# US 8,542,221 B1 · Method and system for optimizing display power reduction through a continuously variable refresh rate adjustment > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,221 B1 - Document ID: US8542221B1 - Status: Granted - Kind: B1 - Application number: 12/492,020 - Filed: 2009-06-25 - Granted: 2013-09-24 - Earliest claimed: 2009-06-25 - Assignees: NVIDIA Corporation - Applicants: David Wyatt; Laurence Harrison - Inventors: David Wyatt; Laurence Harrison - Web page: https://patentgrep.com/patent/US8542221B1 ## CPC - G09G 5/36: characterised by the display of a graphic pattern, e.g. using an all-points-addressable [APA] memory - G06F 1/3265: {Power saving in display device} - G06F 15/00: Digital computers in general (details G06F1/00 – G06F13/00); Data processing equipment in general - G09G 5/00: Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators (image data processing or generation, in general G06T) - G09G 5/026: {Control of mixing and/or overlay of colours in general (G09G5/022 and G09G5/024 take precedence)} - G09G 3/3611: {Control of matrices with row and column drivers} - G09G 5/14: Display of multiple viewports - G09G 2320/0613: The adjustment depending on the type of the information to be displayed - G09G 2320/103: Detection of image changes, e.g. determination of an index representative of the image change - G09G 2330/021: Power management, e.g. power saving - G09G 2340/0435: Change or adaptation of the frame rate of the video stream - G09G 2340/10: Mixing of images, i.e. displayed pixel being the result of an operation, e.g. adding, on the corresponding input pixels - G09G 2340/12: Overlay of images, i.e. displayed pixel being the result of switching between the corresponding input pixels - G09G 2340/125: wherein one of the images is motion video - G09G 2350/00: Solving problems of bandwidth in display systems - Y02D 10/00: Energy efficient computing, e.g. low power processors, power management or thermal management - 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) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract One embodiment of the present invention sets forth a technique for continuously adjusting a variable refresh rate to reduce the power consumption of a display device. The refresh rate of the display device tracks the effective frame rate of the content being displayed. As the effective frame rate of the content decreases, the refresh rate is lowered until a minimum value is reached. When the effective frame rate of the content equals the refresh rate, the refresh rate is increased until the refresh rate exceeds the effective frame rate of the content or until a maximum value is reached. ## Claims ### Claim 1 A computer-implemented method for continuously adjusting a refresh rate used to display frames of image data, the method comprising: identifying a first display frame that includes an image surface; identifying a usage model of the first display frame indicating that the-image surface is a primary surface; determining whether content associated with the image surface is fixed frame rate content or variable frame rate content; if the content associated with the image surface is fixed frame rate content, then: computing a computed refresh rate based on an integer multiple of a frame rate of the fixed frame rate content, or if the content associated with the image surface is variable frame rate content, then: computing a computed refresh rate based on an effective frame rate of the variable frame rate content; and sending image data representing the first display frame at the computed refresh rate to a display device to display the first display frame. ### Claim 2 (depends on 1) The method of claim 1, wherein the content associated with the image surface is variable frame rate content, and the computed refresh rate equals the effective frame rate of the variable frame rate content. ### Claim 3 (depends on 1) The method of claim 1, wherein the content associated with the image surface is variable frame rate content, and the computed refresh rate is within a range of the effective frame rate of the variable frame rate using a hysteresis padding factor. ### Claim 4 (depends on 1) The method of claim 1, further comprising clamping the computed refresh rate to a maximum refresh rate when the computed refresh rate is greater than the maximum refresh rate and a hysteresis padding factor. ### Claim 5 (depends on 1) The method of claim 1, further comprising clamping the computed refresh rate to a minimum refresh rate when the computed refresh rate is less than the minimum refresh rate. ### Claim 6 (depends on 1) The method of claim 1, wherein the usage model of the first display frame comprises a full-screen display mode. ### Claim 7 (depends on 1) The method of claim 1, wherein the usage model of the first display frame comprises a windowed display mode. ### Claim 8 (depends on 1) The method of claim 1, wherein the usage model of the first display frame comprises an active desktop, the content associated with the image surface is variable frame rate content, and the computed refresh rate equals a maximum refresh rate when the effective frame rate of the variable frame rate image surface is increasing and the computed refresh rate is halfway between a current refresh rate and the effective frame rate of the variable frame rate image surface. ### Claim 9 (depends on 1) The method of claim 1, further comprising repeating the steps of identifying a first display frame, identifying a usage model, determining, computing, and sending to compute additional computed refresh rates and display additional frames of the image data using the additional computed refresh rates. ### Claim 10 A non-transitory computer-readable medium that includes instructions that, when executed by a general purpose processor, configure the general purpose processor to continuously adjust a refresh rate used to display frames of image data, by performing the steps of: identifying a first display frame that includes an image surface; identifying a usage model of the first display frame indicating that the image surface is a primary surface; determining whether content associated with the image surface is fixed frame rate content or variable frame rate content; if the content associated with the image surface is fixed frame rate content, then: computing a computed refresh rate based on an integer multiple of a frame rate of the fixed frame rate content, or if the content associated with the image surface is variable frame rate content, then: computing a computed refresh rate based on an effective frame rate of the variable frame rate content; and sending image data representing the first display frame at the computed refresh rate to a display device to display the first display frame. ### Claim 11 A computing device for continuously adjusting a refresh rate used to display frames of image data, the computing device comprising: a memory system for storing frames of image data including a first display frame; a processing unit configured to execute a display device driver that performs a set of operations comprising: identifying that the first display frame includes an image surface; identifying a usage model of the first display frame indicating that the image surface is a primary surface; determining whether content associated with the image surface is fixed frame rate content or variable frame rate content; and if the content associated with the image surface is fixed frame rate content, then: computing a computed refresh rate based on an integer multiple of a frame rate of the fixed frame rate content, or if the content associated with the image surface is variable frame rate content, then: computing a computed refresh rate based on an effective frame rate of the variable frame rate content; and a display controller configured to send image data representing the first display frame at the computed refresh rate to display the first display frame on a display device. ### Claim 12 (depends on 11) The computing device of claim 11, wherein the content associated with the image surface is variable frame rate content, and the computed refresh rate equals the effective frame rate of the variable frame rate content. ### Claim 13 (depends on 11) The computing device of claim 11, wherein the content associated with the image surface is variable frame rate content, and the computed refresh rate is within a range of the effective frame rate of the variable frame rate using a hysteresis padding factor. ### Claim 14 (depends on 11) The computing device of claim 11, further comprising clamping the computed refresh rate to a maximum refresh rate when the computed refresh rate is greater than the maximum refresh rate and a hysteresis padding factor. ### Claim 15 (depends on 11) The computing device of claim 11, further comprising clamping the computed refresh rate to a minimum refresh rate when the computed refresh rate is less than the minimum refresh rate. ### Claim 16 (depends on 11) The computing device of claim 11, wherein the usage model of the first display frame comprises a full-screen display mode. ### Claim 17 (depends on 11) The computing device of claim 11, wherein the usage model of the first display frame comprises a windowed display mode. ### Claim 18 (depends on 11) The computing device of claim 11, wherein the usage model of the first display frame comprises an active desktop, the content associated with the image surface is variable frame rate content, and the computed refresh rate equals a maximum refresh rate when the effective frame rate of the variable frame rate image surface is increasing and the computed refresh rate is halfway between a current refresh rate and the effective frame rate of the variable frame rate image surface. ### Claim 19 (depends on 11) The computing device of claim 11, wherein the processing unit is further configured to repeat the operations of identifying a first display frame, identifying a usage model, determining, computing, and sending to compute additional computed refresh rates and the display controller is further configured to display additional frames of the image data using the additional computed refresh rates.