Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, phase and frequency of an analog signal.
A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms on an oscilloscope, a frame of video on an analog television set (TV), digital raster graphics on a computer monitor, or other phenomena like radar targets. A CRT in a TV is commonly called a picture tube. CRTs have also been used as memory devices, in which case the screen is not intended to be visible to an observer. The term cathode ray was used to describe electron beams when they were first discovered, before it was understood that what was emitted from the cathode was a beam of electrons.
Liquid crystal on silicon is a miniaturized reflective active-matrix liquid-crystal display or "microdisplay" using a liquid crystal layer on top of a silicon backplane. It is also known as a spatial light modulator. LCoS initially was developed for projection televisions, but has since found additional uses in wavelength selective switching, structured illumination, near-eye displays and optical pulse shaping.
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, 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.
Digital Light Processing (DLP) is a set of chipsets based on optical micro-electro-mechanical technology that uses a digital micromirror device. It was originally developed in 1987 by Larry Hornbeck of Texas Instruments. While the DLP imaging device was invented by Texas Instruments, the first DLP-based projector was introduced by Digital Projection Ltd in 1997. Digital Projection and Texas Instruments were both awarded Emmy Awards in 1998 for the DLP projector technology. DLP is used in a variety of display applications from traditional static displays to interactive displays and also non-traditional embedded applications including medical, security, and industrial uses.
A television set or television receiver is an electronic device for the purpose of viewing and hearing television broadcasts, or as a computer monitor. It combines a tuner, display, and loudspeakers. Introduced in the late 1920s in mechanical form, television sets became a popular consumer product after World War II in electronic form, using cathode ray tube (CRT) technology. The addition of color to broadcast television after 1953 further increased the popularity of television sets in the 1960s, and an outdoor antenna became a common feature of suburban homes. The ubiquitous television set became the display device for the first recorded media for consumer use in the 1970s, such as Betamax, VHS; these were later succeeded by DVD. It has been used as a display device since the first generation of home computers and dedicated video game consoles in the 1980s. By the early 2010s, flat-panel television incorporating liquid-crystal display (LCD) technology, especially LED-backlit LCD technology, largely replaced CRT and other display technologies. Modern flat panel TVs are typically capable of high-definition display and can also play content from a USB device. Starting in the late 2010s, most flat panel TVs began to offer 4K and 8K resolutions.
The lumen is the unit of luminous flux, a measure of the perceived power of visible light emitted by a source, in the International System of Units (SI). Luminous flux differs from power in that radiant flux includes all electromagnetic waves emitted, while luminous flux is weighted according to a model of the human eye's sensitivity to various wavelengths; this weighting is standardized by the CIE and ISO. One lux is one lumen per square metre.
Hydrargyrum medium-arc iodide (HMI) is the trademark name of Osram's brand of metal-halide gas discharge medium arc-length lamp, made specifically for film and entertainment applications. Hydrargyrum comes from the Greek name for the element mercury.
A xenon arc lamp is a highly specialized type of gas discharge lamp, an electric light that produces light by passing electricity through ionized xenon gas at high pressure. It produces a bright white light to simulate sunlight, with applications in movie projectors in theaters, in searchlights, and for specialized uses in industry and research. For instance, Xenon arc lamps with mercury lamps are the two most common lamps used in wide-field fluorescence microscopes.
An Eidophor was a video projector used to create theater-sized images from an analog video signal. The name Eidophor is derived from the Greek word-roots eido and phor meaning 'image' and 'bearer' (carrier). Its basic technology was the use of electrostatic charges to deform an oil surface.
A CRT projector is a video projector that uses a small, high-brightness cathode ray tube (CRT) as the image generating element. The image is then focused and enlarged onto a screen using a lens kept in front of the CRT face. The first color CRT projectors came out in the early 1950s. Most modern CRT projectors are color and have three separate CRTs, and their own lenses to achieve color images. The red, green and blue portions of the incoming video signal are processed and sent to the respective CRTs whose images are focused by their lenses to achieve the overall picture on the screen. Various designs have made it to production, including the "direct" CRT-lens design, and the Schmidt CRT, which employed a phosphor screen that illuminates a perforated spherical mirror, all within an evacuated cathode ray tube.
The penetron, short for penetration tube, is a type of limited-color television used in some military applications. Unlike a conventional color television, the penetron produces a limited color gamut, typically two colors and their combination. Penetrons, and other military-only cathode ray tubes (CRTs), have been replaced by LCDs in modern designs.
A raster scan, or raster scanning, is the rectangular pattern of image capture and reconstruction in television. By analogy, the term is used for raster graphics, the pattern of image storage and transmission used in most computer bitmap image systems. The word raster comes from the Latin word rastrum, which is derived from radere ; see also rastrum, an instrument for drawing musical staff lines. The pattern left by the lines of a rake, when drawn straight, resembles the parallel lines of a raster: this line-by-line scanning is what creates a raster. It is a systematic process of covering the area progressively, one line at a time. Although often a great deal faster, it is similar in the most general sense to how one's gaze travels when one reads lines of text.
Laser color television, or laser color video display, is a type of television that utilizes two or more individually modulated optical (laser) rays of different colors to produce a combined spot that is scanned and projected across the image plane by a polygon-mirror system or less effectively by optoelectronic means to produce a color-television display. The systems work either by scanning the entire picture a dot at a time and modulating the laser directly at high frequency, much like the electron beams in a cathode ray tube, or by optically spreading and then modulating the laser and scanning a line at a time, the line itself being modulated in much the same way as with digital light processing (DLP).
A multifaceted reflector light bulb is a reflector housing format for halogen as well as some LED and fluorescent lamps. MR lamps were originally designed for use in slide projectors, but see use in residential lighting and retail lighting as well. They are suited to applications that require directional lighting such as track lighting, recessed ceiling lights, desk lamps, pendant fixtures, landscape lighting, retail display lighting, and bicycle headlights. MR lamps are designated by symbols such as MR16 where the diameter is represented by numerals indicating units of eighths of an inch. Common sizes for general lighting are MR16 and MR11, with MR20 and MR8 used in specialty applications. Many run on low voltage rather than mains voltage alternating current so require a power supply.
Large-screen television technology developed rapidly in the late 1990s and 2000s. Prior to the development of thin-screen technologies, rear-projection television was standard for larger displays, and jumbotron, a non-projection video display technology, was used at stadiums and concerts. Various thin-screen technologies are being developed, but only liquid crystal display (LCD), plasma display (PDP) and Digital Light Processing (DLP) have been publicly released. Recent technologies like organic light-emitting diode (OLED) as well as not-yet-released technologies like surface-conduction electron-emitter display (SED) or field emission display (FED) are in development to supersede earlier flat-screen technologies in picture quality.
A vector monitor, vector display, or calligraphic display is a display device used for computer graphics up through the 1970s. It is a type of CRT, similar to that of an early oscilloscope. In a vector display, the image is composed of drawn lines rather than a grid of glowing pixels as in raster graphics. The electron beam follows an arbitrary path, tracing the connected sloped lines rather than following the same horizontal raster path for all images. The beam skips over dark areas of the image without visiting their points.
Laser-powered phosphor display (LPD) is a large-format display technology similar to the cathode ray tube (CRT). Prysm, Inc., a video wall designer and manufacturer in Silicon Valley, California, invented and patented the LPD technology. The key components of the LPD technology are its TD2 tiles, its image processor, and its backing frame that supports LPD tile arrays. The company unveiled the LPD in January 2010.
A deflection yoke is a kind of magnetic lens, used in cathode ray tubes to scan the electron beam both vertically and horizontally over the whole screen.
