JP2982884B2 - Objective lens drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens driving apparatus used in an optical information recording / reproducing apparatus, and more particularly, to an apparatus for adjusting a relative position between an objective lens and a mirror for directing a laser beam to the objective lens. The present invention relates to an objective lens driving device described above.

[0002]

2. Description of the Related Art Conventionally, a main part of an objective lens driving device is
A carriage movably held on a guide rail and having a magnetic circuit for driving the objective lens, and an actuator mounted on the carriage and driven to adjust the position of the objective lens by the magnetic circuit. .

In such a configuration, the cost of the carriage, the cost of the guide bearing, the cost of the magnetic circuit for driving the objective lens, and the like are increased. Therefore, as shown in FIG. A mirror that directs laser light to the objective lens is mounted on the actuator together,
There has been proposed an objective lens driving device that performs focus, tracking, and access operations on an information recording medium such as an optical disk while performing linear motion while being held by a composite parallel leaf spring.

In FIG. 3, reference numeral 101 denotes an inner yoke of a magnetic circuit, 102 denotes an actuator, 103 denotes a tracking coil, 104 denotes a focusing coil,
105 is an objective lens, 106 is a compound parallel leaf spring,
A mirror (not shown) is arranged inside the actuator 102. Then, the tracking coil 103 and the focusing coil 104 are energized to perform tracking and focusing.

[0005]

The objective lens driving device has the advantage that the number of components is small, and the size and weight are small, so that the access speed to the information recording medium can be increased. It has two drawbacks. That is, one problem is that since the mirror also moves up and down with the focus operation of the objective lens, the return destination of the laser is offset on the servo sensor. The other is that the composite parallel leaf spring has a focus function, so it is vulnerable to torsion.For example, when the actuator causes pitching, the optical axis of the actuator falls, and if this is just the lens falling, The problem is that the mirror may fall down.

[0006]

Therefore, in order to solve the above-mentioned problems, the present invention is constructed so as to hold a mirror separately from a compound parallel leaf spring for holding an objective lens. Since the focusing side does not have a focusing function, the focusing of the lens prevents the mirror from moving up and down. In addition, the torsional rigidity of the compound parallel leaf spring can be increased, and the tilt of the mirror's optical axis can be reduced. It is an object of the present invention to provide an objective lens driving device as described above.

Further, by providing a relative position sensor between the mirror and the lens, the mirror and the objective lens always
It is configured to be able to move while maintaining a certain position in the access direction.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to FIGS. In FIG. 1, reference numeral 1 denotes an inner yoke of a magnetic circuit, 2 denotes a relay yoke, 3 denotes an outer yoke, and 4 denotes a permanent magnet, which are used for focusing, tracking, and access. Reference numeral 5 denotes an actuator, 6
Is an objective lens driven by the actuator 5, 7 is a tracking coil, 8 is a focusing coil, and the focusing coil 8 is integrally formed on the actuator 5. Further, reference numeral 9 denotes a composite parallel leaf spring, which includes three pairs of parallel leaf springs extending in a direction perpendicular to the tracking direction, one of which has one end fixed to the outer yoke, and the other. The end is connected to one end of the other two sets of parallel leaf springs. The other two sets of parallel leaf springs have the other ends attached to the actuator 5. Further, a connecting plate for connecting the leaf springs arranged in parallel with each other is attached to the connecting portion of the parallel leaf springs. When the parallel arms 9a and 9b bend in the tracking direction, the parallel arms 9a and 9b access the optical recording medium such as the optical disk 20 in the radial direction, and the hinges 9c and 9d bend during focusing. The vertical movement of the actuator 5 is allowed. Note that reference numeral 10 is
The pedestal of the composite parallel leaf spring is attached to the outer yoke 3.

Reference numeral 11 denotes a carriage, which is mounted on a composite parallel leaf spring 12 having the same structure as the leaf spring 6 so as not to contact the actuator 5, and as shown in FIG. And a photo sensor 14 and a mirror 15 in the form of, for example, integrally mounted.

The operation of the objective lens driving device will now be described. As shown in FIG.
When accessing, a servo circuit (not shown) operates.
As a result, a current flows through the focusing coil 8 and the tracking coil 7 of the actuator 5, and a magnetic circuit generates forces in the up-down direction and the back-and-forth direction to follow the track on the optical disk. At this time, the photo sensor 14 provided on the carriage 11 observes the distance between the carriage 11 and the actuator 5 in the tracking direction, and always keeps the distance between the carriage 11 and the actuator 5 constant, in other words, the lens 6 and the mirror. 15 so that the position relative to the tracking coil 13 is maintained.
Apply current to

In this case, since the mirror 15 is not linked with the focus operation of the objective lens 6, there is no possibility that the return destination of the laser beam will be offset on the servo sensor. When the actuator 5 pitches and the optical axis of the actuator 5 falls, the mirror 1
There is no risk of the optical axis falling on the 5th side.

[0012]

As described above, according to the present invention, in order to simplify the structure, in the objective lens driving device for supporting and accessing the actuator by the compound parallel leaf spring, the mirror is stably held, In addition, since the mirror and the objective lens are cooperated with each other, the tilt of the optical axis of the mirror can be reduced. Further, by providing a relative position sensor between the mirror and the lens, the mirror and the objective lens are always fixed in the access direction. Excellent effects, such as being able to move while maintaining the position of.

[Brief description of the drawings]

FIG. 1 is a perspective view of the present invention.

FIG. 2 is a cross-sectional view of the present invention.

FIG. 3 is a perspective view of a conventional example.

[Explanation of symbols]

 Reference Signs List 4 magnet 5 actuator 6 objective lens 7 tracking coil 8 focusing coil 9 composite parallel leaf spring 11 carriage 12 composite parallel leaf spring

Claims (3)

(57) [Claims] 1. An actuator having an objective lens that moves in a tracking direction with respect to an optical information recording medium is held by a compound parallel leaf spring, and focusing and tracking of the optical information recording medium are performed by controlling the operation of the actuator. In an objective lens driving device configured to perform an access operation, a mirror for directing laser light to the objective lens via an optical system is provided on a carriage, and the carriage is not held independently of the actuator. An objective lens driving device characterized in that it is configured to guide. 2. The objective lens driving device according to claim 1, wherein the carriage is held by a compound parallel leaf spring. 3. The objective lens driving device according to claim 1, further comprising a detecting unit that detects a distance between the carriage and the actuator.