JP2005071457A - Objective lens drive actuator for optical pickup and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately match a central axis of a liquid crystal panel for reducing spherical aberration and an optical axis of an objective lens. <P>SOLUTION: On the surface 5a of an objective lens 5, a plurality of markers 14 for positioning are arranged on the circumference of a radius C with the light axis OA of the lens as a center, and the radius C is equal to the radius of a circular opening 2. The objective lens 5 is positioned so that each of the markers 14 matches the internal surface of the circular opening 2, and the optical axis OA of the objective lens 5 and a central axis CA1 of the circular opening 2 are matched. Also on the liquid crystal panel 6, a plurality of markers 11 for positioning are arranged on the circumference of a radius B with its central axis CA2 of the panel as a center, and the radius B is equal to the radius A of the circular opening 2. The liquid crystal panel 6 is positioned so that each of the markers 11 matches the internal part of the circular opening 2, and the central axis CA2 of the liquid crystal panel and the central axis CA1 of the circular opening part 2 are matched. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an objective lens driving actuator and an optical disc apparatus of an optical pickup that records or reproduces information by irradiating a disc-shaped recording medium with a laser beam.

  As a standard for high-density optical disk devices, a Blu-ray standard using a blue-violet laser (wavelength: 405 nm), a high NA (= 0.85) objective lens and a disk with a light transmission protective layer thickness of 0.1 mm is proposed. (For example, refer nonpatent literature 1).

  In such a high-density optical disc apparatus, the recording / reproduction characteristics are more greatly affected by the error in the protective layer thickness of the disc as compared with the optical disc apparatus using the current red laser. By using a high NA (= 0.85) objective lens, the light spot focused on the objective lens and irradiated onto the recording surface of the optical disc is accompanied by an error in the thickness of the light transmission protective layer of the optical disc. , The generated spherical aberration increases rapidly. As a result, the quality rapidly deteriorates (cannot be reduced to a predetermined size, distorted, etc.).

As a solution to this problem, a method has been proposed in which a liquid crystal panel is mounted in the optical system of the optical pickup and the spherical aberration of the light spot is reduced by controlling the driving voltage of the liquid crystal (for example, Patent Document 1 and Non-Patent Document). 2)
JP 2000-353333 A IEICE Technical Report Technical Report of IEICE CPM2002-92 (2002-9) P33-P36 IEICE Technical Report Technical Report of IEICE CPM2002-92 (2002-9) P69 ~ P74

  As described above, when a liquid crystal panel is used in the optical system of the optical pickup, if the deviation between the central axis of the liquid crystal panel and the optical axis of the objective lens increases due to the tracking operation of the objective lens, another light spot is generated when the liquid crystal is driven. Aberration (coma aberration) is generated, the quality of the light spot is deteriorated, and the recording / reproducing characteristics of the optical disc apparatus are adversely affected. Therefore, it is conceivable to eliminate the influence of the tracking operation by mounting an objective lens and a liquid crystal panel on the movable part of the objective lens driving actuator of the optical pickup. Even in this case, in order to suppress the above-described coma aberration to a level that does not adversely affect the recording / reproduction of the optical disk device, the central axis of the liquid crystal panel and the optical axis of the objective lens are accurately aligned to the movable part of the objective lens driving actuator. It is necessary to incorporate it. However, until now, no consideration has been given to a method for accurately aligning the central axis of the liquid crystal panel and the optical axis of the objective lens.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an optical pickup capable of accurately aligning the central axis of a liquid crystal panel and the optical axis of an objective lens for reducing spherical aberration. An objective lens driving actuator is provided.

  In order to achieve the above object, the present invention provides a movable holder having a circular opening, an objective lens mounting portion on the upper side, and a flat liquid crystal panel mounting portion on the lower side. An optical pickup having a configuration in which an objective lens for condensing a light beam on a disc-shaped recording medium is mounted on the objective lens mounting portion, and a liquid crystal panel is mounted on the liquid crystal panel mounting portion to provide a concentric transparent electrode to correct the aberration of the light beam A plurality of positioning markers provided on the same circumference around the central axis of the transparent electrode on one of a pair of transparent substrates enclosing the liquid crystal of the liquid crystal panel, and the objective lens In addition, a plurality of positioning markers are provided on the same circumference around the optical axis.

  In addition, the distance from the central axis of the transparent electrode to the end of the positioning marker on one substrate of the liquid crystal panel and the distance from the optical axis of the objective lens to the end of the positioning marker are the radius of the circular opening. Are set equal.

  Further, the positioning marker on the liquid crystal panel and the positioning marker on the objective lens are provided at a position in contact with the extended surface of the circular opening of the movable holder.

  The positioning marker for the liquid crystal panel is formed integrally with the transparent electrode, and the positioning marker for the objective lens is formed integrally with the objective lens.

  The movable holder has a bearing portion parallel to the optical axis of the objective lens at the center thereof, and a circular opening, an objective lens attachment portion, and a liquid crystal panel attachment portion between the bearing portion and the outer peripheral portion of the movable holder. The transparent electrode of the liquid crystal panel is connected to a printed cable, and the printed cable is bent from the transparent electrode into a substantially U-shape and is disposed on the movable holder so as to face the bearing portion.

  An optical disk apparatus according to the present invention is equipped with any of the above-described objective lens driving actuators of an optical pickup.

  ADVANTAGE OF THE INVENTION According to this invention, the objective-lens drive actuator of the optical pick-up which can match | combine exactly the center axis | shaft of the liquid crystal panel for spherical aberration reduction, and the optical axis of an objective lens can be provided, As a result, optical disc The quality of the light spot applied to the recording surface is stabilized well, and recording / reproduction of a high-density optical disc apparatus can be performed stably.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a main part of an objective lens driving actuator of an optical pickup according to the present invention, wherein 1 is a movable holder, 2 is a circular opening, 3 is an objective lens mounting part, 3a is a cylindrical part, and 3b is a flat part. 4 is a liquid crystal panel mounting portion, 5 is an objective lens, 5a is a lens surface, 5b is a flat portion, 6 is a liquid crystal panel, 7 is a liquid crystal, 8 and 9 are transparent electrodes, 10 is an inner surface, and 11 and 14 are positioning markers. It is.

  2 is a plan view of the liquid crystal panel 6 viewed from the objective lens 5 side in FIG. 1, FIG. 3 is a plan view of the objective lens 5 viewed from the liquid crystal panel 6 side in FIG. 1, and 12a to 12c are transparent. The electrodes 13 are printed cables, and the same reference numerals are given to the portions corresponding to FIG.

  In FIG. 1, a circular opening 2 is formed in the movable holder 1, an objective lens mounting portion 3 is above the circular opening 2, and a liquid crystal panel mounting portion is below the circular opening 2. 4 are formed. The circular opening 2 forms a cylindrical hollow portion having a predetermined opening radius A from the central axis CA1, and the objective lens mounting portion 3 has a cylindrical surface 3a having a central axis continuous with the central axis CA1 of the circular opening 2. The liquid crystal panel mounting portion 4 has a flat surface.

  An objective lens 5 for condensing a light beam (not shown) on a disc-shaped recording medium (not shown) is mounted on the flat surface 3b and attached to the objective lens attaching portion 3 and attached to the liquid crystal panel. The unit 4 is provided with a liquid crystal panel 6 for correcting the spherical aberration of the light beam. The disk-shaped recording medium is rotated at a position above the objective lens 5 in the Z direction, and the light beam enters the objective lens 5 from below the liquid crystal panel 6 through the liquid crystal panel 6 and the circular opening 2. The light is focused on a disk-shaped recording medium.

  The liquid crystal panel 6 has a configuration in which the liquid crystal 7 is sealed by a pair of transparent substrates 8 and 9, and one of the transparent substrates 8 and 9 (here, the side of the transparent substrate 8 facing the transparent substrate 9). A marker (that is, a positioning marker) 11 for positioning the liquid crystal panel 6 is provided on the inner surface 10. The positioning marker 11 will be described with reference to FIG.

  In the figure, a plurality of transparent electrodes 12 a, 12 b, 12 c are formed concentrically on the inner surface 10 of the transparent substrate 8 of the liquid crystal panel 6, and these transparent electrodes 12 a, 12 b, 12 c are connected via a printed cable 13. Connected to a drive circuit (not shown), a voltage is applied from the drive circuit to the liquid crystal 7 (FIG. 1). Further, positioning markers 11 are provided at four positions on the same circumference centering on the central axis CA2 (hereinafter referred to as the central axis of the liquid crystal panel 6) of the transparent electrodes 12a, 12b, 12c. A distance B from the central axis CA2 to the outer end of the positioning marker 11 is set equal to the opening radius A from the central axis CA1 of the circular opening 2 shown in FIG. The positioning marker 11 is simultaneously formed in the pattern forming process of the transparent electrodes 12a, 12b, and 12c.

  Returning to FIG. 1, the liquid crystal panel 6 is attached to the liquid crystal panel mounting portion 4 so that the outer end portions of these positioning markers 11 coincide with the surface obtained by extending the inner surface of the circular opening 2 toward the liquid crystal panel 6. Thus, the central axis CA2 of the liquid crystal panel 6 and the central axis CA1 of the circular opening 2 are on the same straight line and coincide with each other.

  The surface of the objective lens 5 on the side of the circular opening 2 is composed of a lens surface 5 a and a flat surface 5 b around the lens surface 5 a, and the flat surface 5 b is attached to the flat surface 3 b in the objective lens attachment portion 2. The objective lens 5 is also provided with a positioning marker 14 on the lens surface 5a. The positioning marker 14 will be described with reference to FIG.

  In the figure, on the lens surface 5a of the objective lens 5, positioning markers 14 are provided at four positions on the same circumference centered on the optical axis OA. A distance C from the optical axis OA to the outer end of the positioning marker 14 is set equal to the opening radius A from the central axis CA1 of the circular opening 2 shown in FIG. Here, these positioning markers 14 are simultaneously formed during the molding process of the objective lens 5 and have a convex shape or a concave shape.

  Returning to FIG. 1, the objective lens 5 is attached to the objective lens attachment portion 3 so that the outer end portions of these positioning markers 14 coincide with the surface obtained by extending the inner surface of the circular opening 2 toward the objective lens 5 side. Thus, the optical axis OA of the objective lens 5 and the central axis CA1 of the circular opening 2 are on the same straight line and coincide with each other.

  As described above, the central axis CA2 of the liquid crystal panel 6 and the optical axis OA of the objective lens 5 coincide with the central axis CA1 of the circular opening 2, and as a result, the central axis CA2 of the liquid crystal panel 6 and the objective lens The optical axis OA of 5 is exactly on the same straight line and coincides.

  Here, the positioning marker 11 of the liquid crystal panel 6 shown in FIG. 2 has a circular shape, but this may be a triangular positioning marker 11a as shown in FIG. As shown in FIG. 5, the positioning marker 11 may be a linear shape, or any other shape such as a square shape or an arc shape. Although not shown, it is also possible to position the liquid crystal panel 6 so that the positioning marker 11 has a cross shape and the intersection of the cross contacts the extended surface of the inner surface of the circular opening 2. The same applies to the positioning marker 14 of the objective lens 5. The shape of the positioning marker on the liquid crystal panel 6 and the shape of the positioning marker on the objective lens 5 may be different.

  6 and 7 show another specific example of the positioning marker 14 by taking the objective lens 5 as an example. In FIG. 3, four positioning markers 14 are provided on the same circumference. As shown in FIGS. 6 and 7 showing examples of using positioning markers 14 having different shapes, the positioning markers 14 may be provided at three locations on the same circumference, or at five or more locations. It may be. The same applies to the liquid crystal panel 6.

  Here, a specific example of a method of attaching the objective lens 5 and the liquid crystal panel 6 to the movable holder 1 will be described with reference to FIG. Here, first, the objective lens 5 is attached, and then the liquid crystal panel 6 is attached, but the reverse order may be used.

  In FIG. 8A, first, the objective lens 5 is inserted into the objective lens mounting portion 3 provided in the movable holder 1 and placed on the flat portion 3b coated with an adhesive. Then, the objective lens 5 side is photographed from above by the CCD camera 15 and the outer end portion of the positioning marker 14 is monitored by the CCD camera 15 so that the circular opening 2 of the movable holder 1 as shown in FIG. The objective lens 5 is aligned so as to be in contact with the inner surface of the lens. When this alignment is completed, the objective lens 5 is bonded to the flat portion 3b of the objective lens mounting portion 3. As such an adhesive, it is preferable to use a rapidly curable one such as an ultraviolet curable type.

  When the adhesion of the objective lens 5 to the objective lens mounting portion 3 is completed, as shown in FIG. 8B, the movable holder 1 is turned upside down and the liquid crystal panel 6 is coated with the adhesive. The liquid crystal panel mounting portion 4 is placed, the liquid crystal panel 6 side is photographed from above by the CCD camera 15, and the outer end portion of the positioning marker 11 is monitored as shown in FIG. The liquid crystal panel 6 is aligned so as to be in contact with the inner surface of the circular opening 2 of the movable holder 1. When this alignment is completed, the liquid crystal panel 6 is bonded to the liquid crystal panel mounting portion 4.

  As a matter of course, the positioning markers 11 and 14 need to have a size that can be recognized on the monitor screen.

  FIG. 9 shows a specific example of the entire structure of the movable holder 1 to which the objective lens 5 and the liquid crystal panel 6 are attached. FIG. 9A is a plan view seen from the liquid crystal panel 6 side. (B) is a longitudinal sectional view in the Y direction from a section P-P perpendicular to the surface (XY plane) of the movable holder 1 in FIG. A focus coil, 23 is a tracking coil, 24 is a printed cable, and 25 is a lower surface. In addition, the same code | symbol is attached | subjected to the part corresponding to previous drawing, and the overlapping description is abbreviate | omitted.

  9 (a) and 9 (b), the movable holder 1 has a shape in which a cylindrical side wall is provided as an outer peripheral side surface 20 in a substantially disc-shaped portion, and a circular opening 2 and an objective are formed in a part thereof. A lens attachment portion 3 and a liquid crystal panel attachment portion 4 are formed, and the objective lens 5 and the liquid crystal panel 6 are attached to each of them as described above, based on the positioning markers. A bearing portion 21 is provided in the center of the movable holder 1 in parallel with the optical axis OA of the objective lens 5. Between the bearing portion 21 and the outer peripheral side surface 20 of the movable holder 1, the circular opening 2 and the objective are provided. A lens mounting portion 3 and a liquid crystal panel mounting portion 4 are formed. Further, a focus coil 22 is attached over the entire circumference of the outer peripheral side surface 20 of the movable holder 1, and tracking coils 23 are attached at equal intervals at four locations on the side surface portion of the focus coil 22. These coils 22 and 23 are connected to a printed cable 24 arranged on the lower surface 25 of the movable holder 1.

  As is clear from FIG. 9A, the print cable 13 connected to the liquid crystal panel 6 is different from the print cable 24 connected to the focus coil 22 and the tracking coil 23 in the lower surface 25 of the movable holder 1 in the X axis. It arrange | positions in the surface located in the opposite side regarding a direction, and is bent by the substantially U shape toward the bearing part 21 from the middle. The printed cable 13 is set to a thickness as thin as about 50 to 60 μm, like the printed cable 24, and after being bent into a substantially U shape, the printed cable 13 overlaps the printed cable 24 from the vicinity of the bearing portion 21. Are arranged. By arranging in this way, unnecessary external force that the printed cable 13 gives to the movable holder 1 is suppressed, and the movable holder 1 can smoothly move for the focus operation and the tracking operation.

  FIG. 10 shows an overall configuration of an embodiment of the objective lens driving actuator of the optical pickup according to the present invention, in which the movable holder 1 is mounted. FIG. 10 (a) is a plan view seen from the objective lens 5 side. FIG. 2B is a longitudinal sectional view taken from the sectional plane QQ perpendicular to the surface (XY plane) of the movable holder 1 in the Y direction, 26 is a DVD / CD compatible objective lens, 27 is a fixed portion, 27a. Is a flat plate portion, 27b is a protruding portion, 27c is a vertical portion, 27d is a protruding portion, 27e is a vertical portion, 28 is a magnet, and 29 is a shaft. In addition, the same code | symbol is attached | subjected to the part corresponding to previous drawing, and the overlapping description is abbreviate | omitted.

  10A and 10B, two types of objective lenses are attached to the movable holder 1. One of the objective lenses 5 is used for a high-density optical disc (laser wavelength = 405 nm), and the other is a DVD / CD compatible objective lens 26. From the objective lens 5, the center of the movable holder 1 is used. Are arranged in a direction different by about 90 degrees.

  The movable holder 1 is attached to a shaft 29 fixed to the center portion of the fixed portion 27 so as to be vertically movable (moving in the Z direction) and rotatable. The fixed portion 27 includes a flat plate portion 27a provided with a shaft 29 in the center portion, a protruding portion 27b provided for each portion of the movable holder 1 of the flat plate portion 27a facing the tracking coil 23, and the protruding portion 27b. It consists of a vertical portion 27c provided at the tip, and a magnet 28 is attached to the inner surface of each vertical portion 27c. Therefore, the magnet 28 faces the tracking coil 23 and a part of the focus coil 22. Here, in the movable holder 1, four tracking coils 23 are arranged at an angular interval of 90 degrees with respect to the bearing portion 21, and accordingly, in the fixed portion 27, the four protruding portions 27b are 90 degrees. Are provided at angular intervals. The fixed portion 27 is made of a material such as iron and constitutes a yoke for the tracking coil 23 and the focus coil 22. That is. A magnetic path is formed by the tracking coil 23, the focus coil 22, and the fixed portion 27.

  In addition, a protruding portion 27d is provided at a part of the fixed portion 27, and a vertical portion 27e is provided at the tip thereof. The vertical portion 27e does not face any tracking coil 23 of the movable holder 1, and no magnet is provided. The printed cable 13 connected to the liquid crystal panel 6 of the movable holder 1 and the printed cable 24 connected to the focus coil 22 and the tracking coil 23 are fixed at the protruding portion 27d and the vertical portion 27e.

  The movable holder 1 is supported in a state where a shaft 29 is inserted into the bearing portion 21. Although not shown, a thin plate-like magnetic body is attached to the lower surface 25 of the movable holder 1, and this acts by a magnetic field from the magnet 28, so that the focus coil 22 and the tracking coil 23 face the magnet 28. The movable holder 1 is held at the neutral position. When a current is passed through the focus coil 22, the movable holder 1 is translated up and down (Z direction) along the shaft 29, and when a current is passed through the tracking coil 23, the movable holder 1 is driven to rotate around the shaft 29. To do.

  Assuming that the objective lens 5 is in the optical path of a light beam (not shown) in the state shown in the figure and is in a state where data can be recorded / reproduced on a disk-like recording medium (not shown), an impulse current is passed through the tracking coil 23 to move it. By rotating the holder 1 by about 90 degrees, a DVD / CD compatible objective lens 26 is moved in the optical path of the light beam in place of the objective lens 5, and data can be recorded / reproduced on a disc-shaped recording medium using this. It becomes a state. In this way, any one of the objective lens 5 and the DVD / CD compatible objective lens 26 can be arbitrarily selected.

  FIG. 11 is a block diagram showing an embodiment of an optical disk apparatus according to the present invention equipped with an objective lens drive actuator according to the present invention, wherein 30 is an optical pickup, 31 is an objective lens drive actuator according to the present invention, 32 is an optical system, 33 is a disk motor, 34 is a disk-shaped recording medium (hereinafter referred to as an optical disk), 35 is a mechanical chassis, 36 is a main shaft guide bar, 37 is a pressurizing portion, 38 is a lead screw, 39 is a sub shaft guide bar, and 40 is a feed. It is a motor, The same code | symbol is attached | subjected to the part corresponding to previous drawing, and the overlapping description is abbreviate | omitted.

  In the figure, the objective lens driving actuator 31 described in FIG. 10 is arranged in a portion surrounded by a one-dot chain line portion of the optical pickup 30, and a laser light source, a collimating lens (not shown), An optical system 32 such as a photodetector is arranged. The optical pickup 30 is disposed on the lower surface of the optical disk 34 that is chucked by the disk motor 33 and rotates.

  The disk motor 33 is fixed to a mechanical chassis 35. The optical pickup 30 has a main shaft guide bar 36 inserted into one end thereof and is connected to a lead screw 38 through a pressurizing portion 37, and a sub shaft guide at the other end. The bar 39 is held in the inserted state. These guide bars 36 and 39 are fixed to the mechanical chassis 35 by screws or the like.

  When the lead screw 38 is driven by a feed motor 40 such as a stepping motor, the optical pickup 30 moves in the radial direction (R direction) of the optical disk 34, and an optical head including the objective lens 5 and the objective lens 26 is accessed. It is.

  Although not shown, this optical disc apparatus is also mounted with an electric circuit for transmitting signals to control components such as the optical pickup 30, the disc motor 33, and the feed motor 40.

  Next, a conventional objective lens driving actuator will be described with reference to FIG. 12 and compared with the above embodiment. In FIG. 12, the parts corresponding to those in FIG.

  In FIG. 12, in the conventional objective lens driving actuator, the objective lens 5 'is attached to the movable holder 1' with the side surface 5a 'as a reference. For this reason, a deviation δ1 between the central axis CA1 ′ of the circular opening 2 ′ and the optical axis OA ′ of the objective lens 5 ′ due to dimensional variations between the side surface 5a ′ of the objective lens 5 ′ and the objective lens mounting portion 3 ′. Will occur.

  On the other hand, the liquid crystal panel 6 ′ is attached by being pressed against the vertical surface 4 a ′ of the liquid crystal panel mounting portion 4 ′ of the movable holder 1 ′ with the outer diameter end surface 6 a ′ as a reference. For this reason, due to dimensional variations between the outer diameter end surface 6a ′ of the liquid crystal panel 6 ′ and the vertical surface 4a ′, there is a shift between the central axis CA1 ′ of the circular opening 2 ′ and the central axis CA2 ′ of the liquid crystal panel 6 ′. δ2 is generated.

  As a result, displacements δ1 and δ2 are accumulated between the optical axis OA 'of the objective lens 5' and the central axis CA2 'of the liquid crystal panel 6'. Thus, until now, it has been difficult to accurately align the optical axis OA 'of the objective lens 5' and the central axis CA2 'of the liquid crystal panel 6'.

  On the other hand, in the embodiment shown in FIG. 1, the positioning marker 11 is provided on the liquid crystal panel 6 at an equal distance from the central axis CA2, and the distance B from the central axis CA2 to the outer end of the positioning marker 11 is circular. Since the positioning marker 11 is used to set the center axis CA2 of the liquid crystal panel 6 and the center axis CA1 of the circular opening 2 to be equal to the opening radius A from the center axis CA1 of the opening 2. Can be matched. The objective lens 5 is also provided with a positioning marker 14 at an equal distance from the optical axis OA, and the distance C from the optical axis OA to the outer end of the positioning marker 14 is the central axis of the circular opening 2. Since it is set to be equal to the opening radius A from CA1, the optical axis OA of the objective lens 5 and the central axis CA1 of the circular opening 2 can be matched by using the positioning marker 14. . As a result, the liquid crystal panel 6 and the objective lens 5 can be accurately aligned so that the optical axis OA of the objective lens 5 and the center axis CA2 of the liquid crystal panel 6 coincide. Therefore, in the objective lens driving actuator according to the present invention, coma aberration does not occur in the light spot when the liquid crystal is driven, the quality of the light spot is not deteriorated, and the recording / reproducing characteristics of the high-density optical disc apparatus are stabilized.

It is a longitudinal cross-sectional view which shows the principal part of one Embodiment of the objective lens drive actuator of the optical pick-up by this invention. It is the top view which looked at the liquid crystal panel side from the objective-lens side in FIG. It is the top view which looked at the objective lens side from the liquid crystal panel side in FIG. It is a figure which shows the other specific example of the marker for positioning of the liquid crystal panel in FIG. It is a figure which shows the other specific example of the marker for positioning of the liquid crystal panel in FIG. It is a figure which shows the other specific example of the marker for positioning of the objective lens in FIG. It is a figure which shows the other specific example of the marker for positioning of the objective lens in FIG. It is a figure which shows one specific example of the attachment method to the movable holder of the objective lens and liquid crystal panel in FIG. It is a figure which shows the example of whole structure of one specific example of the movable holder in one Embodiment of the objective lens drive actuator of the optical pick-up by this invention. It is a figure which shows one Embodiment of the objective lens drive actuator of the optical pick-up by this invention. 1 is a configuration diagram showing an embodiment of an optical disc apparatus equipped with an objective lens driving actuator of an optical pickup according to the present invention. It is a figure explaining attachment to the movable holder of the objective lens and liquid crystal panel in the objective lens drive actuator of the conventional optical pickup.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Movable holder 2 Circular opening 3 Objective lens attachment part 4 Liquid crystal panel attachment part 5 Objective lens 5a Lens surface 5b Flat part 6 Liquid crystal panel 11 Positioning marker 14 Positioning marker 21 Bearing part 22 Focus coil 23 Tracking coil 27 Fixing part 28 Magnet 29 Shaft 30 Optical pickup 31 Objective lens drive actuator 33 Disc motor 34 Disc-shaped recording medium 38 Lead screw 40 Feed motor

Claims (6)

A disc-shaped recording medium having a circular opening, an objective lens mounting portion formed on the upper side of the circular opening, and a flat liquid crystal panel mounting portion formed on the lower side of the circular opening; Of an optical pickup provided with a movable holder having an objective lens for condensing a light beam attached thereto, a concentric transparent electrode provided on the liquid crystal panel attachment portion, and a liquid crystal panel attached to correct the aberration of the light beam. In the objective lens drive actuator,
A plurality of positioning markers are provided on the same circumference around the central axis of the transparent electrode on one of the pair of transparent substrates enclosing the liquid crystal of the liquid crystal panel,
An objective lens driving actuator for an optical pickup, characterized in that the objective lens is provided with a plurality of positioning markers on the same circumference centered on the optical axis. In claim 1,
The distance from the central axis of the transparent electrode to the end of the positioning marker and the distance from the optical axis of the objective lens to the end of the positioning marker on the one substrate of the liquid crystal panel are the circular shape. An objective lens driving actuator of an optical pickup, wherein the objective lens driving actuator is set equal to a radius of an opening. In claim 1,
An objective lens driving actuator of an optical pickup, wherein the positioning marker on the liquid crystal panel and the positioning marker on the objective lens are provided at a position in contact with an extended surface of the circular opening. In claim 1,
An objective lens driving actuator of an optical pickup, wherein the positioning marker of the liquid crystal panel is formed integrally with the transparent electrode, and the positioning marker of the objective lens is formed integrally with the objective lens. In claim 1,
The movable holder includes a bearing portion parallel to the optical axis of the objective lens at a central portion thereof, and the circular opening, the objective lens mounting portion, and the portion between the bearing portion and the outer peripheral portion of the movable holder. A liquid crystal panel mounting portion,
The transparent electrode of the liquid crystal panel is connected to a printed cable, and the printed cable is arranged in the movable holder so as to be bent in a substantially U shape from the transparent electrode toward the bearing portion. Pickup objective lens drive actuator. 6. An optical disc apparatus comprising the objective lens drive actuator for an optical pickup according to claim 1.

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