Optical device for a head-mounted display, and head-mounted device incorporating it for augmented reality

Patent metadata

Field	Value
Publication number	US-11243398-B2
Application number	US-201816493219-A
Country	US
Kind code	B2
Filing date	Mar 9, 2018
Priority date	Mar 13, 2017
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

The present invention relates to an optical device usable in a head-mounted display which comprises a light conducting element and at least one wafer, and to a head-mounted device which is configured to provide an informative display of augmented reality for a wearer of the head-mounted device and which comprises such an optical device. This optical device ( 1 ) comprises: a light conducting element ( 4 ) which has two first and second opposite main faces ( 4 a and 4 b ) and which inputs and conducts by total internal reflections a light ( 6 ) received from the light source ( 5 ) and partially outputs it out of said element, at least one wafer ( 2, 3 ) which comprises an internal surface ( 2 a, 3 a ) facing a said first main face of said light conducting element, and interposition means in contact with said first main face and said internal surface and defining a gap ( 11 a, 11 b ) optically isolating said element. According to the invention, said interposition means comprise a peripheral sealing arrangement ( 10 a, 10 b ) which extends along its peripheral length between and in sealing contact with a peripheral area ( 2 aa, 3 aa ) of said internal surface and a facing zone ( 4 aa, 4 ba ) of said first main face, at least one portion of said sealing arrangement exhibiting a locally reduced optical coupling with said first main face to preserve said internal reflections at said at least one portion toward the inside of said element.

First claim

The invention claimed is:

1. An optical device in a head-mounted display, the optical device comprising:
a light conducting element having a first refractive index which has an input zone coupled to a light source and two first and second opposite main faces and which is configured to input and conduct by total internal reflections between said main faces a light received from said light source and to partially output the conducted light out of said light conducting element,
at least one wafer which comprises an internal surface facing a said first main face of said light conducting element, and
interposition means which are in contact with said first main face and said internal surface and which define therebetween a gap having a gap refractive index lower than said first refractive index and optically isolating said light conducting element,
wherein said interposition means comprise a peripheral sealing arrangement which has a peripheral length and extends along said peripheral length between and in sealing contact with a peripheral area of said internal surface and a zone of said first main face facing said peripheral area, at least one portion of said sealing arrangement along said peripheral length being configured to exhibit a locally reduced optical coupling with said first main face compared to the remaining of said peripheral length, to preserve said internal reflections at said at least one portion inside said light conducting element.

2. The optical device according to claim 1 , wherein said peripheral sealing arrangement comprises at least one elastomeric or plastic peripheral seal extending over said peripheral length in the form of a closed or open loop and further incorporates, on said at least one portion, optically isolating means which are configured for exhibiting said reduced optical coupling and which are in contact with said at least one peripheral seal and with said first main face.

3. The optical device according to claim 2 , wherein said peripheral sealing arrangement is in non-adhesive contact with said internal surface of said at least one wafer and with said first face of said light conducting element, and wherein said optically isolating means are in adhesive or non-adhesive contact with said at least one peripheral seal.

4. The optical device according to claim 2 , wherein said at least one peripheral seal is adapted to prevent intrusion of water and dust into said gap, and is selected from:
rubber seals having a polygonal or elliptic cross-section, and
multilayer thermoplastic adhesive seals optionally containing microbeads.

5. The optical device according to claim 4 , wherein said at least one peripheral seal is selected from:
rubber seals having a square or circular cross-section, and
multilayer thermoplastic adhesive seals comprising two adhesive outer layers which are pressure sensitive layers and which are provided on either side of an inner layer which is of triacetyl cellulose.

6. The optical device according to claim 2 , wherein said optically isolating means are selected from:
(i) a nanostructured film having nanoreliefs able to define an abrupt change of refractive index at an interface between said film and said first main face,
(ii) a monolayer or multilayer mirror film able to reflect the light coupled out from said first main face and exhibiting a contact area with said first main face,
(iii) a sealing member devoid of contact with said first main face and mounted in contact with said light source and with a peripheral edge of said at least one wafer, said light source being connected to said light conducting element on a connecting zone thereof, said sealing member locally replacing and being connected to said peripheral seal in an opening defined by said open loop, and/or
(iv) a flexible gasket compressed between said first main face and said internal surface and exhibiting a contact area with said first main face,
said contact area being defined by a length of said at least one portion in a peripheral direction thereof and, in a transverse direction perpendicular to said length, by a width of said at least one portion in contact with said first main face.

7. The optical device according to claim 6 , wherein said optically isolating means comprise said nanostructured film which is a moth eye film defined by said nanoreliefs which are each tapered from a base to an end thereof, and which exhibit an actual refractive index seen by the incoming light which continuously decreases from said bases to said ends, said nanostructured film being adhesively bonded to said at least one peripheral seal.

8. The optical device according to claim 7 , wherein said nanoreliefs are each tapered from the base to the end thereof in a substantially conical way, said nanostructured film being in contact with said first main face by said ends of said tapered nanoreliefs.

9. The optical device according to claim 6 , wherein said optically isolating means comprise said monolayer or multilayer mirror film which is deposited on said first main face.

10. The optical device according to claim 9 , wherein said monolayer or multilayer mirror film is deposited on said first main face by physical vapor deposition of an aluminum layer or of a reflecting ink, and has said width in contact with said first main face that is less than 200 μm.

11. The optical device according to claim 6 , wherein said optically isolating means comprise said compressed flexible gasket which has said width in contact with said first main face that is less than 200 μm.

12. The optical device according to claim 6 , wherein said sealing member comprises:
a sealing body in contact with said peripheral edge, and a sealing lip extending said sealing body and in contact with said light source, or
a connecting element which is bonded to an area of said connecting zone surrounding said light source and which defines two protruding opposed surfaces provided with two local seals respectively in contact with said peripheral edge and with said light source.

13. The optical device according to claim 1 , wherein said gap has a thickness which is greater than or equal to an emitting wavelength of said light source, and which is of at least 700 nm.

14. The optical device according to claim 13 , wherein said gap is filled with air and has said thickness greater than or equal to an emitting wavelength of said light source which is of at least 1 μm.

15. The optical device according to claim 1 , wherein said at least one portion includes a proximal section of said peripheral sealing arrangement which faces said input zone of said light conducting element adjacent said light source.

16. The optical device according to claim 1 , wherein said light conducting element, is configured to provide:
an informative display of augmented reality by said head-mounted display, said light conducting element partially outputting the conducted light towards an eye of a wearer through said at least one wafer, or a lighting or measurement.

17. The optical device according to claim 16 , wherein said light conducting element is a light-guide optical element (LOE).

18. The optical device according to claim 1 , wherein the optical device comprises at least one pair of first and second said wafers which respectively have first and second said internal surfaces facing said first and second main faces of said light conducting element, the optical device comprising:
a first said peripheral sealing arrangement between a first said peripheral area of said first internal surface and with a first said zone of

Assignees

• Essilor Int

Inventors

• Meynen Mathieu
• Peloux Marius
• Hubacz Dominick
• Jouard Ludovic
• Reignault Marc

Classifications

• G02B2027/0178

  Eyeglass type (eyeglass details G02C) · CPC title

• B82Y20/00

  Nanooptics, e.g. quantum optics or photonic crystals · CPC title

• G02C7/086

  Auxiliary lenses located directly on a main spectacle lens or in the immediate vicinity of main spectacles · CPC title

• G02B27/0172 Primary

  characterised by optical features · CPC title

• G02B27/126

  The splitting element being a prism or prismatic array, including systems based on total internal reflection · CPC title