1. Seeing, Hearing, and printing Data
Chapter 4
Seeing, Hearing, and printing Data
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2. Video and Sound

3. Monitors Most common output device Connects to the video card
Categorized by color output
Monochrome
One color with black background
Grayscale
Varying degrees of gray
Color
Display 4 to 16 million colors

4. Monitors Cathode Ray Tube (CRT) Most common type of monitor
Electrons fired from the back
Electrons excite phosphor to glow
Phosphor is arranged in dots called pixels
Dot mask ensures proper pixel is lit

5. Monitors CRT color Phosphor dots arranged in triads
Red, green, and blue dots
Three colors blend to make colors
Varying the intensity creates new colors
Teaching tip
Unless your students have spend a lot of time with HTML or graphics colors, they will have a hard time grasping how RGB values work. The best methods are to show them various colors and then let them experiment. The website provides decimal-value examples of RGB values. Once the students have seen different colors, open MS Paint and let the students develop their own colors. Challenge them to build pink, orange, brown and any of their favorite colors

6. Monitors CRT drawbacks Very large (16 inches deep)
Very heavy (30 pounds)
Use a lot of electricity

7. Monitors Liquid Crystal Display (LCD) Commonly found on laptops
Desktop versions exist
Solve the problems of CRT
Fluorescent lights provide illumination

8. Monitors Passive matrix LCD Pixels arranged in a grid
Pixels are activated indirectly
Row and column are activated
Animation can be blurry

9. Monitors Active matrix LCD Each pixel is activated directly
Pixels have 4 transistors
One each for red, green, blue
One for opaqueness
Transistors arranged in a thin film
Animation is crisp and clean

10. Monitors Drawbacks to LCD More expensive than CRT
Must sit directly in front of screen
Can be more fragile than CRT
Insider information
The limited viewing angle can be an advantage. For high security systems, low viewing angles stop casual glances at the screen.

11. Monitors Paper-white displays Electro-luminescent displays (ELD)
High contrast between fore and background
Electro-luminescent displays (ELD)
Similar to LCD
Uses phosphor to produce light
Plasma monitor
Gas is excited to produce light

12. Monitors and Video Cards
Monitors impacts user effectiveness
Monitors should have
Crisp text
Clear graphics
Adjustable controls
Clear edges

13. Monitors and Video Cards
Size of monitor
Measured in inches
Measured diagonally
Actual size
Distance from corner to corner
Viewable size
Useable portion of the screen
Teaching tip
It is helpful to draw the relationship between viewable and actual size.

14. Monitors and Video Cards
Resolution
Number of pixels on the screen.( (a) 640*480 (b) 800*600 (c) 1024*768 (d) 1152*864 (e) 1280*1024
Higher number creates sharper images
Higher number creates smaller images
Insider information
Many CRT’s are capable of supporting several resolutions. LCD monitors in contrast often can only support one or two resolutions. The reason are the transistors on the LCD cannot move, while the electron gun on the CRT can simply aim for a smaller pixel.
If you are in a computer class, stop and have students adjust their resolution on the screen. The simplest method is to right click the desktop and select properties. Click the settings tab, and adjust the slider. As the students are experimenting, have a student answer why larger resolution numbers make smaller images. The answer is higher resolutions draw with smaller pixels.

15. Monitors and Video Cards
Refresh rate
Number of time the screen is redrawn
Modern equipment sets this automatically
Improper settings can cause eyestrain
Insider information
Refresh rate is measured in Hz, or in cycles/sec. This means that if a monitore fresh rate is 100 Hz, it refreshes its pixels 100 tikes every second.
Whenever a TV camera films a computer monitor, the monitor seems to have a line moving up the screen. This is the monitor refreshing the pixels. The camera films faster than the eye can see, which is why the refresh is noticeable.

16. Monitors and Video Cards
Dot pitch
Distance between the same color dots
Ranges between .15 mm and .40 mm
Smaller creates a finer picture
Should be less than .22
Insider information : When shopping for a color monitor, you should look for a dot pitch no greater than .28 mm. That number generally applies to 15-inch monitors.

17. Video Cards Device between the CPU and monitor
Better cards result in better output
Removes burden of drawing from CPU
Have their own processor and RAM
Modern cards have up to 512 MB RAM
Capable of rendering 3D images
Insider information
The two leading video card families are ATI’s Radeon and NVIDIA’s GeForce line. Both offer exceptional graphics cards ranging from $50 to $600.

18. Ergonomics and Monitors
Eyestrain
Fatigue of the eyes
Steps to avoid
Choose a good monitor
Place the monitor 2 – 3 feet away
Center of screen below eye level
Avoid reflected light
If you can not avoid the reflection use an antiglare screen to reduce the reflection on the screen.

19. Ergonomics and Monitors
Electronic magnetic fields (EMF)
Generated by all electronic devices
EMF may be harmfull to health
Steps to avoid
Keep the computer at arms length
Take frequent breaks
Use an LCD monitor
Teaching tip
Point out to the students that no conclusive study exists that directly list EMF as a cause of cancer, reduced muscle tone or reduced brain function. For more information see and search for EMF.

20. Data Projectors Replaced overhead and slide projectors
Project image onto wall or screen
LCD projectors
Most common type of projector
Small LCD screen
Very bright light
Require a darkened room

21. Data Projectors Digital Light Projectors
A series of mirrors control the display
May be used in a lighted room
Insider information
A projector is rated in lumens. This is a measure of how bright the projector is. Higher lumens ratings result in a brighter projector. For a guide to lumens ratings, see

22. Sound Systems Integral part of the computer experience
Capable of recording and playback

23. Sound Systems Sound card Device between the CPU and speakers
Converts digital sounds to analog
Can be connected to several devices
Modern cards support Dolby Surround Sound
Insider Information
Sound Blaster is the primary manufacturer of sound cards. Exceptional models start at around $30.00.

24. Sound Systems Headphones and headsets
Replacement for speakers and microphones
Offer privacy
Does not annoy other people
Outside noise is not a factor
Headsets have speakers and a microphone
Insider information
The PS2 game SOCOM II Navy Seals includes a USB headset to allow verbal communication with other team members.

25. Printing

26. Commonly Used Printers
Impact printers
Generate output by striking the paper
Uses an inked ribbon
Non-impact printers
Use methods other than force
Tend to be quiet and fast
Inkjet printers, for example, use tiny nozzles to spray droplers of ink onto the page.

27. Commonly Used Printers
Dot matrix printers
Impact printer
Used to print to multi-sheet pages
Print head strikes inked ribbon
Line printers
Band printers
Speed measured in characters per second(cps)

28. Dot Matrix Print Head

29. Commonly Used Printers
Ink-jet printers
Non-impact printer
Inexpensive home printer
Color output common using CMYK
Cyan, magenta, yellow, black
Sprays ink onto paper
Speed measured in pages per minute
Quality expressed as dots per inch
Insider information
Nearly all of the electronics for the printer is kept in the ink cartridge. Thus, when the cartridge is replaced the printing components of the printer are replaced. Refilling cartridges is OK, but should not be reused more than 2-3 times.

30. Dots Per Inch

31. Commonly Used Printers
Laser printer
Non-impact printer
Produces high quality documents
Color or black and white
Print process
Laser draws text on page
Toner sticks to text
Toner melted to page
Speed measured in pages per minute
Quality expressed as dots per inch
Insider information
The laser printer works on a similar process to a photocopier. The first photocopier as we know it today was invented in Astoria NY in 1938 by Chester Carlson and Otto Kornei.

32. Commonly Used Printers
All-in-one peripherals
Scanner, copier, printer and fax
Popular in home offices
Prices are very reasonable

33. Comparing Printers Determine what you need
Determine what you can spend
Initial cost
Cost of operating
Image quality
Speed
600dpi means 600 columns of dots and 600 rows of dots per inch.
Printer speed is measured in the number of pages per minute (ppm)

34. High-Quality Printers
Special purpose printers
Used by a print shop
Output is professional grade
Prints to a variety of surfaces

35. High-Quality Printers
Photo printers
Produces film quality pictures
Prints very slow
Prints a variety of sizes
Several models creat prints no larger than a standerd 4 * 6 inch snapshot, although newer photo printers can produce 8 * 10 inch or even 11 * 14 inch prints. Photo printers range in price from 200 dollar to 500 dollar.

36. High-Quality Printers
Thermal wax printers
Produces bold color output
Color generated by melting wax
Colors do not bleed
Operation costs are low
Output is slow

37. High-Quality Printers
Plotters
Large high quality blueprints
Older models draw with pens
Operational costs are low
Output is very slow
A roller plotter uses a robotic arm to draw with colored pens on oversized paper.Here, an architectural drawing is being printed.

38. End of Chapter