JPH06243493A - Optical disk device - Google Patents

Abstract

PURPOSE:To provide an optical disk device which surely changes the control contents at the positions of obstacles such as the scratches, the dust, etc., and can attain a stable recording or reproducing operation. CONSTITUTION:An FG 13 outputs the FG pulses 40 for each of timings secured by dividing equally the circumference of an optical disk 10 into eight parts. The pulse 40 is acquired for each block and the stabilizing control is attained for each block. AN obstacle detector means 42 detects the presence or absence of obstacles by the tracking error signal acquired from the output signal of an optical head 3. When an obstacle is detected, an obstacle arrival estimating means 46 estimates the timing when the block including the obstacle arrives again after a single revolution of the disk 10. A stabilizing control means 54 changes the tracking servo loop gain and the recording laser beam power by the estimated timing in order to stabilize the recording and reproducing operations.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc device such as an optical disc recording device and an optical disc reproducing device, and reliably changes the control content at a position where there are obstacles such as scratches and dust that hinder recording and reproducing. In this way, stable recording or reproducing operation can be performed.

[0002]

2. Description of the Related Art In an optical disk recording apparatus, as shown in FIG. 2, when an optical disk 10 has scratches (or stains, black spots, etc.) 9 and obstacles such as dust, the light beam is traced over this. The tracking error signal may suddenly increase. Therefore, the tracking servo system may misunderstand that it is out of tracking and drive the tracking actuator in the opposite direction to cause a needle jump (track jump). Further, in the optical disc recording apparatus, if dust is present on the disc, a shadow is formed during recording, and thus normal pits may not be formed.

In order to solve these problems, the gain of the tracking servo is lowered at the position of scratches or dust to prevent the track jump, or the laser power of the recording laser beam is increased to surely form the pit. It is conceivable to change the control content such as to stabilize the reproduction or recording operation.

[0004]

However, even if the control contents are changed immediately after detecting an obstacle such as a scratch or dust, the section in which the obstacle is present is too short and the effect is sufficient. I can't expect to raise it.

The present invention has been made in view of the above-mentioned points, and it is possible to reliably change the control content at a position where an obstacle such as a scratch or dust exists so that a stable recording or reproducing operation can be performed. The present invention is intended to provide an optical disc recording apparatus that has achieved the above.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a disk rotation detecting means for detecting a rotation amount or a rotation position of an optical disk, an obstacle detecting means for detecting an obstacle existing at a trace position of the optical disk, and the obstacle. Obstacle arrival predicting means for predicting the position or timing at which the obstacle comes afterwards by the detection information of the disk rotation detecting means when the object is detected, and reproducing or recording when the predicted position or timing comes. And a stabilization control means for performing control for stabilizing the operation.

[0007]

According to the present invention, attention is paid to the fact that obstacles such as scratches and dust on the optical disk are usually present over a plurality of tracks at substantially the same circumferential position, and when the obstacle is detected, the obstacle is subsequently detected. Predicts the position or timing at which the data will arrive, and performs control to stabilize the playback or recording operation at that position or timing.Therefore, be sure to check the control content at the position where there are obstacles such as scratches and dust. It can be changed to perform stable recording or reproducing operation.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a CD standard optical disk recording / reproducing apparatus will be described. FIG. 3 shows the overall structure. In response to a command from the system controller 19, the disk servo circuit 16 controls the rotation of the disk motor 12 at a set linear velocity and a constant linear velocity. The motor shaft of the disk motor 12 has an FG (Freque
ncy generator) 13 is directly connected, and a pulse signal (FG output pulse) 40 is generated at every predetermined rotation angle (for example, 1/8 rotation).
Is output and input to the system controller 19.

The focus servo and tracking servo circuit 18 controls the focus and tracking of the laser light 11 emitted from the semiconductor laser in the optical head 3 according to a command from the system controller 19.
Tracking control is performed by detecting the pre-groove formed on the disk 10. The feed servo circuit 17 drives the feed motor 20 according to a command from the system controller 19 to move the optical head 3 in the radial direction of the disk 10.

The input signal to be recorded on the optical disk 10 is
In the case of a digital signal, the data signal is directly input to the data signal forming circuit 22 at a speed corresponding to the recording speed magnification, and in the case of an analog signal, the data signal forming circuit 22 is passed through the A / D converter 24.
Entered in. The data signal forming circuit 22 interleaves the input data to give an error check code, and also gives TOC information and subcode information generated by the TOC and subcode generating circuit 23 to give an EFM.
Modulation is performed to form and output a series of serial data at a transfer rate according to the format of the CD standard and the recording speed magnification.

This data is input to the laser generation circuit 25 through the drive interface 15 after undergoing necessary correction in the data signal correction circuit 26. The laser generation circuit 25 drives the semiconductor laser in the optical head 3 according to the data signal to irradiate the recording surface of the optical disc 10 with laser light to form pits for recording. Laser power is A
It is controlled with high precision by an LPC (Automatic Laser Power Control) circuit. As a result, the optical disc 1 has a CD standard format, a transfer rate and a linear velocity (1.2 to
The data is recorded at 1.4 m / s).

The optical disk 10 recorded as described above
When reproduction is performed by irradiating a reproduction laser beam (having a smaller power than that of the recording laser beam) on the read data, the read data is the signal reproduction processing circuit 30.
It is demodulated by the
The A converter 32 converts the analog signal and outputs the analog signal.

The obstacle detection circuit 42 detects an obstacle existing at the trace position of the optical disk 10 based on the output of the optical head 3 during recording or reproduction of the optical disk 10. When an obstacle is detected, the system controller 19 predicts the next arrival timing of this obstacle based on the FG output pulse, and lowers the tracking servo gain or raises the recording laser beam power at this predicted timing. Or, control is performed so that stable recording and playback continue.

A specific example of the stabilization control by the system controller 19 will be described. FIG. 1 shows the control block. From FG13, for example, FIG.
As shown in, the FG pulse 40 is output at every timing when the circumferential direction of the optical disc 10 is divided into eight equal parts. Here, the interval at which the FG pulse 40 is obtained is one block, and the stabilization control is performed in block units.

The obstacle detecting means 42 (obstacle detecting circuit 42 in FIG. 3) detects the presence or absence of an obstacle based on the output signal of the optical head 3. That is, the tracking error signal is
In general, as shown in FIG. 5A, a spike-like waveform is shown in a section between the entry position and the exit position of the obstacle 9 and therefore, a threshold level is set and the threshold level is exceeded. The section where the spike-like waveform is obtained can be detected as the section of the obstacle 9.
However, if the light beam enters the obstacle 9, the tracking error signal may become unstable and the reliability may be lost. Therefore, in such a case, the HF signal can be used together. That is, since the HF signal has a large amplitude in the section of the obstacle 9 as shown in FIG. 5B, a threshold level is set and at least one of the HF signal and the tracking error signal is set to the respective threshold level. The section exceeding the drive level can be detected as the section of the obstacle 9. If sufficient detection performance can be obtained with the HF signal alone, the HF signal alone can be used for detection. The obstacle detection means 42 outputs an obstacle detection pulse (track-out signal) 44 during the period in which the obstacle 9 is being detected.

The obstacle arrival predicting means 46 predicts the timing when the optical disk 10 makes one rotation and the block in which the obstacle exists next again arrives when the track-out signal 44 is output. The obstacle arrival predicting means 46 is, for example, the system controller 1 shown in FIG.
9 or a counter as an accessory circuit
FG pulse 4 after the track-out signal 44 is output
Start counting the number of pulses of 0, and
It can be configured to output the prediction signal 48 that keeps "1" during the period of one block that has reached the count value (for example, 8 counts) of the rotation.

As shown in FIG. 6, the obstacle arrival predicting means 46 is composed of a shift register 50 having a bit number corresponding to the pulse number of one rotation of the FG pulse 40,
When the track-out signal 44 is output, the track-out signal 44 is taken into the first stage 51 of the shift register 50 by the next FG pulse 40, and sequentially shifted by the FG pulse 40, so that the final stage 5 of the shift register 50 is changed.
It is also possible to output the prediction signal 48 that keeps "1" during the period of one block in which the track-out signal 44 is held at 2.

The stabilization control means 54 receives the prediction signal 48 and performs control for stabilizing the recording and reproducing operations during the period when it is "1". This stabilization control is
When the light beam passes over obstacles such as scratches and dust,
Since the tracking error signal may become unstable as shown in FIG. 5 and cause a track jump, the tracking servo gain is set to the normal case (a) during recording and reproduction, as shown in FIG. 7, for example. In comparison, it is lowered as shown in (b), the high frequency characteristic is lowered as shown in (c), or the tracking error signal is held. Also, when recording, dust creates shadows, which makes it difficult to form normal pits and degrades the recording quality. Pits can be formed. In addition to the above, various kinds of stabilization control for stabilizing the recording and reproducing operations can be performed.

While the obstacle is detected and the arrival prediction and the stabilization control are being performed, the obstacle detecting means 42 is still detecting the obstacle, and the arrival prediction is performed every time the obstacle is newly detected. And stabilization control. Therefore,
If scratches and dust are spread over a plurality of tracks in the same block, stabilization control is performed at the same block position over a plurality of turns until the scratches and dust are completed. If an obstacle is detected in another block while stabilization control is being performed in one block,
Stabilization control is performed in a plurality of blocks.

FIG. 8 shows a control flow of stabilization control with the configuration of FIG. When the obstacle detecting means 42 detects an obstacle (S1), the obstacle arrival predicting means 46 predicts the next arrival timing of the block in which the obstacle exists (S1).
2) When the predicted timing comes, the stabilization control means 54 executes the stabilization control (S3). Even while this stabilization control is being performed, obstacle detection is performed in all blocks including that block, and stabilization control is similarly performed each time an obstacle is detected.

FIG. 9 shows an actual operation example by this stabilization control.
Shown in. Here, it is assumed that the recording or reproducing beam traces on the spiral track and recording and reproducing are performed from the inner peripheral side to the outer peripheral side, and the scratch 9 is T1 of the nth block.
~ It shall exist across the T3 track. At this time, the stabilization control is performed in the shaded section. That is, when the flaw 9 is detected in the nth block while the light beam traces the track T1 above, the optical disc 10 makes one rotation, and stabilization control is performed at the timing when the nth block on the track T2 arrives. Is performed. Since the scratch 9 still exists on the track T2, stabilization control is performed on the next track T3. Similarly track T3
Since the scratch 9 still exists, the stabilization control is performed also in the next track T4. Since there is no scratch 9 on the track T4, the stabilization control is not performed on the next track T5, and the normal control is restored. As described above, it is possible to stabilize the recording and reproducing operations when tracing the period when the obstacle exists.

In FIG. 9, the stabilization control is not performed on the first track T1 in which the scratch 9 exists, but as shown by the dotted line in FIG. 9, when the scratch 9 is detected for the first time on the track T1, the scratch is detected. Although there is a slight delay from the start position of 9, the stabilization control can be performed also on this track T1.

[0023]

[Other Embodiments] In the above-described embodiment, the stabilization control is performed in the entire block in which the obstacle exists, but when one block is large, for example, the laser beam power is increased and recorded in the entire block in which the obstacle exists. Then, there is a possibility that the laser power cannot be increased and the pit becomes too large in a portion where there is no obstacle in the block, and the signal quality is deteriorated. Therefore, in such a case, for example, the position in the block is detected by software in the control microcomputer (system controller 19 in FIG. 3) and the laser power is increased only in the section where there is an obstacle in the block. Can be stabilized.

FIG. 10 shows an example thereof. Figure 1
The same reference numerals are used for the portions common to the embodiment of FIG. The counter 80 in the microcomputer counts a clock having a constant cycle and is reset each time the FG pulse 40 is output. In the obstacle arrival predicting means 46, the block predicting means 82 corresponds to the obstacle arrival predicting means 46 in FIG. 1, and when the track-out signal 44 is output, the optical disk 10 makes one revolution and then this obstacle occurs. This is to predict the timing at which a block containing an object arrives again. The intra-block position prediction means 84 predicts the timing at which an obstacle again arrives within the predicted block. The intra-block position predicting means 84 predicts the count value of the counter 80 at the start position and the end position as the position of the obstacle in the corresponding block of the next track when the track-out signal 44 is output, for example. . In the case of CLV (constant linear velocity) control, the count number of one block changes for each track, but since it does not change much between adjacent tracks, the count value of the previous track can be used as it is as the predicted position of the obstacle. No problem.

The stabilization control means 54 performs the stabilization control in the substantially predicted section of the predicted block. Figure 11
Is a time chart showing the predictive control based on the value of the counter 80. FIG. 12 shows an example of actual control by this predictive control. If you do this,
Stabilization control is performed only in the part with almost obstacles,
It is possible to prevent a portion where stabilization control is unnecessary during recording and reproduction from being widely controlled. When the obstacle exists in a plurality of blocks, this prediction control is performed for each block.

Further, in the above embodiment, the FG is used for detecting the rotation of the optical disk, but an incremental rotary encoder may be used. Further, the rotational position of the optical disk can be detected by detecting the absolute position by an absolute rotary encoder or the like instead of detecting the relative position. An example of such a configuration is shown in FIG. An absolute rotary encoder 70 is directly connected to the motor shaft of the disk motor 12, and a block number indicating the circumferential position traced by the optical head 3 is obtained as absolute position information.

The obstacle detecting means 42 is, for example, the optical head 3.
Error signal and HF obtained from the output signal of
The presence or absence of obstacles is detected by the signal. In the obstacle arrival predicting means 46, the obstacle position detecting means 72 takes in absolute position information 74 when the obstacle is detected by the track-out signal 44. The comparing means 76 compares the absolute position information 74 ′ held in the obstacle position detecting means 72 when the obstacle is detected with the subsequent absolute position information 74, and “1” during the period in which they match each other. Output a prediction signal 48 that lasts. The stabilization control means 54 executes stabilization control while the prediction signal 48 is "1". When the obstacle is no longer detected, the stabilization control in that block will not be performed in the next round. As described above, it is possible to stabilize the recording and reproducing operations when tracing the period when the obstacle exists.

[0028]

[Modification] The arrival of the obstacle position can be predicted by time measurement instead of position detection. That is, CAV
In the case of a (constant number of revolutions) type disc, the time for one revolution of the disc is known, so the time required for one revolution to be detected from obstacle detection should be measured and stabilization control should be performed during the period when the obstacle is present. can do. In the case of a CLV (constant linear velocity) type disc, the rotational velocity at that time can be known from the linear velocity and the position of the optical head in the radial direction of the disc. It is possible to measure the time for one rotation and perform the stabilization control during the period when the obstacle exists.

Further, in the case of the CAV type disc, the arrival prediction can be performed by using the reproducing / recording information such as the sector number which can specify the position in the disc circumferential direction.

Further, in the above embodiment, the stabilization control is performed by dividing it into blocks, but it is also possible to accurately detect the range where the obstacle exists without dividing into blocks and perform the stabilization control in that period. it can.

Further, in the above embodiment, both the start position and the end position of the stabilization control are predictive control, but the end position is not dependent on the predictive control, but is ended at the timing when the end of the obstacle is actually detected. You can also In this case, for example, in the embodiment of FIG. 10, the stabilization control unit 54 uses the start position information of the obstacle predicted by the obstacle arrival prediction unit 46 as the start position of the stabilization control, and the end position is a dotted line. As shown, the stabilization control is performed using the information on the ending position of the track-out signal 44. An actual control example in such a case is shown in FIG. It should be noted that the control for performing the end position control without using the predictive control in this way is not limited to the embodiment of FIG. 10, but can be performed in the embodiments of FIGS. 1 and 13 and the like.

Further, in the above embodiment, the case where the tracking error signal or the HF signal is used for the obstacle detection has been described, but the present invention is not limited to this, and if there is another signal for which the presence / absence of the obstacle is obtained, that Can also be used.

Further, the present invention can be applied to an optical disk device which handles optical disks other than the CD standard, magneto-optical disks and the like.

[0034]

As described above, according to the present invention, attention is paid to the fact that obstacles such as scratches and dust on an optical disk are usually present over a plurality of tracks at substantially the same circumferential position. When it is detected, the position or timing at which this obstacle arrives is predicted, and control is performed to stabilize the playback or recording operation at that position or timing, so there are obstacles such as scratches and dust. It is possible to reliably change the control content at the position to be performed and to perform stable recording or reproducing operation.

[Brief description of drawings]

FIG. 1 is a control block diagram showing an embodiment of the present invention.

FIG. 2 is an enlarged view showing a state where a scratch is generated on the optical disc.

FIG. 3 is a block diagram showing an overall configuration of an optical disc device to which the present invention is applied.

FIG. 4 is a diagram showing a divided state of an optical disc surface which is divided into blocks by the FG of FIG.

5 is a waveform diagram showing an obstacle detecting operation by the obstacle detecting means 42 of FIG.

FIG. 6 is a diagram showing a specific example of the obstacle arrival prediction means 46 in FIG.

FIG. 7 is a diagram showing a change in tracking servo gain due to stabilization control by the stabilization control means 54 in FIG.

FIG. 8 is a control flow diagram of a stabilizing operation according to the configuration of FIG.

9 is a diagram showing an example of a stabilizing operation according to the configuration of FIG.

FIG. 10 is a control block diagram showing another embodiment of the present invention.

11 is a time chart showing an example of stabilization control according to the embodiment of FIG.

12 is a diagram showing an example of a stabilizing operation by the stabilizing control of FIG.

FIG. 13 is a control flow chart showing still another embodiment of the present invention.

FIG. 14 is a diagram showing an example of a stabilizing operation in the case where the end of the stabilization control is performed based on the detection of the actual end of the obstacle, not the predictive control, in the embodiment of FIG.

[Explanation of symbols]

 9 scratches (obstacle) 10 optical disk 13 FG (disk rotation detection means) 42 obstacle detection means 46 obstacle arrival prediction means 54 stabilization control means

Claims (1)

[Claims] 1. A disk rotation detecting means for detecting a rotation amount or a rotation position of an optical disk, an obstacle detecting means for detecting an obstacle existing at a trace position of the optical disk, and the disk when the obstacle is detected. Obstacle arrival prediction means for predicting the position or timing at which the obstacle comes thereafter based on the detection information of the rotation detection means, and control for stabilizing the reproduction or recording operation when the predicted position or timing comes. An optical disk device comprising a stabilizing control means for performing the operation.