How Does the Electric Typewriter Work?
The Revolution Before the Revolution
Long before the desktop computer became the must-have business machine, the electric typewriter was conceived by a number of inventors as an improvement on the manual machine that had been around, in one form or another, since the early 19th century. The first commercially viable use of electrically controlled typing was in the ticker tape, a machine operated by a remote keyboard that reported news and is still used by many services. The first electric typewriters were heavy and bulky, but by 1925, the development of lighter metals and smaller parts began four decades of dominance by the electric typewriter, only to end when it was replaced by the first word processor. In the end, the electric typewriter became obsolete as the business world embraced the computer revolution.
The Basics
All manual typewriters are machines that use a system of levers to tilt an arm called a "typebar." When a symbol on the "keyboard" is struck, the typebar swings across the "typebasket" and strikes the "platen," a long steel tube (covered by a rubber sleeve) that sits on a movable carriage. Original characters were made of recycled linotype, hence the term "typeface" for the parts at the end of each typebar. Each time a character was hit on the keyboard (keystroke"), an impression would be made by the flying typeface through a ribbon of graphite-impregnated fabric onto the paper covering the platen. As each key was hit, a system of gears beneath the carriage moved the platen, one uniform space at a time, until the end of a line of type. The operator then had to knock a lever on the side of the carriage that would turn the platen one line up (or down) as the platen slid back along its ball bearing-filled carriage. The electric typewriter modified this system only by inserting a motor that controlled the typebars, making each keystroke absolutely uniform, requiring only the strength taken to depress characters on the keyboard rather than to push the typebar. The first electric machines had manual "returns," requiring the operator to push the carriage back, but eventually the platen was also operated by a keystroke.
The Advent of the Electronics
The final electric typewriters used a system designed for the first electrics---they had a stationary platen and the type basket moved. First the golfball-sized IBM "typeball," then the "daisywheel" wheel-shaped carriers, were mounted on a moving carriage that contained typeface and ribbon (and in many models, correction tape) that moved laterally in front of the platen. The ball and daisy both moved using a series of tiny levers and tapes that eliminated the problems caused by crossed typebars. Smudgy ribbons were replaced by cartridges containing Mylar-coated media similar to photo printers. The final improvement, electronics, replaced the simple mechanical linkages operated by a motor in the electrics with integrated circuits, memory cards and electromagnetic controls. Electronics could correct words, remember lines of type and change type size without having to change a typeball.
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