JPH04243029A - Turning mirror device for tracking - Google Patents

Abstract

PURPOSE:To allow control with high accuracy and to obtain a small-sized turning mirror by using a sheet spring for turning and supporting the mirror. CONSTITUTION:A reflection mirror 10 is held by a mirror holding member and the rear surface of the mirror mounting surface of this holding member or the rear surface of the reflection surface of the reflection mirror 10 is supported by the sheet spring 12 or wire and the torsion thereof is used. The disposition of a magnetic circuit is disposed in the space on the rear surface of the mirror 10 and the turning center can be brought to the center of the mirror 10 as shown in Fig. A. Then, the turning center A is so disposed as to be positioned at the center of a coil 13 and a permanent magnet 15 is disposed on the inner side of the coil 13 to reduce the device size at the time of generating moment force by looping the magnetic flux flow intersecting with the coil 13 in one direction. The magnetic flux density between a yoke 14 and the magnet 15 is thus increased and the high-accuracy control is executed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an optical disk device.
In particular, the present invention relates to a tracking rotating mirror device for causing a light beam spot to follow a track of an optical disk in the optical head.

0002

2. Description of the Related Art Conventionally, there are two types of tracking rotating mirror devices of this type, as shown in FIGS. 4 to 7. That is, FIGS. 4 and 5 show a conventional example in which a reflective mirror is supported by a rubber member, and a mirror holding member 2 that holds a reflective mirror 1 has one end of a supporting member 3 made of silicone rubber or the like bonded and baked on the back surface. The base 4 is connected via this support member 3.
The mirror holding member 2 is supported by a coil 5 attached to the rear portion of the mirror holding member 2 to rotate.

6 and 7 show a conventional example in which a reflecting mirror 1 is supported by a rotating shaft, and the reflecting mirror 1 has a bearing 6a at one end.
A driving force acting between a coil 8 and a magnetic circuit 9 attached to the back surface of the support member 6, which is attached to a support member 6 having Rotationally driven by.

0004

[Problems to be Solved by the Invention] However, in the rotating mirror device for tracking shown in FIGS. 4 and 5, in which the mirror is made rotatable by being supported by a rubber support member 3, it is difficult to set the desired direction of rotation. In order to restrict rotation in orthogonal directions, it is necessary to widen the width of the rubber considerably. Therefore, the volume that the rubber support member 3 occupies inside the drive coil 5 becomes large, making it difficult to effectively arrange the magnetic circuit. Furthermore, control becomes complicated because the rotation angle has non-linearity with respect to the current flowing through the drive coil due to hysteresis peculiar to the rubber member, and mechanical properties vary between lots of the rubber support member.

[0005] Also, the tracking rotating mirror device of the type using the rotating shaft 7 shown in FIGS. 6 and 7 has a magnetic circuit configuration in which a driving force is generated in a direction perpendicular to the driving coil. Therefore, the center of rotation is offset laterally and two magnets are required. Furthermore, it is difficult to maintain the neutral position, and when rotating by a minute angle, stick slip occurs, resulting in strong nonlinearity and complicated control. Further, since the gap between the shaft 7 and the bearing 6a becomes loose during rotation, the machining accuracy of these parts becomes high and the cost becomes high. From the above points, the conventional type of rotating mirror device for tracking has a problem in realizing a compact device that can rotate at a small angle at high speed.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a rotating mirror device for tracking that is compact and capable of highly accurate control.

[0007] Such an objective is to provide a moving coil-type rotating mirror device for tracking that drives a light beam spot in the radial direction of an optical disk, which includes a reflective mirror member, a mirror holding member that holds the reflective mirror member, and a rotating mirror device for tracking. A thin plate spring rotatably supporting the reflecting mirror holding member, a thin plate spring supporting member supporting the thin plate spring, a moving coil attached to the mirror holding member, and driving the reflecting mirror member in cooperation with the moving coil. a permanent magnet and a yoke disposed to sandwich the moving coil that generates a driving force for moving the thin plate spring; This is achieved by forming a torsion portion for the rotation.

[0008]

[Operation] FIG. 1 shows the structure of a rotating mirror device for tracking according to the present invention. The reflective mirror 10 is attached to the mirror holding member 1
1, and the back surface of the mirror mounting surface of this mirror holding member 11 or the back surface of the reflective surface of the reflective mirror is suspended by a thin plate spring 12 or a wire (not shown) so as to be rotatable.

[0009] This makes it possible to arrange a magnetic circuit in the space behind the reflecting mirror 10, and also allows the center of rotation to be at the center of the reflecting mirror 10, as shown in FIG. 2A. Therefore, when the permanent magnet 15 is arranged so that the rotation center A is at the center of the coil 13 and the magnetic flux flow crossing the coil 13 is made into a unidirectional loop to generate a moment force, the permanent magnet 15 is placed at the center of the coil 13. Since it can be placed inside the yoke 14, it can be miniaturized, and since the gap magnetic flux density between the yoke 14 and the magnet 15 can be easily increased, it is possible to control it with high accuracy.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail based on the embodiments shown in FIGS. 1 to 3.

FIG. 1 is a perspective view of an embodiment in which a reflecting mirror is suspended by a thin plate spring, FIG. 2 is a sectional view thereof, and FIG. 3 is an assembled view thereof.

The reflecting mirror 10 is held by attaching the back side of its reflecting surface to a mirror holding member 11, and the mirror holding member 11 is suspended and held by a thin plate spring 12. A driving coil 13 is wound around the side surface of the mirror holding member 11, and a yoke 14 and a permanent magnet 15 are provided on both sides of the coil 13 so as to sandwich the coil 13.
The yoke 14 and the permanent magnet 15 are magnetically connected by a relay yoke 16.

The permanent magnet 15 also has an annular drive coil 13.
is placed inside. As shown in FIG. 3, the thin plate spring 12 includes an attachment part 12a for attaching to the mirror holding member 11, two attachment parts 12b for supporting the thin plate spring 12, and two torsion parts for rotating the reflecting mirror 10. The torsion part 12c constricts the space between the attachment part 12a and the attachment part 12b to form a bridge, and the torsional rigidity is changed by changing the width of the torsion part 12c and the thickness of the thin plate spring 12. It is said that it is possible to change the primary torsional resonance frequency. The reflection mirror 10 is rotated by a magnetic circuit composed of a yoke 14, a relay yoke 16, and a permanent magnet 15, and driven by a drive coil 13.
The two twisted portions 12c serve as the center of rotation. Reflection mirror 1
A pivot shaft 17 is brought into contact with the back surface of the mirror mounting portion of the mirror holding member 11, that is, the back surface of the mounting portion 12a of the thin plate spring 12, as a means for defining the center of rotation of 0 and regulating translational movement.

For example, when a current flows through the drive coil 13, a force is generated in a direction perpendicular to the reflecting surface of the reflection mirror 10, but this force is restrained by the drive coil 13 via the mirror holding member 11 by the thin plate spring 12. Therefore, the force is converted into a moment force centered on the torsion portion 12c of the thin plate spring 12, and the reflecting mirror 10 rotates around the torsion portion 12c as shown by the arrow in FIG. The center of rotation of the reflecting mirror 10 is defined by a pivot axis 17, and the thin plate spring 12
The translational movement of the reflecting mirror 10 due to the force generated in the direction perpendicular to the reflecting surface of the reflecting mirror 10 can be restricted without applying tension to the reflecting mirror 10.

Further, in the above embodiment, the torsion portion 12c has a flat plate structure, but in order to change the moment of inertia of the area, sheet metal press processing such as bending, hollowing, punching, etc. may be performed. may also be used. Note that the thin plate spring 12 may be made of a synthetic resin material in addition to stainless steel, phosphor bronze, or beryllium copper.

[0016]

As described above, the rotating mirror device for tracking of the present invention uses a thin plate spring torsion to support rotation of the mirror, so that a magnetic circuit can be configured on the back surface of the reflecting mirror with few restrictions. When moment drive is adopted, it can be configured with a single magnet, making it possible to provide a high-performance and compact rotating mirror device for tracking.This makes it possible to provide a compact optical disk recording and reproducing device that is capable of recording and reproducing data at high speed. do.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a rotating mirror device for tracking according to the present invention;

FIG. 2 is a cross-sectional view of the device shown in the first diagram;

[Figure 3] Assembly diagram of the device shown in the first figure

FIG. 4 is a diagram showing a conventional example.

FIG. 5 is a diagram showing a conventional example.

FIG. 6 is a diagram showing a conventional example.

FIG. 7 is a diagram showing a conventional example.

[Explanation of symbols]

10 Reflection mirror 11 Mirror holding member 12 Thin leaf spring 13 Coil 15 Permanent magnet 16 York

Claims (1)

[Claims] 1. A moving coil type rotating mirror device for tracking that drives a light beam spot in the radial direction of an optical disk, the device comprising: a reflective mirror member, a mirror holding member that holds the reflective mirror member, and a reflective mirror holder. A thin plate spring that rotatably supports a member, a thin plate spring support member that supports the thin plate spring, a moving coil attached to the mirror holding member, and a drive for driving the reflecting mirror member in cooperation with the moving coil. A yoke and a permanent magnet are arranged to sandwich the moving coil that generates a force, and the thin plate spring is constricted between the reflecting mirror support part and the attachment part for the thin plate spring support member to rotate the thin plate spring. A rotating mirror device for tracking, characterized in that it has a twisting portion for rotating the mirror.