© 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Chapter 2B Output Devices

2 2 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Learning Objectives 2.5Describe the most common types of computer monitors 2.6Identify the reasons sound systems are useful 2.7Compare the most widely used types of printers 2.8Describe other devices that a computer can use for output

3 3 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Monitors

4 4 Types of Monitors Cathode ray tube (CRT) monitors are powered by a large vacuum tubeCathode ray tube (CRT) monitors are powered by a large vacuum tube Flat-panel displays are a thinner alternative to a CRTFlat-panel displays are a thinner alternative to a CRT –Most flat-panel monitors have a liquid crystal display (LCD) –LED monitors use tiny electronic lights called light- emitting diodes (LEDs) Specialized monitors include:Specialized monitors include: –Paper-white displays –Electroluminescent displays (ELDs) –Plasma displays

5 5 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Comparing Monitors Some factors worth considering:Some factors worth considering: –Size –Text display –Image display –Resolution - the number of pixels displayed on the screen –Response rate - amount of time in a milliseconds that it takes for a pixel to change from black to white –Contrast ratio - how close the monitor can get to perfect black and white

6 6 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Comparing Monitors, cont’d. Other factors worth considering include:Other factors worth considering include: –Viewing angle - measures how far to the side a user can be before the picture fades or blurs –Refresh rate - the number of times per second that the monitor draws its visible image –Dot pitch - the distance between the like-colored phosphor dots of adjacent pixels

7 7 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Video Card A video card contains the video-dedicated memory and sends information to the monitor for displayA video card contains the video-dedicated memory and sends information to the monitor for display The quality of images displayed depends as much on the video card as on the monitorThe quality of images displayed depends as much on the video card as on the monitor Video cards now commonly support at least two displaysVideo cards now commonly support at least two displays

8 8 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Ergonomics and Monitors Eyestrain is fatigue of the eyes caused by focusing on the same point for too longEyestrain is fatigue of the eyes caused by focusing on the same point for too long –One of the most frequently reported health problems associated with computer use Measures to reduce eyestrain:Measures to reduce eyestrain: –Choose a monitor that does not flicker –Position your monitor 2 to 2-1/2 feet away from your eyes –Avoid looking at the monitor for more than 30 minutes

9 9 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Sound Systems Sound system devices include:Sound system devices include: –Microphones –Speakers –Headphones and headsets –Sound cards - circuit boards that convert sound from analog to digital form, and vice versa –Sound editing programs

10 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Printers Basic categories:Basic categories: –Impact printers - create an image by striking an inked ribbon against paper –Nonimpact printers - use other means to create an image

11 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Types of Printers Dot matrix printers are impact printers where physical impact with the paper is importantDot matrix printers are impact printers where physical impact with the paper is important –The printer creates an image by using mechanism called a print head Inkjet printers create an image by spraying inkInkjet printers create an image by spraying ink Laser printers rely on a laser to printLaser printers rely on a laser to print All-in-one printers combine a printer with scanning, photocopying, and faxing capabilitiesAll-in-one printers combine a printer with scanning, photocopying, and faxing capabilities

12 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Special-Purpose Printers Dye-sublimation (dye-sub) printers produce realistic quality and color for photo imagesDye-sublimation (dye-sub) printers produce realistic quality and color for photo images Photo printers use inkjet or dye-sub technology to create high-quality imagesPhoto printers use inkjet or dye-sub technology to create high-quality images Thermal-wax printers operate with a ribbon coated with panels of colored wax that melts and adheres to the paperThermal-wax printers operate with a ribbon coated with panels of colored wax that melts and adheres to the paper Plotters are used to print large-format imagesPlotters are used to print large-format images Line printers uses a wide print headLine printers uses a wide print head Band printers uses a rotating band embossed with alphanumeric charactersBand printers uses a rotating band embossed with alphanumeric characters

13 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Comparing Printers The selection of a printer should be based on the kinds of output needed, as well as the following considerations:The selection of a printer should be based on the kinds of output needed, as well as the following considerations: –Cost –Image quality: The more dots per inch (dpi) a printer can produce, the higher its image quality –Speed: Printer speed is measured in pages per minute (ppm)

14 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Projectors Digital light processing (DLP) projectors have millions of microscopic mirrors that shift to reflect the source of lightDigital light processing (DLP) projectors have millions of microscopic mirrors that shift to reflect the source of light Methods of accepting outputMethods of accepting output –Hooked up to the computer as a monitor –Via a local network of computers –From a USB flash drive

15 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. SMART Boards SMART boards - digital versions of the whiteboardsSMART boards - digital versions of the whiteboards –The board attached to the wall is a touch-sensitive input device –Short-throw projector - designed to be used very close to the display area –Special pens and an eraser are used for input

16 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Haptic Feedback Haptic feedback - the communication of vibration, motion, or physical resistanceHaptic feedback - the communication of vibration, motion, or physical resistance –Game controllers often include mechanical motion generators –Haptic feedback increases the user’s sense of immersion in the game –Force feedback is the application of motion to a controller together with a visual event

17 © 2013 by the McGraw-Hill Companies, Inc. All rights reserved. Computer-aided Manufacturing Computer output is used to drive industrial machinery and robot production in many different manufacturing industriesComputer output is used to drive industrial machinery and robot production in many different manufacturing industries Computer instructions coordinate and control several different motors in a robotic armComputer instructions coordinate and control several different motors in a robotic arm Applications include:Applications include: –Welding cars –Drilling holes precisely –Fabricating tiny computer chips