup, a signal is reproduced while gradually changing the reproducing power, and an error rate is calculated for a test track provided in advance on the magneto-optical disk, or the recording power is gradually changed. Meanwhile, a method has been proposed in which a signal is recorded, the error rate of the reproduced signal is calculated, and the optimum reproduction and recording powers that minimize the error rate are searched.
しかしながら、 光磁気ディスクにおいては、 レーザ光の照射によってディスク 温度が徐々に上昇し、 これに伴って最適記録パワーや最適再生パワーが変化する ことになる。 従って、 システムの起動時にレーザパワーが最適であっても、 その 後の通常動作においてはレーザパワーが最適値からずれて、 正常な信号記録や信 号再生が困難となる問題がある。 尚、 この問題は、 温度を常に監視して、 温度変 化が発生する度にレーザパワーの最適化を実行する方式によって解決することが 可能であるが、 最適化のための演算処理を頻繁に繰り返えす必要があるため、 該 方式は実現が困難である問題がある。  However, in the case of a magneto-optical disk, the laser temperature gradually increases due to the irradiation of the laser beam, and the optimum recording power and the optimum reproducing power change accordingly. Therefore, even if the laser power is optimal at the time of starting the system, the laser power deviates from the optimal value in the normal operation thereafter, and there is a problem that normal signal recording and signal reproduction become difficult. This problem can be solved by a method of constantly monitoring the temperature and optimizing the laser power every time a temperature change occurs.However, arithmetic processing for the optimization is frequently performed. Since this method needs to be repeated, there is a problem that this method is difficult to realize.
本発明の目的は、 ディスク温度の変化に応じて常に最適なレーザパワーを設定 することが出来るディスク記録再生装置を提供することである。  An object of the present invention is to provide a disk recording / reproducing apparatus which can always set an optimum laser power according to a change in disk temperature.
発明の開示 Disclosure of the invention
本発明に係るディスク記録再生装置は、 光学ヘッドに駆動信号を供給して光学 へッドが出射するレーザ光のパワーを調整することが可能なレーザ駆動回路と、 信号再生状態の良否を表わす評価データを検出する評価データ検出回路と、 評価 データ検出回路の出力に基づいてレーザ駆動回路の動作を制御する制御回路とを 具えている。 制御回路は、 ディスクの温度を検出する温度検出手段と、 評価デー タが規定値を越えない様に信号記録時若しくは信号再生時のレーザ光のパワーを 最適化するレーザパワー最適化手段と、 ディスク温度と最適レーザパワーの関係 を格納すべきテープル手段と、 テーブル手段にディスク温度と最適レーザパワー を登録するテーブル登録手段と、 テープル手段からディスク温度に応じた最適レ 一ザパワーを導出する最適レーザパワー導出手段とを具えている。 A disk recording / reproducing apparatus according to the present invention includes a laser driving circuit capable of supplying a driving signal to an optical head and adjusting the power of laser light emitted from an optical head; It has an evaluation data detection circuit for detecting evaluation data indicating the quality of the signal reproduction state, and a control circuit for controlling the operation of the laser drive circuit based on the output of the evaluation data detection circuit. The control circuit includes: a temperature detecting means for detecting a temperature of the disk; a laser power optimizing means for optimizing a laser beam power at the time of signal recording or signal reproduction so that the evaluation data does not exceed a specified value; Table means for storing the relationship between temperature and optimum laser power, table registration means for registering disk temperature and optimum laser power in the table means, and optimum laser power for deriving optimum laser power according to disk temperature from the table means Deriving means.
上記本発明のディスク記録再生装置においては、 起動時及ぴ通常動作の過程で レーザパワーの最適化が実行され、 ディスク温度と最適レーザパワーの関係がテ 一ブル手段に蓄積されるので、 テープル手段に既に最適レーザパワーが登録され ている温度では、 最早レーザパワーの最適化を行なう必要はなく、 テーブル手段 からその温度における最適レーザパワーを読み出して、 設定するだけでよい。 従 つて、 温度変化が発生する度にレーザパワーの最適化を行なうディスク記録再生 装置に比べて、 演算処理の負担は軽減される。  In the disk recording / reproducing apparatus of the present invention, the optimization of the laser power is performed at the time of startup and during the normal operation, and the relationship between the disk temperature and the optimum laser power is stored in the table means. If the optimum laser power is already registered in the table, it is no longer necessary to optimize the laser power, but only the optimum laser power at that temperature is read from the table means and set. Therefore, the processing load is reduced compared to a disk recording / reproducing apparatus that optimizes the laser power every time a temperature change occurs.
具体的構成において、 レーザパワー最適化手段は、 ディスク温度が所定温度だ け変化する度にレーザパワーの最適化を実行し、 テーブル登録手段は、 レーザパ ヮ一登録手段から得られる温度と最適レーザパヮ一をテーブル手段に登録する登 録処理手段と、 既にテーブル手段に最適レーザパワーが登録されている温度と新 たにレーザパワーの最適化が実行された温度との間の温度範囲で、 各温度におけ るレーザパヮ一の最適値を補間によつて算出する演算処理手段とを具えている。 該具体的構成によれば、 レーザパワーの最適化はディスク温度が所定温度だけ 変化する度に実行され、 レーザパワーの最適化が実行されない温度については、 その温度の近傍温度における最適レーザパワーから補間によつて最適値が算出さ れるので、 テーブル手段に全てのデータ（温度及び最適レーザパワーの関係）を登 録するのに必要な演算処理量は大幅に削減される。 尚、 補間処理によっても、 信 号の記録や再生に支障のない、 実質的に最適なレーザパワーを求めることが出来 る。 In a specific configuration, the laser power optimizing means executes laser power optimization each time the disk temperature changes by a predetermined temperature, and the table registering means compares the temperature obtained from the laser page registering means with the optimum laser power. Registration processing means for registering the laser power in the table means, and a temperature range between the temperature at which the optimum laser power has already been registered in the table means and the temperature at which the laser power optimization has been newly performed. And an arithmetic processing means for calculating the optimum value of the laser beam by interpolation. According to this specific configuration, the optimization of the laser power is performed each time the disk temperature changes by a predetermined temperature, and the temperature at which the optimization of the laser power is not performed is interpolated from the optimum laser power near the temperature. Since the optimum value is calculated according to the above, the amount of arithmetic processing required to register all data (relationship between temperature and optimum laser power) in the table means is greatly reduced. In addition, the signal It is possible to find a substantially optimal laser power that does not hinder recording and reproduction of signals.
更に具体的な構成において、 テーブル登録手段は更に、 レーザパワー最適化手 段による最適化若しくは演算処理手段による補間が行なわれていない温度を対象 として、 既に最適化若しくは補間によって求められている近傍温度の最適レーザ パワーと、 温度変化に対する最適レーザパワーの変化の割合を表わす所定の温度 傾斜データとに基づき、 最適レーザパワーの近似値を算出する近似値算出手段を 具えている。  In a more specific configuration, the table registration means further includes, for a temperature at which optimization by the laser power optimization means or interpolation by the arithmetic processing means has not been performed, a nearby temperature already determined by optimization or interpolation. And an approximate value calculating means for calculating an approximate value of the optimum laser power based on the optimum laser power and predetermined temperature gradient data indicating a ratio of the change of the optimum laser power to the temperature change.
該具体的構成によれば、 レーザパワー最適化手段による最適化や演算処理手段 による補間によって最適レーザパワーが未だ算出されていない温度については、 先ず、 最適化若しくは補間によって得られている近傍温度の最適レーザパヮ一と、 温度に対する最適レーザパワーの変化率を表わす所定の温度傾斜データとに基づ き、 最適レーザパワーの近似値が算出されて、 その温度と最適レーザパワーの近 似値との関係がテーブル手段に格納される。 その後、 最適化若しくは補間によつ てレーザパワーの最適化が行なわれていない温度となって、 その温度で最適レー ザパヮ一が算出されたとき、 該最適レーザパヮ一によつて前記近似値が置き換え られる。 そして、 更にその温度での最適レーザパワーを用いた補間処理が実行さ れて、 テーブル手段が更新される。 従って、 テーブル手段には、 常に、 各温度に おける最適レーザパワー若しくはその近似値が登録されており、 徐々に近似値が 最適値に置き換えられていくことになる。  According to the specific configuration, for the temperature at which the optimum laser power has not yet been calculated by the optimization by the laser power optimizing means or the interpolation by the arithmetic processing means, first, the temperature of the neighboring temperature obtained by the optimization or the interpolation is calculated. An approximate value of the optimum laser power is calculated based on the optimum laser power and predetermined temperature gradient data indicating a rate of change of the optimum laser power with respect to the temperature, and the relationship between the temperature and the approximate value of the optimum laser power is calculated. Is stored in the table means. Thereafter, the temperature becomes a temperature at which the laser power has not been optimized by optimization or interpolation, and when the optimum laser power is calculated at that temperature, the approximate value is replaced by the optimum laser power. Can be Then, an interpolation process using the optimum laser power at that temperature is further performed, and the table means is updated. Therefore, the optimal laser power at each temperature or its approximate value is always registered in the table means, and the approximate value is gradually replaced with the optimal value.
ここで、 本発明に係るディスク記録再生装置におけるレーザパヮ一最適化の原 理を説明する。 信号再生においては、 例えば図 1 5に示す如く再生パワーが変化 することによって、 再生信号のエラーレートが二次曲線的に変化し、 例えば実線 で示す特性曲線においては、 エラーレートが最小値となる最適再生パワー Pでが 存在し、 信号再生時のレーザパワーは、 エラーレートが規定値を下回ることとな る 2つの限界値である下方限界再生パワー P r minと上方限界再生パワー P r max の間に設定する必要がある。 同様に、 信号記録についても、 エラーレートが最小 値となる最適記録パワー P wが存在し、 信号記録時のレーザパワーは、 その再生 信号のエラーレートが規定値を下回ることとなる 2つの限界値である下方限界記 録パヮー P wminと上方限界記録パヮー P wmaxの間に設定する必要がある。 Here, the principle of laser power optimization in the disk recording / reproducing apparatus according to the present invention will be described. In signal reproduction, for example, the reproduction power changes as shown in Fig. 15 to change the error rate of the reproduction signal in a quadratic curve. For example, in the characteristic curve shown by the solid line, the error rate becomes the minimum value. There is an optimum reproducing power P, and the laser power at the time of signal reproduction is the lower limit reproducing power P r min and the upper limit reproducing power P r max, which are two limit values at which the error rate falls below the specified value. Must be set between Similarly, for signal recording, there is an optimum recording power P w at which the error rate becomes the minimum value, and the laser power during signal recording has two limit values at which the error rate of the reproduced signal falls below the specified value. It must be set between the lower limit recording power P wmin and the upper limit recording power P wmax.
図 1 7は、 それぞれエラーレートが規定値を下回ることとなる再生パワー P r と記録パワー P wの範囲を表わしており、 再生パワー P r及び記録パワー P wの 設定においては、 この範囲内の任意の値に設定すれば、 信号の記録及び再生に問 題はない 考えられるが、 図 1 7に示す特性はディスクの反り等によって変動す るため、 該範囲內の出来るだけ中央位置に近レ、再生パヮ一と記録パヮ一を設定す ることが望ましい。 そこで、 例えば再生パワーの最適化方法としては、 エラーレ 一トが規定値を下回ることとなる下方限界再生パワー P r minと上方限界再生パヮ 一 P r raaxの平均値を算出して、 その結果を最適再生パワーに決定する方法を採用 することが出来る。  FIG. 17 shows the range of the reproduction power Pr and the recording power Pw in which the error rate is below the specified value, and the setting of the reproduction power Pr and the recording power Pw is within this range. If it is set to an arbitrary value, there is no problem in signal recording and reproduction.However, the characteristics shown in Fig. 17 fluctuate due to the warpage of the disc, etc. In addition, it is desirable to set a reproduction level and a recording level. Therefore, for example, as a method for optimizing the reproduction power, an average value of the lower limit reproduction power Prmin and the upper limit reproduction power Prraax at which the error rate becomes lower than a specified value is calculated, and the result is calculated. A method for determining the optimum reproduction power can be adopted.
しかしながら、 エラーレートが規定値を下回ることとなる再生パワー P rは、 図 1 7に示す如くエラーレートが規定値を下回ることとなる記録パワー P wに依 存しており、 例えば記録パワー P wが 6 . 5 mW〜8 . O mWの範囲では、 エラー レートが規定値を下回ることとなる限界の再生パワー P rが記録パワーに応じて 変化する。 従って、 この記録パワーの範囲で、 エラーレートが規定値を下回るこ ととなる下方限界記録パヮー P wminと上方限界記録パヮー P wmaxの平均値を最 適再生パワーとした場合、 その最適再生パワーの値は、 図 1 7に示す範囲の中心 位置から大きく偏った位置となって、 図 1 7に示す特性に変動があった場合、 再 生パヮ一が最適値から大きくずれて、 エラーレートが規定値を上回る虞がある。 そこで、 本発明においては、 再生パワー及び記録パワーを図 1 7に示す範囲の 出来るだけ中央位置の値に設定するべく、 再生パワーの最適化においては、 先ず、 エラーレートが規定値を下回ることとなる下方の限界再生パワー P r minを検索し た後、 検索された下方限界再生パワー P r minに所定値を加算することによって、 最適再生パワーを算出することとした。 However, the reproduction power Pr at which the error rate falls below the specified value depends on the recording power P w at which the error rate falls below the specified value, as shown in FIG. In the range of 6.5 mW to 8.0 mW, the limit reproduction power Pr at which the error rate falls below the specified value varies according to the recording power. Therefore, if the average value of the lower limit recording power P wmin and the upper limit recording power P wmax at which the error rate falls below the specified value within this recording power range is defined as the optimum reproduction power, The value is a position that is greatly deviated from the center position of the range shown in Fig. 17, and if the characteristics shown in Fig. 17 fluctuate, the playback rate greatly deviates from the optimum value, and the error rate is specified. There is a risk of exceeding the value. Therefore, in the present invention, in order to set the reproduction power and the recording power to the values at the center positions as much as possible in the range shown in FIG. 17, in the optimization of the reproduction power, first, the error rate must be lower than a specified value. After searching for the lower limit reproduction power P r min, by adding a predetermined value to the searched lower limit reproduction power P r min, The optimum reproduction power was calculated.
ここで、 前記所定値としては、 図 1 7に示す関係において再生パワーが記録パ ヮ一に依存しない領域、 即ち記録パワーが 8. OmW以上での最大再生パワー 2. 56 mWと最小再生パワー 1.84 mWの差の 2分の 1である 0. 36 mW、 若し くはその近傍値 (例えば 0.4mW)を採用することが出来る。 これによつて、 再生 パワーに関しては、 記録パヮ一に依存しな 、最適値が得られることになる。  Here, the predetermined value is an area where the reproduction power does not depend on the recording power in the relationship shown in FIG. 17, that is, the maximum reproduction power of 2.58 mW and the minimum reproduction power of 1.84 when the recording power is 8.OmW or more. 0.36 mW, which is one half of the difference in mW, or a value close to it (for example, 0.4 mW) can be adopted. As a result, an optimum value can be obtained for the reproduction power that does not depend on the recording power.
尚、 図 1 5に示す様に、 再生パワーに対するエラーレートの変動特性が実線か ら破線や鎖線に示す様に変動することによって、 再生パワーの最適値が P rから P r 'や P r〃に変化したとしても、 これに伴って、 下方の限界再生パワー P rmin も P rmin'や P rmin"に変化し、 最適値 P r、 P r '及ぴ P r "と下方限界再生パヮ 一 P rmin、 P r min'及び P r min"との差は、 略一定の値 Nとなるので、 下方限界 再生パワー P rmin, P rmin'及ぴ P r min"にこの差 Nを加算することによって、 それぞれ最適再生パワー P r、 P r '及び P r"を求めることが出来るのである。 又、 下方限界再生パワー P rtninに所定値 Nを加算する代わりに、 所定値 αを乗算 することによつても、 同様に正確な最適再生パワー P r、 P r'及び P r"を求め ることが出来る。  Note that, as shown in FIG. 15, the variation of the error rate with respect to the reproduction power varies from the solid line to the broken line or the dashed line, so that the optimal value of the reproduction power changes from Pr to Pr ′ or Pr P. Accordingly, the lower limit reproduction power Prmin also changes to Prmin 'or Prmin ", and the optimum values Pr, Pr' and Pr" and the lower limit reproduction power P rmin, Prmin 'and Prmin "have a substantially constant value N. By adding this difference N to the lower limit reproduction power Prmin, Prmin' and Prmin" It is possible to obtain the optimum reproduction powers Pr, Pr ′ and Pr ″, respectively. Also, instead of adding the predetermined value N to the lower limit reproduction power P rtnin, by multiplying by the predetermined value α. In this case, it is also possible to similarly obtain accurate optimum reproduction powers Pr, Pr 'and Pr ".
上述の如く、 本発明に係るディスク再生装置によれば、 比較的少ない演算処理 量で、 ディスク温度に拘わらず常に最適なレーザパワーを設定することが出来る。 図面の簡単な説明  As described above, according to the disk reproducing apparatus of the present invention, it is possible to always set an optimum laser power with a relatively small amount of arithmetic processing regardless of the disk temperature. BRIEF DESCRIPTION OF THE FIGURES
図 1は、 本発明に係るディスク記録再生装置の構成を表わすプロック図である。 図 2は、 該装置におけるレーザパワー制御の手続きを表わすフローチヤ一トで ある。  FIG. 1 is a block diagram showing a configuration of a disk recording / reproducing apparatus according to the present invention. FIG. 2 is a flowchart showing a procedure of laser power control in the apparatus.
図 3は、 テストリード Zライト及び管理テーブル更新ルーチンのフローチヤ一 トである。  FIG. 3 is a flowchart of the test read Z write and management table update routine.
図 4は、 通常動作における記録再生動作の制御手続きを表わすフローチャート である。 図 5は、 管理テーブルのデータ構造を説明する図表である。 FIG. 4 is a flowchart showing a control procedure of the recording / reproducing operation in the normal operation. FIG. 5 is a chart for explaining the data structure of the management table.
図 6は、 管理テーブル更新の具体例を示す図表である。  FIG. 6 is a chart showing a specific example of updating the management table.
図 7は、 起動時における管理テーブルの温度とレーザパワーの関係を示すグラ フである。  FIG. 7 is a graph showing the relationship between the temperature of the management table and the laser power at the time of startup.
図 8は、 第 1回目のテストリード/ライトにおける管理テーブルの同上のグラ フである。  Fig. 8 is the same graph as the management table for the first test read / write.
図 9は、 第 2回目のテストリード/ライトにおける管理テーブルの同上のダラ フである。  Figure 9 shows the same draft of the management table in the second test read / write.
図 1 0は、 再生パワー最適化の手続きを表わすフローチャートである。  FIG. 10 is a flowchart showing the procedure of the reproduction power optimization.
図 1 1は、 記録パワー最適化の手続きを表わすフローチャートである。  FIG. 11 is a flowchart showing a procedure for optimizing the recording power.
図 1 2は、 記録パワー最適化の他の手続きを表わすフローチャートである。 図 1 3は、 再生パワー最適化の手順を説明するグラフである。  FIG. 12 is a flowchart showing another procedure of the recording power optimization. FIG. 13 is a graph for explaining the procedure of reproducing power optimization.
図 1 4は、 再生パワーとエラーレートの関係を表わすグラフである。  FIG. 14 is a graph showing the relationship between the reproduction power and the error rate.
図 1 5は、 再生パワー最適化の原理を説明するグラフである。  FIG. 15 is a graph illustrating the principle of read power optimization.
図 1 6は、 記録パワー最適化の原理を説明するグラフである。  FIG. 16 is a graph illustrating the principle of recording power optimization.
図 1 7は、 規定値を満たす記録パワーと再生パワーの関係を表わす図である。 図 1 8は、 再生信号のヘッダ部に書き込まれている 2つの基準信号の波形図で ある。  FIG. 17 is a diagram showing the relationship between the recording power and the reproduction power satisfying the specified value. FIG. 18 is a waveform diagram of two reference signals written in the header part of the reproduction signal.
図 1 9は、 両基準信号の再生信号の振幅比と再生パワーとの関係を表わすグラ フである。  FIG. 19 is a graph showing the relationship between the amplitude ratio of the reproduction signals of both reference signals and the reproduction power.
図 2 0は、 光磁気ディスクに形成されているランドとグループを表わす拡大斜 視図である。  FIG. 20 is an enlarged perspective view showing lands and groups formed on the magneto-optical disk.
発明を実施するための最良の形態 BEST MODE FOR CARRYING OUT THE INVENTION
以下、 本発明を、 光磁気ディスクを記録媒体とするディスク記録再生装置に実 施した形態につき、 図面に沿って具体的に説明する。 本発明に係るディスク記録 再生装置は、 図 1に示す如く、 光磁気ディスク（1 )を回転駆動するためのスピン ドルモータ（2)を具えている。 光磁気ディスク（1)の近傍位置には温度センサー (16)が取り付けられている。 Hereinafter, an embodiment in which the present invention is applied to a disk recording / reproducing apparatus using a magneto-optical disk as a recording medium will be specifically described with reference to the drawings. As shown in FIG. 1, a disk recording / reproducing apparatus according to the present invention comprises a spinning device for rotating a magneto-optical disk (1). It has a dollar motor (2). A temperature sensor (16) is mounted near the magneto-optical disk (1).
又、 信号再生系として、 レーザ駆動回路（15)、 光学ヘッド（4)、 再生信号増幅 回路（5)、 再生信号検出回路（7)及びエラー訂正回路（11)を具え、 信号再生時に は、 レーザ駆動回路（15)によって光学ヘッド（4)が駆動されて、 光磁気ディスク (1)にレーザ光が照射される。 一方、 信号記録系として、 磁気ヘッド駆動回路（1 4)及び磁気ヘッド（3)を具え、 信号記録時には、 前記のレーザ駆動回路（15)及び 光学ヘッド（4)が、 光磁気ディスク（1)を局所的に加熱するために動作する。 更 に、 制御系として、 サーボ回路（6)、 外部同期信号生成回路（8)、 システムコン トローラ（10)、 メモリ（9)、 遅延回路（12)、 及びタイミングパルス発生回路（13) を具えている。  The signal reproduction system includes a laser drive circuit (15), an optical head (4), a reproduction signal amplification circuit (5), a reproduction signal detection circuit (7), and an error correction circuit (11). The optical head (4) is driven by the laser drive circuit (15), and the magneto-optical disk (1) is irradiated with laser light. On the other hand, a magnetic head drive circuit (14) and a magnetic head (3) are provided as a signal recording system. At the time of signal recording, the laser drive circuit (15) and the optical head (4) correspond to the magneto-optical disk (1). Operates to locally heat the. In addition, the control system includes a servo circuit (6), an external synchronization signal generation circuit (8), a system controller (10), a memory (9), a delay circuit (12), and a timing pulse generation circuit (13). I have.
光学ヘッド（4)は、 レーザ光を光磁気ディスク（1)に照射し、 その反射光を光 信号及び光磁気信号として検出する。 再生信号増幅回路（5)は、 光学へッド（4) から得られる光信号及び光磁気信号を増幅した後、 光信号に含まれるフォーカス エラー信号及びトラッキングエラー信号をサーボ回路（6)へ供給する。 又、 再生 信号増幅回路（5)は、 光磁気ディスク（1)のグループに一定間隔で形成されてい る不連続領域に起因して検出される光信号を外部同期信号生成回路（ 8 )へ供給す ると共に、 光磁気信号を再生信号検出回路（7)へ供給する。  The optical head (4) irradiates the laser beam to the magneto-optical disk (1) and detects the reflected light as an optical signal and a magneto-optical signal. The reproduction signal amplification circuit (5) amplifies the optical signal and magneto-optical signal obtained from the optical head (4), and then supplies the focus error signal and tracking error signal included in the optical signal to the servo circuit (6). I do. The reproduction signal amplification circuit (5) supplies an optical signal detected due to the discontinuous area formed at a constant interval in the group of the magneto-optical disk (1) to the external synchronization signal generation circuit (8). At the same time, the magneto-optical signal is supplied to the reproduction signal detection circuit (7).
外部同期信号生成回路（ 8 )は外部同期信号を生成し、 サーボ回路（ 6 )及び遅延 回路（12)へ供給する。 サーポ回路（6)は、 フォーカスエラー信号及びトラツキン グエラー信号に基づいて、 光学へッド（4)に装備されているァクチユエータ（図示 省略）に対するフォーカスサーボ及びトラッキングサーボを実行すると共に、 外部 同期信号に基づいてスピンドルモータ（ 2)の回転を制御する。  The external synchronizing signal generation circuit (8) generates an external synchronizing signal and supplies it to the servo circuit (6) and the delay circuit (12). The servo circuit (6) executes a focus servo and a tracking servo for an actuator (not shown) provided in the optical head (4) based on the focus error signal and the tracking error signal, and generates an external synchronization signal. Based on the control of the rotation of the spindle motor (2).
再生信号検出回路（ 7 )は、 検出した再生信号をエラ一訂正回路（11)へ供給し、 エラー訂正回路（11)は、 再生信号を復調すると共に、 これによつて得られる再生 データのエラーを検出し、 そのエラーを訂正した上で、 後段回路へ訂正後の再生 データを出力する。 遅延回路（12)は > 外部同期信号の位相を一定時間遅延させた 同期信号を作成して、 タイミングパルス発生回路（13)へ出力する。 The reproduction signal detection circuit (7) supplies the detected reproduction signal to the error correction circuit (11), and the error correction circuit (11) demodulates the reproduction signal and generates an error in the reproduction data obtained thereby. , And after correcting the error, playback to the subsequent circuit after correction Output data. The delay circuit (12) generates a synchronization signal in which the phase of the external synchronization signal is delayed for a fixed time, and outputs it to the timing pulse generation circuit (13).
タイミングパルス発生回路（13)は、 信号の記録時には、 所定の方式で変調され た記録データと遅延回路（12)からの同期信号の入力を受けて、 光磁気ディスク ( 1 )に交番磁界を印加するためのパルス信号を生成し、 磁気ヘッド駆動回路（14) へ供給すると共に、 光磁気ディスク（1 )にパルス光を照射するためのパルス信号 (ライトクロック）を生成し、 レーザ駆動回路（15)へ供給する。 又、 信号の再生時 には、 再生信号検出回路（7 )は、 遅延回路（12)からの同期信号（リードクロック） に基づいて、 再生アナログ信号をデジタル信号に変換する。  When recording a signal, the timing pulse generator circuit (13) receives recording data modulated by a predetermined method and a synchronization signal from the delay circuit (12), and applies an alternating magnetic field to the magneto-optical disk (1). A pulse signal (write clock) for irradiating the magneto-optical disk (1) with pulse light is generated, and a pulse signal (write clock) for irradiating the magneto-optical disk (1) with pulse light is generated. ). When reproducing a signal, the reproduced signal detection circuit (7) converts the reproduced analog signal into a digital signal based on the synchronization signal (read clock) from the delay circuit (12).
磁気ヘッド駆動回路（14)は、 タイミングパルス発生回路（13)からのパルス信号 に基づいて磁気ヘッド（3 )に対する駆動信号を作成する。 磁気ヘッド（3 )は、 磁 気へッド駆動回路（14)からの駆動信号に基づいて光磁気ディスク（1 )に交番磁界 を印加する。 レーザ駆動回路（15)は、 タイミングパルス発生回路（13)からのパル ス信号に基づいて、 光学へッド（4 )に配備された半導体レーザ（図示省略）を駆動 する。 光学ヘッド（4 )は、 レーザ駆動回路（15)からの駆動信号に基づいてレーザ 光を発生し、 光磁気ディスク（1 )に照射する。  The magnetic head drive circuit (14) creates a drive signal for the magnetic head (3) based on the pulse signal from the timing pulse generation circuit (13). The magnetic head (3) applies an alternating magnetic field to the magneto-optical disk (1) based on a drive signal from a magnetic head drive circuit (14). The laser drive circuit (15) drives a semiconductor laser (not shown) provided in the optical head (4) based on a pulse signal from the timing pulse generation circuit (13). The optical head (4) generates a laser beam based on a drive signal from the laser drive circuit (15) and irradiates the magneto-optical disk (1).
システムコントローラ（10)は、 外部同期信号生成回路（8 )から得られる外部同 期信号に基づいて遅延回路（12)の動作を制御する。 又、 システムコントローラ（1 0)は、 エラー訂正回路（11)から得られるエラー訂正情報に基づいて、 ビットエラ 一レートを算出し、 その結果に応じて、 レーザ駆動回路（15)の動作を制御する。 更に又、 システムコントローラ（10)は、 温度センサー（16)から得られる温度デー タと、 後述するテストリード及びテストライトで求めた最適リードパワー及び最 適ライトパワーとを、 メモリ （9 )内の管理テーブルに蓄積し、 信号再生時及び信 号記録時には、 該管理テーブルを参照して、 レーザパワーを制御する。  The system controller (10) controls the operation of the delay circuit (12) based on the external synchronization signal obtained from the external synchronization signal generation circuit (8). The system controller (10) calculates the bit error rate based on the error correction information obtained from the error correction circuit (11), and controls the operation of the laser drive circuit (15) according to the result. . Further, the system controller (10) compares the temperature data obtained from the temperature sensor (16) with the optimum read power and the optimum write power obtained by the test read and test write described later in the memory (9). The information is accumulated in a management table, and at the time of signal reproduction and signal recording, the laser power is controlled with reference to the management table.
レーザ駆動回路（15)は、 システムコントローラ（10)から供給されるレーザパヮ 一制御信号 C pに応じて、 信号再生時に光学へッド（4 )から出射されるレーザ光 のパワーを後述の如く調整する。 尚、 管理テーブルには、 図 5に示す様に、 各温 度について、 リードパワー P r、 ライトパワー P w、 テストリード/ライ トの実 行済みかどうかを表わすフラグ T estRW、 後述の補間処理済みかどうかを表わす フラグ、 及びその温度が実際に経験済みがどうかを表わすフラグが格納される。 図 2は、 システムコントローラ（10)が実行する手続きの全体の流れを表わして いる。 先ずステップ S 1にて新たな光磁気ディスクの揷入が行なわれると、 ステ ップ S 2では、 以前の管理テーブルをクリアした後、 温度とレーザパワー（P r又 は P w)との関係の基準値 (初期値）を規定した基準テーブルを作成する。 次にステ ップ S 3にて初期温度 T— initialを検出し、 ステップ S 4では、 所定の基準温度 Tdefと、 基準レーザパワー P wdef及び Prdefと、 初期温度 T— initialとから、 起動時のレーザパヮーを求める。 The laser drive circuit (15) responds to a laser power control signal Cp supplied from the system controller (10) to emit laser light from the optical head (4) during signal reproduction. Is adjusted as described below. In the management table, as shown in FIG. 5, for each temperature, the read power Pr, the write power Pw, the flag TestRW indicating whether the test read / write has been executed, and the interpolation processing described later. A flag indicating whether the temperature has been actually experienced and a flag indicating whether the temperature has actually been experienced are stored. Fig. 2 shows the overall flow of the procedure executed by the system controller (10). First, when a new magneto-optical disk is inserted in step S1, in step S2, after clearing the previous management table, the relationship between the temperature and the laser power (Pr or Pw) is determined. Create a reference table that defines the reference values (initial values) for. Next, in step S3, the initial temperature T-initial is detected. In step S4, the starting temperature is determined from the predetermined reference temperature Tdef, the reference laser powers Pwdef and Prdef, and the initial temperature T-initial. Ask for laser power.
その後、 ステップ S 5では、 初期温度 T— initialを現在温度 T及びシステムの 保持する内部温度に設定して、 ステップ S 6のテストリード Zライト及び管理テ 一ブル更新ルーチンを実行する。 テストリード/ライト及び管理テーブル更新ル 一チンにおいては、 図 3に示す如く、 ステップ S 2 1にて、 所定のテストトラッ クを用いてテストリードとテストライト（T e s t RW)を行なって、 最適レーザ パワー P r、 P wを算出する。 そして、 ステップ S 2 3では、 該算出結果に基づ いて、 管理テーブルに規定されている温度 Tにおけるレーザパワー P r、 P wを 更新する。  Then, in step S5, the initial temperature T—initial is set to the current temperature T and the internal temperature held by the system, and the test read Z write and management table update routine in step S6 is executed. In the test read / write and management table update routine, as shown in FIG. 3, in step S21, a test read and a test write (Test RW) are performed using a predetermined test track to optimize the test. Calculate the laser power Pr, Pw. Then, in step S23, based on the calculation result, the laser powers Pr and Pw at the temperature T specified in the management table are updated.
次にステップ S 2 4にて、 レーザパワーの最適化が行なわれた温度についての T est RW項にチェックを付ける。 続いて、 ステップ S 2 5では、 Test RW項に チェックが付けられている 2つの温度についてのデータを用いて、 これら 2つの 温度の間の各温度について、 補間処理によって最適レーザパワー P r、 P wを導 出する。 そして、 ステップ S 2 6では、 補間処理の行なわれた温度についての捕 間済み項にチェックを付けて、 管理テーブルの更新手続きを終了する。  Next, in step S24, the Test RW term for the temperature at which the laser power was optimized is checked. Subsequently, in step S25, using the data for the two temperatures for which the Test RW term is checked, the optimum laser power Pr, Pr for each temperature between these two temperatures is obtained by interpolation. derive w. Then, in step S26, a check is made for the captured term relating to the temperature at which the interpolation processing has been performed, and the procedure for updating the management table is completed.
例えば図 6に示す様にディスク温度とレーザパワーの初期値との関係、 即ちデ イスク温度に対するレーザパヮ一の変化の傾斜 (以下、 温度傾斜という）が規定さ れている場合において、 起動時の温度が 2 5 °C、 テストリード Zライトを行なつ て算出された最適レーザパワーが" 6 2 "であったとき、 レーザパワーの初期ィ直" 6 4 "を" 6 2 "に更新する。 次に、 補間処理においては、 2 5 °Cにおけるレーザパヮ 一を基点として、 他の温度についてのレーザパワーを全て同じ値" 2 "だけ減少さ せることにより、 温度傾斜を保持した補間を行なって、 管理テーブルを更新する のである。 図 7は、 ディスク温度とレーザパワーの初期値との関係が、 2 5 °Cで のテストリードノライトによって更新された例を示している。 この様に、 温度傾 斜を一定に保ちつつ、 管理テーブルが更新される。 For example, as shown in FIG. 6, the relationship between the disk temperature and the initial value of the laser power, When the slope of the change in laser beam temperature with respect to the disk temperature (hereinafter referred to as the temperature slope) is specified, the temperature at startup is 25 ° C, and the optimum laser power calculated by performing a test read Z write is If it is "6 2", update "6 4" to "6 2". Next, in the interpolation processing, from the laser power at 25 ° C. as a base point, the laser powers for the other temperatures are all reduced by the same value “2” to perform interpolation while maintaining the temperature gradient. It updates the management table. FIG. 7 shows an example in which the relationship between the disk temperature and the initial value of the laser power is updated by a test read / write at 25 ° C. In this way, the management table is updated while keeping the temperature gradient constant.
その後、 通常再生時には、 先ず図 2のステップ S 7にて、 ディスク温度 Tを検 出し、 ステップ S 8では、 ディスク温度が 5 °C以上、 上昇したかどうかを判断し、 ここでイエスと判断されたときは、 ステップ S 9にて、 システム温度 T— sysを温 度 Tに更新する。 次に、 ステップ S 1 0では、 その温度が管理テーブルで既に経 験している温度であるかどうかを判断し、 ここでノーと判断されたときは、 ステ ップ S 1 1にて、 図 3に示すテストリードノライト及び管理テーブル更新ルーチ ンを実行する。  Thereafter, during normal playback, first, the disk temperature T is detected in step S7 of FIG. 2, and in step S8, it is determined whether the disk temperature has risen by 5 ° C. or more. In step S9, the system temperature T—sys is updated to the temperature T in step S9. Next, in step S10, it is determined whether or not the temperature is the temperature which has already been experienced in the management table. If the determination is no, the process proceeds to step S11. Execute the test read no-write and management table update routine shown in (1).
例えば図 6の例において、 1回目のテストリード Zライトが 3 0 °Cで行なわれ た場合、 テストリード Zライトによって求められた最適レーザパワー力 5 9 "で あつたとき、 レーザパワー" 5 7 "を" 5 9 "に更新すると共に、 2 5 °Cと 3 0 °Cの 間のレーザパヮーを補間処理（線形補間）によって求め、 2 5 °C未満と 3 0 °C以上 の温度範囲については、 温度傾斜を一定に保つ補間処理が行なわれて、 管理テー ブルが更新される。 図 8は、 上記テストリード/ライトによって管理テーブルが 更新された状態を示している。  For example, in the example of FIG. 6, when the first test read Z-write is performed at 30 ° C., when the optimum laser power power obtained by the test read Z-write is “59”, the laser power is “57”. "" Is updated to "59", and the laser power between 25 ° C and 30 ° C is obtained by interpolation (linear interpolation). For the temperature range below 25 ° C and above 30 ° C, Then, the interpolation processing is performed to keep the temperature gradient constant, and the management table is updated Fig. 8 shows a state in which the management table is updated by the test read / write.
更に、 2回目のテストリード Zライトが 3 5 °Cで行なわれた場合において、 図 6の如くテストリード Zライ トによって求められた最適レーザパワー力 5 0 "で あつたとき、 レーザパワー" 5 4 "を" 5 0 "に更新すると共に、 3 0 °Cと 3 5 °Cの 間のレーザパワーを捕間処理 (線形補間）によって求め、 3 5 °C以上の温度範囲に ついては、 温度傾斜を一定に保つ補間処理が行なわれて、 管理テーブルが更新さ れる。 図 9は、 上記テストリード ライトによって管理テーブルが更新された状 態を示している。 Furthermore, when the second test read Z-write was performed at 35 ° C and the optimum laser power force 50 "obtained by the test read Z-write was as shown in Fig. 6, the laser power" 5 " 4 "to" 50 ", with 30 ° C and 35 ° C The interpolating process (linear interpolation) is used to determine the laser power during the period, and for the temperature range of 35 ° C or higher, an interpolation process is performed to keep the temperature gradient constant, and the management table is updated. FIG. 9 shows a state in which the management table has been updated by the test read / write.
この様にして、 5 °C以上の温度変化が生じる度にテストリード Zライトが実行 されて、 その温度での最適レーザパワーが求められると共に、 そのデータを用い た補間処理が実行されて、 管理テーブルが更新されていくことになる。 そして、 管理テーブルの経験済み項の全てにチェックが付けられると、 その後の通常動作 においては、 管理テーブルに格納されている温度とレーザパワーの関係を参照す ることによって、 リードパワー P r及びライトパワー P wがセッ トされて、 信号 の記録及び再生が行なわれる。  In this way, every time a temperature change of 5 ° C or more occurs, a test read Z-write is performed to determine the optimum laser power at that temperature, and an interpolation process using that data is performed to perform management. The table will be updated. When all the experienced items in the management table are checked, in the subsequent normal operation, the read power Pr and the write power are referred to by referring to the relationship between the temperature and the laser power stored in the management table. The power P w is set, and signal recording and reproduction are performed.
即ち、 通常動作においては、 図 4に示す如くステップ S 3 1にてディスク温度 を検出した後、 ステップ S 3 2にて記録再生要求が発せられているかどうかを判 断し、 ここでイエスと判断されたときは、 ステップ S 3 3にて管理テーブルを参 照し、 ステップ S 3 4では、 そのときの温度に応じたレーザパワー P r、 P wを セットする。 そして、 ステップ S 3 5にて記録、 再生動作を実行して、 手続きを 終了する。  That is, in normal operation, as shown in FIG. 4, after detecting the disk temperature in step S31, it is determined in step S32 whether a recording / reproducing request has been issued, and the determination is yes here. If so, the control table is referred to in step S33, and in step S34, the laser power Pr and Pw according to the temperature at that time are set. Then, in step S35, the recording and reproducing operations are executed, and the procedure ends.
次に、 再生パワーを最適化する手法について説明する。 本実施例では、 最適再 生パワー決定のためのテストリードにおいて、 エラーレートが規定値を下回るこ ととなる再生パワーの 2つの限界値の内、 値が小さい方の下方限界値 P r rainを検 索するために、 図 1 3及び図 1 4に表わされる手続きが採用されている。 即ち、 再生パワーの初期値によって図 1 3に示す 3つの状態を想定し、 Aの如く再生パ ヮ一が下方限界値を下回っているときは再生パワーを上げ、 Bの如く再生パワー が下方限界 ί直と上方限界値の間のときは再生パヮ一を下げ、 Cの如く再生パヮ一 が上方限界 を上回っているときは再生パワーを下げることによって、 再生パヮ 一を図 1 4に示す下方限界値 P r min若しくはその近傍値まで変化させる。 その後、 その再生パワーに所定値 Nを加算することによって、 最適再生パワー P rを求め るのである。 Next, a method for optimizing the reproduction power will be described. In the present embodiment, in the test read for determining the optimum reproduction power, of the two limit values of the reproduction power at which the error rate becomes lower than the specified value, the lower limit value P rain of the smaller value is set. To search, the procedure shown in Figure 13 and Figure 14 is adopted. That is, assuming the three states shown in Fig. 13 according to the initial value of the reproduction power, when the reproduction power is below the lower limit value as in A, the reproduction power is increased, and as shown in B, the reproduction power is lower. By lowering the playback power when it is between the normal and upper limit values, and by lowering the playback power when the playback power is above the upper limit as shown in C, the playback power is reduced by the lower limit shown in FIG. The value is changed to the value Pr min or a value close to the value Pr min. afterwards, By adding a predetermined value N to the reproduction power, the optimum reproduction power Pr is obtained.
尚、 図 1 3の Aの状態と Cの状態を識別するために、 本実施例では次の原理を 利用した手続きを採用している。 即ち、 光磁気ディスクに記録されている信号は、 複数のフレームを時系列に列べたデータフォーマットを有し、 各フレームにへッ ダ部が設けられ、 各ヘッダ部には、 図 1 8に示す如く、 短い周期（2 T)を有する 単一周波数の第 1基準信号と、 長い周期（ 8 T)を有する単一周波数の第 2基準信 号とが記録されており、 第 1基準信号の再生信号の振幅 W 1と第 2基準信号の再 生信号の振幅 W 2の比率（W 2 ZW 1 )は、 図 1 9に示す如く、 再生パヮー P rが 上昇するにつれて大きくなる。 従って、 該比率が所定の設定値を下回っていると きは図 1 3の Aの状態と判断し、 該比率が所定の設定ィ直を上回っているときは図 1 3の Cの状態と判断することが出来る。  In order to distinguish the states A and C in FIG. 13, the present embodiment employs a procedure using the following principle. That is, the signal recorded on the magneto-optical disk has a data format in which a plurality of frames are arranged in chronological order, a header portion is provided in each frame, and each header portion has the format shown in FIG. As described above, the first reference signal of a single frequency having a short period (2 T) and the second reference signal of a single frequency having a long period (8 T) are recorded, and the reproduction of the first reference signal is performed. As shown in FIG. 19, the ratio (W 2 ZW 1) between the amplitude W 1 of the signal and the amplitude W 2 of the reproduced signal of the second reference signal increases as the reproduction power Pr increases. Therefore, when the ratio is lower than the predetermined set value, it is determined to be the state of A in FIG. 13, and when the ratio is higher than the predetermined setting, it is determined to be the state of C in FIG. You can do it.
図 1 0は、 光磁気ディスクに予め設けられているテストトラックのグループに 対するテストリードによる再生パワー最適化の具体的な手続きを表わしている。 先ず図 1 0のステップ S 4 2にて、 ライトパワー P wとして初期値を設定し、 ス テツプ S 4 3にてテストトラックに対する記録を行なう。 次にステップ S 4 4で は、 再生パワー P rとして初期値を設定し、 ステップ S 4 5にて、 テス トトラッ クの再生を行なって、 そのときのエラーレートが閾値を上回っているかどうかに よって再生の良否を判断する。 ここで O Kと判断されたときは、 図 1 3の Bの状 態であるため、 ステップ S 4 6にて再生パワー P rを単位パワー（" 1 ")だけ下げ て、 ステップ S 4 7にて再度、 テストトラックの再生を行ない、 再生の良否を判 断した後、 ステップ S 4 6に戻って、 同じ手続きを繰り返す。  FIG. 10 shows a specific procedure for optimizing the reproduction power by the test read for a group of test tracks provided in advance on the magneto-optical disk. First, in step S42 of FIG. 10, an initial value is set as the write power Pw, and recording on the test track is performed in step S43. Next, in step S44, an initial value is set as the reproduction power Pr, and in step S45, the test track is reproduced, and depending on whether the error rate at that time exceeds the threshold value or not. The quality of the reproduction is determined. Here, when it is determined to be OK, since the state is B in FIG. 13, the reproducing power Pr is reduced by the unit power ("1") in step S46, and in step S47. The test track is reproduced again, and the quality of the reproduction is determined. Then, the process returns to step S46 to repeat the same procedure.
この結果、 ステップ S 4 7にて N Gと判断されると、 ステップ S 4 8に移行し て、 再生パワー P rを単位パワー（" 1 ")だけ上げた値を下方限界値 Prlとし、 更 にステップ S 4 9では、 下方限界再生パワー P r 1に所定値 N (= 0 . 4 mW)を加 算して、 最適再生パワー P r optとし、 手続きを終了する。 尚、 最適再生パワー P r— optの決定においては、 下方限界再生パワー P r lに所定ィ直ひを乗算する方法 を採用することも可能である。 ここで、 所定値 αは、 システムに依存する値として 予め決定しておくことが出来る。 As a result, if it is determined as NG in step S47, the process proceeds to step S48, in which the value obtained by increasing the reproduction power Pr by the unit power ("1") is set as the lower limit value Prl. In step S49, a predetermined value N (= 0.4 mW) is added to the lower limit reproduction power P r1 to obtain the optimum reproduction power P r opt, and the procedure ends. In addition, the optimal playback power In determining P r — opt, a method of multiplying the lower limit reproduction power P rl by a predetermined value may be adopted. Here, the predetermined value α can be determined in advance as a value depending on the system.
一方、 ステップ S 4 5にて N Gと判断されたときは、 図 1 3の Α又は Cの状態 であるため、 図 1 8及び図 1 9で説明した原理に基づいて、 何れの状態であるか を判別する。 即ち、 図 1 0のステップ S 5 0にて、 前述の基準信号の比率 (W 2 / W 1 )が設定値 Aを上回つているかどうかを判断し、 これによつて再生パヮーを変 化させる方向を認識する。 尚、 基準信号の比率 (W 2 /W 1 )に代えて、 基準信号 の差（W 2— W 1 )が設定値を上回つているかどうかによつて再生パヮ一を変化さ せる方向を認識することも可能である。  On the other hand, when it is judged as NG in step S45, it is the state of Α or C in FIG. 13 and therefore, based on the principle described in FIGS. 18 and 19, which state is Is determined. That is, in step S50 of FIG. 10, it is determined whether or not the ratio (W 2 / W 1) of the above-described reference signal exceeds the set value A, thereby changing the reproduction power. Recognize direction. It should be noted that instead of the ratio of the reference signal (W2 / W1), the direction in which the playback power is changed is recognized based on whether or not the difference (W2-W1) between the reference signals exceeds the set value. It is also possible.
ステップ S 5 0にてイエスと判断されたときは、 図 1 3の Cの状態であるため、 ステップ S 5 1に移行して、 再生パワー P rを所定値 riだけ低下させた後、 ステ ップ S 5 2にて、 再生パワー P rが設定下限値 P r— minよりも大きいかどうかを 判断する。 ここでイエスと判断されたときは、 ステップ S 5 3に移行して、 テス トトラックの再生を行なって、 再生の良否を判断する。 ステップ S 5 3にて N G と判断されたときはステップ S 5 1に戻って再生パワー P rを所定値 nだけ低下 させる処理を繰り返す。 その結果、 ステップ S 5 3にて O Kと判断されると、 図 1 3の Bの状態に変化したため、 ステップ S 4 6に移行して、 上述の手続きの実 行により最適再生パワー P r— optを求めて、 手続きを終了する。  If the determination is YES in step S50, the state is indicated by C in FIG. 13, so the flow shifts to step S51 to reduce the reproduction power Pr by a predetermined value ri. In step S52, it is determined whether or not the reproduction power Pr is larger than the set lower limit Pr-min. If the determination is yes here, the process proceeds to step S53, where the test track is reproduced, and the quality of the reproduction is determined. If NG is determined in step S53, the process returns to step S51 to repeat the process of reducing the reproduction power Pr by the predetermined value n. As a result, if it is determined to be OK in step S53, the state changes to B in FIG. 13 and the process proceeds to step S46 to execute the above-described procedure to obtain the optimum reproduction power Pr-opt. And end the procedure.
ステップ S 5 0にてノーと判断されたときは、 図 1 3の Aの状態であるため、 ステップ S 5 7に移行して、 再生パワー P rを単位パワー（" 1 ")だけ増大させた 後、 ステップ S 5 8にて、 再生パワー P rが設定上限値 P r— maxよりも小さいか どうかを判断する。 ここでイエスと判断されたときは、 ステップ S 5 9に移行し て、 テストトラックの再生を行なって、 再生の良否を判断する。 ステップ S 5 9 にて N Gと判断されたときはステップ S 5 7に戻って再生パワー P rを增大させ る処理を繰り返す。 その結果、 ステップ S 5 9にて O Kと判断されたとき、 ステ ップ S 6 0に移行して、 そのときの再生パワー P rを下方限界値 P rlとした後、 ステップ S 4 9に移行して、 下方限界再生パワー P r 1に所定値 N (= 0 . 4 mW) を加算することにより、 最適再生パワー P r— optを求めて、 手続きを終了する。 ステップ S 5 2或いはステップ S 5 8にてノーと判断されたときは、 ステップ S 5 4へ移行して、 記録パワー P wを所定値 nだけ増大させた後、 ステップ S 5 5に移行して、 記録パワー P wが設定上限値 P w— maxよりも小さいかどうかを判 断し、 ここでイエスと判断されたときはステップ S 4 3に移行して、 テストトラ ックライト手続きに移行するが、 ノーと判断されたときは、 ステップ S 5 6にて、 警報" N G"を発すると共に、 テストトラックを N Gとして登録する。 尚、 テスト トラックのランドに対するテストリードについても同様の手続きによって、 最適 再生パワー P r— optを求めることが出来る。 When it is determined NO in step S50, it is in the state of A in FIG. 13, so the process proceeds to step S57, and the reproduction power Pr is increased by the unit power ("1"). Thereafter, in step S58, it is determined whether or not the reproduction power Pr is smaller than the set upper limit value Pr-max. If the determination is yes here, the process proceeds to step S59, where the test track is reproduced, and the quality of the reproduction is determined. If it is determined as NG in step S59, the process returns to step S57 to repeat the process of increasing the reproduction power Pr. As a result, when it is determined in step S59 that it is OK, the step After moving to step S60, the reproduction power Pr at that time is set to the lower limit value Prl, and then to step S49, the lower limit reproduction power Pr1 is set to the predetermined value N (= 0 4 mW) to obtain the optimum reproduction power Pr-opt, and terminate the procedure. If it is determined NO in step S52 or S58, the process proceeds to step S54, in which the recording power P w is increased by a predetermined value n, and then the process proceeds to step S55. Then, it is determined whether the recording power P w is smaller than the set upper limit value P w—max. If the determination is yes, the process proceeds to step S43, and the process proceeds to the test track write procedure. If it is determined in step S56, an alarm "NG" is issued and the test track is registered as NG in step S56. Note that the optimum reproduction power Pr-opt can be obtained by the same procedure for the test read for the land of the test track.
又、 最適記録パワーの決定においても、 上述した再生パワー最適化手法と同様 の手法を用いることが出来る。 図 1 1は、 該手法による記録パワー最適化の具体 的手続きを表わしている。 テス トリードが完了して、 最適ではないが記録可能な 記録パワーの初期値と、 最適な再生パワーとが決まっている状態で、 先ずステツ プ S 6 3では、 記録パワー P wを初期値に設定し、 ステップ S 6 4にて、 テス ト トラックに対する記録と再生を行なって、 再生の良否を判断する。 ここで N Gと 判断されたときは、 ステップ S 6 5にて、 警報" N G"を発すると共に、 テストト ラックを N Gとして登録する。 又、 動作中は、 記録パワーを初期値に保持する。 一方、 ステップ S 6 4にて O Kと判断されたときは、 記録パワー P wを単位パ ヮー" 1 "だけ低下させた後、 ステップ S 6 7にて記録パワー P wが設定下限値 P wjinよりも大きいかどうかを判断し、 ここでノーと判断されたときはステップ S 6 5 へ移行して、 警報" N G"を発すると共に、 テス トトラックを N Gとして登 録する。 又、 動作中は、 記録パワーを初期値に保持する。 ステップ S 6 7にてィ エスと判断されたときは、 ステップ S 6 8にてテス ト トラックに対する記録と再 生を行なって、 再生の良否を判断する。 ここで O Kと判断されたときはステップ S 6 9に移行して、 ライトデータを変更し、 或いはライトする場所をずらした上 で、 ステップ S 6 6へ戻り、 記録パワーを低下させる手続きを繰り返す。 Also, in determining the optimum recording power, a method similar to the above-described reproducing power optimizing method can be used. FIG. 11 shows a specific procedure for optimizing the recording power by the method. In the state where the initial value of the recording power that is not optimal but recordable after the test read is completed and the optimal reproduction power are determined, first in step S63, the recording power P w is set to the initial value. Then, in step S64, recording and reproduction on the test track are performed to determine the quality of reproduction. If it is determined to be NG here, an alarm "NG" is issued in step S65 and the test track is registered as NG. During operation, the recording power is kept at the initial value. On the other hand, if it is determined to be OK in step S64, the recording power Pw is reduced by the unit power "1", and then the recording power Pw is reduced from the set lower limit Pwjin in step S67. Is determined to be larger, the process proceeds to step S65 to issue an alarm "NG" and register the test track as NG. During operation, the recording power is kept at the initial value. If the answer is yes in step S67, recording and playback are performed on the test track in step S68 to determine the quality of playback. If it is judged OK here, step Proceeding to S69, after changing the write data or shifting the write position, the process returns to step S66, and the procedure for lowering the recording power is repeated.
その後、 ステップ S 6 8にて N Gと判断されたとき、 ステップ S 7 0に移行し て、 そのときの記録パワー P wに単位パワー" 1 "を加算して、 下限限界値 P wlと した後、 ステップ S 7 1に移行して、 下方限界記録パワー P r 1に所定値 Nを加算 することにより、 最適記録パワー P w— optを求めて、 手続きを終了する。 尚、 最 適記録パヮー P w— optの決定においては、 下方限界記録パヮー P wlに所定値 αを乗 算する方法を採用することも可能である。 ここで、 所定値 αは、 システムに依存す る値として予め決定しておくことが出来る。  Thereafter, when it is determined as NG in step S68, the process proceeds to step S70, and the unit power "1" is added to the recording power Pw at that time to obtain the lower limit value Pwl. Then, the flow shifts to step S71, where a predetermined value N is added to the lower limit recording power Pr1, thereby obtaining the optimum recording power Pw-opt, and the procedure is ended. In determining the optimum recording power Pw-opt, it is also possible to adopt a method of multiplying the lower limit recording power Pwl by a predetermined value α. Here, the predetermined value α can be determined in advance as a value depending on the system.
最適記録パワーの決定には、 更に、 図 1 6に示す如く記録パワーとビッ トエラ 一レートの関係を 2次曲線で近似する手法を採用することが出来る。 例えば、 デ イスクに予め設けられているテストトラックを利用して、 該テストトラックに対 し、 異なるレーザパワーで信号の記録を行なった後、 適当なレーザパワーで信号 の再生を行なって、 その再生信号のエラーレートを検出する。 これによつて、 図 1 6に示す如く 3点 P l、 Ρ 2及び Ρ 3でのレーザパワー（記録パワー）とエラー レートの関係がプロットされることになる。 該関係は、 近似的に 2次曲線で表わ すことが出来、 該 2次曲線は、 少なくとも 3点における座標値が決まれば、 一義 的に決まることになる。  To determine the optimum recording power, a method of approximating the relationship between the recording power and the bit error rate by a quadratic curve as shown in FIG. 16 can be further employed. For example, using a test track provided in advance on a disk, recording a signal on the test track with a different laser power, and then reproducing the signal with an appropriate laser power and reproducing the signal. Detect the error rate of the signal. As a result, the relationship between the laser power (recording power) and the error rate at the three points P l, Ρ 2 and Ρ 3 is plotted as shown in FIG. The relationship can be approximately represented by a quadratic curve, and the quadratic curve is uniquely determined if coordinate values at least at three points are determined.
そこで、 上記の 3点 P l、 Ρ 2及び Ρ 3でのレーザパワーとエラーレートの値 を用いて、 レーザパワーとエラーレートの関係を表わす 2次曲線を求めることが 出来、 図 1 6の如く、 該 2次曲線の頂点に対応するレーザパワーが、 エラーレー トを最小化する最適レーザパヮー P woとなる。  Therefore, a quadratic curve representing the relationship between the laser power and the error rate can be obtained by using the values of the laser power and the error rate at the three points Pl, Ρ2, and Ρ3, as shown in FIG. The laser power corresponding to the apex of the quadratic curve is the optimum laser power P wo that minimizes the error rate.
図 1 2は、 2次曲線近似に基づく記録パワー最適化の手続きを表わしている。 テス トリードが完了して、 最適ではないが記録可能な記録パワーの初期値と、 最 適な再生パワーとが決まっている状態で、 先ずステップ S 8 3では、 記録パワー P wを初期値に設定し、 ステップ S 8 4にて、 テストトラックに対する記録と再 生を行なって、 再生の良否を判断する。 ここで NGと判断されたときは、 ステツ プ S 8 5にて、 警報" NG"を発すると共に、 テストトラックを NGとして登録す る。 又、 動作中は、 記録パワーを初期値に保持する。 FIG. 12 shows a procedure of recording power optimization based on quadratic curve approximation. After the test read is completed and the optimum recording power that is not optimal but recordable, and the optimal reproduction power are determined, first, in step S83, the recording power P w is set to the initial value. Then, in step S84, recording and We make a live and judge the quality of reproduction. If it is determined to be NG here, an alarm "NG" is issued in step S85, and the test track is registered as NG. During operation, the recording power is kept at the initial value.
一方、 ステップ S 84にて OKと判断されたときは、 そのときの記録パワー P wlとビットエラーレート BERとをメモリに格納する。 次にステップ S 87では、 記録パワー Pwを所定値 nだけ低下させた後、 ステップ S 88にてテストトラッ クに対する記録と再生を行なって、 再生の良否を判断する。 ここで OKと判断さ れたときはステップ S 87に戻って、 記録パワーを低下させる手続きを繰り返す。 この結果、 ステップ S 88にて NGと判断されたときは、 ステップ S 89に移行 して、 NGとなった記録パワー Pw2とビットエラーレート BERとをメモリに格 納する。  On the other hand, if it is determined to be OK in step S84, the recording power P wl and the bit error rate BER at that time are stored in the memory. Next, in step S87, the recording power Pw is reduced by a predetermined value n, and then recording and reproduction are performed on the test track in step S88 to determine the quality of reproduction. Here, if it is determined to be OK, the procedure returns to step S87, and the procedure for lowering the recording power is repeated. As a result, when it is determined as NG in step S88, the process proceeds to step S89, and the NG recording power Pw2 and the bit error rate BER are stored in the memory.
続いて、 ステップ S 90では、 記録パワー Pwを所定値 nだけ増大させた後、 ステップ S 91にてテストトラックに対する記録と再生を行なって、 再生の良否 を判断する。 ここで OKと判断されたときはステップ S 90に戻って、 記録パヮ 一を増大させる手続きを繰り返す。 この結果、 ステップ S 91にて NGと判断さ れたときは、 ステップ S 92に移行して、 NGとなった記録パワー Pw3とビット エラーレート BERとをメモリに格納する。 その後、 ステップ S 93にて、 メモ リに格納されている 3点のデータ（Pwl， BER1)、 (Pw2, BER2)、 (Pw3, BER3)を 用いて、 レーザパワーとビッ トエラーレートの関係を 2次曲線で近似し、 該曲線 の中心軸となる記録パワーを最適値 Pw__optとして算出する。 そして、 ステップ S 94では、 その最適値 Pw— optを記録パワー Pwとして設定し、 手続きを終了 する。  Subsequently, in step S90, after increasing the recording power Pw by a predetermined value n, recording and reproduction with respect to the test track are performed in step S91, and the quality of reproduction is determined. Here, when it is determined to be OK, the process returns to step S90, and the procedure for increasing the recording power is repeated. As a result, when it is determined as NG in step S91, the process proceeds to step S92, and the NG recording power Pw3 and the bit error rate BER are stored in the memory. Then, in step S93, the relationship between the laser power and the bit error rate is determined using the three data points (Pwl, BER1), (Pw2, BER2), and (Pw3, BER3) stored in the memory. Approximate by a quadratic curve, and calculate the recording power as the central axis of the curve as the optimum value Pw__opt. Then, in step S94, the optimum value Pw-opt is set as the recording power Pw, and the procedure ends.
上述の如く、 本発明に係るディスク記録再生装置によれば、 最適再生パワー決 定のためのテストリードにおいて、 最適な記録パワーが不明の状態で、 記録パヮ 一に依存しない最適な再生パワーを少ないステップ数で決定することが出来、 更 にその後の最適記録パワー決定のためのテストライトにおいて、 テストリードで 求まった最適再生パワーを用いて、 より少ないステツプ数で最適な記録パヮーを 決定することが出来、 全体を通して、 簡易な手続きにより精度の高い最適再生パ ヮー及び最適記録パワーを設定することが可能である。 これによつて、 システム の起動後、 短時間で信号再生或いは信号記録に移ることが出来、 信号再生及び信 号記録を精度良く行なうことが出来る。 As described above, according to the disk recording / reproducing apparatus of the present invention, in the test read for determining the optimum reproducing power, the optimum reproducing power independent of the recording power is reduced in a state where the optimum recording power is unknown. It can be determined by the number of steps, and in the subsequent test write to determine the optimum recording power, Using the obtained optimum reproduction power, the optimum recording power can be determined with a smaller number of steps. Throughout the entire procedure, it is possible to set a high-precision optimum reproduction power and optimum recording power by a simple procedure. is there. As a result, after starting the system, signal reproduction or signal recording can be started in a short time, and signal reproduction and signal recording can be performed accurately.

Claims

請 求 の 範 囲 The scope of the claims
1 . ディスクに光学ヘッドからレーザ光を照射して、 該ディスクに信号を記録し、 若しくは該ディスクから信号を再生するディスク再生装置において、 光学へッド に駆動信号を供給して光学へッドが出射するレーザ光のパワーを調整することが 可能なレーザ駆動回路と、 信号再生状態の良否を表わす評価データを検出する評 価データ検出回路と、 評価データ検出回路の出力に基づいてレーザ駆動回路の動 作を制御する制御回路とを具え、 該制御回路は、 ディスクの温度を検出する温度 検出手段と、 評価データが規定値を越えない様に信号記録時若しくは信号再生時 のレーザ光のパワーを最適化するレーザパワー最適化手段と、 ディスク温度と最 適レーザパワーの関係を格納すべきテープル手段と、 テーブル手段にディスク温 度と最適レーザパヮ一を登録するテーブル登録手段と、 テープノレ手段からデイス ク温度に応じた最適レーザパヮーを導出する最適レーザパヮ一導出手段とを具え ていることを特徴とするディスク記録再生装置。 1. In a disc reproducing apparatus that irradiates a laser beam to a disc from an optical head and records a signal on the disc or reproduces a signal from the disc, a drive signal is supplied to the optical head to supply the optical head with a drive signal. A laser drive circuit that can adjust the power of the laser light emitted by the laser, an evaluation data detection circuit that detects evaluation data that indicates the quality of the signal reproduction state, and a laser drive circuit based on the output of the evaluation data detection circuit. A control circuit for controlling the operation of the laser beam, the control circuit comprising: a temperature detecting means for detecting the temperature of the disk; and a power of the laser beam at the time of signal recording or signal reproduction so that the evaluation data does not exceed a specified value. Means for optimizing laser power, table means for storing the relationship between disk temperature and optimum laser power, and means for table temperature A disc recording / reproducing apparatus comprising: a table registration unit for registering an appropriate laser beam; and an optimum laser beam deriving device for deriving an optimum laser beam corresponding to a disk temperature from a tape holding device.
2 . レーザパワー最適化手段は、 ディスク温度が所定温度だけ変化する度にレー ザパワーの最適化を実行し、 テーブル登録手段は、 レーザパワー登録手段から得 られる温度と最適レーザパワーをテーブル手段に登録する登録処理手段と、 既に テ一プル手段に最適レーザパワーが登録されている温度と新たにレーザパワーの 最適化が実行された温度との間の温度範囲で、 各温度におけるレーザパワーの最 適値を補間によって算出する演算処理手段とを具えている請求の範囲第 1項に記 載のディスク記録再生装置。 2. The laser power optimization means performs laser power optimization each time the disk temperature changes by a predetermined temperature, and the table registration means registers the temperature and the optimum laser power obtained from the laser power registration means in the table means. The optimum laser power at each temperature in the temperature range between the temperature at which the optimum laser power has already been registered in the tape means and the temperature at which the new laser power has been optimized. 2. The disk recording / reproducing apparatus according to claim 1, further comprising: an arithmetic processing means for calculating a value by interpolation.
3 . テーブル登録手段は更に、 レーザパワー最適化手段による最適化若しくは演 算処理手段による補間が行なわれていない温度を対象として、 既に最適化若しく は補間によって求められている近傍温度の最適レーザパヮ一と、 温度変化に対す る最適レーザパワーの変化の割合を表わす所定の温度傾斜データとに基づき、 最 適レーザパワーの近似値を算出する近似値算出手段を具えている請求の範囲第 2 項に記載のディスク記録再生装置。 3. The table registering means further targets the temperature which has not been optimized by the laser power optimizing means or interpolated by the arithmetic processing means to the optimum laser power of the neighboring temperature which has already been obtained by optimization or interpolation. Claim 2 comprising an approximate value calculating means for calculating an approximate value of the optimum laser power based on predetermined temperature gradient data indicating a rate of change of the optimum laser power with respect to the temperature change. Item 10. A disk recording / reproducing device according to Item 1.
PCT/JP2002/000612 2001-01-30 2002-01-28 Disc recorder/reproducer WO2002061744A1 (en)

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JPH03276430A (en) * 1990-03-26 1991-12-06 Fuji Electric Co Ltd Laser power adjusting device for optical disk device
JPH06162508A (en) * 1992-11-25 1994-06-10 Ricoh Co Ltd Optical information recording and reproducing device
JPH06267073A (en) * 1993-03-12 1994-09-22 Olympus Optical Co Ltd Optical disc driving apparatus

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Publication number Priority date Publication date Assignee Title
JPH03276430A (en) * 1990-03-26 1991-12-06 Fuji Electric Co Ltd Laser power adjusting device for optical disk device
JPH06162508A (en) * 1992-11-25 1994-06-10 Ricoh Co Ltd Optical information recording and reproducing device
JPH06267073A (en) * 1993-03-12 1994-09-22 Olympus Optical Co Ltd Optical disc driving apparatus

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