Safety sensor

Discussion in 'General Electronics Chat' started by Dritech, Jan 4, 2014.

  1. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
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  2. inwo

    Well-Known Member

    Nov 7, 2013
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    I use light curtain machine sensors for safety and missing parts detection on punch presses.

    The other day I was looking at a spare machine that may be put in service soon.

    For the light curtain circuit, it had a vertical 2' fluorescent light, in a box on one side. The box cover had a row of ~7/8" holes ~2" apart.

    2' away was a similar box with holes and detectors in series.
    I don't recall the type of detectors used.

    At first look I thought it was just for illumination.

    I haven't seen the press run.
    It was fairly new compared to the 40 year old ones I'm used to.
    Lights show signs of being in service for a long time.

    I can only assume it worked for the intended purpose.
    If I work on the press, It's gone!:eek:

    ps.

    All the curtains I've seen, are not truly curtains, but closely spaced beams. Sometimes criss-crossed. sp.?
     
  3. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
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    Thanks for the reply. If I use a fluorescent light I afraid it will be affected by ambient light.

    Is there another way of making such sensor?
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,545
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    I have installed a few industrial made light curtains and they had a batch of IR emitters with receivers on the opposite side.
    They have a synchronized sequencing pattern that ripples down the curtain in order to help make them fool proof or any ambient detection.
    Max.
     
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  5. inwo

    Well-Known Member

    Nov 7, 2013
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    Any other solution would include optics and I'm no help there.:(

    If it is for safety, use a commercial product.
    The liability is huge.
    I even worry implementing the commercial product.

    I get them on Ebay for pennies on the dollar.

    Even have 1 listed. Well half of one.:D barbjb
     
  6. inwo

    Well-Known Member

    Nov 7, 2013
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    I agree.
    I don't know the specifics. It must have worked for them.
     
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