Liquid Crystal Display Compensation Capacitor Ripple Suppression
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Solution Overview
Problem
Liquid crystal display devices experience a 'line dim' phenomenon due to severe ripple phenomena in the common voltage, degrading display quality, especially during polarity changes of the data voltage.
Innovation Solution
The implementation of compensation capacitors arranged on opposite sides of the pixel array region, coupled with a data driver that adjusts the compensation data voltage levels during polarity changes and maintaining intervals, synchronized with the data voltage timing to suppress common voltage ripples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If inversion driving scheme is used to vary polarity of data voltage, then display quality is improved through better contrast, but common voltage ripple becomes severe causing line dim phenomenon
Solution Approach 1:
The patent converts the harmful ripple phenomenon into a beneficial compensation mechanism. By detecting the ripple voltage generated during polarity inversion and applying it as a compensation signal to the common electrode, the originally harmful voltage fluctuation is transformed into a useful correction that eliminates the line dim phenomenon and stabilizes display quality.
Solution Approach 2:
The patent implements a feedback control mechanism where the common voltage ripple is detected and measured, then this detected signal is fed back to the common electrode through the compensation circuit. This closed-loop feedback system continuously monitors and corrects voltage fluctuations, maintaining stable common voltage despite polarity changes in the data voltage.
2Stability of the object's composition
If compensation capacitors are added to suppress common voltage ripple, then common voltage stability is improved, but device complexity increases
Solution Approach 1:
The patent makes the common electrode serve multiple functions: it acts as both the standard common electrode for liquid crystal control and simultaneously as part of the compensation circuit through the connected capacitor. This multi-functionality allows the same component to perform both display control and ripple compensation, avoiding the need for entirely separate compensation circuitry.
Solution Approach 2:
The compensation capacitor acts as an intermediary element that mediates between the data voltage variations and the common electrode. Rather than directly controlling the common electrode or modifying the data lines, the capacitor serves as a buffering intermediary that absorbs and compensates for voltage ripples, simplifying the overall control architecture.
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
Effectively cancels out common voltage ripples, improving display quality by maintaining stable voltage levels and reducing line dim effects.
Implementation Method 1
a compensation capacitor, coupled to a common line
Implementation Method 2
the liquid crystal cell adjusts an amount of light passing through a polarizing plate
Implementation Method 3
Driven by an electric field generated according to a voltage difference between a voltage of a pixel electrode and a common voltage
Data Source
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AI summary
A liquid crystal display device in accordance with various embodiments comprises: a plurality of pixels (P) arranged in rows and columns in a matrix form; a common line (VcomL) coupled to a common electrode of the plurality of pixels (P); at least one compensation capacitor (Cdc) coupled to the common line (VcomL); a data driver (240) configured to: apply a data voltage (ADATA) having a first polarity to a pixel (P) of the plurality of pixels (P); subsequently change the polarity of the data voltage (ADATA) from the first polarity to a second polarity; and charge a compensation data voltage (ADDATA) into the compensation capacitor (Cdc) while changing the polarity of the data voltage (ADATA) from the first polarity to the second polarity, so as to reduce ripples in a common voltage (Vcom) applied to the common line (VcomL).