IMAGE DISPLAY DEVICE

• US 20090141324A1
• Filed: 10/21/2008
• Published: 06/04/2009
• 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 8,213,065 B2
• Time in Patent Office: Days
• US Class Current: 359/13
• 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 including a plurality of pixels arrayed in a two-dimensional matrix manner;

a collimating optical system for converting light emitted from the pixels of the image forming device into parallel light; and

an optical device which light converted into a plurality of parallel light of which the advancing directions differ by the collimating optical system is input to, and is guided, and is emitted from;

wherein said optical device includes

a light guide plate wherein input light is propagated internally by total reflection, and is emitted,

a first diffraction grating member including a volume hologram diffraction grating for diffracting and reflecting light input to said light guide plate such that light input to said light guide plate is subjected to total reflection within said light guide plate, which is disposed on said light guide plate, and

a second diffraction grating member including a volume hologram diffraction grating for diffracting and reflecting light propagated within said light guide plate by total reflection, and emitting the light from said light guide plate, which is disposed on said light guide plate;

and wherein when assuming that the center of said first diffraction grating member is the origin, a normal of said first diffraction grating member passing through the origin with the direction toward said collimating optical system side as the positive direction is an X_i axis, and the axis line of said light guide plate with the direction passing through the origin, orthogonal to the X_i axis, toward said second diffraction grating member side as the positive direction is a Y_i axis, central light emitted from the pixel of the center of said image forming device, and passes through the center of the collimating optical system is optically parallel to an X_i-Y_i plane, and is also intersected with an X_i-Z_i plane with an acute angle.

2. The image display device according to claim 1, wherein said Y_i axis is optically orthogonal to an interference pattern formed in said first diffraction grating member.

3. The image display device according to claim 1, wherein the optical axis of the collimating optical system is parallel to said X_i-Y_i plane, and is intersected with said X_i-Z_i plane with an acute angle.

4. The image display device according to claim 3, wherein the optical axis of the collimating optical system optically passes through the center of said image forming device.

5. The image display device according to claim 1, wherein the optical axis of the collimating optical system is parallel to the X_i axis;

and wherein the optical axis of the collimating optical system optically passes through a position deviant from the center of said image forming device.

6. The image display device according to claim 1, wherein when assuming that the center of said second diffraction grating member is a second origin, a normal of said second diffraction grating member passing through said second origin with the optical emission direction as the positive direction is an X_o axis, and the axis line of said light guide plate with the direction passing through said second origin orthogonal to said X_o axis departed from said first diffraction grating member side as the positive direction is a Y_o axis, light emitted from said light guide plate which is equivalent to central light is optically parallel to an X_o-Y_o plane, and is also intersected with an X_o-Z_o plane with an obtuse angle.

7. 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.

8. The image display device according to claim 1, wherein the thickness of said second diffraction grating member is thinner than the thickness of said first diffraction grating member.

9. 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.

10. The image display device according to claim 1, wherein said volume hologram diffraction grating is reflection-type volume hologram diffraction grating.

11. An image display device comprising:

a light source;

a scanning optical system configured to scan light emitted from said light source, and form virtual pixels arrayed in a two-dimensional matrix manner; and

an optical device which parallel light from said scanning optical system is input to, and is guided, and is emitted from;

wherein said optical device includes

a light guide plate wherein input light is propagated internally by total reflection, and is emitted,

a first diffraction grating member including a volume hologram diffraction grating for diffracting and reflecting light input to said light guide plate such that light input to said light guide plate is subjected to total reflection within said light guide plate, which is disposed on said light guide plate, and

a second diffraction grating member including a volume hologram diffraction grating for diffracting and reflecting light propagated within said light guide plate by total reflection, and emitting the light from said light guide plate, which is disposed on said light guide plate;

and wherein when assuming that the center of said first diffraction grating member is the origin, a normal of said first diffraction grating member passing through the origin with the direction toward said collimating optical system side as the positive direction is an X_i axis, and the axis line of said light guide plate with the direction passing through the origin, orthogonal to the X_i axis, toward said second diffraction grating member side as the positive direction is a Y_i axis, central light emitted from the center of said light source, and passes through a virtual pixel of the said scanning optical system is optically parallel to an X_i-Y_i plane, and is also intersected with an X_i-Z_i plane with an acute angle.

12. The image display device according to claim 11, wherein said volume hologram diffraction grating is reflection-type volume hologram diffraction grating.

13. An image display device comprising:

an image forming device including a plurality of pixels arrayed in a two-dimensional matrix manner;

a collimating optical system for converting light emitted from the pixels of the image forming device into parallel light; and

an optical device which light converted into a plurality of parallel light of which the advancing directions differ by the collimating optical system is input to, and is guided, and is emitted from;

wherein said optical device includes

a light guide plate wherein input light is propagated internally by total reflection, and is emitted,

a first diffraction grating member including a volume hologram diffraction grating for diffracting and reflecting light input to said light guide plate such that light input to said light guide plate is subjected to total reflection within said light guide plate, which is disposed on said light guide plate, and

a second diffraction grating member including a volume hologram diffraction grating for diffracting and reflecting light propagated within said light guide plate by total reflection, and emitting the light from said light guide plate, which is disposed on said light guide plate;

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

14. The image display device according to claim 13, wherein the thickness of said second diffraction grating member is less than 5 μ

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

m.

15. The image display device according to claim 13, wherein said volume hologram diffraction grating is reflection-type volume hologram diffraction grating.

16. An image display device comprising:

a light source;

a scanning optical system configured to scan light emitted from said light source, and form virtual pixels arrayed in a two-dimensional matrix manner; and

an optical device which parallel light from said scanning optical system is input to, and is guided, and is emitted from;

wherein said optical device includes

a light guide plate wherein input light is propagated internally by total reflection, and is emitted,

a first diffraction grating member including a volume hologram diffraction grating for diffracting and reflecting light input to said light guide plate such that light input to said light guide plate is subjected to total reflection within said light guide plate, which is disposed on said light guide plate, and

a second diffraction grating member including a volume hologram diffraction grating for diffracting and reflecting light propagated within said light guide plate by total reflection, and emitting the light from said light guide plate, which is disposed on said light guide plate;

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

17. The image display device according to claim 16, wherein said volume hologram diffraction grating is reflection-type volume hologram diffraction grating.

18. An image display device comprising:

an image forming device including a plurality of pixels arrayed in a two-dimensional matrix manner;

a collimating optical system for converting light emitted from the pixels of the image forming device into parallel light; and

an optical device which light converted into a plurality of parallel light of which the advancing directions differ by the collimating optical system is input to, and is guided, and is emitted from;

wherein said optical device includes

a light guide plate wherein input light is propagated internally by total reflection, and is emitted,

a first diffraction grating member including a volume hologram diffraction grating for diffracting and reflecting light input to said light guide plate such that light input to said light guide plate is subjected to total reflection within said light guide plate, which is disposed on said light guide plate, and

a second diffraction grating member including a volume hologram diffraction grating for diffracting and reflecting light propagated within said light guide plate by total reflection, and emitting the light from said light guide plate, which is disposed on said light guide plate;

and 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.

19. The image display device according to claim 18, wherein the maximum diffraction efficiency of said second diffraction grating member is less than 50%, and the maximum diffraction efficiency of said first diffraction grating member is equal to or greater than 50%.

20. The image display device according to claim 18, wherein said volume hologram diffraction grating is reflection-type volume hologram diffraction grating.

21. An image display device comprising:

a light source;

a scanning optical system configured to scan light emitted from said light source, and form virtual pixels arrayed in a two-dimensional matrix manner; and

an optical device which parallel light from said scanning optical system is input to, and is guided, and is emitted from;

wherein said optical device includes

a light guide plate wherein input light is propagated internally by total reflection, and is emitted,

a first diffraction grating member including a volume hologram diffraction grating for diffracting and reflecting light input to said light guide plate such that light input to said light guide plate is subjected to total reflection within said light guide plate, which is disposed on said light guide plate, and

a second diffraction grating member including a volume hologram diffraction grating for diffracting and reflecting light propagated within said light guide plate by total reflection, and emitting the light from said light guide plate, which is disposed on said light guide plate;

and 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.

22. The image display device according to claim 21, wherein said volume hologram diffraction grating is reflection-type volume hologram diffraction grating.