Discovering Computers Chapter 6 Output

2 Ch 4 Processor Control Unit Arithmetic Logic Unit (ALU) Input Devices Ch 5 Storage Devices Ch 7 Output Devices Ch 6 Data Information Instructions Data Information Control Unit Ch 1 – Introduction Ch 2 – Internet & WWW Ch 3 – Application Software Ch 8 – System Software

3 video audio text graphics Output what? Information - processed, organized, meaningful, useful data

Output device conveys information

5 printer display speakers

6 Display devices Printers Speakers, headphones, ear buds Data projectors Interactive whiteboards Force- feedback game controllers Tactile output

What is a display device?  Output device that visually conveys text, graphics, and video information  Information on display device is called soft copy  Monitor houses display device as a separate peripheral

CRT (Cathode Ray Tube) Monitors What is a CRT monitor?  Contains cathode-ray tube (CRT)  Screen coated with tiny dots of phosphor material  Each dot consists of a red, green, and blue phosphor  Common sizes are 15, 17, 19, 21, and 22 inches  Viewable size is diagonal measurement of actual viewing area

What is an LCD monitor?  Uses liquid crystal display  Mobile devices that contain LCD displays include  Notebook computer, Tablet PC, desktop computer, portable media player, smart phone, and PDA

Using multiple LCD monitors  Some users position two or more monitors side-by-side or stacked  Allows users to run multiple applications simultaneously

What is a plasma monitor?  Displays image by applying voltage to layer of gas  Larger screen size and richer colors than LCD, but plasma monitors are more expensive

The graphics processing unit (GPU) controls the display of graphics 13

Interactive screen More and more electronic screens are used to interact with the computer rather than just reflect information delivered by the computer. Interactive screen

The quality of a display depends on: 15 Resolution Refresh rate = Response time Dot pitch Color depth

What is resolution?  Higher resolution makes image sharper, displays more text on screen  Number of horizontal and vertical pixels in a display device

x 600 most common 1280 x 1024 maximum resolution of most monitors 800 horizontal pixels 600 vertical pixels Total 480,000 pixels 2048 x 1536 maximum for high-end monitors

18 What is dot pitch? Measure of the distance between pixels Sometimes called pixel pitch Smaller the distance between the pixels, the sharper the image Use a monitor with a dot pitch of.29 millimeters or lower to minimize eye fatigue

19 24-bit video card Uses 24 bits to store information about each pixel Can display 16.7 million colors 2 24 = 16.7 million colors Number of bits a video card uses to store information (color) of each pixel Also called color depth Determines number of different colors The greater the number of bits (color depth), the better are colors of the image 8-bit video card Uses 8 bits to store information about each pixel Can display 256 different colors 2 8 = 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 = 256 colors What is bit depth?

What is important in a monitor?  Price of a display is the biggest part of the computer price  Screen resolution: more pixels – sharper picture  Refresh rate is speed at which monitor redraws images on screen  Energy consumption  Dot pitch: distance between neighboring pixels  Color depth: more bytes to carry the color of a pixel

Television From 3 channels to 300 From analog to digital From TV to HDTV Next is streaming

What is digital television (DTV) DTV uses digital signals to produce crisper, higher-quality output on LCD and plasma televisions Many programs can be broadcast on a single digital channel

Great for game playing, watching movies, and browsing the Internet HDTV (high-definition television) HDTV (high-definition television) is the most advanced form of digital TV What is high-definition television HDTV)? High resolution

Using a computer to deliver television Just a few years ago it seemed far-fetched: there was not much video online that was legal and non-pornographic; broadband wasn’t available That has changed. Here are some video- streaming websites: iPlayer, Hulu, YouTube that stream billions of videos per month Ordinary people want a cable that will allow them to connect their computers to their television sets 24

Three-dimensional TV is coming Three-dimensional TV works by projecting two images filmed from slightly different angles onto the screen. Battery-powered glasses ($150 for two sets) alternately darken each lens, so each eye sees only one of two images “Monsters v Aliens”, “Avatar”, “My Bloody Valentine 3D”, televised sport will gain the most. Sport is the “killer application” of today's TV 25

What is the ENERGY STAR program?  Encourages manufacturers to create energy-efficient devices that require little power when not in use  Monitors and devices meeting guidelines display ENERGY STAR label

What is an audio output device?  Computer component that produces music, speech, or other sounds  Speakers and headsets are common devices

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 VoIP uses voice output and voice input 28

Headphones are speakers that cover your head or are placed outside of the ear Ear buds (also called earphones) rest inside the ear canal 29

Some speakers are specifically designed to play audio from a portable media player  Wireless speakers 30

Printers and other output devices

Printers What is a printer?  Output device that produces text and graphics on a physical medium (paper, film, fabric)  The result is the hard copy, or printout  Two orientations: portrait landscape portrait landscape

Nonimpact printer forms characters and graphics on a piece of paper without actually striking the paper 34 Ink-jet printers Photo printers Laser printers Thermal printers Mobile printers Label and postage printers Plotters Large- format printers

Ink-jet printer  Ink-jet printer sprays tiny drops of liquid ink onto paper  Prints in black-and- white or color on a variety of paper types

How does an ink-jet printer work? Step 1. A small resistor heats the ink, causing the ink to boil and form a vapor bubble. Step 2. The vapor bubble forces the ink through the nozzle. Step 3. Ink drops onto the paper. Step 4. As the vapor bubble collapses, fresh ink is drawn into the firing chamber. print cartridge print head firing chamber nozzle bubbleresistorink ink dot

A photo printer produces color photo-lab-quality pictures Most use ink-jet technology PictBridge allows you to print photos directly from a digital camera Print from a memory card and preview photos on a built-in LCD screen 37

Laser printer High- speed High- quality Color Black- and- white High price 39

How does a laser printer work?

A thermal printer generates images by pushing electrically heated pins against the heat-sensitive paper 41 Thermal wax- transfer printer Dye-sublimation printer

A mobile printer is a small, lightweight, battery-powered printer that allows a mobile user to print from a mobile device 42

A label printer is a small printer that prints on adhesive-type material A postage printer prints postage stamps 43

What is a plotter?  Sophisticated printer used to produce high-quality drawings  Large-format printer creates photo-realistic-quality color prints

A multifunction peripheral (MFP) is a single device that prints, scans, copies, and sends faxes  Sometimes called an all-in-one device 45

Impact printer dot-matrix: produces printed images when tiny wire pins strike ribbon band: prints fully formed characters using a hammer mechanism

What is a line printer?  High-speed impact printer that prints entire line at a time Some line printers are band printers Others are shuttle- matrix printers

Speed Characteristics of a Printer Price Color vs. black- white Cost per page Cost per page Paper types and sizes Graphics and photo printing Portable/ Stationary Portable/ Stationary System compatibility Wireless capability Resolution

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

50 special- purpose terminals intelligent terminals Terminals What is a terminal? dumb terminals Device that performs both input and output

What is a facsimile (fax) machine? Device that transmits and receives documents over telephone lines

What is a fax modem?  Extension that allows you to send and receive electronic documents over Internet as faxes external fax modem internal fax card in system unit fax machine

An interactive whiteboard is a touch-sensitive device, resembling a dry-erase board, that displays the image on a connected computer screen 53

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 54

What is a data projector?  Device that takes text and images from computer screen and projects them onto larger screen

Output Devices for Physically Challenged What is the Magnifier?  Windows Magnifier enlarges text and other items on screen

Output Devices for Physically Challenged What other output options are available for visually impaired users?  Change Window settings, (increase the size or change color of text) to make words easier to read  Blind users can work with Windows Vista’s Narrator  Braille printer outputs information in Braille onto paper

To see the online addition to the book click here