OLED Display Panel Compensation Using Sense Signal Lines
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Solution Overview
Problem
In OLED display panels, variations in threshold voltages and mobilities of driving transistors lead to brightness deviations among sub-pixels, reducing image quality due to differences in process conditions and driving environments, necessitating compensation for these parameters to achieve uniform display.
Innovation Solution
A display module with a source driving circuit and timing control circuit that includes sense and reference signal lines, analog-to-digital conversion sub-circuits, and pixel driving circuits with sense transistors, allowing for the extraction of sense voltage signals and compensation for driving transistor parameters, with the sense and reference signal lines arranged in parallel to minimize noise and parasitic effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional display panels without sense signal lines are used, then the device complexity is low, but the measurement precision of driving transistor parameters is insufficient leading to brightness deviations
Solution Approach 1:
The display panel is segmented by introducing sense signal lines separate from data lines, allowing independent measurement of driving transistor parameters without interfering with normal display operations. This segmentation enables precise parameter measurement while maintaining the original display function.
Solution Approach 2:
Sense signal lines are introduced as intermediary components between the driving transistor and the measurement system. These lines specifically transmit sense voltages for parameter measurement, acting as a dedicated channel that isolates measurement operations from data transmission operations.
2Measurement precision
If sense signal lines are used to measure driving transistor parameters, then the measurement precision improves, but parasitic effects and noise on signal lines affect measurement accuracy
Solution Approach 1:
Reference sense signal lines are created as copies of the sensing configuration, positioned to experience identical parasitic effects and noise environments. By copying the signal path structure, the system can differentiate between actual transistor parameters and environmental interference.
Solution Approach 2:
The system measures parameters under different conditions by comparing sense voltages from actual sense signal lines with those from reference sense signal lines. This parameter comparison approach allows extraction of true transistor characteristics by eliminating common-mode noise and parasitic effects.
3Reliability
If compensation for driving transistor parameters is implemented, then the brightness uniformity among sub-pixels improves, but the device complexity increases due to additional circuits
Solution Approach 1:
The sense signal lines are merged with the existing data line structure in terms of physical layout and routing, utilizing the same manufacturing processes and material layers. This merging approach minimizes additional device complexity while enabling parameter measurement and compensation functions.
Solution Approach 2:
The sense signal lines serve multiple functions: they transmit sense voltages for parameter measurement, provide reference signals for noise cancellation, and can be integrated with existing data transmission infrastructure. This multi-functionality reduces the need for completely separate compensation circuits.
Data Source
AI summary
A display module includes a display panel, a source driving circuit, and a timing control circuit. The display panel includes a plurality of sub-pixels, at least one sense signal line, and at least one reference sense signal line. Each sub-pixel includes a pixel driving circuit including a driving transistor. The source driving circuit includes at least one analog-to-digital conversion sub-circuit. Two input terminals of an analog-to-digital conversion sub-circuit in the at least one analog-to-digital conversion sub-circuit are respectively coupled to at least one sense signal line and one reference sense signal line. The analog-to-digital conversion sub-circuit is configured to receive a sense voltage signal from the sense signal line and a reference voltage signal from the reference sense signal line, to obtain a sensing digital signal in accordance with a voltage difference between the sense voltage signals and the reference voltage signal, and to output the sensing digital signal.