Infrared Sensor Module Light Guide Structure for Forehead Thermometer Distance Accuracy
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Solution Overview
Problem
Conventional infrared forehead thermometers face challenges in accurately measuring human body temperature due to a wide viewing angle and the need for close proximity, leading to distortion and loss of infrared energy at longer distances, which results in weak signal reception and noise interference.
Innovation Solution
The infrared sensor module incorporates a light guide structure with an annular hollow space, featuring a matte area with serration portions and a reflective area, which filters out external light and focuses infrared radiation, allowing for a longer measuring distance while maintaining signal strength by positioning the infrared sensor element at the second opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the infrared forehead thermometer is positioned far away from the human forehead, then the measuring distance is extended, but the infrared energy received by the sensor becomes too weak and is distorted by noise
Solution Approach 1:
A light guide structure is introduced as an intermediary component between the infrared sensor element and the external environment. This light guide structure includes a light guide body with specific internal geometry that guides infrared radiation from the forehead to the sensor element, enabling accurate measurement at extended distances while filtering out unwanted external light sources
Solution Approach 2:
The light guide structure incorporates different surface treatments in different regions: a matte treatment on the outer surface to diffuse and filter external light, and a reflective treatment on the inner surface to concentrate and guide infrared radiation toward the sensor element. This localized differentiation of surface properties optimizes both distance extension and measurement precision
2Measurement precision
If the infrared forehead thermometer is positioned close to the human forehead, then the infrared energy reception is strong, but the viewing angle becomes wide and includes unnecessary external light sources causing measurement distortion
Solution Approach 1:
The light guide structure incorporates different surface treatments in different regions: a matte treatment on the outer surface to diffuse and filter external light, and a reflective treatment on the inner surface to concentrate and guide infrared radiation toward the sensor element. This localized differentiation of surface properties optimizes both distance extension and measurement precision
Solution Approach 2:
A light guide structure is introduced as an intermediary component between the infrared sensor element and the external environment. This light guide structure includes a light guide body with specific internal geometry that guides infrared radiation from the forehead to the sensor element, enabling accurate measurement at extended distances while filtering out unwanted external light sources
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 enhances the accuracy of human body temperature measurement by filtering unnecessary external light and maintaining or increasing infrared energy reception, reducing noise interference and improving signal strength.
Implementation Method 1
The matte area has a plurality of serration portions, and each of the serration portions extends from the first opening to the second opening
Implementation Method 2
The reflective area is formed between the second opening and the matte area
Implementation Method 3
The infrared sensor element is disposed at the second opening
Data Source
AI summary
An infrared sensor module and a forehead thermometer are provided. The infrared sensor module includes a light guide structure and an infrared sensor element. An annular hollow space is formed inside the light guide structure and passes therethrough. A first and second opening is formed on two opposite sides of the light guide structure, respectively. A diameter of the first opening is greater than a diameter of the second opening. The annular hollow space includes a matte and reflective area, the matte area has serration portions, and each of the serration portions extends from the first opening to the second opening and is arranged parallel to each other. The reflective area is formed between the second opening and the matte area. The infrared sensor element is disposed at the second opening. The forehead thermometer includes a casing, a circuit board, the infrared sensor module, and an operating switch.