Boost Capacitor Pixel Circuit Layout for Stable OLED Driving
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Solution Overview
Problem
Organic light emitting devices face issues with increased power consumption, reduced aperture ratio, and deteriorated reliability due to high-speed driving processes that increase current density and driving voltage, leading to transistor stains and instability.
Innovation Solution
A display device design incorporating polycrystalline silicon semiconductors for driving transistors and oxide semiconductors for other transistors, with specific electrode and initialization voltage line configurations, including overlapping initialization voltage lines and connection electrodes, to stabilize operation and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed driving process is used to increase pixel count and resolution, then productivity is improved, but reliability deteriorates due to transistor stains and instability
Solution Approach 1:
The patent changes the material parameter of the semiconductor layer from conventional material to polycrystalline silicon, which has superior electrical characteristics and stability. This material parameter change enables the transistor to withstand high-speed driving conditions without degrading, allowing increased pixel count while maintaining reliability.
Solution Approach 2:
The patent employs a composite structure combining polycrystalline silicon semiconductor layer with specific electrode materials and insulating layers. This composite material approach creates a transistor structure that is more resistant to stains and degradation under high-current-density conditions, enabling high-resolution displays with improved reliability.
2Productivity
If current density is increased to achieve high-speed driving, then productivity is improved, but harmful factors increase leading to transistor degradation
Solution Approach 1:
The patent changes the semiconductor material parameter to polycrystalline silicon, which has lower resistance and better current carrying capacity. This allows high current density to be applied for fast driving without generating harmful thermal effects or stains that would degrade the transistor.
Solution Approach 2:
The patent uses a polycrystalline silicon semiconductor layer that can withstand high current density and repeated switching cycles without degrading. This durable material replaces conventional materials that would quickly degrade under high-speed driving conditions, effectively making the transistor resistant to the harmful effects of high current density.
3Productivity
If driving voltage is increased for high-speed operation, then productivity is improved, but reliability deteriorates due to element degradation
Solution Approach 1:
The patent changes the electrical parameters of the transistor by using polycrystalline silicon semiconductor, which enables operation at higher driving voltages without breakdown. The material's superior electrical characteristics allow high-voltage driving for fast response while maintaining element reliability through optimized threshold voltage and channel conductivity.
Data Source
AI summary
A display device includes a substrate, a polycrystalline semiconductor layer including a channel of a driving transistor, and a channel of a seventh transistor, a gate electrode of the driving transistor overlapping the channel thereof, a gate electrode of the seventh transistor overlapping the channel thereof, an oxide semiconductor layer including a channel of a fourth transistor, a gate electrode thereof overlapping the channel of the fourth transistor, a first initialization voltage line connected to a first electrode of the fourth transistor, the first initialization voltage line and the gate electrode of the fourth transistor being position on a same layer, and a second initialization voltage line connected to a second electrode of the seventh transistor, the second initialization voltage line and the first initialization voltage line being positioned on different layers from each other.