Shift Register Unit Transistor Lifetime Extension
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Solution Overview
Problem
Conventional pixel circuits experience transistor degradation due to prolonged periods in the OFF state, leading to abnormal operation and reduced lifespan, as transistors are switched between ON and OFF states during display, causing threshold voltage shifts.
Innovation Solution
A shift register unit with input, reset, output, pull-down, and pull-down control circuits is designed to manage transistor states, ensuring valid and invalid periods for output signals, preventing prolonged OFF states by alternating transistor states within frames, thereby extending transistor lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transistor is switched between ON and OFF states during display operation, then the pixel circuit can control data transmission, but the transistor experiences prolonged OFF states causing threshold voltage shift and degradation
Solution Approach 1:
The patent applies periodic action by introducing a frame inversion mechanism where the scan signal polarity alternates between adjacent frames. During the second time period of even frames, the scan signal is inverted compared to odd frames, causing transistors to switch between ON and OFF states periodically rather than remaining in a fixed state, thereby preventing prolonged OFF state degradation
Solution Approach 2:
The patent implements dynamics by making the transistor states dynamic through frame-by-frame inversion. The scan signal transitions from static ON/OFF states to dynamic alternating states, where transistors that were OFF in one frame become ON in the next frame, extending transistor lifespan by preventing static prolonged OFF states
2Loss of energy
If the transistor remains in OFF state for extended periods, then power consumption is reduced, but threshold voltage shifts negatively causing abnormal operation
Solution Approach 1:
The patent uses periodic action to alternate transistor states between frames. During the second time period of even frames, transistors that would normally remain OFF are switched ON through signal inversion, and vice versa for odd frames. This periodic switching prevents prolonged OFF state threshold voltage shifts while maintaining acceptable power consumption through controlled switching rather than continuous operation
3Duration of action of stationary object
If the scan signal is inverted during the second time period of even frames, then transistor lifespan is extended, but the circuit complexity increases with pull-down circuits and control mechanisms
Solution Approach 1:
The patent applies segmentation by dividing the frame into distinct time periods (first and second time periods) and further dividing the circuit into functional modules (scan signal generation unit, pull-down circuits, output circuits). This segmentation allows the inversion mechanism to be applied selectively during the second time period of even frames without affecting the entire circuit continuously, managing complexity through modular design
Solution Approach 2:
The patent implements preliminary action by pre-configuring the pull-down circuits and control logic to automatically activate during the second time period of even frames. The frame inversion control unit prepares the inverted scan signals in advance, and the pull-down circuits are positioned to immediately respond when needed, extending transistor life through pre-planned signal inversion rather than reactive modifications
Data Source
AI summary
Embodiments of the present disclosure provide a shift register unit, a driving method thereof, a gate driving circuit, and a display device. The shift register unit comprises an input circuit, a reset circuit, a plurality of output circuits, a plurality of pull-down circuits and a plurality of pull-down control circuits. During a first time period, all of signals output by the plurality of output circuits are valid. During a second time period, at least one of the signals output by the plurality of output circuits is invalid, wherein the second time period comprises a first sub-period and a second sub-period, and the state of at least one of the signals output by the plurality of output circuits during the first sub-period is opposite to the state thereof during the second sub-period. The shift register unit may enable transistors in a pixel circuit to switch between ON and OFF states, so as to extend lifetime of the transistors.