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.
The idea for the original Eidophor was conceived in 1939 in Zürich by Swiss physicist Fritz Fischer, professor at the Labor für technische Physik of the Swiss Federal Institute of Technology, with the first prototype being unveiled in 1943. [1] A basic patent was filed on November 8, 1939, in Switzerland [2] and granted by the United States Patent and Trademark Office (patent no. 2,391,451) to Friederich Ernst Fischer for the Process and appliance for projecting television pictures on 25 December 1945. During the Second World War, Edgar Gretener worked together with Fischer at the Institute of Technical Physics to develop a prototype. When Gretener launched his own company Dr. Edgar Gretener AG in 1941 to develop enciphering equipment for the Swiss army, he stopped working on Eidophor. Hugo Thiemann took over this responsibility at the ETH. [3] After six years of work on this project at the ETH, Thiemann moved together with the project to the company Dr. Edgar Gretener AG, which was licensed by the ETH to further develop Eidophor, following Fischer's death in 1947. [3] An original August 1952 magazine article in the Radio and Television News [4] credits the development of the Eidophor to Edgar Gretener.
Following the Second World War, a first demonstration of an Eidophor system as a cinema video projector was organized in the Cinema Theater REX in Zürich to show successfully a TV broadcast in April 1958. [2] An even more promising perspective was the interest of Paramount Pictures [5] [6] and 20th Century Fox [7] which experimented with the concept of "theatre television", where television images would be broadcast onto cinema screens. [8] Over 100 cinemas were set up for the project, which failed because of financial losses and the refusal of the U.S. Federal Communications Commission (FCC) to grant theatre owners their own UHF bands for presentation. [9]
Eidophors used an optical system somewhat similar to a conventional movie projector, but substituted a slowly rotating mirrored disk or dish for the film. The disk was covered with a thin film of transparent high-viscosity oil, and through the use of a scanned electron beam, electrostatic charges could be deposited onto the oil, causing its surface to deform. Light was shined on the disc by a striped mirror consisting of strips of reflective material alternating with transparent non-reflective areas. Areas of the oil unaffected by the electron beam would allow the light to be reflected directly back to the mirror and towards the light source, whereas light passing through deformed areas would be displaced and would pass through the adjacent transparent areas and onwards through the projection system. As the disk rotated, a doctor blade discharged and smoothed the ripples in the oil, readying it for re-use on another television frame. [10]
The Eidophor was a large and cumbersome device. It required a setup crew of at least two engineers and three-phase AC power service. Often, contamination of the oil bath would cause visible artifacts to appear in the projected image. A rainbow-effect "eyebrow", or halo, surrounded the projected image.
It was not commonly used until there was a need for good-quality large-screen projection. This opportunity arose as part of the NASA space program, where the technology was deployed in mission control.
Eidophors were also used in stadiums by touring music groups for live event visual amplification.
Simple Eidophors produced black-and-white images. Later units used a color wheel (equivalent to the color television standard CBS tried to bring to the market against RCA/NBC's FCC-approved NTSC system, and today's DLP projection system) to produce red, green, and blue fields. The last models produced used separate red, green, and blue units in a single case. The Eidophor was 80 times brighter than CRT projectors of the time. The last Eidophors were able to project colour images of up to 18 metres in width.
Advances in projection television technology in the 1990s brought about the end of the Eidophor. An early prototype of a new type of projector with limited resolution using a passive matrix-addressed liquid-crystal display was shown at a conference in San Francisco by Swiss engineer Peter J. Wild already in 1972. [11] The new devices, using active matrix addressing of LCDs were smaller and cheaper. While their projected images were not nearly as bright as those produced by the Eidophor, they were far more economical to use. Current technologies include liquid-crystal display (LCD) and digital light processing (DLP) projectors, both of which produce superior results from easily portable devices.
Digital cinema refers to the adoption of digital technology within the film industry to distribute or project motion pictures as opposed to the historical use of reels of motion picture film, such as 35 mm film. Whereas film reels have to be shipped to movie theaters, a digital movie can be distributed to cinemas in a number of ways: over the Internet or dedicated satellite links, or by sending hard drives or optical discs such as Blu-ray discs.
A home cinema, also called a home theater or theater room, is a home entertainment audio-visual system that seeks to reproduce a movie theater experience and mood using consumer electronics-grade video and audio equipment and is set up in a room or backyard of a private home. Some studies show that films are rated better and generate more intense emotions when watched in a movie theater, but convenience is a major appeal for home cinemas. In the 1980s, home cinemas typically consisted of a movie pre-recorded on a LaserDisc or VHS tape; a LaserDisc Player or VCR; and a heavy, bulky large-screen cathode ray tube TV set, although sometimes CRT projectors were used instead. In the 2000s, technological innovations in sound systems, video player equipment and TV screens and video projectors have changed the equipment used in home cinema set-ups and enabled home users to experience a higher-resolution screen image, improved sound quality and components that offer users more options. The development of Internet-based subscription services means that 2020s-era home theatre users do not have to commute to a video rental store as was common in the 1980s and 1990s.
An overhead projector, like a film or slide projector, uses light to project an enlarged image on a screen, allowing the view of a small document or picture to be shared with a large audience.
An LCD projector is a type of video projector for displaying video, images or computer data on a screen or other flat surface. It is a modern equivalent of the slide projector or overhead projector. To display images, LCD projectors typically send light from a metal-halide lamp through a prism or series of dichroic filters that separates light to three polysilicon panels – one each for the red, green and blue components of the video signal. As polarized light passes through the panels, individual pixels can be opened to allow light to pass or closed to block the light. The combination of open and closed pixels can produce a wide range of colors and shades in the projected image.
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 remote fiber-optic RGB 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.
A handheld projector 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.
An active shutter 3D system is a technique of displaying stereoscopic 3D images. It works by only presenting the image intended for the left eye while blocking the right eye's view, then presenting the right-eye image while blocking the left eye, and repeating this so rapidly that the interruptions do not interfere with the perceived fusion of the two images into a single 3D image.
Fulldome refers to immersive dome-based video display environments. The dome, horizontal or tilted, is filled with real-time (interactive) or pre-rendered (linear) computer animations, live capture images, or composited environments.
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).
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.
Rear-projection television (RPTV) is a type of large-screen television display technology. Until approximately 2006, most of the relatively affordable consumer large screen TVs up to 100 in (250 cm) used rear-projection technology. A variation is a video projector, using similar technology, which projects onto a screen.
Fritz Fischer was a technical physicist, engineer and inventor. He was married to Maud Schätti.
The digital micromirror device, or DMD, is the microoptoelectromechanical system (MOEMS) that is the core of the trademarked Digital Light Processing (DLP) projection technology from Texas Instruments (TI). Texas Instrument's DMD was created by solid-state physicist and TI Fellow Emeritus Dr. Larry Hornbeck in 1987. However, the technology goes back to 1973 with Harvey C. Nathanson's use of millions of microscopically small moving mirrors to create a video display of the type now found in digital projectors.
A holographic screen is a two-dimensional display technology that uses coated glass media for the projection surface of a video projector. "Holographic" refers not to a stereoscopic effect, but to the coating that bundles light using formed microlenses. The lens design and attributes match the holographic area. The lenses may appear similar to the Fresnel lenses used in overhead projectors. The resulting effect is that of a free-space display, because the image carrier appears very transparent. Additionally, the beam manipulation by the lenses can be used to make the image appear to be floating in front of or behind the glass, rather than directly on it. However, this display is only two-dimensional and not true three-dimensional. It is unclear if such a technology will be able to provide acceptable three-dimensional images in the future.
Edgar Gretener was a Swiss electrical engineer.
Hugo Thiemann was a Swiss R&D manager and visionary. He was a founding member of the Club of Rome.
Enter is a museum for computer and consumer electronics in the Swiss town of Solothurn. Now a non-profit foundation, it originated as the project of Swiss entrepreneur Felix Kunz. It is the largest private technology collection open to the public in Switzerland. Its current location in Solothurn opened in 2011.
Peter J. Wild is a Swiss electronics engineer and a pioneer of liquid-crystal display (LCD) technology.