JP2009283081A - Method for correcting spherical aberration of optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for correcting spherical aberration of an optical pickup device equipped with a correcting means for correcting spherical aberration generated by a temperature change of an objective lens. <P>SOLUTION: The method for correcting spherical aberration of the optical pickup device including a focusing coil 12 for displacing the objective lens 8 in the direction vertical to a signal surface of an optical disk D and a tracking coil 13 for displacing the objective lens 8 in the radial direction of the optical disk D is configured to correct the spherical aberration by moving a collimator lens 5 set in an optical path between a laser diode 1 and the objective lens 8 in the optical axis direction based on the temperature detected by a temperature detecting element 21 set for detecting the temperature of the objective lens 8, and corrects the moving position of the collimator lens 5 depending on the operation of the optical pickup device. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a spherical aberration correction method for an optical pickup device that performs reading operation of a signal recorded on an optical disc and recording operation of a signal on an optical disc by laser light.

  2. Description of the Related Art Optical disk apparatuses that can perform signal reading operation and signal recording operation by irradiating a signal recording layer of an optical disk with laser light emitted from an optical pickup device have become widespread.

  As an optical disk apparatus, an apparatus using an optical disk called a CD or a DVD is generally widespread. Recently, an optical disk with improved recording density, that is, an apparatus using a Blu-ray standard optical disk has been developed.

  As a laser beam for performing a read operation of a signal recorded on a CD standard optical disc, an infrared light having a wavelength of 780 nm is used. As a laser beam for performing a read operation of a signal recorded on a DVD standard optical disc, , Red light having a wavelength of 650 nm is used.

  For such CD standard and DVD standard optical disks, the laser light for performing the read operation of the signals recorded on the Blu-ray standard optical disk is a laser light having a short wavelength, for example, a blue-violet light having a wavelength of 405 nm. in use.

  The thickness of the protective layer provided on the upper surface of the signal recording layer in the Blu-ray standard optical disc is 0.1 mm, and the aperture of the objective lens used to read out signals from the signal recording layer The number is set to 0.85.

  In addition, the optical pickup device corresponding to the optical disc standard in which the recording density is improved as described above has strict optical characteristics required for performing the signal recording / reproducing operation as the recording density is improved.

  When glass is used as a material for an objective lens for condensing laser light on a signal recording layer provided on an optical disc, it is not affected by temperature, so that it can improve signal recording characteristics and reproduction characteristics, but is expensive. There is a problem of becoming. As a method for solving such a problem, a method of manufacturing an objective lens by injection molding a synthetic resin is generally performed.

Synthetic resin objective lenses can be manufactured at low cost and have the advantage of being light, but they expand or contract with temperature changes, causing spherical aberration and deteriorating signal reading characteristics. There is. As a method of correcting spherical aberration generated from the objective lens, a method of moving a collimating lens provided in the optical path between the laser diode and the objective lens in the optical axis direction is often employed. (See Patent Document 1)
JP 2003-132573 A

A laser driving circuit for supplying a driving signal to a laser diode provided to emit laser light when an operation of reading a signal recorded on an optical disk mounted on the optical disk device is started by an optical pickup device, and a laser diode Since heat is generated from a focusing coil that moves the objective lens in a direction perpendicular to the optical disk surface and a tracking coil that moves the objective lens in the radial direction of the optical disk, the temperature of the objective lens rises due to these heats.

  When a lens made of a synthetic resin is used as the objective lens, spherical aberration occurs with a change in temperature. The relationship between the change in temperature of the objective lens and the amount of spherical aberration is as shown in FIG. The amount of aberration increases. For this reason, when spherical aberration occurs, there is a problem that the signal reading characteristic of the optical pickup device deteriorates and the jitter value included in the read signal increases.

  As a method for solving such a problem, a recent optical pickup device is provided with a temperature detection element for detecting the temperature of the objective lens, and is capable of displacement in the optical axis direction when the temperature of the objective lens rises. Some collimating lenses are moved to a position corresponding to the detected temperature to correct spherical aberration.

  The objective lens incorporated in the optical pickup device is a lens that is supported by a plurality of support wires so as to be able to be displaced in the focus direction that is perpendicular to the signal surface of the optical disc and in the tracking direction that is the radial direction of the optical disc. It is fixed to a member called a holder.

  As the above-described temperature detection element, a thermistor is generally used. However, in order to accurately detect the temperature of the objective lens, it is necessary to provide a temperature detection element in the vicinity of the objective lens. As described above, the objective lens is fixed on the lens holder, and the lens holder is required to be lightweight in order to perform a focus control operation and a tracking control operation. Therefore, it is not desirable to install the temperature detection element on the lens holder, and it is generally fixed on a printed wiring board in which a circuit for performing the control operation of the optical pickup device is incorporated, for example, at a position away from the objective lens. .

  Therefore, since the temperature detected by the temperature detection element is different from the actual temperature of the objective lens, the aberration correction position of the collimator lens is controlled by estimating the temperature of the objective lens from the detected temperature. It is configured. The objective lens temperature estimation operation in the prior art assumes the case where a signal reading operation is performed. However, in practice, the objective lens temperature estimation operation is for a track jump operation that instantaneously moves the signal reading position or an optical disc surface shake. A focus control operation and the like are frequently performed, and heat generated from the tracking coil and the focusing coil increases with the operation.

  Since measures against the temperature rise of the objective lens due to the heat generated in association with the track jump operation described above are not taken, there is a problem that the spherical aberration correction operation cannot be performed accurately.

  The present invention is intended to provide a spherical aberration correction method for an optical pickup device that can solve such a problem.

  The present invention provides a collimating lens provided in an optical path between a laser diode and an objective lens in the direction of the optical axis based on a temperature detected by a temperature detection element provided to detect the temperature of the objective lens. In this configuration, the spherical aberration is corrected by moving the lens to the position, and the moving position of the collimating lens is corrected in accordance with the operation of the optical pickup device.

  Further, the present invention is characterized in that the movement position of the collimating lens is corrected in accordance with a drive signal supplied to a tracking coil provided to displace the objective lens in the radial direction of the optical disk. is there.

  The present invention is characterized in that the movement position of the collimating lens is corrected in accordance with the track jump drive signal supplied to the tracking coil.

  Furthermore, the present invention is characterized in that the movement position of the collimating lens is corrected in accordance with the number of times the track jump drive signal supplied to the tracking coil is supplied.

  Further, the present invention is characterized in that the moving position of the collimating lens is corrected according to the supply time of the track jump drive signal supplied to the tracking coil.

  In the present invention, the movement position of the collimating lens is corrected in accordance with a drive signal supplied to a focusing coil provided to displace the objective lens in a direction perpendicular to the signal surface of the optical disk. It is a feature.

  Further, the present invention is characterized in that the movement position of the collimating lens is corrected in accordance with the level of the focus drive signal supplied to the focusing coil.

  Furthermore, the present invention is characterized in that the movement position of the collimating lens is corrected in accordance with the movement position of the optical pickup device.

  Further, the present invention is characterized in that the moving position of the collimating lens is corrected according to the rotational speed of the optical disk.

  Further, the present invention is characterized in that the movement position of the collimating lens is corrected based on the correction data read from the aberration correction data memory circuit in which correction data for correcting the movement position of the collimating lens is stored. To do.

  In the spherical aberration correction method of the present invention, the collimating lens provided in the optical path between the laser diode and the objective lens is adjusted to a temperature detected by a temperature detection element provided to detect the temperature of the objective lens. Based on this, the spherical aberration is corrected by moving in the optical axis direction, and the moving position of the collimating lens is corrected in accordance with the operation of the optical pickup device, so that the temperature of the objective lens is detected. Even if the temperature detection element provided is at a position away from the objective lens, the collimating lens can be moved to a position corresponding to the temperature close to the actual temperature of the objective lens, and the spherical aberration correction operation is performed accurately. I can do it.

  FIG. 1 is an example of an optical pickup apparatus according to the present invention, FIG. 2 is a diagram for explaining the relationship between reproduction time and temperature change, and FIGS. 3 and 4 are diagrams for explaining the operation of the present invention. is there.

In FIG. 1, 1 is a laser diode that radiates laser light, for example, blue-violet light having a wavelength of 405 nm, and 2 is a diffraction grating on which laser light emitted from the laser diode 1 is incident. A diffraction grating 2a that separates the main beam that is 0th-order light, two sub-beams that are + 1st-order light, and ½-order light and a half-wave plate that converts incident laser light into linearly polarized light in the S direction, for example. 2b.

  Reference numeral 3 denotes a polarization beam splitter on which the laser light transmitted through the diffraction grating 2 is incident. The polarization beam splitter 3 reflects most of the S-polarized laser light and transmits part of it, and is converted into linearly polarized light in the P direction. Further, a control film 3a that transmits the laser beam is provided.

  Reference numeral 4 denotes a quarter-wave plate provided at a position where the laser beam reflected by the control film 3a of the polarizing beam splitter 3 is incident. The incident laser beam is changed from linearly polarized light to circularly polarized light. On the other hand, it also functions to convert circularly polarized light into linearly polarized light. Reference numeral 5 denotes a collimator lens that receives the laser light transmitted through the quarter-wave plate 4 and converts the incident laser light into parallel light. The aberration correcting motor 6 drives the optical axis direction, that is, arrows A and B. It is configured to be displaced in the direction. Spherical aberration is corrected by a displacement operation of the collimating lens 5 in the optical axis direction.

  Reference numeral 7 denotes a rising mirror provided at a position where the laser light transmitted through the collimating lens 5 is incident so as to reflect the incident laser light in the direction of the objective lens 8 made of synthetic resin. It is configured. Reference numeral 9 denotes a front monitor photodetector provided at a position where the laser beam transmitted through the control film 3a provided in the polarization beam splitter 3 is irradiated, and a signal corresponding to the level of the irradiated laser beam. Is output as a monitor signal.

  In such a configuration, the laser light emitted from the laser diode 1 is incident on the objective lens 8 via the diffraction grating 2, the polarization beam splitter 3, the quarter wavelength plate 4, the collimator lens 5, and the raising mirror 7. After that, the signal recording layer L of the optical disk D is irradiated as a spot by the focusing operation of the objective lens 8, but the laser beam irradiated to the signal recording layer L is reflected as return light.

  The return light reflected from the signal recording layer L of the optical disc D enters the control film 3 a of the polarization beam splitter 3 through the objective lens 8, the raising mirror 7, the collimator lens 5, and the quarter wavelength plate 4. Since the return light incident on the control film 3a of the polarization beam splitter 3 in this way is converted into linearly polarized light in the P direction by the phase changing operation by the quarter wavelength plate 4, such return light is It is not reflected by the control film 3a, but is transmitted as control laser light.

  Reference numeral 10 denotes a sensor lens into which the control laser light transmitted through the control film 3a of the polarizing beam splitter 3 is incident. Astigmatism is added to the control laser light in the light receiving portion provided in the photodetector 11 called PDIC. The effect of irradiating with the addition of. The photodetector 11 is provided with a well-known four-divided sensor or the like, and the signal generation operation and astigmatism accompanying the reading operation of the signal recorded on the signal recording layer L of the optical disc D by the main beam irradiation operation. A signal generation operation for performing a focusing control operation by an aberration method and a signal generation operation for performing a tracking control operation by an irradiation operation of two sub beams are configured. Since the configuration and control operation of the light receiving unit for generating such various signals are well known, description thereof will be omitted.

  As described above, the optical system of the optical pickup device according to the present invention is configured. In such a configuration, the objective lens 8 includes four or six objective lenses 8 on a base (not shown) constituting the optical pickup device. A lens holder (not shown) is supported by the supporting wire so as to be able to perform a displacement operation in a direction perpendicular to the signal surface of the optical disc D, that is, a focusing direction, and a displacement operation in the radial direction of the optical disc D, that is, a tracking direction. ).

  Reference numeral 12 denotes a focusing coil provided in a lens holder to which the objective lens 8 is fixed, and the objective lens 8 is displaced in the focusing direction in cooperation with a magnet (not shown) fixed to a base. Has the effect of causing A tracking coil 13 is provided in a lens holder to which the objective lens 8 is fixed, and displaces the objective lens 8 in the tracking direction in cooperation with a magnet (not shown) fixed to the base. Has an effect.

  The configuration of the optical pickup device in which the focusing coil 12 and the tracking coil 13 are incorporated, and the focusing control operation and the tracking control operation by the driving operation of each coil are well known, and the description thereof is omitted.

  Reference numeral 14 denotes an RF signal which is a signal obtained in response to a reading operation of a signal recorded on the signal recording layer of the optical disc D from a sensor which receives the main beam constituting the photodetector 11, and a sensor which receives the main beam. A light detection signal generation circuit that generates a focus error signal, which is a signal obtained according to a laser beam focusing operation, and a tracking error signal, which is a signal obtained according to a laser beam tracking operation, from a sensor that receives a sub beam. is there.

  Reference numeral 15 denotes a laser output detection circuit to which a signal obtained from the front monitor photodetector 9 is input, and is configured to output a signal corresponding to the level of the input signal as a monitor signal.

  A pickup control circuit 16 receives various signals output from the light detection signal generation circuit 14 and the laser output detection circuit 15 and performs various control operations of the optical pickup device based on the signals. Reference numeral 17 denotes a focusing coil drive circuit to which a focus control signal output from the pickup control circuit 16 is input based on a focus error signal generated and output from the photodetection signal generation circuit 14, and a drive signal is supplied to the focusing coil 12. Is configured to supply. As a driving signal supplied from the focusing coil driving circuit 17 to the focusing coil 12, a focus control operation for a direct current signal for displacing and holding the objective lens 8 at an operation position that is a position for performing the focusing operation and a surface shake of the optical disc D is performed. There is a high frequency signal for performing.

  Reference numeral 18 denotes a tracking coil drive circuit to which a tracking control signal output from the pickup control circuit 16 is input based on a tracking error signal generated and output from the light detection signal generation circuit 14. Is configured to supply. The drive signal supplied from the tracking coil drive circuit 18 to the tracking coil 13 includes a tracking control signal that operates to cause the laser spot to follow a signal track provided on the optical disc D and a track that skips a plurality of tracks. There is a jump signal for performing a jump operation.

  Reference numeral 19 denotes a laser diode drive circuit for supplying a drive signal to the laser diode 1, and adjusts the laser output by a control signal output from the pickup control circuit 16 based on a monitor signal obtained from the laser output detection circuit 15. It is configured. An aberration correction motor drive circuit 20 corrects spherical aberration by displacing the collimating lens 5 in the optical axis direction by supplying a drive signal to the aberration correction motor 6, and is controlled by the pickup control circuit 16. It is comprised so that.

Reference numeral 21 denotes a temperature detecting element provided to detect the temperature of the objective lens 8, and is a printed wiring board (for example, composed of a thermistor and incorporating an electric circuit such as the pickup control circuit 16). (Not shown). Such a temperature detection element 21 is disposed close to the objective lens 8 in order to detect the temperature of the objective lens 8.

  A temperature detection circuit 22 detects a temperature based on a signal obtained from the temperature detection element 21 and is configured to output a detection signal to the pickup control circuit 16. Reference numeral 23 denotes an aberration correction data memory circuit in which various data for performing a spherical aberration correction operation, which will be described later, is stored. The pickup control circuit 16 controls the data reading operation and the like.

  Reference numeral 24 denotes a control circuit incorporated in an optical disc apparatus in which the optical pickup device according to the present invention is incorporated. The control circuit 24 outputs various command signals to the optical pickup control circuit 16 and reads them by the optical pickup device. A circuit for demodulating the received data signal or the like is incorporated.

  As described above, the optical pickup device according to the present invention is configured. Next, the operation will be described.

  When an operation for reading a signal recorded on the signal recording layer L provided on the optical disc D is performed, each operation is performed on the pickup control circuit 16 from the control circuit 24 incorporated in the optical disc apparatus. A command signal for execution is output, and a desired drive control signal is supplied from the pickup control circuit 16 to each circuit constituting the optical pickup device. The laser diode drive circuit 19 is supplied with a drive signal capable of obtaining a laser output that is set in advance in order to accurately perform a signal reading operation on the laser diode 1, and a laser having a desired output is supplied from the laser diode 1. Light will be emitted.

  Laser light emitted from the laser diode 1 is incident on the diffraction grating 2 and is separated into a main beam and a sub beam by the diffraction grating portion 2a incorporated in the diffraction grating 2, and in the S direction by the half-wave plate 2b. Converted into linearly polarized light. The laser beam transmitted through the diffraction grating 2 is incident on the polarization beam splitter 3, and most of the laser beam is reflected by the control film 3 a provided on the polarization beam splitter 3 and a part of the laser beam is transmitted. It is done.

  The laser light reflected by the control film 3a provided on the polarizing beam splitter 3 is incident on the quarter-wave plate 4 and converted from linearly polarized light into circularly polarized light and then incident on the collimating lens 5. . The laser light incident on the collimating lens 5 is converted into parallel light and incident on the raising mirror 7.

  The laser light incident on the raising mirror 7 is reflected by the raising mirror 7 in the direction of the objective lens 8. Since the laser light reflected by the raising mirror 7 is incident on the objective lens 8, a focusing operation by the objective lens 8 is performed.

  The operation of condensing the laser light onto the signal recording layer L by the objective lens 8 is performed by, for example, performing an operation of bringing the objective lens 8 closer from a position away from the optical disc D. Such a displacement operation of the objective lens 8 is performed by supplying a driving signal from the focusing coil driving circuit 17 to the focusing coil 12. When the light condensing operation to the signal recording layer L is performed, the signal recording layer L The reflected laser light is incident on the objective lens 8 from the optical disc D side as return light.

  The return light incident on the objective lens 8 is incident on the control film 3 a provided on the polarization beam splitter 3 through the raising mirror 7, the collimating lens 5 and the quarter wavelength plate 4. Since the return light incident on the control film 3a is converted into linearly polarized light in the P direction by the quarter wavelength plate 4, it is not reflected by the control film 3a, and all is used as control laser light. It will be transparent.

  The control laser light, which is the return light transmitted through the control film 3a, is incident on the sensor lens 10 and then astigmatism is added by the sensor lens 10 to the sensor unit provided in the photodetector 11. Irradiated. As a result of irradiating the control laser light to the photodetector 11, a detection signal based on the position and shape change of the irradiation spot of the main beam and the sub beam is obtained from a quadrant sensor or the like incorporated in the photodetector 11. I can do it.

  In such a state, a focus error signal and a tracking error signal generated from the light detection signal generation circuit 14 based on the detection signal obtained from the light detector 11 are input to the pickup control circuit 16. When such a focus error signal and tracking error signal are input to the pickup control circuit 16, a control signal based on each error signal is output to the focusing coil drive circuit 17 and the tracking coil drive circuit 18. As a result, a control signal is supplied from the focusing coil drive circuit 17 to the focusing coil 12, so that the focusing coil 12 is displaced in the focusing direction of the objective lens 8, and laser light is collected in the signal recording layer L. It is possible to perform a focusing control operation that causes light to illuminate. Further, since a control signal is supplied from the tracking coil drive circuit 18 to the tracking coil 13, the displacement operation in the tracking direction of the objective lens 8 is performed by the tracking coil 13, and laser light is provided in the signal recording layer L. It is possible to perform a tracking control operation to follow the signal track.

  As described above, since the focusing control operation and the tracking control operation are performed in the optical pickup device, it is possible to perform the read operation of the signal recorded on the signal recording layer L of the optical disc D. The reproduction signal obtained by such reading operation is obtained by guiding the RF signal generated from the photodetection signal generation circuit 14 to the control circuit 24 and demodulating the data signal by the demodulation circuit incorporated in the control circuit 24. A signal recorded on the optical disc D can be reproduced.

  Further, when the signal reading operation described above is performed, a driving signal that can obtain a desired laser output is supplied from the laser diode driving circuit 19 to the laser diode 1 and the front monitor light is supplied. The monitor signal output from the laser output detection circuit 15 based on the signal obtained from the detector 9 is in the state of being input to the pickup control circuit 16.

  When the monitor signal output from the laser output detection circuit 15 is input to the pickup control circuit 16 in this way, a control signal based on the level of the monitor signal is supplied from the pickup control circuit 16 to the laser diode drive circuit 19. become. Therefore, if the drive signal supplied from the pickup control circuit 16 to the laser diode drive circuit 19 is controlled so as to have a predetermined value, the laser light emitted from the laser diode 1 can be controlled. The output can be automatically controlled to a desired level. Such an operation is called a laser automatic output control operation, and a description thereof will be omitted.

As described above, when the signal readout operation is performed by the optical pickup device, the drive signal is supplied from the laser diode drive circuit 19 to the laser diode 1 and the drive signal from the focusing coil drive circuit 17 to the focusing coil 12 is supplied. With the supply operation and the supply operation of the drive signal from the tracking coil drive circuit 18 to the tracking coil 13, heat is generated from each circuit and the like, and the temperature in the optical pickup device, that is, the environmental temperature rises.

  When the environmental temperature rises, the temperature of the objective lens 8 made of a synthetic resin rises. Therefore, the objective lens 8 is deformed by expansion and has a characteristic that the light collection characteristic changes. When the condensing characteristic of the objective lens 8 changes, spherical aberration occurs, and the condensing characteristic of the laser beam with respect to the signal recording layer L deteriorates.

  As described above, when the temperature of the objective lens 8 rises as the environmental temperature rises, spherical aberration occurs. In the present invention, the collimating lens 5 provided as aberration correction means is used for the aberration correction motor 6. It is configured to be displaced in the optical axis direction by a rotational drive operation. That is, the collimating lens 5 is displaced in the direction of the arrow A or B, which is the optical axis direction, by the rotational driving operation of the aberration correction motor 6, but the displacement position is a spherical surface generated with the temperature change of the objective lens 8. It is configured to be a position for correcting aberrations.

  FIG. 3 shows the relationship between the position of the collimating lens 5 with respect to the temperature change of the objective lens 8, and FIG. 4 is a characteristic diagram showing the relationship between the jitter value and temperature when the collimating lens 5 is displaced. It is. As apparent from the figure, even when the temperature of the objective lens 8 changes, the spherical aberration can be corrected by displacing the collimating lens 5 in the optical axis direction, so that the jitter value can be made constant. That is, the signal reading operation as the optical pickup device can be performed accurately.

  As described above, by correcting the spherical aberration by the movement operation of the collimating lens 5, the operation of reading the signal recorded on the signal recording layer L provided on the optical disc D can be performed in an optimum state.

  As described above, the collimating lens 5 is displaced in the direction of the optical axis based on the temperature obtained from the temperature detecting element 21 so as to perform a correction operation for the spherical aberration caused by the temperature change of the objective lens 8. However, the displacement position of the collimator lens 5 is configured to be set based on the aberration correction data stored in the aberration correction data memory circuit 23.

  FIG. 2 shows a change in temperature when the reproducing operation is performed by the optical disk device. T1 indicated by a solid line indicates a change in the detected temperature detected by the temperature detecting element 21, and T2 indicated by a solid line indicates the detected temperature. The change of the estimated temperature of the objective lens 8 estimated based on it is shown.

  The correction position of the spherical aberration with respect to the temperature change of the collimator lens 5 is set based on the correction data stored in the aberration correction data memory circuit 23, and the correction position is set based on the estimated temperature. It is configured.

  When a normal reproduction operation is performed, the estimated temperature of the objective lens 8 changes in parallel with the detected temperature. However, desired data is retrieved from the signals recorded on the optical disc D and read out. When an operation called “access” is performed, the temperature of the objective lens 8 changes as indicated by a broken line T3.

When the above-described access operation is performed, a tracking jump drive signal is supplied from the tracking coil drive circuit 18 to the tracking coil 13 and a large focus drive is also performed from the focusing coil drive circuit 18 to the focusing coil 12. A signal will be supplied. If such an access operation is frequently performed in a short time, a lot of heat is generated from the tracking coil 13 and the focusing coil 12, and the temperature of the objective lens 8 rapidly increases.

  With such an operation, the temperature of the objective lens 8 rises, but such a temperature rise cannot be detected by the temperature detecting element 21, so that the spherical aberration correction operation cannot be performed accurately.

  In the present invention, when an access operation is performed, the number of track jump operations, the width of a pulse signal that is a track jump drive signal supplied from the tracking coil drive circuit 18 to the tracking coil 13, and the focusing coil drive circuit 17 Correction data for correcting the aberration correction position of the collimating lens 5 based on the level of the focus drive signal supplied to the focusing coil 12 is stored in the aberration correction data memory circuit 23.

  That is, the present invention recognizes the operation of the optical pickup device based on the signal obtained from the pickup control circuit 16 and estimates the temperature change of the objective lens 8 based on the recognized operation, and the estimated temperature change. Based on the above, the correction data stored in the aberration correction data memory circuit 23 is read out. When correction data is read from the aberration correction data memory circuit 23, a control signal based on the correction data is supplied from the pickup control circuit 16 to the aberration correction motor drive circuit 20. As a result, a drive signal is supplied from the aberration correction motor drive circuit 20 to the aberration correction motor 6, and the collimating lens 5 is moved to the correction position by the rotation of the aberration correction motor 6.

  Since the collimating lens 5 is displaced as described above, the spherical aberration can be corrected accurately even if the temperature of the objective lens 8 rises rapidly with the access operation. Therefore, even if a track jump operation is performed in accordance with the access operation, a signal recorded on the optical disc D can be read accurately, so that desired data can be read quickly.

  In this embodiment, the temperature change of the objective lens 8 is estimated by detecting the change of the drive signal supplied to the tracking coil 13 or the change of the drive signal supplied to the focusing coil 12 like the track jump operation. However, it is also possible to estimate the temperature change based on the radial position of the optical disk D of the optical pickup device and the rotational speed of the optical disk D.

  That is, when the optical disk D rotates, an air flow generated along with the rotation hits the optical pickup device, so that the optical pickup device is cooled. The cooling characteristics vary depending on the rotational speed of the optical disc D and whether the optical disc D is on the inner circumference side or the outer circumference side, so that correction data matching the characteristics is stored in the aberration correction data memory circuit 23. You can also Various aberration correction data stored in the aberration correction data memory circuit 23 are read out corresponding to each operation, and the position of the collimating lens 5 is corrected based on the read data, thereby causing the temperature change of the objective lens 8. The spherical aberration can be accurately corrected.

In this embodiment, when a stepping motor is used as the aberration correction motor 6 provided to displace the collimator lens 5, the rotational speed control operation can be performed with high accuracy. That is, since the stepping motor uses a pulse signal as a drive signal, the number of rotations can be set accurately depending on the number of pulses, so that the collimating lens 5 is a spherical surface generated due to the temperature change of the objective lens 8. It can be displaced to a position where the aberration is accurately corrected.

It is a figure which shows one Example of the optical pick-up apparatus which concerns on this invention. It is a figure for demonstrating the relationship between reproduction time and temperature. It is a figure for demonstrating operation | movement of the optical pick-up apparatus which concerns on this invention. It is a figure for demonstrating operation | movement of the optical pick-up apparatus which concerns on this invention. It is a figure for demonstrating the relationship between temperature and spherical aberration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser diode 3 Polarizing beam splitter 5 Collimating lens 6 Aberration correction motor 8 Objective lens 11 Photo detector 14 Photodetection signal generation circuit 16 Pickup control circuit 19 Laser diode drive circuit 20 Aberration correction motor drive circuit 21 Temperature detection element 22 Temperature Detection circuit 23 Aberration correction data memory circuit

Claims (10)

The laser light emitted from the laser diode is guided to an objective lens made of synthetic resin, and the laser beam is condensed on the signal recording layer provided on the optical disc by the focusing operation of the objective lens so as to perform the signal reading operation. And a collimating lens provided in the optical path between the laser diode and the objective lens based on the temperature detected by the temperature detecting element provided to detect the temperature of the objective lens. It is configured to correct spherical aberration by moving in the axial direction, and includes a focusing coil for displacing the objective lens in a direction perpendicular to the signal surface of the optical disc and a tracking coil for displacing the objective lens in the radial direction of the optical disc. Is a spherical aberration correction method for an optical pickup device, and the operation of the optical pickup device Spherical aberration correcting method of an optical pickup apparatus is characterized in that so as to correct the moving position of the collimating lens according. 2. The spherical aberration correction method according to claim 1, wherein the moving position of the collimating lens is corrected in accordance with a drive signal supplied to the tracking coil. 3. The spherical aberration correction method according to claim 2, wherein the movement position of the collimating lens is corrected in accordance with a track jump drive signal supplied to the tracking coil. 4. The spherical aberration correction method according to claim 3, wherein the movement position of the collimating lens is corrected according to the number of times of supply of the track jump drive signal supplied to the tracking coil. 4. The spherical aberration correction method according to claim 3, wherein the moving position of the collimating lens is corrected in accordance with the supply time of the track jump drive signal supplied to the tracking coil. 2. The spherical aberration correction method according to claim 1, wherein the movement position of the collimating lens is corrected in accordance with a drive signal supplied to the focusing coil. 7. The spherical aberration correction method according to claim 6, wherein the moving position of the collimating lens is corrected in accordance with the level of the focus drive signal supplied to the focusing coil. 2. The spherical aberration correction method according to claim 1, wherein the movement position of the collimating lens is corrected in accordance with the movement position of the optical pickup device. 2. The spherical aberration correction method according to claim 1, wherein the moving position of the collimating lens is corrected according to the rotational speed of the optical disk. 2. The moving position of the collimating lens is corrected based on correction data read from an aberration correction data memory circuit in which correction data for correcting the moving position of the collimating lens is stored. Spherical aberration correction method.

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