US2814795A

US2814795A - Alarm systems

Info

Publication number: US2814795A
Application number: US458140A
Authority: US
Inventors: Robert J Spooner
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-09-24
Filing date: 1954-09-24
Publication date: 1957-11-26
Anticipated expiration: 1974-11-26

Description

United States Patent ALARM SYSTEMS Robert J. Spooner, Essex, Conn.

ApplicationSeptember 24; 1954, Serial No. 458,140

4 Claims. (Cl. 340-213) This invention relates to an electric alarm system, particularly, of the type wherein an energized, normally closed sensing circuit is employed which when opened will effect the closing of a signalor alarm circuit.

In general, the purpose of. this invention is to provide a system having an alarm circuit that will be turned on remainon when activated by the opening of an energized, normally closed sensing circuit. This is of particular value in fire and burglar alarm installations. In such cases the normally closed sensing circuit is equipped with devices that open the circuit when an alarm is desired, and any opening of the sensing circuit causes the alarm to operate. Once the alarm has started again, closing the circuit will not cut off the alarm.

One of the particular objects of the invention is to provide improved energizing sources for the sensing and alarm or signal circuits. Another object of the invention is to provide relay means associated with the sensing and alarm circuits so arranged that when the sensing circuit is open, the relay will be energized sufficiently to close the alarm circuit and remain closed until the system is reset.

Further objects, details and advantages of my improved electric alarm system will appear in the following descriptinnof preferred embodiments of my invention and illustrated in the accompanying drawings forming a part of this specification.

In the drawings:

Fig. 1 is a diagram illustrating an electric alarm circuit in accordance with my invention;

Fig. 2 is a diagram illustrating a modification of the system shown in Fig. l; and

Fig. 3 is a diagram illustrating a further adaptation of the system, wherein diiferent forms of independent electric energy sources are employed for the sensing and alarm circuit of the system.

In general, the electric alarm system in accordance with my invention, includes a sensing circuit A and an alarm circuit B. In each instance the external circuits are not shown, but are indicated by terminals a and a and b and b to which a normally closed sensing circuit external to the system shown and an alarm device, such as a bell, siren, etc., are respectively connected in the usual manner. These sensing and alarm circuits each have its separate energizing supply or source C and D, C and D and C and D in Fig. l, 2, and 3, respectively. Each adaptation is provided with an on and off operating switch SW which may be used in conjunction with a pilot light for checking the external sensing circuit to see that it is in a normally closed condition. An alarm circuit switch SW is provided to be closed after the sensing circuit is found to be in its normally closed condition.

Each adaptation is further characterized by having a relay R which is energized so as to attract an armature Ra, thereby displacing it from its lower contact NC to its upper contact NO, when the external sensing circuit is opened incident to operations of a burglar, fire or other 2,814,795 Patented Nov. 26, 1957 circumstances to be indicated by an alarm device, recorder or other appropriate device.

Each of these systems is primarily powered from the service mains or network, customarily or volts A. 0, indicated at input. However, as will appear in connection with the adaptation Fig. 3 the entire system may be shifted for operation to a D. C. battery or direct current source D in case of power failure in the main or A. C. network.

Referring'particularly to Fig. 1, it will be seen that the A. C. source of the power input is connected through switch SW to the pilot lamp L and shunting resistance S and relay R in series. When switch SW is closed, the current of said A. C. source passes through lamp L and its shunt S as well as through the external sensing circuit which is connected in shunt to the coil RC of the relay R, whereby a current insuflicient to operate this relay R to raise its armature Ra will flow through the relay coil RC. However, when the sensing circuit is opened, the current then flowing through this relay coil RC increases suficient-ly to attract the armature Ra to break with its contact NC and make with its contact NO. In this latter position, the full input voltage of the power source is applied to the alarm circuit connected with terminals b and b as long as both switches SW and SW remain closed. Under these conditions relay R remains energized and the alarm actuated, even though the sensing circuit may be closed again, for example, by a burglar noticing the alarm. To reset the alarm circuit, switch SW has to be opened, whereby the relay R will be deenergized. Switch SW will also be opened, until the sensing circuit is checked by reenergizing it by closing oi switch SW It will be seen that in this embodiment, the energy for the sensing circuit is supplied through the lamp L and its shunt S which is sufficient for the purpose of energizing this sensing circuit across the coil RC of the relay R. While the input is indicated as to be connected directly across a, for example, 110 A. C. power source, obviously if the alarm system is to be operated on a lower voltage, the energy may be derived from a battery or from a secondary of a step-down transformer.

Such well-known step-down transformers are highly practical as source of power for my electric alarm system. The adaptation illustrated in Fig. 2 is shown modified by employing two suitable step-down transformers C and D having their primaries connected in parallel across a 110 volt A. C. power source and their secondaries separately connected for energizing the sensing and alarm circuits A and B, respectively. In this arrangement it will be noted that these energy sources are separated in contrast to the arrangement of Fig. 1, where a single source is used. Yet, the operation of relay R is identical with that in the arrangement in Fig. 1. The two transformers C and D may be combined to a single structural unit.

In the modification shown in Fig. 3, instead of two transformers connected in parallel with the input, the sensing circuit A is normally energized from a step-down transformer C when the latter is supplied with current via the A. C. input of, for example 110 volts, while the alarm circuit B is energized by an entirely distinct source of energy, i. e., a battery D of, for example, 8 volts. In case of power failure in the A. C. supply, the sensing circuit is energized by a portion d for example of 4 volts, of the battery D a tap d of this battery being connected by a conductor d to an upper contact r engaged by an armature Ra of a change-over relay R said armature being biased, for example by a spring (not shown) to assume this position when the relay coil RC is not energized. In this condition, both the sensing and alarm circuits A and B are energized by the battery D or a portion thereof. This operation is important in the event of a failure of the A. C. current source, which is mostly the general power network. It will be noted that in the normal operation of the system, the A. C. current of the network is fed to the transformer C thereby energizing the change-over relay R so that its armature Ra is attracted to engage a lower contact r and thereby connect the secondary of the transformer C to the sensing circuit A. Thus the sensing circuit A is normally energized from the A. C. source through the transformer C and is energized by the battery current only in the event of failure of the A. C. supply. The change-over relay R operates automatically, i. e. the change-over from transformer or A. C. supply to battery and vice-versa takes place without manual actuation and instantaneously.

The parts of the new electric alarm device or system, including relay or relays, switches, pilot light, transformers and/ or battery, may be built into or assembled in a common case to obtain a compact unit.

-It will be clear from the above description that many changes in the system or its circuits may be made without in any way departing from the essence of the invention as defined in the annexed claims.

I claim as my invention:

1. An electric alarm system including a normally closed sensing circuit, an alarm circuit, a source of electric energy for said sensing circuit, a source of electric energy for said alarm circuit, a pilot lamp in the connections between said source of energy and said sensing circuit, a switch for completing the circuit of said sensing circuit and said pilot lamp with its source of energy, whereby said pilot lamp will be energized when said sensing circuit provides a closed circuit, a relay having an energizing coil connected in parallel with said sensing circuit and normally substantially de-energized thereby, said relay having an armature carrying a movable contact element displaceable together with said armature from its normal position to an alarm position when said relay coil is energized upon current increase due to opening of said sensing circuit, said relay being adapted to retain said armature in said alarm position upon opening of said sensing circuit, although the latter is subsequently reclosed, a first fixed contact opposite said movable contact to be engaged thereby when said armature is displaced with said movable contact from said normal position to said alarm position upon energization of said relay coil, said first fixed contact and said movable contact being included in said alarm circuit, a second fixed contact opposite said movable contact to be engaged thereby when said armature is in said normal position while said relay coil is de-energized, said second fixed contact and said movable contact being included in said sensing circuit, whereby upon energization of said relay coil incident to the opening of said sensing circuit and closing of said alarm circuit with its source of energy via said movable contact and said first fixed contact, said movable contact is separated from said second fixed contact to open said sensing circuit which remains interrupted between said latter contacts, until said switch is opened causing said relay upon de-energization of its coil to return its armature to its normal position.

2. An electric alarm system in accordance with claim 1, wherein said sources of energy for said sensing and alarm circuits comprise a pair of transformers having their primaries connected in parallel across an electric energy source and having their secondaries separately connected with said sensing and alarm circuits.

3. An electric alarm system in accordance with claim 1, wherein said source of electric energy for said sensing circuit includes the secondary of a transformer, the primary of which is connected with a source of electric energy and wherein said source of energy for said alarm circuit comprises a direct current battery.

4. An electric alarm system in accordance with claim 3, wherein a relay is connected across said secondary of said transformer and is operable to connect said transformer secondary with said sensing circuit, when said transformer is energized, and when deenergized, the relay operates to connect a portion at least of said alarmcircuit-energizing-battery with said sensing circuit for energizing the same as long as said circuit remains closed.

References Cited in the file of this patent UNITED STATES PATENTS 1,248,942 Sprague Dec. 4, 1917 2,621,240 Kemper Dec. 9, 1952