OLED Pixel Threshold Voltage Sensing via Periodic Scan Signals
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Solution Overview
Problem
In organic light-emitting diode (OLED) display devices, the number of driving signals required to sense the threshold voltage of each pixel increases with the number of external clock signals, leading to increased complexity and thickness of the bezel, as well as a higher control burden for the timing controller.
Innovation Solution
A display device and method that secures sufficient time for sensing the threshold voltage of each pixel by simultaneously outputting high-level scan signals to the first and second scan signal lines, allowing for threshold voltage compensation without increasing the number of external clock signals, thereby reducing the complexity and thickness of the bezel and simplifying the gate driver circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of external clock signals is increased to sense the threshold voltage of each pixel, then the threshold voltage compensation rate increases, but the number of driving signals increases, leading to increased device complexity and bezel thickness
Solution Approach 1:
The patent applies periodic action by using scan signals that are periodically activated in specific sequences. Instead of continuously applying multiple clock signals, the system uses periodic scan signal transitions (first scan signal and second scan signal alternating at different periods) to achieve threshold voltage sensing over time, thereby reducing the number of simultaneous driving signals required.
Solution Approach 2:
The patent implements preliminary action by performing threshold voltage sensing during dedicated sensing periods before the main data input phase. The first and second scan signals are activated in advance to establish the sensing conditions, allowing the threshold voltage to be compensated before the actual pixel driving operation begins, thus avoiding the need for additional post-processing signals.
2Measurement precision
If the number of external clock signals is increased to sense the threshold voltage of each pixel, then the threshold voltage compensation rate increases, but the bezel thickness increases
Solution Approach 1:
The patent uses periodic scan signal activation to achieve threshold voltage sensing without requiring continuous high-frequency clock signals. By alternating between first and second scan signals with different periods, the system maintains sensing capability while reducing the temporal resolution requirements, which translates to reduced bezel thickness in the physical implementation.
Solution Approach 2:
The patent changes the temporal parameters of the scan signals by using different periods for the first and second scan signals. This parameter change allows the system to achieve the same threshold voltage compensation rate with fewer signal transitions, thereby reducing the physical bezel thickness required for signal routing and timing control.
3Measurement precision
If the number of external clock signals is increased to sense the threshold voltage of each pixel, then the threshold voltage compensation rate increases, but the control burden for the timing controller increases
Solution Approach 1:
The patent reduces the control burden by using periodic scan signal activation instead of continuous clock signal management. The timing controller only needs to manage the periodic transitions of the first and second scan signals rather than coordinating multiple simultaneous external clock signals, simplifying the control logic while maintaining threshold voltage compensation effectiveness.
Solution Approach 2:
The patent performs threshold voltage sensing in advance during dedicated sensing periods, allowing the timing controller to prepare compensation data before the main display operation. This preliminary action reduces the real-time control burden during pixel driving, as the threshold voltage compensation can be applied directly without requiring complex real-time adjustments.
Data Source
AI summary
Disclosed are a display device and a method for driving a pixel of the display device. The device and method is capable of securing a time to sense a threshold voltage of a driving transistor and of compensating for the threshold voltage during operation of the pixel. Each of a plurality of pixels has a 5T1C structure including first to fourth transistors and a driving transistor. The first to fourth transistors are configured to apply driving signals through first to fourth scan lines, respectively. Thus, even without increasing the number of driving signals applied to each pixel, a long time for sensing a threshold voltage of each pixel can be secured.