US2740960A - Alarms - Google Patents

Description

April 3, 1956 KlNzLER 2,740,960

ALARMS Filed Dec. 20. 1952 INVENTOR. DA v/ o [6 NZ'L 5e.

ATTORNEK United States Patent ALARMS David Kinz'ler, Kew Gardens, N. Y. Application December 20, 1952, Serial No.'s2'7,11s

1 Claim. (Cl. 340*403 The present invention relates to alarms and, more particularly, to burglar alarms which are especially adapted to be mounted on doors to warn of any intruders who attempt to enter.

The principal object of my invention is to produce an improved simple alarm which can be conveniently mounted on a door to signal when the door is opened.

A further object of my invention is to provide an alarm which may be alternatively set to signal every time the door is opened or which will signal only when the door is opened without unlocking a conditioning means at the option of the user.

Another object of my invention is to provide an alarm which may be put in ready condition by a key when the user is on the outside of the place being protected.

Yet another object of my invention is to provide an alarm which when once started, will continue ringing even after the door has been closed and until the alarm has been manually turned off.

The above object, and other objects which will become apparent as the description proceeds are accomplished by providing a bell, as an arbitrary selection of signal means, which is connected to one side of a power supply through two switches which are connected in parallel with each other, and to the other side of the power supply through a switch which is operated by the opening and closing of the door and preferably also through the bell hammer which engages an electrical contact in its back stroke completing a circuit in parallel with the door switch.

The following description of my invention will be best understood by reference to the accompanying drawings which illustrates a preferred embodiment and in which like reference numerals refer to like parts in the two figures employed, and in which:

Figure 1 is a view, partially diagrammatic, showing my improved alarm with an operating circuit therefor; and

Figure 2 is an enlarged fragmentary view of a portion of Fig. I particularly showing the bell hammer and its associated electrical contact.

The alarm unit of my invention is especially adapted to be conveniently mounted on the back of any door or other closure to give an alarm when the door is opened. The alarm unit is generally comprised of an alarm mechanism such as an electric bell 11, a power supply 12 and associated switches and wiring mounted within a metallic housing 13. The bell is mounted in the top part of the housing and has the usual gong 14 and the associated hammer 15 operated by an electromagnet as commonly employed in the art within the casing 16 through which the hammer 15 protrudes to enable it to strike the gong 14.

The power supply 12 for operating the gong is preferably a battery supply as schematically shown in Fig. l and is mounted in the lower part of the housing 13.

The housing 13 is mounted next to the swinging edge 17 of the backside of the door 18. A switch 19 is pro vided which functions when the door 18 is moved into 2,740,960 Patented Apr. 3, 1956 2 or out of contact with the door jamb 21. The specific switch .19 here shown is comprised of aspring arnr 22 mounted within the housing and insulated therefrom. The arm 22 extends through an opening 23 in the sideOf the housing 13 and projects beyond the swinging edge 17 of the door.

When the door is in other than closed position, the spring arm 22 contacts the housing 13 at the back edge 24 of the opening 23. The arm 19 is curled toward the door jamb '21 so that when the door is closed, the arm 19 will be moved out of contact from said back edge 24, thus eliminating all electrical contact of the arm 19 with the housing 13. p

In the circuit as shown, one side, which for identifying purposes, will be termed the positive side of the power supply 12, is connected to the switch arm 22 and thence to ground (the housing 13), when the door is open and the arm 19 makes contact with the housing 13. One ter-' minal 26 of the electromagnet of the bell 11 is also connected to the housing 13 thus connecting said positive side of the power supply to the bell 11 when the switch 19 is closed. The other terminal 27 of the bellll is connected to what will be termed the negative side of the power supply through a switch 28. The switch 28 is mounted in the side of housing 13 so as to be operable from the outside of the housing.

When the switch 28 is closed, a circuit will be completed through door switch 19 whenever the door is moved from the door jamb 21.

According to my invention, the alarm system may be conditioned from the outside of door 17. To accomplish this, a key switch 29 is connected in parallel with the switch 28 so that the alarm circuit may be conditioned or readied from the front or outside of the door 17. The key switch 29 is mounted in the door 17 so that it may be operated by a key 30 from the front or outside of the door, and by proper turning of the key, an electrical connection may be made to the switch terminals from the inside of the housing 13. Thus the alarm may be put in ready condition from the outside of the room in consequence of which any opening of the door will cause a signal, such as ringing of the gong, to result.

The key switch 29 may comprise a drum or armature 31 having four contact brushes 32, 33, 34 and 35 spaced therearound. Opposite brushes 32 and 34 are connected to the terminals of the switch and brushes 33 and 35 are connected to each other. Covering approximately one quarter of the circumference of the armature and spaced opposite to each other, with non-conductive portions between, are two conductive portions or arcuate bus-bars 36. In open position of the switch, the conductive portions 36 are directly opposite and contacted by brushes 32 and 34 respectively, but as those brushes are merely connected one to the other, no electrical circuit is completed in this position of switch. The circuit through the switch is completed by turning the armature so that each conductive portion 36 electrically connects two adjaccnt brushes together, as 32 to 33 and 34 to 35 and in that condition the switch closes a series line from the battery to the bell.

As a feature of my invention, the alarm is so constructed that the bell 11 when once started will continue to ring even though the door is closed and the switch 19 thereby opened. To accomplish this, a spring contact 40 may be mounted close to the hammer of the bell 11 so that the hammer on its back stroke engages the spring contact. Said spring contact is insulated from the housing 13 and is connected to what has positive side of the battery. The bell hammer is grounded to the housing thereby completing a circuit from the battery 12, through whichever switch 28 or 29 is closed, through the eleetromagnet of the bell 11 to ground, from ICC been termed the ground through the bell hammer 15 and the spring contact 40 and then back to the battery 12. This circuit will cause the bell to continue ringing until the closed switch 28 or 29 is opened.

Referring to Figs. 1 and 2, it can readily be seen that I have provided an alarm which may be conditioned or readied from either side of the door on which the alarm is mounted. If the person readying the alarm is on the inside, a switch 28 may be closed. If the person is on the outside, the alarm may be readied by turning key switch 29. After either switch 28 or 29 has been closed, any movement of the door from its jamb 21 will close the door switch 19, which'is normally held open by the jamb 12, and the circuit through the bell 11 will be completed. The circuit through the bell 11 will be maintained, according to the showing of Figs. 1 and 2, even if the door switch 19 is then opened, by virtue of the bell hammer 15 striking the spring contact 40 on its back stroke. It should be noted that the bell hammer 15, while ringing, moves backward from the gong 14 a distance which is greater than its normal rest position. Thus the hammer 15 will contact a spring contact 40 only on its backstroke.

While I have shown an alarm unit mounted on the door, it is to be understood to be within the scope of the invention to mount the unit on the door jamb, if

convenient, and mount the key switch 29 on the outside of the jarnb. My invention is not limited for use with doors, but may be used with any movable closure, for instance, such as a window.

Iclaim:

An alarm comprising an electric bell having a gong and having vibratory mechanism including a hammer for sounding said gong, a spring engageable by said hammer on reverse stroke of the hammer from the gong, said mechanism providing an electric circuit including said spring and hammer wherein said hammer in its normal position is out of contact from said spring and completes the circuit when vibrated to pass its normal position on reverse stroke, and means to instigate vibration of said hammer.

References Cited in the file of this patent UNITED STATES PATENTS 662,803 Murphy Nov. 27, 1900 908,848 Eden Jan. 5, 1909 1,236,526 Zabel Aug. 14, 1917 1,758,523 Kertz May 13, 1930 2,287,572 Rodth June 23, 1942 2,436,470 Fleming Feb. 24, 1948

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