Photo film take-up spool and shaft

A take-up spool incorporated in a lens-fitted photo film unit, said lens-fitted photo film unit having a cassette containing chamber and a roll chamber between which an exposure aperture is located, said cassette containing chamber containing a cassette, said take-up spool being disposed in said roll chamber in rotatable fashion, unexposed photo film being drawn from said cassette, a leader of said photo film being secured to said take-up spool about which said photo film is wound in a form of a photo film roll, said take-up spool comprising:

• a core having a substantially cylindrical shape with an outer cylindrical face, and said core having a diametrical take-up slot which divides said core into first and second core members, each core member having a confronting planar wall at said take-up slot;
• at least one curved face, formed on at least one of said confronted planar walls of said two core members between said respective one confronting planar wall of said core member at said take-up slot and said cylindrical face of said core, said curved face having an arc shape and having a radius of curvature which is measured at 0.4-0.85 times a radius of said core, said curved face for preventing said leader secured to said core from being sharply bent;
• and
• a retaining device for fixing said first core member to said second core member to render an interval between said first and second core members equal to or smaller than a thickness of said photo film;
• wherein said leader is nipped between said first core member and said second core member.

A take-up spool incorporated in a lens-fitted photo film unit, said lens-fitted photo film unit having a cassette containing chamber and a roll chamber between which an exposure aperture is located, said cassette containing chamber containing a cassette, said take-up spool being disposed in said roll chamber in rotatable fashion, unexposed photo film being drawn from said cassette, a leader of said photo film being secured to said take-up spool about which said photo film is wound in a form of a photo film roll, said take-up spool comprising:

• a core having a substantially cylindrical shape with an outer cylindrical face, and said core having a diametrical take-up slot which divides said core into first and second core halves, each core half having a confronting planar wall at said take-up slot;
• at least one curved face, formed on at least one of said confronted planar walls of said two core halves between said respective one confronting planar wall of said core half at said take-up slot and said cylindrical face of said core, said curved face having an arc shape and having a radius of curvature which is measured at 0.4-0.85 times a radius of said core, said curved face for preventing said leader secured to said core from being sharply bent when nipped between said confronted planar walls of said two core halves;
• first and second flanges, respectively disposed on distal ends of said core, having a substantially circular shape, for regulating edges of said photo film roll;
• wherein said first flange includes first and second flange halves, said second flange includes third and fourth flange halves, said first and third flanges halves are disposed on said first core half, and said second and fourth flange halves are disposed on said second core half.