Surface and Pressure

Santosh Kushwaha        Print Edition: January 2012

Graphics tablet
A graphics tablet is a flat surfaces on which you draw with a stylus or a pen-like device. The tablet is attached to the computer and the stylus to the tablet. The tablets capture the image as data which is then stored as a file or document. Graphics tablets can be used like a large marker board to take notes on or to create outlines at a conference or lecture during which images have to be viewed by the audience. They can also be used by individuals as drawing surfaces to create drawings/ paintings, and edit images. The output is almost close to handmade sketches and drawings.

1. The tablet works by plugging into a computer via a USB port. A stylus is similarly attached to the tablet. When a user draws a line with the stylus, the drawing does not show up on the tablet. Instead the action generates a signal that goes to a vertical grid of wires running across the tablet.

 FACTS FROM THE PAST
1888: The first electronic handwriting transmitting device was the Telautograph, patented by Elisha Gray.
1957: The first graphics tablet resembling contemporary tablets and used for handwriting recognition by a computer was the Stylator.
1980: In the 1980s, several vendors of graphics tablets began to include additional functions, such as handwriting recognition and ontablet menus.
1981: In 1981, musician Todd Rundgren created the first colour graphics tablet software for personal computers. It was licensed to Apple as the Utopia Graphics Tablet System.

In touchscreen tablets , the whole monitor becomes the writing surface and the user interacts directly with the display instead of drawing on one surface and viewing on another.

2. The pen may be battery-powered or may have a cord. When a user draw a line using the stylus, the coil circuit transfers the signals to the main circuit inside the stylus. This calculates the number of lines-lengths, while the pressure sensitive capacitor measures the pressure of the lines. The data signal is generated by the stylus and detected by a grid of wires in the tablet called the sensor board.

3. The horizontal and vertical wires of the tablet operate as both transmitting and receiving coils. the tablet generates an electromagnetic signal, which is received by a circuit in the stylus. the stylus works as an antenna that receives the signal and generates another electromagnetic field that "talks" back to the tablet.

4. By using electromagnetic signals, the tablet is able to transfer the lines to the computer screen or display being used.

Graphics tablet
Stylus effect:
These tablets come with different levels of sensitivity to pressure applied on the surface by the digitiser pen or stylus. Applied pressure on the drawing surface of the graphics tablet gives a mark or line its thickness. Pressing the digitiser pen hard against the drawing surface will result in the line or mark being very dark. Lightly touching the pen to the surface of the graphic tablet will result in a lighter mark or line. With pressure sensitivity, the user experiences a more natural approach to drawing on a computer.

Sizes: Wacom tablets come in various sizes, with the smallest being 7.6 cm by 12.8 inches and the larger tablets having more than these dimensions. The price of a Wacom pen and tablet varies with the size.

Courtesy:Gadgets and Gizmos


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