Liquid Crystal Display Scan Line Drive Circuit for Luminance Uniformity
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Solution Overview
Problem
Liquid crystal display devices with high resolution and high definition face challenges in maintaining contrast due to increased scan lines, leading to luminance differences between regions during 3D active system driving and field sequential operations, and require longer shutter open times for 3D glasses or RGB light sources.
Innovation Solution
A liquid crystal display device with a first and second region, where scan lines and data lines are driven by separate circuits, with active scan signals applied in opposite directions across regions and data signals inverted in polarity, synchronizing timing to reduce luminance differences and shorten screen rewriting time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of scan lines is increased to achieve high resolution, then the image quality is improved, but the contrast is lowered and luminance difference occurs between regions
Solution Approach 1:
The liquid crystal display panel is divided into two separate screens (first screen with first to m-th scan lines, second screen with m+1-th to 2m-th scan lines). Each screen is driven by separate scan line drive circuits that supply active scan signals in opposite directions simultaneously. This segmentation allows independent control of each region, enabling high resolution while maintaining luminance uniformity through coordinated opposite-direction scanning.
2Device complexity
If active scan voltage is applied sequentially to first region then second region, then the circuit control is simplified, but luminance difference is emphasized at the boundary unit of the regions
Solution Approach 1:
The scan line drive circuits are configured to supply active scan signals to both first and second screens simultaneously in opposite directions from the outset. This preliminary coordination of opposite-direction scanning prevents the accumulation of luminance differences that would occur with sequential scanning, thereby eliminating boundary luminance emphasis while maintaining manageable circuit control through pre-established drive patterns.
3Device complexity
If sequential scanning of first and second regions is used, then the scan control is simplified, but the time necessary for rewriting of one screen is extended
Solution Approach 1:
Both scan line drive circuits operate simultaneously and continuously in opposite directions, ensuring that both first and second screens are being scanned and updated at the same time. This continuous parallel operation eliminates the idle time that would occur during sequential scanning transitions, thereby halving the total screen rewriting time while maintaining manageable scan control through symmetric drive patterns.
4Productivity
If shutter open time of 3D glasses is shortened to accommodate high resolution, then the frame rate is improved, but the luminance difference and image quality deteriorate
Solution Approach 1:
The display is segmented into two independently scanned screens with separate drive circuits operating in opposite directions. This segmentation enables the system to maintain longer effective shutter open times for 3D display by efficiently utilizing parallel scanning, thereby improving frame rate while preserving luminance uniformity through coordinated drive patterns that prevent boundary effects.
Data Source
AI summary
A liquid crystal display device supplies an active scan signal to each scan line while skipping a portion of a plurality of the scan lines, per one horizontal scan period, in a direction of the m-th to the first scan lines, by a first scan line drive circuit, and supplies the active scan signal to each scan line while skipping the portion of the plurality of the scan lines, per one horizontal scan period, in a direction of the m+1-th to the 2m-th scan lines, by a second scan line drive circuit. Therefore, the liquid crystal display device synchronizes with a timing of supplying the active signal with the first scan line drive circuit and the second scan line drive circuit, and supplies a data signal whose polarity is inverted to a positive polarity potential and a negative polarity potential per one horizontal scan period, to a data line.