What is Printers
Printers are used for producing output on paper. There are a large variety of printers and printing devices which can be classified according to the print quality and printing speed.
These varieties of printers are:
Printing Technology – impact printers vs. non impact printers
Impact printers use variations of the standard typewriter printing mechanism where a hammer strikes paper through an inked ribbon.
A non Impact printer uses chemical, heat or electrical signals to produce symbols on paper. Some of these require special coated or treated paper to print characters on them.
Classification of printers on the basis of speed :
On the basis of speed printers are of following types
1. Character Printer : These printers can print only one character at a time. They work similar to a typewriter. The examples are Daisy Wheel Printer, Dot Matrix Printer and
Inkjet Printer.
(a) Daisy-Wheel Printer : This printer is similar to a ball-head typewriter. This type of printer has a plastic or metal wheel on which the shape of each character is embossed.
A hammer presses the wheel against a ribbon, which in turn makes an ink stain in the shape of the character on the paper. Daisy-wheel printers produce letter-quality print but cannot print graphics. The print quality of this impact printer is very low as is the speed. These are practically obsolete now.
(b) Dot-Matrix Printer : This is one of the most popular printers used for personal computing systems. These printers are relatively cheaper compared to other technologies and use impact technology.
In the 1970s and 1980s, dot matrix impact printers were generally considered the best tradeoff between expense and versatility, and until the 1990s they were by far the most common form of printers used with personal computers. Characters in this printer are formed by the combination of dots.
A Dot-Matrix printer creates characters by striking pins against an ink soaked ribbon. Each pin makes a dot and combinations of dots form characters and illustrations. The moving portion of the printer is called the print head.
Advantages
· Dot matrix printers, like any impact printer, can print on multi-part stationery or make carbon copies.
· Impact printers have one of the lowest printing costs per page. As the ink is running out, the printout gradually fades rather than suddenly stopping part of the way through a job.
· They are able to use continuous paper rather than requiring individual sheets, making them useful for data logging. They are good, reliable and ideal for use in situations where printed content is more important than print quality.
Disadvantages
· Impact printers are usually noisy.
· They can only print low resolution graphics, with limited color performance, and limited quality.
· These printers are slow. Speed can be 225 cps to 250 cps. Speed may vary from one printer to another.
2. Line Printer: As the name suggests a line printer is a high speed printer which is used to print one entire line of text at a time. Line printers are used to print large amount of data, printing labels, accounting work and other large business printing applications in data centers. These are fast printers ranging in speed from 300 to 2500 lines per minute. Examples are Drum Printers and Chain Printers.
3. Page Printer: These are very high speed printers which produce high quality output. Their speed ranges from10-25 pages per minute. These printers are commonly used today. They use modern Laser Printer technology and print a whole page at one go. There are many varieties of laser page printers and so their prices range from base level upwards.
Classification of printers on the basis of quality
The various types of printers based on print quality are as follows
1. Ink-jet Printer: The Inkjet printer works on inkjet technology and produces better quality printouts than dot matrix printers. These print by spraying a controlled stream of tiny ink droplets accurately on the paper forming either dot matrix or solid characters.
The printing quality of these printers is very good with a speed of 700 or more characters per second. These are non-impact and hence are relatively silent during the printing process. These printers are easy to use and can be used to print color pages.
Advantages
Compared to other printers, inkjet printers have a number of advantages. These are
· They are quieter in operation than impact printers.
· They can print finer, smoother details through higher print head resolution
· They can produce photographic-quality text and images.
Disadvantages
The disadvantages of Inkjet printers are :
· The ink is often very expensive.
· Many intelligent ink cartridges contain a microchip that communicates the estimated ink level to the printer; this may cause the printer to display an error message, or
incorrectly inform the user that the ink cartridge is empty.
· The very narrow inkjet nozzles are prone to clogging with dried ink.
2. Laser Printer : This is a high quality, high speed and high volume technology printer. In laser printers, a laser beam is used to produce an image on a drum. The light of the
laser alters the electrical charge on the drum wherever it hits it. The drum is then rolled through a reservoir of toner, which is picked up by the charged portions of the drum.
Finally, the toner is transferred to the paper through a combination of heat and pressure. Laser printers produce very high quality text and graphics but are expensive. The
technology used by them is the same as that of photocopying machines. The speed of laser printers varies from 10 pages per minute to 200 pages per minute. Laser printers
are also called page printers; because they print a whole page at one go.
Standard laser printers can be classified into two categories in terms of color:
· Monochrome laser printer, and
· Color laser printer
Monochrome laser printers use a single toner. Color laser printers use four toners to print in full color. These printers are about five to ten times as expensive as their monochrome siblings. Color laser printers are popular and are being widely used, in spite of their cost. To print documents with graphics and photographs a color laser printer is a good option. Print speed, quality, printer resolution, reliability and the costs of toner are the major deciding factors for choosing a printer.
Plotters
A Plotter is a device that draws pictures on a page as output, after receiving a print command from the computer. It is also called a graph plotter. In plotters pens are used to draw lines on the paper, which is placed in the plotter.
Plotters produce high quality diagrams on the paper and their output quality is good. Engineers, architects and planners use plotters to generate high quality, high-precision
graphic output of different sizes. For several design applications such as design of layout of an aircraft, car, and architectural design of a building and in other computer-aided
design applications plotter are very useful.
Plotter is of two types:
· Drum Plotter
· Flat-Bed Plotter
The drum plotters are generally smaller than flatbed plotters and they have lower resolutions than flatbed plotters. HP, Canon and Epson are the popular companies which manufacture good quality of platters.
Part I: State true or false.
1)
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Daisy-wheel printers prints high quality printing.
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True/False
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2)
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A Dot-Matrix printer is a character printer.
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True/False
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3)
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A Monochrome laser printer uses four toners.
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True/False
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4)
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Color laser printers use a single toner to print.
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True/False
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5)
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Laser printers are very cheap.
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True/False
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(1) False (2) True (3) False (4) False (5) False
Part II: Short answer type questions
1) What do you mean by speakers?
Computer speakers are output devices which produces sound as output. Computer speakers, or multimedia speakers, are external speakers, commonly equipped with a low-power internal amplifier. These are used to hear audio signals in a computer system.
2) What do you mean by printers? What are the various types of printers ?
A Printer is an output device and lets you take printouts of documents, pictures, and other files. It creates a hard copy of computer documents or files on a piece of paper. Whatever we see on the computer screen can be printed on a paper using a printer.
There are many different types of printers available in the market. Printers are mainly categorized into the following types:
Impact Printers
a) Line Printers 1. Drum Printers, 2. Chain Printers
b) Character Printers 1. Dot Matrix Printer, 2. Daisy Wheel Printer
c) Non impact Printer 1. Thermal Printers, 2. Inkjet Printers, 3.Laser Printers
3) What do you mean by plotters? Explain their characteristics.
A Plotter is an output device which is used to produce high quality graphics on paper. Engineers, architects and planners use plotters to generate high quality, high- precision graphics output of different sizes. For several design applications such as design of layout of aircraft, car and architectural design of a building and in other computer-aided design applications plotters are very useful.
4) What do you mean by a dot-matrix printer?
A Dot matrix printer or impact matrix printer refers to a type of printer with a print head that runs back and forth on the page and prints characters by impact, striking
an ink-soaked cloth ribbon against the paper, much like a typewriter. Its speed is 50 cps (character per second) to 400 cps. It has one of the lowest printing costs per page.
5) What do you mean by Laser Printers?
Laser printers are one of the best printers available due to their high quality, high speed and high volume technology of printing. These printers produce very high quality text and graphics. Speeds of laser printers can range from 10 pages per minute to 200 pages per minute.
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