Introduction
Computer as a machine or device do cannot function alone without other peripherals. Peripherals are external devices that can be connected to a computer device to produce a result that the computer alone can't afford.
However, in this post we will be discussing what is computer output devices as well as give examples of these output devices.
What is Computer Output devices?
The medium at which a processed data from the input device of a computer is displayed is known as an OUTPUT DEVICE. However, we have various output devices that display output in many form as text, hard copies, images, audio or video. Below are some of the examples of output devices.
A. Printer
Processed data are given out in a form of hard copies through a printer. A printer allows the user to print text and images or any other information on paper. We have two main types of printer in the aspect of primary mechanism, they are:
1. Impact Printers
2. Non - impact Printers
1. Impact Printers
Here, hammer or print head is used to print the character or images on papers. Impact printers are further divided into two types namely: Character Printers and Line Printers
a. Character Printers
This type of printer prints a single character with a single stroke of the print head or hammer. it's not capable of printing one line at a time. It is of two types they are:
i. Daisy Wheel Printers
It is a printer that was invented at Diabo Data System by David S. Lee. It has a wheel that has extensions or spokes and the extension further have characters that are molded with metal mounted at end.
During printing of characters, the printer has to rotate the wheel, when the desired character entered the print location the hammer then hits the disk, the extension will further hit the ink ribbon against the paper in order to create the printing impression.
However, this printer is not rapidly in use due to its slowness and inability to print graphics.
ii. Dot Matrix Printers
It is an impact printer that uses patterns and dots for printing characters and images. In order to produce patterns, the ink soaked ribbon is strike against the paper with the printer's print head. The pins used for producing the pattern of dots on the paper is in the print head.
b. Line Printers
This type of printer is capable of printing one line at a time. It consist of a high-speed impact printer, also it prints 500 - 3000 lines each minute. Line printer is also known as bar printer and it is of two types, they are:
i. Chain Printers
It is a type of a line printer whose chains rotates horizontally around a set of hammer. In every of its print location, there is allocation of one hammer. The chain rotates at a high speed until the desired character comes under the hammer and and once it is, a corresponding hammer strikes the page against the ribbon and characters on the chain.
ii. Drum Printers
This is a printer that uses a rotating drum to print characters. There are bands of characters crested on the surface of the drum and each of these band of characters has its own hammer. When the printer is printing, the printer's drum rotates until the character to be printed comes under the hammer and this point, the hammer will strike the ribbon against the paper to print the desired character. It well known for its noise making due to hammering technique.
2. Non - impact Printers
Non - impact Printers prints characters and images without physical contact between the printing machinery and the paper. Non - impact printer has two common types which are;
a. Inkjet Printers
b. Laser Printers
i. Inkjet Printers
Inkjet printer prints images and characters by spraying fine, ionized drops of ink. Inkjet printer is one of the non-impact printer, it is capable of printing high quality images with different colours of at least 300 dots per inch (dpi).
b. Laser Printers
Laser printer uses a laser beam to print characters. It is a non-impact printer. It utilizes powdered toner for printing in place of liquid ink. It is capable of producing quality print objects with a resolution of 600 dots per inch(dpi) or more.
B. Monitor
The display section or the computer screen is known as the Monitor.Data or information are displayed as text, images, video or audio through the monitor. It is the principal output device. Below are the different types of monitors;
1. CRT Monitor
This depends on the cathode ray tubes. They display images in the form of video signals like the vacuum tubes. Images are displayed on the screen when the cathode rays tube gives a beam of electrons that hit the inner phosphorescent surface of the screen via electron guns. Millions of phosphorus dots of red, green and blue colour are present in the monitor. These dots when hit by the beams of electrons they begin to shine this process is known as
cathodoluminescence.
Components of a CRT Monitor
The components of a CRT Monitor are mainly; the electron gun assembly, deflection plate assembly, florescent screen, glass envelope and base. The front view of the screen where the images are displayed is known as face plate. It consist of fiber optics. The three electron beams that hit the screen are red, green and blue. The colours produced on the screen are the mixture of three lights which are the red, blue and green lights. The beams of the electrons are guided by the magnetic field.
2. LCD Monitor
LCD Monitor has a compacted and light weight flat panel screen unlike CRT monitors. LCD monitor depends on liquid crystal display technology, liquid crystal display is utilized in the screens of tablets, laptop, smartphones, etc. LCD screen consist of two layers of polarized glass containing a liquid crystal solution at the center. An electric current signals the liquid crystals whenever the light penetrate the first layer. A different level of light penetrates the second layer to create images on the screen with the permission of the signalled liquid crystals.
The LCD screen is made up of a mixture of pixels that shows the image on the screen. Passive - matrix screens are present in old LCDs, each pixels are controlled by sending a charge. Screens appears faintly whenever the images moved faster on the screen may be as a result of a few electrical charges that might be sent each second. LCDs of today utilizes active - matrix technology, it comprises of thin film transistors ( TFTs) alongside capacitors. Pixels maintain their charge because of this technology. Whenever images moves quickly on the screen, it doesn't cause the screen to be blurry. Also, they are more efficient as compared to pass - matrix displays.
3. LED Monitor
LED monitor is an advanced version of LCD monitor. The difference between the LED monitor and LCD monitor is the light source to backlight the display. The LED monitor has a flat panel display, also make use of liquid crystal display technology same with LCD monitors. Electronic devices of nowadays like mobile phones, laptop and computer screens, LeD TVs and so on makes use of LED display because The gas present in the cells converts to plasma and produces ultraviolet light which displays images on the screen whenever voltage is applied. In terms of brightness, plasma displays are brighter compare to light crystal displays. Also, when it comes to viewing angle, plasma displays provides a wide viewing angle compare to LCD. Plasma monitors has a high resolutions of about 1920 by 1080, a high refresh rate, outstanding contrast ratios etc, also while watching movies especially action movies, sport games and so on, plasma monitors provides a unique viewing experience.
C. Projector
An output device which helps the user to project an output on a large medium like big screen or wall is know as a projector. It utilizes light and lenses to produce magnified texts, pictures or images and videos. A projector is the right output device use in presentation or to educate large number of people
Digital projectors are accompanied with different sources of input like HDMI ports for fresh equipment and VGA ports which support older services. Projectors are used for presentations, teachings, home videos etc. A digital projector is of two types namely:
i. liquid Crystal Display (LCD) digital projector
Ii. Digital Light Processing (DLP) digital monitor
i. Liquid Crystal Display (LCD) digital projector
Liquid crystal display digital projector are common and has light weight. Also, they produce crisp output.
ii. Digital Light Processing (DLP) digital projector
DLP comprises of a set of tiny mirrors, each mirror to one pixel of the image thereby producing images with high quality. DLP are commonly used in theatres due to it high-quality video output.