Transmissive screen and rear projector

• US 7,012,744 B2
• Filed: 09/05/2003
• Issued: 03/14/2006
• Est. Priority Date: 09/24/2002
• Status: Expired due to Fees

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Sakaguchi, Masafumi
• Primary Examiner(s): Nguyen, Judy
• Assistant Examiner(s): SEVER, ANDREW T
• Application Number:
  US10/654,967
• Publication Number:
  US 20040141234A1
• Time in Patent Office: 921 Days
• Field of Search: 353 72- 81, 359452-457, 359/460, 359/448, 359/459, 348/786, 348/787, 348/789, 348/804, 348/834, 348/835, 348/841, 348/842
• 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

The invention provides a transmissive screen having low occurrence of light diffraction and moire-fringing. The invention also provides a rear projector including such a high-quality transmissive screen. A transmissive screen, applied to a rear projector, includes a light-guide plate having substantially cylindrical light-guide spaces arranged in a flat substrate, and a light-exit-angle distribution uniformizing device to make 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 device is provided at the light-exiting face side of the light-guide plate. The invention also provides 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;

a light-exit-angle distribution uniformizing device to make 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 device being disposed at the light-exiting face side of the light-guide plate, and

wherein the light-exit-angle distribution uniformizing device includes a microlens array having microlenses, each microlens being provided correspondingly to each of the substantially cylindrical light-guide spaces of the light-guide plate, and wherein a material composing the microlenses in a substantially central region of the transmissive screen has a greater refractive index than at least a second material composing the microlenses in a peripheral region of the transmissive screen.

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

m to 150 μ

m.

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

4. The transmissive screen according to claim 1, the flat substrate including an opaque material.

5. The transmissive screen according to claim 1, the microlens array being disposed on the light-exiting face of the light-guide plate.

6. The transmissive screen according to claim 1, the light-guide plate including a light diffusing layer disposed on its light-exiting face, and the microlens array being disposed on the light-exiting face of the light diffusing layer.

7. The transmissive screen according to claim 1, the light-exit-angle distribution uniformizing device being disposed over 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.

8. The transmissive screen according to claim 7, the light diffusing layer diffusing light substantially at the surface thereof.

9. The transmissive screen according to claim 7, the light diffusing layer being disposed on the light-exiting face of the light-guide plate.

10. The transmissive screen according to claim 7, the light diffusing layer having a haze value in the range of 5% to 90%.

11. The transmissive screen according to claim 7, the light diffusing layer having a gloss value in the range of 5% to 40%.

12. The transmissive screen according to claim 7, the light diffusing layer having a rough surface with substantially conical protrusions.

13. A rear projector, comprising:

an optical projection unit;

a light-guide mirror; and

the transmissive screen according to claim 1.