JP2006318555A - Tilt detector, optical pickup device, and optical disk drive unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tilt detector capable of highly accurately detecting optical disk tilting in an optical disk drive unit. <P>SOLUTION: By using an objective lens drive unit 4 capable of driving an objective lens 1 in focusing, tracking and tilting directions by a driving circuit formed by arranging a drive coil 5 and a driving magnet 6 to face each other with a certain gap, a tilt detection optical system for passing the tilt detection beam B of the optical disk in the tracking-direction center of the gap between the drive coil 5 and the driving magnet 6 is installed not to interfere with a recording/reproducing optical system. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tilt detection apparatus that detects the tilt of an optical disk in an optical disk drive apparatus.

  When the optical disk is tilted, coma aberration occurs in the light spot collected on the optical disk, and the signal quality deteriorates. As the wavelength of a light beam is shortened to increase the density of the optical disk, the degree of deterioration increases if other conditions are the same. In particular, when the wavelength is shortened without changing the disk substrate thickness, the optical disk The amount of fluctuation in the circumference exceeds the target specification for tilt, and real-time tilt detection and real-time closed tilt correction are required.

  In order to correct the tilt in real time in response to fluctuations in the circumference of the optical disc, in terms of its responsiveness, the entire seek rail that is the guide mechanism on the optical pickup side or a mechanical method that tilts the optical disc can be used. In addition, correction means using liquid crystal cannot be used in terms of its response speed.

  As an effective method, a three-axis or four-axis actuator that can drive an objective lens that focuses a light beam on an optical disk in a focusing direction and a tracking direction and can be driven in one or two axes in a tilt direction is used. There is a method. In order to correct the tilt by controlling the drive in real time, it is necessary to detect the tilt in real time. As one of the tilt detection methods, the optical disc tilt and the objective lens tilt are individually set. There is a method of detecting and obtaining a relative tilt between the optical disk and the objective lens from the difference between them. In order to detect the tilt of the optical disc, it is better to place the sensor near the objective lens as much as possible considering the influence of the warp of the optical disc. However, it is difficult to install the sensor near the objective tilt sensor due to layout restrictions. Therefore, in order to detect the tilt of the optical disk, a method of allowing a parallel light having a small diameter to pass through the vicinity of the objective lens has been considered (for example, see Patent Document 1).

  However, in Patent Document 1, a gap is provided in the objective lens holder that holds the objective lens in order to pass the tilt detection beam, which may adversely affect the higher-order resonance characteristics of the objective lens driving device.

  Further, the tilt detection beam of the optical disc needs to be installed at a position where the detection beam is always applied to the optical disc surface even at the innermost circumference and the outermost circumference of the optical disc. FIG. 2 shows the positional relationship between the objective lens 1 and the inner and outer circumferences of the optical disc. The objective lens 1 originally held by the objective lens holder 2 moves in the tracking direction with respect to the optical disc by seek movement. However, for convenience of explanation, the objective lens side is fixed and the optical disk is moved in the tracking direction. Here, Dout indicates the outermost track of the optical disk, and Din indicates the innermost track. In order to detect the tilt of the optical disk at both the innermost and outermost tracks, a diagonal line that reliably provides reflected light. There is a restriction that the sensor must be installed at a position where the detection beam can be irradiated in the region.

  Here, let us consider a case where parallel light with a small diameter is passed through a position satisfying the above-described restriction of the fixed portion 3 slightly separated from the objective lens 1 as shown in FIG. In FIG. 10, the objective lens driving device 4 includes an objective lens 1, an objective lens holder 2, a drive coil 5, a drive magnet 6, a yoke base 7 and a fixed portion 6, and the objective lens 1, the objective lens holder 2 and the drive. The movable part composed of the coil 5 is supported by the fixed part 3 so as to be operable by the conductive elastic body support member 8. FIG. 10A is a plan view, and FIG. 10B is a side view seen from the tracking direction.

  On the other hand, FIG. 11 shows the relationship between the position of the tilt detection beam of the optical disk in the tangential direction from the optical axis of the objective lens and the detection error due to tilt detection crosstalk. This is because the tilt sensor of the optical disc is disposed at a position offset in the tangential direction with respect to the objective lens, so that a detection error occurs due to movement of the inner circumference to the outer circumference of the optical disc. As shown in FIG. 11, it can be seen that the tilt detection error increases as the sensor installation position moves away from the objective lens. In addition, since the detection error is a crosstalk error of the tilt sensor, the total detection error includes an error due to an initial set value error, a temporal temperature variation, and a detection position shift.

If a system with a disk substrate thickness of 0.6 mm, a blue LD for recording / reproduction LD, and an NA of the objective lens of 0.65 is adopted, the target value of tilt detection accuracy is about 0.1 deg. In consideration of accumulation of error, time-dependent temperature variation, error due to detection position deviation, etc., the crosstalk error needs to be suppressed to 0.02 deg or less. Therefore, the position in the tangential direction of the tilt detection beam of the optical disk from the optical axis of the objective lens must be closer to the fixed part.
JP 2003-193130 A

  The present invention has been made in view of the situation of the prior art as described above, and a tilt detection device capable of detecting the tilt of an optical disc with high accuracy in an optical disc drive device, and an optical pickup provided with the tilt detection device. It is an object to provide an apparatus and an optical disk drive apparatus.

  That is, the invention according to claim 1 is capable of correcting the objective lens that irradiates the optical disc with a tilt detection beam, detects the tilt amount from the reflected light, and collects the light on the recording / reproducing surface of the optical disc. In the tilt detection device that outputs a detection result to the drive device, the objective lens drive device includes: an objective lens holder that holds the objective lens; a fixed portion that operably supports the objective lens holder; and among the objective lens holder and the fixed portion A drive circuit for driving an objective lens holder, the drive circuit being configured to include a drive coil fixed to one side and a drive magnet fixed to the other side opposite to the drive coil. And a gap between the drive magnets. Accordingly, tilt detection can be performed in the vicinity of the objective lens, and highly accurate tilt detection can be performed.

  According to a second aspect of the present invention, in the tilt detection device according to the first aspect, three drive coils are arranged side by side in the tracking direction, of which the drive coil located in the center is thinner than the drive coils located on both sides. The drive coil is characterized in that the tilt detection beam passes between the drive coil and the drive magnet having a small thickness in the gap between the drive coil and the drive magnet.

  According to a third aspect of the present invention, in the tilt detection device of the first aspect, three drive coils are arranged side by side in the tracking direction, and the drive coil located in the center is arranged in a groove provided in the objective lens holder. The tilt detection beam passes between the drive coil and the drive magnet disposed in the groove in the gap between the drive coil and the drive magnet.

  In the second and third aspects of the invention, while securing a space necessary for passing the tilt detection beam, the gap between the drive coils on both sides of the tracking direction and the drive magnets opposed thereto is narrowed to reduce the space on both sides of the tracking direction. The thrust generated by the drive coil can be increased, and the sensitivity of the objective lens driving device can be improved.

  According to a fourth aspect of the present invention, in the tilt detection apparatus according to the first aspect, the two drive coils are arranged apart from each other in the tracking direction, and the tilt detection beam is included in the gap between the drive coil and the drive magnet. It is characterized by passing through a space between two drive coils that are spaced apart.

  According to a fifth aspect of the present invention, in the tilt detection device according to the first aspect, two drive magnets are arranged apart from each other in the tracking direction, and the tilt detection beam is included in a gap between the drive coil and the drive magnet. , Passing through a space between two drive magnets arranged apart from each other.

  According to the fourth and fifth aspects of the present invention, it is possible to increase a thrust generated by the drive coil by narrowing a gap between the drive coil and the drive magnet facing the drive coil while ensuring a space for passing the tilt detection beam. Thus, it is possible to improve the sensitivity of the objective lens driving device.

  According to a sixth aspect of the present invention, in the optical pickup device provided with the objective lens driving device, the tilt detection device according to any one of the first to fifth aspects is provided.

  According to a seventh aspect of the present invention, there is provided an optical disk drive apparatus comprising: a spindle motor for rotating an optical disk; an optical pickup apparatus according to the sixth aspect; a seek mechanism for moving the optical pickup apparatus in a radial direction of the optical disk; And a processing device for performing at least reproduction among recording, reproduction and erasure of information on the optical disk using the signal.

  According to the present invention, the tilt detection beam of the optical disk is arranged in the gap between the drive coil and the drive magnet, so that the objective lens holder (movable part) is not provided with a tilt detection hole, thereby providing high accuracy. Tilt detection can be performed.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. In all the drawings, common portions are denoted by the same reference numerals, and redundant description is omitted.

  1A and 1B show an objective lens driving device portion in a tilt detection apparatus according to a first embodiment of the present invention. FIG. 1A is a plan view, and FIG. 1B is a side view seen from a tracking direction. . In FIG. 1, the movable part of the objective lens driving device 4 includes an objective lens 1, an objective lens holder 2 that holds the objective lens 1, and a drive coil 5 that includes a coil that can be driven in a focusing direction, a tracking direction, and a tilt direction. It consists of The movable part is connected to the fixed part 3 via a plurality of conductive elastic support members 8 from both sides in the tangential direction, and is operably supported. The conductive elastic support members 8 are arranged on both sides of the tangential direction with the movable part sandwiched so that the axis is in the tangential direction, and one end is connected to the movable part and electrically connected to the end point of the drive coil 5 as described above. Has been. Further, the other end of the conductive elastic support member 8 is also connected to the fixed portion 3 as described above, and each of these ends is connected to a power supply unit (not shown) to which current is supplied from the outside. With such a configuration, it is possible to supply current from the outside to the drive coil 5 fixed to the movable part.

  In addition, a driving magnet 6 having a facing surface as a magnetized surface is arranged with respect to the driving coil 5, thereby forming a driving circuit having a certain gap. Further, there is a yoke base 7 in which the back yoke behind the driving magnet 6 and the base portion of the objective lens driving device 4 are integrated, and this yoke base 7 is further connected to the fixed portion 3. The portion of the yoke base 7 on which the objective lens 1 and the tilt detection beam of the optical disk 9 pass is configured not to block these beams. In such an objective lens driving device 4, the current flowing through the driving coil 5 and the magnetic flux generated by the driving magnet 6 disposed opposite to the driving coil 5 are combined to generate a Lorentz force in the driving coil 5, thereby moving the movable part. Can be driven in the direction of movement including the tilt direction.

  In order to realize closed tilt correction in real time using this driving method, it is necessary to detect the relative tilt between the optical disc 9 and the objective lens 1 in real time. As one of the relative tilt detection methods, there is a method in which the optical disc tilt and the objective lens tilt are individually detected, and the relative tilt between the optical disc and the objective lens is obtained from the difference between them.

  In FIG. 1, A is a beam for detecting the tilt of the objective lens 1, and is irradiated on a reflection surface (tilt detection surface) 10 provided on a movable part including the objective lens holder 2, and the reflected beam is reflected on the objective lens. Is detected as a tilt. B is a beam for detecting the tilt of the optical disk 9. The optical beam 9 is irradiated through the center of the gap between the drive coil 5 and the drive magnet 6 in the tracking direction, and the reflected beam is used as the tilt of the optical disk 9. Detected.

  FIG. 2 shows that the objective lens side originally moves in the tracking direction with respect to the optical disc in a form in which the objective lens side is fixed and the optical disc is moved in the tracking direction for convenience of explanation. The inner track is indicated by Dout, and the outermost track is indicated by Dout. The tilt detection beam of the optical disk needs to irradiate the optical disk surface from which reflected light is always obtained even at the innermost periphery and the outermost periphery of the optical disk, and must be installed at a position where irradiation is performed within the shaded area in FIG.

  In the present embodiment, the tilt detection beam B of the optical disk 9 passes through the center in the tracking direction in the gap between the drive coil 5 and the drive magnet 6 and can therefore irradiate the shaded area in FIG. The relative tilt between the optical disc 9 and the objective lens 1 can be obtained from the difference between the beam A and the beam B.

  The tilt detection optical system (not shown in FIG. 1) can be configured as shown in FIG. 3, for example. FIG. 3 shows an optical pickup device 11, which includes an objective lens driving device 4, a tilt detection optical system 12, and a pickup main body 13 equipped with a recording / reproducing optical system for processing a signal for recording / reproducing on / from an optical disc. Consists of.

  The tilt detection optical system 12 includes a light source 14, an aperture 15, a coupling lens 16, a beam splitter 17, a rising mirror 18, a light receiver 19, and the like, and the light beam emitted from the light source 14 has two holes. The aperture 15 is separated into a tilt detection beam of the objective lens and a tilt detection beam of the optical disk. Each light beam is bent by a rising mirror 18 through a coupling lens 16 and a beam splitter 17.

  As shown in FIG. 1, the tilt detection beam A of the objective lens from the rising mirror 18 is irradiated on the tilt detection surface 10 of the movable part, and the tilt detection beam B of the optical disk is irradiated on the optical disk 9. The tilt detection beam A of the objective lens is reflected by the tilt detection surface 10 of the movable part, the tilt detection beam B of the optical disc is reflected by the optical disc surface, and the beam splitter 17 follows a route substantially opposite to the incident direction. Then, the light passes through the beam splitter 17 and is incident on each light receiver 19 which is a photodetector. Then, the relative tilt between the optical disk 9 and the objective lens 1 is calculated from the signals obtained by the respective light receivers 19, and based on this, a current is passed through the drive coil 5 of the objective lens driving device 4 to drive the movable part to tilt. Is done.

  For example, the pickup body 13 is configured as shown in FIG. 4, and includes a light source 22, a collimator lens 23, a beam splitter 24, a rising mirror 25, a detection lens 26, a cylindrical lens 27, and a light receiver 28 in a housing 21. A recording / reproducing optical system is installed. That is, the components of the recording / reproducing optical system and the components of the tilt detection optical system are arranged at different positions in the height direction so as not to interfere with each other.

  In FIG. 4, the light emitted from the light source 22 passes through the collimator lens 23 and the beam splitter 24 and is bent by the rising mirror 25. The light bent by the rising mirror 25 is incident on the objective lens 1 of the objective lens driving device 4 installed on the housing 21 and forms a spot on the recording / reproducing surface of the optical disk 9. The reflected light of the spot changes its direction and direction from the beam splitter 24, passes through the detection lens 26 and the cylindrical lens 27, and then enters a light receiver 28 as a photodetector. The signal obtained by the light receiver 28 is used not only for recording / reproducing, but also for detecting the position of the objective lens 1 in the translational direction, and based on this signal, current is applied to the focusing coil and tracking coil of the objective lens driving device 4. To move the movable part (objective lens holder 2) in translation.

  As described above, information on the optical disk can be obtained by causing the objective lens to follow the translation direction and the tilt direction with respect to the optical disk.

  As shown in FIG. 5, the optical pickup device 11 is mounted in an optical disc drive device 31 so as to be movable in the radial direction of the optical disc 9. In FIG. 5, the optical disk drive device 31 includes a pickup module 32, and a spindle motor 33 that rotates the optical disk 9 is fixed to the pickup module 32. An optical pickup device 11 is mounted on a seek rail 34 attached to the pickup module 32 so as to be able to travel on the seek rail 34.

  As is clear from the above description, in the present embodiment, the tilt detection beam B of the optical disk is passed through the center in the tracking direction in the gap between the drive coil 5 and the drive magnet 6, so that the movable part Tilt detection is possible in the vicinity of the objective lens 1 without providing a gap for tilt detection in the (objective lens holder 2), and highly accurate tilt detection is possible without affecting the high-order resonance characteristics of the objective lens driving device. It becomes.

  In this embodiment, a moving coil type objective lens driving device in which a driving coil is mounted on a movable part is used. However, a similar effect can be obtained by a moving magnet type objective lens driving device in which a magnet is mounted on a movable part. can get.

  FIGS. 6A and 6B show an objective lens driving device portion in the tilt detection apparatus according to the second embodiment of the present invention. FIG. 6A is a plan view, and FIG. 6B is a side view seen from the tracking direction. . Compared to the first embodiment, the drive coil 5 is changed to the drive coil 41, and the portion of the optical disc through which the tilt detection beam B passes is different. Since the other parts are the same, redundant description is omitted.

  In FIG. 6, the drive coil 41 includes coils that can be driven in the focusing direction, the tracking direction, and the tilt direction similarly to the drive coil 5, but here, three are arranged side by side in the tracking direction of the objective lens holder 2. In addition, the thickness of the drive coil 41 located in the center of the tracking direction in the tangential direction is thinner than the thickness of the drive coil 41 located on both sides of the tracking direction. The tilt detection beam B of the optical disk is arranged in the center in the tracking direction, which is the position facing the thin drive coil in the gap between the drive magnet 6 and the drive coil 41. The tilt detection beam B of the optical disk passing through this position is satisfied to irradiate the shaded area in FIG. 2 described above, and the optical disk is determined from the difference between the tilt detection beam A of the objective lens and the tilt detection beam B of the optical disk. And the relative tilt of the objective lens can be obtained.

  By adopting such a configuration, in the second embodiment, a space necessary for passing the tilt detection beam B of the optical disk is ensured, and both sides in the tracking direction are compared with the first embodiment. The gap between the drive coil 41 and the drive magnet 6 facing it can be narrowed. Thereby, the thrust generated by the drive coils 41 on both sides of the tracking direction can be increased, and the sensitivity of the objective lens driving device 4 can be improved.

  Further, as in the case of the first embodiment, since there is no need to provide a tilt detection gap in the objective lens holder 2 (movable part), it does not affect the higher-order resonance characteristics, and at the same time, the objective lens Tilt detection can be performed with high accuracy by performing tilt detection in the vicinity of one. In the above description, a moving coil type objective lens driving device having a driving coil mounted on a movable part is used. However, a moving magnet type objective lens driving device having a driving magnet mounted on a movable part has the same effect. is there.

  7A and 7B show an objective lens driving device portion in a tilt detection device according to a third embodiment of the present invention. FIG. 7A is a plan view, and FIG. 7B is a side view seen from the tracking direction. . Compared with the first embodiment, the objective lens holder 2 and the drive coil 5 are changed to the objective lens holder 42 and the drive coil 43, and the portion through which the tilt detection beam B of the optical disk passes is different. Since the other parts are the same, redundant description is omitted.

  In FIG. 7, the drive coil 43 includes coils that can be driven in the focusing direction, the tracking direction, and the tilt direction in the same manner as the drive coil 5, but here, three are arranged in the tracking direction. Accordingly, a groove in the focusing direction is provided in the center of the tracking direction of the surface including the focusing direction and the tracking direction of the objective lens holder 42, and the drive coil 43 located in the center of the tracking direction is disposed in the groove of the objective lens holder 42. Has been. Then, the tilt detection beam B of the optical disc is placed in the groove of the objective lens holder 42 in the center of the tracking direction in the gap between the drive magnet 6 and the drive coil 43, and the center of the tangential direction is placed in the groove of the objective lens holder 42. It is arranged in a space created in front of the drive coil. The tilt detection beam B of the optical disk passing through this position is satisfied to irradiate the shaded area in FIG. 2 described above, and the optical disk is determined from the difference between the tilt detection beam A of the objective lens and the tilt detection beam B of the optical disk. And the relative tilt of the objective lens can be obtained.

  By adopting such a configuration, in the third embodiment, a space necessary for passing the tilt detection beam B of the optical disk is secured, and both sides of the tracking direction are compared with the first embodiment. The gap between the drive coil 43 and the drive magnet 6 facing it can be narrowed. Thereby, the thrust generated by the drive coils 43 on both sides in the tracking direction can be increased, and the sensitivity of the objective lens driving device 4 can be improved.

  Further, as in the case of the first embodiment, it is not necessary to provide a tilt detection gap in the objective lens holder 42 (movable part), so that the higher-order resonance characteristics are not affected. Tilt detection can be performed with high accuracy by performing tilt detection in the vicinity of one. In the above description, a moving coil type objective lens driving device having a driving coil mounted on a movable part is used. However, a moving magnet type objective lens driving device having a driving magnet mounted on a movable part has the same effect. is there.

  FIGS. 8A and 8B show an objective lens driving device portion in a tilt detection device according to a fourth embodiment of the present invention. FIG. 8A is a plan view, and FIG. 8B is a side view as seen from the tracking direction. . Compared with the first embodiment, the drive coil 5 is changed to the drive coil 45, and the portion through which the tilt detection beam B of the optical disk passes is different. Since the other parts are the same, redundant description is omitted.

  In FIG. 8, the drive coil 45 includes coils that can be driven in the focusing direction, the tracking direction, and the tilt direction in the same manner as the drive coil 5, but here, two are arranged in the tracking direction and separated from each other. Are arranged. The tilt detection beam B of the optical disk is disposed in a space between the drive coils 45 that are spaced apart in the tracking direction. The tilt detection beam B of the optical disk passing through this position is satisfied to irradiate the shaded area in FIG. 2 described above, and the optical disk is determined from the difference between the tilt detection beam A of the objective lens and the tilt detection beam B of the optical disk. And the relative tilt of the objective lens can be obtained.

  With this configuration, in the fourth embodiment, a gap between the drive coil 45 and the drive magnet 6 facing the drive coil 45 is ensured while ensuring a space for passing the tilt detection beam B of the optical disk. Can be narrowed. Thereby, the thrust generated by the drive coil 45 can be increased, and the sensitivity of the objective lens driving device 4 can be improved.

  Further, as in the case of the first embodiment, since there is no need to provide a tilt detection gap in the objective lens holder 2 (movable part), it does not affect the higher-order resonance characteristics, and at the same time, the objective lens Tilt detection can be performed with high accuracy by performing tilt detection in the vicinity of one. In the above description, a moving coil type objective lens driving device having a driving coil mounted on a movable part is used. However, a moving magnet type objective lens driving device having a driving magnet mounted on a movable part has the same effect. is there.

  FIGS. 9A and 9B show an objective lens driving device portion in a tilt detection device according to a fifth embodiment of the present invention. FIG. 9A is a plan view, and FIG. 9B is a side view seen from the tracking direction. . Compared with the first embodiment, the driving magnet 6 is changed to the driving magnet 46, and the portion through which the tilt detection beam B of the optical disk passes is different. Since the other parts are the same, redundant description is omitted.

  In FIG. 9, the driving magnets 46 arranged to face the driving coil 5 are divided at the center in the tracking direction, are arranged side by side in the tracking direction, and are spaced apart from each other in the tracking direction. . The tilt detection beam B of the optical disk is disposed in the space between the two divided drive magnets 46 in the center of the tracking direction. The tilt detection beam B of the optical disk passing through this position is satisfied to irradiate the shaded area in FIG. 2 described above, and the optical disk is determined from the difference between the tilt detection beam A of the objective lens and the tilt detection beam B of the optical disk. And the relative tilt of the objective lens can be obtained.

  By adopting such a configuration, in the fifth embodiment, a gap between the drive coil 5 and the drive magnet 46 facing the drive coil 5 is secured while ensuring a space for passing the tilt detection beam B of the optical disk. Can be narrowed. Thereby, the thrust generated by the drive coil 5 can be increased, and the sensitivity of the objective lens driving device 4 can be improved.

  Further, as in the case of the first embodiment, since there is no need to provide a tilt detection gap in the objective lens holder 2 (movable part), it does not affect the higher-order resonance characteristics, and at the same time, the objective lens Tilt detection can be performed with high accuracy by performing tilt detection in the vicinity of one. In the above description, a moving coil type objective lens driving device in which a driving coil is mounted on the movable portion is used. However, a moving magnet type objective lens driving device in which a magnet is mounted on the movable portion has the same effect.

It is the top view (a) and side view (b) which show the objective lens drive device part of the tilt detection apparatus of the 1st Embodiment of this invention. It is a figure which shows the positional relationship of an objective lens and the inner periphery and outer periphery of an optical disk. It is a perspective view which shows an example of the optical pick-up apparatus concerning this invention. It is a figure which illustrates the recording / reproducing optical system of a pick-up main body. It is a top view which shows an example of an optical disk drive device. It is the top view (a) and side view (b) which show the objective lens drive device part of the tilt detection apparatus of the 2nd Embodiment of this invention. It is the top view (a) and side view (b) which show the objective-lens drive device part of the tilt detection apparatus of the 3rd Embodiment of this invention. It is the top view (a) and side view (b) which show the objective-lens drive device part of the tilt detection apparatus of the 4th Embodiment of this invention. It is the top view (a) and side view (b) which show the objective lens drive device part of the tilt detection apparatus of the 5th Embodiment of this invention. FIG. 4 is a plan view (a) and a side view (b) showing an example in which a tilt detection beam of an optical disc is passed through a fixed portion of an objective lens driving device. It is a figure showing the relationship between the tangential direction position from the objective-lens optical axis of the beam for tilt detection of an optical disk, and the detection error by the crosstalk of tilt detection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Objective lens 2,42 Objective lens holder 3 Fixed part 4 Objective lens drive device 5,41,43,45 Drive coil 6,46 Drive magnet 7 Yoke base 8 Conductive elastic support member 9 Optical disk 10 Reflecting surface (tilt detection surface) )
DESCRIPTION OF SYMBOLS 11 Optical pick-up apparatus 12 Tilt detection optical system 13 Pickup main body 14,22 Light source 16 Coupling lens 17,24 Beam splitter 18,25 Rising mirror 19,28 Light receiver 23 Collimator lens 26 Detection lens 27 Cylindrical lens 31 Optical disk drive apparatus 32 Pickup module 33 Spindle motor 34 Seek rail

Claims (7)

The tilt detection beam is irradiated onto the optical disc, the tilt amount is detected from the reflected light, and the detection result is output to the objective lens driving device capable of correcting the objective lens for condensing the light on the recording / reproducing surface of the optical disc. In the tilt detection device,
The objective lens driving device is
An objective lens holder for holding the objective lens;
A fixed portion that operably supports the objective lens holder;
A drive circuit for driving the objective lens holder, comprising: a drive coil fixed to one of the objective lens holder and the fixed portion; and a drive magnet fixed to the other facing the drive coil;
With
The tilt detection apparatus, wherein the tilt detection beam passes through a gap between the drive coil and the drive magnet.   The three drive coils are arranged side by side in the tracking direction, of which the drive coil located in the center is thinner than the drive coils located on both sides, and the tilt detection beam is the drive coil. 2. The tilt detection apparatus according to claim 1, wherein a gap between the driving magnet and the driving magnet passes between the thin driving coil and the driving magnet.   Three drive coils are arranged side by side in the tracking direction, and a drive coil located in the center is arranged in a groove provided in the objective lens holder, and the tilt detection beam is connected to the drive coil and the drive coil. 2. The tilt detection apparatus according to claim 1, wherein among the gaps between the magnets, the tilt detection apparatus passes between a drive coil and a drive magnet disposed in the groove.   The two drive coils are spaced apart in the tracking direction, and the tilt detection beam is between the two drive coils disposed apart from each other in the gap between the drive coil and the drive magnet. The tilt detecting apparatus according to claim 1, wherein the tilt detecting apparatus passes through the space.   The two drive magnets are arranged apart from each other in the tracking direction, and the two drive magnets are arranged apart from each other in the gap between the drive coil and the drive magnet. The tilt detection apparatus according to claim 1, wherein the tilt detection apparatus passes through a space between magnets.   An optical pickup device provided with an objective lens driving device, comprising the tilt detection device according to any one of claims 1 to 5. A spindle motor that rotates the optical disc;
An optical pickup device according to claim 6,
A seek mechanism for moving the optical pickup device in the radial direction of the optical disc;
An optical disc drive apparatus comprising: a processing device that performs at least reproduction among recording, reproduction, and erasure of information on the optical disc using an output signal of the optical pickup device.

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