Pulse Output Circuit Driver Using Microcrystalline Silicon
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Solution Overview
Problem
Thin film transistors with amorphous semiconductor channel regions face degradation issues such as increased threshold voltage and decreased field-effect mobility, leading to operational difficulties and potential failure in driver circuits, particularly in display devices.
Innovation Solution
A driver circuit design incorporating multiple pulse output circuits with specific connections and configurations of thin film transistors, including microcrystalline silicon in the channel region, to suppress degradation by managing transistor operation and reducing stress on the transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thin film transistors with amorphous semiconductor channel region are used in driver circuits, then cost is reduced and manufacturing is simplified, but transistor characteristics deteriorate over time leading to operational failure
Solution Approach 1:
The driver circuit is divided into multiple pulse output circuits (first, second, third, and fourth pulse output circuits) that operate in a staggered manner. Each circuit includes transistors that are not simultaneously conducting, thereby segmenting the operational load and reducing cumulative stress on individual transistors while maintaining overall circuit functionality
Solution Approach 2:
The pulse output circuits are configured to conduct in alternating periods during each frame period. Specifically, the first and third pulse output circuits conduct during one period while the second and fourth circuits remain non-conducting, then reverse in the next period. This periodic switching reduces the duty cycle for each transistor group, suppressing characteristic deterioration
2Reliability
If transistors are made to conduct in turn to suppress degradation, then the conduction period is shortened, but circuit complexity increases
Solution Approach 1:
Multiple pulse output circuits are combined into a single driver circuit system that shares common power supply lines (VDD, VSS) and control signal lines. The circuits use identical transistor configurations and are controlled by phased clock signals, merging functionality while maintaining individual operational independence to reduce overall complexity
Solution Approach 2:
Each pulse output circuit is designed with universal functionality using the same transistor architecture (first through fourth transistors per circuit). This standardized multi-functional design allows any of the four circuits to perform the same pulse output function at different time periods, simplifying design and maintenance while achieving reliability through redundancy
Data Source
AI summary
An object of the present invention is to suppress deterioration in the thin film transistor. A plurality of pulse output circuits each include first to eleventh thin film transistors is formed. The pulse output circuit is operated on the basis of a plurality of clock signals which control each transistor, the previous stage signal input from a pulse output circuit in the previous stage, the next stage signal input from a pulse output circuit in the next stage, and a reset signal. In addition, a microcrystalline semiconductor is used for a semiconductor layer serving as a channel region of each transistor. Therefore, degradation of characteristics of the transistor can be suppressed.