Display device which changes color and method

• US 3,972,590 A
• Filed: 09/17/1973
• Issued: 08/03/1976
• Est. Priority Date: 09/17/1973
• Status: Expired due to Term

• Current Assignee: Optical Coating Laboratory, Inc. (Lumentum Holdings Inc.)
• Original Assignee: Optical Coating Laboratory, Inc. (Lumentum Holdings Inc.)
• Inventors: Gelber, Robert M.
• Primary Examiner(s): Corbin, John K.
• Assistant Examiner(s): Koren, Matthew W.
• Application Number:
  US05/398,175
• Time in Patent Office: 1,051 Days
• Field of Search: 350/160 LC
• US Class Current: 349/106
• CPC Class Codes: G02F 1/1335 Structural association of cells with optical devices, e.g. polarisers or reflectors
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 2203/02 reflective
• CPC Class Codes: G02F 2203/34 Colour display without the use of colour mosaic filters

Abstract

Display device which changes colors which has first and second spaced members with the first member being formed of an insulating material and being capable of transmitting light. Means is disposed between the first and second members for diffusing light. Means is carried by the second member which is capable of reflecting light. Means is provided on the first member which is capable of transmitting a certain spectral region of the light beam and for reflecting another spectral region of the light beam so that when the light beam passes through the means disposed between the first and second members and certain of the light is diffused, a color is imparted to the eye of the viewer.

Claims

1. In a display device for use with a light beam, first and second spaced optical members, said first member being capable of transmitting light in the visible region, light reflecting means disposed on the second member, means capable of being activated disposed between the first and second members and having properties of transparency when not activated and scattering when activated, dichroic filter means disposed on the first member for transmitting one spectral region of the light beam in the visible region and reflecting another spectral region of the light beam in the visible region whereby when the means disposed between the first and second members is inactive, said display device has one color in the visible region and when said means disposed between the first and second members is activated the display device has a different color in the visible region.

2. A device as in claim 1 wherein said means disposed between said first and second members is a liquid crystal material together with means for applying an electric field to at least a portion of the liquid crystal material.

3. A device as in claim 1 wherein said light reflecting means carried by the second member is in the form of a reflector reflecting all colors to give an unaltered appearance.

4. A device as in claim 1 wherein said dichroic filter is formed to reflect different colors in different areas of the first member.

5. A device as in claim 4 wherein the areas are very small and interspersed to give the appearance of a mixture of colors.

6. A display device as in claim 1 together with a layer of conducting material carried by the dichroic filter means.

7. A display device as in claim 6 wherein said second member is in the form of a conducting metal sheet.

8. A display device as in claim 1 wherein said light reflecting means carried by the second member is in the form of a dichroic filter so that said device will change colors from the inactive to the active states which are different from white.

9. In a display device for viewing by a viewer with a source of light, first and second spaced members, said first member being capable of transmitting light in the visible region and having first and second surfaces with the first surface facing the source of light and the viewer, a dichroic filter disposed on the second surface of said first member, a electrically conductive coating disposed over said dichroic filter, light reflecting means disposed on said second member, said second member including means capable of carrying an electrical current, a liquid crystal material disposed between said first and second members and in contact with the conductive coating and said current carrying means of said first and second members, respectively said conductive coating and said current carrying means being adapted to be connected to a source of voltage to establish an electric field in the liquid crystal material so that when an electric field is not present, the display device gives one colored appearance in the visible region to the viewer and when an electric field is present in the liquid crystal material, a different colored appearance is given to the viewer in the visible region because of the scattering effect of the liquid crystal material on the light which is transmitted by the dichroic filter on the first member.

10. A display device as in claim 9 wherein said light reflecting means carried by the second member is a dichroic filter disposed on a surface of the second member so that the light reflected therefrom is reflected into the liquid crystal material.

11. A device as in claim 10 wherein the dichroic filter of the second member is disposed on the surface of the second member which is closest to the liquid crystal material.

12. A device as in claim 9 wherein said dichroic filter is formed to reflect different colors in different areas of said second surface of said first member.

13. A device as in claim 12 wherein the areas are very small with the colors provided by the areas being interspersed to give an apparent mixture of colors.

14. In a method for providing a visual display to the eye of a viewer utilizing energy from a light beam in the visible region comprising the steps of providing a liquid crystal material capable by activation of a change from a transparent optical state to a scattering optical state, establishing said liquid crystal material in an unactivated state, providing a dichroic filter, impinging said filter with a beam of incident light, whereby a first spectral portion of said incident light beam is reflected to said viewer, transmitting through said filter and said liquid crystal material a second spectral portion of said incident light beam, and reflecting at least a third spectral portion of said second spectral portion of light back through said liquid crystal material and said filter to said viewer, whereby the colored impression perceived by the viewer is the combination of said first spectral portion and said third spectral portion.

15. A method as in claim 14 further comprising the step of activating said liquid crystal material, whereby said liquid crystal material scatters said second and third light beam portions so that the colored impression perceived by the viewer is substantially said first spectral light portion.

16. A method as in claim 15, further comprising the step of adjusting the relative position of said filter and said liquid crystal material with respect to said viewer such that only said scattered second and third spectral portions are perceived by said viewer.

17. A method as in claim 14 wherein said at least spectral light portion comprises a distinct subportion of said second spectral portion of light.

18. In a method for providing a visual display to the eye of a viewer utilizing energy from a light beam in the visible region, providing a liquid crystal material, providing a dichroic filter, using the dichroic filter to reflect a spectral portion of the light beam to the eye of the viewer, transmitting another spectral portion of the light beam through the dichroic filter and into the liquid crystal material, and selecting one of first and second modes of operation, the first mode comprising reflecting at least a spectral portion of the transmitted spectral portion of the light beam back to the viewer so that the colored impression of the viewer is the combination of the spectral portion of the beam reflected to the viewer and the spectral portion of the transmitted beam which is reflected to the viewer, the second mode comprising scattering the transmitted spectral portion of the beam so that it cannot be seen by the viewer so that the colored impression perceived by the viewer is the color of the reflected spectral portion of the beam.

19. In a method for providing a visual display to the eye of a viewer utilizing energy from a light beam in the visible region, providing a liquid crystal material, providing a dichroic filter, reflecting a spectral portion of the light beam to the eye of the viewer by utilizing the dichroic filter, transmitting another spectral portion of the light beam through the dichroic filter and into the liquid crystal material, reflecting at least a spectral portion of the transmitted spectral portion of the light beam back to the viewer so that the colored impression perceived by the viewer is the combination of the spectral portion of the light beam reflected to the viewer and the spectral portion of the transmitted beam which is reflected to the viewer and thereafter activating the liquid crystal material to scatter the transmitted spectral portion of the beam so that the transmitted beam cannot be seen by the viewer so that the colored impression perceived by the viewer is the color of the reflected spectral portion of the beam.

20. In a method for providing a visual display to the eye of a viewer utilizing energy from a light beam in the visible region, providing a liquid crystal material which exhibits a transparent state when not activated and a scattering state when activated, providing a front dichroic filter and a rear reflector disposed on opposite sides of the liquid crystal material with the back reflector providing a specular reflection when the liquid crystal material is not activated, using the dichroic filter to split the light beam into two spectrally distinct beams, and activating and inactivating said liquid crystal material to obtain selective specular and diffuse reflection of one of said two spectrally distinct beams to thereby obtain optical contrast for the viewer.