# US 2014/0198087 A1 · Method and circuit to optimize n-line lcd power consumption > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0198087 A1 - Document ID: US20140198087A1 - Status: Published application - Kind: A1 - Application number: 13/742,263 - Filed: 2013-01-15 - Published: 2014-07-17 - Earliest claimed: 2013-01-15 - Assignees: Synaptics Incorporated - Applicants: Synaptics Incorporated - Inventors: Imre Knausz; Brian Mott; John Childs - Web page: https://patentgrep.com/patent/US20140198087A1 ## CPC - G06F 1/3218: of display devices - G06F 3/041: Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means - G06F 3/0412: {Digitisers structurally integrated in a display} - G06F 3/0416: {Control or interface arrangements specially adapted for digitisers} - G06F 3/04184: {Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally} - G06F 3/044: by capacitive means - G06F 3/0446: {using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes} - G09G 3/3688: {suitable for active matrices only} - G09G 3/3614: {Control of polarity reversal in general} - G09G 2310/0291: Details of output amplifiers or buffers arranged for use in a driving circuit - G09G 2310/0297: Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns - G09G 2330/023: using energy recovery or conservation - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - 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 Embodiments of the invention generally provide an input device that includes one or more source drivers that are coupled to a display screen. Specifically, one of the source drivers may be coupled to a plurality of source lines (or column lines) on the display screen which the source driver uses to set voltages associated with one or more sub-pixels that determine the color displayed by the pixel. When driving voltages onto subsequent source lines, the input device may precharge the source driver using a latent voltage stored on the source lines. That is, if the source line was previously driven to a particular voltage by the source driver, the input device uses that latent voltage to precharge the output of the source driver to the same voltage. The source driver may then adjust its output to a desired voltage and drive the desired voltage onto the source line and sub-pixel. ## Claims ### Claim 1 A method for updating a display device, the method comprising: driving a first voltage on a first source line in the display device using an amplifier in a source driver; after decoupling the source driver from the first source line, disabling the amplifier; while the amplifier is disabled, coupling the source driver to a second source line in the display device, wherein the second source line was previously charged to a latent voltage, wherein the latent voltage alters the charge stored in the precharge circuitry; and after altering the charge, enabling the amplifier such that an output of the amplifier drives a second voltage on the second source line. ### Claim 2 (depends on 1) The method of claim 1, further comprising: while altering the charge, coupling the precharge circuitry to a reference voltage; and decoupling the precharge circuitry from the reference voltage when driving the second voltage on the second source line. ### Claim 3 (depends on 2) The method of claim 2, wherein, while altering the charge, the second source line, the precharge circuitry, and the reference voltage form an electric path through which charge flows. ### Claim 4 (depends on 1) The method of claim 1, wherein the precharge circuitry comprises a capacitive element that is used to compensate the amplifier. ### Claim 5 (depends on 4) The method of claim 4, wherein the source driver comprises a first amplifier stage coupled to a second amplifier stage, the second amplifier stage comprising the amplifier, wherein a first end of the capacitive element is coupled to a node between an output of the first amplifier stage and an input of the second amplifier stage and a second end of the capacitive element is coupled to the output the amplifier. ### Claim 6 (depends on 1) The method of claim 1, wherein the first and second source lines are associated with respective sub-pixels of a color pixel in the display device. ### Claim 7 (depends on 1) The method of claim 1, further comprising: receiving respective input signals at the source driver for driving the first and second voltages, wherein the amplifier and the precharge circuitry amplify the respective input signals to drive the first and second voltages. ### Claim 8 A display driver, comprising: a source driver configured to selectively couple to a first source line and a second source line in a display panel, the source driver comprising: an amplifier, wherein the source driver is configured to drive a first voltage on the first source line and a second voltage on the second source line using the amplifier; precharge circuitry; and amplifier control logic configured to disable the amplifier after the first voltage is driven onto the first source line and the source driver is decoupled from the first source line, wherein, while the amplifier is disabled, the source driver is configured to alter a charge stored in the precharge circuitry based on a latent voltage previously driven onto the second source line, wherein, after altering the charge in the precharge circuitry, the amplifier control logic is configured to enable the amplifier such that an output of the amplifier drives the second voltage onto the second source line. ### Claim 9 (depends on 8) The display driver of claim 8, further comprising: a switch element configured to, while the source drive alters the charge stored in the precharge circuity, couple the precharge circuitry to a reference voltage and decouple the precharge circuitry from the reference voltage when driving the second voltage on the second source line. ### Claim 10 (depends on 8) The display driver of claim 8, wherein, while altering the charge, the second source line, the precharge circuitry, and the reference voltage form an electric path through which charge flows. ### Claim 11 (depends on 8) The display driver of claim 8, wherein the precharge circuitry comprises a capacitive element that used to compensate the amplifier. ### Claim 12 (depends on 11) The display driver of claim 11, wherein the source driver comprises a first amplifier stage coupled to a second amplifier stage, the second amplifier stage comprising the amplifier, wherein a first end of the capacitive element is coupled to a node between an output of the first amplifier stage and an input of the second amplifier stage and a second end of the capacitive element is coupled to the output the amplifier. ### Claim 13 (depends on 8) The display driver of claim 8, wherein the first and second source lines are associated with respective sub-pixels of a color pixel in the display device. ### Claim 14 (depends on 8) The display driver of claim 8, wherein the source driver is configured to receive respective input signals for driving the first and second voltages, wherein the amplifier and the precharge circuitry amplify the respective input signals to drive the first and second voltages. ### Claim 15 A display device, comprising: a display panel, comprising: a first source line, a second source line, and a selection element, and a source driver, wherein the source driver is selectively coupled to the first and second source line via the selection element, the source driver comprising: an amplifier configured to drive a first voltage on the first source line and a second voltage on the second source line; precharge circuitry; and amplifier control logic configured to disable the amplifier after the first voltage is driven onto the first source line and the source driver is decoupled from the first source line using the selection element, wherein, while the amplifier is disabled, the selection element is configured to couple the second source line to the precharge circuitry to alter a charge stored in the precharge circuitry based on a latent voltage previously driven onto the second source line, wherein, after altering the charge in the precharge circuitry, the amplifier control logic is configured to enable the amplifier such that an output of the amplifier drives the second voltage onto the second source line. ### Claim 16 (depends on 15) The display device of claim 15, the source driver comprising: a switch element configured to, while the source drive alters the charge stored in the precharge circuity, couple the precharge circuitry to a reference voltage and decouple the precharge circuitry from the reference voltage when driving the second voltage on the second source line. ### Claim 17 (depends on 15) The display device of claim 15, wherein, while altering the charge, the second source line, the precharge circuitry, and the reference voltage form an electric path through which charge flows. ### Claim 18 (depends on 15) The display device of claim 15, wherein the precharge circuitry comprises a capacitive element that is used to compensate the amplifier. ### Claim 19 (depends on 18) The display device of claim 18, wherein the source driver comprises a first amplifier stage coupled to a second amplifier stage, the second amplifier stage comprising the amplifier, wherein a first end of the capacitive element is coupled to a node between an output of the first amplifier stage and an input of the second amplifier stage and a second end of the capacitive element is coupled to the output the amplifier. ### Claim 20 (depends on 15) The display device of claim 15, wherein the first and second source lines are associated with respective sub-pixels of a color pixel in the display device.