Typewriter ribbon
Encyclopedia
A typewriter ribbon is an expendable module serving the function of transferring pigment to paper in various devices for impact printing. Such ribbons were part of standard designs for hand- or motor-driven typewriter
s, teleprinter
s, stenotype
machines, computer-driven printers and many mechanical calculator
s, before electronic alternatives replaced most of them.
The module consists of a length of a medium, either pigment-impregnated woven ribbon or pigment-coated polymer
tape, and a transport mechanism involving two axles. At any given moment, most of the length of the medium is wound as a close-spaced spiral
around one axle or the other, tight enough for friction between turns to make it behave mostly like a solid cylinder. Rotation of the axles moves the ribbon or tape after each impact and usually aids in maintaining tension along the roughly straight-line path of the medium between the axles. The module may itself include mechanisms that control the tension in the temporarily unwound portion of the medium.
that dries on typing paper but not on the ribbon, and the ribbon is mounted at each end to a flange
d reel whose hub engages with one of the axles. Only the axle onto which the ribbon is winding is driven, and the ribbon module is intended to work with an axle-driving mechanism that reverses the direction of rotation when the undriven axle reaches the point where there is no ribbon left wound around it. Thus the full length of the ribbon shuttles back and forth between reels, and each position along it is struck twice in each cycle of the ribbon's motion (once in the right-to-left phase and once in the left-to-right).
An operator who judges a ribbon's ink supply to be depleted to a point of marginal acceptability typically manually winds the whole ribbon onto the fuller reel, releasing it from the empty one, discarding the ribbon the reel it is wound on, and replaces them with a new ribbon that is purchased already wound on a single compatible reel. Typically the attachment between reel and ribbon involves one grommet at each end of the ribbon, that pierces the ribbon and engages with a hook on the hub of the corresponding reel.
required ribbons of polymer tape and made them common. With them, the entire impacted area of the pigment coating adheres to the paper and peels off of the ribbon, producing typed copy with greater uniformity of character shape, reflecting sharper contrast between the unmarked paper and the pigmented characters compared to cloth ribbons. This full-depth shedding of the pigment renders multiple passes over the length of the ribbon unworkable, and the module is discarded after a single pass through its length. (Incidentally, deducing what has been typed by inspection of the ribbon is far more practicable and reliable than with a cloth ribbon, and some users ensure destruction of discarded one-time ribbons in order to prevent unintended disclosure.)
Typewriter
A typewriter is a mechanical or electromechanical device with keys that, when pressed, cause characters to be printed on a medium, usually paper. Typically one character is printed per keypress, and the machine prints the characters by making ink impressions of type elements similar to the pieces...
s, teleprinter
Teleprinter
A teleprinter is a electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communication channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the...
s, stenotype
Stenotype
A stenotype, stenotype machine or shorthand machine is a specialized chorded keyboard or typewriter used by stenographers for shorthand use...
machines, computer-driven printers and many mechanical calculator
Mechanical calculator
A mechanical calculator is a device used to perform the basic operations of arithmetic. Mechanical calculators are comparable in size to small desktop computers and have been rendered obsolete by the advent of the electronic calculator....
s, before electronic alternatives replaced most of them.
The module consists of a length of a medium, either pigment-impregnated woven ribbon or pigment-coated polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
tape, and a transport mechanism involving two axles. At any given moment, most of the length of the medium is wound as a close-spaced spiral
Spiral
In mathematics, a spiral is a curve which emanates from a central point, getting progressively farther away as it revolves around the point.-Spiral or helix:...
around one axle or the other, tight enough for friction between turns to make it behave mostly like a solid cylinder. Rotation of the axles moves the ribbon or tape after each impact and usually aids in maintaining tension along the roughly straight-line path of the medium between the axles. The module may itself include mechanisms that control the tension in the temporarily unwound portion of the medium.
Reversing ribbons
Woven typewriter ribbons were the earlier variant. With them, the pigment is an inkInk
Ink is a liquid or paste that contains pigments and/or dyes and is used to color a surface to produce an image, text, or design. Ink is used for drawing and/or writing with a pen, brush, or quill...
that dries on typing paper but not on the ribbon, and the ribbon is mounted at each end to a flange
Flange
A flange is an external or internal ridge, or rim , for strength, as the flange of an iron beam such as an I-beam or a T-beam; or for attachment to another object, as the flange on the end of a pipe, steam cylinder, etc., or on the lens mount of a camera; or for a flange of a rail car or tram wheel...
d reel whose hub engages with one of the axles. Only the axle onto which the ribbon is winding is driven, and the ribbon module is intended to work with an axle-driving mechanism that reverses the direction of rotation when the undriven axle reaches the point where there is no ribbon left wound around it. Thus the full length of the ribbon shuttles back and forth between reels, and each position along it is struck twice in each cycle of the ribbon's motion (once in the right-to-left phase and once in the left-to-right).
An operator who judges a ribbon's ink supply to be depleted to a point of marginal acceptability typically manually winds the whole ribbon onto the fuller reel, releasing it from the empty one, discarding the ribbon the reel it is wound on, and replaces them with a new ribbon that is purchased already wound on a single compatible reel. Typically the attachment between reel and ribbon involves one grommet at each end of the ribbon, that pierces the ribbon and engages with a hook on the hub of the corresponding reel.
One-time ribbons
The IBM Selectric typewriterIBM Selectric typewriter
The IBM Selectric typewriter was a highly successful model line of electric typewriters introduced by IBM on July 31, 1961.Instead of the "basket" of individual typebars that swung up to strike the ribbon and page in a traditional typewriter, the Selectric had a type element that rotated and...
required ribbons of polymer tape and made them common. With them, the entire impacted area of the pigment coating adheres to the paper and peels off of the ribbon, producing typed copy with greater uniformity of character shape, reflecting sharper contrast between the unmarked paper and the pigmented characters compared to cloth ribbons. This full-depth shedding of the pigment renders multiple passes over the length of the ribbon unworkable, and the module is discarded after a single pass through its length. (Incidentally, deducing what has been typed by inspection of the ribbon is far more practicable and reliable than with a cloth ribbon, and some users ensure destruction of discarded one-time ribbons in order to prevent unintended disclosure.)