JP2003141758A - Optical disk recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk recording and reproducing device performing the recording and reproducing operation of a signal to the disk by an optical pickup. SOLUTION: The device is constituted of a photodetector 1 for main beam, which is irradiated by the main beam reflected from the disk surface and composed of quadri-sected A-part, B-part, C-part and D-part, a photodetector 2 for 1st sub-beam, which is irradiated by the 1st sub-beam reflected from the disk surface and composed of bisected E-part and F-part, and a photodetector 3 for 2nd sub-beam, which is irradiated by the 2nd sub-beam reflected from the disk surface and composed of bisected G-part and H-part, then the offset amount is detected by signals obtained from the A, B, C, D, E, F, G and H parts constituting each photodetector in the ON state of the tracking servo which makes the light beam follow up to the track.

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. Further, such an optical disc recording / reproducing apparatus is configured to incorporate address information of absolute time into the wobble signal and detect the signal to perform an access operation of a recording position.

[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. Similarly, if the disc is warped, the wobble signal cannot be read out accurately.

The present invention is intended to provide an optical disk recording / reproducing apparatus which solves such a problem.

[0005]

According to the present invention, a main beam which is incorporated in an optical pickup and which is reflected by a disk surface is irradiated and is divided into four parts.
Main beam photodetector, which is composed of section B, section C, section D, and section E, which is irradiated with the first sub-beam which is incorporated in the optical pickup and reflected from the disk surface, and which is divided into two. And a first sub-beam photodetector, which is composed of an F part, and a second sub-beam which is incorporated in the optical pickup and which is reflected from the disk surface, and which is composed of a G part and an H part which are divided into two parts. A photodetector for two sub-beams, and A, B, C, D, which compose each photodetector, in the ON state of the tracking servo for making the light beam follow the track.
The signals obtained from the E, F, G and H parts are converted into A, B, C,
When D, E, F, G and H, K is a constant determined by the optical pickup, and OS is an offset amount, OS = {(A + D)-(B + C)} + K * {(E + G)
The offset amount is detected by-(F + H)}.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The circuit shown in FIG. 1 is an embodiment of a signal detection circuit according to the present invention, FIG. 2 is a block circuit diagram showing an embodiment of the present invention, and FIG. 3 shows the relationship between a signal track and a light beam. FIG.

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 as shown in FIG. 3, and the relationship between each beam and the land L and groove G formed on the disk is as shown. 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 that configure the use detector 3 is set so as to coincide with the tangential direction of the pre-groove provided on the disc.

Reference numeral 4 is a main beam first addition circuit for receiving signals obtained from sections A and D of the main beam photodetector 1 and adding these 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 denotes a sub-beam for receiving the signals obtained from the E section of the first sub-beam photodetector 2 and the G section of the second sub-beam photodetector 3 and adding the signals. A first adder circuit, 8 is the first
The second adder circuit for sub-beams, to which signals obtained from the F section of the photodetector 2 for sub-beams and the H section of the second photodetector 3 for sub-beams are input, and which adds the signals, The sub-beam subtractor circuit receives the output signal of the first sub-beam adder circuit 7 and the output signal of the second sub-beam second adder circuit 8 and outputs a difference signal between the two signals.

According to the above-described structure, a signal corresponding to the deviation of the main beam M from the track is output to the output terminal of the main beam subtracting circuit 6, and the sub beam S1 is output to the output terminal of the sub beam subtracting circuit 9. , S2, a signal corresponding to the deviation of the track with respect to the track is output, but the phase between the output signal of the main beam subtraction circuit 6 and the output signal of the sub beam subtraction circuit 9 is in a relationship shifted by 180 degrees. Is set to.

In the optical pickup, the main beam M, the first sub beam S1 and the second sub beam S2 are
Although split and generated by means called a diffraction grating, the level of the sub beam is smaller than that of the main beam. 1
Reference numeral 0 denotes a constant setting circuit for adjusting the level between the main beam and the sub beam, which has the function of adjusting the level of the signal output from the sub beam subtracting circuit 9.

Reference numeral 11 is a tracking error signal output circuit which receives the output signal of the subtraction circuit 6 for the main beam and the output signal of the constant setting circuit 10 and outputs a difference signal between the two signals to the output terminal 12 as a tracking error signal. Is. A, B, C, which constitute each of the photodetectors,
The signals obtained from the D, E, F, G and H parts are A, B,
If C, D, E, F, G and H, a constant determined by the optical pickup, that is, a coefficient set by the constant setting circuit 10 is K, and a tracking error signal is TE, TE is output terminal 12. = {(A + D)-(B + C)}-K * {(E + G)
The tracking error signal TE represented by − (F + H)} is output.
This is the output signal of the subtraction circuit 6 for the main beam (A + D)
Since-(B + C) and the output signal (E + G)-(F + H) of the subtraction circuit 9 for the sub-beam have a phase shift of 180 degrees, the two output signals are summed up, and tracking of tracking is performed. The tracking error signal TE indicating the deviation can be obtained with high sensitivity.

An offset signal output circuit 13 receives the output signal of the subtraction circuit 6 for the main beam and the output signal of the constant setting circuit 10 and outputs the sum signal of the two signals as an offset signal to the output terminal 14. . The signals obtained from the A, B, C, D, E, F, G and H parts constituting each of the photodetectors are A, B, C, D, E, F and G.
And H, a constant determined by the optical pickup, that is, a coefficient set by the constant setting circuit 10 is K, and an offset amount is OS, OS = {(A + D)-(B + C)} at the output terminal 14. + K * {(E + G)
The offset signal represented by − (F + H)} is output. The output signal of the main beam subtraction circuit 6 is (A + D)-(B + C).
And the output signal of the sub-beam subtraction circuit 9 (E + G)
Since-(F + H) has a phase difference of 180 degrees, the two output signals are subtracted. As a result of such subtraction processing, a signal in which the tracking error signal obtained from each photodetector is canceled at the output terminal 14,
That is, a signal indicating the offset amount is output.

Although the tracking error signal TE and the offset amount OS are detected as described above, in the present invention, the tracking servo for causing the light beam to follow the track is performed in the ON state. That is, since the tracking error signal TE is used to perform the tracking servo operation, it is obvious that the tracking error signal TE is detected when the tracking servo is in the ON state. On the other hand, when the detection operation of the offset amount OS is performed while the tracking servo is on, the tracking servo operation causes the displacement operation of the objective lens, so that the displacement of the objective lens has an influence, but it is detected. A desired offset amount OS can be obtained by averaging the offset amount OS over time or performing a peak detection processing operation.

The detection circuit for the tracking error signal and the offset signal is configured as described above. Next, an embodiment using such a circuit will be described with reference to the circuit shown in FIG.

In FIG. 2, reference numeral 15 is a signal detection circuit composed of the circuit shown in FIG. 1, and is provided with an output terminal 12 for outputting a tracking error signal and an output terminal 14 for outputting an offset signal. ing. Reference numeral 16 denotes an objective lens incorporated in the optical pickup, which is configured to be displaced in the direction of the disc surface by a focusing coil (not shown) and to be displaced in the radial direction of the disc by the tracking coil 17. Reference numeral 18 denotes a tracking control circuit incorporating a tracking servo circuit or the like, which supplies a tracking control signal to the tracking coil 17 by a tracking servo operation based on a tracking error signal output to the output terminal 12 of the signal detection circuit 15. Is configured.

Reference numeral 19 denotes a control circuit provided to control each operation of the optical disk recording / reproducing apparatus, which controls the tracking control circuit 18 and outputs an offset to the output terminal 14 of the signal detecting circuit 15. It is configured to perform various control operations described later based on the signal.

Reference numeral 20 denotes an offset correction circuit whose operation is controlled by the control circuit 19, and is configured to perform offset correction based on the offset amount detected by the signal detection circuit 15 to the tracking control circuit 18. There is.

The present invention is configured as described above, and the operation will be described below. The data signal recorded on the disk is the A that constitutes the photodetector 1 for the main beam.
It is configured to be obtained by summing signals obtained from all parts of the section, the section B, the section C, and the section D. Further, as described in the embodiment shown in FIG. 1, the offset amount is based on the signals obtained from the main beam photodetector 1, the first sub-beam photodetector 2 and the second sub-beam photodetector 3. Is detected.

In the offset amount detecting operation, the tracking servo by the tracking control circuit 18 is turned on,
Then, the focus servo by the focus control circuit (not shown) is performed in the ON state. In such a state, when the offset amount is zero, the level obtained by adding the signals obtained from the A and D sections and the signal obtained by the B section and C section which constitute the main beam photodetector 1 are added. And are equal. Further, the levels obtained from the E section and the F section of the first sub-beam photodetector 2 are the same, and the levels obtained from the G section and the H section of the second sub-beam photodetector 3 are the same. As a result, the level obtained by adding the signals obtained from the E section and the G section becomes equal to the level obtained by adding the signals obtained from the F section and the H section. Therefore, in such a state, the offset amount becomes zero, and the tracking control operation is performed without offset correction.

When the disc is rotated in a tilted state, the optical axis of the light beam reflected from the signal surface of the disc is displaced. As a result, the level obtained by adding the signals obtained from the A and D sections and the level obtained by adding the signals obtained from the B and C sections constituting the main beam photodetector 1 are different. In addition, the first sub-beam photodetector 2
Of the second sub-beam photodetector 3 and the levels obtained from the E part and the F part of the second sub-beam are different from each other.
The level obtained from the department will also be different. And
The level change of each part is opposite to the level change direction of the signal obtained from the A part, D part, E part and G part and the direction of the level change of the signal obtained from the B part, C part, F part and H part. Have a relationship.

As a result, the offset amount OS is OS = {(A + D)-(B + C)} + K * {(E + G)
− (F + H)}, the detected output is the signal detection circuit 15
Output to the output terminal 14 and input to the control circuit 19.

The operation of detecting the offset amount is performed as described above. The detected offset amount is influenced by the deviation of the objective lens due to the tracking control, but the obtained offset amount is controlled by the control circuit 19. A desired offset amount can be derived by performing averaging according to time and peak detection processing operation.

As a result of performing such processing operation, the system control circuit 19 generates a control signal for the offset correction circuit 20 to generate a signal for correcting the offset amount generated at the position where the recording operation is performed. Is output. When such a control signal is applied, the offset correction circuit 20 outputs a signal for correcting the offset to the tracking control circuit 18.

As a result, the tracking control signal supplied from the tracking control circuit 18 to the tracking coil 17 becomes an offset-corrected signal, so that the main beam M reflected from the signal surface of the disk is the main beam light. The main beam photodetector 1 is irradiated so that the level obtained by adding the signals obtained from the sections A and D and the level obtained by adding the signals obtained from the sections B and C are equal to each other. It Further, the first sub-beam S1 reflected from the signal surface of the disk is a light beam for the first sub-beam so that the signal levels obtained by the E section and the F section of the first sub-beam photodetector 2 become equal. Detector 2
The second sub-beam S2 that has been irradiated onto the second sub-beam and reflected from the signal surface of the disc is detected by the second sub-beam so that the levels obtained from the G part and the H part of the second sub-beam photodetector 3 are equal. The container 3 is irradiated.

As described above, since the tracking control operation is performed in a state where the offset is corrected even if the disc is rotated in a tilted state, the wobble signal reading operation can be accurately performed. Therefore, the signal recording operation on the disc can be performed accurately.

Further, the constant K set by the constant setting circuit 10 is set according to the characteristics of the optical pickup used, and the characteristics change due to variations even in the same product. If the value of the constant K can be adjusted for each pickup, a more accurate control operation can be performed.

[0029]

According to the present invention, a main beam which is incorporated in an optical pickup and which is irradiated with a main beam reflected from the disk surface and which is divided into four parts, A, B, C and D, is provided. Photodetector, and a first subbeam photodetector which is incorporated in an optical pickup and which is irradiated with a first subbeam reflected from a disk surface and which is divided into two parts, E and F,
A second sub-beam photodetector, which is incorporated in an optical pickup and which is irradiated by a second sub-beam reflected from the disk surface, and which is divided into two parts, G and H, is provided and the tracking servo is on. In the above, A, B, C, D, E, which constitute each of the photodetectors,
Since the offset amount is detected based on the signals obtained from the F, G and H parts, the offset amount can be detected during the recording operation.

Further, according to the present invention, since the correction operation for the tracking servo operation is performed based on the detected offset amount, the accurate tracking control operation can be performed. Therefore, according to the present invention, the recording is performed. The operation can be performed accurately.

Since the present invention makes it possible to adjust the constant K set to obtain the offset amount, when the characteristics of the optical pickup differ due to variations,
A more accurate control operation can be performed by adjusting the value of the constant K for each pickup.

[Brief description of drawings]

FIG. 1 is an embodiment of a signal detection circuit according to the present invention.

FIG. 2 is a block circuit diagram showing an embodiment of the present invention.

FIG. 3 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 first adder circuit Second adder circuit for 8 sub-beams 9 Sub beam subtraction circuit 10 Constant setting circuit 11 Tracking error signal output circuit 13 Offset signal output circuit 15 Signal detection circuit 18 Tracking control circuit 19 Control circuit 20 Offset correction circuit

Claims (3)

[Claims] 1. An optical disc recording / reproducing device configured to record a signal on a disc by a light beam emitted from an optical pickup and perform a tracking control operation of the light beam by using a pre-groove formed on the disc. In the apparatus, a main beam photodetector which is incorporated in an optical pickup and which is irradiated with a main beam reflected from a disc surface and which is divided into four parts A, B, C and D, A first sub-beam photodetector, which is incorporated in an optical pickup and which is irradiated with a first sub-beam reflected from the disc surface and is divided into two parts, E and F, is incorporated in the optical pickup. The second sub-beam reflected from the disk surface is emitted, and
A second sub-beam photodetector consisting of divided G and H parts, and A, B, C, D constituting each photodetector in the ON state of the tracking servo for making the light beam follow the track. , E, F, G and H signals are A, B, C, D, E, F, G and H, K is a constant determined by the optical pickup, and OS is an offset amount, OS = {(A + D)-(B + C)} + K * {(E + G)
An optical disc recording / reproducing apparatus characterized in that an offset amount is detected by − (F + H)}. 2. The optical disk recording / reproducing apparatus according to claim 1, wherein the constant K is adjustable. 3. The optical disk recording / reproducing apparatus according to claim 1, wherein a correction operation for the tracking servo operation is performed based on the detected offset amount.