Input devices


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this presentation contains information about all the major input devices which we see around.

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Input devices

  1. 1. THE FOLLOWING IS A LIST OF THE MOST COMMON INPUT DEVICES WHICH ARE NOWADAYS FOUND IN A COMPUTER SYSTEM: 1ST KEYBOARD 2ND MOUSE 3RD JOY STICK 4TH LIGHT PEN 5TH TRACK BALL 6TH SCANNER 7TH GRAPHIC TABLET(DIGITIZER) 8TH MICROPHONE 9TH MAGNETIC INK CARD READER(MICR) 10TH OPTICAL CHARACTER READER(OCR) 11TH BAR CODE READER 12TH OPTICAL MARK READER input devices...... Input is any data or instructions entered into the memory of a computer. input device is any hardware component that allows a user to enter data and instructions into a computer.
  2. 2. 1st KEYBOARD................/.
  3. 3. Different categories of keys in keyboard:SR. NO. KEYS DISCRIPTION 1. TYPING KEYS These keys include the letter keys (A-Z) and digits keys (0-9) which are generally give same layout as that of typewriters. 2. NUMERIC KEYS I t is used to enter numeric data or cursor movement. Generally, it consists of a set of 17 keys that are laid out in the same configuration used by most adding machine and calculators. 3. FUNCTION KEYS The twelve functions keys are present on the keyboard. These are arranged in a row along the top of the keyboard. Each function key has unique meaning and is used for some specific purpose. 4. CONTROL KEYS These keys provides cursor and screen control. I t includes four directional arrow key. Control keys also include Home, End, Insert, Delet ,page up, page down Control(Ctrl), Alternate(Alt), Escape(Esc). 5. SPECIAL PURPOSE KEYS Keyboard also contains some special purpose keys such as Enter, Shift, Caps Lock, Num Lock, Space bar, Tab, and Print Screen.
  4. 4. Working of keyboard: WORKING OF KEYBOARD....... When any key is pressed in keyboard, the spring blow presses down thus completing the circuit. The tiny chip KEYBORDS CONTROLLER notes which key is being pressed. It sends interrupt request to the also sends a code called scan code to the KEYBOARD BUFFER the system software respond to the interrupt by reading scan code this scan code is
  6. 6. WORKING OF MOUSE: There is a small ball underneath a mouse , the ball moves too. As the ball moves it rubs against two rollers.One roller senses the horizontal movement and other vertical. These rollers together can tell in which direction the user moves the mouse. Each roller is attached to a wheel called ENCODER. This encoder turns with the rollers.As the encoder turns, its metal bridges touches two fixed electrical contact which generates electrical pulses.The movement of mouse tells with which rate the electrical pulse is generated.These signals are send to the computer through mouse cables.These signals are read by software called the MOUSE DRIVER. this software tells your computer how to move mouse pointer so that it matches mouse movement.
  7. 7. 3rd Joystick: ‘Joystick is also a pointing device which is used to move cursor position on a monitor screen. ’
  8. 8. 4th LIGHT PEN: ‘they are pen shaped devices are used to select the screen icons by detecting the light coming from the CRT screen.’
  9. 9. 5th TRACK BALL: A trackball is a stationary pointing device with a ball mechanism on its top.
  10. 10. 6th SCANNER: ‘Ascanner is a light-sensing input device that convertsprinted text and graphicsinto a digital form that can be furtherprocessed by the computer’
  11. 11. TYPES OF SCANNER: 1.flat bed scaner,2.hand held scanner
  12. 12. 2nd hand held scanner:
  13. 13. Working of a scanner: Scanners operate by shining light at the object or document being digitized and directing the reflected light (usually through a series of mirrors and lenses) onto a photosensitive element. In most scanners, the sensing medium is an electronic, light-sensing integrated circuit known as a charged coupled device (CCD). Light- sensitive photosites arrayed along the CCD convert levels of brightness into electronic signals that are then processed into a digital image. Two other technologies, CIS (Contact Image Sensor), and PMT (photomultiplier tube) are found in the low and high ends of the scanner market, respectively. CIS is a newer technology that allows scanners to be smaller and lighter, but sacrifices dynamic range, depth-of-field, and resolution. PMT-based drum scanners produce very high-quality images, but have limited application in library . Another sensing technology, CMOS (Complementary Metal Oxide Semiconductor), appears primarily in low-end, hand-held digital cameras where its low cost, low power consumption and easier component integration permits smaller, less expensive designs.
  14. 14. GRAPHIC TABLET (DIGITIZER): ‘A graphics tablet or digitizer is a computer input device that enables a user to hand-draw images and graphics, similar to the way a person draws images with a pencil and paper’.
  15. 15. MICROPHONE: ‘a microphone is an input device that convert sound into electrical signals’.
  16. 16. MAGNETIC INK CARD READER (MICR): ‘Magnetic ink character recognition (MICR) is a character-recognition technology used mainly by the banking industry to ease the processing and clearance of cheques and other documents’.
  17. 17. OPTICAL CHARACTER RECOGNITION(OCR): ‘Its the mechanical or electronic conversion of scanned images of handwritten, typewritten or printed text into machine-encoded text’.
  18. 18. BAR CODE READER: ‘A barcode reader (or barcode scanner) is an electronic device for reading printed barcodes’.
  19. 19. OPTICAL MARK READER (OMR): ‘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’.
  20. 20. OMR SHEET: