JPH10106012A - Lens spherical aberration correcting method for optical disk device and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct lens spherical aberration caused by a temp. change and to stably write/read information even on a high recording density optical disk by providing a driving means driving at least one side between a laser beam source and a coupling lens in the optical axial direction and the control part of the driving means. SOLUTION: This device is constituted so that at least one side between a laser beam source assembly body 4 and the coupling lens 11 is driven in the optical axial direction so that a level becomes maximum, or the jitter or an error rate becomes minimum among the level, jitter and error rate of an HF signal obtained from an output signal of a detector in the laser beam source assembly body 4. The driving means is provided with a guide 13, a screw rod driving means 16, etc. The control part 18 performs the above decision from the output signal of the photodetector, and drives the driving means to the prescribed position according to the decision result, and drives the driving means so as to correct the spherical aberration of an objective lens 10 from the output signal of the photodetector after being driven.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of guiding light emitted from a laser light source to an objective lens through a coupling lens, and collecting the light as a light spot on the information recording surface of the optical disk through the transparent substrate of the optical disk. A method for correcting the lens spherical aberration of an optical disc device for receiving light reflected from the information recording surface with a photodetector and outputting a signal, and emitting light from a laser light source to an objective lens via a coupling lens The objective lens converges as a light spot on the information recording surface of the optical disk through the transparent substrate of the optical disk by the objective lens, receives light reflected from the information recording surface with a photodetector, outputs a signal, and outputs a signal. The present invention relates to an optical disk device corresponding to a plurality of optical disks having different thicknesses.

[0002]

2. Description of the Related Art A CD is used as a recording medium of an optical disc device.
(Compact disc), DVD (Digital video disc)
Etc. In these CDs and DVDs, an information recording surface is formed on an optically transparent substrate such as polycarbonate, and data reading and writing are performed through the transparent substrate.

The thickness of the transparent substrate of a CD is 1.2 mm, while the thickness of the transparent substrate of a DVD is 0.6 mm, which is half that of the transparent substrate of a CD. Furthermore, on the recording surface, the CD track pitch is 1.6 μm and the shortest pit length is 0.83 μm, while the DVD
Has a track pitch of 0.74 μm and a minimum pit length of 0.4 μm.
Density is reduced to less than half of D.

In recent years, in optical disk devices,
Optical resins are often used for objective lenses and the like.

[0005]

However, optical resin has a large change in refractive index due to a change in temperature, and therefore a large change in spherical aberration, as compared with optical glass.

When the spherical aberration increases, the spot diameter of the light spot focused on the information recording surface increases, the spot peak intensity decreases, and the side lobe increases. Due to such deterioration of the light spot, at the time of reading information, the read signal level decreases, jitter increases, crosstalk from adjacent tracks increases, and as a result, the error rate increases. In addition, at the time of writing information, the diameter of the recording mark increases, and the recording sensitivity decreases.

[0007] These phenomena are more likely to occur in a DVD having a narrow track pitch and a short pit length than in a CD. It is an object of the present invention to provide a method for correcting a lens spherical aberration of an optical disk device that corrects a lens spherical aberration caused by a temperature change, and an optical disk device that corrects a lens spherical aberration generated by a temperature change.

[0008]

According to a first aspect of the present invention, light emitted from a laser light source is guided to an objective lens via a coupling lens, and the objective lens passes through the transparent substrate of the optical disk. A lens spherical aberration correction method for an optical disc apparatus, wherein a light spot is focused on an information recording surface of an optical disc as a light spot, reflected light from the information recording face is received by a photodetector, and a signal is output. From the output signal of the HF signal level, HF signal jitter, of the error rate, the HF signal level is maximized, or the HF signal jitter or error rate is minimized, the laser light source, A method for correcting a lens spherical aberration of an optical disc device, wherein at least one of the coupling lenses is driven in an optical axis direction.

HF signal obtained from the output signal of the photodetector
(Signal information recorded on the optical disk) Laser light source and coupling lens so that the HF signal level among the levels, HF signal jitters, and error rates is maximized, or the HF signal jitter or error rate is minimized. When at least one of them is driven in the optical axis direction, the lens spherical aberration caused by the temperature change is corrected.

[0010] A plurality of HF signal levels, HF signal jitters, and error rates obtained from the output signal of the photodetector may be used. At this time, if the position of the laser light source and the coupling lens at which the HF signal level is the maximum is different from the position of the laser light source and the coupling lens at which the HF signal jitter and the error rate are the minimum, when there is an error rate, It is preferable to perform the measurement at the error rate, and when there is no error rate, the measurement is performed at the HF signal jitter.

According to a second aspect of the present invention, light emitted from a laser light source is guided to an objective lens via a coupling lens, and is collected as a light spot on the information recording surface of the optical disk through the transparent substrate of the optical disk by the objective lens. A method for correcting the spherical aberration of a lens of an optical disc device, wherein the light is reflected by the photodetector, and the reflected light from the information recording surface is output by a photodetector. Provide a table in which the relationship is recorded, detect the temperature near the objective lens, determine the position of the coupling lens, the laser light source from the table, the laser light source, at least of the coupling lens A method of correcting spherical aberration of a lens of an optical disk device, characterized in that one of them is driven in an optical axis direction.

The temperature near the objective lens is detected, the positions of the coupling lens and the laser light source are determined from the table,
When at least one of the laser light source and the coupling lens is driven in the optical axis direction, lens spherical aberration caused by a temperature change is corrected.

According to a third aspect of the present invention, light emitted from a laser light source is guided to an objective lens via a coupling lens, and the objective lens collects a light spot on an information recording surface of the optical disk through a transparent substrate of the optical disk. An optical disc device corresponding to a plurality of optical discs having different thicknesses of transparent substrates, wherein the laser light source and the coupling lens are provided. Driving means for driving at least one of them in the optical axis direction, and judging the optical disk from an output signal of the photodetector, driving the driving means to a preset position according to the judgment result, and driving A control unit that drives the driving unit so as to correct a spherical aberration of the objective lens from a later output signal of the photodetector. Optical disc device.

First, since the optical disk device of the present invention is a device that can handle a plurality of optical disks, it is determined which type of optical disk is set in the optical disk device.

As a method for making the determination, there are the following methods, but the method is not limited. (1) The control unit drives the driving unit to move at least one of the laser light source and the coupling lens to the position for the first optical disk. Then, the optical disk is irradiated with a laser beam, and reflected light from the information recording surface of the optical disk is received by a photodetector. Depending on the signal output level of the photodetector,
It is determined whether the set optical disk is the first optical disk. And if it is not the first optical disc,
At least one of the laser light source and the coupling lens is moved to another optical disk position.

(2) First, the control unit drives the driving unit to move at least one of the laser light source and the coupling lens to the initial position. Then, the optical disk is irradiated with a laser beam, and reflected light from the information recording surface of the optical disk is received by a photodetector. Depending on the signal output level of the photodetector,
The type of the set optical disk is determined, and at least one of the laser light source and the coupling lens is moved to a position set in advance according to the determined type of the optical disk.

After the movement, the control unit drives the driving means so as to correct the spherical aberration of the objective lens from the output signal of the photodetector, and moves at least one of the laser light source and the coupling lens in the optical axis direction. .

According to the above configuration, after the movement, the control unit drives the driving means so as to correct the spherical aberration of the objective lens from the output signal of the photodetector, and the control unit controls the laser light source and the coupling lens. By moving at least one in the direction of the optical axis, the spherical aberration of the objective lens caused by a change in temperature is corrected, and writing / reading of information is stabilized even with a high recording density, that is, a narrow track pitch and a short pit length. Can be done.

According to a fourth aspect of the present invention, light emitted from a laser light source is guided to an objective lens via a coupling lens, and the objective lens collects a light spot on an information recording surface of the optical disk through a transparent substrate of the optical disk. An optical disc device corresponding to a plurality of optical discs having different thicknesses of transparent substrates, wherein the laser light source and the coupling lens are provided. A drive unit for driving at least one of them in the optical axis direction, a temperature detection unit for detecting a temperature near the objective lens, a type of the optical disk, a temperature near the objective lens, the coupling lens, and the laser light source. The optical disk is determined from the table in which the relationship with the position of the optical disk is recorded and the output signal of the photodetector, and the optical disk is determined. An optical disk device comprising: a control unit that determines the position of the coupling lens and the laser light source from the table using the determination result and the detection result of the temperature detection unit, and drives the driving unit. It is.

First, since the optical disk device of the present invention is a device capable of handling a plurality of optical disks, it is determined which type of optical disk is set in the optical disk device.

The following methods are available for the determination, but are not limited. (1) The control unit drives the driving unit to move at least one of the laser light source and the coupling lens to the position for the first optical disk. Then, the optical disk is irradiated with a laser beam, and reflected light from the information recording surface of the optical disk is received by a photodetector. Depending on the signal output level of the photodetector,
It is determined whether the set optical disk is the first optical disk.

(2) First, the control unit drives the drive unit to move at least one of the laser light source and the coupling lens to the initial position. Then, the optical disk is irradiated with a laser beam, and reflected light from the information recording surface of the optical disk is received by a photodetector. Depending on the signal output level of the photodetector,
The type of the loaded optical disc is determined.

Next, the control unit detects the detection result of the temperature detecting means.
(Temperature near the objective lens), the position of the laser light source and the coupling lens are determined from the table based on the determined type of the optical disk, and based on the determination result, the driving unit is driven to drive the laser light source and the coupling lens. At least one is driven in the optical axis direction.

According to the above configuration, the spherical aberration of the objective lens caused by the temperature change is corrected, and information can be stably written / read even on an optical disk having a high recording density, that is, a narrow track pitch and a short pit length.

According to a fifth aspect of the present invention, light emitted from a laser light source is guided to an objective lens via a coupling lens, and the objective lens collects a light spot on an information recording surface of the optical disk through a transparent substrate of the optical disk. An optical disc device corresponding to a plurality of optical discs having different thicknesses of transparent substrates, wherein the laser light source and the coupling lens are provided. A drive unit for driving at least one of them in the optical axis direction, a temperature detection unit for detecting a temperature near the objective lens, a type of the optical disk, a temperature near the objective lens, the coupling lens, and the laser light source. The optical disk is determined from the table in which the relationship with the position of the optical disk is recorded and the output signal of the photodetector, and the optical disk is determined. Judgment result, using the detection result of the temperature detecting means, the coupling lens from the table, determine the position of the laser light source to drive the driving means, from the output signal of the photodetector after driving, An optical disk device comprising: a control unit that drives the driving unit so as to correct spherical aberration of the objective lens.

First, since the optical disk device of the present invention is a device capable of handling a plurality of optical disks, it is determined which type of optical disk is set in the optical disk device.

As a method of determining, there are the following methods, but the method is not limited. (1) The control unit drives the driving unit to move at least one of the laser light source and the coupling lens to the position for the first optical disk. Then, the optical disk is irradiated with a laser beam, and reflected light from the information recording surface of the optical disk is received by a photodetector. Depending on the signal output level of the photodetector,
It is determined whether the set optical disk is the first optical disk.

(2) First, the control unit drives the drive unit to move at least one of the laser light source and the coupling lens to the initial position. Then, the optical disk is irradiated with a laser beam, and reflected light from the information recording surface of the optical disk is received by a photodetector. Depending on the signal output level of the photodetector,
The type of the loaded optical disc is determined.

Next, the control unit detects the detection result of the temperature detecting means.
(Temperature in the vicinity of the objective lens), from the determined type of optical disc, determine the position of the laser light source and the coupling lens from the table, and drive the driving means based on the determination result.
At least one of the laser light source and the coupling lens is driven in the optical axis direction.

Further, the control section drives at least one of the laser light source and the coupling lens, and then drives the driving means so as to correct the spherical aberration of the objective lens caused by the temperature change from the output signal of the photodetector. Then, at least one of the laser light source and the coupling lens is driven in the optical axis direction.

According to the above configuration, in addition to the fourth aspect of the invention, the control unit drives at least one of the laser light source and the coupling lens and then generates a temperature change from the output signal of the photodetector. By driving the driving means so as to correct the spherical aberration of the objective lens, the spherical aberration of the objective lens caused by the temperature change is further corrected, and the information can be recorded even on an optical disc having a high recording density, that is, a narrow track pitch and a short pit length. Writing / reading can be performed stably.

According to a sixth aspect of the present invention, in the third or fifth aspect of the invention, the control unit is configured to control the HF signal level, the HF signal jitter, and the error rate obtained from the output signal of the photodetector after the driving. An optical disc apparatus characterized in that the driving means is driven so that the HF signal level is maximized or the HF signal jitter or error rate is minimized.

The laser is controlled so that the HF signal level is maximized or the HF signal jitter or error rate is minimized among the HF signal levels, HF signal jitters, and error rates obtained from the output signal of the photodetector. When at least one of the light source and the coupling lens is driven in the direction of the optical axis, lens spherical aberration caused by a temperature change is corrected.

A plurality of HF signal levels, HF signal jitters, and error rates obtained from the output signal of the photodetector may be used. At this time, if the position of the laser light source and the coupling lens at which the HF signal level is the maximum is different from the position of the laser light source and the coupling lens at which the HF signal jitter and the error rate are the minimum, when there is an error rate, It is preferable to perform the measurement at the error rate, and when there is no error rate, the measurement is performed at the HF signal jitter.

According to a seventh aspect of the present invention, there is provided the optical disk apparatus according to the fifth aspect, wherein the table is rewritten based on positional information for correcting the spherical aberration of the objective lens.

The control section drives the driving means so as to correct the spherical aberration of the objective lens caused by the temperature change from the output signal of the photodetector, and then records the correction amount in a table, and records the correction amount on the optical disk in the table. The relationship between the type, the temperature near the objective lens, and the positions of the laser light source and the coupling lens is rewritten.

An error for each device can be corrected.
Also, by writing the latest information to the table every time,
When the spherical aberration of the objective lens is corrected even during operation of the apparatus, the frequency of correction can be reduced.

According to an eighth aspect of the present invention, light emitted from a laser light source is guided to an objective lens via a coupling lens, and the objective lens collects a light spot on the information recording surface of the optical disk through a transparent substrate of the optical disk. An optical disc device that supports a plurality of optical discs having different thicknesses of transparent substrates and outputs a signal by receiving light reflected from the information recording surface with a photodetector, and expands and contracts in the optical axis direction due to a temperature change. A first drive unit having one end attached to at least one of the laser light source and the coupling lens, and the other end attached to a member provided to be movable in the optical axis direction; The optical disc is determined from the second driving means driving in the direction and the output signal of the photodetector, and the coupling lens and the laser are determined from the table. An optical disk device comprising: a control unit that determines a position of a laser light source and drives the second driving unit.

First, since the optical disk device of the present invention is a device that can handle a plurality of optical disks, it is determined which type of optical disk is set in the optical disk device.

The following methods are available for determination, but are not limited. (1) The control unit drives the second driving unit to control the laser light source,
At least one of the coupling lenses is moved to a position for the first optical disk. Then, the optical disk is irradiated with a laser beam, and reflected light from the information recording surface of the optical disk is received by a photodetector. Based on the signal output level of the photodetector, it is determined whether the set optical disk is the first optical disk.

(2) First, the control section drives the second drive means to move at least one of the laser light source and the coupling lens to the initial position. Then, the optical disk is irradiated with a laser beam, and reflected light from the information recording surface of the optical disk is received by a photodetector. The type of the set optical disc is determined based on the signal output level of the photodetector.

Then, at least one of the laser light source and the coupling lens is moved to a position set in advance according to the type of the determined optical disc. on the other hand,
The first driving means expands and contracts by heat, and drives at least one of the laser light source and the coupling lens in the optical axis direction.

According to the above arrangement, by setting the coefficient of thermal expansion of the first driving means to a coefficient of thermal expansion that reduces spherical aberration caused by heat of the objective lens, spherical aberration caused by heat of the objective lens is corrected. High-density recording, that is, information writing / writing even on optical disks with narrow track pitch and short pit length
Reading can be performed stably.

[0044]

Embodiments of the present invention will now be described with reference to the drawings. (1) First Embodiment FIG. 1 is a configuration diagram illustrating a first embodiment of the present invention. FIG. 1 (a) shows a recording medium 2 set, and FIG. FIG. 2 shows the configuration of the laser light source assembly in FIG. 1 when the medium 2 'is set, and FIG. 3 is a flowchart illustrating the operation of FIG.

First, in FIGS. 1A and 1B, reference numeral 1 denotes a DVD2 which is an optical disk having a transparent substrate having a different thickness on a recording surface.
And a disk drive means for rotationally driving the CD 2 '. These DVDs, CDs 2 and 2 'are transparent substrates 2 having different thicknesses.
a, 2a 'and recording surfaces 2b, 2b' formed on these transparent substrates 2a, 2a '.

Reference numeral 3 denotes a DVD, a CD by a driving means (not shown).
The optical pickup is driven in a direction crossing the tracks 2 and 2 '(in the directions indicated by arrows in FIGS. 3A and 3B). Reference numeral 4 denotes a laser light source assembly. As shown in FIG. 2, the laser light source assembly 4 includes a laser light source 5 for emitting a laser beam, and a diffraction grating for separating the laser beam emitted from the laser light source 5 into one main beam and two sub-beams. 6, and DVD,
A photodetector 7 for detecting a return laser beam from the CDs 2, 2 'and a hologram beam splitter 8 for guiding a return laser beam from the optical disks 2, 2' to the photodetector 7 are integrally formed.

Returning to FIG. 1, reference numeral 10 denotes a laser beam emitted from the laser light source
An objective lens 2 'is focused upward, and a coupling lens 11 is provided between the laser light source assembly 4 and the objective lens 10.

The coupling lens frame 12 for holding the coupling lens 11 is provided with two coupling lenses provided along the optical axis direction.
It is slidably engaged with the guides 13 and 14 of the book. Further, the coupling lens frame 11 is rotatable, and
It is screwed into a screw rod 15 provided in parallel with the guide 13. Then, the screw rod 15 is rotationally driven by a screw rod driving means 16 capable of position control such as a stepping motor.
Coupling lens frame 12 (coupling lens 11)
Move along the guides 13 and 14 in the optical axis direction.

Reference numeral 17 denotes a home sensor that responds when the coupling lens frame 12 moves to the home position, and 18 receives a signal from the home sensor 17 and
The control unit drives the screw rod driving means 16 and the laser light source assembly 4.

Reference numeral 19 denotes a stop for controlling the amount of laser light emitted from the laser light source assembly 4. This aperture 19
When the optical disk is CD2 ', the aperture is reduced, and when the optical disk is DVD2, the aperture is opened as compared with the case of CD2'.

Next, the operation of the above configuration will be described with reference to FIG. First, when the power is turned on, the control unit 18 drives the screw rod driving unit 16 and the coupling lens frame 12
(Coupling lens 11) is driven in the direction of the home sensor 17. When the coupling lens frame 12 moves to the home position, the home sensor 17 responds,
Emits a signal. When receiving the signal from the home sensor 17, the control unit 18 stops driving the screw rod driving means 16 (step 1).

Next, the control unit 18 drives the screw rod driving means 16 in the direction opposite to the above, and
Is moved to a preset CD reference position (indicated by arrow B in FIG. 1) (step 2).

Then, the control unit 18 drives the laser light source 5 in the laser light source assembly 4 to emit laser light to the set optical disk. As shown in FIG. 1B, the divergent light from the laser light source assembly 4 is
Is a weakly divergent light having a smaller divergence, and the objective lens 10
Is focused on the recording surface of the CD 2 '. The light reflected from the optical disk is received by the photodetector 7, and the optical disk set by the signal from the photodetector 7 is CD2 ',
Alternatively, it is determined whether the disc is a DVD 2 (step 3).

As a determination method, for example, the determination can be made by rotating the optical disk at a predetermined rotation speed by disk drive means (not shown) and detecting the highest frequency of the HF signal included in the signal from the photodetector 7.

That is, when the optical disk is driven to rotate at a rotational speed of 500 RPM, the HF signal obtained on the inner peripheral side of the CD 2 ′ (at a position where the disk rotational radius is 25 mm) is in a range of about 200 kHz to about 720 kHz, and the inner peripheral side of the DVD 2 The HF signal obtained at about 340kHz
From about 1.6GHz.

Therefore, the highest frequency of the obtained HF signal is about
If the frequency is detected as 720 kHz, the optical disk can be determined to be CD2 '. If the optical disc is determined to be CD2 '(step
4), the controller 18 controls the laser light source 5 in the laser light source assembly 4
Drive the set optical disc (in this case, CD
A laser beam is emitted to 2 ′). The reflected light from the optical disk is received by the photodetector 7 and the level of the HF signal is detected (step 5). Specifically, the HF signal is envelope detected,
The maximum amplitude of the AC component is taken as the level of the HF signal.

Next, it is determined whether or not the detected HF signal level is within the allowable range (step 6). If the detected HF signal level is within the allowable range, information is read / written to / from the optical disk (step 7).

Next, as long as the eject switch is not pressed (step 8), the process returns to step 5, and if the eject switch is pressed, the control unit 18 determines that the optical disk may have been replaced (step 8). 8) Check the presence or absence of an optical disk (step 9), and if there is an optical disk, return to step 2; otherwise, end the series of flows.

If it is determined in step 4 that the optical disk is the DVD 2, the control unit 18 controls the screw rod driving means 16
To move the coupling lens frame 12 to a preset DVD reference position (indicated by an arrow A in FIG. 1) (step 9).

In step 6, if the HF signal level detected in step 6 is out of the allowable range, the HF
The coupling lens frame 12 is moved in the optical axis direction to a position where the signal level becomes maximum (step 10).

That is, the control unit 18 first stores the value of the HF signal level detected in step 6. Next, the coupling lens frame 12 is moved in the optical axis direction by a predetermined amount (for example, 0.1 mm). At this time, if the detected HF signal level is higher than the previously stored HF signal level,
The signal is reset by a signal, and the coupling lens frame 12 is further moved in the optical axis direction in the same direction.

On the other hand, if the detected HF signal level is lower than the previously stored HF signal level, the coupling lens frame 12 is moved in the opposite direction to the previous one without resetting. Move in the direction of the quantitative optical axis.

By repeating this operation, the coupling lens frame 12 is moved to a position where the HF signal level becomes maximum. Whether the value is the maximum value can be obtained by reducing the amount of movement in the direction of the predetermined optical axis by returning the amount by one predetermined amount when the HF signal level changes from large to small.

If the coupling lens frame 12 has been moved to the position where the HF signal level becomes maximum in step 10,
Return to step 6. According to the above configuration, the following effects can be obtained.

(1) By moving the coupling lens 11 to the CD reference position and the DVD reference position, it is possible to cope with a plurality of optical disks having different thicknesses of the transparent substrate, that is, DVD2 and CD2 ', so that the cost is reduced. .

(2) Further, after the coupling lens 11 is moved to the CD reference position and the DVD reference position, the coupling lens 11 is moved in the optical axis direction to the position where the HF signal is maximized, thereby changing the temperature. Lens spherical aberration caused by the above can be corrected.

The present invention is not limited to the above embodiment. In the above embodiment, step 2
Moved the coupling lens 11 to the CD reference position,
The coupling lens 11 may be moved to the DVD reference position. Further, in the above embodiment, the lens spherical aberration due to the temperature change is corrected by using the HF signal level, but the HF signal level, the HF signal jitter, and the error obtained from the output signal of the photodetector are also corrected. Multiple rates may be used. At this time, if the position of the coupling lens 11 at which the HF signal level is the maximum is different from the position of the coupling lens 11 at which the HF signal jitter and the error rate are the minimum, if there is an error rate, the error rate is reduced. Do
If there is no error rate, it is desirable to use HF signal jitter. (2) Second Embodiment In the first embodiment, the coupling lens is moved in the optical axis direction. However, in the present embodiment, the laser light source is moved in the optical axis direction. .

FIGS. 4A and 4B are configuration diagrams for explaining the second embodiment. FIG. 4A shows the case where the recording medium 2 is set, and FIG. 4B shows the case where the recording medium 2 'is set. FIG. The first
The same reference numerals are given to the same portions as those in FIG. 1 for describing the embodiment, and the description thereof is omitted.

In the figure, reference numeral 21 denotes a laser light source assembly 4 and two guides 1 provided along the optical axis direction.
It is a laser light source assembly frame slidably engaged with 3,14.

Further, the laser light source assembly frame 21 is provided with a screw rod 15 provided rotatably and parallel to the guide 13.
Is screwed into. Then, the screw rod 15 is rotationally driven by screw rod driving means 16 such as a stepping motor or the like whose position can be controlled, and the laser light source assembly frame 12 (laser light source assembly 4) moves along It is designed to move.

Next, the operation of the above configuration will be described with reference to FIG. First, when the power is turned on, the control unit 18 drives the screw rod driving unit 16 to drive the laser light source assembly frame 21 (laser light source assembly 4) toward the home sensor 17. When the laser light source assembly frame 21 moves to the home position, the home sensor 17 responds and emits a signal. When receiving the signal from the home sensor 17, the control unit 18 stops driving the screw rod driving means 16 (step 1).

Next, the control unit 18 drives the screw rod driving means 16 in a direction opposite to the above, and places the laser light source assembly frame 21 at a preset CD reference position (indicated by an arrow D in FIG. 4). (Step 2).

Then, the control unit 18 drives the laser light source 5 in the laser light source assembly 4 to emit a laser beam to the set optical disk. The light reflected from the optical disk is received by the photodetector 7, and the optical disk set by the signal from the photodetector 7 is CD2 'or DV.
It is determined whether it is D2 (step 3). As a determination method, there is a method similar to that of the first embodiment.

If the optical disk is determined to be CD2 '
(Step 4) The control unit 18 drives the laser light source 5 in the laser light source assembly 4 to emit a laser beam to the set optical disk (in this case, CD2 '). The reflected light from the optical disk is received by the photodetector 7 and the level of the HF signal is detected (step 5). Specifically, the HF signal is subjected to envelope detection, and the maximum amplitude of the AC component is set as the level of the HF signal.

Next, it is determined whether or not the detected HF signal level is within the allowable range (step 6). If the detected HF signal level is within the allowable range, information is read / written to / from the optical disk (step 7).

Then, when the reading / writing of the information is completed and, for example, the eject switch is pressed, the control unit 18 determines that the optical disk has been replaced (step S1).
8) Return to step 2, if not replaced, step 5
Return to

If it is determined in step 4 that the optical disk is the DVD 2, the control unit 18
To move the laser light source assembly frame 21 to a preset DVD reference position (indicated by an arrow C in FIG. 4) (step 9).

At step 6, if the HF signal level detected at step 6 is out of the allowable range, the HF
Laser light source assembly frame 2 up to position where signal level is maximum
1 is moved in the optical axis direction (step 10).

That is, the control unit 18 first stores the value of the HF signal level detected in step 6. Next, the laser light source assembly frame 21 is moved in the optical axis direction by a predetermined amount (for example, 0.1 mm). At this time, if the detected HF signal level is higher than the previously stored HF signal level, it is reset with a new HF signal, and the laser light source assembly frame 2 is moved in the same direction.
1 is moved in the optical axis direction.

Conversely, if the detected HF signal level is lower than the previously stored HF signal level, the laser light source assembly frame 21 is moved in the opposite direction without resetting. A predetermined amount is moved in the optical axis direction.

By repeating this operation, the laser light source assembly frame 21 is moved to a position where the HF signal level becomes maximum. Whether the value is the maximum value can be obtained by reducing the amount of movement in the direction of the predetermined optical axis by returning the amount by one predetermined amount when the HF signal level changes from large to small.

If the laser light source assembly frame 21 has been moved to the position where the HF signal level becomes maximum in step 10, the process returns to step 6. According to the above configuration, the following effects can be obtained.

(1) Set the laser light source assembly 4 at the CD reference position and the DVD
By moving the optical disk to the reference position, a plurality of optical disks having different thicknesses of the transparent substrate, that is, DVD2 and CD2 'can be handled, so that the cost is reduced.

(2) After the laser light source assembly 4 is moved to the CD reference position and the DVD reference position, the laser light source assembly 4 is moved in the optical axis direction to a position where the HF signal is maximized. It is possible to correct the lens spherical aberration caused by the temperature change.

The present invention is not limited to the above embodiment. In the above embodiment, step 2
Although the laser light source assembly 4 is moved to the CD reference position to the CD reference position in the above, the laser light source assembly 4 may be moved to the DVD reference position. Further, in the above embodiment, the lens spherical aberration due to the temperature change is corrected using the HF signal level, but the HF signal level is obtained from the output signal of the photodetector.
A plurality of signal levels, HF signal jitters, and error rates may be used. At this time, if the position of the laser light source assembly 4 at which the HF signal level becomes maximum is different from the position of the laser light source assembly 4 at which the HF signal jitter and error rate become minimum, an error is detected when there is an error rate. Done at a rate,
If there is no error rate, it is desirable to use HF signal jitter. (3) Third Embodiment FIG. 5 is a configuration diagram for explaining a third embodiment. FIG. 5A is a diagram when a recording medium 2 is set, and FIG.
It is a figure which shows the time when was set.

In FIG. 5, the same parts as those in FIG. 1 for describing the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. In FIG. 5, reference numeral 31 denotes the objective lens 10.
It is a temperature detector that is provided near and detects the temperature near the objective lens 10.

Reference numeral 32 records the relationship between the temperature near the objective lens 10, the position of the coupling lens 11 that corrects the spherical aberration of the objective lens 10 due to the temperature near the objective lens 10, and the type of the optical disk. It is a table.

Here, a method of creating the table 32 will be described with reference to FIGS. FIG. 6A shows the DVD reference position (indicated by an arrow A in FIG. 5) when the coupling lens 11 is at the DVD reference position.
FIG. 7B is a graph showing the relationship between the temperature change and the spherical aberration (SA) deterioration when the coupling lens 11 is located at the position (1). FIG. In FIGS. 7A and 7B, the vertical axis represents the wavefront aberration (λ: rms), and the sign represents the directionality of the spherical aberration (positive is over spherical aberration).

FIG. 7 (a) shows an example of a DVD table, FIG. 7 (b) shows an example of a CD table, and FIG.
(c) is a diagram for explaining the aberration degradation after correction. still,
(a), (b) the residual aberration and the aberration degradation in (b) show the amount of wavefront aberration that does not indicate the direction of the spherical aberration, and (c) the amount of wavefront aberration that does not show the direction of the spherical aberration. Is shown.

FIGS. 6A and 6B show that the coupling lens 1
7 is moved in the direction of the optical axis to correct spherical aberration due to temperature change. FIG. 7 (a) for a DVD and FIG. 7 (b) for a CD
7C, the coupling lens 11 is moved from the table in the direction of the optical axis depending on the temperature. As shown in FIG.
At ℃, the absolute value of aberration degradation can be kept within 0.01.

Next, the operation of the above configuration will be described with reference to FIG. First, when the power is turned on, the control unit 18 drives the screw rod driving unit 16 and the coupling lens frame 12
(Coupling lens 11) is driven in the direction of the home sensor 17. When the coupling lens frame 12 moves to the home position, the home sensor 17 responds,
Emits a signal. When receiving the signal from the home sensor 17, the control unit 18 stops driving the screw rod driving means 16 (step 1).

Next, the control unit 18 drives the screw rod driving means 16 in the direction opposite to the above, and
Is moved to a preset CD reference position (indicated by arrow B in FIG. 5) (step 2).

Then, the control unit 18 drives the laser light source 5 in the laser light source assembly 4 to emit a laser beam to the set optical disk. The light reflected from the optical disk is received by the photodetector 7, and the optical disk set by the signal from the photodetector 7 is CD2 'or DV.
Whether it is D2 is determined by the same method as in the first embodiment (step 3).

Next, the control section 18 receives a temperature signal from the temperature detector 31 (step 4). Then, the position of the coupling lens 11 is determined from the table 32 in which the relationship between the temperature near the objective lens 10, the position of the coupling lens 11, and the type of the optical disk is recorded, and the amount of movement from the current position (CD reference position) Is calculated (step 5), and the coupling lens 11 is moved to the determined position (step 6).

After the movement, information is read / written to / from the optical disk (step 7). Then, when the reading / writing of information is completed and, for example, the eject switch is pressed, the controller 18 determines that the optical disk has been replaced (step 8), returns to step 3, and returns to step 3 if not replaced. Return to

According to the above configuration, the following effects can be obtained. (1) By moving the coupling lens 11, a plurality of optical disks having different thicknesses of the transparent substrate, that is, DVD2, CD
2 'can be accommodated, so that the cost is reduced.

(2) The relationship between the temperature near the objective lens 10, the position of the coupling lens 11 for correcting the spherical aberration of the objective lens 10 due to the temperature near the objective lens 10, and the type of the optical disk is recorded. Table 3
By determining the position of the coupling lens 11 from 2, it is possible to correct lens spherical aberration caused by a temperature change.

The present invention is not limited to the above embodiment. In the above embodiment, the coupling lens 11 is moved in the optical axis direction. However, the laser light source assembly 4 (laser light source) may be moved in the optical axis direction. (4) Fourth Embodiment FIG. 9 is a flowchart illustrating the operation of the fourth embodiment. The configuration of this embodiment is the same as that of FIG. 1 except that the operation of reading the signal of the first embodiment is different.

First, when the power supply is turned on, the control unit 18 drives the screw rod driving means 16 and the coupling lens frame 1 is turned on.
2 (coupling lens 11) is driven in the direction of the home sensor 17. When the coupling lens frame 12 moves to the home position, the home sensor 17 responds and emits a signal. When receiving the signal from the home sensor 17, the control unit 18 stops driving the screw rod driving means 16 (step 1).

Next, the control unit 18 drives the screw rod driving means 16 in a direction opposite to the above, and
Is moved to a preset CD reference position (indicated by arrow B in FIG. 1) (step 2).

Then, the controller 18 drives the laser light source 5 in the laser light source assembly 4 to emit a laser beam to the set optical disk. The light reflected from the optical disk is received by the photodetector 7, and the optical disk set by the signal from the photodetector 7 is CD2 'or DV.
Whether it is D2 is determined by the same method as in the first embodiment (step 3).

If the optical disk is determined to be CD2 '
(Step 4) The control unit 18 drives the laser light source 5 in the laser light source assembly 4 to emit a laser beam to the set optical disk (in this case, CD2 '). The reflected light from the optical disk is received by the photodetector 7 and the level of the HF signal is detected (step 5). Specifically, the HF signal is subjected to envelope detection, and the maximum amplitude of the AC component is set as the level of the HF signal.

Next, it is determined whether or not the detected HF signal level is within an allowable range (step 6). If the detected HF signal level is within the allowable range, information is read from the optical disk (step 7).

If it is determined in step 4 that the optical disk is DVD2, the control unit 18 drives the screw rod driving means 16 to move the coupling lens frame 12 to a preset DVD reference position (FIG. 1). (Indicated by arrow A in FIG. 4) (step 8).

Further, in step 6, the detection in step 6
If the HF signal level is out of the allowable range, the coupling lens frame 12 is moved in the optical axis direction to a position where the HF signal level is maximized by the "hill climbing method" (step 9).

The signal read in step 7 is temporarily stored in a memory and then output to the outside (step 10). Usually, the signal reading speed> the output speed from the memory to the outside, so that information for a predetermined time is always stored in the memory.

Then, unless the eject switch is pressed (step 12), the operations of steps 7 and 10 are continuously performed for 5 minutes (step 11). After 5 minutes, H again
The level of the F signal is detected (step 13). Next, it is determined whether or not the detected HF signal level is within the allowable range (step 14).

If it is out of the allowable range, check the remaining amount of the memory.
(Step 15) If the remaining amount is large, the coupling lens frame 12 is moved in the optical axis direction to a position where the HF signal level becomes maximum by the “hill climbing method” (Step 16).

If the remaining capacity of the memory is small, the process returns to step S7. Further, if the eject switch is pressed in step 12, the control unit 18 determines that the optical disk may have been replaced (step 12), checks the presence or absence of the optical disk (step 17), and If so, the process returns to step 2, and if there is no optical disc, a series of flows is terminated.

According to the above configuration, the following effects can be obtained. (1) By moving the coupling lens 11 to the CD reference position and the DVD reference position, it is possible to cope with a plurality of optical disks having different thicknesses of the transparent substrate, that is, DVD2 and CD2 ', so that the cost is reduced.

(2) Further, after the coupling lens 11 is moved to the CD reference position and the DVD reference position, the coupling lens 11 is moved in the optical axis direction to the position where the HF signal becomes maximum, thereby changing the temperature. Lens spherical aberration caused by the above can be corrected.

(3) Even during signal reading, error-free reading can be performed by correcting the deterioration of the spherical aberration of the objective lens 10 due to a temperature change. Note that the present invention is not limited to the above embodiment. In the above embodiment, the coupling lens 11 is moved to the CD reference position in step 2, but the coupling lens 11 may be moved to the DVD reference position. Further, in the above embodiment, the lens spherical aberration due to the temperature change is corrected using the HF signal level.
An error rate may be used. When using the HF signal jitter and the error rate, the coupling lens 11 is moved in the optical axis direction so as to minimize the jitter.

In the embodiment, the spherical aberration of the objective lens is corrected every 5 minutes. However, if there is a temperature detector, the spherical aberration of the objective lens is changed every 2 ° C. or every 5 ° C. The aberration may be corrected. (5) Fifth Embodiment FIG. 10 is a flowchart illustrating the operation of the fifth embodiment. The configuration of the present embodiment is the same as that of FIG. 5 except for the operation of the third embodiment.

First, when the power supply is turned on, the control unit 18 drives the screw rod driving means 16 and the coupling lens frame 1 is turned on.
2 (coupling lens 11) is driven in the direction of the home sensor 17. When the coupling lens frame 12 moves to the home position, the home sensor 17 responds and emits a signal. When receiving the signal from the home sensor 17, the control unit 18 stops driving the screw rod driving means 16 (step 1).

Next, the control unit 18 drives the screw rod driving means 16 in the direction opposite to the above, and
Is moved to a preset CD reference position (indicated by arrow B in FIG. 5) (step 2).

Then, the control section 18 drives the laser light source 5 in the laser light source assembly 4 to emit a laser beam to the set optical disk. The light reflected from the optical disk is received by the photodetector 7, and the optical disk set by the signal from the photodetector 7 is CD2 'or DV.
It is determined whether it is D2 (step 3).

Next, the control section 18 receives a temperature signal from the temperature detector 31 (step 4). Then, the position of the coupling lens 11 is determined from the table 32 in which the relationship between the temperature near the objective lens 10, the position of the coupling lens 11, and the type of the optical disk is recorded, and the amount of movement from the current position (CD reference position) Is calculated (step 5), and the coupling lens 11 is moved to the determined position (step 6).

Next, the control unit 18 drives the laser light source 5 in the laser light source assembly 4, and
A laser beam is emitted to (in this case, CD2 '). The light reflected from the optical disk is received by the photodetector 7, and the level of the HF signal is detected (step 7). Specifically, the HF signal is subjected to envelope detection, and the maximum amplitude of the AC component is set as the level of the HF signal.

Next, it is determined whether or not the detected HF signal level is within an allowable range (step 8). If the detected HF signal level is within the allowable range, information is read from the optical disk (step 9).

Further, in step 8, the detection in step 7
If the HF signal level is out of the allowable range, the coupling lens frame 12 is moved in the optical axis direction to a position where the HF signal level is maximized by the "hill climbing method" (step 10). Further, the table 32 is rewritten based on this information.
(Step 11).

Next, as long as the eject switch is not pressed (step 12), the process returns to step 7, and if the eject switch is pressed, the control unit 18 determines that there is a possibility that the optical disk has been replaced (step 12). 12), the presence or absence of an optical disk is checked (step 13), and if there is an optical disk, the flow returns to step 2;

According to the above configuration, the following effects can be obtained. (1) By moving the coupling lens 11 in the direction of the optical axis, a plurality of optical disks having different thicknesses of the transparent substrate, that is, DVD2 and CD2 'can be handled, so that the cost is reduced.

(2) The relationship between the temperature near the objective lens 10, the position of the coupling lens 11 for correcting the spherical aberration of the objective lens 10 due to the temperature near the objective lens 10, and the type of the optical disk is recorded. Table 3
By determining the position of the coupling lens 11 from 2, it is possible to correct lens spherical aberration caused by a temperature change.

(3) Further, after the coupling lens 11 is moved in the direction of the optical axis, the coupling lens 11 is moved in the direction of the optical axis until the HF signal is maximized. The spherical aberration can be corrected more precisely.

(4) By rewriting the table 32 based on the information corrected in (3), it is possible to correct a unique error existing in each device. Also, by writing the latest information to the table each time, the spherical aberration of the objective lens is corrected even during operation of the device,
The frequency of correction can be reduced. (6) Sixth Embodiment This embodiment is different from the first to fifth embodiments in the mechanism for moving the coupling lens in the optical axis direction. FIG.
FIGS. 7A and 7B are configuration diagrams illustrating a sixth embodiment, FIG. 7A is a plan configuration diagram, and FIG. 7B is a right side view of FIG. Note that the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, 50 is the coupling lens 1
1 is a coupling lens frame that slidably engages with the guides 13 and 14 while holding the first lens frame 1. The coupling lens frame 50 has a rack portion 50 extending along the guide 14 and having a rack 50b formed in parallel with the guide 14.
a is formed.

A motor 51 is provided on the base 58 side of the apparatus and has two output shafts as driving means. Pulleys 52 and 53 are fixed to one output shaft of the motor 51. A stopper plate 54 is fixed to the tip of the other output shaft, a pinion 55 is loosely fitted to the intermediate portion, and the pinion 55 is further actuated by a biasing force of a spring 56 provided to wind the output shaft. It is in contact with the stopper plate 54.

At the CD reference position and the DVD reference position of the base 58, disk plates 60 and 61 are rotatably provided. A pulley 62 is provided on the disk plate 60, and a pulley 63 is provided on the disk plate 61. A belt 64 is wound around the pulley 53 and the pulley 63, and a belt 65 is wound around the pulley 52 and the pulley 62. Furthermore, pins 66 and 67 to which the coupling lens frame 50 can abut are provided upright on the disc plates 60 and 61 at eccentric positions.

At the CD reference position (indicated by an arrow B) and the DVD reference position (indicated by an arrow A) on the base 58, stopper springs 68 and 69 that can be engaged with the coupling lens frame 50 are provided. I have.

The operation flow of the above configuration is the same as that of the first embodiment. The difference is that step 2 in FIG.
And the movement to the CD reference position and the DVD reference position in Step 9 and the movement of the coupling lens frame 50 in Step 10.

In the case of movement to the CD reference position and the DVD reference position in Steps 2 and 9, the motor 51 is driven to rotate, and the pinion 55 engages with the rack 50b of the rack portion 50a of the coupling lens frame 50. A large movement between the CD reference position and the DVD reference position of the coupling lens frame 50 is performed.

When the coupling lens frame 50 reaches the CD reference position and the DVD reference position, the coupling lens frame 50 comes into contact with the pins 66 and 67 of the disk plates 60 and 61, and the coupling lens frame 50 moves. When the DVD reaches the DVD reference position, the stopper spring 69 moves the coupling lens frame 5
0, and urges the coupling lens frame 50 in the direction of the pin 67 of the disk plate 61, thereby coupling the coupling lens frame 5
When 0 reaches the CD reference position, the stopper spring 68 is engaged with the coupling lens frame 50 to urge the coupling lens frame 50 in the direction of the pin 66 of the disk plate 60,
The movement to the CD reference position and the DVD reference position is completed.

When the motor 51 is driven, the coupling lens frame 50 is moved in step
When the pins 66 and 67 on the eccentric member 61 are eccentrically rotated, the coupling lens frame 50 abutting on the pins 66 and 67 is rotated.
Moves in the direction of the optical axis to correct spherical aberration due to a temperature change of the objective lens 10. (7) Seventh Embodiment This embodiment is different from the first to fifth embodiments in that the mechanism for moving the coupling lens in the optical axis direction is similar to the sixth embodiment. . 12A and 12B are configuration diagrams illustrating a seventh embodiment, wherein FIG. 12A is a plan configuration diagram, and FIG. 12B is a right side view of FIG. Note that the same parts as those in FIG. 11 are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, reference numeral 70 denotes a temperature detector for detecting the temperature near the objective lens 10. At the CD reference position and the DVD reference position of the base 58, linear motors 72 and 73 for driving the coupling lens frame 50 in the optical axis direction are provided.

The operation flow of the above configuration is the same as that of the third embodiment. The difference is that step 1 in FIG.
Move to the home position, move to the CD reference position in step 2, and move the coupling lens frame 50 in step 6.

In the case of the movement to the home position in step 1 and the movement to the CD reference position in step 2, the motor 51 is driven to rotate, and the pinion 55 meshes with the rack 50b of the rack portion 50a of the coupling lens frame 50. Thus, the movement to the CD reference position and the DVD reference position in step 1 and step 2 is performed.

When the coupling lens frame 50 reaches the CD reference position and the DVD reference position, when the coupling lens frame 50 reaches the CD reference position and the DVD reference position.
Abuts against the linear motors 72 and 73, and when the coupling lens frame 50 reaches the DVD reference position, the stopper spring 69 engages with the coupling lens frame 50 and moves the coupling lens frame 50 to the linear motor 73. When the coupling lens frame 50 reaches the CD reference position, the stopper spring 68 engages with the coupling lens frame 50 to urge the coupling lens frame 50 toward the linear motor 72. Then, the movement to the CD reference position and the DVD reference position is completed.

The movement of the coupling lens frame 50 in step 6 is performed by driving each of the linear motors 72 and 73 so that the coupling lens frame 50 moves in the optical axis direction, and the spherical aberration due to the temperature change of the objective lens 10 is reduced. to correct. (8) Eighth Embodiment FIG. 13 is a plan view illustrating an eighth embodiment, and FIG. 14 is a flowchart illustrating the operation in FIG.
Note that the same parts as those in FIG. 11 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 13, reference numeral 90 denotes guides 13 and 14.
The coupling lens frame slidably engages with the coupling lens frame. The coupling lens frame 90 expands and contracts in the optical axis direction depending on the temperature, and an end of a thermal expansion member 91 as a first driving unit is fixed. At the other end of the thermal expansion member 91, a sub-coupling lens frame 82 for holding the coupling lens 11 is provided.

The thermal expansion coefficient of the thermal expansion member 91 is as follows:
The thermal expansion coefficient is set so as to reduce spherical aberration due to heat of the objective lens 10. Also, the coupling lens frame 9
0, a rack portion 90a provided with a rack 90b extending in the guide 14 direction and engaging with a pinion 94 attached to an output shaft of a motor 93, which is a second drive means provided on the base side. ing.

At the CD reference position and the DVD reference position on the base side, stopper pins 96 and 97 with which the coupling lens frame 90 can abut are provided. Next, the operation of the above configuration will be described with reference to FIG. The thermal expansion member 91, which is the first driving means, thermally expands due to the temperature inside the apparatus, and the spherical aberration due to the heat of the objective lens 10 is corrected.

When the power is turned on, the control unit 18 drives the motor 93 to drive the coupling lens frame 90 in the CD reference position direction. Then, when the coupling lens frame 90 comes into contact with the stopper pin 96 and the drive current is detected to rise, the drive of the motor 93 is stopped and the movement to the CD reference position is performed (step 1).

Then, the controller 18 drives the laser light source 5 in the laser light source assembly 4 to emit a laser beam to the set optical disk. The light reflected from the optical disk is received by the photodetector 7, and the optical disk set by the signal from the photodetector 7 is CD2 'or DV.
It is determined whether it is D2 (step 2).

If the optical disk is determined to be CD2 '
(Step 3), information is read / written to / from the optical disk (Step 4). On the other hand, if it is determined in step 3 that the optical disk is DVD 2, the control unit 18 drives the motor 93 to drive the coupling lens frame 90 in the direction of the DVD reference position. Then, the coupling lens frame 90
Detects that the drive current rises, stops the drive of the motor 93, moves to the DVD reference position (step 5), and performs step 4.

Next, as long as the eject switch is not pressed (step 6), the process returns to step 4, and if the eject switch is pressed, the control unit 18 determines that the optical disk may have been replaced (step 6). 6) Check the presence or absence of an optical disk (step 7), and if there is an optical disk, return to step 1; otherwise, end the series of flows.

According to the above configuration, the following effects can be obtained. (1) By moving the coupling lens 11 to the CD reference position and the DVD reference position, it is possible to cope with a plurality of optical disks having different thicknesses of the transparent substrate, that is, DVD2 and CD2 ', so that the cost is reduced.

(2) Further, the thermal expansion member 91 as the first driving means thermally expands, and the spherical aberration due to the heat of the objective lens 10 can be corrected. Note that the present invention is not limited to the above embodiment. In the above embodiment, in step 1, the coupling lens 11 is moved to the CD reference position.
Moved to the DVD reference position.
May be moved.

In the above embodiment, the coupling lens 11 is moved in the optical axis direction, but the laser light source assembly 4 may be moved in the optical axis direction. Further, in the first to eighth embodiments, the coupling lens 11 is moved in the optical axis direction or the laser light source assembly 4 is moved in the optical axis direction. The light source assembly 4 may be moved in the optical axis direction.

[0149]

According to the first aspect of the invention, the HF signal level, the HF signal jitter, and the HF signal level obtained from the output signal of the photodetector are obtained.
Of the error rates, at least one of the laser light source and the coupling lens is driven in the optical axis direction such that the HF signal level is maximized, or the HF signal jitter or error rate is minimized. By doing so, the lens spherical aberration caused by the temperature change is corrected.

According to the second aspect of the present invention, a table is provided in which the relationship between the temperature near the objective lens and the positions of the coupling lens and the laser light source is recorded, and the temperature near the objective lens is detected. Determining the position of the coupling lens and the laser light source from and correcting lens spherical aberration caused by a temperature change by driving at least one of the laser light source and the coupling lens in the optical axis direction. it can.

According to the third aspect of the present invention, the optical disc is determined from the driving means for driving at least one of the laser light source and the coupling lens in the optical axis direction and the output signal of the photodetector. A control unit that drives the driving unit to a position set in advance according to the determination result, and drives the driving unit to correct spherical aberration of the objective lens from an output signal of the photodetector after driving. Is provided, the spherical aberration of the objective lens caused by the temperature change is corrected, and information can be written / read stably even on an optical disk having a high recording density, that is, a narrow track pitch and a short pit length.

According to the fourth aspect of the present invention, at least one of a laser light source and the coupling lens is driven in an optical axis direction, a temperature detecting means for detecting a temperature near the objective lens, The type of the optical disk, the temperature in the vicinity of the objective lens, the coupling lens, a table in which the relationship between the position of the laser light source is recorded, and the output signal of the photodetector, to determine the optical disk, the optical disk Using the determination result and the detection result of the temperature detection unit, the position of the coupling lens and the laser light source is determined from the table, and a control unit that drives the driving unit is provided. The spherical aberration of the objective lens is corrected, and information can be written / recorded even on an optical disc with high recording density, that is, narrow track pitch and short pit length. Look up can be performed in a stable manner.

According to the fifth aspect of the present invention, at least one of the laser light source and the coupling lens is driven in the direction of the optical axis, the temperature detecting means for detecting the temperature near the objective lens, The type of the optical disk, the temperature in the vicinity of the objective lens, the coupling lens, a table in which the relationship between the position of the laser light source is recorded, and the output signal of the photodetector, to determine the optical disk, the optical disk Judgment result, using the detection result of the temperature detecting means, the coupling lens from the table, determine the position of the laser light source to drive the driving means, from the output signal of the photodetector after driving, A control unit for driving the driving unit so as to correct spherical aberration of the objective lens; Spherical aberration is further corrected,
Even with an optical disk having a high recording density, that is, a narrow track pitch and a short pit length, information can be written / read stably.

According to a sixth aspect of the present invention, in the third or fifth aspect of the present invention, the control section may control the HF signal level, HF signal level obtained from the output signal of the photodetector after the driving.
Among the signal jitter and error rate, the lens spherical aberration caused by a temperature change by driving the driving unit so that the HF signal level is maximized, or the HF signal jitter or error rate is minimized. Is corrected.

According to a seventh aspect of the present invention, in the fifth aspect of the present invention, the error of each device can be corrected by rewriting the table based on position information for correcting the spherical aberration of the objective lens. it can. Also, by writing the latest information to the table each time, the spherical aberration of the objective lens is corrected even during operation of the device,
The frequency of correction can be reduced.

According to the invention of claim 8, it expands and contracts in the optical axis direction due to temperature change, one end is attached to at least one of the laser light source and the coupling lens, and the other end is movable in the optical axis direction. A first drive unit attached to a member provided in the unit, a second drive unit for driving the member in the optical axis direction, and from the output signal of the photodetector, determine the optical disk, the table And a control unit for determining the position of the laser light source and driving the second driving means, thereby reducing the coefficient of thermal expansion of the first driving means by spherical aberration caused by the heat of the objective lens. By setting the coefficient of thermal expansion so as to reduce the aberration, the spherical aberration due to the heat of the objective lens is corrected, and high-density recording, that is, information writing even on an optical disk with a narrow track pitch and a short pit length Storing / reading can be performed stably.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a first embodiment, and FIG.
The figure shows the state when the recording medium 2 is set, and the figure (b) shows the state when the recording medium 2 'is set.

FIG. 2 is a configuration diagram of a laser light source assembly in FIG. 1;

FIG. 3 is a flowchart illustrating the operation of FIG. 1;

FIG. 4 is a configuration diagram illustrating a second embodiment, and FIG.
The figure shows the state when the recording medium 2 is set, and the figure (b) shows the state when the recording medium 2 'is set.

FIG. 5 is a configuration diagram illustrating a third embodiment, and FIG.
The figure shows the state when the recording medium 2 is set, and the figure (b) shows the state when the recording medium 2 'is set.

FIG. 6 (a) is a diagram in which the coupling lens 11 is at the DVD reference position.
FIG. 5 is a diagram showing a relationship between temperature change and spherical aberration (SA) degradation when the coupling lens 11 is located at (indicated by an arrow A in FIG. 5), and FIG. It is a figure showing change of spherical aberration (SA) deterioration.

7A is a diagram illustrating an example of a DVD table, FIG. 7B is a diagram illustrating an example of a CD table, and FIG. 7C is a diagram illustrating aberration degradation after correction.

FIG. 8 is a flowchart illustrating the operation of FIG. 5;

FIG. 9 is a flowchart illustrating a fourth embodiment.

FIG. 10 is a flowchart illustrating a fifth embodiment. It is.

FIG. 11 is a configuration diagram illustrating a sixth embodiment;
(a) is a plan view and (b) is a right side view of (a).

FIG. 12 is a configuration diagram illustrating a seventh embodiment;
(a) is a plan view and (b) is a right side view of (a).

FIG. 13 is a plan view illustrating an eighth embodiment.

FIG. 14 is a flowchart illustrating the operation in FIG. 13;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disc drive means 2 DVD 2'CD 3 Optical pickup 4 Laser light source assembly 10 Objective lens 11 Coupling lens 12 Coupling lens frame 13,14 Guide 16 Screw rod drive means 17 Home sensor 18 Control part

Claims (8)

[Claims] 1. The information recording device according to claim 1, wherein the light emitted from the laser light source is guided to an objective lens via a coupling lens, and the objective lens converges as a light spot on an information recording surface of the optical disc through a transparent substrate of the optical disc. A method for correcting the spherical aberration of a lens of an optical disc device for receiving reflected light from a surface with a photodetector and outputting a signal, wherein the HF signal level obtained from the output signal of the photodetector, HF
Signal jitter, error rate, so that the HF signal level is maximized, or so that the HF signal jitter or error rate is minimized, at least one of the laser light source and the coupling lens, the optical axis A method for correcting a spherical aberration of a lens of an optical disc device, wherein the method is driven in a direction. 2. The information recording device according to claim 1, wherein the light emitted from the laser light source is guided to an objective lens via a coupling lens, and the objective lens focuses the light as a light spot on an information recording surface of the optical disk through a transparent substrate of the optical disk. A method for correcting a spherical aberration of a lens of an optical disc device for receiving light reflected from a surface by a photodetector and outputting a signal, wherein a relationship between a temperature near the objective lens and a position of a coupling lens and a laser light source is recorded. Detecting a temperature in the vicinity of the objective lens; determining a position of the coupling lens and the laser light source from the table; and at least one of the laser light source and the coupling lens in an optical axis direction. A method for correcting a spherical aberration of a lens of an optical disc device, characterized by being driven. 3. The information recording device according to claim 1, wherein the light emitted from the laser light source is guided to an objective lens via a coupling lens, and the objective lens converges as a light spot on an information recording surface of the optical disc through a transparent substrate of the optical disc. An optical disc device corresponding to a plurality of optical discs having different thicknesses of a transparent substrate, the optical disc device corresponding to a plurality of optical discs having different thicknesses of a transparent substrate, wherein at least one of the laser light source and the coupling lens emits light. Driving means for driving in the axial direction, determining the optical disk from an output signal of the photodetector, driving the driving means to a preset position according to the determination result, and driving the photodetector An optical disk, comprising: a control unit that drives the driving unit so as to correct the spherical aberration of the objective lens from the output signal of the optical disk. Location. 4. A light emitted from a laser light source is guided to an objective lens via a coupling lens, and the objective lens focuses a light spot on an information recording surface of the optical disk through a transparent substrate of the optical disk. An optical disc device corresponding to a plurality of optical discs having different thicknesses of a transparent substrate, the optical disc device corresponding to a plurality of optical discs having different thicknesses of a transparent substrate, wherein at least one of the laser light source and the coupling lens emits light. Driving means for driving in the axial direction; temperature detecting means for detecting a temperature near the objective lens; and a relationship among a type of the optical disk, a temperature near the objective lens, and a position of the coupling lens and the laser light source. The optical disk is determined from the recorded table and the output signal of the photodetector, and the determination result of the optical disk and the temperature detection are performed. An optical disk device, comprising: a controller that determines a position of the coupling lens and the laser light source from the table using a detection result of the output unit, and drives the driving unit. 5. The information recording device according to claim 1, wherein the light emitted from the laser light source is guided to an objective lens via a coupling lens, and the objective lens condenses the light onto an information recording surface of the optical disc through a transparent substrate of the optical disc. An optical disc device corresponding to a plurality of optical discs having different thicknesses of a transparent substrate, the optical disc device corresponding to a plurality of optical discs having different thicknesses of a transparent substrate, wherein at least one of the laser light source and the coupling lens emits light. Driving means for driving in the axial direction; temperature detecting means for detecting a temperature near the objective lens; and a relationship among a type of the optical disk, a temperature near the objective lens, and a position of the coupling lens and the laser light source. The optical disc is determined from the recorded table and the output signal of the photodetector. Using the detection result of the degree detecting means, the coupling lens, the position of the laser light source is determined from the table to drive the driving means, and from the output signal of the photodetector after driving, the objective lens An optical disc device, comprising: a control unit that drives the driving unit so as to correct spherical aberration. 6. The controller, wherein the HF signal level is maximized among HF signal levels, HF signal jitters, and error rates obtained from the output signals of the photodetectors after the driving, or 6. The optical disk device according to claim 3, wherein the driving unit is driven such that an HF signal jitter or an error rate is minimized. 7. The optical disk device according to claim 5, wherein the table is rewritten based on position information for correcting a spherical aberration of the objective lens. 8. The information recording device according to claim 1, wherein the light emitted from the laser light source is guided to an objective lens via a coupling lens, and the objective lens condenses the light onto an information recording surface of the optical disc through a transparent substrate of the optical disc. An optical disc device which receives a reflected light from a surface with a photodetector and outputs a signal, and which corresponds to a plurality of optical discs having different thicknesses of a transparent substrate. A first driving unit attached to at least one of the light source and the coupling lens and the other end attached to a member provided so as to be movable in the optical axis direction; and a second driving unit for driving the member in the optical axis direction. The optical disc is determined from the output signal of the photodetector, and the positions of the coupling lens and the laser light source are determined from the table. Optical disk apparatus characterized by comprising a control unit for driving the second drive means in.