# US 5,706,023 A · Method of driving an image display device by driving display materials with alternating current > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,706,023 A - Document ID: US5706023A - Status: Granted - Kind: A - Application number: 08/487,704 - Filed: 1995-06-07 - Granted: 1998-01-06 - Earliest claimed: 1988-03-11 - Assignees: Matsushita Electric Industrial Co., Ltd. - Inventors: Seiichi Nagata; Etsuya Takeda; Tetsuya Kawamura; Yutaka Nanno - Web page: https://patentgrep.com/patent/US5706023A ## CPC - G09G 3/3655: {Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors} - G09G 3/3648: {using an active matrix (G09G3/367 - G09G3/3696 take precedence)} - G09G 3/3659: {the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes} - H04N 3/127: {using liquid crystals} - G09G 2300/0876: Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes - G09G 2320/0204: Compensation of DC component across the pixels in flat panels - G09G 2320/0219: Reducing feedthrough effects in active matrix panels, i.e. voltage changes on the scan electrode influencing the pixel voltage due to capacitive coupling - G09G 2320/0247: Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes - 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) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A method of driving a display device having a matrix of display material elements includes transmitting a picture signal voltage to each picture element electrode during an ON period of a respective switching element, applying a first modulation signal to a first wire during an OFF period of the switching elements associated with the first wire, and applying a second modulation signal to counter electrodes associated with the first wire during the OFF period of the switching elements associated with the first wire. Each picture element electrode of a plurality of the display material elements is connected to the first wire through a respective capacitance. ## Claims ### Claim 1 A method of driving a display device, the display device comprising plural picture-element electrodes disposed in a matrix form so as to define plural rows and columns, plural thin film transistors having drain, source and gate electrodes connected to said picture-element electrodes, video signal wires and scanning signal wires, respectively, said video signal wires respectively connected to said columns of picture element electrodes through said plural thin film transistors and said scanning signal wires respectively connected to said rows of picture element electrodes through said plural thin film transistors, first plural wires which are electrically separated from each other and respectively commonly coupled with said picture-element electrodes of each row through a capacitance and running in parallel with said scanning signal wires, and plural counter electrodes which are electrically separated from each other and respectively commonly coupled through a display material with said picture-element electrodes of each row and running in parallel with said scanning signal wires, said display material being AC-driven, said method comprising: applying a scanning voltage to said scanning signal wires in succession to turn ON said thin-film transistors connected to each row of said picture element electrodes while said scanning voltage is applied to a corresponding scanning signal wire; applying a video signal voltage to said video signal wires for each row of said picture-element electrodes during a respective ON-period of each corresponding row of said thin film transistors; applying a respective first modulation signal to said respective first plural wires of each row in positive and negative directions alternately for every field period during an OFF-period of each corresponding row of said thin film transistors and at a certain time after completion of said ON-period of each corresponding row of said thin film transistors; and at the same time applying a respective second modulation signal to said counter electrodes of each row which alternates in positive and negative directions in synchronism with said first modulation signal applied to a corresponding first wire to modulate potentials of said picture-element electrodes and to thereby apply a voltage to said display material. ### Claim 2 (depends on 1) A method as recited in claim 1, wherein said first plural wires are neighboring scanning signal wires. ### Claim 3 (depends on 2) A method as recited in claim 2, wherein an amplitude of said first modulation signal applied to said first plural wires differs between the positive and negative directions. ### Claim 4 (depends on 3) A method as recited in claim 3, wherein a positive amplitude of said first modulation signal applied to said first plural wires is larger than a negative amplitude for a N-channel thin film transistor and a positive amplitude of said first modulation signal applied to said first plural wires is smaller than a negative amplitude for a P-channel thin film transistor. ### Claim 5 (depends on 3) A method as recited in claim 3, wherein a potential of said first modulation signal is partly changed before said ON-period of said thin film transistor is terminated. ### Claim 6 (depends on 4) A method as recited in claim 4, wherein a potential of said first modulation signal is partly changed before said ON-period of said thin film transistor is terminated. ### Claim 7 (depends on 1) A method as recited in claim 1, wherein an amplitude of said first modulation signal applied to said first plural wires differs between the positive and negative directions. ### Claim 8 (depends on 7) A method as recited in claim 7, wherein a positive amplitude of said first modulation signal applied to said first plural wires is larger than a negative amplitude for a N-channel thin film transistor and a positive amplitude of said first modulation signal applied to said first plural wires is smaller than a negative amplitude for a P-channel thin film transistor. ### Claim 9 (depends on 8) A method as recited in claim 8, wherein a potential of said first modulation signal is partly changed before said ON-period of said thin film transistor is terminated. ### Claim 10 (depends on 7) A method as recited in claim 7, wherein a potential of said first modulation signal is partly changed before said ON-period of said thin film transistor is terminated. ### Claim 11 (depends on 1) A method as recited in claim 1, wherein amplitudes of said first and said second modulation signals are the same. ### Claim 12 A method of driving a display device, the display device comprising plural picture-element electrodes disposed in a matrix form so as to define plural rows and columns, plural thin film transistors having drain, source and gate electrodes each connected to said picture-element electrodes, video signal wires and scanning signal wires, respectively, said video signal wires respectively connected to said columns of picture element electrodes through said plural thin film transistors and said scanning signal wires respectively connected to said rows of picture element electrodes through said plural thin film transistors, plural first wires which are commonly coupled with said picture-element electrodes of each row through a capacitance and running in parallel with said scanning signal wires, and counter electrodes disposed at a position counter to said picture-element electrodes across a display material, said display material being AC-driven, said method comprising: applying a scanning voltage to said scanning signal wires in succession to turn ON said thin-film transistors connected to each row of said picture element electrodes while said scanning voltage is applied to a corresponding scanning signal wire; applying a video signal voltage to said video signal wires for each column of said picture-element electrodes during a respective ON-period of each corresponding row of said thin film transistors; applying a first modulation signal having a polarity which is reversed every fixed period to said plural first wires at the same time; applying a second modulation signal having a polarity which is reversed every fixed period to said counter electrodes in synchronism with said first modulation signal to modulate potentials of said picture-element electrodes and to thereby apply an AC voltage to said display material. ### Claim 13 (depends on 12) A method as recited in claim 12, wherein amplitudes of said first and said second modulation signals are the same. ### Claim 14 (depends on 12) A method as recited in claim 12, wherein polarities of said first and said second modulation signals are the same. ### Claim 15 (depends on 14) A method as recited in claim 14, wherein said fixed period is the same as one horizontal scanning period. ### Claim 16 (depends on 12) A method as recited in claim 12, wherein polarities of said first and said second modulation signals are inverted at every said fixed period. ### Claim 17 (depends on 12) A method as recited in claim 12, wherein said fixed period is the same as one horizontal scanning period. ### Claim 18 (depends on 12) A method as recited in claim 12, wherein an amplitude of said first modulation signal is larger in a positive direction than in a negative direction for a certain period after said applictaion of said scanning voltages as compared with the remainder of the period for N-channel thin film transistors, and an amplitude of said first modulation signal is smaller in a positive direction than in a negative direction for a certain period after said application of scanning voltages as compared with the remainder of the period for P-channel thin film transistors. ### Claim 19 (depends on 12) A method as recited in claim 12, wherein a potential of said first modulation signal applied in duplication to said scanning signal wire is lower than a gate voltage at which said thin film transistors are turned off. ### Claim 20 (depends on 12) A method as recited in claim 12, wherein a potential of said first modulation signal is varied during said ON-period and varied again during an OFF-period of said thin film transistor. ### Claim 21 A method of driving a display device, the display device comprising plural picture-element electrodes disposed in a matrix form so as to define plural rows and columns, plural thin film transistors having drain, source and gate electrodes each connected to said picture-element electrodes, video signal wires and scanning signal wires, respectively, said video signal wires respectively connected to said columns of picture element electrodes through said plural thin film transistors and said scanning signal wires respectively connected to said rows of picture element electrodes through said plural thin film transistors, said picture-element electrodes of a first row coupled through a capacitance with a first wire, said picture-element electrodes after said first row coupled through a capacitance with a scanning signal wire of a previous row of picture elements, and a counter electrode disposed at a position counter to said picture-element electrodes across a display material, said display material being AC-driven, said method comprising: applying a scanning voltage to said scanning signal wires in succession to turn ON said thin-film transistors connected to each row of said picture element electrodes while said scanning voltage is applied to a corresponding scanning signal wire; transmitting video signal voltages to said video signal wires for each column of said picture-element electrodes during a respective ON-period of each corresponding row of said thin film transistors; applying a second modulation signal having a polarity which is reversed every fixed period to said counter electrodes; applying a first modulation signal to said first wires and in duplication to said scanning signal wires during an OFF-period of said thin film transistors to modulate a potential of said picture-element electrode and to thereby apply a voltage to said display material. ### Claim 22 (depends on 21) A method as recited in claim 21, wherein amplitudes of said first and said second modulation signals are the same. ### Claim 23 (depends on 21) A method as recited in claim 21, wherein polarities of said first and said second modulation signals are the same. ### Claim 24 (depends on 21) A method as recited in claim 21, wherein polarities of said first and said second modulation signals are inverted every fixed period. ### Claim 25 (depends on 24) A method as recited in claim 24, wherein said fixed period is the same as one horizontal scnning period. ### Claim 26 (depends on 21) A method as recited in claim 21, wherein said fixed period is the same as one horizontal scanning period. ### Claim 27 (depends on 21) A method as recited in claim 21, wherein the amplitude of said first modulation signal is larger in a positive direction than in a negative direction for a certain period after said application of said scanning voltages as compared with the remainder of the period for N-channel thin film transistors, and an amplitude of said first modulation signal is smaller in a positive direction than in a negative direction for a certain period after said application of scanning voltages as compared with the remainder of the period for P-channel thin film transistors. ### Claim 28 (depends on 21) A method as recited in claim 21, wherein the potential of said first modulation signal is lower than a gate voltage at which said thin film transistors are turned off. ### Claim 29 (depends on 21) A method as recited in claim 21, wherein a potential of said first modulation signal is varied during said ON-period and varied again during said OFF-period of said thin film transistor. ### Claim 30 A method of driving a display device, the display device including (a) a plurality of liquid crystal picture elements disposed in a matrix form so as to define plural rows and columns, each picture element having a picture element electrode and a counter common electrode, (b) a plurality of thin film transistors having drain, source and gate electrodes each connected to said picture element electrode, a video signal wire and a scanning signal wire respectively, said each video signal wire being connected to said picture element electrodes of each column through said thin film transistors, said each scanning signal wire being connected to said picture element electrodes of each row through said thin film transistors, (c) a plurality of capacitors respectively associated with each said picture element, one electrode of each said capacitor being coupled to said each picture element electrode of said associated picture element, the other electrodes of said capacitors of each row being commonly connected to said scanning signal wires of a previous row, said display device being AC-driven, said method comprising: applying a scanning voltage to said scanning signal wire to turn ON said thin film transistors connected to said picture element electrodes of each row; transmitting video signal voltages applied to said video signal wires of each column to said picture element electrodes of each row during a respective ON-period of each corresponding row of said thin film transistors; applying a first modulation signal to said scanning signal wires of a previous row in duplication, applying a second modulation signal having a polarity which is reversed every fixed period to said counter common electrodes of said picture elements to modulate a voltage applied to said picture elements. ### Claim 31 (depends on 30) A method as recited in claim 30, wherein said first modulation signal is applied to said scanning signal wires during an OFF-period of said thin film transistor. ### Claim 32 (depends on 30) A method as recited in claim 30, wherein a potential of said first modulation signal is varied during said ON-period and varied again during said OFF-period of said thin film transistor. ### Claim 33 A method of driving a display device, the display device including (a) a plurality of liquid crystal picture elements disposed in a matrix form so as to define plural rows and columns, each picture element having a picture element electrode and a counter common electrode, (b) a plurality of thin film transistors having drain, source and gate electrodes each connected to said picture element electrode, a video signal wire and a scanning signal wire respectively, said each video signal wire being connected to said picture element electrodes of each column through said thin film transistors, said each scanning signal wire being connected to said picture element electrodes of each row through said thin film transistors, (c) a plurality of capacitors respectively associated with each said picture element, one electrode of each said capacitor being coupled to said each picture element electrode of said associated picture element, the other electrodes of said capacitors of the first row being commonly connected to a first signal wire, the other electrodes of said capacitors after the first row being commonly connected with said scanning signal wires of a previous row, said display device being AC-driven, said method comprising: applying a scanning voltage to said scanning signal wire to turn ON the thin film transistors connected to said picture element electrodes of each row; transmitting video signal voltages applied to said video signal wires of each column to said picture element electrodes of each row during a respective ON-period of each corresponding row of said thin film transistors; applying a first modulation signal to said first signal wire and said scanning signal wires of a previous row in duplication, and applying a second modulation signal having a polarity which is reversed every fixed period to said counter common electrodes of said picture elements to modulate a voltage applied to said picture elements. ### Claim 34 (depends on 33) A method as recited in claim 33, wherein the potential of said first modulation signal is varied during said ON-period and varied again during an OFF-period of said thin film transistor.