Image combiner and image display unit

• US 20050141066A1
• Filed: 01/10/2005
• Published: 06/30/2005
• Est. Priority Date: 07/26/2002
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Ouchi, Yumiko
• Granted Patent: US 7,072,085 B2
• Time in Patent Office: Days
• US Class Current: 359/15
• 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 2027/0123 comprising devices increasing the field of view
• CPC Class Codes: G02B 2027/0174 holographic
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/0103 comprising holographic elements
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: H04N 5/7491 of head mounted projectors

Abstract

During use, a plate-form part 5 which is constructed from an optical material and which corresponds to a spectacle lens is positioned in front of the eye of the user which is disposed in the vicinity of the exit pupil P of an image combiner 1. The combiner 1 causes light from an image display element 2 to be superimposed on light that is transmitted through the plate-form part 5 so as to pass through the thickness of the plate-form part 5 from the front of the plate-form part 5, and conducts this light to the eye. The light from the image display element 2 reaches the eye of the user after being diffracted and reflected by a reflective type HOE 6 inside the plate-form part 5. The wavelength at which the diffraction efficiency shows a maximum value when the chief rays that are emitted from the center of the display part of the image display element 2 are diffracted and reflected by the reflective type HOE 6 and the wavelength at which the diffraction efficiency shows a maximum value when the chief rays that are emitted from the peripheral portions of the display part in a specified direction are diffracted and reflected by the reflective type HOE 6 are substantially different. As a result, it is possible to improve the image quality of the display images that are obtained in cases where the center of the pupil of the eye of the user deviates from the center of the exit pupil of the image combiner.

Claims

1. An image combiner in which a reflective type hologram optical element is installed, and light from the outside world is superimposed on light from image display means, this image combiner being characterized in that the light that is emitted from the image display means has wavelength region components that respectively extend before and after one or more peak wavelengths, and

the wavelength λ

_o and wavelength λ

_y are different

where λ

_o is the wavelength at which the diffraction efficiency shows a maximum value in the wavelength region in the vicinity of a single peak wavelength among the one or more peak wavelengths after the chief rays that are emitted from the center of the display part of the image display means are diffracted by the reflective type hologram optical element, and

λ

_y is the wavelength at which the diffraction efficiency shows a maximum value in the wavelength region in the vicinity of this single peak wavelength among the one or more peak wavelengths after the chief rays that are emitted from the peripheral portions of the display part are diffracted by the reflective type hologram optical element.

2. The image combiner according to claim 1, wherein

either Equation (6) or Equation (7) shown below is satisfied:

1.013<

λ

_y/λ

_o 

 

(6).
λ

_y/λ

_o<

0.98 

 

(7).

3. The image combiner according to claim 1, wherein Equation (8) shown below is satisfied where FWHM is the full width at half maximum for the single peak wavelength of the light that is emitted from the image display means:

0.2<

|(λ

_y−

λ

_o)/FWHM| 

 

(8).

4. The image combiner according to claim 1, wherein Equation (9) shown below is satisfied where θ

1 is the angle of incidence (angle calculated in air) on the center of the reflective type hologram optical element from the light source that is located on the side of the eye of the observer during playback among the two light sources used to expose the reflective type hologram optical element corresponding to the single wavelength region or the one of peak wavelength regions during the manufacture of this element, and θ

2 is the angle of reflection (angle calculated in air) at the reflective type hologram optical element of the light rays that are emitted from the center of the display part of the image display means and directed toward the center of the exit pupil of the image combiner;

0.80<

|θ

1−

θ

2| 

 

(9).

5. An image display device comprising the image combiner according to claim 1, and an image display means, wherein at least a part containing the image combiner is mounted on a user during use.

14. The image combiner according to claim 2, wherein Equation (8) shown below is satisfied where FWHM is the full width at half maximum for the single peak wavelength of the light that is emitted from the image display means:

0.2<

|(λ

_y−

λ

_o)/FWHM| 

 

(8).

15. The image combiner according to claim 14, wherein Equation (9) shown below is satisfied where θ

1 is the angle of incidence (angle calculated in air) on the center of the reflective type hologram optical element from the light source that is located on the side of the eye of the observer during playback among the two light sources used to expose the reflective type hologram optical element corresponding to the single wavelength region or the one of peak wavelength regions during the manufacture of this element, and θ

2 is the angle of reflection (angle calculated in air) at the reflective type hologram optical element of the light rays that are emitted from the center of the display part of the image display means and directed toward the center of the exit pupil of the image combiner;

0.8°

<

|θ

1−

θ

2| 

 

(9).

16. The image combiner according to claim 2, wherein Equation (9) shown below is satisfied where θ

1 is the angle of incidence (angle calculated in air) on the center of the reflective type hologram optical element from the light source that is located on the side of the eye of the observer during playback among the two light sources used to expose the reflective type hologram optical element corresponding to the single wavelength region or the one of peak wavelength regions during the manufacture of this element, and θ

2 is the angle of reflection (angle calculated in air) at the reflective type hologram optical element of the light rays that are emitted from the center of the display part of the image display means and directed toward the center of the exit pupil of the image combiner;

0.80<

|θ

1−

θ

2 

 

(9).

17. The image combiner according to claim 3, wherein Equation (9) shown below is satisfied where θ

1 is the angle of incidence (angle calculated in air) on the center of the reflective type hologram optical element from the light source that is located on the side of the eye of the observer during playback among the two light sources used to expose the reflective type hologram optical element corresponding to the single wavelength region or the one of peak wavelength regions during the manufacture of this element, and θ

2 is the angle of reflection (angle calculated in air) at the reflective type hologram optical element of the light rays that are emitted from the center of the display part of the image display means and directed toward the center of the exit pupil of the image combiner;

0.80<

|θ

1−

θ

2 

 

(9).

18. An image display device comprising the image combiner according to claim 2, and an image display means, wherein at least a part containing the image combiner is mounted on a user during use.

19. An image display device comprising the image combiner according to claim 3, and an image display means, wherein at least a part containing the image combiner is mounted on a user during use.

20. An image display device comprising the image combiner according to claim 4, and an image display means, wherein at least a part containing the image combiner is mounted on a user during use.

6. An image display device comprising image display means and a light conducting part that conducts light from the image display means to the eye of the user, this image display device being characterized in that:

the light conducting part has a reflective type hologram optical element,

the light that is emitted from the image display means has wavelength region components that respectively extend before and after one or more peak wavelengths, and

the wavelength λ and

wavelength λ

_y are different

where λ

_o is the wavelength at which the diffraction efficiency shows a maximum value in the wavelength region in the vicinity of a single peak wavelength among the one or more peak wavelengths after the chief rays that are emitted from the center of the display part of the image display means are diffracted by the reflective type hologram optical element, and

λ

_y is the wavelength at which the diffraction efficiency shows a maximum value in the wavelength region in the vicinity of the single peak wavelength after the chief rays that are emitted from the peripheral portions of the display part are diffracted by the reflective type hologram optical element.

7. The image display device according to claim 6, wherein either Equation (6) or Equation (7) shown below is satisfied:

1.013<

λ

_y/λ

_o 

 

(6)
λ

_y/λ

_o<

0.98 

 

(7).

8. The image display device according to claim 6, wherein Equation (8) shown below is satisfied where FWHM is the full width at half maximum for the single peak wavelength of the light that is emitted from the image display means:

0.2<

|(λ

_y−

λ

_o)/FWHM| 

 

(8).

9. The image display device according to claim 6, wherein Equation (9) shown below is satisfied where θ

1 is the angle of incidence (angle calculated in air) on the center of the reflective type hologram optical element from the light source that is located on the side of the eye of the observer during playback among the two light sources used to expose the reflective type hologram optical element (corresponding to the single wavelength region or the one of peak wavelength regions during the manufacture of this element, and θ

2 is the angle of reflection (angle calculated in air) at the reflective type hologram optical element of the light rays that are emitted from the center of the display part of the image display means and directed toward the center-of the exit pupil of the image combiner;

0.8°

<

|θ

1−

θ

2| 

 

(9).

10. The image display device according to claim 7, wherein Equation (8) shown below is satisfied where FWHM is the full width at half maximum for the single peak wavelength of the light that is emitted from the image display means:

0.2<

|(λ

_y−

λ

_o)/FWHM | 

 

(8).

11. The image display device according to claim 10, wherein Equation (9) shown below is satisfied where θ

1 is the angle of incidence (angle calculated in air) on the center of the reflective type hologram optical element from the light source that is located on the side of the eye of the observer during playback among the two light sources used to expose the reflective type hologram optical element (corresponding to the single wavelength region or the one of peak wavelength regions during the manufacture of this element, and θ

2 is the angle of reflection (angle calculated in air) at the reflective type hologram optical element of the light rays that are emitted from the center of the display part of the image display means and directed toward the center of the exit pupil of the image combiner;

0.80<

|θ

1−

θ

2 

 

(9).

12. The image display device according to claim 8, wherein Equation (9) shown below is satisfied where θ

1 is the angle of incidence (angle calculated in air) on the center of the reflective type hologram optical element from the light source that is located on the side of the eye of the observer during playback among the two light sources used to expose the reflective type hologram optical element (corresponding to the single wavelength region or the one of peak wavelength regions during the manufacture of this element, and θ

2 is the angle of reflection (angle calculated in air) at the reflective type hologram optical element of the light rays that are emitted from the center of the display part of the image display means and directed toward the center of the exit pupil of the image combiner;

0.80<

|θ

1−

θ

2| 

 

(9).

13. The image display device according to claim 7, wherein Equation (9) shown below is satisfied where θ

1 is the angle of incidence (angle calculated in air) on the center of the reflective type hologram optical element from the light source that is located on the side of the eye of the observer during playback among the two light sources used to expose the reflective type hologram optical element-(corresponding to the single wavelength region or the one of peak wavelength regions during the manufacture of this element, and θ

2 is the angle of reflection (angle calculated in air) at the reflective type hologram optical element of the light rays that are emitted from the center of the display part of the image display means and directed toward the center of the exit pupil of the image combiner;

0.8°

<

|θ

1−

θ

2| 

 

(9).