Input Devices

Input device enables the user to send data, information, or control signals to a computer. The
Central Processing Unit (CPU) of a computer receives the input and processes it to produce the
output.

Some of the popular input devices are:

1. Keyboard
2. Mouse
3. Scanner
4. Joystick
5. Light Pen
6. Digitizer
7. Microphone
8. Magnetic Ink Character Recognition (MICR)
9. Optical Character Reader (OCR)
10. Digital Camera
11. Paddle
12. Steering Wheel
13. Gesture recognition devices
14. Light Gun
15. Touch Pad
16. Remote
17. Touch screen
18. VR
19. Webcam
20. Biometric Devices

1) Keyboard
The keyboard is a basic input device that is used to enter data into a computer or any other
electronic device by pressing keys. It has different sets of keys for letters, numbers, characters,
and functions. Keyboards are connected to a computer through USB or a Bluetooth device for
wireless communication.

Types of keyboards: There can be different types of keyboards based on the region and
language used. Some of the common types of keyboards are as follows:
 i) QWERTY Keyboard:

It is the most commonly used keyboard with computers in modern times. It is named after the
first six letters of the top row of buttons and is even popular in countries that do not use Latin-
based alphabet. It is so popular that some people think that it is the only type of keyboard to
use with computers as an input device.

ii) AZERTY Keyboard:

It is considered the standard French keyboard. It is developed in France as an alternative layout

to the QWERTY layout and is mainly used in France and other European countries. Some
countries have manufactured their own versions of AZERTY.

Its name is derived from the first six letters that appear on the top left row of the keyboard. The
Q and W keys in AZERTY keyboard are interchanged with A and Z keys in QWERTY
keyboard. Furthermore, in AZERTY keyboard M key is located to the left of the L key.

AZERTY keyboard differs from QWERTY keyboard not only in the placement of letters but
also in many other ways, e.g., it gives emphasis on accents, which is required for writing
European languages like French.

iii) DVORAK Keyboard:

This type of keyboard layout was developed to increase the typing speed by reducing the finger
movement while typing. The most frequently used letters are kept in a home row to improve
typing.
2) Mouse
The mouse is a hand-held input device which is used to move cursor or pointer across the
screen. It is designed to be used on a flat surface and generally has left and right button and a
scroll wheel between them. Laptop computers come with a touchpad that works as a mouse. It
lets you control the movement of cursor or pointer by moving your finger over the touchpad.
Some mouse comes with integrated features such as extra buttons to perform different buttons.

The mouse was invented by Douglas C. Engelbart in 1963. Early mouse had a roller ball
integrated as a movement sensor underneath the device. Modern mouse devices come with
optical technology that controls cursor movements by a visible or invisible light beam. A mouse
is connected to a computer through different ports depending on the type of computer and type
of a mouse.

Common types of the mouse:

i) Trackball Mouse:

It is a stationary input device that has ball mechanism to move the pointer or cursor on the
screen. The ball is half inserted in the device and can be easily rolled with finger, thumb or the
palm to move the pointer on the screen. The device has sensor to detect the rotation of ball. It
remains stationary; you don't need to move it on the operating surface. So, it is an ideal device
if you have limited desk space as you don't need to move it like a mouse.

ii) Mechanical Mouse:

It has a system of a ball and several rollers to track its movement. It is a corded type of mouse.
A mechanical mouse can be used for high performance. The drawback is that they tend to get
dust into the mechanics and thus require regular cleaning.

iii) Optical Mouse:

An optical mouse uses optical electronics to track its movement. It is more reliable than a
mechanical mouse and also requires less maintenance. However, its performance is affected by
the surface on which it is operated. Plain non-glossy mouse mat should be used for best results.
The rough surface may cause problems for the optical recognition system, and the glossy
surface may reflect the light wrongly and thus may cause tracking issues.

iv) Cordless or Wireless Mouse:

As the name suggests, this type of mouse lacks cable and uses wireless technology such as
IrDA (infrared) or radio (Bluetooth or Wi-Fi) to control the movement of the cursor. It is used
to improve the experience of using a mouse. It uses batteries for its power supply.

3) Scanner

The scanner uses the pictures and pages of text as input. It scans the picture or a document. The
scanned picture or document then converted into a digital format or file and is displayed on the
screen as an output. It uses optical character recognition techniques to convert images into
digital ones. Some of the common types of scanners are as follows:

Types of Scanner:

i) Flatbed Scanner:
It has a glass pane and a moving optical CIS or CCD array. The light illuminates the pane, and
then the image is placed on the glass pane. The light moves across the glass pane and scans the
document and thus produces its digital copy. You will need a transparency adapter while
scanning transparent slides.

ii) Handheld Scanner:

It is a small manual scanning device which is held by hand and is rolled over a flat image that
is to be scanned. The drawback in using this device is that the hand should be steady while
scanning; otherwise, it may distort the image. One of the commonly used handheld scanners is
the barcode scanner which you would have seen in shopping stores.

iii) Sheetfed Scanner:

In this scanner, the document is inserted into the slot provided in the scanner. The main
components of this scanner include the sheet-feeder, scanning module, and calibration sheet.
The light does not move in this scanner. Instead, the document moves through the scanner. It
is suitable for scanning single page documents, not for thick objects like books, magazines, etc.

iv) Drum Scanner:

Drum scanner has a photomultiplier tube (PMT) to scan images. It does not have a charge-
coupled device like a flatbed scanner. The photomultiplier tube is extremely sensitive to light.
The image is placed on a glass tube, and the light moves across the image, which produces a
reflection of the image which is captured by the PMT and processed. These scanners have high
resolution and are suitable for detailed scans.

v) Photo Scanner:

It is designed to scan photographs. It has high resolution and color depth, which are required
for scanning photographs. Some photo scanners come with in-built software for cleaning and
restoring old photographs.

4) Joystick

A joystick is also a pointing input device like a mouse. It is made up of a stick with a spherical
base. The base is fitted in a socket that allows free movement of the stick. The movement of
stick controls the cursor or pointer on the screen.

The frist joystick was invented by C. B. Mirick at the U.S. Naval Research Laboratory. A
joystick can be of different types such as displacement joysticks, finger-operated joysticks,
hand operated, isometric joystick, and more. In joystick, the cursor keeps moving in the
direction of the joystick unless it is upright, whereas, in mouse, the cursor moves only when
the mouse moves.
5) Light Pen

A light pen is a computer input device that looks like a pen. The tip of the light pen contains a
light-sensitive detector that enables the user to point to or select objects on the display screen.
Its light sensitive tip detects the object location and sends the corresponding signals to the CPU.
It is not compatible with LCD screens, so it is not in use today. It also helps you draw on the
screen if needed. The first light pen was invented around 1955 as a part of the Whirlwind
project at the Massachusetts Institute of Technology (MIT).

6) Digitizer

Digitizer is a computer input device that has a flat surface and usually comes with a stylus. It
enables the user to draw images and graphics using the stylus as we draw on paper with a
pencil. The images or graphics drawn on the digitizer appear on the computer monitor or
display screen. The software converts the touch inputs into lines and can also convert
handwritten text to typewritten words.

It can be used to capture handwritten signatures and data or images from taped papers.
Furthermore, it is also used to receive information in the form of drawings and send output to
a CAD (Computer-aided design) application and software like AutoCAD. Thus, it allows you
to convert hand-drawn images into a format suitable for computer processing.

7) Microphone
The microphone is a computer input device that is used to input the sound. It receives the sound
vibrations and converts them into audio signals or sends to a recording medium. The audio
signals are converted into digital data and stored in the computer. The microphone also enables
the user to telecommunicate with others. It is also used to add sound to presentations and with
webcams for video conferencing. A microphone can capture audio waves in different ways;
accordingly the three most common types are described below:

i) Dynamic:

It is the most commonly used microphone with a simple design. It has a magnet which is
wrapped by a metal coil and a thin sheet on the front end of the magnet. The sheet transfers
vibrations from sound waves to the coil and from coil to electric wires which transmit the sound
like an electrical signal.

ii) Condenser:

It is designed for audio recording and has a very sensitive and flat frequency response. It has a
front plate called diaphragm and a back plate parallel to the front plate. When sound hits the
diaphragm, it vibrates the diaphragm and alters the distance between the two plates. The
changes in distance are transmitted as electric signals.

iii) Ribbon:
It is known for its reliability. It has a thin ribbon made of aluminum, duraluminum, or nanofilm
suspended in a magnetic field. The sound waves cause vibrations in the ribbon, which generate
a voltage proportional to the velocity of the vibration. The voltage is transmitted as an electrical
signal. Early ribbon microphones had a transformer to increase the output voltage, but modern
ribbon microphones come with advanced magnets to produce a strong signal.

8) Magnetic Ink Character Recognition (MICR)

MICR computer input device is designed to read the text printed with magnetic ink. MICR is
a character recognition technology that makes use of special magnetized ink which is sensitive
to magnetic fields. It is widely used in banks to process the cheques and other organizations
where security is a major concern. It can process three hundred cheques in a minute with
hundred-percent accuracy. The details on the bottom of the cheque (MICR No.) are written
with magnetic ink. A laser printer with MICR toner can be used to print the magnetic ink.

The device reads the details and sends to a computer for processing. A document printed in
magnetic ink is required to pass through a machine which magnetizes the ink, and the magnetic
information is then translated into characters.

9) Optical Character Reader (OCR)

OCR computer input device is designed to convert the scanned images of handwritten, typed
or printed text into digital text. It is widely used in offices and libraries to convert documents
and books into electronic files.

It processes and copies the physical form of a document using a scanner. After copying the
documents, the OCR software converts the documents into a two-color (black and white),
version called bitmap. Then it is analyzed for light and dark areas, where the dark areas are
selected as characters, and the light area is identified as background. It is widely used to convert
hard copy legal or historic documents into PDFs. The converted documents can be edited if
required like we edit documents created in ms word.

10) Digital camera:

It is a digital device as it captures images and records videos digitally and then stores them on
a memory card. It is provided with an image sensor chip to capture images, as opposed to film
used by traditional cameras. Besides this, a camera that is connected to your computer can also
be called a digital camera.

It has photosensors to record light that enters the camera through the lens. When the light strikes
the photosensors, each of the sensors returns the electrical current, which is used to create the
images.
11) Paddle:

It is a simple input device that is widely used in games. It is a wheel that is held by hand and
looks like a volume knob on a stereo that is used to increase or decrease the volume. Paddle
moves or controls cursor or any other objects in the game in a back-and-forth motion. It is
widely used as an alternative to the joystick. Besides this, the term paddle also refers to many
handheld devices designed to control a function in an electronic device, computer, etc.

12) Steering wheel:

It is used as an input device in racing video games such as car racing games or in driving
programs as virtual simulators to steer a vehicle. It works like the real steering wheel by
allowing you to take a right or left turn. A steering wheel may be provided with acceleration
and brake pedal devices and a mechanism for shifting gears. Thus, it makes racing games more
adventurous and entertaining.

13) Gesture recognition devices:

These devices take human gestures as input. There are many such devices that respond to
gestures. For example, Kinect is one such device that observes the movement of a player's body
and interprets these movements as inputs to video games. This feature is also available in
certain tablets and smartphones where you can perform certain tasks such as taking pictures
using finger gestures such as swiping, pinching, etc.

14) Light Gun:

As the name suggests, it is a pointing input device that is designed to point at and shoot the
targets on the screen in a video game, or arcade, etc. The light gun was used for the first time
on the MIT Whirwind computer. When the gun is pointed at the target on the screen and the
trigger is pulled, the screen goes blank for a fraction of a second. During this moment, the
photodiode, which is present in the barrel, determines where the gun is pointed. For example,
shooting ducks in a duck hunt game.

15) Touchpad:

It is usually found in laptops as a substitute for the mouse. It allows you to move or control the
cursor on the screen using your finger. Just like a mouse, it also has two buttons for right and
left click. Using the touchpad, you can perform all the tasks that you do with a mouse, such as
selecting an object on the screen, copy, paste, delete, open a file or folder, and more.

16) Remote:

It is a hardware device designed to control the functioning of a device, e.g., a TV remote that
can be used to change channels, increase or decrease the volume, from a distance without
leaving the seat. The first cordless TV remote was invented by Dr. Robert Adler of Zenith in
1956. The remote sends the electromagnetic waves to communicate with the device. These
waves can be infrared rays, radio waves, etc.
17) Touch screen:

It is the display screen of a device such as a smartphone, tablet, etc., that allows users to interact
or provide inputs to the device by using their finger. Today, most of the electronic devices
come with touchscreen as an alternative to a mouse for navigating a graphical user interface.
For example, by touching, you can unlock your phone, open emails, open files, play videos,
etc. Besides this, it is used in lots of devices such as Camera, Car GPS, Fitness machine, etc.

The concept of the touch screen was first introduced and published by E.A. Johnson in 1965.
The first touch screen was developed at the beginning of the 1970s by CERN engineers Frank
Beck and Bent Stumpe.

18) VR:

VR stands for virtual reality. It is an artificial or virtual environment which is generated by

computers. A person can interact with virtual objects of this artificial environment using some
input devices such as headsets, gloves, headphones, etc. For example, he or she can find himself
or herself walking on a beach, watching a football match, walking in the sky, etc., without
actually doing all this.

19) Webcam:

Any camera which is connected to a computer is called a webcam. The in-built camera provided
on a computer can also be considered a webcam. It is an input device as it can take pictures,
and can be used to record videos if required. The pictures and videos are stored in the computer
memory and can be displayed on the screen if required. Although it works almost the same as
the digital camera, it is different from a digital camera, as it is designed to take compact digital
photos that can be uploaded easily on the webpages and shared with others through the internet.

20) Biometric Devices:

Biometrics refers to a process in which a person is identified through his or her biological
features such as fingerprints, eye cornea, face structure, etc. It is done by using biometric
devices, which can be of different types based on their scanning features and abilities, such as:

i) Face Scanner:

It is designed to identify a person by scanning his or her face. It takes the face measurements
of a person. For example, the distance between eyes, nose, and mouth, etc., accordingly, it
confirms the identity of a person. Besides this, it is smart enough to differentiate between a
person's picture and the real person.

ii) Hand Scanner:

The hand of a person can also be used to verify his or her identity as every person has a unique
pattern of veins in the palm, just like fingerprints. This device takes advantage of this feature;
it identifies a person by scanning the palm of his hand. It uses infrared light to scan veins'
patterns and blood flowing in them. Palm is even more unique than fingerprints.

iii) Fingerprint Scanner:

It scans the fingerprints to identify people or for biometric authentication. This device is
developed, keeping in mind the fact that no two persons in the world can have the same
fingerprints. It is widely used in companies as a fingerprint attendance system to mark the
attendance of employees. This type of scanners captures the pattern of valleys and ridges found
on a finger and store it in the memory or database. When you press your finger on the given
space, it verifies the identity by using its pattern-matching software.

iv) Retina or Iris Scanner:

It scans the retina or iris of a person's eye to confirm the identity. This device is more secure
than others as it is next to impossible to copy the retina or iris. It works by mapping the retina's
blood vessel patterns of the eye. The blood vessels of retina absorb light more easily as well as
can be identified with appropriate lighting.

In this scan, a beam of low-energy infrared light falls on the retina through the scanner's
eyepiece. Then, the software captures the network of blood vessels in the retina and uses it to
verify a person's identity.

v) Voice Scanner:

It records the voice of a person and digitizes it to create a distinctive voice print or template.
The voiceprints are stored in the database, and are used to verify the voice of a person to
confirm his or her identity. The person is required to speak in the normal or same voice that
was used to create a voice template. It is not much reliable as it can be misused using a tape
recording.

Output Devices

The output device displays the result of the processing of raw data that is entered in the
computer through an input device. There are a number of output devices that display output in
different ways such as text, images, hard copies, and audio or video.

Some of the popular output devices are:

1. Monitor
o CRT Monitor
o LCD Monitor
o LED Monitor
o Plasma Monitor
2. Printer
o Impact Printers
A. Character Printers
i. Dot Matrix printers
ii. Daisy Wheel printers
B. Line printers
i. Drum printers
ii. Chain printers
o Non-impact printers
A. Laser printers
B. Inkjet printers
3. Projector

1) Monitor

The monitor is the display unit or screen of the computer. It is the main output device that
displays the processed data or information as text, images, audio or video.

The types of monitors are given below.

i) CRT Monitor

CRT monitors are based on the cathode ray tubes. They are like vacuum tubes which produce
images in the form of video signals. Cathode rays tube produces a beam of electrons through
electron guns that strike on the inner phosphorescent surface of the screen to produce images
on the screen. The monitor contains millions of phosphorus dots of red, green and blue color.
These dots start to glow when struck by electron beams and this phenomenon is called
cathodoluminescence.

The main components of a CRT monitor include the electron gun assembly, deflection plate
assembly, fluorescent screen, glass envelope, and base.The front (outer surface) of the screen
onto which images are produced is called the face plate. It is made up of fiber optics.

There are three electron beams that strike the screen: red, green, and blue. So, the colors which
you see on the screen are the blends of red, blue and green lights.The magnetic field guides the
beams of electrons. Although LCDs have replaced the CRT monitors, the CRT monitors are
still used by graphics professionals because of their color quality.

ii) LCD Monitor

The LCD monitor is a flat panel screen that is compact and light-weight as compared to CRT
monitors. It is based on liquid crystal display technology which is used in the screens of laptops,
tablets, smart phones, etc. An LCD screen comprises two layers of polarized glass with a liquid
crystal solution between them. When the light passes through the first layer, an electric current
aligns the liquids crystals. The aligned liquid crystals allow a varying level of light to pass
through the second layer to create images on the screen.

The LCD screen has a matrix of pixels that display the image on the screen. Old LCDs had
passive-matrix screens in which individual pixels are controlled by sending a charge. A few
electrical charges could be sent each second that made screens appear blurry when the images
moved quickly on the screen.
Modern LCDs use active-matrix technology and contain thin film transistors (TFTs) with
capacitors. This technology allows pixels to retain their charge. So, they don?t make screen
blurry when images move fast on the screen as well as are more efficient than passive-matrix
displays.

iii) LED monitor

The LED monitor is an improved version of an LCD monitor. It also has a flat panel display
and uses liquid crystal display technology like the LCD monitors. The difference between them
lies in the source of light to backlight the display. The LED monitor has many LED panels, and
each panel has several LEDs to backlight the display, whereas the LCD monitors use cold
cathode fluorescent light to backlight the display. Modern electronic devices such as mobile
phones, LED TVs, laptop and computer screens, etc., use a LED display as it not only produces
more brilliance and greater light intensity but also consumes less power.

iv) Plasma Monitor

The plasma monitor is also a flat panel display that is based on plasma display technology. It
has small tiny cells between two glass panels. These cells contain mixtures of noble gases and
a small amount of mercury. When voltage is applied, the gas in the cells turns into a plasma
and emits ultraviolet light that creates images on the screen, i.e., the screen is illuminated by a
tiny bit of plasma, a charged gas. Plasma displays are brighter than liquid crystal displays
(LCD) and also offer a wide viewing angle than an LCD.

Plasma monitors provide high resolutions of up to 1920 X 1080, excellent contrast ratios, wide
viewing angle, a high refresh rate and more. Thus, they offer a unique viewing experience
while watching action movies, sports games, and more.
2) Printer

A printer produces hard copies of the processed data. It enables the user, to print images, text
or any other information onto the paper.

Based on the printing mechanism, the printers are of two types: Impact Printers and Non-impact
Printers.
o Impact Printers: They are of two types:
A. Character Printers
i. Dot Matrix printers
ii. Daisy Wheel printers
B. Line printers
i. Drum printers
ii. Chain printers
o Non-impact printers: They are of two types:
A. Laser printers
B. Inkjet printers

Impact Printer

The impact printer uses a hammer or print head to print the character or images onto the paper.
The hammer or print head strikes or presses an ink ribbon against the paper to print characters
and images.

Impact printers are further divided into two types.

A. Character Printers
B. Line printers

A) Character Printers

Character printer prints a single character at a time or with a single stroke of the print head or
hammer. It does not print one line at a time. Dot Matrix printer and Daisy Wheel printer are
character printers. Today, these printers are not in much use due to their low speed and because
only the text can be printed. The character printers are of two types, which are as follows:

i) Dot Matrix Printer

Dot Matrix Printer is an impact printer. The characters and images printed by it are the patterns
of dots. These patterns are produced by striking the ink soaked ribbon against the paper with a
print head. The print head contains pins that produce a pattern of dots on the paper to form the
individual characters. The print head of a 24 pin dot matrix contains more pins than a 9 pin dot
matrix printer, so it produces more dots which results in better printing of characters. To
produce color output, the black ribbon can be changed with color stripes. The speed of Dot
Matrix printers is around 200-500 characters per second.

ii) Daisy Wheel Printer

Daisy Wheel Printer was invented by David S. Lee at Diablo Data Systems.It consists of a
wheel or disk that has spokes or extensions and looks like a daisy, so it is named Daisy Wheel
printer. At the end of extensions, molded metal characters are mounted. To print a character
the printer rotates the wheel, and when the desired character is on the print location the hammer
hits disk and the extension hits the ink ribbon against the paper to create the impression. It
cannot be used to print graphics and is often noisy and slow, i.e., the speed is very low around
25-50 characters per second. Due to these drawbacks,these printers have become obsolete.

B) Line Printers:

Line printer, which is also as a bar printer, prints one line at a time. It is a high-speed impact
printer as it can print 500 to 3000 lines per minute. Drum printer and chain printer are examples
of line printers.

i) Drum Printer:
Drum printer is a line printer that is made of a rotating drum to print characters. The drum has
circular bands of characters on its surface. It has a separate hammer for each band of characters.
When you print, the drum rotates, and when the desired character comes under the hammer,
the hammer strikes the ink ribbon against the paper to print characters. The drum rotates at a
very high speed and characters are printed by activating the appropriate hammers. Although all
the characters are not printed at a time, they are printed at a very high speed. Furthermore, it
can print only a predefined style as it has a specific set of characters. These printers are known
to be very noisy due to the use of hammering techniques.

ii) Chain Printer:

Chain printer is a line printer that uses a rotating chain to print characters. The characters are
embossed on the surface of the chain. The chain rotates horizontally around a set of hammers,
for each print location one hammer is provided, i.e., the total number of hammers is equal to
the total number of print positions.

The chain rotates at a very high speed and when the desired character comes at the print
location, the corresponding hammer strikes the page against the ribbon and character on the
chain.They can type 500 to 3000 lines per minute. They are also noisy due to the hammering
action.

Non-Impact Printer:

Non-impact printers don't print characters or images by striking a print head or hammer on the
ink ribbon placed against the paper. They print characters and images without direct physical
contact between the paper and the printing machinery. These printers can print a complete page
at a time, so they are also known as page printers. The common types of non-impact printers
are Laser printer and Inkjet printer:

i) Laser Printer:
A laser printer is a non-impact printer that uses a laser beam to print the characters. The laser
beam hits the drum, which is a photoreceptor and draws the image on the drum by altering
electrical charges on the drum. The drum then rolls in toner, and the charged image on the drum
picks the toner. The toner is then printed on the paper using heat and pressure. Once the
document is printed, the drum loses the electric charge, and the remaining toner is collected.
The laser printers use powdered toner for printing instead of liquid ink and produce quality
print objects with a resolution of 600 dots per inch (dpi) or more.

ii) Inkjet Printer:

The inkjet printer is a non-impact printer that prints images and characters by spraying
fine,ionized drops of ink. The print head has tiny nozzles to spray the ink. The printer head
moves back and forth and sprays ionized drops of ink on the paper, which is fed through the
printer. These drops pass through an electric field that guides the ink onto the paper to print
correct images and characters.

An inkjet printer has cartridges that contain ink. Modern inkjet printers are color printers that
have four cartridges containing different colors: Cyan, Magenta, Yellow, and Black. It is
capable of printing high-quality images with different colors. It can produce print objects with
a resolution of at least 300 dots per inch (dpi).

3) Projector
A projector is an output device that enables the user to project the output onto a large surface
such as a big screen or wall. It can be connected to a computer and similar devices to project
their output onto a screen. It uses light and lenses to produce magnified texts, images, and
videos. So, it is an ideal output device to give presentations or to teach a large number of people.

Modern projects (digital projectors) come with multiple input sources such as HDMI ports for
newer equipment and VGA ports that support older devices. Some projectors are designed to
support Wi-Fi and Bluetooth as well. They can be fixed onto the ceiling, placed on a stand, and
more and are frequently used for classroom teaching, giving presentations, home cinemas, etc.

A digital projector can be of two types:

Liquid Crystal Display (LCD) digital projector: This type of digital projectors are very
popular as they are lightweight and provide crisp output. An LCD projector uses transmissive
technology to produce output. It allows the light source, which is a standard lamp, to pass
through the three colored liquid crystal light panels. Some colors pass through the panels and
some are blocked by the panels and thus images are on the screen.

Digital Light Processing (DLP) digital projector: It has a set of tiny mirrors, a separate
mirror for each pixel of the image and thus provide high-quality images. These projectors are
mostly used in theatres as they fulfill the requirement of high-quality video output.

Plotters
.
Plotters are typically wide printers designed to reproduce architectural drawings, maps,
graphs, and diagrams on large sheets of paper. Plotters can be classified into the following
types.

Pen plotters (shown at right) use a vertical pen or pencil to draw images. The pen or pencil
may move over a static sheet of paper, or the plotter may move the paper beneath a static pen
or pencil. Pen plotters are slow and produce low-quality images but are the most commonly
used type due to their low cost of ownership.

Inkjet plotters spray drops of ink onto paper in a manner similar to inkjet printers. They are
capable of precise, clean images, are much faster than pen plotters, and are relatively
expensive to maintain.

Electrostatic plotters mark paper with electrostatic charges and run it through a developing
system to create an image. They produce high-quality images and are typically used by
graphic and commercial artists.

Thermal printers, which use heat-sensitive paper and heated pins, are specialty devices used
by cartographers and for applications requiring high-volume, two-color printing.

Difference between Plotter and Printer

S.No. PLOTTER PRINTER

It can read files in the DWG, CDR, It can read BMP, PDF and JPG TIFF
1 Al and other vector formats. formats.

It is a device that draws pictures on It is a device that brings images and texts
the page with the help of commands on the page with the help of commands
2 given through a computer. given through a network.

3 It is expensive . It is less costly as compared to plotters.

4 It can draw continuous lines. It cannot draw continuous lines.

5 It work on slow speeds. It work on fast speeds.

Its software includes Adobe Its software includes Photoshop and any
6 Illustrator, Corel, Flexi and CAD. other image-editing program.

It gives the output in a format that is It gives the output file data in a format such
7 similar to a vector graphic. as bitmap or pixels.

Examples are Drum plotters, Flatbed Examples are Laser Printers, Solid Ink
plotters, Pen plotters, Electrostatic Printers, LED Printers., Business Inkjet
8 plotters, Inkjet plotters. Printers, Home Inkjet, Printers, 3D Printers.