Film exposure status indicator for a film cartridge

Abstract

A film exposure status indicator 10,78 for a film cartridge 11 to indicate whether a filmstrip on a spool 18 within the cartridge has been at least partially rewound onto the spool. The indicator relies on rewinding motion of the spool to indicate at least partial exposure of the filmstrip. In the preferred embodiment 78, the status indicator is a self-contained module attachable to a standard 35 mm film cartridge entirely within an external well 66 of one 34 of the cartridge end caps. The module has a central aperture for receiving the protruding end 38 of the film spool and includes a cover disk 26 having first and second status indication windows 40,39. An indicator wheel 52 below the cover disk has first and second exposure indicia visible through the respective windows. A spring-biased locking button 58 on the indicator wheel 52 is engageable by a driver tab 50 on a driver wheel 42, rotatably driven by the film spool, below the indicator wheel when the driver wheel is rotated in the film-rewinding direction. When the locking button 58 is aligned with the first window 40, button 58 is urged axially to enter the window, indicating the filmstrip has been at least partially rewound, which movement locks the indicator wheel 52 to the cover disk 26 preventing further rotation of the indicator wheel and decouples the indicator wheel 52 from the driver wheel 42. A second indicium indicating film exposure is then visible through the second status indication window 39.