ALARM MONITORING SYSTEM

• US 3,623,087 A
• Filed: 11/21/1968
• Issued: 11/23/1971
• Est. Priority Date: 11/21/1968
• Status: Expired due to Term

• Current Assignee: John H. Gallichotte, Russell L. Terrell
• Original Assignee: John H. Gallichotte, Russell L. Terrell
• Inventors: Gallichotte, John H., Terrell, Russell L.
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Swann, III, Glen R.
• Application Number:
  US04/777,726
• Time in Patent Office: 1,097 Days
• Field of Search: 340/412,164,147,213.1,213,215,253,255,256,285,292,181,220,276 317/7,235 324/51
• US Class Current: 340/509
• CPC Class Codes: G08B 25/14 Central alarm receiver or annunciator arrangements

Abstract

An alarm-monitoring system including a central station having a plurality of fire alarm indicating and control panels and a plurality of security alarm indicating and control panels, each panel having a plurality of zone sections individually responsive to a remote located alarm-condition responsive device or termination unit. Each zone section includes a sensor which generates an alarm signal at the central station when its associated fire or police alarm condition responsive device detects a fire or police alarm condition at its associated remote protected premise. Each zone section also includes an alarm condition storage device for storing the fact that an alarm condition has occurred, and an alarm condition indicator responsive to the storage device for providing an intermittent visual indication when an alarm condition occurs. Each zone section further includes a sensor for detecting circuit faults at its associated alarm condition responsive device or termination unit, a storage device for storing the fact that a circuit fault has occurred, and a circuit fault indicator for providing an intermittent indication of the detection of such a circuit fault. Each fire and security panel includes means for converting an intermittent indicating alarm signal to a continuous indicating signal. The signal-converting means of each panel is common to all zones of the panel. Each of the zones also includes a printer interface capable of generating, each time one of the zone storage devices changes state, a binary signal indicating the nature of the change and the identity of the zone. Associated with all of the panels and common to each of them is a printer which provides, in response to successive changes in the status of the zones, successive printed records reflecting the nature of the status change, the time and date thereof, and the identity of the zone in which the status change occurs.

Claims

1. An alarm condition responsive termination unit connectable in use between first and second terminals of an alarm-monitoring system, said unit comprising:

resistance means connectable between said first and second terminals, an alarm switch means connected in parallel with said resistance means and responsive to an alarm condition for changing the condition of said switch between first and second states wherein said switch is effectively a closed circuit and an open circuit, respectively, and an electrical polarity responsive switch including a transistor having it emitter-collector path connected in parallel with said alarm switch, said polarity responsive switch being biased to be rendered nonconductive and conductive in response to first and second electrical polarities of said terminals for effectively placing said polarity responsive switch in open circuit and closed circuit conditions, respectively, thereby enabling and disabling, respectively, the capability of said alarm switch to alter the resistance of said unit in response to an alarm.

2. An alarm system comprising:

a plurality of termination units each including a resistance variable between a normal and an alarm value in response to the existence of normal and alarm conditions, respectively, a plurality of monitoring units connected to different ones of said termination units, said monitoring units each comprising;

a. a sensing circuit responsive To the change in resistance of said termination unit for developing an alarm signal at a sensing point, b. a bistable device responsive to said sensing point for switching said bistable device from a normal state to an alarm state when said termination unit is in its alarm condition, said bistable device being unresponsive to switch from its alarm state to its normal state when said termination unit returns from its alarm condition to its normal condition, a strobe signal source for generating a strobe signal each time an alarm signal is produced at one of said sensing points, and a coding matrix comprising;

a. a plurality of normally nonconductive output transistors having their bases connected in different combinations to said sensing points, and b. a plurality of normally conductive inhibit transistors connected to said output transistors to inhibit conduction of said output transistors when said inhibit transistors are nonconductive, said inhibit transistors having their bases connected to said strobe signal source for rendering said inhibit transistors conductive in response to a strobe signal, and thereby enable said output transistors, when alarm signals present at said sensing points are input to the bases thereof, to conduct and provide a combination of output signals unique to the sensing point which actuated the strobe signal source.

3. An alarm system comprising:

a termination unit having a. first and second terminals, b. a first resistance means connected between said first and second terminals, c. an alarm switch means connected in parallel with said resistance means and responsive to an alarm condition for changing the condition of said switch between first and second states wherein said switch is effectively a closed circuit and an open circuit, respectively, d. an electrical polarity responsive switch connected in parallel with said alarm switch, said polarity responsive switch being responsive to first and second electrical polarities of said terminals for effectively placing said switch in open circuit and closed circuit conditions, respectively, thereby enabling and disabling, respectively, the capability of said alarm switch to alter the resistance of said unit in response to an alarm;

a monitoring unit having;

a. third and fourth terminals connectable to said first and second terminals, b. a balanced DC bridge including in one leg thereof relatively positive and negative terminals, c. first and second transistor pairs each having a first transistor connected between said positive output and one of said third and fourth terminals and a second transistor connected between said negative output and the other of said third and fourth terminals, d. control means for alternatively rendering said first and second transistor pairs conductive and nonconductive, and e. sensing means responsive to said bridge for providing a first signal at a first output in response to an alarm condition at said termination unit and a second signal at a second output in response to a circuit fault in said termination unit, and a first bistable multivibrator device connected to said first output of said sensing means for switching said first bistable multivibrator to an abnormal condition in response to said first signal, and a second bistable multivibrator device connected to said second output of said sensing means for switching and second multivibrator to an abnormal condition in response to said signal and connected to said first output of said sensing means for preventing switching of said second device in response to both said first and second signals.

4. An alarm system comprising:

a termination unit having a. first and second terminals, b. a first resistance means connected between said first and second terminals, c. an alarm switch means connected in parallel with said resistance means and responsive to an alarm condition for changing the conditiOn of said switch between first and second states wherein said switch is effectively a closed circuit and an open circuit, respectively, d. an electrical polarity responsive switch connected in parallel with said alarm switch, said polarity responsive switch being responsive to first and second electrical polarities of said terminals for effectively placing said polarity responsive switch in open circuit and closed circuit conditions, respectively, thereby enabling and disabling, respectively, the capability of said alarm switch to alter the resistance of said unit in response to an alarm;

a monitoring unit having a. a balanced DC bridge, b. first and second transistor pairs each having a first transistor connected between one corner of said bridge and one of said first and second terminals and a second transistor connected between an adjacent corner of said bridge and the other of said first and second terminals. c. control means for selectively rendering said first and second transistor pairs alternatively conductive and nonconductive, thereby selectively reversing the polarity applied to said polarity responsive switch and in turn the resistance altering capability of said alarm switch.

5. An alarm system comprising:

a plurality of termination units having a. first and second terminals, b. a first resistance means connected between said first and second terminals, c. an alarm switch means connected in parallel with said resistance means and responsive to an alarm condition for changing the condition of said alarm switch between first and second states wherein said switch is effectively a closed circuit and an open circuit, respectively, d. an electrical polarity responsive switch connected in parallel with said alarm switch, said polarity responsive switch being responsive to first and second electrical polarities of said terminals for effectively placing said polarity responsive switch in open circuit and closed circuit conditions, respectively, thereby enabling and disabling, respectively, the capability of said alarm switch to alter the resistance of said unit in response to an alarm;

a plurality of monitoring units each comprising a. a sensing circuit responsive to the change in resistance of said termination unit for developing an alarm signal at a sensing point, and b. a bistable device responsive to said sensing point for switching said bistable device from a normal state to an alarm state when said termination unit is in its alarm condition, said bistable device being unresponsive to switch from its alarm state to its normal state when said termination unit returns from its alarm condition to its normal condition; and

c. an alarm indicator connected to said bistable device for providing an alarm indication when said bistable device switches to its alarm state, said indication not terminating in response to return of said termination unit from its alarm condition to its normal condition, and identification means associated with each termination unit for providing a termination unit identification signal unique to each unit when the bistable device associated with a unit switches states, and printing means responsive to said bistable devices and said identification means for providing sequential unit-identifiable printed records of sequential changes in state of said bistable devices.

6. The alarm system of claim 5 wherein said printing means includes a strobe signal source for generating a strobe signal each time an alarm signal is produced at one of said sensing points, and a coding matrix comprising:

a. a plurality of output transistors having their bases responsive in different combinations to said sensing points, and being normally in one state, b. a plurality of inhibit transistors connected to said output transistors to inhibit switching of said output transistors when said inhibit transistors are in their normal states, said inhibit transisTors having their bases connected to said strobe signal source for switching said inhibit transistor in response to a strobe signal, and thereby enabling said output transistors, when an alarm signal present at an associated sensing point is input to a base thereof, to switch and provide a combination of output signals unique to the sensing point at which is present an alarm signal.

7. An alarm system comprising:

a first pair of lines each having a remote station end connected to a first terminal and each having a central station end, a second pair of lines each having a remote station end connected to a second terminal and each having a central station end, a first resistor connected between one of said central station ends of said first line pair and one of said central station ends of said second line pair, an AC source having a first terminal coupled to both said central station ends of said first line pair and a second terminal coupled to both said central station ends of said second line pair, a second resistor, a DC source having one terminal connected to the other of said central station ends of said first line pair, and having another terminal connected through said second resistor to the other of said central station ends of said second line pair, an alarm responsive switch connected between said first and second terminals for selectively shunting said first resistor in response to an alarm condition at said remote station, an alarm sensor responsive to the AC potential across said first resistor for providing an alarm signal at its output when said first resistor is shunted by said alarm switch, and a circuit fault sensor responsive to the DC potential across said second resistor for providing a circuit fault signal at its output when said lines of a pair are short circuited and/or when said lines of a pair are grounded.

8. An alarm system comprising:

a first line having a remote station end and a central station end, a second line having a remote station end and a central station end, a first resistor connected between said central station ends of said lines, an alarm switch connected between said remote ends of said lines and responsive to an alarm condition to shunt said first resistor, an AC source connected to said resistor, a second resistor, a DC source connected across first and second resistors, an alarm sensor responsive to the AC potential across said first resistor for providing an alarm signal at its output when said first resistor is shunted by said alarm switch, and a circuit fault sensor responsive to the DC potential across said second resistor for providing a circuit fault signal at its output when said lines are grounded.

9. The alarm signal of claim 8 further including:

alarm and circuit fault bistable devices responsive to said output of said alarm sensor and said output of said circuit fault sensor, respectively, for placing said respective bistable devices in abnormal conditions in response to alarm and circuit fault conditions, respectively, and reset means providing when actuated, a reset signal on a reset line which is connected to said bistable devices for resetting said devices to normal conditions, and reset signal inhibit means connected to said reset line and said bistable devices for inhibiting the resetting of one of said bistable devices for inhibiting the resetting of one of said bistable devices when the other of said bistable devices is in an alarm condition, thereby preventing a single-reset signal from simultaneously resetting both said bistable devices should both said devices be in their abnormal conditions when said reset signal is actuated.

10. A remote alarm condition responsive termination unit connectable in use between first and second terminals of a central station alarm-monitoring system, said unit comprising:

a first resistance means, an alarm switch coNnected in parallel with said first resistance means and responsive to an alarm condition for changing the condition of said switch between first and second states wherein said switch is effectively an open circuit and a closed circuit, respectively, a mode switch connected in parallel with said alarm switch and selectively operable between open circuit and closed circuit conditions for selectively enabling and disabling the capability of said alarm switch to alter the resistance of said termination unit in response to an alarm, a second resistance means, an electrical polarity responsive switch connected in parallel with said second resistance means and responsive to first and second electrical polarities there across for effectively placing said switch in open and closed circuit conditions, respectively, said parallel connected polarity responsive switch and second resistance means being connected with said parallel connected first resistance means and alarm and mode switches to form a series circuit, polarity reversing switch means interconnecting said series circuit and said first and second terminals for selectively reversing the polarity of the potential present across said terminals to said series circuit, and means for jointly operating said mode switch and polarity reversing switch to enable said polarity responsive switch to change state and thereby alter the resistance of the termination unit should the condition of said mode switch be changed when the polarity of the potential present at said terminals is not also changed.

11. An alarm condition responsive termination unit connectable in use between first and second terminals of an alarm monitoring system, said unit comprising:

a resistance means connectable between said terminals, a first selective shunting circuit, including a transistor having an emitter-collector path connected in parallel with said resistance means and adapted to be conductive to shunt said resistance means in response to a first polarity condition at said terminals, and adapted to be nonconductive in response to a second polarity condition at said terminals which is opposite to said first polarity condition, and a second selective shunting circuit connected in parallel with said resistance means, including an alarm switch, said second shunting circuit normally shunting said resistance means, said second shunting circuit being inoperative to shunt said resistance means in response to actuation of said alarm switch produced by an alarm condition.

12. The unit of claim 11 wherein said alarm switch is normally closed, and is open-circuited in response to an alarm condition.