JP3114348B2 - Precision angular displacement mechanism - Google Patents

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 for an optical recording / reproducing apparatus (hereinafter referred to as a galvano actuator).

[0002]

2. Description of the Related Art In a conventional galvano actuator, an adhesive is used for fixing a coil to a holding member constituting a movable portion, but no special consideration is given.

[0003]

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

[0004]

In order to solve the above-mentioned problems, a precision angle displacement mechanism of the present invention reflects a laser beam in a precision angle displacement mechanism for performing tracking of an optical recording / reproducing apparatus having a separation optical system. A reflecting mirror, a substantially rectangular parallelepiped holding member having a concave cross section as viewed in the longitudinal direction of the rectangular parallelepiped, an integrated component including a support member and a terminal integrated via a hinge, a coil, And a magnet positioned through a gap in the coil, wherein the terminal of the integrated component is mounted inside the recess so that the hinge portion fits inside the recess, and a longitudinal end of the holding member is provided. The reflecting mirror is attached to the portion, the coil is attached to both sides of the holding member, a damping material is interposed between the holding member and the coil, and the light beam incident parallel to the rotation axis of the reflecting mirror is orthogonally oriented. It characterized in that for reflecting.

Further, the damping material is a sheet-like adhesive containing a viscoelastic material.

[0006]

[0007]

[0008]

【Example】

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

FIG. 1 is a perspective view showing a main configuration of an optical recording / reproducing apparatus using a galvano actuator according to the present invention.
FIG. 2 is a perspective view showing a main configuration of a galvano actuator according to one embodiment of the present invention, FIG. 3 is a front view of a movable portion 50 of the galvano actuator according to one embodiment of the present invention, and FIG. FIG. 5 is an enlarged view of a section A in FIG. 4.

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

The optical recording / reproducing apparatus generally comprises a movable 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) for moving the moving optical system 70 in the radial direction of the recording medium 60. I have. The fixed optical system 80 includes the recording medium 60.
, A light source 81 composed 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 to be 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 as shown by a solid line in FIG.
Then, the light beam reflected by the flip-up prism 71 is condensed through the objective lens 72 and forms a spot P62 on the recording medium 60, thereby recording and reproducing 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 and reproducing information. The movable optical system 70 has a relatively large mass and a frictional resistance, so the response frequency band is narrow, but the movable distance is large. Reflector 1
1. Since the movable portion 50 including the holding member 12 and the coil 13 has a small mass and inertia moment and no frictional resistance, it 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, and the spot P62 is largely moved to the position of the desired spot Q61. When the moving amount 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 displaced minutely as shown by a dotted line in FIG. Is tracked so as to form the spot Q61. As a control method, according to a target track position command, first, 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.
61 is formed. That is, a two-stage servo control method is employed in which control is performed by a large displacement by the moving optical system 70 and a small displacement by the galvano actuator 10.

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

A holding member 12 for holding the reflecting mirror 11 and a coil 1 connected to both sides of the holding member 12 with an adhesive 19
3 constitutes the movable part 50. The yokes 14 are arranged outside the movable portion 50, and two magnets 15 are fixed to the yokes 14 with a gap from the coil 13. Therefore, since the yoke 14 and the magnet 15 form a closed magnetic circuit, when a current flows through the coil 13, a magnetomotive force is generated in each coil. The coils are connected so that the directions of the magnetomotive forces are opposite to each other, and the magnetomotive force acts as a torque around the holding member 12. The holding member 12 has a concave cross section, and is fixed to the terminal 16 inside the concave portion. The terminal 16, the support member 17, and the hinge 18 are integrated parts, and the terminal 16 is rotatable about the hinge 18. Therefore, coil 1
3, the movable part 50 is moved by an arrow b in FIG.
Rotate in the direction.

Next, the fixing 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 by a sheet-like adhesive 19 containing a viscoelastic material. The sheet-like adhesive 19 containing a viscoelastic material is an acrylic polymer material having both viscosity and elasticity,
Moreover, it is a sheet-like double-sided adhesive having a self-adhesive action. Therefore, when the galvano actuator is driven by using the sheet-like adhesive 19 containing a viscoelastic material in fixing the holding member 12 and the coil 13, the resonance of the coil 13 is suppressed as a damping material, There is an effect that 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 a frequency characteristic diagram of the vibration amplitude of the conventional galvano actuator, and FIG. 9 shows a frequency characteristic diagram of the vibration amplitude of the galvano actuator according to the present embodiment.

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

In the frequency characteristic diagram of FIG. 12, resonances appear at around 100 Hz, around 1000 Hz, and around 40000 Hz. When the galvano actuator is servo-controlled, the resonance around 100 Hz is the primary resonance point of this system and can be corrected by the control circuit.
Since the servo system becomes unstable at the resonance point at resonance from around 00 Hz to around 30000 Hz, servo control becomes impossible.

However, in the frequency characteristic diagram of the present embodiment shown in FIG. 9, the harmful resonance amplitude is greatly suppressed as compared with the conventional frequency characteristic diagram shown in FIG. That is, the amplitude of each resonance is suppressed and reduced, and
The resonance point near 0 Hz has disappeared. Also, 40000
With respect to the resonance point near Hz, the necessary frequency band of the galvano actuator in this embodiment is about 3500 Hz.
Since it is generally known that up to about 10 times the band is affected by resonance, there is no particular problem since the resonance point is 35000 Hz or more.

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

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

Therefore, when the adhesive 19 containing synthetic rubber is used for fixing the holding member 12 and the coil 13, there is an effect of suppressing the resonance of the coil 13 as a damping material.

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

( Comparative Example ) FIG. 6 is a perspective view showing a main configuration of a galvano actuator according to a comparative example of the present invention, FIG. 7 is a front view of a movable portion of the galvano actuator according to the comparative example , and FIG. Qq
FIG.

On both sides of the holding member 12, the holding members 12
And a rib 21 integrated therewith. Since the rib 21 is located at a position where it engages with the coil 13, the coil 13 is positioned and fixed to the rib 21. Further, since the holding member 12 has a concave cross section, 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 comparative example . In the frequency characteristic of FIG. 10, the frequency of the resonance point in the high frequency band around 40,000 Hz moves to a higher frequency side. That is, when the galvano actuator is driven by forming the rib 21 on the holding member 12,
This has the effect of shifting the higher order resonance frequency to a higher frequency.

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, the positioning of the coil 13 is facilitated and the position of the coil 13 after bonding is accurately maintained. That is, the accuracy of the coil bonding position and the assembling work can be simplified.

(Embodiment 2 ) This embodiment is a combination of Embodiment 1 and a comparative example . That is, in the first embodiment, the holding member 1
The resonance can be suppressed by interposing a damping material between the coil 2 and the coil 13, and furthermore, in the comparative example , the ribs are formed on both side surfaces of the holding member to hold the coil. At the same time as increasing the rigidity of the member, the resonance frequency in the high frequency band can be increased.

FIG. 11 shows a frequency characteristic diagram of the vibration amplitude of the galvano actuator of this embodiment. As shown in FIG.
This embodiment can provide an effect combining characteristics of the first embodiment and the comparative example .

[0034]

As described above, in the galvano actuator, the holding member is provided with the concave portion, and the hinge portion is accommodated inside the concave portion so that the light is reflected on the center axis (hinge portion) of the rotating reflecting mirror. The resonance can be effectively suppressed by setting the center of gravity of the mirror substantially at the position. Further, since the resonance can be suppressed by interposing and fixing the damping material between the holding member and the coil, the problem 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 driven stably in a wide frequency band.

[0036]

[0037]

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing a main configuration of a galvano actuator of 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 in FIG. 3 of the present invention.

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

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

7 is a front view of a movable portion of the galvano actuator in FIG. 6 of a comparative example .

FIG. 8 is a sectional view taken along line qq in FIG. 7 of a comparative example .

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

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

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

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

[Explanation of symbols]

Reference Signs List 10 Precision angular displacement mechanism (galvano actuator) 11 Reflecting mirror 12 Holding member 13 Coil 14 Yoke 15 Magnet 16 Terminal 17 Support member 18 Hinge part 19 Adhesive 21 Rib 50 Movable part 60 Recording medium 61 Spot Q 62 Spot P 63 Track 70 Move Optical system 71 Jump-up prism

Continuation of the front page (56) References JP-A-3-214430 (JP, A) JP-A-2-244427 (JP, A) JP-A-3-292643 (JP, A) JP-A-57-33434 (JP, A) , U) Actually open 58-148733 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/09 G11B 7/095 G02B 26/10 104

Claims (2)

(57) [Claims] 1. A precision angular displacement mechanism for tracking an optical recording / reproducing apparatus having a separation optical system, comprising: a reflecting mirror for reflecting a laser beam; and a substantially rectangular parallelepiped having a cross section viewed from the longitudinal direction of the rectangular parallelepiped having a concave shape. And a coil, and a magnet positioned via a gap in the coil, wherein the hinge portion is the concave portion. Attaching the terminal of the integrated component to the inside of the concave portion so as to fit inside the concave portion, attaching the reflecting mirror to a longitudinal end of the holding member, attaching the coil to both sides of the holding member, A precise angular displacement mechanism, wherein a damping material is interposed between a member and the coil, and a light beam incident parallel to a rotation axis of the reflecting mirror is reflected in a direction perpendicular to the member. 2. The precision angular displacement mechanism according to claim 1, wherein the damping material is a sheet-like adhesive containing a viscoelastic material.