Film cassette with lockable light shield

Abstract: A film cassette comprises light blocking means supported for rotation to a light blocking position for preventing ambient light from entering the cassette interior and to a non-blocking position. The light blocking means has a cavity (17) configured for permitting a driver element (19) to rotate in the cavity initially without rotating the light blocking means out of its light blocking position and then into driving engagement with the light blocking means to allow the driver element (19) to rotate the light blocking means from its light blocking position to its non-blocking position. A locking pawl (13) protrudes into the cavity (17) to secure the light blocking means in its light blocking position and is adapted to be displaced from the cavity to release the light blocking means when the driver element (19) is rotated initially in the cavity without rotating the light blocking means out of its light blocking position.

Description: The invention relates generally to the field of photography, and in particular to film cassettes. More specifically, the invention relates to a film cassette with a movable light shield for preventing ambient light from entering the cassette interior. The light shield can be locked open or closed. It is known to provide a film cassette with a light shield that can be closed to prevent ambient light from entering the cassette interior and can be opened to permit film movement out of and into the film cassette as described by the EP-A-0 545 098. Commonly assigned U.S. Patent No. 4,255,034, issued March 10, 1981, discloses a film disk cartridge in which a core or hub for the disk film has a central opening for receiving a splined post (of a camera) in driving engagement to rotate successive sectors of the disk film beneath an exposure window in the housing of the cassette. A cover member is supported inside the housing for rotation about the core between a closed position over the exposure window and an open position removed from the exposure window. Engagement of a flexible tab on the cover member and a fixed tooth on an inside wall of the housing secures the cover member releasably in its closed position. An access hole is located in the housing to receive a release pin (of the camera) which disengages the tab from the tooth to permit the cover member to be rotated from its closed position to its open position. A separate pin (of the camera) engages the cover member to rotate the cover member to its open position In U.S. Patent No. 4,255,034, a release pin is used to disable the locking mechanism for the cover member and a separate pin is used to rotate the cover member from its closed position to its open position. This arrangement results in an unduly complex design for the camera as well as for the film disk cartridge. In accordance with the present invention, a film cassette with lockable light shield is provided as defined in claim 1. Preferred embodiments may be gathered from the dependent claims. ADVANTAGEOUS EFFECT OF THE INVENTION Thus, a relatively simple design can be realized for a camera as well as for the film cassette. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front perspective view of a film cassette with a lockable light shield according to a preferred embodiment of the invention; FIGS. 2 and 3 are perspective views of an end post of the light shield and a separate driver element for rotating the light shield between a closed or light blocking position and an open or non-blocking position, showing how the driver element is inserted into a coaxial cavity in the end post; and FIGS. 4, 5, and 6 are elevation views similar to FIGS. 2 and 3, showing how the driver element is rotated in the cavity initially to displace a locking pawl from the cavity and then to rotate the light shield from its light blocking position to its non-blocking position. DETAILED DESCRIPTION OF THE INVENTION The invention is disclosed as being embodied preferably in a film cassette. Because the features of a film cassette are generally known as typified by commonly assigned U.S. Patent No. 5,200,777, issued April 6, 1993, the description which follows is directed in particular only to those elements forming part of or cooperating directly with the disclosed embodiment. It is to be understood, however, that other elements may take various forms known to a person of ordinary skill in the art. Referring now to the drawings, FIGS. 1-6 show a film cassette 1 comprising a cassette shell or housing 3 with a film egress/ingress slot 7, light blocking means preferably in the form of a light shield 9, a film spool 11 for supporting a film roll (not shown), and locking means for the light shield preferably in the form of a locking pawl 13. The light shield 9 has a pair of opposite end posts, only one 15 shown, which are supported via the cassette shell 3 to mount the light shield for rotation to a closed or light blocking position, shown in FIGS. 1, 4 and 5, for preventing ambient light from entering the cassette interior through the film egress/ingress slot 7, and to an open or non-blocking position, shown in FIG. 6. for permitting film movement out of and into the cassette interior through the film egress/ingress slot. The end post 15 of the light shield 9 has a coaxial cavity 17 for receiving a rotary driver element 19 (of a camera) to allow the driver element to rotate the light shield between its closed and open positions. As shown in FIGS. 3 and 4, the driver element 19 has an integral driver rib 21 which is received in a driver opening 23 of the cavity 17 when the driver element is received in the cavity. The driver opening 23 is substantially wider than the driver rib 21 to permit the driver element 19 to be rotated in the cavity 17, in an opening direction indicated by an arrow O in FIG. 5, initially without similarly rotating the light shield 9 and then into driving engagement with the end post 15 to rotate the light shield from its closed position to its open position as shown in FIG. 6. The locking pawl 13 is integrally formed with the cassette shell 3, and it is inherently biased to protrude into a locking opening 25 of the cavity 17 to secure the light shield 9 in its closed position as shown in FIGS. 2-4. The locking opening 25 is substantially wider than an integral cam rib 27 of the driver element 19 which is received in the locking opening when the driver element 19 is received in the cavity 17, and the locking pawl 13 is resilient. These features permit the locking pawl 13 to be pushed out of the locking opening 25 by the cam rib 27 when the driver element 19 is rotated in the cavity 17, in the opening direction indicated by the arrow O in FIG. 5, initially without similarly rotating the light shield 9. Thus, the driver element 19 must be rotated in the cavity 17 in order to disengage the locking pawl 13 from the end post 15. The end post 15 has a locking notch 29 located to receive the locking pawl 13, as shown in FIG. 6, when the light shield 9 is in its open position, to secure the light shield in the open position. The locking notch 29 is partly defined by a ramp 31 that serves to push the locking pawl 13 out of the locking notch when driver element 19 is rotated in the cavity 17 in driving engagement with the end post 15, in a closing direction opposite to the opening direction indicated by the arrow O, to rotate the light shield 9 from its open position to its closed position. The invention has been described with reference to a preferred embodiment. However, it will be appreciated that variations and modifications can be effected by a person of ordinary skill in the art without departing from the scope of the invention. PARTS LIST FOR FIGS. 1-3 1. film cassette 3. cassette housing 7. film egress/ingress slot 9. light shield 11. film spool 13. locking pawl 15. end post 17. coaxial cavity 21. driver rib 23. driver opening 25. locking opening 27. cam rib 29. locking notch 31. ramp

Claims: Film cassette (1) comprising light blocking means (9) supported at the film egress/ingress slot (7) for rotation to a light blocking position for preventing ambient light from entering the cassette interior through the film egress/ingress slot and to a non-blocking position, and locking means for engaging said light blocking means to secure the light blocking means in its light blocking position and adapted to be moved out of engagement with the light blocking means (9) to release the light blocking means, said light blocking means (9) having a cavity (17) for an external driver element (19), characterized in that: said cavity is configured for permitting the driver element (19) to rotate in said cavity (17) initially without rotating the light blocking means out of its light blocking position and then to rotate into driving engagement with the light blocking means to allow the driver element to rotate the light blocking means from its light blocking position to its non-blocking position, and in that said cavity (17) has an opening (25) shaped so as to allow engagement with said locking means and to permit the driver element to move the locking means out of engagement with said aperture and the light blocking means when the driver element (19) is rotated initially in the cavity without rotating the light blocking means out of its light blocking position. Film cassette (1) as recited in claim 1, wherein said locking means comprises a locking pawl (13) which protrudes into said cavity (17) through said aperture to secure said light blocking means (9) in its light blocking position and is adapted to be displaced from the cavity to release the light blocking means when the driver element is rotated initially in the cavity without rotating the light blocking means(9). Film cassette (1) as recited in claim 2, wherein said light blocking means includes a notch (29) in said aperture for receiving said locking pawl (13) to secure the light blocking means (9) in its non-blocking position. Film cassette (1) as recited in claim 2, wherein said locking pawl (13) is resilient to permit the locking pawl to be displaced from said cavity (17). Film cassette (1) as recited in claim 2 or 4, wherein said locking pawl (13) is integrally formed with a cassette shell (3).

Inventors: WIRT MICHAEL LEVERNE, WIRT, MICHAEL LEVERNE, WIRT, MICHAEL LEVERNE , C/O EASTMAN KODAK COMPANY
Applicants: EASTMAN KODAK CO, EASTMAN KODAK COMPANY
Application year: 1995
Main classification: G03B17
IPC codes: G03B17, G03C3