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. For more such innovative content on management studies, join WeSchool PGDM-DLP Program:


<ul><li> 1. I.T. for Management Chapter 3</li></ul><p> 2. Input/Output DevicesKeyboardThe keyboard is much like the QWERTY typewriter keypadA 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. Input/Output Devices Keyboard Types of keys Alphanumeric Function keys Curser &amp; screen control General control .Cont 4. Input/Output DevicesKeyboardMerits: 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 &amp; hands 5. Input/Output DevicesMouseThe 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. Input/Output Devices MouseThe 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. Input/Output Devices Inside Mouse (back) Two sensors on each wheel allow the direction to be detected 8. Input/Output Devices Inside mouse(front) 9. Input/Output DevicesOptical Mouse A typical optical encoding disk: Thisdisk has 36 holes around its outer edge. 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. Input/Output Devices Monitors A Monitors refers to an output device used to render visual information Types of monitors are : Gray scale, Color, Analog &amp; Digital Flat panel display.. Cont 12. Input/Output Devices Monitors Display Technologies used Cathode Ray Technology Liquid Crystal Displays Plasma displays Thin film Transistors.. Cont 13. Input/Output DevicesMonitorsA CRT monitor contains millions of tiny red,green, and blue phosphor dots that glowwhen struck by an electron beam thattravels across the screen to create avisible image. The illustration belowshows how this works inside a CRT..cont 14. Input/Output Devices MonitorsThe terms anode and cathode are used inelectronics as synonyms for positive andnegative terminals. For example, youcould refer to the positive terminal of abattery as the anode and the negativeterminal as the cathode. ..cont 15. Input/Output Devices Monitors 16. Input/Output DevicesScannersThe basic principle of a Scannersis to analyze an image and processit in same wayThe image Capture will allow youto save information to a file onyour computer.. Cont 17. Input/Output Devices ScannersTypes 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. Input/Output Devices ScannersTypes 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. Input/Output Devices ScannersTypes of Scanners Drum scanners are used by the publishingindustry to capture incredibly detailedimages. They use a technology called aphoto multiplier tube (PMT). In PMT, thedocument to be scanned is mounted on aglass cylinder. At the center of the cylinderis a sensor that splits light bounced fromthe document into three beams. Each beamis sent through a color filter into a photomultiplier tube where the light is changedinto an electrical signal 20. Input/Output Devices ScannersParts of a typical flatbed scanner include: Charge-coupled device (CCD) array MirrorScan head Glass plate Lamp ,Lens ,Cover Filters Stepper motor Stabilizer bar Belt Power supply Interface port(s) Control circuitry 21. Input/Output Devices Scanners What to look for: 1. Scanners vary in resolution &amp;sharpness 2. Most of the scanners have ahardware resolution of atleast300*300 dots per inches 3. Physical dimension 4. Paper path specifically in case ofsheet fed 22. Input/Output DevicesHow 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. 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. Input/Output Devices How Scanner worksThe entire mechanism (mirrors, lens, filter and CCD array) make up the scanhead. The scan head is moved slowly across the document by a belt that isattached to a stepper motor.The scan head is attached to a stabilizerbar to ensure that there is no wobble or deviation in the pass. Pass means thatthe scan head has completed a singlecomplete scan of the document. 25. Input/Output DevicesHow Scanner works The image of the document is reflectedby an angled mirror to another mirror. Insome scanners, there are only two mirrors while others use a three mirrorapproach. Each mirror is slightly curved to focus the image it reflects onto asmaller surface. The last mirror reflects the image ontoa lens. The lens focuses the image through a filter on the CCD array. 26. Input/Output DevicesHow Scanner worksThe filter and lens arrangement varybased on the scanner. Some scannersuse a three pass scanning method.Each pass uses a different color filter(red, green or blue) between the lensand CCD array.After the three passes are completed, thescanner software assembles the threefiltered images into a single full-colorimage. 27. Input/Output Devices Touch screen A Touch screen is an assembly that ismounted in front of a video displayIt is activated by touching the selected area onthe display that indicates the desirefunction,with stylus or fingerThere are three basic systems that are used torecognize a persons touch: Resistive Capacitive Surface acoustic wave . Cont 28. Input/Output Devices Touch screen The resistive system consists of a normalglass panel that is covered with a conductiveand a resistive metallic layer. These two layersare held apart by spacers, and a scratch-resistant layer is placed on top of the wholesetup.An electrical current runs through the twolayers while the monitor is operational. When auser touches the screen, the two layers makecontact in that exact spot. The change in theelectrical field is noted and the coordinates ofthe point of contact are calculated by thecomputer. Cont. 29. Input/Output DevicesTouch screenOnce the coordinates are known, aspecial driver translates the touch intosomething that the operating systemcan understand, much as a computermouse driver translates a mousesmovements into a click or a drag.In the capacitive system, a layer thatstores electrical charge is placed on theglass panel of the monitor.. Cont. 30. Input/Output Devices Touch screenWhen a user touches the monitor with his orher finger, some of the charge is transferred tothe user, so the charge on the capacitive layerdecreases. This decrease is measured in circuits locatedat each corner of the monitor. The computercalculates, from the relative differences incharge at each corner, exactly where the touchevent took place and then relays thatinformation to the touch screen driversoftware.. Cont. 31. Input/Output DevicesTouch screenOne advantage that the capacitivesystem has over the resistive system isthat it transmits almost 90 percent ofthe light from the monitorWhereas the resistive system onlytransmits about 75 percent. This givesthe capacitive system a much clearerpicture than the resistive system. Cont. 32. Input/Output Devices Touch screenOn the monitor of a surface acoustic wavesystem, two transducers (one receiving andone sending) are placed along the x and y axesof the monitors glass plate.Also placed on the glass are reflectors -- theyreflect an electrical signal sent from onetransducer to the other. The receivingtransducer is able to tell if the wave has beendisturbed by a touch event at any instant, andcan locate it accordingly.. Cont. 33. Input/Output DevicesTouch screenThe wave setup has no metallic layers on the screen,allowing for 100-percent light throughput and perfect imageclarity. This makes the surface acoustic wave system bestfor displaying detailed graphics (both other systems havesignificant degradation in clarity).Another area in which the systems differ is in which stimuliwill register as a touch event. A resistive system registers atouch as long as the two layers make contact, which meansthat it doesnt matter if you touch it with your finger or arubber ball. A capacitive system, on the other hand, musthave a conductive input, usually your finger, in order toregister a touch.. Cont. 34. Input/Output Devices Types of Touch screenVisi TouchDust ProofKiosk touchBevel touchState touchAntiglare 35. Input/Output DevicesTouch screenTechnologies used Analogue resistive Capacitive Scanning Infrared Surface Acoustic Wave 36. Input/Output DevicesPrinterTypes of Printer ImpactDot matrixDaisy WheelLineNon ImpactInkjetThermalLaserDye SublimationSolid ink 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. 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. Input/Output DevicesDot-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. 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. 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. 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. 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. Input/Output DevicesLaser 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. Input/Output DevicesLaser 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. Input/Output Devices Laser Printer 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. Input/Output Devices Inkjet...</p>