JPH05151599A - Optical head device - Google Patents

Abstract

PURPOSE:To prevent the intrinsic resonance of a movable member by balancing left and right inertial moments centering the hinge. CONSTITUTION:A supporting section 3 is joined to a galvanomirror base 2 fixed on a chassis base 1. A case 6 supporting an elastic and thin hinge 4 and a mirror 5 is extended to left and right centering the hinge 4 thereon. A driving coil 7 is wound the inside of the left and right hinges. The mirror 5 is joined to one end of the outside of the case 6 and a balancer 8 is joined to the other end. The mirror 5 is rotatable centering the hinge 4 by the electromagnetic force of the driving coil 7. By receiving tracking error signals, a current flows through the coil and the galvanomirror 5 performs a prescribed up and down motion. Since the mirror 5 and the balancer 8 are mechanically balanced centering the thin hinge 4, the device is affected too little by gravity and external impact, and the intrinsic resonance of the movable part is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a galvanometer mirror mechanism used in an optical disk recording / reproducing apparatus for recording information on a rotating flat disk or reproducing already recorded information.

[0002]

2. Description of the Related Art As a device for optically recording information on a concentric or spiral track formed on a rotating disk, or for optically reading and reproducing already recorded information, Devices such as compact discs and optical video discs that record in the form of pits, irradiate a light beam on this, and reproduce by utilizing the interference of light, or magneto-optical discs that record and reproduce by utilizing the magneto-optical effect, It has already been put to practical use.

An optical disk device as a data storage device is required to have a high-speed access, and in order to realize this, a heavy type optical system is fixed to a chassis base and a movable part at the time of access is a lens actuator only. Optical heads have been proposed. In the optical head of this configuration, the lens actuator uses only one axis for focus operation to reduce the weight of the movable part, and for tracking, the mirror surface of the galvano mirror fixed to the chassis base is tilted to make the incident angle to the light beam to the objective lens. The reading and focusing light is given and moved. 5 is a top view of the galvanometer mirror, FIG. 6 is a side view, and FIG. 7 is an operation explanatory view. 8 is an overall view of the apparatus, FIG. 9 is a view showing a traveling state of light, and FIG. 10 is an enlarged view of a portion A of FIG.

An example of an optical disk device using a conventional galvano mirror is shown in FIGS. When reading the data of the recording medium 10, the reading light 12 must be scanned to follow the eccentricity of the track 11, but the operation is performed by the galvanometer mirror 13 located in the optical path of the parallel light 15 incident on the objective lens 14. By changing the incident angle, the position of the reading light 12 on the recording medium 10 is moved as shown in FIG.

As shown in FIGS. 5 to 7, the galvano mirror has a supporting portion 52 joined to a galvano mirror base 51 fixed to the chassis base 1 of the apparatus, and an end portion thereof is a thin hinge 53 made of an elastic body. Further, a housing 54 that supports the mirror 5 is joined to the tip portion thereof. This case 5
A drive coil 55 is wound around the hollow portion of the magnetic disk 4 and is arranged so as to be rotatable around the hinge 53 while maintaining a clearance in the bias magnetic field of the magnetic circuit 56 fixed to the galvano mirror base 51. , Are driven by electromagnetic action with the magnetic circuit 56. As an operation, an arbitrary current is passed through the drive coil 55, and the magnetic action with the magnetic circuit 56 causes the mirror 5 to move vertically as shown in FIG. As the movement of the entire apparatus, the laser light 12 from the fixed optical element means 16 is reflected by the mirror 5, and the reflected light is moved to the actuator 17 to which the objective lens 14 is attached.
Then, the light is refracted in the direction of the objective lens by the rising mirror and is irradiated onto the recording medium 10. At this time, the objective lens 1
The movement of 4 in the focus direction is performed by the actuator 17, and the adjustment of the track direction is performed by the vertical movement of the galvanometer mirror. That is, as shown in FIGS. 9 and 10, when the track 11 is eccentric, a tracking error signal is supplied to the drive coil 55 of the galvanometer mirror 13, the mirror 5 moves up and down, and the traveling direction of the reflected light is shifted. Then, the reflection position on the raising mirror changes, the irradiation position of the parallel light 15 on the objective lens 14 shifts, and the irradiation position on the recording medium 10 finally changes. Thus, conventionally, tracking adjustment has been performed.

[0006]

As described above, in the conventional galvanometer mirror, the mirror, the drive coil and the like are arranged in the same direction with respect to the center of rotation (hinge) in the housing in which the mirror is supported. Therefore, the neutral position of the mirror is disturbed due to gravity, external impact, or the like that acts on the mass of the mirror, the drive coil, and the like.

[0007]

In order to solve the above problems, in the present invention, a galvanometer mirror is supported by an elastic body so as to be capable of minute rotation, a drive coil is provided on both sides of the center of rotation, and a mirror is provided outside thereof. Provided is a galvanometer mirror mechanism, which has a casing rotatably arranged together with a drive coil while supporting it, and has a moment of inertia balanced with respect to a rotation center.

[0008]

Since the inertial moments on the mirror side and the opposite side are balanced with respect to the center of rotation, the influence of gravity on the movable mass and other external impacts is small.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to FIGS. First, FIG. 1 is a plan perspective view showing the structure of the galvano mirror of the present invention, and FIG. 2 is a front view thereof.
FIG. 3 is a plan view showing the overall structure of a separation type optical head adopting the galvano mirror of the present invention, and FIG. 4 is a plan view of the same, and an enlarged view showing the movement of the reading spot on the recording medium. As shown in FIGS. 1 and 2, a supporting portion 3 is joined to a galvano mirror base 2 fixed to a chassis base 1 of the apparatus, and a thin hinge portion 4 of an elastic portion is formed on the upper portion of the supporting portion. A housing 6 supporting the mirror 5 extends to the left and right around the hinge portion 4 like an arm on the upper part thereof. A drive coil 7 is wound inside the housing 6 on both sides of the hinge 4, a mirror 5 is joined to one end on the outside, and a balancer 8 is joined to the opposite end. The magnetic circuit 9 fixed to the galvano mirror base 2 and the drive coil 7 electromagnetically actuate the mirror 5 to rotate about the hinge 4. The overall movement is basically the same as the operation of the prior art, so details thereof will be omitted. However, the movement of the galvanometer mirror receives a tracking error signal, and the signal causes a current to flow in the drive coil 7, causing a predetermined vertical movement. Move. At this time, the mirror 5 and the balancer 8 are mechanically balanced with each other around the thin hinge portion 7, so that the mirror 5 and the balancer 8 are less affected by gravity or an external impact.

[0010]

According to the above invention, the left and right moments of inertia are balanced around the hinge, which is the center of rotation of the movable portion, so that the posture of the mirror will be affected by gravity or other external impacts. Less likely to be disturbed.
Further, since the driving force is balanced with respect to the center of rotation, the natural resonance of the movable part including the hinge is less likely to occur.

[Brief description of drawings]

FIG. 1 is a plan perspective view of an embodiment of a galvanometer mirror of the present invention.

FIG. 2 is a front view of FIG.

FIG. 3 is a plan view showing the overall configuration of a separation type optical head that employs the galvano mirror shown in FIG.

FIG. 4 is a front view of FIG. 3 and an enlarged view showing a tracking operation.

FIG. 5 is a plan view showing a conventional galvanometer mirror.

6 is a front perspective view of FIG.

FIG. 7 is a front view showing the operation of the galvanometer mirror shown in FIG.

8 is a plan view showing the overall configuration of a separation type optical head that employs the galvano mirror of FIG.

9 is a front view of FIG. 8 and an enlarged view showing a tracking operation.

10 is an enlarged view of a main part of FIG.

[Explanation of symbols]

 1 Chassis Base 2 Galvano Mirror Means (Galvano Mirror Base) 3 Galvano Mirror Means (Support) 4 Galvano Mirror Means (Hinge) 5 Galvano Mirror Means (Mirror) 6 Galvano Mirror Means (Case) 7 Galvano Mirror Means) Drive Coil ) 8 galvano mirror means (balancer) 9 galvano mirror means (magnetic circuit) 10 recording medium 11 track 12 read light 13 galvano mirror means (galvano mirror) 14 objective lens 15 parallel light 16 fixed optical element means 17 actuator movable part (actuator 51) Galvano mirror base 52 Support portion 53 Hinge 54 Housing 55 Drive coil 56 Magnetic circuit

Claims (1)

[Claims] 1. An objective lens, an actuator moving part provided with this objective lens so that it can be finely moved in one axis direction, fixed optical element means for irradiating or not irradiating a light beam to this objective lens, and this fixed optical element means. In the optical head device, which is located between the objective lens and the objective lens and reflects the light beam in the direction of the objective lens or in the direction of the fixed optical element means and which can be moved minutely, the galvano mirror means moves minutely. An optical head device characterized in that the center of movement is located near the balancing center of this means.