This is an overview of the technology behind the Touchjet WAVE.
The WAVE reads touch inputs by detecting reflections from a wall of infrared light which it projects downward from the bottom of the Android Box that mounts on top of a flatscreen TV. The image below shows the whole setup.
You can see the light wall projected parallel to the TV screen. This is crucial for the WAVE to read touch. When you touch your screen, your finger (or stylus, etc.) reflects the IR signal back up toward a camera at the end of the arm on top of the WAVE. This camera, when calibrated properly, will see that reflection as a touch input right where your finger meets the screen.
Each part labeled on the right of the figure helps stabilize the box to reduce the need for repeat calibrations and inaccuracy. The Bracing Rod prevents horizontal rotation, the Stabilizing Arm and Velcro Pad hold it vertically stable.