Input Devices

An input device is anything that puts information inside a computer. It is a

hardware device that sends information into the CPU. Without any input

devices a computer would simply be a display device and not allow users to

interact with it. Any machine that feeds data into a computer is called input

devices. It provide means of communication between a computer and outer

world. Also known as peripheral devices because it surround the CPU

and memory of a computer system. Input devices are used to enter data

from the outside world into primary storage.

Commonly use Input Devices

Keyboard devices

Point-and-draw devices

Data scanning devices

Digitizer

Electronic cards based devices

Speech recognition devices

Vision based devices

Keyboard

A keyboard is an input device, partially modeled after the typewriter keyboard, which

uses an arrangement of buttons or keys, to act as mechanical levers or electronic

switches. A keyboard typically has characters engraved or printed on the keys and each

press of a key typically corresponds to a single written symbol. However, to produce

some symbols requires pressing and holding several keys simultaneously or in sequence.

While most keyboard keys produce letters, numbers or signs (characters), other keys or

simultaneous key presses can produce actions or computer commands. In normal usage,

the keyboard is used to type text and numbers into a word processor, text editor or other

program. In a modern computer, the interpretation of key presses is generally left to the

software. A computer keyboard distinguishes each physical key from every other and

reports all key presses to the controlling software. Keyboards are also used for computer

gaming, either with regular keyboards or by using keyboards with special gaming

features, which can expedite frequently used keystroke combinations. A keyboard is also

used to give commands to the operating system of a computer, such as Windows'

Control-Alt-Delete combination, which brings up a task window or shuts down the

machine.

Point and Draw devices

A pointing device is any human interface device that allows a user to input spatial data to

a computer. In the case of mice and touch screens, this is usually achieved by detecting

movement across a physical surface. Analog devices, such as 3D mice, joysticks, or

pointing sticks, function by reporting their angle of deflection. Movements of the

pointing device are echoed on the screen by movements of the cursor, creating a simple,

intuitive way to navigate a computer's GUI.

Some of the Point and draw devices are:-

Mouse Track ball

Joy stick

Light pen

Touch screen

Mouse

A mouse (plural mouses, mice, or mouse devices.) is a pointing device that functions by

detecting two-dimensional motion relative to its supporting surface. Physically, a mouse

consists of an object held under one of the user's hands, with one or more buttons. It

sometimes features other elements, such as "wheels", which allow the user to perform

various system-dependent operations, or extra buttons or features can add more control or

dimensional input. The mouse's motion typically translates into the motion of a pointer

on a display, which allows for fine control of a Graphical User Interface.

Trackball

A trackball is a pointing device consisting of a ball held by a socket containing sensors to

detect a rotation of the ball about two axes—like an upside-down mouse with an exposed

protruding ball. The user rolls the ball with the thumb, fingers, or the palm of the hand to

move a cursor. Large tracker balls are common on CAD workstations for easy precision

Before the advent of the touchpad, small trackballs were common on portable

computers, where there may be no desk space on which to run a mouse. Some small

thumbballs clip onto the side of the keyboard and have integral buttons with the same

function as mouse buttons. The trackball was invented by Tom Cranston and Fred

Longstaff as part of the Royal Canadian Navy's DATAR system in 1952, eleven years

before the mouse was invented. This first trackball used a Canadian five-pin bowling

ball.

Joystick

A joystick is an input device consisting of a stick that pivots on a base and reports its

angle or direction to the device it is controlling. Joysticks are often used to control video

games, and usually have one or more push-buttons whose state can also be read by the

computer. A popular variation of the joystick used on modern video game consoles is the

analog stick. The joystick has been the principal flight control in the cockpit of many

aircraft, particularly military fast jets, where centre stick or side-stick location may be

employed (see also Centre stick vs side-stick). Joysticks are also used for controlling

machines such as cranes, trucks, underwater unmanned vehicles, wheelchairs,

surveillance cameras and zero turning radius lawn mowers. Miniature finger-operated

joysticks have been adopted as input devices for smaller electronic equipment such as

mobile phones.

Light pen

A light pen is a computer input device in the form of a light-sensitive wand used in

conjunction with a computer's CRT TV set or monitor. It allows the user to point to

displayed objects, or draw on the screen, in a similar way to a touch screen but with

greater positional accuracy. A light pen can work with any CRT-based display, but not

with LCD screens (though Toshiba and Hitachi displayed a similar idea at the "Display

2006" show in Japan), projectors and other display devices. A light pen is fairly simple

to implement. Just like a light gun, a light pen works by sensing the sudden small change

in brightness of a point on the screen when the electron gun refreshes that spot. By

noting exactly where the scanning has reached at that moment, the X,Y position of the

pen can be resolved. This is usually achieved by the light pen causing an interrupt, at

which point the scan position can be read from a special register, or computed from a

counter or timer. The pen position is updated on every refresh of the screen. The light

pen became moderately popular during the early 1980s.

Touch screen

A touchscreen is a display that can detect the presence and location of a touch within the

display area. The term generally refers to touch or contact to the display of the device by

a finger or hand. Touchscreens can also sense other passive objects, such as a stylus.

However, if the object sensed is active, as with a light pen, the term touchscreen is

generally not applicable. The ability to interact directly with a display typically indicates

the presence of a touchscreen. The touchscreen has two main attributes. First, it enables

one to interact with what is displayed directly on the screen, where it is displayed, rather

than indirectly with a mouse or touchpad. Secondly, it lets one do so without requiring

any intermediate device, again, such as a stylus that needs to be held in the hand. Such

displays can be attached to computers or, as terminals, to networks. They also play a

prominent role in the design of digital appliances such as the personal digital assistant

(PDA), satellite navigation devices, mobile phones, and video games.

Scanners

A scanner is a device that optically scans images, printed text, handwriting, or an object,

and converts it to a digital image. Common examples found in offices are variations of

the desktop (or flatbed) scanner where the document is placed on a glass window for

scanning. Hand-held scanners, where the device is moved by hand, have evolved from

text scanning "wands" to 3D scanners used for industrial design, reverse engineering,

test and measurement, orthotics, gaming and other applications. Mechanically driven

scanners that move the document are typically used for large-format documents, where a

flatbed design would be impractical. Modern scanners typically use a charge-coupled

device (CCD) or a Contact Image Sensor (CIS) as the image sensor, whereas older drum

scanners use a photomultiplier tube as the image sensor. A rotary scanner, used for

high-speed document scanning, is another type of drum scanner, using a CCD array

instead of a photomultiplier. Other types of scanners are planetary scanners, which take

photographs of books and documents, and 3D scanners, for producing three-dimensional

models of objects.

Types of Scanners are:-

1. Image Scanners (a)Flatbed scanners (b)Handheld scanners

2. OCR (Optical Character recognition)

3. OMR (Optical Mark Reader)

4. Bar code Reader

5. MICR (Magnetic Ink Character Recognition).

Image Scanners

Flatbed Scanners:- Flatbed scanners will take up some desktop space but provide a lot

bang for the buck. They look like miniature printers with a flip up cover protecting the

glass platen. Depending on its size, a flatbed scanner can fit standard or legal-sized

documents, and the flexible cover allows you to scan large items such as books. These

scanners are great for scanning the occasional newspaper article, book chapter, or

photograph; or for those who may need to scan or bulky items such as the cover of a

DVD. Flatbed scanners are often built into multifunction printers (MFPs).

Handheld Scanners :- A small handheld scanning device used for digitizing images.

While images from a handheld scanner are considered low quality, today's technology

enables full color 24 bit scanning. Depending on the scanner device type and

manufacturer, handheld scanners can also define, translate, and hear printed text, and can

also store and beam text to computers and other devices. A scanner that is moved across

the image to be scanned by hand. Handheld scanners are small and less expensive than

their desktop counterparts, but rely on the dexterity of the user to move the unit across

the paper. Trays are available that keep the scanner moving in a straight line. Contrast

with flatbed scanner, sheet-fed scanner and drum scanner.

Optical Character Recognition

Optical character recognition, usually abbreviated to OCR, is the mechanical or

electronic translation of images of handwritten, typewritten or printed text (usually

captured by a scanner) into machine-editable text. It is used to convert paper books and

documents into electronic files, for instance, to computerize an old record-keeping

system in an office, or to serve on a website such as Project Gutenberg. When one scans

a paper page into a computer, it produces just an image file, a photo of the page. The

computer cannot understand the letters on the page, so you cannot search for words or

edit it and have the words re-wrap as you type, or change the font, as in a word

processor. You would use OCR software to convert it into a text or word processor file

so that you could do those things. The result is much more flexible and compact than the

original page photo. OCR is a field of research in pattern recognition, artificial

intelligence and computer vision. Though academic research in the field continues, the

focus on OCR has shifted to implementation of proven techniques. Optical character

recognition (using optical techniques such as mirrors and lenses) and digital character

recognition (using scanners and computer algorithms) were originally considered

separate fields. Because very few applications survive that use true optical techniques,

the OCR term has now been broadened to include digital image processing as well.

Optical Mark Reader

Optical Mark Recognition (also called Optical Mark Reading and OMR) is the process of

capturing human-marked data from document forms such as surveys and tests. OMR

devices work with a dedicated scanner device that shines a beam of light onto the form

paper. The contrasting reflectivity at predetermined positions on a page is then utilized to

detect the marked areas because they reflect less light than the blank areas of the paper.

Some OMR devices use forms which are preprinted onto 'transoptic' paper and measure

the amount of light which passes through the paper, thus a mark on either side of the

paper will reduce the amount of light passing through the paper. In contrast to the

dedicated OMR device, desktop OMR software allows a user to create their own forms

in a word processor and print them on a laser printer. The OMR software then works

with a common desktop image scanner with a document feeder to process the forms once

filled out. OMR is generally distinguished from optical character recognition by the fact

that a complicated pattern recognition engine is not required. That is, the marks are

constructed in such a way that there is little chance of not reading the marks correctly.

This does require the image to have high contrast and an easily-recognizable or

irrelevant shape. A related field to OMR and OCR is the recognition of barcodes such as

the UPC bar code found on product packaging. One of the most familiar applications of

optical mark recognition is the use of #2 (HB in Europe) pencil bubble optical answer

sheets in multiple choice question examinations. Students mark their answers, or other

personal information, by darkening circles marked on a pre-printed sheet.

Bar Code Reader

A barcode reader (or barcode scanner) is an electronic device for reading printed barcodes. Like a flatbed scanner, it consists of a light source, a lens and a light sensor translating optical impulses into electrical ones. Additionally, nearly all barcode readers contain decoder circuitry analyzing the barcode's image data provided by the sensor and sending the barcode's content to the scanner's output port. Many different types of barcode scanners are available. Some of them are:

Pen type readers :- Pen type readers consist of a light source and a photodiode that are placed next to each other in the tip of a pen or wand. To read a bar code, you drag the tip of the pen across all the bars in a steady even motion. The photodiode measures the intensity of the light reflected back from the light source and generates a waveform that is used to measure the widths of the bars and spaces in the bar code. Dark bars in the bar code absorb light and white spaces reflect light so that the voltage waveform generated by the photo diode is an exact duplicate of the bar and space pattern in the bar code.

CCD Readers :- CCD readers (also referred to as LED scanner) use an array of hundreds of tiny light sensors lined up in a row in the head of the reader. Each sensor can be thought of as a single photodiode that measures the intensity of the light immediately in front of it. Each individual light sensor in the CCD reader is extremely small and because there are hundreds of sensors lined up in a row, a voltage pattern identical to the pattern in a bar code is generated in the reader by sequentially measuring the voltages across each sensor in the row. The important

difference between a CCD reader and a pen or laser scanner is that the CCD reader is measuring emitted ambient light from the bar code whereas pen or laser scanners are measuring reflected light of a specific frequency originating from the scanner itself.

Camera-Based Readers :- 2D imaging scanners are the fourth and newest type of bar code reader currently available. They use a small video camera to capture an image of a bar code. The reader then uses sophisticated digital image processing techniques to decode the bar code. Video cameras use the same CCD technology as in a CCD bar code reader except that instead of having a single row of sensors, a video camera has hundreds of rows of sensors arranged in a two dimensional array so that they can generate an image.

Magnetic Ink Character Recognition

Magnetic Ink Character Recognition, or MICR, is a character recognition technology

used primarily by the banking industry to facilitate the processing of cheques. The

technology allows computers to read information (such as account numbers) off of

printed documents. Unlike barcodes or similar technologies, however, MICR codes can

be easily read by humans. MICR characters are printed in special typefaces with a

magnetic ink or toner, usually containing iron oxide. As a machine decodes the MICR

text, it first magnetizes the characters in the plane of the paper. Then the characters are

then passed over a MICR read head, a device similar to the playback head of a tape

recorder. As each character passes over the head it produces a unique waveform that can

be easily identified by the system. The use of magnetic printing allows the characters to

be read reliably even if they have been overprinted or obscured by other marks, such as

cancellation stamps. The error rate for the magnetic scanning of a typical check is

smaller than with optical character recognition systems. For well printed MICR

documents, the "can't read" rate is usually less than 1% while the substitution rate

(misread rate) is in the order of 1 per 100,000 characters.

Digitizers

Digitizers or digitization is the representation of an object, image, sound, document or a

signal (usually an analog signal) by a discrete set of its points or samples. The result is

called digital representation or, more specifically, a digital image, for the object, and

digital form, for the signal. Strictly speaking, digitizing means simply capturing an

analog signal in digital form. McQuail identifies the process of digitization having

immense significance to the computing ideals as it "allows information of all kinds in all

formats to be carried with the same efficiency and also intermingled" The term

digitization is often used when diverse forms of information, such as text, sound, image

or voice, are converted into a single binary code. Digital information exists as one of two

digits, either 0 or 1. These are known as bits (a contraction of binary digits) and the

sequences of 0s and 1s that constitute information are called bytes. Analog signals are

continuously variable, both in the number of possible values of the signal at a given

time, as well as in the number of points in the signal in a given period of time. However,

digital signals are discrete in both of those respects – generally a finite sequence of

integers – therefore a digitization can only ever be an approximation of the signal it

represents.

Electronic-Card Reader

A card reader is an input device which help us to read different types of cards. A card

reader can read memory card, Debit card, Credit card etc. A memory card reader is a

device used for communication with a smart card or a flash memory card. A business

card reader is a scanning device used to scan and electronically save business cards. A

magnetic card reader is a device used to scan cards containing magnetic data strips. A

punched card reader is a device used to read holes in punched cardboard cards. A smart

card reader is an electronic device that reads smart cards. Some keyboards have a built-in

card reader. There are external devices and internal drive bay card reader devices for PC.

Some laptops have built-in smart card reader. Some have a flash upgradeable firmware.

The card reader supplies the integrated circuit on the smart card with electricity.

Communication is done via protocols and you can read and write to a fixed address on

the card.

Speech Recognition Device

A voice command device is a device controlled by means of the human voice. By

removing the need to use buttons, dials and switches, consumers can easily operate

appliances with their hands full or while doing other tasks. The first examples in home

appliances are washing machines that allows consumers to operate washing controls

through vocal commands, and mobile phones with voice-activated dialing. Newer VCDs

are speaker-independent, so they can respond to multiple voices, regardless of accent or

dialectal influences. They are also capable of responding to several commands at once,

separating vocal messages and providing appropriate feedback, accurately imitating a

natural conversation. They can understand around 50 different commands and retain up

to 2 minutes of vocal messages.Speech recognition (also known as automatic speech

recognition or computer speech recognition) converts spoken words to text. The term

"voice recognition" is sometimes used to refer to speech recognition where the

recognition system is trained to a particular speaker - as is the case for most desktop

recognition software, hence there is an aspect of speaker recognition, which attempts to

identify the person speaking, to better recognize what is being said. Speech recognition

is a broad term which means it can recognize almost anybodys speech - such as a

call centre system designed to recognize many voices.

There are two types of Speech recognition devices:-

1. Single word recognition system :- In this system can recognition only a singlespoken word like NO, YES,MOVE etc.

2. Continuous speech recognition system :- In this system can recognition spoken sentence like MOVE TO THE NEXT BLOCK etc.

Vision Input system

Vision recognition is a topic in computer science and language technology with the goal

of interpreting human gestures via mathematical algorithms. Gestures can originate from

any bodily motion or state but commonly originate from the face or hand. Current

focuses in the field include emotion recognition from the face and hand gesture

recognition. Many approaches have been made using cameras and computer vision

algorithms to interpret sign language. However, the identification and recognition of

posture, gait, proxemics, and human behaviors is also the subject of gesture recognition

techniques. vision recognition can be seen as a way for computers to begin to understand

human body language, thus building a richer bridge between machines and humans than

primitive text user interfaces or even GUIs (graphical user interfaces), which still limit

the majority of input to keyboard and mouse. Vision recognition enables humans to

interface with the machine (HMI) and interact naturally without any mechanical devices.

Using the concept of gesture recognition, it is possible to point a finger at the computer

screen so that the cursor will move accordingly. This could potentially make

conventional input devices such as mouse, keyboards and even touch-screens redundant.