U.S. patent number 3,696,373 [Application Number 05/063,127] was granted by the patent office on 1972-10-03 for electric alarm screen.
Invention is credited to John Malcolm Dunn, George Kenneth Hornbrook.
United States Patent |
3,696,373 |
Dunn , et al. |
October 3, 1972 |
ELECTRIC ALARM SCREEN
Abstract
A screen with mesh wires of one extension of conductive material
electrically separates from screen wires of the opposite extension
which may be conductive or nonconductive, is held in a frame having
side members each having troughs to receive and hold the wires or
strands. Two sets of wire connectors in one trough and one set of
wire connectors in an opposite trough establish runs spaced
transversely to the conductive strands across the screen mesh. A
connector from each set in a trough is next adjacent a connector
from the other set. One continuous electrical path back and forth
across the screen mesh is established, as are parallel
discontinuous paths intermediate the spaced runs of the continuous
path. Leads from the screen frame conventional join the connector
sets into an alarm circuit including conventional open circuit and
closed circuit detectors. The detectors are adapted to actuate an
alarm--which may be audible, visual, or recording--when the screen
is cut or shorted.
Inventors: |
Dunn; John Malcolm (San
Clemente, CA), Hornbrook; George Kenneth (Monrovia, CA) |
Family
ID: |
22047103 |
Appl.
No.: |
05/063,127 |
Filed: |
August 12, 1970 |
Current U.S.
Class: |
52/664; 160/10;
160/371; 340/550; 160/368.1; 200/52R |
Current CPC
Class: |
G08B
13/126 (20130101) |
Current International
Class: |
G08B
13/02 (20060101); G08B 13/12 (20060101); G08b
013/00 () |
Field of
Search: |
;340/273,274,276
;200/52D |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Habecker; Thomas B.
Assistant Examiner: Partridge; Scott F.
Claims
We claim:
1. An alarm screen for use with electrical open circuit and closed
circuit detectors linked to a perceivable alarm, the combination
comprising side and end members defining a screen frame, means for
securing the frame at an opening, a screen mesh receptor in the
members of the screen frame, a screen mesh having conductive
strands of one extension electrically separate from strands of
opposite extension, a plurality of electrical connectors in each of
two opposed screen frame members establishing a continuous
electrical path back and forth across the screen mesh through the
conductive strands, a continuous connector conductor on one of the
two opposed screen members, connector elements spaced along the
conductor and making electrical contact with transversely spaced
conductive strands, and means electrically connecting the
connectors and the continuous conductor to the detectors.
2. Apparatus in accordance with claim 1 wherein each strand of the
screen mesh of one extension comprises a conductive wire, and
wherein each strand of opposite extension comprises a nonconductive
wire.
3. Apparatus in accordance with claim 1 wherein each strand of the
screen mesh comprises a conductive wire, and an insulating sheath
on the wire.
4. Apparatus in accordance with claim 3 wherein a second pair of
opposed screen frame members carries on each frame member second
plurality of electrical connectors establishing a continuous
electrical path back and forth across the screen mesh through the
conductive strands of opposite extension, a second continuous
conductor on one of the two opposed screen frame members of the
second pair, connector elements spaced along the conductor and
making contact with transversely spaced conductive strands of the
opposite extension, and means connecting the second connectors and
the second conductor to the detectors.
5. An alarm screen for use with electrical open circuit and closed
circuit detectors linked to a perceivable alarm, the combination
comprising side and end members defining a screen frame, means for
securing the screen frame to on opening, a screen mesh retaining
trough in the members of the screen frame, screen mesh having
conductive strands and nonconductive strands, a screen bead
securing the screen mesh margins in the troughs of the screen frame
members, a continuous conductor on one screen frame member
electrically contacting a plurality of transversely spaced
conductive strands; a plurality of contactors on each of two
opposed frame members each in contact with at least one conductive
strand so as to establish a continuous electrical path back and
forth across the screen mesh through the conductive strands, and
means electrically connecting the conductor and the connectors to
the detectors.
6. Apparatus in accordance with claim 5 wherein the screen bead
carries the continuous conductor and the plurality of
connectors.
7. Apparatus in accordance with claim 5 wherein the conductor
strands of the screen mesh extend transversely to the nonconductor
strands.
8. Apparatus in accordance with claim 5 wherein the screen bead,
the continuous conductor and a plurality of spaced connectors bind
the screen mesh margins to the frame members.
9. Apparatus in accordance with claim 5 wherein the means for
securing the frame to the opening includes connector means linking
the conductor to the closed circuit detector.
10. Apparatus in accordance with claim 5 wherein the means for
securing the screen frame to the opening includes connector means
linking the contactors to the open circuit detector.
11. Apparatus in accordance with claim 5 wherein the continuous
conductor comprises conductive strip, contact fingers extending
from the edge of the strip, and curved portions on said fingers
conforming to the retaining trough and adapted to contact
electrically the conductive strands of the screen mesh at the mesh
margin.
Description
BACKGROUND OF THE INVENTION
The invention relates to electric alarm screens and more
particularly to screens for windows and sliding doors wherein the
screen is conventionally insect mesh which, when cut or
electrically shorted, registers an alarm signal.
Prior attempts to utilize the insect screening at windows and doors
as part of an alarm system have resulted in devices which are
either expensive to install and initially obvious as to purpose, or
devices which are particularly expensive to fabricate and which
have mechanical flaws which enable intruders to defeat the alarm.
Many such devices have required special alarm circuits or
supplementary devices which complicate fabrication, installation
and maintenance. The general type of electric screen alarm related
to the present invention is shown and described in U.S. Pat. No.
3,051,935 issued to C. P. Willson on Aug. 28, 1962, titled
"Protective Screen."
Some of the prior devices have been effective bars to penetration
if the screen mesh is cut in one direction, but prove inadequate
against penetration made by cutting screen strands in the other
direction parallel to the visible alarm path in the screen mesh.
Other devices have required special motion sensitivity instruments
to generate a signal when the screen frame is displaced from its
normal position.
We have invented an electric alarm screen which accomplishes the
objective of normal screen appearance, achieved by utilizing
conventional screen frame and screen mesh strands combined in
unique fashion in a screen alarm which signals when the screen is
cut or when the screen is short-circuited or displaced from normal
position within an opening.
The electric screen alarm of the invention may be combined with
conventional open circuit or closed circuit detectors coupled to
audible, visual, or recording signalling devices. The instant alarm
apparatus, by using conventional screen frame material, including
the screen bead to hold the mesh to the frame, and conventional
screen strands such as metallic copper or galvanized wire and fiber
glass strands (which may be compatible in color with the metallic
strands), has an overall cost considerably lower than other alarm
apparatuses which do not achieve the same results.
SUMMARY OF THE INVENTION
The invention contemplates an alarm screen for use with electrical
open circuit and closed circuit detectors linked to a perceivable
alarm. Side and end members define a screen frame. Means for
securing the frame at an opening preferably includes electrical
connectors to the detectors. Each side and end member may have a
screen mesh receptor or trough by which the margin of the screen
mesh is secured. The mesh has conductive strands of one extension
electrically separate from strands of opposite extension. A
plurality of electrical connectors in each of two opposed screen
frame members establishes a continuous electrical path back and
forth across the screen mesh. A continuous connector conductor on
one of the two opposed frame members has connector elements spaced
along the conductor in electrical contact with transversely spaced
conductive strands to establish a plurality of discontinuous
electrical paths across the mesh. Conductive means insulated from
the frame connect the connectors and the continuous conductor to
the detectors, preferably through the means for securing the frame
to the opening.
In a preferred embodiment the conductive strands are of
conventional screen wire, either galvanized steel or copper. The
strands of opposite extension are nonconductive conventional fiber
glass strands. Alternatively, the strands of both extensions may be
metallic wire covered by an insulating sheath. The screen alarm of
the invention cannot be distinguished from conventional screens,
may use conventional screen mesh materials and framing members, and
can actuate conventional alarm systems when the screen is cut,
shorted or moved from its opening. The invention is applicable to
windows, doors and other screened openings.
These and other advantages of the invention are apparent from the
following detailed description and drawing, wherein like numbers
are used for like parts.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a fragmentary exterior elevation of a wall having
openings covered by screen alarms in accordance with the
invention;
FIG. 2 is an interior elevation of the wall of FIG. 1;
FIG. 3 is a fragmentary sectional elevation taken along line 3--3
of FIG. 1;
FIG. 4 is a fragmentary sectional view taken along line 4--4 of
FIG. 1;
FIG. 5 is a fragmentary exploded view of an alarm screen of
preferred form;
FIG. 6 is a fragmentary sectional elevation taken transversely of a
frame member of the screen of FIG. 5;
FIG. 7 is a fragmentary sectional elevation of the frame member of
an alternate embodiment of the invention;
FIG. 8 is a schematic elevation of a screen including the
electrical linkage to the detectors and alarm;
FIG. 9 is a fragmentary schematic elevation of another alternate
embodiment of the invention;
FIG. 10 is a further alternate embodiment of the invention
employing a screen locking bead with a printed circuit, shown prior
to final shaping;
FIG. 11 is a sectional view of the shaped locking bead taken along
a line similar to line 11--11 of FIG. 10;
FIG. 12 is a fragmentary sectional elevation of a still further
embodiment of the invention shown in place in a window frame;
and
FIG. 13 is a fragmentary sectional view taken along line 13--13 of
FIG. 12, to an enlarged scale.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 and FIG. 2 illustrate opposite sides of a building wall 11
in which there are two window openings 13 and 14. FIG. 1 shows
exterior face 11A, whereas FIG. 2 shows interior face 11B. A glazed
sash 15 occupies window opening 13. The sash may be divided into
several panes. A glazed sash 16 occupies window opening 14. Sash
16, too, may have several panes or lights. In conventional fashion
the sash rests within the window opening.
Exteriorly of each window opening is fixed a framed screen. Opening
13 is covered by an alarm screen 21 and opening 14 is covered by an
alarm screen 22. Each window screen is secured in place by
conductive mounting clips such as a mounting clip 24 of opening 13
and a mounting clip 25 of opening 14. Such mounting clips are fixed
in each corner of the window opening.
Alarm screen 22 has a surround or frame 31. A unique mesh 32 is
stretched and held within the frame. Screen 21 comprises a similar
panel of mesh 32 similarly held within a frame 33.
FIGS. 3 and 4 show the unique nature of the mesh within the frame.
The insect mesh is conventionally woven but of an unconventional
combination of materials. In FIG. 3 mesh 32 has vertical strands 35
interwoven with horizontal strands 36 shown in cross-section.
Strands 36 are nonconductive and shown in FIG. 3 as being of an
insulating material. "Fiberglas" or other like fibrous plastics may
be utilized for the horizontal strands 36. In FIG. 4 strands 36 are
shown interwoven with strands 35 which appear in cross-section in
that Figure. Strands 35 are cross-hatched to show that they are
metallic, and thus conductive. Thus the mesh 32 of FIGS. 1 and 2 is
capable of carrying electrical current across the frame in one
direction.
This capability is used in the apparatus of the invention in the
fashion disclosed schematically in FIG. 2 wherein an alarm 41 is
connected with a closed circuit detector 42 and an open circuit
detector 43. The alarm may be silent or audible. FIG. 2 represents
the wiring scheme between windows, while the wiring schematic for
each screen frame and insect mesh is shown in later Figures.
The alarm may be a conventional battery-operated type, batteries
being preferred so that the potential intruder cannot defeat the
alarm system by disturbing the normal AC supply to the structure.
Electrical contact between the detectors and the alarm screen is
achieved by connecting the detectors to the mounting clips 24 and
25 of the respective windows.
As can be seen from FIG. 2, only three of the corner clips are used
in the circuitry. For instance, mounting clip 24 of window opening
13 is not electrically connected with the alarm circuit.
A lead 51 is common to all alarm screens within the system. It is
connected to the closed circuit detector by a connecting wire 52.
The screens 21 and 22 are interconnected by a lead 54. A similar
lead 54A connects to the next adjoining alarm screen (not shown) in
the system. If there are only the two openings to be secured, a
return lead, indicated by the dotted line B, connects with the line
55 and extends to the open circuit detector.
The open circuit detector is connected in series with the screens
22 and 21 through a lead 61 from the first alarm screen and return
lead 55 and the interconnecting leads 54, 54A, etc. between
adjacent window openings. The series path is completed through each
alarm screen by means of the conductive strands 35 in a manner to
be explained later. A connective line 62 links each detector 42 and
43 to the alarm 41. The closed circuit detector is connected to the
open circuit detector by a lead 64, in addition to being connected
to line lead 51 and in parallel to each of the alarm screens
through connecting lead 66 which is joined to lead 51 at each
succeeding alarm screen at a point similar to point A.
FIGS. 5 and 6 illustrate in exploded view and section the physical
arrangement of the unique screen of the invention. A mesh 32 has
vertical strands 35 and horizontal strands 36, of which strands 36
are nonconductive and strands 35 are conductive. A conventional
retaining bead 72 of horseshoe configuration is usually of a linear
plastic material and nonconductive. Likewise, conventional side
frame 71 is conventionally of aluminum, therefore conductive, and
contains a screen bead trough 73 and a flat inner face 74 with
spaced mounting holes 75.
An insulating channel 76, having a trough 77, is adapted to fit
into the trough 73 of the side frame and has a flat flange 78
adapted to fit over the face 74 of the framing member. The channel
76 may be made of any suitable electrically insulating material,
like plastic. The flange 78 has holes 79 spaced to coincide with
holes 75 of face 74. A plurality of conductive connectors 80, each
with U-shaped contacts 81, 82 spaced at opposite ends of the
spanner and connected by a flange 83 with a hole 84, are adapted to
seat on flat flange 78 of the insulating channel with the U-shaped
contacts 81, 82 fitting into the trough 77 of the channel 76.
An insulator strip 85 with spaced holes 86 is commensurate in width
with the flanges 74, 78 of the framing member and the insulating
channel.
A closed circuit detector connector strip 87 of conductive material
has spaced contacts 88 of U-shaped configuration adapted to fit
into the trough 77 of the insulating channel 76. The contacts 88
are lodged in trough 77 intermediate the contacts 81, 82. Strip
flange 89 has holes 90 spaced to insure proper contacts
location.
As can be seen from FIG. 6, the side frame 71 receives the
insulating channel 76 and the contacts 81, 82 and 88 after which
screen mesh 32 is locked in the channel in contact with the
conductive connectors 80, 87 by screen bead 72. The strands 35 are
thus intermittently and alternately contacted by the contact
members 81, 82 and 88 along the width of the screen mesh, as shown
if FIG. 8.
In order to maintain electrical discontinuity between the flanges
83, 89 and 74, an insulating rivet 91, which may be of a pull, or
blind type, rivet, is lodged through each of the various aligned
holes 75, 79, 94, 86, and 90 of the flanges to secure the component
parts to the frame.
An alternative to the blind rivet is illustrated in FIG. 7 wherein
the connecting holes are slightly larger and receive a flanged
insulating grommet 92 through which a self-fastening metal screw 93
penetrates to threadably engage with the flat frame flange 74
without contacting the conductive connectors 80 and 87.
Referring again to FIG. 8, the alarm screen 22 is shown with
parallel spaced side frames 71, each of which has a plurality of
conductive connectors 80 attached thereto in the manner described
with respect to FIGS. 5 and 6. Additionally, the lower side frame
in FIG. 8 has the connector strip 87 in contact with certain of the
conductive strands 35 which extend between the side frames 71 of
the screen alarm. Each side frame has a terminal spanner 94. The
spanners are diagonally opposite each other in the screen alarm.
Each spanner has a post terminal 95 adapted to electrically connect
to a mounting clip 25 as described with respect to FIG. 2.
Conductive connector strip 87 terminates rightwardly in the Figure
in a post 96 similar in function to the post terminals 95, both
post and terminal being electrical extensions of the connector or
connector strip. A nonconducting post 97 is diagonally opposite
post 96. It is electrically null.
End frames 98 of conventional screen design are fixed to side
frames 71 and mesh 32 is secured in the end frames in conventional
manner by a screen bead (not shown).
The contacts 81, 82 of the opposite conductive connectors are
aligned parallel to the conductive strands 35 in staggered array so
that the electrical path is from the second contact of a connector
through the strands to the first contact of a connector, across the
connector to the second contact thereof, and then back across the
mesh by way of another set of strands 35 to another connector
contact. The conductive strands are schematically illustrated in
FIG. 8 such that only those strands contacted by connector contacts
80, 81 and 88 continue across the screen alarm. The intermediate
strands 35 are shown only fragmentarily. Thus each conductive
strand 35 extends from one connector 80 to another connector 80 on
an opposite side frame. The electrical path of the signal is from a
post terminal 95 through the terminal spanner and thence through a
strand group 35A to a connector contact opposite the spanner, then
through a second strand group to a connector contact of a connector
80 on the opposite side frame, and then repetitively from connector
to connector via strand groups to terminate in opposite post
terminal 95.
It can thus be seen that a continuous electrical path is
established through the mesh 32 at spaced intervals across the mesh
from end frame 98 to opposite end frame 98. The mounting clips 25
which make contact with terminal posts 95 are connected to leads 55
and 61 to the open circuit detector, which in turn is connected to
the alarm 41 through lead 62. If any group of strands is severed in
an attempt to gain entry through the mesh, electrical continuity is
broken and the alarm is actuated.
One technique for defeating such detection is to short across the
conductive strands by soldering a conductive wire across the face
of the screen mesh before cutting the strands. In the inventive
apparatus such a technique is foiled by the closed circuit detector
42, which is electrically connected to one of the posts 95 and to
post 96 on the continuous connector strip 87. Each contact 88 of
the continuing strip 87 makes contact with spaced pluralities of
conductive strands 35B which terminate in the side frame opposite
the strip in insulated relationship to the frame, as described with
respect to FIGS. 5 and 6. Any attempt to solder a conductive wire
across the face of the mesh results in the establishment of a
closed circuit between the shorted strands and the strip such that
the closed circuit detector responds by actuating the alarm 41.
In FIG. 9 the apparatus of the invention is further combined with a
corner conductive strip 99 which has a contact 101 adapted to fit
into the trough 77 of side frame 71 and a conductive connector 102
connecting between contact 101 and a second contact 103 adapted to
make electrical contact with the strands immediately adjacent end
frame 98. A null post 97 extends from the corner conductive strip
99. A second corner conductive strip 102 has a contact 106 in
electrical contact with the conductive strands adjacent frame 98
and a terminal post 108, connected by connective strip 107 to
contact 106. The strip 99 and 105 are a part of the circuit
established by conductive connectors 80. Should an intruder attempt
to defeat the screen alarm by removing the mesh 32 from the end
frames 98, the continuity established by the corner conductive
strips would be broken and the open circuit detector would actuate
alarm 41.
As can be seen fragmentarily in FIG. 9, the contacts 81, 82 and 88
of the connector strips 80 and 87 make their normal contact with
the mesh 32 except that each contact is displaced one increment
leftwardly in the Figure as compared with FIG. 8.
FIGS. 10 and 11 illustrate a further alternate embodiment of the
invention wherein the contacts for both open circuit detector and
closed circuit detector are printed upon those portions of the
screen bead which locks the mesh in the frame side members (like
side members 71 of the previously described embodiment). In the
FIGS. 10 and 11 the bead 111 has parallel fold lines 113, 114 which
define an exterior flat wall 115. The folds 113, 114 may be made
subsequent to the printing of the conductive pattern.
A third fold line 116 defines a side wall 117 between the exterior
wall and the fold line. A similar fold line 118 defines a side wall
119 opposite wall 117. Each side wall terminates in a curved end
120, 121, respectively, said curved ends having been formed prior
to the printing of the conductive pattern.
As can be seen from FIG. 10, a continuous connector strip 125 has a
plurality of protruding contacts 126 which extend from a central
connecting bar 127 which is continuous along the length of the bead
paralleling the side frame. A plurality of conductive connectors
130 have spaced contacts 131, 132 extending toward fold line 118
from short connecting bars 133. Both the connecting bars 133 and
the continuous connecting bar 127 are located on the exterior wall
115 such that they extend from trough 73 of the side frame to be
electrically connected to detector circuitry in the manner
previously described with respect to the embodiment of FIG. 8.
Conventionally, the printed circuitry is plated copper and the
screen bead 111 may be of any of those plastics, such as mylar or
vinyls which successfully accept metallic deposits or can be
surface treated to accept such plating.
The continuous connector strip 125 is parallel in function to the
connector strip 87 of the previously described embodiment and the
conductive connectors 130 are parallel in function to the
connectors 80 previously described with respect to FIGS. 5 and 8.
The embodiment of FIG. 10, while possibly more expensive to
fabricate than are the separate metallic components of FIG. 8,
saves time and labor at assembly with the screen frames.
FIGS. 12 and 13 show a further alternate embodiment of the
invention wherein a screen alarm 141 covers an opening 142 in a
structure. A sliding sash 143 moves in the opening between guide
stops 144, 145. An opening framing member 147 has a recess 18 which
may be cut into the framing members on all four sides of the
opening or defined by the offset of the exterior trim fastened to
the framing members of the opening. The recess 148 is therefore
extended on all four sides of the opening.
A framing member 151 similar to the member 71 of the previously
described embodiments contains the connector strips and insulating
strips schematically represented at 152. The strips are of the type
shown at 80, 87 and 76, 85 in FIG. 5, along with the fasteners of
FIG. 6. The screen bead 154 also contains in electrical contact
with the components 152, a screen mesh 156 made up of horizontal
and vertical strands 158, 159, respectively.
The screen alarm 141 may be secured to the opening in conventional
fashion and electrical continuity with the alarm circuitry is
achieved by a contact sleeve 161 lodged in the opening framing
member near the corner of the screen to contact the chosen
connector strip or conductive connector. An electrical lead 163
extends from the sleeve upwardly through the framing member by
means of a duct 165 preferably bored upwardly through the framing
member to give access to an attic or crawl space through which the
alarm wiring may extend to the detector and alarm components (not
shown). Contact sleeve 161 resides in a bore 167 cross-bored to
intersect vertical duct 165.
By lodging the screen wire in an opening recess like recess 148,
the electrical components of the screen alarm may be concealed.
Would-be intruders can be further inhibited by varying the
positions of the mounting clips 25 from window to window of a
structure.
In addition, as indicated in FIG. 13, the horizontal and vertical
strands may both be of a metallic core with an outer cover of
insulation such that the conductive paths of the mesh may be
horizontal or vertical, depending upon the desire of the installer.
The concealment and optional electric paths give further
opportunity to defeat the efforts of intruders to circumvent the
alarm system.
The apparatus of the invention has been illustrated by several
embodiments. These embodiments in no way exhaust the scope of the
invention, and many other embodiments within the scope of the
invention will occur to those skilled in this particular art. It is
therefore desired that the invention be measured by the appended
claims rather than by the purely illustrative apparatus disclosed
herein.
* * * * *