is a popular computer printer that prints text and graphics on the
paper by using tiny dots to form the desired shapes. It uses an array of
metal pins known as printhead to strike an inked printer ribbon and
produce dots on the paper. These combinations of dots form the desired
shape on the paper. Generally they print with a speed of 50 to 500
characters per second as per the quality of the printing is desired. The
quality of print is determined by the number of pins used (varying from
9 to 24).
key component in the dot matrix printer is the ‘printhead’ which is
about one inch long and contains a number of tiny pins aligned in a
column varying from 9 to 24. The printhead is driven by several hammers
which force each pin to make contact with the paper at the certain time.
These hammers are pulled by small electromagnet (also called solenoids)
which is energized at a specific time depending on the character to be
printed. The timings of the signals sent to the solenoids are programmed
in the printer for each character.
printer receives the data from the computer and translates it to
identify which character is to be printed and the print head runs back
and forth, or in an up and down motion, on the page and prints the dots
on the paper.
3. Inkjet printers
Inkjet printers are most popular printers for home and small scale offices as they have a reasonable cost and a good quality of
printing as well. A typical inkjet printer can print with a resolution
of more than 300 dpi and some good quality inkjet printers are able to
produce full colored hard copies at 600 dpi.
An inkjet printer is made of the following parts:
· Printhead – It is the heart of the printer which holds a series a nozzles which sprays the ink drops over the paper.
cartridge – It is the part that contains the ink for printing.
Generally monochrome (black & white) printers contain a black
colored ink cartridges and a color printer contains two cartridges – one
with black ink and other with primary colors (cyan, magenta and
4. Laser Printers
printers are the most popular printers that are mainly used for large
scale qualitative printing. They are among the most popularly used
fastest printers available in the market. A laser printer uses a slight
different approach for printing. It does not use ink like inkjet
printers, instead it uses a very fine powder known as ‘Toner’.
Componetns of a laser printer is shown in the following image:
control circuitry is the part of the printer that talks with the
computer and receives the printing data. A Raster Image Processor (RIP)
converts the text and images in to a virtual matrix of dots. The
photoconducting drum which is the key component of the laser printer has
a special coating which receives the positive and negative charge from a
charging roller. A rapidly switching laser beam scans the charged drum
line by line. When the beam flashes on, it reverses the charge of tiny
spots on the drum, respecting to the dots that are to be printed black.
As soon the laser scans a line, a stepper motor moves the drum in order
to scan the next line by the laser.
developer roller plays the vital role to paste the tonner on the paper.
It is coated with charged tonner particles. As the drum touches the
developer roller, the charged tonner particles cling to the discharged
areas of the drum, reproducing your images and text reversely.
Meanwhile a paper is drawn from the paper tray with help of a belt. As
the paper passes through a charging wire it applies a charge on it
opposite to the toner’s charge. When the paper meets the drum, due to
the opposite charge between the paper and toner particles, the toner
particles are transferred to the paper. A cleaning blade then cleans the
drum and the whole process runs smoothly continuously. Finally paper
passes through the fuser which is a heat and presser roller, melts the
toner and fixes on the paper perfectly.
Difference between a Line Printer and a Dot Matrix Printer
Difference between a Dot Matrix and Thermal Printer