# US 10,371,950 B2 · Imaging optical unit for generating a virtual image and smartglasses > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,371,950 B2 - Document ID: US10371950B2 - Status: Granted - Kind: B2 - Application number: 15/538,653 - Filed: 2015-12-10 - Published: 2017-12-14 - Granted: 2019-08-06 - Earliest claimed: 2014-12-23 - Assignees: tooz technologies GmbH - Applicants: Carl Zeiss Smart Optics GmbH - Inventors: Hans-Juergen Dobschal; Karsten Lindig - Web page: https://patentgrep.com/patent/US10371950B2 ## CPC - G02B 27/0172: {characterised by optical features} - G02B 3/08: with discontinuous faces, e.g. Fresnel lens {(diffractive Fresnel lenses G02B5/1876)} - G02B 27/143: {using macroscopically faceted or segmented reflective surfaces} - 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} - G02B 2027/0178: {Eyeglass type (eyeglass details G02C)} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract An imaging optical unit for generating a virtual image of an initial image represented on an image generator includes at least one spectacle lens, an input coupling device for coupling an imaging beam path emanating from the initial image in between the inner surface and the outer surface of the spectacle lens, and a Fresnel structure present in the spectacle lens for coupling the imaging beam path out from the spectacle lens in the direction of the eye. The input coupling device couples the imaging beam path in between the inner surface and the outer surface of the spectacle lens in such a way that it is guided by reflections between the inner surface and the outer surface to the Fresnel structure. The Fresnel structure has Fresnel surfaces, which bring about a base deflection of the rays of the imaging beam path by 45 to 55 degrees. ## Claims ### Claim 1 An imaging optical unit for generating a virtual image of an initial image represented on an image generator, comprising: at least one spectacle lens, including an inner surface that faces an eye of a user and an outer surface that faces away from the eye of the user; an input coupler that is configured to couple an imaging beam path emanating from the initial image into the spectacle lens in between the inner surface and the outer surface of the spectacle lens; and a Fresnel structure present in the spectacle lens that is configured to couple the imaging beam path out from the spectacle lens towards the eye of the user, wherein the input coupler is configured to couple the imaging beam path such that the imaging beam path is guided by reflections between the inner surface and the outer surface to the Fresnel structure, wherein the imaging beam path comprises a plurality of rays, wherein the Fresnel structure includes Fresnel surfaces configured to provide a base deflection of the plurality of rays of the imaging beam path of 45 to 55 degrees, wherein the input coupler is configured to couple the imaging beam path in between the inner surface and the outer surface of the spectacle lens such that the imaging beam path is guided via exactly four reflections to the Fresnel structure, and each of the exactly four reflections takes place at either of the inner surface or the outer surface of the spectacle lens, wherein an edge thickening region is provided in the spectacle lens between the input coupler and the Fresnel structure, in which a thickness of the spectacle lens is greater than a thickness in the region of the Fresnel structure, and wherein the input coupler is configured to couple the imaging beam path in between the inner surface and the outer surface of the spectacle lens such that a first reflection occurs after the input coupling at the outer surface of the spectacle lens and a second reflection occurs after the input coupling at a reflection surface arranged on the inner side of the spectacle lens in the edge thickening region. ### Claim 2 (depends on 1) The imaging optical unit of claim 1, wherein the Fresnel structure has a focal length of at least 80 mm. ### Claim 3 (depends on 1) The imaging optical unit of claim 1, wherein the Fresnel surfaces have Fresnel zone depths in a range of 0.35 mm to 0.5 mm. ### Claim 4 (depends on 1) The imaging optical unit of claim 1, wherein the spectacle lens has a radius of curvature in the range of 100 mm to 150 mm. ### Claim 5 (depends on 1) The imaging optical unit of claim 1, wherein the spectacle lens and the input coupler form a monolithic unit. ### Claim 6 (depends on 1) Smartglasses comprising an imaging optical unit for generating a virtual image as claimed in claim 1. ### Claim 7 (depends on 1) The imaging optical unit of claim 1, wherein the reflection surface arranged on the inner surface of the spectacle lens in the edge thickening region has a freeform surface that at least partly corrects imaging aberrations. ### Claim 8 (depends on 7) The imaging optical unit of claim 7, wherein the reflection surface arranged on the inner surface of the spectacle lens in the edge thickening region defines a conic section thereof on which the freeform surface is superimposed. ### Claim 9 (depends on 1) The imaging optical unit of claim 1, wherein a collimator that collimates the imaging beam path is integrated into the input coupler. ### Claim 10 (depends on 9) The imaging optical unit of claim 9, wherein the collimator has a focal length in a range of 20 mm to 30 mm. ### Claim 11 (depends on 9) The imaging optical unit of claim 9, wherein the input coupler comprises an entrance surface, a first mirror surface and a second mirror surface, wherein at least one of the entrance surface, the first mirror surface and the second mirror surface forms the collimator. ### Claim 12 (depends on 11) The imaging optical unit of claim 11, wherein at least one of the first mirror surface, the second mirror surface and the entrance surface has a freeform surface that at least partly corrects imaging aberrations. ### Claim 13 (depends on 12) The imaging optical unit of claim 12, wherein at least one of the first mirror surface, the second mirror surface and the entrance surface of the input coupler defines a conic section thereof on which the freeform surface is superimposed. ### Claim 14 An imaging optical unit for generating a virtual image of an initial image represented on an image generator, comprising: at least one spectacle lens, including an inner surface that faces an eye of a user and an outer surface that faces away from the eye of the user; an input coupler that that is configured to couple an imaging beam path emanating from the initial image into the spectacle lens in between the inner surface and the outer surface of the spectacle lens; and a Fresnel structure present in the spectacle lens that is configured to couple the imaging beam path out from the spectacle lens towards the eye of the user, wherein the input coupler is configured to couple the imaging beam path such that the imaging beam path is guided by reflections between the inner surface and the outer surface to the Fresnel structure, wherein the imaging beam path comprises a plurality of rays, wherein the Fresnel structure includes Fresnel surfaces configured to provide a base deflection of the plurality of rays of the imaging beam path of 45 to 55 degrees, and wherein the input coupler is configured to couple the imaging beam path in between the inner surface and the outer surface of the spectacle lens such that the imaging beam path is guided via at most four reflections to the Fresnel structure, and each of the exactly four reflections takes place at either of the inner surface or the outer surface of the spectacle lens wherein an edge thickening region is provided in the at least spectacle lens between the input coupler and the Fresnel structure, in which a thickness of the at least one spectacle lens is greater than a thickness in the region of the Fresnel structure, and wherein the input coupler is configured to couple the imaging beam path in between the inner surface and the outer surface of the at least one spectacle lens such that a first reflection occurs after the input coupling at the outer surface of the at least one spectacle lens and a second reflection occurs after the input coupling at a reflection surface arranged on the inner side of the at least one spectacle lens in the edge thickening region. ### Claim 15 (depends on 14) The imaging optical unit of claim 14, wherein both of the inner surface and the outer surface of the spectacle lens are curved.