Input devices are used to enter data or commands in a form that the computer can use.
They send the data or commands to the processing unit.
According to the type of data they input, they can be grouped into the following :
a) Text input devices
b)Pointing input Devices
c) Imaging input Devices
d) Gaming input Devices
e) Audio input Devices
f) Biometric input Devices and
g) Other Specialized input devices
a) Text input devices
Text is a general word for all characters such as letters, numerical digits, symbols and marks that combine to form words, sentences, paragraphs and so on.
There is a variety of devices that help us to input text into a computer.
Text input devices include:
2.Voice Recognition Equipment
3.OMR and Barcode readers
4.OCR and Optical readers
7.Magnetic Strip Card Readers, etc.
1. The Keyboard
Definition: A keyboard is an input device, consisting of a set of keys (buttons) used to operate a computer. Each press of a key corresponds to a single written character of the text, but to produce some symbols, it requires pressing and holding several keys simultaneously.
Usually, a standard keyboard has between 80 to 110 keys.
A keyboard is the main and most reliable computer input device
The QWERTY is referred to as the “Universal” keyboard.
The name “QWERTY” comes from the first six letters in the top alphabet row (the one just below the numbers).
There are other setups also available such as Dvorak, ABCDE, GKOS, QWERTZ and AZERTY
Keypads, Keyers and chorded keyboards have fewer keys, specially designed for devices such a pocket-sized computer.
Christopher Latham Sholes was an American newspaper publisher
In 1866, he invented the first practical typewriter and the QWERTY keyboard still in use today.
Advantages of Keyboard
- Keyboards are very common (commonly supplied with computers)
- Entering data and commands with a keyboard is faster as compared to the mouse
- Keyboards are more reliable
Demerits of Keyboard
- It takes a lot of time to practice in order to type quickly
- Keys can easily become faulty due to dust.
- Some keyboards keys are very hard to press, causing fingers to hurt.
2. Voice Recognition Equipment
Voice Recognition Equipment (a.k.a Speech recognition ) converts spoken words to text.
Computers with Speech recognition do not actually understand speech, but they are programmed to recognize a vocabulary of words, which can range from two words to millions of words.
- No typing of data is necessary.
- Voice recognition can be used by people whose hands are disabled.
- Dictating text is faster than typing.
- Voice Recognition systems are also ideal for the blind.
HOW SPEECH RECOGNITION WORKS
Demerits of text input by speech Recognition
- The error rate is high, depending on the user’s accent.
- Words with the same pronunciations (Homophones) like see and sea cannot be distinguished
- Speech Recognition does cant work in a noisy environment
- Voice Recognition software must be trained to recognize more words.
- It requires the user to speak in a writing style, i.e. even pronouncing the marks such as a comma.
3. Optical mark recognition (OMR)
Optical mark recognition (OMR) devices read hand-drawn marks such as small circles or rectangles
A person places these marks on a form, such as a test, survey, or questionnaire answer sheet.
The OMR device first reads a master document, such as an answer key sheet for a test, to record correct answers based on patterns of light;
the remaining documents then are passed through the OMR device and their patterns of light are matched against the master document.
4. OMR and Barcode readers
A bar code reader is an optical reader that uses laser beams to read bar codes that are printed on items usually in supermarkets.
A bar code is an identification code that normally consists of a set of vertical lines and spaces of different widths.
The bar code represents some data that identifies the item and the manufacturer.
Optical character recognition (OCR)
Optical character recognition (OCR) is a technology that involves reading typewritten, computer-printed, or handwritten characters from ordinary documents and translating the images into a form that the computer can understand.
OCR devices include a small optical scanner for reading characters and sophisticated software (OCR software) for analyzing what is read.
5. MICR readers
A magnetic-ink character recognition (MICR) reader is used to read text printed with magnetized ink.
MICR readers are mainly used by the banking industry for processing checks
Each check is inserted into a MICR reader, which sends the check information to a computer for processing.
6. RFID readers
Radio-frequency identification (RFID) is a technology that uses radio waves to transfer data from an electronic tag, attached to an object, through a reader for the purpose of identifying and tracking the object.
RFID can work over a long distance.
An RFID tag can be affixed to cars, computer equipment, books, mobile phones, etc
7. Magnetic Strip Card Readers
A magnetic stripe card reader reads the magnetic stripe on the back of credit cards, bank ATM cards, and other similar cards.
Exposure to a magnet or magnetic field can erase the information and contents of a card’s magnetic stripe.
b) Pointing Devices
A pointing device is an input device, which allows users to move a pointer and make selections on the computer screen.
A pointing device is any piece of hardware that is used to input spatial data into a computer.
There are many examples of pointing devices such as:
2.Stylus pen & digitizing tablet
8.A Track Point
Mouse – The mouse is a hand held a device that lets you point to and make selections of items on your screen.
In a PC mouse, there are mostly 2-3 buttons.
A ball under the mouse senses movement.
An optical mouse uses a light-emitting diode and photodiodes to detect movement relative to the underlying surface.
2. Stylus pen & digitizing tablet
Stylus pen- The pen lets you draw on what is called a digitizing tablet that mirrors the surface area of the computer screen.
The pen can be used as a standard mouse (without wires connected to it) or also as a free-flowing drawing device.
The pen is useful for drawing since drawing graphics with a mouse tends to be somewhat difficult.
3. Cordless Mouse
Cordless Mouse – The cordless mouse is a lot better than a normal mouse. It reduces the amount of workspace needed to move the mouse around.
This mouse runs on a battery. When you move the mouse it sends an infrared beam to a sensor which interprets it causing the pointer to move.
Trackball – The trackball is an upside-down mouse that remains stationary on your desk. It is the same principle as the mouse except that the rollers are reversed and the ball is on top. This ball does not need as much attention as the normal mouse because the only thing that touches it is your hand as the normal mouse touches a surface.
5. Touch pad
Touch pad – The touch pad has sensors that sense your touch. When they sense your touch they send a signal to the computer to move the mouse pointer to that location on the screen. Common on laptop computers
7. Light pen
Light pen- is a 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, projectors and other display devices
8. Touch Screens
- A touch screen is a touch-sensitive input and display device. Users can interact with these devices by touching areas of the screen.
- You touch words, pictures, numbers, letter, pointers or special locations identified on the screen.
- With some smart phones, portable media players, and other personal mobile devices, you can touch the screen to perform tasks such as dialing telephone numbers, entering text, and making on-screen selections.
- Kiosks, which are freestanding computers, usually have touch screens. Many ATMs also have touch screens.
Examples of Touch Screens
9. Track Point
A Track Point also called a pointing stick, is a cursor control device located in the middle of the keyboard between the G, H, and B keys. The control buttons are located in front of the keyboard toward the user. The Track Point is operated by pushing in the general direction the user wants the cursor to move. Increasing pressure causes faster movement.
c) Imaging Devices
Imaging input Devices are devices that input images such as still photos, motion pictures, graphics, video etc. into the computer for processing.
Common Imaging devices include:
1. Image scanner
2. Digital Camera
3. Digital video (DV) camera
1. Image scanner
A scanner is a light-sensing input device that converts hardcopy documents, drawings, or pictures to an electronic version (softcopy), which can then be stored on a disk.
The electronic version of scanned material is in the form of rows and columns of dots called a bitmap
Each dot on a bitmap consists of one or more bits of data.
Common types of scanners include:
- Flatbed scanner
- Pen or handheld scanner
- Sheet bed scanner
- Drum scanner.
Image scanner ILLUSTRATIONS
A digital camera allows users to take pictures and store the photographed images digitally instead of storing on a traditional film.
When you take pictures, the images are electronically stored in the camera.
Later, you transfer a copy of the stored pictures to your computer or printer by connecting a cable between the digital camera and your computer.
Digital video (DV) camera
A digital video (DV) camera, by contrast records video as digital signals instead of analog signals.
To transfer recorded images to the computer hard disk, users connect DV cameras directly to a port on the system unit.
After saving the video on a storage medium, you can play it or edit it and burn it to a DVD using software programs on the computer.
Digital video (DV) camera (Illustration)
This is a light weight video camera that records data in digital form onto a storage device such as a videotape.
A Web cam, also called a PC video camera, is a type of digital video camera that usually sits on top of the monitor. Some laptop computers have built-in Web cams.
Webcams enable users to:
- capture video and still images,
- send e-mail messages with video attachments,
- add live images to instant messages,
- broadcast live images over the Internet,
- and make video telephone calls
Gaming Input Devices
Gaming input devices are devices specifically designed to be used for playing computer games.
7.Motion sensing game controllers
Gaming keyboards typically include programmable keys so that gamers can customize the keyboard to the game being played.
The keys on gaming keyboards light up so that the keys are visible in all lighting conditions.
Some have small displays that show important game statistics, such as time to targets remaining.
Gaming Keyboards (Illustration)
A gaming wheel is a steering wheel-type input device. Users turn the wheel to simulate driving a vehicle using programs on a computer.
Most gaming wheels also include foot pedals for acceleration and braking actions. Gaming wheels include buttons, called triggers that you press to initiate certain events.
Joystick- Consists 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 game pad controls the movement and actions of players or objects in video games or computer games.
On the gamepad, users press buttons with their thumbs or move sticks in various directions to trigger events.
Game pads communicate with a game console or a personal computer via wired or wireless technology.
Game pad (Illustration)
A light gun is used to shoot targets and moving objects after you pull the trigger on the weapon.
Instead of emitting light, most light guns work by detecting light. When the user pulls the trigger, the screen uses one of several techniques to send light, which is received by a receptor in the barrel of the gun.
Light Guns (Illustration)
A dance pad is a flat electronic device divided into panels that users press with their feet in response to instructions from a music video game.
These games test the user’s ability to step on the correct panel at the correct time, following a pattern that is matching with the beat of a song.
Motion sensing game controllers
These are devices that allow the user to guide onscreen elements by moving a handheld input device in predetermined directions through the air.
Examples include the power glove, play station move gadgets, among others.
e) Audio input Devices
Audio input is the process of entering any sound into the computer such as speech, music, and sound effects.
To enter sound into a computer, it must have a sound card.
Audio input devices are plugged into a port on the sound card.
Examples of audio input devices include
- Tape players,
- CD/DVD players,
- MIDI devices
A device that can be slotted into a computer to allow the use of audio components for multimedia applications.
Without a sound card, Audio input and output is not possible.
A microphone is an instrument for converting sound waves into electrical energy variations, which may then input into the computer for processing, recording or audio playback.
Microphones are connected to the sound card in the system unit.
MIDI (musical instrument digital interface) is the standard that defines how digital musical devices represent sound electronically.
MIDI devices such as electronic pianos allow users to record and edit music
For example, you can set the beat speed, and add notes, to produce sound.
This the earliest device most commonly used to record speech for later playback or to be typed into print.
It was established by Alexander Graham Bell in Washington, D.C. in 1881.
Biometric input Devices
A biometric device translates a biological personal characteristic into a digital code that is stored or compared with a digital code stored in the computer.
Common biometric devices include:
- Fingerprint scanner
- Face Recognition systems
- Hand geometry systems
- Signature verification systems
- Iris Recognition systems
A fingerprint scanner captures curves and indentations of a fingerprint.
Some grocery and retail stores now use fingerprint readers as a means of payment, where the customer’s fingerprint is linked to a an account or credit card.
Face Recognition systems
A face recognition system captures a live face image and compares it with a stored image to determine if the person is a legitimate user.
Some buildings use face recognition systems to secure access to rooms.
Hand geometry system
Biometric devices measure the shape and size of a person’s hand using a hand geometry system.
Some large companies use this system as time and attendance devices or as security devices.
Day-care centers use this system to verify parents who pick up their children.
Signature verification systems
A signature verification system recognizes the shape of your handwritten signature, as well as measures the pressure exerted and the motion used to write the signature.
Signature verification system uses a specialized pen and tablet.
Iris recognition system
These are devices that use iris recognition technology to read patterns in the iris of the eye.
These patterns are as unique as a fingerprint.
Iris recognition systems are used by government security organizations, the military, and financial institutions that deal with highly sensitive data.
g) Other Specialized input devices
There are many other special input devices that are used for doing special customized tasks. Some of them include:
Remote control devices emit a beam of infrared light, which carries data signals.
Remote control is commonly used with TVs but many laptop computers being produced come with remotes and a form of input device, which allow you to operate the laptop from a distance.
Chemical responses to the physical environment or movement can be converted to electrical signals by devices known as sensors, which input them it to the computer for processing.
Various sensors can be used to measure heat, light, pressure, acidity, oxygen concentration, water flow, etc.
THIS VIDEO EXPLAINS MORE ABOUT INPUT DEVICES