Electrical alarm system

Claim 2

An electrical alarm system, comprising a plurality of protected stations and a remote monitoring station connected to all of the protected stations by transmission lines, each of the protected stations including a condition sensing device capable of transmitting a signal along said lines to said monitoring station when an abnormal condition exists at the protected station, a master signal detector provided at the monitoring station and simultaneously monitoring the sensing devices of all the protected stations, an individual signal detector at the monitoring station, and a selector switch at the monitoring station for transferring from said master detector to said individual detector an abnormal condition signal originating at any particular protected station, whereby that particular protected station may be monitored by the individual detector in exclusion of all the other protected stations which continue to be monitored by said master detector.

Claim 3

The system as defined in claim 1 together with a plurality of indicator lamps provided at said monitoring station and energizable by abnormal condition signals from the respective protected stations, said selector switch being manually actuated and having a plurality of settings corresponding to the respective protected stations, whereby an abnormal condition signal from a particular protected station as indicated by its respective lamp may be transferred from said master detector to said individual detector by an appropriate setting of said manually actuated selector switch.

Claim 4

The system as defined in claim 1 which is further characterized in that said condition sensing device of at least one of the protected stations is responsive to sound and transmits an abnormal condition signal to said monitoring station when sound at that protected station reaches a predetermined threshold level.

Claim 5

The system as defined in claim 1 which is further characterized in that said condition sensing device of at least one of the protected stations is responsive to temperature and transmits an abnormal condition signal to said monitoring station when temperature at that protected station reaches a predetermined degree.

Claim 6

The system as defined in claim 1 which is further characterized in that said condition sensing device of at least one of the protected stations is responsive to a manually actuated switch and transmits an abnormal condition signal to said monitoring station when said last mentioned switch is actuated.

Claim 7

An electrical alarm system comprising a plurality of protected stations and a central monitor station connected to all of the protected stations by transmission lines, each of the protected stations including means for producing audio frequency electrical signals, and means for coupling said audio frequency electrical signals to said transmission lines for transmission to said central monitor station; said central monitor station including a master loudspeaker for simultaneously monitoring the audio signals from all of the protected stations, an individual loudspeaker for individually monitoring the audio signals from only one protected station at one time, a multiposition selector switch, said selector switch having a standby position, means at said standby position for connecting audio frequEncy signals from all of said protected stations to said master loudspeaker while excluding all the audio frequency signals from said individual loudspeaker, a plurality of site positions corresponding in number to the number of protected stations, means at each of said site positions for singly connecting audio frequency signals from the protected station corresponding to said selected site position to said individual loudspeaker and for simultaneously connecting the audio frequency signals from all of the protected stations exclusive of the selected protected station to said master loudspeaker, and means provided at said monitoring station for coupling the audio frequency signals from each of said protected stations to said multiposition selector switch.

Claim 8

An electrical alarm system comprising a plurality of protected stations and a central monitor station connected to all of the protected stations by transmission lines, each of the protected stations including means for producing audio frequency electrical signals, and means for coupling said audio frequency electrical signals to said transmission lines for transmission to said central monitor station; said central monitor station including a master loudspeaker for simultaneously monitoring the audio signals from all of the protected stations, an individual loudspeaker for individually monitoring the audio signals from only one protected station at one time, a multiposition selector switch, said selector switch having a standby position, means at said standby position for connecting audio frequEncy signals from all of said protected stations to said master loudspeaker while excluding all the audio frequency signals from said individual loudspeaker, a plurality of site positions corresponding in number to the number of protected stations, means at each of said site positions for singly connecting audio frequency signals from the protected station corresponding to said selected site position to said individual loudspeaker and for simultaneously connecting the audio frequency signals from all of the protected stations exclusive of the selected protected station to said master loudspeaker, and means provided at said monitoring station for coupling the audio frequency signals from each of said protected stations to said multiposition selector switch.

Claim 9

The apparatus set forth in claim 6 wherein said audio frequency producing means at each of said protected stations includes at least one sound transducer for picking up sounds produced in the region of the protected station.

Claim 10

The apparatus set forth in claim 7 wherein said audio frequency producing means also includes an audio frequency oscillator, and at least one means for keying said oscillator when an abnormal condition occurs in said protected station.

Claim 11

The apparatus set forth in claim 8 wherein there are plural diverse means for keying said oscillator, each keying means being responsive to a different abnormal condition and keying said oscillator in accordance with a preselected code indicative of the abnormal condition to which said keying means responds.

Claim 12

The apparatus set forth in claim 9 wherein at least one of said keying means includes a rotary periodic switch encoder in circuit with an abnormal condition sensing switch and a power supply for energizing said oscillator, said abnormal condition sensing switch being normally open in the absence of an abnormal condition and being closed upon the occurrance of an abnormal condition whereupon energy from said oscillator power supply is intermittently applied to said oscillator through said encoder in accordance with a predetermined code pattern.

Claim 13

The apparatus set forth in claim 7 wherein said sound transducer is a microphone and wherein said means for coupling said audio frequency signals from said sound transducer to said transmission lines is a coupling transformer having a centertapped secondary winding, each protected station further having an audio amplifier interposed between said microphone and said coupling transformer, a power supply for energizing said audio amplifier and microphone, an audio noise generator in circuit with said amplifier power supply and a normally open relay switch, said normally open relay switch having an energizing coil in circuit between said center-tapped secondary winding and ground, said monitor station further having a grounded power source for energizing the coil of said relay switch in each remote station through said transmission lines and circuit means for separately connecting said grounded power source to the transmission lines between each protected station and said monitor station including a test lamp means in each circuit means for indicating the operative condition of the protected station, and a test switch means paralleling said test lamp for applying a sufficient energy from said grounded power source to said relay coil when said test switch is closed to activate said relay switch whereupon said noise generator is energized to produce sound in said protected station which is picked up by said sound transducer and monitored in said monitor station.

Claim 14

The apparatus set forth in claim 6 together with a plurality of indicator lights at the monitoring station, there being one indicator light for each protected station, separate audio frequency signal responsive means at said monitoring station for each protected station for energizing the indicator light associated with a particular protected station when an audio frequency signal above a preselected threshold level is received and for dEenergizing said indicator light when the audio frequency signal falls below said threshold level.

Claim 15

The apparatus set forth in claim 12 together with an audible alarm in normally open circuit with all of said indicator lights, said multiposition selector switch having means at said standby position for closing said normally open circuit between said audible alarm and said indicator lamps so that said audible alarm will sound whenever one of said indicator lights is energized.

Claim 16

The apparatus set forth in claim 6 wherein said selector switch is a multideck rotatable switch having multiple equally spaced fixed contacts circularly arranged on each deck, one deck having an annular rotatable conductor of smaller diameter than the inside diameter of the circle of contacts in said one deck, an arcuate segment extending radially outwardly from said annular conductor for separately engaging one of the fixed contacts at a selected position of said selector switch, a fixed brush in continuous engagement with said annular conductor and circuit means connected to said brush for transmitting signals from said brush to said individual loudspeaker, the fixed contacts of said one deck at said site positions being individually connected to receive audio frequency signals from one of the protected stations so that when said arcuate segment engages any one of the fixed contacts in said plural site positions, audio frequency signals appearing at the selected site position will be applied through said annular conductor and said brush to said individual speaker, a second deck having an annular rotary conductor interrupted by a narrow gap of arcuate length less than the distance between two adjacent fixed contacts on said second deck, means associated with each fixed contact in the site positions of said selector switch for wiping said interrupted annular conductor, a fixed brush in engagement with said interrupted annular conductor and circuit means connected to the fixed brush on said second deck for transmitting signals from said brush to said master loudspeaker, the fixed contacts on said second deck at said site positions each being individually connected to receive audio frequency signals from one of the protected stations, the gap on said interrupted annular conductor being in the same angular position as the arcuate segment extending from the annular conductor on said first deck so that when said selector switch is in a standby position the annular conductor on said second deck will be in conductive contact with all of the fixed contacts in the site positions, and the annular conductor on said first deck will be out of conductive contact with all of the fixed contacts in the site positions, and when said selector switch is in one of the site positions only the fixed contact at the selected site position on the first check will be in conductive contact with the annular conductor of the first deck, and all of the fixed contacts of all of the site positions except the selected site position on said second deck will be in conductive contact with said interrupted annular conductor on said second deck.

Claim 17

The apparatus set forth in claim 14 together with a plurality of indicator lights at the monitoring station, there being one indicator light for each protected station, separate audio frequency signal responsive means at said monitoring station for each protected station for energizing the indicator light associated with a particular protected station when an audio frequency signal above a preselected threshold level is received and for deenergizing said indicator light when the audio frequency signal falls below said threshold level, an audible alarm in normally open circuit with all of said indicator lights, said multiposition selector switch having a third deck and means provided on the third deck only at a standby position for closing said normally open circuit between said audible alarm and said indicator lights so that said audible alarm will sound whenever one of said indicAtor lights is energized.

Claim 18

The apparatus set forth in claim 6 wherein said coupling means at said monitor station for coupling the audio frequency signals from each protected station to said multiple position selector switch is included in a site module, there being plural separate site modules corresponding in number to the number of protected stations, each site module having a coupling transformer, an audio amplifier, and means connecting the output of said audio amplifier to a particular site position on said multiple position selector switch, said coupling transformer coupling the audio signals transmitted over the transmission lines from a particular remote station to said audio amplifier wherein the audio signals are amplified.

Claim 19

The apparatus set forth in claim 16 together with a plurality of indicator lights at the monitoring station, there being one indicator light for each protected station, electric power means for energizing said indicator lights, and audio signal responsive means in each site module for energizing the indicator lights associated with a particular protected station when an audio frequency signal above a preselected threshold level is received and for deenergizing said indicator light when the audio frequency signal falls below said threshold level.

Claim 20

The apparatus set forth in claim 17 wherein said audio signal responsive means includes a threshold level adjusting means connected to the output of said audio amplifier for picking off a selected level of the audio output signal, a threshold amplifier connected to said threshold level adjusting means, a detector means for detecting the d.c. level of the audio output signal from said threshold amplifier, a sound operated relay means for opening and closing the energizing circuit to a particular indicator light, and means responsive to the d.c. output from said detector means for energizing said sound operated relay means when the d.c. level is above a certain level and for deenergizing said sound operated relay when said d.c. level is below a certain level.