Electronic Safety Switch for LED Tubes Using Ballast Frequency Detection
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Solution Overview
Problem
The installation of LED tubes into lamp fixtures designed for fluorescent tubes poses a risk of electrical shock due to exposed connector pins, as existing mechanical safety switches are complex, unreliable, and difficult to implement, especially in fixtures with restricted access.
Innovation Solution
An LED lamp assembly with a safety switch control circuit that discriminates between magnetic and electronic ballast frequencies, using a normally open safety switch to prevent current flow until both ends are securely installed, and includes filament simulation circuits and rectifier circuits to manage power distribution safely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical safety switches with spring elements and moving parts are used, then safety function is provided, but reliability decreases and device complexity increases
Solution Approach 1:
The patent replaces mechanical safety switches with spring elements and moving parts with an electronic control system that uses a microcontroller, voltage detection circuits, and electronic switching components. This substitution eliminates mechanical wear and failure modes while reducing overall device complexity through integration of safety logic into the existing LED driver circuitry.
Solution Approach 2:
The patent extracts the safety switching function from a separate mechanical component and integrates it into the existing LED driver circuit board. The safety function is implemented through voltage detection circuits and electronic control elements that are part of the driver assembly, eliminating the need for separate mechanical safety switches in the endcaps.
2Reliability
If mechanical safety switches are installed in endcaps, then safety function is provided, but ease of operation worsens due to restricted access in some lamp fixtures
Solution Approach 1:
The patent removes the safety switch from the endcap location where it would be inaccessible in restricted fixtures. Instead, the safety control circuitry is integrated into the LED driver circuit board, which remains accessible during installation and maintenance, allowing the safety function to operate without requiring physical access to the switch mechanism.
Solution Approach 2:
The patent uses the LED driver circuit board as an intermediary to implement the safety function. The driver board detects voltage conditions and controls power delivery through electronic means, providing the safety function without requiring a physically accessible mechanical switch in the endcap.
3Ease of manufacture
If exposed connector pins are used for electrical connection, then ease of manufacture improves, but object-affected harmful factors increase due to electrical shock risk
Solution Approach 1:
The patent implements preliminary voltage detection and safety control before power is delivered to the LED tube. The control circuit monitors voltage conditions and only enables power delivery when proper installation is detected, preventing electrical shock hazards before they can occur during the installation process.
Solution Approach 2:
The patent uses feedback from voltage detection circuits to control the safety switching function. The system continuously monitors electrical conditions at the connector pins and adjusts power delivery accordingly, maintaining ease of manufacture with exposed pins while eliminating the shock hazard through active safety control.
Data Source
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AI summary
LED lamp assembly comprising a safety switch, a plurality of connector pins arranged at first and second ends of the LED lamp assembly, the connector pins being adapted for electrical connection to a lamp fixture, a plurality of filament simulation circuits, wherein at least one of the connector pins at each of the first and second ends is electrically coupled to a corresponding one of the filament simulation circuits, a plurality of rectifier circuits, one or more LEDs electrically coupled to an output of the rectifier circuits, and a safety switch control circuit operatively coupled to the safety switch. At least one of the connector pins at the first end is electrically coupled via the safety switch to an input of a first one of the rectifier circuits, and at least one of the connector pins at the second end is electrically coupled to an input of a second one of the rectifier circuits. The safety switch control circuit is arranged to close the safety switch when it detects electrical power having a frequency above a predetermined threshold at the connector pins at the first or second ends of the LED lamp assembly.