JP2009042357A - Optical reflection element and image projection apparatus using the same - Google Patents

Abstract

An object of the present invention is to reduce distortion of an image to be projected.
To achieve this object, according to the present invention, a mirror 7 has one end in the X-axis direction as a fixed end 8 connected to a first vibrating portion 9 and the other end free. In addition to the end 14, the free end 14 has a wing portion 15 that protrudes outward toward the opposing first vibrating portion 9 and folds back toward the fixed end 8. As a result, the present invention compensates for the influence of the optical reflection angle due to the optical reflection portion of the mirror portion at the tip portion of the mirror 7 on the free end 14 side, can suppress the deflection, and reduce the distortion of the projected image.
[Selection] Figure 1

Description

  The present invention relates to an optical reflection element used in an image projection apparatus such as a projector, and an image projection apparatus using the same.

  As shown in FIG. 8, the conventional optical reflecting element includes a mirror 1 tilted in the X-axis and Y-axis directions, and two pairs of first mirrors connected to the mirror 1 and opposed in the Y-axis direction via the mirror 1. The vibrating part 2 is connected to the first vibrating part 2, and the movable frame 3 surrounding the first vibrating part 2 and the mirror is connected to the movable frame 3. Two pairs of second vibrating parts 4 and a support frame 3A connected to these second vibrating parts 4 and surrounding these second vibrating parts 4 and the movable frame 3, wherein the first vibrating part 2 Vibrating in the X-axis direction, the second vibrating unit 4 vibrates in the Y-axis direction.

  The mirror has one end in the X-axis direction as a fixed end 5 connected to the first vibrating portion 2 and the other end as a free end 6.

  In the above configuration, the mirror 1 tilts in the X-axis direction and vibrates in conjunction with the vibration of the first vibration unit 2. In conjunction with the vibration of the second vibration unit 4, the mirror 1 together with the movable frame 3 tilts and vibrates in the Y-axis direction.

  An image can be projected onto a wall or a screen by making light incident on the mirror 1 and scanning the reflected light in the X-axis and Y-axis directions by the vibration of the mirror 1.

As prior art document information similar to this application, for example, Patent Document 1 is known.
JP 2005-148459 A

  In the conventional optical reflecting element, the projected image may be distorted.

  The reason is that when the mirror 1 vibrates, the free end 6 side is greatly bent.

  Therefore, the reflecting surface of the mirror 1 is curved toward the free end 6 side away from the fixed end 5. As a result, image distortion increases.

  Therefore, an object of the present invention is to reduce distortion of an image to be projected.

  And in order to achieve this object, the present invention uses either one end of the mirror in the X-axis direction as a fixed end connected to the first drive unit, and the other end of the mirror as a free end, The free end has a wing portion that protrudes outward toward the opposing first vibrating portion and folds back toward the fixed end.

  Thereby, the present invention can reduce distortion of an image to be projected.

  The reason for this is that the deflection on the free end side of the mirror can be suppressed.

  That is, in the present invention, since the above-described wing portion bends starting from the free end of the mirror, it is considered that a reaction force opposite to the vibration of the mirror body is applied to the free end.

  Therefore, it is possible to suppress the deflection on the free end side, and as a result, it is possible to reduce distortion of the projected image.

(Embodiment 1)
As shown in FIG. 1, the optical reflecting element in the present embodiment is connected to a mirror 7 inclined in the X-axis and Y-axis directions, and an end portion (fixed end 8) of the mirror 7. Two pairs of first vibrating portions 9 facing in the Y-axis direction, and a movable frame 10 connected to the end portions of these first vibrating portions 9 and surrounding the outer periphery of these first vibrating portions 9 and the mirror 7, Connected to the movable frame 10 and connected to the two pairs of second vibrating portions 11 opposed to each other in the X-axis direction via the movable frame 10 and the ends of the second vibrating portions 11, these second vibrating portions 11 and a support frame 12 surrounding the outer periphery of the movable frame 10. A connecting portion is provided between each of the mirror 7 and the first vibrating portion 9, the first vibrating portion 9 and the movable frame 10, the movable frame 10 and the second vibrating portion 11, and the second vibrating portion 11 and the support frame 12. Excluding grooves 13 are formed and separated from each other.

  In the present embodiment, the first vibration unit 9 has a meandering shape that meanders in the X-axis direction, and vibrates in the X-axis direction. The second vibrating portion 11 has a meandering shape that meanders in the Y-axis direction, and vibrates in the Y-axis direction.

  Further, the first vibrating portion 9 and the second vibrating portion 11 of the present embodiment both have a meandering shape having portions facing in parallel, and these portions facing in parallel are formed of piezoelectric elements.

  These parallel facing portions vibrate with their phases shifted by 180 degrees from the adjacent portions.

  Further, the mirror 7 has a substantially rectangular shape, and either one end in the X-axis direction, that is, in this embodiment, the right side in FIG. The other end (the left side) is the free end 14.

  At both ends of the free end 14, there are wings 15 that protrude outwardly toward the adjacent first vibrating portions 9 and turn back 90 degrees toward the fixed end 8.

Here, as shown in FIG. 2 which is an enlarged view of the P part of FIG. 1, the length l _h of the wing part 15 in the X-axis direction is parallel to the length l _m of the mirror 7 body in the X-axis direction, that is, the X-axis. preferably such side quarter is more than one third of the following, in this embodiment was approximately one third of the length l _m of the mirror 7. The reason will be described later.

  As shown in FIG. 3 which is an enlarged view of the Q part in FIG. 1, two upper electrodes 16A and 16B are drawn around the surface of the second vibrating part 11, and the second vibrating part 11 meanders in parallel. In the part opposite to the upper part, the widths of the upper electrodes 16A and 16B are alternately increased or decreased for each adjacent part. As a result, it is possible to apply a voltage of the same polarity to every other part facing in parallel, equalize the phase in the vibration direction every other part, and the center part of the beam to be stationary (shown in FIG. 5). A fixed point 26) can be formed.

  Although not shown in FIG. 3, the upper electrode 17 shown in FIG. 4 is routed between the upper electrodes 16A and 16B, and the first vibrating portion is driven by the upper electrode 17.

  And the part which this 2nd vibration part 11 opposes in parallel is shown in FIG. 4 which is XX sectional drawing of FIG. 3, making the common silicon substrate 18 into the lowermost surface, and the silicon | silicone arrange | positioned on this silicon substrate 18 An oxide film 19, a lower electrode 20 provided in common on the silicon oxide film 19, a piezoelectric layer 21 provided in common on the lower electrode 20, and three electrodes provided in common on the piezoelectric layer 21 The upper electrodes 16A, 16B and 17 are electrically connected to the external electrodes 22 and 23, the lower electrode 20 is electrically connected to the external electrode 24, and the upper electrode 17 is electrically connected to the external electrode 25A. Has been.

In the present embodiment, the composition of the lower electrode 20 is platinum, the upper electrodes 16A, 16B, and 17 are gold, and the piezoelectric layer 21 is lead zirconate titanate (Pb (Zr _x , Ti _1-x ) O ₃ , x = 0.525), and these can be thinned by vapor deposition, sol-gel, CVD, sputtering, or the like.

  Similarly, the first vibrating portion 9 shown in FIG. 1 is also formed of a piezoelectric element. On the first vibration part 9, upper electrodes (17 in FIG. 4) respectively routed from the left and right second vibration parts 11 are arranged. That is, two upper electrodes are routed on the first vibrating portion 9, and the widths of these two upper electrodes are alternately changed at portions where the first vibrating portion 9 meanders and is adjacent in parallel. The upper electrode was configured to be connected to the external electrodes 25A and 25B, respectively.

  Next, the operation principle of the optical reflecting element in the present embodiment will be described.

  First, an AC voltage is applied to each of the external electrodes 22 and 23 shown in FIG. 1 with a phase shifted by 180 degrees, and the external electrode 24 is grounded.

  Thereby, at a certain point, for example, a positive potential is applied to the upper electrode 16A shown in FIG. 3, while a negative potential is applied to the upper electrode 16B, and the lower electrode (20 in FIG. 4) is grounded. Become.

  Therefore, voltages in directions opposite to each other are applied to the piezoelectric layer 21 in the portion adjacent to the second vibrating portion 11 shown in FIG. 4 in parallel.

  Here, since the bending direction of the piezoelectric layer 21 is changed depending on whether the applied voltage is positive or negative, the adjacent portion of the second vibrating portion 11 is shown in FIG. 5 (a side view parallel to the Y axis in FIG. 1). Thus, a fixed point 26 can be formed at the center of each other. The fixed point 26 is distorted in the opposite direction, and the displacement (tilt) in the Y-axis direction from the support frame 12 toward the movable frame 10 is Accumulate. The movable frame 10 is greatly inclined, and the mirror (7 in FIG. 1) is inclined with this inclination.

  Since an AC voltage is applied to the second vibrating portion 11, the portions adjacent in parallel to each other vibrate with a phase shifted by 180 degrees, and the movable frame 10 is vibrated by this vibration. The mirror 7 vibrates in the Y-axis direction in conjunction with.

  In the present embodiment, the first vibrating section 9 shown in FIG. 1 similarly applies reverse voltages to the external electrodes 25A and 25B, thereby reversing the bending direction of the adjacent parts in parallel. The displacement in the X-axis direction accumulates from the movable frame 10 toward the mirror 7. That is, the mirror 7 is largely inclined in the X axis direction with the fixed end 8 as a fulcrum. Then, by changing the polarity of the applied voltage, adjacent portions of the first vibrating section 9 vibrate with a phase shifted by 180 degrees, and the mirror 7 vibrates greatly in the X-axis direction with the fixed end 8 as a fulcrum.

  6, laser light (incident light 29) is incident on the mirror 7 from the laser light source 27, and the reflected light 30 is scanned in the X-axis and Y-axis directions by the vibration of the mirror 7. By doing so, an image can be projected onto the screen 28 or the wall.

  Here, the effect in this Embodiment is demonstrated.

  In this embodiment, distortion of an image to be projected can be reduced.

  That is, as shown in FIG. 1, the mirror 7 has a cantilever-like structure in which one end portion (fixed end 8) is fixed to the first vibrating portion 9. Therefore, when the mirror 7 vibrates in the X-axis direction, the deflection becomes larger toward the free end 14 side.

  Conventionally, as shown in FIG. 9, the surface of the mirror 1 on the fixed end 5 side is relatively straight, whereas the surface is curved toward the free end 6, and the fixed end 5 and the free end 6 are curved. The incident angle and reflection angle of light differed between the images, and the projected image was distorted.

  On the other hand, in the present embodiment, as shown in FIG. 1, since the wing portion 15 shown in FIG. 1 is provided at the free end 14 of the mirror 7, the deflection on the free end 14 side can be suppressed.

  The reason is considered that this wing portion 15 bends starting from the free end 14 of the mirror 7 and applies a reaction force opposite to vibration to the free end 14.

  That is, for example, as shown in the side view of the mirror 7 in FIG. 7, when the free end 14 of the mirror 7 is bent downward (arrow 31), the vibration propagated to the free end 14 is reflected in the same phase. The tip 15A of the wing 15 is also bent downward (arrow 32), and it is considered that an upward reaction force (arrow 33) is applied to the free end 14 of the mirror 7 which is the starting point of this bending vibration.

  In this way, in the present embodiment, the deflection on the free end 14 side can be suppressed, and the distortion of the projected image can be reduced as a result by correcting the curvature on the free end 14 side of the mirror 7.

  In the present embodiment, the curvature of the mirror 7 can be corrected and the mirror 7 can be vibrated while maintaining a flat surface. As a result, the effective area of the mirror 7 can be increased, contributing to the miniaturization of the optical reflecting element. .

  When the mirror 7 is vibrated as in the present embodiment, the amplitude increases and the displacement can be increased as the thickness of the mirror 7 is reduced. On the other hand, however, the thinner the mirror 7, the greater the deflection on the free end 14 side and the greater the image distortion. Therefore, suppressing the bending of the free end 14 by providing the wing portion 15 as in the present embodiment can result in the mirror 7 being thinned, and an image can be projected with high accuracy.

In the present embodiment, as shown in FIG. 2, the length l _h of the wing portion 15 in the X-axis direction is set to about one third of the length l _m of the mirror 7 in the X-axis direction. The bending at the free end 14 of the mirror 7 can be suppressed efficiently.

  That is, for example, when the mirror 7 is inclined downward, the free end 14 side is greatly curved and hangs downward. Therefore, it is effective to intensively correct this curved portion and make the entire mirror 7 flat.

In order to intensively correct the curved portion of the mirror 7 in this way, when the mirror 7 is tilted downward, the mirror 7 is bent downward from the fixed end 8 toward the center and from the center toward the free end 14. It is necessary to apply stress to the mirror 7 so as to draw an S-shaped curve that warps upward. The portion warp above the S-shaped curve corresponds to a quarter of the mirror 7 length l _m.

In addition to the above aspects, in consideration of the length lr of the connecting portion (integral part) of the free end 14 and a wing portion 15 of the mirror 7, the length l _h of the hub 15 is quarter of the mirror 7 length l _m One to one third is the best result.

(Embodiment 2)
The difference between the present embodiment and the first embodiment is that the wing portion 15 is formed of a piezoelectric element.

  That is, in the present embodiment, a piezoelectric layer (not shown) sandwiched between an upper electrode (not shown) and a lower electrode (not shown) is disposed on the upper surface of the wing 15, and the wing 15 has a mirror 7 is applied with a voltage that undergoes primary resonance in the same phase as that of FIG.

  Accordingly, in the present embodiment, by applying vibrations having a desired phase and frequency to the wings 15, it is possible to efficiently suppress the deflection at the free end 14 of the mirror 7, and as a result, to reduce image distortion to be projected. can do.

  Since other configurations and effects are the same as those of the first embodiment, the description thereof is omitted.

  The optical reflecting element of the present invention can reduce distortion of an image to be projected and can be downsized. Therefore, the optical reflecting element is useful in various image projection apparatuses such as a high-precision small projector.

The perspective view of the optical reflective element in one embodiment of this invention Part P enlarged perspective view of FIG. Q part enlarged perspective view of FIG. XX sectional view of FIG. Side view of optical reflecting element parallel to Y-axis of FIG. The perspective view which shows the principle of operation of the image projector in one embodiment of this invention Part P enlarged side view of FIG. A perspective view of a conventional optical reflecting element The principal part expansion perspective view of the conventional optical reflective element

Explanation of symbols

7 Mirror 8 Fixed End 9 First Vibrating Part 10 Movable Frame 11 Second Vibrating Part 12 Support Frame 13 Groove 14 Free End 15 Wing Part 15A Tip 16A Upper Electrode 16B Upper Electrode 17 Upper Electrode 18 Silicon Substrate 19 Silicon Oxide Film 20 Lower Electrode 21 Piezoelectric layer 22 External electrode 23 External electrode 24 External electrode 25A External electrode 25B External electrode 26 Fixed point 27 Laser light source 28 Screen 29 Incident light 30 Reflected light 31 Arrow 32 Arrow 33 Arrow

Claims (6)

A mirror tilting in the X-axis and Y-axis directions;
Two pairs of first vibration parts coupled to the mirror and facing each other in the Y-axis direction via the mirror;
A movable frame connected to these first vibrating parts, and surrounding these first vibrating parts and the mirror,
Two pairs of second vibrating parts connected to the movable frame and opposed in the X-axis direction via the movable frame;
These second vibration parts are connected, and these second vibration parts and a support frame surrounding the movable frame are provided,
The first vibration part vibrates in the X-axis direction,
The second vibration part vibrates in the Y-axis direction,
The mirror is
Either one of the end portions in the X-axis direction is a fixed end connected to the first vibrating portion, the other end portion is a free end,
An optical reflection element in which a wing portion that protrudes outward toward the first vibrating portion side and is folded back toward the fixed end side is disposed at both end portions of the free end. The first vibration part has a meandering shape meandering in the X-axis direction,
The optical reflection element according to claim 1, wherein the second vibrating portion has a meandering shape that meanders in the Y-axis direction. The first and second vibrating parts are
Both meandering shapes having parallel opposing portions,
3. The optical reflecting element according to claim 1, wherein each of the parallel opposing portions is formed of a piezoelectric element and vibrates with a phase shifted by 180 degrees from an adjacent portion. The length of the wing in the X-axis direction is
The optical reflective element according to any one of claims 1 to 3, wherein the length of the mirror in the X-axis direction is not less than one quarter and not more than one third. The wing is formed of a piezoelectric element,
The optical reflection element according to any one of claims 1 to 4, wherein a voltage that primarily resonates in the same phase as the mirror is applied to the wing portion. An optical reflecting element according to any one of claims 1 to 5,
An image projection apparatus comprising: a light source that causes light to enter the mirror of the optical reflection element.

Images