KR960016283B1 - Optical path regulation apparatus by using seramic actuator - Google Patents

Abstract

an active matrix substrate(31) formed in a matrix; a wire pattern(36) applying a voltage to the top of the substrate(31); a signal electrode(32) delivering the voltage applied to the wire pattern; a common grounding electrode(33) grounding in common with the wire pattern; the first and the second transformation part(38,39) polarized by separating the signal electrode and the common grounding electrode; and a reflective surface(34) which sets the optical path by maintaining a certain slope by the expansion and contraction of the actuator, being attached on top of the first and the second transformation part.

Description

Optical path control device using piezoceramic actuator

1 is a cross-sectional view of an optical path control apparatus using a conventional piezoceramic actuator.

2 is a cross-sectional view of an optical path control apparatus using a piezoceramic actuator according to an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

10,30: optical path control device 11,31: active matrix substrate

13,36: conducting wire pattern 14,37: actuator

15,38: first deformation part 17,39: second deformation part

19,32: signal electrode 21,33: common ground electrode

23, 34: reflector 35: displacement transmission unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical path control apparatus using an actuator. In particular, a piezoelectric ceramic actuator for controlling an optical path by using a height difference of a piezoelectric ceramic actuator attached to a reflector to light incident from a light source for a projection image display device is used. It relates to an optical path control device using an actuator).

An image display apparatus is classified into a direct view type image display apparatus and a projection type image display apparatus according to a display method. The direct view type image display device includes a cathode ray tube (hereinafter referred to as a CRT). Such a CRT image display device has a relatively good image quality, but there is a problem of an increase in weight, thickness, and price as the screen is enlarged. There is a limit to implementing a large screen. Projection type image display apparatuses include a large screen liquid crystal display (hereinafter referred to as an LCD), and such large screen LCDs can be thinned to reduce weight. However, such LCDs have a high loss of light due to the polarizing plate, and thin film transistors for driving the LCD are formed for each pixel, so that there is a limit in increasing the aperture ratio (light transmission area).

In order to make up for the shortcomings of LCDs, a projection type image display apparatus using Actuated Mirror Arrays (hereinafter referred to as AMA) has been developed by Aura, USA. A projection image display apparatus using AMA separates white light emitted from a light source into red, green, and blue light beams, and then reflects these color lights to reflectors inclined by the deformation of actuators, respectively. paths, and the amount of light beams are adjusted and projected onto the screen to realize an image. The AMA is classified into a one-dimensional AMA having an actuator of M × 1 and a two-dimensional AMA having an M × N according to the driving method. Such an actuator includes a deformable portion and electrodes made of a piezoelectric material, and deforms when an electric field is generated to tilt the mirror on the top.

1 is a cross-sectional view of an optical path control apparatus using a conventional piezoelectric ceramic actuator.

The optical path control device 10 includes an active matrix substrate 11, an actuator 14, and a reflector 23. The substrate 11 is made of an insulating material, such as glass or alumina (Al ₂ O ₃ ), on which a thin film transistor (not shown) and a conductive pattern 13 in a matrix form are formed. In addition, the substrate 11 may be formed of a single crystal silicon wafer in which a transistor is built in each pixel and a matrix-shaped lead pattern is formed on a surface thereof. The actuator 14 consists of first and second deformations 15, 17, signal electrodes and common electrodes 19, 21. In the above description, the first and second deformation parts 15 and 17 are formed in an “L” shape, and the whole is mounted on the substrate 11 in a block shape. In addition, the common electrodes 21 are formed on the surface of the first and second deformation parts 15 and 17 facing the signal electrode 19. The first and second deformation parts 15 and 17 are polarized in one direction perpendicular to the signal electrode 19. The signal electrode 19 is connected to the lead pattern 13, and the common electrode 19 is connected to the common electrodes of adjacent optical path control devices by an external lead pattern (not shown).

In addition, the signal and the common electrodes 129 and 21 are formed of a conductive material such as metal, and a predetermined voltage is applied to deform the first and second deformation parts 15 and 17. For example, when a signal voltage is applied to the signal electrode 19 in a state in which the first deformation unit 15 is polarized in the direction (→) of the second deformation unit 17, the polarization direction and the electric field direction are the first deformation unit ( 15), but not in the second deformable portion 17. Accordingly, the first deformable portion 15 contracts in the horizontal direction and expands in the vertical direction, and the second deformable portion 17 expands in the horizontal direction and contracts in the vertical direction. Accordingly, the reflector 123 is inclined toward the second deformable portion 17 from the first deformable portion 15 to form a predetermined inclination angle. The inclination angle is proportional to the height of the first and second deformation parts 15 and 17, that is, the distance between the lower portion of the reflector 23 on the substrate 11 and inversely proportional to the thickness square thereof. Therefore, in order to increase the inclination angle of the reflector to widen the optical path control range, the thickness of the upper part of the first and second deformation parts 15 and 17 must be reduced or increased.

The optical path adjusting device described above is stacked in a plurality of layers in which a metal conductive film for forming a signal electrode, a piezoelectric ceramic, and the like are alternated, polarized in one direction, cut perpendicular to the stacking direction, and mounted on the substrate 11. After the piezoelectric ceramics between the metal conductive films, the thickness and length of the upper portions of the first and second deformed portions 15 and 17 are defined by a mechanical cutting process such as sawing, and the first and second portions are formed by sputtering or the like. The common electrodes 21 are formed on the outer surfaces of the bimodal portions 15 and 17 to form M × N actuators, and the reflectors are attached to the upper surfaces of the actuators.

However, in the above-described conventional optical path control device, the upper surface of the actuator on which the reflector is located is inclined due to the bending of the actuator, so that a large stress is concentrated on the signal electrode layer, and thus it is difficult to expect a long lifetime. In order to uniformly manufacture the N actuator arrays, there is a problem in that the flatness of the internal electrode layer of the multilayer ceramic and the thickness tolerance of the ceramic layer are very strict, resulting in a decrease in productivity.

Therefore, the object of the present invention is to not extend the life of the inner electrode layer by using only the displacement of the contraction and expansion without using the bending displacement of the actuator, so that the life can be extended, and a predetermined empty space is formed between the inner electrode and the outer electrode. The present invention also provides an optical path control apparatus using a piezoceramic actuator that improves productivity by solving a problem of flatness and uniformity of an internal electrode layer by repatterning damaged internal electrodes.

According to the present invention, there is provided an apparatus for adjusting an optical path by a voltage, comprising: an active matrix substrate having a signal electrode terminal formed on a surface thereof and having a transistor built into each pixel therein; A conductive wire pattern for applying a voltage to the upper portion of the substrate; An actuator horizontally attached to the substrate on the substrate and expanding and contracting by a voltage applied to the conductive pattern; It is attached to the upper portion of the actuator includes a reflector for setting the optical path to maintain a predetermined inclination angle by the expansion and contraction of the actuator.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view of an optical path control apparatus using a piezoelectric ceramic actuator according to an embodiment of the present invention.

The optical path control device 30 includes an active matrix substrate 31, an actuator 37, a displacement transfer unit 35, and a reflector 34. The substrate 31 is made of an insulating material, such as glass or alumina, on which a conductive pattern 36 in matrix form is formed. In addition, the substrate 31 may be formed of a single crystal silicon wafer in which a transistor is built in each pixel and a matrix-shaped lead pattern is formed on a surface thereof. The actuator 37 is composed of first and second deformable portions 38 and 39, signals and common electrodes 32 and 33. First and second deformation parts 38 and 39 are formed on the substrate 31 and are spaced apart by a predetermined distance T in the horizontal direction and are polarized in the x direction. In addition, the first and second deformable parts 38 and 39 may be formed of piezoelectric ceramics, and the displacement transmission part 35 may be formed in a minimum bondable area thereon. The displacement transmission part 35 is formed between the first and second deformation parts 38 and 39 and the reflector 34 so that the reflector 34 is gentle or steep in the clockwise or counterclockwise direction and according to the intensity of the electric field. It is formed of a soft epoxy or the like so as to be rotatable. The signal electrode 32 is a place where a signal for driving the actuator 37 is applied, and is formed of a soft metal having good stretching force such as silver (Ag). The common electrode 33 is formed of the same material as the signal electrode 33 to apply the bias voltage or ground the actuator 37.

The operation and effects of the present invention configured as described above will be described in more detail.

First, it is assumed that the first and second deformation parts are polarized in the + x direction, and a positive voltage is applied to the conductive line pattern 36 and a ground (GND) voltage is applied to the common electrode 33. The portion 38 has an electric field in a direction opposite to the polarization direction, the second deformed portion 39 has an electric field formed in the same direction, and the first deformed portion 38 contracts in the x-axis direction and the y-axis direction. Will expand. The second deformation portion 39 expands in the x-axis direction and contracts in the y-axis direction. At this time, the displacement in the x-axis direction is very fine compared to the displacement in the y-axis direction and can be ignored. Therefore, a difference in height between the upper portions of both sides of the first deformation portion 38 and the second deformation portion 39 and the substrate 31 occurs. do.

Accordingly, in accordance with the occurrence of the height difference, that is, the height difference between the first deformation portion 38 and the second deformation portion 39, the displacement transmission unit 35 bonded to the actuator 37 and the reflector 34 is Tilt the reflector 34 clockwise.

On the other hand, when the voltage applied to the conductive line pattern 36 is a negative voltage (-), the shrinkage and expansion directions of the first and second deformable portions 38 and 39 are opposite to the case described above, the reflector 34 ) Incline counterclockwise. In addition, since the magnitude of the displacement of the piezoelectric ceramic forming the actuator 37 can be adjusted according to the intensity of the applied electric field, the rotation angle of the reflector 34 can be flexibly adjusted by adjusting the intensity of the voltage applied to the signal electrode terminal. Various adjustments are possible. Furthermore, by setting a predetermined interval between the first and second deformations 38 and 39, the stress concentrated on the internal electrodes can be coped with in the conventional technique.

As described above, the present invention has a very small stress on the signal electrode layer by using only the contraction and expansion range without using the whip range on the actuator by forming a predetermined gap between the first and second deformable portions as described above. The life of the actuator can be extended, and productivity is improved by simultaneously forming the inner electrode layer and the outer electrode layer without forming the stacked inner electrode before the outer electrode layer.

Claims (3)

An apparatus for adjusting an optical path by voltage, comprising: an active matrix substrate (31) formed of a matrix; A conductive wire pattern 36 for applying a voltage on the substrate 31; A signal electrode 32 transferring a voltage applied to the conductive pattern 36; A common ground electrode 33 which is commonly grounded with respect to the conductive pattern 36; First and second deformation parts (38) (39) by polarizing at a predetermined interval between the signal electrode (32) and the common ground (33); Optical paths using piezoelectric ceramic actuators attached to upper portions of the first and second deformable parts 38 and 39 and including reflectors 34 that maintain a predetermined inclination angle by the expansion and contraction of the actuator to set the optical path. Regulator. The displacement according to claim 1 or 2, wherein the displacement due to expansion and contraction between the first and second deformation parts 38 and 39 is transmitted to the reflector 34 so that the reflector 34 is inclined. Optical path control device further comprising a transmission unit (35). The optical path control device according to claim 3, wherein the displacement transmission part 35 is made of soft epoxy or the like.