Folded U-Shaped Waveguide for NDIR Sensor Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional NDIR sensor designs face a trade-off between size reduction and accuracy, as decreasing sensor size often results in a reduced gas sample size, compromising measurement accuracy.
Innovation Solution
The enhanced gas sensor employs a folded optical waveguide configured in a 'U' shape, allowing for increased gas sampling while maintaining a reduced form factor, and includes a two-piece body assembly with recesses and cavities to enhance ventilation and optical path efficiency, thereby improving accuracy and manufacturability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of NDIR sensors is reduced, then cost and flexibility are improved, but gas sample size is reduced which compromises measurement accuracy
Solution Approach 1:
The patent applies dimensionality change by transitioning from a straight linear waveguide to a folded U-shaped waveguide configuration. This allows the optical path to extend in multiple spatial dimensions rather than a single straight line, effectively increasing the gas sampling volume within a compact sensor footprint. The folded design enables the infrared beam to traverse a longer path through the gas sample while maintaining a small overall sensor size, thus resolving the contradiction between miniaturization and measurement accuracy.
2Ease of manufacture
If the size of NDIR sensors is reduced, then manufacturing cost is reduced, but gas sample size is reduced which impacts sensor accuracy
Solution Approach 1:
The folded U-shaped waveguide design allows the sensor to achieve a longer optical path length without proportionally increasing the sensor's external dimensions or manufacturing complexity. By utilizing three-dimensional space efficiently through folding, the design maintains cost-effectiveness while improving the gas sample volume and measurement accuracy, avoiding the need for expensive alternative designs.
3Ease of manufacture
If traditional straight waveguide design is used, then manufacturing is simple, but gas sampling volume is limited reducing accuracy
Solution Approach 1:
The patent maintains manufacturing simplicity while increasing gas sample size by folding the waveguide into a U-shape rather than using complex three-dimensional structures. The folded design can be implemented using standard manufacturing processes for waveguides, adding only a geometric modification that significantly increases the optical path length and gas sampling volume without substantially complicating the manufacturing process.
Solution Approach 2:
The waveguide is segmented into multiple sections (input section, first folded section, second folded section, output section) that can be manufactured and assembled separately. This segmentation allows for modular manufacturing while achieving the extended optical path, making the complex folded geometry more manageable in terms of manufacturing and assembly processes.
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 increased accuracy and reduced manufacturing costs by allowing a larger gas sample size within a compact sensor, while maintaining efficient ventilation and optical energy transmission, thus enhancing the performance of NDIR sensors.
Implementation Method 1
NDIR sensors measure the concentration of a particular gas in a sample by determining an absorption amount of particular wavelengths of light associated with a relatively-high level absorption band of the particular gas being measured
Implementation Method 2
Due to temperature differences between the lower waveguide section including the source and the upper one including the detector, air flows by convection in the sensor
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A system includes a sensor body that has a folded optical waveguide configured in a "U" shape, wherein the waveguide is configured to convey infrared energy from one end of the waveguide to the other end of the waveguide with an infrared source at the first end of the waveguide and an infrared detector at the second end of the waveguide.