Multi-Point Gas Detector LED Array with Closed Loop Control
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Solution Overview
Problem
Current LED technology in gas detectors, specifically GaP-based LEDs, suffer from low intensity, narrow viewing angle, and unstable die materials, leading to performance and reliability issues in multi-point toxic gas monitoring systems.
Innovation Solution
A surface mount package configuration with three green LEDs, emitting at 565 nm, is used to increase viewing angle to over 100 degrees and output intensity threefold, while maintaining the same wavelength, and a closed loop control system ensures consistent radiant energy output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If GaP-based LEDs are used in gas detectors, then the device can operate with available technology, but the intensity is limited to 100 mcd and viewing angle is narrow at 20 degrees
Solution Approach 1:
The patent combines multiple LED dies (three or more) in a single package to achieve higher total intensity output. By merging multiple light sources with individual intensities of 100 mcd each, the system achieves 300 mcd or higher while maintaining the stable 565 nm wavelength characteristic of GaP technology, thus resolving the contradiction between intensity requirements and reliability.
2Illumination intensity
If multiple LED dies are coupled in parallel to increase radiant energy output, then intensity is improved, but the unstable behavior of die materials causes sudden drop and long term degradation
Solution Approach 1:
Multiple stable GaP LED dies are combined in parallel within a single package, achieving higher total intensity (300 mcd or more) while maintaining the inherent stability of GaP materials at 565 nm wavelength. The parallel configuration ensures that if one die degrades, others continue to provide stable output.
Solution Approach 2:
The patent changes the intensity parameter by combining multiple dies rather than relying on a single high-intensity LED with unstable materials. This approach maintains the stable wavelength and material composition parameters while achieving the required intensity through quantitative multiplication of stable units.
3Illumination intensity
If AlInGaP LED technology is used to achieve higher intensity, then intensity is improved, but significant efforts are required to reproduce and correlate gas concentration tables with actual gas tests taking six months to two years
Solution Approach 1:
The patent combines multiple GaP LED dies to achieve high intensity output without changing the wavelength to 565 nm, thereby avoiding the need for extensive recalibration. This approach provides both high intensity and short development time by leveraging existing, well-characterized GaP LED performance data.
4Device complexity
If a single LED is used, then the device structure is simple, but the viewing angle is limited to 20 degrees
Solution Approach 1:
Multiple LED dies are arranged in a parallel configuration within a single package, collectively providing a viewing angle of over 100 degrees. This merging approach achieves the wide viewing angle requirement while maintaining relatively simple device structure through standardized packaging.
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 enhances the reliability and performance of gas detectors by providing increased intensity and viewing angle, reducing electromagnetic interference and maintaining consistent output, thereby improving the accuracy and longevity of gas monitoring systems.
Implementation Method 1
light emitting diodes (LEDs) to provide a beam of radiant energy for the sensing function
Implementation Method 2
Members of a plurality of sources are coupled in parallel to increase radiant energy output for use in the sensing process
Data Source
AI summary
A gas detection apparatus includes a housing which carries a plurality of light emitting diodes which are coupled in parallel and which emit substantially the same wavelength of radiant energy. A closed loop control circuit maintains the radiant energy output of the diodes at substantially a predetermined value. The radiant light radiant light and a sample of a gas of interest are directed to a sensing position at which a gas responsive tape is positioned. Reflected light from the tape is detected at a sensor displaced from the tape. A light collecting element can be positioned between the coupled diodes and the sensing position.