1. Course Name: Computer Application
LECTURE
Course Name: Computer Application
Topic: Output Devices

2. Output Devices
An output device is any piece of computer hardware used to communicate the results of data processing into human-readable form. Following are important output devices:
Monitors
Printer
Plotter
Speaker and Headphones
Speech synthesisers

3. Monitors
Monitors, commonly called as Visual Display Unit (VDU), are the main output device of a computer. It forms images from tiny dots, called pixels that are arranged in a rectangular form. The sharpness of the image depends upon the number of pixels.
There are two kinds of viewing screen used for monitors.
Cathode-Ray Tube (CRT)
Flat-Panel Display Monitor

4. Cathode-Ray Tube (CRT) Monitor
The CRT display is made up of small picture elements called pixels. The smaller the pixels, the better the image clarity, or resolution. It takes more than one illuminated pixel to form whole character, such as the letter ‘e’ in the word help.
A finite number of characters can be displayed on a screen at once. The screen can be divided into a series of character boxes - fixed location on the screen where a standard character can be placed. Most screens are capable of displaying 80 characters of data horizontally and 25 lines vertically. There are some disadvantages of CRT
Large in Size
High power consumption

5. Flat-Panel Display Monitor
These take up a lot less room on a desk and use less energy than the traditional, more bulky monitors. The visual quality of these monitors are very high.
The flat-panel display refers to a class of video devices that have reduced volume, weight and power requirement in comparison to the CRT. You can hang them on walls or wear them on your wrists. Current uses of flat-panel displays include calculators, videogames, monitors, laptop computer, graphics display.
The flat-panel display is divided into two categories
Emissive Displays - The emissive displays are devices that convert electrical energy into light. Example are plasma panel and LED(Light-Emitting Diodes).
Non-Emissive Displays - The Non-emissive displays use optical effects to convert sunlight or light from some other source into graphics patterns. Example is LCD(Liquid-Crystal Device)

6. Liquid Crystal Display (LCD)
Less space
Lighter
Low power consumption
Expensive
Limited viewing angle
Found on watches, calculators, digital cameras and notebook computers

7. Light Emitting Diode (LED)
Less space
Lighter
Very expensive
Provide higher contrast and better viewing angles than LCD monitor

8. What is display resolution
Describes the sharpness and clarity of image
The higher the resolution, the sharper the image and the more that can display on the monitor
What is dot pitch
Measure of the distance between pixels
Sometimes called pixel pitch
Smaller the distance between the pixels, the sharper the image
What is refresh rate
Speed at which monitor redraws images on the screen

9. What is a video card
Converts digital output from computer into analog video signal
Controls how display device produces picture
Also called graphics card or video adapter
How does video travel from the processor to a CRT monitor
Processor sends digital data to video card
Video card converts digital data to analog signal
Analog signal sent via cable to CRT monitor
CRT separates signal into red, green, and blue signals
Electron guns fire color signals to front of CRT
Image displays

10. Printers What is the resolution of a printer
Printer is an output device, which is used to print information on paper.
Output device that produces text and graphics on paper
Result is hard copy, or printout
What is the resolution of a printer
Sharpness and clarity of characters
Measured by number of dots per inch (dpi)
There are two types of printers
Impact Printers
Non-Impact Printers

11. Impact Printers Ideal for printing multipart forms
The impact printers print the characters by striking them on the ribbon which is then pressed on the paper
Ideal for printing multipart forms
Can withstand dusty environments, vibrations, and extreme temperatures
Characteristics of Impact Printers are the following
Very low consumable costs
Very noisy
Useful for bulk printing due to low cost
There is physical contact with the paper to produce an image
These printers are of two types
Character printers
Line printers

12. Character Printers
Character printers are the printers which print one character at a time.
These are further divided into two types
Dot Matrix Printer(DMP)
Daisy Wheel
Dot Matrix Printer
Dot matrix printers work by firing a row of pins, through an ink ribbon, onto the paper. The more pins the print head has the higher the quality of the print, most dot matrix printers have 24 pins.
Most use continuous-form paper
Dot matrix printers are used for high volume / low quality printing, e.g. printing company pay slips
Advantages
Inexpensive
Widely Used
Other language characters can be printed
Disadvantages
Slow Speed
Poor Quality
dot matrix printers can generate a lot of noise and do not produce a very high quality of print, especially when printing graphics.

13. Daisy Wheel
Head is lying on a wheel and pins corresponding to characters are like petals of Daisy (flower name) that is why it is called Daisy Wheel Printer. These printers are generally used for word-processing in offices which require a few letters to be sent here and there with very nice quality.
Advantages
More reliable than DMP
Better quality
The fonts of character can be easily changed
Disadvantages
Slower than DMP
Noisy
More expensive than DMP

14. Line Printers Advantages Disadvantages
Line printers are the printers which print one line at a time. These are of further two types
Drum Printer
Chain Printer
This printer is like a drum in shape so it is called drum printer. The surface of drum is divided into number of tracks. Total tracks are equal to size of paper i.e. for a paper width of 132 characters, drum will have 132 tracks. A character set is embossed on track. The different character sets available in the market are 48 character set, 64 and 96 characters set. One rotation of drum prints one line. Drum printers are fast in speed and can print 300 to 2000 lines per minute.
Advantages
Very high speed
Disadvantages
Very expensive
Characters’ fonts cannot be changed

15. Character fonts can easily be changed.
Chain Printer
In this printer, chain of character sets are used so it is called Chain Printer. A standard character set may have 48, 64, or 96 characters.
Advantages
Character fonts can easily be changed.
Different languages can be used with the same printer.
Disadvantages
Noisy

16. Non-impact Printers Characteristics of Non-impact Printers
Forms characters and graphics on piece of paper without actually striking paper
Non-impact printers print the characters without using ribbon. These printers print a complete page at a time so they are also called as Page Printers.
These printers are of two types
Laser Printers
Inkjet Printers
Characteristics of Non-impact Printers
Faster than impact printers.
They are not noisy.
High quality.
Support many fonts and different character size.

17. Laser Printers Disadvantages Advantages
They use laser lights to produce the dots needed to form the characters to be printed on a page.
Laser printers produce high print quality at high speed. They are called "laser printers" due to the fact that they contain a small laser within them.
Advantages
Very high speed
Very high quality output
Give good graphics quality
Support many fonts and different character size
Disadvantages
Expensive.

18. Expensive as cost per page is high Slow as compared to laser printer
Inkjet Printers
Inkjet printers are non-impact character printers based on a relatively new technology. They print characters by spraying small drops of ink onto paper. Inkjet printers produce high quality output with presentable features.
Inkjet printers are ideal for low volume printing, where high quality print is required and speed is not an issue, such as printing letters in a small office or in the home.
They make less noise because no hammering is done and these have many styles of printing modes available. Colour printing is also possible. Some models of Inkjet printers can produce multiple copies of printing also.
Advantages
High quality printing
More reliable
Disadvantages
Expensive as cost per page is high
Slow as compared to laser printer

19. INPUT & OUTPUT BOTH DEVICES
A modem can be used for downloading information from web sites and receiving s.
It can also be used for uploading and sending s.
A touch screen can display a menu system (output device), and accept input when people touch the menus displayed on the screen.

20. Speakers and Headphones
Plotters
A plotter is an output device similar to a printer, but normally allows you to print larger images.
Sophisticated printer used to produce high-quality drawings
Large-format printer similar to plotter and is used to print quality color prints
Speakers and Headphones
Most computers are sold with the capability to add a pair of speakers to your system unit. In fact, in some cases, the computer screen may have speakers built directly into the unit
Most computers allow you to plug headphones into one of the computer sockets.
This is useful as the sound will then not annoy others in the room.
Enhances the value of educational and presentation products.

21. Speech synthesisers
A recent development is the ability not only to display text on a monitor but also to read the text to you
You could receive a text from a colleague and the system could read that to you
This is of enormous benefit to the visually impaired when using a computer
On the flip side, it is now possible to use a microphone to talk to the computer and for the computer to directly convert the spoken word into text, which will be displayed within a word-processor
Whilst these systems are far from fool proof they are getting better as more advanced software is being made available.
Gives you the ability to not only to display text on a monitor but also to read the text to you

22. Projectors
These are projection devices which can be attached to your computer and are useful for displaying presentations to a group of people.
They are best used in combination with presentation programs, such as Microsoft PowerPoint.
They are used within education and are also very popular for sales presentations.