Dual-Gate Shift Register Circuit for Display Scanning
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Solution Overview
Problem
Conventional bootstrap inverter circuits used in shift register circuits for liquid crystal and organic EL displays suffer from deteriorated transistor properties due to excessive bias voltage, leading to reduced scanning performance.
Innovation Solution
A shift register circuit design featuring p-channel transistors with two gate electrodes, distributing voltage between sources and drains to mitigate the effects of excessive bias voltage, and using thin-film transistors to simplify the fabrication process and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional bootstrap inverter circuit is used in a shift register circuit, then the circuit can drive gate lines or drain lines of liquid crystal displays or organic EL displays, but the bias voltage applied to transistors exceeds the potential difference between VDD and VSS, causing transistor property deterioration and reduced scanning performance
Solution Approach 1:
The transistor gate is divided into two separate gate electrodes (first gate electrode and second gate electrode) that are electrically connected. This segmentation allows the bias voltage to be distributed across both gate electrodes, preventing any single transistor from experiencing excessive bias voltage that would exceed the VDD-VSS potential difference, thereby protecting transistor properties while maintaining scanning performance.
Solution Approach 2:
The invention changes the electrical parameters of the transistor by introducing a dual-gate structure where the gate-to-source voltage and gate-to-drain voltage are independently controlled. By adjusting the voltage distribution across the two gate electrodes, the transistor operates within safe voltage limits while maintaining proper switching functionality in the shift register circuit.
2Adaptability or versatility
If transistors of two conductivity types are used in the shift register circuit, then the circuit functionality can be achieved, but the number of ion implantation steps and ion implantation masks increases, complicating the fabrication process and increasing costs
Solution Approach 1:
The invention uses transistors of the same conductivity type (all n-channel or all p-channel) throughout the shift register circuit, including the inverter transistors and the load transistors. This homogeneous approach eliminates the need for alternating between different conductivity types, thereby reducing the number of ion implantation steps and masks required during fabrication, simplifying the manufacturing process, and reducing costs while maintaining full circuit functionality.
Data Source
AI summary
A display capable of suppressing reduction of a scanning property is provided. This display comprises a shift register circuit formed by connecting a plurality of first circuit parts each including a first conductivity type first transistor connected to a first potential and turned on in response to a clock signal, a first conductivity type second transistor connected to a second potential and a first conductivity type third transistor, connected between the gate of the first transistor and the second potential, having two gate electrodes electrically connected with each other.