High-Voltage Lamp Current Detection Feedback Circuit
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Solution Overview
Problem
Conventional backlight module feedback circuits face challenges in accurately detecting lamp currents due to current diversion through capacitors and inability to handle high voltages, limiting their use with floating lamps, and often result in reduced detection accuracy and potential damage from high voltages.
Innovation Solution
A feedback circuit connected to the high-voltage end of lamps, utilizing current transformers or optical couplers for accurate current detection and a protection unit to prevent damage by disabling lamps when non-functional, allowing for flexible operation with single-drive, dual-drive, or floating lamps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the feedback circuit is connected to the low-voltage end of the lamp through ground connection, then the feedback circuit can detect lamp current, but the detection accuracy is reduced because part of the lamp current flows through the capacitor instead of all current flowing through the detection path
Solution Approach 1:
The patent introduces a current transformer as an intermediary device coupled to the high-voltage end of the lamp. The current transformer accurately detects the lamp current without being directly exposed to the high voltage, providing isolation between the high-voltage lamp circuit and the low-voltage feedback circuit while maintaining detection accuracy.
2Measurement precision
If the feedback circuit is connected to the high-voltage end of the lamp, then the detection accuracy is improved, but the feedback circuit components must withstand high voltages which is difficult for conventional resistor devices
Solution Approach 1:
The current transformer serves as an intermediary that couples to the high-voltage end of the lamp but provides galvanic isolation. This allows the feedback circuit to accurately detect lamp current while the low-voltage side components (operational amplifier, resistors) are protected from high voltage stress, maintaining both accuracy and reliability.
Solution Approach 2:
The patent replaces direct electrical connection components (resistors, operational amplifiers) that would need to withstand high voltage with a magnetic coupling system (current transformer). This substitution allows the low-voltage feedback circuit components to operate at safe voltage levels while still accurately measuring the high-voltage lamp current through magnetic induction.
3Adaptability or versatility
If conventional feedback circuits are used with single-drive lamps, then the circuit can operate, but the circuits cannot be used with floating lamps or dual-drive lamps due to inability to handle high voltages
Solution Approach 1:
The patent creates a universal feedback circuit design using a current transformer that can interface with different lamp configurations (single-drive, dual-drive, floating lamps). The current transformer provides a standardized interface that isolates the feedback circuit from voltage differences, allowing the same circuit topology to work with various lamp types while maintaining safety.
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 provides improved accuracy in lamp current detection and prevents damage to the backlight module by enabling precise feedback for adjusting driving voltages and promptly identifying non-functional lamps, ensuring stable operation across various lamp configurations.
Implementation Method 1
a current transformer coupled to the high-voltage end of the lamp for detecting a current of the lamp
Implementation Method 2
utilizing current transformers or optical couplers for accurate current detection
Data Source
AI summary
A lamp current of a lamp with at least one high-voltage end is detected using a current detector connected to the high-voltage end of the lamp. A feedback signal according to the lamp current is generated, and a drive voltage to the lamp is adjusted according to the feedback signal.