Computers are a necessity of today's technological era. They are making
operations or tasks easier in almost every sector. We cannot even think of a
world without computers because nowadays most services depend on them. The
computer has a wide range of output devices, which help us to see what the
computer is doing. Although computers can operate without an output device, we
will not obtain the results of the processed data/ inputs from the computer.
This article discusses most of the output devices of a computer. Before
discussing computer output devices, let's first understand the definition of
the output device:
Definition of Output Device
An output device is essentially a piece of instrument or computer hardware
that retrieves data from a computer system and further translates the received
data into a form understandable to humans. The most common
human-understandable forms typically include text, visual, audio, or a hard
copy (printed on a paper).
In simple words, an output device is a type of peripheral device that helps us
to get data processed from a computer, usually in the form of audio, visual,
and xerox.
Note: Output devices and Output Units are the same things. They are two
similar terms used in different ways by different people. Also, they are
termed peripheral devices or auxiliary devices.
What are the Output Devices?
Results of data fed into a computer machine are performed using specific
hardware devices. During the process, the result (retrieved data) is referred
to as the output from the computer
machine while the devices or hardware devices used to obtain the output are
referred to as the output devices.
The output devices can be classified into four categories, such as
visual, data, print, and sound. Depending on the type of computer and the requirements, different output
devices can be attached to the computer system. The most common output devices
are listed below:
Computer Output Devices
Functions of Output Devices
Since the output devices help in performing the necessary functions for the
computer, they are considered as parts of the computer system. Output devices
operate by receiving signals from computers and use that signal to process a
task to provide output in varying forms.
The function of the output device can be easily understood by the following
steps:
• When we press a key on the keyboard (input device), it sends a signal
to the computer.
• The computer further processes the input and sends the signal to the
monitor (output device).
• The monitor then translates the received signals and displays the
result (output) on the screen, whichever key we have pressed using the
keyboard.
That is how an output device functions. In case there are no output devices
attached to the computer, we would still be able to press a key on the
keyboard and the computer would still process it. However, we wouldn't be able
to see what key we have pressed to ensure the correct inputs.
Examples of Output Devices
Several types of output devices are available that help in obtaining output
from a computer. Each device has its function, merits, and demerits. The
following are examples of commonly used output devices:
Monitor
The most common example of an output device is a monitor. It is also known as
VDU (Visual Display Unit). It consists of several components, such as screens, circuitry, power
supplies, screen adjustment buttons, and more, which are assembled into a
casing. The monitor provides output from a computer on a screen so that users
can interact with or view data digitally.
The monitor typically provides output in symbolic and graphical form,
generated using several small dots, known as pixels. These pixels are usually
arranged in a rectangular form. That way, the monitor creates real-time video
pictures and other contents with the help of a video card. The more pixels we
have, the better the sharpness and quality of images.
Monitors are broadly classified into two types, such as cathode-ray tubes and
flat-panel displays:
Cathode-Ray Tube (CRT) Monitors
CRT monitors use cathode ray tubes that help to produce images in the form of
video signals on the screen. More clearly, the cathode ray tube generates
electron beams through the electron guns, which strike the screen's inner
phosphorescent surface to form the image on the screen.
The monitor usually contains millions of phosphorus dots in red, green, and
blue. These phosphorescent dots help to form pixels. The sharpness and clarity
of the picture depend mainly on how many pixels are there and what their sizes
are. The smaller the pixels, the better the picture quality of the screen.
Since CRT monitors use red, green, and blue electron beams, the colors we see
on the screen are a mixture of these three lights. The magnetic field helps to
control the electron rays accordingly. Due to the large size and heavy power
consumption, CRT monitors are currently not in widespread use.
Flat-Panel Displays
Flat-panel displays use liquid crystal technology or plasma to generate
output. In these devices, light is passed through liquid crystals to form
pixels. Nowadays, most of the devices are manufactured using flat panel
displays as there are significant advantages of using these displays over the
traditional CRT displays.
Flat-panel displays typically have lower volume, weight, and power consumption
than CRT monitors. They are very light and thin and can even be hung on walls
or worn on wrists. These types of displays can be found in devices such as
calculators, portable video games, laptops, monitors, smartwatches, and many
other digital devices.
There are mainly two categories of flat-panel displays, such as a
non-emissive display and an
emissive display.
Non-Emissive Displays: Non-emissive displays include all such devices that use optical effects to
transform sunlight or light from other sources into graphics patterns.
LCD
is an example of a non-emissive display.
• LCD: LCD monitors are small and lightweight flat panel displays. These monitors
use the light-modulating property of liquid crystals. In particular, an LCD
screen is constructed using two layers of polarized glasses with a liquid
crystal solution between them. Additionally, a cold cathode fluorescent light
is placed in these devices to backlight the displays.
When light is passed through the first layer, the electric current aligns the
liquid crystals. These aligned crystals then allow different levels of light
to pass through another layer, creating an image on the screen. These displays
can be found on the screens of laptops, smartphones, tablets, televisions,
etc.
LCDs typically use a matrix of pixels to display images on the screen.
Previously, LCDs used passive-matrix technology, whereas modern LCDs use
capacitors and thin-film transistors as well as active matrix technology.
Because of this, modern LCDs include pixels that can hold their charge. Thus,
modern LCDs do not have the blurry image problem that older LCDs had to face
when images moved fast.
Emissive Displays: Emissive displays include all such devices that typically transform
electrical energy to light.
LED
and plasma panels are examples of
emissive displays.
• LED: The LED monitor is an improved version of the LCD monitor. Unlike LCDs, LED
monitors make use of multiple panels consisting of multiple LEDs to backlight
the display. Regardless of the backlighting source, the technology used in
LEDs is similar to LCD. LED monitors are comparatively more reliable because
they have a wider dimming range.
LED displays are in widespread use due to their advantages over other
displays. These displays can be found in modern TVs, monitors, laptop screens,
smartphones, tablets, smartwatches, etc. LED displays have better light
intensity and therefore produce better quality output. In addition, LEDs are
known to consume less power than other displays.
• Plasma: Plasma monitors use plasma display technology. These displays usually
consist of small cells between two glass panels. Cells typically contain a
mixture of noble gases with small amounts of mercury. When the voltage is
applied, the gas in the cells converts to plasma and emits ultraviolet light
to produce images on the screen.
Plasma monitors are relatively thinner than CRT monitors and brighter than LCD
monitors. These types of monitors offer high resolutions up to 1920 x 1080
with excellent contrast ratio, refresh rates, and wide viewing angles. That
way, they provide us a brilliant viewing experience either we watch movies,
play games, or study.
Printer
The printer is another most common example of output devices that can be
easily found in homes and many workplaces. The primary function of a printer
is to make a copy (usually called ‘Hard copy’ or ‘Xerox copy’) or print the
information on paper that is sent from the computer to the printer. The
printer receives electronic data from the computer and produces a hard copy of
the processed data.
Earlier printers were only able to make black and white prints; however,
today's printers can produce monochrome and color prints with high quality.
Additionally, they are now available with wireless support, making the print
job much easier.
Printers are broadly classified into two types, such as
impact printers and
non-impact printers:
Impact Printer
Impact printers typically use a type of hammer or print head that is pushed
onto the ink ribbon, which then jointly strikes on a paper and draws the
characters. Although these printers come at a low cost, they make a lot of
noise and are therefore not in widespread use nowadays. However, they can be
the best choice for bulk printing due to their reasonable cost.
Impact printers are divided into two types, such as
character printers and
line printers:
Character Printers: Character printers refer to printers that can only print one character at a
time. These printers use one single stroke of the hammer/ print head at a
time. Therefore, they cannot print an entire line at once. In addition,
character printers are not compatible with printing images, making them less
useful for the current era.
Character printers are further sub-divided into the following two types:
• Dot Matrix Printers: Dot matrix printers are the most popular type of impact character printer.
These printers use a pattern of dots to print characters or pictures. The
pattern is structured by striking a ribbon soaked in ink on paper with the
help of a hammer or print head. The print head consists of several pins and
structures with multiple dots in a pattern to generate the corresponding
character.
To print color documents, the black ribbon on these printers can be replaced
with colored stripes. Generally, dot matrix printers can print 200–500
characters per second.
• Daisy Wheel Printers: The daisy wheel printer consists of a wheel or a disc with a print head and
several pins such as a daisy's petal (a flower) corresponding to the
characters. Thus, it is called a daisy wheel printer.
To make a print, the printer rotates the wheel with its respective characters.
When the desired character reaches the print location, the hammer strikes the
disc and the ink ribbon further creates a corresponding character on the
paper. These printers are slow and noisy, making them unusable for today's
generation.
Line Printers: Line printers refer to printers that can print one line at a time. These
printers are high-speed impact printers and can print up to 3000 lines per
minute.
Line printers are further sub-divided into the following two types:
• Drum Printers: Drum printers use a rotating drum that has a circular band on its surface.
The band contains characters on its surface. Multiple hammers are used in
these printers to print characters from different columns of the band. A paper
is rolled around the surface of the drum. When the print command is given, the
drum rotates and the hammer strikes on the ink ribbon, respective to the
desired character. That way, the drum printers eventually print a character on
paper.
Drum printers usually print character by character and are not compatible with
printing graphics. However, the overall speed of printing characters using
these printers is quite fast. Like other impact printers, drum printers also
make noise due to the hammering system.
• Chain Printers: Chain printers use a rotating chain with characters printed on their
surface. The chain rotates horizontally with the help of two gears. These
printers have several hammers: the total number of hammers is equal to the
number of print positions in these printers.
When the print command is given, the chain rotates and the print-ribbon
strikes the ink ribbon as soon as the desired character arrives at the print
location. The ribbon then creates a character on paper. These printers can
print 300 to 500 lines per minute. Chain printers also make a noise like other
impact printers.
Non-Impact Printer
Non-impact printers do not use any hammer or print head to strike the ink
ribbon. These printers print characters or images without using ribbons.
Unlike impact printers, the internal machinery of non-impact printers does not
make direct physical contact with the paper. These types of printers usually
print the entire page at once, and therefore, are also called
page printers.
Non-impact printers are divided into two types, such as
laser printers and
inkjet printers. Among all printers, these are the two most common types of printers.
Laser Printers: Laser printers use laser light to make dots, which later help to form
letters to print on paper. In particular, the laser beam hits the drum and
structures the image structure on the drum by controlling the electric charge.
The drum then rolls into toner and sends the charged structure to the toner.
The toner prints the respective structure on the paper with the help of some
heat and pressure.
After the document is fully printed, the drum loses electric charge and
collects the remaining toner. Instead of using liquid ink, laser printers use
powder toner for printing documents. This ultimately helps these printers to
produce quality prints with resolutions of 600 dpi (dots per inch) and more.
Inkjet Printers: Inkjet printers are widely used non-impact character printers. These
printers usually print the characters or pictures by spraying small drops of
ink on the paper. These droplets are passed through an electric field that
controls the sprays to print the appropriate characters or images.
Inkjet printers do not make noise because there is no hammer like an impact
printer. These printers use ink cartridges. Modern inkjet printers have ink
cartridges of four different colors: black, yellow, cyan, and magenta. This
ultimately allows these printers to produce high-quality color prints.
Touchscreen
Touchscreens are output devices seen in various devices due to the use of
portable devices. It is a thin, lightweight panel developed to receive output
from a computer. In particular, the touch screen is a touch-sensitive surface
or monitor that can display visuals or graphics.
Nowadays touch screens can be easily found in modern devices, such as laptops,
smartphones, tablets, etc. Because we can also use touchscreens to give input,
these devices are also known as input-output devices.
Projector
A projector is a display output device because it receives images from a
computer and transfers those computer images to a wall, surface, or projection
screen. Specifically, the computer first sends the signal to the video card,
which then transmits the signal to the projector to project the images on the
surface.
Previously, projectors used lens systems that produced images by shining light
through transparent lenses. Modern projectors use laser systems to directly
project images using lasers. Modern projectors are also called video
projectors because these projectors can also project moving images along with
still images.
Speakers
Speakers are one of the most common output devices used on computers to
achieve audio output. Computer speakers usually receive signals from the sound
card and then convert them to audio. These speakers use internal amplifiers
that vibrate at different frequencies to increase/decrease the volume or
amplitude of the sound as per the choice of the user.
Most monitors and laptops come with inbuilt speakers. However, we can also
connect external speakers to the computer via both wired and wirelessly. The
speakers are mainly used to obtain the loud sound output.
Headphones
Headphones, also known as earphones, are output devices that allow us to
listen to audio from a computer. These devices are mainly used to listen to
audio privately or without disturbing others around. Headphones come in a
variety of sizes and designs and can connect with supported devices via both
wired or wirelessly.
Headphones primarily receive audio input from connected devices and convert
them into audio output in waveforms. Many headphones come with a microphone,
making them a great device for communicating with family or friends. These
output devices are mostly used to communicate in gaming and on bulk calls.
Sound Card
A sound card, also known as an
expansion card, is a type of output device that is usually installed on a motherboard in
the inner case of a computer. The main function of a sound card is to control
the output of sound signals and enable devices such as speakers and headphones
to function.
Sound cards usually work with the help of drivers and software. Although a
sound card is not mandatory for the basic functions of a computer system, it
is added to the computer for listening to audio, playing games, watching
movies, listening to music, video conferencing, and more.
Video Card
As the sound card, a video card is also an expansion card installed on the
slots in the motherboard. The primary function of a video card is to process
images and videos so that their visuals are displayed on the screen. It is
also known as a video adapter.
A video card is a basic requirement of a computer system and therefore most
computers come with regular video and graphics capabilities to display images
and video. However, to get more detailed graphics, a higher video card is
required. This is why most gaming computers and laptops use additional
(dedicated) video cards.
GPS (Global Positioning System)
GPS or a global positioning system is a radio-based navigation system
consisting of a network of multiple satellites. It uses a system of about 31
satellites located in space to provide accurate results. The satellites use
microwave signals to interact with GPS devices.
Nowadays GPS is mostly found in smartphones, smartwatches, laptops, etc.
Anyone can use this system to get the location on the map. This mainly helps
in obtaining the exact location of connected devices or locations on the map
in the form of latitude and longitude coordinates on the Earth. In addition,
these devices provide information on vehicle speed, weather conditions, and
many other pieces of data.
Braille Reader
A Braille reader is an output device that primarily helps blind people read
content (texts only) from a computer screen. The computer sends signals to the
Braille reader, which converts them into Braille letters in the form of pins
embossed on a flat surface. People with blindness can touch these pins and
interpret the letters accordingly.
Braille readers are manufactured in different sizes, making them usable on
different devices. Generally, they are found in the size of the computer
keyboard.
Speech-Generating Device (SGD)
Speech generating devices are output devices that help generate voice output
from the text displayed on a computer screen. In particular, these devices
convert text to speech. Additionally, whenever a user enters something from
the keyboard and when the command is executed, SGD can help listen to the
entered data as sound output.
Speech generating devices are also known as
speech synthesizers and
voice output communication aids. These output devices are widely used in telephone exchanges and the
treatment of blind and mute people.
Plotter
A plotter is an output device that is almost identical to a printer. However,
it is primarily used to print vector graphics with high quality. Unlike a
printer, a plotter has various advanced features and can also print on
cardboard, film, fabric, and many other synthetic surfaces.
The plotter helps to produce large-size hardcopies of graphics or designs. It
derives the design from the graphic card and then interprets the vector
graphics. A plotter usually uses color pens to draw multiple lines between
different points to create the entire design. Plotters are expensive compared
to printers.
Note: Many more output devices are used on computers to fulfill
specific objectives. Some other output devices include smart television (TV),
computer output microfilm (COM), modem, a network card (NIC), digital camera,
AirPods (also called earpods), and more.
Summary
This article covers more than 10 examples of output devices used for
computers, including their names, pictures, and functions on each. The primary
function of an output device is to retrieve data from a computer and convert
it into a human-readable form because we cannot understand data in machine
language.
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