Current-Input Pixel Precharge Circuit for Faster Signal Writing
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Solution Overview
Problem
Conventional current drive circuits for display devices face challenges in achieving fast signal write speed and element drive speed, particularly when the signal current is small, due to large parasitic capacitance in wiring, leading to slow signal write speed and voltage generation at the transistor's gate terminal.
Innovation Solution
A semiconductor device with a precharge means that sets the gate terminal potential of a transistor to a predetermined value before the set operation, using a larger current for precharge to rapidly achieve a steady state, allowing for faster completion of the set operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional current drive circuit is used with small signal current, then power consumption is reduced, but the signal write speed becomes slow due to large parasitic capacitance in wiring
Solution Approach 1:
The patent applies preliminary action by performing a precharge operation before the actual set operation. The precharge transistor charges the gate terminal of the current source transistor to a predetermined potential in advance, so that when the set operation begins, the gate terminal is already close to its target voltage. This preliminary preparation significantly reduces the time required for the current source transistor to reach its steady state, thereby improving signal write speed while maintaining low power consumption during the actual operation.
2Speed
If a larger current is used for precharge operation, then the steady state is achieved faster, but the power consumption during precharge increases
Solution Approach 1:
The patent applies periodic action by dividing the operation into distinct phases: a precharge phase where a larger current is used to quickly charge the gate terminal, followed by a set operation phase where a smaller current maintains the steady state. The precharge transistor is activated only during the precharge phase and then turned off, while the current source transistor takes over for the set operation. This time-separated approach allows high current to be used briefly for speed improvement while minimizing overall power consumption during the sustained operation phase.
Data Source
AI summary
The invention provides a semiconductor device which performs a write operation of a signal current rapidly to a current input type pixel. Before inputting a signal current, a precharge operation is performed by flowing a large current. After that, a signal current is inputted to perform the set operation. A predetermined potential can be obtained rapidly as the precharge operation is performed before the set operation. The predetermined potential is approximately equal to a potential after completing the set operation. Therefore, the set operation can be rapidly performed and a write operation of a signal current can be rapidly performed. By using two transistors, a gate width W can be long or a gate length L can be short in the precharge operation or the gate width W can be short and the gate length L can be long in the set operation.