Computer Notes Chapter-10 INPUT/OUTPUT DEVICE ! Input device ! KEYBOARD DEVICES ! MOUSE ! TRACKBALL !JOYSTICK ! ELECTRONIC PEN ! TOUCH SCREEN ! DATA SCANNING DEVICES ! IMAGE SCANNING ! WEB CAMERAS ! OUTPUT DEVICE ! Monitor ! Printers ! TYPES OF PRINTERS ! Plotter !

 INPUT/OUTPUT DEVICES 

The physical components of a computer are known as hardware. such physical components may be electronic. electrical. magnetic. mechanical or optical. some such parts are microprocessor, integrated circuit (ICs), hard disk, floppy disks, color monitor. keyboard. printer. plotter etc.

Input device :

 An input device is an electromechanical device, which accepts data from the outside word, and translates them into a from. which the computer can interpret several input devices are available today They can be broadly classified into the following categories.

1. Keyboard 

2. Point and draw devices

3. Data scanning devices

KEYBOARD DEVICES:

Keyboard devices are the most commonly used input devices today They allow data entry into a computer system by pressing a set of keys (labeled buttons), which are neatly mounted on a keyboard, which is connected to the computer system. The most popular keyboard used today is the 101-keys QWERTY keyboard.

MOUSE:

Mouse is the most popular point and draw devices. it has become a must-have input device on personal computers and workstations, which have GBl-based user interface. A mouse is a small hand - held device, which can comfortable fit in a user's palm, it rolls on a small bearing, and has one or more buttons on the top. when a user rolls the mouse across a flat surface, such as on  top the table on which the computer is placed, the  graphics cursor  moves on the screen of the video display terminal in the direction of the mouse's movement. The graphics cursor, which is used to point and draw , is displayed on the screen as a variety of symbols, such as on arrow, a wrist whit a pointing finger, etc, depending on the application, the text and graphics cursor may be displayed on the screen at the same time.

TRACKBALL :

A trackball is pointing device, which is similar to a mouse. A trackball requires less space than a mouse for operation. Since it need not be moved for moving the graphics cursor, it is often attached to or built into the keyboard. Trackballs built onto the keyboard are commonly used in laptop (notebook) computers, because a mouse is fixed on the top, some people find it helpful to of a trackball as an upside-down mouse.A trackball comes in various shapes and forms with the same functionality. The three commonly used shaped are a ball, a button and a square. In case of a ball, the ball is rolled with the help of fingers to move the graphics cursor.

JOYSTICK:

A joystick is a pointing device, which works on the same principle as a trackball, to make the movement of the spherical ball easier. the spherical ball, which moves in a socket, has stick mounted on it the user of a joystick moves the spherical ball with the help or the sick with his/her hand The stick can be moved forward or backward, left or right, to move and position the graphics cursor at the desired position .

Typical used of a joystick include video games, flight simulators, training simulators, and for controlling industrial  robots.

ELECTRONIC PEN:

 

Another pointing devices is an electronic pen. in  a pen based system,you hold the pen in your hand, and directly point with it on the screen to select menu items or icons or directory draw graphics on the screen with it or writen it on a special pad  direct input of the written information to the system.

TOUCH SCREEN:

Touch screen is the most simple, intuitive, and easiest to learn of all input devices. A touch screen enables the user to choose from valuable options by simply touching with their fingers the desired or menu items displayed on the computer's screen.

Touch screen are the most preferred human-computer interface devices used in information kiosks , information kiosks may be located at an airport or a railway station to provide information to arriving passengers about hotels, restaurants, tourists spots,etc in the city.

DATA SCANNING DEVICES:

Data scanning devices are input devices, which are used for direct data entry into the computer system from source document. Data scanning devices are of many types. some of the commonly used ones are described below.

IMAGE SCANNER:

An image scanner is an input device. The input documents may be typed text, pictures, graphics or even handwritten material. image scanner comes in various shapes and sizes. The two commonly used types are.

1. Flatbed scanner: A flatbed scanner is like a copy machine , which consists of a box having a glass plate on its top and a lid that covers the glass plate. The document to be scanned is placed upside down on the glass plate. The light source is situated below the glass plate, and moves horizontally from left to right when activated After scanning one line the light beam moves up a little, and scans the next line. The process is repeated for all the  lines, it takes about 20 seconds to scan a document of size 21 cm*28cm.

2. Hand-held scanner :   A hand-held scanner has a set of light emitting diodes encased in a small case ,which can be conveniently held in hard during operation .to scan a document , the scanner is slowly dragged from one end of the document to its other end , with its light on the scanner has to be dragged very steadily and carefully over the document ,otherwise the conversion of the document into its equivalent bit map will be correct. Due to this reason, hand -held scanner are  used only in cases where high accuracy is not needed. They are also used when the volume of documents to be scanned is low. They are also much cheaper as compared to flatbed scanners.

WEB CAMERAS :

 

A web camera  allow a computer to accept input just by focusing on an object. The camera is focused on the object to take a picture of the object picture so taken can be transferred over networking to a  distant place.

The image of the object can be seen on the monitor of the distant computer connected through a network or through internet. Voice can also be transmitted over the network. Thus, two or more persons can talk and see one another in this way. This method is used in video conferencing.

OUTPUT DEVICE :-

 An output device is an electromechanical device, which accepts data from a computer and translates them into a form, which is suitable for use by the outside word (the uses). Several output devices are available today. They can be broadly classified into the following categories.   

1. Monitors

2. Printers

3. Plotters

4. Screen image projector 

5. Voice response systems

Output device generate computer output, which can be broadly classified into the following two types. 

1. Soft-copy output

2. Hard-copy output

Monitor:

Monitor are by far the most popular output,devices used today for producing soft-copy output. A monitor is usually associated with a keyboard and together they form a video display terminal (VDT) VDT (often referred to as just terminal) is the most popular input/output (I/O) device used with today's computer. That is it serves both an input and an output device. The keyboard is used for input to the computer, and the monitor is used to display the output from the computer. Then name"terminal" comes from the fact that terminal is at the terminal, or end, point of a communication path.

The two basic types of monitors used today are cathode-ray-tube (CRT) and flat-panel. The CRT monitor look much like a television, and are used with non-portable computer systems. on the other hand, the flat-panel monitors are thinner and lighter, and are commonly used with portable computer systems. like notebook computers.

Printers:

Printers are hardware devices that allow you to create  a hard copy of a file. Today a printer is a necessary requirement for any home user and business. Allowing individuals to save their work in the format of paper instead of electronically.

The standard length of printer parallel cables is a maximum of 15 feet although there are 50- foot cables it is not recommended that these cable be used as it can create poor connections and data signals 

TYPES OF PRINTERS :

Below is a listing of the various types of printers available for computers.

1. Dot Matrix Printer- Type of printer that employs movable print heads with pins or wires that shoot and strike the ribbon placing a dot on the paper with hundreds of dots forming images or text.

2. Inkjet Printer -  Printer developed by Canon which forms letters and images on the paper by spraying small streams of quick-drying ink. The ink is stored in a disposable ink cartridge.

3. Laser Printer -  Laser printers are printer that uses laser technology to print images on the paper. The laser, recreates  the image on a negatively charges drum, which will then collect ink that is positively charged to attract to the areas of the image. The paper is then negatively charged therefore the positively charged ink is attracted to the paper and then is fused onto the paper. see laser printer printing steps for step by step procedure of laser printers. 

4. Thermal Printer- A printer that uses heated pins to "burn" images onto heat-sensitive paper.The pins are electrically heated and brought into contact with the specially treated paper easily, instead of with great impact. The coating on the paper discolors when heated in this way. These printers, used in calculators and many fax machines, are  inexpensive, but produce low-quality, low-resolutions print. They are however, quiet and fast as they print. 

5. Plotter :

       We saw above that dot matrix, inkjet and laser printers are capable of producing graphics output.

However many engineering design application, like architectural plan of a  building design of mechanical components of an aircraft or a car, etc, often require high-quality, perfectly-proportioned graphic output on large sheets. The various types of printer discussed above are not suitable for meeting  this output requirement of such application. A special type of output device, called plotters, is used for this purpose. plotters are ideal output device for architects, engineers, city planners and others who need to routinely generate high precision, hard copy, and graphic.