# US 11,443,704 B1 · Backlight dimming method and control circuit for variable refresh rate display, and display apparatus using same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,443,704 B1 - Document ID: US11443704B1 - Status: Granted - Kind: B1 - Application number: 17/487,591 - Filed: 2021-09-28 - Granted: 2022-09-13 - Earliest claimed: 2021-06-03 - Assignees: Anax Technology Corp. - Applicants: Anax Technology Corp. - Inventors: Sung-Wei Chiang; Shih-Yu Hsieh; Hung-Cheng Chang - Web page: https://patentgrep.com/patent/US11443704B1 ## CPC - G09G 3/3426: {the different display panel areas being distributed in two dimensions, e.g. matrix} - G09G 5/10: Intensity circuits - G09G 2320/064: by time modulation of the brightness of the illumination source - G09G 2320/0653: Controlling or limiting the speed of brightness adjustment of the illumination source - G09G 2320/0686: with two or more screen areas displaying information with different brightness or colours - G09G 2340/0435: Change or adaptation of the frame rate of the video stream - 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 backlight dimming method for backlighting an LCD panel having a variable refresh rate with an LED module, the variable refresh rate having a maximum refresh rate, the LED module having at least one LED sub-zone, the LED sub-zone including a plurality of LEDs, and the method including: using a controller to generate a secondary synchronizing signal having a frequency higher than the maximum refresh rate; and using the controller to update dimming values for the at least one LED sub-zone at one or more pulses of the secondary synchronizing signal with current dimming data after the controller has received the current dimming data from a scaler. ## Claims ### Claim 1 A backlight dimming method for backlighting an LCD panel having a variable refresh rate with an LED module, the variable refresh rate having a maximum refresh rate and being determined by a first synchronizing signal having a variable frequency, the LED module having at least one LED sub-zone, the LED sub-zone including a plurality of LEDs, and the method including: using a controller to generate a secondary synchronizing signal having a frequency higher than the maximum refresh rate, wherein the secondary synchronizing signal is not synchronized with the first synchronizing signal; using the controller to update dimming values for the at least one LED sub-zone at one or more pulses of the secondary synchronizing signal with current dimming data after the controller has received the current dimming data from a dimming data controller; and using at least one driver circuit to refresh the at least one LED sub-zone a plurality of times with a plurality of groups of sub-dimming values for each said LED subzone during a time period between two consecutive said pulses of the secondary synchronizing signal, wherein the plurality of groups of sub-dimming values add up to a value of the current dimming data for each said LED sub-zone. ### Claim 2 (depends on 1) The backlight dimming method of claim 1, further including using at least one driver circuit to refresh the at least one LED sub-zone once with the current dimming data during a time period between two consecutive said pulses of the secondary synchronizing signal. ### Claim 3 (depends on 1) The backlight dimming method of claim 1, wherein the current dimming data is transmitted in a series format from the dimming data controller. ### Claim 4 (depends on 1) The backlight dimming method of claim 1, wherein the current dimming data is derived by undergoing a series-to-parallel transformation. ### Claim 5 A control circuit having a controller and a driver circuit for performing a backlight dimming method for backlighting an LCD panel having a variable refresh rate with an LED module, the variable refresh rate having a maximum refresh rate and being determined by a first synchronizing signal having a variable frequency, the LED module having at least one LED sub-zone, the LED sub-zone including a plurality of LEDs, and the method including: using the controller to generate a secondary synchronizing signal having a frequency higher than the maximum refresh rate, wherein the secondary synchronizing signal is not synchronized with the first synchronizing signal; and using the controller to update dimming values for the at least one LED sub-zone at one or more pulses of the secondary synchronizing signal with current dimming data after the controller has received the current dimming data from a dimming data controller; wherein the at least one driver circuit is used to refresh the at least one LED sub-zone a plurality of times with a plurality of groups of sub-dimming values for each said LED subzone during a time period between two consecutive said pulses of the secondary synchronizing signal, wherein the plurality of groups of sub-dimming values add up to a value of the current dimming data for each said LED sub-zone. ### Claim 6 (depends on 5) The control circuit of claim 5, wherein the at least one driver circuit is used to refresh the at least one LED sub-zone once with the current dimming data during a time period between two consecutive said pulses of the secondary synchronizing signal. ### Claim 7 (depends on 5) The control circuit of claim 5, wherein the current dimming data is transmitted in a series format from the dimming data controller. ### Claim 8 (depends on 5) The control circuit of claim 5, wherein the current dimming data is derived by undergoing a series-to-parallel transformation. ### Claim 9 A display apparatus comprising a control circuit, an LCD panel having a variable refresh rate and an LED module having at least one LED sub-zone, the LED sub-zone including a plurality of LEDs, the control circuit having a controller and at least one driver circuit for performing a backlight dimming method for backlighting the LCD panel with the LED module, the variable refresh rate having a maximum refresh rate and being determined by a first synchronizing signal having a variable frequency, and the method including: using the controller to generate a secondary synchronizing signal having a frequency higher than the maximum refresh rate, wherein the secondary synchronizing signal is not synchronized with the first synchronizing signal; and using the controller to update dimming values for the at least one LED sub-zone at one or more pulses of the secondary synchronizing signal with current dimming data after the controller has received the current dimming data from a dimming data controller; wherein the at least one driver circuit is used to refresh the at least one LED sub-zone a plurality of times with a plurality of groups of sub-dimming values for each said LED subzone during a time period between two consecutive said pulses of the secondary synchronizing signal, wherein the plurality of groups of sub-dimming values add up to a value of the current dimming data for each said LED sub-zone. ### Claim 10 (depends on 9) The display apparatus of claim 9, wherein the at least one driver circuit is used to refresh the at least one LED sub-zone once with the current dimming data during a time period between two consecutive said pulses of the secondary synchronizing signal. ### Claim 11 (depends on 9) The display apparatus of claim 9, wherein the current dimming data is transmitted in a series format from the dimming data controller. ### Claim 12 (depends on 9) The display apparatus of claim 9, wherein the current dimming data is derived by undergoing a series-to-parallel transformation.