Active Matrix Substrate Demultiplexer Boost Circuit Power Optimization
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Solution Overview
Problem
The challenge in active matrix substrates is to reduce drive power consumption while incorporating a demultiplexer circuit, as oxide semiconductor TFTs have lower mobility than polycrystalline silicon TFTs, requiring larger TFTs or higher drive voltages, which increase power consumption and gate capacitance.
Innovation Solution
The active matrix substrate incorporates a demultiplexer circuit with boost circuits that enhance the gate voltage of switching TFTs, using a set-and-reset unit and boost unit to efficiently distribute display signals to multiple source bus lines, reducing the need for larger TFTs or higher voltages by optimizing the drive signal timing and circuit configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If oxide semiconductor TFT is used as DEMUX circuit TFT, then fabrication process compatibility is improved, but current drive force is insufficient due to lower mobility
Solution Approach 1:
The patent changes the material parameter from conventional semiconductor to oxide semiconductor for the DEMUX TFT active layer, achieving fabrication process compatibility while accepting the mobility trade-off and compensating through circuit design optimizations
2Stability of the object's composition
If oxide semiconductor TFT is used as DEMUX circuit TFT, then material uniformity is improved, but TFT size must be increased to compensate for lower mobility
Solution Approach 1:
The patent changes the semiconductor material parameter to oxide semiconductor, which provides superior material uniformity and stability, and accepts the area increase as a necessary trade-off that is later mitigated through boost circuit implementation
3Power
If TFT size is increased to compensate for lower mobility, then current drive force is improved, but gate capacitance load increases and drive power increases
Solution Approach 1:
The patent applies preliminary action by using boost circuits to pre-charge the gate electrode to a higher voltage before the TFT needs to conduct, thereby reducing the required TFT size and gate capacitance while maintaining adequate current drive force during operation
Solution Approach 2:
The patent dynamically changes the gate voltage parameter through boost circuits, allowing the TFT to operate with lower gate capacitance by using higher instantaneous gate voltage when needed, rather than requiring permanently larger TFT size
4Power
If drive voltage is increased to compensate for lower mobility, then current drive force is improved, but drive power increases
Solution Approach 1:
The patent dynamically changes the gate voltage parameter using boost circuits that provide high voltage only when needed for signal distribution, rather than maintaining continuously high drive voltage, thereby reducing average power consumption while ensuring adequate current drive force during active operation
Data Source
AI summary
The active matrix substrate includes a demultiplexer circuit disposed in a peripheral region. Unit circuits of the demultiplexer circuit each distribute a display signal from one signal output line to n source bus lines (n: two or greater). Each unit circuit includes n branch lines and n switching TFTs configured to perform individual on/off control of electrical connections of the branch lines to the source bus lines. The demultiplexer circuit includes a plurality of boost circuits each configured to boost a voltage applied to a gate electrode of a corresponding one of the switching TFTs. Each boost circuit includes: a set-and-reset unit configured to perform set operation of pre-charging a node connected to the gate electrode and reset operation of resetting the potential of the node at different timings; and a boost unit configured to perform boost operation of boosting the potential of the node pre-charged by the set operation.