JP2867304B2 - Optical disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus of a separation type using a galvanometer mirror.

[0002]

2. Description of the Related Art A head of an optical disk has a separation type head in which an actuator section for holding an objective lens and a laser oscillation section are separated and only the actuator section moves.
There is an integrated head in which both move together. The former separation type head is easy to reduce the weight, and is advantageous for speeding up the tracking operation. Also, in order to further reduce the weight of the separation type head, taking into account that the tracking operation includes two different frequency regions, the tracking in the low frequency region is controlled by a linear motor provided on the head, and the tracking in the high frequency region is performed. Is performed using a galvanomirror separated from a head.

In this galvanomirror type optical disk apparatus, a galvanomirror is provided on an optical path from a laser light source to an optical head, and the optical path of incident laser light is changed by slightly inclining the galvanomirror to control tracking. I have. The rotation angle at this time is only a few minutes,
The tilt angle of the galvanomirror needs to be constantly measured because it is an amount that can be sufficiently displaced under vibration conditions.

As a method for detecting the rotation angle of the galvanomirror with high accuracy, a non-contact optical method has been devised as shown in FIG. According to this method, the fixed mirror 2 is arranged at a position facing the galvanometer mirror 1 arranged obliquely with respect to the optical path L, and a laser beam is emitted from the light emitting element 3 provided on the side of the fixed mirror 2, The light path length and the rotation angle are enlarged by reciprocating reflection between the mirror 1 and the fixed mirror 2 a plurality of times. In this type of rotation angle measurement mechanism, since there is no contact, no burden is imposed on the driving of the ruvano mirror. This has the advantage that the angle can be sufficiently detected.

[0005]

However, considering the incorporation of the rotation angle measuring means into a small optical disk device, a light emitting element and a light receiving element are separately arranged near the fixed mirror as in the above-mentioned conventional example. This is very difficult due to space constraints.

An object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide a small-sized optical disk device for measuring a rotation angle of a galvanomirror with high accuracy using a part of a laser beam irradiated on an optical disk.

[0007]

According to the present invention, there is provided an optical disk apparatus for irradiating a laser beam from a laser light source with a galvanomirror and irradiating the laser beam onto an optical disk. A light splitting member is arranged in an optical path from the optical disk to the optical disk to split a part of the laser light toward the optical disk, and the split laser light is transmitted between the galvano mirror and a fixed mirror arranged opposite thereto. After the light is reflected back and forth a plurality of times, the light is received by a detector, and the rotation angle of the galvanometer mirror is detected based on the incident position of the detector.

[0008]

In the optical disk apparatus having the above-described structure, a part of the laser light emitted from the laser light source for irradiating the optical disk is split by the light splitting member and reflected back and forth between the galvanometer mirror and the fixed mirror a plurality of times. It is detected later by the detector, but since the reflection angle changes in proportion to the rotation angle of the galvanomirror, the rotation angle of the galvanomirror is detected as an enlarged position change on the detector.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a plan view of a main part of a separation type optical disk device. An outer yoke 11, a permanent magnet 12, and an inner yoke 13 are installed in the radial direction of the optical disk in parallel and symmetrically to form a magnetic circuit. The movable optical head is a carriage 1 having a tracking coil 14.
5 and an actuator 17 having an objective lens 16 are arranged back and forth, and are connected by a leaf spring 18.
The inner yoke 13 of the book is inserted.

The inner surface of the inner yoke 13 and the carriage 15
A V-shaped groove (not shown) is engraved on the outer surface, and a ball 19 is arranged therebetween. Thereby, the carriage 1
Numeral 5 is movably supported along the radial direction of the optical disk, that is, along the inner yoke 14, and the actuator 17 is driven back and forth by a linear motor including a tracking coil 14 and a magnetic circuit.

An optical system for sending laser light to the optical head is arranged behind the magnetic circuit, and a beam splitter 22 is provided on an optical path from the laser light source 21 to the optical head.
Galvano mirrors 23 are sequentially arranged. That is,
The light transmitted through the beam splitter 22 is guided to a rotation angle detection mechanism, and the light reflected by the half mirror 22 a of the beam splitter 22 is guided to an optical head via a galvanometer mirror 23. The light returned from the optical head is guided to a condenser lens 24 and a sensor 25 via a galvanomirror 23 and a beam splitter 22.

The rotation angle detecting mechanism includes a first first mirror 26.
And the galvanometer mirror 23 and the two reflecting surfaces 27a and 27b
And a light receiving element 29 fixed to a fixed substrate 28 having a fixed elongated hole 28a as shown in FIG. And arranged on the optical path in this order.

In the above-described configuration, the laser light emitted from the laser light source 21 is reflected by the half mirror 22a of the beam splitter 22 and the galvano mirror 23 rotated by a predetermined angle and reaches the optical head. The laser light incident on the optical head is reflected by a mirror (not shown), and is condensed on the optical disk by the objective lens 16. The laser light reflected on the disk returns to the galvanometer mirror 23 through the same path, passes through the half mirror 22a of the beam splitter 22, is collected by the condenser lens 24, forms an image on the sensor 25, and is detected as a signal. You.

The laser light emitted from the laser light source 21 and transmitted through the half mirror 22a is guided to a rotation angle detecting mechanism. That is, the laser light that has entered the galvanometer mirror 23 via the first mirror 26 is reflected a plurality of times between the second mirror 27 and the galvanometer mirror 23. At this time, as shown in FIG. 3, the rotation angle θ of the galvanometer mirror 23 is amplified each time reflection is repeated between the two mirrors 23 and 27, and in the example shown in the drawing, the rotation angle θ is enlarged to 8θ. The laser beam having undergone the amplification of the rotation angle has a sufficient optical path length and is emitted toward the light receiving element 29.
The direction can be largely changed on the other reflection surface 27b. The product of the rotation angle and the optical path length is a lateral displacement, and the rotation angle θ can be detected in the form of the light receiving position of the light receiving element 29.

In the rotation angle detecting mechanism, since the rotation angle is enlarged, the first mirror 26 and the second mirror 2
7, the mounting error is also increased. Therefore, FIG.
A fixed long hole 28a is provided in a fixed substrate 28 having a light receiving element 29 as shown in FIG. Mounting errors are offset.

[0016]

As described above, in the optical disk apparatus according to the present invention, the laser beam is split into two by the light splitting member, and one of the laser beams is detected through multiple round trip reflections between the galvanometer mirror and the fixed mirror. Is detected as the displacement of the vessel,
The enlarged rotation angle of the galvanomirror can be detected in a small space, and a light emitting element for detecting the rotation angle is not required, so that the apparatus can be downsized.

[Brief description of the drawings]

FIG. 1 is a plan view of a main part of an optical disk device.

FIG. 2 is an explanatory diagram of a method of mounting a rotation angle detecting light receiving element.

FIG. 3 is an explanatory diagram of a process of expanding a rotation angle of a galvanomirror.

FIG. 4 is a perspective view of a conventional rotation angle detection mechanism.

[Explanation of symbols]

 Reference Signs List 21 laser light source 22 beam splitter 22a half mirror 23 galvano mirror 26, 27 mirror 29 light receiving element

Claims (2)

(57) [Claims] 1. A galvanic laser light from the laser light source
Optical disc that irradiates the optical disc after being reflected by a mirror
The optical disk from the laser light source.
A light splitting member is arranged in the optical path leading to
A part of the laser beam is split and the split laser
The light is arranged opposite to the galvanometer mirror
After multiple reciprocating reflections with the fixed mirror,
An optical disk device , which receives light and detects a rotation angle of the galvanometer mirror based on an incident position of the detector. 2. The optical disk device according to claim 1, wherein the detector is capable of adjusting a position.