DC/AC Inverter Substrate Voltage Abnormality Detector Circuit
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Solution Overview
Problem
Existing DC/AC inverter substrates for liquid crystal display devices lack effective detection of voltage abnormalities caused by corona or arc discharges at the low voltage side of the lamp, leading to potential damage and inefficiencies in downsizing the printed circuit board due to restrictive pattern arrangements and vulnerability to abnormal voltages.
Innovation Solution
A DC/AC inverter substrate with a voltage abnormality detector circuit that includes high and low voltage side detection sensors disposed near the transformer and lamp connection points without direct electrical connection, allowing for independent detection and prevention of abnormal voltage without damaging the detection circuit, and optionally incorporating a current-degradation detector for comprehensive monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If detection sensors are directly electrically connected to the secondary side of the transformer, then the detection circuit can directly monitor voltage, but the detection circuit becomes vulnerable to damage from abnormal high voltage during corona or arc discharge
Solution Approach 1:
The patent introduces an intermediary coupling mechanism between the detection sensor and the high voltage secondary side. The sensor is positioned to detect voltage through electromagnetic coupling or capacitive coupling rather than direct electrical connection, allowing voltage monitoring while isolating the detection circuit from damaging high voltage spikes during corona or arc discharge events
Solution Approach 2:
The detection circuit creates a copy or replica of the voltage signal through non-contact means. By using a sensor that couples electromagnetically or capacitively to the secondary side wiring, the circuit obtains an accurate voltage representation without the sensor being directly exposed to the harsh high voltage environment
2Area of stationary object
If the printed circuit board is downsized, then the device becomes more compact, but the arrangement of detection patterns becomes restrictive and direct electrical connection becomes more difficult
Solution Approach 1:
The patent replaces the mechanical/electrical connection system with an electromagnetic or capacitive coupling system. Instead of requiring direct physical contact and complex trace routing between sensors and high voltage points, the solution uses field-based sensing that can be implemented with simpler, more flexible patterns on compact circuit boards
Solution Approach 2:
The patent transitions from planar two-dimensional pattern arrangement to utilizing three-dimensional spatial positioning and field distribution. By positioning sensors in proximity to high voltage points and using electromagnetic coupling, the design achieves effective voltage detection on downsized boards without requiring complex multi-layer trace routing
3Measurement precision
If the detection sensor is positioned close to the secondary side wiring, then voltage abnormality detection sensitivity increases, but the sensor becomes vulnerable to damage from abnormal voltage
Solution Approach 1:
The patent employs an intermediary coupling mechanism that allows the sensor to be positioned close to the secondary side wiring for high detection sensitivity while preventing direct exposure to damaging abnormal voltages. The electromagnetic or capacitive coupling acts as a protective barrier that transmits voltage information while blocking harmful voltage spikes
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
Enables stable detection of voltage abnormalities, preventing damage to the substrate and allowing for downsizing of the circuit board by avoiding direct overvoltage exposure to the detection sensors, while also detecting current degradation issues, thus enhancing the reliability and compactness of the inverter substrate.
Implementation Method 1
a high voltage side detection sensor which is disposed at a secondary side of the transformer without being electrically connected to the secondary side
Data Source
AI summary
A DC/AC inverter substrate includes a voltage abnormality detector circuit. All of a high voltage side detection sensor, a low voltage side detection sensor, and a high-voltage and low-voltage detection sensor in the voltage abnormality detector circuit are disposed without being electrically connected to a secondary side of a transformer or to a connection point. Those detection sensors are not damaged since overvoltage is not applied to the voltage abnormality detector circuit when abnormal discharge occurs because the detection sensors are not electrically connected.