Duo-Sprocket: 3 perf movie projection.

[charles pappas]

While looking through some old papers I was reminded of a patent some aquaintances had received in 1995, for what they called Duo-Sprocket. This was a nested set of two sprockets such that the different diameters of the sprockets would allow for 3 or 4 perf running speeds for the movie projector depending on which sprocket was used (they were easily changed out).

The patent obviously never "took off" and I'm wondering if anyone would have an idea why not. I can imagine that perhaps it was realized to be near the end of analogue projection era or that the theaterical exhibition  industry (and film makers) was too hidebound, or perhaps an outsider was not to be enriched.

I'd be interested in anyone's ideas.

https://www.freepatentsonline.com/4900293.html

[charles pappas]

I'm sure other entities had thought of " 3 perf," release prints, wondering why that didn't take off.

[David Mullen ASC]

3-perf would have been a savings for producers and distributors but not exhibitors so there would be little incentive to upgrade every projector.  Plus you’d have to deal with trailers and 4-perf scope prints. Digital projection only took off because of some financial help from distributors plus the success of “Avatar” when suddenly all the theaters wanted to show 3D.