In office technology and data processing, a printer is a peripheral device of a computer for outputting data (e.g. texts, characters, numbers, graphics , photos , diagrams, etc.) on a two-dimensional carrier medium, usually paper . The process of generating pressure is called "printing", the result (the printed product ) is called "printout", "printing unit" or "printing result".
Photocopiers can also be viewed as printers in the broader sense: By scanning in or simultaneously exposing the original, an image of the original is created in these devices and this is then printed. Newer copiers can also be used as printers in the conventional sense. So-called multifunctional devices work as scanners, printers, fax machines and offline copiers.
Plotters bring the graphic elements (lines, letters) to be printed onto the print medium as vector graphics by continuously moving the print head or cutting head. The writing instrument is a special form of the plotter. Writing implements are used to produce reproduced signatures on mass letters. Line recorders are used to map measured values over a longer period of time.
There are two types of printers: printers with a stop and printers without a stop. Printers with a stop are in direct contact with the medium to be printed, while printers without a stop do not touch the medium.
Printing machines are used for printing tasks on a larger scale.
In the first half of 2012, 370,000 printers were sold to end users in Germany.
For example, there were precursors to computer printers
- electric typewriters ,
- the wax matrix duplication or hectography ,
- Calculating machines with receipt printing,
- electric metal typesetting machines .
But Charles Babbage had already planned a (decimal number) printer and a curve plotter for the Analytical Engine in 1837 . Due to the high expected costs of building this extensive precision engineering machine, neither the analytical engine nor its print output stage was ever built.
Inkjet printers are printers that spray very small droplets of ink onto the medium to be printed (paper, packaging, bottles, eggs, etc.) without impact. Classified according to the type of character display, these printers are dot matrix printers . The forerunners of inkjet printers are technical and medical devices that record measured values as ink curves on paper. They were followed as the first ink jet printers by the continuous ink jet printers, which used a continuous ink jet that was electrostatically deflected as required . This process is still used - in an improved form - in some high-quality inkjet printers. In normal inkjet printers, droplets are thrown from nozzles onto the paper only when required (drop on demand) in order to create individual dots (average size 0.3 to 0.4 mm). These droplets are created either in the bubble jet or in the piezo process. The resolution that the inkjet printer achieves depends primarily on how many nozzles the printhead has and how they are controlled. Simple inkjet printers achieve around 300 to 360 dpi, more powerful 1200 dpi and more. A new variant of the bubble jet technology, the so-called drop modulation technology, which uses two heating elements whose different control influences the drop size, achieves smoother gradients through different point sizes.
Such printers are relatively inexpensive and quiet to buy and deliver print results in good to very good quality. Compared to other printing processes, however, the consumption costs are relatively high; in individual cases the price for a set of replacement ink can reach or exceed the purchase price of the device, but this depends on the purchase price of the device. As a rule, the following applies: expensive printer, inexpensive ink and vice versa. The prices here are not due to technical reasons, but due to marketing. In particular, the so-called “ locking ” of the ink cartridges used by microchips prevents the use of alternative (cheaper) ink cartridges or the refilling of empty cartridges using built-in consumption meters. Through these practices, manufacturers are increasingly securing exclusive access to the highly profitable market for ink consumables.
There are inkjet printers available as black and white and color printers . The latter are often equipped with several print heads for the different basic colors. It is also possible to work with gold or silver paint or with paints that dry under UV light. A special form are high-speed printers on assembly lines, for example to print the use-by date on food bottles or a code on eggs.
Since ink is used for printing, there are some typical problems: The water-soluble inks or the prints made with them are often not lightfast and often not (very) waterproof. Certain types of paper can curl, and some decorative papers are completely unsuitable for inkjet printing because the ink does not dry and smudges when touched. If the printheads are not used for a long time, they can dry out.
Laser printers are photoelectric printers that work on a similar principle to a photocopier. The laser printer uses an image drum , the usable width of which generally corresponds to the width of an A4 page. The circumference of the imaging drum is smaller than the length of a DIN A4 page, so that the drum has to rotate several times per page. The drum is statically charged. It rotates and is described point by point by a laser beam moving back and forth line by line (with simple laser printers usually with about 600 × 600 dpi ; with high-quality printers a significantly higher resolution of 1,200 × 1,200 dpi or used above). If the beam hits, the charge is removed at the respective points. If no information can be obtained, the laser remains off for the corresponding point and thus the charge remains unchanged. Whether and how the laser is activated depends on the data in the application program (graphics, text, etc.). This creates an invisible negative of the later printout on the imaging drum. Is on the image drum toner powder applied, exactly the same charge as that of the drum. It only sticks to the places where the laser has deleted the charge.
This toner image of the data is then placed on statically charged paper and is fixed there by heating . The laser printer is a so-called page printer. It always creates the complete image of a page and then prints the entire page, even if only a short text or only a small graphic is to be reproduced.
In terms of the basic principle, color laser printers differ from monochrome laser printers (also known as "black and white laser printers") only in that additional toner containers (and separate exposure units) are available for the individual colors (cyan, magenta, yellow and black, see CMYK color model ) stand. The laser beam exposes the four image drums, one for each toner color, to the respective toner image for each print . With them, the individual basic colors are printed on top of one another with the appropriate toner and then fixed.
LED printers work on the principle of laser printers. However, instead of the laser and deflection mirror unit, a smaller LED strip is used, which covers the entire width of the paper. Among other things, high reliability and service life are considered advantageous.
LCD / LCS printer
Abbreviation for liquid crystal display / shutter printer. These are photoelectric printers that use basic principles similar to laser printers or LED printers. Instead of using a moving laser beam, they use a bar that is as wide as one side and contains 2,400 LCD elements. The imaging drum to be exposed rotates past it. The individual LCD elements are controlled according to the data to be output and then either let the light of a powerful lamp through or darken it. Accordingly, charges on the imaging drum are removed, reduced, or left unchanged. The rest of the process corresponds to that of the laser printer. Due to the similarity, LCD / LCS printers are often referred to as laser printers. They too produce the harmful ozone in the company .
In contrast to other technologies, the print medium of impact printers is mechanically stressed by stops.
Type wheel printer
These printers work much like a type wheel typewriter . The letters are created by using a hammer to hit the types of a rotating type wheel against the paper through a ribbon . The hammer is usually powered by a permanent magnet that is located in an electromagnet . The type wheels are interchangeable, interchangeable and mostly available for different fonts . The printing speed is usually 15-30 characters per second. Professional devices also achieve much higher speeds of up to 80 characters per second. The typeface of the text printouts is of very good quality. The graphics capability of such printers is usually limited to drawing lines and line-based shapes, such as tables. It is necessary, however, that proportional fonts are used, as is usual with these printed works, or that another form of spacing control or formatting takes place. The devices are very suitable for making copies .
Print wheel printers were mainly used for correspondence in the 1980s. The robust devices for mass printing of forms were used by companies and authorities until well into the 1990s. Today they are no longer of any importance due to their low speed, high noise levels and lack of graphics capabilities.
Ball head printer
The ball head printer works on the principle of the ball head typewriter .
Unlike with the type wheel printer, the type wheel does not move like a round disk on which the individual characters are attached as "stamps", but a round print head. This ball head rotates quickly, tilts the head around several levels and stamps on a ribbon when the right “stamp” is in front of the paper. This then prints through on the paper behind it. This printing method was initially replaced by type wheel printing units, and later by laser or inkjet printers.
Examples of line printers are type roll printers , chain printers , drum printers, and tape printers. With this type of printer, in contrast to the dot matrix printer or character wheel printer, entire lines are printed at once, not individual letters or parts of them. They were used in data centers to quickly print large amounts of paper, for example log files, payrolls, etc. In the age of dot matrix printers, they were the fastest printers with up to 1,500 lines per minute. Elaborate paper guides ensured that the continuous paper with an edge perforation could be printed cleanly at the high speed. Using a mechanical format control, different paper formats could be set, which ensured a corresponding page feed. The color was transferred to the paper with wide, color-soaked strips of fabric.
Dot matrix printer
Dot matrix printers are dot matrix printers that use needles instead of whole letters to put dots onto the paper, which visually combine to form letters. Often continuous paper (tabulating paper ) is used. A decisive advantage over other printers is the ability to make copies in one operation, which is why such printers can still be found in many medical practices and companies today. Dot matrix printers can also be used to print simple black and white graphics. However, they make a lot of noise when printing.
Metal paper printer (electric erosion printer)
A metal-coated paper is heated by electricity from a print head at the areas to be printed and thus blackened. These printers have a simple structure, allow similarly compact sizes as thermal printers and do not require a ribbon , but require expensive paper. They never found a breakthrough in the mass market, but always remained a niche product for special purposes, e.g. B. as an accessory for home computers such as the Sinclair ZX series . Until the end of paper roll production, they were rarely used in cash registers. They have mainly been replaced by the thermal printer, which is recommended for similar uses. On the other hand, his printouts are lightfast, but sensitive to skin oil (nickname among other things "finger printer").
Solid ink printer
Solid ink printers, also solid ink printers or wax printers, are printers that print with drops of wax . Since the colors are not transparent , the color droplets are placed next to each other and fused again in the printer's fusing unit . Wax printers are sometimes also referred to as solid ink printers or phasers.
For printing, wax cubes (usually in the colors black, magenta, cyan and yellow) are melted in the device. The toner wax cubes are dust-free and can be refilled while printing - without getting your hands dirty. The fuser does not generate ozone , but it may smell wax during operation.
Each time the device is switched off or on, the spray nozzles are emptied, which greatly increases toner consumption. After switching on, ten to twenty minutes warm-up time before the first printout is not uncommon. To circumvent this, the devices are left switched on, so that the wax melt in the printing unit always remains liquid due to continuous heating, but the power consumption in stand-by mode is very high.
The printers stand out i. d. Usually through strong, true-to-color and lightfast colors, (with long print runs) low printing costs and ease of maintenance. They are mainly used for proof prints in prepress and in the advertising industry . The disadvantage is that the documents are not scratch-resistant due to their wax layer, cannot be written on with aqueous inks (e.g. from ballpoint pens ) and are very sensitive to heat, and they are difficult to process further (for example, no lamination possible).
Direct thermal printer
With direct thermal printers, heat-sensitive thermal paper is heated by a print head at the areas to be printed. These printers are also simple in design, allow extremely small designs, depending on the intended use, and do not require a ribbon , but expensive paper, which also yellows over time, so that the printout is no longer or only poorly visible after about half a year. In the past, often used in fax machines , this technology is now mainly used in receipts , ticket machines or label printers .
Thermal transfer printer
Thermal transfer printers are mainly used in the field of high-quality color printing, such as photo or barcode printing . Different colored foils are melted and applied to the paper. However, since the ribbon can only be used once, these printers are expensive to operate.
Dye sublimation printer
For this printing process, ribbons or foils are used to which dyes are applied. By heating, the dyes are sublimated , d. H. evaporated without prior liquefaction and evaporated into the medium to be printed, usually paper. Typical areas of application are the graphics industry, prepress applications , image / photo processing and advertising agencies .
Printer according to purpose
In general, in the small office and home office sector (small offices and private users, sometimes referred to as SOHO for short), the number of pages that can be achieved and the costs per page are of little importance because the print volume in this area is small. Only inexpensive inkjet printers and some laser printers fall into this category today. In this market segment, the printing costs for ink and laser printing are gradually converging. A simple four-color process is common here for inkjet printers. The paper formats are seldom much larger than A4.
For larger offices and work groups, not only the print quality but also the total costs are decisive. The systems should be usable over a longer period of time and even under full load with low side costs. In this segment you can currently find almost only LED and laser printers.
Well-known manufacturers are Canon, HP, Konica Minolta, Kyocera Document Solutions, Lexmark (spun off from IBM in 1991), RICOH, Sharp, Xerox.
Large format printer
The large format printer segment includes a wide range of applications, including technical applications such as the printing of plans as well as the production of posters for outdoor advertising.
Important manufacturers are Canon, HP, RICOH, Xerox, Océ, ROWE
Applications here are invoice printing for authorities or mail order companies, account statement printing for banks, i.e. the production of all kinds of printed matter in large volumes . Book-on-demand applications have been particularly popular since the late 2000s . Instead of warehousing, production only takes place when a book is also in demand.
Depending on the application, the need for quality, page yield or printing costs can predominate. Larger office printers are sometimes used in this segment. Laser printers with page yields of up to 160 ppm B / W are currently still common, but ink printers with up to 220 ppm in color are currently emerging. Chain printers , which were the 'workhorses' of this printer class until the early 2000s, are no longer to be found today and have been replaced by laser printers. Machines of this class are also known as high-speed printers.
In 2004, RICOH bought Hitachi Printing to broaden its range of production printing. The joint venture with IBM (IBM Infoprint Solution) marks a further milestone for RICOH in this area since 2007.
Important manufacturers in this area are Konica Minolta , Ricoh , Océ , Xerox and Canon . Canon's involvement in this market led to the expansion of the group to include the Dutch printer manufacturer Océ in mid-November 2009, with Canon now covering the entire spectrum of digital printing machines in all performance classes.
With photo printers, the focus is generally on the quality that can be achieved. Special papers and, in the case of professional devices, also pigmented inks are used to achieve a corresponding quality. The papers have surface structures that are similar to those of various photo papers . In addition, they are highly absorbent on the surface, but hardly water-permeable in the paper itself. This and the pigmentation of the ink can reduce the penetration of the print onto the reverse side. Low-cost copies use 4 to 6 colors of ink. It is common here to use a lighter gray ink in addition to the pigmented black. More complex systems rely on pigmentation of all colors and also use gamut- expanding inks such as orange, blue and red.
Paper formats up to A3 + are possible.
These can endlessly print out labels from rolls or fan folders. Most of these printers work on a thermal transfer or thermal direct basis. A heat-sensitive label is sufficient for direct thermal printing, as this printing technique does not require a ribbon. A wax, wax / resin or resin ribbon is required for thermal transfer printing. Each ribbon meets different requirements for different label materials. Only monochrome prints are possible. These printers can also be equipped with label dispensers to remove labels individually. They are available from small desktop printers to industrial printers and also as mobile devices. They have established themselves primarily in trade and industry in order to produce barcode labels flexibly and also in small quantities. Today, high-performance industrial devices print at speeds of around 30 cm per second with low resolutions (150–200 dpi are sufficient for barcode readers). Newer types of printers also run "stand-alone" and no longer require a connection to a PC. The data for the labels are stored internally or on memory cards, variable data are entered via a connectable PC keyboard.
There are liquid (e.g. water-soluble ) and powdered printing inks.
The type of paint application also depends on the material:
- Via a color-soaked textile tape or cloth that is printed on by letters (letter printing) or needles (dot matrix printer), thereby releasing ink onto the paper
- As a print through of an ink carrier film (as a sheet or ribbon)
- Using nozzles (inkjet printer, wax printer)
- Photoelectric toner application (laser printer)
Carrier or solvent, consistency and components of the paint are important for durability and resistance:
- liquid, dries by evaporation
- liquid, dries with UV light
- as a gel
- with toner powder
Print media can have different surfaces:
- Smooth surfaces, for example paper , cardboard , labels , signs , films, foils , circuit boards (see assembly printing ), etc. a. m.
- Fabrics and textiles
- (irregularly) shaped surfaces, for example on bottles, food (eggs, sweets ), packaging
In single-sided printers, a rubber roller is responsible for transporting the paper. This can lead to a paper jam.
Interface with the computer
In the 1990s, the IEEE 1284 standard (parallel or Centronics interface) was introduced, which, with its further developments EPP and ECP, became the predominant technology for connecting a printer. Previously, character-oriented printers (e.g. type wheel printers) were used for which the serial connection , for example , was sufficient.
Storage media can also be connected directly to some printers. The printer can then independently process data from such a medium (e.g. a memory card or a digital camera ). Today's printers often have a USB interface, via which they can also be connected directly to a computer.
Printer drivers integrated in the operating system provide the application programs with a uniform interface for printing. This means that printing is possible regardless of the type of printer used.
There are also printer drivers that do not output the input data via a physical printer, but write them to a file. For example, documents can be generated in the platform-independent PDF format.
The programming language for controlling printers is often referred to for short as printer language . A distinction is generally between PDL ( Page Description Languages, PDL) and Printer Control Languages . The former are languages that describe the appearance of a page (to be printed) at a very low level (from a hardware point of view ), but a higher level than a simple raster graphic . In such a programming language, the content of a page is described, for example, with vectors or even letters. The areas of application of Printer Control Languages (not to be confused with the Printer Command Language from Hewlett-Packard) overlap with those of Page Description Languages, but are generally more hardware-specific in that they contain direct commands for controlling individual components of a printer.
The most common interfaces include:
- ESC / P ( Epson )
- PostScript ( Adobe )
- PCL ( Hewlett-Packard )
- GDI ( Microsoft )
- HP-GL, HP-GL / 2 ( Hewlett-Packard )
- Portable Document Format (PDF)
- Variable Print Specification (VPS) (further development of PostScript)
- Prescribe II ( Kyocera Document Solutions )
In current operating systems (but also used in the days of punched card technology), printouts are usually first saved electronically and only actually printed later. The primary aim of this is to ensure that the relatively low processing speed during printing does not hinder internal processing. Such a printer (which is often only available once) can also be used for printouts from applications running in parallel - one after the other.
- In modern systems, operating system processes handle caching and then printing; The expression "virtual printing" is also used for this.
- In earlier times, the printing results were initially electronically generated by the computer program itself, e.g. B. output on magnetic tape and physically printed with special printing programs.
- In large organizations, printing is done in special printing centers. Many different printers can be controlled, duplicates can be created, paper changes can be automated, printing dates and priorities can be taken into account, etc.
Many models with a color option leave behind an almost invisible identification code ( tracking dots ) on the printouts . It is issued regardless of the user's settings. The device-specific identification code added to the printed documents is intended to enable individual documents to be assigned to specific individual printers. The corresponding function was originally intended to trace counterfeit money printouts.