Buffer Amplifier Stabilizes EL Display Voltage
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Solution Overview
Problem
Existing organic electroluminescent (EL) display devices face issues with luminance variations due to fluctuations in supply voltages, particularly in larger screens, leading to display unevenness in the form of horizontal stripes, as the configuration of existing solutions fails to stabilize initialization and reference supply voltages applied to drive transistors and capacitors.
Innovation Solution
The organic EL display device incorporates buffer amplifier circuits in the signal drive units to stabilize the supply voltage, ensuring that the fixed voltage applied to the pixels is unaffected by line resistances, thereby reducing fluctuations and maintaining accurate threshold voltage detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the display panel is upsized, then the display area is increased, but line resistance increases causing supply voltage fluctuations
Solution Approach 1:
The power supply system is segmented into multiple independent power supply units, each serving specific regions of the display panel. This segmentation reduces the effective line resistance for each unit by limiting the current path length, thereby maintaining supply voltage stability across large display areas without requiring a single centralized power supply system.
2Length of stationary object
If the line distance is increased to connect power supply board to pixels, then the display panel can be made thinner with narrow borders, but line resistance increases causing supply voltage fluctuations
Solution Approach 1:
The power supply system is divided into multiple distributed power supply units positioned at different locations within the display panel structure. Each unit supplies power to adjacent pixel regions through shorter internal connection lines, reducing line resistance effects while maintaining the thin profile and narrow border design of the display panel.
3Reliability
If buffer amplifier circuits are added to stabilize supply voltage, then supply voltage fluctuations are suppressed, but device complexity increases
Solution Approach 1:
The buffer amplifier circuits are merged with the existing power supply unit structure, combining the voltage stabilization function with the power delivery function in integrated units. This merging approach provides supply voltage stabilization without requiring completely separate complex external circuits, thereby limiting the increase in overall device complexity while maintaining reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The implementation of buffer amplifier circuits effectively suppresses supply voltage fluctuations, leading to improved display uniformity and accurate threshold voltage detection, which reduces display unevenness and enhances the precision of light emission operations.
Implementation Method 1
the signal drive unit includes a buffer amplifier circuit which suppresses a variable component of the supply voltage carried from the power supply unit to stabilize the fixed voltage corresponding to the supply voltage
Data Source
AI summary
An organic electroluminescent display device includes: a display unit in which pixels are arranged in rows and columns, the pixels each including an organic electroluminescent element, a drive transistor, and a capacitor; a power supply unit which generates a supply voltage; a gate drive unit which applies a reference supply voltage to the capacitor; and a control unit which carries the supply voltage from the power supply unit to the gate drive unit, wherein the gate drive unit includes a buffer amplifier circuit which suppresses a variable component of the supply voltage carried via the control unit to stabilize the reference supply voltage, and supplies the stabilized reference supply voltage to the pixel.