JPH09198690A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the workability at the time of adjusting a focus error signal by movement in an optical axis direction by providing a holder for holding quadrisected photodetectors and a cylindrical lens with a guide for prohibiting the rotation around an axis. SOLUTION: A prism 9 introduces the light beam from a semiconductor laser 3 to a pickup body 2 and introduces the reflected beam from the pickup body 2 to the quadrisected photodetectors 8 via the cylindrical lens 6. When the beam from the pickup body 2 exists at a position where the beam is focused at a disk, the beam is so adjusted that a circular beam image is formed at the photodetectors 8 by moving the cylindrical holder 5 to which the cylindrical lens and the photodetectors 8 are attached along a holder guide hole 7. The inner peripheral surface of the holder guide hole 7 is provided with a guide groove 10 formed in an axial direction and the corresponding outer peripheral part of the cylindrical holder 5 is provided with a projecting member consisting of a leaf spring. The member is engaged with the guide groove 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device used in, for example, a magneto-optical disc player.

[0002]

2. Description of the Related Art An optical pickup device controls a focus actuator for driving an objective lens by detecting a focus error signal in order to maintain a constant focal length against surface deviation of a disc itself.

As a method of detecting this focus error signal, an astigmatism method is known, which is a method of generating astigmatism by an optical component using an anamorphic optical system.

An anamorphic optical system is two sections that include the optical axis and are orthogonal to each other, and have different focal lengths or magnifications. A cylindrical lens is used in an optical pickup device.

In this astigmatism method, for example, Japanese Unexamined Patent Publication No. Sho 53 is used.
As disclosed in Japanese Unexamined Patent Publication No. 1003, a four-division sensor detects reflected light, and the output signal of each sensor is calculated to output a focus error signal.

The cylindrical lens is fixed to the cylindrical holder and then mounted on the pickup base. Then, the holder is slid in the optical axis direction so that the focus error signal becomes zero at the focus position.

[0007]

However, when the holder having the cylindrical lens is slid in the optical axis direction, the holder also rotates at the same time, and the optical image of the four-division sensor also rotates.
The boundary of each sensor of the four-division sensor is a dead zone of 5 to 10 μm, and when the optical image rotates in this way, the amount of light entering the dead zone increases, and the amplitude of the focus error signal decreases.

Therefore, a hole or groove is formed in the holder, and when the holder is adjusted, a pin is inserted into the hole or the like to prevent the holder from rotating, but this adjustment is complicated.

[0009]

In view of the above points, the present invention is directed to a photodetector for detecting reflected light through an anamorphic lens mounted in a cylindrical hole provided in a pickup base so as to be slidable. In the one having a holder guided to, a convex pressing spring which is pressed by a screw is provided in a groove provided in the holder, and a guide groove for guiding the pressing spring is provided in a cylindrical hole of the pickup base.

[0010]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view of an optical pickup device. In the figure, (1) is an aluminum pickup base, which is connected to a base feeding mechanism of a disc reproducing device (not shown) and is arranged in a radial direction of the optical disc. Will move.
(2) is a pickup main body fixed in the base (1), and incorporates an actuator mechanism for three-dimensionally driving the objective lens. (3) is a semiconductor laser fixed to one end of a beam guide hole (4) formed in the base (1), (5)
Is a cylindrical holder having a cylindrical lens (6) fixed to one opening and inserted into a cylindrical holder guide hole (7) formed in the base (1). Reference numeral (8) denotes a four-division photodetection element which is screwed and fixed to the pickup base (1) so as to cover the holder guide hole (7), and focus control is performed based on the output of this detection element.
(9) guides the light beam from the semiconductor laser (3) to the pickup body (2), and then the pickup body (2)
This is a prism that guides the reflected beam from the cylindrical lens (6). The light beam from the cylindrical lens (9) is applied to the light detection element (8) through the holder (5).

Thus, the holder guide hole (7) has a structure shown in FIG.
As shown in (left side view of the optical pickup device with the photodetector (8) removed), a spring guide groove (10) for guiding a leaf spring (15) arranged in a holder (5) described later. , Screw holes (1
1) and an adjusting hole (12) communicating with the bottom surface is formed. The shape of the adjusting hole (12) is circular as shown in FIG. 3 (bottom view of the optical pickup device).

As shown in FIG. 4, the holder (5) is provided with an adjusting groove (13) around the holder and a spring insertion groove (14) in the length direction. A dogleg-shaped leaf spring (15) is inserted into the spring insertion groove (14) with its apex facing outward. Further, the apex of the leaf spring (15) protrudes from the periphery of the holder (5) in the inserted state, and when the holder (5) is inserted into the holder guide hole (7), this protruding portion has a spring guide groove. You will be guided to (10). In addition, as shown in FIG. 3, a holder (5)
In the state in which is inserted into the holder guide hole (7), the adjustment groove (13) faces the adjustment hole (12) of the pickup base (1).

In the above structure, when the beam from the pickup body (2) is at the in-focus position with respect to the disc, the holder (5) is beamed so that a circular beam image is formed on the photodetector (8). It is necessary to move it in the optical axis direction. For this adjustment, the adjustment rod (1
6) is inserted into the adjusting hole (12), and then the adjusting rod (1
6) Adjust the adjustment protrusion (17) of the holder (5) to the adjustment groove (1).
3) and the adjusting rod (16) is rotated.

In this case, since the protruding portion of the leaf spring (15) inserted in the holder (5) is engaged with the guide groove (10), the holder (5) does not rotate and the optical axis of the beam is not rotated. It will move only in the direction. After the adjustment is completed, the screw is screwed into the pickup base (1) through the screw hole (11). At this time, the tip of the screw
The leaf spring (15) is pushed against the biasing force,
The holder (5) will be fixed to the pickup base (1).

As described above, when the holder (5) is adjusted, the work of preventing the rotation of the holder (5) is unnecessary, and the adjustment work can be efficiently performed.

[0017]

As described above, according to the present invention, there is no need to prevent the holder from rotating when adjusting the holder, and the optical pickup device can be efficiently adjusted. You can

[Brief description of drawings]

FIG. 1 is a plan view of an optical pickup device of the present invention.

FIG. 2 is a left side view of the optical pickup device with a photodetector removed.

FIG. 3 is a bottom view of an essential part of the optical pickup device of the present invention.

FIG. 4 is a perspective view of the holder of the present invention.

FIG. 5 is a perspective view of an adjusting rod of the present invention.

[Explanation of symbols]

 1 Pickup base 2 Pickup body 5 Holder 6 Cylindrical lens 7 Holder guide hole 10 Spring guide groove 14 Spring insertion groove 15 Leaf spring

Front page continued (72) Inventor Shinichi Yamaguchi 3 201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd.

Claims (1)

[Claims] 1. An optical pickup device for irradiating a disk-shaped medium with a light beam and reading a recording signal of the disk-shaped medium based on the reflected light, which is slidably disposed in a cylindrical hole provided in a pickup base. , A holder having a holder for guiding reflected light to a photodetector through an attached anamorphic lens, wherein a groove provided in the holder is provided with a convex pressing spring which is pressed by a screw, and a cylinder of the pickup base. An optical pickup device characterized in that a guide groove for guiding a pressing spring is provided in the hole.