JPH09171628A - Optical head device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate angle displacement control of a mirror for an optical head device by arranging a leaf spring so as to become wide width in the gravitational direction, fixing and supporting its both ends to a support frame body and attaching the mirror on the intermediate part of the leaf spring. SOLUTION: One end part of a pin 37 is fitted and fixed to a fixed hole 38 bored on the support frame body 22 in press-in state, and a washer 39 is fitted to the other end part, and a compression coil spring 40 is inserted between the washer 39 and a pedestal 21. The support frame body 22 is energized so as to slant downward always by the elastic biased force of the compression coil spring 40. Further, an adjusting screw 42 is inserted into a through-hole 41 bored on the pedestal 21 above a roller 35, and its tipis screwed in a screw hole 43 board on the support frame body 22. By rotatablly operating the screw 42, the support frame body 22 is slanted around the roller 35 in the direction of ω2 for the pedestal 21, and the angular adjustment of the mirror 25 in the direction perpendicular to an optical axis surface of a light beam is performed. Then, the optical axis L of the light beam reflected by the mirror 25 is precisely matched with a slide feed shaft of a lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head device used in an optical disk system, and more particularly to the structure of an optical deflecting device used as its tracking actuator.

[0002]

2. Description of the Related Art In an optical head device used in an optical disk system, there is a system in which a high frequency region is separated into an optical deflecting device (galvano mirror device) and a low frequency region is separated into a slide motor as a tracking servo actuator.

That is, an optical head device of this type has a fixed optical system composed of an optical block containing a laser diode and a photodetector, and a galvanometer mirror device as an optical deflecting device for reflecting and deflecting a light beam emitted from this optical block. And a movable optical system composed of an objective lens that focuses the light beam reflected by the galvano mirror device on the recording surface of the disc and a slide motor that slides the objective lens in the radial direction of the disc. Bandwidth limitation is performed on each actuator, that is, the galvanometer mirror device and the slide motor, and accurate and quick tracking operation is performed by the cooperation of the galvanometer mirror device and the slide motor.

Attention is paid to the galvanometer mirror device used in the optical head device constructed as described above. This galvanometer mirror device has a mirror for reflecting the light beam incident from the optical block toward the objective lens. The mirror is angularly displaced in the direction perpendicular to the optical axis of the light beam by the tracking signal from the servo system, whereby the light beam is deflected and fine tracking control is performed.

[0005]

Conventionally, in such a galvanometer mirror device, a structure has been adopted in which the mirror is supported by an elastic material so that the mirror can be angularly displaced in the direction perpendicular to the optical axis of the light beam. However, in this structure, the elastic material is easily bent downward due to the weight of the mirror, and the normal state, that is, the initial state of the mirror is changed by this bending deformation,
For example, the mirror tilts so as to fall forward and downward.

Therefore, in this galvanometer mirror device, it is necessary to apply an initial force for holding the mirror in a predetermined initial state to the mechanism for controlling the angular displacement of the mirror, which complicates the control. Further, due to the tilting of the mirror due to the bending of the elastic material described above, the angular displacement force required during the servo control for angularly displacing the mirror also becomes uneven, which makes it difficult to perform control with high accuracy. Become.

The present invention has been made in view of the above problems, and prevents the control from being complicated and the control accuracy from being deteriorated due to the self-weight of the mirror as described above, thereby facilitating the control with high accuracy. There is a problem to be solved in order to be able to carry out.

[0008]

In the optical head device of the present invention, the optical deflecting device (galvanic mirror device) fixedly supports both ends of a leaf spring arranged so as to be wide in the direction of gravity, and A mirror that is angularly displaced in the direction perpendicular to the optical axis of the incident light beam is supported in the middle of the spring.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a spindle motor, 2 is a turntable attached to the drive shaft of the motor 1, and an optical disk D is mounted and held on the turntable 2. Reference numeral 3 indicates an optical head device as a whole for reading or writing a signal from the disk D, and reference numeral 4 indicates a base on which the constituent members are mounted and fixed.

The optical head device 3 is roughly divided into a fixed optical system 5 and a movable optical system 6. First, the fixed optical system 5 includes an optical block 10 including a laser diode 7, a photodetector 8, a beam splitter 9, and the like.
And a galvanometer mirror device 11 as an optical deflecting device for reflecting and deflecting the light beam emitted from the optical block 10 to perform precise tracking. The configuration of the galvano mirror device 11 will be described in detail later.

On the other hand, the movable optical system 6 includes an objective lens 12 and
A slide block 14 having a prism 13 for raising the optical axis L of the light beam reflected by the galvanometer mirror device 11 to this objective lens 12 is provided, and this slide block 14 is moved by an objective lens feed mechanism 15 to a disk. It is configured to be slid in the radial direction of D.

The objective lens feeding mechanism 15 is constructed as follows. That is, the guide rail 16 is fixed on the base 4 in parallel with the disc D, and the slide block 14 is movably supported along the guide rail 16. The slide block 14 is driven by a linear motor, that is, the linear motor includes a yoke 17 and a magnet 18 fixed to the base 4 side, and a coil 19 wound around the slide block 14.
When the reproducing (or recording) operation is performed, a tracking signal is supplied to the coil 19 so that the slide block 1
4 drives in the radial direction of the disk D along the guide rail 16, that is, the objective lens 12 is fed. Reference numeral 20 denotes a focus coil for focusing the objective lens 12.

The optical head device 3 of this embodiment is constructed by arranging the fixed optical system 5 and the objective lens feeding mechanism 15 constituting the movable optical system 6 on one plane, that is, the fixed optical system. The optical block 10 of 5 is fixed to the base 4 in a horizontal state so that the light beam is emitted in the horizontal direction (direction parallel to the disk D), and the light beam emitted from the optical block 10 is aligned with its optical axis. The galvano-mirror device 11 arranged at 45 ° horizontally reflects the object lens 12 in a direction that coincides with the moving direction (feed axis) of the objective lens 12 and guides it to the movable optical system 6. After being raised in the direction, the objective lens 12 forms a spot on the recording surface of the disc D.

That is, the optical axis L of the light beam emitted from the optical block 10 is expanded on one plane in which all the optical axes except the rising portion to the objective lens 12 are parallel to the disk D. Become. Therefore, in this case, the normal line of the galvanometer mirror device 11 is the optical surface (galvanometer mirror device 11
Optical axis of the light beam incident on and the galvanometer mirror device 1
1 is arranged so as to move in a plane perpendicular to the plane formed by the optical axis of the light beam reflected by 1.

2 to 5 show the detailed structure of the galvanometer mirror device 11, in which 21 is a base thereof and 22 is supported on the base 21 so as to be rotatable and adjustable through an adjusting mechanism which will be described later. It is a supporting frame body. A mirror support 23 is rotatably supported on the support frame 22 via a leaf spring 24 in a vertical direction, that is, in a direction perpendicular to the optical axis plane of the light beam. A mirror 25 that reflects the light beam is attached. Here, as shown in FIG. 3, the leaf spring 24 is arranged horizontally so as to be wide in the direction of gravity, and both left and right ends of the leaf spring 24 are fixedly supported by the support frame 22. The mirror support 23, that is, the mirror 25 is supported in the middle part.
Further, a coil 26 is wound around the peripheral surface of the mirror support 23, and magnets 27 are vertically attached to the support frame 22 side facing the coil 26 to form a galvano motor.

Further, this galvanometer mirror device 11
In the above, an adjusting mechanism for adjusting the angular position of the mirror 25 is provided. This adjusting mechanism has the following configuration. The base 21 of the galvano mirror device 11 is
A support hole 28 formed in the front portion is fitted into a projecting column 29 projecting from the base 4, and the projecting column 29 is the center in a lateral direction with respect to the base 4, that is, parallel to the optical axis plane of the light beam. It is rotatably supported in different directions (ω ₁ direction). Base 2
An elongated hole (correctly, an arcuate elongated hole centering on the projecting column 29) 30 is formed in the rear portion of the first portion 1 in the lateral direction. It is screwed into a screw hole 32 formed in the. Then, by loosening the adjusting screw 31, the base 21 is moved toward the base 4 by ω
It becomes rotatable in _one direction, that is, the angle of the mirror 25 can be adjusted in the direction parallel to the optical axis surface of the light beam, and after the adjustment is completed, the adjusting screw 31 is tightened to fix the base 21 at that position.

On the other hand, the roller 3 is provided between the V-shaped grooves 33 and 34 formed so as to face each other between the base 21 and the support frame 22.
5, the support frame 22 is tiltable with respect to the base 21 in the up-down direction, that is, in the direction (ω ₂ direction) perpendicular to the optical axis plane of the light beam. Further, a shaft-shaped pin 37 is inserted into a through hole 36 formed in the base 21 below the roller 35 (this pin 3
7 are provided on the left and right), one end of these pins 37 is press-fitted into a fixing hole 38 formed in the support frame 22, and a washer 39 is fitted to the other end. A compression coil spring 40 is fitted between the washer 39 and the base 21, and the support frame 22 is always biased downward by the elastic biasing force of the compression coil spring 40. Has been done. An adjusting screw 42 is inserted into a through hole 41 formed in the base 21 above the roller 35, and a tip end of the adjusting screw 42 is screwed into a screw hole 43 formed in the support frame 22. By rotating the screw 42, the support frame 22 is rotated by ω ₂ around the roller 35 with respect to the base 21.
The mirror 25 is tilted in the direction, that is, the angle of the mirror 25 is adjusted in the direction perpendicular to the optical axis of the light beam.

By operating the adjusting screws 31 and 42 in this way, the angle of the mirror 25 is independently adjusted in the ω ₁ direction and the ω ₂ direction, and the optical axis L of the light beam reflected by the mirror 25 is adjusted. It is possible to exactly match the slide feed axis of the objective lens 12.

Then, in this way, the galvanometer mirror device 11
With the angular position adjusted, the tracking signal is supplied from the servo system to the coil 26 during the reproducing (or recording) operation, so that the mirror 25 moves in the vertical direction, that is, in the direction perpendicular to the optical axis plane of the light beam. The optical axis L of the light beam is deflected by this, and the position of the spot focused on the recording surface of the disc D moves in the disc radial direction, that is, fine tracking is performed.

In this galvanometer mirror device 11,
Since both ends of the leaf spring 24 are fixedly supported by the support frame 22 so as to be wide in the direction of gravity, the weight of the mirror 25 supported at the intermediate portion of the leaf spring 24 may cause the leaf spring 24 to bend downward. Suppressed. Therefore, it is possible to prevent the center position of the mirror 25 from being displaced and to hold the mirror 25 in the vertical state. Therefore, an initial force for holding the mirror 25 in the vertical state is applied to the drive mechanism that controls the angular displacement of the mirror 25. It becomes unnecessary to give it. Further, the bias of the force when the mirror 25 is angularly displaced in the vertical direction by the servo operation is eliminated. As a result, the angular displacement of the galvanometer mirror device 11 can be controlled easily and with high accuracy.

Although one embodiment of the present invention has been described above, the present invention is not limited to the configuration of this embodiment and various embodiments can be adopted, and this embodiment specifies the present invention. Of course not.

[0022]

As described above, in the optical head apparatus of the present invention, the optical deflector has the mirror supported on the intermediate portion of the leaf spring arranged so as to be wide in the direction of gravity. There is an effect that the mirror is prevented from bending due to its weight, adjustment work for setting the mirror at a predetermined angular position is facilitated, and angular displacement control of the mirror is facilitated.

[Brief description of the drawings]

FIG. 1 is a perspective view of an optical head device according to the present invention.

FIG. 2 is a plan view of a galvanometer mirror device (optical deflection device) used in the optical head device according to the present invention.

FIG. 3 is a front view of the same.

FIG. 4 is a perspective view of the same.

FIG. 5 is a vertical side view of the same.

[Explanation of symbols]

3 ... Optical head device, 5 ... Fixed optical system, 6 ... Movable optical system, 7 ... Laser diode, 8 ... Photodetector, 11 ... Galvano mirror device (optical deflector), 1
2 ... Objective lens, 15 ... Objective lens feeding mechanism, 24
Flat leaf, 25, mirror, D, disc, L
Optical axis of light beam

Claims (1)

[Claims] 1. A fixed optical system having a laser diode, a photodetector, and a light deflector, and a mechanism for feeding an objective lens forming a movable optical system to the fixed optical system in a radial direction of a disc. The optical deflector fixedly supports both end portions of a leaf spring arranged so as to be wide in the direction of gravity, and an intermediate portion of the leaf spring is provided in a direction perpendicular to the optical axis of an incident light beam. An optical head device characterized in that a mirror that is angularly displaced is supported.