JPH0896386A - Optical retrieval device - Google Patents

Abstract

PURPOSE: To correct offset of a tracking error signal generated by mechanical crosstalk of a focusing actuator in the tracking direction by improving a tracking control circuit of an optical disk. CONSTITUTION: A position detector 60 detects a position of an objective lens in the focusing direction, a focusing position detection signal 112 outputted from the detector 60 is given to a gain adjustment device 113, in which its gain is adjusted and the result is given to a subtractor 106 as a tracking direction crosstalk estimate signal 114. The subtractor 106 subtracts the tracking direction crosstalk estimate signal 114 from a tracking error signal 105 to correct an offset caused by the shift of a lens actuator accompanying the focusing in the tracking direction and to provide an output of a correction tracking error signal 107. The correction tracking error signal 107 is given to a tracking gain phase compensation device 108 and a tracking power amplifier 109 to drive the tracking actuator, that is, the tracking coil 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical retrieval device for optically reproducing information from an optical disk and optically recording information on the optical disk, and more particularly to accurately track a track of the optical disk with a light beam. The present invention relates to a tracking control device for an optical disk device.

[0002]

2. Description of the Related Art As a tracking error signal detection method for tracking a track of a laser beam condensed on a track of an optical disk, a dividing boundary is arranged in parallel with the tangential direction of the track.
A push-pull detection method is widely used in which a split light detector receives a reflected light beam from an optical disk and the difference between the outputs of the respective light detectors is used as a tracking error signal. In the push-pull detection method, when an objective lens actuator that shifts and tracks a light beam is used, it is known that an offset occurs in the tracking error signal due to the beam shift. In such an optical disk device, for example, the Optical Memory Symposium '85 Proceedings pp. As described in 195-208, a linear motor is used for tracking a large amplitude so that the light beam is not shifted.

However, in an optical disc in which the track intervals are narrowed to achieve a high density, the offset allowable value becomes small, and a slight movement in the tracking direction that occurs when the lens actuator is driven in the focus direction (in the tracking direction). Even with mechanical crosstalk), a non-negligible offset occurs in the tracking error signal, and tracking is performed at a position deviated from the track center. FIG. 12 shows an example of the relationship between the lens shift amount and the offset generation amount. FIG. 12 shows the amount of offset generation when the track intervals are 1.0 μm, 0.9 μm, 0.8 μm, and 0.7 μm. The offset generation amount increases as the track interval is narrowed. On the contrary, the track error allowable value needs to be made smaller as the track interval becomes narrower. Assuming that the track error tolerance is ± 5% of the track interval, the track interval is 0.
At 7 μm, it becomes ± 0.035 μm, and if the lens shift amount is 10 μm, the track error allowable value will be exceeded by itself.

[0004]

In order to prevent this offset from occurring, the mechanical crosstalk of the lens actuator must be reduced, and the lens actuator becomes expensive.

The present invention has been made in view of the above-mentioned circumstances, and provides an optical disk device equipped with a tracking control device capable of always maintaining a tracking state even when a lens actuator is operated for focus control. It is in.

[0006]

According to the present invention, a condensing means for condensing a light beam on the track of an optical recording medium having a track, and the condensing means are driven along the optical axis direction. A driving means for driving the optical recording medium, and a first detection signal for detecting a positional relationship between the optical recording medium and the condensing means based on a light beam from the optical recording medium.
Detecting means, and output means for generating a drive signal for maintaining the condensing means at a predetermined position with respect to the optical recording medium based on the first detection signal and outputting the drive signal to the drive means. An optical search device is provided, comprising: a moving unit that moves the light collecting unit in a direction orthogonal to the track based on a second detection signal based on a drive signal.

Further, according to the invention, a condensing means for condensing the light beam on the track of the optical recording medium having the track, and a driving means for driving the condensing means along the optical axis direction thereof. First detecting means for detecting a positional relationship between the optical recording medium and the condensing means on the basis of a light beam from the optical recording medium to generate a first detection signal, and the first detecting means. Output means for generating a drive signal for maintaining the condensing means at a predetermined position with respect to the optical recording medium based on a detection signal and outputting the drive signal to the driving means; and a light beam from the optical recording medium. Second detection means for detecting a deviation from the track center of the optical recording medium to generate a second detection signal based on the above, and the second detection signal is corrected by referring to the drive signal, and this correction is performed. Based on the detected second detection signal Optical retrieval apparatus characterized by comprising moving means for moving in a direction perpendicular to the focusing means to the track, is provided.

Further, according to the present invention, a condensing means for condensing the light beam on the track of the optical recording medium having the track, and a driving means for driving the condensing means along the optical axis direction thereof. First detecting means for generating a first detection signal by detecting a focusing state of the light beam from the condensing means with respect to the optical recording medium based on the light beam from the optical recording medium; Second detecting means for detecting a relative position of the light collecting means with respect to the position and generating a position signal, and setting the light collecting means at a predetermined position with respect to the optical recording medium based on the first detection signal. Output means for generating a drive signal for maintaining and outputting the drive signal to the drive means;
Second detection means for detecting a deviation from the track center of the optical recording medium on the basis of a light beam from the optical recording medium to generate a third detection signal, and a position signal for the third detection signal. And moving means for moving the condensing means in a direction orthogonal to the track based on the corrected second detection signal. Provided.

Furthermore, according to the present invention, a condensing means for condensing the light beam on the track of the optical recording medium having the track, and a driving means for driving the condensing means along the optical axis direction thereof. And first detecting means for generating a first detection signal by detecting the positional relationship between the optical recording medium and the condensing means based on the light beam from the optical recording medium, and the first detecting means. Output means for generating a drive signal for maintaining the condensing means at a predetermined position with respect to the optical recording medium on the basis of the detection signal and outputting the drive signal to the drive means, and light from the optical recording medium. It has two detection areas arranged along a direction intersecting the track irradiated with the beam, and detects a deviation of the track center of the optical recording medium on the basis of a difference signal from the detection areas. To generate the detection signal of And the drive signal are input to an equivalent filter having characteristics substantially equivalent to the drive means to extract a correction signal, the correction signal is used to correct the second detection signal, and the corrected second signal is used. An optical search device is provided, comprising: a moving unit that moves the light collecting unit in a direction orthogonal to the track based on a detection signal.

Furthermore, according to the present invention, a condensing means for condensing the light beam on the track of the optical recording medium having the track, and a driving means for driving the condensing means along the optical axis direction. And first detecting means for generating a first detection signal by detecting the positional relationship between the optical recording medium and the condensing means based on the light beam from the optical recording medium, and the first detecting means. Output means for generating a drive signal for maintaining the condensing means at a predetermined position with respect to the optical recording medium on the basis of the detection signal and outputting the drive signal to the drive means, and light from the optical recording medium. It has two detection areas arranged along a direction intersecting the track irradiated with the beam, and detects a deviation from the track center of the optical recording medium on the basis of a difference signal from the detection areas. Two
Second detection means for generating the detection signal of (1) and the drive signal, after removing the low frequency component through the low frequency removal filter, are input to an equivalent filter having characteristics substantially equivalent to the drive means to extract a correction signal. Then, the second detection signal is corrected by the correction signal, and the moving means moves the light collecting means in the direction orthogonal to the track based on the corrected second detection signal. A featured optical retrieval device is provided.

[0011]

The moving position of the light collecting means is detected, or the moving position is estimated, and the offset amount generated by the shift in the tracking direction, which is the mechanical crosstalk in the tracking direction corresponding to this position, is corrected by the moving means. It Therefore, it is possible to record or reproduce a signal with high accuracy even on an optical disc with a narrowed track interval for higher density.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk device according to an embodiment of the present invention will be described in detail below with reference to the drawings. 1 is a block diagram showing a tracking control circuit of an optical disc apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram showing a schematic configuration of the optical disc apparatus of the present invention, and FIG. 3 is shown in FIG. It is a perspective view showing the structure of the optical head.

First, the overall structure of the optical disk device will be described with reference to FIG. As shown in FIG. 2, in the disk device, an optical head 3 incorporating a photodetector 8, a semiconductor laser 10 and an optical system is placed on a carriage (not shown), and a linear motor 24 is used to move the optical disk 1 in the radial direction. Is movably held. In such an optical head 3, the light beam generated from the semiconductor laser 10 is collimated by the collimator lens 11a, the optical disc 1 is rotated by the motor 1 at a constant rotation speed, and the objective lens 6 is rotated through the half prism 11b. Be guided by. This laser beam is used for this objective lens 6
Is focused on the optical disc 1. This optical disc 1
Are rotated at a constant rotation speed by the motor 2 controlled by the motor control circuit 29.

In the reproducing mode, the semiconductor laser 10 generates a reproducing laser beam having a constant light intensity, and in the recording mode, the recording laser intensity-modulated by the recording signal to a light intensity higher than that of the reproducing beam. A beam is emitted from the semiconductor laser 10. In the erase mode, the semiconductor laser 10 emits an erase laser beam having a light intensity higher than that of the reproduction beam.

From the optical disk 1, the reflected light beam is redirected to the objective lens 6, and the reflected light beam from the objective lens 6 passes through the half mirror 11b and the focus detection including the condenser lens 10a and the cylindrical lens 10b is performed. For an astigmatism detection optical system. The light beam that has passed through this detection optical system is focused on the photodetector 8 having four photodetection cells 8a, 8b, 8c, 8d by this optical system, and a light beam spot is formed on this detector 8. It Since the shape of the beam spot formed on the detector 8 changes according to the focus state of the objective lens 6, this change in beam shape is detected by the photodetector cell 8.
Focus is detected by detecting a, 8b, 8c, and 8d. Further, the tracking state of the objective lens 1, which indicates whether or not the light beam is correctly tracking the track of the optical disk 1, is because the track image is formed on the beam spot on the detector 8 The tracking state is detected by detecting with the light detection cells 8a, 8b, 8c, 8d. In the reproduction mode, the reproduction light beam is modulated when reflected by the optical disk, and the modulated light beam is incident on the photodetector 8. Therefore, the reproduction signal is added by adding the detection signals from the photodetector 8. Can occur.

The photo-detecting cells 8a, 8b, 8c and 8d are connected to the amplifiers 12a, 12b, 12c and 12d, the detection signals from the amplifiers 12a and 12c are added by the adder 30a, and also from the amplifiers 12d and 12e. Detection signals are added by the adder 30b, and the addition signals from the adders 30a and 30b are supplied to the differential amplifier OP2. Therefore, 2
A difference signal corresponding to the difference between the two added signals is generated as a focus error signal from the differential amplifier OP2, and the focus error signal is supplied to the focus control circuit 20. Further, the detection signals from the amplifiers 12a and 12d are added by the adder 30c, the detection signals from the amplifiers 12c and 12e are added by the adder 30d, and the addition signals from the adders 30c and 30d are added to the differential amplifier OP1. Is supplied to. Therefore, a difference signal corresponding to the difference between the added signals is generated as a tracking error signal from the differential amplifier OP1, and the tracking error signal is supplied to the track control circuit 21. Details of the track control circuit 21 will be described later with reference to FIG. Adders 30C and 30
The added signal from d is added by the adder 30e and supplied to the reproduced signal generator 22 as a reproduced signal.

From the focus control circuit 20, a coil drive signal for driving the focusing drive coil 5 is generated according to the focus error signal, and the objective lens 6 is driven by the focusing drive coil 5 in the optical axis direction thereof, and the objective lens 6 is driven. Are always kept in focus, and the light beam is focused on the optical disc 1 by the objective lens 6. A drive signal for driving the drive coil 4 for tracking is generated from the track control circuit 21 in accordance with the tracking error signal, and the objective lens 6 is moved in the direction orthogonal to the optical axis thereof, so that the optical disc 1 is always on the optical disc 1. Directed to the truck. Therefore, the objective lens 6 is maintained in the track state, and the light beam from the objective lens 6 is
It will track the target track.

As will be described later, a position sensor 60 for detecting the position of the objective lens 6 is provided in the vicinity of the objective lens 6, and a position signal from this position sensor 60 is given to the tracking control circuit 21 to cause the objective lens 6 to move. The tracking error signal is corrected according to the position.

When a tracking error occurs beyond the range that can be corrected by the tracking drive coil 4, it is given to the linear motor control circuit 23, and a drive signal is supplied from the linear motor control circuit 23 to the linear motor 24. The linear motor 24 is driven. Therefore, the carriage on which the optical head 3 is mounted is moved, and the carriage is finely moved. At this time, the objective lens 6 is moved so that the light beam tracks the target track by the tracking drive coil 4 in association with the fine movement of the carriage. By operating the linear motor 24 in this way, the objective lens 6 is always moved to a range in which the track error can be corrected.

The position of the carriage on which the optical head 3 is placed is detected by the position detector 25, and the position signal from the position detector 25 is used by the linear motor control circuit 23,
It is transmitted to the CPU 34 via the D / A converter 26 and the bus 32. Therefore, the CPU 34 can always recognize the position of the carriage. When accessing the target track, the CPU 34 compares the track number of the target track input from the outside with the track number of the track currently being searched, and a movement signal corresponding to the difference is sent from the CPU 34 to the D / A. The linear motor 2 is supplied to the linear motor control circuit 23 via the converter 26.
4 is driven. Therefore, at the time of access, the carriage is quickly moved and the target track is searched. At the time of this access, an access signal is sent from the CPU 34 via the D / A converter 26.
And the track control circuit 21, and the objective lens 6 is moved to the home position for focus and track operations.

In the reproducing mode, the semiconductor laser 10 is driven by the semiconductor laser 10 being driven by a reproducing drive signal having a constant level from the laser driving circuit 28, and a reproducing light beam is generated from the semiconductor laser 10 and a laser reproducing signal is generated. A reproduction signal obtained by binarizing the reproduction signal is generated from the device 22, is supplied to a data processor 27 which will be described in detail later, and is converted into reproduction data. This reproduction data is given to the CPU 34 via 32 and stored in the memory 36. In the recording mode, the recording data is supplied to the bus 32 from the system controller 38 outside the optical disk device via the interface 40, and the recording data is supplied to the data processor 27 under the control of the CPU 36. The recording data is converted into a recording signal by the data processor 27 and supplied to the laser drive circuit 28. The semiconductor laser 10 is driven by the drive signal according to the recording signal, and the semiconductor laser 10 is driven.
From, a laser beam whose intensity is modulated according to the recording signal is generated.

The optical head 3 has a structure as shown in FIG. 3 as an example. In the optical head 3 having this structure, the objective lens 6 is fixed to the movable body 50 through the lens barrel 52, and the movable body 50 is vertically moved by the four wires 57, that is, focusing and left-right directions, that is, the tracking direction. It is movably supported by. The wire 57 is connected and fixed to a substrate 58 provided on an end surface of the block 59 that extends in an insertion hole formed in the block 59 and is fixed to a base serving as the yoke 55. A pair of focus coils 5 are wound around both sides of the movable body 50, and a center yoke portion 55C of a yoke 55 is inserted into the focusing coil 5.
Further, permanent magnets 56 facing each other are fixed to the side yoke portion 55a of the yoke 55. The tracking coil 4 is fixed to the movable body facing the permanent magnet 56. The yoke 55 as a base is mounted on the carriage of the linear motor 24 (not shown) and is movable in the radial direction of the optical disc 1.

As shown in FIG. 4, on the side surface of the movable body 50,
A position sensor 60 that detects the position of the objective lens 6 is provided. The position sensor 60 is provided on the movable body 50.
A light shielding plate 59 fixed to the movable body 50 so as to move together, a detector 61 fixed to the yoke 55 as a base and having two detection regions, a light shielding plate 59, and a detector 6.
The laser diode 62 fixed to the yoke 55 is disposed so as to face the laser diode 1. The laser diode 62 is provided on the front surface of the light shield plate 58, and the detector 60 is provided on the back surface of the light shield plate 59. The light shield plate 59 is provided from the laser diode 62 to the detector 61 when the movable body 50 is moved up and down.
It is arranged so as to block the laser beam directed toward. Moreover, in the detection area of the detector 61 and the light shielding plate 59, two beam components having the same light intensity enter the detection area of the detector 59 when the objective lens 6 is in the focus state, and the objective lens 6 is in the focus state. The beam components having different light intensities are arranged so as to be incident on the two detection regions of the detector 61 when they are deviated from the above. A detection signal from the detection area of the detector 61 is supplied to a differential amplifier OP3 via an amplifier (not shown), and the difference signal is generated as a position signal indicating the position of the objective lens 6.

In the optical head having the structure shown in FIG. 4, when the focus drive current is supplied to the focusing coil 5 via the wire 57, the movable body 55 is moved substantially to the objective lens 6.
Is moved along the optical axis of and the focus is adjusted. Further, when the tracking drive current is supplied to the tracking coil 4 via the wire 57, the tracking coil 4 is moved in the tracking direction orthogonal to the optical axis of the objective lens 6 to perform tracking adjustment. Further, when the movable body 50 is moved in the focus direction during focus adjustment, the light blocking plate 59 is also moved in the focus direction, and when the objective lens 6 is in the focus state as shown in FIG. Equal detection signals are generated from the detection area of the detector 61, and a zero level position signal corresponding to the focus state is generated from the differential amplifier OP3. Further, when the light shielding plate 59 is arranged in front of one detection region of the detector 61 as shown in FIG. 5B from this focus state, different detection signals are generated from the detection region of the detector 61, A positive or negative position signal is generated from the differential amplifier OP3.

The tracking control circuit shown in FIG.
It is configured as shown in FIG. In FIG. 2, the 4-division detector 8 is shown as a 2-division detector for convenience of description.
That is, the detection areas 8a and 8d of the detector 8 are shown as the first detection area, and the detection areas 8b and 8c of the detector 8 are shown as the detection area of the second detection area. As described above, the first and second detection areas of the detector 8 are arranged parallel to the tangential direction of the track of the optical disc, and the light beam reflected from the optical disc 1 is incident on the detector. The outputs of the two-division photodetector 8 are the preamplifiers 12a, 12b, 12c, 1 of FIG.
Input to the preamplifiers 102 and 103 corresponding to 2d,
After being amplified, it is input to the differential amplifier OP1 of the tracking error signal detection circuit. The differential amplifier OP1 of the tracking error signal detection circuit subtracts the outputs of the preamplifiers 102 and 103 and outputs a tracking error signal 105. The tracking error signal 105 is input to the subtractor 106. Further, the position detector 60 detects the position of the objective lens 6 in the focusing direction. The focusing position detection signal 11 output from the position detector 60 is detected.
The gain of 2 is adjusted by the gain adjuster 113, and is input to the subtractor 106 as the tracking direction crosstalk estimation signal 114. The subtractor 106 subtracts the tracking direction crosstalk estimation signal 114 from the tracking error signal 105 and outputs a corrected tracking error signal 107 in which the offset amount generated by the shift of the lens actuator in the tracking direction due to the focusing operation is corrected. The corrected tracking error signal 107 is input to the tracking gain phase compensator 108 and the tracking power amplifier 109 to drive the tracking actuator, that is, the tracking coil 4.

The operation of such a tracking control circuit will be described with reference to FIG. FIG. 6 shows a state in which the tracking control is inactive for easy understanding. 6A is a tracking error signal output from the differential amplifier OP1 of the tracking error signal detection circuit in FIG. 1, and FIG. 6B is a focusing direction position detection output from the position detector 60 in FIG. FIG. 6C shows the tracking direction crosstalk estimation signal output from the gain adjuster 113 in FIG. 1, and FIG. 6D shows the corrected tracking error signal output from the subtractor 106 in FIG. ing. As shown in FIG. 6A, the tracking error signal is offset due to the displacement of the focusing actuator in the tracking direction (mechanical crosstalk) during the focusing operation. This offset amount is canceled by the tracking direction crosstalk estimation signal shown in FIG. 6C obtained from the focusing direction position detection signal shown in FIG.
The corrected tracking error signal d shown in (d) is output. According to the corrected tracking error signal d, it is possible to execute the correct tracking control operation in which the offset amount generated by the shift of the lens actuator in the tracking direction due to the focusing operation is corrected.

Needless to say, the same effect can be obtained by adding a coarse movement loop such as the linear motor 24 shown in FIG. As described above, the lens shift amount can be estimated by detecting the focus position even if there is a lens shift in the tracking direction due to the lens actuator driving by the focusing control, so the offset of the tracking error signal can be corrected and the track interval can be narrowed to a high level. It is possible to record or reproduce signals with high accuracy even with an optical disc having a high density. In addition, since a high-performance lens actuator is not required, an inexpensive device can be provided.

A tracking control circuit according to another embodiment of the present invention will be described with reference to FIGS. Figure 7
11 to 11, the portions denoted by the same reference numerals as those shown in FIGS. 1 to 6 indicate the same portions, and detailed description thereof will be omitted.

As shown in FIG. 7, in the optical disk device according to this embodiment, the position sensor 60 is the objective lens 6
The focus coil drive signal is supplied from the focus control circuit 20 to the tracking control circuit 21 without being provided in the vicinity.

Details of the tracking control circuit 21 are shown in FIG. In FIG. 8, reference numeral 211 indicates a focusing power amplifier of the focus control circuit 20, to which a signal from a focusing gain phase compensator (not shown) is input, and a focusing actuator, that is, the focusing coil 5 is connected. It is driven to perform follow-up control (focusing control) to shake in the width direction of the optical disk. The current flowing through the focusing coil 5 during the focusing control is detected by the current detector 213 and is input to the equivalent filter 214 simulating the mechanical characteristics of the focusing actuator to estimate the position of the focusing actuator. Here, the gain of the focusing position estimation signal 215 is adjusted by the gain adjuster 216 to become the tracking direction crosstalk estimation signal 217, which is input to the subtractor 106. The subtractor 106 is provided with a tracking error signal 105.
From the tracking direction crosstalk estimation signal 217
The corrected tracking error signal 107 from which is subtracted is output. The corrected tracking error signal 107 is input to the tracking gain phase compensator 108 and the tracking power amplifier 109, and drives the tracking actuator, that is, the tracking coil 4.

FIG. 9 shows the operation of the tracking controller circuit according to the embodiment shown in FIG. In Figure 9,
For easy understanding, the tracking control is in a non-operating state as in FIG. 9A is a tracking error signal output from the differential amplifier OP1 of the tracking error signal detection circuit, and FIG. 9B is a current detector 2
9 (c) is a focusing position estimation signal output from the equivalent filter 214, and FIG. 9 (d) is a tracking direction crosstalk estimation output from the gain adjuster 216. The signal and FIG. 9E show the corrected tracking error signal output from the subtractor 206.
The tracking error signal shown in FIG. 9A has an offset due to the displacement of the focusing actuator in the tracking direction (mechanical crosstalk) during the focusing operation. Therefore, the focusing position estimation signal shown in FIG. 9C is obtained from the focusing actuator drive current signal shown in FIG. 9B. The offset amount of the tracking error signal shown in FIG. 9A is obtained from the focusing position estimation signal shown in FIG. 9C.
This is canceled by the tracking direction crosstalk estimation signal shown in (d), and the corrected tracking error signal shown in FIG. 9 (e) is output. According to this corrected tracking error signal, as in the embodiment shown in FIG. 1, it is possible to execute a correct tracking control operation in which the offset amount caused by the shift in the tracking direction of the lens actuator due to the focusing operation is corrected.

FIG. 10 shows the configuration of a tracking control circuit according to still another embodiment of the present invention. Also,
The focusing actuator, that is, the current flowing through the focusing actuator during focusing control for driving the focusing coil 5 is detected by the current detector 213, and its cutoff frequency is at least lower than the main resonance frequency of the focusing actuator and the rotation frequency of the optical disk. After passing through the filter 314, the position of the focusing actuator is estimated by inputting it to the equivalent filter 215 which imitates the mechanical characteristics of the focusing actuator. Here, the equivalent filter 315 is based on a second-order low-pass filter in which the main resonance frequency of the actuator is the resonance frequency. The focusing position estimation signal 215 output from the equivalent filter 315 is input to the gain adjuster 216, the gain is adjusted, and the tracking direction crosstalk estimation signal 217 is input to the subtractor 106.
As described above, the subtractor 106 outputs the corrected tracking error signal 107 obtained by subtracting the tracking direction crosstalk estimation signal 217 from the tracking error signal 105. Corrected tracking error signal 107
Is input to the tracking gain phase compensator 108 and the tracking power amplifier 109 to drive the tracking actuator, that is, the tracking coil 4.

The operation of the tracking control circuit shown in FIG. 10 will be described with reference to FIG. In FIG. 11, the tracking control is in a non-operating state as in FIGS. 6 and 9 for easy understanding. FIG. 11 (a) is the same as FIG.
The tracking error signal output from the tracking error signal detection circuit 04 shown in FIG. 11B is the focusing actuator drive current signal output from the current detector 213 shown in FIG. Here, when an electrical offset is applied to the current detector 213, an offset occurs in the focusing actuator drive current signal, which is indicated by a chain line k2 in the figure. Here, k1 is a focusing actuator drive current signal in a state where no offset occurs. When the focusing actuator drive current signal k2 with the offset is directly input to the equivalent filter 215, the wavy focusing actuator position estimation signal shown in FIG. 11C is obtained.
After passing through the gain adjuster 216, the tracking direction crosstalk estimation signal becomes as shown by the wavy line m2 in FIG. 11 (d). Tracking direction crosstalk estimation signal m
When 2 is input to the subtractor 106, the corrected tracking error signal obtained is as indicated by the symbol n in FIG. 6 (e) and is not corrected correctly.

On the other hand, the focusing actuator drive current signal k2 with the offset is applied to the low-pass elimination filter 3
After passing through 14, when inputting to the equivalent filter 215,
When the solid line focusing actuator position estimation signal shown in FIG. 11 (c) is obtained and further passed through the gain adjuster 216, the tracking direction crosstalk estimation signal becomes the solid line m1 shown in FIG. 11 (d). Like If this tracking direction crosstalk estimation signal m1 is used, the corrected tracking error signal output from the subtractor 106 is correctly corrected as shown in FIG. According to this corrected tracking error signal, as in the above-described embodiment, it is possible to execute a correct tracking control operation in which the offset amount generated by the shift in the tracking direction of the lens actuator due to the focusing operation is corrected.

[0035]

As described above, according to the present invention, the lens shift amount can be estimated by the focus position estimation even if the lens shift in the tracking direction is accompanied by the driving of the lens actuator by the focusing control.
It is possible to correct the offset of the tracking error signal, and it is possible to record or reproduce the signal with high accuracy even on an optical disc with a narrowed track interval for higher density. Also, do not require high-performance lens actuators,
Since no position sensor or the like is required, an inexpensive device can be provided. Further, even if an electrical offset occurs in the focusing actuator drive current detection signal used for focus position estimation, the ossefoot of the tracking error signal can be corrected.

[Brief description of drawings]

FIG. 1 is a block diagram showing a tracking control circuit of an optical disc device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of an optical disk device incorporating the tracking control circuit shown in FIG.

FIG. 3 is a perspective view showing a structure of the optical head shown in FIG.

4 is a perspective view schematically showing the structure of a position sensor of the optical head shown in FIG.

5 is a plan view showing the operation of the position sensor shown in FIG.

6 is a waveform diagram showing a waveform of a signal in each part of the tracking control circuit shown in FIG.

FIG. 7 is a block diagram showing a schematic configuration of an optical disc device according to another embodiment of the present invention.

8 is a block diagram showing a tracking control circuit shown in FIG. 1. FIG.

9 is a waveform diagram showing a waveform of a signal in each part of the tracking control circuit shown in FIG.

FIG. 10 is a block diagram showing a tracking control circuit incorporated in an optical disc apparatus according to still another embodiment of the present invention.

11 is a waveform diagram showing a waveform of a signal in each part of the tracking control circuit shown in FIG.

FIG. 12 is a diagram showing a relationship between a lens shift and an offset of a tracking error signal.

[Explanation of symbols]

 3 ... Optical head 4 ... Tracking coil 5 ... Focus coil 6 ... Objective lens 8 ... Photodetector OP1 ... Differential amplifier 10 ... Semiconductor laser 20 ... Focus control circuit 21 ... Track control circuit 60 ... Position detector 101 ... Divided light Detectors 102, 103 ... Preamplifier 104 ... Tracking error signal detector 105 ... Tracking error signal 106 ... Subtractor 107 ... Correction tracking error signal 108 ... Tracking gain / phase compensator 109 ... Tracking power amplifier 211 ... Focusing power amplifier 213 ... Current detector 214 ... Equivalent filter 215 ... Focusing position estimation signal 216 ... Gain adjuster 217 ... Tracking direction crosstalk estimation signal 314 ... Low-pass elimination filter

Claims (6)

[Claims] 1. An optical recording medium having a track, a condensing means for condensing a light beam on the track, a driving means for driving the condensing means along an optical axis direction thereof, and the optical recording medium. Detecting the positional relationship between the optical recording medium and the condensing means based on the light beam from
And a drive signal for generating a drive signal for maintaining the light converging means at a predetermined position with respect to the optical recording medium based on the first detection signal. An optical retrieval apparatus comprising: an output unit that outputs the second detection signal to the unit; and a moving unit that moves the light-collecting unit in a direction orthogonal to the track based on a drive signal. 2. A condensing means for condensing a light beam on the track of an optical recording medium having a track, a driving means for driving the condensing means along the optical axis direction thereof, and the optical recording medium. Detecting the positional relationship between the optical recording medium and the condensing means based on the light beam from
And a drive signal for generating a drive signal for maintaining the light converging means at a predetermined position with respect to the optical recording medium based on the first detection signal. Output means for outputting to the means, second detection means for detecting a deviation from the track center of the optical recording medium based on a light beam from the optical recording medium, and generating a second detection signal, A moving unit that corrects the second detection signal with reference to the drive signal, and moves the light collecting unit in a direction orthogonal to the track based on the corrected second detection signal. Characteristic optical retrieval device. 3. An optical recording medium having a track, a condensing means for condensing a light beam on the track, a driving means for driving the condensing means along an optical axis direction thereof, and the optical recording medium. First detecting means for detecting a focusing state of the light beam from the light collecting means with respect to the optical recording medium on the basis of the light beam from the first detecting signal, and the light collecting means for the reference position. Second detecting means for detecting a relative position of the optical recording medium and generating a position signal, and a drive signal for maintaining the light collecting means at a predetermined position with respect to the optical recording medium based on the first detecting signal. An output means for generating and outputting to the driving means, and a third detection signal for detecting a deviation from the track center of the optical recording medium based on a light beam from the optical recording medium. 2 detection means, 3 is corrected by referring to the position signal, and based on the corrected second detection signal, the light condensing means is moved in a direction orthogonal to the track. Optical search device. 4. A condensing means for condensing a light beam on the track of an optical recording medium having a track, a driving means for driving the condensing means along an optical axis direction thereof, and the optical recording medium. Detecting the positional relationship between the optical recording medium and the condensing means based on the light beam from
And a drive signal for generating a drive signal for maintaining the light converging means at a predetermined position with respect to the optical recording medium based on the first detection signal. Output means for outputting to the means, and two detection areas arranged along a direction intersecting the track irradiated with the light beam from the optical recording medium, and based on a difference signal from the detection areas Second detection means for detecting a deviation of the track center of the optical recording medium to generate a second detection signal; and a correction signal by inputting a drive signal to an equivalent filter having characteristics substantially equivalent to the drive means. And correcting the second detection signal with this correction signal, and moving the condensing means in the direction orthogonal to the track based on the corrected second detection signal. Optics characterized by Search device. 5. An optical recording medium having a track, a condensing means for condensing a light beam on the track, a driving means for driving the condensing means along an optical axis direction thereof, and the optical recording medium. Detecting the positional relationship between the optical recording medium and the condensing means based on the light beam from
And a drive signal for generating a drive signal for maintaining the light converging means at a predetermined position with respect to the optical recording medium based on the first detection signal. Output means for outputting to the means, and two detection areas arranged along a direction intersecting the track irradiated with the light beam from the optical recording medium, and based on a difference signal from the detection areas Second detecting means for detecting a deviation from the track center of the optical recording medium to generate a second detecting signal; and the driving means after removing the low-frequency component of the drive signal through a low-frequency removing filter. Is input to an equivalent filter having substantially equivalent characteristics to extract a correction signal, and the correction signal
And a moving unit that moves the light collecting unit in a direction orthogonal to the track based on the corrected second detection signal. 6. The cutoff frequency of the low-pass elimination filter is
5. The optical retrieval device according to claim 4, wherein the optical retrieval device is at least lower than the main resonance frequency of the drive means and the rotation frequency of the optical recording medium.