Curved IR Sensor Reflectors for Low Power Gas Detection
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Solution Overview
Problem
Existing gas sensors for measuring gas concentrations using infrared radiation face challenges with high power consumption, signal-noise ratio, and compact design limitations, particularly in automotive applications, where long absorption paths require strong IR sources and suffer from heating issues and optical adjustments.
Innovation Solution
A compact gas sensor design with an IR radiation source and detector attached to a common substrate, utilizing concave or parabolic mirrored surfaces to enlarge the effective measurement area without increasing the beam path, reducing radiation losses and power consumption, and allowing for economical manufacturing and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If long absorption paths are used to achieve high sensitivity, then measurement precision is improved, but power consumption increases and heating effects occur
Solution Approach 1:
The patent employs a curved, concave reflector surface instead of flat mirrors to focus and bundle infrared radiation. This curvature enables the radiation to be concentrated onto the detector, achieving high measurement sensitivity with a compact absorption path length, thereby reducing the required power consumption of the IR source while maintaining detection precision
Solution Approach 2:
The patent transforms the traditional linear optical path into a three-dimensional measurement volume by using the curved reflector to create multiple reflection paths and bundle radiation from different spatial dimensions onto the detector. This dimensional transformation allows adequate sensitivity without requiring excessively long absorption paths, thus reducing power consumption requirements
2Illumination intensity
If strong IR radiation sources are used to achieve adequate radiation entry into the detector, then measurement signal intensity is improved, but power consumption increases and heating effects falsify measurements
Solution Approach 1:
The curved, concave reflector surface focuses and bundles infrared radiation onto the detector, maximizing the radiation intensity received by the detector element. This focusing effect achieves adequate signal intensity without requiring high-power radiation sources, thereby reducing power consumption and minimizing heating effects that would otherwise falsify measurements
3Length of stationary object
If reflective surfaces are used to enlarge the absorption path, then measurement area is expanded, but additional costs and optical adjustments are required
Solution Approach 1:
The patent integrates the curved reflector directly into the housing structure of the gas sensor, merging the optical component with the mechanical housing. This integration eliminates the need for separate, precisely adjustable reflector assemblies, simplifying the device structure and reducing optical adjustment requirements while still achieving an enlarged effective absorption path through the curved geometry
Solution Approach 2:
The curved, concave reflector surface is designed to work with the compact housing geometry, creating an integrated optical path that enlarges the absorption path length without requiring complex external optical components or precise adjustments. The curvature is optimized to fit within the housing constraints while achieving the desired path length extension
4Volume of moving object
If compact construction with common module installation is used, then device size is reduced, but heating effects falsify measurement signals
Solution Approach 1:
The curved, concave reflector focuses infrared radiation efficiently onto the detector, maximizing the signal intensity received. This allows the use of lower-power IR sources in the compact design, thereby reducing the heating effects that would otherwise falsify measurements while maintaining the compact module construction
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 design achieves a high signal-noise ratio with low power consumption and precise, dynamic gas measurements, eliminating the need for additional optical components and adjustments, while maintaining a compact and cost-effective structure.
Implementation Method 1
the various individual gases in a gas mixture each absorb IR (infrared) radiation in specific wavelength ranges
Implementation Method 2
the various individual gases in a gas mixture each absorb IR (infrared) radiation in specific wavelength ranges
Implementation Method 3
The IR detector generally converts the received IR radiation into a thermoelectric voltage
Implementation Method 4
the measurement takes place via the mirrored areas, which according to the present invention have a concave curvature
Data Source
AI summary
A gas sensor for measuring at least one gas concentration, in particular for a vehicle climate control system, having a substrate, an IR radiation source fastened on the substrate, an IR detector fastened on the substrate, a measurement chamber for receiving a gas having the gas concentration that is to be measured, a shielding device situated in the measurement chamber between the IR radiation source and the IR detector, for shielding a direct transmission of IR radiation from the IR radiation source to the IR detector along an optical axis, and a reflective surface that has a concavely curved first mirrored area for receiving the IR radiation emitted by the IR radiation source, and that has a concavely curved second mirrored area that reflects the IR radiation to the IR detector, the measurement chamber being formed between the reflective surface and the substrate.