# US 7,609,442 B2 · Synchronizing screen > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,442 B2 - Document ID: US7609442B2 - Status: Granted - Kind: B2 - Application number: 11/250,068 - Filed: 2005-10-13 - Published: 2007-04-19 - Granted: 2009-10-27 - Earliest claimed: 2005-10-13 - Assignees: Hewlett-Packard Development Company, L.P. - Inventors: Peter James Fricke; Timothy Emmerich; Gregory J. May - Web page: https://patentgrep.com/patent/US7609442B2 ## CPC - G03B 21/56: Projection screens - 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) ## Abstract Embodiments of synchronizing modification of an optical characteristic of a screen are disclosed. ## Claims ### Claim 1 A method comprising: controlling a timing of modifying an optical characteristic of a projection screen using (1) a timing of a color component of light incident on a sensor, the light including ambient light and projected light forming an image on the projection screen, and (2) a signal related to a timing of the projected light. ### Claim 2 (depends on 1) The method of claim 1, wherein the controlling comprises utilizing a phase-locked loop to achieve phase lock of a synchronizing signal to a signal provided by the sensor based on the signal. ### Claim 3 (depends on 1) The method of claim 1, further comprising generating the signal using a clock of a projection system controller. ### Claim 4 (depends on 1) The method of claim 1, further comprising generating the signal using a color wheel timing of a projector. ### Claim 5 (depends on 1) The method of claim 1, wherein the optical characteristic is one of a reflectivity and an absorbance. ### Claim 6 (depends on 1) The method of claim 1, further comprising determining a peak of an intensity of a plurality of colors of the light incident on the sensor. ### Claim 7 (depends on 1) The method of claim 1, wherein, the light comprises projected light. ### Claim 8 (depends on 1) The method of claim 1, wherein, the modifying the optical characteristic comprises modifying the optical characteristic of all pixels of the screen. ### Claim 9 (depends on 1) The method of claim 1, further comprising adjusting one of reflectivity, absorbance, or transmissiveness for time intervals corresponding to red, green, and blue segments of a color wheel of a projector according to the controlling. ### Claim 10 (depends on 1) The method of claim 1, further comprising modifying one of reflectivity, absorbance, or transmissiveness of the screen over a portion of a color segment time interval of a projector to achieve a desired average of the optical characteristic over the segment interval. ### Claim 11 (depends on 1) The method of claim 1 further comprising reflecting both the projected light and ambient light from the screen. ### Claim 12 (depends on 11) The method of claim 11 further comprising controlling the optical characteristic of the screen based additionally upon sensed color content of ambient light. ### Claim 13 An apparatus comprising: a screen having an adjustable optical characteristic; a sensor to provide a sensor signal indicating timing of a color component of light; and a circuit to generate a synchronization signal using the sensor signal to synchronize adjustment of the optical characteristic with the timing of the color component. ### Claim 14 (depends on 13) The apparatus of claim 13, wherein the synchronizer comprises a phase-locked loop coupled to receive the sensor signal and a qualification signal. ### Claim 15 (depends on 13) The apparatus of claim 13, further comprising a controller to generate a qualification signal using a clock signal provided by the projection system controller. ### Claim 16 (depends on 13) The apparatus of claim 13, further comprising a projector to generate a qualification signal according to timing of segments of a color wheel. ### Claim 17 (depends on 13) The apparatus of claim 13, wherein the screen is a projection screen selected from a group comprising a rear projection screen and a front projection screen. ### Claim 18 (depends on 13) The apparatus of claim 13, wherein the sensor comprises a plurality of sensors, wherein each of the plurality of sensors corresponds to a primary color. ### Claim 19 (depends on 13) The apparatus of claim 13, further comprising a projector to project at least a portion of the light on the screen. ### Claim 20 (depends on 13) The apparatus of claim 13, further comprising a projection system controller to adjust one of a reflectivity, absorbance, or transmissiveness of the screen to compensate for ambient light. ### Claim 21 (depends on 13) The apparatus of claim 13, further comprising a control data decoder to extract control data from the sensor signal. ### Claim 22 (depends on 21) The apparatus of claim 21, wherein the control data is one or more of an offset or a sampling period. ### Claim 23 (depends on 13) The apparatus of claim 13, wherein the sensor is configured to sense ambient light impinging the screen. ### Claim 24 A computer-readable medium comprising: stored instructions to synchronize modification of an optical characteristic of a projection screen with a timing of a change between color components of light of an image incident on the screen, wherein the synchronizing uses a timing of a color component of light incident on a sensor and a signal related to a timing of projected light. ### Claim 25 (depends on 24) The computer-readable medium of claim 24, further comprising stored instructions to modify the optical characteristic of all pixels of the screen. ### Claim 26 (depends on 24) The computer-readable medium of claim 24, further comprising stored instructions to modify the optical characteristic of the screen in response to data provided by the sensor. ### Claim 27 An apparatus comprising: means for sensing an occurrence of a color component of light; and means for synchronizing an optical characteristic modification of a screen based on a qualification signal and the occurrence of the color component of light. ### Claim 28 (depends on 27) The apparatus of claim 27, further comprising means for locking onto a signal provided by the sensor. ### Claim 29 (depends on 27) The apparatus of claim 27, further comprising means for modifying the optical characteristic of the screen in response to an ambient light contribution.