| 摘要 |
<p>In a film cassette (1), a film spool (5) is rotatable independently of a pair of coaxially spaced disks (51, 53). The two disks (51, 53) have respective annular circumferential lips (59, 61) which prevent the outermost leader convolution (47) of a film roll (37) wound on the spool core (23) from clock-springing into contact with the cassette shell (3). When the spool core (23) is initially rotated, the disks (51, 53) can remain substantially stationary and the film roll (37), since its inner end (39) is secured to the spool core, tends to expand radially to ensure a non-slipping relation between the outermost leader convolution (47) and the circumferential lips (59, 61). Then, rotation of the spool core (23) must rotate the disks (51, 53) and stationary internal spreaders (65, 67) will deflect successive portions (59 min , 61 min ) of the lips (59, 61) to an axial dimension exceeding the film width, thereby allowing corresponding portions of the outermost leader convolution (47) to exit from the radial confinement of the lips. Stationary internal guides (73, 75) direct the freed forward end (45) of the outermost leader convolution (47) to the cassette opening (25). Sufficient film thrust is provided by the spool core (23) as it is rotated, to thread the film leader (43) along a predetermined path from the cassette opening (25), to the outside of the cassette shell (3).</p> |
