Peristaltic electrostatic binary device

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This application is related to co-pending applications, Ser. No. 854,822 and Ser. No. 854,820, concurrently filed herewith and commonly assigned, the entire disclosures of which are also, incorporated by references.

This invention relates to electrostatically controllable electromechanical binary devices for use as an array in visual displays, switching matrices, memories, and the like.

The prior art contains various examples of electrostatic display elements. One type of device such as is shown in U.S. Pat. Nos. 1,984,683 and 3,553,364 includes light valves having flaps extending parallel with the approaching light, with each flap electrostatically divertable to an oblique angle across the light path for either a transmissive or reflective display. U.S. Pat. No. 3,897,997 discloses an electrode which is electrostatically wrapped about a curved fixed electrode to affect the light reflective character of the fixed electrode. Further prior art such as is described in ELECTRONICS, Dec. 7, 1970, pp. 78-83, and I.B.M. Technical Disclosure Bulletin, Vol. 13, No. 3, Aug. 1970, uses an electron gun to electrostatically charge selected portions of a deformable material and thereby alter its light transmissive or reflective properties.

Additional instruction in the area of electrostatically controlled elements useable for display purposes can be gained from the following U.S. Pat. Nos.: 4,336,536, Kalt et al.; 4,266,339, Kalt; 4,234,245, Toda et al.; 4,229,075, Ueda et al.; 4,208,103, Kalt et al.; 4,160,583, Ueda et al.; 4,160,582, Yasuo; 4,105,294, Peck; 4,094,590, Kalt; 4,065,677, Micheron et al.; 3,989,357, Kalt; 3,897,997, Kalt; and 888,241, Kuhlmann.

The present invention proceeds from material disclosed in Simpson U.S. Pat. No. 4,248,501, and Simpson et al. 4,235,522, the disclosure of which is incorporated herein by reference.

Of background interest are: W. R. Aiken: "An Electrostatic Sign--The Distec System", Society for Information Display, June 1972, pp. 108-9; J. L. Bruneel et al.: "Optical Display Device Using Bistable Elements", Applied Physics Letters, Vol. 30, no. 8, Apr. 15, 1977, pp. 382-3, an R. T. Gallagher: "Microshutters Flip to Form Characters in Dot-Matrix Display", Electronics, July 14, 1983, pp. 81-2.

Grandjean et al. 4,383,255 deals with the subject of the above Gallager Article. A plurality of shutters are ganged together to form a bar. A pattern of seven bars can display a numeral. Each bar requires an external lead. More on this subject can be found in "A Novel Electromechanical Micro-shutter Display" by R. Vuilleumier et al., a typescript not known to be a publication and showing a date "27.9.1983".

SUMMARY OF THE INVENTION

The present invention provides an electrostatically controllable electromechanical binary device for light reflective or light transmissive display arrays, switching matrices, memories, and the like. Each binary element in the array can be controlled individually by coordinate addressing. Coordinate addressing is employed to select a particular element for actuation. The location of an element in a two dimensional matrix can be its address in terms of the column and row at which the element is found. The columns and rows can be numerical values for variables such as x, y. According to the present invention, the address may comprise more than two dimensions or variables, for example W, X, Y, and Z. The invention will be described in the context of use as a visual display, including black and white and multi-color alpha-numeric and pictorial displays.

A display element (pixel) of this invention has a stator member including a plurality of stationary electrode regions and an electrostatically attractable, flexible member having a transverse bulge, buckle, hump, or undulation moveable back and forth across the stator member. In a eense, the flexible member resembles a carpet having a bulge which can be moved across the room by careful footwork.

The flexible member is electrostatically attractable by the electrode regions of the stator member. By arranging the electrode regions in a linear series, sequential energization of those regions will cause the bulge of the flexible member to progress linearly along the stator member in a peristaltic fashion. Reversing the energization sequence will drive the bulge in the reverse direction.

The flexible member is displaced linearly with respect to the stator a distance related to the size of the bulge in the direction of travel of the bulge. The linear displacement of the moveable member can alter visual or electrical characteristics, or can provide low force linear motion. The device is two-state or binary in character.

If the moveable flexible member of each display element is provided with an appropriate pattern of light and dark color filter, or opaque and translucent areas such as transverse bars, and it is viewed through a stationary mask having a corresponding appropriate pattern, the appearance of the element can be switched in color, or between light and dark by moving the bulge from one end of the flexible member to the other. The corresponding patterns of the mask and flexible member either will be in or out of registration. The display elements can control light transmission or light reflection or color qualities. Electrical characteristics can be switched or altered by registration and de-registration of circuit