Virtual image display device

• US 8,576,491 B2
• Filed: 01/24/2012
• Issued: 11/05/2013
• Est. Priority Date: 02/04/2011
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Takagi, Masayuki, Totani, Takahiro, Komatsu, Akira, Takeda, Takashi, Miyao, Toshiaki
• Primary Examiner(s): Sugarman, Scott J
• Assistant Examiner(s): O'NEILL, GARY WILLIAM
• Application Number:
  US13/357,205
• Publication Number:
  US 20120200936A1
• Time in Patent Office: 651 Days
• Field of Search: 359/630, 359/632, 359/633, 345/7, 345/8, 345/9
• US Class Current: 359/633
• 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 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 6/00 Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings

Abstract

In regard to a second direction (combination direction) that is turned back by a reflection at the time of light-guiding, a projective optical system has an emission opening width larger than an opening width of a third reflective surface, such that it is possible to prevent a partial deficiency of image light when the image light emitted from the projective optical system is incident to the third reflective surface from occurring, and thereby it is possible to prevent the occurrence of deficiency of an image or a large variation in brightness.

Claims

1. A virtual image display device, comprising:

an image display device that emits image light;

a projective optical system that allows the image light emitted from the image display device to be incident; and

a light guiding member, comprising;

a light guiding portion;

a light incidence portion that allows the image light to be incident to the light guiding portion; and

a light emission portion that emits the image light guided by the light guiding portion to the outside, and that makes the image light visible through the light emission portion,

the light guiding portion having a first reflective surface and a second reflective surface that are disposed in parallel with each other and allow the image light to be guided through a substantially total reflection,

the light incidence portion having a third reflective surface that defines an opening width and makes a predetermined angle with respect to the first reflective surface,

the light emission portion having a fourth reflective surface that makes a predetermined angle with respect to the first reflective surface, and

the projective optical system having an emission opening width that is larger than the opening width of the third reflective surface in a direction that is parallel with a plane of the first reflective surface and is orthogonal to an intersection line between the first reflective surface and the third reflective surface.

2. The virtual image display device according to claim 1,

a distance from a lens, which is closest to the light emission side, of the projective optical system to the first reflective surface of the light guiding member being 3 mm or less.

3. The virtual image display device according to claim 1,

the emission opening width of the projective optical system in a second direction that is parallel with the first reflective surface and is orthogonal to the intersection line between the first reflective surface and the third reflective surface being smaller than that in a first direction that is parallel with the intersection line between the first reflective surface and the third reflective surface.

4. The virtual image display device according to claim 3,

an effective size of the image display device in the second direction being larger than that in the first direction.

5. The virtual image display device according to claim 1,

the number of times of reflection of a first image light beam emitted from a first partial region in the image display device in the light guiding portion, and the number of times of reflection of a second image light beam emitted from a second partial region different from the first partial region in regard to a confinement direction in which a return of an optical path due to reflection occurs at the time of the light-guiding, in the light guiding portion, being different from each other.

6. The virtual image display device according to claim 5,

the confinement direction being a direction that is parallel with a cross-section including a first optical axis passing through the projective optical system and a normal line of the third reflective surface.

7. The virtual image display device according to claim 1, further comprising:

a wedge-shaped light transmitting member that has a transmissive surface that is opposite to the fourth reflective surface; and

a half mirror formed on the fourth reflective surface.

8. The virtual image display device according to claim 7,

the wedge-shaped light transmitting member further comprising a first surface and a second surface that are disposed in parallel with the first reflective surface and the second reflective surface, respectively.

9. The virtual image display device according to claim 1,

the light guiding member being integrally molded independently by injection molding.

10. The virtual image display device according to claim 9,

the light guiding member being molded from a thermal polymerization type resin material.

16. The virtual image display device according to claim 1, the projective optical system having an emission opening width along a vertical direction of an emission opening that is larger than an emission opening width along a horizontal direction of the emission opening, such that the emission opening has a substantially vertically-elongated shape.

11. A virtual image display device, comprising:

an image display device that emits image light;

a projective optical system that converts the image light into a parallel light beam; and

a light guiding member having a light guiding portion and a light emission portion,

the light guiding portion having a plurality of reflective surfaces forming a polyhedral shape with at least two corners that form end surfaces, the plurality of reflecting surfaces reflecting the parallel light beam,

at least one of the plurality of reflective surfaces defining an open end width, and

the projective optical system defining an emission opening width that is larger than the opening width of the at least one of the plurality of reflective surfaces.

12. The virtual image display device according to claim 11, at least another of the plurality of reflective surfaces having a plurality of layers.

13. A method of forming a virtual image, the method comprising:

emitting a two-dimensional illumination light with an illumination device housed in an image display device;

spatially modulating the illumination light to form an image light;

outputting an image signal to a liquid crystal display device to form a colored-image light;

emitting the colored-image light through a projective optical system that converts the colored-image light into a parallel light beam, the projective optical system having an emission opening width that is larger than an opening width of a third reflective surface in a direction that is parallel with a plane of a first reflective surface and is orthogonal to an intersection line between the first reflective surface and the third reflective surface;

passing the light beam through a light incidence portion having the third reflective surface that makes a predetermined angle with respect to the first reflective surface;

passing the light beam into a light guiding portion having the first reflective surface and also having a second reflective surface, the first and second reflective surfaces being disposed in parallel with each other, allowing the image light to be guided through a substantially total reflection;

reflecting the light beam by a plurality of reflective surfaces in the light guiding portion; and

emitting the light beam that is incident to an observer'"'"'s eye from a light emission portion of the light guiding portion guided by the light guiding member to the outside, the light emission portion having a fourth reflective surface that makes a predetermined angle with respect to the first reflective surface.

14. The method according to claim 13, wherein the image light passes through at least three lenses of the projective optical system.

15. A virtual image display device that forms a virtual image according to the method of claim 13.