Film cassette
US4834306A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 25, 1988 |
| Grant date | May 30, 1989 |
| Priority date | — |
| Expiry date | Mar 25, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B2217/266
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
In a film cassette, a film spool is rotatable independently of a pair of coaxially spaced rotatable disks. The two disks have respective circumferential lips which prevent the outermost leader convolution of a film roll wound on the spool from clock-springing into contact with the cassette shell. When the spool is initially rotated, the disks may remain substantially stationary and the film roll, since its inner end is secured to the spool, tends to expand radially to ensure a non-slipping relation between the outermost leader convolution and the lips. Then, rotation of the spool must rotate the disks and stationary internal spreaders will deflect successive sections of the disks to an axial dimension exceeding the film width, thereby allowing corresponding sections of the outermost leader convolution to exit from the radial confinement of the lips. Stationary internal guides direct the freed end of the outermost leader convolution to the cassette opening. Sufficient film thrust is provided by the spool as it is rotated, to thread the film leader along a predetermined path from the cassette opening, particularly because the outermost leader convolution is kept out of contact with t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.