LCD Data Driving Circuit Polarity Control
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Solution Overview
Problem
Conventional liquid crystal display inversion methods cause luminance differences between neighboring cells due to varying response times, leading to power consumption and heat generation issues, as well as picture quality degradation.
Innovation Solution
The liquid crystal display employs a divided block-type column inversion method where the polarity of the data voltage is maintained within each block, and Over Driving Control (ODC) modulation is applied only when the polarity is inverted, or the ODC modulation rate is increased to compensate for response time differences, ensuring uniform response times across the screen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the polarity of data voltage is inverted many times (dot inversion method), then picture quality is improved with no flicker or luminance difference, but power consumption and heat generation increase
Solution Approach 1:
The display panel is divided into multiple blocks (e.g., 4 blocks) along the data line direction, and polarity inversion is applied selectively to different blocks in different time periods. This segmentation allows reducing the frequency of polarity inversion for each individual data line while maintaining the overall inversion effect across the display, thereby reducing power consumption and heat generation while preserving picture quality.
2Illumination intensity
If the polarity of data voltage is inverted many times (dot inversion method), then picture quality is improved with no flicker or luminance difference, but heat generation increases
Solution Approach 1:
The display panel is divided into multiple blocks (e.g., 4 blocks) along the data line direction, and polarity inversion is applied selectively to different blocks in different time periods. This segmentation allows reducing the frequency of polarity inversion for each individual data line while maintaining the overall inversion effect across the display, thereby reducing power consumption and heat generation while preserving picture quality.
3Use of energy by moving object
If the polarity of data voltage is not inverted during one frame period (column inversion method), then power consumption and heat generation are reduced, but luminance difference appears between neighboring cells due to response time differences
Solution Approach 1:
The display panel is divided into multiple blocks (e.g., 4 blocks) along the data line direction, and polarity inversion is applied selectively to different blocks in different time periods. This segmentation allows reducing the frequency of polarity inversion for each individual data line while maintaining the overall inversion effect across the display, thereby reducing power consumption and heat generation while preserving picture quality.
Solution Approach 2:
Over driving control is applied in advance to cells that will experience polarity inversion, by pre-modulating the data voltage to compensate for the upcoming polarity change. This preliminary action ensures that cells maintain uniform response times even when polarity inversion occurs, preventing luminance differences between neighboring cells while maintaining low power consumption.
4Reliability
If Over Driving Control is applied to all data lines, then response time uniformity is improved, but power consumption and heat generation increase
Solution Approach 1:
Over driving control is applied selectively only to data lines that experience polarity inversion, while data lines maintaining constant polarity do not receive ODC modulation. This local application of ODC reduces unnecessary power consumption while ensuring that response time uniformity is maintained for the critical cells that do undergo polarity changes.
Data Source
AI summary
The liquid crystal display of the present invention lowers the power consumption and heat generation of the data driving circuit by controlling the polarity of a data voltage by divided block-type column inversion to maintain the polarity of the data voltage within one block, and prevents picture quality degradation by inverting the polarity of a data voltage between neighboring blocks.