Lock safety device

The safety device comprises a rotatable lock-operating rotor having a first key slot extending transversely thereof, a non-rotatable inner cylindrical body adapted for fixed securement to a door or the like, and a hollow cylinder embracing the rotor and the cylindrical body and having its inner end fixedly secured to the cylindrical body or member. Key-operable pins, plungers or pistons interconnect the rotor and the fixed cylindrical body to prevent rotation of the rotor. The rotor is formed with a first key slot extending transversely thereof and the hollow cylinder has a closed outer end formed with a second key slot extending transversely thereof. A rotatable diaphragm member is interposed between the fixed outer end of the hollow cylinder and the rotor, and has a third key slot extending transversely thereof. The rotor may be disconnected from the fixed cylindrical member by a key inserted into the first slot to engage the pins, plungers or pistons. The second slot in the fixed outer end of the hollow cylinder is normally angularly aligned with the third slot in the rotatable diaphragm, and the second and third slots extend at an angle, such as 90.degree., to the first key slot in the rotor to block access to the pins, plungers, or pistons. The key has a stem with a transverse bar on its inner end.

FIELD AND BACKGROUND OF THE INVENTION 
The present invention relates to a safety device for locks which utilizes a 
rotatable diaphragm interposed between the key opening and the operating 
portion of the lock. 
There are presently known many types of so-called `safety` locks which in 
effect are not so inasmuch as the operating portion of the lock is easily 
accessible from the outside through the opening in which the key is 
inserted. It is for this reason that the so-called `safety` locks can be 
easily opened from the outside by the use of lock picks and other 
commonly-known burglar tools. 
SUMMARY OF THE INVENTION 
To eliminate these particular problems and to provide locks which are truly 
`safety` locks, the present invention provides a rotatable diaphragm which 
is interposed between the key opening and the operating section of the 
lock, this rotatable diaphragm being acted upon by means of the key 
itself, when the key is partially inserted in the key opening, in a way 
such that it is impossible to arrive at the tumbler pins or other 
operating means of the lock by the use of lock picks or other types of 
burglar tools through the key opening.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
A typical lock of the head cylinder type is substantially composed of a 
cylindrical body 1 integral with a terminal flange 2 for fixing the lock 
to the door body and by a rotor 3 provided at its outer end with a slot 4 
through which the end 5 of the key 6 is inserted. On the inside, between 
the fixed body 1 and the rotor 3, there are located the conventional 
spring-actuated tumblers or pistons. 
The assembly of the body 1 and of the rotor 3 is contained in a hollow 
cylinder 7 closed at one extremity by a plate 8 having an opening 9 
therein which permits the entrance of the end 5 and of the stem 6 of the 
key, cylinder 7 being attached by conventional means to flange 2 and/or to 
fixed body 1. 
The conventional mode of operation of such a lock is known and may be 
briefly described as follows: the key 6 is introduced through the opening 
9 of the hollow cylinder 7 and the end or head 5 can freely enter into the 
slot 4 of the rotor 3, in a manner such that each tooth of the head 5 
pushes, in operating contact with the individual springs, the operating 
pistons or tumblers located between the rotor 3 and the fixed body 1, 
bringing them to the level of the plane of separation between the rotor 3 
and the body 1. In so doing it is possible to effect the rotation of rotor 
3 with respect to body 1 thus also effecting the rotation of the command 
stem of the lock. It is also evident that, inasmuch as the opening 4 of 
rotor 3 remains aligned with the fixed opening 9 of hollow cylinder 7, the 
pistons located on the inside of rotor 3 are easily accessible from the 
outside. It is therefore possible to actuate said pistons or tumblers from 
the outside by the use of these lock picks or other burglar tools, in the 
same manner in which operates the end or head 5 of the key. 
The safety device of the present invention provides essentially the 
interposition of a diaphragm, indicated in its whole as 10, substantially 
consisting of a small cylinder 11 positioned between the rotor 3 and the 
plate 8 of the hollow cylinder 7. Such rotatable diaphragm has preferably 
a width or diameter corresponding to the transverse length of the key head 
5 and consequently it is necessary to increase by the same amount also the 
interior dimension of the hollow cylinder 7. The rotatable diaphragm 11 is 
provided with an opening 12, corresponding exactly, in plan view, to that 
of the opening 9, which extends through the entire width of diaphragm 11. 
According to the invention, there may be also provided spherical bearings 
13, spring-biased, capable of engaging, in at least two positions at right 
angles with respect to each other, suitable seats provided on interior 
face of plate 8, these bearings assuring at least two fixed positions at 
which, respectively, the opening 12 coincides with the opening 9 or with 
the slot 4 of the rotor 3. 
The operation of the device of the present invention can be briefly 
summarized as follows: the lock is mounted with the parts thereof in a 
position whereby they may rotate exactly with respect to each other as 
indicated in FIG. 1. In particular, above the standard fixed body 1 and 
the rotor 3, there is located the rotatable safety diaphragm 10 in a way 
such that the key opening slot 12 extends at a right angle with respect to 
the opening 4 of the rotor. The assembly is then positioned and fixed with 
respect to hollow cylinder 7 in a manner such that the opening 12 
coincides angularly with the opening 9 of the plate 8. The key is inserted 
through the opening until the head 5 engages completely the rotatable 
diaphragm 12 (the key cannot proceed any further since the head 5 is at a 
right angle with respect to the opening 4 of the rotor). 
Following this, the key is rotated through 90.degree., such rotation moving 
the rotatable diaphragm 10 to a position where opening 12 corresponds to 
opening 4 of the rotor. The key can then be inserted further into the body 
of the lock, in a manner that the head 5 enters through the opening 4 and 
activates the pistons or tumblers to rotate the rotor 3 with respect to 
fixed body 1, so as to activate the main stem of the lock. 
It is evident from the preceding description that, in a rest position, it 
is impossible to contact from the outside, without the correct key, the 
pistons or tumblers located between the rotor 3 and the fixed body 1, 
inasmuch as the aligned openings 9 of the hollow cylinder 7 and 12 of the 
diaphragm 10 are at a right angle with respect to opening 4 of rotor 3. It 
is to be noted as a particular characteristic of the present invention 
that the rotatable diaphragm not only prevents the opening of the lock by 
means of lock picks or similar devices but also avoids the possibility 
that imprints be made for the purpose of manufacturing false keys. 
It is to be finally noted that, even if the diaphragm is made to rotate by 
any illegal means and the rotatable diaphragm 10, through the opening 9 of 
the hollow cylinder 7, is made to be positioned with its opening 12 
aligned with opening 4 of the rotor 3, one still does not have access to 
the interior of the lock since the opening 9 is always at right angle to 
the opening 4. 
It is also to be considered that the use of the safety diaphragm 10 does 
not complicate in any way the opening and closing operation of the lock 
and this is particularly due to provision of positioning means 13 and to 
the other means already known in the art, such as automatic spring-driven 
means for the partial expulsion of the key, off-centered keys, or similar 
means. 
The invention has been particularly described with reference to a barrel or 
cylinder lock but it is evident that it automatically extends to any other 
type of combination locks, both to those in which the pistons or tumblers 
are oriented parallel to the key axis and to those in which the pistons or 
tumblers are oriented perpendicular to the key axis. Variations to be made 
to the object of the present invention to apply to various types of locks 
should be evident to those skilled in the art in the light of the present 
disclosure. 
While only one embodiment of the invention has been described, it should be 
now possible to one skilled in the field to arrive at numerous variations 
and changes in connection therewith, which variations and changes should 
be considered as falling within the scope of the present invention.