# US 8,149,252 B2 · Duty cycle calculation and implementation for solid state illuminators > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,149,252 B2 - Document ID: US8149252B2 - Status: Granted - Kind: B2 - Application number: 12/125,896 - Filed: 2008-05-22 - Published: 2009-11-26 - Granted: 2012-04-03 - Earliest claimed: 2008-05-22 - Assignees: Texas Instruments Incorporated - Inventors: Todd Alan Clatanoff - Web page: https://patentgrep.com/patent/US8149252B2 ## CPC - G09G 3/346: {based on modulation of the reflection angle, e.g. micromirrors (micromirrors devices per se G02B26/0833)} - G09G 3/2003: {Display of colours (specific for liquid crystal displays G09G3/3607)} - G09G 3/3413: {Details of control of colour illumination sources} - G09G 2320/0285: using tables for spatial correction of display data - G09G 2340/06: Colour space transformation - G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00) ## Abstract A display uses x illuminator systems to produce x primary colors and y overlap colors, which are combinations of primary colors, to illuminate a spatial light modulator in a display system. A first set of n duty cycles for the x primary colors over a frame is provided, wherein the display system can select any one of the duty cycles to produce a desired white point. A second set of n duty cycles of x+y colors over a frame corresponding to the first set of duty cycles is determined, where the second set of duty cycles are generated responsive to a specified desired allocation of the frame to the y overlap colors, such that each of the overlap colors can be displayed from a dark shade to a bright shade while maintaining a constant color point. ## Claims ### Claim 1 A method of controlling x illuminator systems to produce of x respective primary colors using a single one of the illuminator systems and y distinct overlap colors using two or more illuminator systems to illuminate a spatial light modulator in a display system, comprising the steps of: providing a first set of n duty cycles of the x primary colors over a frame, wherein the display system can select one of the duty cycles to produce a desired white point; determining an second set of n duty cycles of x+y colors over a frame corresponding to the first set of duty cycles, where the second set of duty cycles are generated responsive to a specified desired allocation of the frame to the y overlap colors, such that each of the overlap colors can be displayed from a dark shade to a bright shade while maintaining a constant color point. ### Claim 2 (depends on 1) The method of claim 1 wherein said primary colors are red, green and blue. ### Claim 3 (depends on 2) The method of claim 2 wherein said overlap colors are chosen from the group of cyan, yellow, magenta and white. ### Claim 4 (depends on 1) The method of claim 1 wherein said determining step comprises the steps of: generating a plurality of possible scenarios for said second set of duty cycles; and evaluating each scenario by calculating error functions relating the portions of the frame that each illuminator system is enabled relative to desired portions determined by the first set of duty cycles to determine an optimum scenario. ### Claim 5 (depends on 4) The method of claim 4 wherein the step of calculating error functions includes the step of calculating, for each duty cycle in the scenario, the difference between the illumination from all illuminator systems over a frame and the expected illumination based on the desired overlap allocation. ### Claim 6 (depends on 5) The method of claim 5 wherein the error function accumulates the difference for each duty cycle in the scenario. ### Claim 7 (depends on 4) The method of claim 4 wherein the step of calculating error functions includes the step of calculating, for each duty cycle in the scenario, the difference between the sum of the primary colors used in a frame according to the duty cycle and the expected sum of the primary colors within the frame. ### Claim 8 (depends on 7) The method of claim 7 wherein the error function accumulates the difference for each duty cycle in the scenario. ### Claim 9 (depends on 4) The method of claim 4 wherein the step of calculating error functions includes the step of calculating, for each duty cycle of the scenario, a difference between an expected portion of illumination for each primary color based on the apportionment of the primary colors in the corresponding duty cycle of the first set and the portion of the frame in which the illuminator system for the primary color would be enabled to produce either primary or overlap colors, according to the duty cycle of the scenario. ### Claim 10 (depends on 9) The method of claim 9 wherein the error function accumulates the difference for each duty cycle in the scenario. ### Claim 11 (depends on 4) The method of claim 4 wherein the step of calculating error functions includes the step of calculating, for each duty cycle in the scenario, the difference between an expected portion of illumination for each primary color based on the apportionment of the primary colors in the corresponding duty cycle of the first set and the portion of the frame in which the illuminator system for the primary color would be enabled for primary colors only, according to the duty cycle of the scenario. ### Claim 12 (depends on 11) The method of claim 11 wherein the error function accumulates the difference for each duty cycle in the scenario. ### Claim 13 (depends on 1) The method of claim 1 wherein said determining step maintains, for each overlap color, a constant ratio between the portion frame within the overlap color in which an illuminator is enabled and the portion of the frame in which the illuminator is used to produce a primary color. ### Claim 14 (depends on 1) The method of claim 1 wherein one or more of the illuminator systems producing an overlap color may be enabled for less than all of the portion of the frame allocated to the overlap color. ### Claim 15 (depends on 4) The method of claim 4 wherein the step of calculating error functions includes the step of calculating, for each duty cycle of a scenario, a portions of an overlap color in which one of the illuminator systems producing the overlap color is not enabled. ### Claim 16 (depends on 4) The method of claim 4 wherein the step of calculating error functions includes the step of calculating, for each duty cycle of a scenario, a portions of an overlap color in which one of the illuminator systems producing the overlap color is enabled at less than full intensity. ### Claim 17 (depends on 4) The method of claim 4 wherein each error function is weighted. ### Claim 18 (depends on 1) The method of claim 1 wherein a tolerance is provided to allow the allocation of the overlap colors in a duty cycle of the second set to vary from the specified desired allocation within a certain range. ### Claim 19 (depends on 4) The method of claim 4 wherein the error functions account for a non-ideal ramping by each illumination system ramping between a low intensity and a full intensity state. ### Claim 20 (depends on 4) The method of claim 4 wherein the error functions account for a non-ideal ramping by each illumination system ramping between a full intensity and a low intensity state. ### Claim 21 (depends on 4) The method of claim 4 wherein the error functions account for a degradation of intensity over time of an enabled illumination system. ### Claim 22 (depends on 4) The method of claim 4 wherein the error functions for different scenarios are compared using optimization software. ### Claim 23 (depends on 1) The method of claim 1 wherein the determining step is performed in real-time during operation of a display system. ### Claim 24 A display system comprising: x illuminator systems to produce of x respective primary colors using a single one of the illuminator systems and y distinct overlap colors using two or more illuminator systems, said illuminator systems illuminating a spatial light modulator in a display system; an electronically readable table including a first set of n duty cycles of the x primary colors over a frame, wherein the display system can select one of the duty cycles to produce a desired white point; processing circuitry for determining an second set of n duty cycles of x+y colors over a frame corresponding to the first set of duty cycles, where the second set of duty cycles are generated responsive to a specified desired allocation of the frame to the y overlap colors, such that each of the overlap colors can be displayed from a dark shade to a bright shade while maintaining a constant color point. ### Claim 25 (depends on 24) The display system of claim 24 wherein said primary colors are red, green and blue. ### Claim 26 (depends on 25) The display system of claim 25 wherein said overlap colors are chosen from the group of cyan, yellow, magenta and white. ### Claim 27 (depends on 25) The display system of claim 25 wherein said processing circuitry performs the steps of: generating a plurality of possible scenarios for said second set of duty cycles; and evaluating each scenario by calculating error functions relating the portions of the frame that each illuminator system is enabled relative to desired portions determined by the first set of duty cycles to determine an optimum scenario.