☰

• Device that prints text and graphics in the same format and shape which is displayed on the screen connected via printer cable or USB cable.
• Transforms digitally stored documents, graphics, text data on paper/hard copy.
• Speed of printer is measured in printed pages per minute.
• Printers can be shared in the LAN, Wireless networks or Ethernets.
• New types of printers are combined with printing, scanning and fax in a single unit.

Types of Modern Printers

Inkjet Printers:

Sprays small droplets of ink at high speed on the surface. They are reliable, quick, and inexpensive.

1) Continuous Flow:

• Produces continues flow of stream droplets by spraying ink out of the nozzle.
• Stream of ink is broken down into droplets of ink using ultrasonic waves.
• When ink is desired on the medium, only selected droplets are electro statically charged.
• Deflection plates are used to direct the ink onto the medium.
• Remaining ink which is not required is sent back to reservoir through gutter.

2) Drop on demand:

• Ink is sprayed from the nozzle when it is required.
• Ink is fired on medium pressure with the help of piezoelectric crystal.
• When sufficiently high voltage is applied the piezoelectric crystal expands.
• This minimizes the volume of the ink chamber and vice versa for low voltage.
• Color printers consists of three nozzles each for one basic color.

Laser Printers:

Uses laser beam to produce images with excellent text and graphics.
Used in high quality outputs.

Working:

• Consists of drum which is coated with a photo conductive material.
• As drum rotates the coating on drum gets electrically charged.
• Drum remains charged until it is struck by laser light.
• When laser light falls on drum it selectively discharges some area of the drum.
• This forms a negative image on the drum.
• Position of laser light is maintained by rotating polygonal mirror.
• Toner is a black plastic base ink powder.
• This powder gets attracted to the charged areas on the drum.
• Image on the drum is transferred to oppositely precharged paper.
• Toner is fused to the paper by hearing and applying pressure to form a permanent image.