Chapter 8.1 Display Technologies

Transmissive

A backlight behind the panel shines light toward the user, making the display readable in low light situations. One drawback is that these LCDs used in bright ambient light must have very powerful backlights.

Plasma

A flat panel screen that uses small cells filled with noble gases and phosphors to create color. An electrical current is applied to the gas to ionize it into a charged plasma, and each cell illuminates a pixel on the screen.

active-matrix (thin film transistor [TFT])

A form of LCD display in which electric current drives the display by charging each pixel individually as needed. Active matrix displays are more expensive, but improved response time and image quality has made them the dominant display technology for PCs and mobile devices.

Reflective

A mirror behind the panel bounces ambient light back to the user. Reflective displays are cheap and power-efficient, but difficult or impossible to read without ample ambient light.

what are the there main advantages of LCD over DLP projectors

Colors are more accurate. This is due to a clear section into the DLP color wheel. It boosts brightness, but reduces color saturation. Slightly sharper images than the DLP at the same resolution. Produces a brighter image than DLP using the same wattage lamp.

organic light-emitting diode (OLED)

Display is a flat panel screen that uses an organic substance as the semiconductor material in LEDs. Unlike LED, which uses an array of individual LED bulbs, ____ uses a series of thin, light emitting films.

IN-Plane Switching (IPS)

Displays use crystals which are horizontally aligned with the screen rather than vertically as in the TN LCD. This allows the polarized crystals to move more freely into the desired alignment. Advantages: Include the best viewing angles of all the LCD display technologies and the ability to produce the most accurate colors. Disadvantages include increased power consumption and slower response time.

What are the three ways of illuminating an LCD screen

Reflective Transmissive Transflective

what are the there main advantages of DLP over LCS projectors

Smaller and more portable due to the use of the mirror chip instead of panels. Produces deeper blacks than LCD, giving them a higher contrast. Less pixelation, allowing for smoother motion graphics. Higher reliability due to fewer moving parts.

What are the 4 primary layers of OLED display levels ?

The substrate, which acts as the structural framework. Red, green, and blue tinted plastic layers are added to the substrate to produce color. The anode, which draws electrons. The cathode, which provides electrons. The organic layer, which contains two sublayers: a conducting layer (in which the electrons move) and an emissive layer (which produces light).

Passive Matrix

Uses a grid of horizontal and vertical wires with an LCD element at each intersection. Each LCD element is a single pixel on the display screen. As current is sent through the LCD element, the liquid crystals at that location twist or straighten, allowing light to pass through or blocking it. Today they're primarily manufactured for small devices and industrial applications where their disadvantages aren't a drawback.

Transflective

Uses both a backlight and a partially reflective layer between the backlight and the LCD display to capture ambient light. This allows them to operate efficiently under a wide range of lighting conditions. these LCDs tend to be more expensive.

LCD (liquid crystal display)

a flat panel screen that uses a liquid crystal solution sandwiched between two polarizing filters and glass panels. LCD screens are the most common displays used in external display devices and laptop computers.

CRT (cathode ray tube)

display contains a large vacuum tube with a flat end covered in phosphors. An emitter in the back shoots a stream of electrons at the phosphors to create an image

Vertical Alignment (VA)

displays have crystals which are vertically aligned when there is no electrical current and horizontally aligned when current is applied. The former blocks light, producing a black image; the latter allows light from the backlight to pass through, producing a white image. Typically more expensive with slower response time that TN or IPS

Twisted Nematic (TN)

displays use nematic liquid crystal in a perpendicular orientation confined between two plates of polarized glass. Is the most common and oldest LCD panel type. Advantages include shortest response time, low power draw, high brightness when combined with LED backlighting, and low manufacturing cost. The chief disadvantage of this panel is a very narrow viewing angle; the colors distort as you view the screen from the side and from above.

Screen Inverter

takes DC from the motherboard and converts it into AC for the backlighting. Found in devices like Laptops