Virtual image display device

• US 8,837,880 B2
• Filed: 10/03/2011
• Issued: 09/16/2014
• Est. Priority Date: 10/08/2010
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Takeda, Takashi, Takagi, Masayuki, Miyao, Toshiaki, Totani, Takahiro, Komatsu, Akira
• Primary Examiner(s): Connelly, Michelle R
• Application Number:
  US13/251,614
• Publication Number:
  US 20120086625A1
• Time in Patent Office: 1,079 Days
• Field of Search: None
• US Class Current: 385/33
• CPC Class Codes: G02B 2027/011 comprising device for correcting geometrical aberrations, distortion
• CPC Class Codes: G02B 2027/0121 Parasitic image effect attenuation by suitable positioning of the parasitic images
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 30/27 involving lenticular arrays
• 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 6/0006 Coupling light into the fibre in general G02B6/4298
• CPC Class Codes: G02B 6/0008 the light being emitted at the end of the fibre

Abstract

The invention is directed to provide a virtual image display device capable of setting the aspect ratio of the image light entering the eyes of the observer as a virtual image to a desired state while fulfilling the design limitations. In the invention, the aspect ratio of the virtual image can be converted to the aspect ratio (16:9) laterally longer than the aspect ratio (4:3) of the image area due to the conversion in the aspect ratio conversion optical system. Thus, the aspect ratio of the image light to be recognized by the eye of the observer as a virtual image can be adjusted to a desired state even in the case in which, for example, the lateral width of the image forming device with respect to the whole of the virtual image display device is limited by a design requirement.

Claims

1. A virtual image display device comprising:

an image display device adapted to form an image light;

a projection optical system adapted to form a virtual image by the image light emitted from the image display device; and

a light guide device including

a light entrance section adapted to take in the image light having passed through the projection optical system,

a light guide section adapted to guide the image light taken in from the light entrance section using total reflection on first and second total reflection surfaces extending so as to be opposed to each other, and

a light exit section adapted to take out the image light having passed through the light guide section,

wherein the projection optical system includes a toric optical system adapted to perform adjustment of an aspect ratio with respect to a virtual image in an image area of the image display device, the toric optical system having a plurality of lenses with flat surfaces facing an image display device side of the projection optical system, and curved surfaces on a light guide device side of the projection optical system.

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

the toric optical system performs conversion of an aspect ratio with respect to the virtual image so as to increase a lateral ratio for an observer taking an aspect ratio of display in the image display device as a reference.

3. The virtual image display device according to claim 2, wherein

the toric optical system performs either one of

an expansion conversion with respect to a first direction corresponding to the lateral direction for the observer, and

a contraction conversion with respect to a second direction perpendicular to the first direction.

4. The virtual image display device according to claim 1, wherein

the image forming device is disposed on an ear side of an observer observing the image light, and

the light guide device guides the image light along a lateral direction for the observer.

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

in the image display device, an aspect ratio of a shape of each of a plurality of pixels disposed in the image area is inverse to a ratio of the conversion by the toric optical system.

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

in the image display device, each the pixels is composed of three pixel segments arranged in a line.

7. The virtual image display device according to claim 6, wherein

the three pixel segments respectively have three colors of RGB, and are arranged in a line along the lateral direction for the observer.

8. The virtual image display device according to claim 5, wherein

in the image display device, each the pixels is composed of four pixel segments arranged in a 2×

2 matrix.

9. The virtual image display device according to claim 8, wherein

the four pixel segments are assigned with three colors of RGB.

10. The virtual image display device according to claim 8, wherein

the four pixel segments are assigned with four colors obtained by adding another color to the three colors of RGB.

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

an image processing section adapted to perform a conversion process of an aspect ratio, which is inverse to a conversion ratio of an aspect ratio of the image light by the toric optical system, with respect to an image signal input to the image display device in accordance with the conversion ratio of the aspect ratio of the image light by the toric optical system.

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

a drive mechanism adapted to move the toric optical system on a light path of the image light.

13. The virtual image display device according to claim 1, wherein

the toric optical system includes a pair of cylindrical lenses respectively having concave and convex shapes and disposed in a direction opposed to a light entrance surface of the light guide device adapted to take in the image light, and a conversion ratio of an aspect ratio of the image light is adjusted by changing locations of the cylindrical lenses.

14. The virtual image display device according to claim 1, wherein

the light guide section includes a first reflecting surface and a second reflecting surface disposed in parallel to each other, and adapted to make light guide by total reflection possible,

the light entrance section includes a third reflecting surface forming a predetermined angle with the first reflecting surface, and

the light exit section includes a fourth reflecting surface forming a predetermined angle with the first reflecting surface.

15. The virtual image display device according to claim 14, wherein

the light guide device has a hologram element in at least one of the third reflecting surface and the fourth reflecting surface.

16. The virtual image display device according to claim 1, wherein

the light guide device further includes an angle conversion section having a plurality of reflecting surfaces extending in a predetermined direction, and bending the image light guided by total reflection on the first and second total reflection surfaces of the light guide section toward the light exit section using the plurality of reflecting surfaces.

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

wherein the image display device is adapted to form image light comprised of a plurality of light rays propagating in different directions, and

wherein the projection optical system includes a collimating lens disposed between the toric optical system and the image display device that parallelizes different ones of the plurality of light rays into differently parallel light ray groups.