Printers

What is a printer?

• A printer is an output device which makes a human-readable representation of graphics or text on paper.
• The printed output is generally referred to as "hard copy". The printers takes the computer data and prints text and still images.

What are the categories of printers?

1. Impact printers makes contact with the paper. It usually forms the print image by pressing an inked ribbon against the paper using a hammer or pins. An impact printer has mechanism same as that of a type writer and are more noisy and slow compared to the Impact printers.
Examples of impact printers:

• Dot Matrix.
• Daisy Wheel.
• Drum Printer.
• Chain Printer.
• Line Printer.

2. Non-Impact printers used almost everywhere now, are faster and quieter than impact printers because they have fewer moving parts. Non impact printers form characters and images without direct physical contact between the printing mechanism and the paper.
Examples of Non-Impact printers:

• Inkjet.
• Laser.
• Thermal.
• Plotter.

Laser vs Inkjet Printers:

Laser	Inkjet
Laser printers produces digital images by scanning a laser beam across photo-receptors.	Inkjet printing creates a digital image by dropping spots of ink into paper.
Uses Powder toner catridge filled with fine powder and a heated fuser.	The catridge is filled with liquid ink
Prints high quality sharp text on the paper making it ideal for black and white printing.	Great for photos and image heavy documents making it ideal for color printing.
High buffer capacity.	Low buffer capacity
Fast for high volume printing.	Slow when printed in large volumes.
Low printing cost per page.	High printing cost per page.
Occupies more space and is noisy.	Occupies less space and less noisy than laser.
Requires a larger initial investment, but the toner catridges need replacing less often.	Inkjet printers are more economical to purchase but ink need to be replaced frequently and can be costly over a long term.
Ideal printer for office use where more pages has to be printed.	Ideal for domestic use where less number of pages has to printed.

Thermal Printers:

A thermal printer makes use of heat to transfer an impression onto paper.

Uses:

Due to technological advances, printing speed, portability thermal printers are more popular and widely used in:

• Airline
• Banking
• Entertainment
• Retail and whole sales
• Grocery
• Healthcare and Pharma
• Petrol Bunks etc....

Advantages:

• Easy to use.
• Inexpensive and portable.
• No involvement of catridges.
• More durable and faster in printing.

Disadvantages:

• Do not printout colors well.
• If too heated the print head could be harmed resulting in breakdown.

Dot-Matrix Printers:

• A type of impact printer that produces characters and illustrations by striking pins against an ink ribbon to print closely spaced dots in appropriate shape.
• They can produce even prints with carbon copy. 
• The resolution of the print depends on the number of pins (9-low, 24-high).

Uses:

• Used for receipt printing, especially when carbon copies are required.
• Used in retail outlets, ATM offices and Banks.

Advantages:

• Can print carbon copies.
• Less expensive.
• Low printing cost per page. Ink does not finish rapidly.
• Low maintainance costs.
• Printer lasts for long period of time.
• Can be used in rough environment as they are very strong.

Disadvantages:

• Low quality printing.
• Very noisy.
• Low speed printing compared to others.
• Print head may get damage due to bending of pins.

DPI:

• Dots Per Inch (DPI) is the measure of printer resolution indicating how many ink dots the printer can place in one square inch.
• Higher the DPI, the more sharper the image will be.