Shift Register Driving Circuit for Display Devices
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Solution Overview
Problem
The driving ability of thin-film transistor (TFT) manufactured circuits is limited, leading to longer propagation delay and a restricted frame rate in display devices due to the dominance of all N-type or all P-type TFTs, which restricts the performance of shift registers in display devices.
Innovation Solution
A driving circuit design incorporating shift registers with a resetting circuit, an input switch, a capacitor, and an output circuit, where the capacitor adds voltage variation from a boosting signal to the control voltage, enhancing the driving ability by optimizing the output signal timing and reducing signal propagation delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If all N-type or all P-type TFTs are used in the circuit, then the manufacturing process is simplified, but the driving ability of the switch is limited and propagation delay increases
Solution Approach 1:
The patent applies local quality by using different TFT types (N-type and P-type) in different parts of the circuit. Specifically, the first switch uses an N-type TFT while the second switch uses a P-type TFT, allowing each switch to operate in its optimal conduction state and thereby reducing overall propagation delay while maintaining manufacturing simplicity through the existing TFT process
2Ease of manufacture
If all N-type or all P-type TFTs are used in the circuit, then the manufacturing process is simplified, but the frame rate of the display device is limited
Solution Approach 1:
The patent uses different TFT types in different switches to improve frame rate. By having the first switch as N-type and the second switch as P-type, the circuit achieves better driving ability and faster signal propagation, directly enabling higher frame rates while still using the standard TFT manufacturing process
3Speed
If the boosting signal voltage variation is added to the control voltage, then the conduction rate of the output switch is improved, but the circuit complexity increases
Solution Approach 1:
The patent applies preliminary action by adding the boosting signal voltage variation to the control voltage in advance, before the switch needs to conduct. This pre-charging or pre-biasing of the control voltage ensures that when the switch is activated, it transitions to the conduction state more rapidly, improving conduction rate without requiring complex real-time control mechanisms
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The enhanced driving circuit improves the conduction rate of the output switch, reducing signal propagation delay and increasing the frame rate of display devices by effectively utilizing the voltage variation from the boosting signal.
Implementation Method 1
The capacitor is electrically connected between a boosting signal and the input switch, for adding a voltage variation of the boosting signal to the control voltage
Data Source
AI summary
A driving circuit comprises a plurality of shift register (SR). An ith SR among the plurality SR's comprises a resetting circuit, an input switch, a capacitor, and an output circuit. The resetting circuit is used for adjusting a resetting voltage according to a control voltage. The input switch is used for adjusting the control voltage according to an (i−2)th driving signal from an (i−2)th SR among the plurality of SR's, selectively. The capacitor is used for adding a voltage variation of a boosting signal to the control voltage. The output circuit is used for taking an ith input signal as an ith output signal according to the control voltage and the resetting voltage, selectively. The positive edge of the boosting voltage leads the negative edge of the ith input signal.