Lock And Alarm

Abstract

A lock and alarm including a bolt and a compression spring located in a bolt casing. A latch is attached to the bolt and moves in a slot to a holding position to retract and hold the bolt. The latch is released to move the bolt to a position where it engages a portion of the receiver. When the bolt is moved off the engaging portion the spring moves it into the receiver and at the same time the latch controls a switch to actuate an alarm.

Description

This invention relates to a locking and alarm system and more particularly to a device which is automatically operated to provide a lock and to trigger an alarm when a normally closed opening, such as a door, is partly opened.

Security devices are often used in addition to conventional locks to protect stores, homes, apartments, and other places against entry by an unauthorized intruder. In the case of a door, conventional door locks usually can be easily forced by an intruder. For example, a simple passage lock, which is part of the door knob, sometimes can be forced merely by inserting a piece of stiff material between the door and the jamb to move back the bolt. Other locks, having keyholes on the outside of the door, can be picked or opened with master keys. In addition none of the foregoing types of locks can provide an alarm when unauthorized entry is attempted.

In the Contreras U.S. Pat. No. 3,402,405, a self-locking burglar alarm system is provided which uses a spring biased bolt arm which extends across and through opposite walls of a housing. An audible alarm and switching means are also located in the housing. One end of the bolt arm engages a latch plate near an opening while the other end is used to move the arm back to extend the spring to cock it. When the window or door on which the alarm is mounted is moved, the end of the arm moves off the latch plate into the opening to provide a lock. At the same time the arm actuates the switching means to trigger the alarm.

While the device of the Contreras patent is operative, it has several disadvantages. First of all, the structure does not lend itself to manufacture to produce a heavy duty lock. In addition, since the end of the arm opposite the one engaging the latch plate extends out of the housing, it can be reached through a window opening, if available, to disable the alarm. Further, the cooperative relationship of the operative end of the bolt arm and the latch plate are such that it is possible for an intruder to move the bolt arm to an inoperative position from outside the area being protected.

It is therefore an object of the present invention to provide a novel, self-locking alarm device of strong and secure construction. In accordance with the invention, the device includes an alarm housing having a bolt casing in its interrior holding a solid and sturdy bolt. An audible alarm and a switching device is also located in the housing. The bolt has a slot along a portion of its length which terminates in an end providing a latching, or rest, position for a latch attached to the bolt. The latch is operated to move the bolt against the force of the spring to place it in its latched position or to place the lock and alarm in the ready position.

The alarm device cooperates with a receiver, also of sturdy construction, which includes an internal shoulder on which the operative end of the bolt rests when the alarm is in the "ready" position. This makes the bolt less accessible to movement by the intruder. When the door or window is moved, the bolt moves off the shoulder to make the lock and also carries the latch pin to actuate the alarm.

The latch pin is generally transverse to the bolt and extends through a plate covering the housing plate through which the latch pin extends. This makes latch pin somewhat more inaccessible to operation by an intruder who could place his hand through a window. In addition, in a preferred embodiment the latch pin is made of two piece construction so that one piece can be removed making it relatively impossible for an intruder to deactivate the alarm.

It is therefore an object of the present invention to provide a self-locking alarm of sturdy construction.

It is a further object to provide a lock and alarm utilizing a bolt which is biased by a compression spring, both the bolt and the compression spring being located in a bolt casing.

A further object is to provide a self-locking alarm device having a movable bolt which engages a recessed lip portion of a receiver.

Other objects and advantages of the invention will become more apparent upon reference to the following specification and annexed drawings, in which:

FIG. 1 is a plan view, shown with the cover and bolt receiver partly broken away;

FIG. 2 is a top view taken in cross-section along lines 2--2 of FIG. 1 showing the device in the "ready" position; and

FIG. 3 is a view similar to FIG. 2 showing the bolt in the actuated position.

The lock and alarm unit includes a lock 10 and a receiver 12. Lock 10 includes a housing 13 of generally rectangular shape preferably formed, such as by casting, from one piece construction from a suitable sturdy metal material. Housing 13 includes upstanding walls 14a, 14b, 14c and 14d each having an internal recessed lip 15 on its upper edge. A number of holes 18 are formed in the housing bottom wall, or through an upstanding post 19 (FIG. 2) to accommodate screws 20 which fasten housing 13 to an operating member such as a door D. The door is of conventional construction and can be of wood, metal or other suitable material.

A tapped hole 22 is formed in an upstanding post 23 formed on top of a bolt receiver casing 25. A screw 26 fastens a cover plate 27 to the housing. Cover plate 27 rests in the lip 15 on walls 14. With the cover plate 27 on, the screws holding housing 13 to the door are unaccessible.

Where housing 13 is of cast construction, a generally rectangular guide bolt casing 25 is also cast with a generally cylindrical interior bore 28 terminating at one end in back wall 29. A guide slot 31 is formed through a portion of the length of casing 25 parallel to the axis of bore 28. A latching slot 33 is also formed in a portion of the circumference of the casing generally transverse to guide slot 31. A latching lip 34 is formed on a portion of one wall of slot 33 to form a notched area, including a wall 35 at the end of guide slot 31, in which a latch pin can latch.

A locking bolt 37 of generally cylindrical shape is slidably carried in the bore 28. Locking bolt 37 is preferably solid, and of rigid metal construction. Bolt 37 has a hole 39 for holding one part, pin 41, of the operating latch 42. The operating latch also includes an extension 43 terminating in a knob 44. Extension 43 is telescoped and force fit over pin 41. Pin 41 can be a roll pin so that it can be held in hole 39 without requiring threading or machining. A coil spring 45 is held between the back wall 29 of casing 25 and a recess 46 in the rear end of bolt 37. Latch member 42 limits the travel of bolt 37 to the length of slot 31.

As seen in FIG. 1, cover plate 27 has a slot which includes a straight portion 48 and a curved or arcuate shaped part 49, forming a latching projection 50. The cover slot portions 48, 49 overlie and are spaced from slots 31, 33 in the bolt casing 25. As seen in FIGS. 2-3, the latching member 42 extends through the slot 48, 49 and is movable therealong.

An upstanding support block 55 is formed on the interior of housing 13 and has a recessed portion between two upstanding walls 56. A switch 58 is mounted between and held in place by a suitable adhesive, such as an epoxy cement. Switch 58 includes leaf-spring members 59a and 59b having respective contact points at one end. Member 59a has an extension lying in the path of travel of latch pin 42. The back end of each member 59 is sandwiched between insulating members 60 mounted on support post 55. The rear end of member 59a is electrically connected to block 55 to place it at the common potential point of an electrical circuit. The circuit includes one or more batteries B held in a conventional battery case 62 suitably fastened to the bottom wall of housing 13. Two batteries B are shown arranged in series circuit with one terminal of case 62 electrically connected by a wire 63 to the rear of switch member 59b and the other terminal connected by a wire 64 to an audible alarm 66. Openings 67 are formed in the cover plate opposite alarm 66 for the alarm sound to pass through. Alarm 66 preferably has a metallic case which is connected to housing 13 and the common potential point. When the contacts of the two switch members 59a and 59b are closed, the electrical circuit is completed and the alarm operates.

The bolt receiver 12 is a case of generally rectangular shape also preferably cast from sturdy metal. A pair of ears extend outwardly and each has a hole 70 therein through which a screw 72 passes to fasten receiver 12 to a fixed point, for example, a door jamb J. A striker plate (not shown) can be part of the receiver 12 to extend transverse to ears 70 into the space between the door and jamb to provide additional structural strength in fastening the receiver to the jamb. Where a striker plate is used the jamb would be recessed to make the plate flush.

The interior of receiver 12 is a hollow cavity 76. A step or ledge 77 is formed across the length of the receiver to provide a lip, or shoulder, 78 against which the operative end of bolt 37 rests when the device is in the "ready" position, as explained below. Receiver 12 is preferably mounted so that shoulder 78 lies inwardly of the edge of jamb.

Both the lock 10 and receiver 12 are mounted on the inside of the areas to be protected. Therefore, they are not visible to an intruder. In general, there will be another lock (not shown) on the door.

To operate the device, the alarm can be placed in an inoperative condition by moving the latch 42 in the cover plate slot 48 against the force of spring 45 to the right, as shown in the figures. It is then moved down and around projection 50. The latch 42 is released and the pin 41 comes to rest in the notched area at the end of guide slot 31 and latches against the wall 35. Locking bolt 37 will clear the receiver so that the door can be opened and closed in the normal manner.

To place the alarm lock in the "ready" position, the door is closed and the latch 42 is moved upwardly back around the projection 50. This moves pin 41 away from shoulder 35 and bolt 37 is moved to the left by spring 45. As seen in FIG. 2 the front end of bolt 37 extends partly beyond housing wall 14b and comes to rest against receiver shoulder 78. Switch contacts 59a and 59b are still open since the latch 42 is spaced away from the extension of 59a. Thus, the alarm will not be actuated. Spring 45 is still partly compressed and has stored energy.

When the door is moved a small amount, as shown in FIG. 3, the end of bolt 37 rides off shoulder 78. The spring 45 is now free to extend and quickly moves the bolt into the receiver locking cavity 76 to form a lock against any further door movement. A large portion of the length of bolt 37 remains in casing 25 to provide a rigid and secure lock. As the bolt moves, latch 42 engages and carries switch member 59a toward member 59b to close the electrical circuit. The alarm sounds, indicating that an attempt has been made to open the door. Thus, the door is locked and an alarm is sounded in the same action.

To stop the alarm, the door is closed and the latch is moved to move the bolt to the inoperative position.

The lock alarm has several advantages. The components such as the housing 10, receiver 12 and bolt 37 are of sturdy construction. In addition bolt 37 which is guided in a strong casing. This reduces the likelihood that the alarm can be disabled by breaking the bolt.

In addition, once the alarm has been set (FIG. 2), the latch extension 43 can be removed. Pin 41 is made of sufficient height to engage switch member 59a even if extension 43 is removed. This is an advantage since, for example, in the case where the lock alarm is used near a window, an intruder cannot disable the alarm by cutting the window, putting his hand through, and moving the bolt back to the inoperative position.

The engagement of the switch contacts by the pin 41, or extension 43 provides positive actuation of the electrical circuit.

The use of the coil spring 43 in casing 25 also provides a positive acting arrangement. The spring is fully concealed and guided in casing 25. It can exert a substantial force to rapidly move the locking bolt into locking position (FIG. 3) and hold it there. Some prior art locking devices, for example, the Contreras patent require that the spring be extended when in the ready position (FIG. 2). This makes the spring more susceptible to breaking.

The fact that the shoulder 78, which engages the end of the bolt in the ready position, extends partly in from the edge of the door jamb edge is also advantageous. This arrangement makes it more difficult for an intruder to insert a device in between the door and the jamb to attempt to move the bolt backward.

Claims

What is claimed is:

1. A lock and alarm device comprising in combination a receiver means including an opening; a housing including a first upstanding wall defining an opening, an elongated guide bolt casing formed on the interior of the housing and having a central bore which terminates at one end in an opening at said first housing wall and at the other end at a wall of said casing, said casing also formed with an elongated through slot into said bore having a first portion generally parallel to the longitudinal axis of the bore along at least a part of the length thereof and a second portion which is at an angle to said first portion, an elongated bolt in said casing bore and a spring between one end of said bolt and said casing wall at said other end of said bore, a cover plate attached to said housing and having a slot formed therein with an elongated generally straight first portion corresponding to said first portion of the casing slot, and a curved second portion including at least a part corresponding to said second portion of said casing slot and defining a projection on the plate, a latch pin attached to and generally transverse of said bolt and movable in said casing slot and having a portion extending through said cover plate slot and movable therein; audible alarm means located in said housing, switch means in said housing connected in electrical circuit with said alarm means and having an actuating means in the path of travel of said latch pin, said pin when moved around said projection in said cover plate and resting in a first position against the wall forming said second portion of said slot to hold said bolt in a retracted position with said spring compressed in said bore, said pin being movable in said first portion of said cover slot from said first position around said projection of said cover plate into an intermediate position when one end of said bolt remote from the end engaged by the spring engages a fixed part adjacent said opening of said receiver means, said one end of said bolt being carried into said receiver opening to a second position by said compressed spring being released as said one end is moved off said fixed part, said pin carried by said bolt as it is moved to said second position engaging the switch actuating means to complete the electric circuit with the alarm means.

2. A device as in claim 1 wherein said latch pin is formed of two pieces, one of which is inserted through the slot on the plate to connect with the other piece attached to the bolt.

3. A device as in claim 1 wherein said switching means includes at least one switch contact mounted on a leaf spring, said leaf spring comprising said switch actuator means which is engaged by said latch pin.

4. Apparatus as in claim 1 wherein said fixed part adjacent said receiver means engaged by said one end of said bolt comprises a step on said receiver means recessed from the exterior of said receiver means.

5. A lock and alarm device comprising a housing including an upstanding wall defining an opening, a guide bolt casing formed on the interior of the housing and having a central bore which terminates at one end in an opening at said housing wall and at the other end at a wall of said casing, said casing also formed with a through slot into said bore having a first portion generally parallel to the longitudinal axis of the bore along part of the length thereof and a second portion which is at an angle to said first portion, a bolt in said casing bore and a spring between one end of said bolt and said casing wall at said other end of said bore, a latch pin attached to said bolt and movable in said slot, audible alarm means located in said housing, switch means in said housing connected in electrical circuit with said alarm means and having an actuating means in the path of travel of said latch pin, said pin when resting in a first position on the wall of said second portion of said slot holding said bolt in its retracted position and said spring in a compressed condition in said bore, said pin when fully released from said first position carried by said bolt as it is moved by the released spring to a second position engaging the switch actuating means to complete the electric circuit with the alarm means, a cover plate for said housing, said cover plate having a slot therein which generally corresponds to the shape of the slot in the bolt casing and is adjacent thereto, said latch pin formed of two pieces, one of which is attached to said bolt and the other of which is inserted through said slot of the plate to connect with said one piece.

6. A device as in claim 5 wherein said slot in said plate has an elongated generally straight first portion corresponding to said first portion of the casing slot, and a curved second portion defining a projection in the plate, said pin being movable in said curved second portion around the plate projection to place said latch pin in said first position.