# US 2015/0177516 A1 · Optical see-through glass type display device and corresponding optical element

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- Number: US 2015/0177516 A1
- Document ID: US20150177516A1
- Status: Published application
- Kind: A1
- Application number: 14/574,702
- Filed: 2014-12-18
- Published: 2015-06-25
- Earliest claimed: 2013-12-18
- Assignees: Thomson Licensing
- Applicants: Thomson Licensing
- Inventors: Laurent BLONDE; Valter DRAZIC
- Web page: https://patentgrep.com/patent/US20150177516A1

## CPC

- G02B 27/0101: {characterised by optical features (G02B27/0172 takes precedence)}
- G02B 27/017: {Head mounted}
- G02F 1/315: based on the use of controlled internal reflection
- G02B 3/08: with discontinuous faces, e.g. Fresnel lens {(diffractive Fresnel lenses G02B5/1876)}
- G02B 5/04: Prisms
- G02B 5/1842: {Gratings for image generation (G02B5/1847 takes precedence)}
- G02B 5/3016: {involving passive liquid crystal elements (optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528)}
- G02B 5/3083: {Birefringent or phase retarding elements (G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001)}
- G02B 6/00: Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B 6/0055: {Reflecting element, sheet or layer}
- G02B 13/16: for use in conjunction with image converters or intensifiers {, or for use with projectors, e.g. objectives for projection TV}
- G02B 17/004: {Systems comprising a plurality of reflections between two or more surfaces, e.g. cells, resonators (multipass arrangements for optical cuvettes G01N21/031; laser resonators H01S3/05)}
- G02B 17/006: {Systems in which light light is reflected on a plurality of parallel surfaces, e.g. louvre mirrors, total internal reflection [TIR] lenses (Fresnel mirrors G02B5/09, Fresnel lenses G02B3/08)}
- G02B 19/0038: {for use with ambient light (G02B19/009, G02B19/0095 take precedence)}
- G02B 26/005: {based on electrowetting}
- G02B 27/0075: {with means for altering, e.g. increasing, the depth of field or depth of focus}
- G02B 27/01: Head-up displays
- G02B 27/0103: {comprising holographic elements}
- G02B 27/0172: {characterised by optical features}
- G02B 27/0176: {characterised by mechanical features}
- G02B 27/022: {Viewing apparatus (G02B27/04, G02B27/06, G02B27/08 take precedence)}
- G02B 27/0905: {Dividing and/or superposing multiple light beams}
- G02B 27/14: operating by reflection only
- G02B 2027/0118: {comprising devices for improving the contrast of the display / brillance control visibility}
- G02B 2027/0123: {comprising devices increasing the field of view}
- G02B 2027/0127: {comprising devices increasing the depth of field}
- G02B 2027/0154: {with movable elements}
- G02B 2027/0163: {Electric or electronic control thereof}
- G02B 2027/0178: {Eyeglass type (eyeglass details G02C)}
- G03B 21/28: Reflectors in projection beam {(in illumination beam G03B21/2066)}
- G06T 19/20: Editing of three-dimensional [3D] images, e.g. changing shapes or colours, aligning objects or positioning parts
- G09G 3/36: using liquid crystals
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D)
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)

## Abstract

An optical see-through glass type display device (100) comprises: an image projector (140) projecting a virtual image; a first optical element (130) configured to guide light of the virtual image; and a second optical element (120) having a first reflection surface (122a) for reflecting back light coming through the front surface of the second optical element (120) and a second reflection surface (124a) for retro-reflecting light coming through the rear surface of the second optical element (120). The second optical element (120) is switchable between a first state in which the reflection on the first and second reflection surfaces (122a, 124a) is enabled and a second state in which the reflection on the first and second reflection surfaces (122a, 124a) is disabled.

## Claims

### Claim 1

An optical see-through glass type display device, comprising:
an image projector projecting a virtual image;
a first optical element configured to guide light of the virtual image; and
a second optical element to be positioned between the first optical element and an ambient scene, having a first reflection surface for reflecting back light coming through the front surface of the second optical element and a second reflection surface for retro-reflecting light coming through the rear surface of the second optical element,
wherein the second optical element is switchable between a first state in which the reflection on the first and second reflection surfaces is enabled and a second state in which the reflection on the first and second reflection surfaces is disabled.

### Claim 2 (depends on 1)

The display device according to claim 1, further comprising:
at least one gap formed between the first reflection surface and the second reflection surface of the second optical element; and
a liquid supplier/remover which supplies liquid to fill the gap and removes the liquid from the gap, the liquid having a refraction index capable of disabling the reflection on the first and second reflection surfaces of the second optical element.

### Claim 3 (depends on 2)

The display device according to claim 2, wherein the gap is segmented into a plurality of gaps arranged in a matrix form, and wherein the liquid supplier/remover supplying the liquid to fill each gap and removing the liquid from each gap, individually.

### Claim 4 (depends on 3)

The display device according to claim 3, wherein the liquid supplier/remover does not supply the liquid to the gaps which overlap an area of the first optical element where the virtual image is presented and the liquid supplier/remover supplies the liquid to the gaps which don't overlap the area.

### Claim 5 (depends on 2)

The display device according to claim 2, wherein the liquid supplier/remover comprising a reservoir for containing the liquid, a pump for pumping the liquid into and out of the gap and a controller to control the pump and liquid flow to the gap.

### Claim 6 (depends on 1)

The display device according to claim 1, further comprising:
refraction index variable elements arranged in a matrix form between the first reflection surface and the second reflection surface of the second optical element;
electrodes formed on the second optical element for driving the elements individually; and
a controller for controlling the electrodes to drive the refraction index variable elements individually so that refraction index for each element be individually switched between a low refraction index state which enables the reflection on the first and second reflection surfaces and a high refraction index state which disables the reflection on the first and second reflection surfaces.

### Claim 7 (depends on 6)

The display device according to claim 6, wherein the refraction index variable elements, which overlaps an area of the first optical element where the virtual image is presented, are switched to the low refraction index state and the refraction index variable elements which don't overlap the area are switched to the high refraction index state.

### Claim 8

An optical element, comprising a first reflection surface for reflecting back light coming through the front surface of the optical element and a second reflection surface for retro-reflecting light coming through the rear surface of the optical element,
wherein the optical element is switchable between a first state in which the reflection on the first and second reflection surfaces is enabled and a second state in which the reflection on the first and second reflection surfaces is disabled.

### Claim 9 (depends on 8)

The optical element according to claim 8, further comprising at least one gap formed between the first reflection surface and the second reflection surface of the optical element, wherein liquid having a refraction index capable of disabling the reflection on the first and second reflection surfaces of the optical element may be supplied to fill the gap and removed from the gap.

### Claim 10 (depends on 9)

The optical element according to claim 9, wherein the gap is segmented into a plurality of gaps arranged in a matrix form, the liquid may be supplied to fill each gap and removed from each gap, individually.

### Claim 11 (depends on 8)

The optical element according to claim 8, further comprising:
refraction index variable elements arranged in a matrix form between the first reflection surface and the second reflection surface of the optical element; and
electrodes formed on the optical element for driving the elements individually,
wherein the refraction index variable elements are individually driven by the electrodes so that refraction index for each element be individually switched between a low refraction index state which enables the reflection on the first and second reflection surfaces and a high refraction index state which disables the reflection on the first and second reflection surfaces.