JPH06314433A - Optical system supporting device - Google Patents

Abstract

PURPOSE:To reduce the size and thickness of the optical system supporting device by providing the flank of an optical element holding member with a notch opening and longitudinally shifting at least one of the supporting members on a light incident side among plural supporting members at the time of constituting the optical system supporting device of the optical element holding member, the plural supporting members freely displaceable in required directions and driving members to be displaced. CONSTITUTION:The holding member 2 is supported by means of springs 3a to 3d in such a manner that the member is freely displaceable in the direction Z and the direction X at the time of holding an objective lens 1 by the holding member. The member 2 is provided with projecting parts 2b on both flanks thereof, i.e., in the direction X where the metallic wire-shaped springs 3a to 3d for the supporting member 2 are previously mounted. Their one-side ends are fixed to a fixing member 5 and the outer peripheries of the springs 3a to 3d are provided with rubber dampers 4. A focusing coil 6 and a tracking coil 7 are mounted on the flank of the member 2, i.e., in the direction Y, and a magnet 9 is fixed to the inside surface of an outside yoke 8a thereof. The notch opening 2d is formed on the flank of the member 2 and the springs 3c, 3d are mounted therein while the springs are longitudinally shifted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system supporting device for supporting an objective lens for projecting a light spot on the surface of an information recording medium in an optical information recording / reproducing device such as an optical disk.

[0002]

2. Description of the Related Art Conventionally, in an optical pickup,
Miniaturization and thinning are required. This is because it is essential to reduce the thickness of the entire optical disc device. For this reason, in the conventional optical pickup, a mirror is installed under the objective lens with an inclination of 45 degrees, the optical path is bent at a right angle, and the light emitting element and the light receiving element are arranged side by side so as to be thinned. However, in this case, the thickness of the optical pickup is defined by the size of the height of the objective lens driving device plus the height of the mirror, and further reduction in thickness is impossible.

Therefore, the present applicant has filed Japanese Patent Application Laid-Open No. 2-22652.
Japanese Patent Laid-Open No. 3 proposes an optical system supporting device as shown in FIGS. In the figure, reference numeral 1 is an objective lens, 2 is a holding member that holds the lens 1, and 3a to d are the holding members 2 described above.
This is a spring that supports the lens so that it can be displaced in the focus and tracking directions. That is, in the apparatus shown in the figure, the recess 2c is formed on the bottom surface of the holding member 2 to avoid interference with the mirror 10, while the side surface of the holding member 2 is provided with a cutout opening 2d for passing a light beam. Therefore, the overall thickness of the optical system supporting device is reduced.

However, even if the notch opening 2d is provided on the side surface of the holding member 2, the spring 3d for supporting the holding member 2 may block the light flux. This is because the effective length of the springs 3a to 3d is required to be about 10 mm in order to constantly move the objective lens 1 up and down in a stable manner by following the shake and tilt of the optical disk surface. This is because the external dimensions of the device are also restricted due to the above problem. Therefore, the distance between the springs 3b and 3d on the incident light beam side is set to be smaller than the distance between the springs 3a and 3c. Therefore, in the publication, even if the holding member 2 is displaced in a predetermined direction, the optical axis of the objective lens is tilted. Spring 3 to avoid
The mounting position of each spring is determined so that the sum of the moments of the forces a to d becomes zero.

[0005]

However, the above-mentioned conventional device has the following problems. When the support member on the incident side and the support member on the opposite side are provided asymmetrically, the support member cannot be stably supported unless the support member is arranged so that the sum of moments becomes zero as described above.
Therefore, at least one of the support members on the incident side is arranged below the center of gravity of the movable portion. Further, there is a restriction on the arrangement of the incident optical path in order to avoid the interference with the supporting member, which hinders the thinning of the entire apparatus.

Even under the above conditions, if the spring constant of each support member is changed, it is possible to arrange the support member on the incident light beam side only above the center of gravity of the movable portion. However, this is not preferable because the supporting member has to be composed of separate parts, resulting in an increase in cost and a complicated assembly process. For the above reasons, the conventional optical system supporting device cannot be made sufficiently thin.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical system supporting device capable of achieving a sufficiently small size and a thin structure while having the same cost and the same number of assembling steps as the conventional one. I am trying.

[0008]

In order to achieve the above object, in an optical system supporting device of the present invention, a holding member for holding an optical element and a plurality of supporting members for movably supporting the holding member in a required direction. And a drive means for displacing the holding member, wherein a notch opening is formed in a side surface of the holding member, and at least one of the plurality of supporting members on the incident light side is also supported. It was decided to attach them by shifting them in the longitudinal direction of the member.

[0009]

In the optical system supporting apparatus of the present invention having the above structure, the holding member horizontally holds the optical element near the optical disk surface. The plurality of support members support the holding member such that the holding member can be displaced vertically and always maintain a stable horizontal state. The driving means drives the holding member to move up and down (focusing direction) and left and right (tracking direction).

A notch opening is formed on the side surface of the holding member to prevent the incident optical path from being obstructed. Further, the support member on the incident light side is attached while being shifted in the longitudinal direction to prevent the incident light path from being obstructed.

Embodiments of an optical system supporting device according to the present invention will be described below with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

[0012]

First Embodiment First, a first embodiment of the present invention will be described. Figure 1
Is a perspective view showing the optical system supporting device, FIG. 2 is a partial sectional view taken along the XZ plane, and FIG. 3 is a side view. As shown in the figure, in this apparatus, the objective lens 1 is held by a holding member 2, and the holding member 2 is supported by springs 3a to 3d so as to be displaceable in the Z and X directions.

The holding member 2 is an integrally molded product made of synthetic resin, and a cylindrical lens mounting portion 2a is formed on the upper surface thereof, and the objective lens 1 is fixedly adhered thereto. The objective lens 1 is, for example, an aspherical single lens formed by plastic injection molding, and is used to focus laser light on pits on the surface of the optical disk 12.

Next, a convex portion 2c is formed on the side surface (X direction) of the holding member 2, and springs 3a to 3d as supporting members are attached thereto. The springs 3a to 3d are wire-like metal single wires, and the other ends are fixed to the fixing member 5. In addition, 4 is a rubber damper integrally provided on the outer periphery of each spring.

Next, on the side surface (Y direction) of the holding member 2,
The focus coil 6 and the tracking coil 7 as the driving means are bonded and fixed. An outer yoke 8a and an inner yoke 8b of the magnetic circuit are formed by a part of the base 8 made of sheet metal, and the magnet 9 is fixed to the inner surface of the outer yoke 8a. By these, two sets of magnetic circuits are configured symmetrically with the optical axis position in the Y direction, and the holding member 2 is displaced and driven in the Z and X directions.

Next, a recess 2c is formed in the bottom of the holding member 2, and the mirror 10 is placed therein. Then, the light flux emitted from the optical unit 11 is bent at a right angle by the mirror 10 and projected on the surface of the optical disc 12 through the objective lens 1 to read / write information. The optical unit 11 is composed of a light emitting element such as an LD and a light receiving element such as a PD.

Here, in the optical system supporting device of the present invention, the notch opening 2d is provided on the side surface of the holding member 2 so as not to obstruct the light beam entering the mirror 10 from the optical unit 11.
Further, the position of the convex portion 2b for fixing the two springs 3c, 3d on the lower side in the Z direction so as not to interfere with the incident light flux, and the spring fixing portion 5a of the fixing member 5 for the other two springs 3a, 3b.
The position of the notch is displaced in the Y plus (tangential) direction from the position.

Therefore, since the spring 3d on the incident light flux side does not interfere with the light flux, the height of the light flux (Z direction position) can be raised to a position just below the spring 3b. Thereby, the optical path length in the Z direction from the mirror 10 to the objective lens 1 can be shortened. And the four springs 3a-
Since the same parts can be used for d, there is no problem of cost increase.

In this embodiment, the upper portion of the fixing member 5 is cut out as shown in FIG. 3 so as to avoid interference with the cartridge 13. As a result, the entire optical system supporting device can be brought closer to the optical disk 12, and the device can be made thinner.

[0020]

Second Embodiment Next, a second embodiment of the present invention will be described. Figure 1
Is a perspective view showing the optical system supporting device, FIG. 2 is a partial sectional view taken along the XZ plane, and FIG. 3 is a side view. As shown in the figure, in this embodiment, two springs on both sides of the incident light are arranged so as to be offset from each other.

That is, the spring 3 on the side surface of the incident light side (+ X direction) so as not to block the notch opening 2d of the holding member 2.
In order to dispose both b and 3d in the + Y direction, the convex portion 2b is provided so as to be displaced. Here, the convex part on the opposite side is
It is provided at the same position as in the first embodiment without shifting.

In the first embodiment, the base 8 made of sheet metal is used.
In this embodiment, the yokes 8a and 8b are integrally formed. However, in this embodiment, the outer yoke 14a and the inner yoke 14b made of sheet metal are fixed to the base 8 made of resin, and the mirror 10 is adhesively fixed to the base 8. And

In this embodiment, the dimension in the X direction is also shortened. Specifically, the light shielding member 15 is fixed on the cutout opening 2d on the side surface on the incident light side, and the LED is attached to this portion.
A radial sensor 18 formed by press-fitting 16 and two-divided PD 17 is arranged. Here, the radial sensor 18 is an LED
Light-shielding member 1 in which light emitted from 16 is fixed to holding member 2
Projection is made on the PD 2 divided into two through 5, and the position of the objective lens 1 in the radial (X) direction is detected from this difference signal. With this configuration, the radial sensor 18 can be arranged in the vicinity of the holding member 2, and the spring 3b does not intervene between the holding member 2 and the radial sensor 18 as in the conventional case. The size of the system support device in the X direction can be shortened.

As described above, according to this embodiment, it is possible to realize a thin optical system supporting device and a small size in the X direction.

The present invention is not limited to the above embodiment, and for example, instead of arranging the supporting member extending in the Y direction, the supporting member may be arranged in the X direction. Further, it goes without saying that the present invention can also be applied to a focus actuator that drives an objective lens in only one direction. Further, the light flux incident on the mirror just below the objective lens from the light source may not be from the direction perpendicular to the extending direction of the spring as in the embodiment.

[0026]

As described above, according to the optical system supporting device of the present invention, by forming the notch opening in the side surface of the holding member, the supporting member on the incident light side is further displaced in the longitudinal direction and attached. This prevents the interference of the incident light path. As a result, it is possible to provide a sufficiently small and thin optical system supporting device without being restricted by the engagement of the incident optical path with the holding member and the supporting member as in the conventional case and hindering the thinning. In addition, since it can be carried out only by changing the design of some of the parts, and it is not necessary to increase the number of parts or the kind of parts, the cost and the number of assembling steps are the same as the conventional one, and it is economically excellent.

[Brief description of drawings]

FIG. 1 is a perspective view showing an optical system supporting device according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing an optical system support device of Example 1 according to the present invention.

FIG. 3 is a side view showing an optical system support device of Example 1 according to the present invention.

FIG. 4 is a perspective view showing an optical system supporting device according to a second embodiment of the present invention.

FIG. 5 is a partial cross-sectional view showing an optical system support device of Example 2 according to the present invention.

FIG. 6 is a side view showing an optical system supporting device according to a second embodiment of the present invention.

FIG. 7 is a perspective view showing a conventional optical system supporting device.

FIG. 8 is a partial cross-sectional view showing a conventional optical system support device.

FIG. 9 is a side view showing a conventional optical system support device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens (optical element) 2 Holding member 2a Lens mounting part 2b Convex part 2c Recessed part 2d Notch opening 3a-d Spring (supporting member) 4 Rubber damper 5 Fixing member 5a Spring fixing part 6 Focus coil 7 Tracking coil 8 Base 8a , 14a Outer yoke 8b, 14b Inner yoke 9 Magnet 10 Mirror 11 Optical unit 12 Optical disc 13 Cartridge 15 Light blocking member 16 LED 17 PD 18 Radial sensor

Claims (1)

[Claims] 1. An optical system supporting device comprising a holding member for holding an optical element, a plurality of supporting members for movably supporting the holding member in a required direction, and a driving means for displacing the holding member. An optical system supporting device, characterized in that a cutout opening is formed in a side surface of a holding member, and at least one of the plurality of supporting members on the incident light side is displaced in the longitudinal direction of the supporting member.