Gamma Voltage Regulation Circuit for AMOLED IR-Drop Compensation
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Solution Overview
Problem
In thin film transistor (TFT) pixel circuits, IR-Drop in the electroluminescent voltage drive drain (ELVDD) power supply voltage leads to current fluctuations and manufacturing deviations in Active Matrix Organic Light Emitting Diode (AMOLED) panels, affecting screen brightness and color accuracy, with current solutions requiring complex measurements and algorithms for compensation.
Innovation Solution
A gamma voltage regulation circuit and method that dynamically adjusts grayscale voltage through a driver chip, using an input circuit to detect power supply voltage, a computing circuit to calculate variations, and an adjustment circuit to output adjusted grayscale voltage, eliminating the need for screen brightness measurements and algorithm support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If screen GAMMA measurement and multiple GAMMA value adjustment is used to compensate for IR-Drop, then current fluctuations are compensated, but device complexity and measurement requirements increase
Solution Approach 1:
The gamma voltage regulation circuit autonomously monitors ELVDD voltage through the input circuit and automatically adjusts grayscale voltage through the adjustment circuit without requiring external measurement systems or complex algorithms. The system serves itself by using internal circuits to detect and compensate for voltage drops, eliminating the need for screen GAMMA measurement and multiple GAMMA value adjustments.
Solution Approach 2:
The circuit implements a feedback mechanism where the input circuit continuously monitors the ELVDD voltage level, compares it with a reference value, and uses the computing circuit to determine the voltage drop magnitude. The adjustment circuit then applies compensatory adjustment to the grayscale voltage based on this feedback, creating a closed-loop system that automatically maintains current stability without complex external measurement systems.
2Power
If ELVDD power supply voltage is used to drive pixel circuits, then power supply is provided to pixel array, but IR-Drop causes voltage fluctuation and current inconsistency
Solution Approach 1:
The adjustment circuit dynamically changes the grayscale voltage parameter based on the detected ELVDD voltage level. When voltage drop is detected, the circuit modifies the grayscale voltage to compensate for the loss, ensuring that the effective voltage driving the pixel circuits remains consistent. This parameter adjustment maintains current consistency despite power supply fluctuations.
Solution Approach 2:
The gamma voltage regulation circuit acts as an intermediary between the ELVDD power supply and the pixel arrays. It receives the power supply voltage, monitors it through the input circuit, processes the voltage drop information through the computing circuit, and outputs adjusted grayscale voltage that compensates for the drop. This intermediary function isolates the pixel circuits from direct exposure to ELVDD fluctuations.
3Ease of manufacture
If manufacturing deviations cause wiring resistance differences, then panel production is achieved, but screen brightness and color accuracy fluctuate
Solution Approach 1:
The gamma voltage regulation circuit provides localized compensation for each pixel or pixel group by adjusting grayscale voltage based on actual ELVDD conditions. Rather than requiring precise control of wiring resistance during manufacturing, the circuit adapts to local voltage conditions and applies针对性的 adjustment, allowing manufacturing variations to be compensated after production without affecting overall brightness and color accuracy.
Data Source
AI summary
A gamma voltage regulation circuit set in a driver chip of a display panel, includes: an input circuit configured to determine a measured value of a power supply voltage of a power supply; a computing circuit configured to compute a variation value between the measured value and a reference value of the power supply voltage, an adjustment circuit configured to adjust a dynamic value of a reference voltage of a grayscale voltage generated by gamma correction through the variation value; and a third output circuit configured to output the grayscale voltage based on the dynamic value.