Liquid Crystal Display Timing Controller Refresh Rate Adjustment
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Solution Overview
Problem
Liquid crystal display devices face challenges in reducing power consumption while maintaining image quality, as refresh rate reduction leads to fluctuations in voltage between pixel and common electrodes, causing gray level changes and image deterioration.
Innovation Solution
A liquid crystal display device with a timing controller that adjusts the refresh rate based on the gray level of the image signal, using a lookup table and counter circuits to manage the display period and writing frequency, thereby minimizing gray level changes and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If refresh rate is reduced for still image display, then power consumption is lowered, but voltage fluctuation causes gray level changes and image quality deterioration
Solution Approach 1:
The patent applies dynamics by making the refresh rate adjustable rather than fixed. The timing controller dynamically changes the refresh rate based on whether the displayed image is moving or still, optimizing power consumption while maintaining image quality. For still images, the refresh rate is reduced to save power, while for moving images, it returns to normal to maintain display quality.
Solution Approach 2:
The patent changes the refresh rate parameter based on image type. By detecting whether the image is moving or still, the system adjusts the refresh rate parameter accordingly - using a lower refresh rate for still images to reduce power consumption while preventing gray level changes through controlled voltage maintenance.
2Use of energy by stationary object
If refresh rate is reduced, then power consumption decreases, but off-state current and leakage current cause voltage changes between pixel and common electrodes
Solution Approach 1:
The patent applies preliminary anti-action by proactively compensating for the harmful effects of off-state current and leakage current. The timing controller pre-adjusts the voltage between pixel and common electrodes to counteract the expected voltage changes caused by these currents during the extended idle period between refresh cycles, thereby maintaining stable gray levels despite reduced refresh rate.
Solution Approach 2:
The system uses feedback by monitoring the display state (moving or still image) and adjusting the refresh rate accordingly. The timing controller receives feedback about the image type and dynamically modifies the refresh rate to maintain voltage stability while optimizing power consumption.
Data Source
AI summary
It is an object to suppress deterioration of a displayed still image which is caused when a refresh rate is reduced. A liquid crystal display device includes a display portion controlled by a driver circuit and a timing controller for controlling the driver circuit. An image signal for displaying a still image is supplied to the timing controller. By the timing controller, a refresh rate in displaying an image corresponding to an image signal on the display portion reduced as a gray level number of the image signal is smaller.