JPH0490506A - Rotary mirror device for tracking - Google Patents

Abstract

PURPOSE:To make the rotational attitude of a reflecting mirror more secure, to expand the frequency range of the tracking, and to record and reproduce data at a high speed by regulating the center of rotation of the reflecting mirror by an elastic member and restraining the translational motion of the reflecting mirror by a thin leaf spring. CONSTITUTION:When a current flows through a driving coil 13, a force is generated perpendicularly to the reflecting surface of the reflecting mirror 10. This force is restrained by the thin leaf spring 12 through a mirror holding member 11, so the force is converted into a moment force centering on the twist part 12c of the spring 12 and the mirror 10 rotates around the twist part 12c. The center of rotation of the mirror 10 is regulating by a pivot member 17 and the translational motion of the mirror 10 based upon the force generated at right angles to the reflecting surface of the mirror 10 can be restrained without applying any tension to the spring 12. Consequently, the rotational attitude of the reflecting mirror is made more secure, the frequency range of the tracking is expanded, and the data can be recorded and reproduced at high speed.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a rotating mirror device for tracking used in an optical head of an optical disk device, for example, for making a light beam spot follow a track of an optical disk. It is something.

[Prior Art] Conventionally, in this type of rotating mirror device for tracking, in order to rotatably hold the reflecting mirror, one end of a rubber member such as silicone is bonded and baked onto the mirror holding member to serve as a supporting member. something is known. Further, as shown in FIGS. 8 and 9, by supporting the mirror holding member 2 that holds the reflecting mirror 1 with a thin plate spring 3 or a wire, the reflecting mirror 1 can be driven by the drive coil 4 and the mirror can be held. A system has been proposed in which a pivot shaft 5 made of a rigid body is provided to define the center of rotation of the member 2.

[Problems to be Solved by the Invention] Among the conventional examples described above, in the former method in which a rubber member is used as a support member, the rotation angle is non-linear with respect to the current flowing through the drive coil due to hysteresis accompanied by permanent deformation peculiar to the rubber member. Control becomes complicated due to the characteristics of rubber parts and variations in mechanical properties between lots of rubber parts.
Further, there are problems such as difficulty in defining the neutral position and center of rotation. In addition, the latter method using the pivot shaft 5 generates frictional force due to tension and uncoupling force that push the center of rotation of the reflecting mirror l in one direction, which increases the resonance frequency and disturbs the frequency characteristics. It has drawbacks such as being easily stowed away.

An object of the present invention is to make it possible to regulate the translational movement of a reflecting mirror without applying tension to the thin plate spring that supports the mirror holding member, thereby making the rotating posture of the reflecting mirror more reliable;
Another object of the present invention is to provide a rotating mirror device for tracking that can reduce the resonance frequency caused by the mirror holding member, expand the tracking frequency band, and perform data recording and reproduction at high speed.

[Means for Solving the Problems] In order to achieve the above-mentioned object, a tracking rotating mirror device according to the present invention includes a tracking rotating mirror device that drives a light beam spot in the radial direction of an optical disk of an information recording medium. A mirror device in which a mirror holding member for holding a reflecting mirror is rotatably supported by a thin plate spring,
The flat part of the thin plate spring is overlapped with the reflective surface of the reflective mirror, and the thin plate spring is bent between the flat part and the attachment part to the thin plate spring support member to prevent twisting for the rotation. The present invention is characterized in that an elastic member is provided, which forms a portion, contacts the flat portion of the thin plate spring from the back side, and has low rigidity with respect to the rotating direction of the reflecting mirror.

[Operations] The rotating mirror device for tracking having the above-mentioned configuration is
The elastic member has a shape with reduced rigidity in the desired direction of rotation,
To define the center of rotation of a reflecting mirror and to regulate the translational movement of the reflecting mirror without applying tension to a thin plate spring.

[Example] The present invention will be described in detail based on the example illustrated in FIGS. 1 to 7.

FIG. 1 is a side view of an embodiment applied to a rotating mirror device for tracking in which a reflecting mirror is suspended by a thin plate spring, and FIG. 2 is a perspective view thereof.

The reflective mirror IO has a mirror holding member 1 on the back side of its reflective surface.
The mirror holding member 1 is held by sticking it to the mirror holding member 1.
1 is suspended and held by a thin plate spring 12. A drive coil 13 is wound around the side surface of the mirror holding member 11, and a yoke 14 and a relay yoke 15 are provided on both sides of the coil 13 so as to sandwich the coil 13.
．． A permanent magnet 16 is interposed between the magnets 15 and 15 . Thin spring 1
2, as shown in FIG. 3, a mounting portion 12a for attaching to the mirror holding member 11, two mounting portions 12b for supporting the thin plate spring 12, and two torsion portions for rotating the reflecting mirror 10. 12c, and this twisted part 12c is the mounting part 12a.
and the attachment part 12b to create a bridged state, and by changing the width of the torsion part 12c and the thickness of the thin plate spring 12, it is possible to change the torsional rigidity and change the next torsional resonance frequency. has been done. The reflection mirror 10 is rotated by a magnetic circuit including a yoke 14, a relay yoke 15, and a magnet 16, and driven by a drive coil 13, and the two torsion portions 12c of the thin plate spring I2 serve as centers of rotation.

As a means for defining the center of rotation of the reflecting mirror 10 and regulating the translational movement, a POM is installed on the back surface of the mirror mounting portion of the mirror holding member 11, that is, on the back surface of the mounting portion 12a of the thin plate spring 13.
The pivot member 17 shown in FIG. 4 is connected to the tip of the pivot member 17 as shown in FIG. 5. This pivot member 17 has a flat part 17a at its tip and a hinge part 17b at the center of rotation.The hinge part 17b is given a considerable width to maximize the rigidity of the reflecting mirror 10 in the direction of rotation. It is a small elastic member.

For example, when a current flows through the drive coil 13, a force is generated in a direction perpendicular to the reflective surface of the reflection mirror 10 in FIG. Since it is restrained, it 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. The center of rotation of the reflective mirror 1o is defined by the pivot member 17, and the translational movement of the reflective mirror 10 due to a force generated in a direction perpendicular to the reflective surface of the reflective mirror 10 is regulated without applying tension to the thin plate spring 12. be able to.

The above is an example in which the rigidity in the desired direction of rotation is reduced using the shape effect, and as shown in FIGS. A similar effect can be obtained by supporting the pivot shaft 19. Here, the pivot shaft 19 is connected to the thin plate spring 1.
An elastic member 18 made of room temperature vulcanizable silicone rubber or the like is bonded to the mounting portion 12a of the mirror 1 without applying tension to the mirror holding member 11 or the thin plate spring 12.
The translational movement of 0 is regulated. Although the tip of the pivot shaft 19 in this case is spherical, it may be shaped like a knife in order to more reliably define the center of rotation of the reflecting mirror 10.

[Effects of the Invention] As explained above, the rotating mirror device for tracking according to the present invention can make the rotating posture of the reflecting mirror more reliable, and suppress the torsional resonance frequency caused by the reflecting mirror support member to a low level. Therefore, the tracking frequency band is expanded, and as a result, it becomes possible to speed up data recording and reproduction.

[Brief explanation of drawings]

1 to 7 show an embodiment of the rotating mirror device for tracking according to the present invention, in which FIG. 1 is a side view, FIG. 2 is a perspective view, FIG. 3 is a plan view of a thin plate spring, and FIG. 4 is a perspective view of the pivot member, FIG. 5 is a partially cutaway perspective view, FIG. 6 is a front view of the thin plate spring of the second embodiment, and FIG. 7 is a partially cutaway perspective view. , FIG. 8 is a perspective view of the conventional example, and FIG. 9 is a partially cutaway plan view thereof. 10 is a reflecting mirror, 11 is a mirror holding member, 12 is a thin plate spring, 13 is a drive coil, 14 is a yoke, 15 is a relay yoke, 16 is a magnet, 17 is a pivot member, 18 is an elastic member, and 19 is a pivot shaft. be.

Claims (1)

[Claims] 1. A rotating mirror device for tracking that drives a light beam spot in the radial direction of an optical disk of an information recording medium, in which a mirror holding member that holds a reflecting mirror is rotatably supported by a thin plate spring, and a flat portion is superimposed on the reflective surface of the reflective mirror, and the thin plate spring is constricted between the flat portion and an attachment portion to the thin plate spring support member to form a torsion portion for the rotation; A rotating mirror device for tracking, characterized in that an elastic member is provided which abuts the plane portion of the thin plate spring from the back side and has small rigidity with respect to the rotating direction of the reflecting mirror.