JPH05314517A - Mechanism for displacing precision angle - Google Patents

Abstract

PURPOSE:To realize stable drive in a broad frequency band by interposing a dumping material between a holding member and a coil and sticking it and suppressing resonance. CONSTITUTION:A movable part 50 is constituted of the holding member 12 holding a reflection mirror 11 and the coil 13 attached to both side of the member 12 by an adhesive material 19 containing a viscoelastic material. A yoke 14 is arranged on the outside of the movable part 50 and two magnets 15 each are stuck to the yoke 14 having a gap with the coil 13. Thus, a magnetic circuit is formed by the yoke 14 and the magnets 15 and when current flows through the coil 13, electromotive force is generated in the coil. By wiring so that the direction of the electromotive force are opposite each other, the elctromotive force acts as torque around the member 12. The cross section of the member 12 is a recessed part shape and the member 12 is stuck with a terminal 16. The terminal 16, a supporting member 17 and a hinge part 18 are formed integrally and the terminal 16 is made rotatable around the hinge part 18. Thus, when the current flows through the coil 13, the movable part 50 is rotated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision angular displacement mechanism (hereinafter referred to as a galvano actuator) for an optical recording / reproducing apparatus.

[0002]

2. Description of the Related Art In a conventional galvanometer actuator, an adhesive is used to fix a holding member and a coil that form a movable portion, but no special consideration is given.

[0003]

In the prior art, when a galvanometer actuator is driven, resonance occurs due to the coil. There is a problem that the servo system becomes unstable at the resonance point when the galvano actuator is servo-controlled. Therefore, the present invention solves such a problem and provides a galvanometer actuator which is stably driven in a wide frequency band by suppressing the harmful resonance point.

[0004]

The structure of the present invention for solving the above-mentioned problems is (1) in a galvanometer actuator,
A reflecting mirror that reflects the laser light; a holding member that holds the reflecting mirror; coils that are fixed to both sides of the holding member; magnets that have a gap in the coil and a yoke; A damping material is interposed between the holding member and the coil.

(2) The damping material is a sheet-shaped adhesive containing a viscoelastic material.

(3) In (1), the damping material is an adhesive containing synthetic rubber.

(4) In the galvano actuator,
A reflecting mirror that reflects the laser light; a holding member that holds the reflecting mirror; coils that are fixed to both sides of the holding member; magnets that have a gap in the coil and a yoke; It is characterized in that ribs are formed on both side surfaces of the holding member.

[0008]

【Example】

(Embodiment 1) Hereinafter, the configuration of the galvano actuator of the present invention will be described in detail based on the embodiments shown in the drawings.

FIG. 1 is a perspective view showing the main configuration of an optical recording / reproducing apparatus using a galvano actuator according to the present invention,
2 is a perspective view showing the main configuration of a galvano actuator according to an embodiment of the present invention, FIG. 3 is a front view of a movable portion 50 of the galvano actuator according to an embodiment of the present invention, and FIG. p sectional view, FIG. 5 shows an enlarged view of a portion A of FIG.

First, the structure of the optical recording / reproducing apparatus will be described.

The optical recording / reproducing apparatus generally comprises a moving optical system 70 movable in the radial direction of the medium 60 and a fixed optical system 80 including a light source 81. The moving optical system 70 includes a flip-up prism 71, an objective lens 72, an objective lens actuator (not shown), and a voice coil motor (not shown) that moves the moving optical system 70 in the radial direction of the recording medium 60. There is. The fixed optical system 80 is the recording medium 60.
Is fixed at a fixed position with respect to a light source 81 made of a semiconductor laser or the like, and a spot position signal / optical signal detection unit 82.
And a reflecting mirror 11 and actuator means (described later) for angularly displacing the reflecting mirror 11.

Next, the operation and tracking of the optical recording / reproducing apparatus will be described.

The light beam L88 emitted from the light source 81 is reflected by the reflecting mirror 11 and is moved by the moving optical system 70 as shown by the solid line in FIG.
Then, the light flux reflected by the flip-up prism 71 passes through the objective lens 72 and is condensed to form a spot P62 on the recording medium 60 to record / reproduce information.

Since the recording medium 60 has a plurality of tracks 63, it is necessary to move the spot P62 to a desired position when recording / reproducing information. Since the moving optical system 70 has a relatively large mass and has frictional resistance, the frequency band in which it can respond is narrow, but the movable distance is large. Reflector 1
1. The movable portion 50 including the holding member 12, the coil 13 has a small mass and a small moment of inertia and has no frictional resistance, and thus has a wide response frequency band, but has a small movement amount. Therefore, where the required movement amount of the spot P62 is large, the moving optical system 70 is moved in the radial direction of the recording medium 60 to largely move the spot P62 to the position of the desired spot Q61. When the amount of movement is small, the reflecting mirror 11 is slightly displaced in the direction of arrow a in FIG. 1 by the operation of a galvano actuator described later, and the light beam M89 is slightly displaced as shown by the dotted line in FIG. Tracking is performed so as to form a spot Q61. As a control method, first, according to the command of the target track position, the reflecting mirror 11 is rotated to bring the spot closer to the target, and the angular displacement of the reflecting mirror 11 is detected by an angular displacement detecting means (not shown). The moving optical system 70 is moved to the vicinity of the desired track so that the displacement becomes zero, and for the final minute amount, the reflecting mirror 11 is angularly displaced to obtain the spot Q of the desired track.
61 is formed. That is, the two-stage servo control method is used in which the displacement is controlled by the large displacement by the moving optical system 70 and the minute displacement by the galvano actuator 10.

Next, the structure of the galvanometer actuator and the actuator means / operation will be described.

A holding member 12 for holding the reflecting mirror 11 and a coil 1 bonded to both sides of the holding member 12 with an adhesive 19.
The movable part 50 is composed of 3 and. The yoke 14 is arranged outside the movable portion 50, and two magnets 15 are fixed to the yoke 14 with a gap between the yoke 14 and the coil 13. Therefore, since the yoke 14 and the magnet 15 form a closed magnetic circuit, a magnetomotive force is generated in each coil when a current is applied to the coil 13. The coils are connected so that the directions of the magnetomotive forces are opposite to each other, and the magnetomotive forces act as a torque around the holding member 12. The holding member 12 has a recessed section, and is fixed to the terminal 16 inside the recessed section. The terminal 16, the support member 17, and the hinge portion 18 are an integral part, and the terminal 16 is rotatable around the hinge portion 18. Therefore, coil 1
When a current is passed through the movable part 50, the movable part 50 moves in the direction of arrow b in FIG.
Rotate in the direction.

Next, the fixation of the holding member 12 of the movable portion 50 and the coil 13 will be described.

The holding member 12 and the coil 13 are fixed to each other with a sheet-like adhesive 19 containing a viscoelastic material. The sheet-shaped adhesive 19 containing a viscoelastic material is an acrylic polymer material having both viscosity and elasticity,
Further, it is a sheet-shaped double-sided adhesive having a self-adhesive action. Therefore, when the holding member 12 and the coil 13 are fixed to each other, the sheet-shaped adhesive 19 containing a viscoelastic material is used to suppress resonance of the coil 13 as a damping material when the galvano actuator is driven, There is an effect that the resonance is not transmitted to the holding member 12 and the reflecting mirror 11.

Next, a frequency characteristic diagram of the vibration amplitude of the galvano actuator will be described.

FIG. 12 shows the frequency characteristic diagram of the vibration amplitude of the conventional galvano actuator, and FIG. 9 shows the frequency characteristic diagram of the vibration amplitude of the galvano actuator according to this embodiment.

In the graph of the frequency characteristic diagram, the horizontal axis represents the vibration frequency, and the vertical axis represents the ratio of the current input to the coil 13 and the rotation angle of the movable part 50 in decibels.

In the frequency characteristic diagram of FIG. 12, resonance appears near 100 Hz, around 1000 Hz and around 40,000 Hz. When the galvano actuator is servo-controlled, resonance near 100 Hz is the primary resonance point of this system and can be corrected by the control circuit, so no problem occurs.
Resonance from around 00 Hz to around 30,000 Hz makes the servo system unstable at the resonance point, making servo control impossible.

However, in the frequency characteristic diagram of the present embodiment of FIG. 9, the harmful amplitude of resonance is greatly suppressed as compared with the conventional frequency characteristic diagram of FIG. That is, the amplitude of each resonance is suppressed and reduced, and in particular, 100
The resonance point near 0 Hz has disappeared. Also, 40,000
Regarding the resonance point around Hz, the necessary frequency band of the galvano actuator in this embodiment is about 3500 Hz.
Since it is generally known that resonance is affected up to about 10 times the band, there is no particular problem because the resonance point is 35000 Hz or higher.

Therefore, according to this embodiment, the galvano actuator can have good frequency characteristics.

Next, the adhesive 19 used for fixing the holding member 12 and the coil 13 in this embodiment is an acrylic polymer material, but an adhesive containing synthetic rubber can also achieve the same effect. The adhesive containing synthetic rubber is an adhesive containing chloroprene synthetic rubber / phenolic resin as a main component, and has the property of not losing viscoelasticity even after adhesion.

Therefore, when the holding member 12 and the coil 13 are fixed to each other, the use of the adhesive 19 containing synthetic rubber has an effect of suppressing resonance of the coil 13 as a damping material.

Further, since the adhesive 19 containing synthetic rubber is a mucous liquid, it is characterized in that it can be easily fixed even if the adhesive surface is a complicated surface such as a curved surface.

(Embodiment 2) FIG. 6 is a perspective view showing the main structure of a galvano actuator which is another embodiment of the present invention.
FIG. 7 is a front view of a movable portion of the galvano actuator according to this embodiment, and FIG. 8 is a sectional view taken along the line qq of FIG.

On both sides of the holding member 12, the holding member 12 is provided.
A rib 21 is formed integrally with the rib 21. Since the rib 21 is in a position to engage with the coil 13, the coil 13 is positioned and fixed to the rib 21. Moreover, since the holding member 12 has a concave cross-sectional shape, the rigidity is low. Therefore, by forming the ribs 21 on both side surfaces of the holding member 12, the rigidity of the holding member 12 can be increased.

FIG. 10 shows a frequency characteristic diagram of the vibration amplitude of the galvano actuator of this embodiment. In the frequency characteristic of FIG. 10, the frequency at the resonance point in the high frequency band around 40,000 Hz is even higher. That is, forming the rib 21 on the holding member 12 has an effect of moving the higher resonance frequency to a higher frequency when the galvano actuator is driven.

The coils 13 are provided on both sides of the holding member 12.
By forming the ribs 21 so as to engage with the coil 13, positioning of the coil 13 becomes easy, and at the same time, the position of the coil 13 after being bonded is accurately held. That is, the accuracy of the coil bonding position and the assembling work can be simplified.

(Third Embodiment) This embodiment is a combination of the first embodiment and the second embodiment. That is, in Example 1, resonance can be suppressed by connecting the holding member 12 and the coil 13 with a damping material interposed therebetween, and further, in Example 2, ribs are provided on both side surfaces of the holding member. By forming it, the rigidity of the holding member can be increased and the resonance frequency in the high frequency band can be increased.

FIG. 11 is a frequency characteristic diagram of the vibration amplitude of the galvano actuator of this embodiment. As shown in Figure 11,
This embodiment can have the effect of combining the characteristics of the first and second embodiments.

[0034]

As described above, in the galvanoactuator, the damping can be interposed between the holding member and the coil to fix the resonance, so that the resonance can be suppressed, so that the servo control becomes unstable at the resonance point. Can be solved.

That is, by using the galvano actuator of the present invention, it is possible to realize an optical recording / reproducing apparatus which is stably driven in a wide frequency band.

Further, by forming ribs on both sides of the holding member, the rigidity of the holding member can be increased and the resonance frequency in the high frequency band can be increased, so that the frequency characteristic of the galvano actuator is further improved. be able to.

Further, the position of the coil becomes accurate when the coil is bonded, and it is possible to simplify the assembling work.

[Brief description of drawings]

FIG. 1 is a perspective view showing the main configuration of an optical recording / reproducing apparatus of the present invention.

FIG. 2 is a perspective view showing a main configuration of a galvano actuator according to the present invention.

FIG. 3 is a front view of a movable portion of the galvano actuator in FIG. 2 of the present invention.

FIG. 4 is a sectional view taken along the line pp of FIG. 3 of the present invention.

5 is an enlarged view of part A in FIG. 4 of the present invention.

FIG. 6 is a perspective view of a movable portion of a galvano actuator according to another embodiment of the present invention.

7 is a front view of a movable portion of the galvano actuator in FIG. 6 of the present invention.

8 is a sectional view taken along the line qq in FIG. 7 of the present invention.

FIG. 9 is a frequency characteristic diagram of vibration amplitude of the galvano actuator according to the first embodiment of the present invention.

FIG. 10 is a frequency characteristic diagram of vibration amplitude of the galvano actuator according to the second embodiment of the present invention.

FIG. 11 is a frequency characteristic diagram of vibration amplitude of the galvano actuator according to the third embodiment of the present invention.

FIG. 12 is a frequency characteristic diagram of vibration amplitude of a conventional galvano actuator.

[Explanation of symbols]

10 Precision Angle Displacement Mechanism (Galvano Actuator) 11 Reflector 12 Holding Member 13 Coil 14 Yoke 15 Magnet 16 Terminal 17 Supporting Member 18 Hinge Part 19 Adhesive 21 Rib 50 Movable Part 60 Recording Medium 61 Spot Q 62 Spot P 63 Track 70 Moving Optical system 71 Splashing prism 72 Objective lens 80 Fixed optical system 81 Light source 82 Detector 88 Light flux L 89 Light flux M

Claims (4)

[Claims] 1. A precision angle displacement mechanism for tracking an optical recording / reproducing apparatus having a separation type optical system, a reflecting mirror for reflecting a laser beam, a holding member for holding the reflecting mirror, and both sides of the holding member. A precision angle displacement mechanism comprising a coil to be fixed, a magnet and a yoke positioned with a gap in the coil, and a damping material interposed between the holding member and the coil. 2. The precision angle displacement mechanism according to claim 1, wherein the damping material according to claim 1 is a sheet-shaped adhesive containing a viscoelastic material. 3. The precision angle displacement mechanism according to claim 1, wherein the damping material according to claim 1 is an adhesive containing synthetic rubber. 4. A precision angular displacement mechanism for tracking an optical recording / reproducing apparatus having a separation type optical system, a reflecting mirror for reflecting a laser beam, a holding member for holding the reflecting mirror, and both sides of the holding member. A precision angular displacement mechanism comprising: a coil to be fixed, a magnet and a yoke positioned with a gap in the coil, and ribs formed on both side surfaces of the holding member.