Arrangement for opening and closing a film sheet cassette and a film sheet cassette provided therewith

An arrangement for opening and closing a film sheet cassette having a bottom element and a top element movable relative to the bottom element between open and closed positions, includes a sliding element guided on the bottom element and movable relative to the top element in a first direction from a first position in which it engages the top element and thereby the latter is retained in the closed position to a second position in which said sliding element disengages from the top element and thereby the latter can move to the open position, a spring urging the sliding element into the first engaged position and an arresting device cooperating with the sliding element and operative for preventing unintentional movement of the sliding element from the first engaged position to the second disengaged position by itself or under the action of impacts, and thereby preventing opening of the cassette.

BACKGROUND OF THE INVENTION 
The present invention relates to an arrangement for opening and closing of 
a film sheet cassette, particularly an X-ray film cassette, and to a film 
sheet cassette provided with this arrangement. 
Film sheet cassettes with opening and closing arrangements are widely 
utilized. A known film sheet cassette has a bottom part, a top part, and a 
sliding element which is guided on one or two edges of the bottom part, is 
held in closing position by a spring, and has a hook which in the closing 
position engages with a pin provided in the top part. Generally, the top 
part of the film sheet cassette is connected with the bottom part by a 
hinge at its edge, and closing elements are arranged at a side which is 
opposite to the side wherein the hinge is provided. Cassettes are also 
known in which the top part is placed onto the bottom part in parallel 
direction and connected with the latter by connecting elements provided at 
at least two opposite sides. In the cassettes of the first mentioned type, 
several connecting elements are generally provided lengthwise of the 
connecting side of the cassette. It has been recognized that the known 
cassettes possess the disadvantage in that there is a danger that such 
cassettes can be easily opened under the action of impacts delivered in a 
direction opposite to the opening direction of the sliding element. Also, 
the probability that during X-ray examination involving manipulation with 
several cassettes at least one cassette drops on the floor, is relatively 
high. Opening of the cassette is especially undesirable when it has been 
exposed inasmuch as the opening of the cassette makes it useless and the 
patient must be again subjected to X-ray examination involving radiation 
for the second time. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide an 
arrangement for opening and closing of film sheet cassettes, and a 
cassette including such an arrangement, which prevent unintentional 
opening of the cassette under the action of impacts. 
In keeping with these objects and with others which will become apparent 
hereinafter, one feature of the present invention resides, briefly stated, 
in an arrangement which has a sliding element guided on a bottom element 
of the cassette and movable relative to a top element in a first direction 
from a first position in which it engages the top element and thereby the 
latter is retained in the closed position to a second position in which 
said sliding element disengages from the top element and thereby the 
latter can move to the open position, and spring means urging the sliding 
element into the first engaged position wherein arresting means is 
provided for operating the sliding element and operative for preventing 
unintentional movement of the sliding element from the first engaged 
position to the second disengages position by itself or under the action 
of impacts, and thereby preventing opening of the cassette. 
Another feature of the present invention is a film sheet cassette which is 
provided with the above-described opening and closing arrangement. 
When the arrangement and the cassette is constructed in accordance with the 
present invention, the arresting means under the action of impacts 
performs its arresting function and prevents opening of the cassette. The 
arresting means is also brought into action by closing of the cassette so 
as to prevent unintentional opening of the latter. 
The novel features which are considered as characteristic for the invention 
are set forth in particular in the appended claims. The invention itself, 
however, both as to its construction and its method of operation, together 
with additional objects and advantages thereof will be best understood 
from the following description of specific embodiments when read in 
connection with the accompanying drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS 
FIG. 1 shows a cassette which has a bottom element identified by reference 
numeral 1 and having a side wall provided with an opening 2 through which 
a pin of an automatic opening mechanism can extend. Reference numeral 3 
identifies a part of guiding elements which together with a face of the 
bottom element forms a guiding passage for a sliding element 4. 
The sliding element 4 has a gripping member or portion 5 which is located 
near the opening 2, and is also provided with elongated slots 6 extending 
in the direction of movement of the sliding element. Pins 7 arranged on 
the bottom element 1 extend through the slots 6. A tension spring 9 is 
suspended on a further pin 8 connected with the bottom element 1. The 
tension spring 9 has one end inserted into a hole 10 of the sliding 
element 4 and holds the latter in the shown closed position. 
Hooks 11 are further formed on the sliding element 4 and engaged with pins 
12 which are mounted on a top element or cover 13 of the cassette. In 
order to open the cassette, the sliding element 4 is displaced in the 
direction of arrow 14 with the aid of the gripping member 5 against force 
of the spring 9 so as to release the hooks 11 from the pins 12 of the 
cover element 13, whereupon the cover element 13 displaces under the 
action of its prestress. The displacement of the sliding element 4 in the 
direction of arrow 14 can also be performed with the aid of a pin which 
extends through the hole 2 and presses against the sliding element so as 
to displace the latter in this direction. 
The conventional cassette can, however, open also in the cases when it 
falls on the floor in the direction of arrow 14, or as an impact is 
delivered against the cassette in a direction opposite to the direction of 
arrow 14. In accordance with the invention, the displacement of the 
sliding element 4 under the action of impacts is prevented by an arresting 
device which may include mechanical elements initially preventing such 
movement of the sliding element, or inertia elements which are brought 
into action by impacts and also prevents this movement. 
One construction of such mechanical arresting device is shown in FIGS. 2a 
and b. The gripping member 5 is spaced from the sliding element 4 in a 
transverse direction and connected with the latter by an elastic 
connecting piece 14a, so that the gripping member 5 can be resiliently 
displaced toward the bottom element 1 of the cassette. The gripping member 
5 has a depression 15 in which a pin 16 of the top element 13 is received. 
A raised portion 15a is also formed in the depression 15 and has a height 
which somewhat exceeds the half diameter of the pin 16. 
In order to automatically open the cassette, a movable pin 17 which extends 
in the direction of movement of the sliding element 4 is inserted in the 
gripping element 5. The movable pin 17 has a rounded head 17a located in 
the opening 2 of the bottom element 1. The movable pin 17 can be displaced 
in the direction of movement 14 of the sliding element 4 against force of 
a spring 18. The movable pin 17 is guided on a pin 19 which extends 
through a slot 20 and is mounted on the gripping member 5. 
The movable pin 17 also has a depression 21 provided with an outwardly 
extending inclined surface 22. The depression 21 is so dimensioned that 
the pin 16 in closed condition is located in this depression, the inclined 
surface 22 upon displacement of the movable pin slides over the pin 16, 
and thereby the gripping member 5 is displaced downwardly. As a result of 
this, the raised portion 15a is released, and the sliding element 4 can be 
displaced to the open position. The operation of the arrangement shown in 
FIGS. 2a and b is as follows: The pin 16 retains the gripping member 5 and 
thereby the sliding element 4 in the condition of striking action against 
movement of the sliding element to the open position. When a user presses 
against the gripping element 5, the latter displaces against force of the 
elastic connecting piece 14a. Thereby, the raised portion 15a moves 
downwardly beyond the pin 16 and the sliding element 4 moves in the 
direction of arrow 14. In the event of automatic opening, a member 23 of 
an automatic opening mechanism presses against the rounded head 17a of the 
movable pin 17, whereby the latter displaces against the force of the 
spring 18 in the direction 14. When the inclined surfaces 22 moves over 
the pin 16, the entire gripping element is placed against the bottom 
element 1 of the cassette. The raised portion 15a moves downwardly so as 
to release the pin 16, and the member 23 displaces the movable pin 17 with 
the gripping member 5 and the sliding element to the open position in the 
direction 14. 
FIGS. 3a and b show a second construction of the arresting arrangement in 
accordance with the present invention. In these Figures parts which are 
identical to the parts of FIGS. 2a and b are identified by identical 
reference numerals. The gripping member is formed here by a rotatable 
rocking member 5' which can turn about an axis extending transverse to the 
direction of movement of the sliding element 4. The rocking member 5' has 
a hook 24 at its one end, the hook engaging with the pin 16 of the top 
element 13 of the cassette. A spring 25 acts between the sliding element 4 
and the rocking member 5' and retains the latter in the closed position. 
The gripping portion of the rocking member 5' is pressed, the latter 
rotates in the counterclockwise direction and overcomes force of the 
spring 25, whereby the hook 24 is released from the pin 16. Thus, the 
sliding element 4 can be displaced in the direction 14. In order to 
automatically open the cassette, a movable pin 17' is provided which can 
be displaced in the sliding element 4 against the force of a spring 18' in 
the direction 13. The rocking member 5' has an inclined surface 26 which 
cooperates with an inclined surface 17" provided on the movable pin 17'. 
When the movable pin 17' is displaced in the direction 14 with the aid of 
the member 23, the inclined surface 17" presses against the inclined 
surface 26 of the rocking member 5' upwardly. Thereby the locking member 
5' turns in the counterclockwise direction and the pin 16 is released in 
the above-mentioned manner. 
FIGS. 4a and b show a third construction of the arresting arrangement. 
Similarly to the first construction, the gripping member 5 is connected 
with the sliding element 4 by the elastic connecting piece 14a. A lever 27 
is pivotably mounted on the gripping member 5 and retained in the shown 
rest position by a pressure spring 28 arranged in the gripping member 5. 
In this rest position, an end portion 27a of the lever extends toward one 
side of the pin 16 of the top element 13, whereby movement of the sliding 
element 4 in the direction 14 is prevented. 
When the gripping member 5 is pressed toward the bottom element of the 
cassette in the abovementioned manner, the end portion 27a of the lever 27 
is displaced out of the path of movement of the pin 16, so that the 
sliding element 4 can be displaced in the direction 14. In the event of 
automatic opening, the member 23 presses against the other end portion 27b 
located in the opening 2, whereby the lever is turned against force of the 
pressure spring 28 and the end portion 27a is again turned away from its 
arresting position. During further displacement of the member 23 the 
gripping member 5 with the sliding element 4 can be displaced in the 
direction 14. 
FIGS. 5a and b show an arresting arrangement which operates under the 
action of inertia forces. It includes a gripping member 5" which is 
connected with the sliding element 4 and has a depression 29 at a side 
located opposite to the bottom element. The bottom element 1 has a 
depression 30 with upwardly inclined surfaces 31. A ball 32 is inserted in 
the above described depressions. When the gripping member 5" displaces in 
the direction 14, the ball 32 can be displaced with the gripping member 
and slide over the inclined surface 31 upwardly out of the depression 29. 
A passage 33 is further provided in the gripping member 5". This passage 
extends in the direction 14 and has a transverse extension 34. A movable 
pin 35 is accommodated in the passage 33 and held in the shown rest 
position by a spring 36 having very small pressure force. The passage 33 
crosses the depression 27, so that its periphery almost contacts with the 
ball 32 accommodated in the depression 30. The spring 36 is located in the 
extension 30 of the gripping member 5". For opening of the cassette the 
gripping member 5" is displaced in the direction 14. As mentioned above, 
the ball 32 is taken away from the depression 29 and brought over the 
inclined surface 31 upwardly onto the bottom element 1 of the cassette. 
This displacement of the gripping element 5" can be performed by the 
opening member 23 which have an engaging surface exceeding the cross 
section of the movable pin 35. 
When, however, an impact is delivered in the direction opposite to the 
direction 14, the movable pin 35 moves under the action of its inertia in 
the direction 14 and closes the space above the ball 32. Thereby the ball 
32 during movement of the gripping member 5" abuts against the inclined 
surface 31 and prevents further displacement of the gripping member. Since 
the sliding element 4 connected with the gripping member 5" must overcome 
different friction torques, the abovementioned displacement of the movable 
pin 35 takes place somewhat faster, whereby the movable pin 35 overlaps 
the path of movement of the ball 32 before the beginning of displacement 
of the sliding element 4 with the gripping member 5". 
FIGS. 6a and b also show an arresting arrangement which operates under the 
action of inertia forces. This arrangement also includes the pin 35 which 
is arranged in the gripping member 5" and movable in the direction 14 
against force of the weak spring 36. A rocking member 37 is provided 
between the gripping member 5" and the bottom element 1 of the cassette. 
The gripping member 5" is pivotal about an axis 35 extending in a 
direction transverse to the direction 14. An end portion 37a of the 
rocking member 37 extends in the passage 33 for the movable pin 35 and is 
located somewhat in front of the inwardly facing end portion of the pin. 
The other end portion 37b of the rocking member 37 almost contacts the 
outer end of the movable pin 35. 
The rocking member 37 has an inclined surface at the side opposite to the 
bottom element 1. In the above-described rest position of the rocking 
member, this inclined surface during displacement of the gripping member 
5" can slide over a projection 39 which is fixedly connected with the 
bottom element. When, however, impact action takes place in the direction 
opposite to the direction 14, the movable pin 35 displaces in the 
direction 14 and its inner end portion turns the end portion 37a of the 
rocking member 37 so that this end portion is withdrawn from the passage 
32 and thereby the rocking member 37 turns in the counterclockwise 
direction. Thereby the rocking member 37 is rotated until it abuts against 
the bottom element 1. In the latter position, displacement of the gripping 
member 5" results in that the front edge of the end portion 37a of the 
rocking member abuts against the projection 39 and further movement of the 
gripping member is prevented. 
After the impact, the movable pin is returned to its initial position by 
the spring 26. Thereby the outer end portion of the movable pin presses 
against the other end portion 37b of the rocking member 37 and displaces 
the same out of the passage 33. The rocking member 37 is turned in 
clockwise direction so as to assume its first position. In the latter 
position the gripping member 5" can be displaced by the user either by 
hand or via the member 23. 
It will be understood that each of the elements described above, or two or 
more together, may also find a useful application in other types of 
constructions differing from the types described above. 
While the invention has been illustrated and described as embodied in an 
arrangement for opening and closing a film sheet cassette and a film sheet 
cassette provided therewith, it is not intended to be limited to the 
details shown, since various modifications and structural changes may be 
made without departing in any way from the spirit of the present 
invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention.