. PRINTER.

. PRINTER.

A printer is an output device that produces text and graphics on a physical medium such as a paper.  Printed information is often referred to as a Hard copy because the information exists physically and is more permanent form of output than that presented on a display device.

Printers are grouped into two categories.

(a)    IMPACT PRINTERS:  Impact printers form characters and graphics on apiece of paper by striking mechanism against an ink ribbon that physically contacts the paper.  Examples of impact printers include;

  (i) Dot Matrix printers.  A Dot matrix printer is an impact printer that produces

     printed images with a print head striking mechanism.  Dot matrix has a

     head with 9-24 pins which can pushed out to hit on the paper through a

     ribbon.  A higher number of pins on the print head means more dots are  

     printed, which results in higher print quality i.e a 24 pin printer has better

     print quality than a 9 – pin printer.

      The speed of a dot matrix printer is normally measured by the number

     characters per second it can print.

Advantages of dot matrix printers

➢    Dot matrix printers can print multipart forms.

➢    They can withstand dust environment, vibrations and extreme temperatures.

Disadvantages

➢    They are generally noisy because of the striking mechanism.

➢    Print quality is not as good as those from inkjet and LaserJet printers.

 (ii) Daisy wheel printers:  This is an impact printer that uses a wheel as a print

head.  As the wheel rotates, a hammer strikes the backside of the spoke and

presses it against the paper to print a character.

Advantages

➢    It can print letter quality characters.

Disadvantages

➢    The printing speed is very slow.

➢    It cannot print graphics.

(iii)  Ball Printer: A ball printer is an impact that uses a rotating ball as a print

head.  The printing characters are on the surface of the ball, which strikes a

ribbon to transfer the character onto a paper.

(iv) DeskJet printers: This has a head which is pushed against the paper to

     produce characters or graphics.  Its performance is relatively similar to

     inkjet printers.

(b)    NON IMPACT PRINTERS.

These use chemical lasers to form images that eventually become characters.  They form characters and graphics on a piece of a paper without actually striking the paper.  Examples include:

   (i)  Laser Jet Printers.  Laser jet printers are also known as page printers

        because they process and store the entire page before they actually print

        it.  The mechanism of how a laser printer works is similar to a

        photocopier.

  

                       

                                 Advantages

➢    Laser printers are generally quite and fast.

➢    They can produce high quality output on ordinary papers.

➢    The cost per page of toner cartridges is lower than other printers.

Disadvantages

➢    The initial cost of laser printers can be high.

➢    Laser printers are more expensive than dot-matrix printers and inkjet printers.

   (ii) Ink Jet printers: An ink jet printer is a non-impact printer that forms

        characters and graphics by spraying tiny drops of liquid ink onto a piece

       of paper.  Ink jet printers can produce letter quality text and graphics in

       both black and white and colours.

        The speed of ink jet printers is measured in pages per minute (ppm)

Advantages

➢    They are generally quite.

➢    They can produce high quality colour output.

➢     

Disadvantages.

➢    Specialised papers are required to produce high quality colour output.

➢    The ink cartridges and specialized papers are expensive.

➢    The ink may smear when printed on ordinary paper.

 

A comparison of Impact and Non-impact Printers

	Impact printers	Non impact printers
Advantages	1. Ideal for printing multipart forms because they can easily print through many layers of paper. 2. Can normally withstand dusty environment, vibrations and extreme temperature.	1. Generally much quieter than impact printers because there is no striking mechanism. 2. Can produce high quality output
Disadvantages	1. Generally noisy because of the striking activity. 2. Produce near letter quality (NLQ) print only, which is just suitable for printing mailing labels, envelopes or invoices	1. Cannot print multipart forms.

LESS COMMON TYPES OF PRINTERS

(a)    Line printer:  This is a high impact printer that prints an entire line at a time.  Line printers are often used with mainframes, minicomputers or with a network in applications such as manufacturing, distribution or shipping.

(b)   Thermal Printer: A thermal printer generates images by pushing electronically heated pins against heat sensitive paper.  Standard thermal printers are inexpensive but the print quality is also low.

(c)    Plotter: A plotter is a sophiscated printer used to produce high quality drawings that can be quite large (e.g with width up to 60 inches). Two basic types of plotters are pen plotters and electrostatic plotters.

(d)   Photo printer: A photo printer is a colour printer designed to produce photo quality pictures directly from the digital camera.

PRINTING METHODS:

The printer is an output device by which we can get hard copy of the output i.e on a paper.

     (i) Line printing: In this type of printing, the printer prints line by line.  The

         paper used on line printers is called continuous stationery  though varieties

        of paper can be used.

    (ii) Character printing: In this type of printing,  the printer prints one character

        at a time.  The printer or serial printer is slower than the line printer and also

        cheaper e.g dot matrix printer.

   (iii) Page printing: In this type of printing, the printer outputs page by page e.g

        laser jet printer.

Common factors to consider when buying a printer

➢    Page per minute (ppm)

➢    Memory of atleast 2mb

➢    Price of the cartridge or toner

➢    Availability of cartridges.

➢    Purpose for which the printer is going to be put to use.

➢    Printer drivers.  Most printer drivers are installed before a printer can print some work for you.