| Electronics > Projects, Designs, and Technical Stuff |
| Proximity detection for a keyboard? |
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| 3dgeo:
Hi, I would like to hear suggestions on a simple solution how to implement proximity/hand over detection in a keyboard I'm designing. I have a steel plate under keycaps, so I was thinking about capacitive detection, but I don't know how well it would work in real world situation... Idea is to use it to turn on/off backlight, I know this could easily made by detecting key press, but I want a bit more sophisticated solution, even if it will add few bucks to the BOM. All suggestions are welcome. EDIT: This is what I'm looking for: Find on Google: "When something approaches, such as a steel disk or a hand, the impedance changes. When the impedance passes a certain threshold, the controller will know to turn on/off the backlight" (green PCB – "Santiago proximity detector"): |
| NiHaoMike:
IR LED one one side of the keyboard coupled with an IR detector on the other side. Modulate the light to make it resistant to ambient light and look for changes in IR reflectivity. There's also radar and sonar, but those are likely to cost substantially more than an IR LED and detector. PIR is another possibility. |
| 3dgeo:
Thanks for your reply, I had IR in mind, but sensors will be visible and relatively unprotected. I think I will try duplicate Logi keyboard approach. |
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