I need to detect the presence of an object at the front of my PCB with a maximum distance about 10-20cm.
The behaviour would be similar to the proximity sensor found in modern touch-screen smartphones that let the OS switch off LCD backlight and touch detection when the phone is near the face during a voice call. The proximity sensor in the phone detects an object at a maximum distance of about 5cm, I need to extend the range a little.
I understood there are many types of proximity sensors, but I'm not able to decide which to choose. I need:
- low cost for 1kpcs
- small size
- it must work well in the dark
I don't need lux sensor, even if it seems some phones uses lux sensor for proximity detection.
On a sunny day (Fri, 14 Nov 2014 10:12:46 +0100) it happened pozzugno wrote in :
ebay has thousands, of different type. This one uses IR, and had 15 cm range:
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It is a kit, for 2$79 free shipping you could order one and check what chip and circuit diagram. Or just get a thousand and negotiate half the price :-)
I really do not know if this works, but is is great fun to search ebay for 'proximity sensor'.
I believe China subsidizes the shipping to expand the market. The trap with eBay and Paypal is if you want to send something back, they require a tracking number. It most likely costs more than the item is worth to ship something with a tracking number.
So consider anything you buy from China to be a one-way trip. I limit the purchases to $10.00 unless there is a very good reason to go higher. But that takes some convincing, and I often lose.
If you have a problem and can show the item is defective or does not meet their specs, some vendors will reimburse the purchase cost without requiring you to ship the item back. I give those vendors 5 stars. Others get zero and bad feedback.
Another problem that is starting to show up with American vendors is shipping everything with "Customs services and international tracking provided". An example is
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where a speed wrench is offered for $3.99, but the shipping to Canada is $25.01, which is outrageous.
The charges are paid to Pitney Bowes, who has apparently taken a lock on the market. I think their charges are rediculous and I refuse to buy anything that goes through them. Same goes for UPS.
I lived in the US for 30 years before returning to Canada. I sometimes think of moving back to the states, but then I think of Asset Seizure from the police, DHS searching anyone within 100 miles of the border, and NSA which unfortunately works with Canadian security. Then I figure it is best to stay put.
I've used one of these with reasonable success - make sure you get a decent distance ( a few cm) between the IR tx diode and the Silabs chip or else have some proper optical shielding.
If you projected a stripe pattern from one edge of the device, and received the stripe pattern from the other edge, so that the field-of-view only overlapped for objects in the 10-20 cm range, the analysis of an image for stripes (modulated at some carrier frequency, and in some not-obnoxious part of the spectrum, like infrared), would detect surfaces in the region of interest. It'd take two lenses, a driven bar display, and a linear diode array, plus some software.
As cheap in mass production as some kinds of optical mice...
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