do touchless faucets discriminate?

Discussion in 'General Electronics Chat' started by strantor, Jul 12, 2013.

  1. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
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    today I was installing Satan's 150 HP injection molding machine, when my bowels began making a big fuss. I made my way with haste to the nearest bathroom, covered almost up to my elbows in hydraulic fluid, black rubber dust, soot and all other manner of mechanical unholiness; my hands and arms were pitch black. I went up to a touchless faucet and it wouldn't turn on, no matter how frantically I waved my hands in front of it. So I went to the next sink, same story, on and on until I exhausted all 5 sinks. Then I assumed, since the building is brand new and still partially under construction, the water must be turned off in here, so I duck-walked all the way across the plant clutching my lower abdomen only to encounter the same thing in the other bathroom. So I gave up and did my business with dirty hand. As I sit there in the stall I hear several people come and go, washing their hands in turn. When I get out of the stall, the sink still refuses to turn over its previous booty to me. I was thinking surely there's no secret "employees only " valve to turn on these sinks.

    My thoughts turned to the faucet sensor. My assumption has alway been that these things are sonic sensors. But maybe they're light sensors, and my black hands don't reflect any, so the faucet doesn't see them. To test my theory, I rolled up my sleeve and presented my pale white elbow to her highness the Sloan faucet, and voila! It works! And after I got the first layer of dirt off, it started to work great for my hands too. I went back several times and retested the theory (one of those days, too many tacos for breakfast) and every time it wasn't until my hands were already clean that the stupid thing voluntarily washed them.

    So now I'm curious, do black people have this problem? Do you guys suffer discrimination at the hands of touchless faucets? If so, How do you get around it? Wave toiletpaper at the sink?

    So am I right about these things being light sensors? If so, how do they distinguish between a white hand and a white sink?
     
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  2. tshuck

    Well-Known Member

    Oct 18, 2012
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    First.....a little too much information...

    Second, the reflectivity of a black person's skin (thanks to oils and whatnot) is more reflective to IR than the gunk on your hands obviously was. The stuff on your hands seems to have absorbed much of the IR, enough to not register your hand.

    While I'm sure the amount of reflected IR is less than that of a white person, I don't think there is enough of a discrepancy to warrant so little IR to return to the sensor so as to not register.
     
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  3. strantor

    Thread Starter AAC Fanatic!

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    The key to the black people thing, I realized that they have pale palms. So if any black member would like to chime in, I'm curious if you have to show your palms to the faucet, especially if you have very dark skin. I'm also still curious how the faucet can distinguish between a white hand and a white sink.
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    The ir emitter and photo diode each have a defined angle of emission and incident. The sink is likely too far away to reflect the beam back to the photodiode - alignment should be wrong.
     
  5. LDC3

    Active Member

    Apr 27, 2013
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    Even though I am a Caucasian with pale skin, some sinks need to be convinced that my hands are under the faucet.
     
  6. wayneh

    Expert

    Sep 9, 2010
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    I really think the issue was the gunk. Just like the scene in Predator where Arnold covers himself with mud so the predator cannot see him in the infrared.
    Just like sunscreen but for IR.

    Gosh, I wonder if you could fool a motion detector by covering yourself with that stuff. Invisible man!
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    Slick! (no, really)
     
  8. PackratKing

    Well-Known Member

    Jul 13, 2008
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    Not exactly on topic, but what of our snipers over yonder, being subject to IR detection by the taliban, [ providing they had that kind of equipment ] How in hang is that debacle avoided. ???
     
  9. wayneh

    Expert

    Sep 9, 2010
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    Our fist reaches farther than the enemy's. To get close enough to see and shoot, they have to risk being seen and shot first. You only need a small advantage to have a large impact on outcome. I saw a simulation once that showed a 51:49 advantage would virtually guarantee a win at Wimbledon.
     
  10. Brownout

    Well-Known Member

    Jan 10, 2012
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    Aren't those faucest passive IR operated? Any mammal should be able to activate it. I very often have trouble getting the water and soap dispenser to operate correctly where I work. It can be maddening.
     
  11. tshuck

    Well-Known Member

    Oct 18, 2012
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    I didn't find many saying this, and most said nothing, but I did manage to find a Sloan brand faucet that states there is a "continuous, invisible light beam emitted" from the faucet.
     
  12. wayneh

    Expert

    Sep 9, 2010
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    Yes, according to the wiki
     
  13. strantor

    Thread Starter AAC Fanatic!

    Oct 3, 2010
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    That's the same brand, similar model that I ha issues with.
     
  14. Ron H

    AAC Fanatic!

    Apr 14, 2005
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    I have noticed that the automatic flush feature of some toilets and urinals don't work if I am wearing dark clothing. I'm assuming the same principle is involved.
     
  15. tshuck

    Well-Known Member

    Oct 18, 2012
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    ...any chance you know the model?
     
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