Cholesteric Liquid Crystal Display Voltage Control for Image Uniformity
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Solution Overview
Problem
Liquid crystal display devices with passive matrix structures face challenges in speeding up image display without causing unevenness due to insufficient transition of molecular structures when shortening the application time of pulse voltage, leading to incomplete transitions between planar and focal conic states.
Innovation Solution
A liquid crystal display device that applies a synthesized voltage from both the segment and common drivers to ensure the molecular structure of previous drive lines transitions to a focal conic state, regardless of image data, by setting voltages such that the molecular structure of previous drive lines is uniformly arranged to a focal conic state, even when the voltage application time is shortened.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the application time of pulse voltage is shortened to speed up image display, then the display speed is improved, but the molecular structure transition becomes incomplete causing image unevenness
Solution Approach 1:
The patent applies a preliminary voltage to the previous drive line before the drawing line to pre-transition the molecular structure to a focal conic state. This preliminary action ensures that when the main voltage is applied to the drawing line, the molecular structure is already in the desired state, allowing for faster display without image unevenness.
Solution Approach 2:
The patent applies different voltage conditions to different lines: the previous drive line receives a preliminary voltage to establish focal conic state, while the drawing line receives the full voltage according to image data. This local differentiation ensures optimal molecular structure transition in each region, resolving the contradiction between speed and uniformity.
2Duration of action of moving object
If the voltage application time is reduced to achieve faster display, then the response time is improved, but the molecular structure cannot fully transition between planar and focal conic states
Solution Approach 1:
By applying voltage to the previous drive line before the drawing line, the molecular structure transition is initiated in advance. This preliminary action reduces the time needed for complete transition when the main voltage is applied, achieving both fast response and complete molecular structure transition.
Solution Approach 2:
The voltage application is continuous across multiple lines in sequence. The previous drive line receives voltage first, then the drawing line follows. This continuous action ensures that molecular structure transition is always progressing, maintaining reliability while reducing total application time.
3Device complexity
If a passive matrix structure is used to simplify the display device, then the device complexity is reduced, but the image display speed is limited due to sequential voltage application
Solution Approach 1:
The passive matrix structure combines with preliminary voltage application to the previous drive line. This allows the simple passive matrix architecture to achieve faster display speeds by pre-preparing the molecular structure state before the main voltage is applied to the drawing line, thus resolving the contradiction between simplicity and speed.
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 approach allows for faster and more uniform image display by ensuring consistent molecular structure transitions, reducing image unevenness and enabling clear, high-contrast displays even with shorter voltage application periods.
Implementation Method 1
the molecular structure of cholesteric liquid crystal is changed in accordance with the intensity of an applied electric field. For example, when a strong electric field is given to cholesteric liquid crystal, the helical structure of a liquid crystal molecule uncoils perfectly
Implementation Method 2
a liquid crystal display element that uses cholesteric liquid crystal has an excellent characteristic such as a semi-permanent display retention characteristic, a bright color display characteristic
Implementation Method 3
the molecular structure of liquid crystal becomes a so-called planar state in which light according to a pitch of a helical structure is selectively reflected
Implementation Method 4
the molecular structure of liquid crystal becomes a so-called focal conic state in which incident light is transmitted
Data Source
AI summary
A liquid crystal display device includes a segment driver, a common driver, and a voltage setting unit. The voltage setting unit derives a voltage at which a previous drive line becomes a focal conic state regardless of image data by applying a synthesized voltage of a voltage that is applied from the segment driver and a voltage that is applied from the common driver to the previous drive line. Then, the voltage setting unit sets the voltages that are applied from the segment driver and the common driver on the basis of the derived result.