Untitled_4

Printers

1. Dot Matrix Printers

   • A print head, consisting of a number of pins, moves back and forth on a cartridge. Each pin is mounted on a spring with a magnet on the head and an electromagnetic above each pinhead. The printers microprocessor analyes the information from the computer and translates the instructios into a series of electrial impulses. The signals are sent so the selected pins push down onto the paper. Between the print head is an ink ribbon. The 'firing' pin heads impress a series of ink dots on to the page. These dots make the text/graphic being printed.
   • Strengths: Relatively cheap and fairly reliable
   • Limitations: Print quality is poor. They are also slow and nosy.

2. Ink Jet Printers

   • A controller receives information from the computer which is translated into instructions. The print head contains a series of nozzles and moves back and forth across the pages. Each nozzle takes ink from the cartridge, above the print head, and heats it to produce a small bubble of ink. The bubble pushes a droplet of ink out of the nozzle and on to the paper.
   • Cheap, reliable and good quality. Cost effectives for homes and small ofices
   • Slower than laser printers and cope less well with bulk printing

3. Laser Printers

   • The printers processors prepare the received data and then send a series of instructions. The print head contains a laser which emits a beam of light. The laser is switched on and off in a designated pattern creating an equivalent pattern of positively or negatively charged dots on the drum. The drum then picks up black powder from a toner cartridge. The arrangement of toner is then deposited on to the paper as it passes by the drum. The 'fusing system' uses heat and pressure to bind the toner to the paper. The drum passes a thin wire which emits a strong positive charge it is then prepared to receive another pattern of charged dots via the laser.
   • Fast, reliable and high quality, Quiet and can handle bulk printing.
   • Moe expensive than ink jets. Costly expensive