[Konvas] imax projector (off topic)

[Peter Haas]

On Feb 14, 2009, at 5:38 PM, Brad Leong wrote:

> I was wathcing "how it's made" last night on discovery channel,  
> awesome show by the way.  They had a segment on how imax projectors  
> are made.  Very intersting stuff.  Can anyone explain the movement  
> exactly?  There seemed to be a large rotating wheel that the film  
> spun through and somehow advances frame by frame, didn't seem to be  
> a claw or intermetents sprockets

Even more interesting was a "How It's Made" where they showed an Arri  
435 being made. Most particularly, the single-piece internal frame  
and the construction of the movement.

Anyway, the IMAX patent documents disclose all.

The HIM 5-minute clip (their maximum, unless it is continued to a  
second 5 minute maxmimum part, for a total of ten minutes maximum)  
clearly showed the registration pins, but it DID NOT show what is  
perhaps the most critical detail, the so-called "rolling loop".

The interior circumference of the mechanism is perhaps almost exactly  
one (horizontal) frame less, and the supporting mechanisms  
facilitate, thereby, the single frame advance.