LED Array Brightness Uniformity via Sensing Circuit Compensation
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Solution Overview
Problem
Existing LED array displays face challenges in maintaining brightness uniformity due to variations in transistor threshold voltage, LED chromaticity, voltage drops, and carrier mobility, which current internal compensation methods are unable to effectively address.
Innovation Solution
An electronic device with a first driving circuit, a processor, and a data driver that operates in a detection phase to calculate compensation values based on sensing signals, and a compensation phase where the data driver generates adjusted driving signals to compensate for brightness variations across the LED array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If internal circuitry compensation is used for LED array, then threshold voltage of transistor element can be compensated, but the range of compensation is limited and only threshold voltage can be compensated
Solution Approach 1:
A sensing circuit is introduced as an intermediary component between the LED and the compensation circuit. This sensing circuit measures the actual voltage at the LED terminal, enabling the system to compensate for multiple factors including threshold voltage, IR drop, and LED forward voltage variations, thereby expanding the compensation range beyond what internal circuitry alone can achieve.
Solution Approach 2:
The compensation system is divided into separate functional modules: a sensing circuit for measuring LED terminal voltage, a control circuit for processing the sensed data, and a compensation circuit for generating corrected drive signals. This segmentation allows each module to be optimized independently and enables comprehensive compensation for multiple error sources.
2Manufacturing precision
If internal circuitry compensation is used for LED array, then compensation can be performed, but the complexity of the compensation circuit is prone to differences due to process factors
Solution Approach 1:
The sensing circuit is integrated within the pixel circuit itself, allowing the circuit to automatically sense its own operating conditions and generate compensation signals without requiring external complex compensation circuitry. This self-service approach reduces overall circuit complexity while maintaining compensation effectiveness.
Solution Approach 2:
The sensing circuit serves multiple functions: it measures LED forward voltage, detects threshold voltage variations, and provides data for IR drop compensation. This multi-functionality eliminates the need for separate compensation circuits for each error source, thereby reducing overall circuit complexity.
3Manufacturing precision
If internal circuitry compensation is used for LED array, then compensation can be performed, but there is no way to know which pixel circuit has an anomalous LED
Solution Approach 1:
The sensing circuit provides real-time feedback on the actual voltage at each LED terminal to the control circuit. This feedback mechanism enables the system to identify anomalous pixel circuits by comparing sensed values against expected ranges, and to apply targeted compensation or flag defective pixels for replacement.
Data Source
AI summary
An electronic device including a first driving circuit, a processor, and a data driver is disclosed. The first driving circuit is configured to receive a first driving signal and generates a sensing signal. The data driver is coupled to the first driving circuit and the processor. An operation period of the electronic device includes a first detection phase and a compensation phase. The compensation phase is after the first detection phase. During the first detection phase, the data driver provides the first driving signal to the first driving circuit and receives the sensing signal from the first driving circuit. Based on the sensing signal, the processor calculates a first compensation value corresponding to the first driving circuit. In the compensation phase, the data driver generates a second driving signal based on the first compensation value and provides the second driving signal to the first driving circuit.