Transmissive screen and rear projector

• US 20040141234A1
• Filed: 09/05/2003
• Published: 07/22/2004
• Est. Priority Date: 09/24/2002
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Sakaguchi, Masafumi
• Granted Patent: US 7,012,744 B2
• Time in Patent Office: Days
• US Class Current: 359/456
• CPC Class Codes: G02B 5/021 the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
• CPC Class Codes: G02B 5/0221 the surface having an irregular structure G02B5/0226 takes precedence
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02B 5/0294 adapted to provide an additional optical effect, e.g. anti-reflection or filter
• CPC Class Codes: G02B 6/0001 specially adapted for lighting devices or systems lighting or signalling on vehicles using light guides B60Q1/00; lighting devices for vehicle dashboards B60Q3/10; lighting devices for vehicle interior using light guides B60Q3/62; lighting devices mounted on the vehicle rear part using light guides F21S43/235; measuring arrangements having light conducting pointers G01D13/265; illumination of liquid crystal displays G02F1/1336; illuminated signs G09F13/00
• CPC Class Codes: G03B 21/10 Projectors with built-in or built-on screen
• CPC Class Codes: G03B 21/602 Lenticular screens G03B21/625 takes precedence

Abstract

To provide a transmissive screen having low occurrence of light diffraction and moire-fringing, and also to provide a rear projector including such a high-quality transmissive screen. A transmissive screen applied to a rear projector, including a light-guide plate having substantially cylindrical light-guide spaces arranged in a flat substrate, and light-exit-angle distribution uniformizing means for making the angular distribution of the light exiting from the substantially cylindrical light-guide spaces of the light-guide plate uniform over the transmissive screen, the light-exit-angle distribution uniformizing means being provided at the light-exiting face side of the light-guide plate. A rear projector including such a transmissive screen.

Claims

1. A transmissive screen applied to a rear projector, the transmissive screen comprising a light-guide plate having substantially cylindrical light-guide spaces arranged in a flat substrate;

and light-exit-angle distribution uniformizing means for making the angular distribution of the light exiting correspondingly from the substantially cylindrical light-guide spaces of the light-guide plate uniform over the transmissive screen, the light-exit-angle distribution uniformizing means being disposed at the light-exiting face side of the light-guide plate.

2. The transmissive screen according to claim 1, wherein the light-guide spaces have a diameter in the range of 1 μ

m to 150 μ

m.

3. The transmissive screen according to claim 1, wherein the light-guide spaces have a length greater than the diameter of the light-guide spaces, and have a length of 10 mm or less.

4. The transmissive screen according to any one of claim 1, wherein the flat substrate comprises an opaque material.

5. The transmissive screen according to any one of claim 1, wherein the light-exit-angle distribution uniformizing means comprises a microlens array having microlenses, each microlens being provided correspondingly to each of the substantially cylindrical light-guide spaces of the light-guide plate, the microlenses in a substantially central region of the transmissive screen having radii of curvature smaller than at least the radii of curvature of the microlenses in a peripheral region of the transmissive screen.

6. The transmissive screen according to any one of claim 1, wherein the light-exit-angle distribution uniformizing means comprises a microlens array having microlenses, each microlens being provided correspondingly to each of the substantially cylindrical light-guide spaces of the light-guide plate, a material composing the microlenses in a substantially central region of the transmissive screen has a greater refractive index that at least a second material composing the microlenses in a peripheral region of the transmissive screen.

7. The transmissive screen according to claim 5, wherein the microlens array is disposed on the light-exiting face of the light-guide plate.

8. The transmissive screen according to claim 5, wherein the light-guide plate comprises a light diffusing layer disposed on its light-exiting face, and the microlens array is disposed on the light-exiting face of the light diffusing layer.

9. The transmissive screen according to any one of claim 1, wherein the light-exit-angle distribution uniformizing means comprises a light diffusing layer, the light diffusing layer in a central region of the transmissive screen having a haze value greater than at least the haze value of the light diffusing layer in a peripheral region of the transmissive screen.

10. The transmissive screen according to claim 9, wherein the light diffusing layer diffuses light substantially at the surface thereof.

11. The transmissive screen according to claim 9, wherein the light diffusing layer is disposed on the light-exiting face of the light-guide plate.

12. The transmissive screen according to any one of claim 9, wherein the light diffusing layer has a haze value in the range of 5% to 90%.

13. The transmissive screen according to any one of claim 9, wherein the light diffusing layer has a gloss value in the range of 5% to 40%.

14. The transmissive screen according to any one of claim 9, wherein the light diffusing layer has a rough surface with substantially conical protrusions.

15. A rear projector comprising an optical projection unit, a light-guide mirror, and a transmissive screen according to any one of claim 1.