Liquid Crystal Device Dual-Mode Driving for Bend Alignment
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Solution Overview
Problem
Liquid crystal devices using OCB mode face challenges in maintaining bend alignment reliability while avoiding light leakage and adverse effects on display characteristics, particularly due to high voltage requirements for black insertion.
Innovation Solution
A liquid crystal device operates in two modes: a first operation mode for display with a gray-scale voltage and a second operation mode for non-display with a higher voltage to maintain bend alignment, incorporating a separated data line driving device to reduce element withstand voltage and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high voltage exceeding black level is applied for black insertion to maintain bend alignment, then the reliability of maintaining bend alignment is improved, but light leakage occurs and display characteristics are adversely affected
Solution Approach 1:
The patent applies a voltage that dynamically changes over time: initially applying a high voltage exceeding the black level to ensure reliable bend alignment maintenance, then reducing the voltage to a lower level that prevents light leakage. This time-varying voltage approach allows the system to achieve both reliable alignment maintenance and acceptable display characteristics during the same black insertion period.
Solution Approach 2:
The patent implements periodic voltage adjustment during black insertion by dividing the black insertion period into multiple phases: a first period with high voltage for reliable alignment maintenance, and subsequent periods with reduced voltage to minimize light leakage. This periodic action pattern allows the system to balance alignment reliability with display quality throughout the frame period.
2Reliability
If a high voltage is applied for black insertion to maintain bend alignment, then the bend alignment is maintained more reliably, but the element withstand voltage requirement increases
Solution Approach 1:
The patent uses dynamic voltage adjustment where the high voltage exceeding the black level is applied only during the initial period of black insertion when alignment maintenance is most critical. After this initial period, the voltage is reduced to a lower level that still maintains alignment but reduces the peak withstand voltage requirement for the liquid crystal element and driving circuitry.
Solution Approach 2:
The patent applies the high voltage during the initial period of black insertion to proactively ensure bend alignment maintenance before transitioning to lower voltage. This preliminary high-voltage action establishes reliable alignment early in the frame period, allowing subsequent periods to use lower voltages that reduce peak withstand voltage requirements while maintaining alignment stability.
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
The solution improves bend alignment reliability and reduces power consumption by applying a higher voltage in the non-display mode, minimizing light leakage and maintaining display quality.
Implementation Method 1
An alignment state of the liquid crystal varies on the basis of a voltage applied between the pixel electrodes and the opposite electrode. In this manner, the amount of light transmitted in each of pixels is varied
Implementation Method 2
The bend alignment is suitable for image display and is able to respond at a speed higher than an existing Twisted Nematic (TN) liquid crystal
Implementation Method 3
The OCB liquid crystal is placed in the splay alignment that is not suitable for image display
Data Source
AI summary
A liquid crystal device that operates in a first operation mode and a second operation mode. The liquid crystal device includes a plurality of scanning lines, a plurality of data lines, a plurality of pixel circuits, a scanning line driving device, and a data line driving device. The plurality of pixel circuits are provided at positions corresponding to intersections of the scanning line and the data lines. Each of the plurality of pixel circuits includes a liquid crystal element that has a first electrode, a second electrode, and a liquid crystal held between the first electrode and the second electrode. A first alignment, which is an initial state, and a second alignment for display are provided for the liquid crystal as an alignment state. The scanning line driving device selects the plurality of scanning lines in a predetermined order. The data line driving device supplies each of the pixel circuits corresponding to the selected one of scanning lines with a writing voltage through the corresponding data line. In the first operation mode, in one frame that includes a first period and a second period, the data line driving device outputs a gray-scale voltage corresponding to a gray-scale to be displayed as the writing voltage in the first period and outputs a first voltage, which is used for maintaining the second alignment, as the writing voltage to the data line in the second period. In the second operation mode, the data line driving device outputs a second voltage, which is used for maintaining the second alignment, as the writing voltage in all the period of the one frame. The second voltage is higher than the first voltage.