JPH05174419A - Control method for optical pickup device - Google Patents

Abstract

PURPOSE:To eliminate an adverse effect caused by the deviation of optical axes of a fixed optical system and a movable optical system in a separation optical system type optical pickup. CONSTITUTION:A signal light beam outputted from the fixed optical system 14 is reflected on the surface of a parallel plate 23 slantingly provided at the opening part of the movable optical system 15 and the reflected light beam is received by a receiving element 30 having receiving faces bisected in the tracking direction. The deviation of optical axes of the fixed optical system 14 and the movable optical system 15 is detected based on the difference of light beam receiving signals outputted from two receiving faces of the receiving element 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises at least a moving optical system having an objective lens for focusing a laser beam on a recording medium and a moving mechanism for the objective lens, and optical elements other than the optical elements of this moving optical system. The present invention relates to a control method of an optical pickup device including a fixed optical system.

[0002]

2. Description of the Related Art Conventionally, a laser beam is focused on a recording medium in order to reduce the moving weight of an optical pickup device for recording / reproducing data on / from an optical disc or a magneto-optical disc (hereinafter collectively referred to as an optical disc). Separate the objective lens and its moving mechanism from the other optical system elements,
A so-called separated optical system type optical pickup device in which only the separated optical system elements are moved has been put into practical use.

In this separation optical system type optical pickup device, the weight of the element of the optical pickup device (hereinafter referred to as the moving optical system) that moves to access the recording area of the optical disk is small, so that it can be moved at high speed. You can
High-speed data access becomes possible.

However, the optical pickup device of such a separation optical system has the following disadvantages.

That is, for example, as shown in FIG. 9, when the moving optical system 1 is moved from the outer peripheral side (shown by a solid line) of the optical disc 2 to the inner peripheral side (shown by a chain double-dashed line), the moving optical system 1 is moved. Due to the dimensional accuracy of the seek mechanism 3 provided in the optical disk drive and the base member (not shown) of the optical disk drive device in which the optical pickup device is installed, the objective lens 4 of the moving optical system 1 and the recording surface of the optical disk 2 are caused. Varies (for example, moves upward by dimension d).

On the other hand, the height of the laser beam LB emitted from the fixed optical system 5 is always constant, and therefore, depending on whether the moving optical system 1 is located on the outer peripheral side or on the inner peripheral side. In the moving optical system 1, the position where the laser beam LB is incident on the deflection prism 6 for matching the laser beam LB with the optical axis of the objective lens 4 changes.

Here, it is assumed that the mounting position of the deflection prism 6 is adjusted so that the laser beam LB coincides with the optical axis of the objective lens 4 when the moving optical system 1 is located on the outer peripheral side. When the moving optical system 1 moves to the inner peripheral side, the incident position of the laser beam LB on the deflection prism 6 moves downward by a dimension d from a predetermined position.

As a result, the laser beam LB deflected by the deflecting prism 6 does not coincide with the optical axis of the objective lens 4, and therefore the laser beam luminous flux focused by the objective lens 4 on the recording surface of the optical disc 2 is the optical disc 2. Of the moving optical system 1 does not pass through the same optical path as the laser beam LB, and as a result, the returning light LB ′ is output from the fixed optical system 5. The laser beam LB is made to deviate by a dimension d ′ and is incident on the fixed optical system 5.

By the way, the fixed optical system 5 forms a tracking error signal representing a positioning error of the laser beam LB on the recording track of the optical disk 2, and the tracking error signal is such that the laser beam LB crosses the recording track. When the moving optical system 1 is moved in the radial direction of the optical disc 2 as shown in FIG.
It changes as shown in.

However, as described above, the moving optical system 1
When the return light LB ′ from the laser beam LB ′ is incident on the fixed optical system 5 in a manner deviated from the laser beam LB output from the fixed optical system 5, the tracking error signal has a waveform L indicated by a broken line in FIG.
As indicated by 2, the waveform L1 changes in a manner such that the offset value OF is added.

Therefore, the return light L from the moving optical system 1 is caused by a position change accompanying the movement of the moving optical system 1, or an inclination between the optical disk 2 and the moving optical system 1.
When B ′ is incident on the fixed optical system 5 in a manner shifted from the laser beam LB output from the fixed optical system 5, the offset value OF is added to the tracking error signal obtained from the fixed optical system.
Therefore, there is a problem in that the laser beam LB cannot accurately follow the recording track.

As a means for solving such inconvenience, for example, there is one disclosed in Japanese Patent Laid-Open No. 2-62729. In this device, the light flux (parallel light) of the fixed optical system is divided into two, and one light flux is returned to the fixed optical system by the reflecting plate provided in the moving optical system, and the two light receiving elements provided in the fixed optical system are used. The reflected light is received, and the optical axis shift is detected based on the difference between the light receiving signals of the two light receiving surfaces of the light receiving element. An objective lens moving mechanism or the like is installed in a direction to eliminate the detected optical axis shift. I am trying to move.

[0013]

However, in such a conventional apparatus, since the luminous flux is divided into two and used,
It is necessary to increase the output capacity of the semiconductor laser device used as a light source, which increases the price of the semiconductor laser device,
The inconvenience of increasing the device cost has occurred. Further, an optical element for splitting the signal light is required, which increases the cost of the device and hinders downsizing of the device.

The present invention has been made in order to eliminate such inconvenience, and provides a control method of an optical pickup device which can eliminate the optical axis shift between the moving optical system and the fixed optical system and can suppress the increase of the device cost. It is intended to be provided.

[0015]

According to the present invention, there is provided at least a moving optical system including an objective lens for focusing a laser beam on a recording medium and a moving mechanism for the objective lens, and an optical element other than the optical elements of the moving optical system. In the method of controlling an optical pickup device including a fixed optical system, the moving optical system is provided so as to be inclined with respect to the optical axis of the signal light output from the fixed optical system, and the signal light is incident on the movable optical system. A parallel plate made of a transparent material having a reflection film for reflecting a part of the incident light amount on its surface, and a signal light reflected by the parallel plate whose light receiving surface is divided into two in the recording track arrangement direction of the recording medium. Providing a light receiving element to receive light,
The deviation between the optical axis of the fixed optical system and the optical axis of the objective lens is detected based on the difference between the two received light signals of the light receiving element. The difference signal between the two light receiving signals of the light receiving element is added as an offset component to the tracking error signal representing the tracking error of the laser beam. Further, the difference signal between the two light receiving signals of the light receiving element is added as an offset component to the movement detection signal of the objective lens in the tracking direction. The parallel plate is also used as a cover member for the opening of the moving optical system.

Further, it comprises at least a moving optical system having an objective lens for focusing a laser beam on a recording medium and a moving mechanism for this objective lens, and a fixed optical system comprising optical elements other than the optical elements of this moving optical system. In the method of controlling the optical pickup device, the moving optical system includes
A parallel plate made of a transparent material, which is provided so as to be inclined with respect to the optical axis of the signal light output from the fixed optical system and has a reflective film provided on the incident surface of the signal light to reflect a part of the incident light amount. A light-receiving element for receiving the signal light reflected from the parallel flat plate, the light-receiving surface of which is divided into two in the recording track arrangement direction of the recording medium, and based on the difference between the two light-receiving signals of the light-receiving element The deviation between the optical axis of the optical system and the optical axis of the objective lens is detected, and the output level of the laser beam is monitored based on the sum of the two light receiving signals of the light receiving element.

[0017]

Therefore, since the deviation of the optical axis can be detected by using one light receiving element, it is possible to suppress an increase in the cost of parts of the optical system. In addition, it is possible to prevent the device from increasing in size. Further, since the optical axis shift and the output level of the laser beam can be detected by using the same light receiving element, the number of parts of the device can be further reduced, and the device can be further downsized.

[0018]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an optical disk drive device according to an embodiment of the present invention. In this case, a write-once optical disc using an optical recording medium is used as the recording medium.

In the figure, an optical disc 13 is removably attached to a turntable 12 fixed to a rotary shaft 11 of a spindle motor 10, and an optical pickup for recording / reproducing data on / from a recording surface of the optical disc 13. The device is divided into a fixed optical system 14 and a moving optical system 15. The carriage 16 of the moving optical system 15 is provided with a seek mechanism 17 for moving the moving optical system 15 in the radial direction of the optical disk 13. The guide member 18 is for guiding the moving direction of the seek mechanism 17.

Next, the optical system of this optical pickup device will be described. The optical pickup device uses a push-pull method as a tracking error detection method and a knife edge method as a focusing error detection method.

In the figure, the signal light output from the semiconductor laser element 19 is converted into parallel light by the coupling lens 20 and is incident on the polarization beam splitter 21 as P-polarized light. It is reflected by the splitter 21 and guided to the quarter-wave plate 22.

The P-polarized signal light transmitted through the quarter-wave plate 22 is converted into circularly-polarized light by the quarter-wave plate 22, and then a parallel substrate made of a transparent substrate provided in the opening of the moving optical system 15. The light passes through the flat plate 23, enters the deflecting prism 24, is reflected by the deflecting prism 24, enters the objective lens 25, is condensed by the objective lens 25, and is imaged on the recording surface of the optical disc 13.

The reflected light from the optical disk 13 passes through the objective lens 25, is converted into substantially parallel light, is reflected again by the deflecting prism 24, and is guided to the fixed optical system 14.
It is incident on the quarter-wave plate 22 again. Thereby, 1 /
The reflected light that has passed through the four-wave plate 22 is converted into linearly polarized light whose azimuth is orthogonal to that of the incident light, so that it is transmitted through the polarization beam splitter 21.

In this way, the polarization beam splitter 2
The reflected light from the optical disk 13 that has passed through 1 is reflected by the lens 2
6 is focused by 6, and about half of the light flux is reflected by the splitting mirror 27 that constitutes a knife edge, and the light receiving surface is split into two in the tracking direction (that is, the radial direction of the optical disc 13). Is incident on the light receiving element 28.

The remaining portion of the light flux focused by the lens 26 is incident on a light receiving element 29 for detecting a focusing error, the light receiving surface of which is divided by a dividing line parallel to the ridge of the dividing mirror 27. ..

Then, a tracking error signal is obtained based on the difference between the light receiving signals output from the two divided light receiving surfaces of the light receiving element 28, and the light receiving elements 29 output from the two divided light receiving surfaces of the light receiving element 29. A focusing error signal is obtained based on the signal difference. Further, a reproduction signal from the optical disc 13 is obtained based on the total sum of the light receiving signals of the light receiving element 28 and the light receiving element 29. In addition, the objective lens 2
An objective lens moving mechanism (described later) for moving the objective lens 25 in the tracking direction and the focusing direction is attached to the lens 5.

Here, in the parallel plate 23, a reflecting film for reflecting a part of the incident light is formed on the surface 23a which receives the signal light from the fixed optical system 14, and is reflected by this reflecting film. The component signal light is incident on the light receiving element 30 whose light receiving surface is divided into two in the tracking direction.

Therefore, as shown in FIG. 2 (a), the light receiving element 30 receives the incident light SP from the fixed optical system 14 reflected by the surface 23a of the parallel plate 23, and receives the respective light receiving surfaces 30a, 30a. A light receiving signal is generated from 30b. For example, when the optical axis of the moving optical system 15 is lower than the optical axis of the fixed optical system 14, as shown in FIG.
The light receiving position of the signal light at 0 goes up. As a result, the amount of light received by the light receiving surface 30a becomes larger than the amount of light received by the light receiving surface 30b.

Therefore, when the difference between the light receiving signal output from the light receiving surface 30a and the light receiving signal output from the light receiving surface 30b is calculated, this difference is generated due to the optical axis shift between the fixed optical system 14 and the moving optical system 15. The value of changes as shown in FIG.

As a result, the light receiving surface 30a of the light receiving element 30
The optical axis shift between the fixed optical system 14 and the moving optical system 15 can be detected based on the difference between the light receiving signal output from the light receiving surface 30b and the light receiving signal output from the light receiving surface 30b.

Further, in this embodiment, since the parallel plate 23 closes the opening of the moving optical system 15, it is possible to prevent dust and the like from entering the moving optical system 15. Also,
Since the parallel plate 23 is inclined with respect to the optical axis, flare light due to the surface reflection of the parallel plate 23 causes the light receiving element 2 to generate flare light.
It is possible to prevent the inconvenience that the tracking error signal and the focusing error signal are affected by being incident on the light beams 8 and 29.

4 and 5 show an example of the moving mechanism of the objective lens 25.

In the figure, a ring-shaped holder 31 is attached to the objective lens 25.
Are fixed to the upper end of a hole 33 formed in the objective lens holder 32. Further, one end of two sets of parallel leaf springs 33, 34, 35, 36 are fixed to the objective lens holder 32, and the parallel leaf springs 33, 34, 35, 3 are fixed.
The other end of 6 is fixed to the pin supporter 37.

The pin supporter 37 is provided with a pin 38 and a pin 39 at the upper and lower ends of its rotation center, and the pin 39 is inserted into a bearing member 41 attached to a housing 40. Also, the pin 38
Is a bearing member 43 attached to the holding member 42.
Has been inserted into.

The holding member 42 is fixed to a support member 44 which is raised from the housing 40, and therefore the objective lens holder 32 is positioned with respect to the housing 40 with the pins 38 and 39 of the pin supporter 37 as the center. It is rotatably attached.

The housing 40 includes an objective lens holder 3
A magnetic circuit member 49 composed of substantially U-shaped yoke members 45 and 46 sandwiching 2 and permanent magnets 47 and 48 magnetically attracted to one rising portion of the yoke members 45 and 46. , 50 are provided, and a focus coil 51 for applying a drive current interlinking the magnetic gap of the magnetic circuit members 49, 50 is provided on the side surface of the objective lens holder 32. Further, on the surface of the focus coil 51, track coils 52, 53, 54, 55 wound in a plane are attached.

Further, a hole 56 is formed on the bottom surface of the housing 40 for allowing the light flux to pass therethrough. A light emitting element 57 is attached to one side end of the pin supporter 37, and a cylindrical aperture member 58 is provided in the light emitting portion of the light emitting element 57. A light receiving element 59 that receives the light detected by the light emitting element 57 is provided in the housing 40.

Therefore, when a drive current is applied to the focus coil 51, a force corresponding to the magnitude and direction of the drive current acts on the focus coil 51, whereby a force in the focus direction acts on the objective lens holder 32. As a result, the leaf springs 33, 34, 35, 36 are deformed.

As a result, in the objective lens holder 32, the leaf springs 33, 34, 35, 36 are deformed in such a manner that the restoring force of the deformed leaf springs 33, 34, 35, 36 and the force acting on the focus coil 51 are balanced. The objective lens holder 32 is moved in the focus direction.

The track coils 52, 53, 54,
When a drive current is applied to 55, the track coils 52, 5
A force in the track direction acts on 3, 54, 55. As a result, a force in the track direction acts on the objective lens holder 32, and the pin supporter 37 rotates in the acting direction.

By thus applying the drive current to the focus coil 51 and the track coils 52 to 55, the objective lens holder 32 can be moved in the focus direction and the track direction.

As shown in FIG. 6, when the objective lens holder 32 is moved in the tracking direction,
Since the position of the spot output from the aperture member 58 and received by the two light receiving surfaces 59a and 59b of the light receiving element 59 moves in the moving direction, this light receiving element 5
The movement of the objective lens holder 32 can be detected based on the difference between the light receiving signals output from the two light receiving surfaces 59a and 59b of the light receiving device 9.

FIG. 7 shows an example of a control system of the optical disk drive.

In the figure, the light receiving surface 28 of the light receiving element 28 is shown.
The light reception signal Pa output from a is applied to the plus side input end of the subtractor 61 and the input end of the adder 62,
Light receiving signal P output from the light receiving surface 28b of the light receiving element 28
b is the minus side input end of the subtractor 61 and the adder 62
Is added to the input terminal of the light receiving surface 29 of the light receiving element 29.
The received light signal Pc output from a is applied to the plus side input end of the subtractor 63 and the input end of the adder 62,
Light receiving signal P output from the light receiving surface 29b of the light receiving element 29
d is the negative input terminal of the subtractor 63 and the adder 62
Has been added to the input end of.

The subtractor 61 subtracts the light receiving signal Pb from the light receiving signal Pa, and the subtraction result is a tracking servo control section 64 as a tracking error signal ET.
Has been added to. The subtractor 63 subtracts the light reception signal Pd from the light reception signal Pc, and the subtraction result is added to the focusing servo control unit 65 as a focusing error signal EF. The adder 62 calculates the total sum of the received light signals Pa, Pb, Pc, Pd,
The calculation result is added to the signal reproduction unit 66 as the reproduction signal RF.

The tracking servo control unit 64 forms a tracking control signal ST for changing the tracking error to 0 based on the input tracking error signal ET and optical axis deviation signal ES, and the tracking control signal ST is , Tracking coil drive 67. The tracking coil drive unit 67 supplies a drive current to the track coils 52 to 55 of the objective lens moving mechanism based on the input tracking control signal ST.

The focusing servo control unit 65 changes the focusing error to 0 on the basis of the input focusing error signal ET.
The focusing control signal SF, which forms F, is applied to the focusing coil drive unit 68. The focusing coil drive unit 68 supplies a drive current to the focus coil 51 of the objective lens moving mechanism based on the input focusing control signal SF.

The signal reproducing section 66 receives the reproduced signal RF inputted.
The data recorded on the optical disk 13 is reproduced on the basis of the above, and the reproduced data is added to the decoder 69. The decoder 69 detects and corrects the error contained in the reproduced data by using the error correction code added to the inputted reproduced data, and its output data is reproduced data as the control unit 70. Has been added to.

The encoder 71 adds a predetermined error correction code to the recording data output from the control unit 70, and the output data is added to the semiconductor laser drive control unit 72 as a recording signal. ..

The semiconductor laser drive controller 72 includes the controller 3
When the reproduction mode is set from No. 4, the semiconductor laser device 19 is driven to light at a predetermined reproduction level. When the recording mode is set by the control unit 70, the semiconductor laser device 19 is driven to light up in the recording mode based on the recording signal applied from the encoder 71. As a result, the output level of the semiconductor laser element 19 changes according to the recording data, and the recording information corresponding to the recording data is recorded on the recording track of the optical disc 13.

The position detector 73 detects the position of the moving optical system 15 moved by the seek mechanism 17, and the detection signal thereof is applied to the seek motor controller 74 as a position detection signal SP.

The light receiving signal Pe output from the light receiving surface 59a of the light receiving element 59 is added to the plus side input end of the subtractor 7, and the light receiving signal Pf output from the light receiving surface 59b of the light receiving element 59 is subtracted. It is added to the negative input terminal of the device 75. The subtractor 75 subtracts the light reception signal Pf from the light reception signal Pe, and the subtraction result is added to the adder 76 as the movement error signal EK.

The light receiving signal Pg output from the light receiving surface 30a of the light receiving element 30 is added to the plus side input end of the subtractor 77 and one input end of the adder 78, and from the light receiving surface 30b of the light receiving element 30. The output light reception signal Ph is applied to the minus side input end of the subtractor 77 and the other input end of the adder 78. The subtractor 75 receives the light reception signal Pg.
The light reception signal Ph is subtracted from the optical axis deviation signal ES.
Is added to the adder 76.

As a result, the corrected movement error signal from the adder 76 is obtained by removing the offset component contained in the movement error signal EK due to the optical axis shift between the fixed optical system 14 and the moving optical system 15. EKc is output, and the corrected movement error signal EKc is applied to the seek motor control unit 74.

The adder 78 receives the light reception signal Pg and the light reception signal Pg.
h is added, and the addition result is added to the semiconductor laser drive control section 72 as a monitor signal ES representing the output level of the semiconductor laser element 19. As a result, the semiconductor laser drive controller 72 refers to the monitor signal ES to control the magnitude of the drive signal applied to the semiconductor laser element 19.

The seek motor control unit 74 drives the seek motor 80, which is the drive source of the seek mechanism 17, so that the value of the position detection signal SP becomes the value corresponding to the target position instructed by the control unit 70. It is a thing. Further, when the value of the correction movement error signal EKc exceeds the predetermined range, the seek motor control unit 74 moves in the direction corresponding to the code,
The seek motor 77 is driven so that the seek mechanism 17 moves by a distance corresponding to the corrected movement error signal EKc.

The speed detector 81 is the spindle motor 10
Is detected, and the detection signal is applied to the spindle motor control section 82 as a speed detection signal SV.

The spindle motor control section 82 drives the spindle motor 10 so that the value of the speed detection signal SV becomes a value corresponding to the target speed instructed by the control section 70.

Further, the host interface circuit 83 is
This is for exchanging various data with a host device that uses this optical disk drive device as an external storage device.

With the above configuration, when the optical disk 13 is mounted in the optical disk drive, the spindle motor control section 8
2, the spindle motor 10 is rotated at a predetermined rotation speed, and the data recording / reproducing operation on the optical disc 13 by the optical pickup device becomes possible.

Then, when the semiconductor laser element 19 is driven at the reproduction level while the moving optical system 15 is moved to the predetermined initial position by the seek mechanism 17, the reflected light from the recording surface of the optical disk 13 is obtained and the control section 70 starts the operation of the focusing servo control unit 65. Thereby, the focusing servo control operation is performed by the focusing servo control unit 65, and the focus position of the objective lens 25 is controlled so as to coincide with the recording surface of the optical disc 13.

When the control of the focusing servo control unit 65 is locked, the control unit 70 starts the operation of the tracking servo control unit 64, and the tracking servo control operation by the tracking servo control unit 64 is thereby performed. , The laser beam follows the recording track.

When the driving of the semiconductor laser element 19 is started and signal light is output from the fixed optical system 14, effective light receiving signals Pg and Ph are obtained from the light receiving surfaces 30a and 30b of the light receiving element 30, As a result, the optical axis shift signal ES is added to the adder 76.

On the other hand, when the objective lens moving mechanism is moved in the tracking direction by the tracking servo control section 65, the position of the spot on the light receiving element 59 is moved, whereby the value of the movement error signal EK changes according to the movement amount. To do.

Therefore, the value of the correction movement error signal EKc applied to the seek motor control unit 74 is the objective lens 2
The value obtained by adding the value of the optical axis deviation caused by the movement of the moving optical system 15 to the value of the optical axis deviation caused by the movement of No. 5 is a value that reflects both optical axis deviations.

When the value of the movement error signal EK exceeds the predetermined range, the seek motor control section 74 moves the seek motor 80 according to the value of the movement error signal EK. As a result, the tilt of the optical axis that the objective lens 25 focuses on the optical disk 13 is eliminated.

In this way, the optical axis shift between the fixed optical system 14 and the moving optical system 15 is eliminated, and the light of the signal light on the recording surface of the optical disk 13 caused by the movement of the objective lens 25 in the tracking direction. It is possible to eliminate axis tilt.

Further, in the present embodiment, since the output level of the semiconductor laser element 19 is monitored by using the light receiving signal of the light receiving element 30, it is not necessary to provide this light receiving element for monitoring, and the light receiving element for monitoring is not necessary. The number of parts of the pickup device can be reduced.

FIG. 8 shows another example of the control system of the optical disk drive. In the figure, the same parts as those in FIG. 7 and the corresponding parts are designated by the same reference numerals.

In the figure, the tracking error signal ET output from the subtractor 61 is added to one input end of the adder 85, and the optical axis deviation signal ES output from the subtractor 77 is a multiplier. After being multiplied by a gain Kb of a predetermined value by 86, it is added to the other input end of the adder 85 as a tracking offset signal ETo.

As a result, the correction tracking error signal from the adder 85, in which the offset component contained in the tracking error signal ET due to the optical axis shift between the fixed optical system 14 and the moving optical system 15 is removed, is obtained. ETc is output, and the corrected tracking error signal ETc is applied to the tracking servo control unit 64.

The tracking servo control unit 64 changes the tracking error to 0 based on the input corrected tracking error signal ETc.
And the tracking control signal ST is output to the tracking coil drive unit 67.

In this case, the movement error signal EK output from the subtractor 75 is directly applied to the seek motor control section 74, whereby the seek motor control section 74.
When the value of the movement error signal EK exceeds a predetermined range, the movement error signal EK moves in the direction corresponding to the code.
So that the seek mechanism 17 moves by a distance corresponding to
The seek motor 77 is driven.

By the way, in the above-described embodiment, the present invention is applied to the optical pickup device which uses the push-pull method as the tracking error detection method and the knife edge method as the focusing error detection method, but other detection methods are used. The present invention can be similarly applied to the optical pickup device.

Further, in the above-mentioned embodiments, the present invention is applied to the optical disk device using the write-once optical disk as the recording medium, but the present invention is similarly applied to the optical disk device using other optical disks as the recording medium. can do.

[0077]

As described above, according to the present invention,
Since the deviation of the optical axis can be detected using one light receiving element, it is possible to suppress an increase in the cost of parts of the optical system. In addition, it is possible to prevent the device from increasing in size. Further, since the optical axis shift and the output level of the laser beam can be detected by using the same light receiving element, it is possible to further reduce the number of parts of the device, and thereby it is possible to further downsize the device.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an optical disk device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an example of a light receiving element.

FIG. 3 is a graph showing a relationship between a difference between received light signals obtained from two light receiving surfaces of a light receiving element and an optical axis shift.

FIG. 4 is a schematic perspective view showing an example of an objective lens moving mechanism.

FIG. 5 is a schematic sectional view showing an example of an objective lens moving mechanism.

FIG. 6 is a schematic partial view showing an example of movement detecting means in the tracking direction.

7 is a block diagram showing an example of a control system of the device shown in FIG.

FIG. 8 is a block diagram showing another example of the control system of the apparatus shown in FIG.

FIG. 9 is a schematic view for explaining the inconvenience of the separation type optical pickup device.

FIG. 10 is a waveform diagram for explaining that an offset component is generated in the tracking signal.

Claims (5)

[Claims] 1. A moving optical system including at least an objective lens for focusing a laser beam on a recording medium and a moving mechanism for the objective lens, and a fixed optical system including optical elements other than the optical elements of the moving optical system. In the control method of the optical pickup device, the moving optical system is provided to be inclined with respect to the optical axis of the signal light output from the fixed optical system, and a part of the incident light amount is incident on the incident surface of the signal light. A parallel plate made of a transparent material provided with a reflection film for reflecting and a light receiving element for receiving the signal light reflected from the parallel plate, the light receiving surface of which is divided into two in the recording track arrangement direction of the recording medium, are provided. A method of controlling an optical pickup device, characterized in that a deviation between an optical axis of the fixed optical system and an optical axis of the objective lens is detected based on a difference between two light receiving signals of a light receiving element. Law. 2. The optical pickup device according to claim 1, wherein a difference signal between two light reception signals of the light receiving element is added as an offset component to a tracking error signal representing a tracking error of the laser beam. Control method. 3. The optical pickup device according to claim 1, wherein a difference signal between two light receiving signals of the light receiving element is added as an offset component to a movement detection signal of the objective lens in the tracking direction. Control method. 4. The optical pickup device according to claim 1, wherein the parallel plate is also used as a cover member for the opening of the moving optical system. 5. A moving optical system having at least an objective lens for focusing a laser beam on a recording medium and a moving mechanism for the objective lens, and a fixed optical system including optical elements other than the optical elements of the moving optical system. In the control method of the optical pickup device, the moving optical system is provided to be inclined with respect to the optical axis of the signal light output from the fixed optical system, and a part of the incident light amount is incident on the incident surface of the signal light. A parallel plate made of a transparent material provided with a reflecting film for reflecting and a light receiving element for receiving the signal light reflected from the parallel plate whose light receiving surface is divided into two in the recording track arrangement direction of the recording medium are provided. The deviation between the optical axis of the fixed optical system and the optical axis of the objective lens is detected based on the difference between the two light receiving signals of the light receiving element, and the sum of the two light receiving signals of the light receiving element is detected. A method for controlling an optical pickup device, which comprises monitoring the output level of a laser beam based on the above.