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Home , Computer monitor, Output device

Learning Objectives

• Identify several types of input and output devices and explain their functions. Chapter 5 • Describe the characteristics of the input equipment that most users encounter regularly, Input and Output namely, keyboards and pointing devices.

• Explain what source data automation is and discuss how scanners and other devices can be used to accomplish it.

Learning Objectives, cont’d. Overview • This chapter covers: • List several types of multimedia input devices and discuss their purposes. – Equipment designed primarily for input of • Describe the characteristics of the output equipment that programs and data into the most users encounter regularly, namely, display devices system, or for output, or for both. and printers. • Many other types of input/output devices • Discuss several types of multimedia output equipment. exist, but this chapter covers a good • Explain what a multifunction device is and list some sampling of the most widely used ones. advantages and disadvantages of using such a device.

Input and Output Keyboards

• Keyboards can differ in number of keys, key • Input devices convert data and programs that arrangement, types of special keys, and touch. people can understand into a form – QWERTY – widely used comprehensible to the CPU. – Dvorak – not used often

• Output devices convert the strings of bits used • Function keys enable software packages to be by the computer back into a form that people customized to meet a user's applications needs. can understand. • The numeric keypad makes it easy to enter numbers quickly.

1 Ergonomic Keyboards

• Designed to reduce or minimize repetitive strain injury of wrists – Provide more natural, comfortable position of wrists, arms, and hands

Pointing Devices: Mouse

• The most common – Movement on flat surface causes Common mouse movement of pointer on screen operations are clicking, • Several types , and dragging – Mechanical - small ball on underside rolls as and dropping. mouse is moved – Optical - uses a beam to monitor mouse movement – Cordless - uses either infrared or radio waves, rather than a cord, to connect to computer

Pointing Devices: Electronic Electronic Pens Use Pens • Electronic pen: an alternative to the mouse to • select objects or to write or draw on the screen – User moves or puck • Types: across board – (uses light-sensitive cell in its tip) – Used to create or trace precise – stylus (usually plastic) drawings • Devices that use pen input: • • Pen-based – Signature capture devices –Use pen-like stylus to input data – Graphics tablets –Often used in PDAs or pocket PCs – Pen-based –Use handwritten character recognition

2 Pointing Devices: Touch Screens and

• Touch screens are used: • Trackball – When consumer input is – Variation on mechanical mouse required, as in consumer kiosks – User rolls the ball directly – When other input devices are – Often built into computers impractical • Joystick – Allow user to touch items on – Short lever with handgrip screen – Distance and speed of movement – Position of finger on screen controls pointer’s position determines item to be input – Pressing trigger causes actions to into system take place

Touchpad and Scanners and Related Devices

• • Source data automation involves collecting – Rectangular pressure-sensitive pad data in machine-readable form as soon as – Sliding finger across pad moves pointer it is generated. – Tapping with finger recognized as click • Pointing stick • Source data automation is used to convert – Small pressure-sensitive post source into digital form and mounted in center of keyboard commonly utilizes some type of scanner. – Pushing post in any direction moves pointer

Optical Scanners Scanners • Flatbed scanner • Optical scanner: converts hard-copy images of • – Typically scans one page at a text pages, photographs, and drawings into time digital form – Can be used to scan large bound documents • Common uses: • Sheetfed scanner – Scanners at supermarkets – Motorized rollers feed sheet – imaging - converts paper across scanner head documents to electronic versions • Handheld scanner • Documents stored on disk – Smallest and least accurate • Can be edited or processed by software

3 Scanners (Cont’d) Optical Readers

• Other types of scanners: – Drum scanner (very large and expensive. • Optical marks Documents are mounted on a glass cylinder) – 3D scanner (for multimedia applications) • Optical • Scanner resolution • characters – Measured in dots per inch (dpi) – 72 to 150 dpi for images displayed on screen Optical codes – 300 dpi and higher for printed • Optical codes

Magnetic Ink Character Optical Characters Recognition (MICR) •Optical character recognition (OCR) software required to convert picture (scanned document) into • Uses a machine to read characters characters made of •2nd type of optical character recognition magnetized particles –Wand reader reads characters in special typeface • Banking industry is • Bar Codes predominant user – A series of vertical marks – Characters preprinted on lower left-hand side of check – Represents a unique code – Amount added by MICR • Universal Product Code (UPC) inscriber when check is used as standard in supermarkets cashed

Magnetic Ink Character Recognition Multimedia Input: Digital Reader Cameras • Readers can read the special magnetic • User takes photo that is stored on a chip characters, as well as sort documents by their instead of codes. • Photos can be downloaded to computer (via cable or special card reader) – Use photo-editing software to enhance – Store permanently on CDs or • Photos composed of many of color • Photos stored on removable

4 Multimedia Input: Cameras • Video cameras can be used to either record or send images over the Internet.

• Video input can also be obtained by using special hardware to transfer conventional video images to the computer.

Multimedia Input: Video Input Audio Input Devices • Digital video consists of series • Voice-input systems convert spoken words to digital of still frames data. – Displayed rapidly enough to • User speaks to computer give illusion of motion – Speech recognition devices convert spoken words into binary digits • Web cam used to transmit binary digits • Most are speaker-dependent video over the Internet • – System “learns” user’s voice • Can capture video from • Types of systems analog sources with video – Discrete word systems - user must pause between capture card words – Continuous word systems - user can speak normally

Other Audio Input Devices Display Devices

• Music-input systems can record musical input for • Display devices are the most common type of use with a multimedia presentation or to be . edited or combined with other input • PC displays are commonly called monitors. • MIDI – musical instrument digital interface – device, such as musical keyboard • Can be separate from computer or combined • Telephony is the process of performing telephone-oriented tasks using a computer • The , or insertion point, indicates where editing or typing will appear on the display screen.

5 Size Resolution

• Resolution refers to the sharpness of the screen image. • Most monitors today are about 17 inches screen image. wide, measured diagonally. „ Images are formed by lighting up tiny • The actual viewing area is typically less dots on the screen called pixels. than the stated size.

Resolution (cont’d) Graphics Standards

• Dot pitch – the distance between the pixels • standards specify such characteristics (measures in millimiters). Usual are .26 and .28 as the possible resolutions and number of colors that can (smaller is better) be used.

• Resolution shows how many distinct columns • Video cards connect the monitor to the PC and support a and rows of pixels the screen can display particular graphics standard, such as SVGA. (SVGA allows true color - 24 bit - 16.7 million colors)

• Higher resolution – smaller image – more details • • Video cards typically contain video RAM to support the number of colors and resolutions allowed, as well as to • Can be selected by user help speed up image display.

Color vs. Displays CRT vs. Flat-Panel Displays

• Most color displays are of the RGB type. • Most desktop display devices use CRT • RGB displays combinations of red, blue, and cathode ray tube) technology, similar to green light to form other colors. green light to form other colors. conventional technology. • – 60 to 80 times per second (Hz)

• Flat-panel displays are compact, lightweight, and consume little power. – Ideal for notebook computers – Most use liquid crystal display (LCD) technology

6 Flat-Panel Screens Flat Panel Technologies • Active-matrix LCD • Liquid crystal display (LCD) – Uses many thin-film transistors (TFT) – Originally used for , but – Produces brighter image and can be viewed from wider angles making their way to desktop Passive-matrix LCD computers • Passive-matrix LCD – Uses fewer transistors • Very thin (only a few inches) – Cheaper and uses less power • Produce sharper text images • Gas plasma than CRTs – Supports very large displays – Has brilliant color display • Easier on eyes than CRTs – Viewable at very wide angles

HDTV

• HDTV is a new type of television that supports high-resolution digital broadcasts (up to 1080 lines)

• Wide-format (16:9 instead of regular 4:3)

• All broadcasting is expected to eventually be in high definition

• HDTV monitor can be used as both TV and

Printers Impact Printers

• Produce information on paper output • Physical contact with paper required to produce – Printed output known as hard copy image • Line • Print resolution is commonly measured in dots – Prints an entire line of a program at once – Typically used with mainframe computers printing per inch (dpi). lengthy reports • Dot-matrix printer • Two technologies are used: – Has print head consisting of one – Impact Printers or more columns of pins – Pins form characters and images – Nonimpact printers as pattern of dots – still used for multipart forms

7 Nonimpact Printers Personal Printers: Laser

• Places an image on a page without physically • Laser printers often cost between $200 touching the page and $400 and print 5 to 12 pages per • Laser printer • minute (ppm), at resolutions of at least – Uses light beam to help transfer images to paper – Produces high-quality output at very fast speeds 600 dpi.

• Ink-jet printer „ Work similarly to photocopy – Sprays dots of ink from jet nozzles machines. – Can print in both black and white and „ Toner is in toner cartridge color – Requires high-quality paper so ink does not smear „ Are usually black and white, though color laser printers – Less expensive than laser printers are available.

Personal Printers: Ink-Jet Network Printers

• Ink-jet printers produce images by spraying • A network printer is shared by several thousands of droplets of electrically charged ink onto a page. people over a local area network. • Technology of choice for home users who want to • Line printers print a whole line at a time produce affordable, hard-copy color output from desktop rather than just a character. systems. • Ink is in print cartridge (can be expensive) • Page printers can produce a page of output at a time. • Network laser printers are faster and hold more paper than personal versions.

Special Purpose Printers

• Photo printers „ Portable printers

„ Electrostatic • Bar-code printers

„ Wide-format ink-jet printers • Label printers

8 Multimedia Output Devices Voice Output

• Speakers • Voice synthesizers convert data to vocalized sounds • Two approaches • Data and multimedia projectors – Synthesis by analysis - analyzes actual human voice, records and plays back as needed – Synthesis by rule - uses linguistic rules to create • Voice-output systems artificial speech • Used in automated telephone-based customer service applications – Useful when an inquiry would be followed by a short reply, such as a balance inquiry

Multifunction Devices

• A multifunction device offers some combination of:

– Printing

– Copying

– Scanning

– Faxing

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