Active Matrix Substrate Demultiplexer Boost Circuits
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Solution Overview
Problem
The challenge is to reduce the driving power of an active matrix substrate with a demultiplexer circuit, as oxide semiconductor TFTs have lower current driving force compared to polycrystalline silicon TFTs, requiring larger TFTs or higher driving voltage, which increases power consumption and bezel size.
Innovation Solution
The active matrix substrate incorporates a demultiplexer circuit with boost circuits that enhance the gate voltage of switching TFTs, including a set section for pre-charging, a boost section for voltage boosting, and a reset section for potential resetting, along with an equalizer circuit for charge-sharing between nodes, allowing for reduced driving power and smaller TFT sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If oxide semiconductor TFTs are used for DEMUX circuit, then manufacturing consistency is improved, but current driving force decreases
Solution Approach 1:
The patent introduces boost circuits that dynamically change the voltage parameter applied to the gate of oxide semiconductor TFTs. By boosting the gate voltage to higher levels temporarily during switching operations, the circuit compensates for the inherently lower current driving force of oxide semiconductor TFTs, enabling them to function effectively in DEMUX applications while maintaining manufacturing consistency advantages
2Power
If TFT size is increased to compensate for lower mobility, then current driving force is improved, but gate capacitance load increases
Solution Approach 1:
Instead of increasing TFT size, the patent changes the voltage parameter by introducing boost circuits that temporarily raise the gate voltage to higher levels during switching operations. This allows smaller TFTs to achieve the necessary current driving force without incurring increased gate capacitance load, as the voltage boost provides the needed drive current while the physical dimensions remain small
3Power
If driving voltage is raised to compensate for lower mobility, then current driving force is improved, but driving power increases
Solution Approach 1:
The boost circuits operate periodically rather than continuously, providing high voltage boosts only during the brief moments when switching operations are required. This periodic action allows the circuit to achieve high current driving force when needed while keeping the average power consumption low, as the high voltage is applied only transiently during switching events rather than continuously
4Length of stationary object
If DEMUX circuit is monolithically formed, then bezel thickness is reduced, but circuit complexity increases
Solution Approach 1:
The DEMUX circuit is segmented into multiple independent unit circuits, each handling a portion of the signal distribution task. This segmentation allows the complex monolithic DEMUX to be divided into manageable modules that can be designed and fabricated using standard oxide semiconductor TFT processes, reducing the practical complexity while maintaining the thin bezel advantage of monolithic integration
Data Source
AI summary
An active matrix substrate is provided with a demultiplexer circuit. Each unit circuit of the demultiplexer circuit splits the display signal from a single signal output line to n source bus lines. Each unit circuit includes n branch lines and n switching TFTs. The demultiplexer circuit includes boost circuits configured to boost the voltage applied to the gate electrodes of the switching TFTs. Each boost circuit includes a set section that pre-charges a node connected to the gate electrode, a boost section that boosts the potential of the node pre-charged by the set section, and a reset section that resets the potential of the node. The demultiplexer circuit includes an equalizer circuit configured to perform charge sharing by electrically connecting a first node boosted by the boost section of a first boost circuit and a second node boosted by the boost section of a second boost circuit.