Liquid Crystal Display Drive Circuit Polarity Inversion Control
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Solution Overview
Problem
Liquid crystal display devices experience horizontal stripes when liquid crystal pixels are driven in multiple steps due to unwanted potential variations in signal lines, particularly when pixel voltages are set at opposite polarities in units of multiple rows, leading to fluctuations in brightness and display quality.
Innovation Solution
A liquid crystal display device with a drive circuit that includes a signal line driver, a multiplexer, and a controller, which outputs pixel voltages in parallel to signal line groups and controls the multiplexer to connect and disconnect signal line groups sequentially to maintain uniform polarity inversion, preventing potential variations across signal lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If liquid crystal pixels are driven in multiple steps with polarity inversion in units of multiple rows, then the circuit scale of signal line driver is reduced, but horizontal stripes occur due to unwanted potential variations in signal lines
Solution Approach 1:
The patent applies preliminary action by setting the potentials of signal lines to predetermined values before polarity inversion occurs. The potential setting unit pre-charges or pre-discharges signal lines to specific potentials before the polarity inversion step, preventing unwanted potential variations during the inversion process. This preliminary preparation ensures that when polarity inversion happens, the signal lines transition smoothly without causing horizontal stripes in the display.
2Illumination intensity
If pixel voltages are set at opposite polarities on a row-by-row basis, then flicker is prevented, but horizontal stripes occur when polarity inversion is applied in units of multiple rows
Solution Approach 1:
The patent segments the polarity inversion process into distinct phases: potential setting phase and polarity inversion phase. By dividing the driving waveform into these separate segments, the system can first establish proper potentials for all signal lines, then perform polarity inversion uniformly across all lines. This segmentation prevents the horizontal stripe artifact that would otherwise occur when polarity inversion is applied without prior potential normalization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution prevents the occurrence of horizontal stripes by ensuring uniform potential inversion across signal lines, even when capacitive-coupling occurs, thereby maintaining consistent display quality during multi-step driving of liquid crystal pixels.
Implementation Method 1
even if the signal lines are capacitive-coupled to each other, the potentials of the signal lines do not greatly vary
Data Source
AI summary
A liquid crystal display device includes liquid crystal pixels, signal line groups each including a predetermined number of signal lines, and a drive circuit which selects the pixels on a row-by-row basis and drives the pixels of the selected row via the signal lines. The drive circuit includes a signal line driver which outputs a predetermined number of pixel voltages for each group driving period while the pixels of each row are being selected, a multiplexer which distributes to each signal line group the pixel voltages output from the signal line driver, and a controller which controls the multiplexer to electrically connect all of the signal line groups to the signal line driver and electrically disconnect the signal line groups one by one from the signal line driver for each group driving period, in a selection period of the pixels of an initial row that requires polarity inversion.