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SENSOR CHARACTERISTICS
Interface electronic:Current Amplifier
The motion sensor in Automatic door opener uses the current amplifier as one of its interface electronic device. In this section we are going to focus on the panasonic MP motion sensor ‘NaPiOn’. These are small,high performance infrared human detection sensors with a built in amplifier. It has ultra-small design,dual lens colours,digital and analogue output with adjustable sensitivity options to allow for flexibility is applications designs.The sensors have a built in sensor element,amplifier and a comparator. The output from the sensor element has an extremely weak signal in passive infrared scheme and the signal has to be amplified and then converted to an ON/OFF signal with a comparator circuit before output. When a body with temperature different to ambient of the surrounding, moves into the detection field of the sensor,the sensor responds with a small AC signal.The signal is a small voltage around a DC signal that varies,it is therefore compulsory to cancel the DC part of the signal and amplify the AC part.
Figure 3: Rating of the Sensor
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