JPH04344330A - Inclination correcting device for optical head - Google Patents

Abstract

PURPOSE:To provide the inclination correcting device for optical head capable of quick response and easy optical head control. CONSTITUTION:In a sub base 23, guide rails 3 and 3a and voice coil meters 20 and 20a are arranged. An optical head 26 is guided by the guide rails 3 and 3a and can be moved in the radius direction of an optical disk 1. The optical head 26 is driven by voice coil meters 20 and 20a. The driving power by laminated piezoelectric elements 33 and 33a is transferred through elastic deformable metallic arms 32 and 32a to the sub base 23. Accordingly, the sub base 23 rotates in the surface direction of the optical disk 1 around shafts 24 and 24a, and the light beam from the optical head 2 is made incident to the optical disk surface vertically.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head tilt correcting device, and more particularly to an optical head tilt correcting device for correcting the tilt of an optical head in response to a warp of an optical disk.

0002

[Background Art] A light beam from an optical head of an optical disk device should be incident perpendicularly to the optical disk surface. If the light beam is not incident perpendicularly to the optical disk surface, optical performance will deteriorate. There are things to do.

On the other hand, some optical disks tend to warp depending on the substrate material and its outer diameter. For example, an optical disk using a glass substrate can have less warpage, but an optical disk using a substrate of polycarbonate or the like with a diameter of 300 mm will have more warpage. 2. Description of the Related Art A device is known that guarantees optical performance by correcting the inclination of an optical head so that a light beam from an optical head is incident perpendicularly to the optical disc surface when the warpage of an optical disc exceeds a permissible level.

FIG. 4 is a three-dimensional view of a conventional optical head tilt correction device. In FIG. 4, a spindle motor 2 with an optical disk 1 mounted thereon is arranged on a base 4 together with guide rails 3 and 3a. On the other hand, actuator 5
The optical head 7 in which the tilt error detector 6 is disposed,
It is rotatably supported on the carriage 9 via shafts 8, 8a.

The carriage 9 is guided by guide rails 3 and 3a and is configured to be movable in the radial direction of the optical disc 1, indicated by A and A' in the figure, parallel to the optical disc surface. A coil 10 is disposed on the carriage 9, and a driving force is obtained by a magnetic circuit composed of yokes 11, 11a, 12, permanent magnets 13, 13a and an electromagnetic force acting on the coil 10, and the carriage 9 can be moved in parallel. It is said to be composed of The magnetic circuit is fixed to the base 4.

The rotational driving force of the motor 14 is provided by the worm gear 1.
5. It is transmitted to the cam 17 via the reduction gear 16. A shaft 18 press-fitted into the optical head 7 is engaged with the groove of the cam 17, and rotation of the cam 17 is converted into vertical movement of the shaft 18. As a result, the optical head 7 rotates about the shaft 8 in the directions indicated by B and B' in the figure.

The tilt error detector 6 detects the tilt of the optical disk 1, and a control circuit (not shown) drives the motor 14 to rotate the optical head 7.
The light beam from the optical disc is controlled so that it is incident perpendicularly to the optical disc surface.

[0008]

[Problems to be Solved by the Invention] However, in the conventional optical head tilt correction device, the driving force of the motor is transferred to a gear,
Since the tilt of the optical head was controlled using a mechanism such as a cam, there were several drawbacks as described below.

First of all, it takes several hundred [ms] to several [s] to transmit the driving force and properly control the tilt of the optical head.
Since this method takes a long time, it is not suitable for modern optical disk devices that require high-speed response.

Next, because gear backlash, cam, and shaft clearance are required, the movable parts of the device, including the optical head, have a structure that is susceptible to vibration. Therefore, when the optical head vibrates, there is a problem in that it becomes difficult to control the optical head such as focus control, tracking control, access control, etc.

Furthermore, when the weight of the movable part becomes heavy, the response speed becomes slow and the power consumption of the tilt drive motor increases.

In view of the above points, it is an object of the present invention to provide an optical head tilt correction device that is capable of high-speed response, allows easy control of the optical head, and consumes low power.

[0013]

[Means for Solving the Problems] In order to solve the above problem, the invention according to claim 1 includes an optical head guided in the radial direction of the optical disc by a rod-shaped guide member, and an optical head that is moved in the radial direction of the optical disc. a moving means for controlling, a support part for supporting a rod-shaped guide member, a rotation shaft for rotatably supporting the support part in the surface direction of the optical disc, and a rotation axis for moving the optical disc with the support part as a rotation center around the rotation axis. A driving means for driving the optical disk so that the light beam from the optical head is perpendicularly incident on the surface of the optical disk in the surface direction is provided.

In the second aspect of the invention, the rotation shaft is disposed in the vicinity of the center of gravity of the support when the optical head is at the innermost track position with respect to the optical disk.

In the third and fourth aspects of the invention, the driving means includes a laminated piezoelectric element and an elastically deformable metal transmission that transmits a driving force corresponding to the expansion and contraction of the laminated piezoelectric element to the support part. It is composed of parts.

[0016]

According to the invention having the above structure, the optical head and the support section including the moving means for moving the optical head in the radial direction of the optical disk are rotatably supported.

Further, the center of gravity is approximately the center of gravity when the optical head follows the innermost track position of the optical disk. When accessing an optical disk in its radial direction,
A moment of force that coincides with the direction of the tilt correction acts on the support.

[0018] The driving force caused by the expansion and contraction deformation of the laminated piezoelectric element is transmitted to the support part using the elastic deformation of the metal transmission member, and no mechanical parts such as gears or cams are used to transmit the driving force. .

[0019]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a three-view diagram of an embodiment of the present invention. In FIG. 1, a spindle motor 2 with an optical disk 1 mounted thereon is arranged on a base 21. As shown in FIG. base 21
Bearings 22, 22a are disposed on the bearing 22, 22a.
, 22a is the shaft 2 press-fitted into the sub-base 23 (supporting part).
4 and 24a (rotation shaft) are rotatably supported.

A yoke 25 is provided in the longitudinal direction of the sub-base 23.
, 25a are arranged, and permanent magnets 27, 27a are fixed to the yokes 25, 25a facing the optical head 26. Rod-shaped yokes 28, 28a are also fixed to the yokes 25, 25a, and the yokes 25, 25a,
A magnetic circuit is constituted by the permanent magnets 28, 28a and the permanent magnets 27, 27a.

The optical head 26 is provided with an actuator 5 and a tilt error detector 6.
are the guide rails 3, 3a supported by the sub-base 23 (
The optical disc 1 is guided by a rod-shaped guide member) and is configured to be able to move substantially parallel to the optical disc surface in the radial direction of the optical disc 1, indicated by A and A' in the figure.

The optical head 26 also includes yokes 28, 2.
Coils 29, 29a wound around 8a are fixed, and the voice coil motors 20, 20a are constituted by the above-mentioned magnetic circuit. The optical head 26 is driven in the radial direction of the optical disk 1 by electromagnetic force between the coils 29, 29a and the magnetic circuit. optical head 26
The center of rotation by the shafts 24, 24a is located approximately at the center of gravity of the optical head 26 when the optical head 26 is driven and positioned to follow the innermost track of the optical disc 1.

Next, FIG. 2 is a perspective view of essential parts of an embodiment of the present invention. In FIG. 2, a protrusion 30 is provided on the sub-base 23, and the protrusion 30 is supported by an arm 32 (transmission member) provided in a recess 31 of the base 21. As shown in FIG.

FIG. 3 is a side view showing an enlarged main part of an embodiment of the present invention. As shown in FIG. 3, the arm 32 is made of elastically deformable metal and has an L-shape.
It is integrally molded with. A laminated piezoelectric element 33 is adhesively fixed to the base portion 321, and the root portion 322 of the arm 32 is fixed to the base portion 321.
is supported. The laminated piezoelectric element 33 is connected to the control circuit 3
It can be expanded and contracted in the directions B and B' in the figure by means of control voltages from 4. The arm 32 is driven and elastically deformed by the expansion and contraction of the piezoelectric element 33, and the expansion and contraction of the piezoelectric element 33 is magnified and transmitted to its tip 323.

Returning to FIG. 2, the protrusion 30 is driven in the directions B and B' in the figure by the expansion and contraction deformation of the laminated piezoelectric element 33, thereby causing the sub-base 23 to move along the axis 24 (2).
4a) is configured to rotate relative to the base 21 with the rotation center as the rotation center.

As shown in FIG. 1, a protrusion 30a and an arm 32a (transmission member) are located symmetrically with respect to the optical head 26 with respect to the protrusion 30, arm 32, and laminated piezoelectric element 33.
, a laminated piezoelectric element 33a are provided. The laminated piezoelectric element 33a expands and contracts in response to a control voltage from the control circuit 34.

Therefore, when the tilt error detector 6 detects the tilt of the optical disk 1, the laminated piezoelectric element 33 (33a
) is controlled by the control circuit 34 to expand and contract, and controls the rotation of the sub-base 23 about the shaft 24 (24a) via the arm 32 (32a) and the protrusion 30 (30a). Therefore, the light beam from the optical head 26 to the optical disc surface is controlled to be incident perpendicularly to the optical disc surface.

According to the above embodiment, the sub-base 2 includes the optical head 26 and the voice coil motors 20 and 20a for driving the optical head 26 in the radial direction of the optical disc 1.
Since the optical head 3 is rotatably supported as one body, it is possible to correct the inclination of the optical head of the separation optical system as well.

The center of gravity of the sub-base 23 when the optical head 26 tracks the innermost circumference of the optical disk 1 is set as the center of rotation. The optical disk 1 often warps in the direction C in the front view of FIG. 1 due to its own weight at its outer peripheral portion. When the optical head 26 accesses the outer circumferential direction of the optical disc 1, a moment of force acts on the sub-base 23 in the C1 direction in the front view of FIG. Therefore, since the moment of this force matches the direction of the tilt correction, vibration of the sub-base 23, which is a movable part, can be suppressed.

Furthermore, since the driving force of the laminated piezoelectric elements 33, 33a is transmitted to the sub-base 23 by utilizing the elastic deformation of the metal, there is no gear backlash or clearance, so the sub-base 23 is less likely to vibrate. Tracking control of the optical head 26, etc. can be easily performed.

Furthermore, since the driving force is obtained by the expansion and contraction deformation of the laminated piezoelectric elements 33, 33a, even if the movable parts are heavy including the optical head 26 and voice coil motors 20, 20a, the power consumption is reduced compared to motor drive. Power is low.

Furthermore, since no mechanical parts such as gears or cams are used to transmit the driving force, it is possible to perform tilt correction with a fast response speed.

The shape of the transmission member is not limited to that of this embodiment, as long as it is made of metal that can be elastically deformed and transmit the driving force to the support portion.

[0035]

[Effects of the Invention] As described above, according to the present invention, high-speed response is possible, vibration is small, and the optical head can be easily controlled.
It has features such as low power consumption.

[Brief explanation of drawings]

FIG. 1 is a three-view diagram of an embodiment of the present invention.

FIG. 2 is a perspective view of essential parts of an embodiment of the present invention.

FIG. 3 is a side view showing an enlarged main part of an embodiment of the present invention.

FIG. 4 is a three-view diagram of a conventional optical head tilt correction device.

[Explanation of symbols]

1 Optical disk 3, 3a Guide rail (rod-shaped guide member) 7, 26
Optical head 20, 20a Voice coil motor (moving means) 23
Sub base (support part) 24, 24a Axis (rotation axis) 32, 32a Arm (transmission member) 33, 33a Laminated piezoelectric element

Claims (4)

[Claims] 1. An optical head guided in a radial direction of an optical disk by a rod-shaped guide member, a moving means for controlling the movement of the optical head in the radial direction of the optical disk, a support part for supporting the rod-shaped guide member, a rotation shaft that supports a support portion so as to be rotatable in a surface direction of the optical disk; What is claimed is: 1. A tilt correction device for an optical head, comprising: a drive means for driving the light to be incident perpendicularly to a surface. 2. The rotating shaft is disposed at a position near the center of gravity of the support portion when the optical head is at the innermost track position with respect to the optical disk. The optical head tilt correction device described above. 3. The driving means includes a laminated piezoelectric element;
2. The optical head tilt correction device according to claim 1, further comprising a transmission member that transmits a driving force corresponding to expansion/contraction deformation of the laminated piezoelectric element to the support portion. 4. The optical head tilt correction device according to claim 3, wherein the transmission member is made of elastically deformable metal.