Projectors and projection TVs

  • History or how it all began
  • The history and creation of the first projection televisions originates a very long time, since the beginning of the 20th century. First black-and-white TV, in fact, was "projection", here they are:

    First projection TVs

    So, just before, as You may remember from the history of television tubes, their length was quite big, so that the televisions not occupied they are on the floor, the picture tubes in them mounted vertically, and watched them through the reflection in the mirror, mounted in the upper hinged lid ab

    Of course, you say, in this case, if you watch any TV in the mirror, he immediately becomes a projection? ag However, that's the way it is bs All CRT TVs, in fact, are a projection, because an electron beam draw us a picture on the screen (the CRT), but let's go ahead and look at the first projection TVs made in the USSR. They were not commercially available, they were made in small batches to-order associations with 1951 of the year. Before You later "Moscow" and "Topaz" (1957-1961)

    First projector

    These "tables", measuring about 1x0. 5x0. 5 m, collected in wooden buildings, had a weight of about 70kg and has been designed for simultaneous viewing of 25-30 spectators. In addition to receiving television programming, they could receive the program or to spin, had a weak sound system (6 speakers and a wired remote control

    Projection television screen

    For maximum brightness, proektsionnyi was equipped with aluminum reflecting screen in a frame with size: 1045х1345х70 mm (1300х1060х130 mm) with two folding supports, which were installed 2.5 meters from the TV and weighed about 30 kg. the installation uses a CRT 6ЛК1(B) with the optical-mechanical system to project the image on the screen as, in no way inferior to the quality of conventional CRT televisions of the time. Here is a view from inside:

    Diagram of the projection TV

    In the Soviet Union were also released two models of the color projection television "Izumrud-201" and "Izumrud-203" (1959), however, they have not found wide application. The image they formed three different tubes (each given its own color), and optical-mechanical system used to drive the reflecting screen three images into one (full color). The model 201 was as large as her black-and-white "brothers" (about 80 kg), but the "Izumrud-203 was an outdoor projection television personal use

    Home projection television

    The operation of the circuit provided 36 of tubes 22 and a semiconductor diode, and the dimensions of the image on a reflective screen: 350х460 mm (approximately 580 mm in diameter or 23 inches). This, unfortunately, is all, but abroad - projection technology continued and continues to evolve

  • Svetoslavsky projector
  • Svetalana projection device an oil film (with defined optical and electrical characteristics), the modulated electron beam ("Eidophor") - also deserve attention, because this system allowed to obtain an image size of dozens of square meters. The working principle of svetalana device consisted of the following: the light from a powerful source with lens optics 1 to ensure the uniformity of the stream falls on the slit mirror 2 and they reflected on the spherical mirror 6 covered with a film of oil 7. The mirror is oriented in such a way that when a smooth film, the light reflected is returned in the direction of the source and the screen 4 remains unexposed dq

    Svetalana device

    The deformation of the film at any point causing a deviation of the reflected beam from it, which, passing through a crack in the mirror 2, falls through the projection optics 3 at a certain point of the screen. The brightness of the spot on the screen depends on the deformation of the film, which, in turn, depends on the magnitude of the charge established on the surface by the electron beam. Electron gun 5, generating electron beam, is enclosed in a spherical glass mirror shell in which is supported a vacuum. The beam is focused, deflected by an electromagnetic system and modulated power similarly as in a conventional CRT (cathode ray tubes). The main disadvantage - the production of oil, and its replacement (addition of tank) - the procedure is not simple bt

  • Projection televisions and projectors television tubes
  • Typically, these televisions represent the outdoor apparatus, and the bottom part - the projection tube lenses, sound system and electronics, and the upper mirror and translucent screen. The image is formed as follows: from three very bright small light tubes main color (RGB) passes through the optical system of lenses, mirrors, prisms , hidden in the Cabinet and projected onto the screen. This leads to a significant increase of the image that is displayed on a big enough screen.

    Principle of operation

    Tubes (kinescopes) have a very large brightness, it is not recommended to stare into the stationary subjects, as may occur phosphor burn-in and, as a consequence, the formation of lanes and paths, preventing further viewing. In addition, as a result of significant compared to the size of the picture tube, zoom in, fade. They could only look straight, sideways or falling is a bright light - view such systems were impossible. However, the color quality was high, as kinescopes prescribed image continuously (in analog mode) and did not have the "grid". The most common problems - the lack of attention of the rays, which can easily be seen if you go to the hall of the modern slot machines (simulators), at least one with no data - but there will be a picture come out the sides red and blue colors are very reminiscent of the first 3D movies be

    Lack of information rays
  • Projection TVs and projectors, the LCD (LCD) matrices
  • In this type of projectors and TV sets, instead of three picture tubes are used three matrices for the primary colors (RGB - red, green and blue), followed by mixing the resulting three images into one, or one RGB (three-color) matrix. The light of a powerful lamp, which needs constant heat sink (like the matrix), even after the projector is turned on, the built-in cooler (fan) is still cooling for a few minutes. For trehmatrichnye system characterized by the separation of the light spectrum lamp in color components of the optical method:

    the working Principle of LCD panels

    The light is polarized and passes through the dichroic mirrors, which divide it into three primary colors (the rainbow seen in the sky?, that something like this is a division of white light). Each "color" gets on "your" LCD matrix and shines through her optics then collects it all back (in one continuous color flow) and, through the lens to the screen (the projector) or the mirror (in projection TV)

    Projection televisions LCD matrices

    Disadvantages LCD projection systems is imperfect color reproduction and poor network performance: moving objects visible "plume" (fee for digitizing the analog signal). Furthermore, since these matrices operate on the light, and shines through them powerful enough lamp hy , the problem of heat dissipation from the matrices, however, the quality of trehmatrichnye system significantly higher - matrix, which is even more difficult to educate, and brakes added.

    To merit systems include relatively low cost, bright screen (again, if you look at it directly) and small dimensions compared to CRT projectors and TVs

  • Projection TVs and projectors on a silicon substrate (LCOS)
  • On the semiconductor substrate LCoS-crystal is a reflective layer over which is the LCD and polarizer. Under the influence of electrical signals liquid crystals or close reflective surfaces, or open, allowing light directed from an external source reflected from the mirror substrate of crystal:

    Projection TVs and projectors on a silicon substrate

    As LCD-projectors, LCoS projectors are used mainly trentepohlia scheme based on monochromatic (single color) LCoS-matrices, however, there are also single-chip solutions in which a color image is obtained by use of three powerful color rapidly switchable LEDs, consistently giving light red, green and blue colors. Single chip projectors have not found wide application: the triple loss of the light flux passing filter, a low quality rendering, more complex production technology of non-ferrous LCoSchips bn

    To merit trehčipovyh LCoS projectors include a greater coefficient of filling the operating space of the matrix: since the controls are placed behind the reflective layer, they do not prevent the passage of light, in contrast to a translucent LCD-matrix, which reducessetdataset images and minimizes the "effect combs" (trail behind moving objects). In addition, LCoS have a deeper black and higher contrast, which is achieved through "reflection" and not "through the passage of luminous flux through the matrix, the performance of the LCoS matrices are also higher than LCD matrices

    In the second part of the article, You will learn about projection TVs and projectors with Micromirror device (DMD or DLP) and laser TVs ab

    Link to this story: http://en.rem-tv.net/publ/3-1-0-40

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