Film cassette with lockable light shield

A film cassette comprises light blocking means supported for movement 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 for receiving a driver element in driving engagement to allow the driver element to move the light blocking means from its light blocking position to its non-blocking position. A locking pawl protrudes into the cavity 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 is received in the cavity.

CROSS-REFERENCE TO RELATED APPLICATION 
Reference is made to commonly assigned copending application Ser. No. 
08/078,671, entitled FILM CASSETTE WITH INTERACTING SPOOL LOCK AND LIGHT 
SHIELD and filed Jun. 16, 1993, in the name of Anthony DiRisio. 
FIELD OF THE INVENTION 
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. 
BACKGROUND OF THE INVENTION 
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. 
For example, commonly assigned U.S. Pat. No. 4,255,034, issued Mar. 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. 
PROBLEM TO BE SOLVED BY THE INVENTION 
In U.S. Pat. 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. 
SUMMARY OF THE INVENTION 
According to one aspect of the invention, a film cassette comprising light 
blocking means supported for movement to a light blocking position for 
preventing ambient light from entering the cassette interior and to a 
non-blocking position, and locking means for engaging the 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 to 
release the light blocking means, is characterized in that: 
the light blocking means has a cavity for receiving a driver element in 
driving engagement to allow the driver element to move the light blocking 
means from its light blocking position to its non-blocking position and is 
open to the locking means to permit the driver element to move the locking 
means out of engagement with the light blocking means when the driver 
element is received in the cavity. 
More specifically, the locking means includes a locking pawl that protrudes 
into the cavity 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 is received in the cavity. 
According to another aspect of the invention, a driver element to be used 
with a film cassette that has light blocking means supported for movement 
to a light blocking position for preventing ambient light from entering 
the cassette interior and to a non-blocking position and has a locking 
pawl for engaging the light blocking means to secure the light blocking 
means in its light blocking position, is characterized in that: 
the driver element is configured to be received in a cavity in the light 
blocking means to drivingly engage the light blocking means to move the 
light blocking means from its light blocking position to its non-blocking 
position and includes cam means for moving the locking pawl out of 
engagement with the light blocking means when the driver element is 
received in the cavity. 
ADVANTAGEOUS EFFECT OF THE INVENTION 
Thus, a relatively simple design can be realized for a camera as well as 
for the film cassette.

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. Pat. No. 5,200,777, issued Apr. 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. 1-3 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 and 2, 
for preventing ambient light from entering the cassette interior through 
the film egress/ingress slot 7, and an open or non-blocking position, 
shown in FIG. 3. 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 
in driving engagement 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 can be seen in FIG. 1, the driver element 19 has an integral 
driver rib 21 which is received in a driver opening 23 of the cavity 17 to 
drivingly engage the light shield 9. 
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 FIG.2. 
In addition, the locking pawl 13 is resilient. This permits the locking 
pawl 13 to be pushed out of the locking opening 25 by the tapered edge 26 
of an integral cam rib 27 of the driver element 19 when the driver element 
is received in the cavity 17 (to locate the cam rib in the locking 
opening). See the broken line depiction of the locking pawl in FIG. 3. 
The end post 15 has a locking notch 29 located to receive the locking pawl 
13, as shown in FIG. 3, 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 the light shield 9 is rotated clockwise in FIG. 3 
out of its open position. 
Operation 
FIG. 2 shows the locking pawl 13 in the locking opening 25 of the cavity 17 
to secure the light shield 9 in its closed position. 
When the driver element 19 is received in the cavity 17, its cam rib 27 is 
located in the locking opening 25 of the cavity to cause the tapered edge 
26 of the cam rib to push the locking pawl 13 out of the locking opening, 
and its driver rib 21 is located in the driver opening 23 of the cavity to 
drivingly engage the light shield 9. Rotation of the driver element 19, 
then, counter-clockwise in FIG. 3, similarly rotates the light shield 9 
from its closed position to its open position, allowing the locking pawl 
13 to drop into the locking notch 29 to secure the light shield in the 
open position. 
When the driver element 19 is rotated clockwise in FIG. 3, it similarly 
rotates the light shield 9 from its open position to its closed position. 
This causes the ramp 31 of the locking notch 29 to push the locking pawl 
13 out of the locking notch, allowing the locking pawl to come to rest 
against the cam rib 27 of the driver element 19 (which is located in the 
locking opening 25 of the cavity 17). 
When the driver element 19 is removed from the cavity 17, the cam rib 27 is 
fully withdrawn from the locking opening 25 of the cavity 17 before the 
driver rib 21 is fully withdrawn from the driver opening 23. This ensures 
that the driver rib 21 remains in the driver opening 23 until after the 
locking pawl 13 drops into the locking opening 25 to secure the light 
shield 9 in 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. 
TS 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 
26. tapered edge 
27. cam rib 
29. locking notch 
31. ramp