Considerations when using visualplanet touchfoil™ with LCD panels

  • The sensor should be set up with the coarse gain set as low as possible, but will still allow good positive touches. This means that there will be as low a level of noise as possible in the system.
  • The sensor always has a low level of background noise. The setup of the sensitivity and the press threshold is to allow the sensor to differentiate between background noise and true touches.
  • Sometimes the mouse will move around randomly of its own accord. This is due to spurious noise in the system and can be caused by a number of things.

Things to look for if there is too much noise in the LCD/touchfoil™ combination


  • An Air gap of 8mm or more will be required between the LCD panel and the touch sensor.
  • Where visualplanet have experience of a particular LCD we will share that information. In other cases the only way to discover the distance is by trial and error.
  • If the LCD is too close then the resulting noise interference with the touchfoil™ will result in spurious random mouse movements.
  • In all cases the earth cable provided with the touchfoil™ controller MUST be connected to the metal CASE/CHASSIS of the LCD. The whole setup should be very well grounded.
  • Ensure Laptops are connected to the mains. If the earth of the system is floating random noise may occur.
  • Mains conditions vary from one location to another. Visualplanet have had examples of touchfoil™s being on one floor in a building and being noisy, and on a different floor being perfectly OK.
  • Check the routing of the cables. Isolate the USB/Serial cable away from other cables eg. VGA, power or data cables.
  • The touchfoil™ may be too close to a power source of some kind or there may be other electronic devices nearby.
  • Try to locate the controller board away from power supplies, printers, inverters or any other electronic components in your in your unit.
  • If there is a store theft detection system nearby (RFID) then this may cause interference. It can be effectively shielded with a metal shield such as aluminium foil.
  • To check the cause of the noise try to move the touchfoil™ to another location with a known working setup (where possible) and install it there.
  • When installing the touchfoil™ to a unit located in a metal/alluminium frame please ensure the frame is grounded to avoid any unnecessary interference.
  • The store clothing tag detector near entrances causes electrical noise and can stop a touch system working if too close. A grounded metal plate between the two systems will prevent any problems.
Tags: earth, electrical, integration, interference, lcd, MA7, mouse, noise, overlay, press, sensor, setup, threshold
Last update:
Dan Spencer
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