JP2001004952A - Optical deflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to deflect light, such as a laser beam, at a high velocity and wide deflection angle. SOLUTION: This optical deflector 10A has a mirror diaphragm 12, which is integrally formed with a planar fixing plate part 12a fixed to a base board 11, a pair of leaf spring parts 12b and 12c which face each other from one end to the other end of this fixing plate part 12a and is bendable and displaceable, a pair of torsional spring parts 12d and 12e which are respectively extended toward between a pair of the leaf spring parts 12b and 12c from the front end sides of a pair of the leaf spring parts 12b and 12c and are torsionally displaceable and a mirror surface part 12 which is suspended to a pair of the torsional spring parts 12d and 12e and of which the surface is finished to a mirror finished surface and a pair of vibration drive sources 13 and 14, which are mounted onto the base board 11 and vibrate the mirror surface part 12 of the mirror diaphragm 12 at the high velocity and the wide deflection angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical deflector which can surely deflect light such as a laser beam at a high speed and a wide deflection angle.

[0002]

2. Description of the Related Art Optical deflection used in scanning devices for optical devices such as laser beam printers and bar code readers, optical deflection mirrors for optical disc tracking control, and display devices for scanning laser beams and projecting images. Although there are various kinds of structural forms for the element (or the optical scanner), recently, a small and light optical deflector manufactured by subjecting a single crystal silicon wafer as a raw material to fine processing by a micromachining technique is used.

[0003] As an example of such a small and lightweight optical deflector, a light deflector similar in shape to the present invention is disclosed in Japanese Patent Application Laid-Open No. H8 (1996).
-240782.

A conventional optical scanner (optical deflector) A shown in FIG. 6 is disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 8-240782, and will be briefly described here.

In the above-described conventional optical scanner A, one end of a bending elastic deformation portion 3a having a bending deformation mode is supported by the vibration input portion 4 in a cantilever shape, and a continuous portion 5 is provided in a cantilever shape on the other end. ing. The vibrator 1 in which the scanning section 6 is supported by the continuous section 5 and the vibration input section 5 by two torsional elastic deformation sections 3b having a torsional deformation mode is integrally formed from a silicon wafer or the like. A vibration surface of the drive source 2 is joined to the vibration input unit 4, and a mirror unit 7 that reflects the light beam r is provided in the scanning unit 6.

When a vibration having a frequency equal to the resonance frequency fB of the bending elastic deformation section 3a is applied from the driving source 2 to the vibration input section 4, the bending elastic deformation section 3a resonates in a bending deformation mode, thereby being continuously provided. The unit 5 and the scanning unit 6 rotate around the axis P. Therefore, when the light beam r emitted from the light source 8 is projected on the mirror unit 7 of the scanning unit 6, the light beam r reflected by the mirror unit 7 is scanned in the illustrated θB direction. When a vibration having a frequency equal to the resonance frequency fT of the torsion elastic deformation portion 3b is applied, the torsion elastic deformation portion 3b resonates in the torsion deformation mode, whereby the scanning unit 6 rotates around the axis Q. Therefore, when the light beam r emitted from the light source 8 is projected on the mirror unit 7 of the scanning unit 6, the light beam r reflected by the mirror unit 7 is scanned in the illustrated θT direction. Further, when the vibration having the frequency equal to the resonance frequency fB of the bending elastic deformation portion 3a and the vibration having the frequency equal to the resonance frequency fT of the torsion elastic deformation portion 3b are simultaneously applied to the vibration input portion 4, the scanning portion 6 causes the axis P and Shaft center Q
And the light beam r emitted from the light source 8 irradiates the mirror unit 7, the light beam r is at an angle twice the rotation angle of the scanning unit 6 in the θB direction and the θT direction. Is scanned two-dimensionally.

[0007]

By the way, in the conventional optical scanner (optical deflector) A shown in FIG. 6, the vibration input section 4 is formed substantially at right angles from one end and the other end of the bending elastic deformation section 3a of the vibrator 1. The scanning section 6 is formed between the vibration input section 4 and the continuous section 5 via two torsionally elastically deforming sections 3b. However, since the vibration surface of the drive source 2 is joined to the vibration input section 4 and the drive section 5 has no drive source, the torsional vibration deformation conditions are different between one and the other of the two torsional elastic deformation sections 3b. Therefore, by superimposing two types of resonance frequencies,
Although the light beam r can be scanned in one dimension, it is difficult to deflect the light beam r at high speed and stably with respect to one-dimensional optical scanning.

Therefore, an optical deflector that can deflect light such as a laser beam at high speed and with a wide deflection angle with a simple structure is desired.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a plate-shaped fixing plate fixed to a base table, and one end and the other end of the fixing plate facing each other. A pair of leaf spring portions that extend and can be bent and displaced, and a pair of torsion that can be displaced and torsionally displaced from the distal ends of the pair of leaf spring portions to between the pair of leaf spring portions. A mirror diaphragm integrally formed with a spring portion, a mirror surface portion suspended on the pair of torsion spring portions and having a mirror-finished surface, and opposed to a pair of leaf spring portions formed on the mirror diaphragm. A pair of a pair attached to the base table, and a pair of vibrating the mirror surface portion by imparting torsional vibration to the pair of torsion spring portions by bending and displacing the distal end sides of the pair of leaf spring portions. An optical deflector characterized by having a vibration drive source That.

Further, in the optical deflector according to the present invention, the resonance frequency of the pair of leaf spring portions formed on the mirror diaphragm is set lower than the resonance frequency of the mirror surface portion. .

Further, in the optical deflector according to the present invention, an electrostatic force is used for the pair of vibration driving sources, or an electromagnetic force is used for the pair of vibration driving sources. An optical deflector, or an optical deflector characterized by using a piezo-stacked actuator using a piezoelectric element for the pair of vibration driving sources, or a piezo bimorph using a piezoelectric element for the pair of vibration driving sources. An optical deflector characterized by being used.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an optical deflector according to the present invention will be described below in detail in the order of <first embodiment> to <fourth embodiment> with reference to FIGS.

<First Embodiment> FIG. 1 is a perspective view showing an optical deflector according to a first embodiment of the present invention, and FIG. 2 explains the operation of the optical deflector according to the first embodiment of the present invention. FIG.

In the optical deflector 10A according to the first embodiment of the present invention shown in FIG.
1a is formed so as to protrude upward, and a flat surface 11b is formed to be one step lower to the right of the support portion 11a. Therefore, the base 11 is formed in a substantially L-shape by the support portion 11a and the flat surface 11b. Further, a concave surface 11c that is concavely formed is formed at the center of the flat surface 11b of the base table 11.

Further, the support portion 11 formed on the base table 11
A plate-like fixed plate portion 12a formed on the mirror diaphragm 12 is fixedly mounted on a.

Here, the mirror diaphragm 12 is integrally formed by forming a pattern of a predetermined shape on the silicon substrate by using a silicon substrate by a micromachine technology and etching the silicon substrate. At this time, since the area of one mirror diaphragm 12 is small, a plurality of mirror diaphragms 12 can be simultaneously formed on the silicon substrate, and the cost of the mirror diaphragm 12 can be reduced.

That is, the above-mentioned mirror diaphragm 12 has a plate-shaped fixed plate portion 12a fixed to the base table 11, and a cantilever substantially perpendicularly opposed from one end and the other end of the fixed plate portion 12a. A pair of leaf spring portions 1 that are extended and can be bent and displaced.
2b, 12c and a pair of torsion spring portions 12d extending substantially perpendicularly from the distal ends of the pair of leaf spring portions 12b, 12c to between the pair of leaf spring portions 12b, 12c and capable of being distorted. , 12e and a pair of torsion springs 1
It is integrally formed with a mirror surface portion 12f suspended on 2d and 12e and having a mirror-finished surface. At this time, the surface of the mirror surface portion 12f is mirror-finished by applying a very thin film of a metal material such as Al or Au so that light such as a laser beam can be reflected.

A pair of fixed electrodes 13 and 14 are mounted on the flat surface 11b of the base 11 as a vibration drive source for vibrating the mirror diaphragm 12 by electrostatic force. The pair of fixed electrodes 13 and 14 are opposed to the pair of leaf springs 12 b and 12 c of the mirror diaphragm 12, and are spaced apart from the pair of leaf springs 12 b and 12 c by a predetermined gap. It is mounted on the surface 11b. A mirror surface portion 12f of the mirror diaphragm 12 faces above a concave surface 11c formed at the center of the flat surface 11b of the base table 11.

The electrode on the other side of the pair of fixed electrodes 13 and 14 is a mirror diaphragm 12, and the pair of fixed electrodes 1
A battery 15 and a switch 16 are connected between the mirror diaphragm 12 and the mirror diaphragm 12, and when the switch 16 is turned on, a voltage is applied between the pair of fixed electrodes 13, 14 and the mirror diaphragm 12. When the switch 16 is turned off, the application of the voltage is cut off, and the switch 16 is periodically turned on.
N, OFF control is performed.

Here, the state shown in FIG. 2A corresponds to a pair of torsion spring portions 12d and 1d formed on the mirror diaphragm 12.
2e shows a state in which the center of gravity of the mirror surface portion 12f matches,
On the other hand, the state shown in FIG. 2B shows a state where the centers of gravity of the pair of torsion spring portions 12d and 12e formed on the mirror diaphragm 12 and the mirror surface portion 12f do not match.

Then, as shown in FIG. 2A, between the pair of fixed electrodes 13 and 14 and the mirror diaphragm 12, in other words, between the pair of fixed electrodes 13 and 14 and the mirror diaphragm 12
When a voltage is applied between the pair of leaf spring portions 12b, 12c formed in the pair, the pair of leaf spring portions 12b, 1
The tip side of 2c is elastically bent and displaced so as to be attracted to the pair of fixed electrodes 13 and 14. On the other hand, when the switch 16 is turned off and the voltage is turned off, the distal ends of the pair of leaf spring portions 12b and 12c formed on the mirror diaphragm 12 return to the original position by the restoring force. Therefore, when a voltage is applied periodically, a pair of leaf spring portions 12b and 12c of the mirror diaphragm 12 are provided.
The tip side elastically bends and displaces vertically (or back and forth) with the fixed plate portion 12a as a fulcrum and vibrates. At this time, the torque generated in the pair of leaf spring portions 12b and 12c is transmitted to the pair of torsion spring portions 12d and 12e, and torsional vibration is applied to the pair of torsion spring portions 12d and 12e by the moment of inertia. The mirror surface portion 12f oscillates right and left in the figure around the pair of torsion spring portions 12d and 12e.

As shown in FIG. 2B, when the center of gravity of the mirror surface 12f formed on the mirror diaphragm 12 is not on the line connecting the pair of torsion spring portions 12d and 12e (the mirror surface 12f is In a case where the mirror is not axially symmetric with respect to the pair of torsion spring portions 12d and 12e), the torque acts more on the center of gravity of the mirror surface portion 12f, and a larger vibration displacement and vibration speed can be obtained.

When the frequency of the electrostatic force due to the periodic voltage application is set near the resonance frequency of the mirror surface portion 12f formed on the mirror diaphragm 12, the mirror surface portion 12f can vibrate at the maximum displacement, and at the same time, a pair of leaf springs can be used. Part 12b, 1
Since the resonance frequency of 2c is set to be lower than the resonance frequency of the mirror surface portion 12f, the amplitude can be made substantially zero. At this time, the electrostatic force is applied to the pair of leaf springs 12b and 12c.
Is inversely proportional to the square of the gap generated between the pair of fixed electrodes 13 and 14, so that the pair of leaf springs 12b and 1
When the amplitude of 2c is small, the gap between the pair of fixed electrodes 13 and 14 can be narrowed, and a larger force can be generated.

When light (not shown) such as a laser beam is applied to the surface of the mirror surface portion 12f while the mirror surface portion 12f formed on the mirror diaphragm 12 is vibrating, the laser beam is reflected on the surface and reflected by the surface. Can be deflected at a wide angle.

<Second Embodiment> FIG. 3 is a perspective view showing an optical deflector according to a second embodiment of the present invention.

In the optical deflector 10B according to the second embodiment of the present invention shown in FIG. 3, the electromagnetic force is used as a vibration driving source for vibrating the mirror diaphragm 12, as described in the first embodiment. It is different only from the example light deflector 10A.

Here, a pair of permanent magnet films 1 are formed on the surfaces of the pair of leaf spring portions 12b and 12c formed on the mirror diaphragm 12.
7 and 18 are formed, and the pair of permanent magnet films 17 and 1 are formed.
A pair of coils 19 and 20 are mounted on the flat surface 11b of the base base 11 substantially below the base 8. Then, a magnetic field is generated by passing a current through the pair of coils 19 and 20 by the AC power supply 21, and the magnetic field generates a magnetic field between the pair of permanent magnet films 17 and 1.
8, the pair of leaf spring portions 12b, 12c are attracted and repelled, and the current direction of the pair of coils 19, 20 is periodically changed to thereby form the pair of leaf spring portions 12b, 12c.
c reciprocates up and down (or back and forth) in the figure, and this vibrates through a pair of torsion springs 12d and 12e.
And the mirror surface portion 12f is twisted and resonated left and right in the drawing, and is driven at high speed and wide displacement.

<Third Embodiment> FIG. 4 is a side view showing an optical deflector according to a third embodiment of the present invention.

In the optical deflector 10C according to the third embodiment of the present invention shown in FIG. 4, a piezoelectric actuator 22 of a piezoelectric element is used as a vibration driving source for vibrating the mirror diaphragm 12. This is different from the light deflectors 10A and 10B of the first and second embodiments described above.

Here, the piezo laminated actuator 22
Is driven by a change in volume in the stacking direction. Therefore, a pair of leaf spring portions 12 b and 12 c formed on the mirror diaphragm 12 and the flat surface 11 b of the base table 11 are fixedly connected. Then, the vertical driving of the piezo multilayer actuator 22 in the stacking direction causes the pair of leaf spring portions 12b and 12c to reciprocate up and down in the drawing, and the pair of torsion spring portions 12d and 1
The mirror surface portion 12f is transmitted to the mirror surface portion 12f via 2e, and the mirror surface portion 12f is twisted and resonated, and is driven at high speed and wide displacement.

<Fourth Embodiment> FIG. 5 is a side view showing an optical deflector according to a fourth embodiment of the present invention.

In the optical deflector 10D according to the fourth embodiment of the present invention shown in FIG. 5, a piezoelectric element piezo bimorph 23 is used as a vibration driving source for vibrating the mirror diaphragm 12.
The only difference from the light deflectors 10A to 10C of the first to third embodiments described above is that the light deflector 24 is used.

Here, on both surfaces of a pair of leaf spring portions 12b and 12c formed on the mirror diaphragm 12, piezoelectric materials 23 and 24 made of PZT or the like are formed.
When a voltage is applied between b and 12c, the piezoelectric material is polarized, and the vibrator bends. When the voltage is periodically changed, the pair of leaf spring portions 12b and 12c reciprocate up and down in the drawing due to the deflection, and the pair of torsion spring portions 12d and 12e.
Is transmitted to the mirror surface portion 12f through the mirror surface portion 12f.
f performs torsional resonance and drives at high speed and wide displacement.

As described in detail above, the first to fourth embodiments of the present invention are described.
Since the light deflectors 10A to 10D of the fourth embodiment have characteristics of high-speed displacement and wide displacement angle, a scanning device of an optical device such as a laser beam printer or a bar code reader,
It can be used as an optical deflecting mirror for tracking control of an optical disc, or a display device that scans light such as a laser beam at a scanning frequency of several tens KHz and projects an image.

[0035]

According to the optical deflector according to the present invention described in detail above, light deflection can be performed at a high speed, and a large light deflection angle can be reliably obtained with a small voltage.
Since there are only two pairs of torsion springs formed on the mirror diaphragm, the structure is simple, there are few places where there is a possibility of fatigue failure, and the reliability is improved. Further, the mirror diaphragm is formed integrally by forming a pattern of a predetermined shape on the silicon substrate and etching it.
Since the area of one mirror diaphragm is small, a plurality of mirror diaphragms can be simultaneously formed on a silicon substrate,
It is also effective in reducing costs.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an optical deflector according to a first embodiment of the present invention.

FIG. 2 is a side view for explaining the operation of the optical deflector of the first embodiment according to the present invention.

FIG. 3 is a perspective view showing an optical deflector according to a second embodiment of the present invention.

FIG. 4 is a side view showing a light deflector according to a third embodiment of the present invention.

FIG. 5 is a side view showing an optical deflector according to a fourth embodiment of the present invention.

FIG. 6 is a perspective view illustrating an example of a conventional light deflector.

[Explanation of symbols]

10A: Optical deflector of the first embodiment, 10B: Optical deflector of the second embodiment, 10C: Optical deflector of the third embodiment, 10D: Optical deflector of the fourth embodiment, 11: Base stand, 11a ... Supporting part, 11b ... Flat surface, 12 ... Mirror diaphragm, 12a ... Fixed plate part, 12b, 12c ... Pair of leaf spring parts, 12d, 1
2e: a pair of torsion springs, 12f: mirror surface, 1
3, 14: A pair of fixed electrodes, 15: Battery, 16: Switch, 17, 18: A pair of permanent magnet films, 19, 20: A pair of coils, 21: AC power supply, 22: Piezo laminated actuator, 23, 24 ... piezo bimorph.

Claims (6)

[Claims] A plate-shaped fixing plate fixed to a base;
A pair of leaf spring portions that extend from one end and the other end of the fixed plate portion so as to be opposed to each other and can be displaced in bending, and respectively from the distal end side of the pair of leaf spring portions to between the pair of leaf spring portions. A mirror diaphragm integrally formed with a pair of torsion spring portions extending and torsionally displaceable, and a mirror surface portion suspended on the pair of torsion spring portions and having a mirror finished surface; A pair of leaf spring portions formed on the plate are attached to the base table in a pair, and the distal ends of the pair of leaf spring portions are bent and displaced to twist the pair of torsion spring portions. An optical deflector comprising: a pair of vibration driving sources for applying vibration to vibrate the mirror surface. 2. The optical deflector according to claim 1, wherein a resonance frequency of a pair of leaf spring portions formed on said mirror diaphragm is set lower than a resonance frequency of said mirror surface portion. . 3. The optical deflector according to claim 1, wherein an electrostatic force is used for said pair of vibration driving sources. 4. The optical deflector according to claim 1, wherein an electromagnetic force is used for said pair of vibration driving sources. 5. The optical deflector according to claim 1, wherein a piezo-stacked actuator using a piezoelectric element is used as the pair of vibration driving sources. 6. The optical deflector according to claim 1, wherein a piezo bimorph using a piezoelectric element is used as said pair of vibration driving sources.