# US 2023/0057575 A1 · Display driver having output correction function > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2023/0057575 A1 - Document ID: US20230057575A1 - Status: Published application - Kind: A1 - Application number: 17/820,841 - Filed: 2022-08-18 - Published: 2023-02-23 - Earliest claimed: 2021-08-19 - Assignees: Lx Semicon Co., Ltd. - Applicants: LX Semicon Co., Ltd. - Inventors: Byeong Yong KIM; Chang Bae LEE - Web page: https://patentgrep.com/patent/US20230057575A1 ## CPC - G09G 3/006: {Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays (testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309)} - 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 2330/08: Fault-tolerant or redundant circuits, or circuits in which repair of defects is prepared - G09G 2330/12: Test circuits or failure detection circuits included in a display system, as permanent part thereof - 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 Various embodiments disclose a display driver, wherein the display driver may be configured to detect a defective output buffer among output buffers and perform an output correction function for the defective output buffer. ## Claims ### Claim 1 A display driver comprising: an output buffer configured to output a source signal corresponding to an input signal; a dummy buffer configured to output a dummy source signal corresponding to the input signal; a detection circuit configured to provide a control signal by detecting a state of the source signal; and a switching circuit configured to select one of the source signal and the dummy source signal according to the control signal and output a selected signal as an output signal. ### Claim 2 (depends on 1) The display driver according to claim 1, wherein the output buffer receives the input signal having a level transition in a first frame in which an output of the source signal is activated, and wherein the detection circuit provides the control signal for selecting the source signal when a level transition is in the source signal, and provides the control signal for selecting the dummy source signal when the level transition is not in the source signal. ### Claim 3 (depends on 1) The display driver according to claim 1, wherein the detection circuit includes: a comparator configured to receive the source signal corresponding to the input signal having a level transition during a preset test frame period and output a comparison signal obtained by comparing the source signal with a preset reference voltage; a failure determination unit configured to provide an activated determination signal at a level transition time point of the comparison signal, and provide a deactivated determination signal when a level transition is not in the comparison signal; and a control circuit configured to output the control signal for selecting the source signal in response to the activated determination signal and output the control signal for selecting the dummy source signal in response to the deactivated determination signal. ### Claim 4 (depends on 3) The display driver according to claim 3, wherein the control circuit is configured to: output the control signal for selecting the source signal in response to a check signal that remains enabled during the test frame period; and when the check signal is disabled due to expiration of the test frame period, output the control signal for selecting the source signal in response to the activated determination signal, or output the control signal for selecting the dummy source signal in response to the deactivated determination signal. ### Claim 5 (depends on 3) The display driver according to claim 3, further comprising: a check switch that is turned on by a check signal that remains enabled during the test frame period and transmits the source signal to the comparator. ### Claim 6 (depends on 1) The display driver according to claim 1, wherein the switching circuit includes: a first switch configured to switch to output the source signal as the output signal according to a first switching signal included in the control signal; and a second switch configured to switch to output the dummy source signal as the output signal according to a second switching signal included in the control signal, and wherein the detection circuit provides the first switching signal for turning on the first switch and the second switching signal for turning off the second switch when the source signal has a level transition corresponding to the input signal during a preset test frame period, and provides the first switching signal for turning off the first switch and the second switching signal for turning on the second switch when the level transition is not in the source signal during the preset test frame period. ### Claim 7 A display driver comprising: a first output buffer configured to output a first source signal corresponding to a first input signal; a second output buffer configured to output a second source signal corresponding to a second input signal; a first detection circuit configured to provide a first control signal by detecting a state of the first source signal; and a first switching circuit configured to select one of the first and second source signals according to the first control signal and output a selected signal as a first output signal corresponding to the first output buffer. ### Claim 8 (depends on 7) The display driver according to claim 7, further comprising: a second detection circuit configured to provide a second control signal by detecting a state of the second source signal; and a second switching circuit configured to select one of the first and second source signals according to the second control signal and output a selected signal as a second output signal corresponding to the second output buffer. ### Claim 9 (depends on 7) The display driver according to claim 7, wherein, through a first frame in which an output of the first source signal is activated, the first output buffer receives the first input signal having a level transition, and wherein the first detection circuit provides the first control signal for selecting the first source signal or the second source signal as the first output signal according to whether the first source signal has a level transition. ### Claim 10 (depends on 7) The display driver according to claim 7, wherein the first detection circuit includes: a comparator configured to receive the first source signal corresponding to the first input signal having a level transition during a preset test frame period and output a comparison signal obtained by comparing the first source signal with a preset reference voltage; a failure determination unit configured to provide an activated determination signal when a level transition is present in the comparison signal, and provide a deactivated determination signal when the level transition is not in the comparison signal; and a control circuit configured to output the first control signal for selecting the first source signal in response to the activated determination signal and output the first control signal for selecting the second source signal in response to the deactivated determination signal. ### Claim 11 (depends on 10) The display driver according to claim 10, wherein the control circuit is configured to: output the first control signal for selecting the first source signal in response to a check signal enabled during the test frame period; and when the check signal is disabled, output the first control signal for selecting the first source signal in response to the activated determination signal, or output the first control signal for selecting the second source signal in response to the deactivated determination signal. ### Claim 12 (depends on 10) The display driver according to claim 10, further comprising: a check switch that is turned on by a check signal enabled during the test frame period and transmits the first source signal to the comparator. ### Claim 13 (depends on 7) The display driver according to claim 7, wherein the first switching circuit includes: a first switch configured to switch to output the first source signal as the first output signal according to a first switching signal included in the first control signal; and a second switch configured to switch to output the second source signal as the first output signal according to a second switching signal included in the first control signal, and wherein the first detection circuit provides the first switching signal for turning on the first switch and the second switching signal for turning off the second switch when the first source signal has a level transition corresponding to the first input signal during a preset test frame period, and provides the first switching signal for turning off the first switch and the second switching signal for turning on the second switch when the level transition is not in the first source signal during the preset test frame period. ### Claim 14 A display driver comprising: first output buffers of a first group; a number of second output buffers of a second group equal to a number of the first output buffers of the first group; a first detection circuit configured to provide a first control signal by detecting states of first source signals of the first output buffers; and a first switching circuit configured to select one group of the first group and the second group according to the first control signal and output source signals of the selected group as first output signals corresponding to the first output buffers. ### Claim 15 (depends on 14) The display driver according to claim 14, further comprising: a second detection circuit configured to provide a second control signal by detecting states of second source signals of the second output buffers; and a second switching circuit configured to select one group of the first group and the second group according to the second control signal and output source signals of the selected group as second output signals corresponding to the second output buffers. ### Claim 16 (depends on 14) The display driver according to claim 14, wherein, during a first frame in which an output of the first source signals of the first output buffers is activated, a pair of adjacent first output buffers receive a first input signal and a second input signal having a level transition of a complementary phase, and wherein the first detection circuit compares the first source signals of the pair of adjacent first output buffers of the first group, and provides the first control signal for selecting the first source signals of the first group or second source signals of the second output buffers of the second group as the first output signals corresponding to a case in which a level transition is present in all of the first source signals of the first group, or not in at least one of the first source signals. ### Claim 17 (depends on 14) The display driver according to claim 14, wherein the first detection circuit includes: comparators configured to output comparison signals obtained by comparing first source signals of a pair of adjacent first output buffers receiving a first input signal and a second input signal having a level transition of a complementary phase during a preset test frame period, respectively; failure determination units configured to correspond to the comparators, wherein each failure determination unit provides an activated determination signal when a level transition is present in the comparison signal, and provides a deactivated determination signal when the level transition is not in the comparison signal; and a control circuit configured to output the first control signal for selecting the first source signal when all of the determination signals of the failure determination units are in an active state, and output the first control signal for selecting a second source signal of the second output buffers when at least one of the determination signals of the failure determination units is in an inactive state. ### Claim 18 (depends on 17) The display driver according to claim 17, wherein the control circuit is configured to: output the first control signal for selecting the first source signal in response to a check signal enabled during the test frame period; and when the check signal is disabled, output the first control signal for selecting the first source signal in response to all of the activated determination signals, or output the first control signal for selecting the second source signal in response to at least one of the deactivated determination signals. ### Claim 19 (depends on 17) The display driver according to claim 17, further comprising: check switches that are turned on by a check signal enabled during the test frame period and transmit the first source signals to the comparators. ### Claim 20 (depends on 15) The display driver according to claim 15, wherein the first switching circuit includes: first switches configured to switch to output the first source signals of the first output buffers as the first output signals according to a first switching signal included in the first control signal; and second switches configured to switch to output the second source signals of the second output buffers as the first output signals according to a second switching signal included in the first control signal, and wherein the first detection circuit provides the first switching signal for turning on the first switches and the second switching signal for turning off the second switches when a level transition corresponding to input signals is present in all the first source signals during a preset test frame period, and provides the first switching signal for turning off the first switches and the second switching signal for turning on the second switches when the level transition is not in at least one of the first source signals during the preset test frame period.