Near-eye display device, augmented reality glasses including same, and operating method therefor
A near-eye display device, an augmented reality device including the near-eye display device, and an operation method of the near-eye display device are provided. The near-eye display device includes a first expanding waveguide including a first expanding diffractive grating and a second waveguide including a second diffractive grating. The first expanding diffractive grating and the second diffractive grating are located on different planes.
1. A near-eye display device comprising:
a projection system configured to project light to display an image;
a first expanding waveguide including a first surface, a second surface opposite to the first surface, and a first expanding diffractive grating disposed on one of the first surface or the second surface, wherein the light projected from the projection system is incident upon the first surface or the second surface; and
a second waveguide upon which light emitted from the first expanding waveguide is incident,
wherein the second waveguide includes a second diffractive grating,
wherein the light from the projection system is incident upon the first expanding diffractive grating included in the first expanding waveguide to form (−1)-order diffraction, 0-order diffraction, and (+1)-order diffraction from respective diffractions of light beams,
wherein the first expanding diffractive grating and the second diffractive grating are located on different planes so that 0-order diffracted light emitted from the first expanding waveguide is incident upon the second waveguide,
wherein (−1)-order diffracted light and (+1)-order diffracted light are extended in the first expanding waveguide due to internal total reflection,
wherein the extended (−1)-order diffracted light and the extended (+1)-order diffracted light are fed back to the first expanding diffractive grating, and the extended (−1)-order diffracted light and the extended (+1)-order diffracted light are incident upon different locations on the first expanding diffractive grating, and
wherein new (−1)-order diffraction, new 0-order diffraction, and new (+1)-order diffraction are formed from each of the extended (−1)-order diffracted light and the extended (+1)-order diffracted light.
2. The near-eye display device of claim 1 ,
wherein the light projected from the projection system is incident upon the first expanding waveguide, and
wherein an angle at which the light is incident upon the first expanding diffractive grating has a range of 0 to 90 degrees with respect to normal to a surface of the first expanding waveguide.
3. The near-eye display device of claim 1 , wherein a grating line of the first expanding diffractive grating is arranged along a projection of light from the projection system onto the first expanding diffractive grating.
4. The near-eye display device of claim 1 , wherein an acute angle between a projection of a main light beam of the projection system onto a plane of the first expanding waveguide and a grating line of the first expanding diffractive grating has a range of (+) 30 degrees to (−) 30 degrees.
5. The near-eye display device of claim 1 , wherein the first expanding diffractive grating is located on the first surface of the first expanding waveguide upon which the light projected from the projection system is incident.
6. The near-eye display device of claim 5 , wherein the second surface of the first expanding waveguide includes a mirror coating.
7. The near-eye display device of claim 1 , wherein the second waveguide includes a first region upon which the light is incident, a second region where the light does not enter an eye of a user, and a third region where the light enters a pupil of the eye.
8. The near-eye display device of claim 7 , wherein the near-eye display device is configured so that diffraction does not occur in the second region of the second waveguide.
9. The near-eye display device of claim 7 , wherein the second diffractive grating is configured to have a relationship of a diffraction efficiency of the first region>a diffraction efficiency of the third region>a diffraction efficiency of the second region.
10. The near-eye display device of claim 7 , wherein the second diffractive grating is configured to have a relationship of a diffraction efficiency of the first region>a diffraction efficiency of the second region=a diffraction efficiency of the third region.
11. The near-eye display device of claim 7 , wherein the first region of the second diffractive grating has high diffraction efficiency and the second region and the third region have gradient diffraction efficiency.
12. The near-eye display device of claim 1 , wherein the first expanding waveguide and the second waveguide constitute a monolithic curve-shaped waveguide.
13. The near-eye display device of claim 1 ,
wherein the second surface of the first expanding waveguide includes a mirror coating formed thereon, and
wherein the first surface of the first expanding waveguide includes the first expanding diffractive grating and is free from the mirror coating.
14. The near-eye display device of claim 1 , wherein the 0-order diffracted light emitted from the first expanding waveguide is emitted from the first expanding waveguide at a same angle as an angle at which the light is incident upon the first expanding waveguide.
15. Augmented reality glasses comprising:
an element for a left eye and an element for a right eye,
wherein at least one of the element for the left eye or the element for the right eye comprises a projection system, a first expanding waveguide including a first surface, and a second surface opposite to the first surface,
wherein light projected from the projection system is incident upon the first surface, a first expanding diffractive grating included in the first expanding waveguide, a second waveguide upon which light emitted from the first expanding waveguide is incident, and a second diffractive grating included in the second waveguide,
wherein the light from the projection system is incident upon the first expanding diffractive grating included in the first expanding waveguide to form (−1)-order diffraction, 0-order diffraction, and (+1)-order diffraction from respective diffractions of light beams,
wherein the first expanding diffractive grating and the second diffractive grating are located on different planes so that 0-order diffracted light output by the first expanding waveguide is incident upon the second waveguide,
wherein (−1)-order diffracted light and (+1)-order diffracted light are extended in the first expanding waveguide due to internal total reflection,
wherein the extended (−1)-order diffracted light and the extended (+1)-order diffracted light are fed back to the first expanding diffractive grating, and the extended (−1)-order diffracted light and the extended (+1)-order diffracted light are incident upon different locations on the first expanding diffractive grating, and
wherein new (−1)-order diffraction, new 0-order diffraction, and new (+1)-order diffraction are formed from each of the extended (−1)-order diffracted light and the extended (+1)-order diffracted light.
16. The augmented reality glasses of claim 15 , wherein the element for the left eye is integral with the element for the right eye.
17. The augmented reality glasses of claim 15 , wherein the element for the left eye is separate from the element for the right eye.
18. The augmented reality glasses of claim 15 ,
wherein the first expanding waveguide includes a plurality of regions, and
wherein at least two of the plurality of regions have different diffractive values.
19. An operation method of a near-eye display device, the operation method comprising:
projecting light from a projection system onto a first expanding diffractive grating;
diffracting the light projected from the projection system onto the first expanding diffractive grating to form a (−1)-order diffraction, a 0-order diffraction, and a (+1)-order diffraction from respective diffractions of light beams incident upon the first expanding diffractive grating;
outputting 0-order diffracted light from a first expanding waveguide and inputting the 0-order diffracted light to a second waveguide;
extending (−1)-order diffracted light and (+1)-order diffracted light in the first expanding waveguide due to internal total reflection, feeding the extended (−1)-order diffracted light and the extended (+1)-order diffracted light back to the first expanding diffractive grating, and making the extended (−1)-order diffracted light and the extended (+1)-order diffracted light be incident upon different locations on the first expanding diffractive grating; and
forming new (−1)-order diffraction, new 0-order diffraction, and new (+1)-order diffraction from each of the (−1)-order diffracted light and the (+1)-order diffracted light.
20. The operation method of claim 19 ,
wherein each 0-order diffracted light incident upon the second waveguide passes a second diffractive grating via the second waveguide,
wherein diffraction of each ray incident upon the second diffractive grating forms (−1)-order diffraction, 0-order diffraction, and (+1)-order diffraction, and
wherein the (+1)-order diffraction is reflected by a surface of the second waveguide opposite to a surface of the second waveguide facing an eye and is incident again upon the second diffractive grating.