Organic EL Display Panel Driving Circuit Design
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Solution Overview
Problem
The existing thin film process limitations prevent the adoption of p-channel type thin film transistors in organic EL panels, leading to variations in driving current and light emission luminance due to differences in threshold value and mobility of n-channel type transistors, which complicates achieving stable light emission characteristics and increases manufacturing costs.
Innovation Solution
The proposed solution involves an organic EL display panel with a pixel array section driven by an active matrix system, featuring writing control line and power supply line driving sections arranged on both sides of the pixel array, using low-resistance wiring and output buffer circuits with larger channel lengths and widths to reduce waveform bluntness and resistance, ensuring consistent light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If n-channel type thin film transistors are used due to thin film process limitations, then manufacturing feasibility is improved, but variations in driving current and light emission luminance occur due to differences in threshold value and mobility
Solution Approach 1:
The patent introduces a feedback mechanism by measuring the threshold voltage and mobility of each n-channel thin film transistor and using this information to adjust the driving conditions. Specifically, the system determines compensation values based on measured transistor characteristics and applies these to correct the driving current, thereby compensating for variations caused by manufacturing process limitations and achieving uniform light emission across all pixels.
2Productivity
If pixel array size is increased to improve display area, then productivity is improved, but voltage drops and shading effects increase
Solution Approach 1:
The patent divides the large pixel array into multiple regions or groups, each with its own driving circuitry or compensation scheme. By segmenting the display into smaller manageable units, the system can independently control and compensate for voltage drops in each region, preventing the propagation of errors across the entire large display and maintaining uniform image quality throughout.
Solution Approach 2:
The patent applies local quality adjustment by tailoring the driving conditions and compensation values to the specific characteristics of different regions within the pixel array. Each region receives customized driving parameters based on its measured transistor characteristics and positional factors, ensuring that local variations in voltage drops and transistor performance are compensated appropriately to maintain overall image uniformity.
Data Source
AI summary
An EL display panel including: a pixel array section in which EL display elements whose light emission state is controlled by an active matrix driving system are arranged in a form of a matrix; a first writing control line driving section and a second writing control line driving section configured to drive each writing control line from both sides of the pixel array section; and a first power supply line driving section and a second power supply line driving section configured to drive a power supply line disposed along a direction of a horizontal line from both sides of the pixel array section, the first power supply line driving section and the second power supply line driving section being respectively arranged between the first writing control line driving section and the pixel array section and between the second writing control line driving section and the pixel array section.