Graphic tablet

A graphic tablet (also known as a digitizer, drawing tablet, digital drawing tablet, pen tablet, or digital art board) is a computer input device that enables a user to hand-draw images, animations and graphics, with a special pen-like stylus, similar to the way a person draws images with a pencil and paper. These tablets may also be used to capture data or handwritten signatures. It can also be used to trace an image from a piece of paper which is taped or otherwise secured to the tablet surface. Capturing data in this way, by tracing or entering the corners of linear poly-lines or shapes, is called digitizing.

The device consists of a flat surface upon which the user may "draw" or trace an image using the attached stylus, a pen-like drawing apparatus. The image is displayed on the computer monitor, though some graphic tablets now also incorporate an LCD screen for a more realistic or natural experience and usability.

Some tablets are intended as a replacement for the computer mouse as the primary pointing and navigation device for desktop computers.

The first electronic handwriting device was the Telautograph, patented by Elisha Gray in 1888. Elisha Gray is best known as a contemporaneous inventor of the telephone to Alexander Graham Bell.

The first graphic tablet resembling contemporary tablets and used for handwriting recognition by a computer was the Stylator in 1957. Better known (and often misstated as the first digitizer tablet) is the RAND Tablet also known as the Grafacon (for Graphic Converter), introduced in 1964. The RAND Tablet employed a grid of wires under the surface of the pad that encoded horizontal and vertical coordinates in a small magnetic signal. The stylus would receive the magnetic signal, which could then be decoded back as coordinate information.

The acoustic tablet, or spark tablet, used a stylus that generated clicks with a spark plug. The clicks were then triangulated by a series of microphones to locate the pen in space. The system was fairly complex and expensive, and the sensors were susceptible to interference by external noise.

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