Discharge Circuit for LCD Gate Off Voltage Control
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Solution Overview
Problem
Conventional discharge circuits for liquid crystal displays (LCDs) face challenges in quickly discharging the gate off voltage to prevent image sticking during power failures or standby modes, as they rely on resistors that either slow down discharge or cause excessive leakage current.
Innovation Solution
A discharge circuit with a p-channel transistor and control unit that rapidly discharges the gate off voltage to ground when the external power is shut off, using a control signal to manage operation states and prevent leakage current during normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a resistor is used to discharge the gate off voltage, then the discharge path is provided, but the discharge speed becomes slow causing image sticking
Solution Approach 1:
The patent changes the discharge mechanism from passive resistor-based discharge to active transistor-controlled discharge. By using a p-channel transistor with controlled gate voltage, the discharge path resistance can be dynamically adjusted, enabling fast discharge when needed while preventing excessive leakage during normal operation.
Solution Approach 2:
The discharge circuit uses the gate off voltage signal itself to control the discharge process. When the gate off voltage drops below a threshold, it automatically triggers the transistor to discharge the voltage, creating a self-regulating system that responds to the actual voltage state without requiring external control signals.
2Loss of energy
If a resistor is used to discharge the gate off voltage, then the discharge path is provided, but excessive leakage current occurs burdening the booster circuit
Solution Approach 1:
The patent transforms the discharge element from a fixed-resistance component to a variable-resistance transistor switch. This allows the resistance to be extremely high (blocking leakage) during normal operation and extremely low (enabling discharge) when the gate off voltage needs to be discharged, eliminating the trade-off between leakage prevention and discharge capability.
Solution Approach 2:
The discharge circuit transitions from a static resistor configuration to a dynamic transistor-controlled configuration. The transistor's channel conductivity changes dynamically based on its gate voltage, allowing the circuit to adapt its resistance characteristic to the operational requirements - blocking current during normal operation and conducting current during discharge.
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 solution effectively prevents image sticking by quickly discharging the gate off voltage during power failures and reduces leakage current, ensuring faster discharge without burdening the booster circuit.
Implementation Method 1
a discharge unit connected between a first input terminal receiving the gate off voltage and a second input terminal receiving a ground voltage, and configured to discharge the gate off voltage to the ground voltage of the second input terminal in response to a control signal
Data Source
AI summary
A discharge circuit of a device including a drive circuit operating by an inputted negative voltage includes: a discharge unit connected between a first input terminal receiving the negative voltage and a second input terminal receiving a ground voltage, and configured to discharge the negative voltage to the ground voltage of the second input terminal in response to a control signal; and a control unit connected between the first input terminal and a third input terminal receiving an operation voltage corresponding to a normal operation mode and an abnormal operation mode of the drive circuit, and configured to generate the control signal in response to an operation signal for determining an operation state and a non-operation state in the normal operation mode of the drive circuit.