Compact edge illuminated diffractive display

• US 20130271731A1
• Filed: 04/17/2012
• Published: 10/17/2013
• Est. Priority Date: 04/17/2012
• Status: Active Grant

• Current Assignee: DigiLens Inc
• Original Assignee: Jonathan David Waldern, Milan Momcilo Popovich
• Inventors: Popovich, Milan Momcilo, Waldern, Jonathan David
• Granted Patent: US 9,075,184 B2
• Time in Patent Office: Days
• US Class Current: 353/31
• CPC Class Codes: G01J 3/1895 using fiber Bragg gratings or gratings integrated in a waveguide
• CPC Class Codes: G02B 6/02076 Refractive index modulation gratings, e.g. Bragg gratings
• CPC Class Codes: G02F 1/225 in an optical waveguide structure
• CPC Class Codes: G03B 21/005 Projectors using an electronic spatial light modulator but not peculiar thereto
• CPC Class Codes: G03F 7/70316 Details of optical elements, e.g. of Bragg reflectors, extreme ultraviolet [EUV] multilayer or bilayer mirrors or diffractive optical elements
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• 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 9/3173 wherein the projection device is specially adapted for enhanced portability

Abstract

There is provided a projection display device comprising: a light source, an SBG device comprising a multiplicity of separately SBG elements sandwich between transparent substrate to which transparent electrodes have been applied. The substrates function as a light guide. A least one transparent electrode comprises plurality of independently switchable transparent electrodes elements, each electrode element substantially overlaying a unique SBG element. Each SBG element encodes image information to be projected on an image surface. Light coupled into the light guide, undergoes total internal reflection until diffracted out to the light guide by an activated SBG element. The SBG diffracts light out of the light guide to form an image region on an image surface when subjected to an applied voltage via said transparent electrodes.

Claims

1. A projection display for projecting image light onto an image surface, said display comprising:

a first light source emitting light of a first wavelength;

a first SBG array comprising a multiplicity of separately switchable SBG elements disposed in a single layer;

transparent substrates sandwiching said SBG array, said substrates together functioning as a first light guide;

transparent electrodes applied to opposing faces of said substrates, at least one of said transparent electrodes comprising a plurality of independently switchable transparent electrode elements, each of said independently switchable electrode elements substantially overlaying a unique SBG element;

a means for coupling said first wavelength light into said first light guide, said first wavelength light undergoing total internal reflection within said first light guide;

each said SBG element having a diffracting state and a non diffracting state;

characterized in that each said SBG element when in its diffracting state diffracts said first wavelength light to form a focused image region of predefined geometry and luminance distribution on said image surface,

wherein said SBG element encodes wavefront and phase information corresponding to said geometry and said luminance distribution.

2. The projection display of claim 1 wherein said diffracting state exists when no electric field is a applied across said SBG element via said transparent electrodes and said non diffracting state exists when an electric field is applied across said SBG element via said transparent electrodes.

3. The projection display of claim 1 wherein the image surface is disposed in proximity to said display. The projection display of claim 1 wherein the image surface is more than 25 centimeters from said display.

4. The projection display of claim 1 wherein the image surface is more than 50 centimeters from said display.

5. The projection display of claim 1 wherein one said image region comprises an image of a keyboard.

6. The projection display of claim 1 wherein said image region is an image pixel.

7. The projection display of claim 1 wherein said SBG elements pre-distort the shape of said image region.

8. The projection display of claim 1 wherein image surface is a diffusing material.

9. The projection display of claim 1 wherein image surface is the retina of an eye.

10. The projection display of claim 1 wherein said image surface is curved.

11. The projection display of claim 1 further comprising:

at least one infrared source;

means for directing infrared light from said source towards said image surface and at least one infrared sensor operative to detect light scattered from an object disposed in proximity to said image surface.

12. The projection display of claim 11 wherein said infrared source is a laser.

13. The projection display of claim 11 wherein said infrared sensor comprises an image sensing array and lens.

14. The projection display of claim 11 wherein said first SBG array contains at least one infrared diffracting SBG element operative to diffract infrared light from said infrared source towards said image surface when said infrared diffracting SBG element is subjected to an applied voltage via said transparent electrodes.

15. The projection display of claim 1 further comprising:

second and third light sources emitting light of second and third wavelengths;

second and third SBG arrays each comprising a multiplicity of separately switchable SBG elements disposed in a single layer;

said SBG elements of said first, second and third SBG arrays substantially overlapping;

transparent substrates sandwiching said second SBG array, said substrates together functioning as a second light guide;

transparent substrates sandwiching said third SBG array, said substrates together functioning as a third light guide;

transparent electrodes applied to substrate faces in contact with said second and third SBG arrays, at least one of said transparent electrodes in contact with said second and third SBG arrays comprising a plurality of independently switchable transparent electrodes elements, each of said independently switchable electrodes substantially overlaying a unique SBG element;

means for coupling said first, second and third wavelength light into said first, second and third light guides, said first, second and third wavelength light undergoing total internal reflection within said light guides,

each element of said second SBG array diffracting said second wavelength light to form a second image region on an image surface when subjected to an applied voltage via said transparent electrodes, each said element of said second SBG array when in its diffracting state diffracting said second wavelength light to form a focused image region of predefined geometry and luminance distribution on said image surface,

wherein said element of said second SBG array encodes wavefront and phase information corresponding to said geometry and said luminance distribution,

each element of said third SBG array diffracting said third wavelength light to form a third image region on an image surface when subjected to an applied voltage via said transparent electrodes, each said element of said third SBG array when in its diffracting state diffracting said third wavelength light to form a focused image region of predefined geometry and luminance distribution on said image surface,

wherein said element of said third SBG array encodes wavefront and phase information corresponding to said geometry and said luminance distribution.

16. The projection display of claim 15 wherein said first, second and third image regions substantially overlap.

17. The projection display of claim 15 wherein in each said first, second and third wavelength SBG array said SBG elements are configured in rows and columns of a rectangular array and are switched sequentially into their diffracting states in bands comprising at least one row of SBG elements, wherein at least one band of SBG elements in each of said first, second and third SBG arrays is activated at any instant, wherein no overlap exists between said first, second and third wavelength SBG array bands.