Arc Discharge Detecting Circuit Using Coupling Capacitance
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Solution Overview
Problem
Existing arc discharge detecting circuits in LCD backlight systems are complex, difficult to detect arc discharges due to low voltage levels, and prone to false negatives, which can lead to operational issues and environmental pollution from mercury release.
Innovation Solution
A current-source type arc discharge detecting circuit with a voltage dividing part, a detecting part using loop-shaped wiring with coupling capacitance to detect high-frequency arc discharge currents, and an output part that rectifies and outputs the detection voltage, simplifying the design and improving detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage dividing part with capacitors is used to detect arc discharge, then the circuit can detect voltage changes, but the detected voltage level becomes low making arc discharge hard to detect
Solution Approach 1:
The patent replaces the conventional voltage division method using capacitors with a current detection method using a loop-shaped wiring structure. This substitution allows direct detection of arc discharge current without voltage attenuation, solving the problem of low voltage level detection.
Solution Approach 2:
The patent changes the detection parameter from voltage to current. By detecting the current flowing through the loop-shaped wiring during arc discharge, the system achieves higher detection sensitivity without the voltage loss inherent in capacitor-based voltage division circuits.
2Reliability
If arc discharge detecting circuit is connected at each of both electrodes of the fluorescent lamp, then arc discharge can be detected, but the circuit becomes complicated and includes multiple duplicated parts
Solution Approach 1:
The patent merges the detection functions for both electrodes into a single loop-shaped wiring structure. The loop configuration allows the circuit to detect arc discharge at either electrode through a unified detection path, eliminating the need for separate detection circuits at each electrode.
Solution Approach 2:
The loop-shaped wiring serves multiple functions: it acts as both the current path for the fluorescent lamp and the detection antenna for arc discharge. This multi-functional design simplifies the overall circuit structure while maintaining comprehensive arc discharge detection capability.
3Device complexity
If visual inspection is used to prevent arc discharge, then no additional circuit is needed, but arc discharge cannot be reliably detected and prevented
Solution Approach 1:
The loop-shaped wiring structure utilizes the existing current path of the fluorescent lamp circuit itself for detection purposes. The same wiring that carries the operating current also serves as the detection sensor, eliminating the need for separate inspection procedures or additional complex detection circuits.
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
Enhances the sensitivity of arc discharge detection, reduces design complexity, and prevents operational hazards by effectively blocking driving voltage when arc discharge is detected, thereby preventing further arcing and potential mercury pollution.
Implementation Method 1
detects a current corresponding to an arc discharge flowing through the voltage dividing part using a coupling capacitance generated between the loop-shaped wiring of the detecting part and a wiring of the voltage dividing part
Data Source
AI summary
An arc discharge detecting circuit includes; a voltage dividing part which divides a driving voltage provided to a light source, a detecting part which includes a loop-shaped wiring spaced apart from the voltage dividing part and which detects a current corresponding to an arc discharge flowing through the voltage dividing part using a coupling capacitance generated between the loop-shaped wiring of the detecting part and a wiring of the voltage dividing part, and an output part connected to the detecting part to output a detection voltage corresponding to the arc discharge. Accordingly, the arc discharge detecting circuit may improve a sensitivity of detecting an arc discharge as a current source type using the coupling capacitors, a design may be simplified, and manufacturing costs may be decreased.