Display

OLED: An organic light emitting diode display

- flat panel screen that uses an organic substance as the semiconductor material in LEDs. An OLED display has four primary layers: 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). - OLED displays are becoming more common in laptop computers. OLED display include the best picture quality of any display technology due to its ability to produce deep, dark blacks. They have a wide 160-degree viewing angle, a very high contrast ratio of 1.000.000:1, and quick response time. It's important to note that OLED displays can be slightly curved at the sides. However, they are expensive compared to LCD displays. They also have a problem with the material used to produce the color blue. It degrades at a much faster rate than the material for the other colors. This eventually affects the display's color balance and reduces its overall brightness. OLED doesn't require backlighting to be seen in low-light conditions. They aren't as bright as backlit LCDs, but because they don't need backlighting, they can be thinner and lighter than their LCD counterparts.

LCD (liquid crystal display) monitor

- uses a liquid crystal solution sandwiched between two polarizing filters and glass panels. - polarized using an electrical current, which straightens and twists them to achieve the desired color. -In an LCD display, liquid crystal molecules independently being rapidly pulsed on and off at different rates of power to create various shades of red, green or blue for each pixel. -LCD screens are the most common displays used in external display devices and laptop computers.

Connecting external displays

1. Examine your display connections, and determine which one you will use. 2. Digital connections are preferred over analog. Remember that VGA connections are not designed to be hot-swappable. You should power down your computer before connecting a VGA monitor. If there is an onboard video port and a video expansion card, verify the one you won't use is disabled in the BIOS/UEFI, or that the motherboard is configured to autodetect which you are using. 3. Attach the display data cable to the back of the monitor. 4. If necessary, attach an adapter to the computer end of the display data cable. For example, if your display device has a DVI connection and your computer has a VGA connection, you would attach a DVI to VGA adapter to the computer end of the DVI cable. 5. Attach the display data cable to the computer's video port. 6. Plug the power cable into the back of the monitor, then into the wall outlet. 7. Install any software or drivers that came with the display device. Software and drivers provided by the display manufacturer will give you more features than the generic PnP display driver installed with Windows. 8. Use Control Panel, PC Settings, or the driver software to make any desired display setting changes for the external display device.

Connecting multiple displays

1. Identify the video port you will use on the computer, laptop, or mobile device.On a PC, you will need a second video port, or a video port that supports multiple chained displays. For PCs, if you are currently using a graphics expansion card and want to use the onboard video port for your second monitor, verify the onboard port is enabled in the BIOS/UEFI. Attach the display data cable to the back of the monitor. If necessary, attach an adapter to the computer end of the display data cable.For example, if your display device has a DVI connection and your computer has a VGA connection, you would attach a DVI to VGA adapter to the computer end of the DVI cable. Attach the display data cable to the computer's video port. Plug the power cable into the back of the monitor, then the wall outlet. Install any software or drivers that came with the display device. If you connected an external display device to a laptop, you scroll through which screen(s) display data by pressing the FN key + the appropriate F# key.The appropriate F# key typically has a picture of a laptop and a box behind it to indicate a second display.

Transmissive LCD

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

Display projectors

A display projector is a specialized computer display that projects an enlarged image on a large surface such as a wall, whiteboard, or movie screen. Two important projector technologies include LCD and DLP.

Reflective LCD

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. They're also more difficult to achieve with TFT displays, so reflective displays are generally passive matrix with all their drawbacks.

A related technology to VR is augmented reality (AR.)

AR displays allow you to perceive your surroundings normally, but augment it with images, sounds, or other sensory information provided by the computer. For example, an AR display can superimpose text and visual indicators related to what you're seeing, such as showing patient monitoring data to a surgeon, or overlaying a blueprint-based model onto a construction site as a worker walks through it. Since AR displays must show the real world in accurate alignment with augmented elements, they can be more complex to design than VR displays, or have more demanding requirements for motion and positioning tracking. AR headsets may process input from eternal cameras, while AR glasses and head-up displays project augmented elements into a natural field of view. Even AR contact lenses are currently in development.

In Windows 7 and Windows 8, display settings are in

Control Panel > Appearance and Personalization > Display.

Resolution

Display resolution is the number of pixels (individual points of light or color) displayed on a screen. The measurement is documented as horizontal pixels x vertical pixels.The size of your display and the resolution determine how sharp an image appears to the human eye. For example, an image on a 14" monitor with a 1600 × 1200 resolution appears sharper than it does at the same resolution on a 19" monitor, since it has a higher pixel density. Pixel density is often expressed as pixels per inch (ppi) in a display's statistics. Higher resolution provides more image detail, while high pixel density provides a sharper image. However, it's important to note that setting a higher resolution could make the image too small to view comfortably, depending on the software you're using and content you're viewing.

Filters

Filters are attached or applied to the surface of a display to reduce glare on a glass screen from external light sources. They can be permanently installed as part of the display screen or purchased as an accessory to be added. Filters also reduce the viewing angle of the display. While you might think of this as a disadvantage, it can be a benefit. It decreases people's ability to surreptitiously view the display from the side, increasing privacy in the work environment. Privacy filters are especially useful where unauthorized people may be near displays used to view sensitive information, such as at the counter of a doctor's office.

LCD projector

LCD is an older technology that uses mirrors and prisms to direct light through LCD panels and towards the projector's lens. Lamplight is projected through mirrors and prisms which split the light up into the primary colors of red, green, and blue. The three colors then are projected back through three glass LCD panels, each holding one color channel of the image. Like other LCD panels, individual pixels can allow or block light, creating three monochrome images. The separate colors are then converged using another prism, sent to the projector's lens, and the image is displayed onto the projection surface. LCD display projectors three main advantages over DLP projectors. 1. Colors are more accurate. This is due to a clear section into the DLP color wheel. It boosts brightness, but reduces color saturation. 2. Slightly sharper images than the DLP at the same resolution. 3. Produces a brighter image than DLP using the same wattage lamp.

LCD backlighting

LCD technologies work by blocking light rather than by emitting it. - While an LCD panel consumes less power than an OLED or plasma display, that also means it is only visible with a light source. There are three ways of illuminating an LCD panel. Reflective, Transmissive, Transflective

LCD matrix technologies

LCDs use one of two technologies to polarize the liquid crystals: a passive or active matrix.

Analog or digital connection

Most current external display devices have both digital and analog connection interfaces. If possible, use a digital connection, such as DVI, HDMI, or DisplayPort.

Native resolution

Native resolution is the resolution that gives the best image quality on an LCD. LCD displays are unable to perform the calculations to resize an image from one resolution to another without affecting image quality. This is especially noticeable in resolutions that aren't multiples of one another.For example, if the video card sends an image signal in 1366 × 768 resolution and the native resolution of the LCD is 1920 × 1080, there isn't a one-to-one mapping of pixels. You'll notice the image distorts and quality suffers. Depending on the display, the quality difference might be minor or major. The other way around is even worse; displaying a 1920 × 1080 image on a 1366 × 768 display will either be impossible, or result in downscaling that causes fine details of the image to be lost or blurry. If you have an LCD display, you'll want to use its native resolution, or in some cases an even multiple of its native resolution.

In Windows 10, display settings are in

Settings > System > Display.

Refresh rate

The refresh rate is a measurement of how often the display image is updated per second. It is expressed in hertz (Hz). Common display device refresh rates range from 60 to 144 Hz. As the refresh rate increases, it decreases how much the human eye can notice the image being redrawn on the screen (called flicker). Flicker is particularly a problem for old CRT devices, so refresh rate is most important when you use those displays.The refresh rate is actually controlled by the computer's video card, not the display device. However, the rate you choose must be supported by both the video card and the display device. If you select a refresh rate that isn't supported by the display, the screen will go blank or distort the image.The maximum refresh rate you can choose is also affected by the display's resolution. Lower resolutions (for example, 800 × 600) support higher refresh rates than higher resolutions (for example, 1600 × 1200).

Transflective LCD

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. Transflective LCDs tend to be more expensive.

VR headsets

Virtual reality systems providing immersive 3D multi-sensory experiences have existed for a long time, but they're enjoying a new surge of popularity as PC and smartphone displays. A modern VR headset for a PC, such as the Oculus Rift, is a display containing stereoscopic displays, one for each eye, along with stereo output. Critically, a VR headset has some sort of motion tracking, allowing the wearer to look around within the virtual environment. This is typically accomplished by means of internal gyroscopes and accelerometers, and may include more advanced features such as eye tracking sensors. Applications for virtual reality include gaming, simulations, and training.

CRT: A 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. Due to their bulk and expense, CRTs were displaced entirely by flat panel technologies, and you'll only see them on old computers today.

Plasma Display Panel

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. Plasma screens were primarily used for large televisions in the late 1990s and early 2000s, but they've largely been replaced by LCDs. A plasma display panel displays bright images and uses a wide color range. The panels are available in 30 inches or larger sizes.A plasma display contains a neon/xenon gas mixture sealed between two glass plates. Within the plates is a grid of cells in which the gas mixture is charged. When the charged gas breaks down, it produces ionized plasma. This in turn emits UV radiation. The UV radiation activates color phosphors to produce red, green, or blue subpixels. Varying gas/phosphor reactions make it possible for a plasma display to produce over 16 million different colors. Plasma displays have a wide 160-degree viewing angle and are free of distortion at the edges of the screen. They are better at displaying motion graphics without blur. However, they are not as bright as other display technologies and consume more power. These features made them popular for home theater systems in the past, but maturing LCD technologies displaced them.

When comparing display devices

here are various features you should take into account: Analog or digital connection Aspect ratio Brightness Filters Refresh rate Resolution

Brightness

is a measurement of the intensity of the energy output of a visible light source with pure white having the maximum brightness and pure black the minimum brightness. In a computer display, optimal screen brightness varies based on the amount of ambient light. Setting the screen brightness to a high-level is useful only when you are viewing the screen under high ambient lighting. High brightness drains the battery power on a laptop quickly, which is why most laptops have a power setting that dims the display automatically when on battery power. For a projector, "brightness" has the additional meaning of total light output, measured in lumens. A brighter projector can create a larger image, or one which is visible in a brighter room. For a home theater projector used in a darkened living room, 1000-2000 lumens might be sufficient, while for a conference room or lecture hall with more ambient light you might need 3000-5000 lumens. Brighter projectors are more expensive, consume more power, and produce more waste heat.

Aspect ratio

is the measurement describing the width and height ratio of an image on the screen, expressed in width:height format. For example, "wide-screen" HDTV uses a 16:9 aspect ratio, so an HDTV screen is 16 units wide and 9 units tall, or almost twice as wide as it is long.

In an active matrix, or thin film transistor (TFT) LCD

there is a transistor at each intersection which controls the light for each pixel. Transistors require less electrical current to control the pixels, allowing the current to be switched on and off more frequently, thus improving screen refresh time. 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.

Passive matrix LCD

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. Passive matrix displays were used by early LCDs due to ease of manufacture, but had slow refresh times, low contrast, and poor support for high resolutions. Today they're primarily manufactured for small devices and industrial applications where their disadvantages aren't a drawback.

Digital Light Processing (DLP) projector

uses a single chip with a reflective surface composed of thousands of tiny mirrors corresponding to individual pixels. The mirrors move back and forth, varying the amount of light that is projected from each pixel towards the projector's lens. The DLP projects colors by passing the light from the lamp through a rotating wheel with red, green, and blue filters. DLP display projectors advantages: 1. Smaller and more portable due to the use of the mirror chip instead of panels. 2. Produces deeper blacks than LCD, giving them a higher contrast. 3. Less pixelation, allowing for smoother motion graphics. 4. Higher reliability due to fewer moving parts.