# US 10,311,808 B1 · Display latency calibration for liquid crystal display > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,311,808 B1 - Document ID: US10311808B1 - Status: Granted - Kind: B1 - Application number: 15/495,654 - Filed: 2017-04-24 - Granted: 2019-06-04 - Earliest claimed: 2017-04-24 - Assignees: Facebook Technologies, LLC - Applicants: Facebook Technologies, LLC - Inventors: Evan M. Richards; Matthew Robert Fulghum - Web page: https://patentgrep.com/patent/US10311808B1 ## CPC - G09G 3/36: using liquid crystals - G06F 1/163: {Wearable computers, e.g. on a belt} - G09G 3/3648: {using an active matrix (G09G3/367 - G09G3/3696 take precedence)} - G09G 2310/08: Details of timing specific for flat panels, other than clock recovery - G09G 2320/0233: Improving the luminance or brightness uniformity across the screen - G09G 2320/0252: Improving the response speed - G09G 2320/0261: in the context of movement of objects on the screen or movement of the observer relative to the screen - G09G 2320/0285: using tables for spatial correction of display data - G09G 2320/0295: by monitoring each display pixel - G09G 2320/041: Temperature compensation - G09G 2320/064: by time modulation of the brightness of the illumination source - G09G 2320/0646: Modulation of illumination source brightness and image signal correlated to each other - G09G 2320/0693: Calibration of display systems - G09G 2320/103: Detection of image changes, e.g. determination of an index representative of the image change - 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) ## Abstract A system for calibrating a liquid crystal display (LCD) includes a plurality of temperature sensors, a storage medium, and a controller. Each temperature sensor measures a current temperature of at least one pixel in the LCD. The storage medium stores information about latencies for any LC-based pixel, wherein each latency corresponds to a time period for transition from a starting to an ending illumination state for one temperature of the LC-based pixel. The controller determines, based on the current temperature, the transition information and frame information, a time for each pixel in at least a portion of the LCD to transition from a first to a second illumination state. The controller computes, based on transition times, an LC transition time for at least the portion of the LCD and performs calibration of at least the portion of the LCD based on the LC transition time. ## Claims ### Claim 1 A system comprising: a liquid crystal display (LCD) having a plurality of pixels; a plurality of temperature sensors coupled to at least a portion of the plurality of pixels, each temperature sensor of the plurality of temperature sensors configured to measure a current temperature associated with at least one pixel in at least the portion of the plurality of pixels; a storage medium configured to store transition information about latencies for a pixel of the LCD, each latency corresponds to a time period for transition from a defined start state to a defined end state for one temperature associated with the pixel, wherein the defined start state is related to an intensity of light emitted from the pixel in a first time instant and the defined end state is related to another intensity of light emitted from the pixel in a second time instant consecutive to the first time instant; and a controller coupled to the plurality of temperature sensors and the storage medium, the controller configured to: obtain frame information related to at least two consecutive frames of video content to be displayed on at least the portion of the plurality of pixels, determine, based on the current measured temperature, the transition information and the frame information, a transition time for each pixel in at least the portion of the plurality of pixels to transition from a start state to an end state for the current measured temperature of that pixel, wherein the start state is related to a first intensity of light emitted from that pixel for a first frame of the at least two consecutive frames and the end state is related to a second intensity of light emitted from that pixel for a second frame of the at least two consecutive frames, compute an effective liquid crystal (LC) transition time for at least the portion of the plurality of pixels as a longest time period of the determined transition times for all pixels in at least the portion of the plurality of pixels, and calibrate at least the portion of the plurality of pixels of the LCD based on the effective LC transition time when the video content is displayed on at least the portion of the plurality of pixels. ### Claim 2 (depends on 1) The system of claim 1, wherein at least the portion of the plurality of pixels comprises all the pixels in the LCD. ### Claim 3 (depends on 2) The system of claim 2, wherein the controller is further configured to instruct all the pixels in the LCD to simultaneously illuminate, after delaying illumination of each pixel based on the effective LC transition time. ### Claim 4 (depends on 1) The system of claim 1, wherein the controller is further configured to: determine the transition time for each pixel of each segment of the plurality of pixels, based on the current measured temperature, the transition information and the frame information; and compute the effective LC transition time for each segment of the plurality of pixels as a longest time period of the determined transition times for all pixels in that segment. ### Claim 5 (depends on 4) The system of claim 4, wherein the controller is further configured to instruct simultaneous illumination of all pixels in that segment, after delaying the illumination based on the effective LC transition time. ### Claim 6 (depends on 1) The system of claim 1, wherein the controller is further configured to: determine the transition time for each pixel of a controllable portion of the plurality of pixels, based on the current measured temperature, the transition information and the frame information; and compute the effective LC transition time for the controllable portion as a longest time period of the determined transition times for all pixels in the controllable portion. ### Claim 7 (depends on 6) The system of claim 6, wherein the controller is further configured to: control a size of the controllable portion of the plurality of pixels; and instruct simultaneous illumination of all the pixels in the controllable portion, after delaying the illumination based on the effective LC transition time. ### Claim 8 (depends on 1) The system of claim 1, wherein the controller is further configured to calibrate at least the portion of the plurality of pixels by delaying illumination of each pixel in at least the portion of the plurality of pixels until the effective LC transition time expires after data scanning of at least the portion of the plurality of pixels is finished. ### Claim 9 (depends on 1) The system of claim 1, wherein the frame information comprises information about at least two consecutive digital numbers associated with intensities of light emitted from each pixel in at least the portion of the plurality of pixels for the at least two consecutive frames. ### Claim 10 (depends on 1) The system of claim 1, wherein the system is integrated into a head-mounted display (HMD). ### Claim 11 A method comprising: obtaining and storing transition information about latencies for a pixel of a plurality of pixels of a liquid crystal display (LCD), each latency corresponds to a time period for transition from a defined start state to a defined end state for one temperature associated with the pixel, wherein the defined start state is related to an intensity of light emitted from the pixel in a first time instant and the defined end state is related to another intensity of light emitted from the pixel in a second time instant consecutive to the first time instant; measuring, by each temperature sensor of a plurality of temperature sensors coupled to at least a portion of the plurality of pixels, a current temperature associated with at least one pixel in at least the portion of the plurality of pixels; obtaining frame information related to at least two consecutive frames of video content to be displayed on at least the portion of the plurality of pixels; determining, based on the current measured temperature, based on the transition information and based on the frame information, a transition time for each pixel in at least the portion of the plurality of pixels to transition from a start state to an end state for the current measured temperature of that pixel, wherein the start state is related to a first intensity of light emitted from that pixel for a first frame of the at least two consecutive frames and the end state is related to a second intensity of light emitted from that pixel for a second frame of the at least two consecutive frames; computing an effective liquid crystal (LC) transition time for at least the portion of the plurality of pixels as a longest time period of the determined transition times for all pixels in at least the portion of the plurality of pixels; and calibrating at least the portion of the plurality of pixels based on the effective LC transition time when the video content is displayed on at least the portion of the plurality of pixels. ### Claim 12 (depends on 11) The method of claim 11, wherein at least the portion of the plurality of pixels comprises all the pixels in the LCD. ### Claim 13 (depends on 12) The method of claim 12, further comprising: instructing all the pixels in the LCD to simultaneously illuminate, after delaying illumination of each pixel based on the effective LC transition time. ### Claim 14 (depends on 11) The method of claim 11, further comprising: determining the transition time for each pixel of each segment of the plurality of pixels, based on the current measured temperature, the transition information and the frame information; and computing the effective LC transition time for each segment of the plurality of pixels as a longest time period of the determined transition times for all pixels in that segment. ### Claim 15 (depends on 14) The method of claim 14, further comprising: instructing simultaneous illumination of all pixels in that segment, after delaying the illumination based on the effective LC transition time. ### Claim 16 (depends on 11) The method of claim 11, further comprising: determining the transition time for each pixel of a controllable portion of the plurality of pixels, based on the current measured temperature, the transition information and the frame information; and computing the effective LC transition time for the controllable portion as a longest time period of the determined transition times for all pixels in the controllable portion. ### Claim 17 (depends on 16) The method of claim 16, further comprising: controlling a size of the controllable portion of the plurality of pixels; and instructing simultaneous illumination of all the pixels in the controllable portion, after delaying the illumination based on the effective LC transition time. ### Claim 18 (depends on 11) The method of claim 11, further comprising: calibrating at least the portion of the plurality of pixels by delaying illumination of each pixel in at least the portion of the plurality of pixels until the effective LC transition time expires after data scanning of at least the portion of the plurality of pixels is finished.