JPH04281229A - Optical system driving device - Google Patents

Abstract

PURPOSE:To reduce the weight of a movable member having an optical system and to improve the responsiveness. CONSTITUTION:Elastic members 15 having an attenuating property are adhered to the inside surfaces of through-holes 2a for passing magnetic yokes which are formed in a holder 2 having an objective lens 1 and focusing coils 12 and are not shown in Fig. Further, reinforcing members 16 shaped to comply with the inside surfaces are adhered to the inner side thereof, by which the strength of the holder 2 is increased and side resonance amplitude is decreased.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system driving device for driving optical system members such as an objective lens for optical information recording and reproduction.

0002

2. Description of the Related Art FIG. 5 shows a conventional optical system driving device for an information recording/reproducing apparatus, in which an objective lens 1 is held in a holder 2,
The holder 2 is supported by a carriage 5 via a parallel leaf spring 3 and a relay member 4 so as to be movable up and down. Hollow tracking coils 6, 6 are attached to both sides of the carriage 5, inner yokes 7, 7 are inserted through the tracking coils 6, 6 and through holes in the holder 2, respectively, and a U-shaped outer yoke 8 is inserted. , 8 are connected to both ends of the inner yokes 7, 7 to form a magnetic circuit with permanent magnets 9, 9 fixed inside the outer yokes 8, 8. The carriage 5 is movably supported by a mechanism not shown in the seek direction parallel to the inner yokes 7 , 7 , and a mirror 11 is attached to the carriage 5 directly below the objective lens 1 via a mounting member 10 .
Two focus coils 12, 12 are fixed to the left and right side surfaces of the camera, arranged vertically.

The carriage 5 is driven in the tracking direction by the current flowing through the tracking coils 6, 6, and the objective lens 1 is driven up and down via the holder 2 by the current flowing through the focusing coils 12, 12, thereby driving the fixed head (not shown). Laser light that enters the mirror 11 in parallel to the tracking direction is focused on a recording medium (not shown), and the reflected light is returned in the opposite direction along the same optical path.

0004

[Problems to be Solved by the Invention] However, in the conventional example described above, the width of the holder 2 is wide, and when the holder 2 is driven in the focusing direction, the holder 2 is deformed and distorted as shown in FIG. As shown in FIG. 7, the sub-resonance peak appears high at low frequencies, which has a large adverse effect on electrical servo control. In order to attenuate this sub-resonant peak,
Adhesive material 13 and plate-shaped weight member 14 as shown in FIG.
A method is known in which a damping member made of the above is bonded to the outer circumference of the holder 2, but there are problems such as difficulty in balancing the center of gravity or a decrease in responsiveness due to increased weight.

The object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide an optical system driving device that improves the deterioration of frequency characteristics due to insufficient strength, has good responsiveness, and is small and lightweight.

[0006]

[Means for Solving the Problems] An optical system driving device according to the present invention for achieving the above object includes a movable member including an optical system and a driving coil for the optical system, and a movable member that includes an optical system and a driving coil for the optical system. In an optical system drive device having a permanent magnet and a yoke that work together, an elastic member having damping performance is attached to the inner wall of the movable member, and a reinforcing member having substantially the same shape is attached to the elastic member, and the yoke is fixed to the inner wall of the movable member. and the movable member.

[0007]

[Operation] In the optical system drive device having the above configuration, the peak of sub-resonance caused by the deformation of the movable member is suppressed, the movable member and the reinforcing member mutually increase their strength, the structure itself is strengthened, and the weight can be reduced. .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail based on the embodiments shown in FIGS. 1 to 4.

FIG. 1 shows an exploded perspective view of an optical system driving device corresponding to FIG. 5, and the configuration of the objective lens 1 to the mirror 11 is the same as that in FIG. In the two through holes 2a of the holder 2,
As shown in FIG. 2, an elastic member 15 having damping properties on its inner surface
is attached by a method such as adhesive, and a frame-shaped reinforcing member 16 is further fixed to the inner surface of the elastic member 15 by a method such as adhesive. This reinforcing member 16 is made of a highly rigid material such as a metal such as aluminum, a synthetic resin reinforced with carbon fiber or glass fiber, or ceramics, and is a sandwich sandwich with the elastic member 15 sandwiched between it and the inner wall of the through hole 2a. It has a structure.

A fixed optical head (not shown) is arranged further behind the mirror 11, and a laser beam is emitted in a tracking direction parallel to the inner yoke 7, reflected upward by the mirror 11, and passed through the objective lens 1 (not shown). The light is focused on the recording medium, and the reflected light travels the same optical path in the opposite direction toward a fixed optical head. At this time, the carriage 5 is driven in the front-back direction by the electromagnetic force that the current flowing through the tracking coil 6 receives from the magnetic field of the gap from the inner yoke 7 to the permanent magnet 9, and tracking is performed.Similarly, the focus coil 1
The holder 2 is moved in the vertical direction by the current flowing through the holder 2,
Focusing is performed by changing the position of the objective lens 1.

FIG. 3 shows an exploded perspective view of the second embodiment,
A movable member 24 is supported by a support shaft 22 provided on the carriage 21 and having a center line in the vertical direction via a bearing 23 so as to be slidable up and down and rotatable left and right. Movable member 2
Reference numeral 4 has a substantially short cylindrical shape and is bilaterally symmetrical, and an objective lens 25 is fixed to a through hole facing in the vertical direction of the bearing 23, and a balance weight 26 is fixed at a position symmetrical to the objective lens 23 with respect to the bearing 23. Semicircular through holes 24a are formed on the left and right sides. A focus coil 27 is wound around the outer periphery of the movable member 24, and one focus coil 27 is wound around the outer periphery of the movable member 24, and one focus coil 27 is wound around the outer periphery of the movable member 24.
A total of four tracking coils 28 are fixed. An elastic member 29 having damping properties is provided on the inner wall of the through hole 24a.
is bonded to the reinforcing member 30, and a reinforcing member 30 is further bonded to the inner side of the reinforcing member 30, both of which are formed in layers along the inner wall of the through hole 24a.

On the carriage 21, there is an inner yoke 31 that stands vertically and enters the through hole 24a of the movable member 24;
L-shaped outer yoke 3 whose one end touches the lower part of the inner yoke 31
2 and a permanent magnet 33 fixed inside the vertical portion of the outer yoke 32 and extending along the circumference of the movable member 24. A magnetic circuit is attached symmetrically with respect to the support shaft 22 on the left and right sides. Further, a through hole 21a is provided near the support shaft 22, and a light beam bent by a reflection mirror (not shown) is emitted upward through the through hole 21b on the right side of the carriage 21. The objective lens 25 is positioned directly above the through hole 21a, the inner yoke 31 is inserted through the through hole 24a, and the focus coil 27 and tracking coil 28 are positioned between the inner yoke 31 and the permanent magnet 33. Further, the coils 27 and 28 on the movable member 24 are connected to each other via four lands of the relay board 34 provided on the side surface of the movable member 24.
The four conductive wires 35 are connected to lands on a flexible substrate 36 fixed to the carriage 21.

The laser light incident from the through hole 21b of the carriage 21 is deflected by a reflection mirror (not shown) and focused on a recording medium (not shown) via the objective lens 25, so that the reflected light from the recording medium follows the same optical path. Go back the other way. At this time, a current is applied to the focusing coil 27 to adjust the vertical position of the movable member 24 to perform focusing, and a current is applied to the tracking coil 28 to rotate the movable member 24 around the support shaft 22, thereby causing the objective lens to rotate. Tracking is performed by adjusting the left and right positions of 25.

In any of the above-described embodiments, the movable member on which the objective lens is mounted is reinforced by a reinforcing member and an elastic member, so that deformation does not easily occur, and as shown by the solid line in FIG.
The sub-resonance peak is lower than that of the conventional example shown by the broken line.

In the embodiment, the elastic members 15 and 29 that overlap the reinforcing members 16 and 30 may be a viscoelastic member, a combination of an elastic member and a viscoelastic member, or a composite material, as long as it has vibration damping properties. It may also be something that has been used. Further, the elastic member and the reinforcing member do not need to be attached to the entire surface of the inner wall of the movable member, but may be attached along the shape of the inner wall. In addition, in the embodiment, the laser light source etc. are connected to the objective lens 1.
, 25 is used, but the invention is not limited to this, and a method in which a semiconductor laser light source or the like is mounted on a movable member may be used.

[0016]

As explained above, in the optical system drive device according to the present invention, by stacking the reinforcing member on the elastic member and attaching it to the movable member, the strength of the movable member increases compared to its weight, and at the same time Since the resonance peak is reduced, the response is good and at the same time it is lightweight.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a first embodiment.

FIG. 2 is an exploded perspective view of main parts.

FIG. 3 is an exploded perspective view of the second embodiment.

FIG. 4 is an explanatory diagram of frequency characteristics.

FIG. 5 is an exploded perspective view of a conventional example.

FIG. 6 is an explanatory diagram of a modification of a conventional holder.

FIG. 7 is an explanatory diagram of frequency characteristics of a conventional example.

FIG. 8 is a perspective view of main components of a conventional example.

[Explanation of symbols]

1, 25 Objective lens 2 Holder 2a, 24a Through hole 5, 21 Carriage 7, 31 inner yoke 12, 27 Focus coil 15, 29 Elastic member 16, 30 Reinforcement member 22 Support shaft 24 Movable member 28 Tracking coil

Claims (1)

[Claims] 1. An optical system driving device comprising: an optical system; a movable member having a driving coil for the optical system; a permanent magnet and a yoke that cooperate with the driving coil; An optical system driving device characterized in that an elastic member having damping performance is attached, and a reinforcing member having substantially the same shape is attached to the elastic member, and the reinforcing member is interposed between the yoke and the movable member.