Display Device Luminance Stability Variable Refresh Rate
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Solution Overview
Problem
Display devices experience luminance differences when driving frequencies vary, leading to potential image quality degradation due to differences in blanking periods and luminance reset during frequency changes.
Innovation Solution
A display device with a timing controller that adjusts driving frequencies based on input digital video data, using a data driver to manage data voltages and sensing signals, and transistors to control light emitting elements, ensuring stable luminance by omitting luminance reset when digital video data remains unchanged, thus minimizing luminance differences between frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the driving frequency is lowered to extend the blanking period, then the blanking period length is improved, but the luminance consistency deteriorates due to differences between low frequency and high frequency luminance
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the sensing line connection state based on frequency conditions. When operating at a first (lower) driving frequency, the sensing line is connected to the initialization voltage line to perform luminance reset. When operating at a second (higher) driving frequency, the sensing line is connected to high impedance to maintain stable luminance. This frequency-based parameter adjustment resolves the luminance consistency issue while preserving the benefits of variable blanking period lengths.
Solution Approach 2:
The patent implements dynamics by making the sensing line connection state dynamic rather than fixed. The connection state changes based on the driving frequency being used, allowing the system to adapt its behavior to different operating conditions. This dynamic adjustment enables the system to optimize both blanking period length and luminance consistency depending on the current frequency setting.
2Adaptability or versatility
If frequency variable driving is performed to adapt to different video content, then the adaptability is improved, but the luminance difference between frequencies worsens
Solution Approach 1:
The patent uses parameter changes to maintain luminance consistency across different frequencies. By changing the sensing line connection parameter based on the current driving frequency, the system can perform luminance reset when needed (at lower frequencies) and maintain stable luminance when not needed (at higher frequencies), thus enabling frequency variable driving without luminance differences.
Solution Approach 2:
The patent implements feedback by using the driving frequency information to control the sensing line connection state. The system receives feedback about the current operating frequency and adjusts its behavior accordingly, ensuring that luminance reset is applied only when necessary to maintain consistent luminance across frequency transitions.
3Illumination intensity
If the sensing line is always connected to initialization voltage during data addressing, then the luminance reset is improved, but the power consumption and signal interference worsen
Solution Approach 1:
The patent applies dynamics by making the sensing line connection state conditional rather than always connected. The connection to initialization voltage occurs only during data addressing periods at specific frequencies, while at other times the sensing line is connected to high impedance. This dynamic switching reduces unnecessary power consumption and minimizes signal interference while maintaining luminance reset when required.
Solution Approach 2:
The patent uses partial action by applying luminance reset only when necessary (at lower driving frequencies during data addressing) rather than continuously. This selective application of luminance reset reduces power consumption and signal interference while still achieving the required luminance management for image quality.
Data Source
AI summary
A display device includes a display panel including a pixel including a light emitting element emitting light and electrically connected to a data line and a sensing line, a timing controller varying a driving frequency of the display panel based on an input frequency of digital video data, and a data driver supplying a data voltage to the data line based on the digital video data during a data addressing period of a frame period and receiving a sensing signal from the sensing line during a sensing period. The data driver electrically connects the sensing line to an initialization voltage line during the data addressing period in case that the digital video data is changed, and electrically connects the sensing line to a high impedance during the data addressing period in case that the digital video data is not changed.