Dithering methods and apparatus for wearable display device

• US 10,444,419 B2
• Filed: 08/22/2017
• Issued: 10/15/2019
• Est. Priority Date: 08/22/2016
• Status: Active Grant

• Current Assignee: Magic Leap, Inc.
• Original Assignee: Magic Leap, Inc.
• Inventors: Bhargava, Samarth, TeKolste, Robert D., Liu, Victor K., Peroz, Christophe, St. Hilaire, Pierre, Poliakov, Evgeni, Schaefer, Jason, Melli, Mauro, West, Melanie, Luo, Kang, Singh, Vikramjit, Xu, Frank Y.
• Primary Examiner(s): Bedtelyon, John
• Application Number:
  US15/683,702
• Publication Number:
  US 20180059304A1
• Time in Patent Office: 784 Days
• CPC Class Codes: G02B 2027/0114 comprising dichroic elements
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 2027/012 comprising devices for attenuating parasitic image effects
• CPC Class Codes: G02B 2027/0125 Field-of-view increase by wavefront division
• CPC Class Codes: G02B 2027/014 comprising information/image processing systems
• CPC Class Codes: G02B 2027/0174 holographic
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0018 with means for preventing ghost images anti-reflection coatings G02B1/11
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/0176 characterised by mechanical features
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 27/30 Collimators
• CPC Class Codes: G02B 5/1823 in an overlapping or superposed manner
• CPC Class Codes: G02B 5/1857 using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams
• CPC Class Codes: G02B 5/1866 Transmission gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence
• CPC Class Codes: G02B 5/1871 Transmissive phase gratings
• CPC Class Codes: G02B 5/3025 Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state G02B5/3008, G02B5/3016 take precedence
• CPC Class Codes: G02B 6/0016 : Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0023 : provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
• CPC Class Codes: G02B 6/0035 : provided on the surface of the light guide or in the bulk of it
• CPC Class Codes: G02B 6/0036 : 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0038 : Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/005 : provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0076 : Stacked arrangements of multiple light guides of the same or different cross-sectional area
• CPC Class Codes: G02B 6/29325 : of the slab or planar or plate like form, i.e. confinement in a single transverse dimension only integrated circuit planar waveguide arrangements G02B6/12007; specially adapted for lighting G02B6/0011
• CPC Class Codes: G02B 6/34 : utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: G02B 7/008 : with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation
• CPC Class Codes: G02C 11/10 : Electronic devices other than hearing aids
• CPC Class Codes: G02C 5/16 : resilient or with resilient parts
• CPC Class Codes: G06F 1/163 : Wearable computers, e.g. on a belt
• CPC Class Codes: G06F 1/203 : for portable computers, e.g. for laptops
• CPC Class Codes: G06F 1/206 : comprising thermal management
• CPC Class Codes: G06F 3/011 : Arrangements for interaction with the human body, e.g. for user immersion in virtual reality blind teaching G09B21/00
• CPC Class Codes: G06F 3/013 : Eye tracking input arrangements G06F3/015 takes precedence
• CPC Class Codes: G06F 3/147 : using display panels
• CPC Class Codes: G09G 2320/0233 : Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2330/045 : Protection against panel overheating
• CPC Class Codes: G09G 2340/0464 : Positioning
• CPC Class Codes: G09G 3/001 : using specific devices not provided for in groups G09G3/02 - G09G3/36, e.g. using an intermediate record carrier such as a film slide; Projection systems; Display of non-alphanumerical information, solely or in combination with alphanumerical information, e.g. digital display on projected diapositive as background slide projectors per se G03B23/00 = 42 HP
• CPC Class Codes: G09G 3/002 : to project the image of a two-dimensional display, such as an array of light emitting or modulating elements or a CRT
• CPC Class Codes: G09G 3/2003 : Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/2044 : using dithering
• CPC Class Codes: H04N 9/3102 : using two-dimensional electronic spatial light modulators micromechanical modulators as such G02B26/0833; liquid crystal modulators as such G02F1/13
• CPC Class Codes: H04N 9/3144 : Cooling systems cooling of liquid crystal cells in general G02F1/133382; cooling of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/16
• CPC Class Codes: H04N 9/3164 : using multiple light sources
• CPC Class Codes: H05K 7/20963 : Heat transfer by conduction from internal heat source to heat radiating structure H05K7/20972 takes precedence

Abstract

A device includes an input coupling grating having a first grating structure characterized by a first set of grating parameters. The input coupling grating is configured to receive light from a light source. The device also includes an expansion grating having a second grating structure characterized by a second set of grating parameters varying in at least two dimensions. The second grating structure is configured to receive light from the input coupling grating. The device further includes an output coupling grating having a third grating structure characterized by a third set of grating parameters. The output coupling grating is configured to receive light from the expansion grating and to output light to a viewer.

Claims

1. A device comprising:

an input coupling grating having a first grating structure characterized by a first set of grating parameters, wherein the input coupling grating is configured to receive light from a light source;

an expansion grating having a second grating structure characterized by a second set of grating parameters varying in at least two dimensions, wherein the second grating structure is configured to receive light from the input coupling grating, and wherein the second grating structure has a phase variation pattern that causes light beams to diffract with different phases at different portions along the second grating structure; and

an output coupling grating having a third grating structure characterized by a third set of grating parameters, wherein the output coupling grating is configured to receive light from the expansion grating and to output light to a viewer.

2. The device of claim 1, wherein the at least two dimensions include at least two of pitch, angle, apex angle, refractive index, height, and duty cycle.

3. The device of claim 1, wherein the second grating structure includes a film having a plurality of first regions characterized by a first refractive index and a plurality of second regions characterized by a second refractive index, and wherein the second refractive index is lower than the first refractive index.

4. The device of claim 1, wherein the phase variation pattern comprises a continuous phase variation pattern that includes at least one of a periodic or graded periodic pattern, a heuristic pattern, a computational hologram, or a random pattern.

5. The device of claim 1, wherein the second grating structure has a periodic structure.

6. The device of claim 1, wherein the second grating structure includes a plurality of regions having a first refractive index covered by a layer having a second refractive index, and wherein the second refractive index is lower than the first refractive index.

7. The device of claim 1, wherein the second grating structure comprises a first diffractive portion and a second diffractive portion adjacent to the first diffractive portion, wherein the first diffractive portion is configured to cause a first light beam to diffract with a first phase shift at a first diffraction order, wherein the second diffractive portion is configured to cause a second light beam to diffract with a second phase shift at a second diffraction order, wherein the second diffraction order is similar to the first diffraction order, and wherein the second phase shift is different than the first phase shift, and wherein a difference between the first phase shift and the second phase shift is associated with the phase variation pattern.

8. The device of claim 7, wherein the first diffractive portion is configured to deflect the first light beam into a first diffracted light beam at the first diffraction order, wherein the second diffractive portion is configured to deflect the first diffracted light beam into a second diffracted light beam at a negative order of the second diffraction order, and wherein the second diffracted light beam has a phase change as compared to the first light beam, the phase change being the first phase shift minus the second phase shift.

9. An optical structure comprising:

a waveguide layer lying at least partially in a plane defined by a first dimension and a second dimension; and

a diffractive element coupled to the waveguide layer and operable to diffract light in the plane, wherein the diffractive element is characterized by a set of diffraction parameters that vary in at least the first dimension and the second dimension, and wherein the diffractive element has a phase variation pattern that causes light beams to diffract with different phases at different portions along the diffractive element.

10. The optical structure of claim 9, wherein the set of diffraction parameters vary continuously in at least the first dimension and the second dimension.

11. The optical structure of claim 9, wherein the set of diffraction parameters comprises at least one of pitch, grating vector angle, duty cycle, height variation, refractive index variation, or blaze or apex angle.

12. The optical structure of claim 9, wherein the diffractive element is characterized by a random variation in height and spacing of projections extending in a third dimension orthogonal to the first dimension and the second dimension.

13. The optical structure of claim 9, wherein the diffractive element includes a film having a plurality of first regions characterized by a first refractive index and a plurality of second regions characterized by a second refractive index, and wherein the second refractive index is lower than the first refractive index.

14. The optical structure of claim 9, wherein a period of the phase variation pattern is within a range from 100 μ

m to 5 cm.

15. The optical structure of claim 9, wherein the phase variation pattern comprises a continuous phase variation pattern that includes at least one of a periodic or graded periodic pattern, a heuristic pattern, a computational hologram, or a random pattern.

16. The optical structure of claim 9, wherein the diffractive element includes a plurality of regions having a first refractive index covered by a layer having a second refractive index, and wherein the second refractive index is lower than the first refractive index.

17. The optical structure of claim 9, wherein the diffractive element comprises a first diffractive portion and a second diffractive portion adjacent to the first diffractive portion, wherein the first diffractive portion is configured to cause a first light beam to diffract with a first phase shift at a first diffraction order, wherein the second diffractive portion is configured to cause a second light beam to diffract with a second phase shift at a second diffraction order, wherein the second diffraction order is similar to the first diffraction order, and wherein the second phase shift is different than the first phase shift, and wherein a difference between the first phase shift and the second phase shift is associated with the phase variation pattern.

18. The optical structure of claim 17, wherein the first diffractive portion is configured to deflect the first light beam into a first diffracted light beam at the first diffraction order, wherein the second diffractive portion is configured to deflect the first diffracted light beam into a second diffracted light beam at a negative order of the second diffraction order, and wherein the second diffracted light beam has a phase change as compared to the first light beam, the phase change being the first phase shift minus the second phase shift.