Graphics tablet

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Image:Graphics tablet.jpg Image:Wacom Cintiq Monitor.jpg A graphics tablet is a computer peripheral device that allows one to hand-draw images directly into a computer, generally through an imaging program. Graphics tablets consist of a flat surface upon which the user may "draw" an image using an attached stylus, a pen-like drawing apparatus. The image generally does not appear on the tablet itself but, rather, is displayed on the computer monitor.

It is interesting to note that the stylus, as a technology, was originally designed as a part of the electronics, but later it simply took on the role of providing a smooth, but accurate "point" that would not damage the tablet surface while "drawing".

Graphics tablets should not be confused with the tablet PC.

1 History and background
2 Uses
- 2.1 General uses
- 2.2 Examples
3 Manufacturers
4 Similar devices
5 References

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History and background

Early graphics tablets, known as spark or acoustic tablets, 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.

The first graphics tablet resembling contemporary tablets was 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 first home computer graphics tablet was the KoalaPad. Though originally designed for the Apple II, the Koala eventually broadened its applicability to practically all home computers with graphics support, examples of which include the TRS-80 Color Computer, Commodore 64, and Atari 8-bit family. Competing tablets were eventually produced; the tablets produced by Atari were generally considered to be of high quality.

Modern graphics tablets operate in a fashion similar to the RAND Tablet. In modern devices, though, the horizontal and vertical wires of the grid are separated by a thin insulator. When pressure is applied to the tablet, the horizontal wire and vertical wire associated with the corresponding grid point meet each other, causing an electric current to flow into each of these wires. Since an electric current is only present in the two wires that meet, a unique coordinate for the stylus can be retrieved. Pointing device detection is additionally aided by a weak magnetic field projected approximately one inch from the tablet surface. It is important to note that, unlike the RAND Tablet, modern tablets do not require electronics in the stylus and any tool that provides an accurate "point" may be used with the pad (though the stylus itself is likely designed with both the resolution of the grid and the durability of the tablet in mind and, therefore, should be used).

Graphics tablets produced by Wacom primarily make use of induction technology, where the tablet itself operates as both a transmitting and receiving coil. The tablet generates a signal, which is then received in the tank circuit in the pen. Changing the pressure on the stylus or pressing a switch changes the capacitance, which is then reflected in the signal generated by the pen.

Some modern arrangements also provide pressure information, but the electronics for this information are present in the stylus nub, not the tablet.

Graphics tablets are available in various sizes and price ranges; A6-sized tablets being relatively inexpensive and A3-sized tablets being far more expensive. Modern tablets usually connect to the computer via a USB interface.

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Uses

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General uses

Graphics tablets, because of their stylus-based interface and (in some cases) ability to detect pressure, tilt, and other attributes of the stylus and its interaction with the tablet, are widely considered to offer a very natural way to create computer graphics, especially two-dimensional computer graphics. Indeed, many graphics packages (e.g. Corel Painter, Inkscape, Photoshop, Pixel image editor, Studio Artist, The GIMP) are able to make use of the pressure (and, in some cases, stylus tilt) information generated by a tablet, by modifying attributes such as brush size, opacity, and color based on data received from the graphics tablet. Tablets are also popular for technical drawings and CAD, as one can put a piece of paper on them without interfering with their function.

Finally, tablets are gaining popularity as a replacement for the computer mouse as a pointing device. Advocates cite relief from repetitive strain injury and greater intuitiveness[1].

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Examples

In high-end computer graphics systems, the graphics tablet has always been the input device of choice. Some examples are:

the Crosfield imaging system
PCB drafting/layout systems
the Quantel Paintbox

Devices similar to graphics tablets, such as light pen-based systems, have been used to control other types of systems, such as the Fairlight CMI computer musical instrument. Here are some example images of the latest version of modern tablets.
The Graphire4 6x8 (Snow) Intuos 3 4x5, 6x8, and 9x12

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Manufacturers

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Similar devices

Touch screens are operated in similar ways, but they usually use either optical grids or a pressure sensitive film instead, and therefore they do not need a special pointing device.

The development of the Tablet PC is another example of the integration of graphics tablet and screen.

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