Handheld IR Thermometer Non-Contact Measurement Aperture
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Solution Overview
Problem
Conventional clinical infrared thermometers require contact with the patient's skin for temperature measurement, leading to accuracy issues due to cooling and warming effects, and they struggle with non-uniform infrared radiance, necessitating hygienic covers and precise distance control.
Innovation Solution
A clinical hand-held IR thermometer with specially configured optics and a limiting aperture allows for non-contact temperature measurement from any distance, using a 'scan and integrate' function to account for non-uniform radiance, and features a protective shutter and LED illumination for accurate readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the thermometer contacts the patient's skin for temperature measurement, then the measurement can be taken, but the accuracy is compromised due to cooling and warming effects on the skin
Solution Approach 1:
The patent replaces the mechanical contact-based temperature measurement system with an optical/infrared-based non-contact measurement system. The infrared detector assembly captures thermal radiation from the patient's skin without physical contact, eliminating the cooling and warming effects that compromise accuracy in contact-based measurements.
Solution Approach 2:
The patent introduces an intermediary optical system including a lens and detector assembly that mediates the temperature measurement process. Instead of direct contact, the system uses infrared radiation as an intermediary to transfer thermal information from the skin to the detector, enabling accurate non-contact measurement.
2Measurement precision
If the thermometer uses a fixed aperture for measurement, then the structure is simple, but it cannot accurately measure from varying distances
Solution Approach 1:
The patent implements a dynamic optical system where the aperture size is adjusted based on the measurement distance. The aperture diameter is varied to maintain a consistent field of view and measurement accuracy across different distances, allowing the same detector to accurately measure from close range to farther distances.
Solution Approach 2:
The patent changes the physical parameter of aperture diameter dynamically during operation. By varying the aperture size according to the detected object distance, the system maintains optimal measurement conditions across a range of distances, transforming a static optical system into an adaptive one.
3Measurement precision
If the thermometer requires precise distance control for accurate measurement, then the measurement accuracy is maintained, but the ease of use is reduced
Solution Approach 1:
The patent incorporates a feedback mechanism where the system detects the distance to the measurement target and automatically adjusts the aperture size accordingly. This closed-loop control eliminates the need for manual distance control by the user, as the system self-adjusts to maintain optimal measurement conditions.
Solution Approach 2:
The optical system performs self-adjustment based on the measurement conditions. The aperture mechanism automatically varies the aperture diameter in response to distance changes, making the system self-sufficient and eliminating the need for user intervention in distance control.
4Device complexity
If the thermometer tip is exposed for measurement, then the device is simple, but hygienic protection is required when contacting the patient
Solution Approach 1:
The patent replaces the mechanical contact-based measurement system with a non-contact optical measurement system. By eliminating physical contact between the thermometer and patient skin, the system inherently prevents hygiene contamination without requiring additional protective covers or mechanisms.
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
Enables accurate and repeatable temperature measurements without contact, maintaining measurement consistency across varying distances and surface emissivity, eliminating the need for hygienic covers and reducing user effort in aiming the device.
Implementation Method 1
an infrared detector and specially configured optics... The infrared detector of the present thermometer apparatus has a defined detector sensitive area which detects infrared radiation
Implementation Method 2
Under paraxial assumption, any light ray arriving at the sensitive area of the detector is transmitted along a line which originates at the image; all the rays originating from the image pass through the limiting aperture and hit the sensitive area of the detector
Data Source
AI summary
Method and apparatus for measuring temperature of a measured area of a surface without contacting the surface. The thermometer apparatus has an optical system which generates a correlative image of an infrared energy detector sensitive area at an image distance from the thermometer. A limiting aperture, having a size and a shape corresponding to those of the generated image, is between a mirror and the generated image. The measured area of the surface is between the generated image and the thermometer in use. With such a configuration, little infrared energy that does not originate from the measured area strikes the detector. Consequently, the energy reaching the detector is limited such that the size of the measured area remains constant, regardless of changes in the thermometer's field of view attributable to differences in the distance between the surface and the thermometer. A scan-and-integrate mode for practicing the invention is disclosed.