Optical retarder

• US 20040183972A1
• Filed: 05/13/2004
• Published: 09/23/2004
• Est. Priority Date: 04/20/2001
• Status: Active Grant

• Current Assignee: Aptiv Technologies AG
• Original Assignee: PureDepth Limited (Aptiv PLC)
• Inventors: Bell, Gareth Paul
• Granted Patent: US 7,742,124 B2
• Time in Patent Office: Days
• US Class Current: 349/117
• CPC Class Codes: G02B 30/40 giving the observer of a single two-dimensional [2D] image a perception of depth
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/13471 in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells G02F1/13475 takes precedence

Abstract

The present invention (1) includes a multi-focal plane display with two or more at least partially overlapping screens (2, 3) with a first order optical retarder (5) interposed therebetween. The invention removes the undersirable presence of coloured interference fringes whilst also providing a means of addressing the polarisation incompatibility between adjacent LCD display screens (2, 3).

Claims

1. A multi-focal plane display including at least two at least partially overlapping display surfaces having a first order optical retarder interposed between at least two said screens.

2. A display as claimed in claim 1, wherein said first order retarder is a material with the optical properties of a biaxial polypropylene.

3. A display as claimed in claim 1 or claim 2, wherein said optical properties include those of a diffuser.

4. A display as claimed in claim 1 or claim 2, further comprising a diffuser formed as a distinct layer from said retarder.

5. A display as claimed in claim 4, wherein said diffuser is adhered to said display by adhesive of a predetermined thickness.

6. A display as claimed in any one of claims 1-5, wherein said biaxial polypropylene is formed as a clear flexible film.

7. A display as claimed in any one of claims 1-5, wherein said biaxial polypropylene is formed as a lacquer or coating.

8. A display as claimed in any one of the preceding claims, wherein said display surfaces are formed from liquid crystal display panels.

9. A display as claimed in any one of the preceding claims, wherein said retarder causes a phase angle retardation of less than or equal to one wavelength of light incident on said display.

10. A display as claimed in claim 9, wherein said retarder causes a linear displacement of less than or equal to 560 nm of said incident light.

11. A display as claimed in any one of the preceding claims, wherein said diffusive effects are formed by a means selected from the group comprising chemical etching;

embossing;

impressing;

or calendering a random, non-periodic surface structure onto the diffuser surface.

12. A method of manufacturing a multi-focal plane display as claimed in any one of claims 1-11, including the step of positioning a first order optical retarder between at least two partially overlapping display surfaces.

13. The method as claimed in claim 12 wherein said first order optical retarder sheet is formed from biaxial polypropylene.

14. A biaxial polypropylene layer adapted for use in an optical system as a first order retarder.

15. A multi focal plane display substantially as hereinbefore described, with reference to, and as shown in the accompanying drawing.

16. A method of manufacturing a multi-focal plane display substantially as hereinbefore described, with reference to, and as shown in the accompanying drawing.