Compact overhead projection device for image display uses internal, laterally mounted image generator with three angles mirrors and lens to project a magnified image onto an enclosed screen forming part of the device housing

摘要

The device comprises a housing (1) in which a structure (10) is installed, with first (12) and second (11) internal volumes. The first volume houses the image creation elements, including two mirrors (110,112) and short focal-length lens (114), enclosed in box (30) made typically from folded metal sheet. The image rays (R) are projected through the opening (124) into the second volume containing the main mirror (123), positioned vertically or at a shallow angle, to project the image forward onto the screen (121) which is viewed from the other side. The screen (121) may incorporate a surface using a Fresnel lens arrangement to improve image quality and luminosity. Typically the base (2) has a depth of 15 cm, the top (3) a depth of 25 cm and a height of 65 cm.