| 摘要 |
An improved sprocket wheel for substantially planar feeding of a strip of film in a photographic camera by applying a thrust to end edges of two parallel and spaced apart rows of perforations provided along the film strip includes two corresponding trains of film feeding teeth, each tooth having a curved film thrusting surface confronting the plane along which film is fed in the camera and comprising a base portion having a gentler slope with respect to the film feeding plane than an involute tooth profile and an upper portion having a steeper slope with respect to the film feeding plane than an involute tooth profile, and further having a ridge defined between the outer side surface and the film thrusting surface of each tooth to substantially conform to a rounded corner of each film performation and thereby facilitate smooth feeding of the film. |
