LED in the context of "Quartz crisis"

A projector or image projector is an optical device that projects an image (or moving images) onto a surface, commonly a projection screen. Most projectors create an image by shining a light through a small transparent lens, but some newer types of projectors can project the image directly, by using lasers. A virtual retinal display, or retinal projector, is a projector that projects an image directly on the retina instead of using an external projection screen.

The most common type of projector used today is called a video projector. Video projectors are digital replacements for earlier types of projectors such as slide projectors and overhead projectors. These earlier types of projectors were mostly replaced with digital video projectors throughout the 1990s and early 2000s, but old analog projectors are still used at some places. The newest types of projectors are handheld projectors that use lasers or LEDs to project images.

A display device is an output device for presentation of information in visual or tactile form (the latter used for example in tactile electronic displays for blind people). When the input information that is supplied has an electrical signal the display is called an electronic display.

Common applications for electronic visual displays are television sets or computer monitors.

A light fixture (US English), light fitting (UK English) or luminaire is an electrical lighting device containing one or more light sources, such as lamps and all the accessory components required for its operation to provide illumination to the environment. All light fixtures have a fixture body and one or more lamps. The lamps may be in sockets for easy replacement—or, in the case of some LED fixtures, hard-wired in place.

Fixtures may also have a switch to control the light, either attached to the lamp body or attached to the power cable. Permanent light fixtures, such as dining room chandeliers, may have no switch on the fixture itself, but rely on a wall switch.

Wafer fabrication is a procedure composed of many repeated sequential processes to produce complete electrical or photonic circuits on semiconductor wafers in a semiconductor device fabrication process. Examples include production of radio frequency (RF) amplifiers, LEDs, optical computer components, and microprocessors for computers. Wafer fabrication is used to build components with the necessary electrical structures.

The main process begins with integrated circuit design, where electrical engineers designing the circuit and defining its functions, and specifying the signals, inputs/outputs and voltages needed. These electrical circuit specifications are entered into electrical circuit design software, such as SPICE, and then imported into circuit layout programs, which are similar to ones used for computer aided design. This is necessary for the layers to be defined for photomask production. The resolution of the circuits increases rapidly with each step in design, as the scale of the circuits at the start of the design process is already being measured in fractions of micrometers. Each step thus increases circuit density for a given area.

A video projector is an image projector that receives a video signal and projects the corresponding image onto a projection screen using a lens system. Video projectors use a very bright ultra-high-performance lamp (a special mercury arc lamp), Xenon arc lamp, metal halide lamp, LED or solid state blue, RB, RGB or fiber-optic lasers to provide the illumination required to project the image. Most modern projectors can correct any curves, blurriness and other inconsistencies through manual settings.

Video projectors are used for many applications such as conference room presentations, classroom training, home cinema, movie theaters, and concerts, having mostly replaced overhead, slide and conventional film projectors. In schools and other educational settings, they are sometimes connected to an interactive whiteboard. In the late 20th century, they became commonplace in home cinema. Although large LCD television screens became quite popular, video projectors are still common among many home theater enthusiasts. In some applications, video projectors have been replaced with large monitors or LED screens, or their replacement has been explored.

A handheld projector (also known as a pocket projector, mobile projector, pico projector or mini beamer) is an image projector in a handheld device. It was developed as a computer display device for compact portable devices such as mobile phones, personal digital assistants, and digital cameras, which have sufficient storage capacity to handle presentation materials but are too small to accommodate a display screen that an audience can see easily. Handheld projectors involve miniaturized hardware, and software that can project digital images onto a nearby viewing surface.

The system comprises five main parts: the battery, the electronics, the laser or LED light sources, the combiner optic, and in some cases, scanning micromirror devices. First, the electronics system turns the image into an electronic signal. Next, the electronic signals drive laser or LED light sources with different colors and intensities down different paths. In the combiner optic, the different light paths are combined into one path, defining a palette of colors. An important design characteristic of a handheld projector is the ability to project a clear image on various viewing surfaces.

An LED-backlit LCD is a liquid-crystal display that uses LEDs for backlighting instead of traditional cold cathode fluorescent (CCFL) backlighting. LED-backlit displays use the same TFT LCD (thin-film-transistor liquid-crystal display) technologies as CCFL-backlit LCDs, but offer a variety of advantages over them.

Televisions that use a combination of an LED backlight with an LCD panel are sometimes advertised as LED TVs, although they are not truly LED displays.

An organic light-emitting diode (OLED), also known as organic electroluminescent (organic EL) diode, is a type of light-emitting diode (LED) in which the emissive electroluminescent layer is an organic compound film that emits light in response to an electric current. This organic layer is situated between two electrodes; typically, at least one of these electrodes is transparent. OLEDs are used to create digital displays in devices such as television screens, computer monitors, and portable systems such as smartphones and handheld game consoles. A major area of research is the development of white OLED devices for use in solid-state lighting applications.

There are two main families of OLED: those based on small molecules and those employing polymers. Adding mobile ions to an OLED creates a light-emitting electrochemical cell (LEC) which has a slightly different mode of operation. An OLED display can be driven with a passive-matrix (PMOLED) or active-matrix (AMOLED) control scheme. In the PMOLED scheme, each row and line in the display is controlled sequentially, one by one, whereas AMOLED control uses a thin-film transistor (TFT) backplane to directly access and switch each individual pixel on or off, allowing for higher resolution and larger display sizes. OLEDs are fundamentally different from LEDs, which are based on a p–n diode crystalline solid structure. In LEDs, doping is used to create p- and n-regions by changing the conductivity of the host semiconductor. OLEDs do not employ a crystalline p-n structure. Doping of OLEDs is used to increase radiative efficiency by direct modification of the quantum-mechanical optical recombination rate. Doping is additionally used to determine the wavelength of photon emission.