LED Driver Circuit Indirect Mains Voltage Monitoring
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Solution Overview
Problem
Existing emergency lighting systems using LEDs face challenges in efficiently managing battery power and determining the state of the mains supply voltage without direct measurement, which can lead to inefficient operation and reduced battery life.
Innovation Solution
A circuit design that utilizes a flyback converter with a controllable switch and optocoupler for charging, and a switching regulator with a diode and inductor for emergency lighting, allowing indirect measurement of mains supply voltage and varying the LED current through pulse duty factor control, enabling efficient operation and monitoring of battery state without direct voltage measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LED current is kept constant to maintain consistent brightness, then illumination stability is improved, but battery power is consumed faster
Solution Approach 1:
The patent applies dynamics by making the LED current adaptive rather than constant. The control circuit dynamically adjusts the LED current based on real-time battery voltage detection, allowing the system to optimize between brightness stability and power consumption according to the current battery state.
Solution Approach 2:
The patent changes the operating parameters of the LED based on battery voltage levels. By detecting battery voltage and adjusting LED current accordingly, the system modifies electrical parameters to balance illumination requirements with available power, preventing deep discharge while maintaining acceptable brightness.
2Duration of action of stationary object
If battery power is reduced to extend battery life, then duration of action is improved, but LED brightness becomes unstable
Solution Approach 1:
The patent implements feedback control by continuously detecting battery voltage and using this information to adjust LED current. The control circuit receives feedback about the battery state and automatically modifies the LED driving current to maintain brightness stability while managing power consumption to extend battery life.
Solution Approach 2:
The system dynamically adjusts LED operating parameters based on real-time battery voltage detection. This dynamic adaptation allows the LED brightness to remain stable across varying battery conditions, preventing both over-consumption that would shorten battery life and under-performance that would compromise illumination.
3Measurement precision
If mains supply voltage is directly measured to detect emergency state, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses an intermediary approach by measuring voltage across a known impedance element (charging circuit) rather than directly measuring mains supply voltage. This indirect measurement method provides sufficient information to detect emergency states without requiring complex isolation circuits or direct high-voltage measurement capabilities.
Solution Approach 2:
The patent replaces direct electrical voltage measurement with an indirect measurement through a charging circuit. By measuring current or voltage drop across a known impedance in the charging path, the system substitutes a simpler measurement approach that avoids the complexity of direct mains voltage sensing while still enabling emergency state detection.
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
This solution allows for reliable monitoring of the mains supply state and efficient operation of LEDs with consistent brightness, even with fluctuating battery power, while extending battery life by adjusting power levels and preventing deep discharge.
Implementation Method 1
a charging circuit (3) which is connected to the mains supply voltage on the input side and, during the charging operation, permanently supplies energy to the energy storage unit (4)
Implementation Method 2
light sources in the form of light-emitting semiconductors, in particular LEDs
Data Source
Figure 1~4
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Figure 6
AI summary
The emergency lighting device (1) has a charging connection (3), which is provided with a main voltage supply (U in) for charging of the energy storage unit (4). The operating switch (5) for operating the light source. The device has a control unit (2) to monitor the state of the main voltage supply during charging operation and to activate the operation of the emergency light by identifying an emergency. The control unit determines the state of the main voltage supply by measured operating parameters of device at the output end of the charging connection.