Over-voltage Protection Circuit for LCD Driving
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Solution Overview
Problem
LCD devices are vulnerable to damage due to unstable external power supplies and interference, which can cause voltage levels to exceed acceptable ranges, potentially harming the power board circuit and connected elements.
Innovation Solution
An over-voltage protection circuit is integrated into the LCD driving circuit, utilizing a voltage-dividing circuit, voltage-stabilizing circuit, and control circuit with transistors to automatically disconnect power when voltages exceed a predetermined value, ensuring safe operation within acceptable voltage ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power board circuit is connected to an external main power supply, then the LCD device can receive power output, but the circuit is vulnerable to voltage fluctuations and interference that may exceed acceptable voltage ranges
Solution Approach 1:
The protection circuit performs preliminary detection of voltage levels through the voltage-dividing circuit and voltage-stabilizing circuit before the over-voltage condition can damage the LCD device. The control circuit is prepared in advance to activate the switching element for disconnection when over-voltage is detected
Solution Approach 2:
The protection circuit acts as an intermediary between the external power supply and the LCD device. It includes intermediate components such as the voltage-dividing circuit (first resistor and second resistor), voltage-stabilizing circuit, and control circuit that mediate the voltage transmission and provide protection
2Reliability
If over-voltage protection circuit is added to the LCD driving circuit, then the device is protected from over-voltage damage, but the circuit complexity increases
Solution Approach 1:
The protection circuit is segmented into distinct functional modules: voltage-dividing circuit (first resistor and second resistor), voltage-stabilizing circuit, control circuit, and switching element. This segmentation allows each component to perform its specific function independently while maintaining overall system simplicity
Solution Approach 2:
The control circuit serves as an intermediary that processes the voltage detection signal and controls the switching element. This intermediary structure simplifies the overall design by centralizing the control logic in a dedicated circuit block rather than distributing complex protection logic throughout the entire system
Data Source
AI summary
An LCD driving circuit comprising an over-voltage protection circuit includes an input terminal to receive an input voltage, a voltage-dividing circuit, a voltage-stabilizing circuit including a voltage-stabilizing element, a control circuit, a switching element, and an output terminal. The voltage-dividing circuit provides a reference voltage according to the input voltage to the voltage-stabilizing circuit, the voltage-stabilizing circuit determines whether the voltage-stabilizing element conducts according to the reference voltage, and the control circuit controls the switching element to switch on or off according to a working stage of the voltage-stabilizing element to determine whether the output terminal outputs an output voltage.