Light scattering display having a structured solid state selectivity reflective layer formed inside the display cell

• US 6,130,733 A
• Filed: 09/16/1998
• Issued: 10/10/2000
• Est. Priority Date: 09/16/1998
• Status: Expired due to Fees

• Current Assignee: Videocon Global Ltd. (Videocon Industries Limited)
• Original Assignee: International Business Machines Corporation
• Inventors: Lowe, Anthony Cyril
• Primary Examiner(s): Parker, Kenneth
• Application Number:
  US09/154,019
• Time in Patent Office: 755 Days
• Field of Search: 349/62, 349/64, 349/96, 349/97, 349/86, 349/113, 349/56, 349/104
• US Class Current: 349/86
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133565 inside the LC elements, i.e. between the cell substrates
• CPC Class Codes: G02F 2203/023 total internal reflection

Abstract

A display device having a selectively reflective layer inside the display cell is described. By incorporating the selectively reflective layer inside the display cell itself, enhanced reflectivity is produced from the scattering state, but the problem of parallax is substantially avoided.

Claims

1. A display device comprising a structured solid state selectively reflective layer formed inside a display cell, said display cell comprising at least a display transducer, wherein said structured solid state selectively reflective layer transmits light that is not scattered by said display transducer and reflects a portion of light that is scattered in a forward direction by the display transducer towards a viewer.

2. The display device of claim 1 wherein the display transducer comprises liquid crystals.

3. The display device of claim 2 wherein the liquid crystals are polymer stabilized cholesteric liquid crystals.

4. The display device of claim 2 wherein the liquid crystals are polymer dispersed liquid crystals.

5. The display device of claim 2 wherein the liquid crystals are surface stabilized cholesteric liquid crystals.

6. The display device of claim 2 wherein the liquid crystals can be switched by means of an electric field from a transparent to a scattering state.

7. The display device of claim 2 wherein the liquid crystals can be switched by thermal means from a transparent to a scattering state.

8. The display device of claim 1 wherein the selectively reflective layer has a thickness of a least about 1 μ

m.

9. The display device of claim 1 wherein the selectively reflective layer is a high or low refractive index material.

10. The display device of claim 9 wherein the high refractive index material is a mixed oxide amorphous material.

11. The display device of claim 9 wherein the low refractive index material is a fluorinated polymeric material.

12. The display device of claim 1 wherein the selectively reflective layer is formed as a series of ridges substantially triangular in cross-section.

13. The display device of claim 1 wherein the selectively reflective layer is formed as a close packed rectilinear array of square pyramids.

14. The display device of claim 1 wherein a transparent electrode layer is formed on top of the selectively reflective layer.

15. The display device of claim 1 wherein a transparent electrode layer is formed between the selectively reflective layer and a light absorbing layer.

16. The display device of claim 1 wherein the selectively reflective layer is designed to become reflective at angles less than a predetermined critical angle for propagation of light therethrough.