An output device is any device used to send data from a computer to user. Most computer data output that is meant for humans is in the form of audio or video. Thus, most output devices used by humans are monitors, projectors, speakers, headphones and printers.
A printer prints whatever is on the monitor screen onto a paper. A printer can print words, numbers or pictures. The speed of a printer is measured in cps (characters per second), lpm (line per minute), ppm (pages per minute), the faster the printing, more expensive the printer. Printer resolution is the more numerical measure of print quality that is measured in dots per inch (dpi).
Types of Printer
Mainly printers can be classified into two types:
- Impact Printers
- Non-Impact Printers
This type of printer strikes on a ribbon that strikes on the paper to form a character, like a typewriter. These are less expensive and old type of printers. Types of Impact Printer are:
- Dot Matrix: It forms characters using rows of pins which impact the ribbon on the top of the paper. These are bidirectional printers which can print left to right or right to left as well.
- Daisy Wheel: Characters on daisy wheel printers are formed on the ‘petals’ like typewriter keys. These are slowest type of printers. These are generally used in railways.
- Chain and Band Printers: This type of printer uses characters on a band or chain that is moved into place before striking the characters onto the paper.
Such type of printer does not involve actual contact with paper. It sprays ink onto paper to form characters. Types of Non-Impact printers are:
- Ink jet: It sprays ink onto paper to form characters. Quality of text and graphics is good in Ink jet printers.
- Thermal Printer: It uses heat on chemically treated paper to form characters. Fax machine, ATM, Shopping POS Machines uses this kind of printers.
- Laser Printers: It is the fastest type of printers and prints high quality graphics. It is the most expensive kind of printers. Eg: Photo Copy machines.
A monitor is the screen on which words, numbers and graphic can be seen. It is the most commonly used type of output device. Some of the features of a screen are:
- Size: It is measured as the diagonal size of a screen.
- Resolution: Resolution determines how much clear the picture will be. Pictures on a screen are made up of tiny dots. 1 dot on screen = 1 Pixel. The more the pixels per inch, the clear and more detailed the picture will be.
- Refresh Rate: This determine how fast the picture is redrawn on the monitor. It f the rate is low the picture will appear to flicker. 75 times per second or more is better and necessary for the high quality pictures.
Types of Screens
- Monochrome: This type of screen has one colour text on single colour background.
- Colour: It can display a numerous colours
- CRT: It uses a cathode ray tube and it is found on earlier type of monitors and TV screens.
- LCD: Liquid Crystal display, it is a thin flat screen and found in laptops, mobile etc.
- LED: Light emitting diode is the latest type of screens. These are thinner in size, consume less amount of power and have greater resolutions.
Speakers and Headphones
Speakers give us the sound as output for our computer. Some speakers are built in computer or some are attached it with separately.
Headphones are similar to speakers, they are smaller in size and they are worn on the ears. Only one person can use a headphone at a time.