Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
  • G03B21/00—Projectors or projection-type viewers; Accessories therefor
  • G03B21/54—Accessories
  • G03B21/56—Projection screens
  • G03B21/60—Projection screens characterised by the nature of the surface

Definitions

• Screen of light gain used for low luminosity sources, such as video projectors, for instance, are usually slightly reflective; their concave shape allows them to guide the light so that the luminosity can be more or less uniform to the spectators at every point of its surface.
• a screen cannot be mirrored, because, as anyone with a slight knowledge of optics knows, what would be seen, besides the room and the projector, would be the circle of the lens at the point corresponding to the lens of the projector existing in the virtual room on the other side of the surface of the mirror.
• the surface of the screen must diffuse the light in all directions, so that the light can reach the spectators from each and every point of the screen, even if they change position.
• the solution found to date now is the use of slightly reflective dim pellicles (as if it were a dirty mirror, in which we can see hardly anything, but which still maintains some metallic brightness) being half way between mirrored and opaque. Nevertheless, in a bright environment, especially with low luminosity sources, the result is still unsatisfactory, because when the screen becomes semi-obscure, it only reflects part of the light, absorbing the rest, which is better in respect of a white wall, but is still far from being ideal.
• one (2) which is slightly translucent, produces almost without light absorption the scattering of the light that passes through it, due to the micrometrical irregularity of its surface.
• the second one (3) which completely mirrored, recedes the light in the oposite direction and, by crossing the first pellicle, scatters the light a bit more.
• the pellicles are thin, they can be adhesive, and the first one can also have other characteristics, such as a surface with a configuration of multiple tiny lenses side by side or having a fluted or wavy surface, vertically or crossed vertically and horizontally causing a sufficient scattering of the light by diffraction so that transparent material can be used in order to make even more use of the light.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Overhead Projectors And Projection Screens (AREA)
• Transforming Electric Information Into Light Information (AREA)

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• 1995
  • 1995-05-04 PT PT916695U patent/PT9166T/pt not_active Application Discontinuation
• 1996
  • 1996-05-03 WO PCT/PT1996/000002 patent/WO1996035141A1/en not_active Application Discontinuation
  • 1996-05-03 AU AU54105/96A patent/AU5410596A/en not_active Abandoned
  • 1996-05-03 CA CA 2194410 patent/CA2194410A1/en not_active Abandoned
  • 1996-05-03 JP JP8533214A patent/JPH10503034A/ja active Pending
  • 1996-05-03 EP EP96911128A patent/EP0769163A1/de not_active Withdrawn

Non-Patent Citations (1)

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