Chapter 4: Display Devices Flashcards
VDU
Video Display Unit
Monitor
CRT stands for
Cathode Ray Tube
LCD stands for
Liquid Crystal Display
TTL
Transistor-Transistor Logic
A legacy technology that VGA replaced.
VGA stands for
Video Graphics Array
This is an example of what type of VDU:
CRT
Two ways to measure CRT monitor’s quality
Dot Pitch
Resolution
What is dot pitch
A way of measuring CRT monitor’s image quality.
Measurement expressed in dots per inch (DPI) or in millimeters.
Example: 0.28mm
The higher the dots per inch (or the lower the millimeters, if expressed in mm), the better the image.
Resolution
A way of measuring picture quality.
How many software picture elements (pixels) are used to draw the screen.
Expressed in terms of rows and columns of pixels.
Example: 1024x768
Two types of LCD displays
Active-Matrix
Passive-Matrix
Active Matrix LCD Display
Uses several independent LCD pixels. Allows display to be seen easily from all angles, including from the side. Does not require constant refreshing to maintain an image.
Uses more power than passive-matrix LCDs
Majority of LCDs are active matrix.
Passive Matrix LCD
Display does not have a dedicated transistor for each pixel or subpixel, unlike active matrix LCDs.
Turns a pixel “on” by sending a signal across the x and y coordinate traces that intersect the pixel. See image.
It’s difficult to see the screen unless you’re right in front of it. No easy viewing from the sides.
Dual Scan LCDs
A variation on Passive Matrix LCDs.
The passive matrix is split into two and each half of the is updated seperately
Passive-matrix LCDs have a lower response rate than active-matrix LCDs, which can lead to an effect known as Submarining, which is _____
The temporary visual loss of the cursor because you moved it faster than the screen could keep up.
One of the reasons Mouse Trails were introduced.
Privacy Filter
Panel that fits over the front of a display and uses a polarization effect to limit the viewing angle of the onitors.
Not needed for passive-matrix LCDs, but since most LCDs are active-matrix, they’re applicable.
Can also be used as antiglare filters
LED displays are just ____ panels with light emitting diods as light sources instead of fluorescent bulbs.
LCD
PDP
Plasma Display Panel
Plasma Displays create a cloud of plasma, or _____, to create an image
cloud of ionized particles (atoms and molecules with electrons in an unstable state)
Both PDPs and CRTs can ____ over time
burn out / become “used up”
Refresh Rate
The vertical scan frequency of a monitor. Specifies how many times in one second the scanning beam of electrons redraws a screen in a CRT monitor or are refreshed in an LCD monitor.
Measured in Hertz
Steps to change the refresh rate in Windows 7.
I can’t list the answer here. It’s in the book on page 210. Be sure you can reproduce it.
Screen Resolution
The number of vertical and horizontal pixels that make up the display
Degaussing
Reduction of the magnetic field of an object.
Strictly for CRT monitors, which use magnetic fields (while LCDs do not).
Reduces changes made to the display from magnetic fields NOT caused by the CRT monitor (Like a magent or eletromagnetic interference)
Look like this:
Five primary groups of display adapters in history
Monochrome
CGA
EGA
VGA
DVI/HDMI and other modern digital video
Monochrome Video
First video technology for PCs.
Black and white (well - more like green and amber)
Could display just text at first. Eventually Hercules Computer Technology introduced the Hercules Graphics Card (HGC) that could switch between text mode and graphics mode.
Resolution was 720x350
CGA
Color Graphics Adapter
Allowed for color. Up to 16 colors for text.
Graphics could be displayed with limited color.
VGA
Video Graphics Array
Used for Windows Safe Mode, until recently.
VGA is analog, while MDA, CGA, EGA and later technologies (HDMI and DVI-D) are all digital.
Buil from 256 colors, chosen from various shades of 262,114 colors.
