OLED Pixel Structure Simplification via Dual-Use Data Line
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Solution Overview
Problem
The existing organic light emitting display devices face challenges in simplifying the structure for sensing the threshold voltage of organic light emitting diodes (OLEDs), leading to luminance variations and image sticking phenomena due to differential deterioration of OLEDs across pixels.
Innovation Solution
The proposed organic light emitting display device incorporates a digital-to-analog converter (DAC) and a sensing unit connected to a data line, allowing for the direct acquisition of anode voltage as a sensing voltage, thereby simplifying the pixel structure and eliminating the need for additional switch elements and patterns, enabling internal compensation during the displaying period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional patterns and switch elements are added to sense OLED threshold voltage, then sensing accuracy is improved, but device complexity increases
Solution Approach 1:
The data line is designed to serve dual purposes: transmitting data voltages during the displaying period and transmitting sensing voltages during the sensing period. This eliminates the need for separate sensing lines and reduces pixel structure complexity while maintaining sensing accuracy
Solution Approach 2:
The sensing function is merged with the existing data line and DAC structure. The DAC is configured to output both data voltages and sensing voltages through the same data line, combining multiple functions into existing components rather than adding separate sensing circuits
2Device complexity
If pixel structure is simplified to reduce complexity, then device complexity is reduced, but sensing capability may be compromised
Solution Approach 1:
The system dynamically switches between displaying period and sensing period operations. During the sensing period, the DAC outputs sensing voltages and the sensing unit measures OLED characteristics. This dynamic temporal separation allows simplified structure to perform both display and sensing functions reliably without requiring complex simultaneous circuitry
3Area of stationary object
If initialization line is arranged vertically to improve layout, then area utilization is improved, but design margin is reduced
Solution Approach 1:
The initialization line is repositioned from a vertical arrangement to a horizontal arrangement, changing its spatial dimension within the pixel structure. This horizontal placement along the bottom of the pixel provides adequate design margin while still achieving effective area utilization
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 allows for efficient compensation of threshold voltage deviations in real-time, reducing luminance variations and enhancing resolution by simplifying the pixel structure and increasing design margin, facilitating high-resolution displays without additional patterns or switch elements.
Implementation Method 1
the holes passing the hole transport layer and the electrons passing the electron transport layer move to form excitons, which causes the emission layer to emit visible light
Data Source
AI summary
An organic light emitting display device can include an organic light emitting diode (OLED), a driving transistor connected to an anode electrode of the OLED, a scan transistor, a digital-to-analog converter (DAC) and a sensing unit. The scan transistor is connected the anode electrode of the OLED and a data line. The DAC supplies a data voltage for displaying to the data line in a displaying period and supplies a data voltage for sensing to the data line in a sensing period. The sensing unit obtains an anode voltage of the OLED as a sensing voltage through the data line in the sensing period.