Liquid Crystal Display Driving With Floating Electrodes
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Solution Overview
Problem
Existing liquid crystal display devices face challenges in reducing power consumption while maintaining image quality, particularly during still image display, due to complex driver circuit operations and insufficient reduction of refresh rates, leading to image deterioration.
Innovation Solution
The method involves using oxide semiconductors in thin film transistors for pixel and switching transistors, allowing the pixel electrode and common electrode to float during still image display, and controlling transistor states to minimize driver circuit operations, with a comparator circuit to differentiate between still and moving images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If refresh rate is significantly decreased in still image display to reduce power consumption, then power consumption is reduced, but image quality deteriorates due to charge leakage and noise
Solution Approach 1:
The display period is segmented into moving image periods and still image periods with different refresh rates. The system divides operation modes to apply low refresh rate only during still image display while maintaining high refresh rate during moving image display, thus reducing power consumption without compromising image quality during motion
Solution Approach 2:
Image signals are held in a storage circuit before display. By preliminarily storing the image signal and maintaining it during the hold period, the system can display still images without continuous refresh, reducing power consumption while preventing charge leakage and noise from affecting image quality
2Use of energy by moving object
If driver circuit operation is simplified to reduce power consumption, then power consumption is reduced, but image quality deteriorates due to potential fluctuations and noise
Solution Approach 1:
The driver circuit operations are extracted and separated into essential functions (signal output to electrodes) and non-essential functions (continuous signal line driving). By taking out only the necessary driver circuit operations during still image display, power consumption is reduced while image quality is maintained through proper signal line potential control
Solution Approach 2:
The driver circuit is designed to perform multiple functions: driving gate lines and signal lines during moving image display, and maintaining signal line potentials during still image display. This multi-functionality allows the same circuit to reduce power consumption while preventing image deterioration through appropriate potential maintenance
Data Source
AI summary
The liquid crystal display device includes a first substrate provided with a terminal portion, a switching transistor, a driver circuit portion, and a pixel circuit portion including a pixel transistor and a plurality of pixels, a second substrate provided with a common electrode electrically connected to the terminal portion through the switching transistor, and liquid crystal between a pixel electrode and the common electrode. In a period during which a still image is switched to a moving image, the following steps are sequentially performed: a first step of supplying the common potential to the common electrode; a second step of supplying a power supply voltage to the driver circuit portion; a third step of supplying a clock signal to the driver circuit portion; and a fourth step of supplying a start pulse signal to the driver circuit portion.