JP2877651B2 - Correction device for disk device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detecting unit such as an optical head.
Is detected when the disc moves in the tracking direction of the disc.
When the detected signal has an offset amount,
The present invention relates to a correction device for a disk device that can correct the error.

[0002]

2. Description of the Related Art FIG. 3 is a component layout diagram showing an optical system of a magneto-optical disk drive using a movable mirror (galvano mirror) as a deflector. FIG. 4 detects a reproduction signal (MO signal) and a tracking error signal. FIG. 5 is an explanatory diagram showing a recording surface of a magneto-optical disk, and FIG. 6 is an explanatory diagram of a light receiving surface of a four-division light receiving unit for explaining a conventional problem. FIG. 7 is an explanatory view showing a state in which the shift amount changes between the outer peripheral portion and the inner peripheral portion of the optical disc. The magneto-optical disk device shown in FIG. 3 is a so-called separation optical system, and is divided into an optical system 1 on the fixed part side and an optical system 2 on the movable part side. The optical system 2 on the movable portion side is mounted on an optical head, and is driven in a radial direction β thereof along a recording surface of a magneto-optical disk by a linear motor indicated by reference numeral 33. The optical system 2 on the movable portion side is provided with an objective lens 3 facing the recording surface of the magneto-optical disk and a total reflection prism 4 located just below the optical axis.

[0003] A semiconductor laser 5 is provided in the optical system 1 on the fixed portion side. Laser light emitted from the semiconductor laser 5 passes through a collimating lens 6 to become a parallel light beam, is reflected by a beam splitter 7 and further has The light is reflected by the mirror 8 and sent to the total reflection prism 4 of the optical system 2 on the movable portion side. Then, after being reflected by the total reflection prism 4, it is condensed on the recording surface of the magneto-optical disk by the objective lens 3 to form a minute spot. The return light from the recording surface of the magneto-optical disk passes through the objective lens 3, the total reflection prism 4, and the galvanometer mirror 8, and passes through the beam splitter 7. The transmitted light is converged by the condenser lens 9 and is divided into three lights E0, E1, and E2 by the polarization splitter 10.
Is separated into The polarization splitter 10 is composed of, for example, a Wollaston prism or the like, and the return light from the magneto-optical disk is used as a light component E1,
E2 and a light component E0 for detecting a focus and tracking error signal.

The separated light components are received by a pin photodiode 11. This pin photodiode 1
1 has a light receiving portion 11a divided into four, and light receiving portions 11b and 11c arranged on both sides thereof. The light E0 separated by the polarization separator 10 is received by a four-divided light receiving unit 11a, and a tracking error and a focus error are detected by the light receiving unit 11a. Although not shown in the figure, a member for generating astigmatic difference, such as a cylindrical lens, is provided on the path of the light E0 in order to obtain a focus error signal by the four-division method. The light E1 separated into different polarization components (P-wave component and S-wave component) to detect the reproduction signal (MO signal)
And E2 are received by the light receiving units 11b and 11c, respectively.

FIG. 4 shows a circuit configuration for detecting a reproduction signal (MO signal) and a tracking error signal based on the light receiving output of the pin photodiode 11. In the circuit shown in the drawing, the difference between the amounts of light received by the two light receiving units 11b and 11c is calculated by the arithmetic unit 16 to obtain an MO reproduction signal (I-J output) corresponding to the angular direction of the Kerr rotation angle. Can be In a tracking error signal detection method generally called a push-pull method, arithmetic units 13, 14, and 15 calculate (B + D)-(A + C) for each light reception amount of the four-divided light receiving unit 11a. .

FIG. 5 shows the recording surface of a magneto-optical disk. The MO signal recording area (a) has a land 17 as a signal recording surface and grooves 18 formed on both sides thereof. Grooves are formed. FIG. 7A shows a state in which a spot of a laser beam is moving on a land 17 as a track without a tracking error.
(B) or (c) shows a state in which a part of the spot is on the groove 18 and a tracking error occurs.

As shown in FIG. 6, a four-divided light receiving section 11a
The light reflected from a minute spot formed on the recording surface of the magneto-optical disk forms an image, and a light receiving spot S is formed. As shown by (b) or (c) in FIG. 5, when the minute spot is on the groove 18, the light receiving unit 11
A shadow Sa will be generated at any edge of the light receiving spot S on a. On which side the decrease in the amount of received light due to the shadow Sa can be detected based on the output from the arithmetic unit 15, a tracking error signal is thereby obtained. As a tracking correction operation based on this error signal, first, fine correction of a tracking error is performed by slightly moving the galvanometer mirror 8 in the α direction with respect to the O axis by the galvanometer mirror driving unit 12 shown in FIG. This is performed by moving the optical system 2 on the movable portion side in the β direction by the motor 33.

[0008]

In the tracking error signal detection method according to the push-pull method shown in FIG.
The amount of light received by the divided light receiving unit 11a is detected separately for the left and right as (A + C) and (B + D), and the difference is taken. Therefore, if there is a relative displacement in the tracking direction between the center position of the light receiving unit 11a and the center position of the light receiving spot S, the detection accuracy of the tracking error signal is greatly affected. For example, if there is a quantitative shift δ between the center of the light receiving unit 11a and the center Os of the light receiving spot S as shown in FIG. Even if the shadow Sa is on the left side of the spot S, (A + C) and (B +
The difference in the amount of received light in D) cannot be accurately detected, resulting in an offset.

As a method for coping with the shift of the light receiving spot S, for example, a bias voltage applied to a tracking error signal is adjusted in an adjustment stage so as to cancel out a difference between the light receiving amounts of the right and left light receiving sections due to the positional shift of the light receiving spot S. There is something that I did. However, in the adjustment by the bias voltage described above, there is a limit to the shift amount δ that can be corrected, and therefore, it is necessary to maintain the positioning of each optical component and the like with extremely high accuracy. Further, after the adjustment is once performed, it is impossible to cope with a shift that occurs over time due to curing of the adhesive at the bonding portion of the optical component.

On the other hand, the mirror surface (see (b) of FIG. 5) formed on the magneto-optical disk is irradiated with detection light to form a light-receiving spot S without shadow on the light-receiving portion 11a. By performing the operation of (B + D)-(A + C),
The offset amount due to the deviation δ can be detected, and the tracking error signal can be corrected by subtracting a component corresponding to the offset amount from the tracking error signal. However, the time required for the detection light to pass through the mirror surface is as short as about 2 μs, and it is extremely difficult to reliably extract the detected component in a short time.

Further, when the offset amount is quantitatively obtained from the mirror surface, for example, when δ occurs due to a shift in the mounting position of the pin photodiode 11, it can be dealt with. If there is an error, it cannot be handled. That is, galvanometer mirror 8
If there is an error in the neutral position of the tilt in the α direction, as shown in FIG. 7, the offset amount is δ1, when the spot of the laser beam is near the outer circumference and near the inner circumference of the magneto-optical disk. It will change as shown by δ2. In the case where the offset amount fluctuates in this manner, it is not possible to cope with the situation by merely obtaining a quantitative offset correction amount by detecting the mirror surface, and it is necessary to always detect the mirror surface and detect the offset amount at each time. Will not be.

Therefore, the present invention corrects the offset amount.
It is a first object of the present invention to provide a correction device for a disk device which is made possible.

[0013]

[0014]

According to the present invention, there is provided a disk drive comprising:
The compensator moves along the disk and records it on the disk.
A detecting unit for detecting the detected signal; and
Seek to perform seek operation in the direction crossing the recording track
Means, and the detecting unit is moved in a direction traversing the recording track.
The peak and bottom obtained when moving
Detecting means for detecting a detection signal that appears;
Calculates the amount of offset from the average of peak and bottom values
Means for performing the detection, and
To determine whether the amount changes or changes as the part moves
Disconnection means and the offset amount is determined to be quantitative
Sometimes, a first supplementary correction is made to reduce the offset amount.
Correct means, and the offset amount fluctuates.
A second method of reducing the offset amount when it is determined that
Correction means and seek operation during recording or playback operation.
The issued offset amount is based on the determination means.
A system for controlling switching between the first correction means and the second correction means.
And a control unit.

[0015] For example, the detection unit may emit detection light to a disk.
An objective lens for focusing light, and the objective lens on a fixed side
A deflector for providing the detection light to the first correction means.
The stage comprises a signal component corresponding to an offset amount from the detection signal.
Subtraction means for subtracting a minute, wherein the second correction means comprises:
The deflection angle of the deflector is changed by the amount corresponding to the offset amount.
This is a means for correcting.

[0016]

[0017]

According to the present invention, the detecting section is moved across the track of the disk.
The amount of offset of the detection signal obtained when moving in the direction
The amount of offset is quantitative when removing
Or fluctuating, and the offset is determined.
Switch the correction method according to whether the cut amount is quantitative or variable.
I can get it. As a result, the offset from the detection signal
Not only subtract the offset amount, but also change the offset amount.
The movement can also be corrected.

[0018]

[0019]

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a circuit configuration showing a correction device of a magneto-optical disk device as one embodiment. The circuit shown in FIG. 1 is connected to the subsequent stage of the computing unit 15 shown in FIG. FIGS. 2A and 2B are waveform diagrams showing a tracking error signal and its offset amount. The correction device shown in FIG. 1 is mounted on a magneto-optical disk device using a galvanometer mirror 8 as a deflector shown in FIG. In the magneto-optical disk device shown in FIG. 3, a laser beam emitted from a semiconductor laser 5 provided in a fixed-side optical system 1 is reflected by a galvano mirror 8, and the objective lens 3 provided in the optical system 2 allows the magneto-optical disk to be used. Is focused on the recording surface of. In the reproducing or recording operation, the spot of the laser beam is finely driven in the tracking direction (T direction) on the recording surface of the magneto-optical disk by swinging the galvanometer mirror 8 in the α direction. In addition, the optical system 2 is driven in the β direction by the linear motor 33, thereby performing a coarse tracking operation and a seek operation.

An arithmetic circuit for calculating the tracking error and calculating the MO signal shown in FIG. 4 is connected to the pin photodiode 11 shown in FIG. 3, but the tracking error signal is calculated at the left end in FIG. Arithmetic unit 15 is shown. In the device shown in FIG.
Are supplied to the tracking controller 26 via the subtraction circuit 20. A tracking controller 26 generates a tracking correction control signal, and the control signal is supplied to the galvano controller 28 and the linear motor controller 27.
The drive signal from the galvano controller 28 is supplied to the galvanomirror driving unit 12 via the Q dump circuit 31, and the galvanomirror 8 is driven in the α direction. In addition, the linear motor 33 operates according to a drive signal from the linear motor controller 27, and the optical system 2 is driven in the β direction.

In the reproducing or recording operation, the position of the minute spot formed on the recording surface of the magneto-optical disk is changed by the fine tracking correction by the galvanometer mirror 8 and the coarse tracking correction by the linear motor 33. Since the tracking error signal is generated by the detector 15, a closed loop of the tracking correction is formed. The tracking error signal obtained by the calculator 15 is provided to the offset amount calculator 41. The offset amount calculation section 41 is provided with a peak / bottom detection section 34. The peak / bottom detection unit 34 includes a peak detection circuit 24 that samples and holds a peak value of a tracking error signal during a seek,
A bottom detection circuit 25 that samples and holds the bottom value of the tracking error signal is provided.

The detection output from the peak detection circuit 24 and the detection output from the bottom detection circuit 25
And given to the control unit 29 via the A / D converter 30. The control unit 29 has a CPU (Central Processing).
Unit). The control unit 29 generates a switching signal for switching the changeover switch 35. Further, the control unit 29 has a function of calculating an average value from a peak detection value from the peak detection circuit 24 selected by the changeover switch 35 and a bottom detection value from the bottom detection circuit 25. Further, the control unit 29
Has a function of recognizing whether the calculated average value is quantitative or variable.

The control unit 29 outputs a correction signal based on the average value, and generates a switching control signal based on recognition of whether the average value fluctuates. The control signal is supplied to the multiplexer 21 through a path indicated by A. Multiplexer 2
Reference numeral 1 denotes a switching operation based on the switching control signal. By this switching operation, a correction signal based on the average value is supplied to the subtraction circuit 20 via the D / A converter 23, or the D / A converter The signal is supplied to the galvanomirror driving unit 12 through the line 22. Further, for example, before the reproducing or recording operation is performed, or when a predetermined search command is given, a seek command signal is issued from the control unit 29 through the path B, and this signal is transmitted to the linear motor controller 27.
Given to. The operation of the control unit 29 is performed based on predetermined programming stored in a ROM or the like.

The operation of the apparatus having the above configuration will be described with reference to FIGS. 2 (A) and 2 (B). FIG. 2 (A),
(B) shows a case where the optical system 2 on the movable portion side is moved in the β direction by the linear motor 33 and seek operation is performed in a direction crossing the track of the magneto-optical disk.
5 shows a tracking error signal obtained at 5,
FIG. 7A shows a case where a quantitative offset amount (δ) is generated in the tracking error signal due to, for example, a shift δ of the mounting position of the pin photodiode 11, and FIG. This shows a case where there is an angle error in the neutral angle of, and an offset amount (δ1−δ2) that fluctuates in the tracking error signal. This variation in the offset amount is caused by a difference in whether the spot on the recording surface of the magneto-optical disk is located on the inner circumference side or the outer circumference side due to an error in the neutral angle of the galvanometer mirror 8.

In this apparatus, when the magneto-optical disk is loaded and after the power is turned on and before the reproduction or recording is performed, the seek operation signal is transmitted from the control unit 29 to the linear motor controller 27 through the path indicated by B. Given to
The optical system 2 on the movable portion side is forcibly driven in the radial direction of the rotating disk to perform a seek operation. This seek operation is performed by the control unit 2 based on a predetermined search command.
9 may be emitted. In this seek operation, the semiconductor laser 5 of the optical system 1 on the fixed portion side shown in FIG.
Is irradiated with laser light. This laser light passes through a collimating lens 6 to become a parallel light flux, is reflected by a beam splitter 7, is further reflected by a galvanometer mirror 8, and is sent to a total reflection prism 4 of the optical system 2 on the movable section side. Then, the light is reflected by the total reflection prism 4 and condensed on the recording surface of the magneto-optical disk by the objective lens 3 to form a minute spot. At this time, the rotation angle of the galvanometer mirror 8 in the α direction is the neutral position.

When the linear motor 33 is controlled by the linear motor controller 27 and the optical system 2 on the movable part side moves in the direction β, a minute spot of the laser light condensed by the objective lens 3 is formed, for example, on the inner circumference of the magneto-optical disk. The minute spot moves from the recording section to the outer peripheral section at a high speed, and the minute spot crosses the land 17 and the groove 18 on the recording surface. When the return light reflected from the recording surface at this time is received by the four-division light receiving unit 11a of the pin photodiode 11, the arithmetic unit 15 obtains tracking error signal signals P1 and P2 having continuous waveforms as shown in FIG. Can be

The tracking error signal P1 shown in FIG. 3A shows a case where a quantitative offset δ is generated with respect to the zero point (0 V) of the subtraction by the calculator 15. This offset amount is, for example, the pin photodiode 1
The center of the return light receiving spot S and the light receiving unit 11 are caused as shown in FIG.
This occurs when the center of a is shifted by δ in the tracking direction. The tracking error signal P2 shown in FIG. 7B includes an offset amount that varies almost linearly from δ1 to δ2. This is due to an angular error in the neutral state of the galvanometer mirror 8, and an offset amount varies depending on whether there is a minute spot on the inner peripheral side or a minute spot on the outer peripheral side of the recording surface of the magneto-optical disk. FIG. 6B shows a case where a more quantitative offset amount is superimposed on the offset amount (δ1−δ2) that varies linearly.

The tracking error signal P1 or P2 obtained by the seek operation is applied to the peak detection circuit 24 and the bottom detection circuit 25 of the offset amount calculation section 41. In the peak detection circuit 24, FIG.
The peak value of the waveform of the tracking error signal is sampled and held, and the bottom value of the tracking error signal is sampled and held in the bottom detection circuit 25. The peak value and the bottom value are determined by the changeover switch 35.
, And is converted into a digital value by the A / D converter 30 and supplied to the control unit 29. And control unit 2
In step 9, the average of the peak value and the bottom value is calculated. FIG.
In (A) and (B), the average value is indicated by Pv1 and Pv2. This average value is the offset amount of the tracking error signal P1 or P2.

The timing at which the peak value and the bottom value are detected by the changeover switch 35 is set. When the seek operation is performed, the changeover switch 35 is continuously and alternately switched.
The peak value and the bottom value may be calculated at a constant pitch, or may be detected in a sample at a fixed time interval. The above average value is stored and stored in a register of the control unit 29. The control unit 29 determines whether the average value Pv1 is constant as shown in FIG. Thus, a switching control signal for switching the multiplexer 21 is generated depending on whether or not the average value Pv2 fluctuates.

Next, the operation proceeds to the reproducing or recording operation. In the recording or reproducing operation, the output of the light receiving section 11a of the pin photodiode 11 is calculated by the calculator 15 to obtain a tracking error signal, and the galvanomirror driving section 12 is driven by the tracking error signal to perform fine correction of tracking. Also, the optical system 2 on the movable portion side is driven in the β direction by the linear motor 33 to perform coarse tracking correction. Here, the average value, that is, the offset amount detected at the time of the seek is Pv in FIG.
When the signal is quantitative as indicated by 1, the multiplexer 21 is switched by the switching control signal from the control unit 29, and the signal component corresponding to the average value, ie, the offset amount, stored in the control unit 29 is D / A. The signal is converted into an analog signal by the converter 23 and supplied to the subtraction circuit 20.
In the subtraction circuit 20, a component corresponding to the offset amount is subtracted from the tracking error signal during the reproducing or recording operation. As a result, the tracking error signal that has passed through the subtraction circuit 20 has no offset component, and high-accuracy tracking correction is performed.

When the offset amount detected at the time of seek varies as indicated by Pv2 in FIG. 2B, the average value stored in the control unit 29, ie, the offset amount, is switched by switching the multiplexer 21. Is converted into an analog signal by the D / A converter 22 and directly supplied to the galvanomirror drive unit 12 to correct the inclination error of the galvanomirror 8. Further FIG.
As shown in (B), when the average value, that is, the offset amount includes a fluctuation component and a quantitative component, for example, the multiplexer 21 is periodically switched during the reproduction or recording operation, and the subtraction circuit 20 and the galvanometer are connected. The offset amount is alternately provided to the mirror driving unit 12 to remove the offset amount from the tracking error signal. Although the galvanomirror is shown as a deflector for performing tracking correction in the above embodiment, the deflector may be a deflector that deflects light by changing a refraction angle due to an acousto-optic effect or an electro-optic effect. .

[0033]

As described above, according to the present invention, the movement of the detecting unit
The amount of offset of the detection signal detected by
The amount of offset, even if it fluctuates
It is possible to make a correction according to the state.

[0034]

[0035]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of a correction device in an optical disk device as one embodiment.

FIGS. 2A and 2B are waveform diagrams showing a tracking error signal during a seek operation and an average value thereof.

FIG. 3 is a component arrangement diagram showing an optical system of a magneto-optical disk device using a movable mirror (galvano mirror) as a deflector.

FIG. 4 is a circuit diagram showing a circuit configuration for detecting a reproduction signal (MO signal) and a tracking error signal.

FIG. 5 is an explanatory diagram showing a recording surface of a magneto-optical disk.

FIG. 6 is an explanatory diagram of a light receiving surface of a four-division light receiving unit for explaining a conventional problem.

FIG. 7 is a diagram showing a state where an offset amount is included in a tracking error signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical system on the fixed part side 2 Optical system on the movable part side 3 Objective lens 4 Total reflection prism 5 Semiconductor laser 6 Collimating lens 7 Beam splitter 8 Galvano mirror 9 Condensing lens 11 Pin photodiode 11a Four-division light receiving part 13 Computing unit 14 Operation Unit 15 arithmetic unit 20 subtraction circuit 21 multiplexer 22 D / A converter 23 D / A converter 24 peak detection circuit 25 bottom detection circuit 26 tracking controller 28 galvano controller 29 control unit 30 A / D converter 31 Q dump circuit 35 switching switch

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 7/09-7/095 G11B 7/085

Claims (2)

(57) [Claims] 1. Moving along a disk and recording on the disk
A detecting unit for detecting the detected signal;
Seek operation in the direction crossing the recording track of
In the direction in which the detecting section crosses the recording track.
The peak and bottom obtained during seek movement are periodic
Detecting means for detecting a detection signal appearing on the detection signal;
Offset from the average of peak and bottom values
Output means and the calculated offset amount are determined by the detection.
Determine whether the amount changes or changes as the outlet moves
Determining means for determining that the offset amount is quantitative;
Correction to reduce the offset amount when the first
Correction means, and the offset amount fluctuates.
A second method for reducing the offset amount when it is determined that
Correction means and seek operation during recording or playback operation.
The detected offset amount is based on the determination means.
Switching control between the first correction means and the second correction means;
And a control unit.
Correction device in the device. 2. The detection unit focuses detection light on a disk.
The objective lens on the fixed side.
A deflector for providing detection light, wherein the first correction unit includes:
A signal component corresponding to an offset amount is reduced from the detection signal.
Subtracting means, and the second correcting means comprises:
Correct the deflection angle of the deflector by the amount corresponding to the offset.
2. The correction in the disk drive according to claim 1,
apparatus.