Electrostrictive actuated mirror array and method for the manufacture thereof

#The present invention relates to an optical projection system; and, more particularly, to an array of electrostrictive actuated mirrors for use in the system and an improved method for manufacturing the same.

#Among the various video display systems available on the art, an optical projection system is known to be capable of providing a high quality display on a large scale. In such an optical projection system, light from a lamp is uniformly illuminated onto an array of, e.g., M.times.N, actuated mirrors such that each of the mirrors is coupled with each of the actuators. The actuators may be made of an electrodisplacive material such as a piezoelectric or an electrostrictive material which deforms in response to an electric field applied thereto.

#The reflected light beam from each of the mirrors is incident upon an aperture of a baffle. By applying an electrical signal to each of the actuators, the relative position of each of the mirrors to the incident light beam is altered, thereby causing a deviation in the optical path of the reflected beam from each of the mirrors. As the optical path of each of the reflected beams is varied, the amount of light reflected from each of the mirrors which passes through the aperture is changed, thereby modulating the intensity of the beam. The modulated beams through the aperture are transmitted onto a projection screen via an appropriate optical device such as a projection lens to thereby display an image thereon.

#The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, wherein:

#FIG. 1 shows a cross sectional view of a prior art array of M.times.N electrodisplacive actuated mirrors; and

#FIGS. 2A to 2G represent schematic cross-sectional views illustrating the manufacturing steps in accordance with a preferred embodiment of the present invention.

#In accordance with the present invention, the process for manufacturing an array of M.times.N electrostrictive actuated mirrors, wherein M and N are integers, begins with the preparation of a ceramic wafer 50, as shown in FIG. 2A, having a thickness of 100-150 .mu.m, made of an electrostrictive material, e.g., lead magnesium niobate-lead titanate(PMN-PT) and having top and bottom surfaces, 51, 52, wherein the top and the bottom surfaces, 51, 52, are flat and parallel to each other.

#As shown in FIG. 2B, there are formed on the entirety of the top surface 51 of the ceramic wafer 50 M regularly spaced, vertically oriented first trenches of a fixed dimension, e.g., 54.sub.M-i, 54.sub.M-i+1, 54.sub.M-i+1, by using, e.g., a wet etching process in conjunction with a laser beam applied thereon, wherein each of the M first trenches, e.g., 54.sub.M-1, runs parallel to each other, and is separated from each other by a barrier, e.g., 55.sub.M-1, having a top flat surface 56, and i is an integer and less than or equal to M-1. Each of the M first trenches has a width of 50-70 .mu.m and a depth of 50-100 .mu.m.

#As shown in FIG. 2C, thereafter, M electrodes, e.g., 57.sub.M-i+1, 57.sub.M-1, 57.sub.M-i+1, are formed by filling each of the M first trenches, e.g., 54.sub.M-i, 54.sub.M-i+1, 54.sub.M-i+1, with an electrically conductive adhesive. Subsequently, N-1 horizontally oriented, regularly spaced and parallel grooves(not shown) are made on the top surface 51 of the ceramic wafer 50 treated in accordance with the above described steps, each of the grooves having the same depth as each of the trenches to thereby generate an array of M.times.N signal electrodes.