Printers

Seite 1

Dot Matrix

A dot matrix printer is an impact printer that transfers characters by striking a pattern (from a matrix) through an inked ribbon and onto paper

The most common number of pins providing a higher resolution. 24-pins create a near-letter quality print and anything with less then 24-pins provides a draft quality print. The overall print quality of a dot matrix printer is quite poor when compared to that of other types of printers

The speed of dot matrix printers is measured in characters per second (CPS). Common speeds for a dot matrix printers are 32 to 72 CPS.

Dot matrix printers operate in either a font (letters, numbers and symbols) or dot-addressable (graphs and charts) mode.

Dot matrix printers can use either a friction feed or a tractor feed system to move paper though the printing assembly

Because dot matrix printers strike the image onto paper, it is a good printer to use when carbon-copy documents are being printed

The print head can become dangerously hot due to pin friction.

Dot matrix printers can be loud because printing takes place by pins physically striking the ink ribbon, paper, and the platen (a metal plate behind the paper)

Inkjet

Inkjet printers are quiet non-impact printers with ink stored in a reservoir. Bubble jet printers are the most popular form of inkjet printers

The ink reservoir is in a disposable cartridge that includes the printing mechanism

Bubble jet printers print by heating the ink and squirting it through tiny nozzles in the print head and onto the paper

The crispness of an inkjet printers image is usually rated as dots per inch or dpi. Ink jets range from 150 to over 1400 dpi

A new generation of inkjet printers produce photo-quality printouts when used with photo-quality paper

Photo-quality inkjet printers mix up to 16 drops of ink to form a single dot of color on the page

Inkjet printers feed single cut sheets of paper, from a feed tray, by clamping them between rollers ad advancing them one print line at a time, from top to bottom, and then placing the newly printed paper tray, other than the feed tray.

Inkjet printers are an inexpensive way to produce color printouts

Dye Sublimation (dye diffusion thermal photo)

A dye sublimation printer is a non-impact printer that uses film-embedded dye

The print head heats and passes over the film, causing the dye to vaporize and soak into the film paper

ye sublimation printing prints in transitioning colors rather than pixels

Produces photographic quality images

Solid Ink

Solid ink printers melt ink into the print head (which is as wide as the paper). The head jets the melted ink onto the paper as the paper passes by on the print drum (similar to the laser printing process).

Solid ink printers offer the following advantages:

Simple design

Excellent print quality

Easy set up and maintenance

The head takes as long as 15 to heat prior to printing

Thermal

A thermal printer is a non-impact printer that uses heat to cause a reaction on the specially treated paper

monochrome thermal paper is chemically treated to darken where heated (photosensitive). many cash registers use this type of printer for creating receipts

Color thermal paper is chemically treated to absorb color from a ribbon where heated

Ink is applied using the ribbon in a similar manner to a solid ink printer

the color system used by thermal printers is CMYK (cyan, magenta, yellow, and black)

The paper must make one pass for each application of a different color

The feed assembly takes the thermal paper off the roll and it sends it through the printer to the outside of the printer

Color thermal printers are very expensive, high quality, and operate quietly

Seite 2

Cleaning

The cleaning phase prepares the drum by; removing the previous image printed. It uses a rubber-cleaner blade to remove any excess toner on the drum and them it scrapes off the debris into a debris cavity. Next, a heat roller lubricated to ensure that enough heat will be evenly applied to transfer the next image printed. Then an electrostatic erase lamp neutralizes the electrical charges that remain on the drum from the previous printed image

Processing

The printer receives document to be printed from the connected computer and converts it into a bitmap raster image, which is divided into horizontal raster lines

Charging

The primary corona prepares the photosensitive drum for writing by causing it to receive a negative electrostatic charge. Depending on the printer, the primary corona will be wires or rollers

Exposing

A laser beam changes the charge on the surface of the drum in a pattern of pages image

Developing

the developing roller applies toner to the drum. The toner sticks to the charged ares on the drum

Transferring

The transfer roller charges the paper to attract the toner

Fusing

The fusing assembly attaches the toner to the paper using rollers that press and melt the toner to the paper. As the paper leaves the printer, a static eliminator strip removes the static charge from the paper.