Scanner-illuminated LCOS projector for head mounted display

• US 10,642,045 B2
• Filed: 11/01/2017
• Issued: 05/05/2020
• Est. Priority Date: 04/07/2017
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Wall, Richard Andrew, Miller, Joshua Owen, Vallius, Tuomas, Maimone, Andrew, Kollin, Joel Steven
• Primary Examiner(s): Kakalec, Kimberly N.
• Application Number:
  US15/800,993
• Publication Number:
  US 20180292654A1
• Time in Patent Office: 916 Days
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 2027/0123 comprising devices increasing the field of view
• CPC Class Codes: G02B 2027/0125 Field-of-view increase by wavefront division
• CPC Class Codes: G02B 2027/0174 holographic
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/4205 having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant
• CPC Class Codes: G02F 1/133616 Front illuminating devices
• CPC Class Codes: G02F 1/136277 formed on a semiconductor substrate, e.g. of silicon
• CPC Class Codes: G03B 21/006 using LCD's
• 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 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20
• CPC Class Codes: H04N 9/317 Convergence or focusing systems electronic adjustment of convergence H04N9/3185; convergence or focusing arrangements for cathode ray tubes H04N9/28; means for automatic focusing of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/53

Abstract

A light engine comprises a liquid crystal on silicon (LCOS) panel that is operated in combination with illumination and imaging optics to project high-resolution virtual images into a waveguide-based exit pupil expander (EPE) that provides an expanded exit pupil in a near-eye display system. In an illustrative example, the illumination optics comprise a laser that produces illumination light that is reflected by a MEMS (micro-electromechanical system) scanner using raster scanning to post-scan optics including a microlens array (MLA) and one or more collimating or magnifying lenses before impinging on the LCOS panel. The LCOS panel operates in reflection in combination with imaging optics, including one or more of beam-steering mirror and beam splitter, to couple virtual image light from the LCOS panel into the EPE.

Claims

1. An optical display system configured to show images within a field of view (FOV), comprising:

a waveguide operable as a near-eye display comprising one or more diffractive optical elements (DOEs) including an in-coupling DOE configured for in-coupling image light to the waveguide; and

a light engine comprising a micro-display, illumination optics, and image optics, in which the micro-display projects the image light into the waveguide at the in-coupling DOE,

wherein the illumination optics include

an illumination light source, comprising one of laser or LED (light emitting diode), and a MEMS (micro-electro mechanical system) scanner configured for raster scanning light from the illumination light source to illuminate the micro-display.

2. The optical display system of claim 1 in which the MEMS scanner is a dual-axis scanner operated in reflection using a moveable reflective surface and further is arranged for fast scanning along a first axis and slow scanning along a second axis.

3. The optical display system of claim 1 in which the waveguide further includes at least one intermediate DOE and an out-coupling DOE, wherein the at least one intermediate DOE provides exit pupil expansion in a first direction of the FOV and the out-coupling DOE provides exit pupil expansion in a second direction of the FOV.

4. The optical display system of claim 1 in which the micro-display comprises one of an LCOS (liquid crystal on silicon) panel operating in reflection, a pixel array, or an image source using one or more of light emitting diode (LED), OLED (organic light emitting diode), liquid crystal (LC), or digital light processing (DLP).

5. The optical display system of claim 4 further including post-scan optics in an optical path between the MEMS scanner and the LCOS panel.

6. The optical display system of claim 5 in which the post-scan optics include one or more of microlens array, magnifying lens, or collimating lens.

7. A head mounted display (HMD) device including a chain of optical elements configured to display images to a user'"'"'s eye within a field of view (FOV) having first and second directions with improved non-uniformity, the optical elements comprising:

an imaging panel that produces virtual images;

illumination optics configured to provide illumination light to the imaging panel from a source using a MEMS (micro-electro mechanical system) device operating to raster scan illumination light onto the imaging panel;

a combiner comprising one of numerical aperture (NA) converter or exit pupil expander (EPE); and

imaging optics configured to couple image light from the imaging panel into the combiner, wherein illumination light propagates on a path along the chain of the optical elements comprising the illumination optics, the imaging panel, imaging optics, and combiner in series, such that the combiner is last in the series to thereby display images on the user'"'"'s eye.

8. The HMD device of claim 7 wherein the imaging panel operates in one of transmission or reflection.

9. The HMD device of claim 7 wherein the imaging optics include one of birdbath imaging optics or direct eyepiece optics.

10. The HMD device of claim 7 wherein the MEMS device is operated to provide raster scanning through a fast axis and a slow axis.

11. The HMD device of claim 7 wherein the EPE comprises waveguide-based display comprising one or more diffractive optical elements (DOEs) configured for in-coupling light from the imaging panel, expanding an exit pupil of the image light, and out-coupling the image light from the display with expanded exit pupil.

12. The HMD device of claim 7 in which the imaging optics further comprise magnifying or collimating optics to provide increased exit pupil and field of view of the displayed images.

13. A device configured to control image light associated with virtual images within a field of view (FOV), comprising:

an imager configured to generate the virtual images;

a waveguide including an in-coupling diffractive optical element (DOE) configured to in-couple virtual image light into the waveguide, at least one intermediate DOE configured to expand an exit pupil of the image light in a first direction of the FOV, and an out-coupling DOE configured to expand the exit pupil of the image light in a second direction of the FOV and further configured to out-couple image light out of the waveguide to an eye of a user of the device; and

a MEMS (micro-electro mechanical system) scanner configured to perform raster scanning of illumination light from an illumination light source to illuminate the imager to thereby generate the virtual image light.

14. The device of claim 13 further comprising birdbath imaging optics comprising one or more of fold mirror or polarization beam splitter and one or more lenses configured for magnifying or collimating the virtual image light.

15. The device of claim 13 in which the imager is a micro-display.

16. The device of claim 13 in which the illumination light source is a laser.

17. The device of claim 13 in which the virtual images are color images using different colors, and the MEMS scanner is operated to modulate per-color intensity.

18. The device of claim 17 in which the imager is operated using an RGB (red, green, blue) color model.

19. The device of claim 13 in which the waveguide is configured as a near-eye display.

20. The device of claim 13 in which the MEMS scanner and imager are operated as a pico projector.