Display Devices Flashcards
What are some of the specifications used by display devices?
-Resolution
-aspect ratio
-response time
-viewing angles
-refresh rate
-brightness
-contrast ratio
-color depth
What are the benefits of a higher resolution?
Higher resolutions mean that there more pixels per inch (PPI), resulting in more pixel information and creating a high-quality, crisp image.
What is the refresh rate?
refers to how many times per second the display is able to draw a new image.
The number of bits used for each color component of a single pixel
Color depth
A measurement of an image’s sharpness and clarity. The more pixels that make up an image, the higher its resolution
Resolution
use a variety of technologies to produce visual information
Display devices
-display visual information.
-are the most common type of display device and range in size from less than an inch to over 10 feet.
-backlight the screen.
LCDs (liquid-crystal displays)
-displays use white LEDs along one edge (usually the top) of the LCD and a light diffuser to backlight the screen.
-least expensive, thinnest, and most widely used type of LCD.
Edge-Lit White LED
-have an array of white LEDs behind the screen.
-are able to dim specific regions of the screen, resulting in a much higher contrast ratio than LCDs that use EL-WLED technology.
Full-array WLED displays
-have an array of special LEDs that are able to emit red, green, and blue light, resulting in superior color accuracy.
-are the most expensive type of backlighting technology.
RGB-LED displays
Older LCD monitors and some LCD HDTVs use cold cathode fluorescent lamps (CCFLs) for backlighting. CCFLs are able to produce better colors than EL-WLED and full-array WLED technologies, but consume a lot more energy and require an internal inverter.
True or False
True
-are the most common technology used by LCDs.
-have very good response times (1–5 ms) and refresh rates (60–144 Hz), so are great for PC gaming.
TN (twisted nematic) panels
TN panels have imperfect color reproduction because only six bits per color can be displayed. They mimic true 24-bit color using dithering and other techniques.
TN panels have poor viewing angles and contrast ratios.
True or False
True
-have the best color reproduction quality and viewing angles among LCDs, making them well suited for graphic artists, designers, and photographers.
IPS (In-plane switching) panels
IPS panels have relatively slow response times (5–16 ms) and refresh rates (60 Hz) and have a slight purple tint when viewed from a wide angle.
High-end IPS LCDs are very expensive (over $1000).
True or False
True
Because of how they draw frames, LCDs suffer from motion blur when fast movements occur on the display. While motion blur can be reduced with higher refresh rates and lower response times, it can’t be eliminated entirely.
True or False
True
which devices use LCD screens
HDTVs
Computer displays
Tablets
Smart phones
Mobile devices
Wearable technology
Display devices that are called LED monitors or LED TVs are simply LCDs that use LED backlighting.
True or False
True
-use millions of small cells that contain electrically charged ionized gases.
-When electrical current is applied to a plasma cell, the gas within the cell forms a plasma and emits a photon of light.
-Each pixel in a plasma display is made up of a red, green, and blue cell.
-As with OLED monitors, plasma monitors don’t require a backlight.
Plasma
disadvantages:
-Plasma displays consume two to three times as much power as LCDs.
-They generate much more heat than other display types.
-The gasses inside the cells are sensitive to air pressure fluctuations.
-Plasma displays also suffer from a problem known as image retention (IR).
-Static images that are displayed for a long time cause the phosphors to overheat, which creates a temporary shadow of the image that is visible even when the display is turned off.
-If the static image was displayed for too long, screen burn-in can occur, and the shadow image will be permanent.
True or False
True
Plasma displays smaller than 32 inches are not sold because manufacturing them is not profitable.
True or False
True
use a thin layer of an organic compound (called an OLED) that lights up in response to an electrical current.
OLED displays
OLED displays are more efficient, offer a wider viewing angle, and provide faster response times (< 0.01 ms). However, they are costly to manufacture; OLEDs are the most expensive type of display device. In addition, the pixels in OLEDs (the organic compound) wears out faster than the pixels in LED or plasma displays.
OLEDs can be used in any device that uses a flat-panel display. And because of their size, OLEDs can even be used in textiles (clothing and upholstery).
Flexible materials can be used to create OLED screens, resulting in a bendable—sometimes even foldable—screen. These types of OLEDs are called FOLEDs (flexible OLEDs).
Facts
use a powerful light source (either an LED or laser diode) and a lens to project visual content onto a surface, which is typically a specialized screen.
Projectors
