NDIR Sensor Split Sample Tube and Light Pipes
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Solution Overview
Problem
Existing non-dispersive infrared (NDIR) sensors face challenges in size due to the need for a tube to capture samples and contain IR light, leading to a size/performance tradeoff. Additionally, the IR lamp heats the sample tube, causing operational issues and potential false negative detections.
Innovation Solution
A sensor design that includes a housing with a distal end for an automotive cigarette lighter and a transceiver using IEEE 802.11 protocols to detect the proximity of smart devices. The sensor also incorporates a processor, memory, and an audio circuit to alert the user if the smart device is not present. For gas detection, the sensor uses a split sample tube design with light pipes to reduce heat transfer from the IR lamp and maintain sensor size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a tube is used to capture sample and contain IR light in NDIR sensors, then detection performance is improved, but sensor size increases
Solution Approach 1:
The patent divides the sample tube into multiple sections (first sample tube section, second sample tube section) with different functions. The first section captures the sample while the second section contains the IR light, allowing the tube to be shorter overall while maintaining detection performance. This segmentation resolves the contradiction by separating the sample capture function from the light containment function into distinct spatial zones.
Solution Approach 2:
The patent introduces light pipes to guide IR light through a folded optical path within the sample tube. By using light pipes to redirect light at angles, the effective light path length is extended without increasing the physical length of the tube, thereby maintaining detection precision while reducing sensor size.
2Use of energy by moving object
If IR lamp is placed close to sample tube for efficient light delivery, then light transmission efficiency is improved, but heat transfer to sample tube increases causing operational issues
Solution Approach 1:
The patent introduces a light pipe as an intermediary component between the IR lamp and the sample tube. The light pipe efficiently transmits IR light from the lamp to the sample tube while providing thermal isolation. This mediator allows high light transmission efficiency to be achieved without direct thermal contact between the lamp and the sample tube, resolving the contradiction between light efficiency and heat transfer.
Solution Approach 2:
The patent extracts the heat transfer function from the light delivery system by using a light pipe that transmits only light while blocking heat. The light pipe material and design are selected to be transparent to IR wavelengths while providing thermal insulation, thereby separating the light transmission function from the heat transfer function.
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 sensor effectively notifies users of the proximity of their smart devices while maintaining a compact size and reducing heat-related operational issues. The split sample tube design enhances gas detection accuracy by minimizing heat transfer and maintaining sensor efficiency.
Implementation Method 1
The IR lamp produces light which passes through a length of the tube, the CO2 gas molecules absorb the specific band of IR light
Implementation Method 2
an optical filter that absorbs every wavelength of light except the 4.2 micron wavelength absorbed by CO2 molecules
Implementation Method 3
a first light pipe section having a first end portion and a second end portion, the first end portion abutting the IR lamp and the first light pipe section passing the light through
Implementation Method 4
the second light pipe section receiving the light at the second end portion of the first sample tube section and transmitting the light from the first end portion to a second end portion
Implementation Method 5
a first filter located at the second end portion of the second sample tube section, the first filter bandpassing only a band of IR spectrum light centered on a wavelength that is indicative of the presence of a gas
Implementation Method 6
a first detector located behind to the first filter, the detector detecting the amount of IR spectrum light in the band of IR spectrum light
Data Source
AI summary
Disclosed is a sensor for detecting the proximity of smart devices previously connected to the sensor using the IEEE 802.11 protocols. Importantly, the sensor does not operate using a Bluetooth® connection, which would require the smart devices previously connected to the sensor using the IEEE 802.11 protocols to also have Bluetooth® protocols enabled. Enabling such Bluetooth® protocols uses more battery than having the IEEE 802.11 protocol adapter enabled. The sensor references a list of previously connected smart devices and attempts to connect with any in range, if none can be connected to, the sensor emits an audible alarm signal. Further, no application is required for the sensor to operate.