# US 10,310,161 B2 · Planar illumination device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,310,161 B2 - Document ID: US10310161B2 - Status: Granted - Kind: B2 - Application number: 15/825,281 - Filed: 2017-11-29 - Published: 2018-06-07 - Granted: 2019-06-04 - Earliest claimed: 2016-12-02 - Assignees: MINEBEA MITSUMI Inc. - Applicants: MINEBEA MITSUMI Inc. - Inventors: Kazumasa Adachi - Web page: https://patentgrep.com/patent/US10310161B2 ## CPC - G02B 6/005: {provided by one optical element, or plurality thereof, placed on the light output side of the light guide} - G02B 6/0088: {of the light guide or other optical sheets in the package} - G02B 6/02209: {Mounting means, e.g. adhesives, casings (G02B6/02171 and G02B6/02195 take precedence)} - G02B 6/0068: {Arrangements of plural sources, e.g. multi-colour light sources} - G02B 6/009: {of the light source in the package (G02B6/0021 takes precedence)} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A planar illumination device according to an embodiment includes: a light source; a light guide plate including a light incident side surface on which the light source is arranged; a housing that includes side walls surrounding outer circumferential surfaces of the light source and the light guide plate; a first light blocking sheet that is adhered to an outer side surface and a top end surface of a side wall opposed to the light source among the side walls and that covers the top end surface, a top surface of the light source, and part of a top surface of the light guide plate; and a second light blocking sheet that is adhered to top end surfaces of the side walls other than the side wall to which the first light blocking sheet is adhered and that covers at least the top end surfaces. The first light blocking sheet includes a first light blocking layer that extends from the outer side surface of the side wall to which the first light blocking layer is adhered toward a side wall opposed to the side wall to which the first light blocking layer is adhered; and a second light blocking layer that extends from part of a top surface of the first light blocking layer toward a side wall opposed to the side wall on which the first light blocking layer is adhered. ## Claims ### Claim 1 A planar illumination device comprising: a light source; a light guide plate including a light incident side surface on which the light source is arranged; a housing that includes side walls surrounding outer circumferential surfaces of the light source and the light guide plate; a first light blocking sheet that is adhered to an outer side surface and a top end surface of a side wall opposed to the light source among the side walls and that covers the top end surface, a top surface of the light source, and a part of a top surface of the light guide plate; and a second light blocking sheet that is adhered to top end surfaces of the side walls other than the side wall to which the first light blocking sheet is adhered and that covers at least the top end surfaces, wherein the first light blocking sheet includes a first light blocking layer that extends from the outer side surface of the side wall to which the first light blocking layer is adhered toward a side wall opposed to the side wall to which the first light blocking layer is adhered; and a second light blocking layer that extends from a part of a top surface of the first light blocking layer toward a side wall opposed to the side wall on which the first light blocking layer is adhered. ### Claim 2 (depends on 1) The planar illumination device according to claim 1, wherein the first light blocking layer extends from the outer side surface of the side wall to which the first blocking layer is adhered to a part of the top surface of the light source. ### Claim 3 (depends on 1) The planar illumination device according to claim 1, wherein a slit is formed between the first light blocking sheet and the second light blocking sheet. ### Claim 4 (depends on 3) The planar illumination device according to claim 3, wherein the slit is crank-shaped when viewed from the top. ### Claim 5 (depends on 1) The planar illumination device according to claim 1, wherein the first light blocking layer is a single-sided adhesive tape, and the second light blocking layer and the second light blocking sheet are double-sided adhesive tapes. ### Claim 6 (depends on 1) The planar illumination device according to claim 1, wherein the second light blocking sheet has a thickness that is approximately equal to the thickness of an area of the first light blocking sheet where the first light blocking layer and the second light blocking layer overlap each other. ### Claim 7 A planar illumination device comprising: a light source; a light guide plate including a light incident side surface on which the light source is arranged; a housing that includes side walls surrounding outer circumferential surfaces of the light source and the light guide plate; a first light blocking sheet that is adhered to an outer side surface and a top end surface of a side wall opposed to the light source among the side walls and that covers the top end surface, a top surface of the light source, and a part of a top surface of the light guide plate; and a second light blocking sheet that is adhered to top end surfaces of the side walls other than the side wall to which the first light blocking sheet is adhered, wherein the first light blocking sheet and the second light blocking sheet have different layer structures. ### Claim 8 (depends on 7) The planar illumination device according to claim 7, wherein the first light blocking sheet includes: a first light blocking layer; and a second light blocking layer that covers at least a part of a top surface of the first light blocking layer. ### Claim 9 (depends on 8) The planar illumination device according to claim 8, wherein the first light blocking layer extends from the outer side surface of the side wall to which the first blocking layer is adhered to a part of the top surface of the light source. ### Claim 10 (depends on 7) The planar illumination device according to claim 7, wherein a slit is formed between the first light blocking sheet and the second light blocking sheet. ### Claim 11 (depends on 10) The planar illumination device according to claim 10, wherein the slit is crank-shaped when viewed from the top. ### Claim 12 (depends on 8) The planar illumination device according to claim 8, wherein the first light blocking layer is a single-sided adhesive tape, and the second light blocking layer and the second light blocking sheet are double-sided adhesive tapes. ### Claim 13 (depends on 8) The planar illumination device according to claim 8, wherein the second light blocking sheet has a thickness that is approximately equal to the thickness of an area of the first light blocking sheet where the first light blocking layer and the second light blocking layer overlap each other.