In computing, a printer is a peripheral which produces a hard copy (permanent readable text and/or graphics) of documents stored in electronic form, usually on physical print media such as paper or transparencies. The world's first computer printer was a 19th century mechanically driven apparatus invented by Charles Babbage for his Difference Engine. Printers are routinely classified by the underlying print technology they employ; numerous such technologies have been developed over the years. The choice of print engine has a substantial effect on what jobs a printer is suitable for, as different technologies are capable of different levels of image/text quality, print speed, low cost, noise; in addition, some technologies are inappropriate for certain types of physical media Many printers are primarily used as local peripherals, and are attached by a printer cable or, in most new printers, a USB cable to a computer which serves as a document source. Individual printers are often designed to support both local and network connected users at the same time. In addition, a few modern printers can directly interface to electronic media such as memory sticks or memory cards, or to image capture devices such as digital cameras, scanners; some printers are combined with a scanners and/or fax machines in a single unit, and can function as photocopiers. Printers that include non-printing features are sometimes called Multifunction printers (MFP), Multi-Function Devices (MFD), or All-In-One (AIO) printers. Most MFPs include printing, scanning, and copying among their features. Printers are designed for low-volume, short-turnaround print jobs; requiring virtually no setup time to achieve a hard copy of a given document. However, printers are generally slow devices (30 pages per minute is considered fast; and many inexpensive consumer printers are far slower than that), and the cost per page is actually relatively high. However, as printers have improved in quality and performance, many jobs which used to be done by professional print shops are now done by users on local printers; see desktop publishing. As a student myself printer is very useful to me because a I need to print lecture sheet, document& assignment for that I need a printer that is good printing quality & less maintenances cost.

DIFFERENT TYPES OF PRINTER

Dot matrix printer

The term dot matrix printer is specifically used for impact printers that use a matrix of small pins to create precise dots. The advantage of dot-matrix over other impact printers is that they can produce graphical images in addition to text; however the text is generally of poorer quality than impact printers that use letterforms (type). Dot matrix printers can either be character-based or line-based (that is, a single horizontal series of pixels across the page), referring to the configuration of the print head. At one time, dot matrix printers were one of the more common types of printers used for general use — such as for home and small office use. Such printers would have either 9 or 24 pins on the print head. 24-pin print heads were able to print at a higher quality. Once the price of inkjet printers dropped to the point where they were competitive with dot matrix printers, dot matrix printers began to fall out of favor for general use. Dot matrix printers are still commonly used in low-cost, low-quality applications like cash registers, or in demanding, very high volume applications like invoice printing. The fact that they use an impact printing method allows them to be used to print multi-part documents using carbonless copy paper (like sales invoices and credit card receipts), whereas other printing methods are unusable with paper of this type.

Line printer

As the name implies, print an entire line of text at a time. Three principal designs existed. In drum printers, a drum carries the entire character set of the printer repeated in each column that is to be printed. In chain printers (also known as train printers), the character set is arranged multiple times around a chain that travels horizontally past the print line. In either case, to print a line, precisely timed hammers strike against the back of the paper at the exact moment that the correct character to be printed is passing in front of the paper. The paper presses forward against a ribbon which then presses against the character form and the impression of the character form is printed onto the paper. Line printers were the fastest of all impact printers and were used for bulk printing in large computer centers. They were virtually never used with personal computers. Line printers, better known as line matrix printers are widely used in the automotive, logistic and banking world for high speed and barcode printing. They are known as robust and durable printers that have the lowest price per page.

Ink-jet printer

An inkjet printer is a type of computer printer that reproduces a digital image by propelling variably-sized droplets of liquid material (ink) onto a page. It is capable of printing 300 dot per inch Inkjet printers are the most common type of printer and range from small inexpensive consumer models to very large and expensive professional machines. Most consumer inkjet printers, from companies including Canon, Hewlett-Packard, and Lexmark, use print cartridges with a series of tiny electrically heated chambers constructed by photolithography. To produce an image, the printer runs a pulse of current through the heating elements causing a steam explosion in the chamber to form a bubble, which propels a droplet of ink onto the paper. The initial price of ink jet printer is very low like Bangladeshi taka 3000-4000 and maintains cost is also lower then the other printer.

Laser printer

A laser printer is a common type of computer printer that rapidly produces high quality text and graphics on plain paper. As with digital photocopiers and multifunction printers (MFPs), laser printers employ a xerographic printing process but differ from analog photocopiers in that the image is produced by the direct scanning of a laser beam across the printer's photoreceptor. Laser printers have many significant advantages over other types of printers. Unlike impact printers, laser printer speed can vary widely, and depends on many factors, including the graphic intensity of the job being processed. The fastest models can print over 200 monochrome pages per minute (12,000 pages per hour). The fastest color laser printers can print over 100 pages per minute (6000 pages per hour). It is capable of printing 600dot per inch. ITS initial cost of buying the printer is very high like minimum 7000-98000 Taka. But maintains cost is very lower and it is capable of print faster than any printer.

Thermal printer

A thermal printer (or direct thermal printer) produces a printed image by selectively heating coated thermo chromic paper, or thermal paper as it is commonly known, when the paper passes over the thermal print head. The coating turns black in the areas where it is heated, producing an image. Two-color direct thermal printers are capable of printing both black and an additional color (often red), by applying heat at two different temperatures. It mainly used in print photo because it is capable of printing high quality of photo print and it is little bit expensive to maintains.

Plotter printer

A plotter is a vector graphics printing device to print graphical plots that connects to a computer. There are two types of main plotters. n plotters print by moving a pen across the surface of a piece of paper. This means that plotters are restricted to line art, rather than raster graphics as with other printers. Pen plotters can draw complex line art, including text, but do so very slowly because of the mechanical movement of the pens. Pen Plotters are often incapable of creating a solid region of color; but can hatch an area by drawing a number of close, regular lines. When computer memory was very expensive, and processor power was very limited, this was often the fastest way to efficiently produce very large drawings or color high-resolution vector-based artwork. Those are pen plotters and electrostatic plotters. Traditionally, printers are primarily for printing text. This makes it fairly easy to control, simply sending the text to the printer is usually enough to generate a page of output. This is not the case of the line art on a plotter, where a number of printer control languages were created to send the more detailed commands like "lift pen from paper", "place pen on paper", or "draw a line from here to here". Those printers are used to print large size of drawing and poster.

Conclusion

As a student I need to print various kinds of document such as lecture sheet, slides document there are two kinds of printer that can be used in this purpose Ink-jet and leaser printer .The Ink–jet printer is less initial cost to buy and maintenance cost is also low and but printing quality is lower and printing time is higher then the leaser printer. But the leaser printer is expensive to buy .It can be cost effective in large base printing. So I prefer Ink-jet printer is the most usefully one.