# US 2018/0024425 A1 · Illumination device and image projection apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0024425 A1 - Document ID: US20180024425A1 - Status: Published application - Kind: A1 - Application number: 15/547,901 - Filed: 2016-02-09 - Published: 2018-01-25 - Earliest claimed: 2015-02-20 - Assignees: Ricoh Company, Ltd. - Inventors: Kazuhiro FUJITA; Takahiro KADO - Web page: https://patentgrep.com/patent/US20180024425A1 ## CPC - G03B 21/204: {using secondary light emission, e.g. luminescence or fluorescence (using different colours G03B33/00; if related to video signals H04N9/3197)} - G03B 21/16: Cooling; Preventing overheating - G03B 21/2013: {Plural light sources} - G03B 21/2066: {Reflectors in illumination beam (in projection beam G03B21/28)} - G03B 21/208: {Homogenising, shaping of the illumination light} - H04N 9/3152: {for shaping the light beam (beam shaping per se G02B27/09)} - 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) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract This invention is concerning an illumination device that can obtain illumination light efficiently. An illumination device 1 used in, for example, a projection display apparatus includes a light source and a light tunnel 14. The light tunnel 14 includes a light incident port 15, a light emission port 16, a light guide path 17, a reflection surface 20 surrounding the light guide path 17, a phosphor layer 19 that generates fluorescent light LF having a different wavelength range from that of excitation light LE when being excited by the excitation light LE, a condensing optical system 13 that diverges the excitation light LE in the vicinity of the light incident port 15 and guides the diverged light into the light tunnel 14 to irradiate the phosphor layer 19, and a wavelength selection element that reflects the fluorescent light LF toward the light emission port 16. ## Claims ### Claim 1 An illumination device, comprising: a light source that emits light having a predetermined wavelength range; a light incident part to which the light is incident from the light source; a light emission part from which the light is emitted; and a light guide member that includes a light guide path extending from the light incident part to the light emission part, wherein the light guide member includes a wavelength conversion member to convert the light into light having a different wavelength range from the light emitted from the light source, a wavelength selector to permeate the light emitted from the light source and to reflect the converted light is provided at the light incident part, the light guide member has a tapered shape in which a diameter gradually increases as it goes from one end to the other end, the light incident part is provided at a position closer to the one end of the light guide member than the other end of the light guide member and at the position facing the wavelength conversion member, and the light emission part is the other end of the light guide member. ### Claim 2 (depends on 1) The illumination device according to claim 1, further comprising an incident part at a position between the light source and the light guide member, wherein the incident part diverges the light emitted from the light source at a position in vicinity of the light incident part and allows the diverged light to enter the light guide member so as to irradiate the wavelength conversion member with the diverged light. ### Claim 3 (canceled) ### Claim 4 (canceled) ### Claim 5 (depends on 1) The illumination device according to claim 1, further comprising a second wavelength selector at the light emission part, wherein the second wavelength selector permeates the converted light and reflects excitation light. ### Claim 6 (depends on 1) The illumination device according to claim 1, wherein, in the light guide member, at least an inside surface provided with the wavelength conversion member is formed of a member having thermal conductivity. ### Claim 7 (depends on 1) The illumination device according to claim 1, wherein the light guide member includes a heat radiation structure on an outside surface opposite to an inside surface provided with the wavelength conversion member. ### Claim 8 (depends on 1) The illumination device according to claim 1, wherein the wavelength conversion member is a phosphor that generates fluorescent light containing green light when being excited by excitation light. ### Claim 9 An illumination device, comprising a light source that emits light having a predetermined wavelength range; a light incident part to which the light is incident from the light source; a light emission part from which the light is emitted; and a light guide member that includes a light guide path extending from the light incident part to the light emission part, wherein the light guide member includes a wavelength conversion member to convert the light into light having a different wavelength range from the light emitted from the light source, and a wavelength selector to selectively extract the converted light and to guide the extracted light toward the light emission part is provided at the light incident part. ### Claim 10 (depends on 9) The illumination device according to claim 9, wherein the wavelength selector permeates the light emitted from the light source and reflects the converted light toward the light emission part. ### Claim 11 (depends on 9) The illumination device according to claim 9, wherein the wavelength conversion member generates fluorescent light containing at least a red color component and a green color component. ### Claim 12 (depends on 11) The illumination device according to claim 11, further comprising a wavelength separator that separates the fluorescent light into red illumination light having a red light wavelength range and green illumination light having a green light wavelength range. ### Claim 13 (depends on 12) The illumination device according to claim 12, wherein the wavelength separator at least includes two areas each representing a first wavelength separator and a second wavelength separator, the first wavelength separator selectively extracts the green illumination light, the second wavelength separator selectively extracts the red illumination light, and the first wavelength separator and the second wavelength separator are sequentially switched on the optical path of the fluorescent light. ### Claim 14 (depends on 13) An image projection apparatus, comprising an illumination device according to claim 13, a single light valve that is illuminated with at least two color illumination light sequentially obtained by the illumination device and that generates an image modulated in response to each color, and a projection optical system that projects the generated image.