# US 10,502,970 B2 · Display device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,502,970 B2 - Document ID: US10502970B2 - Status: Granted - Kind: B2 - Application number: 15/942,619 - Filed: 2018-04-02 - Published: 2018-10-04 - Granted: 2019-12-10 - Earliest claimed: 2017-04-04 - Assignees: Japan Display Inc. - Applicants: Japan Display Inc. - Inventors: Takeo Koito; Yudai Numata - Web page: https://patentgrep.com/patent/US10502970B2 ## CPC - G02B 30/56: by projecting aerial or floating images - G02B 5/124: plural reflecting elements forming part of a unitary plate or sheet - G02B 27/0018: {with means for preventing ghost images (anti-reflection coatings G02B1/11)} - G02F 1/13306: {Circuit arrangements or driving methods for the control of single liquid crystal cells (G02F1/132, G02F1/133382 take precedence)} - G02F 1/133526: {Lenses, e.g. microlenses or Fresnel lenses} - G02F 1/133536: {Reflective polarizers (G02F1/13362 takes precedence)} - G02F 1/133553: {Reflecting elements (associated to illuminating devices G02F1/133605)} - G02F 1/13362: {providing polarized light, e.g. by converting a polarisation component into another one} - G02F 1/134363: {for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]} - G02F 1/13471: {in which all the liquid crystal cells or layers remain transparent, e.g. FLC, ECB, DAP, HAN, TN, STN, SBE-LC cells (G02F1/13475 takes precedence)} - G02F 1/29: for the control of the position or the direction of light beams, i.e. deflection - G02F 1/133345: {Insulating layers (G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence)} - G02F 1/133512: {Light shielding layers, e.g. black matrix (G02F1/136209 takes precedence)} - G02F 1/133514: {Colour filters} - G02F 1/133562: {on the viewer side} - G02F 1/133565: {inside the LC elements, i.e. between the cell substrates} - G02F 1/1337: Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers - G02F 1/133738: {for homogeneous alignment} - G02F 1/13439: {characterised by their electrical, optical, physical properties; materials therefor; method of making} - G02F 1/136286: {Wiring, e.g. gate line, drain line} - G02F 1/1368: in which the switching element is a three-electrode device {(G02F1/136277 takes precedence)} - G02F 2203/01: transmissive - G02F 2203/07: Polarisation dependent - G02F 2203/09: transflective - 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 ## Abstract According to one embodiment, a display device comprises a light modulating element which transmits or reflects incident light, a display unit which emits display light toward the light modulating element, and a retroreflective element which retroreflects the display light reflected from the light modulating element, the light modulating element including an inner surface on a side opposed to the display unit and the retroreflective element, and an outer surface on a side opposite to the inner surface, the light modulating element includes a first mode of transmitting light incident from the outer surface at a first transmittance, and a second mode of transmitting the light incident from the outer surface at a second transmittance lower than the first transmittance. ## Claims ### Claim 1 A display device comprising: a light modulating element which transmits or reflects incident light; a display unit which emits display light toward the light modulating element; and a retroreflective element which retroreflects the display light reflected from the light modulating element, the light modulating element including an inner surface on a side opposed to the display unit and the retroreflective element, and an outer surface on a side opposite to the inner surface, the light modulating element comprising a first mode of transmitting light incident from the outer surface at a first transmittance, and a second mode of transmitting the light incident from the outer surface at a second transmittance lower than the first transmittance, wherein the light modulating element comprises: a first polarizing element which is located on a side closer to the inner surface, and includes a first transmission axis which reflects first linearly polarized light and transmits second linearly polarized light crossing the first linearly polarized light; a second polarizing element including a second transmission axis; a first substrate comprising a plurality of first control electrodes; a second substrate comprising a second control electrode opposed to the plurality of first control electrodes; and a liquid crystal layer which is located between the first polarizing element and the second polarizing element, and is held between the first substrate and the second substrate. ### Claim 2 (depends on 1) The display device of claim 1, wherein the display unit emits the display light in the first mode, and does not emit the display light in the second mode. ### Claim 3 (depends on 1) The display device of claim 1, wherein the light modulating element further comprises a third polarizing element which is located between the first polarizing element and the liquid crystal layer, and includes a third transmission axis parallel to the first transmission axis. ### Claim 4 (depends on 1) The display device of claim 1, further comprising a retardation film which imparts a retardation to transmitted light, wherein the retardation film is arranged along an inner surface of the retroreflective element. ### Claim 5 (depends on 1) The display device of claim 1, wherein at least one of the first control electrode and the second control electrode is a semi-transmissive layer. ### Claim 6 (depends on 1) The display device of claim 1, wherein the light modulating element comprises: a semi-transmissive layer located between the first polarizing element and the second polarizing element. ### Claim 7 (depends on 1) The display device of claim 1, wherein the light modulating element comprises: a controller which controls a voltage to be applied to the liquid crystal layer for forming a liquid crystal lens in the liquid crystal layer, and the controller applies a voltage for forming the liquid crystal lens to the liquid crystal layer in the second mode, and does not apply a voltage to the liquid crystal layer in the first mode. ### Claim 8 A display device comprising: a light modulating element which transmits or reflects incident light; a display unit which emits display light toward the light modulating element; a retroreflective element which retroreflects the display light reflected from the light modulating element; and a controller which controls the light modulating element, the controller setting the light modulating element to a first transmittance state having a first transmittance at a display period when the display unit emits the display light, and setting the light modulating element to a second transmittance state having a second transmittance of which is lower than the first transmittance, at a non-display period when the display unit does not emit the display light. ### Claim 9 (depends on 8) The display device of claim 8, wherein the light modulating element comprises: a first polarizing element including a first transmission axis; a second polarizing element including a second transmission axis; and a liquid crystal layer located between the first polarizing element and the second polarizing element, and the controller applies a voltage to the liquid crystal layer in the first transmittance state, and does not apply a voltage to the liquid crystal layer in the second transmittance state. ### Claim 10 (depends on 9) The display device of claim 9, wherein a retardation of the liquid crystal layer in the first transmittance state is substantially zero, and the second transmission axis is parallel to the first transmission axis. ### Claim 11 (depends on 9) The display device of claim 9, wherein: a retardation of the liquid crystal layer in the first transmittance state is substantially λ/2, where λ is a wavelength of light transmitted through the liquid crystal layer; and the second transmission axis crosses the first transmission axis. ### Claim 12 (depends on 8) The display device of claim 8, wherein the light modulating element comprises: a first polarizing element including a first transmission axis which reflects first linearly polarized light, and transmits second linearly polarized light crossing the first linearly polarized light; a second polarizing element including a second transmission axis; a first substrate comprising a plurality of first control electrodes; a second substrate comprising a second control electrode opposed to the plurality of first control electrodes; and a liquid crystal layer which is located between the first polarizing element and the second polarizing element, and is held between the first substrate and the second substrate. ### Claim 13 (depends on 8) The display device of claim 8, further comprising a retardation film which imparts a retardation to transmitted light, wherein the retardation film is arranged along an inner surface of the retroreflective element. ### Claim 14 (depends on 8) The display device of claim 8, wherein the light modulating element comprises: a first polarizing element including a first transmission axis; a second polarizing element including a second transmission axis; a first substrate comprising a plurality of first control electrodes; a second substrate comprising a second control electrode opposed to the plurality of first control electrodes; and a liquid crystal layer which is located between the first polarizing element and the second polarizing element, and is held between the first substrate and the second substrate, and at least one of the first control electrode and the second control electrode is a semi-transmissive layer. ### Claim 15 (depends on 8) The display device of claim 8, wherein the light modulating element comprises: a first polarizing element including a first transmission axis; a second polarizing element including a second transmission axis; a first substrate comprising a plurality of first control electrodes; a second substrate comprising a second control electrode opposed to the plurality of first control electrodes; a liquid crystal layer which is located between the first polarizing element and the second polarizing element, and is held between the first substrate and the second substrate; and a semi-transmissive layer located between the first polarizing element and the second polarizing element. ### Claim 16 (depends on 8) The display device of claim 8, wherein the light modulating element comprises: a first substrate comprising a plurality of first control electrodes; a second substrate comprising a second control electrode opposed to the plurality of first control electrodes; and a liquid crystal layer held between the first substrate and the second substrate, the controller controls a voltage to be applied to the liquid crystal layer for forming a liquid crystal lens in the liquid crystal layer, and the controller applies a voltage for forming the liquid crystal lens to the liquid crystal layer in the second transmittance state, and does not apply a voltage to the liquid crystal layer in the first transmittance state.