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LED Light Plane Multitouch Technique

LED-LP is similar to LLP in that a plane of light is created above the surface. Instead of using lasers like LLP, narrow angle LEDs are used. The LEDs are positioned just above the touch surface in order to create a plane of light. When a finger or object touches the light plane, it is illuminated and seen by a infrared camera below the surface.


Parts List

  • Clear, Flat Surface (Glass, Acrylic, Polycarbonate, Plexiglass, etc.)
  • Infrared LEDs – Placed slightly above the surface on each side to create a plane of light
  • Projection Material (Rosco Grey, Vellum, Mylar, Paper, other, etc.) – For displaying an image when using a projector
  • Infrared Camera/Modified Webcam

Video Examples



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  • Nuxtoon

    How many volt for IR LED ?

    • It depends on the LEDs you buy. It’ll be specified by the LEDs.

  • wht mean Modified Webcam?
    and how to modified the normal webcam?
    thank you ..

  • Sid

    hey if i am using 200 leds so wich type of resistor i should use?

    • You can find out by using an LED calculator http://ledcalculator.net/ or http://led.linear1.org/led.wiz

  • Remaldeep

    Hi Seth,

    Can you tell me LED’s angle used for this setup?
    I tried asking for them in a nearby shop but they provided only conventional LED’s.

    • 30 degrees or less is best for this setup.

    • Rogal_22

      What about 12 degrees? is it better than 27 degrees?

  • Roy

    Hello Seth,

    if i change the location and angle of the ir cam would the LLP technique still funtion? an example would be if i was to place the camera paralel to the surface instead of below it thank you

    • Probably not because the camera wouldn’t see the surface.