Turning light pipe for a pupil expansion system and method

• US 10,088,675 B1
• Filed: 05/18/2015
• Issued: 10/02/2018
• Est. Priority Date: 05/18/2015
• Status: Active Grant

• Current Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Original Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Inventors: Brown, Robert D., Stanley, James H., Stratton, Eric P., Yu, Ming
• Primary Examiner(s): Chwasz, Jade R
• Application Number:
  US14/715,332
• Time in Patent Office: 1,233 Days
• Field of Search: 359 13, 359 34, 359 35, 359 15
• CPC Class Codes: G02B 17/0884 having a pupil corrector
• CPC Class Codes: G02B 2027/0123 comprising devices increasing the field of view
• CPC Class Codes: G02B 2027/0154 with movable elements
• 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 27/0176 characterised by mechanical features
• CPC Class Codes: G02B 27/30 Collimators
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces

Abstract

A display system includes a light pipe including elongated surfaces and an input coupler. The light pipe is configured to provide an image received by the input coupler and expand the image in a first direction through one of the elongated surfaces. The display also includes a waveguide including an output grating, a first surface, a second surface, and a side surface. The first surface and the second surface have a larger area than the side surface, the output grating being configured to provide the image expanded in a second direction. The second direction is different than the first direction. The image enters the waveguide from the one of the elongated surfaces at the side surface.

Claims

1. A near eye optical display, comprising:

a light pipe comprising a plurality of elongated surfaces and an input coupler, the light pipe being configured to provide an image received by the input coupler and expand the image in a first direction through one of the elongated surfaces, wherein light associated with the image travels through the light pipe by striking three or more of the elongated surfaces; and

a waveguide comprising an output grating, a first surface, a second surface, and a side surface, the first surface and the second surface having a larger area than the side surface, the output grating being configured to provide the image expanded in a second direction, the second direction being different than the first direction, wherein the image enters the waveguide from the one of the elongated surfaces at the side surface, wherein the three or more elongated surfaces comprise at least a third surface, a fourth surface and a fifth surface, the third surface and the fourth surface being parallel and the fifth surface being non-parallel to the third surface and the fourth surface and connecting the fourth surface to the third surface.

2. The near eye optical display of claim 1, wherein the first direction is orthogonal to the second direction.

3. The near eye optical display of claim 1, wherein the one elongated surface, the side surface, the first surface and the second surface are planar surfaces.

4. The near eye optical display of claim 1, further comprising:

a collimating lens system for providing light from a display source to the input coupler, the collimating lens system being a catadioptric system.

5. The near eye optical display of claim 1, further comprising:

a gradient reflective coating disposed on the one elongated surface.

6. The near eye optical display of claim 5, further comprising a beam splitting coating between the input coupler and the gradient reflective coating.

7. The near eye optical display of claim 1, wherein the input coupler is a volume hologram or a surface relief grating.

8. The near eye optical display of claim 1, wherein the first direction is horizontal and the second direction is vertical.

9. The near eye optical display of claim 1, wherein gratings associated with the input coupler are parallel to the output grating and wherein the output grating is not parallel to the side surface.

10. The near eye optical display of claim 1, wherein the output grating is disposed in a relationship to an angle of the waveguide with respect to the light pipe.

11. A method of displaying information, the method comprising:

receiving light in a light pipe having a surface with a non-gradient or gradient reflection coating and at least three elongated surfaces, the light striking the at least three elongated surfaces and traveling at least partially by total internal reflection within the light pipe;

receiving the light from the surface with the non-gradient or gradient reflective coating in a waveguide having a first surface and a second surface;

providing the light to an output grating via total internal reflection between the first surface and the second surface,

providing the light from the waveguide via the output grating, where the light is provided with dual axis pupil expansion with respect to the light received in the light pipe.

12. The method of claim 11, wherein the output grating is a volume hologram or surface relief grating.

13. The method of claim 11, further comprising beam splitting the light received in the light pipe before the light enters the waveguide.

14. The method of claim 11, wherein the light pipe includes an input coupler.

15. The method of claim 14, wherein the input coupler is a surface relief grating.

16. An apparatus for providing an image, the apparatus comprising:

a light pipe comprising a non-gradient or gradient reflective coating and at least four elongated surfaces, each elongated surface connecting to at least two other of the elongated surfaces, the non-gradient or gradient reflective coating is disposed on one of the at least four elongated surfaces and light associated with the image strikes at least three of the at least four elongated surfaces as the light travels in a corkscrew or helical fashion within the light pipe; and

a waveguide comprising an input surface and an output surface, the input surface being non-planar with respect to the output surface, wherein the light from the non-gradient or gradient reflective coating is received at the input surface and the light is ejected from the output surface of the waveguide by an output grating.

17. The apparatus of claim 16, wherein the apparatus provides dual axis pupil expansion.

18. The apparatus of claim 16, wherein the light pipe comprises an input grating.

19. The apparatus of claim 16, further comprising a first beam splitting coating disposed in the waveguide and a second beam splitting coating disposed in the light pipe.

20. The apparatus of claim 16, wherein the light pipe has a rectangular prismatic shape.