Digitizer tablets or graphics tablets are pressure-sensitive data input devices that allow users to select and draw images with a special pen called a stylus or a mouse-like device called a puck. Pucks feature a series of buttons and a lens with crosshairs that allows users to select images with greater accuracy. Both pens and pucks can be wireless devices or attached to digitizer tablets via cords or wires. Typically, pucks are used to trace highly detailed engineering drawings or medical X-rays while pens are used for a variety of sketching and tracing applications. With digitizer tablets, producing an image creates a series of X,Y coordinates as either a continuous stream or a series of end points. Pens that record vector graphics in three-dimensional space are also available. The drawings that users produce with digitizer tables are stored as mathematical line segments. Outputs can be sent to computer aided design (CAD) applications, graphics programs, or related software applications.
Digitizer tablets vary in terms of active area length and active area width. Performance specifications include maximum resolution in lines per inch and maximum sampling rate, the rate at which digitizer tablets process user inputs. Accuracy, another important product specification, separates various product lines. Devices that perform standard diagnostic tests can alert users about potential performance problems. Serial interfaces for digitizer tablets include universal serial bus (USB), RS232, and RS422. Parallel interfaces include general-purpose interface bus (GPIB), an 8-bit standard. Digitizer tablets that use special forms of transistor-transistor logic (TTL) or discrete signals are also available.
Digitizer tablets offer a variety of special features and can be used in numerous applications. Some devices are backlit in order to highlight details without distorting colors. Others feature selectable output resolutions or non-volatile memory. Digitizer tablets with integral tables and stands do not require mounting. Devices with a flexible surface can be rolled up and are designed to be portable. Medical personnel use digitizer tablets to digitize X-rays and to perform needle biopsies and orthopedic surgery. Digitizer tablets are also used in construction estimating, cartography, soil conservation, civil and architectural engineering, aerial photo interpretation, property appraisal, and real estate development.