Input Devices

One of the most common ways to input data is by keyboard. It

translate numbers, letters, and special characters that people

understand into electrical signals.

There are a wide variety of different keyboard designs. The most common

types are:

Traditional keyboards, Flexible keyboard, Ergonomic keyboard,

Wireless keyboard, PDA keyboard

Full-sized, rigid, rectangular Full-sized, rigid, rectangular keyboards that include function, keyboards that include function, navigational, and numeric keys.navigational, and numeric keys.

Fold or roll up for easy packing or storage. Fold or roll up for easy packing or storage. They are designed to provide mobile users They are designed to provide mobile users with a full-sized keyboard with minimal with a full-sized keyboard with minimal storage requirements.storage requirements.

Similar to traditional keyboard. The Similar to traditional keyboard. The keyboard arrangement, however, is not keyboard arrangement, however, is not rectangular and a palm rest is provided. rectangular and a palm rest is provided. They are designed specifically to alleviate They are designed specifically to alleviate wrist strain associated with the repetitive wrist strain associated with the repetitive movements of typing.movements of typing.

Transmit input to the system unit Transmit input to the system unit through the air. By eliminating through the air. By eliminating connecting wires to the system unit, connecting wires to the system unit, these keyboards provide greater these keyboards provide greater flexibility and convenience.flexibility and convenience.

Miniature keyboards for PDA’s for Miniature keyboards for PDA’s for sending email, creating documents sending email, creating documents and more.and more.

A computer keyboard combines a A computer keyboard combines a typewriter keyboard with a typewriter keyboard with a numeric numeric keypadkeypad, used to enter numbers and , used to enter numbers and

arithmetic symbols. It also has many arithmetic symbols. It also has many special purpose keys. Some keys special purpose keys. Some keys

such as the Caps Lock key are such as the Caps Lock key are toggle toggle keyskeys. These keys turn a feature on or . These keys turn a feature on or

off. Other such as off. Other such as CtrlCtrl key are key are combination keyscombination keys, which perform an , which perform an

action when held down in action when held down in combination with another key. combination with another key. (See (See

Figure 7-4)Figure 7-4)

Pointing, of course, is one of the most natural of all human gestures.

Pointing devices provide a comfortable interface with the

system unit, by accepting pointing gestures and converting them into

machine-readable input.

There are a wide variety of different pointing devices including the

mouse, joystick, touch screen, light pen and stylus.

A mouse controls a pointer that is displayed on the monitor. The mouse pointer usually appears in the shape of an arrow. It frequently changes shape, however, depending on the application. A mouse can have one,

two, or more buttons, which are used to select command options and to control the mouse pointer on the

monitor . The three basic designs of mouse are mechanical, optical and

cordless or wireless mouse.

Mechanical mouse is generally considered the traditional type and is currently the most widely used. It has a ball on the

bottom and is attached with a cord to the system unit. As you move the mouse

across a smooth surface, or mouse pad, the roller rotates and controls the pointer

on the screen.

Optical mouse has no moving parts. It emits and senses light to detect mouse

movement. The newer type of mouse has some advantages compared to the

mechanical mouse: it can be used on any surface, is more precise, and does not

require periodic cleaning.

Cordless or wireless mouse is a battery-powered device that typically uses radio

waves or infrared light waves to communicate with the system unit. This

devices eliminate the mouse cord and free up desk space.

It is an upside-down version of the mouse. A It is an upside-down version of the mouse. A ball mounted in a box is rolled with the fingers ball mounted in a box is rolled with the fingers

to move the cursor. Some people prefer the to move the cursor. Some people prefer the trackball over the mouse because the trackball over the mouse because the

trackball does not require as much hand-eye trackball does not require as much hand-eye coordination, nor does it require the extra coordination, nor does it require the extra desk space to move the mouse pointer. It is desk space to move the mouse pointer. It is usually included in portable computers such usually included in portable computers such

as laptops.as laptops.

A A joystickjoystick is the most popular input device for is the most popular input device for computer games. You control a game actions computer games. You control a game actions by varying the pressure, speed, and direction by varying the pressure, speed, and direction of the joystick. Additional controls such as of the joystick. Additional controls such as buttons and triggers are used to specify buttons and triggers are used to specify commands or initiate specific actions. commands or initiate specific actions.

A A touch screentouch screen is a particular kind of monitor is a particular kind of monitor with a clear plastic outer layer. Behind this with a clear plastic outer layer. Behind this layer are criss-crossed invisible beams of layer are criss-crossed invisible beams of infrared light. infrared light. This arrangement This arrangement enables someone to enables someone to select actions or select actions or commands by touching commands by touching the screen with a finger. the screen with a finger. Touch screens are easy Touch screens are easy to use, especially when to use, especially when people need information people need information quickly. They are quickly. They are commonly used at commonly used at restaurants, ATM, and restaurants, ATM, and information centers.information centers.

A A light penlight pen is a light-sensitive pen-like device. is a light-sensitive pen-like device. The light pen is placed against the monitor. The light pen is placed against the monitor. This closes a photoelectric circuit and This closes a photoelectric circuit and identifies the spot for entering or modifying identifies the spot for entering or modifying data. For example, light pens are used to edit data. For example, light pens are used to edit digital images. digital images.

Scanners move across text and images. Scanning devices convert

scanned text and images into a form that the system unit can process.

There are three type of scanning devices:

Optical scanners, Bar code readers, and Character and Mark recognition

devices.

An An optical scanneroptical scanner, also known as a , also known as a scannerscanner, , accepts documents consisting of text and/or accepts documents consisting of text and/or

images and converts them to machine images and converts them to machine readable form. There are two types of readable form. There are two types of

scanners: scanners: flatbedflatbed and and portableportable scannerscanner. .

These devices are either handheld These devices are either handheld wand wand readersreaders or or platform scannersplatform scanners. They contain . They contain photoelectric cells that scan or read photoelectric cells that scan or read bar bar codescodes, or the vertical zebra-striped marks , or the vertical zebra-striped marks printed on product containers. printed on product containers.

Character and mark recognition devicesCharacter and mark recognition devices are scanners that are able to recognize are scanners that are able to recognize special characters and marks. They are special characters and marks. They are

specialty devices that are essentials specialty devices that are essentials tools for certain applications. tools for certain applications.

Three types are: Three types are: Magnetic-ink character Magnetic-ink character recognition (MICR),recognition (MICR), Optical-character Optical-character

recognition (OCR),recognition (OCR), Optical-mark Optical-mark recognition (OMR).recognition (OMR).

Used by banks to automatically read those Used by banks to automatically read those unusual numbers on the bottom of checks and unusual numbers on the bottom of checks and

deposit slips. A special purpose machine deposit slips. A special purpose machine known as known as reader/sorterreader/sorter reads these numbers reads these numbers

and provides input that allows banks to and provides input that allows banks to efficiently maintain customer account efficiently maintain customer account

balances. balances.

Uses special preprinted characters that can be Uses special preprinted characters that can be read by a light source and changed into read by a light source and changed into

machine-readable code. A common OCR device machine-readable code. A common OCR device is the handheld is the handheld wand readerwand reader. These are used . These are used in department stores to read retail price tags in department stores to read retail price tags by reflecting light on the printed characters.by reflecting light on the printed characters.

Also called Also called mark sensingmark sensing. An OMR device . An OMR device senses the presence or absence of a mark, senses the presence or absence of a mark,

such as a pencil mark, OMR is often used to such as a pencil mark, OMR is often used to score multiple-choice tests such as the College score multiple-choice tests such as the College

Board’s Scholastic Aptitude Test (SAT) and Board’s Scholastic Aptitude Test (SAT) and Graduate Record Examination (GRE). Graduate Record Examination (GRE).

Optical Scanners, like traditional copy machines, can make a copy from an original. For example, an optical scanner can make a digital

copy of a photograph. Image capturing devices, on the other hand, create or capture original

images.

These devices include digital cameras and digital video cameras

Digital camerasDigital cameras are similar to traditional are similar to traditional cameras except that images are recorded cameras except that images are recorded

digitally on a disk or in the camera’s memory digitally on a disk or in the camera’s memory rather than on a film, and rather than on a film, and downloadeddownloaded, or , or

transferred, to your computer. transferred, to your computer.

Unlike traditional video cameras, Unlike traditional video cameras, digital video digital video camerascameras record motion digitally on a disk or in record motion digitally on a disk or in

the camera’s memory. Most have the the camera’s memory. Most have the capability to take still images as well. capability to take still images as well.

Digitizing devices convert a sketch or figure into a form that can be

processed by a computer. Similar to slate tablet PCs, these devices have

some type of flat surface and a writing device. As the user moves

the writing device across the surface, the digitizing device records the movement as a series of points and sends this information to the

computer. Two widely used digitizing devices are graphics tablets and digital notebooks.

Graphics tablet Graphics tablet use a special graphics surface use a special graphics surface or tablet and s special stylus or pen-like or tablet and s special stylus or pen-like

device. The user either directly sketches on device. The user either directly sketches on the tablet or traces images that have been the tablet or traces images that have been

placed on the tablet.placed on the tablet.

Digital notepadsDigital notepads are similar to tablet PCs are similar to tablet PCs except that they typically use regular notepads except that they typically use regular notepads

and pens.and pens.

Audio input devices convert sounds into a form that can be processed by

the system unit. By far the most widely used audio input device is the

microphone.

Audio input can take many forms including human voice and music.

Voice recognition systemsVoice recognition systems use a microphone, use a microphone, sound card, and special software. These sound card, and special software. These

systems allow users to operate computers and systems allow users to operate computers and to create documents using voice commands. to create documents using voice commands.

Portable voice recognition systems are widely Portable voice recognition systems are widely used by doctors, lawyers, and others to record used by doctors, lawyers, and others to record

dictation.dictation.

Discrete-speech recognition systems are able to recognize individual word

based on their sound.

Continuous-speech recognition systems are able to distinguish

between same-sounding words by evaluating the context within which

individual words are used.