Low power device motion module - Sensor Selection


Thermal Sensor and Passive Infrared Sensor (PIR)

 PIR Sensor

Thermal Sensor





Figure above show Output difference between Pyro - electric Sensor and Thermal Sensor

For the temperature sensor , there will be two type of component that can be taken into consideration which is pyro - electric based sensor and MEMS IR based sensor . Referring to figure above , Pyro - electric sensor like passive infrared sensor is the most commonly use because it is low cost however it only can provide detection for moving ( dynamic ) living thing ( to be exact moving heat source ) while Omron MEMS IR Sensor can provide detection for both static living thing and dynamic movement of living thing .


Figure above show Field of View Characteristic of Thermal Sensor

Figure above shows the field of view characteristic of thermal sensor. It has around 45 degree angle of view however its sensitivity level will be decreased along with the distance . The best thing with this sensor is it able to scan temperature and give back the reading in degree Celsius value . It is also have 16 pixel of measure value as shown on the right of figure above . Due to this great capability , this sensor cost very high to be implemented in low cost product .


Figure above show Field of View Characteristic of PIR

Figure above shows the field of view characteristic of PIR . It has a wider angle compare to thermal sensor which is around 138 degree angle of view and its sensitivity level also will be decreased along with the distance . It can only detect ( dynamic ) heat source movement and only able to provide 1 bit of resolution with reference to the internal reference voltage . Its performance is not good as the thermal sensor , however it do provide low cost for low cost product .

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