JP2004171768A - Optical disk recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to perform a high definition recording even if a surface wobbling and an eccentricity are caused on an optical disk and to make it possible to highly accurately detect appropriate recording power even if the surface wobbling and eccentricity are caused on an optical disk. <P>SOLUTION: A record signal is recorded by modulating an optical beam to recording power by which recording is performed and non-recording power by which recording is not performed in accordance with the record signal and irradiating a track of an optical disk with the modulated optical beam. At the time, a light beam output in the recording power is compensated so as to cancel the periodic variation component by detecting the periodic variation component of an light beam return light detected output caused by wobbly surface and eccentricity of the disk caused repeatedly in accordance with turning of the disk. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to an optical disk recording method, and performs high-quality recording even if the optical disk has surface runout (undulation in the circumferential direction of the disk substrate) or eccentricity (eccentricity of a track (guide groove or the like) with respect to the central axis of the disk). In addition, an appropriate recording power can be obtained with high accuracy even if the optical disc has surface runout or eccentricity.

  In a recordable optical disk such as a CD-R (compact disk-recordable), a CD-RW (compact disk-rewritable), and a DVD-R (digital versatile disk-recordable), predetermined recording is performed before actual recording. Test recording is performed by sequentially changing the recording power of the laser light in the test recording area. After the test recording, the test recording is reproduced to measure the signal quality. Based on the measurement, the recording power at which the best reproduced signal quality is obtained is determined. Then, the recording power of the laser beam is set to the determined recording power, and the actual recording is started.

  The optical disc has surface runout and eccentricity due to manufacturing errors, aging, and the like. If there is surface deflection, the angle formed by the laser optical axis with respect to the track changes periodically (one rotation of the disk as one cycle), and the amount of defocus also changes periodically. The light amount (illuminance) of light fluctuates periodically. In addition, if there is eccentricity, the tracking shift amount periodically changes, so that the light amount of the laser beam applied to the track periodically changes. For this reason, if the optical disc has surface runout or eccentricity, even if the recording power is kept constant, the recording quality differs depending on the position in the disc circumferential direction, and high-quality recording can be performed over the entire circumference of the disc. could not. In particular, this phenomenon was more remarkable when recording was performed with a higher recording speed magnification. Also, at the time of test recording, since recording is performed in a state affected by surface runout and eccentricity, the optimum recording power cannot be obtained with high accuracy.

  In order to cope with a fluctuation in the optimum recording power due to a rise in the temperature of the disk substrate during recording or a change in the film thickness of the recording film at a position in the disk radial direction (this occurs when the recording film is formed by spin coating), etc. Conventionally, ROPC (Running Optimum Power Control: real-time optimal power control) or the like is called for to determine the optimal recording power in real time during actual recording, and the recording power of laser light is controlled to the detected optimal recording power. Although there is a method, this method generally responds to a change in the state of the disk in the radial direction, so that the response is extremely slow, and it is not possible to cope with fluctuations in the circumference of the disk such as surface deflection and eccentricity. Was.

  The present invention has been made in view of the above points, and can perform high-quality recording even if the optical disc has runout or eccentricity, and can perform appropriate recording even if the optical disc has runout or eccentricity. It is an object of the present invention to provide an optical disk recording method capable of detecting power with high accuracy.

  The optical disk recording method of the present invention modulates a light beam into a recording power at which recording is performed and a non-recording power at which recording is not performed in accordance with a recording signal, and irradiates the track of the optical disk with the light beam. In an optical disk recording method for performing recording, prior to actual recording, test recording is performed by sequentially changing the recording power for one round of the disk, and after the test recording, the test recording is reproduced, and the asymmetry value at each recording power is measured. A linear or quadratic approximation characteristic of the recording power value versus the asymmetry value is obtained from the measured value, and a recording power value that achieves a predetermined target value of the asymmetry value is obtained from the obtained linear or quadratic approximation characteristic. The recording power value thus set is set as the recording power command value at the start of the actual recording, and the actual recording is started. That is, if the optical disc has surface runout or eccentricity, a sine wave-like undulation occurs in the recording power value-asymmetry value characteristic, and when the recording power value that realizes the target asymmetry value is obtained from this characteristic, the target asymmetry value is realized. An error has occurred with respect to the true recording power value, and high-quality recording cannot be performed if the actual recording is performed with the recording power value set to the value causing the error. Therefore, by obtaining a linear or quadratic approximation characteristic from the measurement result of the recording power value versus the asymmetry value characteristic based on test recording for one round of the disk, the surface runout component and the eccentric component of the optical disk included in the characteristic are canceled out. Thus, a recording power value that achieves the target asymmetry can be obtained with high accuracy, and by performing the actual recording with the recording power value set to the obtained value, high-quality recording can be performed. Note that the approximate characteristics can be obtained by, for example, the least squares method. Further, one round of the disk can be detected by counting, for example, FG pulses obtained from an FG (frequency generator) as the disk rotates.

  The optical disk recording method of the present invention modulates a light beam into a recording power at which recording is performed and a non-recording power at which recording is not performed in accordance with a recording signal, and irradiates the track of the optical disk with the light beam. In an optical disc recording method for performing recording, test recording is performed by sequentially changing the recording power prior to the actual recording, and after the test recording, the test recording is reproduced, and the recording power value-asymmetry value characteristic and the asymmetry value-recording signal quality characteristic are recorded. Is determined from the asymmetry value versus the recording signal quality characteristic, the center of gravity of the characteristic in the asymmetry value direction is determined, and the recording power value that realizes the determined asymmetry value is determined from the recording power value versus asymmetry value characteristic. The set recording power value is set as a recording power command value at the start of the actual recording, and the actual recording is started. According to this, a value near the center of the asymmetry value range in which the recording signal quality is excellently obtained, that is, an asymmetry value in which a wide power margin is obtained (the recording signal quality is good and the recording signal quality is changed due to the fluctuation of the recording power value). An asymmetry value with a small decrease) can be obtained, and by using the asymmetry value as a target asymmetry value and determining a recording power value for realizing the target asymmetry value from a recording power value-asymmetry value characteristic, an appropriate recording power value can be obtained. High-quality recording can be performed by setting the recording power value to the obtained value with high accuracy and performing actual recording. As the parameters of the recording signal quality, for example, an occurrence rate of a C1 error (Reed-Solomon correction one level error), an occurrence rate of a CU error (uncorrectable error), an out-of-synchronization occurrence rate, a jitter amount, and the like can be used.

  The embodiments of the invention described below include the invention of the following optical disk recording method or optical disk recording device. That is, in the optical disk recording method, a light beam is modulated according to a recording signal into a recording power at which recording is performed and a non-recording power at which recording is not performed, and is irradiated onto a track of the optical disk to record the recording signal. In the optical disc recording method of performing, the cyclically variable component of the light beam return light detection output due to the surface deflection or eccentricity of the optical disk that repeatedly occurs according to the disk rotation is detected, and the periodic variable component is canceled. This is for correcting the light beam output at the time of recording power. According to this, even if the light amount of the laser beam applied to the track periodically changes due to surface deflection or eccentricity of the optical disk, the light beam output at the recording power is corrected so as to cancel the change, High-quality recording can be performed.

  An optical disk recording method is to record a recording signal by irradiating a light beam to a recording power at which recording is performed and a non-recording power at which recording is not performed according to a recording signal and irradiating the track on the optical disk. In the optical disc recording method, a light beam output at a recording power is detected, and the light beam output at a recording power is controlled so that the light beam output coincides with a predetermined target value. A response frequency band different from the light beam output control based on the light beam output detection at the recording power (e.g., such as, for example, detecting the generated periodic fluctuation component of the light beam return light detection output and canceling the periodic fluctuation component). (A response frequency range higher than the light beam output control based on the detection of the light beam output at the recording power) to correct the light beam output at the recording power. . According to this, the light beam output control based on the light beam output detection at the recording power suppresses the fluctuation of the light beam output due to the temperature change and the like, and the light amount of the laser light irradiated on the track due to the surface deflection or eccentricity of the optical disk. Is periodically changed, the light beam output at the time of recording power is corrected so as to cancel the fluctuation, so that high-quality recording can be performed.

  The detection of the periodic fluctuation component of the light beam return light detection output can be performed, for example, in real time in parallel with the recording, or can be performed prior to the recording. The recording of the recording signal can be performed, for example, as actual recording, or as test recording performed by sequentially changing the recording power in order to obtain an appropriate recording power prior to the actual recording. If the recording is performed as the actual recording, high-quality recording can be performed. If the recording is performed as the test recording, an appropriate recording power can be obtained with high accuracy.

  The optical disk recording device records the recording signal by irradiating a light beam to a recording power at which recording is performed and a non-recording power at which recording is not performed according to a recording signal and irradiating the track on the optical disk. A recording power control loop for detecting a light beam output at a recording power and controlling the light beam output at a recording power so that the light beam output coincides with a predetermined target value; A non-recording power control loop for controlling the light beam output at the time of non-recording power so that the light beam return light at the time of power is detected and the return light detection output coincides with a predetermined target value; The response frequency band of the non-recording power control loop is set to a band that responds to the periodic fluctuation component of the light beam return light detection output that repeatedly occurs according to the disk rotation, and The response frequency band of the loop is set to a relatively low band that does not respond to the periodic fluctuation component repeatedly generated according to the disk rotation, and at the time of recording power, the recording power control loop is generated by the recording power control loop. The light beam source is driven according to a composite value of the light beam drive signal and the light beam drive signal generated in the non-recording power control loop, and the light beam output is set to a predetermined target value at the time of recording power. Control.

  The optical disk recording device detects a change in the output of the light beam return light detection at the time of the recording power, which is generated as the recording position moves in the radial direction of the disk, and corrects the change in the output of the return light detection at the time of the recording power. Recording power target value correcting means for generating a value and correcting the target value of the recording power control loop with the correction value. It is set to a frequency band different from the response frequency band of the control loop (for example, a frequency band relatively lower than the response frequency band of the recording power control loop).

  An optical disk recording method is to record a recording signal by irradiating a light beam to a recording power at which recording is performed and a non-recording power at which recording is not performed according to a recording signal and irradiating the track on the optical disk. In the optical disk recording method, prior to recording, a periodic fluctuation component of the light beam return light detection output which repeatedly occurs according to the disk rotation is detected, and the periodic change of the light beam return light detection output according to the disk circumferential position. It is stored in a memory in advance as a component characteristic, and at the time of recording, the disk circumferential position is sequentially detected, and the periodic fluctuation component of the light beam return light detection output at each corresponding disk circumferential position is sequentially read from the memory, The light beam output at the time of recording power is corrected so as to cancel the periodic fluctuation component. According to this, even if the light amount of the laser beam applied to the track periodically changes due to surface deflection or eccentricity of the optical disk, the light beam output at the recording power is corrected so as to cancel the change, High-quality recording can be performed.

  An optical disk recording method is to record a recording signal by irradiating a light beam to a recording power at which recording is performed and a non-recording power at which recording is not performed according to a recording signal and irradiating the track on the optical disk. In the optical disk recording method, prior to recording, a periodic fluctuation component of the light beam return light detection output which repeatedly occurs according to the disk rotation is detected, and the periodic change of the light beam return light detection output according to the disk circumferential position. The component characteristics are stored in a memory in advance, and at the time of recording, the light beam output at the recording power is detected, and the light beam output at the recording power is controlled so that the light beam output matches a predetermined target value. In addition, the disk circumferential position is sequentially detected, and the periodic fluctuation component of the light beam return light detection output at each corresponding disk circumferential position is sequentially read from the memory. And a response frequency band different from the light beam output control based on the light beam output detection at the recording power (for example, higher than the light beam output control based on the light beam output detection at the recording power) so as to cancel the periodic fluctuation component. (Response frequency range) to correct the light beam output at the recording power. According to this, the light beam output control based on the light beam output detection at the recording power suppresses the fluctuation of the light beam output due to the temperature change and the like, and the light amount of the laser light irradiated on the track due to the surface deflection or eccentricity of the optical disk. Is periodically changed, the light beam output at the time of recording power is corrected so as to cancel the fluctuation, so that high-quality recording can be performed.

  The detection of the periodic fluctuation component of the light beam return light detection output, which is repeated prior to recording and repeatedly occurs in accordance with the disk rotation, is performed, for example, by irradiating the optical disk with a predetermined power light beam on which no recording is performed. be able to. The recording of the recording signal can be performed, for example, as actual recording, or as test recording performed by sequentially changing the recording power in order to obtain an appropriate recording power prior to the actual recording.

  The optical disk recording device records the recording signal by irradiating a light beam to a recording power at which recording is performed and a non-recording power at which recording is not performed according to a recording signal and irradiating the track on the optical disk. In an optical disk recording device, a memory for storing a detection characteristic of a periodic variation component of a light beam return light detection output according to a disk circumferential position, which is repeatedly generated according to disk rotation, with respect to a mounted optical disk, And a recording power control loop for controlling the light beam output at the time of recording power so that the light beam output coincides with a predetermined target value. From the memory in accordance with the disk circumferential position detected by the circumferential position detecting means during recording. Light beam output correction means for sequentially reading out the periodic fluctuation component of the light beam return light detection output at the position in the disk circumferential direction to be corrected and correcting the light beam output at the recording power so as to cancel the periodic fluctuation component. Wherein the response frequency band of the recording power control loop is set to a frequency band not responding to the light beam output correction by the light beam output correction means (for example, a frequency band relatively lower than the light beam output correction). It is.

  The optical disk recording device detects a change in the output of the light beam return light detection at the time of the recording power, which is generated as the recording position moves in the radial direction of the disk, and corrects the change in the output of the return light detection at the time of the recording power. Recording power target value correcting means for generating a value and correcting the target value of the recording power control loop with the correction value. It is set to a frequency band different from the response frequency band of the control loop (for example, a frequency band relatively lower than the response frequency band of the recording power control loop).

  Hereinafter, an embodiment in which the present invention is applied to a CD-R / RW drive (an optical disc recording apparatus capable of recording and reproducing a CD-R disc and a CD-RW disc) will be described.

(Embodiment 1)
FIG. 1 shows an optical disc recording apparatus according to a first embodiment of the present invention. This is to detect the surface runout and eccentricity of each disk orbital position at the time of recording in real time, and perform recording while correcting the recording power so as to cancel the surface runout and eccentricity. An optical disc (CD-R disc or CD-RW disc) 10 is driven by a spindle motor 12 and recorded and reproduced by an optical pickup 13. The spindle controller 14 compares the phase of a wobble or ATIP (Absolute Time In Pre-groove) signal detected from the optical disk 10 with a signal obtained by dividing the frequency of the reference clock oscillated from the reference oscillator 16 so that the two synchronize. The spindle motor 12 is controlled. The optical pickup 13 emits laser light 20 from a laser light source 18 such as a semiconductor laser and irradiates the recording surface of the optical disk 10 to perform recording or reproduction. A part of the laser light 20 emitted from the laser light source 18 is received by the front monitor 23. Return light (reflected light) 20a of the main beam from the optical disk 10 is received by a return light detector 22 for the main beam, such as a four-divided photodetector. The reproduction EFM signal output from the return light detector 22 at the time of reproduction is EFM-demodulated by the EFM decoder 24, and the recording signal is demodulated. The recording signal generation circuit 26 generates a recording signal for performing test recording and actual recording. The laser drive circuit 28 is a circuit for driving the laser light source 18, and controls the laser light output to a predetermined reproduction power at the time of reproduction, and at the time of recording, the recording power for performing recording and the recording power according to the recording signal. The signal is modulated to a non-recording power (for example, the same power as the reproducing power).

  FIG. 2 shows a configuration example of the laser drive circuit 28. The laser drive circuit 28 includes a current source 31 for supplying a laser drive current Ib for realizing a reproduction power at the time of reproduction and a non-recording power at the time of recording (at the time of actual recording and test recording), and at the time of recording (at the time of actual recording and test recording). A current source 33 for supplying a current It corresponding to a difference between a laser driving current for realizing recording power during recording and a current Ib supplied from the current source 31. The currents Ib and It supplied from the two current sources 31 and 33 are added by an adder 35 to drive the laser light source 18 to emit the laser light 20. A switch 41 is provided in a supply path of the current source 33 for realizing the recording power, and is turned on and off according to the recording signal output from the recording signal generation circuit 26. Thereby, the laser beam 20 emitted from the laser light source 18 is modulated into a recording power and a non-recording power according to the recording signal during recording. During reproduction, the switch 41 remains off, and the laser light 20 emitted from the laser light source 18 is controlled to reproduction power.

  In FIG. 1, an ALPC1 loop 30 constitutes an ALPC control (Automatic Laser Power Control) loop for controlling the recording power at the time of actual recording to be equal to a predetermined target value. It functions to suppress fluctuations in laser light output. That is, the ALPC1 loop 30 samples and holds the detection output of the front monitor 23 at the recording power timing {see FIG. 3C} in the sample and hold circuit SH1 at the time of the actual recording, and the sample and hold value at the addition point 34. And the recording power target value, and the ALPC1 circuit 36 controls the laser drive circuit 28 to cancel the deviation (in the case of the configuration of FIG. 2, the current value It of the current source 33 is controlled). The recording power is controlled to the target value. The ALPC1 circuit 36 incorporates a low-pass filter LPF1 for setting the response frequency band of the ALPC1 loop 30. At the time of test recording, the ALPC1 circuit 36 indicates a recording power that changes by a predetermined step every predetermined period (for example, one subcode frame) as shown in FIG. 4, for example.

  The non-recording power command value output circuit 37 commands the non-recording power at the time of recording and the reproducing power at the time of reproduction, and controls the laser drive circuit 28 so as to realize the command value (in the case of the configuration of FIG. The current value Ib of the source 31 is controlled.). The ALPC2 loop 38 constitutes an ALPC control loop for controlling the return light detection output at the time of non-recording power to coincide with a predetermined target value during recording (at the time of actual recording and test recording). It functions to suppress the deterioration of the recording quality due to the fluctuation of the irradiation light amount of the laser beam 20 to the track due to the eccentricity and the like. That is, the ALPC2 loop 38 samples and holds the detection output of the return light detector 22 at the non-recording power timing {see FIG. 3D} in the sample and hold circuit SH2 at the time of test recording and actual recording. At the point 40, the sample hold value and the return light intensity target value at non-recording power output from the ALPC2 target value output circuit 42 (a value preset as a standard value of the return light detection output at non-recording power). Is obtained, and the laser drive circuit 28 is controlled via the low-pass filter LPF2 and the addition point 39 so as to cancel the deviation (in the case of the configuration of FIG. 2, the current value Ib of the current source 31 is corrected and controlled). .

  The recording power target value calculation circuit 25 measures the asymmetry value of each step of the recording power from the reproduced EFM signal at the time of reproducing the test recording (solid line in FIG. 5), and calculates the measured value by a linear approximation such as the least square method or the like. The recording power value vs. asymmetry value characteristic is obtained by approximation using the following approximation (dotted line in FIG. 5). The asymmetry value is a value obtained by (a + b) / (ab) where a is the peak level (sign is +) of the reproduced EFM signal waveform and b is the bottom level (sign is-). In a memory (not shown) in the optical disc recording device, an asymmetry value for realizing high-quality recording is stored in advance as a target asymmetry value for each disc type. The disc type is determined, and the corresponding target asymmetry value is read from the memory. Then, the recording power target value calculation circuit 25 obtains a recording power value for realizing the target asymmetry value from the obtained recording power value vs. asymmetry value characteristic (see FIG. 5), and records this value at the beginning of the actual recording. Output as power target value.

  The sample and hold circuit SH3 samples and holds the detection output of the return light detector 22 at the recording power timing {see FIG. 3C}. The ROPC circuit 44 functions to change the target value of the recording power by following a change in the optimum recording power due to a temperature rise of the disk substrate after the start of the actual recording, a change in the thickness of the recording film at a position in the disk radial direction, or the like. The amount of change of the sample-hold value of the sample-hold circuit SH3 after the start of the actual recording with respect to the sample-hold value of the sample-hold circuit SH3 (caused by the change in the intensity of the return light due to the change of the recording state such as the recording depth). ) Is detected, and a correction value of the recording power target value for canceling the variation is created. The created correction value is added to the recording power target value at the start of the actual recording at the addition point 46 to correct the recording power target value. The ALPC1 loop 30 uses this corrected recording power target value as a new recording power target value to control the laser light output of the recording power after the start of the actual recording. The ROPC circuit 44 incorporates a low-pass filter LPF3 for setting its own response frequency characteristic.

  FIG. 6 shows an example of setting the response frequency band of the ALPC1 loop 30, the ALPC2 loop 38, and the ROPC circuit 44 by the low-pass filters LPF1, LPF2, and LPF3. The response frequency band of the ALPC2 loop 38 is set to a band that responds to surface deflection and eccentricity. Thus, during recording, the low-pass filter LPF2 outputs, as shown in FIG. 7, a periodic variation component due to surface deflection, eccentricity, or the like that is repeated every disk rotation. The response frequency band of the ALPC1 loop 30 is set to be lower than that of the ALPC2 loop 38, which responds to a temperature change of the laser light source 18 and does not respond to surface deflection and eccentricity. The response frequency band of the ROPC circuit 44 is a return light detection at the time of recording power due to a state change in a disk radial direction (a temperature rise of a disk substrate during actual recording, a change in a film thickness of a recording film at a position in a disk radial direction, etc.). The band is set lower than that of the ALPC1 loop 30 in response to the output fluctuation. In this way, the response frequency band is divided for each control system, and stable control is realized.

  FIG. 8 shows an example of a control operation by the optical disk recording device of FIG. When the optical disk 10 is mounted on the optical disk recording device, the test recording mode is automatically started. That is, the spindle motor 12 is started (S1), a predetermined non-recording power command value is output from the non-recording power command value output circuit 37, and the return light intensity target value at non-recording power is output from the ALPC2 target value output circuit 42. The ALPC1 circuit 36 outputs a command to output a recording power that changes stepwise, and the laser drive circuit 28 modulates the laser light output into a recording power and a non-recording power according to the test EFM signal to perform test recording ( S2). At this time, the ALPC2 loop 38 is on, and even if the light amount of the laser beam applied to the track fluctuates due to the surface deflection or eccentricity of the optical disk 10, the light beam output at the recording power is canceled so as to cancel the fluctuation. Since the correction is made, test recording can be performed without being affected by surface runout or eccentricity. At the time of test recording, the ALPC1 loop 30 is turned off, and the recording power is controlled in an open loop by the stepwise recording power command value output from the ALPC1 circuit 36. At this time, the true recording power for each step is obtained. The value is detected by the front monitor 23, and a recording power value-asymmetry value characteristic after test recording can be obtained using the detected value of the true recording power for each step. During test recording, the ROPC circuit 44 can also be turned off.

  After the test recording, this is reproduced and the recording power target value calculation circuit 25 measures the asymmetry value for each recording power step (solid line in FIG. 5), and the measurement result (true recording power value for each step) , An approximate characteristic (dotted line in FIG. 5) between the recording power value and the asymmetry value is determined from the asymmetry value data for (a), and the recording power value for realizing the target asymmetry value is determined from the characteristic (S3). Then, the obtained recording power value is set as a recording power target value at the beginning of the actual recording. Now you are ready for production recording. When the actual recording is commanded (S4), a predetermined non-recording power command value (the same value as in test recording) is output from the non-recording power command value output circuit 37, and the non-recording power is output from the ALPC2 target value output circuit 42. The return light intensity target value (the same value as at the time of test recording) is output, and the recording power target value at the start of the actual recording obtained by the test recording is output from the recording power target value calculation circuit 25, and the ALPC1 loop 30, ALPC2 The loop 38 and the ROPC circuit 44 are turned on to start actual recording (S5). During the actual recording, the recording power target value is corrected by the ROPC circuit 44 as necessary, and the ALPC1 loop 30 controls the recording power so as to realize the corrected recording power target value. Further, the periodic fluctuation of the track irradiation light quantity for each track rotation due to the surface runout or eccentricity of the optical disc 10 is canceled by the ALPC2 loop 38. When the recording of the actual recording signal is completed (S6), the actual recording ends (S7).

(Embodiment 2)
FIG. 9 shows an optical disc recording apparatus according to a second embodiment of the present invention. This means that the runout and eccentricity of each disk orbital position are detected in advance and stored in a memory, and the memory is read out at the time of recording according to the disk orbital position and the recording power is reduced so as to cancel the surface runout and eccentricity. The recording is performed while making corrections. The same reference numerals are used for parts common to the first embodiment. The optical disk 10 is driven by a spindle motor 12, and recording and reproduction are performed by an optical pickup 13. The spindle controller 14 compares the phase of a wobble or ATIP signal detected from the optical disc 10 with a signal obtained by dividing the frequency of a reference clock oscillated from the reference oscillator 16 and controls the spindle motor 12 so that the two synchronize. An FG pulse is generated from the spindle motor 12 according to the rotation. The counter 50 is reset at an appropriate circumferential position of the optical disk 10 and counts FG pulses. The optical pickup 13 emits laser light 20 from a laser light source 18 such as a semiconductor laser, and irradiates the recording surface of the optical disk 10. A part of the laser light 20 emitted from the laser light source 18 is received by the front monitor 23. Return light 20a of the main beam from the optical disk 10 is received by a return light detector 22 for the main beam such as a four-division light detector. The reproduction EFM signal output from the return light detector 22 at the time of reproduction is EFM-demodulated by the EFM decoder 24, and the recording signal is demodulated. The recording signal generation circuit 26 generates a recording signal for performing test recording and actual recording. The laser driving circuit 28 is a circuit for driving the laser light source 18, and controls the laser light output to a predetermined reproducing power at the time of reproduction, and performs recording at the time of recording according to a recording signal. Modulation to no non-recording power (for example, the same power as the reproduction power). The laser drive circuit 28 is configured, for example, as shown in FIG.

  The ALPC1 loop 30 samples and holds the detection output of the front monitor 23 at the recording power timing (see FIG. 3C) in the sample and hold circuit SH1 at the time of actual recording, and records the sample and hold value at the addition point 34 with the sample and hold value. The deviation from the power target value is determined, and the ALPC1 circuit 36 controls the laser drive circuit 28 to cancel the deviation (in the case of the configuration of FIG. 2, the current value It of the current source 33 is controlled), and the recording power is adjusted. Is controlled to the target value. The ALPC1 circuit 36 incorporates a low-pass filter LPF1 for setting the response frequency band of the ALPC1 loop 30. At the time of test recording, the ALPC1 circuit 36 indicates a recording power that changes by a predetermined step every predetermined period (for example, one subcode frame) as shown in FIG. 4, for example.

  The non-recording power command value output circuit 37 commands the non-recording power at the time of recording and the reproducing power at the time of reproduction, and controls the laser drive circuit 28 so as to realize the command value (in the case of the configuration of FIG. The current value Ib of the source 31 is controlled.). The control path 52 has a function of suppressing a decrease in recording quality due to a change in the irradiation light amount of the laser beam 20 to the track due to a surface deflection or an eccentricity during recording (during actual recording and test recording). This control path 52 is a training operation prior to the test recording, and detects a surface runout and an eccentric component at each position in the circumferential direction of the optical disk 10 and stores the detected components in the orbiting memory 54. The corresponding wobble and eccentric component are read from the orbiting memory 54 in accordance with the circumferential position, and the recording power is corrected so as to cancel the wobble and eccentric component.

  The training operation prior to the test recording is performed, for example, as follows. The optical disc 10 is driven to rotate, and the laser light source 18 emits a laser beam 20 of non-recording power (reproducing power) to irradiate the optical disc 10, and the return light 20 a is detected by the return light detector 22. The non-recording power return light intensity standard value output circuit 56 outputs a return light intensity standard value at the time of non-recording power (a value preset as a standard value of return light detection output at the time of non-recording power). The return light detection output has a deviation from the return light intensity standard value at the time of non-recording power at the addition point 58, and the deviation signal is output from the low-pass filter LPF4 to noise in a higher frequency range than the surface deflection and the eccentric component. The components are removed to extract the surface runout and eccentric components, which are input to the sample and hold circuit SH4. In this state, the counter 50 is reset at an appropriate circumferential position on the optical disk 10, and the return light detection output is sampled and held by the sample hold circuit SH4 at each FG pulse timing, and the count value of the counter 50 is set as an address value. The orbit memory 54 stores a sample hold value for one round of the disk, that is, a surface deflection and an eccentric component at each circumferential position of the optical disk 10. FIG. 10 shows an example of data stored in the circulation memory 54 in this training operation.

  In FIG. 9, a target recording power calculation circuit 25 measures the asymmetry value of each step of the recording power from the reproduced EFM signal at the time of reproducing the test recording (solid line in FIG. 5), and calculates the measured value by the least square method or the like. The recording power value vs. asymmetry value characteristic is obtained by linear approximation or quadratic approximation (dotted line in FIG. 5). A recording power value for realizing a predetermined target asymmetry value is obtained (see FIG. 5), and this value is output as a recording power target value at the start of actual recording.

  The sample and hold circuit SH3 samples and holds the detection output of the return light detector 22 at the recording power timing {see FIG. 3C}. The ROPC circuit 44 detects a subsequent change in the sample and hold value of the sample and hold circuit SH3 with respect to the sample and hold value of the sample and hold circuit SH3 at the beginning of the actual recording, and corrects the correction value of the recording power target value for canceling the change. Create The created correction value is added to the recording power target value at the start of the actual recording at the addition point 46 to correct the recording power target value. The ALPC1 loop 30 uses this corrected recording power target value as a new recording power target value to control the laser light output of the recording power after the start of the actual recording. The ROPC circuit 44 incorporates a low-pass filter LPF3 for setting its own response frequency characteristic. The response frequency band of the ALPC1 loop 30 is set to a relatively low band that responds to a temperature change of the laser light source 18 and does not respond to surface deflection and eccentricity. The response frequency band of the ROPC circuit 44 is a return light detection at the time of recording power due to a state change in a disk radial direction (a temperature rise of a disk substrate during actual recording, a change in a film thickness of a recording film at a position in a disk radial direction, etc.). The band is set to be lower than that of the ALPC1 loop 30 in response to the output fluctuation.

  FIG. 11 shows an example of a control operation by the optical disk recording device of FIG. When the optical disk 10 is mounted on the optical disk recording device, the training mode and the test recording mode are started automatically. That is, the spindle motor 12 is started, the counter 50 is reset at an appropriate circumferential position of the optical disk 10 (S11), and the above-described training operation stores the surface deflection and the eccentric component in the circumferential memory 54 at each circumferential position of the optical disk 10. Is stored (S12). When the training operation is completed, the test recording mode starts. That is, a predetermined non-recording power command value is output from the non-recording power command value output circuit 37, a recording power that changes stepwise is commanded from the ALPC1 circuit 36, and the laser drive circuit 28 outputs the laser beam output to the test EFM signal. The test recording is performed by modulating the recording power and the non-recording power in accordance with the above (S13). At this time, the counter 50 counts the FG pulse and is reset each time the optical disk 10 reaches the same circumferential position as during the training. Then, using the count value of the counter 50 as address information, the surface runout and the eccentric component at each circumferential position are sequentially read from the orbiting memory 54, and the surface runout and the eccentric component are canceled through the addition point 39. The laser drive circuit 28 is controlled (in the case of the configuration shown in FIG. 2, the current value Ib of the current source 31 is corrected and controlled). Therefore, even if the light amount of the laser beam applied to the track fluctuates due to the surface runout or eccentricity of the optical disk 10, the light beam output at the recording power is corrected so as to cancel out the change. Test recording can be performed without being affected by the above. At the time of test recording, the ALPC1 loop 30 is turned off, and the recording power is controlled in an open loop by the stepwise recording power command value output from the ALPC1 circuit 36. At this time, the true recording power for each step is obtained. The value is detected by the front monitor 23, and the detected value of the true recording power for each step can be used in calculating the recording power value-asymmetry value characteristic after the test recording. During test recording, the ROPC circuit 44 can also be turned off.

  After the test recording, this is reproduced and the recording power target value calculation circuit 25 measures the asymmetry value for each recording power step (solid line in FIG. 5), and the measurement result (true recording power value for each step) The approximate characteristic (dotted line in FIG. 5) between the recording power value and the asymmetry value is obtained from the data of the asymmetry value with respect to (a), and the recording power value realizing the target asymmetry value is obtained from the characteristic (S14). Then, the obtained recording power value is set as a recording power target value at the beginning of the actual recording. Now you are ready for production recording. When the actual recording is commanded (S15), a predetermined non-recording power command value (the same value as in test recording) is output from the non-recording power command value output circuit 37, and the recording power target value calculation circuit 25 performs test recording. The obtained recording power target value at the start of the actual recording is output, and the ALPC1 loop 30 and the ROPC circuit 44 are turned on to start the actual recording (S16). During the actual recording, as in the test recording, the surface runout and the eccentric component at each circumferential position are sequentially read out from the orbiting memory 54 using the count value of the counter 50 as address information, The laser drive circuit 28 is controlled so as to cancel the shake and the eccentric component (in the case of the configuration of FIG. 2, the current value Ib of the current source 31 is corrected and controlled). During the actual recording, the recording power target value is corrected as necessary by the ROPC circuit 44, and the ALPC1 loop 30 controls the recording power so as to realize the corrected recording power target value. When the recording of the actual recording signal is completed (S17), the actual recording ends (S18).

  In the first and second embodiments, the surface eccentricity component is detected from the return light at the time of non-recording power. However, the surface deflection and the eccentricity component can be detected from the return light at the time of recording power. At this time, when the laser drive circuit 28 is configured as shown in FIG. 2, the current value It of the current source 33 is controlled according to the detected surface runout and eccentricity component, and the surface runout and the eccentricity component are reduced. Can be countered.

(Embodiment 3)
In the first and second embodiments, the recording power is corrected in the test recording according to the surface deflection and the eccentricity component. However, the test recording is performed without performing the correction, and the reproduction data of the test recording is used. When the recording power value-asymmetry value characteristic is obtained, the recording power for realizing the target asymmetry value can be obtained with high accuracy by removing the surface deflection and the eccentric component. An example of a control operation when this is realized in the configurations of the first and second embodiments will be described with reference to FIG. When the optical disk 10 is mounted on the optical disk recording device, the test recording mode is automatically started. That is, the spindle motor 12 is started (S21), a predetermined non-recording power command value is output from the non-recording power command value output circuit 37, and the recording power that changes stepwise is commanded from the ALPC1 circuit 36, and the laser driving circuit Reference numeral 28 performs test recording by modulating the laser light output into a recording power and a non-recording power according to the test EFM signal (S22). At this time, the ALPC2 loop 38 is turned off in the configuration of FIG. 1, and the control path 52 is turned off in the configuration of FIG. 9 to stop the recording power correction operation. The number of steps of the recording power is set so that this test recording is completed in just one round or almost one round of the disk. At the time of test recording, the ALPC1 loop 30 is turned off, and the recording power is controlled in an open loop by the stepwise recording power command value output from the ALPC1 circuit 36. At this time, the true recording power for each step is obtained. The value is detected by the front monitor 23, and a recording power value-asymmetry value characteristic after test recording can be obtained using the detected value of the true recording power for each step. During test recording, the ROPC circuit 44 can also be turned off.

  After the test recording, this is reproduced (S23), the asymmetry value for each recording power step is measured by the recording power target value calculation circuit 25, and the measurement result (asymmetry with respect to the true recording power value for each step) From the value data) (solid line in FIG. 13), an approximate characteristic of the recording power value to the asymmetry value is obtained by the least square method or the like (dotted line in FIG. 13) (S24). Since the test recording has just been completed in one round or almost one round of the disc, this approximate characteristic is obtained by removing the surface runout and the eccentric component. Therefore, by determining the recording power value that achieves the target asymmetry value from the approximate characteristics, the recording power that achieves the target asymmetry value is determined with high accuracy (S25). By setting the obtained recording power value as the target recording power value at the start of the actual recording, the preparation for the actual recording is completed, and the actual recording can be started by the instruction for the actual recording. At the time of the actual recording, the recording power correction according to the surface deflection and the eccentric component described in the first and second embodiments can be performed.

(Embodiment 4)
In the first to third embodiments, the target asymmetry value is registered in the memory in advance. However, when the target asymmetry value is not registered in the memory in advance or is registered in advance, the target asymmetry value is more accurately recorded. In some cases, for example, it is necessary to obtain the target asymmetry value at the user use stage. An example of a control operation when this is realized in the configurations of the first to third embodiments will be described with reference to FIG. When the optical disk 10 is mounted on the optical disk recording device, the test recording mode is automatically started. That is, the spindle motor 12 is started (S31), and the recording power is changed stepwise to perform test recording (S32). After the test recording, this is reproduced (S33), the asymmetry value for each recording power step is measured by the recording power target value calculation circuit 25, and the approximation characteristic of the recording power value to the asymmetry value is minimized from the measurement result. Calculate by multiplication. Further, the recording power target value calculation circuit 25 measures the number of occurrences of the C1 error for each recording power step from the decoding result of the EFM decoder 24. Assuming that one step period is one subcode frame (= 98 EFM frame), the maximum value of the number of C1 error occurrences in one step is 98. Therefore, for each recording power step, a value obtained by subtracting the number of occurrences of the C1 error from 98 is obtained as the number of times of no C1 error, and the characteristic of the number of times of no C1 error with respect to the asymmetry value is obtained (S34). FIG. 15 shows an example of the asymmetry value-to-C1 error-free frequency characteristic thus obtained. The recording power target value calculation circuit 25 obtains the center of gravity of the asymmetry value axis direction from the obtained asymmetry value versus C1 error-free frequency characteristic. That is, the parameter value SQ of the following expression for evaluating the quality of the recording signal is obtained by multiplying the number NERn of the C1 error-free operation at each recording power by the difference Δβn between the asymmetry value of the recording power in the next step and the sum, thereby obtaining the sum. can get.
SQ = ΣΔβn * NERn
Then, by dividing the SQ value by the total number of NERn times without C1 error at all recording powers, the center of gravity βc in the direction of the asymmetry value axis is obtained by the following equation.
βc = SQ / ΣNERn

  The obtained asymmetry value is a value with which a wide power margin can be obtained, and the value is set as a target asymmetry value (S35). After the target asymmetry value is obtained, the recording power for realizing the target asymmetry value is obtained from the approximate characteristic of the recording power versus the asymmetry value (S36). By setting the obtained recording power value as the target recording power value at the start of the actual recording, the preparation for the actual recording is completed, and the actual recording can be started by the instruction for the actual recording. At the time of the actual recording, the recording power correction according to the surface deflection and the eccentric component described in the first and second embodiments can be performed.

  Note that a jitter characteristic may be used instead of the C1 error characteristic. An example of the control operation in that case will be described with reference to FIG. When the optical disk 10 is mounted on the optical disk recording device, the test recording mode is automatically started. That is, the spindle motor 12 is started (S41), and the recording power is changed stepwise to perform test recording (S42). After the test recording, this is reproduced (S43), the asymmetry value for each recording power step is measured by the recording power target value calculation circuit 25, and the approximation characteristic of the recording power value to the asymmetry value is determined based on the measurement result. Calculate by multiplication. The recording power target value calculation circuit 25 measures the jitter (error in the time axis direction) for each recording power step from the reproduced EFM signal of the test recording, and obtains the jitter for each asymmetry value (S44). FIG. 17A shows an example of the asymmetry value vs. jitter characteristic (approximate characteristic) thus obtained. The obtained asymmetry value versus jitter characteristic is sliced by an appropriate jitter value, and the slice is inverted as shown in FIG. Then, the asymmetry value of the center of gravity of the area surrounded by the inverted characteristics is obtained, and the value is set as the target asymmetry value (S45). When the target asymmetry value is obtained, the recording power for realizing the target asymmetry value is obtained from the approximate characteristic of the recording power versus the asymmetry value (S46). By setting the obtained recording power value as the target recording power value at the start of the actual recording, the preparation for the actual recording is completed, and the actual recording can be started by the instruction for the actual recording. During the actual recording, the recording power correction according to the surface deflection and the eccentric component described in the first and second embodiments can be performed.

  In each of the above embodiments, the case where the present invention is applied to a CD-R / RW drive has been described. However, the present invention is not limited to this and can be applied to a DVD recording drive and other optical disk drives.

FIG. 1 is a block diagram showing an embodiment of an optical disk recording device for carrying out the present invention. FIG. 2 is a circuit diagram illustrating a configuration example of a laser driving circuit 28 in FIG. 1. FIG. 2 is a time chart illustrating sample timings of the sample hold circuits SH1, SH2, and SH3 of FIG. FIG. 7 is a diagram illustrating a change in a recording power command value during test recording. FIG. 6 is a diagram illustrating an example of a recording power value-asymmetry value characteristic obtained based on test recording. FIG. 2 is a diagram illustrating an example of setting a response frequency band of the ALPC1 loop 30, the ALPC2 loop 38, and the ROPC circuit 44 in FIG. FIG. 2 is a waveform diagram showing a periodic fluctuation component due to surface deflection, eccentricity, or the like output from the low-pass filter LPF2 of FIG. 1. 3 is a flowchart illustrating an example of a control operation performed by the optical disc recording device of FIG. 1. FIG. 14 is a block diagram showing another embodiment of the optical disc recording apparatus for carrying out the present invention. FIG. 10 is a diagram illustrating an example of data stored in a circulation memory 54 in FIG. 9. 10 is a flowchart illustrating a control operation example of the optical disc recording device in FIG. 9. 4 is a flowchart illustrating an embodiment of an optical disc recording method according to the present invention. FIG. 13 is a diagram showing an example of a recording power value-asymmetry value characteristic obtained based on test recording by the method of FIG. 12. 4 is a flowchart illustrating an embodiment of an optical disc recording method according to the present invention. FIG. 15 is a diagram illustrating an example of an asymmetry value versus C1 error-free count characteristic obtained by the method of FIG. 14; 4 is a flowchart illustrating an embodiment of an optical disc recording method according to the present invention. FIG. 17 is a diagram illustrating an example of asymmetry value versus jitter characteristics obtained by the method of FIG. 16 and its inversion characteristics.

Explanation of reference numerals

  DESCRIPTION OF SYMBOLS 10 ... Optical disk, 20 ... Light beam, 20a ... Return light, 30 ... ALPC1 loop (recording power control loop), 38 ... ALPC2 loop (non-recording power control loop), 44 ... ROPC circuit (Recording power target value correction means), 50: counter (circumferential position detecting means), 52: control path (light beam output correcting means), 54: circulating memory (memory)

Claims (2)

In an optical disk recording method for recording a light beam by irradiating a light beam on a track of an optical disk by modulating a recording power at which recording is performed and a non-recording power at which recording is not performed according to a recording signal,
Prior to the actual recording, test recording is performed by sequentially changing the recording power for one round of the disc, and after the test recording, the test recording is reproduced, the asymmetry value at each recording power is measured, and the recording power value versus the asymmetry is determined from the measured value. A linear or quadratic approximation characteristic of the value is obtained, a recording power value for realizing a predetermined target value of the asymmetry value is obtained from the obtained linear or quadratic approximation characteristic, and the obtained recording power value is recorded in the actual recording. An optical disc recording method in which actual recording is started by setting the recording power command value at the start. In an optical disk recording method for recording a light beam by irradiating a light beam on a track of an optical disk by modulating a recording power at which recording is performed and a non-recording power at which recording is not performed according to a recording signal,
Prior to the actual recording, test recording is performed by sequentially changing the recording power, and after the test recording, the recording is reproduced to obtain a recording power value-asymmetry value characteristic and an asymmetry value-recording signal quality characteristic. The center of gravity of the characteristic in the asymmetry value direction is determined from the signal quality characteristic, the recording power value for realizing the determined asymmetry value is determined from the recording power value-asymmetry value characteristic, and the determined recording power value is calculated in the actual An optical disk recording method in which actual recording is started by setting the recording power command value at the start of recording.

Images