Chapter 7: Understanding Output

Output

- Output is data that has been processed into a useful form

Output Device

- It is any type of hardware component that conveys information to one or more people
- Eg: Display devices, printers, speakers, headphones, earbuds, data projectors, interactive whiteboards, force-feedback game controllers, tactile output

Display Devices

- It visually conveys text, graphics and video information
- Eg: LCD monitor
- Liquid crystal display (LCD) uses a liquid compound to present information on a display device

• Active-matrix display - Uses a grid of transistors and capacitors with the ability to hold charge for a limited period of time
• Passive-matrix display - Uses a simple conductive grid to apply supply voltage to pixels on the display

- The quality of a LCD screen depends primarily on:

• Resolution - Number of horizontal and vertical pixels in a display
• Response time
• Brightness
• Dot pitch - Distance between sub-pixels
• Contrast ratio

- Graphics processing unit (GPU) controls the manipulation and display of graphics on a display device
- LCD monitors use a digital signal and should plug into DVI port, HDMI port or DisplayPort
- Plasma monitors are display devices that use gas plasma technology and offer screen sizes up to 150"
- Digital television (DTV) offers a crisper, higher quality output
- HDTV is the most advanced form of digital television
- Cathode ray tube (CRT) monitor is a desktop monitor that contains a cathode-ray tube

Printers

- Printer produces text and graphics on a physical medium
- Nonimpact printer forms characters and graphics on a piece of a paper without actually striking the paper

• Ink-jet printers - Forms characters and graphics by spraying tiny drops of liquid ink onto a piece of paper
• Photo printers - Produces color photo-lab-quality pictures. Use ink-jet technology
• Laser printers - High-speed, high-quality, color / B&W

• Thermal printers - Generates images by pushing electrically heated pins against the heat-sensitive paper. Eg: Thermal wax-transfer printer, dye-sublimation printer
• Mobile printers - Small, lightweight, battery-powered printer that allows a mobile user to print from a notebook computer, smartphone or other mobile device
• Label printers - Small printer that prints on adhesive-type material
• Postage printers - Prints postage stamps
• Plotters - Produce high-quality drawings
• Large-format printers - Create photo-realistic quality color prints on a larger scale

- Multifunction peripheral (MFP) is a single device that prints, scans, copies and in some cases faxes
- Impact printers form characters and graphics on a piece of paper by striking a mechanism against an inked ribbon that physically contacts the paper

• Dot-matrix printer - Produces printed images when tiny wire pins on a print head mechanism strike an inked ribbon
• Line printer - Prints an entire line at a time

Speakers, Headphones & Earbuds

- It is an audio output device produces music, speech or other sounds
- Users attach speakers to their computers to:

• Generate higher-quality sounds for playing games
• Interact with multimedia presentations
• Listen to music
• View movies

- Headphones are speakers that cover or placed outside of ear
- Earbuds rest inside ear canal
- Some speakers are specifically designed to play audio from a portable media player. Eg: Wireless speakers.
- Voice output occurs when you hear a person's voice or when the computer talks to you through the speakers
- Some website dedicate themselves to providing voice output
- Voice output often works with voice input
- VoIP uses voice output and voice input

Data Projector

- A device that takes the text and images displaying on a computer screen and projects them on a larger screen

Interactive whiteboard

- A touch-sensitive device, resembling a dry-erase board, that displays the image on a connected computer screen

Force-feedback Game Controller

- It sends resistance to the device in response to actions of the user

Tactile Output

- It provides the user with a physical response from the device