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.
The projection is realized in four main steps and via three modules: projection module, sensor module and illumination module. The main devices and technologies used to project the image are a diffractive optical element, red laser diode, CMOS sensor chip and an infrared (IR) laser diode.
Projection keyboards connect to the computer either through Bluetooth or USB.
Bluetooth dongle technology enables the projection keyboard for point to multi-point connectivity with other Bluetooth devices, such as PCs, PDAs and mobile phone.
How the Bluetooth projection keyboard connects to devices depends on the specific tablet, phone or computer.
The connection between the USB keyboard and the device is made through a USB port, which is available on every computer and (via an adapter) other devices.
Apart from simply being used to type, most laser keyboard systems can function as a virtual mouse or even as a virtual piano.
Copyrighted by: http://en.wikipedia.org/wiki/Projection_keyboard
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