Fire Alarm Flash Control Circuit Suppressing Inrush Current
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Solution Overview
Problem
Existing fire alarm notification devices experience repetitive inrush currents due to the flashing of LEDs or xenon lamps, which are difficult to control and result in energy inefficiencies and increased costs, often requiring current-limiting circuits to mitigate these issues.
Innovation Solution
Designing the notification device's circuit such that the residual voltage across the energy storage element remains greater than or equal to the input voltage during each flash operation, using a flash control circuit with a controlled switch element and optionally a clamping element, eliminates the need for a current-limiting circuit by controlling the switch element's operation and ensuring the residual voltage is always sufficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a current-limiting circuit is added to suppress repetitive inrush currents, then the harmful current is reduced, but the device complexity and cost increase
Solution Approach 1:
The patent removes the current-limiting circuit from the system entirely by redesigning the flash control approach. Instead of adding a separate current-limiting circuit to suppress inrush current, the invention uses the flash control circuit to manage the discharge timing and duration, thereby eliminating the need for additional current-limiting components and reducing overall circuit complexity while still controlling harmful currents
Solution Approach 2:
The energy storage element is charged to a voltage level that naturally limits the inrush current when discharging through the flash element. The system uses its own energy storage characteristics to self-regulate the current, eliminating the need for external current-limiting circuits. The flash control circuit leverages the inherent properties of the energy storage element to achieve current control without additional components
2Object-generated harmful factors
If a current-limiting circuit is added to suppress repetitive inrush currents, then the harmful current is reduced, but energy consumption increases
Solution Approach 1:
By removing the current-limiting circuit, the patent eliminates the continuous energy dissipation that would occur through current-limiting resistance. The system achieves current control through timing-based flash management rather than resistive limiting, significantly reducing energy loss while still suppressing harmful inrush currents
Solution Approach 2:
The flash control circuit operates in periodic cycles, charging the energy storage element and then discharging it through the flash element for controlled durations. This periodic operation allows the system to accumulate energy efficiently and release it in controlled bursts, minimizing energy waste compared to continuous current limiting
3Illumination intensity
If the flash element flashes continuously at high intensity, then the visual alert effectiveness is improved, but the energy storage element voltage drops below input voltage causing inrush current
Solution Approach 1:
The flash control circuit implements periodic flashing with controlled duty cycles, alternating between charging and discharging phases. During the charging phase, the energy storage element voltage is restored to above the input voltage level, preventing inrush current. During the discharging phase, the flash element operates at high intensity. This periodic operation allows both high flash intensity and prevention of inrush current
Solution Approach 2:
The flash control circuit controls the discharge duration to be partial rather than continuous, allowing the energy storage element to maintain voltage above the input level. By using less than maximum possible discharge time, the system achieves sufficient visual alert effectiveness while preventing the voltage from dropping low enough to cause inrush current
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 approach effectively suppresses repetitive inrush currents without additional circuitry, reduces energy consumption, and allows for flexible light intensity settings, simplifying the design and reducing costs while maintaining reliable flash operation.
Implementation Method 1
an energy storage element, coupled to the booster circuit and charged by the booster circuit
Implementation Method 2
at least one flash element...causing energy in the energy storage element to be applied to the at least one flash element to make it flash
Implementation Method 3
a notification device uses a xenon lamp or light-emitting diode (LED) as a flash element
Data Source
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AI summary
The present invention proposes a visual notification device in a fire-fighting system, comprising: an input end (210), a booster circuit (230, 830), an energy storage element (240), at least one flash element (260), and a flash control circuit (450), for causing energy in the energy storage element (240) to be applied to the at least one flash element (260) to make it flash; wherein at least one of the booster circuit, the at least one flash element and the flash control circuit is designed such that a residual voltage (Vr) across the energy storage element in each flash operation is greater than or equal to the input voltage (Vin). Using the notification device proposed by the present invention enables the occurrence of a repetitive inrush current to be suppressed effectively without the addition of a current-limiting circuit.