I am investigating the validity of a foreign patent that describes toy which chases a spot of light projected on the ground by a handheld controller (e.g. flashlight or laser pointer).
It is very similar behavior to a classic Photovore but is distinguished by the fact that the photodetectors are aimed such that they ignore the source of the light and only see the reflected spot.
I have heard of prople doing this with the Mindstroms kits, but does anyone have objective evidence - preferably dated printed or published material - of such a device existing earlier than 2002, either a commercially available product or something someone cobbled together? I would very much appreciate any help you can provide me in tracking this down; it's really important to me to find a prior art example.
Thanks in advance,