Storage Capacitor Design for Variable Frame Frequency Flicker
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Solution Overview
Problem
Display devices with variable frame frequencies experience flickers due to changes in luminance when the frame frequency varies, leading to reduced display quality.
Innovation Solution
A display device with a storage capacitor that adjusts its capacitance based on the difference between maximum and minimum frame frequencies, and a storage voltage greater than the common voltage by more than a predetermined level, to maintain consistent pixel voltage and prevent flickers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the frame frequency is varied to match rendering time, then the display device can adapt to different image types and rendering speeds, but luminance inconsistency occurs causing visible flickers
Solution Approach 1:
The storage capacitor is pre-configured with a specific capacitance value before operation to compensate for voltage leakage. By calculating the required capacitance based on the frame frequency range (using the formula CST ≥ CLC × (1/(1-G)) - CLC), the capacitor is designed in advance to maintain sufficient voltage across the entire frequency range, preventing flickers before they occur.
Solution Approach 2:
The invention changes the capacitance parameter of the storage capacitor to a specific value that is sufficient for the maximum frame frequency. This parameter adjustment ensures that the capacitor can hold enough charge to maintain pixel voltage even when the frame frequency varies, thereby maintaining luminance consistency across different operating conditions.
2Illumination intensity
If a fixed frame frequency is used, then luminance consistency is maintained, but the display device cannot adapt to variable rendering times
Solution Approach 1:
The storage capacitor is designed with sufficient capacitance in advance to handle the entire range of frame frequencies. This preliminary configuration allows the display device to maintain luminance consistency without needing to actively adjust the capacitance during operation, enabling both adaptability and consistency simultaneously.
3Productivity
If the frame frequency is lowered to match long rendering times, then processing capacity is utilized effectively, but pixel voltage leaks more causing reduced luminance
Solution Approach 1:
The storage capacitor is pre-configured with sufficient capacitance to compensate for voltage leakage during extended frame periods. By calculating the required capacitance based on the minimum frame frequency (longest frame time), the capacitor is designed to maintain adequate voltage even during long rendering intervals, preventing luminance reduction.
Solution Approach 2:
The storage capacitor acts as a voltage buffer that compensates for leakage current during long frame periods. By providing this cushioning capacitance in advance, the system maintains stable pixel voltage even when frames take longer to render, ensuring consistent luminance output.
4Speed
If the frame frequency is increased to match short rendering times, then display responsiveness is improved, but the storage capacitor discharges more causing luminance reduction
Solution Approach 1:
The storage capacitor is designed with a capacitance value optimized for the maximum frame frequency. This parameter setting ensures that even during rapid frame updates, the capacitor maintains sufficient charge to prevent voltage drops and luminance reduction, enabling high-speed operation without sacrificing brightness.
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 effectively prevents flickers and improves display quality by maintaining consistent luminance across varying frame frequencies, ensuring a stable image output.
Implementation Method 1
capacitance of the storage capacitor is set according to a difference between the maximum frame frequency and the minimum frame frequency
Data Source
AI summary
A display device includes: a switching element connected to a gate line and a data line; a liquid crystal capacitor including a pixel electrode that is connected to the switching element and a common electrode to which a common voltage is applied; and a storage capacitor including a first electrode that is connected to the switching element and a second electrode to which a storage voltage is applied. The display device is operable at a variable frame frequency between a maximum frame frequency and a minimum frame frequency. Capacitance of the storage capacitor is set according to a difference between the maximum frame frequency and the minimum frame frequency, and the storage voltage is greater than the common voltage by more than a predetermined level.