Download
1 / 63
640 likes | 896 Vues
C. omputer. Devices. I. nput. Input Peripherals. Input devices are used to feed data to your computer. The users enter data through input devices, the computer converts it to binary, and then the CPU reads the data.
E N D
C omputer Devices I nput
Input Peripherals Input devices are used to feed data to your computer. • The users enter data through input devices, the computer converts it to binary, and then the CPU reads the data. • They are connected to the computer via ports to manage the transfer of data between the computer and the devices.
Keyboard • Application - Word Processing, • The keyboard we normally use has a qwerty layout. • Apart from character keys, a keyboard has the function keys, cursor control keys, page control etc.. • Pressing a key on the keyboard causes a scan code to be sent to the computer via the keyboard port. • Nowadays keyboards are more ergonometric and are being designed to reduce stress.
Typists can use with ease. Every computer comes with a keyboard If you are not a fast typist, it can be relatively slow. Advantages and Disadvantages Note : keyboards can be found with wire and without (wireless)
Mouse • Application– Computer Aided Design • Used to position the cursor on the screen by moving it about on your tabletops
Mouse ball housing Mouse ball Different types of Mouse • Ball Mouse : which has a ball underneath which as the muse is moved a flat surface enables a corresponding mouse cursor to move in the same direction on the screen.
2.Opt mechanical: Same as a mechanical mouse, but uses optical sensors to detect motion of the ball. 3. Optical: Uses a laser to detect the mouse's movement. Optical mice have no mechanical moving parts. They respond more quickly and precisely than mechanical and opt mechanical mice. Note : mouse can be found with wire and without (wireless)
Allows diagrams to be easily drawn and modified, therefore it is very versatile for drawing packages. Relatively cheap. Easy and convenient to use. Selects a position on screen more quickly than is possible with a keyboard. Uses more desk space than any other pointing device. It cannot be used to input text Relatively slow for selecting options from menus. Requires a flat surface to operate. Advantages and Disadvantages
Trackball • Application – Drawing Packages and Menu Selection • It works exactly like a mouse, except that the ball is rotated by hand. • This device was initially used with laptop computers.
Uses less desk space than a mouse. More finger movement needed to reach buttons than any other pointing device. Advantages and Disadvantages
Joystick • Application – Playing games and computer simulation • Enables the user to control movement on the screen by maneuvering a small lever. • It usually has buttons with which actions can be carried out.
Allows the fast interaction needed in games. Much easier than using a keyboard. Cannot be used to accurately select options from screen Special interface required. Advantages and Disadvantages
Touch Pad • Application – Menu Selection • Touch pads let you control the pointer with your finger. • As you move your fingertip, the cursor follows the movement. • You click by tapping the finger on the pad’s surface.
Less prone to dust. Small active movements makes precise cursor control difficult Advantages and Disadvantages
Light Pen • Application – Computer Aided Design • It is a light sensitive device • It can be used to write or draw on the screen • It has to be used with a device which outputs light • When the tip of the pen is placed next to the display screen, light coming from the screen is detected by a photo detector in the tip of the pen. • Then the software determines the screen location (x and y coordinates) where the light pen is pointing
More direct and precise than using a mouse Easier to draw with Can record only the presence or absence of light Requires software written specially for it Advantages and Disadvantages
Touch Screen • Application – Fast Food and Menu Selection • The user need only to point a finger to indicate the location needed.
Different types of Touch Screen • LEDs are placed along a vertical and horizontal edge of the screen and a series of photo detectors along the opposite sedges. When the user touches the screen one or more LEDs are blocked in the vertical and horizontal directions so the software can determine the approximate location the user pointed at. • A pressure sensitive membrane is placed over the screen. Pressure on this membrane is detected by the computer and then the software calculates the position
User just uses his finger It is very useful for people whose work involves a lot of movement or standing up Accuracy of a touch screen is not very good so this restrict them to selecting function “Not useful when needing to input large amount of data Advantages and Disadvantages
Graphics Tablet • Application – Computer Aided Design • It is a flat surface that has a fine grid of vertical and horizontal wired embedded in it. • Attached to you find the stylus (like a pen) • Like the touch sensitive screen the device controller can determine the row/column address of the stylus from the embedded wire mesh • It has high resolution
Image Scanner • Application – Desktop Publishing • It can produce a digital image of a document for input and storage in a computer • The technology is very similar to the photocopier
Different types of Scanners • Hand Scanner : small scanner that can be passed over the document surface by hand. 2. Flat bed: like a photocopier, on which the input document is placed and scanned
No artistic performance is required High quality graphics require large amounts of disc space. Scanned handwriting or text is treated as one whole picture unless u have the specific software. Advantages and Disadvantages
Digital Camera • High resolution pictures can be taken and stored in specially designed storage in the camera • The camera can be connected to the computer and pictures can be downloaded • Since pictures are digital they can be edited, enhanced and printed
Easy image capture Pictures can be send through telephone lines Still relatively costly Advantages and Disadvantages
Bar Code Reader. • Set of bars and spaces of different width. • They are used to identify the product purchased. • They are used in: • Libraries • Luggage routing • Stocktaking, etc.. • Consists of light sensitive and a light emitting diode. • Nowadays almost all products are give a UPC (universal product code) • Written in 2 forms: human readable and barcode.
Optical Mark Reader (OMR) • Allows direct transfer of data from source document to computer. • Information obtained by marking with a pencil. • It can detect the presence or absence of a mark by shining a light and measure the amount of light reflected. • Used for : • Questioners • Tests • Software notices if there are more then one marked boxes.
Magnetic Ink Character Reader (MICR) • Reads only those numbers written in magnetic ink. • It is really accurate and sensitive. • It is practically tamperproof. • Found in almost every shop. • They are used in: • Banks and they are the biggest users. • Passport control. • Significant important documents. • Shops to check if money is false.
Advantages and Disadvantages. • MICR is difficult to forge • Documents can still be read when folded, written etc.. • MICR readers and encoders are very expensive. • The system can only accept a few different characters.
Magnetic ink. Magnetic ink character reader.
Optical Character Reader (OCR). • It recognizes characters from their shape. • Scanners are frequently used for optical recognition. • Some can read hand-printed characters (neatly written), typed or printed fonts. • How it works: • Light is reflected from paper and from ink.
Advantages and Disadvantages. • Data can be read and checked by people. • Can be programmed to read text and neat handwriting. • Documents can be inputted in the computer without the need of re-typing them. • Regularly fail to recognize characters. • Certain words can be easily mistaken for others.
Pen Computing. • Utilizes an electronic pen (called a stylus) rather than a keyboard for input. • Some recognize your handwriting and transform it into typed text. • Some need to be trained first in order to recognize your handwriting. • The most sophisticated do not need any training. • They are hand held. • Too small for a full size keyboard.
Web Cam • Can be used as a Video Conference System, a Home Network System or for Real time Webcam & Web Casting! • It is a camera that is in some way connected to the World Wide Web, or Internet. • Can take many different forms and flavors. • One of the most common types of webcams are personal cameras that are connected to a home PC, which with the help of some software allow the user to share a moving image of themselves with others.
Speech Recognition Human speech is recorded and coded into a sequence of electrical signals
No types or data is necessary The system can be done remotely by telephone, by handicaps and by people whose hands are busy Current speech recognition does not give good results Relatively few words can be recognized and the error rates are high The system is not suitable for noise places Advantages and Disadvantages
Signature Pad • Offers a fully integrated signature capture option that allows users to capture signatures and store them electronically. • There are those which are portable and those which are not. • There are those which are wireless. • There are different types of signature pads and the more they go the more they evolve. • Customer information, service applications and teller-based transactions which are recorded electronically.
Palm Reader • Mostly used for security and privacy, this small device can read your palm. • You put your hand in front of it and it scan your fingerprints • More evolved palm readers scan vein structures in the user’s hand without touching the device. • The device uses infrared light to scan the palm. • Data about your hand layout has to be stored on a computer in order to identify if you have access or not.
