Display Technologies Flashcards
CRT
Cathode Ray Tube:
An old type of display used by PC/Mac a while back.
Had toxic materials inside; required licensed recycling services to dispose.
LCD
Liquid Crystal Display:
Primary visual output component today.
Uses liquid crystals that take advantage of polarization.
Tiny liquid crystal molecules arranged in rows and columns between polarizing filters.
Liquid Crystals
Composed of specially formulated liquid full of long, thin crystals that always want to orient themselves in the same direction. Acts as a polarized filter.
Sub-Pixels
Any of the units that make up a pixel. Each pixel usually has one red, green, and blue subpixel.
In LCD: Translucent sheet above the subpixels is colored red, green, blue.
Pixel
Tiny distinct group of RGB subpixels.
Static Charging (Older LCDs)
Didn’t use rectangular pixels.
Images were composed of different-shaped elements, each electrically separate from the others.
To create an image, each area was charged at the same time.
Earlier LCDs (Functionality)
Matrix of wires on an X & Y axis running along rows & columns of subpixels.
Needed a charge on both wires to light a subpixel.
Passive Matrix
Three matrices intersected very close together.
Above intersections: glass coated RGB dots.
Varying voltage on wires made different RGB levels to create colors.
TFT
Thin Film Transistor (Active Matrix - Modern LCDs):
One or more tiny transistors control each color dot, providing a faster display, crisp definition, and much tighter color control.
LCD Components (List)
LCD Panel: Creates the image
Backlight: Illuminates the image
Inverters (older): Send power to backlights that need AC
TN (LCD Panel Tech)
Twisted Nematic: Fastest, but inadequate color
Main tech breakthrough that made LCDs practical.
Takes advantage of nematic substance ability to rotate the polarization of light beams.
IPS (LCD Panel Tech)
In-Plane Switching: Beautiful color, best viewing angle
Designed to resolve limitations of TN (color, angle)
VA (LCD Panel Tech)
Vertical Alignment: In between TN & IPS
Characterized by vertically aligned pixels. Liquid pixels run vertically to glass substrate on which they are used.
LED (Backlight)
Light-Emitting Diode (Modern): DC electricity; consumes less energy than CCFL. Gives off no heat Enables super thin screens Does not need inverter
CCFL (Backlight)
Cold Cathode Fluorescent Lamp (Older): Low power use Even brightness Long life Required high-frequency AC Needed inverter to convert to AC from DC in monitor PSU
Edge LED Backlighting
Two backlights: One at top, one at bottom
Drawback: can sometimes notice brighter edges
Direct LED Backlighting
Puts a bank of LEDs behind the panel providing better uniformity.
More expensive & more energy than Edge backlighting.
Resolution
Describes the number of pixels on display.
Native Resolution
Specified resolution for a monitor. One should not use any other resolution than the native. (Cannot run higher, shouldn’t run lower)
Interpolation
Softening the jagged corners of pixels when running at a lower resolution than the native.
Video Modes (3 Names & Resolutions)
VGA = 640 x 480 WXGA = 1366 x 768 FHD = 1920 x 1080
Aspect Ratio
Number of pixels arranged on the screen.
16: 9 = 1080p
21: 9 = 3440 x 1440 (on some laptops/phones)
PPI
Pixels Per Inch:
Combination of physical size & resolution.
Higher res + smaller screen = Greater PPI
(Why phones and small screens can look so amazing)
Brightness (LCD Backlight Measurement)
The strength of an LCD monitor’s backlights.
Measured in nits
100 = low end
300 = average
1000+ = high end
Viewing Angle (Viewing Cone)
TN Viewing Angle
IPS Viewing Angle
LCD panels have a limited viewing angle.
The screen will fade when viewed from the side.
TN = 70 degree viewing cone IPS = 178 degree viewing cone
Response Rate
The amount of time it takes for all of the subpixels on the panel to change from one state to another (measured in ms).
BtW
Black-to-White (Response Rate Measurement):
How long it takes for the pixels to go from pure black to pure white and back to black again.
GtG
Gray-to-Gray (Response Rate Measurement):
How long it takes for pixels to go from one gray state to another (always faster than BtW time)
Manufacturers usually advertise GtG over BtW
Avg modern time: 5ms
Refresh Rate
How often the screen can change or update completely.
“Metronome/timer”
Regular standard: 60Hz
Gaming Monitors: 120Hz, 144Hz, 165Hz, 240Hz
Contrast Ratio
Lower Level Ratio
Good Ratio
High Level Ratio
The difference between the darkest and lightest spots that the monitor can display.
Lower Level: 250:1
Good: 450:1
High Level: 1000:1
Why old CRTs lingered in a few professions in 2000s
Early LCDs could not match the color saturation & contrast of CRT.
Dynamic Contrast Ratio
Difference between full-on (all white) vs. full-off (all black)
Doesn’t affect viewing on computer monitors
Focus on regular contrast ratio
Manufacturers like to advertise this number.
Color Depth
The amount of colors that can be displayed.
Old TN: 6-bit panel (64 variations per color channel)
Modern Monitors: 8-bit panel (256 variations per channel)
AKA: 24-bit color
High-End: 10-bit panel (1024 variations per channel)
= 1 billion + variations
Projectors (Function)
Generate an image in one device and use light to throw (project) it onto a screen.
Front-View Projectors
Shoot an image out the front and count on you to place a screen at the proper distance.
CRT (Projector)
Cathode Ray Tube Projector:
Beautiful images
Very expensive, large, and heavy (abandoned now)
LCD (Projector)
Much lighter and inexpensive compared to CRT.
DLP (Projector)
Digital Light Processing (Texas Instruments):
Uses a single processor and an array of tiny mirrors to project a front-view image.
Differs substantially from LCD:
Softer image, more electricity, and not as heavy
Lumens
Brightness measurement for projectors
The amount of energy given off by a light source form a certain angle that is perceived by the human eye.
Best rating depends on room size and lighting.
Small, Dark Room (Lumens Recommendation)
1000-1500 Lumens
Mid-sized, Typical Lighting (Lumens Recommendation)
2000+ Lumens
Large Rooms (Lumens Recommendation)
10,000+ Lumens (very expensive)
Throw
The size of an image at a certain distance from a screen.
Always in terms of distance required to project 100 inch diagonal screen.
Standard Throw
11-12 feet from projection surface.
Short-Throw
4 feet from projection surface.
Ultra-Short-Throw
15 inches from projection surface.
Lens prices go way up.
Lamps
The bane of every projector.
Generate tremendous amounts of light.
Generate lots of heat (fan needed to prevent overheating)
Fan runs until lamp is fully cooled (even after turned off)
Expensive to replace (at least a few hundred dollars)
Metal Halide (Lamp Technology)
Produce a tremendous amount of lumens with a small form factor.
Excessive heat & fan noise
Average life: ~3000 hours
LED (Lamp Technology)
Use red, green, and blue LEDs to provide light.
Don’t heat up; quieter/smaller fans.
Not nearly as many lumens as metal halide.
Requires a darker room.
Average life: 20,000+ hours
Lasers (Lamp Technology)
White lasers hitting color wheels.
OR
Colored lasers doing all the work.
Vibrant, high-contrast images
Very little heat
Average life: 30,000+ hours
Most expensive lamp tech
VR Headsets
Immersive 360-degree experience created by mounting two high-resolution screens into a headset that blocks external visual sensory input.
Use OLED technology.
OLED
Organic Light-Emitting Diode:
Use organic compounds between glass layers that light up when given an electrical charge.
No backlighting required (creates its own light)
Pixels can turn off completely, enabling pure black.
Results in phenomenal contrast compared to LCD panels.
VGA
15-pin, 3 row, D-type connector
d-shell, d-subminiature
DVI
Digital Visual Interface
DVI-D = Digital
DVI-A = Analog
DVI-I = Digital/Analog
Single-Link DVI
Max bandwidth of 165MHz
Limited to 1920 x 1080 at 60Hz
or
1280 x 1024 at 85Hz
Dual-Link DVI
Uses more pins than Single-Link to double throughput.
2048 x 1536 at 60Hz
HDMI
High Definition Multimedia Interface:
Carries both HD audio & video
Can handle just about any resolution monitor
Mini & Micro versions for smaller devices.
DisplayPort & Thunderbolt
Support full HD audio & video
mDP (miniDisplayPort) = Thunderbolt 1 & 2 connectors
HDBaseT
Enables long-range connectivity for uncompressed HD audio/video over a Cat 5a or Cat 6 network cable.
Monitor Adjustments
Brightness Contrast OSD (on-screen display) Physical screen adjustment Color adjustment (adjust RGB levels)
Monitor Adapter Types (4)
+
Alternative to Adapters
DVI-VGA | DVI-HDMI
Thunderbolt-DVI | Thunderbolt-HDMI
Alternatively: cables with different end connectors
VESA Mounts
A standardized bracket option for mounting to a wall or special stand.
VESA Standards
FDMI (Flat Display Mounting Interface)
MIS (VESA Mounting Interface Standard)
Curved panels do not have VESA mount options.
Display Adapters (Video Cards)
Processes data from CPU and outputs commands to the display.
Needs its own RAM (VRAM)
Needs fast connectivity between monitor, CPU, and system RAM
PCI
Peripheral Component Interconnect:
32-bit transfers at 33MHz
(132MBps max bandwidth)
Cannot handle current systems’ needs.
AGP
Accelerated Graphics Port:
Single, special port dedicated to video.
Only found on ancient systems.
Only 1 motherboard slot.
PCIe
Peripheral Component Interconnect Express:
Can take advantage of all 16 lanes
(8Gbps lanes)
Modern GPUs use this.
HDCP
High-bandwidth Digital Content Protection:
Stops audio & video copying between high-speed connections.
Stops playback of HDCP-encrypted content on devices.
GPU Manufacturers
NVIDIA, AMD, Intel
NVIDIA & AMD sell to third parties (ex: EVGA)
Intel mostly does integrated GPUs.
Video Memory (VRAM)
Hardest working set of electronics in a PC.
Constantly updates to reflect every change on screen.
Memory bus on card can be many times wider than 64-bit pathway, so data can be manipulated very quickly.
Can read/write data at the same time.
VRAM Bottlenecking (Cause & Solution)
Data throughput, access speed, and capacity limits reached.
Overcame by increasing the bus width.
Video Processor Chip
Handles rendering/processing of graphics.
VRAM Types
DDR3: Budget cards & laptop video cards GDDR3: Faster speeds & different cooling requirements GDDR4: Upgrade of GDDR3; faster clock GDDR5: Doubles I/O rate of GDDR4 GDDR5X GDDR6
HBM (High Bandwidth memory): Competitor to GDDR5
HBM2: Competitor to GDDR6
Onboard Video
Motherboard with built-in GPU
Integrated GPU
Separate chip attached to motherboard or built into northbridge chip.
APU
AMD Accelerated Processing Unit:
Integrates 2-4 CPU cores
Memory controller (supports DDR4 for system & cache)
GPU
Requires far less electricity than competitors
GPU Installation 3 Issues
Length of card
Proximity of nearest expansion card
(Leave room for fan ventilation space)
(Some cards are double-wide for air vents)
Presence of power connectors
Inverter Dangers
Powered by high-voltage electrical circuit
Charge remains after unplugged (wait a bit)
Gets very hot, can burn you.
Cleaning a Monitor
DO NOT use window cleaners (ammonia/liquid)
It can get into the monitor.
Use a microfiber cloth (anti-static monitor wipe)
