A projection keyboard is a virtual keyboard that can be projected and touched on any surface. The keyboard watches finger movements and translates them into keystrokes in the device. Most systems can also function as a virtual mouse or even as a virtual piano. A proposed system called the P-ISM will combine the technology with a small video projector to create a portable computer the size of a fountain pen.
How a projection keyboard generally works:
- A laser or beamer projects visible virtual keyboard onto level surface
- A sensor or camera in the projector picks up finger movements
- detected co-ordinates determine actions or characters to be generated
Some devices use a second (invisible infrared) beam:
- An invisible infrared beam is projected above the virtual keyboard
- Finger makes keystroke on virtual keyboard. This breaks infrared beam and infrared light is reflected back to projector
- Reflected infrared beam passes through infrared filter to camera
- Camera photographs angle of incoming infrared light
- Sensor chip determines where infrared beam was broken
- detected coordinates determine actions or characters to be generated
