Printers

By the end of this lesson you should
be able to:
1. Define a printer
2. Name the two categories of printers
3. Give three examples of impact printers
4. List area of application of impact printers
5. Outline the advantages and disadvantages of using
impact printers

Printer
a printer is a peripheral which produces a
representation of an electronic document on physical
media such as paper or transparency film

Impact printers
Impact printers rely on a forcible impact to transfer
ink to the media. The impact printer uses a print head
that either hits the surface of the ink ribbon, pressing
the ink ribbon against the paper (similar to the action
of a typewriter), or hits the back of the paper,
pressing the paper against the ink ribbon

Classes of printers
1. Impact Printers
2. Non impact printers

Examples of impact printers
1. Dot matrix
2. Drum printer
3. Daisy wheel
4. Chain printer

Dot matrix printer

“A typical dot matrix output”
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How Dot-Matrix works?
The dot matrix forms images one character at a
time as the print head moves across the paper.
Uses tiny pins to hit an ink ribbon and the paper
much as a typewriter does.
This printer arranges dots to form characters and
all kinds of images.
9 to 24 vertical column pins are contained in a
rectangular print head. When print head moves
across the paper, pins are activated to form a
dotted character image. These printers can produce
carbon copies along with the originals.
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“Advantages/Dis-advantages of Dot-
Matrix”
Advantages:
(1) In-expensive.
(2) Low per page cost.
(3) Energy efficient.
Dis-advantages:
(1) Noisy
(2) Low resolution
(3) Limited fonts flexibility
(4) Poor quality graphics output.
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“Daisy Wheel Printer”
A daisy wheel printer is
basically an impact printer
consisting of a wheel and
attached extensions on
which molded metal
characters are mounted.
A daisy wheel printer
produces letter quality
print and it can’t produce
graphics output.
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How Daisy wheel printer works?
In a daisy wheel printer, a hammer presses the wheel
against a ribbon which in turn makes an ink stain on
the paper in the form of a character mounted on the
wheel extensions.
These printers are very noisy as there occur great
movement during the printing. Its printing speed is
also very slow ,i.e. less than 90cps.
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Drum printers
Fixed font character is engraved onto a number of
print wheels
The wheels join to form a large drum and spins at high
speed and paper and ink ribbon are moved past a
print position

Advantages of a drum printer
Less expensive
Use less ink

Disadvantages of a drum printer
Very noisy
Low speed
Space consuming

Chain printers
Use type slugs linked together in a chain so as its
printing mechanism
The chain spins horizontally around a set of hammers
When a desired character is in front of the selected
print column, the corresponding hammer hits the
paper onto a ribbon and onto a character in chain

Advantages and disadvantages of impact
printers
Advantages:
(1) In-expensive.
(2) Low per page cost.
(3) Energy efficient.
(4) Use less ink
Dis-advantages:
(1) Noisy
(2) Low resolution
(3) Limited fonts flexibility
(4) Poor quality graphics output.
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