We are designing for an application where the customer needs to touch more than one touch screen simultaneously. We want to use projected capacitive for its scratch resistance but are not sure how to manage the interference problem when two screens are touched at the same time. Do you have any suggestions on how to solve this problem?

Hey Keith C.,

Two-timing touch on multiple displays is an old surface capacitive problem with a complicated solution. I am assuming you are using the same computer running a multi-display solution under windows. By now you know that multi-touch electronics send information to the multi-touch driver which converts it to the equivalent of multiple mice being connected to your computer. To create the actual touch, the driver takes the X-Y coordinate touch point to move the mouse pointer in the video RAM to the touch point and issues a click. So far, so good.

Now you are going to connect multiple displays, which are supported by the Windows system. Again, so far, so good. But here is the rub. The touch electronics have a USB name that tells the Windows driver that there is a multi-touch device out there. If you plug in two USB touch screens, the Windows driver will not know which touch screen is associated with which display, and, further, would be totally annoyed at you for trying to trick it with two devices with the same name.

For this application, Touch International can change the name of each of the two electronic controllers (so you can know which is which), but this would not make the Windows driver any more capable. So, now you have to call in the big guns and get them to sell you a multi-touch-multi-display driver. This can and has been done, but get out your wallet. Touch can give you suggestions for software companies that can do this.

Till next time, Touch Guy