JP2003157552A - Method for tracking control of optical disk recording/ playback device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for a tracking control of an optical disk recording/playback device in which a signal is recorded on and reproduced from a disk with an optical pickup. SOLUTION: A front track and a rear track of a track which is irradiated with a main beam are irradiated with a first sub-beam and a second sub-beam, respectively, a tracking control action is performed on the basis of signals derived from the reflected light of each of the beams, and the signal derived from the reflected light of the second sub-beam is corrected with an offset.

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 signal obtained from the reflected light of the second sub-beam is offset-corrected.

[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 S
The relationship between the first and second sub-beams S2 is the relationship 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 section and the B section that configures the main beam photodetector 1,
A track in which the direction of the dividing line between the E portion and the F portion forming the sub-beam photodetector 2 and the direction of the dividing line between the G portion and the H portion forming the second sub-beam detector 3 are provided on the disk. It is set to match the tangential direction of.

Reference numeral 4 is a main beam first addition circuit for inputting signals obtained from sections A and D of the main beam photodetector 1 and adding those signals. Reference numeral 5 is for the main beam. A second adder circuit for main beam, which receives the signals obtained from the B and C sections of the photodetector 1 and adds the signals, 6 is an output signal of the first adder circuit 4 for the main beam, and It is a subtraction circuit for the main beam which receives the output signal of the second addition circuit 5 for the main beam 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
Section and H section, and a subtraction circuit for the second sub-beam which outputs a difference signal between the two signals, and 9 sections G and H which constitute the photodetector 3 for the second sub-beam.
It is a second sub-beam adder circuit for adding a signal obtained from the unit and adding both signals.

Reference numeral 10 is an amplifier circuit for amplifying the high frequency signal which is the output signal of the second sub-beam adder circuit 9 and 11 is the signal amplified by the amplifier circuit 10. Recording characteristics of the signal recorded on the disk based on the input signal, for example, β of the signal recorded on the track by the main beam M
A control circuit that recognizes a value and is configured to perform various control operations described later. The β value described above is a value calculated based on the peak voltage and the bottom voltage of the signal reproduced from the disk as is well known, and the laser output control operation is performed so that this β value becomes a predetermined value. Is configured.

The signal reproduced by the second sub-beam S2 is the signal recorded on the track N-1 located behind the track N on which the recording operation is performed, and the signal recorded immediately before by the main beam M. Is. Therefore, the recording characteristic can be recognized by calculating the β value of the reproduction signal, and the laser output adjusting operation can be performed by using the recognized recording characteristic.

Reference numeral 12 is an offset signal generation circuit for generating an offset signal based on the offset correction data determined by the recording characteristic recognition operation by the control circuit 11. Reference numeral 13 denotes a switch circuit whose operation is controlled by the control circuit 11 and which opens and closes a switch 14 inserted in the output signal path of the offset signal generation circuit 12, and which switches the switch 14 when in a recording operation state. It is configured to be closed.

Reference numeral 15 denotes an offset signal output from the offset signal generation circuit 12 via the switch 14 and an output signal of the second sub-beam subtraction circuit 8 via the switch 14 and both signals in the recording operation state. A first adder circuit 16 for adding is a second adder circuit which receives the output signal of the first sub-beam subtracting circuit 7 and the output signal of the first adding circuit 15 and adds both signals.

According to the configuration described above, the track N of the main beam M is connected to the output terminal of the main beam subtracting circuit 6.
A signal corresponding to the deviation from the second addition circuit 1
The output terminal of 6 has a track N + of the first sub-beam S1.
1 and the track N-1 of the second sub-beam S2
However, the phase between the output signal of the main beam subtraction circuit 6 and the output signal of the second addition circuit 16 is caused by lens movement or disk distortion. The offsets are set to be 180 degrees apart.

A tracking error signal output circuit 17 receives the output signal of the main beam subtraction circuit 6 and the output signal of the second addition circuit 16 and outputs a difference signal between the two signals as a tracking error signal to an output terminal. Is. Reference numeral 18 denotes a main beam M by displacing an objective lens incorporated in the optical pickup.
Is a tracking control circuit that performs a control operation to cause the track N to follow the track N, and is configured to perform the tracking control operation based on the tracking error signal output from the tracking error signal output circuit 17.

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 13 and the switch 14 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 17 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 18 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.

The present invention is configured to correct such an offset by the offset signal generated by the offset signal generating circuit 12. The level of the offset signal generated by the offset signal generation circuit 12 is the level of the RF signal or the offset change detected from the low frequency component of the signal including the high frequency (RF) component obtained by the second sub-beam photodetector 3. It is set by the control circuit 11 based on the change. Since such an offset change and a level change of the RF signal change according to the recording characteristics of the signal on the disc, the offset amount setting operation can be performed by recognizing the recording characteristics. According to the present invention, the signal obtained from the second sub-beam photodetector 3 is offset-corrected by the offset signal generated by the offset signal generating circuit 12.
The offset with the signal obtained from the sub-beam photodetector 2 can be corrected, and as a result, an accurate tracking error signal is output as the tracking error signal output circuit 17
Since more output can be performed, 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 14 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 the present embodiment, the signal obtained from the second sub-beam photodetector 3 is offset-corrected based on the reflected light obtained from the track N-1, but it is obtained from the track N-1. The offset correction may be performed on the signal obtained from the first sub-beam photodetector 2 based on the reflected light.

[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 the operation is performed and the signal obtained from the reflected light of the second sub-beam is offset-corrected, an 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 recording characteristic of the signal recorded on the disk is recognized based on the signal obtained from the monitor signal, and the offset correction amount is set based on the recognized recording characteristic. , The offset correction amount can be set accurately.

[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 Subtraction circuit for main beam 7 Sub-beam subtraction circuit 8 Sub-beam subtraction circuit 9 Second sub-beam adder circuit 11 Control circuit 12 Offset signal generation circuit 15 First addition circuit 16 Second adder circuit 17 Tracking error signal output circuit 18 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 BA01 BC08 BF02                       BF03 CA13 CB03 CC12 CD03                       CD11 CG04 DA33

Claims (4)

[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 disc recording / reproducing apparatus configured to perform a recording / reproducing operation by using the first sub-beam and the second sub-beam on a front track and a rear track of a track on which the main beam is irradiated, and reflecting the respective beams. A tracking control method for an optical disk recording / reproducing apparatus, characterized in that a tracking control operation is performed based on a signal obtained from light, and a signal obtained from the reflected light of the second sub-beam is offset-corrected. 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 second sub-beam. A tracking control method for an optical disk recording / reproducing apparatus, comprising: 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. A recording characteristic of a signal recorded on a disc is recognized by a signal obtained from a monitor signal, and an offset correction amount is set based on the recognized recording characteristic. Item 4. The tracking control method according to Item 3.