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.

  1. iswandoyo says: August 9, 20071:51 am

    good one !

  2. Timmay says: August 18, 20105:10 pm

    I was once told that the over-head projector was invented by the military so that instructors could keep an eye on sleepy GI’s.

  3. Firebrand38 says: August 18, 20105:56 pm

    You were told wrong.
    1939 Principle used in bowling alleys…
    1941 same inventor…
    1944 civilian…
    1948 (filed) civilian…
    1948 another civilian…
    1963 The one we all grew up with…

  4. Timmay says: August 19, 20108:06 am

    Very informative, thank you.
    And yes I do remember the last one quite well. Right down to the trapezoid door to access the bulb.

  5. M.S.W. says: August 20, 20108:05 am

    Wow 500Watt bulb. Must have cost a fortune back then to keep that thing going.

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