Total internal reflection prismatically interleaved reflective film display screen

• US 6,437,921 B1
• Filed: 08/14/2001
• Issued: 08/20/2002
• Est. Priority Date: 08/14/2001
• Status: Active Grant

• Current Assignee: Concord HK International Education Limited
• Original Assignee: University of British Columbia
• Inventors: Whitehead, Lorne A.
• Primary Examiner(s): Mack, Ricky
• Assistant Examiner(s): HINDI, OMAR Z
• Application Number:
  US09/928,730
• Time in Patent Office: 371 Days
• Field of Search: 359/222, 359/296, 359/627, 359/628, 359/640, 385/146, 385/129
• US Class Current: 359/640
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 5/08 Mirrors vehicle mirrors involving special optical features B60R1/08

Abstract

A reflective image display screen formed of two reflective sheets. The first sheet has a prismatic inward surface and an opposed outward viewing surface. The second sheet has a prismatic outward surface and an opposed inward surface. The second sheet'"'"'s outward surface is prismatically interleaved with the first sheet'"'"'s inward surface. An air gap substantially 0.5 μm thick is left between the prismatically interleaved surfaces. The prismatic surfaces each constitute a plurality of 60° included angle, parallel, linearly extending prisms. The first sheet'"'"'s outward viewing surface and the second sheet'"'"'s inward surface are flat. The sheets may be formed of a polycarbonate material having a refractive index of about 1.59.

Claims

1. A reflective image display screen, comprising:

(a) a first reflective sheet having a prismatic inward surface and an opposed outward viewing surface;

(b) a second reflective sheet having a prismatic outward surface and an opposed inward surface, said second sheet outward surface prismatically interleaved with said first sheet inward surface; and

,

(c) an air gap substantially 0.5 μ

m thick between said prismatically interleaved surfaces.

2. An image display screen as defined in claim 1, wherein said prismatic surfaces each comprise a plurality of 60°

included angle prisms.

3. An image display screen as defined in claim 2, wherein said prisms are parallel linearly extending prisms.

4. An image display screen as defined in claim 3, wherein said prismatically interleaved sheets further comprise:

(i) substantially each one of said first sheet prisms projects between opposing facets of an adjacent pair of said second sheet prisms; and

(ii) substantially each one of said second sheet prisms projects between opposing facets of an adjacent pair of said first sheet prisms.

5. An image display screen as defined in claim 3, wherein said first sheet outward viewing surface is flat.

6. An image display screen as defined in claim 3, wherein said second sheet inward surface is flat.

7. An image display screen as defined in claim 3, wherein said first sheet outward viewing surface is flat and said second sheet inward surface is flat.

8. An image display screen as defined in claim 3, wherein said first and second sheets are formed of a polycarbonate material.

9. An image display screen as defined in claim 3, wherein said first and second sheets are formed of a material having a refractive index of about 1.59.

10. An image display screen as defined in claim 1, said screen having a preferred viewing direction, and wherein:

(a) said first reflective sheet and said prismatic surfaces together comprise a substantially macroscopically planar and substantially non-light absorptive light deflecting portion of said screen having longitudinal symmetry in a first direction substantially perpendicular to said preferred viewing direction;

(b) said second sheet inward surface comprises a substantially macroscopically planar and substantially non-light absorptive light reflecting portion of said screen having longitudinal symmetry in a second direction substantially perpendicular to said first direction and substantially perpendicular to said preferred viewing direction, said light reflecting portion substantially parallel to said light deflecting portion;

(c) said light deflecting portion deflects light rays incident upon said display in said preferred viewing direction toward said light reflecting portion by imparting to said incident light rays a directional component in said second direction;

(d) said light reflecting portion totally internally reflects said deflected light rays toward said light deflecting portion; and

,

(e) said light deflecting portion deflects said totally internally reflected light rays by cancelling said directional component from said totally internally reflected light rays, such that said deflected totally internally reflected light rays emerge from said screen in a direction substantially parallel to said preferred viewing direction.