# US 12,216,303 B2 · Light-guide plate, manufacturing method for the same, light-guide plate module, and image display device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,216,303 B2 - Document ID: US12216303B2 - Status: Granted - Kind: B2 - Application number: 17/603,353 - Filed: 2020-02-13 - Published: 2022-06-30 - Granted: 2025-02-04 - Earliest claimed: 2019-06-21 - Assignees: Hitachi-LG Data Storage, Inc. - Applicants: Hitachi-LG Data Storage, Inc. - Inventors: Hiroyuki Minemura - Web page: https://patentgrep.com/patent/US12216303B2 ## CPC - G02B 6/0016: {Grooves, prisms, gratings, scattering particles or rough surfaces} - G02B 27/0172: {characterised by optical features} - G02B 5/1861: {Reflection gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials (G02B5/1809, G02B5/1828, G02B5/1833, G02B5/1838 and G02B5/1847 take precedence)} - G02B 6/00: Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings - G02B 6/0038: {Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide} - G02B 6/0065: {Manufacturing aspects; Material aspects} - G02B 27/02: Viewing or reading apparatus (stereoscopic systems G02B30/00) - G02B 2005/1804: {Transmission gratings} - G02B 2027/0125: {Field-of-view increase by wavefront division} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract The light-guide plate includes a substrate, an incidence diffraction grating that diffracts incident light, and an emission diffraction grating that emits light from the substrate, the light being diffracted by the incidence diffraction grating. The emission diffraction grating is formed of a recessed/projected pattern formed on a substrate surface, the recessed/projected pattern includes a first group of parallel straight lines and a second group of parallel straight lines intersecting the first group of parallel straight lines, and a pitch of the first group of parallel straight lines is equal to a pitch of the second group of parallel straight lines. A relationship between the pitch P of the first group of parallel straight lines and the second group of parallel straight lines and a pattern width W of the recessed/projected pattern is defined as W/P, which is 0.15 or more and 0.85 or less. ## Claims ### Claim 1 A light-guide plate comprising: a substrate; an incidence diffraction grating that diffracts incident light; and an emission diffraction grating that emits light from the substrate, the light being diffracted by the incidence diffraction grating, the emission diffraction grating having two wave vectors that form an angle of 120°, wherein the emission diffraction grating is formed of a recessed/projected pattern formed on a surface of the substrate, the recessed/projected pattern includes a first group of parallel straight lines and a second group of parallel straight lines intersecting the first group of parallel straight lines, and a pitch of the first group of parallel straight lines is equal to a pitch of the second group of parallel straight lines, and a relationship between the pitch P of the first group of parallel straight lines and the second group of parallel straight lines and a pattern width W of the recessed/projected pattern is defined as W/P that is 0.15 or more and 0.85 or less. ### Claim 2 (depends on 1) The light-guide plate according to claim 1, wherein the substrate is made of a polymer compound material, and an aspect ratio of the recessed/projected pattern is 1 or less. ### Claim 3 (depends on 1) The light-guide plate according to claim 1, wherein an aspect ratio of the recessed/projected pattern is 0.25 or more and 1.0 or less. ### Claim 4 (depends on 1) The light-guide plate according to claim 1, wherein a pitch P of the first group of parallel straight lines and the second group of parallel straight lines is equal to a pitch of the incidence diffraction grating. ### Claim 5 (depends on 1) The light-guide plate according to claim 1, wherein the incidence diffraction grating is a reflection-type diffraction grating that causes incident light to propagate inside the substrate in a state of being reflected and diffracted, and is formed on a surface of the substrate that is a same as a surface where the emission diffraction grating is formed. ### Claim 6 (depends on 1) The light-guide plate according to claim 1, wherein the W/P is 0.3 or more and 0.7 or less. ### Claim 7 (depends on 1) The light-guide plate according to claim 1, wherein in the emission diffraction grating, a relationship between a pitch P of the first group of parallel straight lines and the second group of parallel straight lines and a pattern width W of the recessed/projected pattern changes, depending on a positional relationship between the emission diffraction grating and the incidence diffraction grating. ### Claim 8 (depends on 1) The light-guide plate according to claim 1, wherein the emission diffraction grating includes a part where the W/P is 0.4 or more and 0.6 or less. ### Claim 9 (depends on 1) A light-guide plate module comprising a plurality of the light-guide plates according to claim 1, the light-guide plates being stacked to make up the light-guide plate module. ### Claim 10 (depends on 9) The light-guide plate module according to claim 9, wherein a surface of the substrate of the light-guide plate, the surface carrying the incidence diffraction grating and the emission diffraction grating, is provided with an alignment mark. ### Claim 11 (depends on 10) An image display device comprising: the light-guide plate module according to claim 10; and a projector that emits image light onto the light-guide plate module, wherein the image light is incident on the incidence diffraction grating. ### Claim 12 (depends on 11) The image display device according to claim 11, wherein the substrate is made of a polymer compound material, and an aspect ratio of the recessed/projected pattern is 1 or less. ### Claim 13 (depends on 11) The image display device according to claim 11, wherein the light-guide plate module emits the image light to a side opposite to a side where the projector is disposed. ### Claim 14 (depends on 9) The light-guide plate module according to claim 9, wherein a surface of the substrate of the light-guide plate has a gap holding pattern having an occupancy area that is 0.1% to 5.0% of an area of the light-guide plate. ### Claim 15 (depends on 1) A manufacturing method for the light-guide plate according to claim 1, the manufacturing method comprising steps of: preparing the substrate made of a polymer compound material; and forming the incidence diffraction grating and the emission diffraction grating on the substrate, using a stamper. ### Claim 16 A light-guide plate comprising: a substrate; an incidence diffraction grating that diffracts incident light; and an emission diffraction grating that emits the light the emission diffraction grating having two wave vectors that form an angle of 120°, wherein the emission diffraction grating is formed of a linear recessed/projected pattern formed on a surface of the substrate, and diffracts light in a direction perpendicular to the linear recessed/projected pattern at a diffraction efficiency η1, the light coming from the incidence diffraction grating and propagating in the substrate, and at the same time, diffracts the light in a direction perpendicular to the substrate at a diffraction efficiency η11, and a relationship between the diffraction efficiencies η11 and η1 is determined to be η11<η1. ### Claim 17 (depends on 16) The light-guide plate according to claim 16, wherein η11 is set 0.8 to 1.2 times (η1)2.