What are the types of printers

Wheel
printers They are impact and character printers. The printing head is made up of a metal wheel that contains the different types of molds on the outside. The wheel moves perpendicular to the paper along a metal shaft or rod parallel to the roller where the paper sits. The wheel is continually turning, and as the type to be written passes in front of the ink ribbon, a hammer is fired from the back of the paper, causing the character to be printed in ink on the paper.

Once the character is written, the wheel scrolls along the rod, to its right, or moves to the next line. These printers are deprecated.

Daisy
printers These are print quality printers, however they are relatively slow. The characters are modeled on the widest (outermost) part of the sectors (petals) of a metal or plastic wheel in the shape of a daisy.

The daisy forms part of the printhead. A motor positions the daisy sheet of the character to be printed in front of the ink ribbon, hitting the petal against the ribbon with a hammer, writing the character on the paper. The character set can be easily changed by simply replacing the daisy.

They are analogous to typewriters. They are currently out of use.

Matrix or needle
printers These printers, also called dot matrix printers, are the most used with microcomputers and small computer systems. The characters are formed by means of a matrix of needles. The needles hit the ink ribbon, transferring the points corresponding to the fired needles to the paper.

The characters, therefore, are dotted, their quality being much lower than the continuous characters produced by a daisy chain printer. However, some models of matrix printers present the possibility of writing in semi-print quality. To do this, the characters are rewritten with the points slightly displaced, overlapping those of the second impression with those of the first, giving a greater appearance of continuity.

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

• Compact drum.
• Wheel drum.

Both types are line and impact printers.
The compact drum printer contains a cylindrical metal part whose length matches the width of the paper. On the external surface of the cylinder or drum, the character sets are modeled in circumferences, these being repeated as many times as printing positions of a line. The drum is constantly rotating, and when a generatrix corresponding to a certain letter is positioned, the «A» for example, all the «A» of the line are printed simultaneously.
Wheel drum printers are similar, only each circumference can rotate independently. All the characters of the printing line are written at the same time, each type being previously positioned in its correct position.

Instead of an ink ribbon, these printers usually use a piece of inked cloth the width of the paper.

Bar printers
The characters are molded on a steel bar that moves from left to right at high speed, oscillating in front of the line to be written. The character set is repeated several times (usually three). When the molds of the characters to be printed are positioned in front of the positions in which they have to remain on the paper, some hammers are fired behind it, thus printing the line.

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

Chain printers
The fundamentals are exactly the same as for bar printers. Now the characters are engraved on the links of a chain. The chain is closed and constantly turning at high speed in front of the ink ribbon.

Thermal printers
They are similar to needle printers. A special heat-sensitive paper is used that blackens when heat is applied.

The heat is transferred from the head through a matrix of small resistances in which, when an electric current passes through them, they heat up, forming the dots on the paper.

These printers can be:
Character: The lines are printed with a moving head.
Of lines: They contain as many heads as characters to be printed per line. They are faster.

Inkjet printers
The discovery of this technology was the result of chance. When a technician accidentally brought the soldering iron closer to a tiny cylinder full of ink, a projected drop of ink came out, giving rise to ink injection by thermal process. The first patent referring to this type of printing dates back to 1951, although until 1983, when Epson launched the SQ2000, they were not reliable and cheap enough for the general public.

Currently there are several technologies, although there are very few manufacturers worldwide that produce them, most of them from the same manufacturer with a brand set by the one who sells them. Canon (which supplies parts to Hewlett Packard) and Olivetti are the biggest of this type.

The physical foundation is similar to that of video screens. Instead of transmitting a beam of electrons, a jet of ionized ink drops is emitted, which is deflected along its path by electrodes according to the electrical charge of the drops. The character is formed by the ink striking the paper. When not writing, the ink drops are diverted to a return tank, if it is continuous flow, while those that are on demand, all used with PCs, the ink only circulates when needed. The characters are formed according to a dot matrix. These printers are bidirectional and there are models that print in different colors.

An example of ink printing application is batch marking and expiration date on milk bottles. This process is carried out with the continuous circulation printing system. The bottle marking equipment suffers a progressive degradation in the ink they contain, due to the technological process of operation. the continuous ink circulation system causes an ink particle to pass through the print head many times before being projected. When the ink undergoes pressure, comes into contact with the air and undergoes the charge of the electrostatic plates, it loses electrical properties, part of the solvent evaporates and suffers contamination due to dust and humidity in the air.

The contamination that the ink suffers with the contact of the air, causes worse printing quality, reaching a time when the ink has to be changed. The equipment incorporates a central deposit for easy and instant change that notifies 24 hours in advance of the moment of substitution. The central tank incorporates the main ink filter, so it can be changed without intervention each time the tank is replenished.

Electrostatic
printers Electrostatic printers use special electrically conductive paper (metallic gray in color). The shape of the characters is produced by electrical charges that are fixed on the paper by means of a row of nibs that span the width of the paper. After the line is electrically formed, it is passed, advancing the paper, through a tank where it is sprayed with a liquid containing suspended toner particles (carbon powder). The particles are attracted to the points that make up the character. These line printers are very fast.

Laser
printers These printers are currently of great importance due to their high speed, print quality, relative low price and the ability to use normal paper.

Its foundation is very similar to that of photocopying machines. The page to be printed is transferred to the paper by contact, from a drum that contains the image impregnated with toner.

Printing is done by laser radiation, directed on the drum whose surface has electrostatic properties (it is a photoconductive material, such that if light falls on its surface, the electrical charge of that surface changes).

LED printers
They are analogous to lasers, with the only difference that the image is generated from a row of diodes, instead of a laser. Being a fixed device, they are more compact and cheaper, although the quality is worse. Some of those that are advertised as lasers at a cheap price are of this technology, for example Fujitsu and OKI.