Light Emitting Display Pixel Structure for Current Driving Capability Deviation Minimization
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Solution Overview
Problem
Current light emitting display devices face significant challenges in minimizing current driving capability deviations among driving switching elements of pixels, which affects picture quality.
Innovation Solution
The proposed light emitting display device incorporates a specific pixel structure with multiple switching elements, capacitors, and an organic light emitting diode, utilizing distinct voltage levels and signal control periods to manage threshold voltage compensation, ensuring consistent current paths and reduced parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional driving switching elements are used in pixels, then the device structure remains simple, but current driving capability deviation among pixels increases, degrading picture quality
Solution Approach 1:
The patent applies preliminary action by introducing a threshold voltage compensation period before the normal display operation. During this preliminary period, the sensing signal is activated to detect threshold voltage variations in driving switching elements, and compensation voltages are applied to compensate for these variations before actual pixel operation begins. This preliminary compensation action ensures uniform current driving capability across all pixels without affecting the overall device structure simplicity.
Solution Approach 2:
The patent implements feedback mechanisms through sensing lines and sensing signals that continuously monitor the threshold voltage of driving switching elements. The detected threshold voltage information is fed back to the control circuit, which then adjusts the compensation voltage applied to each pixel's driving switching element. This feedback loop ensures that current driving capability deviations are dynamically compensated, improving picture quality while maintaining manageable device complexity through systematic control.
2Manufacturing precision
If threshold voltage compensation is implemented, then current driving capability deviation is reduced, but the number of signal lines and control periods increases
Solution Approach 1:
The patent applies universality by designing the sensing line to serve multiple functions: it acts as a data line during normal display operation and as a sensing line during the threshold voltage compensation period. The same physical infrastructure is reused for different purposes at different times, eliminating the need for separate dedicated sensing lines. This multi-functional approach enables accurate threshold voltage compensation while avoiding an increase in the number of signal lines.
Solution Approach 2:
The patent implements periodic action by dividing the operation into distinct periods: a threshold voltage compensation period where sensing signals are activated, and a normal display period where data signals are transmitted. The sensing signal and data signal are activated at different times in a periodic manner, allowing the same signal lines to be used for both sensing and data transmission without interference. This time-division multiplexing approach enables precise compensation without increasing physical device complexity.
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 enhances picture quality by minimizing current driving capability deviations, improving threshold voltage compensation rate and range, and ensuring reliable operation across varying threshold voltages.
Implementation Method 1
an organic light emitting diode connected between the third node and a supply line for a second driving voltage
Data Source
AI summary
Disclosed is a light emitting display device capable of minimizing a current driving capability deviation among driving switching elements. The light emitting display device includes pixels each including a first TFT for supplying data voltage to a first node in response to a scan signal, a second TFT for forming a current path between first and second nodes in response to an emission control signal, a driving TFT for forming a current path between a first driving voltage supply line and a third node in accordance with a voltage level of the second node, a third TFT for supplying a reference voltage to a fourth node in response to a sensing signal, a fourth TFT for supplying an initialization voltage to the third node in response to an initialization signal, and a fifth TFT for supplying the reference voltage to the second node in response to the initialization signal.