Designer Times
Page 2 of 2

Several tricky issues were involved in the design of the Reversing Projector. Film is transported thru the projection gate by an escapement mechanism whereby a claw feature engages the film perforations....little rectangular holes punched in the edges of the film. When the film moves in one direction, the claws contact the leading edge of the perf holes. When running in reverse, the trailing edge is now the new leading edge. Thus the two 35mm film frames must have a very slight offset so as to ensure that the projected image always is in the same place on the screen.

Since the lamphouse is fixed and the projection gate is shifted sideways from one image path to the next, the film path must move with the gate creating quite a potential film path problem. In addition the whole projector must be able to be aimed up or down to match the screen as well as side to side. It was a requirement to install the biggest practical film reels inside the smallest possible cabinet. This is where my lack of industry practice came in handy.

I experimented in 3-D Cad with a zillion reel location combinations until I found a real goofy set up that violated typical projection expectations. The next thing was to figure out the nutty film path with the least amount of idler spools. This was so easy to visualize in CAD....far quicker than experimenting physically in the shop.

The final result was that rather than have a cabinet with a film access door, the whole cabinet became a group of doors on a steel tube frame....100% access to everything. The usual formed edge sheet metal doors would be pretty complex, why not just use heavy sheet aluminum panels with quick release hardware....much cheaper. When some flat sound deadener was added to the flat panels, the projector was quiet enough to not need a sound proofed projection booth. Another cost saving. In the end the whole deal was this rectangular group of flats....sort of an artistic cubist block.

After the wrinkles were worked out of the test prototype, Don suggested applying for a U.S. patent. I thought what for. Ever since the Thomas Edison early movie days 100 years ago, everything surely has now been invented.

Wrong! The United States Patent Office issued patent number 5,581,313 to inventor dudes Iwerks and Gurr. New and novel they say. I think the lesson here is that if you know too much, you can't do it. Sounds familiar....Walt got Disneyland built the same way fifty years ago, including a new and novel 360 degree movie theater to go with it.

oOo

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