I am working on project that requires me to detect the position of a pen on a piece of normal paper.
My first thought was to use 4 IR LEDs on a receiving unit set at the top of the page, and to put a camera on the pen to triangulate the position.
However I have come across some problems with this. The first being that I do not know of any sensor that is an "infrared camera" that I could buy commercially. The second problem I have run into is that the pen can be oriented in any direction, and no camera would be able to detect the IR in every direction.
I was wondering if anyone had any solutions to the first 2 problems, or if anyone knew of another technique to detect the position of one object relative to another.