Input / Output Devices


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Secondary storage devices are required mainly because primary storage devices are volatile and information is lost the moment power is switched off. Floppy Disks and Drive, Hard Disks, CD/DVD drive, Pen drive and magnetic tapes are some of the secondary storage devices.

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Input / Output Devices

  1. 1. • I.T. for Management Chapter 3
  2. 2. Input/Output Devices Keyboard The keyboard is much like the QWERTY typewriter keypad A computer keyboard contains an Array of switches, each of which sends the PC a unique signal when pressed The keyboard has a keyboard buffer memory where it stores
  3. 3. Input/Output Devices Keyboard Types of keys Alphanumeric Function keys Curser & screen control General control …….Cont
  4. 4. Input/Output Devices Keyboard Merits: keyboard is very familiar means of inputs of data.It has substantial amount of original text It is mail tool for data entry keyboard offers special keys for connect internet or launch browser etc. Demerits: A keyboard is relatively slow input device.A keyboard can strain eyes & hands
  5. 5. Input/Output Devices Mouse The mouse is a device which is used to translate the motion of your hand into the signals that the computer can use Classification is based on types of 3 keys Either2 , 3 or wheel type Based on port it is connected Serial USB Based on technology Mechanical,optical
  6. 6. Input/Output Devices Mouse The mouse is a device which is used to translate the motion of your hand into the signals that the computer can use A Tracker ball is a round ball which when rotated detects the motion and converts it into a relative shift of the cursor on the screen ……………Cont
  7. 7. Input/Output Devices Inside Mouse (back) Two sensors on each wheel allow the direction to be detected
  8. 8. Input/Output Devices Inside mouse(front)
  9. 9. Input/Output Devices Optical Mouse A typical optical encoding disk: This disk has 36 holes around its outer edge.
  10. 10. Input/Output Devices Tracker ball A Tracker ball is a round ball which when rotated detects the motion and converts it into a relative shift of the cursor on the screen Tracker ball is easier movements,no need to move entire hand Less desk space required
  11. 11. Input/Output Devices Monitors A Monitors refers to an output device used to render visual information Types of monitors are : Gray scale, Color, Analog & Digital Flat panel display ………….. Cont
  12. 12. Input/Output Devices Monitors Display Technologies used – Cathode Ray Technology – Liquid Crystal Displays – Plasma displays – Thin film Transistors ……….. Cont
  13. 13. Input/Output Devices MonitorsA CRT monitor contains millions of tiny red, green, and blue phosphor dots that glow when struck by an electron beam that travels across the screen to create a visible image. The illustration below shows how this works inside a CRT. ……….cont
  14. 14. Input/Output Devices MonitorsThe terms anode and cathode are used in electronics as synonyms for positive and negative terminals. For example, you could refer to the positive terminal of a battery as the anode and the negative terminal as the cathode. ……..cont
  15. 15. Input/Output Devices Monitors
  16. 16. Input/Output Devices Scanners The basic principle of a Scanners is to analyze an image and process it in same way The image Capture will allow you to save information to a file on your computer. ………. Cont
  17. 17. Input/Output Devices Scanners Types of Scanners – Flatbed :Flatbed scanners, also called desktop scanners, are the most versatile and commonly used scanners. In fact, this article will focus on the technology as it relates to flatbed scanners – Sheet bed Sheet-fed scanners are similar to flatbed scanners except the document is moved and the scan head is immobile. A sheet-fed scanner looks a lot like a small portable printer.
  18. 18. Input/Output Devices Scanners Types of Scanners Handheld scanners – use the same basic technology as a flatbed scanner, but rely on the user to move them instead of a motorized belt. This type of scanner typically does not provide good image quality. However, it can be useful for quickly capturing text. – ………….Cont
  19. 19. Input/Output Devices Scanners Types of Scanners Drum scanners are used by the publishing industry to capture incredibly detailed images. They use a technology called a photo multiplier tube (PMT). In PMT, the document to be scanned is mounted on a glass cylinder. At the center of the cylinder is a sensor that splits light bounced from the document into three beams. Each beam is sent through a color filter into a photo multiplier tube where the light is changed into an electrical signal
  20. 20. Input/Output Devices ScannersParts of a typical flatbed scanner include:• Charge-coupled device (CCD) array• Mirror Scan head• Glass plate Lamp ,Lens ,Cover• Filters• Stepper motor Stabilizer bar Belt• Power supply Interface port(s)• Control circuitry
  21. 21. Input/Output Devices Scanners What to look for: 1. Scanners vary in resolution & sharpness 2. Most of the scanners have a hardware resolution of atleast 300*300 dots per inches 3. Physical dimension 4. Paper path specifically in case of sheet fed
  22. 22. Input/Output Devices How Scanner works – 1. The document is placed on the glass plate and the cover is closed. The inside of the cover in most scanners is flat white, although a few are black. – 2. The cover provides a uniform background that the scanner software can use as a reference point for determining the size of the document being scanned. – 3. Most flatbed scanners allow the cover to be removed for scanning a bulky object, such as a page in a thick book.
  23. 23. Input/Output Devices How Scanner works• A lamp is used to illuminate the document. The lamp in newer scanners is either a cold cathodefluorescent lamp (CCFL) or a xenon lamp, while olderscanners may have a standard fluorescent lamp.
  24. 24. Input/Output Devices How Scanner works The entire mechanism (mirrors, lens, filter and CCD array) make up the scan head. The scan head is moved slowly across the document by a belt that is attached to a stepper motor. The scan head is attached to a stabilizer bar to ensure that there is no wobble or deviation in the pass. Pass means that the scan head has completed a single complete scan of the document.
  25. 25. Input/Output Devices How Scanner works • The image of the document is reflected by an angled mirror to another mirror. In some scanners, there are only two mirrors while others use a three mirror approach. Each mirror is slightly curved to focus the image it reflects onto a smaller surface. • The last mirror reflects the image onto a lens. The lens focuses the image through a filter on the CCD array.
  26. 26. Input/Output Devices How Scanner worksThe filter and lens arrangement vary based on the scanner. Some scanners use a three pass scanning method. Each pass uses a different color filter (red, green or blue) between the lens and CCD array.After the three passes are completed, the scanner software assembles the three filtered images into a single full-color image.
  27. 27. Input/Output Devices Touch screen A Touch screen is an assembly that is mounted in front of a video display It is activated by touching the selected area on the display that indicates the desire function,with stylus or finger There are three basic systems that are used to recognize a persons touch: Resistive Capacitive Surface acoustic wave ……………. Cont
  28. 28. Input/Output Devices Touch screen The resistive system consists of a normal glass panel that is covered with a conductive and a resistive metallic layer. These two layers are held apart by spacers, and a scratch- resistant layer is placed on top of the whole setup. An electrical current runs through the two layers while the monitor is operational. When a user touches the screen, the two layers make contact in that exact spot. The change in the electrical field is noted and the coordinates of the point of contact are calculated by the computer. ………………… Cont.
  29. 29. Input/Output Devices Touch screen Once the coordinates are known, a special driver translates the touch into something that the operating system can understand, much as a computer mouse driver translates a mouses movements into a click or a drag. In the capacitive system, a layer that stores electrical charge is placed on the glass panel of the monitor. …………. Cont.
  30. 30. Input/Output Devices Touch screen When a user touches the monitor with his or her finger, some of the charge is transferred to the user, so the charge on the capacitive layer decreases. This decrease is measured in circuits located at each corner of the monitor. The computer calculates, from the relative differences in charge at each corner, exactly where the touch event took place and then relays that information to the touch screen driver software. …………. Cont.
  31. 31. Input/Output Devices Touch screen One advantage that the capacitive system has over the resistive system is that it transmits almost 90 percent of the light from the monitor Whereas the resistive system only transmits about 75 percent. This gives the capacitive system a much clearer picture than the resistive system …………. Cont.
  32. 32. Input/Output Devices Touch screen On the monitor of a surface acoustic wave system, two transducers (one receiving and one sending) are placed along the x and y axes of the monitors glass plate. Also placed on the glass are reflectors -- they reflect an electrical signal sent from one transducer to the other. The receiving transducer is able to tell if the wave has been disturbed by a touch event at any instant, and can locate it accordingly. …………. Cont.
  33. 33. Input/Output Devices Touch screen The wave setup has no metallic layers on the screen, allowing for 100-percent light throughput and perfect image clarity. This makes the surface acoustic wave system best for displaying detailed graphics (both other systems have significant degradation in clarity). Another area in which the systems differ is in which stimuli will register as a touch event. A resistive system registers a touch as long as the two layers make contact, which means that it doesnt matter if you touch it with your finger or a rubber ball. A capacitive system, on the other hand, must have a conductive input, usually your finger, in order to register a touch. …………. Cont.
  34. 34. Input/Output Devices Types of Touch screen Visi –Touch Dust Proof Kiosk touch Bevel touch State touch Antiglare
  35. 35. Input/Output Devices Touch screen Technologies used – Analogue resistive – Capacitive – Scanning Infrared – Surface Acoustic Wave
  36. 36. Input/Output Devices PrinterTypes of Printer Impact Dot matrix Daisy Wheel Line Non Impact Inkjet Thermal Laser Dye Sublimation Solid ink
  37. 37. Input/Output Devices Dot matrix PrinterA type of printer that produces characters andillustrations by striking pins against an ink ribbon to printclosely spaced dots in the appropriate shape.Dot-matrix printers are relatively expensive and do notproduce high-quality output.However, they can print to multi-page forms (that is,carbon copies), something laser and ink-jet printerscannot do. …………Cont
  38. 38. Input/Output Devices Dot-matrix PrinterDot-matrix printers vary in two important characteristics:· speed: Given in characters per second (cps), the speed canvary from about 50 to over 500 cps. Most dot-matrix printersoffer different speeds depending on the quality of printdesired.· print quality: Determined by the number of pins (themechanisms that print the dots), it can vary from 9 to 24.The best dot-matrix printers (24 pins) can produce nearletter-quality type, although you can still see a difference ifyou look closely.In addition to these characteristics, you should also considerthe noise factor. Compared to laser and ink-jet printers, dot-matrix printers are notorious for making a racket.
  39. 39. Input/Output Devices Dot-matrix Printer A dot matrix printer or impact matrix printer refers to a type of computer printer with a print head that runs back and forth on the page and prints by impact, striking an ink-soaked cloth ribbon against the paper, much like a typewriter. Unlike a typewriter or daisy wheel printer, letters are drawn out of a dot matrix, and thus, varied fonts and arbitrary graphics can be produced. Because the printing involves mechanical pressure, these printers can create carbon copies and carbonless copies.
  40. 40. Input/Output Devices Dot-matrix PrinterDigital then broadened the basic LA36 line ontoa wide variety of dot matrix printers including: •LA180 -- 180 c/s line printer •LS120 -- 120 c/s terminal •LA120 -- 180 c/s advanced terminal •LA34 -- Cost-reduced terminal •LA38 -- An LA34 with more features •LA12 -- A portable terminal
  41. 41. Input/Output Devices Daisywheel PrinterA daisy wheel printer is a type ofcomputer printer that produceshigh-quality type, and was often referred to during the1980s as a letter-quality printer(in contrast to high-quality dot matrix printers, capableof so-called near letter quality (NLQ) output).There were also, and still are, daisy wheeltypewriters, based on the same principle.The system used a small wheel with each letter printedon it in raised metal or plastic. The printer turns thewheel to line up the proper letter under a single pawlwhich then strikes the back of the letter and drives itinto the paper.
  42. 42. Input/Output Devices Daisywheel PrinterIn many respects the daisy wheel is similar to a standardtypewriter in the way it forms its letters on the page,differing only in the details of the mechanism (daisywheel vs. typebars or the typeball used on IBM Selectrictypewriters).Daisy wheel printers were fairly common in the 1980s,but were always less popular than dot matrix printers(ballistic wire printers) due to higher cost and the dot-matrixs ability to print graphics and different fonts. Withthe introduction of high-quality laser printers and inkjetprinters in the later 1980s, daisy wheel systems quicklydisappeared but for the small remaining typewritermarket
  43. 43. Input/Output Devices Laser PrinterThe term laser printer is a bit more mysterious -- how can alaser beam, a highly focused beam of light, write letters anddraw pictures on paper?In this article, well unravel the mystery behind the laserprinter, tracing a pages path from the characters on yourcomputer screen to printed letters on paper. As it turns out,the laser printing process is based on some very basicscientific principles applied in an exceptionally innovativeway.
  44. 44. Input/Output Devices Laser PrinterThe Basics: Static ElectricityThe primary principle at work in a laser printer is staticelectricity, the same energy that makes clothes in the dryerstick together or a lightning bolt travel from a thundercloud tothe ground.Static electricity is simply an electrical charge built up on aninsulated object, such as a balloon or your body.Since oppositely charged atoms are attracted to each other,objects with opposite static electricity fields cling together. ….. Cont
  45. 45. Input/Output Devices Laser PrinterA laser printer uses thisphenomenon as a sort of"temporary glue." The corecomponent of this system is thephotoreceptor, typically arevolving drum or cylinder.This drum assembly is madeout of highly photoconductivematerial that is discharged bylight photons.
  46. 46. Input/Output Devices Laser Printer
  47. 47. Input/Output Devices Inkjet PrinterAn inkjet printers simply spray ink in a series of dotsto form characters. Print head assembly Print head - The coreof an inkjet printer, the print head contains aseries of nozzles that are used to spray drops ofink.
  48. 48. Input/Output Devices Inkjet PrinterStepper motors like this onecontrol the movement ofmost parts of an inkjetprinter.
  49. 49. Input/Output Devices Inkjet Printer Belt - A belt isused to attach the print headassembly to the steppermotor. Stabilizer bar -The print head assembly usesa stabilizer bar to ensure thatmovement is precise andcontrolled.
  50. 50. Input/Output Devices Inkjet Printer Paper feed assembly Paper tray/feeder - Most inkjet printers have a traythat you load the paper into. Some printers dispense withthe standard tray for a feeder instead.he feeder typically snaps open at an angle on the back ofthe printer, allowing you to place paper in it. Feedersgenerally do not hold as much paper as a traditional papertray.
  51. 51. Input/Output Devices Inkjet Printer § Rollers - A set of rollers pull the paper infrom the tray or feeder and advance the paper when theprint head assembly is ready for another pass. The rollers move the paper through the printer
  52. 52. Input/Output Devices Inkjet Printer Paper feed stepper motor - This stepper motorpowers the rollers to move the paper in the exact incrementneeded to ensure a continuous image is printed. Power supply - While earlier printersoften had an external transformer, most printers sold todayuse a standard power supply that is incorporated into theprinter itself. Control circuitry - A small butsophisticated amount of circuitry is built into the printer tocontrol all the mechanical aspects of operation, as well asdecode the information sent to the printer from thecomputer
  53. 53. Input/Output Devices Inkjet Printer Paper feed stepper motor - This stepper motorpowers the rollers to move the paper in the exact incrementneeded to ensure a continuous image is printed. Power supply - While earlier printersoften had an external transformer, most printers sold todayuse a standard power supply that is incorporated into theprinter itself. Control circuitry - A small butsophisticated amount of circuitry is built into the printer tocontrol all the mechanical aspects of operation, as well asdecode the information sent to the printer from thecomputer
  54. 54. Input/Output Devices Inkjet PrinterThe mechanical operation of the printer is controlled by asmall circuit board containing a microprocessor andmemory.
  55. 55. Input/Output Devices Inkjet Printer Interface port(s) - The parallel port is still used by many printers, but most newer printers use the USB port. A few printers connect using a serial port or small computer system interface (SCSI) port.While USB taking over, many printers still use a parallel port
  56. 56. Input/Output Devices Thermal Printer In the Thermal printers a film coated synthetic paper and miniature heat element embedded rollers are used. The film turns black when it gets heated These are normally used for high quality short life printing It fades after 6 months or 1year
  57. 57. Input/Output Devices Web Camera A simple Web cam consists of a digital camera attached to a computerTypically through the USB port.The camera part of the Web cam setup is just a digital camera -- theres really nothing special going on there. The "Web cam" nature of the camera comes with the software
  58. 58. Input/Output Devices Web Camera Web cam software "grabs a frame" from the digital camera at a preset interval (for example, the software might grab a still image from the camera once every 30 seconds) and transfers it to another location for viewing. If youre interested in using your Web cam for streaming video, youll want a Web cam system with a high frame rate. Frame rate indicates the number of pictures the software can grab and transfer in one second. For streaming video, you need a minimum rate of at least 15 frames per second (fps), and 30 fps is ideal.
  59. 59. Input/Output Devices PDA’s Personal Digital Assistance (PDA) is a tiny,fully functional computer that you can hold in one hand. A PDA can hold your down loaded emails & music Palm PDAs Most Palm devices are made by palm One, which offers the Zire and Tungsten product lines. The company formed in 2003 when Palm Computing acquired Handspring, Inc. Sony, which produced the Palm-based CLIE, stopped producing PDAs in 2005.
  60. 60. Input/Output Devices PDA’snown for their ease of use, Palm OS PDAs have: A vast library of third-partyapplications (more than 20,000) that you can addto the system (most devices come bundled withe-mail, productivity, and multimedia software) An updated version of the Graffitihandwriting-recognition application Synchronization with both Windowsand Macintosh computers using the PalmDesktop Smaller displays than Pocket PCsto accommodate a dedicated Graffiti area on the
  61. 61. Input/Output Devices PDA’s A cellular service provider to handle phoneservice (As with cell phones, you typically purchasea cellular plan and smart phone from the serviceprovider.) Internet access through cellular data networks Various combinations of cell phone and PDAfeatures, depending on the device (for example, notall smart phones offer handwriting-recognitioncapabilities)
  62. 62. Bar CodeYou can see that the UPC symbol printed on apackage has two parts:• The machine-readable bar code• he human-readable 12-digit UPC numberBYG Publishings manufacturer identificationnumber is the first six digits of the UPC number --639382. The next five digits -- 00039 -- are the itemnumber. A person employed by the manufacturer,called the UPC coordinator, is responsible forassigning item numbers to products, making surethe same code is not used on more than oneproduct, retiring codes as products are removedfrom the product line, etc.
  63. 63. Bar Code In general, every item the manufacturersells, as well as every size package andevery repackaging of the item, needs adifferent item code. So a 12-ounce can ofCoke needs a different item number than a16-ounce bottle of Coke, as does a 6-pack of12-ounce cans, a 12-pack, a 24-can case,and so on. It is the job of the UPCcoordinator to keep all of these numbersstraight!The last digit of the UPC code is called acheck digit.
  64. 64. • I.T. for Management End of Chapter 3
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