LED Tube Lamp Impedance Detection Circuit
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Solution Overview
Problem
Existing LED tube lamps with dual-end power supply structures face challenges in safety certification due to high risk of electric shock and leakage current, particularly in Type-B LED tube lamps, which hinder their commercialization and widespread adoption.
Innovation Solution
The development of an LED tube lamp with a power supply module that includes a rectifying circuit, filtering circuit, driving circuit, flicker suppression circuit, and installation detection circuit, which detects foreign external impedance and adjusts current flow to prevent electric shock, ensuring compliance with safety standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Type-B LED tube lamps with dual-end power supply structure are used, then energy efficiency and longevity are improved, but electric shock risk and leakage current increase
Solution Approach 1:
An installation detection circuit is introduced as an intermediary component between the power supply and LED modules. This circuit detects foreign external impedance and controls current flow through switching elements, acting as a mediator that prevents direct harmful current paths while allowing normal operation. The intermediary circuitry enables Type-B lamps to maintain their energy efficiency benefits while eliminating the electric shock hazard.
2Use of energy by moving object
If Type-B LED tube lamps with dual-end power supply structure are used, then energy efficiency and longevity are improved, but compliance with safety certification standards becomes difficult
Solution Approach 1:
The installation detection circuit performs preliminary detection of the installation environment before allowing current to flow through the LED modules. By detecting foreign external impedance in advance and controlling switching elements accordingly, the system prevents unsafe operating conditions from developing. This preliminary action ensures that the lamp only operates in certified-safe configurations, thereby achieving compliance with safety standards while maintaining energy efficiency.
3Object-affected harmful factors
If installation detection circuit is added to detect foreign external impedance, then electric shock risk is reduced, but device complexity increases
Solution Approach 1:
The installation detection circuit is designed to perform multiple functions simultaneously: it detects foreign external impedance, controls current flow through switching elements, and ensures safety certification compliance. By consolidating these functions into a single integrated circuit rather than separate components, the design reduces overall device complexity while achieving the goal of eliminating electric shock risk.
Data Source
AI summary
An LED tube lamp and an impedance detection method thereof are provided. The LED tube lamp includes a power supply module comprising an impedance detection controller, configured to perform, before the LED tube lamp being lighted up, an impedance detection to determine whether the LED tube lamp is electrically connected to a foreign external impedance in series. When the LED tube lamp is connected to the foreign external impedance in series, the impedance detection controller causes at least two transient variations to an operating current of the LED tube lamp and limits the operating current of the LED tube lamp to not exceed 5 MIU in root-mean-square (RMS), in which a duration of each transient variation does not exceed 1 millisecond when the impedance detection controller performs the impedance detection.