US 3587081 A
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United States Patent inventors Paul M Hawkins Alton Township, Washington County; Allan E. Reynolds, Shoreview, both of,
' Minn. App]. No. 833,387 Filed June 16, 1969 Patented June 22, 1971 Assignee Minnesota Mining and Manufacturing Company St. Paul, Minn.
PICK RESISTANT LOCK AND ALARM 9 Claims, 4 Drawing Figs. v
US. Cl 340/274, 70/268, 200/44, 200/61 .66 Int. Cl ..G08b 13/08, H01h 27/06, E05b 43/00 Field of Search 340/274, 275, 276; ZOO/61.66, 44; 70/267, 268, 269, 419, 439
References Cited UNITED STATES PATENTS 7/1900 Carleton 340/274 4/1928 Watts 200/61 .66 X
6/1936 Thompson 70/419 10/1936 Golokow et a1 ZOO/61.66 10/1936 Maxwell et a1 70/419 X 5/1943 Welch 70/268 X 7/1949 Chaulk et a1... ZOO/61.64 X 10/1967 Luna et a1 340/274 X Primary Examiner-John W. Caldwell AssistantExaminer-Scott F. Partridge Attorneyl(inney, Alexander, Sel1, Steldt& Delahunt ABSTRACT: A pin-tumbler type lock in combination with a cam operated upon rotation of the plug to operate a switch connected in circuit relation with a delay device such that upon attempted picking of the lock cylinder the incremental rotation of the plug will operate the switch which if operated for a period of time exceeding that preset time of the delay device will sound an alarm.
PICK RESISTANT LOCK AND ALARM This invention relates to an improvement in security devices and in one aspect to an improved lock structure for energizing a signal upon abnormal and unauthorized manipulation of the lock cylinder.
Various types of alarm actuating mechanisms are known which are designed to produce a signal or operate an alarmof some type upon the attempted unauthorized entry through .the lock. Pin-tumbler locks had been regarded as being substantially invulnerable but various methods have been devised for defeating such 'locks and they no longer stand as complete protection against unauthorized entry. For example,'professionals have devised tools for picking locks and the conventional pin-tumbler locks can be picked with considerable speed. For example, in "picking" a lock of the pin-tumbler type, the intruder will insert a torque tool into the keyway so asto exert a torque or leverage on the plug upon the application of pressure with one hand permitting the other hand to apply a picking tool" to the pintumblers. As he gradually raises the tumblers to a position where their upper edge meets the parting line between the plug and the cylinder he may hold them in that position and continue pickingthe other tumblers.
Attempts have been made therefore to devise various keyways, drivers and key constructions to hamper the speed or the possibility of picking the locks. The provision of a specific type of driver known as a "mushroom pin is shown in U.S. Pat. No. 2,043,205. This patent discloses a mushroomheaded driver which will become cocked and prevent rotation of the plug beyond a predetermined extend upon the application of a tension to-the plug during picking. U.S. Pat. No. 1,860,712 is another example of an antipick tumbler lock.
Patents have shown the combinations of locks and switches for producing a signal if an unauthorized attempt is made to operate the lock, either by picking or by a key other than the proper key. Examples of such combinationsare U.S. Letters Pat. Nos. 2,057,301; 653,132 (July 3, 1900); and 3,444,546.
The structure of the present invention of the present invention provides an improved reliable pin-tumbler lock which itself offers resistance to presently known methods of overcoming a lock in conjunction with a structure for sounding an alarm or giving a signal in the event an attempt is made to pick the lock or enter with an improper key.
The present invention comprises.apin-tumbler-type lock cylinder wherein at least one of the drivers is a conventional cylindrical driverreceived in the bores through the cylinder and plug and at least one of the other drivers is formed with a reduced intermediate portion. The invention further includes a cam associated with the plug of the lock cylinder such that rotation of the plug rotates the cam, said cam being formed with spaced lobes such that upon rotation of the camin either direction from a normal locked position, a switch will be actuated by engagement of a follower arm with a lobeon the cam. The switch is connected in circuit with a signalling device, and included in the circuit is a timed delay device such that-energization of the circuit by the switch is not sufficient in and of 6 lines 3-3 of FIG. 1; and
FIG. 4 is a detailed view of a cam.
Referring now to the drawings, there is illustrated a pintumbler type cylinder lock comprising a cylinder having a bore 11 in which is mounted a key plug 12 having a series of pin-tumblers 14 mounted in bores 15 in the usual manner. Aligned with each plug tumbler bore 15 is a driver bore 16 located in the cylinder 10 and containing a spring 17 for pressing the driver down against the tumbler 14. In the illustrated to 6 tumbler bores and 6 driver bores are positioned axially along the keyway. In the rearmost driver bore is positioned a driver .19 which is uniformly .cylindrical from end to end and biased by a spring 17 against the associated tumbler 14 in the tumbler bore 15. The other drivers indicated by the reference numeral 20 are constructed to afford slight relative movement between the plug and cylinder and as illustrated have a reduced intermediate portion giving them the general shape of miniature dumbbells comprising uniform end portions connected by an intermediate bar at their axis, however the drivers could be undersized with respect to the bores. The pin tumblers have different axial lengths to permit in various locks various key combinations as is well known in the art. Thedrivers 20 permit limited rotational movement of the plug 12 whether or not all the drivers 20 are raised by thepins to the parting line between the plug 12 and in the bore 11.
.In the structure illustrated the driver 19 normally maintains the plug in the cylinder in aligned position. When the proper key is inserted all of the pin-tumblers lift the drivers such that one end thereof is positioned at the parting line. The plug 12 may thus be rotated to turn a spindle 22 extending axially of the plug and connected for rotation thereto. If one attempts to pick the cylinder of the present invention it is necessary that he apply a torque to the plug with one instrument and insert a .picking tool into the keyway to work the pin tumblers upward in their bores to position the lower ends of thedrivers at the parting line. The first driver which will be picked is the driver which is tight or bound in the bores when the torque is applied and in the illustrated construction it will mean the driver 19 will be picked first. The torque placed on the plug after picking the driver 19 will permit rotation of the plug 12 and of the spindle a few degrees,.e.g. from 3 to 20, from a normal position, either to the right or left before the plug binds due to the presence of the dumbbell drivers 20.
The cylinder is mounted in a bore 25 in a door structure 26 between a bezel plate 27 in which are mounted semiannular rings 29 and 30 formed with aL-shaped cross section to support the shouldered portion on the face of the cylinder 10 and a mounting plate 31 on the opposite side of the door. The connecting elements between the cylinder and the mounting plate 31 are axially extending threaded bolt members 32, which extend from a second deformable mounting plate 34 positioned over the plate 31, on the side opposite the cylinder 10 and spanning the area where plate 31 is offset as at 35 to fit within the bore 25 in the door or building member 26, into threaded bores in the'lock cylinder 10. The members 32 are drawn up tight topull the cylinder l0.against the semiannular members 29 and 30, and inturn, against the bezel plate 27 to secure the cylinder in position.
Supported in the offset portion 35 of the plate 31 is a cam 0 36 which includes an axial trunnion 37 fitting through and journaled in an opening 38 in the plate 31, a shoulder 39 0f the ward from the otherwise generally circular periphery of the cam surface 40. A cruciform opening 43 is formed axially through the middle of the cam 36 and is adapted to receive the spindle 22. The lobes 41 and 42 are spaced circumferentially on the surface 40, and in the normal position of the plug 12, the lobes-41 and'42 are on opposite sides of a cam follower arm 44.
The follower arm 44 is positioned to operate and is connected to a switch 45 and is'biased toward and into engagement with the cam surface 40. The switch is normally open or closed, depending on the type of circuit employed, and is operated by plunger 46 which is engaged by the arm 44 to locking member, said system comprising move the contacts in the switch. The switch 45 is mounted by suitable screws 49 to the offset portion 35 of the plate 31.
The switch 45 is connected in a circuit and closes or opens the circuit upon operation of the plunger 46 under the force of the follower arm 44. The circuit in which the switch 45 is a part includes a time delay circuit and may include a signalling means for producing an audible, visual or electrical signal. As illustrated, a horn 50 is energized through the time delay circuit 51 which time delay circuit is connected to a power source 52 and receives the actuating signal from the switch 45 to close the circuit to the born 50 upon the lapse of a time interval exceeding a predetermined set time interval.
In normal operation of the lock of the present invention the proper key may be inserted in the keyway of the plug 12 to raise the pin tumblers to the parting line and to rotate the plug. As the plug rotates the spindle 22 it rotates the cam 36 and cam surface 40 such that one lobe 41 or 42 will close the switch 45. In normal operation however to withdraw a bolt from the door the switch 45 will remain closed only momentarily to open the door and only momentarily as the key is returned to the position at which it may be withdrawn from the lock. Thus the period of time for which the delay circuit 51 will be energized is sufficiently short that the circuit will not permit the signal energizing means or horn 50 to be energized. In the event one attempts to overcome the lock with an improper key or by picking the lock they may be able to move the driver 19 to the parting line and will apply sufficient torque to the plug l2 to rotate the same in the bore 11 but in this rotation the same will be retarded when one of the drivers 20 becomes bound in the bores of the cylinder and of the plug. This amount of rotation however will be sufficient to move the lobe 41 or the lobe 42 beneath the cam follower arm 44 to close the switch 45. As one continues to try to pick the pin tumblers 14 he will maintain the switch closed for a period of time sufficient to energize the signal generating means or horn 50. The delay circuit 51 may also include a seal-in circuit which will maintain the signal generating means energized even upon the plug 12 being returned toits normal aligned position and the cam surface 40 being returned to its normal position where the cam follower 44 opens the switch 45.
The normal time delay period can be between 1 and 10 seconds, a period of time greater than normally lapsed in operating a lock and a time interval less than the interval required for any skilled lock-picker to overcome a lock having a predetermined number of pin tumblers.
Having thus disclosed the invention what is claimed is: l. A system for detecting the unusual operation of a rotatable member in a lock unit for locking and unlocking the a lock unit including a locking member and a rotatable member having a first normal position and rotatable toward a second position for operating said locking member to move it from a first locked position to an unlocked position, respectively,
a cam connected to and rotatable with said rotatable member, said cam having at least one lobe on its surface,
a signal generating means for producing a signal,
cam follower means engageable with said cam and positioned about said cam to be operated by said lobe as said cam is moved when said rotatable member is moved from said first position toward said second position for operating said signal generating means, and time delay circuit means connected-to said signal generating means for receiving said signal and operative, upon receiving said signal for a duration greater than a predetermined time interval for producing a further signal. 2. A system according to claim 1 wherein said lock unit comprises a key operated pin-tumbler lock having a lock cylinder and said rotatable member being a lock plug, said lock having a lurality of aligned transverse bores in said lock cy lnder and said lock plug and pin and driver means positioned in each set of aligned bores, with at least a majority of said driver means having shape affording limited rotation of said plug relative to said cylinder, and wherein said cam follower means is positioned relative to said cam lobe to be operated upon' said limited rotation of said plug.
3. A system according to claim 3 wherein the shape of said plurality of driver means is dumbbell-like with reduced diameter intermediate portions- 4. In combination a cylinder pin-tumbler lock, including a cylinder having a longitudinal plug bore, a plug in said bore, a plurality of aligned transverse bores in said cylinder and plug, a driver and pin tumbler in each aligned set of bores, at least one of said drivers being cylindrical, at least one of said drivers having a reduced central portion so as to permit slight rotation of said plug relative to the cylinder upon the remaining drivers being raised to the parting line between the plug and cylinder, and upon torque being applied to the plug,
a spindle extending axially of said plug and rotatable therewith,
a circular cam supported for rotation with said plug and spindle, said cam having a pair of space lobes positioned adjacent to each other and on opposite sides of a diametric line through said cam,
a cam follower normally positioned on said cam on said line between said lobes when the transverse bores in said cylinder are aligned with the transverse bores in said plug and movable upon engaging a said lobe,
switch means responsive to rotation of said cam and movement of said follower in response to engagement with a said lobe for generating a signal, and
time delay circuit means for receiving said signal and for energizing a further circuit upon said signal having a duration greater than a predetermined time interval.
5. The combination of claim 4 wherein said lobes are positioned with 3' and 20 on either side of a said diametric line.
6. The combination of claim 4 wherein all but one of said drivers have a reduced intermediate portion between the ends thereof.
7. The combination of claim 4 wherein said predetermined time interval is between one second and 10 seconds.
8. The combination of claim 4 wherein said cam is supported on a spindle connected to and rotatable with said plug and said cam is journaled in a mounting plate for the cylinder.
9. The combination of claim 6 wherein said cylindrical driver is the innermost driver in the cylinder.