Optical device and image display apparatus

Patent metadata

Field	Value
Publication number	US-10025009-B2
Application number	US-201414156405-A
Country	US
Kind code	B2
Filing date	Jan 15, 2014
Priority date	Jan 22, 2013
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

An optical device includes a light-conducting member, having a first panel surface disposed facing an image forming unit, that conducts image light incident on a light entry plane formed at an end of the first panel surface to a light exit plane formed in front of the viewer's eye; a first diffractive optics element, provided on the light entry plane, that diffracts the image light incident on the light entry plane in a predetermined direction and transmits that light into the light-conducting member; a second diffractive optics element, provided on the light exit plane, that diffracts the image light exiting from the light exit plane in a predetermined direction and transmits that light to the front of the viewer's eye; and one or more reflective planes disposed within a waveguide for the image light diffracted by the first diffractive optics element.

First claim

What is claimed is:

1. An optical device comprising:
an image forming unit that emits image light;
a light-conducting member including:
a light entry plane and a light exit plane,
an opposite plane that faces the light entry plane and the light exit plane,
a light entry portion comprising an area between the light entry plane and the opposite plane and including the light entry plane and a portion of the opposite plane facing the light entry plane, and
a light exit portion comprising an area between the light exit plane and the opposite plane and including the light exit plane and another portion of the opposite plane facing the light exit plane;

a first diffractive optics element positioned between the light entry plane of the light-conducting member and the image forming unit;
a second diffractive optics element positioned on the light exit plane of the light-conducting member; and
a reflective layer positioned on the light-conducting member at an area other than on the opposite plane,
wherein:
the image light is at least partially diffracted by the first diffractive optics element and becomes diffracted image light;
at least some of the diffracted image light enters into the light-conducting member from the light entry plane of the light-conducting member;
the reflective layer is provided in a position that reflects at least some of the diffracted image light that has entered into the light-conducting member directly to the second diffractive optics element; and
a width of the reflective layer is smaller than a width of the second diffractive optics element.

2. The optical device according to claim 1 ,
wherein the reflective layer is further positioned on the light-conducting member at an area other than the light exit plane.

3. The optical device according to claim 2 ,
wherein the reflective layer is positioned on another plane located in the light exit portion, the another plane being a plane different from the light exit plane and the opposite plane.

4. The optical device according to claim 2 ,
wherein the first diffractive optics element and the second diffractive optics element are both volume holograms.

5. The optical device according to claim 2 ,
wherein the first diffractive optics element and the second diffractive optics element are both surface relief holograms.

6. The optical device according to claim 2 ,
wherein the first diffractive optics element and the second diffractive optics element are both slanted surface relief holograms.

7. The optical device according to claim 2 ,
wherein the first diffractive optics element and the second diffractive optics element are both diffractive elements having blazed gratings formed in their surfaces.

8. The optical device according to claim 2 ,
wherein a grating period of the first diffractive optics element and a grating period of the second diffractive optics element are the same grating period.

9. An optical device comprising:
an image forming unit that emits image light;
a first light-conducting member including:
a first light entry plane and a first light exit plane,
a first opposite plane that faces the first light entry plane and the first light exit plane,
a first light entry portion comprising an area between the first light entry plane and the first opposite plane and including the first light entry plane and a portion of the first opposite plane facing the first light entry plane, and
a first light exit portion comprising an area between the first light exit plane and the first opposite plane and including the first light exit plane and another portion of the first opposite plane facing the first light exit plane;

a first diffractive optics element positioned between the first light entry plane of the first light-conducting member and the image forming unit;
a second diffractive optics element positioned on the first light exit plane of the first light-conducting member;
a first reflective layer positioned on the first light-conducting member at an area other than on the first opposite plane;
a second light-conducting member including:
a second light entry plane and a second light exit plane,
a second opposite plane that faces the second light entry plane and the second light exit plane,
a second light entry portion comprising an area between the second light entry plane and the second opposite plane and including the second light entry plane and a portion of the second opposite plane facing the second light entry plane, and
a second light exit portion comprising an area between the second light exit plane and the second opposite plane and including the second light exit plane and another portion of the second opposite plane facing the second light exit plane;

a third diffractive optics element positioned between the second light entry plane of the second light-conducting member and the first light-conducting member;
a fourth diffractive optics element positioned between the second light exit plane of the second light-conducting member and the first light-conducting member; and
a second reflective layer positioned on the second light-conducting member at an area other than on the second opposite plane,
wherein
the image light is at least partially diffracted by the first diffractive optics element and becomes first diffracted image light;
at least some of the first diffracted image light is conducted into the first light-conducting member;
the first reflective layer is provided in a position that reflects at least some of the first diffracted image light conducted into the first light-conducting member directly to the second diffractive optics element;
a width of the first reflective layer is smaller than a width of the second diffractive optics element;
at least some of the image light not diffracted by the first diffractive optics element is diffracted by the third diffractive optics element and becomes second diffracted image light;
at least some of the second diffracted image light enters into the second light-conducting member from the second light entry plane of the second light-conducting member;
the second reflective layer is provided in a position that reflects at least some of the second diffracted image light conducted into the second light-conducting member directly to the fourth diffractive optics element;
a width of the second reflective layer is smaller than a width of the fourth diffractive optics element;
a grating period of the first diffractive optics element and a grating period of the third diffractive optics element are different; and
a grating period of the second diffractive optics element and a grating period of the fourth diffractive optics element are different.

10. An image display apparatus comprising the optical device according to claim 1 .

11. An image display apparatus comprising the optical device according to claim 9 .

12. The optical device according to claim 1 , wherein
the light entry plane and the light exit plane are provided on a first surface of the light-conducting member,
the opposite plane is provided on a second surface of the light-conducting member, and
the first surface and the second surface are substantially parallel.

Assignees

• Seiko Epson Corp

Inventors

• Yamada Fumika
• Yonekubo Masatoshi
• Yokoyama Osamu

Classifications

• G02B6/0035

  provided on the surface of the light guide or in the bulk of it · CPC title

• G02B2027/0174

  holographic · CPC title

• G02B2027/0123

  comprising devices increasing the field of view · CPC title

• G03H2001/2226

  Edge lit holograms · CPC title

• G02B27/0172

  characterised by optical features · CPC title