Dynamic holographic display with cantilever

• US 5,424,866 A
• Filed: 08/16/1993
• Issued: 06/13/1995
• Est. Priority Date: 01/30/1991
• Status: Expired due to Fees

• Current Assignee: PDACO LIMITED
• Original Assignee: Cordata, Inc.
• Inventors: Kikinis, Dan
• Primary Examiner(s): Ben, Loha
• Assistant Examiner(s): Juba, Jr., John
• Application Number:
  US08/107,987
• Time in Patent Office: 666 Days
• Field of Search: 359/9, 359/10, 359/11, 359/21, 359/35, 359/290, 359/291, 359/292, 359/846, 359/849, 359/850, 359/224, 359/226, 359/230, 359/288, 359/320, 358/2, 395/119, 395/120, 345/32, 348/740, 348/750, 348/771, 348/772
• US Class Current: 359/292
• CPC Class Codes: G03H 1/22 Processes or apparatus for obtaining an optical image from holograms G03H1/26 - G03H1/34 take precedence
• CPC Class Codes: G03H 1/2294 Addressing the hologram to an active spatial light modulator
• CPC Class Codes: G03H 2225/24 Having movable pixels, e.g. microelectromechanical systems [MEMS]

Abstract

A dynamic holographic display has an array of reflective surfaces formed on cantilever structures substantially parallel to the surface of a substrate, such as a silicon wafer. A holographic image is formed by controlling electrical currents passed through the cantilever structures to position the reflective surfaces of the cells in the array so the topography forms a hologram, and reflected light interferes to form a holographic image. In a preferred embodiment, control is by computer and positions of reflective surfaces are determined by calculation from dimensional data available to the control computer.

Claims

1. A method of forming an image comprising steps of:

forming an array of cells on the surface of a substrate, each cell comprising a cantilever structure of semiconducting material, each cantilever structure having a free end and a metallic film with a reflective surface insulated from the semiconducting material except at an area adjacent the free end;

passing electrical currents through said metallic films to the areas adjacent the free ends into the semiconducting material, and back to the substrate from control circuitry connected to said metallic films causing said cantilever structures to head and deform from differing expansion characteristics of the metallic films and the semiconducting material, moving said reflective surfaces; and

controlling said electrical currents for each cell such that said reflective surfaces move in a manner to reflect illumination to provide an image to an observer.

2. The method of claim 1 wherein said substrate is a silicon semiconductor wafer.

3. The method of claim 1 wherein said electrical currents are provided by circuitry comprising semiconductor switching devices and conducting traces formed on said substrate and controlled by a host computer system.