# US 9,520,089 B2 · Liquid crystal display device and method of driving the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,520,089 B2 - Document ID: US9520089B2 - Status: Granted - Kind: B2 - Application number: 14/080,653 - Filed: 2013-11-14 - Published: 2014-06-05 - Granted: 2016-12-13 - Earliest claimed: 2012-12-04 - Assignees: LG Display Co., Ltd. - Applicants: LG Display Co., Ltd. - Inventors: Min-Beom Kim; Jae-Sung Jeon - Web page: https://patentgrep.com/patent/US9520089B2 ## CPC - G09G 3/3406: {Control of illumination source (illumination devices structurally associated with liquid crystal cells G02F1/1336)} - G09G 3/3648: {using an active matrix (G09G3/367 - G09G3/3696 take precedence)} - 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 2360/16: Calculation or use of calculated indices related to luminance levels in display data - 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 Disclosed are a liquid crystal display device and a drive method thereof. The liquid crystal display device includes a liquid crystal panel having a plurality of pixel areas to display an image, a data driver configured to drive data lines of the liquid crystal panel, a dimming controller configured to generate a dimming value via modulation using any one value within the range from an average gray-level value to a maximum gray-level value of image data input from an external source, and output the image data via modulation and control drive time of a backlight unit based on the dimming value, a timing controller configured to allow transmission of the image data modulated by the dimming controller to the data driver, and to control the data driver, and the backlight unit configured to emit light to the liquid crystal panel in response to a drive signal from the dimming controller. ## Claims ### Claim 1 A liquid crystal display device comprising: a liquid crystal panel having a plurality of pixel areas to display an image; a data driver configured to drive data lines of the liquid crystal panel; a dimming controller configured to generate a dimming value via modulation using any one value within a range from an average gray-level value to a maximum gray-level value of image data input from an external source, and to modulate the image data into modulated image data based on the dimming value and control drive time of a backlight unit based on the dimming value; a timing controller configured to allow transmission of the image data modulated by the dimming controller to the data driver, and to control the data driver; and the backlight unit configured to emit light to the liquid crystal panel in response to a drive signal from the dimming controller, wherein the dimming controller includes: a data analyzer configured to detect the average gray-level value and the maximum gray-level value of image data input from the external source or the timing controller on a per at least one frame basis; a dimming value setter configured to output the dimming value via modulation on a per at least one frame bases using the average gray-level value, the maximum gray-level value, or any one value between the average gray-level value and the maximum gray-level value detected on a per at least one frame basis; a data modulator configured to generate the modulated data by modulating the image data from the external source or the timing controller using the dimming value from the dimming value setter, the data driver driving the data lines based on the modulated image data; and a Pulse Width Modulation (PWM) generator configured to generate the drive signal for conversion of a duty ratio based on the dimming value from the dimming value setter to thereby control drive time of the backlight unit. ### Claim 2 (depends on 1) The device according to claim 1, wherein the dimming value setter generates the dimming value by dividing a differential value between the average gray-level value and the maximum gray-level value by the maximum gray-level value, multiplying a predetermined coefficient, and adding the average gray-level value as represented by the following Equation 1: dim=[{(MAX−APL)/255}×hyb_coeff]+APL Equation 1 where hyb_coeff is a coefficient predetermined based on experimental values, or the dimming value setter generates the dimming value by dividing a differential value between the average gray-level value and the maximum gray-level value by the maximum gray-level value, extracting the square of the resulting value, multiplying a predetermined coefficient, and adding the average gray-level value as represented by the following Equation 2: dim=[{(MAX−APL)/255}2×hyb_coeff]+APL, Equation 2 wherein the dimming value setter adjusts the dimming value based on the above Equation 1 or Equation 2 by adjusting the maximum gray-level value using the following Equation 3: adj_MAX=MAX−[{(MAX−APL)/255}2×(255−APL)]×adj_coeff Equation 3 where adj_MAX replaces the maximum gray-level value of Equation 1 or Equation 2, and wherein the dimming value setter generates the dimming value by replacing the maximum gray-level value of Equation 2 with the maximum gray-level value adjusted based on the above Equation 3 as described by the following Equation 4: dim=[{(adj_MAX−APL)/255}2×hyb_coeff]+APL Equation 4. ### Claim 3 (depends on 2) The device according to claim 2, wherein the dimming value setter includes predetermined first and second threshold values as reference values to differently select and apply setting of the dimming value according to the range within which the detected average gray-level value is included, wherein, if the detected average gray-level value is included within the range from a minimum gray-level value to the predetermined first threshold value, the dimming value setter generates the dimming value using only the average gray-level value, wherein, if the detected average gray-level value is greater than the first threshold value and less than the predetermined second threshold value, the dimming value setter generates the dimming value using the following Equation 5: dim = Result ⁢ ⁢ of ⁢ ⁢ Eq . ⁢ 4 - APL up_apl - lw_apl * ( APL - lw_apl ) + APL , Equation ⁢ ⁢ 5 and wherein, if the detected average gray-level value is included within the range from the second threshold value to the maximum gray-level value, the dimming value setter generates the dimming value using the above Equation 4. ### Claim 4 (depends on 2) The device according to claim 2, wherein the dimming value setter includes predetermined third and fourth threshold values as reference values to differently select and apply setting of the dimming value according to the range within which the detected maximum gray-level value is included, wherein, if the detected maximum gray-level value is included within the range from the minimum gray-level value (zero gray-level) to the predetermined third threshold value, the dimming value setter generates the dimming value using only the average gray-level value, wherein, if the detected maximum gray-level value is greater than the third threshold value and less than the fourth threshold value, the dimming value setter generates the dimming value using the following Equation 6: dim = Results ⁢ ⁢ of ⁢ ⁢ Eq . ⁢ 4 ⁢ ⁢ or ⁢ ⁢ Eq . ⁢ 5 - APL up_max - lw_max * ( MAX - lw_max ) + APL , Equation ⁢ ⁢ 6 and wherein, if the detected maximum gray-level value is included within the range from the fourth threshold value to the maximum gray-level value, the dimming value setter generates the dimming value using the above Equation 4 or Equation 5. ### Claim 5 A method of driving a liquid crystal display device, the method comprising: driving gate and data lines of a liquid crystal panel; generating a dimming value via modulation using any one value within a range from an average gray-level value to a maximum gray-level value of image data input from an external source or a timing controller, and modulating the image data into modulated image data based on the dimming value and controlling drive time of a backlight unit based on the dimming value; allowing transmission of the modulated image data to a data driver, and controlling the data driver; and emitting light to the liquid crystal panel in response to a drive signal generated to control drive time of the backlight unit, wherein outputting the image data via modulation and controlling drive time of the backlight unit includes: detecting the average gray-level value and the maximum gray-level value of the image data on a per at least one frame basis; outputting the dimming value via modulation on a per at least one frame bases using the average gray-level value, the maximum gray-level value, or any one value between the average gray-level value and the maximum gray-level value detected on a per at least one frame bases; generating the modulated image data by modulating the image data using the output modulated dimming value; and generating the drive signal for conversion of a duty ratio based on the output modulated dimming value to thereby control drive time of the backlight unit. ### Claim 6 (depends on 5) The method according to claim 5, wherein, upon outputting the dimming value via modulation, the dimming value is generated by dividing a differential value between the average gray-level value and the maximum gray-level value by the maximum gray-level value, multiplying a predetermined coefficient, and adding the average gray-level value as represented by the following Equation 1: dim=[{(MAX−APL)/255}×hyb_coeff]+APL Equation 1 where hyb_coeff is a coefficient predetermined based on experimental values), or the dimming value is generated by dividing a differential value between the average gray-level value and the maximum gray-level value by the maximum gray-level value, extracting the square of the resulting value, multiplying a predetermined coefficient, and adding the average gray-level value as represented by the following Equation 2: dim=[{(MAX−APL)/255}2×hyb_coeff]+APL, Equation 2 wherein the dimming value based on the above Equation 1 or Equation 2 is adjusted by adjusting the maximum gray-level value using the following Equation 3: adj_MAX=MAX−[{(MAX−APL)/255}2×(255−APL)]×adj_coeff Equation 3 where adj_MAX replaces the maximum gray-level value of Equation 1 or Equation 2, and wherein the dimming value is generated by replacing the maximum gray-level value of Equation 2 with the maximum gray-level value adjusted based on the above Equation 3 as described by the following Equation 4: dim=[{(adj_MAX−APL)/255}2×hyb_coeff]+APL Equation 4. ### Claim 7 (depends on 6) The method according to claim 6, wherein, upon outputting the dimming value via modulation, based on predetermined first and second threshold values as reference values to differently select and apply setting of the dimming value according to the range within which the detected average gray-level value is included, if the detected average gray-level value is included within the range from a minimum gray-level value to the predetermined first threshold value, the dimming value is generated using only the average gray-level value, if the detected average gray-level value is greater than the first threshold value and less than the predetermined second threshold value, the dimming value is generated using the following Equation 5: dim = Result ⁢ ⁢ of ⁢ ⁢ Eq . ⁢ 4 - APL up_apl - lw_apl * ( APL - lw_apl ) + APL , Equation ⁢ ⁢ 5 and if the detected average gray-level value is included within the range from the second threshold value to the maximum gray-level value, the dimming value is generated using the above Equation 4. ### Claim 8 (depends on 6) The method according to claim 6, wherein, upon outputting the dimming value via modulation, based on predetermined third and fourth threshold values as reference values to differently select and apply setting of the dimming value according to the range within which the detected maximum gray-level value is included, if the detected maximum gray-level value is included within the range from the minimum gray-level value (zero gray-level) to the predetermined third threshold value, the dimming value is generated using only the average gray-level value, if the detected maximum gray-level value is greater than the third threshold value and less than the fourth threshold value, the dimming value is generated using the following Equation 6: dim = Results ⁢ ⁢ of ⁢ ⁢ Eq . ⁢ 4 ⁢ ⁢ or ⁢ ⁢ Eq . ⁢ 5 - APL up_max - lw_max * ( MAX - lw_max ) + APL , Equatio ⁢ ⁢ n ⁢ ⁢ 6 and if the detected maximum gray-level value is included within the range from the fourth threshold value to the maximum gray-level value, the dimming value is generated using the above Equation 4 or Equation 5.