# US 9,641,714 B2 · Light guide and image reading apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,641,714 B2 - Document ID: US9641714B2 - Status: Granted - Kind: B2 - Application number: 14/766,677 - Filed: 2014-02-14 - Published: 2016-01-14 - Granted: 2017-05-02 - Earliest claimed: 2013-02-21 - Assignees: Mitsubishi Electric Corporation - Applicants: Mitsubishi Electric Corporation - Inventors: Taku Matsuzawa; Kosaku Yamagata; Tadashi Minobe; Yasuhiro Nakamura; Hiroyuki Kawano - Web page: https://patentgrep.com/patent/US9641714B2 ## CPC - H04N 1/02855: {in combination with a light guide, e.g. optical fibre, glass plate (light-guides per se G02B6/00)} - G02B 6/0008: {the light being emitted at the end of the fibre} - G02B 6/001: {the light being emitted along at least a portion of the lateral surface of the fibre} - G02B 27/0994: {Fibers, light pipes (optical fibers per se G02B6/02)} - G06V 40/1365: {Matching; Classification} - H04N 1/00167: {Processing or editing (H04N1/00196 - H04N1/00201 take precedence)} - H04N 1/00188: {Printing, e.g. prints or reprints (H04N1/0019, H04N1/00196 take precedence)} - H04N 1/028: for picture information pick-up - H04N 1/04: Scanning arrangements {, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa}(H04N1/387 takes precedence) - G02B 3/06: with cylindrical or toric faces - H04N 2201/03125: Light guide upstream of the scanned picture elements - H04N 2201/03137: Reflecting element downstream of the scanned picture elements - H04N 2201/03145: Photodetector - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING ## Abstract A light guide including a light scattering portion that reflects light guided inside the light guide, and a light emitting surface portion emitting light reflected by the light scattering portion to outside the light guide. A light emitting surface portion includes first and second light emitting surface portions, the first light emitting surface portion has a longer circumferential length than that of the second light emitting surface portion in the transversal cross section, and circumference curvature of the first light emitting surface portion in the transversal cross section increases away from the second light emitting surface portion. A normal line to the light scattering portion, passing through the center of the light scattering portion in the transversal cross section, intersects with the first light emitting surface portion, at a point at a near side to the second light emitting surface portion in the transversal cross section. ## Claims ### Claim 1 A light guide extending along a longitudinal direction and having an arc-like outer shape portion at least in a part of a transversal cross section being a cross section along a transversal direction that intersects with the longitudinal direction, comprising: a light scattering portion formed on a side surface of the light guide along the longitudinal direction and for reflecting light guided inside the light guide; and a light emitting surface portion including at least a part of the outer shape portion and formed on a side surface along the longitudinal direction located opposite to the light scattering portion, and for emitting light reflected by the light scattering portion to the outside of the light guide, wherein, the light emitting surface portion is configured with a first light emitting surface portion and a second light emitting surface portion that are connected continuously along a plurality of inflection points arranged along the longitudinal direction, the first light emitting surface portion has a longer circumferential length than that of the second light emitting surface portion in the transversal cross section, and a curvature of a circumference of the first light emitting surface portion in the transversal cross section becomes larger as getting away from the second light emitting surface portion to increase a region of uniform illuminance in the transversal direction on a reading target of light emitted by the first light emitting surface portion and the second light emitting surface portion; and a normal line to the light scattering portion, passing through a center of the light scattering portion in the transversal cross section, is arranged so as to intersect with the first light emitting surface portion, and a point where the normal line intersects with the first light emitting surface portion is arranged in the circumference of the first light emitting surface portion at a near side to the second light emitting surface portion in the transversal cross section, and the inflection points are closer, along the transversal direction, to the second light emitting surface portion than the point where the normal line intersects with the first light emitting surface portion. ### Claim 2 (depends on 1) The light guide according to claim 1, wherein the light scattering portion is formed on a planar portion being flat and provided in a side surface of the light guide along the longitudinal direction. ### Claim 3 (depends on 2) The light guide according to claim 2, wherein a second planar portion being flat and provided in a side surface of the light guide along the longitudinal direction is disposed between the planar portion and the first light emitting surface portion. ### Claim 4 (depends on 2) The light guide according to claim 2, wherein a third planar portion being flat and provided in a side surface of the light guide along the longitudinal direction is disposed between the planar portion and the second light emitting surface portion. ### Claim 5 (depends on 1) An image reading apparatus comprising: the light guide according to claim 1; an imaging optical system for converging reflected light, the reflected light being light emitted from the light guide and reflected by a reading target; and an optical receiver for receiving light converged by the imaging optical system. ### Claim 6 (depends on 1) An image reading apparatus comprising: at least two light guides according to claim 1, wherein a plurality of the light guides are disposed so that the normal lines intersect with each other in the transversal cross section, and a point at which the normal lines intersect with each other is arranged between a reading target and the light guides; an imaging optical system for converging reflected light, the reflected light being light emitted from the light guide and reflected by the reading target; and an optical receiver for receiving light converged by the imaging optical system.