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I.T. for Management Chapter 3

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: http://bit.ly/ZEcPAc

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Page 1: Input / Output Devices

• I.T. for Management

Chapter 3

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Input/Output Devices

KeyboardThe keyboard is much like the QWERTYtypewriter keypadA computer keyboard contains an Arrayof switches, each of which sends the PC a unique signal when pressed The keyboard has a keyboard buffer memory where it stores

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KeyboardTypes of keysAlphanumericFunction keysCurser & screen controlGeneral control

…….Cont

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KeyboardMerits:

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 ex.to connect internet or launch browser etc.Demerits: A keyboard is relatively slow input device.A keyboard can strain eyes & hands

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MouseThe mouse is a device which is used to translate the motion of your hand into the signals that the computer can useClassification is based on types of 3 keys Either2 , 3 or wheel typeBased on port it is connected Serial USBBased on technology Mechanical,optical

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MouseThe mouse is a device which is used to translate

the motion of your hand into the signals that the computer can useA 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

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Inside Mouse (back)Two sensors on each wheel allow the direction to be detected

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Inside mouse(front)

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Optical MouseA typical optical encoding disk: This

disk has 36 holes around its outer edge.

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Tracker ballA Tracker ball is a round ball which when rotated detects the motion and converts it into a relative shift of the cursor on the screenTracker ball is easier movements,no need to move entire handLess desk space required

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MonitorsA Monitors refers to an output device used to render visual information Types of monitors are :Gray scale,Color,Analog & DigitalFlat panel display

………….. Cont

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MonitorsDisplay Technologies used– Cathode Ray Technology– Liquid Crystal Displays– Plasma displays– Thin film Transistors

……….. Cont

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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

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Monitors

The 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

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Monitors

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Input/Output Devices

ScannersThe basic principle of a Scannersis to analyze an image and process it in same wayThe image Capture will allow you to save information to a file on your computer.

………. Cont

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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.

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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

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ScannersTypes 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

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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

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Input/Output Devices

ScannersWhat to look for:1. Scanners vary in resolution &

sharpness2. Most of the scanners have a

hardware resolution of atleast 300*300 dots per inches

3. Physical dimension4. Paper path specifically in case of

sheet fed

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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.

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How Scanner works• A lamp is used to illuminate the document.The lamp in newer scanners is either a cold cathode fluorescent lamp (CCFL) or a xenon lamp, while older scanners may have a standard fluorescent lamp.

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How Scanner worksThe 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.

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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.

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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.

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Touch screenA 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 fingerThere are three basic systems that are used to recognize a person's touch:

ResistiveCapacitive Surface acoustic wave

……………. Cont

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Touch screenThe 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.

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Touch screenOnce the coordinates are known, a special driver translates the touch into something that the operating systemcan understand, much as a computer mouse driver translates a mouse's 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.

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Touch screenWhen 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.

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Touch screenOne advantage that the capacitive system has over the resistive system is that it transmits almost 90 percent of the light from the monitorWhereas the resistive system only transmits about 75 percent. This gives the capacitive system a much clearer picture than the resistive system

…………. Cont.

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Touch screenOn 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 monitor's 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.

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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 doesn't 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.

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Types of Touch screenVisi –TouchDust ProofKiosk touchBevel touchState touchAntiglare

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Touch screenTechnologies used

– Analogue resistive– Capacitive– Scanning Infrared– Surface Acoustic Wave

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PrinterTypes of Printer

ImpactDot matrixDaisy WheelLine

Non ImpactInkjetThermalLaserDye SublimationSolid ink

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Dot matrix Printer

A type of printer that produces characters and illustrations by striking pins against an ink ribbon to print closely spaced dots in the appropriate shape.

Dot-matrix printers are relatively expensive and do not produce high-quality output.

However, they can print to multi-page forms (that is, carbon copies), something laser and ink-jet printers cannot do. …………Cont

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Input/Output Devices Dot-matrix Printer

Dot-matrix printers vary in two important characteristics: · speed: Given in characters per second (cps), the speed can vary from about 50 to over 500 cps. Most dot-matrix printers offer different speeds depending on the quality of print desired. · print quality: Determined by the number of pins (the mechanisms that print the dots), it can vary from 9 to 24.The best dot-matrix printers (24 pins) can produce near letter-quality type, although you can still see a difference if you look closely. In addition to these characteristics, you should also consider the noise factor. Compared to laser and ink-jet printers, dot-matrix printers are notorious for making a racket.

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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.

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Input/Output Devices Dot-matrix Printer

Digital then broadened the basic LA36 line onto a 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

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Input/Output Devices Daisywheel Printer

A daisy wheel printer is a type of computer printer that produces high-quality type, and was often referred to during the 1980s as a letter-quality printer(in contrast to high-quality dot matrix printers, capable of so-called near letter quality (NLQ) output). There were also, and still are, daisy wheel typewriters, based on the same principle.The system used a small wheel with each letter printed on it in raised metal or plastic. The printer turns the wheel to line up the proper letter under a single pawl which then strikes the back of the letter and drives it into the paper.

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Input/Output Devices Daisywheel Printer

In many respects the daisy wheel is similar to a standard typewriter in the way it forms its letters on the page, differing only in the details of the mechanism (daisy wheel 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-matrix's ability to print graphics and different fonts. With the introduction of high-quality laser printers and inkjet printers in the later 1980s, daisy wheel systems quickly disappeared but for the small remaining typewritermarket

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Input/Output Devices Laser Printer

The term laser printer is a bit more mysterious -- how can a laser beam, a highly focused beam of light, write letters and draw pictures on paper? In this article, we'll unravel the mystery behind the laser printer, tracing a page's path from the characters on your computer screen to printed letters on paper. As it turns out, the laser printing process is based on some very basic scientific principles applied in an exceptionally innovative way.

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Input/Output Devices Laser Printer

The Basics: Static ElectricityThe primary principle at work in a laser printer is static electricity, the same energy that makes clothes in the dryerstick together or a lightning bolt travel from a thundercloud to the 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

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Input/Output Devices Laser Printer

A laser printer uses this phenomenon as a sort of "temporary glue." The core component of this system is the photoreceptor, typically a revolving drum or cylinder. This drum assembly is made out of highly photoconductivematerial that is discharged by light photons.

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Input/Output Devices Laser Printer

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Input/Output Devices Inkjet Printer

An inkjet printers simply spray ink in a series of dots to form characters.

Print head assembly Print head - The core of an inkjet printer, the print head contains a series of nozzles that are used to spray drops of ink.

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Input/Output Devices Inkjet Printer

Stepper motors like this one control the movement of most parts of an inkjet printer.

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Input/Output Devices Inkjet Printer

Belt - A belt is used to attach the print head assembly to the stepper motor.

Stabilizer bar -The print head assembly uses a stabilizer bar to ensure that movement is precise and controlled.

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Input/Output Devices Inkjet Printer

Paper feed assembly

Paper tray/feeder - Most inkjet printers have a tray that you load the paper into. Some printers dispense with the standard tray for a feeder instead.

he feeder typically snaps open at an angle on the back of the printer, allowing you to place paper in it. Feeders generally do not hold as much paper as a traditional paper tray.

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Input/Output Devices Inkjet Printer

§ Rollers - A set of rollers pull the paper in from the tray or feeder and advance the paper when the print head assembly is ready for another pass.

The rollers move the paper through the printer

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Input/Output Devices Inkjet Printer

Paper feed stepper motor - This stepper motor powers the rollers to move the paper in the exact increment needed to ensure a continuous image is printed.

Power supply - While earlier printers often had an external transformer, most printers sold today use a standard power supply that is incorporated into the printer itself.

Control circuitry - A small but sophisticated amount of circuitry is built into the printer to control all the mechanical aspects of operation, as well as decode the information sent to the printer from the computer

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Input/Output Devices Inkjet Printer

Paper feed stepper motor - This stepper motor powers the rollers to move the paper in the exact increment needed to ensure a continuous image is printed.

Power supply - While earlier printers often had an external transformer, most printers sold today use a standard power supply that is incorporated into the printer itself.

Control circuitry - A small but sophisticated amount of circuitry is built into the printer to control all the mechanical aspects of operation, as well as decode the information sent to the printer from the computer

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Input/Output Devices Inkjet Printer

The mechanical operation of the printer is controlled by a small circuit board containing a microprocessor and memory.

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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

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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 heatedThese are normally used for high quality short life printingIt fades after 6 months or 1year

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Input/Output Devices Web Camera

A simple Web cam consists of a digital camera attached to a computer

Typically through the USB port.The camera part of the Web cam setup

is just a digital camera -- there's really nothing special going on there. The "Web cam" nature of the camera comes with the software

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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 you're interested in using your Web cam for streaming video, you'll 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.

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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 & musicPalm PDAsMost 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.

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Input/Output Devices PDA’s

nown for their ease of use, Palm OS PDAs have:

A vast library of third-party applications (more than 20,000) that you can add to the system (most devices come bundled with e-mail, productivity, and multimedia software)

An updated version of the Graffiti handwriting-recognition application

Synchronization with both Windows and Macintosh computers using the Palm Desktop

Smaller displays than Pocket PCs to accommodate a dedicated Graffiti area on the

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Input/Output Devices PDA’s

A cellular service provider to handle phone service (As with cell phones, you typically purchase a cellular plan and smart phone from the service provider.)

Internet access through cellular data networks

Various combinations of cell phone and PDA features, depending on the device (for example, not all smart phones offer handwriting-recognition capabilities)

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Bar Code

You can see that the UPC symbol printed on a package has two parts: • The machine-readable bar code • he human-readable 12-digit UPC number BYG Publishing's manufacturer identification number 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 for assigning item numbers to products, making sure the same code is not used on more than one product, retiring codes as products are removed from the product line, etc.

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Bar Code

In general, every item the manufacturer sells, as well as every size package and every repackaging of the item, needs a different item code. So a 12-ounce can of Coke needs a different item number than a 16-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 UPC coordinator to keep all of these numbers straight! The last digit of the UPC code is called a check digit.

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• I.T. for Management

End of Chapter 3