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  Wikipedia: Typewriter

Wikipedia: Typewriter
Typewriter
From Wikipedia, the free encyclopedia.


Typist typing on a typewriter.
1st decade of 20th century

A typewriter is a mechanical, electromechanical, or electronic device with a set of "keys" that, when pressed, cause characters to be printed on a document, usually paper.

A typewriter has a keyboard, with keys for the characters in its font. The method by which the typewriter actually marks the paper now varies as greatly as types of printers do, but until the end of the 20th century was by the impact of a metal (or, later, metallized plastic) type element against an "inked" ribbon which caused ink to be deposited on the paper. Carbon paper was sometimes inserted between multiple pieces of paper, so the impact also caused duplicate characters to be printed on each layer of paper.

Innovations

The typewriter was invented in 1864 by Peter Mitterhofer.

In 1867 Christopher Sholes, Carlos Glidden, and Samuel W. Soule invented another typewriter. The patent (US 79,265) was sold for $12,000 to a couple of entrepreneurs who made an agreement with E. Remington and Sons (then famous as a manufacturer of sewing machines), to commercialize what was known as the Sholes and Glidden Type-Writer. Remington started production of the first practical typewriter on March 1, 1873 in Ilion, New York.



Mechanical typewriter with carriage return

In the original design style, now known as a "mechanical" or "manual" typewriter, each key was attached to a typebar that had the corresponding letter molded into its other end. When a key was struck briskly and firmly, the typebar hit a ribbon (usually made of inked fabric) stretched in front of a cylindrical platen that moved back and forth. The paper was rolled around by the typewriter's platen which was rotated by a lever (the "carriage return" lever at the far left) to each new line of text. Some typewriters used ribbons that were inked in black and red, each a stripe half the width and the entire length of the ribbon, and there was a lever to switch between them, for typing bookkeeping entries, where negative amounts had to be in red.

Electric designs

Electrical typewriter designs removed the direct mechanical connection between the keys and the element that struck the paper, and Remington's electric typewriters were the most common until IBM broke the mold with the IBM Selectric typewriter, which replaced the typebars with a spherical typeball (more correctly, "element"), slightly smaller than a golf ball, with the letters molded on its surface and a system of electric motors for rotating the ball into the correct position, then striking it against the ribbon, so the typeball moved across in front of the paper instead of the platen's carrying the paper across a stationary print position.


Typeball
spherical element

The typeball design had many advantages, especially elimination of "jamming" when more than one key was struck at once and the ability to change the typeball, thus allowing multiple fonts in one document. Selectrics were widely used as computer terminals in the 1970s, because the electronic instructions for manipulating the typeball could come just as easily from a computer as from the keyboard, and then the keyboard communicated to the computer, and the computer communicated to the typeball.


Daisy Wheel
letters disk

Later models of Selectrics replaced inked fabric ribbons with "carbon film" ribbons (that had a dry black (or, later, colored) powder on a ("once-thru") clear plastic tape and could be used only once but were in a cartridge that was easy to replace); introduced auto-correction (where a sticky tape in front of the print ribbon could remove the black-powdered image of a typed character); and introduced selectable "pitch" (so the typewriter could be switched among pica ("10 pitch"), elite ("12 pitch"), and sometimes agate ("15 pitch") even in one document). The final major development of the typewriter was "electronic" typewriters, most of which replaced the typeball with a daisy wheel mechanism (a disk with the letters molded on the outside edge of the "petals"). A plastic daisy-wheel was much simpler and cheaper than the typeball but frequently wore out and had to be replaced. Some electronic typewriters were basically dedicated word processors with internal memory and, often, cartridge or diskette external memory-storage devices.

Typewriter legacy

In the developed world, with the proliferation of the personal computer, typewriters have faded into near-obscurity and are now used mainly by people without access to, or the training to use, a computer, and for specialized applications such as filling out forms. However they are still commonly used in poor countries which lack access to computers or to an electricity supply.


QWERTY typewriter
de facto standard

In some of those countries it is possible, in medium sized towns or large villages, to go to the public square and find individuals who gather there with their old but sturdy typewriters. These individuals rent out their services as letter writers, on the spot. They have illiterate or semi-literate customers who tell them what they want in their letters and they also have literate individuals who do not own a typewriter and wish to send a well done letter to an official or some other correspondent who would not be impressed by manuscript correspondence.

Keyboard layout

The 1874 Sholes & Glidden typewriters established the QWERTY layout for the letter keys that is used in virtually all computer and other keyboards nowadays. This layout of keys has been adopted as the de facto standard for English-language keyboards. Other nations using the Latin alphabet use variants of the QWERTY layouts, for example the French AZERTY layout.

Radically different layouts such as the Dvorak keyboard have been proposed but have not been able to displace the QWERTY layout, despite the advantages claimed by their proponents.

Correction methods

According to the standards taught in secretarial schools in the mid-1900s, a business letter was supposed to have no mistakes and no visible corrections. Accuracy was, therefore, prized as much as speed. Indeed, typing speeds, as scored in proficiency tests and typewriting speed competitions, included a deduction of ten words for every mistake that was made.

Corrections, were, of course, necessary, and a variety of methods and technologies were used.

The traditional method involved the use of a special typewriter eraser. The typewriter eraser was made of fairly hard, stiff rubber, containing abrasive material. It was the approximate size of a pizza wheel, and fairly thin, allowing for the erasure of individual typed letters. Business letters were typed on heavyweight, high-rag-content bond paper, not merely to give a luxurious appearance, but also to stand up to erasure. Typewriter erasers were equipped with a brush for brushing away eraser crumbs and paper dust, and using the brush properly was an important element of typewriting skill, because if erasure detritus fell into the typewriter, a very small buildup could cause the typebars to jam in their narrow supporting grooves.

Erasing a set of carbon copies was particularly difficult, and called for the use of a device called an eraser shield to prevent the pressure of erasure on the upper copies from producing carbon smudges on the lower copies.

Paper companies produced a special form of typewriter paper called erasable bond. This incorporated a thin layer of material that prevented ink from penetrating and was relatively soft and easy to remove from the page. An ordinary soft pencil eraser could quickly produce perfect erasures on this kind of paper. However, the same characteristics that made the paper erasable made the characters subject to smudging due to ordinary friction, making it unacceptable for business correspondence or anything archival.

In the fifties and sixties, correction fluid made its appearance, under brand names such as Liquid Paper and Wite-Out. This was a kind of opaque white fast-drying paint which produced a fresh white surface onto which a correction could be re-typed. However, when held to the light, the covered-up characters were visible, as was the patch of dry correction fluid (which was never perfectly flat, and never a perfect match for the color, texture, and luster of the surrounding paper). The standard trick for solving this problem was Photocopying the corrected page, but this was possible only with high quality photocopiers, and was not practical with color letterheads.

Dry correction products under brand names such as Ko-Rec-Type were introduced in the seventies and functioned like white carbon paper. A strip of the product was placed over the letters needing correction, and the incorrect letters were retyped, causing the black character to be overstruck with a white overcoat. Similar material was soon incorporated in carbon-film electric typewriter ribbons; like the traditional two-color black-and-red inked ribbon common on manual typewriters, a black/white correcting ribbon became commonplace on electric typewriters.

The pinnacle of this kind of technology was the IBM Correcting Selectric. This machine, and similar products, incorporated a black/white ribbon and a character memory. With a single keystroke, the typewriter was capable of automatically reversing and overstriking the previous few characters with white cover-up.

Related topics

Office Printers and Fonts Other
Keyboards Corporations and typewriters Encryption Use as Computer peripherals

  

From Wikipedia, the free encyclopedia. 
Modified by Geona