JPH0573939A - Objective lens driving device - Google Patents

Abstract

PURPOSE:To reduce the occupancy distance in the radial direction, magnetically control the device by each magnetic flux density, and miniaturize it by horizontally arranging a focusing coil and a tracking (seek) coil in the radial direction of an optical recording medium. CONSTITUTION:A focusing coil 5 and a tracking (seek) coil 6 are horizontally arranged in common in the radial direction of a disk-shaped optical recording medium D. Therefore, the occupancy distance in the radial direction can be reduced for the pertinent arrangement. And also, the movement of an objective lens holding body 2 and a carriage 4 or the like can be magnetically controlled by each magnetic flux density only by providing a magnet 13 at the carriage 4, so that the device can be reduced and miniaturized as a whole, and the optimal design of the coil can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an optical or magneto-optical recording / reproducing apparatus for irradiating an optical recording medium with a laser beam to optically record or erase information. The present invention relates to an objective lens driving device.

[0002]

2. Description of the Related Art An objective lens driving device of this type is used, for example, for recording / reproducing information on / from the disc through an objective lens when recording / reproducing information on / from a rotating disc-shaped optical recording medium (hereinafter referred to as disc). This is for focusing the laser light on the portion, and at this time, the laser light is controlled to move in the radial direction and the focusing direction of the disk. A conventional recording / reproducing apparatus is movably equipped with an optical head including the objective lens driving device. In particular, in order to improve the access speed, the laser light emitting part and the sensor part are separated from the objective lens driving part and fixedly installed on the device frame side, and the optical parts of the moving parts are reduced. , Has also been made lighter.

However, the movable portion (carrier) of the optical head uses the objective lens driving device provided on the carrier to perform a focus operation (direction perpendicular to the disk surface) and a tracking operation (disk radial direction) of the objective lens. In order to perform (a minute range of), a magnetic circuit including a magnet is configured on a carrier, and an actuator equipped with a coil corresponding to tracking and focusing operations is provided,
The carrier is adapted to perform a seek operation (movement over the entire recording / reproducing range in the radial direction of the disk) by an electromagnetic force generated by a magnetic circuit provided outside and a coil provided on the carrier. Therefore, the structure of the entire carrier including the objective lens driving device for focusing and tracking becomes complicated, hindering miniaturization, and it is difficult to move the objective lens at high speed.

Therefore, an objective lens driving device as shown in FIG. 6 has already been proposed. Here, a pair of magnets 11 facing each other along the seek direction are provided, and a magnetic circuit is formed together with the magnetic body 10 as a yoke and the end magnetic body 12 arranged on the back surface of the magnet 11. , A carriage 4 for elastically holding an objective lens holder 2 for holding the objective lens 1 via a leaf spring 3, a coil 6 for seek drive and tracking drive so as to cut off the magnetic flux of the magnetic circuit. In addition, the objective lens holder 2 is further equipped with a focusing driving coil 5 for cutting the magnetic flux in order to move the objective lens holder 2 in the optical axis direction of the objective lens 1.

In the objective lens driving device, the carriage 4 is supported via a bearing 7 so as to be guided along a guide rail 8 extending in the seek direction.

[0006]

SUMMARY OF THE INVENTION With such a configuration,
The tracking drive coil is also used as the seek drive coil, and the carriage 4 is not provided with a magnet or a magnetic body forming a magnetic circuit corresponding to the coil and the focusing drive coil 5. Therefore, the structure of the movable optical system can be made smaller and lighter, and high-speed accessibility can be improved, but the coil 5 for focusing drive and the coil 6 for tracking drive (for seek drive) have a common magnetic field. Due to the arrangement in the circuit gap, it is necessary to secure each occupied distance in the radial direction of the disk D, and it is impossible to reduce the size and size of the device in this direction. Further, since each coil 5 and 6 uses a common magnetic circuit, there is a restriction on the magnetic flux density and the like, which makes it difficult to perform optimum design.

[0007]

SUMMARY OF THE INVENTION The present invention has been made based on the above circumstances, and in the radial direction of an optical recording medium, a focusing coil and a tracking (seeking) coil are arranged in common, and accordingly, An objective lens driving device that enables optimal design of the coil by devising such that the occupied distance in the radial direction can be shortened and the magnetic flux density can be magnetically controlled within a range that does not hinder weight reduction. It is the one we are trying to provide.

[0008]

Therefore, in the objective lens driving device of the present invention, the objective lens of the optical head is moved with respect to the optical recording medium in the seek direction, the tracking direction and the focusing direction. In the objective lens driving device to be controlled, a pair of magnets facing each other along the seek direction is provided, and a magnetic circuit is formed with a magnetic body provided in parallel with the magnets, and the objective lens is provided via an objective lens holder. The carriage for holding is provided with seek drive and tracking drive coils so as to cut off the magnetic flux of the magnetic circuit, and the objective lens holder is moved in the optical axis direction of the objective lens. In order to achieve this, a coil for driving focusing is equipped, and the carriage is further provided with another magnet located between the coils. Follower - Cushing constitute a magnetic circuit for driving.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. In this embodiment, the same components as those shown in the conventional example are designated by the same reference numerals and the description thereof will be omitted. In particular, here, the leaf spring 3 is attached to the carriage 4.
The objective lens holder 2 held via the carriage is located between the coils 6 for tracking (seek) driving provided on the left and right of the carriage 4, and the leaf spring 3 is the carriage. 4 extends from one side parallel to the seek direction to the center thereof. A space is formed between the left and right of the objective lens holder 2 and the inner portion of the carriage 4,
Focusing drive coils 5 and 5 are arranged on the left and right sides of the objective lens holder 2 in the space, and facing the carriage, another plate magnet 13 is provided on the carriage side. , 13 are arranged.

The magnet 11 extending in the moving direction of the carriage 4 has a yoke surrounded by the coils 6, 6 in addition to the magnetic body 10 and the end magnetic body 12 provided on the back surface as a back yoke. Together with the magnetic bodies 9, 9 as a magnetic circuit for the coils 6, 6, the plate-shaped magnets 13, 13 make the magnetic bodies 9, 9 of the magnetic circuit function as a back yoke. And constitutes a magnetic circuit for the coils 5 and 5. Further, in the above-mentioned embodiment, reference numeral 14 is a refraction for polarizing the laser beam from the fixed optical unit (not shown) to the objective lens 1 held by the objective lens holding body 2. It's a mirror.

In such a structure, in the radial direction of the disk-shaped optical recording medium, the focusing coils 5, 5 and the tracking (seek) coils 6, 6 are arranged side by side and are commonly arranged. Therefore, the occupied distance in the radial direction can be shortened, and the carriage 13 has the magnet 13,
Since the objective lens holder 2, the carriage 4 and the like can be magnetically moved and controlled with different magnetic flux densities within a range that does not hinder the weight reduction, the overall size reduction and downsizing can be realized, and Enables optimum coil design.

In the above embodiment, the objective lens holder 2 is arranged in symmetrical positions with respect to the coils 6, 6, but in the embodiment shown in FIG. 4 and FIG. The objective lens holder 2 and the carriage 4
You may equip it to the side of one side. In this case, the difference in magnetic flux density between the air gaps causes the unnecessary vibration to occur.
This can be avoided by changing the number of turns of 5 or changing the driving current value to adjust the driving force to be symmetrical.

[0013]

Since the present invention is configured as described above in detail, a pair of magnets facing each other along the seek direction is provided, and a magnetic circuit is formed together with a magnetic body provided in the magnet. , A carriage for holding the objective lens via the objective lens holder is provided with seek drive and tracking drive coils so as to cut off the magnetic flux of the magnetic circuit, and the objective lens holder is provided with In order to move this in the optical axis direction of the objective lens, a coil for driving focusing is provided, and the carriage is further provided with another magnet located between the both coils. However, since the magnetic circuit for driving the focusing is constituted, the focusing coil and the tracking (seeking) coil are arranged side by side in common in the radial direction of the optical recording medium. It is location, correspondingly, can reduce the occupancy distance of the radial, moreover, within a range which does not impair the lighter,
It can be magnetically controlled by each different magnetic flux density, reducing overall,
It is possible to achieve miniaturization, and it is possible to obtain the effect of enabling optimal coil design.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of the present invention.

FIG. 2 is a plan view of the above embodiment.

FIG. 3 is a vertical sectional end view of the embodiment.

FIG. 4 is a plan view of another embodiment.

FIG. 5 is a vertical end view of the above embodiment.

FIG. 6 is a perspective view of the conventional example.

[Explanation of symbols]

 1 Objective Lens 2 Objective Lens Holder 3 Leaf Spring 4 Carriage 5 Coil 6 Coil 7 Bearing 8 Guide Rail 11, 13 Magnet 9, 10, 12 Magnetic Material 14 Refraction Mirror D Disk (Optical Recording Medium)

Claims (1)

[Claims] 1. An objective lens driving device for controlling movement of an objective lens of an optical head in a seek direction, a tracking direction and a focusing direction with respect to an optical recording medium, wherein the objective lens drive device is arranged along the seek direction. A pair of magnets facing each other on the left and right are provided, and a magnetic circuit is configured with a magnetic body provided in parallel with the magnets, and a magnetic flux of the magnetic circuit is cut off in a carriage that holds the objective lens via an objective lens holder. , Seek driving and tracking driving coils are provided, and the objective lens holder is
In order to move this in the optical axis direction of the objective lens, a coil for driving focusing is provided, and the carriage is further provided with another magnet located between the both coils. Then, the objective lens driving device is characterized in that a magnetic circuit for driving the focusing is constituted.