# US 11,442,348 B2 · Wavelength conversion element, phosphor wheel, light source device, and projection display apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,442,348 B2 - Document ID: US11442348B2 - Status: Granted - Kind: B2 - Application number: 17/141,503 - Filed: 2021-01-05 - Published: 2021-04-29 - Granted: 2022-09-13 - Earliest claimed: 2018-04-26 - Assignees: Panasonic Intellectual Property Management Co., Ltd. - Applicants: Panasonic Intellectual Property Management Co., Ltd. - Inventors: Takashi Ikeda; Makoto Maeda; Yusaku Nishikawa - Web page: https://patentgrep.com/patent/US11442348B2 ## 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)} - G02B 26/008: {in the form of devices for effecting sequential colour changes, e.g. colour wheels} - G03B 21/2066: {Reflectors in illumination beam (in projection beam G03B21/28)} - G03B 21/008: {using micromirror devices} - G03B 21/2073: {Polarisers in the lamp house (peculiar to electronic spatial light modulators H04N9/3197)} - 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) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A wavelength conversion element includes a first phosphor region and a second phosphor region. The second phosphor region is disposed in a thickness direction of the first phosphor region and has a phosphor particle with a particle size different from a particle size of a phosphor particle positioned in the first phosphor region. ## Claims ### Claim 1 A wavelength conversion element comprising: a first phosphor region including first phosphor particles; and a second phosphor region including second phosphor particles, wherein the first phosphor region is on the second phosphor region, the first phosphor particles have a peak emission of fluorescent light, the second phosphor particles have a peak emission of fluorescent light, the peak emission of the first phosphor particles is same in color as the peak emission of the second phosphor particles, and an average particle size of the first phosphor particles is larger than an average particle size of the second phosphor particles, the wavelength conversion element further comprising a third phosphor region including third phosphor particles, wherein the second phosphor region is between the first and the third phosphor regions, the third phosphor particles have a peak emission of fluorescent light, the peak emission of the third phosphor particles is same in color as the peak emissions of the first and the second phosphor particles, and an average particle size of the third phosphor particles is larger than the average particle size of the second phosphor particles. ### Claim 2 (depends on 1) The wavelength conversion element according to claim 1, wherein the first and the second phosphor particles are excited by blue excitation light. ### Claim 3 (depends on 1) The wavelength conversion element according to claim 1, wherein the average particle size of the second phosphor particles is larger than one micron. ### Claim 4 (depends on 1) The wavelength conversion element according to claim 1, wherein the average particle size of the second phosphor particles is larger than one-tenth of the average particles size of the first phosphor particles and less than one-fifth of the average particle size of the first phosphor particles. ### Claim 5 (depends on 1) The wavelength conversion element according to claim 1, wherein the average particle size of the second phosphor particles is lager larger than one-tenth of the average particle size of the third phosphor particles and less than one-fifth of the average particle size of the third phosphor particles. ### Claim 6 (depends on 1) A phosphor wheel comprising: the wavelength conversion element according to claim 1; a base plate on which the wavelength conversion element is provided; and a motor that rotationally drives the base plate. ### Claim 7 (depends on 6) The phosphor wheel according to claim 6, wherein the second phosphor region is between the first phosphor region and the base plate. ### Claim 8 (depends on 6) The phosphor wheel according to claim 6, wherein the wavelength conversion element has a ring shape. ### Claim 9 (depends on 6) The phosphor wheel according to claim 6, wherein the wavelength conversion element has a segment shape with a cutout portion in which a ring shape is partially cut. ### Claim 10 (depends on 9) The phosphor wheel according to claim 9, wherein the base plate has an opening corresponding to the cutout portion, and the wavelength conversion element and the opening are disposed at substantially a same distance from a rotation center of the phosphor wheel. ### Claim 11 (depends on 6) The phosphor wheel according to claim 6, wherein the wavelength conversion element has a ring shape, and a reflection layer is provided on a surface of a portion of the wavelength conversion element. ### Claim 12 (depends on 6) A light source device comprising the phosphor wheel according to claim 6. ### Claim 13 (depends on 12) A projection display apparatus comprising the light source device according to claim 12.