Printers

A printer is an out put device that prints characters, symbols and graphics on paper. The printed output is called hard copy. Print resolution is commonly measured in dots per inch(dpi). Different categories of printers are as follows:

• 1. Impact Printers:

An impact printer works like a typewriter. It prints characters or images by striking a print hammer or set of pins against an inked ribbon. The ink is pressed from the ribbon on the paper to produce the output. Impact printers are the oldest print technologies which are still produced. The impact printers are used where low-cost printing is required. Three most common forms of impact printers are  

1.dot matrix printers,

2.daisy wheel printer 

3. line printer.

2. Non Impact Printers:

A non impact printer prints characters and graphics on paper without striking paper. The characters are printed on paper with different means such as laser. Some printers use spray ink while others use heat and pressure to create images. These printers are faster than impact printers. However, they are more costly than impact printers. The produce no noise during printing. The print quality of non-impact printers is better than impact printers.

Different kinds of non-impact printers are as follows:

• Laser Printer

• Inkjet Printer

•  Thermal Printer

• Laser Printer:

LASER stands for Light Amplification by Stimulated Emission of Radiation. The laser printer is a non-impact printer. Its working is similar to photocopying machine. It uses laser beams to burn special powder on the page to create a permanent image. The powder is contained in the toner. Laser printer prints complete page at a time. It is also known as page printer. The printing speed of laser printers for home and small office user is 12 to 45 pages per minute (ppm). The printing speed of laser printer for large business user is 150 ppm or more. The speed depends on the contents being printed. The plain text i printed faster than graphics. Laser printer prints text ad graphics in high quality resolution. A typical laser printer provides a resolution of 1200 DPI or more. It also prints at higher speed than inkjet and dot matrix printers. It does not make much noise. Laser printer is mostly used in the business field. The black and white printing cost of laser printer is less than inkjet printers. Laser printers are available in black and white as well as color models.

•  Inkjet Printer:

An ink-jet printer is a type of non-impact printer. It prints characters and graphics by spraying tiny drops of liquid ink on paper. These printers can produce quality text and graphics in both-and-white and color including photos. A typical inkjet printer provides a resolution of 600 DPI or more. The price of inkjet printers is less than laser printers. However, they are slower than laser printers. Most inkjet printers can print from 10 to 35 pages per minute. However, they print graphics and color at slower rate. The print quality of inkjet printers is higher than dot matrix printer. They are also comparatively inexpensive.Most inkjet printers usually have two print cartridges. One cartridge contains black ink and the other contains color.

• Thermal Printer: 

Thermal printer is a printer that uses heat process to transfer colored dyes or inks to the paper. Thermal printer is the best color printers currently available but it is also very expensive. It was originally used only in scientific labs to record data. This printer is used to produce very high-quality color artwork and text. Professional applications requiring very high image quality such as photo studio, medical labs and security identification systems use thermal printers.The cost of this printer is thousands of dollars and it prints images in a wide range or sizes.

4. Photo Printer:

Photo printer is a color printer that is specially designed to print high-quality photographs. It is also called snapshot printer. Some photo printers print photos of one or two sizes only. Many photo printers have a built- in card slot. The printer can print digital photos directly from a media card. It means that there is no need to transfer the images from media card to the computer to print them. Some photo printers also have build-in LCD color screens. The user can view pictures before printing them. Some photo printers also have built-in LCD color screens. The user can view pictures before printing them.
5. Portable Printer:

Portable printer is a small, light - weight and battery- powered printer. It can be used by mobile users to print images from a notebook computer, Table PC or PDA while traveling. Its size is a bit wider than the page on which it prints. Portable printer fits in briefcase easily. Many printers connect to parallel port or USB port. Some portable printers have built in wireless port to communicate with computer wirelessly.
 6. Label and postage Printer:

Label printer is a small printer. It prints on an adhesive type material that can be placed on different items like envelopes, packages, CDs, toys etc. Many label printers also print bar codes. Postage printer is a special type of label printer. It has a built-in digital scale. It prints postage stamps. It allows the users to buy and print digital postage from their personal computers. The digital postage is also called Internet postage.