Photographic apparatus gear train having a unique set of gears

A self-developing camera for exposing and processing self-developing film units, said self-developing camera comprising:

• a first housing section having a chamber therein in which a self-developing film unit is adapted to be located for exposure, said first housing section having an opening therein providing access to said chamber;
• a second housing section coupled to said first housing section for movement between an operative position wherein said second section is in blocking relation to said opening in said first housing and an inoperative position wherein said second section is located in unblocking relation to said opening for providing access to said opening;
• a pair of pressure-applying rollers, mounted on said second housing section for movement therewith between said operative and inoperative positions, for applying a compressive pressure to such a film unit as it is advanced between said pair of rollers subsequent to exposure when said second housing section is located in said operative position;
• a motor mounted in said first housing section and
• a gear train coupling said motor to at least one of said pair of pressure rollers when said second housing section is located in said operative position for transmitting power from said motor to said one roller to cause said one roller to rotate and advance such a film unit relative to said pair of rollers;
• said gear train including a driver pinion mounted on said first housing section and a follower mating gear mounted on said second housing section for movement therewith such that said pinion and gear engage in operative mesh when said second housing section is located in said operative position and are disengaged from one another when said second housing section is moved from said operative position to said inoperative position;
• said pinion and said gear having respective numbers of teeth and gear tooth profiles such that the speed ratio of said pinion and gear is other than 1:1 and the tip spacing of the teeth on said gear and pinion, as measured between the midpoints of the radial end tips of adjacent teeth, is substantially equal to facilitate bringing said gear into operative mesh with said pinion when said second housing section is moved from said inoperative position to said operative position.

A separable gear train, usable in a photographic apparatus for transmitting power from a motor to a motor-driven component of the appartus, said gear train comprising:

• a first gear adapted to be coupled to and driven by the motor;
• a second gear adapted to be coupled to the motor driven component and being configured for movement, relative to said first gear, between an operative position wherein said second gear is engaged in operative mesh with said first gear whereby said second gear serves as follower of and is driven by said first gear, and inoperative position wherein said second gear is disengaged from said first gear;
• said first and second gears having respective numbers of teeth and tooth profiles such that the speed ratio of said first and second gears is other than 1:1 and the tip spacing of said first and second gears, as measured between the midpoints of the radial ends of adjacent teeth, is substantially equal to facilitate bringing said first and second gears into operative mesh when said second gear is moved from said inoperative position to said operative position, said second gear being a pinion and said first gear being a mating gear, said addendum of said pinion being shorter than the addendum of said mating gear whereby the ratio of the length of the addendum on said mating gear to the length of the addendum of said pinion is at least 2:1, said profiles of the contacting surfaces of said pinion and said gear being based on involute curves and said pinion and gear having teeth that are substantially pointed.