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An overhead projector works on the same principle as a slide projector, in which a focusing lens projects light from an illuminated slide onto a projection screen where a real image is formed. However some differences are necessitated by the much larger size of the transparencies used (generally the size of a printed page), and the requirement ...
In the GDR, it was mainly known for producing overhead projectors, called Polylux. The company was founded in 1870 as Reißzeugrichter and manufactured drawing table tools. In 1874 the founder Emil Oskar Richter invented the bow compass. After switching its focus to overhead projectors in the late 1960s, it was renamed to VEB Polytechnik.
The Polylux was an overhead projector produced in the German Democratic Republic (GDR). It also functioned as a generic name for overhead projectors in the GDR. The Polylux was produced in the VEB ( Volkseigener Betrieb : people’s enterprise) Phylatex-Physikgeräte DDR, in Frankenberg near Chemnitz (then known as Karl-Marx-Stadt ).
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 .
Overhead projector in operation, with a transparency being flashed. A transparency, also known variously as a viewfoil or foil (from the French word "feuille" or sheet), or viewgraph, is a thin sheet of transparent flexible material, typically polyester (historically cellulose acetate), onto which figures can be drawn.
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Nicholas Power (October 22, 1854–February 7, 1921) was one of the most successful manufacturers of film projectors in the silent era, creating some of the earliest commercial projectors. [1] He began his career working in theaters in the 1890s, and taking apart Edison projectors to learn how they worked.
Slide projector light generation and collimation system: from left to right, mirror / reflector, bulb, condenser lens 1, green-tinted heat-absorbing glass, condenser lens 2; a centrifugal fan, used to cool the bulb, is visible at the top of the picture. A projector has three main optical elements: [3]: 39–40