Add Touch Capabilities to Any Screen with a Scanner’s CCD Sensor

If you have a monitor that you’d like to repurpose into something else, allowing it to act as a touchscreen would open up all kinds of possibilities. But how would you even go about this task without a complicated vision system? Per Jean Perardel’s project, this can, in fact, be accomplished using an array of IR LEDs along with a CCD sensor recycled from a scanner.

The way it works is that the receiver sits on one side of the screen, while 24 IR LEDs transmit light from the other side one-by-one in rapid succession. Since only one light is on at a time, the receiving CCD can successively determine which part of the sensor is blocked by an object, giving its position in two dimensions.

A Teensy board is used both to control the IR LEDs, read the CCD, and calculate object position. It then sends data to a Raspberry Pi in the form of a mouse, keyboard, Python program, or serial data as needed. As setup here, it’s running on a 32” TV screen mounted in an excellent wooden frame. The triangulation method can be seen at around 0:45 in the project’s video, or keep watching till after 2:00 to see it used as a controller for The Legend of Zelda.