JP2006344259A - Track jump control method for optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a track jump control method suitable for an optical disk drive configured to reproduce the signals recorded by an optical pickup on an optical disk. <P>SOLUTION: This method makes track jumping to the target track on an optical disk by turning off the tracking servo circuit. When the irradiating position of the laser beam reaches the target track, it turns on the tracking servo circuit and increases its gain larger than normal. Then, it checks whether or not the level of the tracking error signals is within the predetermined limit, and changes the gain to the normal one when it is within the predetermined limit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a track jump control method for an optical disc apparatus configured to read a signal recorded from an inner circumference side to an outer circumference side of an optical disc with an optical pickup.

  2. Description of the Related Art Optical disc apparatuses that perform a reproduction operation by reading a signal with an optical pickup from an optical disc in which information data such as music is recorded by a digital signal are widespread. As representative examples of such optical disc apparatuses, CDs and DVDs are used. There is an optical disk device that uses an optical disk called.

  Such an optical disc apparatus is configured to cause a laser beam to follow a track provided on a signal surface of an optical disc by displacing an objective lens incorporated in an optical pickup, and the control operation is performed as a tracking operation. This is called a control action. In addition, the optical disc apparatus supplies a driving signal called a kick pulse to a tracking coil that displaces the objective lens during a pause operation, a fast-forward operation, a rewind operation, and a search operation for searching for a desired position. In general, it has a function capable of performing a track jump operation for displacing light to another track.

When the laser beam is displaced to the target track position by the track jump operation, a technology has been developed to quickly perform the search operation by changing the gain of the tracking servo circuit when the laser beam is displaced to the target track position. (For example, refer to Patent Document 1).
Japanese Patent Application Laid-Open No. 2004-241065

  The operation of displacing the laser beam to the target track position by the track jump operation accompanying the search operation is performed with the tracking servo circuit turned off, and the irradiation position of the laser beam has reached the target position by counting the number of tracks. When it is determined that the tracking servo circuit is turned on, the tracking servo circuit is turned on.

  At this time, a tracking control operation is performed to capture the target track. In order to perform such a capturing operation powerfully, the servo gain of the tracking servo circuit is increased from the steady gain. The tracking servo circuit gain is increased for a set time and then returned to a steady gain.

  The rotation driving operation of the optical disk in the optical disk apparatus is performed by rotating the turntable on which the optical disk is mounted by a spindle motor. Swelling will occur. When the rotation characteristic of the optical disk has a wave, there is a characteristic that the level of the tracking error signal changes according to the magnitude of the wave.

When the level of the tracking error signal at the time when the gain of the tracking servo circuit is increased from the steady gain to the steady gain is high, the tracking control operation cannot be performed normally and a phenomenon of track skip occurs. When such a track jump occurs, there is a problem that the jump operation to the target track cannot be performed quickly.

  The present invention is intended to provide a track jump control method capable of solving such a problem.

  According to the present invention, the track jump operation to the target track on the optical disk is performed with the tracking servo circuit turned off, and the tracking servo circuit is turned on when the irradiation position of the laser beam reaches the target track. At the same time, the gain of the tracking servo circuit is increased from the steady gain to detect whether or not the level of the tracking error signal is within a predetermined range, and when it is within the predetermined range, the gain is changed to the steady gain. .

  Further, the present invention is configured such that the level detection operation of the tracking error signal is performed every predetermined time shorter than a period in which the level of the tracking error signal is within a predetermined range.

  The present invention is configured such that the average value of the tracking error signal level detected a predetermined number of times every predetermined time is set to a detection level for performing a determination operation as to whether or not it is within a predetermined range.

  Further, the present invention is configured to change the interval for performing the level detection operation of the tracking error signal in accordance with the rotation speed of the optical disc.

  The present invention is configured to change the gain of the tracking servo circuit to a steady gain when the level of the tracking error signal detected by the level detection operation of the tracking error signal does not fall within a predetermined range within the set time. Yes.

  Further, according to the present invention, if the track acquired by changing the gain of the tracking servo circuit to a steady gain is not the target track when the level of the tracking error signal does not fall within the predetermined range within the set time, the track is returned to the target track again. The track jump operation is configured to be performed.

  In the present invention, the time for detecting the tracking error signal level is set to be the time required for one or half rotation of the optical disc.

  Further, the present invention is configured to change the gain amount that is increased from the steady gain of the tracking servo circuit in accordance with the rotation speed of the optical disk.

  According to the present invention, the track jump operation to the target track on the optical disk is performed with the tracking servo circuit turned off, and the tracking servo circuit is turned on when the irradiation position of the laser beam reaches the target track. And the gain of the tracking servo circuit is increased from the steady gain, and it is detected whether the level of the tracking error signal is within the predetermined range, and when it is within the predetermined range, the gain is changed to the steady gain. That is, since the gain is restored when the influence of the eccentricity or the like on the rotation of the optical disk is small, the target track capturing operation can be performed accurately.

  In the present invention, the level detection operation of the tracking error signal is performed every predetermined time shorter than the period in which the level of the tracking error signal is within the predetermined range, so that the time point when the level of the tracking error signal falls within the predetermined range. Can be reliably performed.

  In the present invention, since the average value of the tracking error signal level detected a predetermined number of times every predetermined time is set to a detection level for determining whether or not it is within a predetermined range, the detection operation that suppresses the influence of noise Can be done.

  In the present invention, since the interval for performing the level detection operation of the tracking error signal is changed in accordance with the rotation speed of the optical disk, a stable track jump operation can be performed even if the rotation speed of the optical disk is changed. I can do it.

  In the present invention, when the level of the tracking error signal detected by the level detection operation of the tracking error signal does not fall within the predetermined range within the set time, the gain of the tracking servo circuit is changed to a steady gain. It is possible to return to the state of performing the tracking control operation after the track jump.

  Further, according to the present invention, if the track acquired by changing the gain of the tracking servo circuit to a steady gain is not the target track when the level of the tracking error signal does not fall within the predetermined range within the set time, the track is returned to the target track again. Since the track jump operation is performed, the track jump operation to the target track can be performed.

  In the present invention, since the time for performing the tracking error signal level detection operation is set to be the time required for one or half rotation of the optical disc, the track captured by the tracking control operation by the tracking servo circuit is recorded. The track can be close to the target track.

  Further, according to the present invention, the gain amount that is increased from the steady gain of the tracking servo circuit is changed in accordance with the rotation speed of the optical disk, so that even if the rotation speed of the optical disk is changed, the track jump operation suitable for each speed is performed. Can be done.

  The present invention controls a track jump operation by detecting a level change of a tracking error signal obtained from an optical pickup.

  FIG. 1 is a flowchart showing a track jump control method of the present invention, FIG. 2 is a block circuit diagram showing an embodiment of an optical disk apparatus according to the present invention, and FIG. 3 is a signal waveform diagram for explaining the operation of the present invention. .

  In FIG. 2, reference numeral 1 denotes an optical disk that is rotationally driven by a spindle motor (not shown), and 2 denotes a laser diode (not shown) that irradiates the optical disk 1 with laser light and is reflected from the signal surface of the optical disk 1. And a tracking coil 5 for displacing the objective lens 4 in the tracking direction, and a rotation operation of the pickup feeding motor 6 is provided. The main body of the optical pickup 2 is configured to be displaced in the radial direction of the optical disc 1.

In such an optical pickup 2, the tracking error detection operation is performed, for example, by a known method called a three-beam method. Reference numeral 7 denotes a tracking error signal generation circuit that generates a tracking error signal as shown in FIG. 3 based on a signal obtained from a photodetector 3 incorporated in the optical pickup 2, and 8 denotes the tracking error signal generation circuit 7. A tracking equalizer circuit 9 that corrects the frequency of the error signal output from the tracking equalizer 9 receives a tracking control signal input through the tracking equalizer circuit 8 and supplies a driving signal corresponding to the tracking control signal to the tracking coil 5. It is a coil drive circuit.

  In such a circuit, the tracking error signal generation circuit 7, the tracking equalizer circuit 8, and the tracking coil drive circuit 9 constitute a circuit for performing a tracking control operation for causing the laser light to follow the signal track, that is, a tracking servo circuit. Thus, the control operation for causing the laser beam to follow the signal track provided on the optical disc 1 is performed.

  A system control circuit 10 is provided to control the operation of the optical disk apparatus, and is constituted by a microcomputer. Reference numeral 11 denotes a pickup feed motor drive circuit that supplies a drive signal to the pickup feed motor 6. The operation of the pickup feed motor drive circuit is controlled by the system control circuit 10, and the rotation drive is performed based on a signal obtained from the tracking coil drive circuit 9. The operation is configured to be controlled.

  A kick pulse generation circuit 12 outputs a kick pulse to the tracking coil drive circuit 9 when performing a track jump operation. The kick pulse generation operation is controlled by the system control circuit 10. . Reference numeral 13 denotes a jump operation setting circuit whose operation is controlled by the system control circuit 10 and which controls the kick pulse generation operation of the kick pulse generation circuit 12 and the operation of the pickup feed motor drive circuit 11.

  Reference numeral 14 denotes a sampling circuit to which a tracking error signal generated and output from the tracking error signal generation circuit 7 is input. Based on the signal output from the system control circuit 10, a sampling operation of the tracking error signal is performed at a predetermined interval. Is configured to do. An AD converter circuit 15 converts the level of the tracking error signal, which is an analog signal sampled by the sampling circuit 14, into a digital signal. The converted digital signal is input to the system control circuit 10. ing.

  In such a configuration, on / off of the tracking servo circuit can be controlled by controlling operation / non-operation of the tracking equalizer circuit 8 constituting the tracking servo circuit by the system control circuit 10 and is incorporated in the tracking equalizer circuit 8. The gain of the tracking servo circuit can be changed by controlling the gain of the amplifier circuit (not shown) by the system control circuit 10.

  As described above, the optical disk apparatus according to the present invention is configured. Next, the operation will be described. The reading operation of the signal recorded on the optical disc 1 includes a focus control operation for rotating the optical disc 1 at a desired rotational speed and focusing the laser beam on the signal surface, and a tracking control operation for causing the laser beam to follow the signal track. It is performed in the state where has been performed.

  In this embodiment, a signal obtained from the photodetector 3 incorporated in the optical pickup 2 is input to the tracking error signal generation circuit 7, and the tracking error signal generation circuit 7 is based on the input signal. 3 is generated. The tracking error signal output from the tracking error signal generation circuit 7 is input to the tracking equalizer circuit 8 to be frequency corrected, amplified by the amplifier circuit, and then input to the tracking coil drive circuit 9.

  When the tracking error signal whose frequency has been corrected by the tracking equalizer circuit 8 is input to the tracking coil drive circuit 9, a tracking drive signal is supplied from the tracking coil drive circuit 9 to the tracking coil 5. Such a signal acts to bias the objective lens 4 in the direction of decreasing the level of the tracking error signal. As a result of controlling the position of the objective lens by such a signal, an operation of causing the laser beam to follow the signal track, that is, a tracking control operation is performed.

  In this way, the tracking control operation for causing the laser beam to follow the signal track is performed. The gain of the tracking servo circuit in such a case is the normal operation, that is, when the signal recorded on the optical disc 1 is reproduced. The required steady gain is set.

  As described above, the tracking control operation by the tracking servo circuit is performed. However, when the deflection operation of the objective lens 4 is performed to an allowable range, the further deflection operation of the objective lens 4 cannot be performed. In this state, a drive signal is supplied from the pickup feed motor drive circuit 11 to the pickup feed motor 6. That is, the objective lens 4 can be returned from the biased position to the neutral position by moving the main body of the optical pickup 2 by the rotational operation of the pickup feed motor 6. The movement of the optical pickup 2 main body by the pickup feeding motor 6 is performed every time the reading position on the optical disk 1 is moved. Since such an operation is well known, its description is omitted.

  Although the tracking control operation is performed as described above, the search operation for moving the laser beam irradiated from the optical pickup 2 to the target track at the target position on the optical disc 1 will be described next.

  Such a search operation is performed by a biasing operation of the objective lens 4 by applying a kick pulse signal to the tracking coil 5 and a moving operation of the optical pickup 2 main body by the pickup feeding motor 6. That is, when the position of the target track is close to the current position, the search operation to the target track is performed only by the biasing operation of the objective lens 4, and when the position of the target track is far from the current position, the pickup feed is performed. This is performed by the movement operation of the optical pickup 2 body by the motor 6 and the deflection operation of the objective lens 4.

  The moving operation of the laser beam to the target track is performed by the biasing operation of the objective lens 4 and the moving operation of the optical pickup 2 main body by the pickup feeding motor 6. This is done by counting the number of tracks by detecting the signal obtained when crossing a track. Since such an operation is well known, its description is omitted.

  The track jump operation for the search operation described above causes the system control circuit 10 to output a control signal for generating a kick pulse signal to the kick pulse generation circuit 12 and performs a control operation for the jump operation setting circuit 13. Is done by.

  When the system control circuit 10 outputs a control signal to the kick pulse generation circuit 12 in order to perform a track jump operation, the kick pulse generation circuit 12 outputs a kick pulse. The kick pulse output from the kick pulse generation circuit 12 is a plus level signal when performing an operation of jumping the laser beam in the outer circumferential direction of the optical disc 1, and jumps the laser beam in the inner circumferential direction of the optical disc 1. When the operation is performed, the signal becomes a negative level signal.

  When the optical pickup 2 main body needs to be moved, a control signal is output from the jump operation setting circuit 13 to the pickup feed motor drive circuit 11, and a drive signal corresponding to the control signal is sent to the pickup feed. It is supplied from the motor drive circuit 11 to the pickup feeding motor 6 and can perform a moving operation for the search operation of the optical pickup 2 main body.

  Next, the track jump control method of the present invention will be described with reference to the flowchart shown in FIG. 1 and the signal waveform diagram shown in FIG.

  When the search operation to the target track is started, the control operation for the search operation by the system control circuit 10 is started (step A). When such an operation is started, a control operation for the tracking equalizer circuit 8 by the system control circuit 10 is performed, and an operation for turning off the tracking servo circuit is performed (step B).

  After such an operation is performed, a control operation is performed on the kick pulse generation circuit 12 and the jump operation setting circuit 13 to start the track jump operation (step C). Such a track jump operation is an operation corresponding to the distance to the target track as described above, that is, an operation based only on the deflection operation of the objective lens 4 by the kick pulse output from the kick pulse generation circuit 12, or a deflection operation of the objective lens 4. The optical pickup 2 main body is moved by the rotation of the pickup feed motor 6, and when such an operation is being performed, an operation for counting the number of tracks traversed is performed.

  By performing an operation of counting the number of tracks traversed, an operation of detecting whether or not the laser beam has reached the position of the target track is performed (step D). When it is determined in step D that the laser beam has reached the position of the target track, the biasing operation with respect to the objective lens 4 and the driving operation with respect to the pickup feeding motor 6 are canceled and the tracking equalizer circuit 8 by the system control circuit 10 is applied. Control action is performed.

  The control operation for the tracking equalizer circuit 8 by the system control circuit 10 is an operation for turning on the tracking servo circuit that has been turned off and increasing the gain of the tracking servo circuit (step E). When such an operation is performed, a tracking error signal generation operation is performed by the tracking error signal generation circuit 7, and a tracking error signal having a waveform shown in FIG. 3 is output.

  In FIG. 3, a period in which the level of the tracking error signal is larger than the reference level VR indicates a state in which the track of the optical disk 1 is shifted to the outer peripheral side due to the eccentricity of the optical disk 1, and conversely, a period smaller than the reference level VR is The state where the track of the optical disc 1 is shifted to the inner peripheral side is shown. Also, in the figure, the values of + α and −α representing the level of the tracking error signal are values set for performing a control operation to be described later according to the level of the tracking error signal.

  When the operation of Step E is performed, a state in which a tracking control operation is performed is entered. In such a state, an operation for performing a level detection operation of the tracking error signal is performed every predetermined time (Step F). Such a tracking error signal level detection operation is performed by a sampling operation by the sampling circuit 14, and the sampled level value is converted into a digital signal by the AD converter circuit 15 and input to the system control circuit 15. Therefore, the system control circuit 10 can recognize the level of the tracking error signal detected.

The tracking error signal level detection operation is performed for recognizing whether or not the detection value L, which is the level of the tracking error signal, is VR−α <L <VR + α. In FIG. The sampling period is set so that the sampling operation is performed.

  In the present embodiment, for example, when the time required for one rotation of the optical disk 1 is 150 ms, the level detection operation of the tracking error signal is performed at intervals of 2 ms, and the average of the tracking error signal level obtained by several sampling operations is obtained. A value is calculated and set to a detection value L.

  An operation for determining whether or not the detection value L obtained in this way is within a predetermined level is performed (step G). If it is determined in step G that it is not within the predetermined level, that is, if it is determined that the time point at which the detection operation is performed is in the period indicated by T1 or T2 in FIG. A determination operation is performed to determine whether or not a set time has elapsed since the error signal level detection operation was started (step H). Such a set time is set based on the time required for one rotation of the optical disc 1, but as is apparent from FIG. 3, the detected value L which is the level of the tracking error signal during one rotation is VR−α <L. <There are two periods in which VR + α is entered. If the time required for one rotation is 150 ms, the half rotation may be set from 75 ms to 80 ms.

  If the set time has not elapsed in step H, the process returns to step F to perform the tracking error signal level detection operation. As described above, the level detection operation of the tracking error signal is performed. If it is determined in step G that the detection value L is within the predetermined level, that is, if it is determined that it is in the period indicated by T3, tracking is performed. A control operation for reducing the gain of the servo circuit to a steady state is performed by the system control circuit 10 (step I).

  By performing such an operation, a normal tracking control operation is performed by the tracking servo circuit, and the track can be irradiated with a laser beam following the track. In this case, since the gain of the tracking servo circuit is reduced to a steady gain when the level of the tracking error signal is small, that is, when the waviness due to the eccentricity of the optical disc 1 is small, track skipping does not occur. The target track can be accurately captured.

  If it is determined in step H that the set time has elapsed since the tracking error signal detection operation was started, the operation of step I, that is, the control operation for reducing the gain of the tracking servo circuit to a steady state is performed by the system control circuit 10. Done. Even in such a case, a normal tracking control operation by the tracking servo circuit is performed, and a control operation for following and irradiating the track with the laser beam is performed. In this case, the time point when the level of the tracking error signal is large, that is, the optical disc 1 Since the operation of lowering the gain of the tracking servo circuit to the steady gain is performed at the time when the undulation due to the eccentricity is large, the possibility of the occurrence of the track jump increases.

  When the tracking control operation by such a tracking servo circuit is performed and the captured track is not the target track, a search operation from the position to the target track is performed. In such a case, the target track is close. Therefore, the search operation can be performed again only by the biasing operation of the objective lens 4. Therefore, the target track search operation can be performed.

In this description, the detection value L used in the level determination operation of the tracking error signal is a value obtained by averaging the levels obtained by several sampling operations, but is determined by one measurement value. You can also do so. If the interval for performing the level detection operation is changed in accordance with the rotation speed of the optical disc 1, the level detection operation of the tracking error signal suitable for the rotation speed of the optical disc 1 can be performed.

  In this description, the set time for performing the level detection operation of the tracking error signal is set to the time required for the optical disk 1 to make a half rotation, but may be set to the time required for one rotation.

  If the amount of gain increased from the steady gain of the tracking servo circuit is changed in accordance with the rotational speed of the optical disc 1, the level of the tracking error signal changes due to the change in the rotational characteristics accompanying the difference in rotational speed. In addition, the target track capturing operation suitable for each state can be accurately performed.

It is a flowchart which shows the track jump control method of this invention. 1 is a block circuit diagram showing an embodiment of an optical disc apparatus according to the present invention. It is a signal waveform diagram for demonstrating operation | movement of this invention.

Explanation of symbols

1 Optical disc
2 Optical pickup
3 Photodetector
4 Objective lens
5 Tracking coil
7 Tracking error signal generation circuit
8 Tracking equalizer circuit
9 Tracking coil drive circuit 10 System control circuit 11 Pickup feed motor drive circuit 12 Kick pulse generation circuit 14 Sampling circuit

Claims (9)

A track jump control method of an optical disc apparatus configured to read a signal recorded from the inner circumference side to the outer circumference side of the optical disc by an optical pickup, and tracking servo to track a target track on the optical disc. When the circuit is turned off and the laser beam irradiation position reaches the target track, the tracking servo circuit is turned on and the gain of the tracking servo circuit is increased from the steady gain. A track jump control method for an optical disk apparatus, wherein the gain is changed to a steady gain when it is within a predetermined range. 2. The track jump control method according to claim 1, wherein the tracking error signal level detection operation is performed every predetermined time shorter than a period in which the tracking error signal level is within a predetermined range. 3. The track jump control method according to claim 2, wherein an average value of the levels detected a predetermined number of times for each predetermined time is set as a detection level for performing an operation of determining whether or not the level is within a predetermined range. 3. The track jump control method according to claim 2, wherein the interval for performing the level detection operation is changed in accordance with the rotational speed of the optical disk. 2. The gain of the tracking servo circuit is changed to a steady gain when the level of the tracking error signal detected by the level detection operation of the tracking error signal does not fall within a predetermined range within a set time. The track jump control method described in 1. 6. The track jump control method according to claim 5, wherein when the track captured by the tracking control operation is not the target track, the track jump operation to the target track is performed again. 6. The track jump control method according to claim 5, wherein the set time is set to a time required for half rotation of the optical disc. 6. The track jump control method according to claim 5, wherein the set time is set to a time required for one rotation of the optical disk. 2. The track jump control method according to claim 1, wherein the gain amount to be increased from the steady gain is changed in accordance with the rotation speed of the optical disk.

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