# US 10,371,937 B2 · Projection display apapratus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,371,937 B2 - Document ID: US10371937B2 - Status: Granted - Kind: B2 - Application number: 15/888,215 - Filed: 2018-02-05 - Published: 2018-08-16 - Granted: 2019-08-06 - Earliest claimed: 2017-02-10 - Assignees: Canon Kabushiki Kaisha - Applicants: Canon Kabushiki Kaisha - Inventors: Shinya Ohara; Tetsuya Kagawa - Web page: https://patentgrep.com/patent/US10371937B2 ## CPC - G02B 26/008: {in the form of devices for effecting sequential colour changes, e.g. colour wheels} - G02B 27/1006: {for splitting or combining different wavelengths (G02B27/1086, G02B27/141 take precedence)} - G02B 27/141: {using dichroic mirrors} - G03B 21/16: Cooling; Preventing overheating - 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 21/206: {Control of light source other than position or intensity} - H04N 5/63: Generation or supply of power specially adapted for television receivers - H04N 9/3144: {Cooling systems (cooling of liquid crystal cells in general G02F1/133382; cooling of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/16)} - H04N 9/3155: {for controlling the light source (light source control per se H05B35/00 – H05B47/00; control of an illumination source for displays in general G09G3/3406)} - H04N 9/3158: {for controlling the spectrum} - H04N 9/3179: {Video signal processing therefor} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - 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 A projection display apparatus (1) includes a wavelength conversion element (11) that converts a wavelength of light from a light source, a driver (13) that rotates the wavelength conversion element, and an internal power supply (15) that stores power in advance and to be used for an operation of the projection display apparatus after a supply of power from an external power supply is cut off, and the driver rotates the wavelength conversion element at the predetermined number of rotations per unit time by using the power of the internal power supply. ## Claims ### Claim 1 A projection display apparatus comprising: a light source; a wavelength conversion element configured to convert a wavelength of light from the light source; a driver configured to rotate the wavelength conversion element; an image generator configured to generate an image by using light from the light source and light wavelength-converted by the wavelength conversion element; and a controller configured to control the light source, the driver, and the image generator, wherein the controller is configured to: in a first mode to project an image with the light source turned on, rotate the wavelength conversion element at the first number of rotations per unit time, in a second mode to supply the light source with power which is smaller than that supplied to the light source in the first mode, rotate the wavelength conversion element with the second number of rotations per unit timewhich is smaller than the first number of rotations per unit time, and in a third mode to supply the light source with power which is smaller than that supplied to the light source in the first mode and to supply the image generator with power that is smaller than that supplied to the image generator in the first mode, rotate the wavelength conversion element with the third number of rotations per unit timewhich is smaller than the second number of rotations per unit time. ### Claim 2 (depends on 1) The projection display apparatus according to claim 1, wherein the controller is configured to maintain the number of rotations per unit time of the wavelength conversion element in each of the second mode and the third mode. ### Claim 3 (depends on 1) The projection display apparatus according to claim 1, wherein when transferring from the first mode to the second mode or the third mode, the controller is configured to set the number of rotations per unit time of the wavelength conversion element to the fourth number of rotations per unit time that is the number of rotations per unit time between the first number of rotations per unit time and the second number of rotations per unit time or between the first number of rotations per unit time and the third number of rotations per unit time. ### Claim 4 (depends on 1) The projection display apparatus according to claim 1, wherein when transferring from the first mode to the second mode or the third mode, the controller is configured to change the number of rotations per unit time of the wavelength conversion element at a specific rate of change. ### Claim 5 (depends on 4) The projection display apparatus according to claim 4, further comprising a temperature acquirer configured to acquire a temperature of the wavelength conversion element, wherein the controller is configured to change a rate of change of the number of rotations per unit time of the wavelength conversion element based on the temperature of the wavelength conversion element. ### Claim 6 (depends on 5) The projection display apparatus according to claim 5, wherein when the temperature is a first temperature, the controller is configured to set the specific rate of change to a first rate of change, and wherein when the temperature is a second temperature that is lower than the first temperature, the controller is configured to set the specific rate of change to a second rate of change that is larger than the first rate of change. ### Claim 7 (depends on 1) The projection display apparatus according to claim 1, wherein the second mode is a mode to turn off the light source, and the third mode is a mode to turn off the light source and stop an operation of the image generator. ### Claim 8 (depends on 1) The projection display apparatus according to claim 1, wherein each of the first to third modes is settable while power of the projection display apparatus is turned on. ### Claim 9 (depends on 1) The projection display apparatus according to claim 1, wherein in each of the second and third modes, power supplied to the light source is larger than zero.