U.S. patent number 3,710,371 [Application Number 05/012,344] was granted by the patent office on 1973-01-09 for portable security alarm and alarm system.
Invention is credited to Rudolf F. Graf, George J. Whalen.
United States Patent |
3,710,371 |
Whalen , et al. |
January 9, 1973 |
PORTABLE SECURITY ALARM AND ALARM SYSTEM
Abstract
A portable alarm system including at least one alarm device
triggered when displaced from a normal position. A mercury switch
triggers a latching type semi-conductor switch, causing electrical
current to energize an alarm. Once sounded, the alarm cannot be
silenced unless the correct procedure or key method is
followed.
Inventors: |
Whalen; George J. (White
Plains, NY), Graf; Rudolf F. (New Rochelle, NY) |
Family
ID: |
21754524 |
Appl.
No.: |
05/012,344 |
Filed: |
February 18, 1970 |
Current U.S.
Class: |
340/571; 340/327;
340/429; 340/531; 340/689; 327/475; 340/539.1; 327/483;
340/539.26 |
Current CPC
Class: |
G08B
13/1436 (20130101) |
Current International
Class: |
G08B
13/14 (20060101); G08b 013/14 () |
Field of
Search: |
;340/283,280,276,384E,224,261,327 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Trafton; David L.
Claims
We claim:
1. An alarm system comprising a source of electrical power, alarm
means for producing an alarm signal when connected to said source
of electrical power, first switch means for providing a gating
pulse, a latching gate, said first switch means being connected to
said latching gate, said latching gate being responsive to said
gating pulse for connecting said alarm means to said source of
electrical power, and second switching means different from said
first switch means for disconnecting said alarm means from said
source of electrical power, said latching gate including a silicon
controlled rectifier, said first switch means including a mercury
switch, said second switch means including shunt means connected
across said latching gate for diverting electrical power away from
said latching gate.
2. The alarm device set forth in claim 1, wherein said second
switch means is provided with a high gain current amplifier, a pair
of contact means for causing current to flow through said high gain
current amplifier when said contact means are activated, said high
gain current amplifier shunting said latching gate diverting
electrical power from said latching gate when said pair of contact
means are activated and further disconnecting said alarm means from
said source of electrical power when said contact means are
deactivated.
3. The alarm device set forth in claim 2, including a housing
having said alarm means, said source of electrical power, said
first and second switch means, and said latching gate being located
therein, said latching gate connecting said source of electrical
power to said alarm means when said housing is displaced from a
normal position.
4. The alarm device set forth in claim 3, wherein said first switch
means includes a mercury switch being gravity responsive and
connecting said source of electrical power to said alarm means when
said housing is displaced from said normal position, said housing
being provided with a bottom capable of adhering to non-level
surfaces.
Description
Security systems are finding increasing personal use as well as in
homes, automobiles, and factories. The systems generally available
are frequently expensive, unreliable and complex to set. In
addition, once sounded, the alarm signal is easily squelched by an
intruder, thus detracting from its effectiveness. In addition,
industrial and home alarm systems are, generally, stationary, thus
permitting one to study the system to avoid triggering it.
An object of the present invention is to provide an improved
security system.
Another object of the present invention is to provide an alarm
device which is reliable, sturdy, easy to set, and passive prior to
actuation, so that detection by an intruder is made substantially
more difficult than with present alarm systems.
Still another object of the present invention is to provide a
security alarm system which is difficult to silence after it is
sounded.
Yet another object of the present invention is to provide a
portable alarm system capable of being easily carried and moved, so
as to afford the user the option of changing the setup of the alarm
system by readily changing the location of the sensors within the
area to be protected.
Still another object of the present invention is to provide an
alarm system which is capable of being easily triggered, not only
because of its inherent sensitivity, but also because of the
"surprise" element resulting from the complete freedom of placement
and variability of location made possible by use of sensing means
which are not "tied down" by connecting wiring or the like.
A further object of the present invention is to provide an alarm
system in which the independent alarm units can be readily
camouflaged as ordinary packages, containers, merchandise or the
like to further conceal the presence of an alarm system from the
unwary intruder.
A still further object of the present invention is to provide an
alarm system capable of producing either audible or non-audible
signals to be remotely sensed.
Other objects, advantages and features of the present invention
will be made more apparent from the following description.
In accordance with the principles of the present invention, these
objects are accomplished by providing a security system including
at least an alarm device comprising a housing being disposed in a
normal position, a source of electrical current, alarm means in the
housing for producing an alarm signal when energized, gating means
in the housing connected to the alarm means for supplying the
electrical current to the alarm means, and first switching means in
the housing for controlling the gating means and causing the gating
means to supply electrical current to the alarm means producing an
alarm signal when the housing is displaced from the normal
position.
The alarm device includes a mercury switch, enclosed in the
housing, so that when the housing is displaced from its normal
position, the mercury switch closes, triggering the gating means to
supply electrical current to the alarm. With the housing of the
alarm device being provided with a high center of gravity, the
device is tipped easily thus triggering the alarm. The device is
relatively light in weight and can be carried personally. In
addition, its location can be changed frequently, thereby
preventing the security system from being avoided. The alarm device
can be placed in any desired portal, desk drawer, on counter tops,
atop merchandise, on baggage, in vehicles to emit a periodic
audible alarm when displaced from its normal position. By placing a
plurality of such alarm units in a protected area and providing an
audible or a non-audible alarm signal capable of being remotely
detected, a relatively fool-proof security alarm system is
achieved. Use of an audible local alarm may create panic in an
unwary intruder, thereby reducing his probable changes for escape.
In some cases, a non-audible local alarm may be deemed proper as
the means of actuating a remote central alarm, to assist in capture
of intruders while "in the act."
As another principle of the present invention, once the alarm is
sounded, it cannot be silenced unless a prescribed key method or
procedure is followed. In one embodiment, a "touch" switch silences
the alarm only when its contacts are simultaneously touched with
moistened finger tips. The contacts are placed on the outer surface
of the housing and may easily be hidden from the unwary intruder.
Considerable latitude in the use of hidden switching means is
envisioned.
FIG. 1 is a side elevation view of one possible configuration of
the alarm device of the present invention shown capable of being
tipped;
FIG. 2 is an exploded assembly view of the alarm device;
FIG. 3 is a schematic diagram of one embodiment of the alarm
circuit of the present invention;
FIG. 4 is a schematic diagram of another embodiment of the alarm
circuit of the present invention; and,
FIG. 5 is a block diagram of an alarm system utilizing the alarm
device.
The present invention provides a compact, yet sturdy alarm unit,
which is capable of being placed on any surface and which when
placed in an armed state, will signal its being moved from a normal
position. The alarm may be audible or inaudible, as desired, and is
relatively light and, therefore, portable. For personal use, it may
be placed on an attache case while one is in a telephone booth and
will be sounded if the alarm or attache case is moved. For
convenience, the alarm is capable of being switched to a disarmed
state preventing its being sounded whether or not its position
changes. When in this state, the alarm may be jostled without
sounding. A security system may be provided with a plurality of
such alarm devices to protect a large area.
The alarm unit 10 may be cylindrical in shape and fabricated of a
relatively sturdy and durable material to withstand rough use and
prevent tampering. Considerable variation is possible in the
outward appearance of the alarm unit, to permit its disguise, as an
object of merchandise or other object normally found in a store,
home or office, which an intruder would not suspect of being an
alarm device. The components of the alarm device are placed within
the alarm unit and preferably in the upper portion thereof to
provide a relatively high center of gravity. Thus, when the device
is placed on a level surface, it may readily be tipped when
disturbed. The housing 12 of the unit includes a rounded and
weighted bottom to be self-righting when disturbed and also usable
on non-level surfaces. As another embodiment of the present
invention, the central portion of the rounded bottom may be
magnetized so that the unit could be placed on a non-level metal
surface with some degree of adhesion, but still remaining free to
be tipped when disturbed. As still another alternative, a temporary
adhesive could also be utilized.
As described above, preferably the components of the alarm device
are mounted within the housing 12. The alarm 14 is attached to the
top portion of housing 12, and may be a "Sonalert" type (registered
trademark of P. R. Mallory & Co., Inc.), which is an acoustical
generator producing an audio tone of approximately 70 decibels
interrupted at a period of 3 to 5 Hertz. It should be noted that
this "Sonalert" would give way to other suitable means of signal
generation where a non-audible alarm was desired. Such non-audible
alarm signal generators could comprise ultrasonic or
radio-frequency oscillators, suitably modulated so as to assure
fool-proof detection by a remote central monitor. The components of
the alarm device are mounted on and between oppositely disposed
mounting plates 16 and 18. The plates are held together by means of
threaded screws 20, 22 and 24 which fit through corresponding holes
oppositely disposed in support plates 16 and 18. The alarm unit is
powered by batteries connected in series to terminals 26 and 28.
The batteries preferably are portable and may be rechargeable, if
desired. The mounted components shown in FIG. 2 are schematically
illustrated in FIG. 4 and will be described with reference to that
Figure. After the functional description of this schematic circuit
shown in FIG. 4 is completed, the components shown in FIG. 2 will
be identified.
FIGS. 3 and 4 present schematic diagrams of an alarm circuit used
with the present invention, and in addition, illustrate two
different turn off procedures employed to silence the alarm.
Electrical power for the alarm is provided by an internal battery
30 with the positive electrode of the battery connected to the
positive terminal of the alarm 32. The negative terminal of the
alarm is connected to the anode of a silicon controlled rectifier
34. Alarm 32, as described above, is capable of providing periodic
bursts of sound at a specific frequency when energized. Silicon
controlled rectifier 34 is a bi-stable semi-conductor device which
conducts when a triggering pulse is applied to the gate terminal of
the device. In effect, the silicon controlled rectifier 34 "latches
on". The rectifier will remain conducting until the current through
it falls below a pre-determined level. A General Electric type
C106Y1 silicon controlled rectifier may be used with the principles
of the present invention, although any other latching device would
be suitable. The cathode of silicon controlled rectifier 34 is
connected through a key operated switch 36 controlled by key 37 to
the negative electrode of battery 30. When the silicon controlled
rectifier 34 is triggered and conducting, the series path of
battery 30, alarm 32, silicon controlled rectifier 34, and key
operated switch 36 provides a closed circuit sounding the alarm 32.
In its normal state, silicon controlled rectifier 34 is not
conducting. The positive electrode of battery 30 is connected to a
mercury switch 38 having contacts capable of being electrically
connected by means of an electro-conductive blob of mercury 43
moving in response to gravity when the orientation of the switch 38
is altered in relation to the normal rest position. Normally, the
contacts 40 and 42 are not so connected; that is, the mercury blob
does not simultaneously touch both of the contacts. By placing
contact 42 permanently in mercury blob 43 and contact 40 very close
to the mercury blob, a slight alteration in the position of the
alarm device will cause the mercury blob to close the electrical
path between contacts 40 and 42.
The positive electrode of battery 30 is connected to contact 40.
Contact 42 is connected through a parallel connection of resistor
44 and capacitor 46 to the gate terminal of silicon controlled
rectifier 34. A resistor 50 is connected between the gate terminal
and the cathode of the silicon controlled rectifier 34. Resistors
44 and 50 and capacitor 46 provide a wave shaping function for the
triggering pulse applied to the gate terminal.
The positional sensor of the alarm is the mercury switch 38 which
detects a disturbance of the unit from its normal position. Once
the alarm is sounded, the circuit remains active, operating on the
internal battery supply 30. In operation, the unit is placed in a
predetermined position, so that the mercury blob 42 does not close
contacts 40 and 42, and the key operated switch 36 is placed to its
arm position. When the mercury switch 38 closes the electrical path
between contacts 40 and 42, a trigger pulse is applied to the gate
terminal of silicon controlled rectifier 34 triggering it into its
conducting state. Once triggered, the rectifier 34 remains
"latched" in the conducting state closing the above described path
for current flow through the alarm 32. Thus, the alarm sounds and
continues in operation until the unit is disarmed or the internal
battery is exhausted. By turning, the key operated switch 36 to its
disarm position, the current supplied through silicon controlled
rectifier device 34 is interrupted, turning off the alarm. It
should be noted that the alarm cannot be turned off by positional
changes, only by use of a "key" method. By providing a relatively
sturdy housing for the device, the sounding of the alarm cannot be
interrupted by an intruder, unless he possess the required key
method. The"panic property" inherent in a device which cannot be
deactivated by a startled intruder, lacking the required knowledge
to silence the alarm, is a principal feature of the present
invention.
FIG. 4 presents a schematic diagram including the same alarm
circuit shown in FIG. 3 and with similar components designated as
primed numerals. The operation of the alarm circuit need not be
repeated again except to point to differences therein. In FIG. 3, a
key operated switch 36 was utilized as a master control for the
device. In FIG. 4, a switch 52, preferably not key operated, is
placed in the trigger circuit for the silicon controlled rectifier
device 34'. Therefore, when switch 52 is in its arm position,
silicon controlled rectifier device 34' is capable of being
triggered. But, once the alarm has been trigger, should switch 52
be placed in its disarm position, the silicon controlled rectifier
will continue to operate because the current supplied to it will
not be interrupted by placing switch 52 in its disarm position. To
this end, switch 52 is connected between the positive electrode of
battery 30' and contact 40'. As above, when switch 52 is placed in
its arm position, electrical power is available to trigger silicon
controlled device 34' when the mercury switch 38' closes contact
40' and 42'. Therefore, switch 52 must first be placed in the arm
position before the silicon controlled rectifier 34' is triggered
into its conducting state, sounding alarm 32'.
Rather than using the key operated switch to silence the alarm, a
"tough" switch 53 is utilized including a solid-state circuit which
is energized when two contacts 62 and 64 are simultaneously touched
with moistened finger tips. The touch switch can be completely
concealed in the design of the alarm unit so that its presence is
undetectable to the uninformed observer. The semi-conductor circuit
includes a Darlington type amplifier 54. A Darlington amplifier
comprises cascaded transistors providing an extremely high input
and extremely low output impedance and having a high current gain.
The collector of NPN transistor 56 is connected to the collector of
NPN transistor 58. The emitter of transistor 56 is connected to the
base of transistor 58, while the base of transistor 56 is connected
through a limiting resistor 60 to touch contact 62. The emitter of
transistor 58 is connected to the cathode of silicon controlled
rectifier 34', while the collectors of transistors 56 and 58 are
connected to the anode of rectifier 34'. Contact 64 is connected to
contact 40' of the mercury switch 38'. To conserve space, the
Darlington amplifier may be a monolithic type integrated circuit of
which a General Electric type 2N5306 is typical. Other suitable
amplifier/switching devices may be utilized.
Normally, the Darlington amplifier 54 is not active. In order to
silence the alarm after it has been triggered, moistened finger
tips are applied to the touch contacts 62 and 64. When the touch
contacts are so bridged, a minute direct current is applied through
the skin resistance to the base of transistor 46. This current is
sufficient to cause the Darlington amplifier to conduct, thereby
shunting current away from silicon controlled rectifier 34' and
sufficiently impeding the current flow through the rectifier
causing it to be non-conductive. When the fingers are subsequently
removed from contacts 62 and 64, the current flowing through the
alarm 32' is interrupted, silencing the alarm. To the unwary
intruder, who may attempt to silence the alarm by turning the
switch 52 to its disarm position, the continuing sounding of the
alarm can only cause panic, thereby being thrown into the desired
state of disorientation which will hinder his escape.
A plurality of "touch" switches may be included in the circuit to
heighten the complexity of the turn-off function. These switch
circuits may be so arranged that coincident operation is necessary.
Of they may be so configured that one circuit will negate the
function of the other when both are simultaneously activated. The
meaning of the switching function would be construed broadly to
include such alternatives.
With the alarm circuit shown in FIGS. 3 or 4, the device may be
manually carried from place to place without triggering the alarm
by placing the switches 36 and 52 to the disarm position, thus
preventing current from flowing through alarm devices 32 and 32'
and triggering silicon controlled rectifiers 34 and 34'
respectively.
The assembly diagram of the device presented in FIG. 2 includes the
components shown in FIG. 4. The silicon controlled rectifier 34' is
mounted to support plate 18 and resistors 44' and 50' are connected
to the silicon controlled rectifier device and are located between
support plates 16 and 18. Capacitor 46' is also located between the
support plates. Darlington device 54 is attached to support plate
18, while mercury switch 38' is attached between support plates 16
and 18. Resistor 60 is also connected between the support plates
while master switch 52 is connected to the housing 12 of the alarm
device. While the arrangement of the components shown in FIG. 2
enables the device to be assembled and housed completely within
housing 12, other physical arrangements for the components may be
devised by those of ordinary skill in the art.
While the above described alarm device 10 can be used as a security
alarm protecting against unwary intruders, it may also be used as a
fire detection alarm. To achieve this, a thermally actuated
bi-metallic, normally open, switch paralleling the mercury switch
may be included. Thus, when a substantial heat rise of the ambient
air occurs, the bi-metallic switch contacts close, triggering the
alarm in the same manner as the above described mercury switch.
While a single alarm unit has been described above, it should be
noted that a number of similar independent units may be placed at
strategic locations, each being capable of being altered in
position, creating an alarm system providing security for a
relatively large area. The units designated 70, 72 and 74, when
triggered, may produce an audible or inaudible alarm. When an
inaudible alarm is produced, suitable transducers 76 and 78 tuned
to pick up the inaudible alarm signal, activate a central
monitoring system 80 which in turn activates a main alarm 82 or any
of a plurality of remote alarms 84. Each transducer is tuned to an
alarm frequency of, for instance, 2,800 Hertz while transducers 76
and 78 reject other frequencies. Suitable means for discriminating
between the true alarm signal and a random, unwanted signal of like
frequency could be provided in the central monitor, wherein
coincident reception of the desired frequency signal and an
accompanying pulse modulation or audio modulating frequency would
be required before the central monitor would activate the main
alarm system. This would prevent "nuisance" alarms. A modulated
ultrasonic or radio frequency transmission system may be used
between the alarm devices, transducers 76 and 78 and central
monitor system 80. The central monitor may activate such remote and
local alarms as telephone dialers, alarm bells, lights or other
similar warning devices. In the case of an audible system, suitable
transmission techniques are employed to prevent the central monitor
from picking up extraneous noise signals, and, to this end, the
alarm signal produced by alarm units 70, 72 and 74 may be at a
fixed frequency of 2800 Hertz modulated at a 3 to 5 Hertz rate. It
is impossible that a similar extraneous noise signal, having these
characteristics, will be produced, thus insuring that the central
monitor will be responsive only to the actual triggering of an
alarm unit. Because the alarm units 70, 72 and 74 are portable,
their positions may be changed nightly, thus preventing "casing" of
the protected area by even the most skillful burglar. The entirely
passive nature of the alarm units, when armed but not activated,
also enhances the effectiveness of the system by giving no sign of
their presence or location.
It may be seen that the above objects are efficiently accomplished
and obtained by the principles of the present invention. Further,
the above description merely illustrates the principles of the
present invention and should not be construed in a limiting sense.
To that end, therefore, the invention should be accorded its full
scope of protection to which it is entitled by this patent
application.
* * * * *