Incandescent Filament Current Limiting for LED Reliability
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Solution Overview
Problem
Lighting devices with semiconductor light sources face challenges in managing current as supply voltage increases, particularly at high operating temperatures, leading to potential overloading and inefficiencies.
Innovation Solution
Incorporating an incandescent filament as an electrical resistance element in series with the semiconductor light source, which acts as a series resistor to regulate voltage and current, and can also function as an infrared emitter or additional light source, with configurations such as parallel filaments and pulse width modulation for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an incandescent filament is added in series with the semiconductor light source, then current limiting and voltage regulation are improved, but device complexity increases
Solution Approach 1:
The incandescent filament is designed to serve multiple functions: it acts as a current-limiting resistor for the LED, provides backup lighting when the LED fails, and can function as an independent light source. This multi-functionality justifies the added complexity by delivering multiple benefits from a single component addition.
Solution Approach 2:
The patent converts the traditionally harmful effect of incandescent filaments (low energy efficiency) into a beneficial feature by using them specifically for current limiting during LED startup and operation. The filament's resistance naturally limits inrush current without requiring complex electronic circuitry, turning an inefficient technology into a useful protective element.
2Reliability
If the incandescent filament is used for current limiting at high temperatures, then the regulation range for supply voltage is increased, but energy consumption increases
Solution Approach 1:
The control unit switches between LED-only operation and combined LED-filament operation based on operating conditions. The filament is activated periodically or conditionally (such as during startup, voltage fluctuations, or LED failure) rather than continuously, reducing overall energy consumption while maintaining voltage regulation capabilities when needed.
Solution Approach 2:
The system dynamically adjusts the operating parameters of the filament (current, voltage, duty cycle) based on the required voltage regulation level and thermal conditions. By varying these parameters rather than operating at fixed high levels, the system achieves effective voltage regulation while minimizing energy consumption.
3Measurement precision
If multiple incandescent filaments are connected in parallel, then current coordination precision is improved, but device complexity increases
Solution Approach 1:
The filament system is divided into multiple independently controllable segments or filaments connected in parallel. Each filament can be controlled separately by the control unit, allowing precise adjustment of total resistance and current distribution. This segmentation enables fine-tuned current coordination while maintaining manageable complexity through modular control.
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 effectively limits current through the semiconductor light source, enhances voltage regulation, and allows for versatile lighting functions, including independent operation of the incandescent filament, while protecting the LED from overload and providing additional lighting capabilities.
Implementation Method 1
at least one electrical resistance element comprising at least one incandescent filament or embodied as an incandescent filament and connected in series with the at least one semiconductor light source
Implementation Method 2
The at least one incandescent filament of the at least one electrical resistance element serves as an electrical series resistor for the at least one semiconductor light source
Implementation Method 3
the at least one incandescent filament of the at least one electrical resistance element in accordance with one or more exemplary embodiments of the invention is embodied as an infrared emitter or as a light source
Implementation Method 4
The visible light emitted by the electrical resistance elements or incandescent filaments can have a color temperature in the range of from a few 100 kelvins (K) to a few thousand kelvins
Data Source
AI summary
A lighting device includes at least one semiconductor light source, at least one incandescent filament configured to emit electromagnetic radiation when energized, and a carrier supporting both the semiconductor light source and the incandescent filament. A screen is defined by the carrier between the semiconductor light source and the incandescent filament, so as to shield the semiconductor light source from the electromagnetic radiation emitted by the incandescent filament. The incandescent filament connected in series with the at least one semiconductor light source.