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Printer

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What is Printer?

A printer is an external hardware output device that takes the electronic data stored on a computer or other device and generates a hard copy of it. For example, if you created a report on your computer you could print several copies to hand out at a staff meeting. Printers are one of the most popular computer peripherals and are commonly used to print text and photos.

A printer is a piece of computer hardware. It allows a user to print items on paper, such as letters and pictures. Mostly a printer prints under the control of a computer. Many can also work as a copying machine or with a digital camera to print directly without using a computer.

A printer is a device that accepts text and graphic output from a computer and transfers the information to paper, usually to standard size sheets of paper. Printers vary in size, speed, sophistication, and cost. In general, more expensive printers are used for higher-resolution colour printing.

 

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History of Printer:-

 

Mechanical printer

The first mechanical printer was invented by Charles Babbage, for use with the Difference Engine, which Babbage developed in 1822. Babbage's printer utilized metal rods with printed characters on each rod to print text on rolls of paper that were fed through the device.

Inkjet printer

While inkjet printers started being developed in the late 1950s, it wasn't until the late 1970s that they were able to reproduce acceptable digital images. These better quality inkjet printers were developed by multiple companies, including Canon, Epson, and Hewlett-Packard.

Laser printer

In the early 1970s, Gary Stark weather invented the laser printer while working at Xerox. He modified a Xerox 7000 copier to be a laser printer, by having a laser output electronic data onto paper. However, it wasn't until 1984 when Hewlett-Packard introduced the HP LaserJet that laser printers became more widely available and affordable. The following year, Apple introduced the Apple LaserWriter, which introduced PostScript technology to the printer market.

 

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How Printer work?

Millions of bytes (characters) of data stream into the printer from your computer.

An electronic circuit in the printer (effectively, a small computer in its own right) figures out how to print this data so it looks correct on the page.

The electronic circuit activates the corona wire. This is a high-voltage wire that gives a static electric charge to anything nearby.

The corona wire charges up the photoreceptor drum so the drum gains a positive charge spread uniformly across its surface.

At the same time, the circuit activates the laser to make it draw the image of the page onto the drum. The laser beam doesn't actually move: it bounces off a moving mirror that scans it over the drum. Where the laser beam hits the drum, it erases the positive charge that was there and creates an area of negative charge instead. Gradually, an image of the entire page builds up on the drum: where the page should be white, there are areas with a positive charge; where the page should be black, there are areas of negative charge.

An ink roller touching the photoreceptor drum coats it with tiny particles of powdered ink (toner). The toner has been given a positive electrical charge, so it sticks to the parts of the photoreceptor drum that have a negative charge (remember that opposite electrical charges attract in the same way that opposite poles of a magnet attract). No ink is attracted to the parts of the drum that have a positive charge. An inked image of the page builds up on the drum.

A sheet of paper from a hopper on the other side of the printer feeds up toward the drum. As it moves along, the paper is given a strong positive electrical charge by another corona wire.

When the paper moves near the drum, its positive charge attracts the negatively charged toner particles away from the drum. The image is transferred from the drum onto the paper but, for the moment, the toner particles are just resting lightly on the paper's surface.

The inked paper passes through two hot rollers (the fuser unit). The heat and pressure from the rollers fuse the toner particles permanently into the fibres of the paper.

 

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