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You have selected free tutorial of the Microsoft Corporation for the Microsoft Technology Associate (MTA) :
98-349: MTA: Windows Operating System Fundamentals : Module 5: Managing Devices :
Understanding Printing Devices
Microsoft Help:-
A printer is a device that prints text or illustrationed item/ images / graphicss on paper. There are many different types of printers. In terms of the technology utilized, printers fall into the following categories:
- Impact printers: It's makes contact with the paper. It usually forms the print image by pressing an inked ribbon against the paper using a hammer or pins.
- Dot-Matrix Printers: The dot-matrix printer are having print heads, which contain 9 to 24 pins and produce patterns of dots on the paper to form the individual characters. The 24 pin dot-matrix printer produces more dots that a 9 pin dot-matrix printer, which results in much better quality and clearer characters. The general rule is: the more pins, the clearer the letters on the paper. The pins strike the ribbon individually as the print mechanism moves across the entire print line in both directions, i-e, from left to right, then right to left, and so on.
- Daisy-wheel printers: a daisy-wheel impact printer can be used to get the quality of type as usually found on typewriters,. It is called daisy-wheel printer because the print mechanism looks like a daisy; at the end of each "Petal" is a fully formed character which produces solid-line print. A hammer strikes a "petal" containing a character against the ribbon, and the character prints on the paper. Its speed is slow typically 25-55 characters per second.
- Line printers: In business where enormous amount of material are printed, the character-at-a-time printers are too slow; therefore, these users need line-at-a-time printers. Line printers, or line-at-a-time printers, use special mechanism that can print a whole line at once; they can typically print the range of 1,200 to 6,000 lines per minute. Drum, chain, and band printers are line-at-a-time printers.
- Drum printer A drum printer consists of a solid, cylindrical drum that has raised characters in bands on its surface. The number of print positions across the drum equals the number available on the page. This number typically ranges from 80-132 print positions. The drum rotates at a rapid speed. For each possible print position there is a print hammer located behind the paper. These hammers strike the paper, along the ink ribbon, against the proper character on the drum as it passes. One revolution of the drum is required to print each line. This means that all characters on the line are not printed at exactly the same time, but the time required to print the entire line is fast enough to call them line printers. Typical speeds of drum printers are in the range of 300 to 2000 lines per minute.
- Chain printers A chain printer uses a chain of print characters wrapped around two pulleys. Like the drum printer, there is one hammer for each print position. Circuitry inside the printer detects when the correct character appears at the desired print location on the page. The hammer then strikes the page, pressing the paper against a ribbon and the character located at the desired print position. An impression of the character is left on the page. The chain keeps rotating until all the required print positions on the line have filled. Then the page moves up to print the next line. Speeds of chain printers range from 400 to 2500 characters per minute.
- Band printers A band printer operates similar to chain printer except it uses a band instead of a chain and has fewer hammers. Band printer has a steel band divided into five sections of 48 characters each. The hammers on a band printer are mounted on a cartridge that moves across the paper to the appropriate positions. Characters are rotated into place and struck by the hammers. Font styles can easily be changed by replacing a band or chain.
- Non-impact printers Non-impact printers do not use a striking device to produce characters on the paper; and because these printers do not hammer against the paper they are much quieter. Following are some non-impacted printers.
- Ink-jet printers: Inkjet printer has same working principle with needle printer. The difference between two lies in printing head structure. For Inkjet printer print head, it is composed of thousands of ink channels of extremely tiny diameter. They are also orifice quantity which directly determine inkjet printer printing precise. Each interior channel is attached with implementing abrasion or heat generating unit. Printing head of inkjet printer works like this. When printing head control circuit receives driving signal, it instantly drives these implementing units to produce vibration which extrudes ink in channel to spray. In another way, it generates high temperature to heat ink in channel and generates bubble to extrude ink to spray out of orifice. When ink sprayed reaches printing paper, picture generates. Structure and working principle of laser printer These printers are a better choice if user uses one color more than other colors. These printers produce
less noise and print in better quality with greater speed.
- Laser printers Laser printers produce images on paper by directing a laser beam at a mirror which bounces the beam onto a drum. The drum has a special coating on it to which toner (an ink powder) sticks. Using patterns of small dots, a laser beam conveys information from the computer to a positively charged drum to become neutralized. From all those areas of drum which become neutralized, the toner detaches. As the paper rolls by the drum, the toner is transferred to the paper printing the letters or other graphics on the paper. A hot roller bonds the toner to the paper. Laser printers use buffers that store an entire page at a time. When a whole page is loaded, it will be printed.
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