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Output Devices

Objectives :

After the completion of this lesson, students will be able to:

  • – define the output devices.
  • – know about the monitors and their types.
  • – differentiate between b/w and color monitor.
  • – differentiate between impact and non-impact printers.

The devices which are used to expose the processed data from the computer are called output devices.

An output device is responsible for providing the output in user readable form.

Some of the output devices are Visual Display Units (VDU) i.e. a Monitor, Printer, Graphic Output device, Plotter, Speaker, etc. A new type of Output device has been developed these days, known as Speech synthesizer, a mechanism attached to the computer which produces verbal output sounding almost like human speeches.

 Monitors

 Monitor is a standard output device to display the processed data. It is called visual display unit(VDU) and monitor also. A display device is the most common form of output device. It presents output visually on computer screen. The output appears temporarily on the screen and can be easily edited or erased. It is sometimes referred to as soft copy also. The display devices are also used in home entertainment systems, mobile systems, cameras and video games.

Types of monitors

  • a) CRT monitors
  • b) LCD monitors
  • c) LED monitors

CRT Monitors(Cathode Ray Tube)

A CRT monitor contains millions of tiny red, green, and blue phosphor dots in an array that glow when focused by an electron beam that travels across the screen to create a visible image. Red, green and blue are present in colour monitor, so they are called color or

RGB monitors. Black and white monitors do not have. A unit of image in the screen is called a pixel (picture element). A set of pixels create an image.

There is an electron gun at the narrow side of the CRT. The electron gun continuously fires the electrons to create an electron beam.The electron beam hits the  phosphorescent screen and the light is produced and the image is formed.

LCD Monitors

A LCD monitor is an output device which displays the output the visual form. The full for of LCD is Liquid Crystal Display.. a flat panel display. LCD monitors are based on the polariza of light, florescent light and crystal movement. The flores. light is polarized and the crystal plays a role of on and off of light by twisting. When light passes through the crystal it formie an image in the screen. LCD monitors are flat, light and easy available to display arbitrary images or fixed images with low which can be displayed or hidden, such as preset words, digits, displays, as in the digital clock or in calculator. 7 segment display clock or in calculator. 7 segment display is formed by any 7 different lines.

0123456789

They use the same basic technology, except that arbitrary images are made up of many small pixels, while other displays have larger elements.

 LED Monitors

Another flat-panel display monitor is LED. Light-emitting diode, or LED monitors are LCD type monitors, but they use backlighting to produce even brighter, more vibrant images, all while consuming less power in a thinner design than basic LCD computer monitors.

 Only the difference is the light source.

LCD uses florescent light source and LED uses the LED bulbs light source.

Printers

The devices which give the hardcopy as an output from the computers are called printers.

A printer is a peripheral device which gives output on paper. Most output of the printer is human-readable, but barcode printers are an example of an expanded use for printers.

  • a) Non-Impact Printer
  • b) Impact Printer

Non-Impact Printer

 Non impact printers do not make sound while printing. They are as follows:

  • Toner-based printers
  • Laser Printer

Laser Printer

Laser printer is a high quality fast printer based on laser beam and thermal heat. Other printers print characters or lines one by one but laser printer prints a page at a time. So, laser printers are very fast printers. Laser printers employ a xerographic printing process but differ from analog photocopiers in that the image is produced by the direct scanning of a laser beam across the printer’s photoreceptor. Xerographic is a dry copying process in which black or colored powder stick to parts of a surface copied Xerography remaining electrically charged after being exposed to light from an image of the document to be copied. The fastest models laser printer can print over 200 monochrome pages per minute (12,000 pages per hour). The fastest color laser printers can print over 100 pages per minute (6000 pages per hour).

Liquid inkjet printers(bubble jet printers)

Inkjet printers do not create sound while printing. There is no impact while printing. The inkjet printer injects the ink on the paper and prints. There is a cartridge full of ink and nozzle to inject the ink. Inkjet printers are the most commonly used type of printer, and range from small inexpensive consumer models to expensive professional machines.

Thermal printers

Thermal printer is a non-impact printer which is based on a selectively heat coated paper. The printing process occur when the heated paper passes over the thermal print head. Basically it is used in cash registers, ATMs, petrol pumps and fax machines. To print the color image special papers, different temperatures and heating rates are used.

Impact printers

Impact printers create impact sound while printing. There is an impact between paper and the printer head. For example, dot-matrix printer, line printer, daisy wheel printer etc.

Dot-matrix printer

Dot-matrix printer is an impact printer which creates sound while printing. The printer consists of a head with pins in it. The pin of the head of the printer strikes the paper with an inked ribbon to create a dot. The combination of the dots makes the character or figure on the paper.

The printer uses a matrix of small pins to transfer ink to the page. The advantage of dot matrix over other impact printers is that can produce graphical images in addition to text; however the text is generally poorer quality than impact printers that use letterforms (type). These prini make carbon copy also.

Ball printer

A ball printer is an impact printer having a ball like structure containing the characters surrounded its body. The letter to be printed comes in front of the paper and then the ball hits the paper with the inked ribbon, the character is printed.

Daisy wheel printers

Daisy wheel printer is an impact printer. The head of this printer is like a daisy flower. All the characters are placed at the end of the leaflet of the wheel. The wheel rotates very fast according to the instruction of the computer. A hammer is fixed at the back side of the wheel. Suppose we have to print a character “A” at the paper, the leaflet having “A” character comes at top just backside of the hammer and the hammer hits the leaflet, which hits the paper with inked ribbon in front of it and marks on the paper. Again next letter comes and hammer hits, and so on.

It is a character printer and slower than line printer. This printer can print a carbon copy also.

Line printers

Line printers print an entire line of text at a time. Line printers are very fast printers. These printers were used in the mainframe computers to print the printing request from hundreds of users. The printers are still in use.

Speakers

Speakers are the sound output devices which produces output of processed data in the form of sound. The speakers have an internal amplifier and power source.

The external speaker is connected to a computer to produce sound. the sound card receives the signal from the computer and sends to the speaker. Most computers have inbuilt speakers of low power and quality  but external speakers are connected to produce qualitative Cound. External speaker disables the internal speaker while working. The blue tooth speakers are the wireless speakers which need a Aux jack and compatible adaptor. The laptop computers have built in integrated speakers which are usually small and of restricted sound quality to conserve space.

 Graphic Plotters

 A plotter is a graphical output device which prints the large sized graphical objects. Mostly plotters are used to draw the figures of house, bridge, and other images designed by the engineers in auto CAD. Generally the big sized images are printed by the plotters.

a) A Drum Plotter

A drum plotter is a Pen-based plotter which uses colored pens to draw the image. The paper is attached in the drum which rolls the paper as the pen draws.

b) Flat based plotter

A flat based plotter is also the pen based plotter. Here the paper is fixed on the table and the pen which is attached device moves to draw the image. It is like drawing by

hand in the paper fixed on the table.

c) Electro plotter

An electro plotter does not have a pen to draw. Laser technology is used to print in this type of printer.

Points to remember

  • The devices which are used to expose the processed data from the
  • computer are called output devices.
  • The monitor is a standard output device to display the processed data.
  • The output appears temporarily on the screen and can easily altered or
  • erased, it is sometimes referred to as soft copy also.
  • The devices which give the hardcopy as an output from the computers are called printers. 5. There are two types of printers, impact and non impact.
  • 6. Laser, inkjet are the nonimpact and dot-matrix, line print
  • printers.
  • 7. An Impact printer creates sound while printing and a non
  • does not create sound while printing.
  • 8. A Laser printer uses laser-beam and thermal hit technology 9. A plotter is a computer printer for printing vector graphics 10. A speaker is an output hardware device that is connected     to a computer to generation sound.

Full forms:

  • 1. VDU: Visual Display Unit
  • 2. CRT: Cathode Ray Tube
  • 3. LCD: Liquid Crystal Display
  • 4. UPC: Universal Product Code
  • 5. EAN:European Article Number
  • 6. RCA: Radio Corporation of America

Computer terms

  • 1. Output device : The devices which are used to expose the processed data from the computer.
  • 2. Monitor: A standard output device to display the processed data.
  • 3. Softcopy : The output appears temporarily on the screen and can easily
  • be altered or erased.
  • 4. Printer : The devices which give the hardcopy as an output from the computer.
  • 5. Impact: making sound.
  • 6. Non-impact: not creating sound
  • 7. Plotter: a computer printer for printing vector graphics.
  • 8. Speaker: An output hardware device that is connected to a computer to generate sound.

Exercises

1. Answer the following questions.

a) What do you mean by output devices?

b) What is a softcopy?

c) What is a CRT monitor?

d) What is a pixel?

e) Why color monitors are called RGB monitors?

 f) What is the difference between LCD and LED monitors?

g) What is the similarity between LCD and LED monitors?

h) What do you mean by a printer?

 i) Differentiate between impact and non-impact printers?

j) What is a laser printer?

k] What is a plotter?

1 What is a speaker? How does it work?

Write true or false.

a) The output appears temporarily on the screen and can easily be altered or

erased, it is sometimes referred to as soft copy.

b) LCD monitors are older than CRT.

 c) LCD emits light directly.

d LCD and LED both are flattened screens.

e) Hardcopy output are harder like iron.

f) Dot-matrix printer is a non-impact printer.

g) A speaker converts electronic signal into sound system.

3. Fill in the blanks.

a) …………. is an impact printer having a ball like structure containing the characters surrounded its body.

b) …………………….. printers work by selectively heating regions of special

heat-sensitive paper.

c) A hammer ………………….. a wheel of petals “The Daisy Wheels”.

d) Computer speakers are ……………………. output devices.

4. Write the full form.

VDU, Pixel, CRT, LCD, LED, RCA

5. Choose the correct answer.

a) A standard output device to display the processed data

i) Mousep ii) RCA iii) Monitor iv) CMYK

 b) The output appears temporarily on the screen and can easily be  altered or erased.

i) Hardcopy ii) Pixeliii) Softcopy iv) Printer

c) A computer printer for printing vector graphics.

 i) Plotter ii) Alter iii) Printer iv) Sound maker

d) An output hardware device that connects to a computer to generate sound.

i) Computer ii) Speaker iii) Laser Printer iv) All of above

6. Match the following.

Plotter                     Screen

OR                           Cathode Ray Tube

Electron beam                        Paper

VDU                          Input device

 AutoCad

7. Project work.

Make a slide for an impact printer and a non-impact printer.

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