JP2006134471A - Track jump control method of optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a track jump control method of an optical disk device which reads a signal recorded on a disk by an optical beam radiated from an optical pickup. <P>SOLUTION: In the track jump control method, a tracking error signal generation circuit 7 is set for generating a tracking error signal based on a signal acquired from a photo detector 3 incorporated in the optical pickup 2, and sampling of a tracking error signal generated by a tracking error signal generation circuit 7 is performed for every predetermined time by a sampling circuit 13, and a kick pulse is generated from a kick pulse generation circuit 12 which supplies a kick pulse to a tracking coil 5 which displaces the objective lens 4 when a sampling value of the tracking error signal acquired by sampling changes from small to large, and the sampling value is in the prescribed range. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  2. Description of the Related Art An optical disk device that performs a reproduction operation by reading a signal with an optical pickup from a disk on which information data such as music is recorded by a digital signal is widely used, and a disk called a CD is a typical example of such an optical disk device. There are optical disk devices that use

  Such an optical disc apparatus is configured to cause a light beam to follow a track provided on a signal surface of the disc by displacing an objective lens incorporated in the optical pickup, and the control operation is performed as a tracking operation. This is called a control action. In addition, the optical disk apparatus supplies a drive 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. Generally, a function capable of performing a track jump operation for displacing the beam to another track is provided.

  In addition, the rotational drive operation of the disk in the optical disk apparatus is performed by rotating the turntable on which the disk is placed by a spindle motor. Swelling will occur in the rotation.

If the track jump operation is performed in a state in which the rotational characteristics are swelled due to the eccentricity of the disk, the number of tracks actually jumped differs even with the same kick pulse. A technique for solving such a problem has been developed (see, for example, Patent Document 1).
JP-A-4-60974

  Since the technique of Patent Document 1 is configured to generate a kick pulse with reference to the zero cross point of the tracking error signal, there is a problem that a stable track jump operation cannot be performed against the eccentricity of the disk. .

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

  The present invention provides a tracking error signal generation circuit that generates a tracking error signal based on a signal obtained from a photodetector incorporated in an optical pickup, and the tracking error signal generated by the tracking error signal generation circuit To the tracking coil that displaces the objective lens when the sampling value of the tracking error signal obtained by sampling changes from small to large and the sampling value is within the predetermined range. A kick pulse is generated from a kick pulse generation circuit that supplies the kick pulse.

  Further, the present invention is configured to set a predetermined range set for generating a kick pulse around a reference value for detecting the level of the tracking error signal.

  In the present invention, a kick pulse including an acceleration pulse for displacing the objective lens and a deceleration pulse for stopping the displacement of the objective lens is generated from a kick pulse generation circuit.

  The present invention is configured to change the magnitudes of the acceleration pulse and the deceleration pulse in accordance with the direction in which the objective lens is displaced.

  The present invention provides a tracking error signal generation circuit that generates a tracking error signal based on a signal obtained from a photodetector incorporated in an optical pickup, and the tracking error signal generated by the tracking error signal generation circuit To the tracking coil that displaces the objective lens when the sampling value of the tracking error signal obtained by sampling changes from small to large and the sampling value is within the predetermined range. Since the kick pulse is generated from the kick pulse generation circuit for supplying the kick pulse, the timing for performing the track jump operation is constant, and a stable track jump operation can be performed.

  Further, according to the present invention, the predetermined range set for generating the kick pulse is set centering on the reference value for detecting the level of the tracking error signal, so that the track jump timing is affected by the eccentricity of the disc. Can be minimized, and a stable track jump operation can be performed.

  In the present invention, since the magnitudes of the acceleration pulse and the deceleration pulse are changed in accordance with the direction in which the objective lens is displaced, an accurate track jump operation can be performed.

  The present invention controls timing for generating a kick pulse for performing a track jump operation by detecting a level change of a tracking error signal obtained from an optical pickup.

  FIG. 1 is a block circuit diagram showing an embodiment of an optical disk apparatus according to the present invention, and FIGS. 2 and 3 are signal waveform diagrams for explaining the operation of the present invention.

  In FIG. 1, reference numeral 1 denotes a disk that is rotationally driven by a spindle motor (not shown), and 2 denotes a laser diode (not shown) that irradiates the disk 1 with a light beam and is reflected from the signal surface of the disk 1. Is an optical pickup in which a light detector 3 for receiving the light beam is incorporated, a tracking coil 5 for displacing the objective lens 4 is provided, and the disk 1 is rotated by the pickup driving motor 6. It is configured to be displaced in the radial direction.

In such an optical pickup 2, the tracking error detection operation is performed 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. 2 based on a signal obtained from the photodetector 3 incorporated in the optical pickup 2, and 8 denotes the tracking error signal generation circuit 7. Tracking equalizer that corrects the frequency of the error signal output from
Reference numeral 9 denotes a tracking coil driving circuit that receives a tracking control signal input through the tracking equalizer 8 and supplies a driving signal corresponding to the signal to the tracking coil 5.

  In such a circuit, a circuit for controlling the tracking operation by the tracking error signal generation circuit 7, the tracking equalizer 8, and the tracking coil drive circuit 9, that is, a tracking servo circuit is configured, and is provided on the disk 1 by a known operation. A control operation for causing the light beam to follow the signal track is performed.

  A system control circuit 10 is provided for controlling the operation of the disk device, 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, and the operation is controlled by the system control circuit 10.

  Reference numeral 12 denotes a kick pulse generating circuit for outputting a kick pulse to the tracking coil drive circuit 9 when performing a track jump operation, and the operation is controlled by the system control circuit 10.

  Reference numeral 13 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 14 converts the level of the tracking error signal, which is an analog signal sampled by the sampling circuit 13, into a digital signal. The converted digital signal is input to the system control circuit 10. Yes.

  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 disc 1 at a desired rotational speed and focusing the light beam on the signal surface, and a tracking control operation for causing the light 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. 2 is generated. The tracking error signal output from the tracking error signal generation circuit 7 is input to the tracking equalizer 8 and frequency-corrected, and then input to the tracking coil drive circuit 9.

  When the tracking error signal frequency-corrected by the tracking equalizer 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. The signal acts to bias the objective lens 4 in a direction that reduces the tracking error signal. As a result of the position of the objective lens being controlled by such a signal, an operation in which the light beam follows the signal track, that is, a tracking control operation is performed.

As described above, the tracking control operation is performed. However, if 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. A drive signal is supplied from the 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 disk 1 is moved. Since such an operation is well known, its description is omitted.

  The tracking control operation is performed as described above. Next, the track jump operation will be described. The track jump operation is performed by outputting a control signal for generating a kick pulse signal from the system control circuit 10 to the kick pulse generation circuit 12.

  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 the light beam is jumped in the outer circumferential direction of the disk 1, and when the light beam is jumped in the inner circumferential direction of the disk 1. Becomes a minus level signal.

  When the optical beam is caused to track jump to the outer peripheral side of the disk 1, the kick pulse generation circuit 12 first outputs a positive level acceleration pulse for displacing the objective lens 4, and then applies a brake to the displacement for a negative level deceleration. It is comprised so that a pulse may be output. When the optical beam is caused to track jump to the inner peripheral side of the disk 1, the kick pulse generating circuit 12 first outputs a negative level acceleration pulse for displacing the objective lens 4 and then brakes the displacement for a positive level. It is configured to output a deceleration pulse. When a track jump operation is performed, a kick pulse formed from an acceleration pulse and a deceleration pulse is generally used, and the description thereof is omitted.

  The kick pulse generation circuit 12 generates the above-described kick pulse based on the control signal output from the system control circuit 10, and the pulse level and pulse width are set in accordance with the number of tracks to be jumped. It will be. Such a pulse width of the kick pulse is set by a control operation of the system control circuit 10 based on table data stored in advance in a memory circuit (not shown).

  As described above, the track jump operation in this embodiment is performed. Next, the track jump method of the present invention will be described. FIG. 2 shows the level change of the tracking error signal output from the tracking error signal generation circuit 7. In the figure, a period in which the level of the tracking error signal is higher than the reference level VR indicates a state in which the track of the disk 1 is shifted to the outer peripheral side due to the eccentricity of the disk. 1 shows a state in which one track is displaced toward the inner periphery.

  In FIG. 2, the values of + α and −α representing the level of the tracking error signal are values set up and down around the reference value VR in order to divide one cycle of the tracking error signal into four. The period is divided into four periods T1, T2, T3, and T4.

The period T1 is a period in which the deviation of the signal track due to eccentricity is small because the level of the tracking error signal is within the reference value VR ± α, and the light beam is displaced to the outer peripheral side. Also, the period T2 is a period in which the level of the tracking error signal is larger than the reference value VR + α, so that the deviation of the signal track to the outer peripheral side due to eccentricity is large, and the light beam is displaced toward the outer peripheral side and the inner peripheral side. Means a period. The period T3 is a period in which the level of the tracking error signal is within the reference value VR ± α, so that there is little deviation of the signal track due to eccentricity, and the light beam is displaced to the inner circumference side. ing. Furthermore, since the level of the tracking error signal is smaller than the reference value VR-α, the period T4 is a period in which the deviation of the signal track to the inner peripheral side due to eccentricity is large, and the light beam moves to the inner peripheral side and the outer peripheral side. And means the period of displacement.

  When a tracking error signal as shown in FIG. 2 is output from the tracking error signal generation circuit 7, a sampling operation by the sampling circuit 13 to which such tracking error signal is input is performed. The sampling operation by the sampling circuit 13 is performed based on the control operation by the system control circuit 10, and the sampling timing is set so as to be performed at a cycle in which the sampling operation can be performed twice during the period T1. Will be.

  That is, the level change of the tracking error signal generated with the eccentricity of the disk 1 appears corresponding to the rotation period of the disk 1, and therefore the sampling period may be set based on the rotation period.

  With this setting, the sampling circuit 13 performs a sampling operation according to the rotational speed of the disk 1. The level of the tracking error signal, which is an analog signal obtained by sampling, is converted to a digital signal by the AD converter 14. And is input to the system control circuit 10.

  When a level value of a tracking error signal, which is a sampling value converted into a digital signal by the AD converter 14, is input to the system control circuit 10, the range of the level value by the system control circuit 10 and the level value An operation for determining how the change has occurred is performed. Next, such an operation for determination will be described.

  Determining whether or not VR−α <L1 <VR + α and VR−α <L2 <VR + α, where L1 is the level value detected by sampling first and L2 is the level value detected next Is done. When it is determined that the values of L1 and L2 are both between VR−α and VR + α by such determination operation, the level of the tracking error signal is determined to be in either the period T1 or T3.

  When such a determination operation is performed, a determination operation for determining whether or not L1 <L2 is performed next. When it is determined that L1 <L2 by such determination operation, the level of the tracking error signal is in the period T1, and when it is determined that L1 <L2 is not satisfied, the level of the tracking error signal is It is determined that the period is T3.

  The present invention is configured to generate a kick pulse from the kick pulse generation circuit 12 when it is determined by the above-described determination operation that the level of the tracking error signal is in the period T1. The period T1 is a period in which the level of the tracking error signal is small, that is, a period in which the rotational characteristic of the disk 1 is least affected by the eccentricity.

  In the above-described period T1, the displacement operation of the objective lens 4 is in a state in which the light beam is displaced toward the outer peripheral side of the disc 1, so that when the direction of performing the track jump operation is the outer peripheral direction of the disc 1, As shown in FIG. 3A, the kick pulse output from the pulse generation circuit 12 has a low acceleration pulse P1 level and a high deceleration pulse P2 level. On the other hand, when the direction in which the track jump operation is performed is the inner circumferential direction of the disk 1, the kick pulse output from the kick pulse generation circuit 12 has the level of the acceleration pulse P1 as shown in FIG. Large, the level of the deceleration pulse P2 is small.

  As described above, according to the present invention, in the period T1, a kick pulse as shown in FIGS. 3A and 3B is generated from the kick pulse generation circuit 12 in correspondence with the track jump direction. Jump operation can be performed. The levels and pulse widths of the acceleration pulse P1 and the deceleration pulse P2, which are kick pulses output from the kick pulse generation circuit 12, are set based on data set according to the number of tracks to be jumped. Become.

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. It is a signal waveform diagram for demonstrating operation | movement of this invention.

Explanation of symbols

1 disc
2 Optical pickup
3 Photodetector
4 Objective lens
5 Tracking coil
7 Tracking error signal generation circuit
9 Tracking coil drive circuit 10 System control circuit 12 Kick pulse generation circuit 13 Sampling circuit

Claims (6)

A track jump control method for an optical disc apparatus configured to read a signal recorded from the inner circumference side to the outer circumference side of the disc with an optical pickup, and obtained from a photodetector incorporated in the optical pickup. A tracking error signal generation circuit for generating a tracking error signal based on the generated signal and a sampling error obtained by sampling the tracking error signal generated by the tracking error signal generation circuit at a predetermined time. When the sampling value of the tracking error signal changes from small to large and the sampling value is within a predetermined range, a kick pulse is generated from a kick pulse generating circuit that supplies a kick pulse to a tracking coil that displaces the objective lens. What Track jump control method of the optical disk apparatus according to symptoms. 2. The track jump control method according to claim 1, wherein a predetermined range set for generating a kick pulse is set around a reference value for detecting a level of a tracking error signal. 2. The track jump control method according to claim 1, wherein a kick pulse comprising an acceleration pulse for displacing the objective lens and a deceleration pulse for stopping the displacement of the objective lens is generated from a kick pulse generation circuit. 4. The track jump control method according to claim 3, wherein the magnitudes of the acceleration pulse and the deceleration pulse are changed corresponding to the direction in which the objective lens is displaced. 4. The track jump control method according to claim 3, wherein the magnitude of the acceleration pulse is made small and the magnitude of the deceleration pulse is made large when the direction in which the objective lens is displaced is the outer peripheral direction. 4. The track jump control method according to claim 3, wherein when the direction in which the objective lens is displaced is the inner circumferential direction, the magnitude of the acceleration pulse is made large and the magnitude of the deceleration pulse is made small.

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