# US 2014/0198093 A1 · Low power display device with variable refresh rates > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0198093 A1 - Document ID: US20140198093A1 - Status: Published application - Kind: A1 - Application number: 14/155,300 - Filed: 2014-01-14 - Published: 2014-07-17 - Earliest claimed: 2013-01-14 - Assignees: Apple Inc. - Applicants: Apple Inc. - Inventors: Prasanna Nambi; Jason N. Gomez; Fenghua Zheng; Paolo Sacchetto; Sandro H. Pintz; Taesung Kim; Christopher P. Tann; Marc Albrecht; David W. Lum - Web page: https://patentgrep.com/patent/US20140198093A1 ## CPC - G09G 3/3618: {with automatic refresh of the display panel using sense/write circuits} - G06T 1/20: Processor architectures; Processor configuration, e.g. pipelining - G09G 3/36: using liquid crystals - G09G 3/3611: {Control of matrices with row and column drivers} - G09G 3/3648: {using an active matrix (G09G3/367 - G09G3/3696 take precedence)} - G09G 3/3696: {Generation of voltages supplied to electrode drivers} - G06T 2210/52: Parallel processing - G09G 3/3655: {Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors} - G09G 2310/08: Details of timing specific for flat panels, other than clock recovery - G09G 2320/0626: for control of overall brightness - G09G 2330/02: Details of power systems and of start or stop of display operation - G09G 2330/021: Power management, e.g. power saving - G09G 2340/0435: Change or adaptation of the frame rate of the video stream - G09G 2360/18: Use of a frame buffer in a display terminal, inclusive of the display panel - G09G 2370/08: Details of image data interface between the display device controller and the data line driver circuit - 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) - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract The disclosure describes procedures for dynamically employing a variable refresh rate at an LCD display of a consumer electronic device, such as a laptop computer, a tablet computer, a mobile phone, or a music player device. In some configurations, the consumer electronic device can include a host system portion, having one or more processors and a display system portion, having a timing controller, a buffer circuit, a display driver, and a display panel. The display system can receive image data and image control data from a GPU of the host system, evaluate the received image control data to determine a reduced refresh rate (RRR) for employing at the display panel, and then transition to the RRR, whenever practicable, to conserve power. In some scenarios, the transition to the RRR can be a transition from a LRR of 50 hertz or above to a RRR of 40 hertz or below. ## Claims ### Claim 1 A method for conserving power at a liquid crystal display (LCD), the method comprising: at a display driver, receiving a first input signal from a display controller; at the display driver, determining a setting of the first input signal; at the display driver, selectively shutting down one or more circuits of the LCD based on the setting of the first input signal, wherein the setting of the first input signal is further configured to control an output voltage of the display driver. ### Claim 2 (depends on 1) The method of claim 1, further comprising: at the display driver, receiving a second input signal from the display controller; at the display driver, determining a setting of the second input signal; and at the display driver, selectively shutting down one or more circuits of the LCD based on the setting of the second input signal. ### Claim 3 (depends on 2) The method of claim 2, wherein: a digital circuit portion of the display driver is required to determine the setting of the second input signal; and the setting of the second input signal is a protocol setting that cannot shut down the digital circuit portion of the display driver. ### Claim 4 (depends on 1) The method of claim 1, further comprising, at the display driver, selectively shutting down a digital circuit portion of the display driver based on the setting of the first input signal. ### Claim 5 (depends on 1) The method of claim 1, wherein: the display driver is a column driver that is configured to drive a display panel of the LCD; and the first input signal is received at a dedicated hardware pin of the column driver. ### Claim 6 (depends on 1) The method of claim 1, wherein: the setting of the first input signal is further configured to set an impedance at an output of the display driver; and a display panel of the LCD is a load at the output of the display driver. ### Claim 7 (depends on 1) The method of claim 1, wherein the setting of the first input signal is configured to control the output voltage of the display driver to: i. increase a luminosity level of a display panel of the LCD when the LCD is operating at a reduced refresh rate; or ii. decrease a luminosity level of a display panel of the LCD when the LCD is operating at an increased refresh rate. ### Claim 8 A column driver of a liquid crystal display (LCD), comprising: frontend circuitry for receiving input signals; and backend circuitry for outputting a reference voltage to a display panel, wherein the column driver is configured to: receive at least one input signal from a display controller; determine one or more settings from the at least one input signal; and shut down at least a portion of the column driver based on the one or more settings of the at least one input signal. ### Claim 9 (depends on 8) The column driver of claim 8, wherein a first setting of the one or more settings is received as an input signal at a dedicated hardware pin of the column driver. ### Claim 10 (depends on 9) The column driver of claim 9, wherein the first setting is a non-protocol setting that is configured to shut down all circuitry of the column driver. ### Claim 11 (depends on 9) The column driver of claim 9, wherein a second setting of the one or more settings is a protocol setting that cannot shut down a digital circuit portion of the column driver. ### Claim 12 (depends on 9) The column driver of claim 9, wherein the first setting is configured to control a voltage value for the reference voltage. ### Claim 13 (depends on 12) The column driver of claim 12, wherein the output voltage value of the reference voltage determines a luminosity of the display panel. ### Claim 14 (depends on 9) The column driver of claim 9, wherein: the first setting is configured to set a specific impedance at an output of the column driver; and the display panel is a load at the output of the column driver. ### Claim 15 A method for conserving power at a liquid crystal display (LCD), the method comprising: at a display driver, receiving at least one input signal from a display controller; at the display driver, determining one or more settings from the at least one input signal; and at the display driver, shutting down at least a portion of the display driver based on the one or more settings of the at least one input signal, wherein a first setting of the one or more settings is configured to control a voltage value of a reference voltage output of the display driver, and wherein the voltage value of the reference voltage is proportional to a luminosity level of a display panel of the LCD. ### Claim 16 (depends on 15) The method of claim 15, wherein the first setting is received as an input signal at a dedicated hardware pin of the display driver. ### Claim 17 (depends on 15) The method of claim 15, wherein the first setting is a non-protocol setting that is configured to shut down all circuitry of the display driver. ### Claim 18 (depends on 17) The method of claim 17, wherein a second setting of the one or more settings is a protocol setting that cannot shut down a digital circuit portion of the display driver. ### Claim 19 (depends on 15) The method of claim 15, wherein: the first setting is configured to set a specific impedance at an output of the display driver; and the display panel is a load at the output of the display driver. ### Claim 20 (depends on 15) The method of claim 15, wherein the first setting is configured to control the voltage value of the reference voltage output to: i. increase a luminosity level of the display panel when the LCD is operating at a reduced refresh rate; or ii. decrease a luminosity level of the display panel when the LCD is operating at an increased refresh rate.