Pixel Driving Chip Compensation for OLED Uniformity
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Solution Overview
Problem
Conventional active matrix OLED display devices face challenges in achieving uniform image display due to variations in threshold voltage and voltage drop across driving transistors, leading to uncontrollable and inflexible compensation processes.
Innovation Solution
A pixel driving chip with a control circuit to generate control voltage signals for testing the driving transistor, an acquisition circuit to measure source voltage, a computation circuit to compute compensation voltage, and a compensation circuit to store and apply this voltage for flexible and controllable signal compensation, independent of normal operating signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional active matrix OLED display devices are used without compensation circuits, then device complexity is reduced, but image display uniformity deteriorates due to threshold voltage and voltage drop variations
Solution Approach 1:
The pixel driving chip is divided into functionally independent modules: control circuit for generating test signals, acquisition circuit for measuring voltages, computation circuit for calculating compensation values, and compensation circuit for applying corrections. This segmentation allows each module to perform its specific function efficiently while maintaining overall system manageability and image uniformity.
Solution Approach 2:
The system performs preliminary measurement and computation of threshold voltage and voltage drop variations during idle periods or initialization phases. By pre-calculating compensation values before normal display operation begins, the system eliminates the need for complex real-time compensation circuits while maintaining image uniformity through advance preparation.
2Manufacturing precision
If threshold voltage compensation is implemented, then image display uniformity is improved, but the compensation process becomes less flexible due to fixed compensation methods
Solution Approach 1:
The compensation system dynamically adjusts compensation values based on actual measured threshold voltages and voltage drops. The control circuit generates different test signals to drive the transistor into various states, and the computation circuit calculates appropriate compensation values in real-time, making the compensation process adaptive and flexible rather than fixed.
Solution Approach 2:
The system changes operating parameters by applying different test voltages and currents to the driving transistor during measurement. By varying these parameters and observing the transistor's response, the system accurately determines threshold voltage and voltage drop characteristics, enabling flexible compensation adapted to each pixel's specific electrical characteristics.
3Manufacturing precision
If voltage drop compensation is implemented, then image display uniformity is improved, but measurement precision requirements increase due to need for accurate voltage measurements
Solution Approach 1:
The acquisition circuit measures the actual voltage at the source electrode of the driving transistor and feeds this information back to the computation circuit. This feedback mechanism allows the system to automatically adjust compensation values based on real measured data, reducing the impact of measurement errors and maintaining image uniformity even with moderate measurement precision.
Solution Approach 2:
The pixel driving chip performs self-measurement and self-compensation by using its own internal circuits to measure threshold voltage and voltage drop variations. The chip generates test signals, measures its own electrical characteristics, calculates compensation values, and applies corrections without requiring external measurement equipment, thereby reducing measurement precision requirements while maintaining display uniformity.
Data Source
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AI summary
A pixel driving chip for compensating an original signal provided to a pixel structure including a driving transistor (T4) having a drain electrode coupled to a light-emitting device, the pixel driving chip includes a control circuit configured to generate at least one control voltage signal for controlling the driving transistor (T4); an acquisition circuit configured to acquire a measured source voltage at a source electrode of the driving transistor (T4) under control of the at least one control voltage signal; a computation circuit configured to compute a compensation voltage based on the measured source voltage; a storage circuit configured to store the compensation voltage; a compensation circuit configured to compensate the original signal provided to the driving transistor (T4) using the compensation voltage stored in the storage circuit to obtain a compensated signal; and an output circuit configured to output the compensated signal to the driving transistor (T4).