# US 2019/0171009 A1 · Head up display device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0171009 A1 - Document ID: US20190171009A1 - Status: Published application - Kind: A1 - Application number: 16/267,703 - Filed: 2019-02-05 - Published: 2019-06-06 - Earliest claimed: 2016-10-31 - Assignees: Japan Display Inc. - Applicants: Japan Display Inc. - Inventors: Tatsuya Yata; Naoyuki Takasaki - Web page: https://patentgrep.com/patent/US20190171009A1 ## CPC - G02B 27/0101: {characterised by optical features (G02B27/0172 takes precedence)} - G02B 27/283: {used for beam splitting or combining} - G02F 1/0136: {for the control of polarisation, e.g. state of polarisation [SOP] control, polarisation scrambling, TE-TM mode conversion or separation (G02F1/0353 takes precedence)} - G02F 1/133528: {Polarisers} - G02F 1/1368: in which the switching element is a three-electrode device {(G02F1/136277 takes precedence)} - G02F 1/137: characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering - G03B 21/28: Reflectors in projection beam {(in illumination beam G03B21/2066)} - G09G 3/002: {to project the image of a two-dimensional display, such as an array of light emitting or modulating elements or a CRT} - G09G 3/3406: {Control of illumination source (illumination devices structurally associated with liquid crystal cells G02F1/1336)} - 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 2027/0118: {comprising devices for improving the contrast of the display / brillance control visibility} - G02B 2027/014: {comprising information/image processing systems} - G02F 1/1362: Active matrix addressed cells {(G02F1/134336, G02F1/134363 take precedence)} - G02F 2203/01: transmissive - G02F 2203/12: spatial light modulator - G09G 2320/041: Temperature compensation - G09G 2320/0646: Modulation of illumination source brightness and image signal correlated to each other - G09G 2320/0686: with two or more screen areas displaying information with different brightness or colours - G09G 2330/045: Protection against panel overheating - G09G 2380/10: Automotive applications - 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) - 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 According to one embodiment, a display device includes a polarization separation element which transmits first polarized light, and reflects second polarized light, a first optical modulation unit which displays a first image by using transmitted light, a second optical modulation unit which displays a second image by using reflected light, and a projector which projects the first image onto a first projection area of a projection plane, and projects the second image onto a second projection area different from the first projection area of the projection plane. ## Claims ### Claim 1 A display device comprising: a polarization separation element configured to transmit first polarized light as transmitted light, and reflect second polarized light different from the first polarized light as reflected light, the first polarized light and the second polarized light being part of illumination light from an illumination device; a first optical modulation unit including a liquid crystal layer and configured to display a first image by using the transmitted light; a second optical modulation unit including a liquid crystal layer and configured to display a second image by using the reflected light; and a retardation plate configured to impart retardation to at least one of the transmitted light and the reflected light. ### Claim 2 (depends on 1) The display device according to claim 1, wherein the retardation plate is configured to change the reflected light from the second polarized light to the first polarized light. ### Claim 3 (depends on 1) The display device according to claim 1, wherein the retardation plate is configured to change the transmitted light from the first polarized light to the second polarized light. ### Claim 4 (depends on 1) The display device according to claim 1, wherein the retardation plate is configured to change at least one of the transmitted light and the reflected light to third polarized light different from the first polarized light and the second polarized light. ### Claim 5 (depends on 1) The display device according to claim 1, wherein the retardation plate is arranged in at least one point between the polarization separation element and the first optical modulation unit, and between the polarization separation element and the second optical modulation unit. ### Claim 6 (depends on 1) The display device according to claim 1, wherein the retardation plate is configured to impart retardation to at least one of the transmitted light through the first optical modulation unit and the reflected light through the second optical modulation unit. ### Claim 7 (depends on 1) The display device according to claim 1, wherein the first image is projected onto a first projection area, and the second image is projected onto a second projection area different from the first projection area. ### Claim 8 (depends on 1) The display device according to claim 1, further comprising a mirror configured to reflect the reflected light from the polarization separation element to the second optical modulation unit. ### Claim 9 (depends on 1) The display device according to claim 1, wherein an optical path length from the illumination device to the first optical modulation unit is different from an optical path length from the illumination device to the second optical modulation unit. ### Claim 10 A display device comprising: a polarization separation element configured to transmit first polarized light as transmitted light, and reflect second polarized light different from the first polarized light as reflected light, the first polarized light and the second polarized light being part of illumination light from an illumination device; a optical modulation unit including a liquid crystal layer and having a first area and a second area, the first area configured to display a first image by using the transmitted light, and the second area configured to display a second image by using the reflected light; and a retardation plate configured to impart retardation to at least one of the transmitted light and the reflected light. ### Claim 11 (depends on 1) The display device according to claim 1, wherein the retardation plate is configured to change the reflected light from the second polarized light to the first polarized light. ### Claim 12 (depends on 1) The display device according to claim 1, wherein the retardation plate is configured to change the transmitted light from the first polarized light to the second polarized light. ### Claim 13 (depends on 1) The display device according to claim 1, wherein the retardation plate is configured to change at least one of the transmitted light and the reflected light to third polarized light different from the first polarized light and the second polarized light. ### Claim 14 (depends on 1) The display device according to claim 1, wherein the retardation plate is arranged in at least one point between the polarization separation element and the first area of the optical modulation unit, and between the polarization separation element and the second area of the optical modulation unit. ### Claim 15 (depends on 1) The display device according to claim 1, wherein the retardation plate is configured to impart retardation to at least one of the transmitted light through the first area of the optical modulation unit and the reflected light through the second area of the optical modulation unit. ### Claim 16 (depends on 1) The display device according to claim 1, wherein the first image is projected onto a first projection area, and the second image is projected onto a second projection area different from the first projection area. ### Claim 17 (depends on 1) The display device according to claim 1, further comprising a mirror configured to reflect the reflected light from the polarization separation element to the second area of the optical modulation unit. ### Claim 18 (depends on 1) The display device according to claim 1, wherein an optical path length from the illumination device to the first area of the optical modulation unit is different from an optical path length from the illumination device to the second area of the optical modulation unit.