U.S. patent number 3,887,909 [Application Number 05/248,050] was granted by the patent office on 1975-06-03 for alarm device.
This patent grant is currently assigned to National Presto Industries, Inc.. Invention is credited to John L. Beiswenger, Leland DeVon Jorgensen.
United States Patent |
3,887,909 |
Beiswenger , et al. |
June 3, 1975 |
Alarm device
Abstract
An alarm device having an extendible cord control element the
outer end of which is attached to an object, such as a window or
door, to place the cord in predetermined tension with the cord
acting directly on a switch arm to effect an alarm signal upon a
change in tension of the cord resulting from breaking or pulling
thereof.
Inventors: |
Beiswenger; John L. (Pacific
Palisades, WI), Jorgensen; Leland DeVon (Chippewa Falls,
WI) |
Assignee: |
National Presto Industries,
Inc. (Eau Claire, WI)
|
Family
ID: |
22937449 |
Appl.
No.: |
05/248,050 |
Filed: |
April 27, 1972 |
Current U.S.
Class: |
340/521;
200/61.62; 340/593; 340/548; 340/568.2 |
Current CPC
Class: |
G08B
13/08 (20130101); G08B 17/06 (20130101) |
Current International
Class: |
G08B
17/06 (20060101); G08B 13/02 (20060101); G08B
13/08 (20060101); G08b 013/00 (); G08b
013/08 () |
Field of
Search: |
;340/274,276,283,273,420,232 ;200/61.39,61.62 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Caldwell; John W.
Assistant Examiner: Partridge; Scott F.
Attorney, Agent or Firm: Johnson, Dienner, Emrich &
Wagner
Claims
We claim:
1. An alarm device for use in detecting movement of an object,
comprising, in combination, housing means, electrically operated
alarm generating means supported by said housing means, a source of
electrical energy supported by said housing means, circuit means
selectively electrically connecting said alarm generating means to
said source of electrical energy, said circuit means including
switch means having a pair of spaced fixed contacts and a movable
contact arm therebetween and biasing means urging the movable
contact arm to one and away from the other of said fixed contacts,
said movable contact arm and fixed contacts being connected in said
circuit such that said circuit means is closed when said contact
arm is contacting either of said fixed contacts and open when said
contact arm is disposed intermediate said fixed contacts, a
rotatable reel member, means including a length of cord wound about
said rotatable reel member, and releasable clutch means for
resisting rotation of said reel member, said cord means acting
directly on said movable contact arm and having its free end
adapted to be secured to the object, said clutch means being
releasable to permit unwinding of said cord means from said reel
member to facilitate attachment of said cord means to the object
and to take up slack in said cord means to place said cord means
under tension of an amount sufficient to resist the force of the
biasing means and hold said contact arm intermediate and out of
engagement with said fixed contacts, whereby when said cord means
is pulled, broken or otherwise disturbed said contact arm will be
caused to contact one of said fixed contacts and to energize said
alarm generating means.
2. An alarm device as defined in claim 1 wherein said movable
contact arm has an opening therein, and wherein said cord means
passes through said opening and acts upon said contact arm to
effect movement thereof when the tension in said cord is varied
from said tension placed thereon.
3. An alarm device as defined in claim 1 wherein said reel member
is mounted within said housing and includes a flange portion
extending outwardly of said housing to allow said reel member to be
rotated through movement of said flange portion externally of said
housing.
4. An alarm device as defined in claim 1 wherein said source of
electrical energy comprises a pair of DC batteries normally
connected in series, said circuit means having a pair of separable
contacts normally connecting said batteries in series, and
including means adapted to be inserted between said last mentioned
contacts to separate the same and open said series connection
between said batteries.
5. An alarm device as defined in claim 1 wherein said reel member
is mounted within said housing for rotation about its longitudinal
axis, and wherein said movable contact arm of said switch means is
mounted for pivotal movement about the axis of rotation of said
reel.
6. An alarm device comprising, in combination, housing means,
electrically operated alarm generating means supported by said
housing means, a source of electrical energy supported by said
housing means, circuit means selectively electrically connecting
said alarm generating means to said electrical energy source, said
circuit means including switch means comprising a pair of fixed
contacts and a movable contact arm swingable therebetween, and
biasing means urging the movable contact arm to one of said fixed
contacts and away from the other, a rotatable reel having a length
of cord wound thereabout and spring-biased, releasable clutch means
for resisting rotation of said reel, said cord passing through a
provided opening in one end of said contact arm and having its free
end adapted for attachment to an object, said clutch means being
releasable to permit unwinding of the cord therefrom to facilitate
attachment of said cord to such object and to take up slack in the
cord sufficiently to place the cord under tension and hold the
contact arm out of engagement with the fixed contacts and against
the force of the biasing means whereby when the cord is pulled,
broken or otherwise disturbed the contact arm will be caused to
contact one of the fixed contacts and to energize the alarm
generating means.
7. An alarm device as defined in claim 6 wherein said free end of
the cord has a magnet attached thereto.
8. An alarm device as defined in claim 6 wherein the circuit means
includes a pair of separable contacts aligned with an opening in
the housing through which a removable electrical insulating member
is insertable to separate the contacts and open the circuits to
disable the alarm device.
9. An alarm device as defined in claim 6 wherein the reel and
movable contact arm are mounted to independently turn on a common
axis located to one side of and spaced from the opening in the
contact arm through which the cord passes, said housing having a
further opening therein spaced from and to the opposite side of
said opening in the contact arm through which the cord is also
threaded, said opening being so related that the reel may be
rotated on its axis to take up slack in the cord and thereby to
center the contact arm spaced between the fixed contacts.
10. An alarm device as defined in claim 6 including thermostat
means supported by said housing means and connected in circuit with
said circuit means, said thermostat means being adapted to effect
energizing of said alarm generating means when a predetermined
temperature surrounding said thermostat means is reached.
11. An alarm device as defined in claim 10 wherein said thermostat
means is connected in parallel with the portion of said circuit
having said switch means therein so that said alarm generating
means may be energized by said thermostat means while said swith
means is open.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to alarm devices, and more
particularly to a burglar alarm device having novel switch means
operative in response to the change in tension of a control element
to effect an alarm signal.
Burglar alarm devices are known which employ trip wire means
attachable to a window or the like such that unauthorized opening
or entry will effect an alarm signal. For example, U.S. Pat. Nos.
118,199 to Cock and Guest, 1,238,532 to Lemberg, and 1,937,134 to
Stout disclose burglar alarm mechanisms utilizing trip cord or
chain means which are connected to an object such that a change in
tension of the cord as through movement of the object effects an
alarm signal. The present invention provides an improved alarm
device of this general type which includes novel structural and
functional advantages over the prior art devices.
SUMMARY OF THE INVENTION
In accordance with a preferred embodiment of the present invention,
an alarm device is provided having housing means which encloses
electrically operative alarm signal means and a source of
electrical energy to selectively energize the signal means. The
energy source is connected to the alarm signal means through a
circuit which includes a control switch having a contact arm
movable to contact either of a pair of spaced fixed contacts. The
contact arm is supported for pivotal movement about the rotational
axis of a reel which has a length of cord wrapped therearound. The
cord directly engages the contact arm and has magnetic attachment
means on its outer end allowing it to be led from the reel and
attached to an object such as a window or door or the like. The
reel is manually adjustable from outside the housing to place the
cord under a predetermined tension and position the contact arm
intermediate the fixed contacts. When the cord is pulled or broken
by unauthorized movement thereof, the contact arm is caused to
contact one of the fixed contacts and energize the alarm signal
means. A key may be removably inserted into the housing to open the
circuit to the alarm signal means during adjustment of the reel and
contact arm. Thermostat means are preferably connected in circuit
with the alarm signal means to establish an alarm when the ambient
temperature surrounding the housing reaches a danger level such as
in the case of fire.
Accordingly, one of the primary objects of the present invention is
to provide an alarm device having novel means for establishing an
alarm signal upon unauthorized movement of a control element of the
device.
Another object of the present invention is to provide an alarm
device which employs a novel contact switch arrangement responsive
to unauthorized movement of a control cord having an outer end
secured to an object such as a window or door or the like.
Another object of the present invention is to provide an alarm
device as described wherein the control cord is supported on a
rotatable reel and acts directly on a contact arm movable in
response to a change in tension in the cord to contact one of a
pair of fixed switch contacts and thereby energize alarm signal
means.
A further object of the present invention is to provide an alarm
device which is relatively inexpensive to manufacture and highly
efficient in operation.
A feature of the present invention is a provision of a circuit
disabling key which may be removably inserted into the housing to
disable the circuit during adjustment of the control cord and
movable contact arm.
Further objects and advantages of the present invention, together
with the organization and manner of operation thereof, will become
apparent from the following detailed description of a preferred
embodiment of the invention when taken in conjunction with the
accompanying drawings wherein like reference numerals designate
like elements throughout the several views.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevational view of an alarm device in accordance with
the present invention illustrated as being operatively connected to
a window to detect unauthorized movement thereof;
FIG. 2 is an enlarged front view of the alarm device of FIG. 1, the
cover of the housing being removed to show the internal
elements;
FIG. 3 is a longitudinal sectional view taken generally along the
line 3--3 of FIG. 2 but showing the cover of the housing in
assembled position;
FIG. 4 is a transverse sectional view taken generally along the
line 4--4 of FIG. 3: and
FIG. 5 is a schematic circuit diagram of the control circuit
utilized in the alarm device of FIGS. 1-4.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now to the drawings, and in particular to FIG. 1, an
alarm device in accordance with the present invention is indicated
generally at 10 and is shown in conjunction with a conventional
double-hung window, indicated generally at 12. For purposes of
illustration, the alarm device 10 is shown in FIG. 1 in
substantially greater size relative to the window 12 than the size
of the actual production unit which is approximately three by five
inches, considered in front elevation as in FIGS. 1 and 2. As will
become more apparent hereinbelow, the use of the alarm device 10 in
conjunction with the window assembly 12 exemplifies but one
possible use of the alarm device. In general, the alarm device 10
may be employed to generate an alarm system responsive to the
unauthorized movement of an object to which a control element is
attached, or signal the movement of the control element when
positioned in a passageway or the like so as to be obstructed by
movement of a person in the passageway.
The alarm device 10 includes a rectangularly shaped housing
indicated generally at 14, having a removable cover plate 16.
Noting FIG. 3, the cover plate 16 is retained on the top of the
rectangularly shaped housing 14 by a retaining screw 18 the lower
end of which is threadedly secured in an upstanding boss 20 formed
integral with or otherwise suitably secured to the lower wall 22 of
the housing 14. The housing 14 is preferably made of a lightweight
material such as a suitable thermoplastic material. The cover plate
16 of the alarm device 10 has a plurality of openings 24
therethrough to facilitate the transmission of an audible alarm
signal from the alarm device as will be described more fully
hereinbelow.
With reference to FIG. 2, taken in conjunction with FIGS. 3 and 4,
the alarm device 10 includes alarm generating means, indicated
generally at 26, which, in the illustrated embodiment, comprises a
Klaxon steady signal electrically operated audible alarm 28 of
known design. The alarm 28 has a mounting bracket 30 secured to the
lower surface thereof (FIG. 3) which is suitably secured to and
supported by an upstanding boss 32 formed integral with the bottom
22 of the housing 14. A conductor strip 34 has one end thereof
interposed between the mounting bracket 30 and the boss 32 and
extends along the bottom 22 of the housing to an upturned end
portion 36 which forms a contact for a conventional "C" size
alkaline DC battery cell, indicated in phantom at 38. The mounting
bracket 30 of the alarm 28 serves as the negative or ground
terminal for the alarm control circuit to be described more fully
below. While the alarm generating means 26 is described and
illustrated herein as being an audible tone generating means, it
will be understood that the alarm means may comprise a visual
signal device such as a light, or may comprise means providing an
output signal for a remote indicating means.
The battery 38 is connected in circuit with a second DC battery,
indicated at phantom at 40, identical to the battery 38 to provide
a source of electrical energy for the alarm generating means 26. To
this end, the positive terminal 42 of the battery 38 contacts an
upstanding conductor strip 44 which is of a configuration to
cooperate with the upstanding end 36 of the conductor strip 34 to
resiliently receive the battery 38 therebetween. Suitable battery
support plates 46 are formed integral with the housing 14 and serve
to cradle the batteries 38 and 40 in operating position within the
housing. The conductor strip 44 has an integral conductive arm
portion 48 adjacent the bottom 22 of the housing 14 which normally
resiliently contacts a second conducting arm 50 formed integral
with an upstanding conductive strip 52 which provides the ground
contact for the battery 40. The conductive strips or contacts 44
and 52 are secured to the lower or bottom plate 22 of the housing
means 14 through suitable means such as rivets 54 and 56,
respectively.
The housing 14 is preferably provided with a suitable opening 58
which receives an elongated end portion 60 of a circuit disabling
key 62 made of a non-conducting material such as plastic. The
elongated end 60 of the disabling key 62 may be selectively
inserted through the opening 58 in the housing 14 and caused to
separate the normally contacting conductive arms 48 and 50 and
thereby open the series circuit between the batteries 38 and 40 to
open the circuit to the alarm generating means 26.
The positive terminal 64 of the battery 40 contacts a conductive
strip 66 which is secured to a non-conducting support plate 68. The
support plate 58 is of planar rectangular configuration and is
slidably received between and supported by inwardly directed
projections 70 formed integral with the housing 14 and having slots
along their lengths to receive the opposite edge portions of the
support plate 68 as shown in FIG. 2 such that the support plate may
be removed from the housing 14.
The support plate 68 supports switch means, indicated generally at
72, which is connected in circuit between the source of electrical
energy comprising the batteries 38 and 40 and the alarm generating
means 26 to effect selective energizing of the alarm generating
means. The switch means 72 includes a pair of fixed contacts 74 and
76 which comprise conductor strips formed integral with the
conductive strip 66, the fixed contacts 74 and 76 being formed to
extend downwardly from the top edge of the support plate 68 and
upwardly from the bottom edge thereof, respectively, as illustrated
in FIGS. 3 and 4. The switch means 72 further includes a movable
contact arm 78 which has a suitable opening mid-length thereof to
allow the contact arm to be pivotally mounted on a support pin 80
secured in normal relation to the support plate 68 generally
centrally thereto. The support pin 80 has a threaded end portion 82
which is received through a suitable opening in the support plate
68 and has a nut 84 secured thereon to retain the support pin 80 in
fixed relation on the support plate 68. A compression spring 86 is
disposed about the support pin 80 between a reel 88 to be described
more fully hereinbelow, and the movable contact arm 78 which
engages an enlarged head portion 90 of the support pin 80. The
opposite ends of the contact arm 78 are formed to establish leg
portions 92 and 94 which lie in planes perpendicular to the plane
of the main arm portion 78.
Noting FIG. 4, a tension spring 96 has its opposite ends connected,
respectively, to the inwardly turned leg portion 92 of the movable
contact arm 78 and to a projection 98 formed integral with and
projecting outwardly from the support plate 68 adjacent the upper
edge thereof. The tension spring 96 is adapted to urge the movable
contact arm 78 in a counter-clockwise rotational direction, as
considered in FIG. 4, to effect engagement of the end leg portion
94 with the fixed contact 76. As will be described below, the
contact arm 78 is also rotatable in a clockwise direction to effect
engagement of the leg portion 94 with the other fixed contact
74.
The support pin 80 is made of a metallic conducting material so as
to be conductively connected to the movable contact arm 78, which
in turn is made of a conductive metallic material. The support pin
80 is conductively connected to a conductor 100 adjacent the
threaded end 82 and nut 84, the conductor 100 having its opposite
end connected to a metallic terminal 102 through a screw 104
received through a suitable opening in the bottom 22 of the housing
14 and having a nut 106 secured on the lower end thereof to retain
the terminal 102 against a raised boss formed on the bottom 22 of
the housing. A conductor 108 connects the conductor 100 to a
terminal 109 of the alarm 28 to complete a circuit from the alarm
generating means 26 through the batteries 38 and 40 and back to the
alarm 28 through the conductor 108 when the movable contact arm 78
is contacting either of the fixed contacts 74 or 76.
The alarm device 10 includes switch operating means for cooperation
with the movable contact arm 78 to selectively effect movement of
the switch arm to engage the fixed contact 74 or allow movement of
the switch arm to engage the fixed contact 76 under the influence
of the biasing spring 96. Such switch operating means includes a
control element 110 comprising a trip wire or cord, preferably made
of a monofilament nylon line, which acts directly on the movable
contact arm 78 and is adapted to be secured to an object under a
predetermined tension to position the contact arm intermediate the
fixed contacts 74 and 76. To this end, the control element 110 is
wound upon the aforenoted reel 88 which is made of a nonconductive
thermoplastic material and is supported on the support pin 80 for
rotational movement thereon. The reel 88 is urged toward the
support plate 68 by the compression spring 86. The reel 88 has a
peripheral surface portion which extends through a suitable
rectangular opening 112 in the cover 16 of the housing 14 such that
the reel 88 may be rotated on the support shaft 80 by one's thumb
from outside the housing 14. The reel 88 is adapted to hold
approximately 30 feet of the control element line 110 and allows
the control element line to be played outwardly from the reel
whereupon the control element line is passed through an opening 114
in the leg portion 94 of the movable contact arm 78 and through an
opening 116 formed in the sidewall of the housing 14. The opening
114 in the movable contact arm 78 and the opening 116 in the
housing have smooth peripheral surfaces to allow free sliding
movement of the control element line 110. The outer end of the
control element 110 has a magnet 118 secured thereto for
magnetically attaching the end of the control element to a metallic
plate 120 affixed to an L-shaped bracket 122 to the vertical leg
portion of which has a pressure adhesive surface 124 providing
means to secure the bracket 122 to an object such as the horizontal
window frame member 126 of the window assembly 12 shown in FIG. 1.
It will be understood that the outer end of the control element 110
may be secured to the window frame member 126 or other object
through any suitable means alternative to the magnet 118 and
bracket 122.
As noted, the control element 110 may be played-out from the reel
88 to allow the magnet 118 to be secured to the bracket 122 which
is attached to an object removed from the alarm device 10. To
prevent free rotation of the reel, a flange portion 128 thereof has
one or more V-shaped projections or teeth 130 projecting outwardly
therefrom toward the opposing surface of the support plate 68. The
teeth 130 cooperate with a plurality of circularly disposed
V-shaped teeth 132 formed integral with the support plate 68 and
lying on a circle having a radius equal to the radial distance of
the teeth 130 from the axis of the flange 128 of the reel. In this
manner, the compression spring 86 urges the reel 88 in a direction
to position the teeth 130 intermediate the spaced teeth 132 thereby
providing resistance to rotation of the reel when the reel is
rotated by the operator's thumb from outside the casing 14 or when
the control element 110 is pulled outwardly from the reel. The
compression spring 86 is of a suitable spring rate to allow
rotation of the reel when adjusting the tension in the control
element 110.
Preferably, the alarm device 10 includes a conventional heat
sensitive thermostat means 134 which is supported within a suitable
opening in an end wall 136 of the housing 14. The thermostat means
134 has a pair of terminals 138 and 140. The terminal 130 is
connected through conductors 142 and 144 to the conductive strip 66
so as to be in circuit with the batteries 38 and 40. The terminal
140 of the thermostat means 134 is connected through a conductor
146 to a positive terminal 148 on the bottom of the alarm 28. The
thermostat means 138 is of known design and is responsive to a
predetermined termperature rise to close the circuit between the
batteries 38 and 40 and the alarm 28 to energize the alarm and
effect an alarm signal when the temperature surrounding the alarm
device 10 reaches a danger condition such as would result from a
fire.
FIG. 5 schematically illustrates the circuit for selectively
electrically connecting the alarm 28 of the alarm generating means
26 to the energy source comprising the batteries 38 and 40, and
shows that with the disabling key 62 removed to effect connection
between the conductive arms 48 and 50, the alarm 28 may be
energized through closing of the normally open thermostat switch
means 134 or through engagement of the movable contact arm 78 with
either of the fixed contacts 74 and 76.
Having thus described a preferred embodiment of the present
invention, its operation will now be briefly described. With the
elements of the alarm device 10 assembled as hereinabove described,
the housing 14 may be secured to a wall or window frame adjacent a
window, door or passageway in which unauthorized movement it to be
detected. In the application of the alarm device as illustrated in
FIG. 1, the bracket 122 would then be secured to the horizontal
window frame member 126 and the control element 110 withdrawn or
played-out from the reel to allow the magnet 110 to be magnetically
attached to the metallic plate 120 of the bracket 122. When
mounting the alarm device 10 in an operating position, the
disabling key 62 is inserted through the opening 58 to separate the
contact arms 48 and 50 and thereby open the circuit to the alarm 28
through the batteries 38 and 40. After connecting the magnet 118 to
the bracket 122, the reel 88 is moved by the operator's thumb in a
rotational direction to tighten the control element line 110 until
the end leg 94 of the movable contact arm 78 is positioned
intermediate the fixed contacts 74 and 76 as illustrated in FIG. 4.
After roughly tensioning the control element 110, the disabling key
62 is removed and the reel 88 further rotated, if necessary, to
assure placement of the contact arm 76 intermediate the fixed
contacts 74 and 76. The compression spring 86 serves to maintain
friction engagement of the teeth 130 on the reel flange 128 between
the opposing teeth 132 on the support plate 68 such that the reel
will remain in its set position with the control element 110 being
under a corresponding predetermined tension to establish the
intermediate position of the contact arm 78.
With the alarm device 10 so installed, if the lower window of the
window assembly 112 should be opened upwardly in an unauthorized
manner, the tension in the control element 110 will be reduced to
allow the biasing spring 96 to move the contact arm 78 into
engagement with the fixed contact 76 and thereby energize the alarm
28 giving an alarm signal. Alternatively, if the control element
110 and its associated magnet 118 are secured to the lower window
when in a desired raised position, unauthorized lowering of the
window will increase the tension on the control element 110 and
cause the movable contact arm 76 to engage the fixed contact 74 and
close the circuit to the alarm 28 to establish an output alarm
signal. Similarly, if the alarm device 10 is placed adjacent a
floor area close to a passage through which people pass, the
control element 110 may be placed across the passage area and
secured in a predetermined tension to place the contact arm 78
intermediate the contacts 74 and 76. Thereafter, should anyone
effect an unauthorized passage through the passageway and contact
the control element 110, it would either place the control element
in greater tension to effect movement of the contact arm 78 with
the contact 74 to establish an alarm signal, or would pull the
magnet 118 from the associated bracket 122 to slacken the control
element sufficiently to allow movement of the contact arm 78 into
engagement with the contact 76 to again close the circuit to the
alarm 28 and establish an alarm signal. Similarly, if the control
element 110 is cut, broken, or burned after having been installed
in the aforedescribed manner, an alarm will be established.
While a preferred embodiment of the present invention has been
illustrated and described, it will be understood that changes and
modifications may be made therein without departing from the
invention in its broader aspects.
* * * * *