JPH0296935A - Galvano-mirror unit - Google Patents

Abstract

PURPOSE:To use only one mirror to make the title unit easily adjustable by performing operations to deflect a light beam in the radial direction and tangen tial direction of the information track of a recording medium by means of the mirror and using a laminated piezo-electric element for driving the mirror. CONSTITUTION:Four laminated piezo-electric elements 31a-31d are fixed on the X and Y axes on the rear of a mirror 21 in the vicinity of the outer periphery and other ends of the elements are fixed to a fixing section 32. When such a voltage that elongates the element 31a and contracts the element 31b is applied across the elements 31a and 31b, the mirror 21 rotates in one direction around the Y axis. When a voltage of the opposite polarity is applied across the elements 31a and 31b, on the other hand, the mirror rotates in the opposite direction around the Y axis. When similar operations are made by using the elements 31c and 31d, the mirror 21 can be rotated around the X axis. Therefore, when such operations are simultaneously performed, the mirror 21 can be deflected by a desired angle. Therefore, adjustment of this galvano-mirror unit can be adjusted easily in optical axis by only one mirror and the number of parts can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a galvanometer mirror used as means for deflecting the optical axis of an optical system of an optical recording/reproducing device.

[Summary of the invention]

The present invention is an optical recording and reproducing device for recording and reproducing information, in which a single galvano mirror deflects a light beam in the radial and tangential directions of the disk during recording and reproducing information signals, thereby reducing the number of parts. In addition, by using a laminated piezoelectric element to drive the galvanomirror, stable operation can be achieved that is resistant to external disturbances.

[Prior art]

FIG. 3 shows a conventional configuration of an optical recording/reproducing device. Third
In the figure, ``■'' is a light source such as a semiconductor laser, and 2 is a condensing lens, which condenses the diverging light of the semiconductor laser and converts it into substantially parallel light. 3 is a beam shape conversion optical system that converts the cross-sectional shape of an incident beam and outputs light having a substantially circular beam cross section.

Note that this optical system may be omitted in an apparatus that only reproduces signals recorded on a disk in advance. 4 is a beam splinter, and 5°6 is a galvano mirror that totally reflects the light beam.

Reference numeral 5 designates a tracking mirror that directs the light beam in the radial direction of the disk in order to track the information track 10 on the disk 9, and reference numeral 6 designates a tangential mirror that directs the light beam in the tangential direction to eliminate temporal fluctuations in the reproduced signal. . The light beam totally reflected by 5 and 6 passes through an objective lens 8 and is focused into a spot of about 1 μm. Reference numeral 7 denotes an objective lens driving device that drives the objective lens 8 so as to focus on a track 10 on the disk 9. The light reflected by the disk 9 is
8, 6.5 again, the optical path is separated by the beam splitter 4, passes through the cylindrical lens 11, and is sent to the photodetector 1.
2. This photodetector 12 detects a focus error signal, a tracking error signal, and an RF multiplied signal.

By the way, the aforementioned five tracking mirrors and the tangential mirror 6 are used as means for deflecting the optical axis in the aforementioned optical system, and these mirrors 5 and 6 are used as means for deflecting the optical axis in the aforementioned optical system.
For example, as shown in FIG. 4, a galvano mirror used as a mirror has magnets 22 fixed near both sides of the back surface of a mirror 21, and a rubber 23 fixed in the center to form a movable part. The coil 25 is attached by means of a metal fitting 24 to a fixed part constituted by a case (not shown) to which the coil 25 is fixed. The coil 25 is wound into a rectangular tube shape that can surround the mirror 210.

When the coil 25 is energized, a force is generated between the magnet 22 and the coil 25, and the mirror 21 swings at an angle corresponding to the current, using the rubber 23 as a fulcrum. In this way, the light incident on the mirror is reflected in the desired direction.

[Problem that the invention seeks to solve]

However, the above-mentioned conventional technology requires two mirrors, a tracking mirror and a tangential mirror, so adjustment of these mirrors is troublesome and the number of parts increases. Since rubber is used as the fulcrum of the movable part, the characteristics of the galvanometer mirror are greatly influenced by the properties of this rubber.Also, since the movable part is supported only by this rubber, it is weak against external vibrations and is stable. It is interfering with normal movement. SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and its purpose is to provide a two-dimensionally driven galvanomirror unit with a hour wheel configuration that solves the above drawbacks, has stable support, and ensures reliable operation. It's about doing.

[Means to solve the problem]

The two-dimensional drive galvano mirror unit of the present invention is used in an optical recording and reproducing apparatus that irradiates a disc-shaped recording medium with a light beam to record and reproduce information. In order to shake the recording medium in the radial direction and eliminate temporal fluctuations in the reproduced signal, a mirror is used to swing the light beam in the tangential direction of the information track, and a laminated piezoelectric element is used to drive this mirror. Features.

[For production]

According to the above configuration of the present invention, since only one mirror is required, optical axis adjustment becomes easy and the number of parts is reduced. Furthermore, since the mirror can be supported by a highly rigid laminated piezoelectric element or metal, it is extremely resistant to external disturbances. Furthermore, since a piezoelectric element is used to drive the mirror, power consumption is also reduced.

〔Example〕 Hereinafter, the present invention will be described with reference to illustrated embodiments.

FIG. 1 is a diagram showing an embodiment of the present invention. In FIG. 1, 21 is a mirror, and four laminated piezoelectric elements 31a to 31d are arranged on the Y-axis and the Y-axis near the circumference of the back surface of this mirror.
is fixed. The other ends of these piezoelectric elements are fixed to the fixing part 32. Then, by applying a voltage to the piezoelectric element 31a so that it expands and applying a voltage so that the piezoelectric element 31b contracts, the mirror 21 becomes Y
rotate around an axis. Furthermore, when a voltage with a polarity opposite to that above is applied to each piezoelectric element, the mirror 21 rotates in the opposite direction. Generally, piezoelectric elements cannot take a large strain on the compression side, so if a large rotation angle is required, apply a bias voltage o to the two piezoelectric elements on the expansion side in advance.
This ■. By applying a voltage with an opposite phase to each piezoelectric element around , the mirror can be rotated around the Y axis in the same way as described above. Next 31c and 31
By performing the same operation as above using d, the mirror 21 can be rotated around the X axis. For example, by aligning the Y-axis with the radial direction of the disk and the Y-axis with the tangential direction of the track, and performing the above operations at the same time, the incident light beam on the mirror 21 can be directed in the radial direction and tangential direction of the disk by the desired angle. It can be deflected.

FIG. 2 shows another embodiment of the invention. Components that are the same as in FIG. 1 are given the same numbers. In Figure 2, 33
As shown in the figure, is a mirror support plate from which a support rod having a notch A at its origin protrudes.

On the Y axis and the positive portion of the Y axis near the circumference, mounting portions B protrude for adhering the laminated piezoelectric elements 31a and 31b. This portion B is also provided with a cutout portion to facilitate rotation of the mirror 21. This support plate is made of highly rigid metal. Now, when a voltage is applied to the piezoelectric element 31a and this element expands and contracts, the mirror 21 rotates around the Y axis. On the other hand, when the piezoelectric element 31b is expanded or contracted,
rotate around an axis. As mentioned above, 2 of 31a and 31b
By using two piezoelectric elements, the light incident on the mirror 21 can be simultaneously deflected in the radial direction of the disk and in the tangential direction of the track.

[Effects of the invention] As mentioned above, if the first misfire occurs, only one mirror is required, so troublesome adjustment between the mirrors is unnecessary, and the number of parts is reduced. Because it is supported by a type piezoelectric element or metal, it is resistant to external disturbances and can operate stably.Furthermore, unlike conventional electromagnetic systems, it requires almost no current, so it also has the effect of reducing power consumption.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view of a galvano mirror according to the present invention, FIG. 1(b) is a side view of the same, and FIG. 2(a) is a plan view of a galvano mirror according to another embodiment of the present invention. , Figure 2 (
b) is a sectional view of the same, FIG. 3 is a schematic diagram of a conventional optical recording/reproducing device, and FIG. 4 is a sectional view of a conventional galvano mirror. 1... Light source 2... Condensing lens 3...
- Beam shape conversion optical system 4... Beam splinter 5... Tracking mirror 6... Tangential mirror 7... Objective lens drive device 8... Objective lens 9... Disk 10...
・Information track 11...Cylindrical lens 12...Photodetector 21...Mirror 22...
・Magnet 23...Rubber 24...Metal fittings 25...Coils 31a to 31d...Laminated piezoelectric element 32...Fixing part 33...Mirror support plate or more 2 toggles 31gu ~ 3JJ... Plan view of Seishichitensobuku 1 Lo 3 Rue--One-fathom type one-electron element %2 figure (12-), 21 Δ4 view of pin-open lever sock, 2 @(b)

Claims (3)

[Claims] (1) In an optical recording and reproducing device that records and reproduces information by irradiating a light beam onto a disc-shaped recording medium, the light beam is swung in the radial direction of the recording medium, and the light beam is directed in the tangential direction of the information track. A galvano mirror unit characterized in that a shaking operation is performed by a mirror, and a laminated piezoelectric element is used to drive the mirror. (2) At least four or more of the laminated piezoelectric elements are fixed on two orthogonal axes around the mirror, and a pair of the laminated piezoelectric elements facing each other across the axes is pushed.
- The galvanometer mirror unit according to claim 1, wherein the mirrors are rotated around their respective axes by being driven using a pull method. (3) A metal plate having two points of force on two axes perpendicular to a fulcrum having a notch in the center is fixed to the back surface of the galvanometer mirror, and at least two or more of the laminated pieces are stacked with the fulcrum as a fixed part. In a structure in which piezoelectric elements are fixed to the two points of force, the mirror is rotated about the two orthogonal axes about the fulcrum by driving the laminated piezoelectric elements to expand and contract. A galvanometer mirror unit according to claim 1.