Графические планшеты: история и современные устройства

Computer input device

A graphics tablet (also known as a digitizer, digital graphic tablet, pen tablet, drawing tablet, external drawing pad 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. Graphics tablets may also be used to capture data or handwritten signatures. They can also be used to trace an image from a piece of paper that is taped or otherwise secured to the tablet surface. Capturing data in this way, by tracing or entering the corners of linear polylines or shapes, is called digitizing. The device consists of a rough surface upon which the user may "draw" or trace an image using the attached stylus, a pen like drawing apparatus. The image is shown on the computer monitor, though some graphic tablets now also incorporate an LCD screen for 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. 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 electrostatic signal. The stylus received the signal by capacitive coupling, 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. Digitizers were popularized in the mid 1970s and early 1980s by the commercial success of the ID (Intelligent Digitizer) and BitPad manufactured by the Summagraphics Corp. The Summagraphics digitizers were sold under the company's name but were also private labeled for HP, Tektronix, Apple, Evans and Sutherland and several other graphic system manufacturers. The ID model was the first graphics tablet to make use of what was at the time, the new Intel microprocessor technology. This embedded processing power allowed the ID models to have twice the accuracy of previous models while still making use of the same foundation technology. Key to this accuracy improvement were two US Patents issued to Stephen Domyan, Robert Davis, and Edward Snyder. The Bit Pad model was the first attempt at a low cost graphics tablet with an initial selling price of $555 when other graphics tablets were selling in the $2,000 to $3,000 price range. This lower cost opened up the opportunities for would be entrepreneurs to be able to write graphics software for a multitude of new applications. These digitizers were used as the input device for many high end CAD (Computer Aided Design) systems as well as bundled with PCs and PC based CAD software like AutoCAD. These tablets used a magnetostriction 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. In 1981, musician Todd Rundgren created the first color graphic tablet software for personal computers, which was licensed to Apple as the Utopia Graphic Tablet System. In 1981, the Quantel Paintbox color graphic workstation was released; This model was equipped with the first pressure sensitive tablet. The first home computer graphic tablet was the KoalaPad, released in 1983. Though originally designed for the Apple II, the Koala eventually broadened its applicability to other home computers including the TRS 80 Color Computer, Commodore 64, and Atari 8 bit computers. In the 1980s, several vendors of graphic tablets began to include additional functions, such as handwriting recognition and on tablet menus.

Typically tablets are characterized by size of the device, drawing area, its resolution size («active area», which is measured in lpi), pressure sensitivity (level of varying the size of strokes with pressure), number of buttons and types and number of interfaces: Bluetooth, USB; etc. The actual drawing accuracy is restricted to pen's nib size.

After styluses, pucks are the most commonly used tablet accessory. A puck is a mouse like device that can detect its absolute position and rotation. This is opposed to a mouse, which can only sense its relative velocity on a surface (most tablet drivers are capable of allowing a puck to emulate a mouse in operation, and many pucks are marketed as a "mouse"). Pucks range in size and shape; some are externally indistinguishable from a mouse, while others are a fairly large device with dozens of buttons and controls. Professional pucks often have a reticle or loupe which allows the user to see the exact point on the tablet's surface targeted by the puck, for detailed tracing and computer aided design (CAD) work. Pucks are used on the Microsoft Surface range and were recently used on the Dell Canvas. However, they have been largely discontinued by most manufactures in favour of physical hotkeys and dials.

Graphic tablets, because of their stylus based interface and ability to detect some or all of 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 graphic packages can make use of the pressure (and, sometimes, stylus tilt or rotation) information generated by a tablet, by modifying the brush size, shape, opacity, color, or other attributes based on data received from the graphic tablet. In East Asia, graphic tablets, known as "pen tablets", are widely used in conjunction with input method editor software (IMEs) to write Chinese, Japanese, and Korean characters (CJK). The technology is popular and inexpensive and offers a method for interacting with the computer in a more natural way than typing on the keyboard, with the pen tablet supplanting the role of the computer mouse. Uptake of handwriting recognition among users who use alphabetic scripts has been slower. Graphic tablets are commonly used in the artistic world. Using a pen like stylus on a graphic tablet combined with a graphics editing program, such as Illustrator, Photoshop by Adobe Systems, Corelpainter, or Krita gives artists a lot of precision when creating digital drawings or artwork. Photographers can also find working with a graphic tablet during their post processing can really speed up tasks like creating a detailed layer mask or dodging and burning. Educators make use of tablets in classrooms to project handwritten notes or lessons and to allow students to do the same, as well as providing feedback on student work submitted electronically. Online teachers may also use a tablet for marking student work, or for live tutorials or lessons, especially where complex visual information or mathematical equations are required. Students are also increasingly using them as note taking devices, especially during university lectures while following along with the lecturer. They facilitate smooth online teaching process and are popularly used along with face cam to mimic classroom experience. Tablets are also popular for technical drawings and CAD, as one can typically 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. They can feel more intuitive to some users than a mouse, as the position of a pen on a tablet typically corresponds to the location of the pointer on the GUI shown on the computer screen. Those artists using a pen for graphic work may, as a matter of convenience, use a tablet and pen for standard computer operations rather than put down the pen and find a mouse. Popular rhythm game osu! allows utilizing a tablet as a way of playing. Graphic tablets are available in various sizes and price ranges; A6 sized tablets being relatively inexpensive and A3 sized tablets far more expensive. Modern tablets usually connect to the computer via a USB or HDMI interface.

Interactive whiteboards offer high resolution wall size graphic tablets up to 95" (241,3 cm) along with options for pressure and multiple input. These are becoming commonplace in schools and meeting rooms around the world. Earlier resistive touch screen devices (like PDAs, early smartphones, tablet PCs, and the Nintendo DS) were typically equipped with styluses, but accuracy of stylus input was very limited. The more modern capacitive touch screens such as those found on some table computers, tablet computers and laptops operate in similar ways, but they usually use either optical grids or a pressure sensitive film instead so do not need a special pointing device. Some of the latest models with capacitive input can be equipped with specialized styluses, and then these input devices can be used similar to full function graphics tablet. A graphic tablet is also used for Audio Haptic products where blind or visually impaired people touch swelled graphics on a graphic tablet and get audio feedback from that. The product that is using this technology is called Tactile Talking Tablet or T3.