JPH0325733A - Multistage multioptical head for optical disk device - Google Patents

Abstract

PURPOSE:To realize a multistage multioptical head with fast access speed with high mass-productivity and a low price by switching a laser beam toward an actuator in an optical disk window with an optical switch or a galvanomirror, etc. CONSTITUTION:An optical pickup 12 is equipped with the optical switch 12a to switch an optical beam in a horizontal direction from a laser diode 12c to two laser beams shown as A and C and a mirror 12b. At a mirror part 14, the beams A and C that are upper and lower parallel optical paths are directed to two actuators 16 arranged keeping an interval in the radial direction of an optical disk 22 with a riser mirror 14a. Tracking servo and focusing servo can be performed by supporting an objective lens 18 movably freely with the actuators 16. Therefore, each beam takes partial charge of tracking on two, inner and outer, peripheral areas of the optical disk, which shortens access time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a multi-stage multi-optical head for an optical disc device. (Prior art) Conventionally, optical disk devices have generally been equipped with one optical head (l beam generated by one laser diode).Since only one laser beam can be used, the access speed has decreased. The speed of reading information on optical disks was slow, and there was a significant difference in speed compared to multi-head technology such as magnetic disks.In addition,
The problem with a single head was the same as the writing speed, which was a cause of limiting the field of application of optical disk devices. Therefore, it is necessary to provide multiple laser beams for the optical head of the optical disk device, and the following proposals have been made. In other words, a method has been proposed in which multiple laser diodes are mounted on a single body of an optical head (laser array). Another proposal has been made to arrange multiple optical heads at different angles in the circumferential direction of the optical disk. (Problem to be solved by the invention) In the case of an optical head that uses only a single actuator,
As mentioned above, there is an inherent drawback that the speed of accessing information, and therefore the speed of reading and writing, is slow. In addition, the laser array method is difficult to assemble and adjust, and problems such as differences in characteristics of individual laser diodes and problems when one laser diode breaks down still remain to be solved. Furthermore, the method of arranging multiple optical heads at different angles in the circumferential direction of the optical disk was not always usable when the optical disk was in a cassette case because of the cassette window. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a multi-stage multi-optical head for an optical disc device which can widen the field of application by eliminating the above-mentioned conventional drawbacks and improving the access speed of the optical disc device. In particular, the objective is to speed up data writing and reading even when the optical disc is stored in a cassette and can only be accessed through the cassette window, thereby solving the slow access speed that has been the biggest drawback of conventional optical disc devices. Another object of the present invention is to create a multi-stage multi-optical head for an optical disk device that can realize mass production and low cost by utilizing conventional technology as much as possible in the structure of the optical head. The goal is to provide the following. (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a multi-stage multi-optical head for an optical disk device, which includes a laser diode and an optical switch that switches the laser beam from the laser diode in at least two directions. an optical pickup having a galvano mirror; and at least two raised mirrors that are juxtaposed in the radial direction of the optical disk, receive a laser beam from the optical switch or the galvano mirror of the optical pickup, and change the direction of the laser beam. a mirror part; and fixed to the upper part of the mirror part,
A multi-stage multi-optical head for an optical disc device, comprising at least two actuators each having an objective lens that receives a laser beam from each rising mirror, and means for moving at least the mirror portion in the radial direction of the optical disc. The following will be adopted. (Embodiment) Next, a preferred embodiment of the multi-stage multi-optical head of the present invention will be described with reference to the drawings. FIG. 1 is a schematic perspective view of the main parts and optical disk of the first embodiment of the multi-stage multi-optical head of the present invention, FIG. 2 is a schematic side view of the main parts, and FIG. FIG. 4 is a schematic perspective view of main parts and an optical disk of a second embodiment of the multi-stage multi-optical head of the invention, and FIG. 4 is a schematic plan view of the main parts. Referring first to FIGS. 1 and 2, a first embodiment of the present invention will be described.
The multi-stage multi-optical head 10 (hereinafter simply referred to as an optical head) of the embodiment is controlled by an optical pickup 12, a mirror section 14, an actuator 16 fixed to the upper part of the mirror section, and a linear motor 20.

Note that the optical head 10 is arranged so that its actuator 16 opposes the window 22a of the cassette of the optical disc 22.

The optical pickup 12 has a built-in laser diode 12c, a detector, a condenser lens, a 1/4 wavelength plate, etc. similar to the conventional one. This optical pickup 12 further includes:
According to the invention, an optical switch 12a and a mirror 12b are provided. This optical switch 12a is a second
As shown in the figure, the horizontal direction of the laser beam from the laser diode 12c is indicated by the solid line "A" and the straight direction indicated by "A" and the dotted line "A".
This is for switching between the direction (in this embodiment, upward) perpendicular to the straight direction as shown by B''.
The mirror 12b is provided to change the direction of the laser beam received from the optical switch 12a and redirect it to the horizontal direction as indicated by the dotted line "C". Thus, the two laser beams labeled "A" and "C" are on parallel optical paths spaced apart from each other. The mirror unit 14 includes two mirrors 14a that receive the laser beam from the optical switch 12a and change the direction of the laser beam toward two actuators that will be described in detail later. These raised mirrors 14
a is used to direct the laser beam, which is located in a parallel optical path spaced vertically from the optical pickup, to two actuators 16 spaced apart in the radial direction of the optical disk 22 (that is, in the tracking direction). The optical disk 22 is arranged so as to be shifted in the direction and in the radial direction of the optical disk 22. The actuator 16 movably supports an objective lens 18 that focuses the laser beam from the mirror 14a on the optical disk surface, and is configured to perform tracking servo and focusing servo of the objective lens 18. These actuators 16 are connected to an optical disk 22 (for convenience of illustration, only the lower plate with the optical disk cassette window is shown in the drawing).
The cassette window 22a is disposed opposite to the window 22a of the cassette and shifted in the radial direction. Therefore, tracking of the inner and outer circumferences of the optical disc can be shared, and access time can be shortened. The linear motor 20 is for moving the mirror section 14 and the actuator l6 fixed thereto in the radial direction of the optical disk 22 to perform a tracking operation. Next, referring to FIGS. 3 and 4, the second embodiment of the present invention will be described.
An example optical head 10 is shown. The optical head of this second embodiment has the optical switch 1 of the optical head of the first embodiment.
The main difference is that a galvano mirror 12d is used instead of 2a to switch the direction of the laser beam, but the other points are the same. The galvanometer mirror 12d is attached to the optical pickup 12 so as to be rotatable within a horizontal plane. Due to the rotation angle of the galvanometer mirror 12d, the laser beam from the laser diode 12c is directed to either one of the two mirrors 12e provided in the optical pickup 12, and as shown by "D" and "E", the laser beam takes two parallel optical paths in the horizontal plane. The laser beam from the mirror 12e enters the two rising mirrors 14a of the mirror section, and is directed from these mirrors 14a to the objective lens 18 of the actuator 16 in the same manner as in the first embodiment. In this second embodiment, two upright mirrors 14a are provided on the mirror section 14 in order to direct the two laser beams in the horizontal plane coming from the optical pickup to the two actuators 16 arranged to be shifted in the radial direction of the optical disk. The discs are distributed in a horizontal plane, shifted in the radial and circumferential directions of the optical disc. Although preferred embodiments of the present invention have been described above, various modifications can be made within the scope of the present invention. For example, an ellipse may be used to switch the laser beam into two or more optical paths (eg, three optical paths). It is also possible to configure the optical pickup as a unit integrated with the mirror section and move this unit using a linear motor. In addition, we have explained that the optical switch is used for switching in the vertical direction and the galvano mirror is used for switching in the horizontal left and right directions, but on the contrary, the optical switch is used for switching between left and right, and the galvano mirror is used for switching in the vertical direction. It can also be used for switching. It is also possible to place an optical switch or galvanometer mirror in the mirror part. (Effects of the Invention) As described above in detail, the present invention provides an optical switch or a galvanometer mirror or the like to switch the direction of the laser beam from the laser diode and direct it to the actuator disposed within the window of the optical disk. Since the structure is simple, it does not require the use of multiple laser diodes as in a laser array, and does not require delicate adjustments between laser diodes, and can be applied to optical discs with windows.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of the main components and optical disk of a first embodiment of the multi-stage multi-optical head of the present invention. FIG. 2 is a schematic side view of its main parts. FIG. 3 is a schematic perspective view of the main components and optical disk of a second embodiment of the multi-stage multi-optical head of the present invention. FIG. 4 is a schematic plan view of its main parts. DESCRIPTION OF SYMBOLS 10... Optical head, 12... Optical pickup, 12a... Optical switch, 12d... Galvanometer mirror 14... Mirror part, 14a... Mirror 16... Actuator, 18... Objective lens, 20... Linear mode, 22... Optical disk.

Claims (4)

[Claims] (1) In a multi-stage multi-optical head for an optical disk device, an optical pickup having a laser diode and an optical switch or a galvano mirror that switches the laser beam from the laser diode in at least two directions, and an optical pickup that is arranged in parallel in the radial direction of the optical disk, one of the a mirror section having at least two raising mirrors that receive the laser beam from the optical switch or galvano mirror of the optical pickup and change the direction of the laser beam; at least two having objective lenses that receive the laser beam;
1. A multi-stage multi-optical head for an optical disc device, comprising: an actuator; and means for moving at least the mirror portion in the radial direction of the optical disc. (2) The multi-stage multi-optical head for an optical disc device according to claim 1, wherein the moving means is a linear motor. (3) The multi-stage multi-optical head for an optical disc device according to claim 1, wherein the raised mirrors of the mirror section are arranged to be shifted in the vertical direction. (4) The multi-stage multi-optical head for an optical disc device according to claim 1, wherein the raised mirrors of the mirror section are arranged shifted in the left-right direction.