Printer working and construction

Type of printer
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Difference between Impact and non-impact printer:

      1)Impact printers operate by having an element strike the paper with ink ribbon in between them. 
          The printheads of non-impact printers do not strike the page. 

2.      Types :

·         Impact printer - Dot-matrix printer

·         Non-impact printer - Inkjet printer, laser printer and thermal printer

3.      Speed :

·         Impact printer - Low printing speed

·         Non-impact printer - Reasonably fast

4.      Quality :

·         Impact printer - Print quality lower in some types

·         Non-impact printer - High quality of output, capable of printing fine and smooth details

5.      Letter quality :

·         Impact printer - Produce near letter quality (NLQ) print only, which is just suitable for printing mailing labels, envelopes, or invoices

·         Non-impact printer - Letter-quality printouts

6.      Consumption :

·         Impact printer - Not commonly used today

·         Non-impact printer - Most commonly used printer today

7.      Tools :

·         Impact printer - Uses ink ribbon

·         Non-impact printer - Uses ink spray or toner powder

8.      Cost :

·         Impact printer - Less expensive 

·         Non-impact printer - More expensive

9.      Durability :

·         Impact printer - Reliable, durable (lasting for a long time)

·         Non-impact printer - Print head is less durable, inclined towards to clogging and damage

1)Dot matrix printer

Impact printer:

The printing mechanism works as follow. The permanent magnetic field holds the hammer spring in stressed, ready to strike position. The driver sends electrical current to hammer coil, which then creates electromagnetic field opposite to the permanent magnetic field. When both fields equalize, the energy stored in the spring is released to strike the hammer against the ribbon and prints a dot on the paper. The hammer printhing mechanism is shown in action at the picture bellow.

The line printer mechanism in action:

During printing process the print-shuttle vibrates in horizontal direction with high speed while the print hammers are fired selectively. So each hammer may print a series of dots in horizontal direction for one pass of the shuttle, then paper advances at one step and the shuttle prints the following row of dots

Refer:

http://mimech.com/printers/line-printer-technology.asp

2)Inkjet printer

 liquid ink in various colors being squirted onto paper and other media, like plastic film and canvas, to build an image. Its a non impact printer.

Ink is pressured by a ink supply pump and flows from the ink bottle to the nozzle.

The nozzle uses ultrasonic vibration to break a pressurized ink stream into small droplets as it leaves the nozzle.

The drops are ejected from the nozzle at high speed. They pass through the charge electrode tunnel / and then on between the deflection electrode.

Here the drops are deflected, by an amount which depends on the charge they were given by the charge electrode.

After the drops leave the region of the deflection electrode they continue to travel in their new direction until they pass out of the printhead and to the substrate.

Drops that aren't required for printing are caught by the gutter and subsequently recycled back to the ink bottle.

3)Laser printer

http://www.computershopper.com/feature/how-it-works-laser-printer