Graphics tablet
From Wikipedia, the free encyclopedia
A graphics tablet is a computer input device that allows one to hand-draw images and graphics, similar to the way one draws images with a pencil and paper.
A Graphics tablet consists 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.
Graphics tablets should not be confused with the tablet PC.
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[edit] 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.
Digitizers were popularized in the mid 1970's and early 1980's by the commercial success of the ID (Intelligent Digitizer) and BitPad manufactured by the Summagraphics Corp. These digitizers were used as the input device for many high-end CAD (Computer Aided Design) systems as well as bundled with PC's and PC based CAD software like AutoCad.
Summagraphics also made a OEM version of its BitPad which was sold by Apple as an accessory to their Apple II. These tablets used a magneto-strictive technology which used wires made of a special alloy stretched over a solid substrate to accurately locate the tip of a stylus or the center of a digitizer cursor on the surface of the tablet. This technology also allowed Proximity or "Z" axis measurement.
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.
[edit] Operation
- Passive tablets make use of electromagnetic induction technology, where the horizontal and vertical wires of the tablet operate as both transmitting and receiving coils (as opposed to the wires of the RAND Tablet which only transmit). The tablet generates an electromagnetic signal, which is received by the LC circuit in the pen. The wires in the tablet then change to a receiving mode and read the signal generated by the pen. Some modern arrangements also provide pressure sensitivity and one or more switches (similar to left and right click on a mouse), with the electronics for this information present in the pen itself, not the tablet. Changing the pressure on the pen nub or pressing a switch changes the capacitance, which affects the signal generated by the pen. By using electromagnetic signals, the tablet is able to sense the stylus position without the stylus having to even touch the surface, and powering the pen with this signal means that the devices used with the tablet never need batteries.
- Active tablets differ in that the stylus used contains self-powered electronics that generate and transmit a signal to the tablet. These pens rely on an internal battery rather than the tablet for their power, resulting in a bulkier pen. Eliminating the need to power the pen means that such tablets may listen for pen signals constantly, as they do not have to to alternate between transmit and receive modes, which can result in less jitter.
[edit] Uses
[edit] 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. The GIMP, Corel Painter, Inkscape, Photoshop, Pixel image editor, Studio Artist) 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.
In East Asia, graphics tablets, or pen tablets as they are known, are widely used in conjunction with input method editor software (IMEs) to write Chinese, Japanese, Korean characters (CJK). The technology is popular and inexpensive.
Tablets are also popular for technical drawings and CAD, as one can put a piece of paper on them without interfering with their function.
Many of the most successful webcomic artists use tablets, including Hawk of AppleGeeks, Tim of Ctrl+Alt+Del and Gabe of Penny Arcade, who uses a Wacom Cintiq to color directly into the computer.
Finally, tablets are gaining popularity as a replacement for the computer mouse as a pointing device. They can be more intuitive to some users than the mouse, as the position of the pen on the tablet typically corresponds to the location of the pointer on the GUI shown on the computer screen. Those artists using the pen for graphics work will as a matter of convenience use the tablet and pen for standard computer operations rather than put down the pen and find the mouse.
[edit] A Solution for Injuries
Advocates of tablets and pens cite relief from occupational overuse syndrome varieties such as repetitive strain injury [1]. Sufferers of carpal tunnel syndrome also report good results. This is because the use of computer mice tends to be very repetitive on the wrist, whereas operating a pen is more natural and tends to involve the movement of the entire arm [2].
[edit] 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
- 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) http://www.dpreview.com/news/0509/wacom_graph4white68-001.jpg Intuos 3 4x5, 6x8, and 9x12 http://www.dpreview.com/news/0409/wacomint3-01.jpg
[edit] Manufacturers
- ACE CAD Enterprise Co., Ltd [3]
- Adesso [4]
- Aiptek [5]
- Genius KYE [6]
- GTCO CalComp [7]
- Promethean Ltd [8]
- UC-Logic [9]
- Wacom [10]
[edit] Similar devices
Some Interactive Whiteboards operate on the induction principle, with some brands offering high resolution wall size graphic tablets up to 95" along with options for pressure and multiple input based on different resonance patterns from tuned pens. Interactive Whiteboards are proving to be immensely popular in schools in the UK, US and Mexico.
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. Also, the Nintendo DS is a Touch Screen Device.
[edit] References
- Repetitive Stress. WACOM Technology United States Website. Retrieved on August 24, 2007.
