CHAPTER 4 OUTPUT DEVICES

Objectives: Define output and output device Describe the four categories of output Explain the types of output devices

WHAT IS OUTPUT AND OUTPUT DEVICE? Output is data that has been processed into a useful form   Output device is any hardware component that can convey information to one or more people

Categories of output: Text – memos, letters, press releases, reports, classified advertisements, envelops, mailing labels, text messages Graphics – logos, charts, drawings, clip arts, photos Audio – songs, narrations, speeches Video – video blogs, vodcast

Categories of Output

CATEGORIES OF OUTPUT DEVICES Display devices Printers Speakers, headphones, and earbuds Data projectors Interactive whiteboards Force-feedback game controllers Tactile output

Display Devices A display device visually conveys text, graphics, and video information A monitor is packaged as a separate peripheral LCD monitor Widescreen Discovering Computers 2010: Living in a Digital World Chapter 6

DISPLAY DEVICES Flat-Panel Displays CRT Monitors LCD Monitor Plasma Monitor Digital Television (DTV) CRT Monitors

Flat-Panel Displays Output device that visually conveys text, graphics, and video information Information on display device sometimes called soft copy

LCD monitor A desktop monitor that uses liquid crystal display to produce images Produce sharp, flicker free images Mobile devices that contain LCD displays include Notebook computer, Tablet PC, ultra personal computer, portable media player, smart phone, and PDA

Factors to be considered in selection of LCD Resolution Response time Brightness Dot pitch Contrast ratio

Resolution Number of horizontal and vertical pixels in a display device Sharpness and clarity of image Higher resolution makes image sharper, displays more text on screen, makes some elements smaller

Dot pitch Distance in millimeters between pixels on a display device Text created with a smaller dot pitch is easier to read Average dot pitch on LCD monitors and screen should be 0.30mm or lower. The lower the number, the sharper the image

Response time The time in milliseconds (ms) that it takes to turn a pixel on or off LCD monitor’ and screens’ response time today range from 3 to 16 ms. The lower the number, the faster the response time

Brightness Measured in nits. A nit is a unit of visible light intensity equal to one candela per square. Candela is the standard unit of luminous intensity LCD monitors and screen range from 250 to 550 nits. The higher the nits, the brighter the images

Contrast ratio Describe the difference in light intensity between the brightness white and darkest black that can be displayed on an LCD monitor Contrast ratios today range from 500:1 to 2000:1. Higher contrast ratios represent colours better

Plasma monitor A display device that uses gas plasma technology, which sandwiches a layer of gas between two glass plate Offer size up to 150 inches wide and richer colors than LCD, but are more expensive

Digital Television (DTV) Uses digital signals to produce crisper, higher-quality output on LCD and plasma televisions HDTV (high-definition television) is the most advanced form of digital television. Great for game playing, watching movies, and browsing the Internet

CRT Monitors Contains cathode-ray tube (CRT) Screen coated with tiny dots of phosphor material. Each dot consists of a red, blue, and green phosphor

What determines the quality of a CRT monitor? Screen resolution Text created with a smaller dot pitch is easier to read Refresh rate is speed at which monitor redraws images on screen

Printers A printer produces text and graphics on a physical medium Printed information is called a hard copy, or printout Landscape or portrait orientation

PRINTER Non impact printers Impact printers Ink-jet printers Photo printers Laser printers Thermal printers Mobile printers Label and postage printers Plotters Large format printers Impact printers Dot-matrix printer Line printer Discovering Computers 2010: Living in a Digital World Chapter 6

Non Impact Printers A nonimpact printer forms characters and graphics on a piece of paper without actually striking the paper. Some spray ink, while others use heat or pressure to create images Ink-jet printers Photo printers Laser printers Thermal printers Mobile printers Label and postage printers Plotters Large-format printers

What is the resolution of a printer? Sharpness and clarity Measured by number of dots per inch (dpi) printer can output

Ink-jet printer sprays tiny drops of liquid ink from jet nozzles onto paper Prints in black-and-white or color on a variety of paper types Requires high-quality paper so ink does not smear Less expensive than laser printers

Photo printer Color printer that produces photo-lab-quality pictures Many photo printers have a built-in card slot PictBridge is a standard technology that allows you to print pictures directly from a digital camera

Laser printer High-speed, high-quality nonimpact printer Prints text and graphics in high-quality resolution, ranging from 1,200 to 2,400 dpi Typically costs more than ink-jet printer, but is much faster

Thermal Printer Thermal wax-transfer printer Dye-sublimation printer A thermal printer generates images by pushing electrically heated pins against the heat-sensitive paper Thermal wax-transfer printer Dye-sublimation printer

Mobile Printer A mobile printer is a small, lightweight, battery-powered printer that allows a mobile user to print from a notebook computer, smart phone, or other mobile device

Label Printers and Postage Printers Small printer that prints on adhesive-type material Most also print bar codes Postage printer has built-in digital scale and prints postage stamps

Plotter Sophisticated printer used to produce high-quality drawings such as blueprints, maps, and circuit diagrams Large-format printer creates photo-realistic-quality colour prints. Graphic artists use these high-cost, high-performance printers for signs, posters, and other professional quality displays.

Dot-matrix printer Line printer Impact Printers Forms characters and graphics on a piece of paper by striking a mechanism against an inked ribbon that physically contacts paper Characteristically are noisy because of this striking activity Dot-matrix printer Line printer

Dot-matrix printer Impact printer that produces printed images when tiny wire pins strike ribbon Speed measured by the number of characters per second (cps)

Line Printer High-speed impact printer that prints entire line at a time Speed measured in lines per minute (lpm)

Speakers, Headphones, and Earbuds An audio output device produces music, speech, or other sounds Most computer users attach speakers to their computers to: Generate higher-quality sounds for playing games Interact with multimedia presentations Listen to music View movies

Speakers, Headphones, and Earbuds Headphones are speakers that cover or are placed outside of the ear Earbuds (also called earphones) rest inside the ear canal

Speakers, Headphones, and Earbuds Some speakers are specifically designed to play audio from a portable media player Wireless speakers

Speakers, Headphones, and Earbuds Voice output occurs when you hear a person’s voice or when the computer talks to you through the speakers Some Web sites dedicate themselves to providing voice output Often works with voice input VoIP uses voice output and voice input

Other Output Devices Other output devices are available for specific uses and applications Data projectors Interactive whiteboards Force-feedback game controllers Tactile output

Data Projector A data projector is a device that takes the text and images displaying on a computer screen and projects them on a larger screen LCD projector Digital light processing (DLP) projector

Interactive Whiteboard An interactive whiteboard is a touch-sensitive device, resembling a dry-erase board, that displays the image on a connected computer screen

Force-Feedback Controller and Tactile Output Force-feedback sends resistance to the device in response to actions of the user Tactile output provides the user with a physical response from the device