Gate Signal Line Drive Circuit Threshold Voltage Shift
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Solution Overview
Problem
In gate signal line drive circuits for liquid crystal display devices, prolonged application of on-voltage to switching elements leads to threshold voltage shift, causing instability and noise in the gate signal, which deteriorates the performance of the drive circuit.
Innovation Solution
The proposed solution involves a gate signal line drive circuit with a shift register basic circuit that applies high and low voltages during signal high and low periods, respectively, and includes additional circuits to manage voltage states during screen non-display periods, preventing prolonged high-voltage application and thus maintaining switching element stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gate line low voltage applying circuit is kept in on-state during signal low period, then the low voltage is stably applied to the gate signal line, but the threshold voltage of the switching element shifts to positive side causing noise and performance deterioration
Solution Approach 1:
The patent applies periodic action by alternating the on-state and off-state of the gate line low voltage applying circuit between signal low period and signal high period. During signal low period, the circuit is in on-state to provide stable low voltage. During signal high period, the circuit is turned off to prevent prolonged high voltage application and threshold voltage shift. This periodic switching resolves the contradiction between maintaining stable low voltage application and preventing threshold voltage drift.
2Productivity
If the switching element is kept in on-state for long period, then the gate signal line can be driven continuously, but the switching element properties deteriorate due to prolonged high voltage application
Solution Approach 1:
The patent implements periodic action by switching the gate line low voltage applying circuit between on-state and off-state based on the signal period. The circuit is turned on during signal low period for continuous drive capability, and turned off during signal high period to prevent prolonged high voltage application. This periodic operation enables continuous driving while maintaining switching element reliability.
Solution Approach 2:
The patent applies parameter changes by dynamically altering the voltage state (on-voltage or off-voltage) applied to the switching element based on the operational period. During signal low period, on-voltage is applied to enable continuous driving. During signal high period, off-voltage is applied to protect the switching element from prolonged high voltage stress. This parameter switching resolves the contradiction between continuous drive capability and element stability.
Data Source
AI summary
Provided is a gate signal line drive circuit including a shift register basic circuit for applying a high voltage for a signal high period and a low voltage for a signal low period to a gate signal line at the time of a screen display. The shift register basic circuit includes a gate line high voltage applying circuit applying a high voltage for the signal high period to the gate signal line, and a gate line low voltage applying circuit applying a low voltage to the gate signal line, wherein in the shift register basic circuit, the off-voltage is applied to the switch of the gate line low voltage applying circuit for a predetermined period at the time of a screen non-display.