IMAGE DISPLAY DEVICE

• US 20120243063A1
• Filed: 06/11/2012
• Published: 09/27/2012
• Est. Priority Date: 11/29/2007
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Mukawa, Hiroshi
• Granted Patent: US 8,743,442 B2
• Time in Patent Office: Days
• US Class Current: 359/15
• CPC Class Codes: G02B 17/004 Systems comprising a plurality of reflections between two or more surfaces, e.g. cells, resonators multipass arrangements for optical cuvettes G01N21/031; laser resonators H01S3/05
• CPC Class Codes: G02B 2027/0112 comprising device for genereting colour display
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 2027/0174 holographic
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 5/18 Diffraction gratings holographic optical elements G02B5/32, G03H; integrally combined with optical fibres G02B6/02057; for coupling light guides G02B6/34; integrally combined with optical integrated light guides G02B6/12; grating systems G02B27/44
• CPC Class Codes: G02B 5/1814 structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings G02B5/189 takes precedence
• CPC Class Codes: G02B 5/1861 Reflection gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02B 6/00 Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces

Abstract

An image display device includes an image forming device, collimating optical system, and optical device, with the optical device including a light guide plate, first diffraction grating member and second diffraction grating member which are made up of a volume hologram diffraction grating, and with central light emitted from the pixel of the center of the image forming device and passed through the center of the collimating optical system being input to the light guide plate from the near side of the second diffraction grating member with a certain angle. Thus, the image display device capable of preventing occurrence of color irregularities, despite the simple configuration, can be provided.

Claims

1. An image display device comprising:

an image forming device; and

an optical device,

wherein said optical device includes

a light guide plate wherein input light is propagated internally,

a first diffraction grating member for diffracting and reflecting light input to said light guide plate which is disposed on said light guide plate, and

a second diffraction grating member for diffracting and reflecting light propagated within said light guide plate which is disposed on said light guide plate,

wherein the thickness of said second diffraction grating member is thinner than the thickness of said first diffraction grating member.

2. The image display device according to claim 1, wherein the thickness of the second diffraction grating member is less than 5 μ

m, and the thickness of the first diffraction grating member is equal to or greater than 5 μ

m.

3. The image display device according to claim 1, wherein said light emitted from said light guide plate which is equivalent to central light is orthogonal to a straight line connecting the two pupil centers of an observer.

4. The image display device according to claim 1, wherein the value of the maximum diffraction efficiency of said second diffraction grating member is smaller than the value of the maximum diffraction efficiency of said first diffraction grating member.

5. The image display device according to claim 4, wherein the maximum diffraction efficiency of the first diffraction grating member is equal to or greater than 50%, and the value of the maximum diffraction efficiency of the second diffraction grating member is less than 50%.

6. The image display device according to claim 4, wherein the maximum diffraction efficiency of the first diffraction grating member is equal to or greater than 90%, and the value of the maximum diffraction efficiency of the second diffraction grating member is less than 30%.

7. The image display device according to claim 1, wherein the first diffraction grating member includes a volume hologram diffraction grating, and the second diffraction grating member includes a volume hologram diffraction grating.

8. The image display device according to claim 7, wherein said volume hologram diffraction gratings are reflection-type volume hologram diffraction gratings.

9. An optical device comprising:

a light guide plate wherein input light is propagated internally;

a first diffraction grating member for diffracting and reflecting light input to said light guide plate which is disposed on said light guide plate; and

a second diffraction grating member for diffracting and reflecting light propagated within said light guide plate which is disposed on said light guide plate,

wherein the thickness of said second diffraction grating member is thinner than the thickness of said first diffraction grating member.

10. The optical device according to claim 9, wherein the thickness of the second diffraction grating member is less than 5 μ

m, and the thickness of the first diffraction grating member is equal to or greater than 5 μ

m.

11. The optical device according to claim 9, wherein said light emitted from said light guide plate which is equivalent to central light is orthogonal to a straight line connecting the two pupil centers of an observer.

12. The optical device according to claim 9, wherein the value of the maximum diffraction efficiency of said second diffraction grating member is smaller than the value of the maximum diffraction efficiency of said first diffraction grating member.

13. The optical device according to claim 12, wherein the maximum diffraction efficiency of the first diffraction grating member is equal to or greater than 50%, and the value of the maximum diffraction efficiency of the second diffraction grating member is less than 50%.

14. The optical device according to claim 12, wherein the maximum diffraction efficiency of the first diffraction grating member is equal to or greater than 90%, and the value of the maximum diffraction efficiency of the second diffraction grating member is less than 30%.

15. The optical device according to claim 9, wherein the first diffraction grating member includes a volume hologram diffraction grating, and the second diffraction grating member includes a volume hologram diffraction grating.

16. The optical device according to claim 15, wherein said volume hologram diffraction gratings are reflection-type volume hologram diffraction gratings.