JP2003162829A - Tracking control method for optical disc recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tracking control method for an optical disc device which records and reproduces signals on a disc by using an optical pickup. <P>SOLUTION: The first sub-beam and the second sub-beam are radiated to the tracks in front and rear of the track irradiated with the main beam. Tracking control is carried out depending on the signals obtained from the reflected light of the above beams. The signal obtained from the reflected light of the above second sub-beam is offset corrected based on the signal obtained from the reflected light of the above main beam. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention records a signal on a disc by a light beam emitted from an optical pickup and a reproducing or recording operation using a wobble signal recorded on a pre-groove formed on the disc. The present invention relates to an optical disc recording / reproducing device configured to perform.

[0002]

2. Description of the Related Art An optical disk recording / reproducing apparatus configured to record a signal on an optical disk by using a light beam emitted from an optical pickup has been commercialized. An optical disc used in such an optical disc recording / reproducing apparatus is formed with a groove called a pre-groove containing a wobble signal component. The pre-groove is used to perform tracking control of a light beam during recording. It is configured to control the rotation of the disk.

[0003]

In the optical disc recording / reproducing apparatus for recording a signal on the disc, since the signal recording operation is performed by using the above-mentioned wobble signal, it is necessary to detect the wobble signal accurately. There are various methods for detecting such a wobble signal, but generally, the wobble signal is detected based on a signal obtained from a photodetector incorporated in an optical pickup, for example, a photodetector called a 4-division sensor. . The disc used for recording operation is placed on a turntable and driven to rotate.
If chucking is not performed accurately, the disc is rotated in a tilted state, so it becomes impossible to perform the tracking control operation that causes the light beam to follow the signal track accurately, and as a result, the wobble signal There is a problem that the read operation cannot be performed accurately.

The tracking control operation in the optical disk recording / reproducing apparatus is performed by a main beam for recording a signal on a signal track of the disk, a first sub-beam located in front of the main beam and a second sub-beam located behind the main beam.
It is configured to use a signal obtained from the reflected light of each beam of the sub beam. Recently, a track in front of the track irradiated by the main beam is irradiated with the first sub-beam, and a track in the rear of the track irradiated by the main beam is irradiated with the second sub-beam.
A technique has been developed in which the signal recorded on the disc is monitored by the second sub-beam.

In the optical disc recording / reproducing apparatus having the above-described structure, in the state where the recording operation is performed, the first sub-beam irradiates the track on which the signal is not recorded, but the second sub-beam records the signal. The track is being illuminated. As a result, when the tracking control operation is performed, a level difference occurs between signals obtained from the first sub beam and the second sub beam, and there is a problem that the tracking control operation cannot be performed accurately.

The present invention is intended to provide a tracking control method for an optical disk recording / reproducing apparatus which solves the above problem.

[0007]

According to the present invention, the first sub-beam and the second sub-beam are irradiated to the front track and the rear track of the track irradiated with the main beam, and the tracking control operation is performed based on the signal obtained from the reflected light of each beam. The offset correction is performed on the signal obtained from the reflected light of the second sub-beam based on the signal obtained from the reflected light of the main beam.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The circuit shown in FIG. 1 is a block circuit diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing the relationship between signal tracks and light beams.

In FIG. 1, reference numeral 1 denotes a main beam photodetector which is incorporated in an optical pickup and which is irradiated with a main beam M reflected from a signal surface of a disk. And D part. Reference numeral 2 denotes a first sub-beam photodetector which is incorporated in the optical pickup and is irradiated with the first sub-beam S1 reflected from the signal surface of the disc. ing. Reference numeral 3 denotes a second sub-beam photodetector which is incorporated in the optical pickup and which is irradiated with the second sub-beam S2 reflected from the signal surface of the disc. It is configured.

The main beam M and the first sub beam S1
And the relationship with the second sub-beam S2 are as shown in FIG. That is, when the main beam M is located at an accurate position on the track N on which the recording operation is performed, the first sub-beam S1 is in a state where half of the beam is applied to the front track N + 1 track. , The second sub-beam S2 is in a state where half of the beam is applied to the rear track N-1 track. In addition, the direction of the dividing line between the A and B parts forming the main beam photodetector 1, the direction of the dividing line between the E and F parts forming the first sub-beam photodetector 2, and the second sub-beam. The direction of the dividing line of the G portion and the H portion which configure the use detector 3 is set to coincide with the tangential direction of the track provided on the disc.

Reference numeral 4 denotes a main beam first adder circuit for receiving signals obtained from the A and D sections of the main beam photodetector 1 and adding both signals. Reference numeral 5 denotes the main beam light. A second adder circuit for main beam, which receives the signals obtained from the B and C parts of the detector 1 and adds both signals, 6 is an output signal of the first adder circuit 4 for the main beam and the main signal It is a first subtraction circuit for the main beam, which receives the output signal of the second beam addition circuit 5 and outputs a difference signal between the two signals.

Reference numeral 7 is a first sub-beam subtraction circuit which receives signals obtained from the E and F sections of the first sub-beam photodetector 2 and outputs a difference signal between the two signals, and 8 is the first sub-beam subtraction circuit. G that constitutes the photodetector 3 for two sub-beams
Is a subtraction circuit for the second sub-beam, which receives a signal obtained from the H and H sections and outputs a difference signal between the two signals.

Reference numeral 9 is a main beam third adder circuit for receiving signals from the sections A and B constituting the main beam photodetector 1 and adding both signals.
Is a C portion and a D constituting the photodetector 1 for the main beam.
A main beam fourth adder circuit for inputting a signal obtained from the main beam adder and adding both signals, and 11 an output signal of the main beam third adder circuit 9 and an output signal of the main beam fourth adder circuit 10. Is a main beam second subtraction circuit that outputs a difference signal between the two signals, and is configured to output an offset signal for correcting an offset described later.

Reference numeral 12 denotes the main beam second subtraction circuit 1
1 is an output signal, that is, an offset signal, and is a level setting circuit that adjusts the level of the offset signal, and the setting level is determined by the control circuit 13. Reference numeral 14 denotes a switch circuit whose operation is controlled by the control circuit 13 and which opens and closes the switch 15 inserted in the output signal path of the level setting circuit 12 when the switch 15 is in the recording operation state.
Is configured to close.

Reference numeral 16 denotes an offset signal output from the level setting circuit 12 via the switch 15 and an output signal of the second sub-beam subtraction circuit 8 while the recording operation is being performed, and both signals are added. A first adder circuit 17 for performing the first sub-beam subtraction circuit 7
And the output signal of the first adder circuit 16 is input, and is a second adder circuit for adding both signals.

According to the above-mentioned structure, a signal corresponding to the deviation of the main beam M from the track N is output to the output terminal of the main beam first subtraction circuit 6, and the output terminal of the second addition circuit 17 is output. , Deviation from the track N + 1 of the first sub-beam S1 and track N of the second sub-beam S2
A signal obtained by adding the deviation with respect to -1 is output, but the phase between the output signal of the first subtraction circuit 6 for the main beam and the output signal of the second addition circuit 17 depends on the movement of the lens or the disc. 18 for offset due to distortion of
It is set so that the relationship is shifted by 0 degree.

Reference numeral 18 denotes the first subtraction circuit 6 for the main beam.
Is a tracking error signal output circuit for inputting the output signal of 1) and the output signal of the second adder circuit 17 and outputting the difference signal of the two signals as a tracking error signal to the output terminal. Reference numeral 19 denotes a tracking control circuit for performing a control operation for causing the main beam M to follow the track N by displacing the objective lens incorporated in the optical pickup, and a tracking error signal output from the tracking error signal output circuit 18. The tracking control operation is performed based on the above.

In such a structure, the level setting operation by the level setting circuit 12 by the control circuit 13 is performed by setting the gain for amplifying the offset signal output from the second main beam subtracting circuit 11, for example. The gain setting operation is configured to be performed in accordance with, for example, the disc type, the signal recording speed, the track pitch of the disc, and the like.

The present invention is constructed as described above. Next, the tracking control operation of the present invention will be described. When the optical disk recording / reproducing apparatus is set to the recording operation state, the switching operation is performed by the switch circuit 14, and the switch 15 is closed. Although various control operations for performing the recording operation are performed, the optical disk recording / reproducing apparatus is in a state of performing the recording operation. In the state of performing the recording operation, the main beam M, the first
The irradiation positions of the sub beam S1 and the second sub beam S2 are
As shown in FIG. 2, the positions are set so as to correspond to the tracks N, N + 1 and N-1.

In such a state, a signal is recorded on the track N by the main beam M and the second sub-beam S2.
The reproduction operation of the signal recorded on the track N-1, that is, the monitor operation is performed. Then, the recording characteristic of the signal recorded on the disc is detected based on the monitor signal, and the laser output adjusting operation is performed based on the recording characteristic detected by the detecting operation.

In the recording operation state, the tracking error signal output circuit 18 is based on the signals obtained from the main beam photodetector 1, the first subbeam photodetector 2 and the second subbeam photodetector 3. Then, a tracking error signal is output, and the tracking control operation is performed by the tracking control circuit 19 based on the tracking error signal.

Then, the tracking control operation is
The detection is performed based on not only the signal obtained from the main beam photodetector 1 but also the signals obtained from the first sub-beam photodetector 2 and the second sub-beam photodetector 3, but the first sub-beam photodetector The reflected light radiated to 2 is a signal from the track N + 1 in which no signal is recorded, and the reflected light radiated to the second sub-beam photodetector 3 is a signal from the track N-1 in which a signal is recorded. Therefore,
A level difference, that is, an offset occurs between the two signals.

In the present invention, such an offset is corrected by an offset signal generated based on the signal obtained from the main beam photodetector 1. The level of the offset signal output from the level setting circuit 12 is set by the control operation by the control circuit 13 based on the data set corresponding to the type of the disc, the recording speed of the signal and the track pitch of the disc. Since the offset change and the level change of the RF signal detected from the low frequency component of the signal including the high frequency (RF) component obtained from the main beam photodetector 1 change according to the recording characteristics of the signal on the disc, The level of the offset signal changes according to the recording characteristics. In the present invention, the signal obtained from the second sub-beam photodetector 3 is offset-corrected by the offset signal output from the level setting circuit 12, so that the signal obtained from the first sub-beam photodetector 2 is corrected. The offset between can be corrected. As a result, since an accurate tracking error signal can be output from the tracking error signal output circuit 18, an accurate tracking control operation can be performed.

Although the tracking control operation in the recording operation state is performed as described above, the tracking control operation in the reproducing operation is performed with the switch 15 opened. That is, since signals are recorded on all tracks of the track N, the track N + 1, and the track N-1 in the disc that performs the reproducing operation, the first sub-beam photodetector 2 and the second sub-beam photodetector 3 This is because there is no need to perform offset correction because no offset occurs between the obtained signals.

In this embodiment, the signal obtained from the second sub-beam photodetector 3 is offset-corrected based on the reflected light obtained from the track N, but it is based on the reflected light obtained from the track N. It is also possible to perform offset correction on the signal obtained from the first sub-beam photodetector 2.

[0026]

According to the present invention, the first sub-beam and the second sub-beam are irradiated to the front track and the rear track of the track irradiated with the main beam, and the tracking control is performed based on the signal obtained from the reflected light of each beam. Since it is configured to perform the operation, the signal obtained from the reflected light of the second sub-beam or the signal obtained from the reflected light of the first sub-beam is offset-corrected based on the signal obtained from the reflected light of the main beam. Accurate tracking control operation can be performed.

Further, according to the present invention, since the recorded signal is monitored by the second sub-beam,
It is possible to perform a control operation such as a laser output adjustment operation based on the monitor signal.

Further, according to the present invention, the level of the signal obtained from the reflected light of the main beam is changed according to the type of the disc, the recording speed of the signal or the track pitch of the disc, so that an accurate offset correction is performed. You can

[Brief description of drawings]

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

FIG. 2 is a diagram showing a relationship between a signal track and a light beam.

[Explanation of symbols]

1 Main beam photodetector 2 Photodetector for first sub-beam 3 Photodetector for second sub-beam 4 First addition circuit for main beam 5 Second addition circuit for main beam 6 First subtraction circuit for main beam 7 Sub-beam subtraction circuit 8 Sub-beam subtraction circuit 9 Main beam third adder circuit 10 Main beam fourth adder circuit 11 Second subtraction circuit for main beam 12 level setting circuit 16 First addition circuit 17 Second adder circuit 18 Tracking error signal output circuit 19 Tracking control circuit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akira Tsukihashi             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. F-term (reference) 5D118 AA13 AA18 AA26 BA01 BF02                       BF03 CA13 CB03 CC12 CD03                       CD11 CF05 CG04

Claims (6)

[Claims] 1. An optical pickup for irradiating a disc with a main beam for recording a signal on a disc, a first sub-beam located in front of the main beam and a second sub-beam located behind the main beam. In an optical disk recording / reproducing apparatus configured to perform a recording / reproducing operation using the same, irradiating a first sub beam and a second sub beam to a front track and a rear track of a track irradiated with a main beam and reflecting the respective beams. The tracking control operation is performed based on the signal obtained from the light, and the signal obtained from the reflected light of the second sub-beam is offset-corrected based on the signal obtained from the reflected light of the main beam. And a tracking control method for an optical disk recording / reproducing apparatus. 2. An optical pickup for irradiating a disc with three beams: a main beam for recording a signal on the disc, a first sub-beam located in front of the main beam, and a second sub-beam located behind the main beam. In an optical disk recording / reproducing apparatus configured to perform a recording / reproducing operation using the same, irradiating a first sub beam and a second sub beam to a front track and a rear track of a track irradiated with a main beam and reflecting the respective beams. The tracking control operation is performed based on the signal obtained from the light, and the signal obtained from the reflected light of the first sub-beam is offset-corrected based on the signal obtained from the reflected light of the main beam. And a tracking control method for an optical disk recording / reproducing apparatus. 3. The tracking control method according to claim 1, wherein the monitoring operation of the recorded signal is performed by the second sub-beam. 4. The tracking control method according to claim 1, wherein the level of the signal obtained from the reflected light of the main beam is changed according to the type of the disk. 5. The tracking control method according to claim 1, wherein the level of the signal obtained from the reflected light of the main beam is changed according to the recording speed of the signal. 6. The tracking control method according to claim 1, wherein the level of the signal obtained from the reflected light of the main beam is changed according to the track pitch of the disk.