# US 2013/0278581 A1 · Devices and methods for pixel discharge before display turn-off > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0278581 A1 - Document ID: US20130278581A1 - Status: Published application - Kind: A1 - Application number: 13/451,389 - Filed: 2012-04-19 - Published: 2013-10-24 - Earliest claimed: 2012-04-19 - Assignees: Apple Inc. - Inventors: Ahmad Al-Dahle; Brian J. Conner; Hopil Bae; Yafei Bi - Web page: https://patentgrep.com/patent/US20130278581A1 ## CPC - G09G 3/3648: {using an active matrix (G09G3/367 - G09G3/3696 take precedence)} - G09G 2310/0251: Precharge or discharge of pixel before applying new pixel voltage - G09G 2310/061: for resetting or blanking - G09G 2310/063: Waveforms for resetting the whole screen at once - G09G 2320/0204: Compensation of DC component across the pixels in flat panels - G09G 2320/0247: Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes - G09G 2320/0257: Reduction of after-image effects - G09G 2320/046: Dealing with screen burn-in prevention or compensation of the effects thereof - G09G 2330/027: Arrangements or methods related to powering off a display - 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 Methods and devices employing circuitry for quickly discharging pixels of a display before the display is turned off are provided. In one example, a method may include receiving at the electronic display a signal indicating the electronic display will be powered off within a period of time. The method may also include, in response to the signal, causing a frame of pixel data originating from the electronic display to be stored in pixels of the electronic display before the electronic display is powered off. Storing the frame of pixel data in the pixels may inhibit image artifacts from occurring on the electronic display when the electronic display is powered back on in the future. ## Claims ### Claim 1 A method for preparing an electronic display of an electronic device to be turned off comprising: receiving at the electronic display a signal indicating the electronic display will be powered off within a period of time; and in response to the signal, causing a frame of pixel data originating from the electronic display to be stored in pixels of the electronic display before the electronic display is powered off to inhibit image artifacts from occurring on the electronic display when the electronic display is powered back on in the future. ### Claim 2 (depends on 1) The method of claim 1, wherein the frame of pixel data produces a voltage difference between pixel electrodes and common electrodes substantially equal to ground. ### Claim 3 (depends on 1) The method of claim 1, wherein the frame of pixel data produces a voltage difference between pixel electrodes and common electrodes substantially equal to a darkest pixel value achieved during normal electronic display operation. ### Claim 4 (depends on 1) The method of claim 1, wherein the electronic display is powered off after a sufficient time has elapsed for discharging power supplied to the electronic display. ### Claim 5 (depends on 1) The method of claim 1, comprising outputting a feedback signal from the electronic display after the frame of pixel data is stored in the pixels of the electronic display, wherein the feedback signal indicates that the electronic display may be powered down without a residual bias voltage on the pixels of the electronic display. ### Claim 6 (depends on 5) The method of claim 5, comprising receiving an electronic display reset signal, after outputting the feedback signal, to stop operation of the electronic display before power to the electronic display is cut off. ### Claim 7 An electronic display comprising: a plurality of pixels; and display control circuitry configured to cause the plurality of pixels to be discharged after receiving an indication of an imminent reset of the electronic display but before the electronic display is powered down. ### Claim 8 (depends on 7) The electronic display of claim 7, wherein the display control circuitry is configured to cause the plurality of pixels to be discharged substantially within a period of time associated with a refresh rate of the electronic display during normal operation. ### Claim 9 An electronic device comprising: an electronic display configured, after receiving an indication of an imminent electronic display reset, to cause a frame of pixel data to be stored in pixels of the electronic display before power is removed from the electronic display to inhibit image artifacts from occurring when the electronic display is powered on at a later time; and a processor configured to send image data to the electronic display; wherein the electronic display is configured to ignore the image data from the processor after receiving the indication of the imminent electronic display reset. ### Claim 10 (depends on 9) The electronic device of claim 9, wherein the electronic display is configured to cause the frame of pixel data to be stored in pixels of the electronic display within approximately 16 ms when the electronic display normally operates at approximately 60 Hz. ### Claim 11 (depends on 9) The electronic device of claim 9, wherein the electronic display is configured to receive an electronic display reset signal within substantially 36 ms after receiving the indication of the imminent electronic display reset. ### Claim 12 (depends on 9) The electronic device of claim 9, wherein the processor is configured to send the indication of the imminent electronic display reset. ### Claim 13 (depends on 9) The electronic device of claim 9, comprising a power management unit configured to send the indication of the imminent electronic display reset. ### Claim 14 (depends on 13) The electronic device of claim 13, wherein the power management unit is configured to power off the electronic display after sending an electronic display reset signal. ### Claim 15 (depends on 13) The electronic device of claim 13, wherein the power management unit is configured to power off the electronic display substantially within a period of time associated with discharging power supplied to the electronic display. ### Claim 16 (depends on 13) The electronic device of claim 13, wherein the electronic display is configured to send a feedback signal to the power management unit after the frame of pixel data is stored in the pixels of the electronic display. ### Claim 17 (depends on 16) The electronic device of claim 16, wherein the electronic display is configured to send the feedback signal substantially within a period of time associated with a refresh rate of the electronic display during normal operation. ### Claim 18 (depends on 16) The electronic device of claim 16, wherein the electronic display is configured to receive an electronic display reset signal from the power management unit after sending the feedback signal. ### Claim 19 A method comprising: causing a frame of pixel data to be stored in pixels of an electronic display after the electronic display receives a signal indicating that the electronic display is about to be powered off, wherein the frame of pixel data originates from the electronic display; outputting a feedback signal from the electronic display after the frame of pixel data is stored in the pixels of the electronic display, wherein the feedback signal is output to a power management unit, a processor, or some combination thereof; and receiving an electronic display power off signal, after outputting the feedback signal, to power off the electronic display to limit image artifacts from occurring on the electronic display when the electronic display is powered back on at a later time. ### Claim 20 An electronic device comprising: a power management unit configured to control power applied within the electronic device; a processor configured to control operation of the electronic device; and an electronic display configured to stop displaying image data and to discharge pixel data from pixels of the electronic display after receiving an indication that an electronic display reset is about to occur, wherein the indication is received from the power management unit, the processor, or some combination thereof. ### Claim 21 (depends on 20) The electronic device of claim 20, wherein the indication that the electronic display reset is about to occur is received from the power management unit. ### Claim 22 (depends on 20) The electronic device of claim 20, wherein the indication that the electronic display reset is about to occur is received from the processor.