JP2006073131A - Optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device capable of detecting and controlling tilting by recording/reproducing irradiation light without needing any special additional mechanism and without any reduction in performance. <P>SOLUTION: The optical disk device having tracking control means 11 and 13 for driving a pick-up housing 6 supported to freely move in a disk radial direction with respect to a motor 2 for rotary-driving an optical disk 1 and an objective lens 7-1 supported to freely move in the disk radial direction on the housing to cause a recording/reproducing optical spot radiated to the optical disk to follow around the track of the optical disk, is provided with a lens driving amount detection means 13 for detecting the driving amount of the objective lens with respect to the housing 6, and a push-pull signal detection means 10A for generating a push-pull signal in the radial direction of the optical disk. The output of the push-pull signal detection means 10A is obtained by an acquisition means 14 at timing where the output of the lens driving amount detection means 13 becomes an original point, and an operation regarding the tilting of the disk radial direction is controlled based on the acquisition value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical disc apparatus that performs recording and / or reproduction with respect to an optical disc that is an optical recording medium.

Conventionally, an optical pickup device (also referred to as an optical head device) having a mechanism for preventing spot movement on a light receiving element due to a shift of an objective lens and an optical disk device using the same have been proposed.
For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2002-31966), by providing a mechanism that does not involve an offset component generated due to an optical axis deviation, light that can realize highly accurate tilt detection without providing a new detection member. For the purpose of providing a pickup device, an optical system including at least a laser light source, an objective lens, and a light receiving element for detecting reflected light from the optical disk in a light beam incident on the optical disk, and an optical disk in the light beam In an optical pickup apparatus provided with a correction mechanism for correcting defocusing and deviation from the center of the information track, when the deviation from the center of the information track is corrected, an optical axis deviation of the optical beam with respect to the optical disk is corrected. Optical means for preventing the occurrence of the light receiving element Such as by detecting a tilt signal based on a known signal is described.

  Further, in Patent Document 2 (Japanese Patent Laid-Open No. 9-212891), in the optical head device, an optical axis deviation is prevented from occurring even when the objective lens facing the optical disk is tracked, and a dedicated sensor device. In order to make it possible to detect a disc tilt without providing a light source, a laser light source, a light beam dividing means for dividing the laser light into a main light beam and at least one sub light beam, and a tracking direction of the main light beam and the sub light beam Movable deflecting means for deflecting in the direction perpendicular to the focusing direction and tracking direction, fixed deflecting means for deflecting the main light beam and the sub light flux incident from the movable deflecting means in the focusing direction, and the fixed deflecting means Objective that focuses the main beam incident on the optical disc on the track of the optical disc and the sub beam on the track gap And a plurality of light receiving elements for individually detecting a main light beam and a sub light beam reflected by the optical disk, and a push-pull signal generating means for individually generating a push-pull signal corresponding to a tracking error from the plurality of detection results And tracking signal generating means for generating a tracking signal by subtracting the push-pull signal between the main light beam and the sub light beam, and the movable deflecting means and the objective lens are integrally controlled in the tracking direction corresponding to the tracking signal. There is described an optical head device or the like characterized by including a movement interlocking mechanism that performs the above and a tilt signal generation unit that adds a plurality of push-pull signals to generate a tilt signal corresponding to the tilt of the optical disc.

Japanese Patent Laid-Open No. 2002-31966 JP 9-212891 A

  In the tilt correction in the conventional optical disc apparatus, an optical tilt sensor is provided separately from the optical pickup for recording and / or reproduction, and the tilt operating means is controlled based on the detected value. In this configuration, since the light irradiation position for recording and / or reproduction is different from the light irradiation position for disc tilt detection, a tilt difference due to the detection position and a difference between the detection direction and the correction direction are errors. The inventions described in Patent Document 1 and Patent Document 2 described above detect tilt by using irradiation light for recording and / or reproduction, and prevent these errors from occurring. In other words, the push-pull signal is offset according to the lens shift or the disc tilt, and is combined with a mechanism for removing the offset accompanying the lens shift. As a mechanism for removing the offset due to the lens shift, for example, a mechanism for driving the objective lens and the mirror integrally as shown in FIG. 3 of Patent Document 2 has been proposed. If an objective lens actuator intended to do so is additionally mounted with a mirror having a mass larger than that of the objective lens, the acceleration performance will be greatly reduced.

  The present invention has been made in view of the above circumstances, and can detect and control tilt with irradiation light for recording and / or reproduction without requiring a special additional mechanism and causing no deterioration in performance. It is an object of the present invention to provide an optical disc device having a configuration that can be used.

In order to achieve the above object, the present invention employs the following means.
The first means of the present invention includes a pickup housing supported so as to be movable in the radial direction of the optical disk with respect to a spindle motor that rotationally drives the optical disk, and supported on the pickup housing so as to be movable in the radial direction of the optical disk. In the optical disk apparatus having a tracking control means for driving a recording or reproducing light spot irradiated on the optical disk to follow the track center of the optical disk by driving the objective lens, the driving amount of the objective lens relative to the pickup housing A lens drive amount detection means for detecting the push-pull signal detection means for generating a push-pull signal in the radial direction of the optical disc from the light reflected from the optical disc and passing through the objective lens, and the lens drive amount When the output of the detection means is the origin (neutral point) The output of the push-pull signal detection means is acquired by the timing, and the operation related to the tilt in the radial direction of the optical disk (hereinafter referred to as radial tilt) is controlled based on the acquired value (claim 1). ).

  The second means of the present invention is a pickup housing supported so as to be movable in the radial direction of the optical disk with respect to a spindle motor that rotationally drives the optical disk, and supported on the pickup housing so as to be movable in the radial direction of the optical disk. In the optical disk apparatus having a tracking control means for driving a recording or reproducing light spot irradiated on the optical disk to follow the track center of the optical disk by driving the objective lens, the driving amount of the objective lens relative to the pickup housing A lens drive amount detection means for detecting the push-pull signal detection means for generating a push-pull signal in the radial direction of the optical disc from the light reflected from the optical disc and passing through the objective lens, and the lens drive amount The average output value of the detection means is the origin (neutral point) That timing to get the average output of the push-pull signal detecting means, and performs control operations related to the radial tilt based on the acquired value (claim 2).

According to a third means of the present invention, in the optical disk device of the second means, the output average value of the lens driving amount detection means and the output average value of the push-pull signal detection means are one rotation or more than one rotation of the optical disk or It is a section average value that is an integral multiple of one revolution (claim 3).
According to a fourth means of the present invention, in the optical disk apparatus of the second means, the output average value of the lens driving amount detection means and the output average value of the push-pull signal detection means are frequencies equal to or higher than the rotation frequency of the optical disk. It is a signal from which components are removed (claim 4).

According to a fifth means of the present invention, in the optical disc apparatus of any one of the first to fourth means, the optical disc apparatus has a radial tilt operation means for correcting an influence of a radial tilt of the optical disc on the quality of the light spot, The operation amount of the radial tilt operation means is controlled based on the acquired value (claim 5).
According to a sixth means of the present invention, in the optical disc apparatus of any one of the first to fourth means, there is an optical pickup tilting means for tilting the pickup housing, and the acquired value is at the origin (neutral point). The amount of inclination of the optical pickup is controlled so as to approach (claim 6).

The seventh means of the present invention has objective lens tilting means for tilting the objective lens in the optical disk device of any one of the first to fourth means, and the objective lens tilt amount is an amount corresponding to the acquired value. (Claim 7).
Further, an eighth means of the present invention is the optical disc apparatus according to any one of the first to fourth means, which is installed in an optical path between the light source and the objective lens, and operates the wavefront of the light beam passing therethrough. Coma aberration adding means for adding coma aberration to the light spot is provided, and the coma aberration adding amount of the coma aberration adding means is controlled to an amount corresponding to the acquired value.

According to a ninth means of the present invention, in the optical disk apparatus according to any one of the first to fourth means, the tilt sensor is installed in the pickup housing and detects a relative angle between the pickup and the optical disk, and the acquired value The tilt sensor output is corrected based on the above (claim 9).
According to a tenth means of the present invention, in the optical disk apparatus of any one of the first to ninth means, the lens driving amount detecting means detects the objective lens driving amount based on a current or voltage for driving the objective lens. (Claim 10).

  In the optical disk device of the first means, the push-pull signal that causes an offset due to the lens shift and the disk tilt is acquired at the timing when the lens shift becomes 0, so that the disk tilt can be detected without providing an additional mechanism.

In the optical disk device of the second means, the average value of the push-pull signal is acquired at the timing when the lens shift becomes 0 on average, so that the detection error due to the acquisition timing shift can be reduced.
In addition, in the optical disk device of the third means, in addition to the effect of the second means, the average value of the section of the optical disk is one rotation, one rotation or more or an integral multiple of one rotation, so that the detection error due to the eccentricity of the optical disk Can be removed.
Further, in the optical disk device of the fourth means, in addition to the effect of the second means, the component below the rotation frequency of the optical disk is extracted by the filter, so that the vibration center of various signals is extracted without determining the average interval. be able to.

In the optical disk device of the fifth means, in addition to the effect of any one of the first to fourth means, the offset of the push-pull signal accompanying the inclination of the optical disk is detected, and the adverse effect of the inclination of the optical disk is corrected based on the detected value. Therefore, it is possible to prevent the deterioration of the light spot due to the inclination of the optical disk.
In addition, in the optical disk device of the sixth means, in addition to the effect of any one of the first to fourth means, the offset of the push-pull signal accompanying the inclination of the optical disk is detected and the detection value of the optical pickup is reduced. Since the tilt attitude is controlled, it is possible to keep the optical pickup and the optical disc in parallel following the change in the tilt amount of the optical disc.

In the optical disk device of the seventh means, in addition to the effect of any one of the first to fourth means, the offset of the push-pull signal accompanying the inclination of the optical disk is detected, and the objective lens inclination amount is controlled according to the detected value. Therefore, the coma aberration accompanying the tilt of the optical disc can be canceled following the change in the tilt amount of the optical disc.
In the optical disk device of the eighth means, in addition to the effect of any one of the first to fourth means, the offset of the push-pull signal accompanying the inclination of the optical disk is detected and added to the irradiation light according to the detected value. Since the amount of wavefront aberration is controlled, coma aberration associated with the tilt of the optical disc can be canceled following the change in the tilt amount of the optical disc.

In the optical disk device of the ninth means, in addition to the effect of any one of the first to fourth means, the offset of the push-pull signal accompanying the tilt of the optical disk is frequently detected to correct the offset of the tilt sensor. Can be prevented from accumulating and increasing the offset fluctuation.
Further, in the optical disk apparatus of the tenth means, in addition to the effect of any one of the first to ninth means, the objective lens driving amount is detected based on the objective lens driving signal, so that an objective lens position sensor is provided separately. The timing at which the lens shift becomes zero can be detected.

  Hereinafter, the configuration, operation and action of the present invention will be described in detail based on the embodiments shown in the drawings.

Example 1
FIG. 1 is a schematic configuration diagram of an optical disc apparatus showing an embodiment of the present invention. In FIG. 1, a spindle motor 2 that rotates an optical disk 1 that is an optical recording medium is fixed to a fixed base 3. The rotating base 4 is pivotally supported on the fixed base 3 by a fulcrum 4-1 and can be tilted in the radial direction of the optical disk 1. The tilt attitude of the rotation base 4 in the radial direction of the optical disk is operated by the tilt operating means 5. The pickup housing 6 is supported by a seek shaft (not shown) and a lead screw 8-1 so as to be movable in the radial direction of the optical disc 1. The lead screw 8-1 is integrated with the rotating shaft of the traverse motor 8, and the pickup housing 6 is driven in the radial direction of the optical disc 1 by rotating the traverse motor 8. The objective lens actuator 7 movably supports the objective lens 7-1 on the pickup housing 6 and drives it in the vertical direction and the radial direction of the surface of the optical disc 1. The pickup housing 6 includes a light source 6-1, a diffractive optical element (a diffraction grating, a hologram, a polarizing diffraction grating, a polarizing hologram, etc.) 6-2, a coupling lens 6-3, a beam splitter 6-4, and a detection lens 6. An optical system including -5 and the light receiving element 6-6 is fixed.

  The recording and / or reproducing light emitted from the light source 6-1 is separated into three light beams of 0th-order diffracted light and ± 1st-order diffracted light by the diffractive optical element 6-2, and each light beam is coupled to the coupling lens 6-3. Then, the light is condensed on the optical disc 1 through the beam splitter 6-4 and the objective lens 7-1 and irradiated as a minute light spot. The light reflected from the optical disk 1 is transmitted through the objective lens 7-1, branched off from the optical path by the beam splitter 6-4, passes through the detection lens 6-5, and enters the light receiving element 6-6.

  The light receiving element 6-6 is a multi-divided light receiving element in which the light receiving surface is divided into multiple parts. The push-pull signal detection means 10A calculates the photoelectric conversion output from each light receiving surface of the light receiving element 6-6, which will be described later. A pull signal (MPP) and a sub push-pull signal (SPP) are generated. A track error detection means (for example, a differential amplifier) 10B generates a track error signal (TE) based on the difference between the main push-pull signal (MPP) and the sub push-pull signal (SPP), and actuator control means (lens driving amount). (Detection means) 13 generates a tracking drive signal (TD) so that the track error signal (TE) becomes small, and the objective lens actuator 7 moves the objective lens 7-1 in the radial direction of the optical disc 1 by the tracking drive signal (TD). To drive. On the other hand, a low frequency component equal to or lower than the rotation frequency of the optical disc 1 is generated from the tracking drive signal (TD) by a low pass filter (LPF) and output to the traverse control means 11 and the MPP acquisition means 14. The traverse control means 11 drives the traverse motor 8 in accordance with the low frequency component of the tracking drive signal (TD). From the main push-pull signal (MPP), a low-frequency component lower than the rotation frequency of the optical disc 1 is generated by a low-pass filter (LPF) and output to the MPP acquisition means 14. The MPP acquisition means 14 monitors the low frequency component of the tracking drive signal (TD), and only during the period when the low frequency component output value of the tracking drive signal (TD) indicates a predetermined range near 0 (the origin (neutral point)). The low frequency component of the main push-pull signal (MPP) is acquired and output to the tilt control means 12. The tilt control means 12 drives the tilt operation means 5 so that the low frequency component of the main push-pull signal (MPP) becomes small.

FIG. 2 is a diagram showing a light spot irradiated on the optical disc 1 and a light spot (light reception spot) irradiated on the light receiving surface of the light receiving element 6-6. The tracking error signal (TE) is detected by the differential push-pull method. ) Is generated. In this description, the push-pull signal generated from the light receiving spot corresponding to the 0th-order diffracted light is the main push-pull signal (MPP), the push-pull signal generated from the light receiving spot corresponding to the + 1st-order diffracted light and the −1st-order diffracted light. The addition average with the push-pull signal generated from the received light spot is called a sub push-pull signal (SPP). The main push-pull signal (MPP), sub push-pull signal (SPP), and track error signal (TE) are signals obtained by the following calculation.
MPP = (a−b) / (a + b)
SPP = {(c−d) / (c + d) + (e−f) / (e + f)} / 2
TE = MPP-SPP

Each push-pull signal is normalized by sum signals (a + b), (c + d), and (e + f), but in the circuit configuration of FIG. 2, an equivalent signal is generated by multiplying gains G1 and G2.
MPP = (a−b)
SPP = G2 × {(cd) + G1 (ef)}
TE = MPP-SPP
G1 = (c + d) / (e + f)
G2 = (a + b) / (c + d) / 2

  A groove (track) is spirally formed on the optical disc 1, and in this description, the concave portion of the groove (track) is called a groove and the convex portion is called a land. Data is recorded in the groove. The distance Pg from the center of the groove to the adjacent groove center is called the groove pitch. In this embodiment, the groove pitch Pg is set to 0.74 μm.

  The light reflected from the optical disk 1 includes a track error component due to diffraction and interference, the intensity distribution in the radial direction is symmetric at the irradiation position at the groove center and the land center, and is untargeted at other irradiation positions. The change of the track error component in each push-pull signal becomes a sine wave having one cycle from the center of the groove to the adjacent groove center when the irradiation light is scanned in the track crossing direction. Since ± 1st-order diffracted light is irradiated to a position away from the irradiation position of 0th-order diffracted light by ± 1/2 groove pitch, the track error component change of the sub push-pull signal (SPP) is the reverse of the main push-pull signal (MPP). Become a phase.

  On the other hand, each spot position on the light receiving element 6-6 changes due to the shift of the objective lens 7-1 as shown in FIG. 3 or the radial tilt (radial tilt) of the optical disc 1 as shown in FIG. Accordingly, an offset corresponding to the shift of the objective lens 7-1 and the tilt (radial tilt) of the optical disc 1 is equally generated in each push-pull signal. FIG. 5 is a diagram showing various signals output when the track is traversed in a state where the shift of the objective lens 7-1 and the tilt (radial tilt) of the optical disc 1 are generated. The main push-pull signal (MPP) and the sub push-pull signal (SPP) have a relationship in which the track error component is opposite in phase and the offset is the same amount. The track error signal (TE) generated by subtracting the sub push-pull signal (SPP) from the main push-pull signal (MPP) has an offset component removed, and becomes a signal containing only the track error component.

FIG. 6 is a diagram showing various signals when the optical spot apparatus shown in FIG. 1 makes the focused spot of 0th-order diffracted light follow the groove in accordance with the track error signal. A solid line is a tracking drive signal (TD) and a main push-pull signal (MPP), and each broken line is a low-frequency component signal extracted by a low-pass filter (LPF).
For simplicity, the movement sensitivity of the objective lens 7-1 with respect to the tracking drive signal (TD) is represented as 1 mm / V, and the offset sensitivity of the main push-pull signal with respect to the objective lens shift amount is represented as 1 V / mm.

  Since the optical disk 1 is decentered, the tracking drive signal (TD) that causes the objective lens 7-1 to follow the groove becomes a sine wave of one cycle by one rotation of the optical disk 1. In FIG. 6, a shake of ± 0.08 mm occurs in one rotation. Since the groove is formed in a spiral shape and the groove pitch is set to 0.74 μm, the vibration center increases by 0.74 μm to the outer peripheral side by one rotation of the optical disk 1. In the state shown by the arrow A in FIG. 6, the objective lens 7-1 vibrates around a position shifted by 0.05 mm toward the inner peripheral side of the optical disc 1 with respect to the pickup housing 6. In the state indicated by the arrow B after about 135 rotations, the vibration center is increased by 0.1 mm, and the vibration center is shifted to the outer peripheral side of the optical disc 1 by 0.05 mm with respect to the pickup housing 6. The low frequency component of the tracking drive signal (TD) is proportional to the change of the vibration center, and the traverse control means 11 generates a drive signal corresponding to the low frequency component of the tracking drive signal (TD) and sends it to the traverse motor 8. Applied. When the applied amount increases to an amount corresponding to a state in which the vibration center of the objective lens 7-1 is shifted by 0.05 mm toward the outer peripheral side with respect to the pickup housing 6, the traverse motor 8 is driven by one resolution, and the pickup housing 6 is It is driven 0.1 mm toward the outer periphery. When the pickup housing 6 is driven 0.1 mm toward the outer peripheral side of the optical disc 1, the vibration center of the objective lens 7-1 is shifted to the inner peripheral side of the optical disc 1 by 0.05 mm with respect to the pickup housing 6.

  The MPP acquisition means 14 monitors the low frequency component output of the tracking drive signal (TD), and when the output value is within ± 0.01 V (± 0.01 mm phase, etc.), the low frequency component output of the main push-pull signal (MPP) is output. Is output to the tilt control means 12. The tilt control means 12 drives the tilt operation means 5 so that the low frequency component output of the main push-pull signal (MPP) approaches the initial value (0 V in this embodiment). In the state where the low frequency component output of the tracking drive signal (TD) is ± 0.01 V, the objective lens shift component affects only the ± 0.01 mm phase or the like on the low frequency component output of the main push-pull signal (MPP). When a large offset is acquired, most of the offset is due to the tilt (radial tilt) of the optical disc 1. Therefore, if the tilt operation means 5 is driven so that the offset is reduced, the relative tilt between the optical disc 1 and the pickup housing 6 is corrected.

  The low frequency component output of the tracking drive signal (TD) reaches −0.01 V at the point indicated by arrow C in FIG. 6, and the tilt operation is started. When the tilt operation is started, the low frequency component output of the main push-pull signal (MPP) approaches 0V, and the vibration center of the main push-pull signal (MPP) also approaches 0V. When the low frequency component output of the tracking drive signal (TD) reaches +0.01 V (point indicated by arrow D in FIG. 6), the tilt operation is interrupted and the posture of the pickup housing 6 is maintained in the last state. When the point indicated by arrow E is reached and the low frequency component output of the tracking drive signal (TD) reaches −0.01 V again, the tilt operation is resumed and the low frequency component output of the tracking drive signal (TD) is +0. Continue to the point of arrow F reaching .01V.

  The initial value of the low frequency component output of the main push-pull signal (MPP) is a state in which the pickup housing 6 is parallel to the optical disc 1 and the objective lens 7-1 is not driven, that is, the objective lens shift is zero. This is the low-frequency component output value of the main push-pull signal (MPP) output at. If a value other than 0V is the initial value due to an assembly error or the like, the value is stored and the low frequency component output of the main push-pull signal (MPP) during the tilt operation approaches the stored value. Control.

  In the embodiment of the optical disk apparatus shown in FIG. 1, the low frequency component output of the main push-pull signal (MPP) is acquired by the MPP acquisition means 14, and tilt control is performed. However, the optical disk of the embodiment shown in FIG. As in the apparatus, the low-frequency component output of the lens position signal (LP) generated from the sum of the main push-pull signal (MPP) and the sub push-pull signal (SPP) is obtained instead using the LP acquisition means 15. However, the same effect can be obtained. Similar effects can be obtained by using the SPP acquisition unit 16 instead of the low-frequency component output of the sub push-pull signal (SPP) as in the optical disc apparatus of the embodiment shown in FIG.

  In the optical disk apparatus of the embodiment shown in FIG. 1, the low frequency component of the tracking drive signal (TD) and the main push-pull signal (MPP), that is, the vibration center is extracted using a low pass filter (LPF). An equivalent signal can also be extracted by calculating the section average of the drive signal (TD) and the main push-pull signal (MPP). Since most of the vibrations of the tracking drive signal (TD) and the main push-pull signal (MPP) are a disk eccentric component of one cycle by one rotation of the optical disk, averaging is performed by setting the section length for obtaining the average to be one rotation or more of the optical disk. The error can be reduced. Further, by setting the section length to an integral multiple of one rotation of the optical disk, higher accuracy can be achieved.

(Example 2)
Next, FIG. 9 is a schematic configuration diagram of an optical disc apparatus showing another embodiment of the present invention. In the optical disk apparatus of the embodiment of FIG. 9 with respect to the optical disk apparatus of the embodiment shown in FIG. 1, the rotation base 4 of FIG. 1 is integrated with the fixed base 3, and the tilt posture of the rotation base 4 is manipulated. The liquid crystal tilt operating element 6-7 for operating the wavefront of the transmitted light beam is mounted on the pickup housing 6, and the liquid crystal tilt operating element 6-7 is moved by the tilt control means 12 instead. To control, is different.

  In the optical disk apparatus of the embodiment of FIG. 9, the MPP acquisition means 14 acquires the low frequency component of the main push-pull signal (MPP) and outputs it to the tilt control means 12 as in the embodiment of FIG. The tilt control means 12 drives the liquid crystal tilt operation element 6-7 with a drive amount corresponding to the output of the MPP acquisition means 14. The output of the MPP acquisition means 14 represents the amount of tilt of the optical disc 1, and the amount of coma increases with the amount of tilt. By adding a wavefront aberration that cancels the coma aberration by the liquid crystal tilt operation element 6-7, it is possible to prevent the deterioration of the focused spot due to the coma aberration.

FIG. 10 is a diagram showing various signals when the optical spot apparatus shown in FIG. 9 causes the focused spot by the 0th-order diffracted light to follow the groove in accordance with the track error signal. A solid line is a tracking drive signal (TD) and a main push-pull signal (MPP), and each broken line is a low-frequency component signal extracted by a low-pass filter (LPF).
Unlike the similar signal (FIG. 6) in the optical disc apparatus of the embodiment of FIG. 1, the signal (FIG. 10) in the optical disc apparatus of the embodiment of FIG. Although the center of vibration does not change, the driving amount of the liquid crystal tilt operating element 6-7 is operated in accordance with the amount of acquisition of the vibration center, so that the coma aberration can be corrected.

(Example 3)
Next, FIG. 11 is a schematic configuration diagram of an optical disc apparatus showing still another embodiment of the present invention. In contrast to the optical disk apparatus of the embodiment shown in FIG. 9, in the optical disk apparatus of the embodiment of FIG. 11, there is no liquid crystal tilt operating element 6-7, and the objective lens 7-1 can be tilted in the radial direction of the optical disk 1. The objective lens actuator 7 is configured, and the objective is that a tilt operation motor (not shown) for operating the tilt amount is provided in the objective lens actuator 7.

In the optical disk apparatus of the embodiment of FIG. 11, the MPP acquisition means 14 acquires the low frequency component of the main push-pull signal (MPP) and outputs it to the tilt control means 12 as in the embodiment of FIG. The tilt control means 12 drives a tilt operation motor (not shown) with a drive amount corresponding to the output of the MPP acquisition means 14, and the objective lens 7-1 is tilted. Since the coma aberration is also generated by the inclination of the objective lens 7-1, the coma aberration that cancels the coma aberration generated by the inclination of the optical disk 1 is added by the inclination of the objective lens 7-1, thereby preventing the deterioration of the focused spot. be able to.
Further, various signals when the focused spot by the 0th-order diffracted light follows the groove according to the track error signal are as shown in FIG. 10 as in the embodiment of FIG.

Example 4
Next, FIG. 12 is a schematic configuration diagram of an optical disc apparatus showing still another embodiment of the present invention. In the optical disk apparatus of the embodiment shown in FIG. 12, unlike the optical disk apparatus of the embodiment of FIG. 11, a tilt sensor 9 that optically detects the relative tilt angle between the pickup housing 6 and the optical disk 1 is mounted on the pickup housing 6. Yes. Then, a gain (G3) is applied so that the output sensitivity of the tilt sensor 9 with respect to the tilt (radial tilt) of the optical disc 1 is equal to the offset sensitivity of the main push-pull signal (MPP) with respect to the tilt (radial tilt) of the optical disc 1. .

The offset cancel amount storage unit 17 stores a cancel value, and the cancel value from the offset cancel amount storage unit 17 and the detection signal of the tilt sensor 9 are input to the tilt control unit 12 via the differential amplifier. The tilt control means 12 drives a tilt operation motor (not shown) of the objective lens actuator 7 in accordance with a signal obtained by subtracting a cancel value from the detection signal of the tilt sensor 9.
Similarly to the embodiment of FIG. 1, the MPP acquisition means 14 acquires the low frequency component of the main push-pull signal (MPP). The offset cancellation amount storage means 17 subtracts the low frequency component acquisition value of the main push-pull signal (MPP) from the output value of the tilt sensor 9 and replaces the stored cancellation value with the subtraction result. That is, every time the MPP acquisition unit 14 acquires a low frequency component of the main push-pull signal (MPP), the offset cancellation amount storage unit 17 updates the cancel value.

  FIGS. 13A and 13B are views showing an example of the tilt sensor 9 of the optical disc apparatus shown in FIG. The light emitted from the light source 9-1 is converted into parallel light by the lens 9-2 and irradiated onto the optical disc 1. The light reflected from the optical disk 1 is condensed by the lens 9-2 and is incident on the dividing line of the two-divided light receiving element 9-3. Since the spot on the two-divided light receiving element 9-3 is moved by the inclination of the optical disc 1, the inclination of the optical disc can be detected by the difference signal output of the two-divided light receiving element 9-3. The detection offset of the tilt sensor 9 easily fluctuates due to a change in distance to the optical disc 1 and a change in reflectance of the optical disc 1. In the optical disc apparatus of the embodiment shown in FIG. 12, since the offset cancel value is frequently updated by the low frequency component of the main push-pull signal (MPP), it can be prevented that the offset fluctuation accumulates and becomes large. Further, since the output of the tilt sensor 9 is continuous, the tilt correction operation can be continuously performed.

In each of the embodiments described above, the tilt component signal of the optical disk 1 included in the push-pull signal is extracted and used to improve the quality of the light spot irradiated onto the optical disk 1. Any operation related to 1 tilt (radial tilt) can be used.
For example, it is possible to prevent deterioration in recording or reproduction quality by switching the rotation speed of the optical disc in accordance with the tilt component signal of the optical disc extracted by the low frequency component of the main push-pull signal (MPP).

Since the recording or reproduction quality is improved when the rotation speed of the optical disk is lowered, it is possible to compensate for the deterioration of the recording or reproduction quality caused by the inclination of the optical disk.
Further, by controlling the output light output of the light source according to the tilt component signal of the optical disk extracted by the low frequency component of the main push-pull signal (MPP) at the time of recording, it is possible to prevent the recording quality from deteriorating. As the optical disc is tilted, the actual efficiency of the recording irradiation light on the optical disc surface is reduced and the recording quality is deteriorated. However, if the light emission output is increased, the reduction in the actual efficiency can be compensated.

Further, in an apparatus in which the defocus detection signal is offset according to the tilt of the optical disc, the defocus detection signal is corrected according to the tilt component signal of the optical disc extracted by the low frequency component of the main push-pull signal (MPP). Thus, an accurate defocus value can be obtained.
In addition, when the tilt component signal of the optical disk extracted by the low frequency component of the main push-pull signal (MPP) during recording is monitored and the allowable value is exceeded, the recording operation is stopped, and data is transferred to a poor optical disk having a large tilt amount. It is possible to prevent data from being lost by moving.

  As described above, according to the present invention, a tilt can be detected and controlled by irradiation light for recording and / or reproduction without requiring a special additional mechanism and causing no deterioration in performance. An optical disc apparatus having the configuration can be realized. Therefore, according to the present invention, a compact, low-cost and high-performance optical disk device can be realized, and a high-speed optical disk device such as a CD (compact disk) system, a DVD (digital versatile disk) system, or a blue semiconductor laser is used. It can be used for various optical disk devices such as a density optical disk device. In addition, according to the present invention, a compact and compact optical disk device can be realized, so that it can be suitably used as an optical disk device mounted on a desktop or notebook personal computer, and can be used in a portable display-integrated optical disk device or the like. Can also be suitably used.

1 is a schematic configuration diagram of an optical disc apparatus showing an embodiment of the present invention. FIG. 2 is a diagram simultaneously showing a light spot irradiated on an optical disk and a light spot (light reception spot) irradiated on a light receiving surface of a light receiving element in the optical disk apparatus shown in FIG. 1. FIG. 2 is a diagram showing a state in which a light spot position on a light receiving element changes due to a shift of an objective lens in the optical disc apparatus shown in FIG. 1. FIG. 2 is a diagram illustrating a state in which a light spot position on a light receiving element changes due to an inclination of the optical disk in the optical disk apparatus illustrated in FIG. 1. In the optical disk apparatus shown in FIG. 1, the main push-pull signal (MPP), the sub push-pull signal (SPP), and the track error that are output when the track is traversed while the objective lens is shifted and the optical disk is tilted. It is the figure which showed the signal (TE). FIG. 2 is a diagram showing a tracking drive signal (TD) and a main push-pull signal (MPP) when a focused spot by zero-order diffracted light is made to follow a groove in accordance with a track error signal in the optical disc apparatus shown in FIG. It is a schematic block diagram of the optical disk apparatus which shows another Example of this invention. It is a schematic block diagram of the optical disk apparatus which shows another Example of this invention. It is a schematic block diagram of the optical disk apparatus which shows another Example of this invention. FIG. 10 is a diagram showing a tracking drive signal (TD) and a main push-pull signal (MPP) when a focused spot by zero-order diffracted light is caused to follow a groove in accordance with a track error signal in the optical disc apparatus shown in FIG. 9. It is a schematic block diagram of the optical disk apparatus which shows another Example of this invention. It is a schematic block diagram of the optical disk apparatus which shows another Example of this invention. It is the figure which showed an example of the tilt sensor of the optical disk apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Optical disk 2: Spindle motor 3: Fixed base 4: Rotation base 4-1: Supporting point 5: Tilt operation means 6: Pickup housing 6-1: Light source 6-2: Diffractive optical element 6-3: Coupling lens 6 -4: Beam splitter 6-5: Detection lens 6-6: Light receiving element 6-7: Liquid crystal tilt operating element 7: Objective lens actuator 7-1: Objective lens 8: Traverse motor 8-1: Lead screw 9: Tilt sensor 10A: Push-pull signal detection means 10B: Track error detection means 11: Traverse control means 12: Tilt control means 13: Actuator control means (lens drive amount detection means)
14: MPP acquisition means 15: LP acquisition means 16: SPP acquisition means 17: Offset cancellation amount storage means

Claims (10)

Driving a pickup housing supported so as to be movable in the radial direction of the optical disk with respect to a spindle motor that rotationally drives the optical disk, and an objective lens supported so as to be movable in the radial direction of the optical disk on the pickup housing; In an optical disc apparatus having tracking control means for causing a recording or reproduction light spot irradiated on the optical disc to follow the track center of the optical disc,
Lens drive amount detection means for detecting the drive amount of the objective lens with respect to the pickup housing, and push-pull signal detection for generating a push-pull signal in the radial direction of the optical disc from the light reflected from the optical disc and passing through the objective lens And the output of the push-pull signal detecting means is acquired at a timing when the output of the lens driving amount detecting means becomes the origin (neutral point), and the optical disc is tilted in the radial direction (hereinafter referred to as the following). An optical disc apparatus that controls operations related to radial tilt). Driving a pickup housing supported so as to be movable in the radial direction of the optical disk with respect to a spindle motor that rotationally drives the optical disk, and an objective lens supported so as to be movable in the radial direction of the optical disk on the pickup housing; In an optical disc apparatus having tracking control means for causing a recording or reproduction light spot irradiated on the optical disc to follow the track center of the optical disc,
Lens drive amount detection means for detecting the drive amount of the objective lens with respect to the pickup housing, and push-pull signal detection for generating a push-pull signal in the radial direction of the optical disc from the light reflected from the optical disc and passing through the objective lens And an average output value of the push-pull signal detection means is acquired at a timing when the output average value of the lens driving amount detection means becomes an origin (neutral point). An optical disc apparatus that controls operation. The optical disk apparatus according to claim 2, wherein
The average output value of the lens driving amount detection means and the average output value of the push-pull signal detection means are average values of one or more rotations of the optical disk or an integral multiple of one rotation. . The optical disk apparatus according to claim 2, wherein
The optical disk apparatus characterized in that the output average value of the lens driving amount detection means and the output average value of the push-pull signal detection means are signals from which frequency components equal to or higher than the rotation frequency of the optical disk are removed. In the optical disc device according to any one of claims 1 to 4,
An optical disc apparatus comprising: a radial tilt operation unit that corrects an influence of a radial tilt of the optical disc on the quality of the light spot, and controlling an operation amount of the radial tilt operation unit based on the acquired value. In the optical disc device according to any one of claims 1 to 5,
An optical disc apparatus comprising optical pickup tilting means for tilting the pickup housing, and controlling an optical pickup tilt amount so that the acquired value approaches an origin (neutral point). In the optical disc device according to any one of claims 1 to 6,
An optical disc apparatus comprising an objective lens tilting unit for tilting the objective lens, and controlling an amount of tilt of the objective lens to an amount corresponding to the acquired value. In the optical disc device according to any one of claims 1 to 7,
A coma aberration adding unit that is installed in an optical path from the light source to the objective lens and that manipulates the wavefront of the light beam passing therethrough to add coma aberration to the light spot. The coma aberration adding amount of the coma aberration adding unit Is controlled to an amount corresponding to the acquired value. In the optical disc device according to any one of claims 1 to 8,
An optical disk apparatus, comprising: a tilt sensor that is installed in the pickup housing and detects a relative angle between the pickup and the optical disk, and corrects a tilt sensor output based on the acquired value. In the optical disc device according to any one of claims 1 to 9,
The optical disk apparatus according to claim 1, wherein the lens driving amount detecting means detects the objective lens driving amount based on a current or voltage for driving the objective lens.

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