# US 12,223,889 B2 · Drive circuit for display device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,223,889 B2 - Document ID: US12223889B2 - Status: Granted - Kind: B2 - Application number: 18/567,232 - Filed: 2022-05-16 - Published: 2024-08-15 - Granted: 2025-02-11 - Earliest claimed: 2021-07-28 - Assignees: Sony Semiconductor Solutions Corporation - Applicants: Sony Semiconductor Solutions Corporation - Inventors: Kouichi Hashikaki - Web page: https://patentgrep.com/patent/US12223889B2 ## CPC - G09G 3/32: semiconductive, e.g. using light-emitting diodes [LED] - G09G 3/20: for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix {no fixed position being assigned to or needed to be assigned to the individual characters or partial characters} - G09G 3/34: by control of light from an independent source - G09G 3/3426: {the different display panel areas being distributed in two dimensions, e.g. matrix} - H04N 5/66: Transforming electric information into light information (scanning details H04N3/00) - H05B 45/10: Controlling the intensity of the light - H05B 45/325: Pulse-width modulation [PWM] - G09G 2300/0857: Static memory circuit, e.g. flip-flop - G09G 2310/0286: Details of a shift registers arranged for use in a driving circuit - G09G 2320/064: by time modulation of the brightness of the illumination source - G09G 2330/021: Power management, e.g. power saving - 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 - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL ## Abstract To reduce power consumption of a drive circuit for a display device. A drive circuit (10) for the display device includes a comparator (100), a PWM signal generation unit (200), and a drive unit (300). The comparator (100) is a comparator that starts comparison between a count number of pulses in an input clock signal and input comparison data in synchronization with a start signal, and includes a shift register (120) that is configured by a plurality of flip-flops in which the clock signal is input to a clock terminal and that is cascade-connected and shifts the start signal, and a selection unit (130) that selects one of outputs of the plurality of flip-flops constituting the shift register according to the comparison data and outputs the shifted start signal as a result of the comparison. The PWM signal generation unit (200) generates a PWM signal according to the result of the comparison. The drive unit (300) drives a light emitting element (11) based on the generated PWM signal. ## Claims ### Claim 1 A drive circuit for a display device, comprising: a comparator that starts comparison between a count number of pulses in a clock signal input and comparison data input in synchronization with a start signal, the comparator including: a shift register that is configured by a plurality of flip-flops in which the clock signal is input to a clock terminal and that is connected in cascade and shifts the start signal; and a selection unit that selects one of outputs of the plurality of flip-flops constituting the shift register according to the comparison data and outputs the start signal shifted as a result of the comparison; a PWM signal generation unit that generates a PWM signal according to the result of the comparison; and a drive unit that drives a light emitting element based on the PWM signal generated. ### Claim 2 (depends on 1) The drive circuit for the display device according to claim 1, wherein the clock signal is commonly input to the plurality of flip-flops cascade-connected in the shift register. ### Claim 3 (depends on 1) The drive circuit for the display device according to claim 1, wherein respective clock signals having different phases are input to respective flip-flops that are adjacent in cascade connection in the shift register. ### Claim 4 (depends on 1) The drive circuit for the display device according to claim 1, further comprising a clock signal supply unit that supplies the clock signal to the shift register during a period from an input of the start signal to an end of a shift of the start signal. ### Claim 5 A drive circuit for a display device, comprising: a comparator that starts comparison between a count number of pulses in a clock signal input and comparison data input in synchronization with a start signal, the comparator including: a shift register that is configured by a plurality of flip-flops in which the clock signal is input to a clock terminal and that is connected in cascade and shifts the start signal; and a selection circuit that selects one of outputs of the plurality of flip-flops constituting the shift register according to the comparison data and outputs the start signal shifted as a result of the comparison; PWM signal generation circuitry configured to generate a PWM signal according to the result of the comparison; and drive circuitry configured to drive a light emitting element based on the PWM signal generated. ### Claim 6 (depends on 5) The drive circuit for the display device according to claim 5, wherein the clock signal is commonly input to the plurality of flip-flops cascade-connected in the shift register. ### Claim 7 (depends on 5) The drive circuit for the display device according to claim 5, wherein respective clock signals having different phases are input to respective flip-flops that are adjacent in cascade connection in the shift register. ### Claim 8 (depends on 5) The drive circuit for the display device according to claim 5, further comprising clock signal supply circuitry configured to supply the clock signal to the shift register during a period from an input of the start signal to an end of a shift of the start signal.