JPH08329485A - Objective lens supporting device - Google Patents

Abstract

PURPOSE: To reduce the weight of a movable part and the number of parts by eliminating a light shielding plate, a reflecting plate, a balancer, etc. CONSTITUTION: An objective lens 10 for converging luminous fluxes on an disk recording medium is held by a lens holder 20. The lens holder 20 is elastically held by a supporting holder 40 via an elastic body in a focusing direction or a tracking direction. A position sensor 60 having a light emitting element and a light receiving element approximately on the same plane is provided in the supporting holder 40. A notched part 24 is formed on a surface opposite the position sensor 60 of the lens holder 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens supporting device in an optical pickup used in an optical disk device or the like, and more particularly to an objective lens supporting device provided with means for detecting the position of the objective lens.

[0002]

2. Description of the Related Art In an optical disc apparatus or the like, in order to randomly access the optical pickup to an arbitrary track of an optical disc medium, the optical pickup is moved in a radial direction of the disc, that is, a tracking direction by a linear motor, a brush motor, a lead screw or the like. Let At this time, the objective lens is shaken in the tracking direction due to inertial force.

Therefore, conventionally, in order to reduce the shake of the objective lens, a position detecting means capable of always detecting the position of the objective lens is provided in the objective lens supporting device (Japanese Patent Laid-Open No. 3-269834). 63-200
No. 327, Japanese Utility Model Laid-Open No. 4-93920, and Japanese Patent Laid-Open No. 7-14190).

An objective lens supporting device provided with a conventional position detecting means in Japanese Patent Laid-Open No. 7-14190 will be described with reference to FIG. In FIG. 4, the objective lens 71
The lens holder 72 holding the lens is supported by a support holder 74 via two leaf springs 73, one above the other. A focusing coil 75 is wound around the lens holder 72, and two tracking coils 76 are arranged so as to oppose each other across the objective lens 71 in a direction orthogonal to the tracking direction (T direction in the drawing).

The support holders 74 are fixed to the yoke 77 by screws or the like, and one magnet 78 is arranged in each of the yokes 77 so as to face the tracking coil 76. The leaf spring 73 is also used as a means for energizing the focusing coil 75 and the tracking coil 76. In order to energize the upper and lower four leaf springs 73 from the outside, the actuator flex 79 is attached to the support holder 74 by soldering or the like. Has been.

In such a structure, when a driving current flows through the focusing coil 75, an electromagnetic force is generated by the magnetic circuit formed by the yoke 77, the magnet 78 and the focusing coil 75, and the lens holder 72.
Are driven in the focusing direction (F direction in the figure). Similarly, when a driving current flows through the tracking coil 76, an electromagnetic force is generated by the magnetic circuit formed by the yoke 77, the magnet 78, and the tracking coil 76,
The lens holder 72 is driven in the tracking direction T. Further, the objective lens supporting device is provided with a position detecting means including a light shielding plate 80 and a sensor body 81 for the purpose of detecting the amount of movement of the objective lens 71 in the tracking direction T.

The lens holder 72 moves in the tracking direction T.
When moved to, the light shield plate 80 attached to the lens holder 72 is moved to the sensor main body 8 attached to the yoke 77.
The light flux from the first light emitting element 82 is blocked, and the blocked light flux is received by the light receiving element 83. In the light receiving element 83, a current flows according to the movement of the light shielding plate 80 in the tracking direction, and is detected by the servo circuit or the like via the sensor flex 84.

Further, in the lens holder 72, the light shielding plate 8 is arranged in the tracking direction T with the objective lens 71 interposed therebetween.
A balancer 85 is attached to a position opposed to 0 in order to balance the weight of the movable portion including the objective lens 71, the lens holder 72, the focusing coil 75, and the tracking coil 76.

[0009]

However, in the conventional objective lens supporting device, since the light shielding plate 80 is attached to one side of the lens holder 72 as a means for detecting the position of the objective lens 71 in the tracking direction, the movable portion is not movable. The balancer 85 must be added to the other side of the lens holder 72 for the purpose of balancing the weight of the above, and there is a problem that the weight of the movable portion is large and the number of parts is large.

Further, the sensor body 81 is attached to the lens holder 7
Since it is arranged on the side surface of No. 2, the whole objective lens supporting device is large, and a sensor flex 84 for drawing out the sensor output must be added, which also increases the number of parts,
As a result, there is a problem that the cost becomes high.

The present invention has been made in view of the above-mentioned problems, and it is possible to reduce the weight of a movable part without adding a balancer and to reduce the number of parts thereof.
It is another object of the present invention to provide an objective lens supporting device that does not require the addition of a sensor flex, can be made small in the entire objective lens supporting device, and can reduce the number of parts.

[0012]

In order to achieve the above object, an objective lens supporting device according to claim 1 of the present invention is an objective lens for condensing a light beam on a disk-shaped recording medium, and an objective for holding this objective lens. A lens holder, a support holder that movably supports the objective lens holder in the focusing direction and the tracking direction via an elastic body, and a position sensor in which the light emitting element and the light receiving element provided in the support holder are substantially in the same plane. And a notch formed on the surface of the objective lens holder facing the position sensor. Further, preferably, the support holder is provided with a printed circuit board for energizing the focusing direction and tracking direction drive coils,
This printed circuit board also serves as a printed circuit board that outputs an electrical signal from the position sensor.

[0013]

According to the objective lens supporting apparatus of the present invention having the above-mentioned structure, the lens holder moves as the objective lens moves, and the notch portion of the lens holder also moves. In the position sensor, the light receiving element receives the light emitted from the light emitting element and reflected by the lens holder, and the amount of the reflected light detects the amount of movement of the objective lens in the tracking direction. That is, the movement of the notch changes the amount of light emitted from the light-emitting element that strikes the lens holder surface and the notch,
As a result, the amount of reflected light changes, so that the position sensor can detect the amount of movement of the objective lens.

Therefore, the light shielding plate, the reflection plate, and the balancer are unnecessary. Further, the support holder integrally holds the position sensor and elastically supports the objective lens holder in the focusing direction and the tracking direction. This eliminates the need to prepare the sensor flex independently.

Further, the printed circuit board for outputting an electric signal from the position sensor is also used as a printed circuit board for energizing the focusing direction and tracking direction drive coils. This eliminates the need to separately provide a printed circuit board for signal output of the position sensor.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the objective lens supporting device of the present invention will be described below with reference to the drawings. 1 is a perspective view of an objective lens supporting device according to the present invention, FIG. 2 is a partial sectional view showing a position detecting portion of the objective lens supporting device according to the present invention,
FIG. 3 is a detection position characteristic diagram showing the relationship between the lens holder moving distance and the relative photocurrent in the objective lens supporting device according to the present invention.

In FIG. 1, reference numeral 10 denotes an objective lens, which is held by a lens holder 20. A relay board 21 is attached to the lens holder 20, and a wire used also as an energizing means and each terminal of the focusing coil 22 and the tracking coil 23 are connected to the relay board 21 by soldering. The lens holder 20 is elastically fixed to the support holder 40 and a printed circuit board (or a flexible printed circuit board, hereinafter the same) 50 with two upper and lower metal wires 30 made of bronze, beryllium copper or the like as elastic bodies. ing.

The support holder 40 is provided with the printed circuit board 50 and the position sensor 60, and the terminals 61, 62, 63 and 64 of the position sensor 60 are soldered to the circuit board 50. Further, the printed circuit board 50 is soldered with a drawing-out flex 51 that shares the actuator flex and the sensor flex. The magnetic circuits of the yoke and the magnet are not shown.

A notch 24 is formed on the surface of the lens holder 20 facing the position sensor 60, and the light emitted from the light emitting element of the position sensor 60 borders on the edge 25 of the notch 24. The amount of return light reflected by the surface of the lens holder 20 and returned to the light receiving element is different.

The operation of the objective lens supporting apparatus of the present embodiment having such a structure will be described with reference to FIGS. Light is radially emitted from the light emitting element 65 of the position sensor 60 in the direction of arrow A, and the light is emitted by the lens holder 20 in the direction of arrow B.
The light reflected in the direction of is received by the light receiving element 66 as return light. At this time, the light is reflected by the lens holder 20 on the left side (− side) of the edge 25 of the cutout portion 24, but the light is reflected on the right side (+ side) of the edge 25 of the cutout portion 24. And is not reflected by the surface of the lens holder 20.

The lens holder 20 moves in the tracking direction T.
When moved to, the position of the edge 25 also changes and the amount of return to the light receiving element 66 also changes relatively. FIG. 3 shows the relationship of the relative photocurrent output from the position sensor 60 with respect to the movement amount of the lens holder 20 at this time.

In FIG. 3, the lens holder 20 is
When moving in the tracking direction T, the position sensor 60
The position of 60% with respect to the maximum current output in step S2 is set as the center position in the tracking direction T, and when the lens holder 20 moves to the + side or − side, the relative change of the output photocurrent is calculated. Shows. From the change in the relative photocurrent, the position of the lens holder 20, that is, the objective lens 10 is detected.

[0023]

As described above, according to the objective lens supporting apparatus of the present invention, the notch is provided on the surface of the lens holder that faces the position sensor, and the change in the reflected light amount due to the movement of the edge in the tracking direction. With this, the amount of movement of the objective lens in the tracking direction is detected.
Since a light shielding plate, a reflection plate, and a balancer are not necessary, it is possible to reduce the weight of the movable part and the number of parts.

Further, since the position sensor is attached to the support holder and integrally formed, the position sensor flex can be shared with the actuator flex, so that the number of parts and the cost can be reduced. .

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of an objective lens supporting device according to the present invention.

FIG. 2 is a partial sectional view of a position detecting portion of an embodiment of the objective lens supporting device according to the present invention.

FIG. 3 is a detection position characteristic diagram showing the relationship between the amount of movement of the lens holder and the current output from the position sensor in the embodiment of the objective lens supporting device according to the present invention.

FIG. 4 is an exploded perspective view of a conventional objective lens support device equipped with a position detection function.

[Explanation of symbols]

 10 Objective Lens 20 Lens Holder 24 Notch 30 Metal Wire 40 Support Holder 50 Printed Circuit Board 60 Position Sensor 61 Light Emitting Element 62 Light Receiving Element

Claims (2)

[Claims] 1. An objective lens for converging a light flux on a disk-shaped recording medium, and a lens holder for holding this objective lens,
A support holder that elastically supports the lens holder in the focusing direction and the tracking direction via an elastic body, a position sensor in which the light emitting element and the light receiving element provided in the support holder are substantially in the same plane, and the lens holder Objective lens supporting device, which comprises a position sensor and a notch formed in a surface facing the position sensor. 2. The support holder is provided with a printed circuit board for energizing the focusing direction and tracking direction drive coils, and the printed circuit board also serves as a printed circuit board for outputting an electric signal from a position sensor. The objective lens support device described.