currently i am planning a PCB that would detect objects at near proximity. The distance from sensor to object is 10mm to 20mm. Also the objects are 20mm wide and 5mm apart. So i plan to make around 25cm long PCB, whit sensors placed 25mm apart, so i will detect if there is an object at that slot or not. The object positioning is +/-few mm, so the question if i am detecting object center or edge is not really that important, i jsut ned to know if there is someting in front of that sensor. And also the sensors must be cheap as possible, since i need 340 sensor PCB (so around 3400 sensors) just for first from first costumer.
Originally i was planning to go whit LDR (or another kind of ambient light sensor whit analog/linear output), since the sensor PCB is gonna be placed in a well litt room and the MCU on main pcb would just take the value of the LDR in "direct line of light" as limit and anything under that would be treated as object detection. But then there could be other obstacles or humans in front the reference sensors and a lot of other problems.
So then i started lookign at IR photo detectors and found some nice whit emmitor and receiver in 1 small SMD package, but the price of those is around 3€ to 5€, 2x time or more of LDR or similar solution. But they do seem as a better and more professional solution, since they rely on the light that they emitt themself.
So what i am asking the community is if you guys and girls know for any sort or even particular type of sensor that would fit perfectly in my PPCB. So to recap, the sensor needs to have sensing range of 5mm to 20mm(can be max 150mm), sensor package needs to be smaller then 1cm hegiht(width doesnt matter) and it would be great if at 1000 units, the price for one would be under 1€.
Just for exmple, this is my favorite at the moment: http://si.farnell.com/broadcom-l...
Thanks in advance :D