New Projector Throws Illustrations Behind Speaker’s Back (Apr, 1935)
New Projector Throws Illustrations Behind Speaker’s Back
FACING the audience as he talks, a speaker may now illustrate his lectures on a screen behind him without turning around with the aid of a novel optical projector recently perfected by a well known German firm.
The speaker, directly facing his audience, illustrates his talk by writing or drawing horizontally on a sheet of cellophane lying on a glass table before him, and the script is projected, ten to fourteen times enlarged, on the wall screen behind him.
Underneath the glass table, the light of a 500-watt bulb is condensed and reflected through the transparent cellophane. The lines then pass through a lens to the mirror and -are projected onto the screen.