# US 12,118,959 B2 · Gamma voltage generating circuit, source driver and display device including the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,118,959 B2 - Document ID: US12118959B2 - Status: Granted - Kind: B2 - Application number: 18/136,299 - Filed: 2023-04-18 - Published: 2023-08-10 - Granted: 2024-10-15 - Earliest claimed: 2019-03-07 - Assignees: Samsung Display Co., Ltd. - Applicants: Samsung Display Co., Ltd. - Inventors: Su Bin Kim; Se Byung Chae - Web page: https://patentgrep.com/patent/US12118959B2 ## CPC - G09G 5/10: Intensity circuits - G09G 5/18: Timing circuits for raster scan displays (specially adapted for television H04N {; synchronisation between the display unit and other display units, videodisc player G09G5/12}) - G06F 1/3265: {Power saving in display device} - G09G 3/2007: {Display of intermediate tones} - G09G 3/3208: organic, e.g. using organic light-emitting diodes [OLED] - G09G 3/3275: Details of drivers for data electrodes - G09G 3/3696: {Generation of voltages supplied to electrode drivers} - G09G 2310/0267: Details of drivers for scan electrodes, other than drivers for liquid crystal, plasma or OLED displays - G09G 2310/027: Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters - G09G 2310/0291: Details of output amplifiers or buffers arranged for use in a driving circuit - G09G 2310/061: for resetting or blanking - G09G 2310/08: Details of timing specific for flat panels, other than clock recovery - G09G 2320/0276: for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction - G09G 2320/0673: for control of gamma adjustment, e.g. selecting another gamma curve - G09G 2330/021: Power management, e.g. power saving - G09G 2330/022: in absence of operation, e.g. no data being entered during a predetermined time - G09G 2330/028: Generation of voltages supplied to electrode drivers in a matrix display other than LCD - 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) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract A display device including a display panel including a scan line, a data line, and a pixel connected thereto, a gate driver, and a source driver including a gamma voltage generator to generate gamma voltages having different voltage levels, a digital-to-analog converter to generate the data voltage corresponding to a gray scale value using the gamma voltages, and a source buffer, in which the gamma voltage generator includes a first resistor string to set a voltage range of the gamma voltages, a second resistor string to set tab gamma voltages corresponding to some of the gamma voltages within the voltage range, gamma buffers to output the tab gamma voltages, and a third resistor string including tabs respectively connected to output terminals of the gamma buffers, the third resistor string being configured to divide a voltage between the tabs to generate the gamma voltages. ## Claims ### Claim 1 A display device comprising: a display panel including a scan line, a data line, and a pixel connected to the scan line and the data line; a gate driver configured to supply a scan signal to the scan line; and a source driver configured to supply a data voltage to the data line, wherein the source driver includes: a gamma voltage generator configured to generate gamma voltages having voltage levels different from each other in response to a gamma enable signal; a digital-to-analog converter configured to generate the data voltage corresponding to a gray scale value using the gamma voltages; and a source buffer configured to output the data voltage to the data line, wherein the gamma voltage generator includes: a first resistor string configured to set a voltage range of the gamma voltages; a second resistor string configured to set tab gamma voltages corresponding to some of the gamma voltages within the voltage range; gamma buffers configured to output the tab gamma voltages; and a third resistor string including tabs respectively connected to output terminals of the gamma buffers, the third resistor string being configured to divide a voltage between the tabs to generate the gamma voltages, wherein the gamma voltage generator, in response to the gamma enable signal, outputs the tab gamma voltages during a part of a horizontal time and stops outputting some of the tab gamma voltages during a rest of the horizontal time, and wherein the scan signal has a turn-off voltage level in the part of the horizontal time. ### Claim 2 (depends on 1) The display device according to claim 1, wherein the horizontal time is a cycle of a horizontal synchronization signal, and wherein the source driver supplies the data voltage to the data line at intervals of the one horizontal time. ### Claim 3 (depends on 1) The display device according to claim 1, wherein at least some of the tab gamma voltages correspond to inflection points of the gamma voltages having nonlinear characteristics. ### Claim 4 (depends on 1) The display device according to claim 1, wherein the first resistor string divides a voltage between a first reference voltage and a second reference voltage, and wherein one of divided voltages by the first resistor string is used as a maximum voltage of the voltage range of the gamma voltages, and another of the divided voltages by the first resistor string is used as a minimum voltage of the voltage range of the gamma voltages. ### Claim 5 (depends on 1) The display device according to claim 1, wherein, in response to the gamma enable signal, the gamma buffers are turned on during the part of the horizontal time and some of the gamma buffers are turned off during the rest of the horizontal time. ### Claim 6 (depends on 5) The display device according to claim 5, wherein the scan signal has a turn-on voltage level in the rest of the horizontal time. ### Claim 7 (depends on 6) The display device according to claim 6, wherein the some of the gamma buffers are turned off at a point of time when the scan signal is shifted from the turn-off voltage level to the turn-on voltage level. ### Claim 8 (depends on 6) The display device according to claim 6, wherein at least some of the gamma buffers are turned off after a point of time when the scan signal is shifted from the turn-off voltage level to the turn-on voltage level. ### Claim 9 (depends on 5) The display device according to claim 5, wherein a first gamma buffer of the gamma buffers connected to an uppermost tab of the third resistor string maintains a turn-on state in the horizontal time, and wherein a second gamma buffer of the gamma buffers connected to a lowermost tab of the third resistor string maintains the turn-on state in the horizontal time. ### Claim 10 (depends on 9) The display device according to claim 9, wherein the gamma buffers, except for the first and second gamma buffers, are turned off in the rest of the horizontal time. ### Claim 11 (depends on 9) The display device according to claim 9, wherein a third gamma buffer of the gamma buffers that is farthest from the first and second gamma buffers maintains the turn-on state in the second period. ### Claim 12 (depends on 9) The display device according to claim 9, wherein a first group of the gamma buffers further includes a fourth gamma buffer of the gamma buffers that is adjacent to the first gamma buffer or the second gamma buffer. ### Claim 13 (depends on 1) The display device of claim 1, wherein a frame period includes a display period in which an image is displayed and a porch period between the display period and another display period, wherein the source buffer is turned off in the porch period and is turned on in the display period, and wherein at least some of the gamma buffers are turned off in the porch period and are turned on in the display period. ### Claim 14 A display device comprising: a display panel including a scan line, a data line, and a pixel connected to the scan line and the data line; a gate driver configured to supply a scan signal to the scan line; and a source driver configured to supply a data voltage to the data line, wherein the source driver includes: a gamma voltage generator configured to generate gamma voltages having voltage levels different from each other in response to a gamma enable signal; a digital-to-analog converter configured to generate the data voltage corresponding to a gray scale value using the gamma voltages; and a source buffer configured to output the data voltage to the data line, wherein the gamma voltage generator includes: a first resistor string configured to set a voltage range of the gamma voltages; a second resistor string configured to set tab gamma voltages corresponding to some of the gamma voltages within the voltage range; gamma buffers configured to output the tab gamma voltages; and a third resistor string including tabs respectively connected to output terminals of the gamma buffers, the third resistor string being configured to divide a voltage between the tabs to generate the gamma voltages, wherein a frame period includes a display period in which an image is displayed and a porch period between the display period and another display period, wherein the source buffer is turned off in the porch period and is turned on in the display period, and wherein at least some of the gamma buffers are turned off during a part of the porch period and are turned on during a rest of the porch period. ### Claim 15 (depends on 13) The display device according to claim 13, wherein the display period includes a black period in which a black image is displayed and a valid period different from the black period, wherein the source buffer is turned off in the black period and is turned on in the valid period, and wherein the at least some of the gamma buffers are turned off in the black period and are turned on in the valid period. ### Claim 16 (depends on 15) The display device according to claim 15, wherein a first gamma buffer connected to an uppermost tab of the third resistor string maintains a turn-on state in the black period, and wherein the remaining gamma buffers except for the first gamma buffer are turned off in the black period. ### Claim 17 (depends on 15) The display device according to claim 15, wherein the at least some of the gamma buffers are turned off during a part of the black period and are turned on during a rest of the black period. ### Claim 18 A source driver comprising: a gamma voltage generator configured to generate gamma voltages having voltage levels different from each other in response to a gamma enable signal; a digital-to-analog converter configured to generate a data voltage corresponding to a grayscale value using the gamma voltages; and a source buffer configured to output the data voltage to a data line, wherein the gamma voltage generator includes: a first resistor string configured to divide a voltage between a first reference voltage and a second reference voltage; a second resistor string configured to divide a voltage between two selected voltages among voltages divided by the first resistor string; gamma buffers configured to output some of voltages divided by the second resistor string as tab gamma voltages; and a third resistor string including tabs respectively connected to output terminals of the gamma buffers, the third resistor string being configured to divide a voltage between the tabs to generate the gamma voltages, and wherein the gamma voltage generator, in response to the gamma enable signal, turns on the gamma buffers during a part of a horizontal time and turns off some of the gamma buffers during a rest of the horizontal time, and wherein the data voltage is not provided to a pixel in the part of the horizontal time. ### Claim 19 (depends on 18) The source driver according to claim 18, wherein the horizontal time is a cycle of a horizontal synchronization signal, and wherein the source driver outputs the data voltage at intervals of the one horizontal time. ### Claim 20 (depends on 18) The source driver according to claim 18, wherein at least some of the tab gamma voltages correspond to inflection points of the gamma voltages having nonlinear characteristics.