Composing typewriters are used to prepare texts for duplication by small-job printing equipment. Unlike office typewriters, composing typewriters have a typeface that resembles print, and they are equipped with variable spacing and with a mechanism that widens or compresses the spaces between letters. Office typewriters are used for high-volume, professional typing of texts and tables. Portable typewriters, which are larger than travel typewriters, are designed for general use. Used primarily by journalists, travel typewriters are small and lightweight. There are several kinds of typewriters, categorized according to their purpose: travel, portable, office, composing, and special typewriters. Typewriters are classified as office machines. The maximum typing speed, which is limited by human physical capabilities, ranges from seven to ten characters per second. In most typewriters, the printed character is produced when the paper is struck through an inked ribbon by a type-bar or spherical or cylindrical head covered with raised (convex) characters. Other forms of typewriters included the stock ticker, which recorded its message on a narrow strip of paper, and the teletypewriter, which transmitted typing over an electric circuit such as the telephone or telegraph.Ī device for printing texts by making standard representations of symbols such as letters and numbers. Nonetheless, the typewriter was almost completely superseded by personal computers using word-processing software and printers by the mid-1990s the machines are still used for specialized printing functions. These innovations have allowed typewriters to become versatile printing instruments, capable of storing entire documents before printing, identifying and correcting errors as they arise, and connecting to computers. The globe was later replaced by the daisy wheel, which spins the proper type into position. The Selectric, introduced by International Business Machines (IBM) in 1961, replaced the usual type bars with a metal globe that moved across the surface of a stationary paper holder, replacing the moving carriage of the traditional typewriter interchangeable globes provided a variety of typefaces and special symbols, allowing a single typewriter to be utilized for scientific writing, foreign languages, or other uses. The electric typewriter, which allowed greater speed with less effort than a manual machine, came into use c.1935. A shift-key model, permitting change of case, appeared in 1878. This early model had only capital letters. A practical commercial machine invented in the United States in 1867 by Christopher Latham Sholes and his associates, Carlos Glidden and Samuel Soulé, was manufactured by Philo Remington and placed on the market in 1874. The early models were chiefly for the blind and produced embossed writing. An improved French machine appeared in 1833. In the United States the typographer of William Austin Burt, patented in 1829, was the first practical writing machine. The first recorded patent for a typewriter was taken out in England by Henry Mill in 1714. Activated through a series of levers or an electronic impulse when its key is pressed, the type strikes the paper in the machine through an inked ribbon the carriage holding the paper then automatically moves, providing space for the next character. Corresponding to each key on the instrument's keyboard is a steel type. Typewriter, instrument for producing by manual operation characters similar to those of printing.
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