Electrostrictive actuated mirror array

• US 5,585,956 A
• Filed: 07/29/1994
• Issued: 12/17/1996
• Est. Priority Date: 07/31/1993
• Status: Expired due to Fees

• Current Assignee: Daewoo Electronics (Government of South Korea)
• Original Assignee: Daewoo Electronics (Government of South Korea)
• Inventors: Kim, Myoung-Jin, Lee, Seok-Won
• Primary Examiner(s): Shafer, Ricky D.
• Application Number:
  US08/282,943
• Time in Patent Office: 872 Days
• Field of Search: 359/223, 359/224, 359/225, 359/846, 359/847, 359/848, 359/850, 359/291, 359/295, 359/849, 359/855, 359/900, 310/328, 310/366, 29/25.35
• US Class Current: 359/224.1
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means
• CPC Class Codes: H04R 17/08 signals being recorded or played back by vibration of a stylus in two orthogonal directions simultaneously
• CPC Class Codes: Y10S 359/90 Methods
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

An array of M ×N electrostrictive actuated mirrors for use in an optical projection system manufactured using the inventive method, comprising: an active matrix including a substrate and an array of M×N connecting terminals thereon; an array of M×N electrostrictive actuators, wherein each of the actuators includes an electrostrictive member having a top and a bottom surfaces, the top surface being separated by a trench thereby creating first top surface and a second top surface, a first electrode located on the bottom surface, a pair of second electrodes, each of the of second electrodes placed on the first and second top surfaces, respectively, and a pair of insulating layers, each covering the first and second top surface, respectively, including the second electrode placed thereon; an array of M×N hinges, wherein each of the M×N hinges is provided with a flat top surface and a bottom surface having a protrusion mounted on the top of each actuators; an array of M×N connecting terminals, wherein each of the connecting terminals is used for electrically connecting each of the first electrodes with the active matrix; and an array of M×N mirrors, wherein each of the M×N mirrors is mounted on the top surface of each of the M×N hinges.

Claims

1. A method for manufacturing an array of M×

N electrostrictive actuated mirrors for use in an optical projection system, wherein M and N are integers, M indicating the total number of columns in the array, running parallel to the vertical direction and N indicating the total number of rows therein, running parallel to the horizontal direction, the method comprising the steps of;

(a) preparing a ceramic wafer, made of an electrostrictive material, having a top and a bottom surfaces;

(b) forming an array of M×

N regularly spaced, identically sized first electrodes on the bottom surface of said ceramic wafer and a set of 2×

(M+1) identically sized second electrodes on the top surface thereof, wherein each of the 2×

(M+1) second electrodes, having a pair of side edges running parallel to each other and to the vertical direction, extends vertically across the top surface, and each of the M×

N first electrodes, when projected onto the top surface, includes two adjacent second electrodes and the centerline thereof coincides with the centerline therebetween;

(c) mounting said ceramic wafer treated in accordance with said step (b) on an active matrix, including a substrate and an array of M×

N connecting terminals to thereby connect each of the first electrodes with each of the M×

N connecting terminals;

(d) covering the top surface of said ceramic wafer, including the 2×

(M+1) second electrodes, treated in accordance with said steps (b) and (c) with an insulating layer;

(e) providing a set of (M+1) photoresistive necked segments on top of the insulating layer covering the top surface of said ceramic wafer, including the 2×

(M+1) second electrodes, each of the photoresistive necked segments, extending in the vertical direction, is placed on a portion of the insulating layer covering a pair of second electrode, wherein the pair of second electrodes, when projected onto the bottom surface, is made up of two neighboring second electrodes from two horizontally adjacent first electrodes;

(f) forming a set of M trenches, wherein each of the M trenches, provided with a pair of side surfaces and a bottom surface, is located between two adjacent second electrodes, the centerline thereof coinciding with the centerline of each of the first electrodes on the same column and the centerline between the two adjacent second electrodes, runs parallel to the second electrodes, and is further provided with a set of N-1 grooves, running perpendicular thereto;

(g) removing the photoresistive necked segments;

(h) placing an array of M×

N hinges on the top surface of said ceramic wafer treated in accordance with said steps (b), (c), (d), (e), (f) and (g), wherein each of the M×

N hinges is provided with a top surface and a bottom surface provided with a protrusion mounted simultaneously on the insulating layers covering the two adjacent second electrodes separated by a trench therebetween;

(i) forming a mirror on the top surface of each of the M×

N hinges; and

(j) making appropriate electrical connections to thereby form an array of M×

N electrodisplacive actuated mirrors.

2. The method of claim 1, wherein the M×

N first electrodes and the 2×

(M+1) second electrodes are formed by first sputtering the top and bottom surfaces of said ceramic wafer with a conductive metallization, and then obtaining the required electrode pattern using a photolithography method.

3. The method of claim 1, wherein the set of M trenches and the set of N-1 grooves formed on each trenches are obtained using an etching method.

4. The method of claim 1, wherein the mirror is formed on the top surface of each of the M×

N hinges by sputtering a light reflecting material thereon.

5. An array of M×

N electrostrictive actuated mirrors for use in an optical projection system, wherein M and N are integers, M indicating the total number of columns in the array, running parallel to the vertical direction, and N indicating the total number of rows in the array, running parallel to the horizontal direction, respectively, comprising;

an active matrix including a substrate, and an array of M×

N connecting terminals thereon;

an array of M×

N electrostrictive actuators, wherein each of the M×

N electrostrictive actuators includes an electrostrictive member having a top and a bottom surfaces, a first electrode, a pair of second electrodes, each of the second electrode having a pair of side edges running parallel to each other and to the vertical direction, and a pair of insulating layers, the top surface of the electrostrictive member being evenly separated by a trench having a pair of side surfaces and a bottom surface formed thereon and running vertically across the top surface, thereby creating a first actuating member having a first top surface and a second actuating member having a second top surface, the first electrode being located on the bottom surface thereof, each of the second electrodes being located on and partially covering the first top surface and the second top surface, with one of the side edges thereof coinciding with the side surface of the trench, and each of the pair of insulating layers covering the first and second top surfaces of the actuating members, including the second electrode placed thereon;

an array of M×

N hinges, wherein each of the M×

N hinges is provided with a flat top surface and a bottom surface having a protrusion mounted on the top of each of the M×

N electrodisplacive actuators;

an array of M×

N connecting terminals, wherein each of the connecting terminals is used for electrically connecting each of the first electrodes with the active matrix; and

an array of M×

N mirrors, wherein each of the M×

N, mirrors is mounted on the top surface of each of the M×

N hinges.

6. The array of M×

N electrostrictive actuated mirrors of claim 5, wherein the first and second electrodes are made of a conductive metallization.

7. The array of M×

N electrostrictive actuated mirrors of claim 6, wherein each of the first electrodes, when projected onto the top surface of the electrostrictive member, includes the pair of second electrodes.

8. The array of M×

N electrostrictive actuated mirrors of claim 7, wherein each of the pair of second electrodes functions as a first bias electrode and a second bias electrode, respectively.

9. The array of M×

N electrostrictive actuated mirrors of claim 8, wherein a first bias voltage applied to the first bias electrode and a second bias voltage applied to the second bias electrode are of the same magnitude but of the opposite polarities.

10. The array of M×

N electrostrictive actuated mirrors of claim 7, wherein the first electrode function as a common signal electrode.

11. The array of M×

N electrostrictive actuated mirrors of claim 10, wherein a voltage applied to the first electrode is developed in accordance with a corresponding pixel intensity.

12. The array of M×

N electrostrictive actuated mirrors of claim 5, wherein the insulating layers are made of either an oxide or a nitride.

13. The array of M×

N electrostrictive actuated mirrors of claim 5, wherein the M×

N hinges are made of an insulating epoxy.

14. The array of M×

N electrostrictive actuated mirrors of claim 5, wherein the mirrors are made of a light reflecting material.

15. The array of M×

N electrostrictive actuated mirrors of claim 5, wherein each of the connecting terminals is used for electrically connecting each of the first electrodes with the active matrix.