Optical Particle Detector Using Pulsed LED Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical particle detectors are expensive, large, and heavy, and rely on high-intensity light sources that are not accessible to the public, while cheap and lightweight light sources like LEDs have insufficient light output for accurate particle differentiation.
Innovation Solution
A particle detector using a controller to operate LEDs with pulsed currents beyond their continuous current damage threshold, increasing light output and extending the lifetime of the light sources, and employing multiple LEDs with different wavelengths for accurate particle identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-intensity light sources are used to illuminate particles for accurate detection, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies parameter changes by switching from continuous to pulsed current operation mode for the LED light source. This allows the use of higher current densities (beyond continuous damage threshold) during brief illumination periods, achieving sufficient light output for particle differentiation without requiring expensive high-intensity continuous light sources. The pulsed operation mode fundamentally changes the electrical parameter profile to resolve the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent implements periodic action through pulsed current delivery to the LED, where current is applied in short bursts rather than continuously. This periodic operation allows the LED to operate at high intensity during pulses (sufficient for particle type identification) while remaining off or at low power between pulses, thereby achieving accurate measurement without the complexity and cost of continuous high-intensity illumination systems.
2Illumination intensity
If pulsed current beyond continuous damage threshold is applied to LED, then light output is increased, but light source reliability deteriorates
Solution Approach 1:
The patent resolves this contradiction through periodic pulsed operation, where the LED receives high current beyond its continuous damage threshold only during brief illumination pulses. The duty cycle is controlled such that the LED is exposed to high-stress conditions only momentarily, allowing it to deliver sufficient light output for particle detection while the majority of time it operates at low or zero power, thereby preserving reliability and extending lifetime.
Solution Approach 2:
The system performs preliminary detection of particle presence (or uses timing signals from particle flow) to trigger the pulsed current activation of the LED only when needed. This preliminary action ensures the LED is subjected to high-stress pulsed operation only during actual measurement events, minimizing cumulative stress and preserving light source reliability while achieving necessary illumination intensity during active measurement periods.
3Measurement precision
If UV LED is operated continuously to provide sufficient illumination, then measurement precision is improved, but duration of action of light source decreases
Solution Approach 1:
The patent applies periodic pulsed operation to the UV LED, delivering high-intensity illumination only during brief pulses when particles are present in the detection region. This reduces the cumulative operating time of the UV LED compared to continuous operation, thereby extending its operational lifetime while maintaining sufficient illumination intensity during active measurement periods for accurate particle identification.
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
The solution provides a lightweight, affordable, and accurate particle detector with increased light output, enabling effective differentiation of particle types using LEDs, addressing the limitations of existing detectors.
Implementation Method 1
The IR gives rise to scattering
Implementation Method 2
The UV can give rise to fluorescence
Data Source
AI summary
Presented is a device for detecting particles, comprising: a first light source positioned for illuminating particles passing through a detection region of the particle detector; a first detector positioned and adapted for detecting light signals from particles illuminated by the first light source in the detection region; a processor configured for determining a type of the particles passing through the detection region from light signals detected by the first detector; characterized in that: the particle detector further comprises: a means for detecting when particles pass through the detection region; and a controller coupled to the means and configured to operate the first light source with a first pulsed current when particles pass through the detection region thereby preserving or extending lifetime of the first light source, and wherein the first pulsed current is selected beyond a continuous current damage threshold of the first light source thereby increasing light output of the first light source.