Display Driver Segmentation for Low Power Black Image Precharging
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Solution Overview
Problem
Display devices in low power mode face limitations in reducing power consumption due to continuous operation of output buffers and color differences between black images in different panel regions, as well as increased panel load and leakage current from gamma voltage generators.
Innovation Solution
A display driving device and method that precharges data lines with a black image signal using output buffers for specific horizontal lines and utilizes a gamma voltage generator for other lines, minimizing power consumption and reducing color differences by selectively connecting analog processing units and gamma voltage generators based on operation mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If output buffers are kept turned on to represent black voltage in the first region, then black image quality is maintained, but power consumption continues without reduction
Solution Approach 1:
The display panel is divided into a first region displaying standby image and a second region displaying black image. The driving method segments the operation of output buffers by region: in the first region, output buffers remain on to maintain black voltage for standby image, while in the second region, output buffers are turned off and gamma voltage generator is used to supply black voltage. This segmentation allows power reduction in the second region while maintaining image quality in the first region.
Solution Approach 2:
Different driving methods are applied to different regions of the display panel. The first region uses conventional output buffer operation to maintain black voltage for standby image display, while the second region uses gamma voltage generator to supply black voltage and turns off output buffers. This local differentiation optimizes both power consumption and image quality in respective regions.
2Reliability
If gamma voltage generator continuously outputs black gradation voltage, then black image is displayed, but leakage current increases
Solution Approach 1:
The gamma voltage generator operates periodically rather than continuously. It outputs black gradation voltage only when needed for specific horizontal lines in the second region, then stops. The output buffers are turned off after precharging data lines, creating periodic operation that reduces continuous leakage current while maintaining black image display capability when required.
3Use of energy by moving object
If output buffers are turned off to reduce power consumption, then power consumption decreases, but color difference between black in first and second regions increases
Solution Approach 1:
The gamma voltage generator acts as an intermediary between the power reduction need and the color consistency requirement. It supplies black voltage to the second region without requiring output buffers to remain on, thus reducing power consumption while maintaining appropriate black voltage levels. The gamma voltage generator mediates between the conflicting requirements of power reduction and color consistency.
4Ease of operation
If all horizontal lines use output buffers for data signaling, then data transmission is simple, but panel load increases
Solution Approach 1:
Horizontal lines are segmented into two types: precharge horizontal lines that use output buffers for data signaling, and other horizontal lines that use gamma voltage generator. This segmentation reduces the overall panel load by distributing the workload between the two components based on their operational characteristics and power consumption profiles.
Data Source
AI summary
A display driving device supporting a low power mode according to an aspect of the present disclosure that is capable of minimizing power consumption when driving in the low power mode includes a plurality of output buffers connected to data lines to precharge the data lines with a first data signal corresponding to a black image when a precharge horizontal line is driven in a display panel including a first region where a standby image is displayed and the second region where the black image is displayed, the precharge horizontal line being included in the second region, and a gamma voltage generator connected to the data lines to output the first data signal to the data lines when other horizontal lines other than the precharge horizontal line in the second region are driven.