OLED Display Panel Demultiplexer for Threshold Voltage Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing OLED displays face challenges in maintaining uniform luminance across pixels due to variations in threshold voltage of driving elements, which are exacerbated by stress over time and input image data, leading to luminance differences and reduced image quality and lifespan.
Innovation Solution
A display panel design that incorporates a demultiplexer and switch array to connect data driving circuit output terminals to data lines, using MUX switch elements to distribute data signals and REF switch elements to supply reference voltages, allowing for real-time compensation of threshold voltage variations across all pixels, ensuring uniform luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a demultiplexer is used to connect data driving circuit output terminals to data lines, then the number of output terminals is reduced, but threshold voltage sensing is incomplete and luminance uniformity deteriorates
Solution Approach 1:
The patent segments the data signal transmission by dividing data lines into two groups: first data lines connected directly to output terminals for normal data transmission, and second data lines connected through the demultiplexer for threshold voltage sensing. This segmentation allows simultaneous achievement of terminal reduction and complete threshold voltage sensing across all pixels.
Solution Approach 2:
The patent applies preliminary action by performing threshold voltage sensing on all pixels before normal data signal transmission. The sensing phase uses the demultiplexer to connect second data lines to output terminals, allowing complete threshold voltage measurement. After sensing, the system switches to normal operation mode where the demultiplexer connects to first data lines for data transmission, ensuring uniform luminance is established beforehand.
2Device complexity
If threshold voltage compensation is not performed on all pixels, then circuit operation is simpler, but luminance uniformity deteriorates
Solution Approach 1:
The patent employs dynamic switching of the demultiplexer connection state based on operation phase. During sensing phase, the demultiplexer connects output terminals to second data lines to enable threshold voltage sensing on all pixels. During normal operation phase, it connects to first data lines for data transmission. This dynamic reconfiguration allows complete compensation without permanently increasing circuit complexity.
Solution Approach 2:
The system implements periodic threshold voltage sensing by alternating between sensing phase and normal operation phase. In each frame period, a portion of time is dedicated to sensing operation where the demultiplexer redistributes connections to sense threshold voltages of all pixels, followed by normal data transmission. This periodic action ensures all pixels receive compensation while maintaining simple circuit operation during normal phases.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A display panel and an electroluminescent display using the same are disclosed. The display panel includes a first data line charged with a first data signal, a second data line charged with a second data signal, a first subpixel connected to the first data line, a second subpixel connected to the second data line, a gate line commonly connected to the first and second subpixels and simultaneously supplying a gate signal to the first and second subpixels, a demultiplexer connecting an output terminal of a data driver to the first data line using MUX switch elements and then connecting the output terminal to the second data line using the MUX switch elements, and a switch array supplying a reference voltage to the second data line when the output terminal is connected to the first data line by the demultiplexer using REF switch elements.