AMOLED Driver IC Feedback Loop for Gamma Shift Compensation
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Solution Overview
Problem
AMOLED display devices experience reduced brightness levels and gamma shifts due to power line impedances, which affect the actual positive power supply voltage applied to pixel circuits, leading to unsatisfactory display quality.
Innovation Solution
An AMOLED display device with a driver IC that detects the actual positive power supply voltage and compensates data voltages by adjusting the minimum and maximum grayscale voltages, maintaining constant differences between the power supply voltage and data voltages to eliminate gamma shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If power supply voltage is applied to pixel circuits through power lines, then pixel circuits receive power for operation, but power line impedances cause voltage drops leading to gamma shifts and reduced brightness
Solution Approach 1:
The driver IC detects the actual positive power supply voltage applied to the pixel circuits through a feedback line and uses this detected voltage to compensate the data voltages, creating a closed-loop feedback system that eliminates gamma shifts caused by power line impedance
Solution Approach 2:
The invention dynamically adjusts the data voltages based on the detected actual power supply voltage, changing the voltage parameters to maintain constant difference relationships and compensate for power line impedance effects
2Ease of manufacture
If conventional pixel circuits use fixed voltage differences for driving OLED, then circuit design is simple, but actual brightness levels fall short of expected values due to voltage drops
Solution Approach 1:
A feedback line is added to allow the driver IC to detect the actual positive power supply voltage at the pixel circuits, enabling real-time compensation of data voltages to maintain expected brightness levels despite power line impedance
Solution Approach 2:
The driver IC pre-compensates the data voltages based on the detected actual power supply voltage before applying them to the pixel circuits, ensuring that the voltage differences remain constant and brightness accuracy is maintained
Data Source
AI summary
An active matrix organic light-emitting diode (AMOLED) display device and a controlling method thereof. The AMOLED display device (100) comprises a system power IC (110), a driver IC (120), an AMOLED panel (130), a power line (111) and a feedback line (112). The AMOLED panel (130) includes a plurality of pixel circuits. The system power IC (110) outputs a positive power supply voltage (ELVdd1) to the plurality of pixel circuits via the power line (111), and the driver IC (120) detects a positive power supply voltage (ELVdd2) actually applied to the plurality of pixel circuits via the feedback line (112) and compensates for data voltages (Vdata) based on the positive power supply voltage (ELVdd2) actually applied to plurality of pixel circuits. The driving chip detects the positive power supply voltage (ELVdd2) actually applied to plurality of pixel circuits, and automatically adjusts a minimum grayscale voltage (VREG1) and a maximum grayscale voltage (VGS) based on the positive power supply voltage (ELVdd2) actually applied to the plurality of pixel circuits, such that a certain difference value can be maintained between the data voltage (Vdata) and the positive power supply voltage (ELVdd2) actually applied to the plurality of pixel circuits, thus eliminating Gamma offset.