JP2002116391A - Thin film type optical modulator - Google Patents

Abstract

(57) Abstract: In a thin-film optical modulation device, the tilt angle of a mirror is increased without increasing the element size. The thin-film light modulation device includes an actuator formed with a deformable layer on a support layer, and a light reflecting means (mirror 150) formed on the support layer. The longitudinal direction of the actuator is arranged so as to coincide with the diagonal direction of the light reflecting means. With this arrangement, the length of the actuator can be increased without changing the element size, and therefore, the tilt angle of the mirror 150 formed above the actuator can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin-film light modulator,
More specifically, the present invention relates to a thin-film light modulator using an actuator as a cantilever.

[0002]

2. Description of the Related Art A spatial light modulator (SLM) is a device that modulates incident light to form an optical image corresponding to an electric or optical input, and is an image forming means in a projection display, an electrophotographic print, or the like. There is a use as. S
Light incident on the LM may be modulated in phase, intensity, polarization, or direction. This light modulation is achieved by various materials exhibiting electro-optical or magneto-optical effects, or by materials that modulate light by surface deformation.

An example in which a piezoelectric material is used as an actuator to realize an SLM is disclosed in Japanese Patent Application Laid-Open No. H11-72724. 4 and 5 are plan views of a conventional thin-film light modulator. FIG. 6 is an enlarged perspective view showing the actuator and the mirror of the device shown in FIG. 5, and FIG. 7 is a cross-sectional view of the device shown in FIG. 6 taken along line C1-C2.

Referring to FIGS. 4 to 7, a thin-film light modulator according to a conventional example includes an active matrix 100 and a support layer 1 formed on the active matrix 100.
10, a first actuating section 120 and a second actuating section 130 formed side by side on the support layer 110, and on the first and second actuating sections 120, 130. It comprises a mirror 150 formed and an anchor 160 supporting the support layer 110 on the active matrix 100.

[0005] In the first actuator section 120 of the above-mentioned thin film type light modulation device, an electric field is generated by applying a voltage between the lower electrode 120a and the upper electrode 120c, and the deformed layer 120b is deformed by the electric field. .
Due to the deformation of the deformation layer 120b, the first actuator section 120 including the deformation layer 120b is bent upward at a predetermined angle with the anchor 160 as a fulcrum. This operation is the same for the second actuator section 130. The mirror 150 includes the first and second actuator units 120.
And 130 are formed on the support layer 110 deformed in the same manner as the deformation of
And tilted at the same angle as the second actuator sections 120 and 130. Therefore, the mirror 150 can reflect the light incident from the light source at a predetermined angle.

The light reflected by the thin-film light modulator is projected onto a screen or the like through an aperture. If the tilt angle of the actuator is small, the aperture must be reduced. Efficiency is reduced and the contrast of the projected image is reduced. Further, since the difference in the light reflection angle between black display and white display is small, it is necessary to increase the distance between the thin-film light modulator and the projection optical system, which reduces the degree of freedom in system design. Therefore, it is necessary to increase the tilt angle of the actuator, and three methods of reducing the thickness of the piezoelectric substance, increasing the applied voltage, or increasing the length of the actuator are considered as the methods.

[0007]

However, reducing the thickness of the piezoelectric material has a manufacturing upper limit, and if the applied voltage is too high, the piezoelectric material may be broken. Therefore, it is considered effective to increase the actuator length.
As shown in FIG. 4 and FIG.
Therefore, when the length of the actuator is increased, the element becomes large.

Accordingly, an object of the present invention is to provide a thin film type light modulation device capable of increasing the tilt angle of a mirror without increasing the size of an element.

[0009]

According to the present invention, there is provided an actuator having a deformation layer on a support layer, and a light reflecting means formed on the support layer. And a longitudinal direction of the actuator is arranged so as to coincide with a diagonal direction of the light reflecting means.

In the present invention, the longitudinal direction of the actuator may be arranged non-parallel to the side direction of the light reflecting means.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A thin-film light modulation device according to the present invention will be described with reference to the drawings.

[First Embodiment] FIG. 1 is a plan view of a thin-film light modulator according to a first embodiment of the present invention. In FIG.
111 is a support layer, 122 is an actuating section, 1
Reference numeral 50 denotes a mirror, and reference numeral 160 denotes an anchor. The actuator has a structure in which the longitudinal direction of the actuator constituted by the support layer 111 and the actuating portion 122 matches the diagonal direction of the mirror 150. The support layer 111 is the same as the support layer 110 in FIGS.

With such an arrangement, the length B of the actuating portion 122 in this embodiment is
Actuating sections 120 and 1 in conventional example
It can be about 1.4 times the length A of 30.

In FIG. 1, the post 140 for supporting the mirror 150 is formed on the support layer 111.
If 0 is formed on the actuating portion 122, it can be made longer.

If a desired tilt angle can be obtained, the longitudinal direction of the actuator does not need to be completely coincident with the diagonal direction of the mirror, and the longitudinal direction is not parallel to the direction of one side of the mirror. Just keep it.

Here, assuming that the length of the actuating portion is L and the displacement is δ, the displacement δ of the actuating portion for the same applied voltage is δ = aL as shown in FIG.
^Since the relationship is ² + bL, a larger displacement can be obtained by increasing the length of the actuating portion 122. By the way, since the support layer 111 is displaced according to the actuating portion 122, the mirror 150 formed on the support layer 111 can have a tilt angle synchronized with the displacement of the actuating portion 122.

[Second Embodiment] FIG. 2 is a plan view of a thin-film light modulation device according to a second embodiment. In FIG. 2, 112 and 113 are first and second support layers, respectively.
And 124 are first and second actuating parts respectively, 125 is a connection part, 150 is a mirror, 160
Is an anchor, the first and second supporting layers 112 and 113 and the first and second actuating portions 1
An actuator is constituted by 23 and 124. The first support layer 112, the second support layer 113, and the connection portion 125 are integrally formed on the same plane. First
The support layer 112 and the second support layer 113 of FIGS.
Is the same as that of the support layer 110.

The actuator according to the present embodiment has a structure in which the actuator according to the first embodiment is connected in a U-shape at a connection portion 125, and a mirror 150 is formed above the connection portion 125. The structure in which the longitudinal direction of the actuator matches the diagonal direction of the mirror 150 is the same as in the first embodiment.

In this structure, the actuating section 1
By forming the layers 23 and 124 to the ends of the support layers 112 and 113, the length C can be made longer than the length A of the conventional example by about 1.4 times.

Further, in the first embodiment, since the diagonal line of the mirror 150 and the position of the actuator coincide with each other, depending on the height of the post 140, the apex of the mirror 150 and the actuator supporting the mirror 150 interfere with each other to cause a tilt angle. May be limited, but this can be avoided by removing the position of the actuator from the diagonal line of the mirror 150 as a “U” -shaped structure. Further, by arranging two actuators side by side, the operation can be stabilized.

[Embodiment 3] FIG. 3 is a plan view of a thin-film optical modulator according to Embodiment 3. FIG. 3, the same parts as those in FIG. 2 are denoted by the same reference numerals. The actuator according to the present embodiment has a structure in which a stage 126 is protruded to the inside of a U-shape from the connecting portion 125 of the actuator according to the second embodiment, and the mirror 150 is formed above the stage 126. Further, the first support layer 112, the second support layer 113, the connection portion 125, and the stage portion 126 are integrally formed on the same plane.

The length D of the actuating portion in the present embodiment is the same as the length C of the actuating portion in the second embodiment, but the center position of the mirror 150 is shifted toward the center with respect to the longitudinal direction of the actuator. By doing so, interference between the mirror 150 and the actuator can be further avoided.

Further, in the structure of the second embodiment, since the actuator of the target pixel greatly enters the lower part of the mirror constituting the adjacent pixel (the upper and left pixels in FIG. 2), the tilted actuator and the tilted actuator are used. There is a possibility that the tilt angle is limited due to interference with an adjacent mirror. By setting the center position of the mirror 150 closer to the center with respect to the longitudinal direction of the actuator, it is possible to reduce the penetration of the lower part of the adjacent pixel. Therefore, it is possible to avoid the interference with the adjacent pixels.

[0024]

According to the present invention described above, the structure in which the longitudinal direction of the actuator coincides with the diagonal direction of the mirror makes it possible to increase the length of the actuator without increasing the size of the element. Can be increased.

In the structure of the present invention, since the direction of the mirror has an angle of 45 ° with respect to the side of the mirror, there is an effect that the diffracted light generated along the mirror edge can be minimized.

[Brief description of the drawings]

FIG. 1 is a plan view showing a thin-film light modulation device according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a thin-film light modulation device according to a second embodiment of the present invention.

FIG. 3 is a plan view showing a thin-film light modulation device according to Embodiment 3 of the present invention.

FIG. 4 is a plan view showing a thin-film light modulation device in a conventional example.

FIG. 5 is a plan view showing a thin-film light modulation device in a conventional example.

6 is an enlarged perspective view showing an actuator and a mirror of the thin-film light modulation device shown in FIG. 5;

FIG. 7 is a cross-sectional view of the thin-film light modulator shown in FIG. 6 taken along line C1-C2.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Active matrix 110, 111 Support layer 112 First support layer 113 Second support layer 120, 123 First actuating section 120 a Lower electrode 120 b Deformation layer 120 c Upper electrode 122 Actuating section 124, 130 Second Actuating section 125 Connecting section 126 Stage section 140 Post 150 Mirror 160 Anchor

Claims (6)

[Claims] 1. A thin-film light modulation device comprising: an actuator formed with a deformation layer on a support layer; and light reflecting means formed on the actuator.
A thin-film light modulation device, wherein a longitudinal direction of the actuator is arranged so as to coincide with a diagonal direction of the light reflecting means. 2. A thin-film light modulator comprising: an actuator formed with a deformation layer on a support layer; and light reflecting means formed on the actuator.
A thin-film light modulation device, wherein a longitudinal direction of the actuator is arranged non-parallel to a side direction of the light reflecting means. 3. The actuator according to claim 1, wherein the actuator has a first actuator portion having a deformation layer on a first support layer;
A second actuator portion formed with a deformation layer on the second support layer, the connection portion connecting the first support layer and the second support layer in a U-shape; 3. The thin-film light modulation device according to claim 1, further comprising: a light reflection means disposed above the connection portion. 4. The thin-film optical modulator according to claim 3, wherein the first support layer, the second support layer, and the connection portion are integrally formed on the same plane. 5. The actuator according to claim 1, wherein the actuator has a first actuator portion having a deformation layer on a first support layer;
A second actuator portion formed with a deformation layer on the second support layer, the connection portion connecting the first support layer and the second support layer in a U-shape; A stage formed inside the U-shape from the connection,
4. A thin-film light modulation device according to claim 1, wherein a light reflecting means is arranged above the stage. 6. The thin-film light modulation device according to claim 5, wherein the first support layer, the second support layer, the connection section, and the stage section are integrally formed on the same plane.