IR SENSORS

I'm trying to build a project using IR sensors to count the number of people entering and leaving a room. I'm using 2 sensors for this---one for counting the number of people entering and the other for counting the number of people leaving. The problem is that I cannot find a way to switch off the second beam when the first is obstructed by a person entering and vice-versa. Could someone help? Also is there any other way to do the same? Please help...

I've seen these at my local gym. They allow people to walk through in either direction, but they only allow one person at a time so that it doesn't get confused.

And they have a bank of sensors, I think. Some algorithm like, the sensors being triggered sequentially in one direction being an "enter" and the other being a "exit". With code for false triggers.

Mike

what are you using to do the counting?

if you're using a microcontroller, you could program it to shut down the unneeded sensor the moment someone crosses the active sensor

like this:

someone is entering the room and they trip the enter beam - the microcontroller records their entry and shuts down the exit beam (or leaves it running but ignores it for 100msec or something)

and vice versa ... someone breaks the exit beam on their way out and the mcu ignores the enter beam for a short instant

I'd need to see a schematic of how you have this wired up, but you should be able to stick a few transistors in there so each beam controlls the other beams emitter