Liquid crystal sequential color display

• US 4,090,219 A
• Filed: 05/26/1976
• Issued: 05/16/1978
• Est. Priority Date: 12/09/1974
• Status: Expired due to Term

• Current Assignee: Hughes Aircraft Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Hoffman, William C., Ernstoff, Michael N., Winner, Richard N.
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Psitos, Aristotelis M.
• Application Number:
  US05/690,324
• Time in Patent Office: 720 Days
• Field of Search: 358/59, 358/58, 358/61, 358/56, 358/64, 358/60, 178/2.82, 350/160 LC
• US Class Current: 348/742
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G02F 1/133622 Colour sequential illumination
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: H04N 11/22 in which simultaneous signals are converted into sequential signals or vice versa

Abstract

A liquid crystal field sequential color display is formed by presenting three monochromatic images corresponding to the three primary colors, that is, red, green and blue, consecutively in a repetitive sequence and at a rate greater than the flicker fusion frequency for human vision. Each field contains a monochromatic image showing how the intensity of the primary color to which it corresponds varies over the entire image area. The black and white imaging techniques typically used for forming the intensity pattern for each field are transformed into the required sequential monochromatic image patterns through the use of colored filters in one embodiment or colored light in another embodiment. The novel result is obtained by the combining of flat panel liquid crystal display technology with color display technology. This invention disclosure shows a practical method for combining these techniques into a device that will form a full color image.

Claims

1. A liquid crystal field sequential color display system for receiving an applied video signal from a video data source and providing a color display to an observer comprising:

liquid crystal display panel means having a multiplicity of liquid crystal cells;

addressing means for selectively energizing individual liquid crystal cells with an applied video signal associated with each of a plurality of primary colors to provide a display pattern for each of said plurality of primary colors characterized by variations in the reflectivity of individual cells over the surface of said display panel;

means for displaying the display pattern associated with each of said plurality of primary colors during repetitive intervals, said means for displaying including means for providing illumination of said liquid crystal display panel by each of said primary colors; and

means for synchronizing the display pattern associated with each of said primary colors with the illumination of said display panel by the associated primary color.

2. A liquid crystal field sequential color display system for receiving an applied video signal from an image data source and providing a color display to an observer comprising:

liquid crystal display panel means having a multiplicity of liquid crystal cells;

addressing means for selectively energizing individual liquid crystal cells with an applied video signal associated with each of a plurality of primary colors to provide a display pattern for each of said plurality of primary colors characterized by variations in the reflectively of individual cells over the surface of said display panel means;

illumination means for sequentially illuminating said display panel means with each of said primary colors during a plurality of color frame intervals, one of said primary colors occurring during each color frame interval; and

means for synchronizing the color frame intervals during which each primary color illumination is incident upon the liquid crystal display panel means with said addressing means.

3. The system of claim 2 wherein said illumination means comprises:

three secondary illuminating sources each of which emits a color of light corresponding to one of the three primary colors; and

a reflector directing said illumination from said secondary sources in the direction of said liquid crystal display panel.

4. A liquid crystal field sequential color display system as recited in claim 2 wherein said illumination means comprises a source of light and a color filter drum in rotational relationship to said source of light with the color filters interposed between said display panel and said source of light.

5. The display system of claim 2 further including light trap means positioned to absorb light specularly reflected from the liquid crystal display panel means.