JPH0573947A - Control system for optical disk device - Google Patents

Abstract

PURPOSE:To exactly execute a focus control or a tracking control even when the deviation of an optical axis of a moving optical part is generated by extracting a laser beam entering the moving optical part, and correcting a focus deviation value and a tracking deviation value based on the positional displacement of the extracted light. CONSTITUTION:The laser beam which is made incident on a movable optical part 2 from a fixed optical part 1 is transmitted through a beam splitter 21 and an objective laser 22, and an optical disk 3 is irradiated with the laser beam. An emitted light from the disk 3 is made incident through an inverse optical path on the optical part 1. One part of the incident beam from the optical part 1 is extracted through the beam splitter 21, received through a condenser lens 23 and a diffraction grating 24 by a light receiving device 4, and the positional displacement of the extracted light is detected. The focus deviation value and the tracking deviation value are corrected based on the detected result, and the exact focus control and tracking control can be excuted even when the deviation of the optical axis at the moving optical part is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for an optical disk device which uses an optical disk or a magneto-optical disk (hereinafter, a magneto-optical disk is also simply called an optical disk) as an information recording medium.

[0002]

2. Description of the Related Art In an optical disk device, an optical pickup device irradiates an optical disk with laser light and receives reflected light to record / reproduce information. It is detecting.

It is often practiced to configure such an optical pickup device with a fixed optical section and a moving optical section. The fixed optical unit is fixed to the device frame, emits laser light in a certain direction, receives laser light returning from the direction, and extracts various detection signals.
The moving optical unit seeks a position facing the information recording surface of the optical disc, irradiates a laser beam emitted from the fixed optical unit to a predetermined track position, and returns the reflected light to the fixed optical unit.

By the way, the astigmatism method is well known as one of the detection methods for detecting the amount of focusing deviation. In this astigmatism method, as shown in FIG. 13, the reflected light from the optical disc is received by a four-division light receiving element PD having light receiving portions A to D. Here, assuming that the detection signals of the light receiving units A to D are A to D as they are, the focus error detection signal FE indicating the amount of focussing deviation is FE = (A + B)-(C + D) (1) ,calculate.

Then, first, the apparatus is set so that the laser spot SP has a perfect circular shape as shown in FIG. 3A while the laser light is focused on the optical disk. Then, when the focus is deviated, the laser spot SP has an elliptical shape as shown in FIG. As a result, as shown by the solid line in FIG. 14, the focus error signal FE corresponding to the amount of focussing deviation is generated.
Is calculated. Then, a predetermined focus control is executed so that the calculated focus error signal FE becomes zero.

By the way, as described above, in the case of the optical disc device in which the optical pickup device is composed of the fixed optical section and the movable optical section, the optical axis shift easily occurs when the movable optical section moves.

Now, assuming that this optical axis shift occurs, for example, in the vertical direction, the laser spot SP shifts upward in each case, as shown in, for example, FIGS. Will end up. Therefore, the calculated focus error signal FE has a change in signal level as shown by a broken line in FIG. 14, and a detection error d occurs. Since the focus control is always executed so that the focus error signal FE becomes zero, in this case, the focus is deviated.

On the other hand, the amount of tracking deviation is detected 1
The push-pull method is well known as one method.
This method extracts a tracking error signal indicating a tracking deviation amount based on the two detection signals of the light receiving portions D and C of the four-division light receiving element PD.

When the tracking error signal is extracted by this method, if the optical axis shift occurs in the horizontal direction in FIG. 13, the laser spot SP also shifts in the same direction. Then,
A level difference occurs between the detection signals of the light receiving sections D and C, and an error occurs in the tracking error signal. Therefore,
Tracking control could not be executed correctly.

[0010]

As described above, conventionally, there has been a problem that focusing control and tracking control cannot be correctly executed due to the optical axis shift of the moving optical unit.

An object of the present invention is to provide a control system for an optical disc device which can explain the above-mentioned problems and can correctly execute focus control and tracking control even if the optical axis of the moving optical unit is deviated. And

[0012]

To this end, according to one invention of the present application, a part of the laser beam incident on the moving optical unit is extracted and emitted in a fixed direction, and the emitted laser beam is received. Then, the displacement of the light receiving position is detected, the detected focus shift amount is corrected according to the shift, and predetermined focus control is executed based on the corrected focus shift amount.

In another aspect of the invention, the detected tracking deviation is corrected according to the displacement of the light receiving position, and predetermined tracking control is executed based on the corrected tracking deviation. I have to.

[0014]

Since the displacement of the light receiving position when receiving the emitted laser light depends on the optical axis shift, the focus and tracking detection errors due to the optical axis shift are corrected. As a result, even if the optical axis shift of the moving optical unit occurs,
Focusing control and tracking control can be performed correctly.

[0015]

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

FIG. 1 is a schematic block diagram of an optical disk device according to a first embodiment of the present invention. In the figure, the fixed optical unit 1 is fixed to a device frame (not shown), and the movable optical unit 2 is arranged below the optical disc 3 so as to slide in the radial direction of the disc. Further, the light receiver 4 is arranged along the moving direction of the moving optical unit 2. The fixed optical unit 1 and the movable optical unit 2 form an optical pickup device. The optical pickup device irradiates a predetermined track position on the optical disc 3 with a laser beam to record / reproduce information.

In the fixed optical section 1, the semiconductor laser 1
The laser light emitted from the beam No. 1 enters the beam splitter 13 via the collimator lens 12. The incident light is reflected in the beam splitter 13 and the moving optical unit 2
Incident on. On the other hand, the laser light returning from the moving optical unit 2 passes through the beam splitter 13 and the detection lens 1
It is incident on the four-division light receiving element PD via 4 and the cylindrical lens 15. The four-divided light receiving element PD is for detecting the deviation of focusing and tracking.

Although not shown, the fixed optical section 1 is provided with a light receiving section for reading recorded information on the optical disk 3 in addition to the above.

FIG. 2 shows a schematic structure of the moving optical unit 2. The laser light emitted from the fixed optical unit 1 enters a beam splitter 21. A part of the incident light is reflected by one reflection surface 21a, and the other part is transmitted as it is. The transmitted laser light is totally reflected by the other reflecting surface 21b and is radiated to the optical disc 3 through the objective lens 22. The reflected light returns through the objective lens 22 and the beam splitter 21 on the opposite path and enters the fixed optical unit 1.

On the other hand, the part of the laser light reflected by the reflecting surface 21a enters the diffraction grating 24 through the condenser lens 23. The incident laser light is split into a plurality of beams and enters the light receiver 4.

The light receiver 4 includes five elongated light receiving elements 4a to 4a.
4e are arranged vertically along the moving direction of the moving optical unit 2. Each of the two light receiving elements 4a, 4b, 4d and 4e on both sides of the five is provided with one signal output terminal, and outputs a detection signal proportional to the amount of received laser light from each terminal. On the other hand, the light receiving element 4c at the center is a semiconductor position detecting element and has signal output terminals at both ends. Then, from each terminal, a higher level detection signal is output as the distance from the terminal to the light receiving position of the laser light becomes shorter.

FIG. 3 shows a control circuit of the magnetic disk device of this embodiment. In the figure, the four-divided light receiving element PD has light receiving portions A to D, the detection signals of the light receiving portions A and B are input to the adding circuit 101, and the detection signals of the light receiving portions C and D are input to the adding circuit 102. It has been entered. Adder circuit 1
The output of 01 is input to the + side terminal of the subtraction circuit 103,
The output of the adding circuit 102 is input to the-side terminal.

The detection signals of the light receiving elements 4a and 4d of the light receiver 4 are input to the adding circuit 104, and the detection signals of the light receiving elements 4b and 4e are input to the adding circuit 105. The output of the addition circuit 104 is input to the + side terminal of the subtraction circuit 106, and the output of the addition circuit 105 is input to the − side terminal. The output of the subtraction circuit 106 is the constant circuit 1
It is inputted to the minus side terminal of the subtraction circuit 108 via 07. The output of the subtraction circuit 103 is the + of the subtraction circuit 108.
It is input to the side terminal and the output of the subtraction circuit 108 is input to the focus control circuit 109.

The detection signal of one output terminal of the light receiving element 4c of the light receiving device 4 is supplied to the + side terminal of the subtraction circuit 110 and the addition circuit 1
The detection signal of the other output terminal is input to the minus terminal of the subtraction circuit 110 and the other terminal of the addition circuit 111.

The output of the subtraction circuit 110 is input to the seek control circuit 112, and the output of the addition circuit 111 is input to the laser emission light amount adjustment circuit 113.

When the optical disk device of this embodiment having the above-described structure starts operating, the semiconductor laser 11 first emits laser light. As a result, the information recording surface of the optical disc 3 is irradiated with the laser light, and the reflected light from the optical disc 3 is received by the four-division light receiving element PD.

Now, for example, it is assumed that the moving optical unit 2 is located at the outermost periphery of the optical disc 3. In this example,
At this time, the optical axis of the reflected light is adjusted so that there is no deviation. As a result, as shown in FIGS. 13A to 13C, the laser spot SP is irradiated to the center of the four-division light receiving element PD, and its shape changes depending on the focus state of the laser light with which the optical disc 3 is irradiated. Come to do.

The adder circuit 101 outputs the sum signal of the detection signals of the light receiving units A and B, and the addition circuit 102 outputs the sum signal of the detection signals of the light receiving units C and D. Then, the subtraction circuit 103 outputs the difference between the two sum signals, that is, the focus error signal FE according to the above-described expression (1).

On the other hand, part of the emitted light is also applied to the light receiver 4. In this case, the diffraction grating 24 separates the incident laser light into a plurality of beams by the diffraction action and irradiates the light receiver 4 with the beams.

In this embodiment, when the moving optical unit 2 is located at the outermost periphery of the optical disc 3, the 0-dimensional laser beam B0 separated by the diffraction grating 24 is emitted as shown in FIG. It is set so as to enter the light receiving element 4c.
The + 1-dimensional laser beam + B1 is incident on the boundary between the light receiving elements 4a and 4b, and the -1 dimensional laser beam -B1 is incident on the boundary between the light receiving elements 4d and 4e.
The arrangement positions of the respective parts are set so that 0 and ± B1 are located at the left end of the light receiver 4.

The adder circuit 104 adds the detection signals of the light receiving elements 4a and 4d, and the adder circuit 105 adds the detection signals.
And the detection signals of 4e are added. Then, the subtraction circuit 10
Reference numeral 6 denotes the difference between the two added signals and the optical axis deviation detection signal S
Output as E. The constant circuit 107 multiplies the optical axis shift detection signal SE by a constant and outputs it as a correction signal FC.

Now, since the respective detection signals of the respective light receiving elements 4a, 4b, 4d and 4e have the same level,
Each signal output of the subtraction circuit 106 and the constant circuit 107 becomes zero.

Therefore, the subtraction circuit 108 receives the focus error signal FE and outputs it as it is. The focus error signal FE is a signal indicating a focus shift as shown by the solid line in FIG. The focus control circuit 109 inputs the focus error signal FE, and moves the objective lens 22 by an actuator (not shown) so that the signal value becomes zero. This allows
The focus of the laser light is adjusted and the four-division light receiving element P
The laser spot of D is, as shown in (a) of FIG.
It becomes a perfect circle.

The seek control circuit 112 drives seek optical control of the optical disk 3, that is, drives the moving optical section 2 to a predetermined track position for recording / reproducing information. Now, if the moving optical unit 2 is moved by this seek operation, the incident position of the laser beam B0 on the light receiving element 4c is moved.
The light receiving element 4c outputs a detection signal proportional to the proximity of the incident position of the laser beam B0 from two detection signal output terminals located at both ends. The subtraction circuit 110 outputs a signal obtained by subtracting the detection signal of the other terminal from the detection signal of the one terminal as the position signal S. As a result, the position signal S becomes a signal that linearly changes according to the seek position of the moving optical unit 2, as shown in FIG. The seek control circuit 112 executes seek control while detecting the seek position of the moving optical unit 2 based on the position signal S.

Now, it is assumed that the optical axis shift occurs in the vertical direction as the moving optical unit 2 moves due to, for example, the shift of the fixed position of the sliding mechanism of the moving optical unit 2. In this case, as shown in (a) to (c) of FIG. 15, the laser spot SP position of the four-division light receiving element PD is deviated from the center. As a result, the focus error signal F
As described with reference to FIG. 14, a detection error d occurs at E.
This detection error d is proportional to the magnitude of the optical axis shift, as shown in FIG.

On the other hand, when such an optical axis shift occurs in the vertical method, the laser beam incident on the photodetector 4 is also changed in the vertical direction by the laser beams B0 and ± B1 as shown in FIG. 4B. Is displaced to. Then, the signal levels of the detection signals of the light receiving elements 4a and 4b and 4d and 4e differ, and a signal difference occurs between the outputs of the adder circuits 104 and 105. As shown in FIG. 7, the subtraction circuit 106 outputs the signal difference as an optical axis shift detection signal SE. The constant circuit 107 multiplies the optical axis shift detection signal SE by a fixed constant to obtain the detection error d.
Then, the level is converted into a correction signal FC having the same level as that of and output. The subtraction circuit 108 outputs a signal obtained by subtracting the correction signal FC from the focus error signal FE. This allows
The error d of the focus error signal FE will be canceled.

The focus control circuit 109 executes a predetermined focus control based on the focus error signal FE in which the error d is canceled so that the signal value becomes zero. In this case, when focus control is executed, FIG.
As shown in (a), the laser spot deviates from the center position of the four-division light receiving element PD, but the laser spot is adjusted to have a perfect circular shape, that is, to have a correct focus.

By the way, during each of the above operations, the adder circuit 11
1 outputs the sum of the detection signals output from both ends of the light receiving element 4c as the light amount detection signal P. The signal level of the light amount detection signal P is not affected by the incident position of the laser beam B0 and becomes a signal proportional to the emitted light amount of the semiconductor laser 11. The laser emission light amount adjustment circuit 113 adjusts the emission light amount of the semiconductor laser 11 so that the light amount detection signal P becomes a preset constant value.

As described above, in this embodiment, the optical axis shift in the vertical direction is detected, and the detection error of the focus error signal FE caused by the optical axis shift is corrected by the detection result. Even if the optical axis shift of the optical unit occurs, the focusing control can be correctly executed.

Further, since a part of the emitted light of the semiconductor laser 11 is detected by the light receiving element 4c of the light receiver 4 to detect the seek position of the moving optical unit 2, another light source for position detection or another light source is used. The seek position can be detected with a simple configuration without requiring a device.

Further, since the amount of emitted light of the semiconductor laser 11 is adjusted based on the amount of light received by the light receiving element 4c, the amount of emitted light can be adjusted without using a special semiconductor laser element having a built-in light receiving element. Can be adjusted. Further, in this case, since the laser beam after passing through the various optical components is detected, it is possible to prevent the light amount from being lower than the target value due to contamination of the optical components.

Further, when the light receiver 4 receives the laser light, it receives both the + 1-dimensional and -1 dimensional laser beams separated by the diffraction grating 24, so that a large detection signal can be obtained even with a small amount of light. can get.

When a detection signal having a sufficient signal level can be obtained by only one of the + 1-dimensional and -1 dimensional laser beams, as shown in FIG.
4e may be removed and the detection signals of the light receiving elements 4a and 4b may be directly input to the subtraction circuit 106.

Next, a second embodiment of the present invention will be described.

It is assumed that the optical disk device of this embodiment does not have the light receiver 4 shown in FIG. 1 but has the same structure as that of FIG.

FIG. 9 shows a schematic structure of the moving optical unit 2 of this embodiment. That is, in this embodiment, the laser light emitted from the fixed optical unit 1 enters the beam splitter 25 and is separated into straight light and reflected light. The reflected light is applied to the optical disc 3 via the objective lens 22, and the reflected light from the optical disc 3 is reflected by the beam splitter 2
The light is reflected again at 5 and returns to the fixed optical unit 1. Further, the straight-ahead light in the beam splitter 25 is incident on the light receiver 26 via the condenser lens 23 and the diffraction grating 24.

The light receiver 26 comprises five light receiving elements 26a-2a.
6e are arranged vertically, and each of the light receiving elements 26a to 26e outputs a detection signal of a level proportional to the amount of received light.

FIG. 10 shows the control circuit of the present embodiment.
4 is a view showing a part different from FIG. 3. That is, the detection signals of the light receiving elements 26a and 26d are input to the adding circuit 104, and the detection signals of the light receiving elements 26b and 26e are input to the adding circuit 105. In addition, the detection signal of the light receiving element 26c is directly input to the laser emission light amount adjustment circuit 113 as the light amount detection signal P.

With the above configuration, when the optical disk device of the present embodiment records / reproduces information on / from the optical disk 3, the semiconductor laser 11 emits laser light. The emitted laser light is applied to the optical disc 3, while a part of the laser light is separated into a plurality of beams by the diffraction grating 24 and applied to the light receiver 26.

Now, for example, it is assumed that the moving optical unit 2 is located at the outermost circumference of the optical disc 3. This optical disk device is set in a state where there is no optical axis shift at this position, as in the above-described embodiment. So in this case,
Focus error signal F without error from subtraction circuit 103
E is output.

In this case, in this embodiment, as shown in FIG. 11A, the 0-dimensional laser beam B0 separated by the diffraction grating 24 is incident on the light receiving element 26c,
+ 1-dimensional laser beam + B1 is received by the light receiving elements 26a and 2
Incident on the boundary with 6b, and -1 dimensional laser beam-B1
The arrangement positions of the respective parts are set so that the light enters the boundary between the light receiving elements 26d and 26e.

The adder circuit 104 includes the light receiving elements 26a and 26a.
The detection signals of d are added, and the addition circuit 105 adds the detection signals of the light receiving elements 26b and 26e. Then, as in the above-described embodiment, the subtraction circuit 106 outputs the difference signal between the two as the optical axis deviation detection signal SE, and the constant circuit 107.
Outputs the correction signal FC.

In this case, each of the light receiving elements 26a, 26b, 2
Since the detection signals 6d and 26e have the same level, the correction signal FC also becomes zero. As a result, the focus control circuit 109 causes the focus error signal FE
Based on the above, the predetermined focus control is correctly executed.

Next, it is assumed that the moving optical unit 2 is moved by the seek operation, and the optical axis is displaced in the vertical direction during this movement. Then, the detection error d as shown in FIG. 6 occurs in the focus error signal FE.

Further, in this case, the incident position of the laser beam on the photodetector 26 moves in the vertical direction as shown in FIG. 11B, for example. Then, a level difference occurs between the detection signals of the light receiving elements 26a, 26b, 26d, and 26e, and the subtraction circuit 106 outputs the optical axis shift detection signal SE according to the level difference.

Then, as in the above-described embodiment, the constant circuit 107 converts the optical axis shift detection signal SE into the correction signal FC, and the subtraction circuit 108 receives the focus error signal FE.
The detection error d is corrected by the correction signal FC. The focus control circuit 109 executes predetermined focus control according to the corrected focus error signal FE. Thereby, even if the optical axis shift occurs, accurate focus control can be executed. On the other hand, the light receiving element 26c outputs a detection signal of a level according to the amount of received light. The laser emission light amount adjustment circuit 113 controls the emission light amount of the semiconductor laser 11 so that the detection signal becomes a constant level. As a result, the amount of light emitted from the semiconductor laser 11 is adjusted to a constant amount.

The light receiver 26 is composed of the light receiving elements 26d and 2d.
6e may be removed and the detection signals of the light receiving elements 26a and 26b may be directly input to the subtraction circuit 106, as in the light receiver 4 in the embodiment of FIG.

Next, a third embodiment of the present invention will be described.

It is assumed that the optical disk device of this embodiment does not have the light receiver 4 shown in FIG. 1 but has the same structure as that of FIG. In addition, the moving optical unit 2 has the same configuration as in FIG. 9, and rotates the light receiver 26 by 90 degrees and fixes it. Then, as shown in FIG. 12, the control circuit inputs the detection signal of the light receiving element D of the four-division light receiving element PD to the + side terminal of the subtraction circuit 114,
The detection signal of the light receiving element C is input to the-side terminal. Note that this circuit is a known tracking error detection circuit by the push-pull method. Then, the output of the subtraction circuit 114 is input to the + side terminal of the subtraction circuit 115.

On the other hand, the control circuit shown in FIG. 10 and the constant circuit 107 shown in FIG. 3 are provided, and the output of the constant circuit 107 is input to the minus side terminal of the subtraction circuit 115. Then, the output of the subtraction circuit 115 is input to the tracking control circuit 116.

With this structure, for example, the moving optical unit 2
Is at the outermost peripheral position of the optical disc 3, and at this time, the optical axis is not displaced. in this case,
When the tracking is correct, the laser spot is irradiated to the center of the four-division light receiving element PD, and when the tracking is deviated, the laser spot moves in the horizontal direction in the figure.
Therefore, if the tracking is deviated, a level difference occurs between the detection signals of the light receiving elements C and D. The subtraction circuit 114 outputs the difference signal as a tracking error signal TE.

On the other hand, at this time, it is assumed that the incident position of the laser beam on the light receiver 26 is set to the reference position as shown in FIG. 11 (a). However, in the present embodiment, the light receiver 26 is rotated by 90 degrees with respect to FIG.

In this case, the correction signal FC output from the constant circuit 107 becomes zero. Therefore, the tracking error signal TE is directly input to the tracking control circuit 116 via the subtraction circuit 115. The tracking control circuit 116 executes predetermined tracking control so that the tracking error signal TE becomes zero. As a result, correct tracking control is executed.

Next, it is assumed that the moving optical section 2 performs a seek operation and an optical axis shift occurs in the horizontal direction during this operation. When this optical axis shift occurs, the position of the laser spot incident on the four-division light receiving element PD also moves in the horizontal direction, and a detection error occurs in the tracking error signal TE. This detection error is proportional to the shift amount of the optical axis shift.

On the other hand, the laser beam incident on the photodetector 26 also moves in the horizontal direction due to the deviation of the optical axis. As a result, the optical axis shift detection signal SE is obtained in the same manner as in the above-described embodiment.
Is output, and the correction signal FC is further output.

The subtraction circuit 115 corrects the tracking error signal TE with the correction signal FC. As a result, the detection error of the tracking error signal TE is canceled. The tracking control circuit 116 executes predetermined tracking control based on the corrected tracking error signal TE. As a result, even if the optical axis shift occurs, the tracking control will be correctly executed.

In the above embodiment, the moving optical unit 2 is
Although the configuration is basically the same as that shown in FIG. 9, the configuration shown in FIG. 2 is basically used, and the condenser lens 23, the diffraction grating 24, and the light receiver 4 are arranged directly below the beam splitter 21, and the fixed optical unit is provided. 1
Even if a part of the incident light from is reflected right below, the same control can be performed and the same effect can be obtained.

In each of the above embodiments, the moving optical unit 2
Although the optical axis is set so as not to be displaced at the outermost position, it is needless to say that the same setting may be made at the innermost position.

Further, in the above-mentioned first and second embodiments, the focus error signal FE is corrected with respect to the optical axis deviation in the vertical direction, but the method shown in the third embodiment is used. The focus error signal FE may be similarly corrected by detecting the optical axis shift of the horizontal method.

[0070]

As described above, according to the present invention, a part of the laser beam incident on the moving optical section is extracted, the displacement of the laser beam with respect to the optical axis is detected, and the detection is performed according to the displacement. Since the predetermined focus control and predetermined tracking control are executed by correcting the focus shift amount and the tracking shift amount that are generated, even if the optical axis shift of the moving optical unit occurs, focusing control and tracking control are performed. Will be able to run correctly.

[Brief description of drawings]

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

FIG. 2 is a schematic configuration diagram of a moving optical unit.

FIG. 3 is a circuit configuration diagram of a control circuit.

FIG. 4 is an explanatory diagram of a laser beam receiving state of a light receiver.

FIG. 5 is a graph showing a change of a position signal with respect to a seek position.

FIG. 6 is a graph showing a change in a detection error with respect to an optical axis shift.

FIG. 7 is a graph showing a change in an optical axis shift detection signal with respect to an optical axis shift.

FIG. 8 is a circuit configuration diagram showing another embodiment of the control circuit in which the light receiver is changed.

FIG. 9 is a schematic configuration diagram of a moving optical unit of an optical disc device according to a second embodiment of the present invention.

FIG. 10 is a circuit configuration diagram of a control circuit in the embodiment.

FIG. 11 is an explanatory diagram of a laser beam receiving state of the light receiver in the above-described embodiment.

FIG. 12 is a schematic configuration diagram of a moving optical unit of an optical disc device according to a third embodiment of the present invention.

FIG. 13 is an explanatory diagram showing a light receiving state of a four-division light receiving element when there is no optical axis shift.

FIG. 14 is a graph showing a change in focus error signal with respect to a focus shift.

FIG. 15 is an explanatory diagram showing a light receiving state of a four-division light receiving element when there is an optical axis shift.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fixed optical part 2 Moving optical part 3 Optical disk 4,26 Light receiver 4a-4c, 26a-26e Light receiving element 11 Semiconductor laser 12 Collimating lens 13,21,25 Beam splitter 14 Detection lens 15 Cylindrical lens 21a Reflective surface 22 Objective lens 23 Condenser lens 26 Diffraction grating 101, 102, 104, 105, 111 Adder circuit 103, 106, 108, 110, 114, 115 Subtractor circuit 107 Constant circuit 109 Focus control circuit 112 Seek control circuit 113 Laser emission light amount adjustment circuit 116 Tracking control Circuit PD 4-division photo detector

Claims (4)

[Claims] 1. A fixed optical unit which is fixed to an apparatus and which emits a laser beam and detects a focus shift amount of the laser beam which is incident on the optical disc by irradiating the laser beam to the optical disc, and which slides in a radial direction of the optical disc. A moving optical unit that receives the laser light emitted from the fixed optical unit, irradiates the optical disc on the optical disc, and returns the reflected light to the fixed optical unit, and if an optical axis shift occurs when the moving optical unit slides. In a control method of an optical disc device in which an error occurs in the detected focus shift amount, a laser light emitting unit that extracts a part of the laser light incident on the moving optical unit and emits the laser light in a fixed direction, and the emitted laser light Laser light displacement detection means for receiving light and detecting the displacement of the light receiving position, and correcting the focus shift amount detected according to the detected displacement of the light receiving position. A control system for an optical disk device, comprising: a correction unit that adjusts the focus of the laser light that is irradiated onto the optical disk based on the corrected displacement amount. 2. A laser beam splitting unit for splitting the laser beam emitted by the laser beam emitting unit into a plurality of beams by a diffracting action, a light amount detecting unit for receiving a 0-dimensional beam and detecting its light amount, and a detecting unit. On the other hand, the laser light displacement detecting means receives the separated ± 1 dimensional beam, and adjusts the light quantity of the laser light emitted from the fixed optical section based on the light quantity. The displacement of the light receiving position of the beam is detected.
A control method of the optical disk device described. 3. The laser light emitting means emits the extracted laser light in a direction perpendicular to the optical axis of the laser light emitted from the fixed optical section, while emitting the emitted laser light in the device. 2. The control of the optical disk device according to claim 1, further comprising a light receiving means for receiving light at a fixed position, and means for detecting the moving position of the moving optical system based on the position where the light receiving means receives the laser light. method. 4. A fixed optical unit fixed to a device for emitting a laser beam, receiving a laser beam reflected from an optical disc, and detecting a tracking deviation amount of the laser beam applied to the optical disc, and a fixed optical unit sliding in a radial direction of the optical disc. A moving optical unit that moves and irradiates a laser beam from the fixed optical unit to the optical disc and returns the reflected light to the fixed optical unit, and when an optical axis shift occurs when the moving optical unit slides. In a control method of an optical disc device in which an error occurs in the detected tracking deviation amount, a laser light emitting unit that extracts a part of the laser light incident on the moving optical unit and emits the laser light in a certain direction, and the emitted laser light emitting unit. Laser light displacement detection means for receiving a laser beam and detecting the displacement of the light receiving position, and the tracking deviation detected according to the detected displacement of the light receiving position. A control method for an optical disk device, comprising: a correction unit that corrects the amount and a control unit that executes tracking control of the laser light with which the optical disk is irradiated, based on the corrected displacement amount.