DISPLAY APPARATUS AND SYSTEM AND DISPLAY METHOD THEREOF

• US 20140293434A1
• Filed: 06/03/2014
• Published: 10/02/2014
• Est. Priority Date: 12/06/2011
• Status: Active Grant

• Current Assignee: Beijing NED+AR Display Technology Co., Ltd.
• Original Assignee: Beijing Institute of Technology
• Inventors: CHENG, Dewen, WANG, Yongtian, LIU, Yue
• Granted Patent: US 9,052,505 B2
• Time in Patent Office: Days
• US Class Current: 359/630
• CPC Class Codes: G02B 2027/0114 comprising dichroic elements
• CPC Class Codes: G02B 2027/0125 Field-of-view increase by wavefront division
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 5/04 Prisms
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G06T 19/006 Mixed reality object pose determination, tracking or camera calibration for mixed reality G06T7/00
• CPC Class Codes: H04N 13/144 for flicker reduction
• CPC Class Codes: H04N 13/344 with head-mounted left-right displays
• CPC Class Codes: H04N 13/346 using prisms or semi-transparent mirrors
• CPC Class Codes: H04N 13/363 using image projection screens volumetric display H04N13/388
• CPC Class Codes: H04N 2213/001 Constructional or mechanical details

Abstract

A display apparatus includes a planar waveguide optical element, a projection optical system, and a microdisplay device. By including free-form optics and waveguide technology, the volume and weight of the display apparatus can be reduced, and an optical system can be realized with improved image quality, structure, and performance parameters.

Claims

1. A display apparatus, comprising:

a waveguide optical device;

a projection optical system including an optical free-form surface; and

a microdisplay device;

wherein the projection optical system is coupled to the waveguide optical device through an inclined optical path.

2. The display apparatus of claim 1, wherein the waveguide device comprises a planar waveguide optical element comprising:

a rectangular prism input coupling end;

a dichroic mirror any output coupling end;

wherein parameters of the waveguide include;

a plate thickness d;

an angle θ

between the dichroic mirror and a plane;

a distance h1 between the input coupling end and the output coupling end;

a distance h2 between dichroic mirrors of the array;

a glass refractive index n;

wherein of the waveguide device;

the dichroic mirror any has mirrors parallel to each other;

the angle θ

satisfies 20°

≦

θ

≦

40°

;

the distance h2 between dichroic mirrors satisfies h2=d/tan (θ

);

the refractive index n satisfies 1.4≦

n≦

1.8;

the thickness d satisfies 1.4≦

d≦

3.6 mm.

3. The display apparatus of claim 2, wherein the planar waveguide optical element output coupling end comprises at least two parallel dichroic mirrors.

4. The display apparatus of claim 2, wherein the planar waveguide optical element input coupling end comprises a reflector or a triangular prism.

5. The display apparatus of claim 1, wherein the projection optical system comprises a light engine system and a free-form surface prism imaging system.

6. The display apparatus of claim 1, wherein the projection optical system comprises a prism having at least one optical free-form curved surface.

7. The display apparatus of claim 6, wherein the free-form surface prism comprises at least three free-form curved surfaces, with non-overlapping exit pupil positions in two orthogonal directions, with a thickness mm, and a width 10 mm.

8. The display apparatus of claim 2, wherein the projection optical system has a short exit pupil substantially overlapping with the input coupling end, and a long exit pupil substantially overlapping with an exit pupil of the waveguide device.

9. The display apparatus of claim 5, wherein the light engine comprises a PBS beam splitter, a ¼

wave plate, a reflector, and an LED light source.

10. The display apparatus of claim 7, wherein if the planar waveguide optical element input coupling end comprises a reflector, the input coupling end substantially overlapping with the free-form surface prism exit pupil, and wherein following conditions are satisfied to thereby reduce stray light:

11. A near-eye display system comprising a display apparatus as described in claim 1, wherein the microdisplay device comprises:

a first and a second microdisplays, configured to display respectively a near and a far observation images relative to a user eye, or display respectively a far and a near observation images relative to the eye, wherein the first and second observation images being displayed have different distances to the user eye, but with substantially fields of view areas being covered, the first image weighted toward describing in a three-dimensional rendering of a scene an object having a nearer depth, the second imaged weighted toward describing in the three-dimensional rendering of the scene an object having a farther depth;

wherein the projection optical system comprises;

a first curved optical surface prism configured to magnify and place an image displayed by the first microdisplay at a distance relatively close to the user eye;

a second curved optical surface prism configured to magnify and place an image displayed by the first microdisplay at a distance relatively far from the user eye;

the first prism and the second prism surface include a pair of optical surfaces having same shape parameters but opposite signs, i.e., a second optical surface of the first prism and a first optical surface of the second prism, through the two surfaces glued together a seamless connection between the two prisms is achieved, wherein the connection is coated with a half-permeable membrane to achieve an integration of two focal plane images.

12. The near-eye display system of claim 11, wherein the first prism comprises three optical free-form surfaces, wherein:

at least one light reflection occurs at one of the optical free-form surfaces, the second optical surface is a concave reflecting surface, a space surrounded by the three optical free-form surfaces is filled with glass or resin optical material having a refractive index greater than 1.4, the optical surfaces include one of a spherical surface, an aspherical surface, or a free-form surface such as a complex curvature XY polynomial surface;

light emitted from the first microdisplay enters into the first prism through the third optical surface, reflected by the first optical surface to the second optical surface, and reflected by the second optical surface and transmits through the first optical surface to the user eye.

13. The near-eye display system of claim 11, wherein the second prism comprises three optical free-form surfaces, wherein:

at least one light reflection occurs at one of the optical free-form surfaces, a space surrounded by the three optical free-form surfaces is filled with glass or resin optical material having a refractive index greater than 1.4, the optical surfaces include one of a spherical surface, an aspherical surface, a free-form surface, or a complex curvature XY polynomial surface;

light emitted from the first microdisplay enters into the second prism through the third optical surface, reflected by the second optical surface to the first optical surface, and transmits through the second and the first optical surfaces of the first prism to arrive at the exit pupil of the near-eye display system.

14. The near-eye display system of claim 11, wherein the first prism comprises three optical free-form surfaces, wherein:

at least one light reflection occurs at one of the optical free-form surfaces, a space surrounded by the three optical free-form surfaces is filled with glass or resin optical material having a refractive index greater than 1.4, the optical surfaces include one of a spherical surface, an aspherical surface, a free-form surface, or a complex curvature XY polynomial surface;

light emitted from the first microdisplay enters into the first prism through the third optical surface, reflected by the first optical surface to the second optical surface, reflected by the second optical surface and transmits through the first optical surface to enter the user eye.

15. The near-eye display system of claim 11, wherein the second prism comprises three optical free-form surfaces, wherein:

at least one light reflection occurs at one of the optical free-form surfaces, a space surrounded by the three optical free-form surfaces is filled with glass or resin optical material having a refractive index greater than 1.4, the optical surfaces include one of a spherical surface, an aspherical surface, a free-form surface, or a complex curvature XY polynomial surface;

light emitted from the second microdisplay enters into the second prism through the third optical surface, is reflected by the first optical surface to the second optical surface, further reflected and reaches the first optical surface for transmission, and transmits through the second and the first optical surfaces of the first prism to arrive at the exit pupil of the near-eye display system.

16. The near-eye display system of claim 11, wherein the first prism comprises three optical free-form surfaces, wherein:

at least one light reflection occurs at one of the optical free-form surfaces, a space surrounded by the three optical free-form surfaces is filled with glass or resin optical material having a refractive index greater than 1.4, the optical surfaces include one of a spherical surface, an aspherical surface, a free-form surface, or a complex curvature XY polynomial surface;

light emitted from the first microdisplay enters into the first prism through the third optical surface, is reflected by the second optical surface to the first optical surface, and transmits through the first optical surface to arrive at the exit pupil of the near-eye display system.

17. The near-eye display system of claim 11, wherein the second prism comprises three optical free-form surfaces, wherein:

at least one light reflection occurs at one of the optical free-form surfaces, a space surrounded by the three optical free-form surfaces is filled with glass or resin optical material having a refractive index greater than 1.4, the optical surfaces include one of a spherical surface, an aspherical surface, or a free-form surface;

light emitted from the second microdisplay enters into the second prism through the third optical surface, is reflected by the first optical surface to the second optical surface, further reflected and reaches the first optical surface for transmission, and transmits through the second and the first optical surfaces of the first prism to arrive at the exit pupil of the near-eye display system.

18. The near-eye display system of claim 11, wherein the first prism comprises three optical free-form surfaces, wherein:

at least one light reflection occurs at one of the optical free-form surfaces, a space surrounded by the three optical free-form surfaces is filled with glass or resin optical material having a refractive index greater than 1.4, the optical surfaces include one of a spherical surface, an aspherical surface, or a free-form surface;

light emitted from the first microdisplay enters into the first prism through the third optical surface, is reflected by the second optical surface to the first optical surface, and transmits through the first optical surface to arrive at the exit pupil of the near-eye display system.

19. The near-eye display system of claim 11, wherein the second prism comprises three optical free-form surfaces, wherein:

at least one light reflection occurs at one of the optical free-form surfaces, a space surrounded by the three optical free-form surfaces is filled with glass or resin optical material having a refractive index greater than 1.4, the optical surfaces include one of a spherical surface, an aspherical surface, or a free-form surface;

light emitted from the second microdisplay enters into the second prism through the third optical surface, is reflected by the second optical surface to the first optical surface, and transmits through the second and the first optical surfaces of the first prism to arrive at the exit pupil of the near-eye display system.

20. The display apparatus of claim 1, wherein the inclined light path is a non-rectangular light path.