Versions Compared

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

...

The  NaPiOn motion sensor is made by  Panasonic product of  Panasonic electronics. The automatic door opener uses the Area Reflective Type.The Area Reflective Type  emits infrared rays from an LED.The sensor sens out a ray of light towards the object/human body then uses the reflected light to measure the distance and determine whether there is  a person within the given distance of the sensor. When a sensor detects a person within its circumference  of sight, it sets an output non-contact switch to ON. This type of sensor uses a series of complex embedded motion sensors with  manually operated Program activators which are push buttons and switches,safety sensors that ensures that the doors do not get in contact with the user, Entrance control system,wireless program switch and a remote control. 
 

Image Modified

                      Figure 1: Area Reflective Type Operation Principles

...

Figure 3 shows that noise is filtered by components R1 and C1,cut-off frequency of about 5 Hz. This application does not need to work at high frequency because usually we are detecting human motion. The second filter is used to cancel out the DC part of the signal, components R2 and C2 perform a high pass filter with a cut-off frequency of about  0.6 Hz. Because DC signal is not amplified,the input offset voltage of the Op-amp has no importance in this application. With a gain of just over 53, the amplification gives a signal that is higher than the noise level.


Image Modified

        Figure 4: Schematic of Second architectural stage

...

In the schematic the components R6,R7,R8 and R9 to Vcc/2 sets the Op-amp common mode which allows for greater amplification of AC signal in stage 2. A factor of 10 is used to avoid limitations  with the gain bandwidth product (GBP).

 


 

Image Modified

      Figure 5: Schematic of third architectural stage

This schematic allows the user to perform a window comparator,the signal is conditioned to a go to a micro-controller. The output of the Op-amp U3 and/or U4 is in low state when a heat source is detected. Components R6,R7,R8,R9 make up the divider bridge  which is used to set the voltage reference of these devices. When the voltage reference of U3 and U4 are within the Vcc range,thus no constraint on the common input common mode voltage,the window comparator works.

Image Modified

When the signal (Vout2) is above this reference (2.77V if Vcc=3.3V),the output of U3 is in low state-close to ground.

component U4 is used to detect when the signal is below a certain reference.In our schematic the reference is 530mV thanks to the divider bridge and the Voltage calculation is thus :

Image Modified

Image Modified

Figure 6:  NAND truth table

...