1. Display Devices
Display device: output device that presents output visually
Monitor/Display screen: The display device used with desktop computers, notebook computers, handheld PCs, smart phones, consumer devices, and many other devices

3. Display Device Characteristics
Usually color, but can be monochrome
Can be a CRT monitor or a flat-panel display
CRT monitor: projects images onto a display screen using technology similar to that of TVs
Flat-panel display: forms images by manipulating electronically charged chemicals or gases sandwiched between thin panes of glass or a liquid crystal. Popular flat panels displays are Plasma screens and LCD screens.

5. CRT vs. Flat-Panel Monitors

6. Display Device Characteristics, Cont’d
Size (measured diagonally)
Screen resolution
Can be changed
Higher resolution = more data on the screen at one time

7. Display Device Characteristics, Cont’d
Video card (determines display characteristics and how monitor can connect to the PC)
Monitors can be also be:
Wired or wireless
2D or 3D Displays
Digital TV and/or HDTV ready or capable

8. Flat-Panel Display Technologies
Liquid crystal displays (LCDs): use charged liquid crystals to display images
Organic light emitting diode (OLED) displays: use emissive organic material to display brighter and sharper images
Plasma displays: use layers of gas to display images; most often used on large displays

9. Flat-Panel Display Technologies, Cont’d

10. Monitors - Comparing Monitors
When comparing monitors, consider four features:
Size
Resolution
Refresh rate
Dot pitch

11. Comparing Monitors - Size
A monitor's size is the diagonal measurement of its face, in inches.
For years, 15" monitors (13"viewing area) were standard.
Today, 17" monitors (15" viewing area) are common.
Larger monitors are available, but can be expensive.

12. The diagonal
size (often 15”)

13. Comparing Monitors - Resolution
Resolution is the number of pixels on the screen, expressed as a matrix (such as 600x800).
A 17" monitor offers resolutions from 640x480 up to 1280x1024.
The Video Graphics Array (VGA) standard is 640x480. Super VGA (SVGA) monitors provide resolutions of 800x600, 1024x768 or higher.

14. Resolution (image sharpness) is important.
(Especially for graphics, page layout, and CAD)

15. Comparing Monitors - Refresh Rate
Refresh rate is the number of times each second that the electron guns scan the screen's pixels.
Refresh rate is measured in Hertz (Hz), or cycles per second.
Look for a refresh rate of 72 Hz or higher. A slower rate may cause eyestrain.

16. Fast scanning = Quick refresh (less flicker)

17. Comparing Monitors - Dot Pitch
Dot pitch is the distance between the phosphor dots that make up a single pixel.
In color monitors, three dots (red, green, and blue) comprise each pixel.
Look for a dot pitch no greater than .28 millimeter.

18. Fine dot pitch = Crisp displays

19. Monitors - Video Controllers
The video controller is an interface between the monitor and the CPU.
The video controller determines many aspects of a monitor's performance, such as resolution or the number of colors displayed.
The video controller contains its own on-board processor and memory, called video RAM (VRAM).

20. VRAM Video Control Board with Monitor Cable
Graphic intensive applications such
as games require plenty of VRAM.

22. Data and Multimedia Projectors
Data projector: display device that projects all computer output to a wall or projection screen
Most data projectors today can project video, in addition to computer output.
Can be wireless projectors

23. Printers Printer: output device that produces output on paper
Produce hard copy
Can be used with both desktop and portable PCs
Printer characteristics
Impact vs. nonimpact printing
Most printers are nonimpact
Impact printers (like dot-matrix printers) are still used for printing multipart forms and shipping documents

24. Printers Printer characteristics, cont’d
Can print in color or black-and white
Can be a personal or network printer
Quality is called print resolution and measured in dots per inch (dpi)
Print speed is measured in pages per minute (ppm)

25. Laser Printers
Laser printer: output device that uses toner powder and technology similar to that of a photocopier to produce images on paper
The standard for business documents
Print one entire page at a time
Usually black and white, though color printers are available
Common print resolution for laser printers is between 600 and 2,400 dpi

27. Ink-Jet Printers
Ink-jet printer: output device that sprays droplets of ink to produce images on paper
Typically print in color
Often the choice for home use
Print fairly slowly, one line at a time
Quality not quite as good as a laser printer

29. Special Purpose Printers
Photo printers (designed to print photographs)
Barcode printers (print barcodes)
Label printers (print labels, electronic postage, etc.)
Portable printers (designed to be carried with you)
Plotters and wide-format ink-jet printers (print on large paper or other large materials)

31. Multifunction Devices
Multifunction device: device that offers some combination of printing, copying, scanning, and faxing capabilities
Most commonly, these types of devices are based on color ink-jet printer technology, although laser multifunction devices are available
Advantage: takes up less space and is less expensive than purchasing multiple machines
Disadvantage: Lose all devices if it needs to be repaired

32. Audio Output Audio output: output in the form of voice or music
Speakers: connect to a PC and provide audio output for computer games, music, video, TV, videoconferencing, and other applications that have audio output
Voice output systems: produce spoken output