Technical Principle Of Infrared Forehead Temperature Gun

All objects whose temperature is above zero (- 273.15 ℃) are constantly emitting infrared energy into the surrounding space. Its radiation characteristics, radiation energy and wavelength distribution are closely related to the surface temperature of the object. On the other hand, by measuring the infrared energy radiated by an object, its surface temperature can be accurately measured, which is the mechanism of infrared radiation temperature measurement.

The human body, like other organisms, is radiating and releasing infrared energy around itself. Its wavelength is generally 9-13 μ m, which is in the near-infrared band of 0.76-100 μ M. Because the light in this wavelength range is not absorbed by the air, that is to say, the infrared radiation of human body has nothing to do with the environmental impact, but is related to the amount of energy contained and released by the human body. Therefore, as long as the infrared energy radiated by human body itself is measured, the surface temperature of human body can be accurately measured. The infrared temperature sensor of human body is designed and made according to this principle.

Infrared temperature sensor

According to the different materials used for energy conversion, the infrared temperature sensors on the market mainly have the following types:

(1) Pyroelectric type: triglyceride sulfate, lithium tantalate, etc

(2) Thermopile type: n-type and p-type polysilicon

(3) Diode type: single crystal or polycrystalline PN junction

(4) Thermoelectric capacity type: bimaterial film

(5) Thermistor type: vanadium oxide, amorphous silicon, etc. in fact, these types are only after receiving infrared energy, the conversion mode and material energy efficiency ratio are different.

At present, the infrared sensors used in ear and forehead temperature gun are thermopile type, and the basic physical principle is Seebeck effect.

Parameters of thermopile type temperature sensor:

Measurement range: - 50 ℃ - 100 ℃;

Measurement accuracy: within 0.1 ℃ and ± 0.1%;

Working temperature: - 20 ℃ - + 85 ℃;

Maximum measuring distance: ≤ 0-50mm (with lens 300-500mm)

Output voltage: 0-10mv;

The maximum range of thermopile temperature sensor can be from - 60 ℃ to + 1200 ℃

There are two main packaging forms of infrared thermopile sensor: TO46 (to18) / to39 (to5);

Infrared forehead temperature gun chip

The core chip of infrared temperature gun is mainly composed of ADC chip and control chip, which can realize key control, LCD display, power detection and other functions.

Working process of infrared thermometer: the infrared thermometer is composed of optical system, photoelectric detector, signal amplifier, signal processing and display output. The optical system collects the infrared radiation energy of the target in its field of view. The size of the field of view is determined by the optical parts and the position of the thermometer. The infrared radiation of the measured object first enters the optical system of the thermometer, and then the infrared ray emitted by the optical system converges to make the energy more concentrated; the accumulated infrared ray is input into the photoelectric detector, and the key component of the detector is the infrared sensor, whose task is to convert the optical signal into electrical signal; The electrical signal output from the photodetector is transformed into the temperature value of the measured target after being corrected according to the algorithm and target emissivity of the instrument through the amplifier and signal processing circuit.