U.S. patent number 3,603,973 [Application Number 04/720,587] was granted by the patent office on 1971-09-07 for combination fire and burglar alarm system.
Invention is credited to Howard O. Hough.
United States Patent |
3,603,973 |
Hough |
September 7, 1971 |
COMBINATION FIRE AND BURGLAR ALARM SYSTEM
Abstract
A fire and burglar alarm system for providing automatic
detection of a fire or burglary having active and passive
components which are capable of operating at very low power levels
continuously until the components are called upon to indicate a
fire or burglary. The system is provided with alternate sources of
power to insure the reliability of operation. Supervisory circuitry
is provided for giving visual indication that all sensors and
circuitry are in proper operating conditions. Annunciator circuitry
is also provided to give visual indication of exact location or
zone of conflagration.
Inventors: |
Hough; Howard O. (Wayland,
MA) |
Family
ID: |
24894553 |
Appl.
No.: |
04/720,587 |
Filed: |
April 11, 1968 |
Current U.S.
Class: |
340/506; 307/66;
340/521; 340/541; 340/333; 340/584; 340/693.2 |
Current CPC
Class: |
G08B
19/00 (20130101) |
Current International
Class: |
G08B
19/00 (20060101); G08b 019/00 (); G08b 029/00 ();
H02j 009/00 () |
Field of
Search: |
;340/333,409,227,276,228,420,258C ;307/66 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Caldwell; John W.
Assistant Examiner: Partridge; Scott F.
Claims
What is claimed is:
1. A fire alarm system for indicating a fire in a given area
comprising a fire sensor, means for identification of fire area or
zone, means for giving a first audio alarm responsive to said fire
sensor, said fire sensing responsive alarm means being connected in
circuit with said fire sensor, a first power supply for operating
said fire alarm system connected to said fire sensor and a second
power supply, means responsive to a failure of said first power
supply for connecting said second power supply to said fire sensor,
and means for preventing the false activation of said first means
for giving an audio alarm due to electrical transients generated
during the operation of said fire sensor means connected to said
means for giving a first audio alarm, thereby preventing the
activation of said audio alarm by electrical radiations generated
by bolts of lightning and other stray electrical noise, a trouble
alarm and means responsive to the failure of said first power
supply and to malfunction of said second power supply for actuating
said trouble alarm connected to said trouble alarm, means for
sensing a burglary connected in series circuit with said fire
sensor but capable of activating only the trouble alarm but
incapable of inadvertant operation of the fire alarm circuit, and
said burglary sensing means causing said series circuit to be
broken when a burglary is detected, thereby causing said trouble
alarm to activate and said fire alarm remaining in a nonactivated
condition.
2. A fire alarm system as defined in claim 1, but further
characterized by having visual means for indicating the operability
of said first power supply connected in parallel with said first
current source.
3. A fire alarm system as defined in claim 1, but further
characterized by having a third power supply, said means responsive
to a failure of said first power supply for connecting said second
power supply to said fire sensor connecting said third power supply
to said trouble alarm means.
4. A fire alarm system as defined in claim 3, wherein said first
power supply comprises: a transformer having a secondary winding,
means for rectifying an AC current connected to said secondary
winding and means for regulating the output voltage of said current
rectifying means connected to said current rectifying means.
5. A fire alarm system as defined in claim 1, wherein said first
power supply comprises: a transformer having a secondary winding,
means for rectifying an AC current connected to said secondary
winding and means for regulating the output voltage of said current
rectifying means connected to said current rectifying means.
6. A fire alarm as defined in claim 1, but further characterized by
having annunciator means for indicating the location of the fire on
the premises to be protected.
Description
The present invention relates to alarm systems and, more
particularly, to an alarm system for indicating a fire or
burglary.
An object of the invention is to provide a fire and burglar alarm
system which will not be activated by stray electrical
radiations.
A further object of the invention is to provide a fire and burglar
alarm system having alternate sources of power.
Another object of the invention is to provide a fire and burglar
alarm system having alternate sources of power which are provided
with means to prevent a false alarm when the system is switched
from one source of power to another.
A still further object of the invention is to provide a fire and
burglar alarm system having an automatic self-checking means for
indicating the operability of the system continuously.
Still another object of the invention is to provide a fire and
burglar alarm system having all components of the system protected
against attempts to open circuiting or short circuiting the master
alarm by an intruder.
A still further object of the invention is to provide a burglar
alarm system having a battery which is protected at all times from
overcharging from the charge circuit and having means for
indicating when the battery circuit is opened.
Other objects and many of the intended advantages of this invention
will be readily appreciated by those skilled in the art as the same
becomes better understood by reference to the following detailed
description when considered in connection with the accompanying
drawings, wherein:
FIG. 1 is a block diagram illustrating the functional relationship
of an alarm system in accordance with the invention; and
FIGS. 2a and 2b, taken together, illustrate a circuit diagram in
accordance with the invention.
Referring to FIG. 1 which illustrates the functional relationship
of the fire and burglar alarm system embodying the present
invention, there is provided a pair of terminals 11 for supplying
the AC power to the system. The power is supplied by way of a
stepdown and isolation transformer 15 which steps down the voltage
from 117 volts, 60 cycles to 25 volts, 60 cycles. The stepdown
voltage is rectified and regulated by a rectifying and regulating
unit 17 which is connected to the output of a stepdown and
isolation transformer. A ground line bearing the numeral indicia 13
is for connecting all the components of the instant invention which
are to have a connection to ground. The output of the rectifier and
regulator system 17 is connected to the input of the AC isolation
diode unit 19. The output of the rectifier regulating unit is also
connected to the circuit monitor relay 27 which activates upon the
cessation of rectified AC current to switch the unit onto standby
alarm power.
To this end there is provided a standby battery alarm power 29
having switches 26 and 28 in order to connect it into the system. A
diode 25 is also connected from the output of the rectifying
regulator 17 to one of the inputs of the trouble alarm 133. When
the rectified current fails the trouble alarm 133 sounds the alarm.
The output of the AC isolation diode is connected to the battery
charging circuit 35 for supplying the charging current to the
battery 91. The battery 91 is connected continuously by way of a
relay battery power supply circuit 37 to the alarm relay 21 for
supplying the power to the relay in the event of a failure of the
rectified current supply.
The AC isolation diode 19 output is also connected to the alarm
relay 21 supplying the rectified current to the alarm relay unit
for normal operation when operating from the 117-volt mains. The
output of the alarm relay is utilized for controlling the fire
alarm by switching the fire alarm switch 24 and the master alarm
switch 34 to their closed positions. One of the outputs of the
alarm relay 21 is connected to the heat detector 41. This output of
the alarm relay 21 is utilized to supply the current which flows
through the heat detector 41 when activated. The output of the heat
detector is utilized to trigger the master alarm relay 43 for
indicating a dangerous condition wherein there is a fire to be
reported. The output of the master alarm relay 43 is connected to
the input of a constant voltage generator 45. The output of the
constant voltage generator 45 is utilized for operating a battery
protection circuit 33. The master alarm 43 has an output 44 which
is connected to the municipal system to initiate an alarm at the
firehouse and thereby indicate that the protected premises are on
fire.
An output of the battery 91 is also coupled to the battery
protection circuit 33 for operating this circuit. The output signal
from the rectifier and regulator provides the positive driving
voltage to operate the circuit monitor relay 27. The negative side
of relay coil 27 is applied to ground through the battery
protection circuit 33 when operating properly.
The operation of the block diagram illustrated in FIG. 1 is as
follows:
The incoming voltage supplied by the AC 117-volt line from the
power company is stepped down and isolated by the unit 15 rectified
by the rectifier and regulator 17 and directly fed to the circuit
monitor relay 27. In the event of a power failure circuit monitor
relay 27 switches on the standby battery 29 and also causes the
trouble alarm 133 to operate. Additionally, the battery 91 is
provided for supplying operational currents to all the system
components except the trouble and burglar alarm 133. In the event
that the battery 91 malfunctions, then the battery protection
circuit 33 operates the circuit monitor relay 27 which again would
connect the standby battery 29 to operate the trouble alarm 133.
The fire alarm 131 is operated by the alarm relay 21 in response to
the control of the heat detector 41. The heat detector 41 is also
connected to the master alarm relay for operating the master alarm
at a remote indication. A zone annunciator 201 is provided to
indicate the zone or location where the fire has started.
The system is provided with a burglar detector 137 for indication
that the protected premises are being burglarized.
Referring now to FIGS. 2a and 2b, concurrently, wherein the circuit
diagram is illustrated embodying the invention. The two FIGS. 2a
and 2b are interconnected by lines A, B, C, D, E, F, G, H, I,
respectively. Referring to FIG. 2a, specifically to the far upper
left, this Figure has a pair of AC input leads. One of the AC leads
11 is connected to one end of the primary winding 58 of a stepdown
transformer 57. The other end of the primary winding 58 of the
stepdown transformer is connected through a fuse 51 and a switch 52
to the other AC input lead 11.
An indicator light 53 is connected in series with a limiting
current resistor 55. The series combination of the indicator light
53 and the series resistor 55 are connected in parallel with the
primary winding 58 of the transformer 57. The indicator light 53
indicates the presence of the AC power. As in FIG. 1, the number 13
indicates the electrical ground of the system. The secondary
winding 60 of the stepdown transformer 57 has approximately a
28-volt output whenever the input AC voltage is 117 volts. This is
merely given by way of explanation and other suitable voltages can
be found for operating the equipment.
The rectifiers 59, 61, 63 and 65 cooperate to form a rectifying
network for rectifying the AC present on the secondary winding 60
of the stepdown transformer 57. The cathode of diode 59 is
connected to one end of the secondary winding 60. The anode of
diode 59 is connected to the ground 13 and the anode of diode 61 is
connected to ground 13; the cathode of diode 61 is connected to the
other end of the secondary winding 60. A diode 65 has its anode
connected to the cathode of a diode 59 and the cathode of diode 65
is connected to one end of a resistor 67. The diode 63 has its
anode connected to the cathode of diode 61 and the cathode of diode
63 is connected to the cathode of diode 65. Resistor 67 acts as a
current limiting resistor in this circuit and cooperates with Zener
diode 74 to perform as the output voltage regulator.
A parallel filter combination of capacitor 69 and resistor 71 is
connected between the system ground 13 and the other side of
resistor 67. A diode 73 has its cathode connected to the cathode of
a Zener diode 74 and its anode connected to the resistor 67. The
Zener diode 74 has its anode connected through a normally closed
relay switch 26 to the ground 13. The Zener diode 74 limits the
voltage at the cathode of diode 73 to the breakdown voltage of the
Zener diode 74.
An indicator lamp 75a is connected in series with a resistor 77a
for reducing the flow of current in the indicator lamp 75a. The
series combination of the indicator lamp 75a and the series
resistor 77a are connected in parallel with the Zener diode 74 and
indicates the operability of the rectifying network. In the event
that there is no rectified current passing through the diode 73
from the diodes 59, 61, 63 and 65 respectively, then the indicator
lamp 75a is off. A second indicator lamp 75b is connected in
parallel with indicator lamp 75a and is placed in another area on
the premises to be protected to remotely indicate the operability
of the apparatus by indicating the presence of rectified current.
The indicator lamp 75b is connected over lines B and C. Similarly,
the indicator lamp 75b is connected in series with a current
limiting resistor 77b.
A rechargeable battery 91 having a plurality of cells has its
positive end connected to one end of a switch 89. The switch 89 is
provided for connecting and disconnecting the battery 91 from the
circuit. The normally closed switch 89 is operated simultaneously
with the switch 87 which connects the battery by way of a line D to
the switch terminal of switch 104 of the relay 101. The switch 89
connects the battery 91 with the cathode of the diode 83. The anode
of diode 83 is connected to one end of a current limiting resistor
81. The other end of the current limiting resistor 81 is connected
to the cathode of diode 73. The negative terminal of the battery 91
is connected through a fuse 93 which protects the battery circuit
from becoming overloaded. The other end of the fuse 93 is connected
to the cathode of diode 95 and the cathode of diode 95 is connected
to the junction of variable resistor 155 and the emitter electrode
152 of the transistor 151. The anode of diode 95 is connected to
the electrical ground 13. The diode 95 provides a shunt path around
the variable resistor 155 when testing the charge conditions of the
battery. 91, thereby providing protection of the emitter to base
junction of transistor 151, and also diode 95 provides low
impedance path for activation of fire alarm relay coil 119.
The variable resistor 155 has its free end connected to the
electrical ground 13 of the system. The variable resistor 155
controls the charging rate of the battery 91. A pushbutton switch
97 is connected in series with an indicator lamp 99. The
combination of the pushbutton 97 and series connected indicator
lamp 99 is connected between the positive end of battery 91 and the
electrical ground 13. When the pushbutton 97 is depressed the
condition of the battery is indicated by the brightness of the
indicator lamp 99.
A relay winding 101 has one end of its control winding connected
through line E to the cathode of diode 85. The other end of the
control winding 101 of the relay is connected to the parallel
combination of the temperature sensing circuit. The temperature
sensing circuit comprises thermal switch 108a, and resistor 107 is
connected in parallel to the cathode of diode 302, thermal switch
110a, and resistor 109 connected in parallel to the cathode of
diode 301, and thermal switch 112a connected in parallel to the
cathode of diode 300. Any suitable relay with suitable threshold
activation voltage may be used for the relay 101. A suitable relay
is the Sigma Model 42RO-2500S-SIL described in Sigma Relay Catalog,
issued Jan. 1967, publish ed by Sigma Instruments Inc., Braintree,
Mass.
The temperature sensor switch 108a is provided with a parallel
pushbutton switch 108 for testing the circuit, the temperature
sensor switch 110a is provided with a pushbutton switch 110 for
testing its circuit, and the temperature sensor switch 112a is
provided with a pushbutton 112 for testing its circuit. Resistors
107, 109 and 111 complete the circuit in the absence of a fire. It
is to be noted that merely three temperature sensors and
annunciators are shown for the purposes of explaining the
invention. However, as many temperature sensors and annunciators as
needed may be utilized in this system. Lamp 401 is connected
between the thermal switch 112a and the anode of diode 73 and
lights when thermal switch 112a activates. Similarly, lamp 403 is
connected between the thermal switch 110a and the anode of diode 73
and lamp 402 is connected between the thermal switch 108a and the
anode of diode 73. When the respective thermal switches are open
then lamps 401, 402, 403 do not get sufficient current to
light.
The relay winding 101 is provided with a diode 103 which has its
cathode connected to the end of the winding 101. The anode of diode
103 is connected to the other end of the relay winding 101. The
diode 103 discharges the transients in the reverse direction which
are present when the current drops below threshold level in the
relay winding 101. An integrating capacitor 105 is connected in
parallel with diode 103 and the integrating capacitor functions to
isolate the system from stray fields caused by bolts of lightning
during a thunderstorm, transients caused by power failure,
switching the system from AC rectified power to battery power, and
other electrical disturbances. A pushbutton switch 106 is provided
for simulating the operation of a heat sensor which causes the
alarm to operate. The terminal 102 of the relay 101 is connected by
way of a lead A to the switch 28. The switch 28 is normally
connected to the output of the rectifier at the junction of
resistors 67 and 71. In the event of a power failure switch 28 is
activated by the relay 161 switching the switch 28 to the battery
29. (Operation of relay coil 161 will be described
hereinafter).
The return leads from the temperature sensors 108a, 110a and 112a
are connected to the anode of a diode 115. The cathode of the diode
115 is connected to one end of a switch 104 and to the switch 125a.
The switch 125a is connected through a cable 124 to a remote fire
station. A relay 119 is provided in the remote fire control station
for operating the switches 121 and 123. When the switch 123 closes,
it operates a nonillustrated fire alarm at the remote fire station
which indicates the location of the fire. The relay 119 is provided
with a 50-millisecond delay before actuation. Any suitable relay
which will operate with a 50-millisecond delay before actuation may
be used for relay 119. A suitable relay is the Eagle Auxtrip No.
A21757-3 described in Bliss Gamewell Bulletin 3130 published by
Bliss Gamewell Co., Newton, Mass. The switch 125a is provided as a
safe arm switch and is connected to the resistor 127. When it is
desired to carry out maintenance on the system the switch 125a is
closed so that a false alarm would not be given (relay coil 119 is
open circuited), and resistor 127 is inserted as a substitute load
for coil 119.
A current limiting resistor 117 is connected in circuit between the
switch 104 and the switch 123 for limiting the current flow in the
circuit path only after the relay coil 119 has been activated. When
maintenance is performed on the system, the switch 125 is closed
and then the rectified power from the rectifier section of the
circuit is connected by way of a lead 126 to the switches 134 and
134a and thence to the trouble alarm indicators 133 and 133a. It is
to be noted that the trouble alarm indicators 133 and 133a and the
alarms are located at various positions on the premises and merely
two are disclosed for symbolic explanation of the system, but as
many units as needed may be provided within the scope of this
invention.
A diode 129 is provided to operate all alarms simultaneously in the
event of fire and has its cathode connected to the switch 125 and
its anode is connected to the alarms 131 and 131a. When the relay
119 activates, the switch 121 operates and removes itself from the
circuit and switch 123 operates connecting resistor 117 to the
junction of 127 and switch 140 connects the alarms 131 and 131a to
the power supply of this system. In the event it is desired to have
a burglar alarm, the windows or doors etc., of the area to be
protected are each provided with switches 137a, 137b, 137c and
137n. A pushbutton 140 is provided in series with the resistor 127
and when it is depressed it causes the trouble alarm to be sounded
as will be indicated hereinafter. In the event any of the switches
137a, 137b, 137c and 137n are open or their respective circuits are
broken, then the trouble indicator alarm will be sounded. A switch,
preferably operated by a key is provided near the door for turning
the burglar alarm on and off. An indicator light 113 is provided
which lights up whenever the burglar alarm switch 139 is turned to
its "on" condition.
The other end of the wire leading from the burglar alarm switches
is connected to one end of an integrating capacitor 141. A first
diode 143 and a second diode 145 are connected in series across
capacitor 141. The free end of capacitor 141 is connected to the
electrical ground 13 of the system. The cathode of diode 145 is
also connected to the electrical ground and the cathode of diode
143 is connected to the anode of diode 145. A resistor 147 is
connected between the junction of the anode of diode 143 and a
capacitor 141 and the base of the transistor 151. The combination
of resistor 147 and capacitor 141 is a low-pass filter and prevents
the circuit from operating unless there has been a fault (fire or
burglar alarm, etc., condition) present for several hundred
milliseconds. This is provided to prevent the operation of the
system in response to superfluous transients and other electrical
disturbances.
The collector 154 of the transistor 151 is connected to the
parallel combination of the capacitor 157, the diode 159 and the
relay coil 161. The relay 161 is normally opened in the absence of
current. When the relay coil 161 draws current then the relay
contacts are as shown in FIG. 2a of the drawing. A suitable relay
is the Sigma Model 42RO-2500S-SIL, described in Sigma Relay
Catalog, published by Sigma Instruments Inc., Braintree, Mass.
The anode of diode 159 is connected to the collector of the NPN
transistor 151. The cathode of the diode 159 is connected to the
junction of resistor 67 and the anode of diode 73. A charging diode
226 has its anode connected to the anode of diode 73 and its
cathode connected by a switch 157 and a fuse 177 to the positive
terminal of a battery 29. The negative terminal of the battery is
connected by way of a trickle charge resistor 225 to the electrical
ground 13 of the system. The fuse 177 is to protect the battery 29
from surge and overload currents. The switch 175 is provided so
that the battery 29 can be disconnected from the circuit and
replaced. Switch 179 is provided to disable trouble alarm switches
134 and 134a. A terminal board for interconnecting the circuit
elements is schematically illustrated as unit 200.
The operation of the system is as follows:
The switch 52 is closed and the circuit is connected to a source of
AC power. The voltage is stepped down by way of a transformer 57
and rectified in the rectifying section of the circuit. Indicator
53 indicates the proper operation of the AC power and indicator
lights 75a and 75b indicate the proper operation of the rectifier
circuit. In the event that the AC power is lost and therefore the
rectifying power is also lost, the relay 161 is deactivated and
returns to its normally open position, thereby connecting the
battery 29 to switch 28. The indicator lights 75a and 75b go off
indicating the loss of the rectified power supply. Additionally,
the trouble alarms 133 and 133a go on indicating a fault condition.
It is to be noted that the transistor 151 is normally conductive
thereby assuring that the relay coil 161 is "on" holding contacts
to the positions shown in the drawing. However, if anything occurs
to cause the transistor 151 to cease conduction, then the relay 161
is again automatically deactivated causing the battery 29 to be
placed in the circuit and also causing the trouble alarms 133 and
133a to sound the trouble alarm. If, for any reason, battery 91
should short circuit or should resistor 81 or diode 83 become
defective, the voltage generated across variable resistor 155 will
increase causing the transistor 151 to turn off thus disabling the
relay 161 which, in turn, will activate trouble alarms 133 and
133a.
Activation of any of the heat detecting elements 108a, 110a or 112a
or by their associate short circuit causes the current level of the
relay coil 101 to increase beyond threshold which causes the relay
101 to operate closing switches 102 and 104 which in turn supplies
power to the relay coil 119 from the battery 91 and simultaneously
applies operating power to the fire alarms 131 and 131a and trouble
alarms 133 and 133a. The relay 119 has a 50-millisecond delay in
its operation and when it operates it opens up the contacts 121 and
closes the contacts 123. Increased current flowing in the fire
detectors circuit causes the relay 101 to operate, which applies
power to coil 119 which in turn operates contacts 121 and 123 after
a 50-millisecond delay. Operation of this relay coil 119 opens its
own power supply line by opening the switch 121 and the relay 119
simultaneously closes the switch 123, thereby placing a resistor
117 as a load in series with the alarm circuit which assures that
the alarm circuit continues to operate. When the relay coil 119
activates at the fire station, it also sets off the fire alarm
therein which indicates the presence of a fire on the premises
being protected. The relay 161 will be deenergized and cause the
trouble alarms 133 and 133a to operate in the event of a short
circuit to ground of any element in the alarm relay groups 101 and
119 and in the event that any of the lines in this group should be
broken, the relay 161 will operate.
It is to be noted that activation of the pushbutton 106 will cause
the fire alarm to be sounded and activation of the pushbutton 140
will cause the trouble alarms 133 and 133a to be sounded. The diode
226 provides power for the trouble alarms as long as there is AC
rectified power in the circuit.
Obviously, many modifications and variations of the present
invention are possible in the light of the above teaching. It is
therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described.
* * * * *