Projection keyboard

A projection keyboard is a form of computer input device whereby the image of a virtual keyboard is projected onto a surface: when a user touches the surface covered by an image of a key, the device records the corresponding keystroke. Some connect to Bluetooth devices, including many of the latest smartphone, tablet, and mini-PC devices with Android, iOS or Windows platform.

An optical virtual keyboard was invented and patented by IBM engineers in 1992. It optically detects and analyses human hand and finger motions and interprets them as operations on a physically non-existent input device like a surface with painted or projected keys. In that way it can emulate unlimited types of manually operated input devices (such as a mouse, keyboard, and other devices). Mechanical input units can be replaced by such virtual devices, potentially optimized for a specific application and for the user's physiology, maintaining speed, simplicity and unambiguity of manual data input.

In 2002, start-up company Canesta developed a projection keyboard using their proprietary "electronic perception technology". The company subsequently licensed the technology to Celluon of Korea.

A proposed system called the P-ISM combines the technology with a small video projector to create a portable computer the size of a fountain pen.

A laser or beamer projects visible virtual keyboard onto level surface. A sensor or camera in the projector picks up finger movements Software converts the coordinates to identify actions or characters.

Some devices project a second (invisible infrared) beam above the virtual keyboard. The user's finger makes a keystroke on the virtual keyboard. This breaks the infrared beam and reflects light back to the projector. The reflected beam passes through an infrared filter to the camera. The camera photographs the angle of incoming infrared light. The sensor chip determines where infrared beam was broken. Software determines the action or character to be generated.

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