Types of Printers

* Character Printer :

These are slow-speed serial devices which print one character at a time like a typewriter. The typewriting is always electrical and sometimes touch-button type.

* Daisy Wheel Printer :

It works on an entirely different principle. Beneath their covers, they have a spinning wheel with each letter and symbol marked at the end of a spindle. As the wheel spins, a hammer punches them against the ribbon at the right moment. Daisy wheel printers make sharper images on the page, but, they cost more and print at a slower rate than dot matrix printers.

* Line Printers :

1. It prints a complete line at a time.

2. Printing speed varies from 150-lines to 2500 lines per minute with 96 to 160 characters on a 15-inch line.

3. Six to eight lines per vertical inch are printed.

4. Usually 64 and 96 character sets are used with English letters.

5. Two types of Line Printers are available.

     i. Drum Printers : It consists of a cylindrical drum. The characters to be printed are embossed on its     surface.

     ii. Chain Printers : It has a steel band on which the character sets are embossed.

* Dot Matrix Printer :

1. Here a character to be printed is made up of a finite number of dots and so, the print head consists of an  array of pins.

2. Characters to be printed are sent one character at a time from the memory to the printer. The character code is decoded by the printer electronics and activates the appropriate pins in the print head.

3. Many dot matrix printers are bi-directional. i.e., they print from left to rights as well as from right to left on return. This enhances the speed of printing. 

4. The printing speed is around 300 characters per second.

* Inkjet printers :

1. It consists of a print head, which has a number of small holes or nozzles.

2. Individual holes can be heated very rapidly by an integrated circuit resistor. When the resistor heats up, the ink near it vaporizes and is ejected through the nozzle and makes a dot on paper placed near the head.

3. A high-resolution inkjet printer has around 50 nozzles within a height of 7 mm and can print with a resolution of more than 300 dots per inch.

4. Latest inkjet printers have multiple heads, one per colour, which allows colour printing.

5. The printing speed is around 120 characters per second.

* Laser Printers :

1. Here an electronically controlled laser beam traces out the desired characters to be printed on a drum. The drum attracts an ink toner on to the exposed areas. This image is transferred to the paper, which comes in contact with the drum.

2. Low speed laser printers, which can print 4 to 16 pages per minute, are now very popular and the unit cost is around Rs. 0.3 lakhs.

3. Very fast printers print 10,000 lines per minute and cost per unit is around Rs. 0.3 lakhs. These printers give excellent outputs and can print a variety of fonts. As these printers do not have a type head striking on a ribbon, they are known as non-impact printers.