Floating-Gate Display Transistor Threshold Compensation
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Solution Overview
Problem
Display devices face challenges due to variations in threshold voltage among transistors, leading to deviations in current flow through light-emitting elements, which can damage these elements and other transistors when high voltages are applied to compensate for these variations.
Innovation Solution
A method of manufacturing display devices that involves forming a global line layer and providing specific constant voltages to compensate for threshold voltage differences among transistors, using a floating gate electrode and control gate electrode configuration to adjust the threshold voltage without the need for additional transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high voltage is applied to compensate for threshold voltage variations, then threshold voltage compensation is improved, but the risk of damage to light-emitting elements and transistors increases
Solution Approach 1:
The patent applies preliminary action by forming a global line layer and providing specific constant voltages during the manufacturing process to compensate for threshold voltage variations before the display device is fully assembled and operational. This preliminary compensation prevents the need for high voltage applications later that could cause damage.
Solution Approach 2:
The global line layer acts as an intermediary structure that enables controlled voltage application for threshold compensation. By using this intermediate layer with specific conductive patterns, the patent achieves precise voltage distribution to compensate for threshold variations without directly applying high voltage that could damage sensitive components.
2Manufacturing precision
If additional transistors are used to compensate for threshold voltage differences, then threshold voltage control is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the global line layer to serve multiple functions simultaneously: it provides threshold voltage compensation, establishes reference potentials, and enables controlled voltage distribution across the display device. This multi-functional approach eliminates the need for additional dedicated compensation transistors.
Solution Approach 2:
The patent uses conductive patterns in the global line layer that replicate or copy the necessary electrical characteristics for threshold compensation without requiring physical copies of transistor structures. The conductive patterns emulate the voltage control function that would otherwise require additional transistors.
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
This approach effectively compensates for threshold voltage variations, reducing the risk of damage to light-emitting elements and transistors while maintaining improved threshold voltage distribution, allowing for more precise control of transistor operation.
Implementation Method 1
forming a first conductive layer including a floating gate electrode overlapping the semiconductor area on the active pattern, forming a second conductive layer including a control gate electrode overlapping the floating gate electrode on the first conductive layer
Implementation Method 2
providing a first constant voltage to the first global line, compensating for a threshold voltage of the driving transistor
Data Source
AI summary
A method of manufacturing a display device includes forming an active pattern including a semiconductor area on a substrate, forming a first conductive layer including a floating gate electrode overlapping the semiconductor area on the active pattern, forming a second conductive layer including a control gate electrode overlapping the floating gate electrode on the first conductive layer, forming a global line layer including a first global line electrically connected to the control gate electrode on the second conductive layer, providing a first constant voltage to the first global line, and removing the global line layer.