Gain reflector-liquid crystal display

• US 4,991,940 A
• Filed: 01/25/1988
• Issued: 02/12/1991
• Est. Priority Date: 01/25/1988
• Status: Expired due to Term

• Current Assignee: Tyco Electronics Corporation (TE Connectivity Limited)
• Original Assignee: Taliq Corp. (TE Connectivity Limited)
• Inventors: McCoy, James, Dalisa, Andrew L., Wiley, Richard
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): GROSS, ANITA P
• Application Number:
  US07/147,756
• Time in Patent Office: 1,114 Days
• Field of Search: 350/338, 350/129, 350/334, 350/335, 350/345
• US Class Current: 349/113
• CPC Class Codes: G02F 1/055 the active material being a ceramic G02F1/035 takes precedence
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/1375 using dynamic scattering
• CPC Class Codes: G02F 1/13756 the liquid crystal selectively assuming a light-scattering state G02F1/1334, G02F1/13718 take precedence

Abstract

A display apparatus comprising a display medium and a gain reflector disposed behind the display medium for reflecting incident light. The display medium may comprise a liquid crystal material containing a dye that conforms to the structure of the liquid crystal material and a containment medium for inducing distorted alignment of the liquid crystal material which in response to such alignment scatters and absorbs light and which response to a prescribed input reduces the amount of such scattering and absorption.

Claims

1. A display comprising:

a display medium switchable between a first state in which incident light is at least one of scattered and absorbed and a second state in which the amount of such scattering or absorption is reduced; and

an offset gain reflector means disposed behind said display medium for reflecting light passing through said display medium such that said reflected light is angularly offset from the specular reflection from said display medium, said offset gain reflector means including an array of optical elements disposed in a continuous relation forming a sheet of optical elements, and each optical element having in at least one plane orthogonal to the sheet a curved reflecting surface with a positive slope portion and a negative slope portion wherein the length of one of said portions is greater than the other and said portion having the greater length having a curvature less than said other portion.

2. The display of claim 1 wherein said display medium comprises a dynamic scattering liquid crystal material.

3. The display of claim 1 wherein said display medium comprises an encapsulated operationally nematic liquid crystal material.

4. The display of claim 3 wherein said encapsulated operationally nematic liquid crystal material contains a dye.

5. The display of claim 1 wherein said display medium is a material selected from the group consisting of twisted nematic liquid crystal material and super twist liquid crystal material.

6. The display of claim 1 wherein said display medium comprises a PLZT ferroelectric ceramic material.

7. The display of claim 1 wherein said positive slope portion is greater than said negative slope portion.

8. The display of claim 1 wherein said negative slope portion is greater than said positive slope portion.

9. A display apparatus comprising:

a liquid crystal means at a viewing side of the display;

said liquid crystal means comprising liquid crystal material containing a dye that conforms to the structure of the liquid material and a containment medium means for inducing a distorted alignment of said liquid crystal material which in response to such alignment scatters and absorbs light and which in response to a prescribed input reduces the amount of such scattering and absorption; and

an offset gain reflector means disposed behind said liquid crystal means for reflecting light passing through said liquid crystal means, such that said reflected light is directionally separated from any specular reflection, said offset gain reflector means including an array of optical elements disposed in a contiguous relation, each optical element having a concave and convex reflecting surface wherein each optical element is smoothly joined to the next without any discontinuities therebetween.

10. The display apparatus of claim 9 utilized in a vehicle dashboard and including a front lighting source.

11. The display apparatus of claim 9 further including a color lens disposed between said liquid crystal means and said gain reflector means.

12. The display apparatus of claim 9, said liquid crystal material being birefringent and having an ordinary index of refraction in the presence of a prescribed input that is substantially matched to the index of refraction of said containment medium means to minimize refraction and scattering of light and an extraordinary index of refraction in the absence of such prescribed input that is different from the index of refraction of said containment medium means to cause refraction and scattering of light.

13. The display apparatus of claim 12 further comprising input means for applying such prescribed input to said liquid crystal material.

14. The display apparatus of claim 13, said input means comprising electrode means at the opposite surfaces of said liquid crystal material for applying an electric field across said liquid crystal material.

15. The display apparatus of claim 14 further comprising circuit means for providing electric energy to said electrode means to effect application of an electric field to said liquid crystal material.

16. The display apparatus of claim 9 wherein said dye is a pleochroic dye.

17. The display apparatus of claim 16 wherein the structure of said pleochroic dye is operative to absorb light when said liquid crystal material is in distorted alignment.

18. The display apparatus of claim 17 further comprising means for applying an electric field to said liquid crystal material to tend to effect generally parallel alignment of said liquid crystal material to reduce the amount of absorption by said dye.

19. A display comprising:

a display medium switchable between a first state in which incident light is at least one of scattered and absorbed and a second state in which the amount of such scattering or absorption is reduced; and

an offset gain reflector means disposed behind said display medium for reflecting light passing through said display medium such that said reflected light is angularly offset from the specular reflection from said display medium, said offset gain reflector means including an array of optical elements disposed in a continuous relation forming a sheet of optical elements and each optical element having in a first plane orthogonal to the sheet a curved reflecting surface with a positive slope portion and a negative slope portion wherein the length of one of said portions is greater than the other and said portion having the greater length having a curvature less than said other portion, and having in a second plane orthogonal to the sheet a curved reflecting surface with positive and negative slope portions wherein the lengths and curvatures of said slope portions are substantially the same.