Previous models relied on a special included stylus to turn the projected image into a touchscreen. But again, once that inevitably goes missing, so do those touchscreen capabilities. This time around Epson has included a sensor unit that bathes the screen in infrared light which it then uses to detect the presence and movements of a finger.
While the projector’s touchscreen capabilities can’t be used to control the OS of whatever computer’s hooked up, it can be used to access the settings menu for making tweaks to the image, or for zooming and scrolling the actual projection. So while the pen might be mightier than the sword, in this case the finger trumps them both.