Based on ZTPl35S-R-type sensor thermometer design

1 Introduction

Now, people on their own physical health concern. wants to have a good body.

Temperature in the body is one of the important physiological parameters, it is very important for monitoring. The most popular electronic thermometer, thermometer is a particular non-contact infrared thermometer. At present the domestic development of infrared thermometer has the "ability of Huazhong University development: HW a 05" body temperature infrared thermal image instrument. its resolution up 0.06 ℃; the development of the Chinese Academy of Sciences, Shanghai Institute of Physics of infrared thermometer and Lanzhou University-China technology development centre development of LHW — I-infrared thermometer. Foreign products have Germany Bo lang group development of just 1 second to gauge the temperature of the infrared thermometer; Japan Omron developed several non-contact infrared thermometer and BJ40-non-contact infrared thermometer for medical use (precision ± tO.2 ℃, whose main component is an infrared temperature sensor. This article gives the application the ZTP135S — GE R type infrared temperature sensor design for thermometer.

2 infrared temperature sensor principle

Absolute zero temperature is higher than the existences (-273.15 ℃).

Because molecular thermal motion of all keep the surrounding space radiation including infrared band, electromagnetic waves. Its radiant energy density and the temperature of the object itself between the Planck (Plank) law. Infrared temperature measurement of the same principle, the principle is based on the Planck. General understanding of infrared measurements of the temperature of a body is, in fact, it is measured. objectives of the sensor or object and the difference between the environmental temperature. Objects the size of the radiation energy directly to the object's temperature. specifically, the object of the thermodynamic temperature of the 4-th power proportional to the expression using formulas to.: E = δ ε (T4-T4o) (1)

Type, E is the radiation emitting ° W/PCT unit is m3; δ is Stephen a Boltzmann constant, 5.67x10-8W/(m2 · K4); δ is the object of the radiation rate: T is the temperature of a body (K); To the objects surrounding environment temperature (K).

The main body for radiation wavelength 9 μ m-10 μ m IR. through the body's own radiation measurement of infrared energy will be able to accurately measure the surface temperature of the human body.

Because the wavelength range of the light is not absorbed by the air and, therefore, may also make use of the human body radiation infrared energy to precisely measure the surface temperature of the human body.

Infrared temperature sensor using a thermocouple measuring principle, the objectives of the sensor or object and the difference between the environmental temperature.

Principle of thermocouples are two different metal A and B form a closed loop, when the second contact end temperature while (T > To), loop generation thermoelectric Eab, where t is called hot end, end-To-end, or measure known as the cold end, open-end or reference client. A and B referred to as hot electrode. Thermoelectric power of size by contact potential (also called Burr veneer potential) and thermal EMF (also known as Thomson EMF).

3 ZTPl35S-R works and performance

GE company ZTP135S-R type infrared temperature sensor is designed for non-contact measurement of body temperature devices, the main parameters are as follows:

Chip size: 1.8 mmxl.8 mm;

Aperture size: 1.4 mm x 1.4 mm;

Electricity even: 60 pairs:

Action area: O.7 mmx0.7 ram;

Internal resistance: 60 kn ± 30%;

Temperature coefficient of resistance: the measured object's radiant energy through the window and aperture focusing in the receiving component (thermopile) heating plate, heat sink 60 only series of thermocouple thermocouple per only in hot end central parts of heating tablets in a circle, welded together, from the leader you can get all the thermoelectric couple.

This architecture has a lower thermal inertia and high sensitivity. The sensor uses the negative temperature coefficient thermal regulator for ambient temperature compensation.

4 application of infrared sensor

This design uses AVR Microcontroller for digital signal processing, and z1 "P135S — R, on its acquisition of temperature signals for processing PCT after filtering and amplifying the temperature of the standard electrical signal conversion extraction out for MD, eventually LCD monitor (LMD) displayed.

LCD: 8 data lines received .PB; control cable RS, R/W, EN respectively PD0, PDl, PD3; LCD backlight control by PD4. Buzzer control by PD5. Infrared temperature signal received MCU PA0 port, environment temperature compensation of signal received MCU PAI. Which also designed the second button (keyl, key2), keyl for system control switch, reset switch for key2.

5. concluding remarks

In temperature measurement system, temperature sensor is an important device, its performance directly affects the accuracy of the temperature measurement needs depending on the PCT measurement accuracy to select a sensor for the infrared temperature sensor, as it is a non-contact type, so the requirements of the environment is particularly high, the use of the measurement principle of thermocouples, temperature compensation on the environment, in order to get accurate measurement results.

This design uses ZTPl35S-R-type sensor is a great way to meet the requirements. Measurement of temperature change linearly and. this device with an infrared sensor just absorb infrared radiation of the human body without any human emission using x-ray. it is passive and non-contact measurement. does produce radiation injury to human beings.