Display Panel Driving Method for Coupling Capacitance Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In liquid crystal display (LCD) panels, the increased frame frequency to prevent video motion blur leads to coupling capacitance between pixel electrodes and the common electrode, causing distorted common voltage, which results in display quality issues like reddishness, horizontal stripes, and crosstalk due to insufficient pixel recharge during the horizontal period.
Innovation Solution
A method of driving the display panel that compensates for coupling capacitance by calculating and adjusting grayscale data based on variations between adjacent pixel rows, using look-up tables to determine coupling capacitance and adjust data voltages, and incorporating a bypass mechanism for when capacitance is below a reference value, with feedback for recalculating capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If frame frequency is increased to prevent video motion blur, then motion blur is reduced, but coupling capacitance between pixel electrodes and common electrode causes distorted common voltage leading to display quality deterioration
Solution Approach 1:
The patent applies preliminary action by calculating and compensating for coupling capacitance effects in advance before displaying the image. The timing controller computes coupling capacitance compensation values based on grayscale data variations between adjacent pixel rows, and applies these compensations to the data voltages before they are sent to the pixel electrodes. This pre-compensation approach allows the system to operate at high frame frequencies without suffering from the detrimental effects of coupling capacitance, thus resolving the contradiction between high speed operation and display quality.
2Speed
If cell gap is decreased to enhance liquid crystal response rate, then response rate is improved, but coupling capacitance is generated between pixel electrode and common electrode causing common voltage distortion
Solution Approach 1:
The patent replaces the mechanical approach of maintaining physical distance (cell gap) to reduce coupling capacitance with an electrical compensation approach. Instead of increasing the cell gap to reduce capacitance effects, the timing controller calculates coupling capacitance based on grayscale data variations and applies compensation voltages to counteract the capacitance effects. This substitution allows the system to maintain the small cell gap for fast response while compensating for the resulting common voltage distortion through computational methods.
3Reliability
If feedback reversed compensating circuit is configured to compensate distorted common voltage, then common voltage distortion is compensated, but RC load of panel is increased and compensating charges become insufficient when horizontal period is short
Solution Approach 1:
The patent extracts the coupling capacitance compensation function from the physical hardware level (feedback reversed compensating circuit) and moves it to the data processing level (timing controller). Instead of using a complex hardware circuit that increases RC load, the system calculates coupling capacitance compensation values digitally based on grayscale data variations between adjacent pixel rows, and applies these compensations to the data voltages. This extraction of the compensation function to the control logic level eliminates the need for additional compensating circuitry and keeps the RC load low.
Solution Approach 2:
The patent replaces the hardware-based feedback reversed compensating circuit with a computational approach in the timing controller. The timing controller calculates coupling capacitance compensation values using grayscale data from adjacent pixel rows and applies these compensations to the data voltages before they are sent to the pixel electrodes. This substitution of hardware compensation with computational compensation reduces the RC load and allows sufficient compensating charges even when the horizontal period is short.
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 effectively compensates for coupling capacitance, preventing display quality deterioration and ensuring proper pixel recharge, thereby enhancing the overall display performance by maintaining accurate grayscale and reducing issues like reddishness and crosstalk.
Implementation Method 1
a liquid crystal layer disposed between the first substrate and the second substrate
Implementation Method 2
a coupling capacitance is generated between the pixel electrode to which the data voltage is applied and the common electrode facing the pixel electrode
Data Source
AI summary
A display apparatus includes a display panel, a timing controller, data and gate driving parts. The display panel includes first and second substrates, and a liquid crystal layer disposed between the first and second substrates, and displays an image. The timing controller includes a data compensating unit that outputs compensated grayscale data in an n-th pixel row, based upon a coupling capacitance generated according to a grayscale data variation between an (n−1)-th pixel row and the n-th pixel row, n′ being a natural number. The data driving part converts the compensated grayscale data to an analog data voltage, and outputs the analog data voltage to data lines.