Light modulating element array and method of driving the light modulating element array

#1. Field of the Invention

#The present invention relates to a light modulating element array which is available as an optical exposure device and a panel display device and, more particularly, to a light modulating element array operative to modulate light traveling in a light guide by electromechanically deflecting a thin-film toward the light guide.

#2. Description of the Related Art

#The above and other objects and features of the present invention will be clearly understood from the following description with respect to the preferred embodiment thereof when considered in conjunction with the accompanying drawings, wherein the same reference numerals have been used to denote the same or similar parts or elements, and in which:

#FIG. 1 is a plan view showing a panel display device in accordance with an embodiment of the present invention;

#FIG. 2 is a cross-sectional view taken along line II—II of FIG. 1;

#Referring to the drawings in detail, and in particular, FIGS. 1 to 4 show a panel display device 21 according to a desired embodiment of the present invention. As schematically shown in FIG. 1, the panel display device 21 comprises a plate type of light modulating element array 25 disposed on a transparent base substrate 27 such as a glass plate and a line light source such as a fluorescent lamp 23 disposed on the back side of the transparent base substrate 27. The light modulating element array 25 comprises a plurality of strip-shaped light guides 29, such as waveguides or light guide plates, formed in parallel to one another on the transparent base substrate 27. The fluorescent lamp 23 is disposed in close proximity to ends of the light guides 29 on one side of the transparent base substrate 27 opposite to the other side where the light modulating element array 25 is disposed such that it extends in a direction perpendicular to the light guides 29. Fluorescent rays emanating from the fluorescent lamp 23 enter the respective light guides 29 passing through an optical element 31 installed to the transparent base substrate 27 at the back side as shown in FIG. 4. The light having entered the light guide 29 once travels in the light guide 29 repeating total reflection at the interfaces of the light guide 29. There is a parallel arrangement of strip-shaped electromechanically deflectable main thin-films 33 on the transparent base substrate 27. Each main thin-film 33 extends in a direction in which the light guide 29 extends such as to spatially overlap a from portion of the light guide 29 and is suspended at a specified distance from the interface of the light guide 29 by a spacer (not shown) on the transparent base substrate 27. Further, there is a parallel arrangement of strip-shaped electromechanically deflectable subsidiary thin-films 35 over the light guides 29. Each subsidiary thin-film 35 extends perpendicularly to the light guides 29 such as to spatially intersect to the light guides 29 and is suspended at a specified distance from the interface of the light guide 29 by a spacer (not shown) on the transparent base substrate 27. That is to say, the light guides 29 and the subsidiary thin-films 35 are arranged in a grade pattern to form a dot matrix of intersection points. These light guide 29, main thin-film 33 and subsidiary thin-film 35 form a light modulating element 36. The suspended structure of these main thin-films 33 and subsidiary thin-films 35 will be described in detail later.

#As shown in FIG. 2, there is a first transparent electrode 37 formed on the entire area of transparent base substrate 27. This transparent electrode 37 is made of a metal oxide such as indium tin oxide (ITO) having high electron density, an ultra thin metal film such as an aluminum film, a thin-film metal comprising fine-grain metal dispersed in transparent insulating material, high density-doped wide-band gap semi-conductor.

#As shown in FIG. 3, there is one spacer 41 extending between each adjacent light guides 29 on an insulation layer 39 formed over the transparent electrode 37. The spacer 41 my be made of, for example, silicon oxides, silicone nitrides, ceramics, resins and the like. The subsidiary thin-film 35 is supported by the spacers 41 arranged at regular distances so as to form a cavity or air gap 49 below the subsidiary thin-film 35 between each adjacent spacers 41. Although not shown in FIG. 2, the main thin-film 33 is also supported by the spacers so as to form a cavity or air gap below the main thin-film 33 between the spacers.