Páginas: 5 (1225 palabras) Publicado: 3 de junio de 2011
Printers wheel:
Are impact printers and character. The printhead consists of a metal wheel that holds the outer molds of various types. The wheel moves perpendicular to the paper over a metal rod axis or parallel to the roller where the paper is based. The wheel is constantly spinning and when the guy to write passes before shooting the ink ribbon for the back to paper, a hammer that makes thecharacter is printed in ink on paper.

After writing the character, the wheel moves along the rod to his right, or go to the next line. These printers are obsolete.

Daisy-wheel printers:
Printers are print quality, but are relatively slow. The characters are modeled on the wider (outer) sectors (petals) of a metal or plastic wheel on a daisy.

Daisy is part of the printhead. A motorpositions the character Daisy sheet against the printing ribbon, banging a hammer against the ribbon petal, type the character on paper. The character set can be easily changed simply by replacing the margarita.

Are similar to typewriters. Are currently out of use.

Matrix printers or needles.
These printers, also known as dot matrix, are the most commonly used with microcomputers and smallcomputer systems. The characters are formed by an array of needles. The hands hit the ink ribbon, transferring to paper the points for the needles fired.

The characters, therefore, are dotted, and its quality far below the continuous characters produced by a printer margarita. However, some models of dot matrix printers have the possibility of Costal written in print. To this end, the characters areoverwritten by slightly off, overlapping those of the second printing with the first, giving a greater semblance of continuity.

Drum printers.
We find, within these printers, two types:

€ ¢ compact drum.
€ ¢ drum wheels.
Both types are line printers and impact.
The compact printer drum contains a cylindrical metal part whose length matches the width of the paper. On the external surfaceof the cylinder or drum circles are modeled in character sets, being repeated many times as they print positions of a line. The drum is constantly turning, and when a generator is positioned corresponding to a certain point, the "A" for example, are printed simultaneously all the "A" line.
The wheel drum printers are similar, except that each circle can rotate independently. All characters in theprint line is written at a time, pre-positioning each type in the correct position.

Instead of a ribbon, these printers usually have a piece of fabric ink width of the paper.

Printers bar.
The characters are molded over a steel bar that moves from left to right at high speed, swinging in front of the line to write. The character is repeated several times (usually three). When the cast ofcharacters printed is positioned in front of the positions that have left the paper behind it triggered a hammer, thus imprinting the line.

The number of hammers match the number of characters per line.

Printers chain.
The rationale is exactly like the bar printers. Now the characters are engraved on the links in a chain. The chain is closed and rotating at high speed against the ink ribbon.Thermal printers.
Similar to needle printers. It uses a special heat-sensitive paper that turns black when applying heat.

The heat is transferred from the head by a small resistance matrix in which an electric current passing through them are heated, forming the dots on the paper.

These printers can be:
€ ¢ Character: The lines are printed with a moving head.
€ ¢ lines: Contain manyheads as characters printed per line. Are faster.

Inkjet printers.
The discovery of this technology was the result of chance. By bringing welder accidentally, by a technician, a tiny cylinder filled with ink, came a projected drop of ink, inkjet born by thermal process. The first patent relating to this type of printing dates from 1951, although until 1983, which launched Epson SQ2000 were not...
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