Stylet (informatique)

In computing, a stylus (or stylus pen) is a small pen-shaped instrument whose tip position on a computer monitor can be detected. It is used to draw, or make selections by tapping. While devices with touchscreens such as newer computers, mobile devices (smartphones and personal digital assistants), game consoles, and graphics tablets can usually be operated with a fingertip, a stylus provides more accurate and controllable input. The stylus has the same function as a mouse or touchpad as a pointing device; its use is commonly called pen computing. The earliest computer-related usage for a stylus was in 1643 with Pascal's calculator. The device had rotary dials that rotated in accordance with the selected numbers; with gears, drums, and clever engineering, it was capable of addition, subtraction, multiplication and division (using 9's constant). A stylus was used to turn the dials. Later devices of this type include the Arithmometer, in the 1860s; and the Addiator, in 1920. The Addiator was a pocket mechanical adding machine that used a stylus to move tiny rigid slices of sheet-metal that were enclosed in a case. On the side of a slice of metal there were numbers that became visible to display the result. It was capable of addition, subtraction, multiplication and division. In 1967 there was a HEXADAT model, which allowed 4-function math to be applied to hexadecimal numbers for use in programming. The first use of a stylus in an electronic computing device was the Stylator, demonstrated by Tom Dimond in 1957. Different types of stylus are used for graphics tablets, as well as resistive and capacitive touchscreens. Capacitive screens are very widely used on smart phones and multi-touch surfaces, where simultaneous use of several fingers is detected; a stylus cannot replicate this. Capacitive (also called passive) styluses emulate a finger by using a tip made of rubber or conductive foam; or metal such as copper. They do not need to be powered and can be used on any multi-touch surface that a finger can be used, typically capacitive screens that are common in smart phones and tablet computers.