# US 7,746,303 B2 · Method and apparatus for extending the color depth of displays > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,746,303 B2 - Document ID: US7746303B2 - Status: Granted - Kind: B2 - Application number: 11/280,284 - Filed: 2005-11-17 - Published: 2007-05-17 - Granted: 2010-06-29 - Earliest claimed: 2005-11-17 - Assignees: Honeywell International Inc. - Inventors: Andrei Cernasov; Fernando R. De La Vega; Donald J. Porawski - Web page: https://patentgrep.com/patent/US7746303B2 ## CPC - G09G 3/3406: {Control of illumination source (illumination devices structurally associated with liquid crystal cells G02F1/1336)} - G09G 3/2018: {by time modulation using two or more time intervals} - G09G 2310/0237: Switching ON and OFF the backlight within one frame - G09G 2320/0271: Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping - G09G 2320/0633: by amplitude modulation of the brightness of the illumination source - G09G 2320/0646: Modulation of illumination source brightness and image signal correlated to each other - 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 method of extending color depth in a display includes determining pixel sub-intervals for pixel intervals in a video signal, modulating a transmissivity of a display panel of the display from one sub-interval to another sub-interval, and modulating backlight intensity of a backlight from the one sub-interval to the another sub-interval. ## Claims ### Claim 1 A display with extended color depth, comprising: a light source; a light source driver coupled to the light source; a transmissive display panel disposed adjacent to the light source; a display panel control circuit coupled to the display panel; and a dithering circuit coupled to the light source driver and display panel control circuit, the dithering circuit comprising: logic for determining pixel sub-intervals for pixel intervals in a video signal, logic for modulating a transmissivity of the display panel from one sub-interval to another sub-interval, and logic for modulating light source intensity from the one sub-interval to the another sub-interval. ### Claim 2 (depends on 1) The display of claim 1, wherein the dithering circuit further comprises: logic for synchronizing the modulating the light source intensity from one sub-interval to the another sub-interval and the modulating the transmissivity of the display panel from the one sub-interval to the another sub-interval. ### Claim 3 (depends on 2) The display of claim 2, wherein the light source driver further comprises: logic for modulating the intensity of the light source step-wise between the sub-intervals of each pixel interval. ### Claim 4 (depends on 2) The display of claim 2, wherein the logic for synchronizing comprises: logic for receiving a desired output of a pixel for a pixel interval; and logic for determining a modulation of the light source intensity. ### Claim 5 (depends on 4) The display of claim 4, wherein the logic for synchronizing, further comprises: logic for determining a modulation of the transmissivity of the pixel; and logic for synchronizing the determined modulation of the transmissivity of the pixel with the modulation of the light source intensity to produce the desired output. ### Claim 6 (depends on 5) The display of claim 5, wherein the display further comprises: logic for powering the light source based on the modulation of the light source; and logic for setting transmissivity of the pixel based on the determined modulation of the transmissivity of the pixel. ### Claim 7 A method of extending color depth in a display, comprising: determining pixel sub-intervals for pixel intervals in a video signal; modulating a transmissivity of a display panel of the display from one sub-interval to another sub-interval and in synchronization with the determined pixel sub-intervals; and modulating backlight intensity of a backlight from the one sub-interval to the another sub-interval and in synchronization with the determined pixel sub-intervals. ### Claim 8 (depends on 7) The method of claim 7, further comprising synchronizing the modulating the backlight intensity from one sub-interval to the another sub-interval and the modulating the transmissivity of the display panel from the one sub-interval to the another sub-interval. ### Claim 9 (depends on 8) The method of claim 8, wherein the backlight intensity is modulated step-wise between the sub-intervals of each pixel interval. ### Claim 10 (depends on 8) The method of claim 8, wherein the backlight intensity is modulated between sub-intervals such that an average of an intensity for the pixel interval is equal to an equivalent uniform backlight intensity. ### Claim 11 (depends on 8) The method of claim 8, wherein the backlight intensity is modulated in a binary pattern between sub-intervals. ### Claim 12 (depends on 8) The method of claim 8, wherein synchronizing the modulating the backlight intensity from one sub-interval to the another sub-interval and the modulating the transmissivity of the display panel from the one sub-interval to the another sub-interval, comprises: receiving a desired output of a pixel for a pixel interval; determining a modulation of the backlight intensity; and determining a modulation of the transmissivity of the pixel, wherein the modulation of the transmissivity is synchronized with the modulation of the backlight intensity to produce the desired output. ### Claim 13 (depends on 12) The method of claim 12, further comprising: powering the backlight based on the determined modulation of the backlight intensity; and setting the transmissivity of the pixel based on the determined modulation of the transmissivity of the pixel. ### Claim 14 A method of extending color depth in a display, comprising: determining pixel sub-intervals for pixel intervals in a video signal; determining a light source modulation for the pixel sub-intervals; modulating intensity of a light source based on the light source modulation; and synchronizing a transmittance of a display panel of the display with the light source modulation for each sub-interval. ### Claim 15 (depends on 14) The method of claim 14, wherein the light source modulation is step-wise between the sub-intervals of each pixel interval. ### Claim 16 (depends on 14) The method of claim 14, wherein the light source intensity is modulated between sub-intervals such that an average of an intensity for the pixel intervals is equal to an equivalent uniform light source intensity. ### Claim 17 (depends on 14) The method of claim 14, wherein the light source modulation is modulated in a binary pattern between sub-intervals. ### Claim 18 (depends on 14) The method of claim 14, further comprising: receiving a desired output of a pixel of the display panel for a pixel interval; and determining the light source modulation based on the received desired output. ### Claim 19 (depends on 18) The method of claim 18, further comprising: determining a modulation of the transmissivity of the pixel, wherein the modulation of the transmissivity is synchronized with the light source modulation to produce the desired output. ### Claim 20 (depends on 19) The method of claim 19, further comprising: powering the light source based on the light source modulation; and setting transmissivity of the pixel based on the determined modulation of the transmissivity of the pixel.