LCD Driver Unit Symmetrical Overdrive Voltage Polarity
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Solution Overview
Problem
Existing liquid crystal display devices face issues with DC voltage components being applied to pixels, especially when gray-scale levels do not change, leading to inefficiencies in overdrive processing and potential DC component application.
Innovation Solution
A driver unit for electro-optical devices that performs overdrive processing in both positive and negative fields with symmetrical voltages, reducing the probability of DC voltage components being applied, and includes a signal processing section that corrects image signals based on stored correction amounts for improved gray-scale level changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If overdrive processing is performed only in the first field with alternating polarity, then the response speed of liquid crystal is increased, but DC voltage components are applied to pixels when gray-scale levels do not change
Solution Approach 1:
The patent applies periodic action by performing overdrive processing in alternating positive and negative fields in a systematic periodic manner. The signal processing section identifies pixels that require overdrive and applies corrected voltages with appropriate polarity in each field, creating a periodic pattern that prevents DC component accumulation while maintaining fast response speeds.
Solution Approach 2:
The patent changes the polarity parameter of the voltage applied to pixels based on the field type (positive or negative). The signal processing section determines the appropriate polarity for each field and applies overdrive voltages with matching polarity, ensuring that voltage parameters alternate systematically to prevent DC component application while maintaining effective gray-scale transitions.
2Productivity
If the correction amount for overdrive is continuously larger for positive polarity than for negative polarity, then overdrive processing is effective, but DC voltage components are applied to the liquid crystal
Solution Approach 1:
The patent applies asymmetry by using different correction amounts for positive and negative polarities. The signal processing section stores and applies different correction values in the lookup table depending on the field polarity, allowing optimized overdrive performance for each polarity type while maintaining overall balance to prevent DC component accumulation.
Solution Approach 2:
The patent implements dynamics by making the correction amount variable based on the field polarity and current gray-scale level. The signal processing section dynamically selects appropriate correction values from the lookup table based on the specific conditions of each field and pixel state, enabling adaptive overdrive processing that prevents DC components while maintaining effectiveness.
Data Source
AI summary
A liquid crystal display device is configured so that one frame is divided into two fields and a pixel of a liquid crystal panel is driven. The liquid crystal display device performs overdrive when a gray-scale level to be supplied to the pixel is different between a previous frame and a current frame. The liquid crystal display writes a voltage corresponding to the gray-scale level of the pixel with a positive voltage in a first field, and writes a voltage corresponding to the gray-scale level to be supplied to the pixel with a negative voltage in a second field. When performing overdrive, the liquid crystal display device performs overdrive in both of the first field and the second field. Also, when performing overdrive, the liquid crystal display device corrects the gray-scale level to be supplied to the pixel.