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Projector screen tunnel1/24/2024 ![]() The pressure required to hold a negative-pressure screen up is very low. The higher air pressure inside the dome pushes the screen up towards the dome frame. The HVAC system filters, cleans, and disinfects the air that is extracted from the room.įor a negative-pressure dome, a fan runs continuously to evacuate air from behind the screen, creating an area of low pressure. When a door is opened for a doctor to enter, air rushes into the room to equalize the pressure, preventing possibly infected air from leaving the room. An infected person is placed in isolation in a room and the HVAC system is set up so that slightly more air is sucked out of the room than is blown in. One place we hear about negative-pressure is hospitals, where negative-pressure rooms are used to prevent the spread of disease. Negative-pressure is where the air pressure in a space is lower than the surrounding atmosphere – a vacuum (or partial vacuum). Inflating a car tire, pumping up a basketball, and blowing up a balloon are all examples of positive air pressure – that is the air pressure inside the vessel is higher than the surrounding atmosphere. When we talk about air pressure, we usually mean positive pressure. When it comes to cleaning, a fabric screen can be removed and washed or replaced in a matter of hours, while an aluminum screen will require the dome to be closed for several days or even weeks. In fact, a fabric screen usually has fewer seams than a perforated aluminum screen of the same size. Our sewing team stitch panels together to form a perfect hemisphere with as few seams as possible. When designing a new dome, we carefully select the screen fabric and choose material with the right gain to match the projection system, resulting in a bright, high-contrast image. Our engineering and sewing teams have continued to innovate, making our domes even easier to assemble and selecting new fabrics for even better projection. Our purpose-built geodesic domes and fabric screens soon became the envy of the dome projection world. So, we set about making something as portable as an inflatable dome, with the projection quality of an aluminum screen. Inflatable domes were not up to the task, solid domes are too heavy and laborious to be easily portable and perforated aluminum is expensive and only suited to fixed installations. When Fulldome.pro introduced high-resolution, multi-projector systems with fast and automatic calibration we realised we also needed to create portable dome screens that could make the most of this technology. The only portable dome projection was via low-resolution, single-projector systems in inflatable domes. Inflatable domes, where the air pressure inside the dome is increased to hold the screen up offer portability but, when used outdoors are prone to movement in windy conditions.īefore Fulldome.pro revolutionized dome projection there wasn’t much call for high quality portable dome screens. However, aluminum screens are expensive and although they can be built to very large diameters, require a complex supporting frame structure. The perforations also allow for the flow of air through the screen for climate control, preventing the build-up of moisture on the surface, which was also a problem with solid screens. The thousands of tiny perforations in the screen reduce acoustic reflection and actually allow speakers to be placed behind the screen so that sound can appear to come from the appropriate direction for the video. Most large planetarium screens are now made of perforated aluminum panels fixed to a support in frame. Solid domes such as this and the many fiberglass and glass reinforced plastic domes that followed, reflect sound as well as light, detracting from the viewing experience. The first optical planetarium, built in 1923 by the Zeiss company in Jena, Germany, projected onto the white plaster lining of a 16-meter diameter hemispherical concrete dome.
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