Latch guard for outwardly opening doors

A door latch guard for guarding the latch of an outwardly opening door and for preventing spreading of the door away from an adjacent door frame comprises a cover plate having a first flat portion for connection to the door and a second flat portion adapted to overlie the adjacent door frame. A third portion of the cover plate, between the first and second flat portions, defines a groove adapted to overlie the door and the door frame and to receive a protruding latch strike plate. The groove includes a flat outer portion having a width adapted to accommodate locks installed in the door at a plurality of different backsets. In addition, the cover plate has a cut-out adapted to allow the cover plate to be mounted flat against the door, without interfering with the door lock hardware, yet still receive the protruding latch strike plate, regardless of the backset at which the door locks are installed.

BACKGROUND OF THE INVENTION 
The present invention relates to door security hardware and, more 
particularly, to a door latch guard for guarding the latch of an outwardly 
opening door. 
Conventional door locking mechanisms typically utilize a retractable 
spring-loaded latch operated by a door knob rotatable from either side of 
the door. When the door is closed, the latch contacts a latch strike plate 
causing the latch to recede within the door until it is aligned with a 
socket formed within the door jamb or frame. Once aligned, the latch 
springs into the socket to retain the door in the closed position. The 
door knob typically has a button-type locking mechanism on one side which 
can be actuated to prevent the knob from being rotated to retract and 
disengage the latch from the socket. The opposite side of the door knob 
typically has a key mechanism for disengaging the locking mechanism so 
that the knob can be rotated to retract the latch from the socket and open 
the door. 
Knob-type door locks of the type described above often can be violated by 
techniques commonly used by unwanted intruders. For example, many latches 
can be disengaged from the socket by simply sliding a flexible strip of 
material, such as a plastic credit card, between the door and the door 
frame, thereby allowing the door to be opened even though the door knob is 
incapable of being rotated. Other tampering techniques include inserting 
rigid objects, such as jimmy bars or screwdrivers, between the door and 
the door frame to pry the latch from the socket. The door latch also can 
be disengaged from the socket by spreading the vertical frames of the door 
at the level near the latch. In order to spread the frame, intruders 
commonly use a car-jack type device positioned horizontally between the 
vertical frames of the door at the level of the latch. When the jack is 
cranked, it spreads the vertical frames such that the latch becomes 
partially or totally removed from the socket, allowing the door to be 
opened or easily kicked open by the intruder. 
To avoid the problems associated with most knob-type locking mechanisms 
described above, the owners of commercial and residential buildings often 
install a dead bolt lock in the door, in addition to the knob-type lock. 
Unfortunately, although dead bolt locks are less susceptible to being 
violated by plastic credit cards and the like, they are not totally 
resistant to forced methods of entry involving spreading of the vertical 
frames around the latch to facilitate kick-in attacks. 
To further combat the above-identified problems, so-called latch guards 
have been developed. A typical latch guard comprises an elongated cover 
plate connected to the door and having a portion adapted to overlie the 
adjacent door frame. To accommodate the latch strike plate extending 
outwardly from the door frame, the cover plate has an elongated V-shaped 
groove to provide a space on the inside surface of the cover plate for 
receiving the protruding latch strike plate. These latch guards also 
include an anti-spread pin in the portion of the cover plate that overlies 
the adjacent door frame. The anti-spread pin typically has a shaft adapted 
to extend into a hole in the door frame to limit spreading of the frames 
by an intruder using the methods described above. 
While latch guards of the type described above generally have been 
effective for preventing tampering with the latch and spreading of the 
door frames, they have been plagued by installation problems and other 
undesirable drawbacks. For example, most residential locks are installed 
at a certain distance from the edge of the door called the backset. 
Residential locks typically are installed at a backset of approximately 
23/8 inches, while commercial locks are typically installed at a backset 
of approximately 23/4 inches. When the V-shaped groove of the cover plate 
is properly positioned to accept the protruding latch strike plate, 
oftentimes the cover plate will overlie a portion of the lock hardware on 
the outside surface of the door. Accordingly, the installer must carve out 
a portion of the cover plate to accommodate the lock hardware so that the 
cover plate can be installed flat against the door. 
These carving procedures, however, are a very time consuming and 
undesirable operation. This is true even when only a single lock is 
installed on the door, such as a knob-type lock. Moreover, if both a 
knob-type lock and a dead bolt-type lock are used, the time and trouble in 
making two separate cutouts in the cover plate is doubled. Carving of the 
cover plate generally cannot be avoided, since the failure to carve the 
cover plate to accommodate the lock hardware will cause the V-shaped 
groove to be misaligned with the protruding latch strike plate, such that 
the groove will contact the latch strike plate, rather than freely receive 
it, thus preventing proper installation of the cover plate flat against 
the door. Even in cases where the cover plate is pre-carved to accommodate 
the lock hardware, it usually is not carved to receive both a knob-type 
lock and a dead bolt-type lock. Such pre-carved plates also are not carved 
sufficiently to accommodate locks installed at different backsets, nor are 
they adapted for use with mortise locks or locks having large escutcheons. 
In addition, bolts generally are used to install the latch guard on the 
door. These bolts typically have an enlarged head adapted to engage the 
outer surface of the cover plate, and an externally threaded shaft 
extending through a mounting hole in the cover plate and through a hole in 
the door. An internally threaded retaining nut, such as an acorn nut, is 
used to secure the shaft of each bolt at the back side of the door. In 
some prior art latch guards, however, the mounting holes in the cover 
plate are in such a position that, when the retaining nuts are installed 
on the bolt shaft at the back side of the door, the nuts interfere with a 
door stop on the door frame that keeps the door from swinging inwardly 
during closing of the door. In such cases, the installer must carve out a 
portion of the door stop to receive the protruding nuts. This procedure is 
made especially difficult when steel door frames and door stops are used. 
Oftentimes, the door frame and door stop are filled with concrete for 
reinforcing purposes. Hence, the installer must use two drill bits, one 
for drilling through the steel door stop and one for drilling through the 
concrete behind it, to carve out sufficient space to accommodate the 
retaining nuts. This causes further inconvenience for the installer. 
Accordingly, there has existed a definite need for a latch guard for 
outwardly opening doors that protects the latches on doors having multiple 
locks positioned one above the other, that accommodates the protruding 
latch plates for locks installed at different backsets, and which does not 
require any special drilling or carving operations to install the latch 
guard. The present invention satisfies these needs and provides further 
related advantages. 
SUMMARY OF THE INVENTION 
The present invention is embodied in a door latch guard for guarding the 
latch of an outwardly opening door and for preventing spreading of the 
door away from an adjacent door frame. The latch guard comprises a cover 
plate having a special groove that overlies the door and the door frame 
and that is adapted to receive the protruding portion of a latch strike 
plate. This special groove, in combination with a specially configured 
cutout which enables the cover plate to be mounted flat against the door 
without interference with the door lock hardware, provides a latch guard 
that can be installed on a door having one or more locks installed at a 
plurality of different backsets. The latch guard of the present invention 
furthermore is intended to be relatively inexpensive to manufacture, 
reliable in use and simple to install. 
The cover plate comprises a first substantially flat portion for connection 
to the outside surface of the door, and a second substantially flat 
portion adapted to overlie the adjacent door frame. A third portion of the 
cover plate, between the first and second substantially flat portions, 
defines the groove adapted to overlie the door and the door frame and the 
space therebetween. The groove includes a substantially flat section 
having a width in the preferred embodiment of approximately 0.5 inches. As 
described below, this groove configuration enables the cover plate to 
receive the portion of the latch strike plate protruding outwardly from 
the door frame, regardless of whether the door lock is installed at a 
residential backset of approximately 23/8 inches or a commercial backset 
of approximately 23/4 inches. 
In a related aspect of the invention, the first substantially flat portion 
of the cover plate includes an elongated cutout adapted to accommodate a 
plurality of locks installed one above the other in the door. The cutout 
is defined by the inner edge of the first flat portion of the cover plate 
adjacent to the door hardware of the locks. The first flat portion of the 
cover plate further includes an upper mounting flange positioned above a 
first lock mounted in the door, and a lower mounting flange positioned 
below a second lock mounted in the door below the first lock. The upper 
and lower flanges each have a mounting hole for receiving a bolt adapted 
to connect the upper and lower flanges of the cover plate flat against the 
outside surface of the door. 
Each of the mounting bolts has an enlarged head adapted to abut against the 
outside surfaces of the cover plate's upper and lower flanges, and a 
threaded shaft extending through the mounting holes in the flanges and 
through holes in the door. A portion of each bolt shaft extends through 
the door and protrudes outwardly beyond the inside surface of the door. 
This portion of the shaft has external threads for threaded engagement 
with an internally threaded retaining nut. 
The mounting holes of the upper and lower flanges are positioned such that, 
when the retaining nuts are mounted to the bolt shafts at the inside 
surface of the door and the door is then closed, the nuts are mounted at a 
location spaced inwardly from, and free of interference with, a door stop 
on the door frame that limits inward swinging of the door when the door is 
being closed. Hence, when the door is closed, the retaining nuts will not 
hit or interfere with the door stop. As a result, the installer does not 
need to carve out a portion of the door stop to receive the retaining nuts 
protruding from the inside surface of the door. 
The foregoing configuration of the cover plate, with its specially shaped 
groove and cutout, allows the cover plate to be installed flat against the 
door, without the need for special carving or cutting procedures, 
regardless of the backset at which the locks are installed. When the locks 
are installed at different backsets, the inner edge of the first flat 
portion of the cover plate can be placed adjacent to the door hardware of 
the locks such that the cover plate is flat against the outside surface of 
the door. The cover plate can be adjusted in a horizontal direction, if 
necessary depending on the backset, yet still receive the protruding 
portion of the latch strike plate without interference. This advantage is 
provided by virtue of the groove and its flat portion, which provides a 
relatively wide space to accommodate the protruding latch strike plate 
regardless of the backset involved. 
The latch guard of the present invention can be used on outwardly opening 
doors having either one lock, such as a knob lock, or two locks, such as 
knob lock and a dead bolt lock mounted one above the other. The latch 
guard also can be used to protect the latch on doors having mortise locks 
or locks having large escutcheons. 
Other features and advantages of the present invention will become apparent 
from the following description of the preferred embodiment, taken in 
conjunction with the accompanying drawings, which illustrate, by way of 
example, the principles of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in the exemplary drawings, the present invention is embodied in a 
latch guard, generally referred to by the reference numeral 10, for 
guarding a latch 12 and resisting the unauthorized opening of a locked 
door 14 and, more particularly, an outwardly opening locked door. 
FIG. 1 shows the latch guard 10 installed on the outside surface 16 of the 
door 14 by a pair of mounting bolts 18 and 20. Two door locking mechanisms 
are installed on the door, comprising a knob lock 22 and a dead bolt lock 
24. The knob lock 22 and the dead bolt lock 24 are shown mounted one above 
the other in the conventional manner. 
The knob lock 22 utilizes a retractable spring-loaded latch 12 operated by 
door knobs 26 and 28 rotatable from either side of the door 14. When the 
door 14 is closed, the latch 12 contacts a latch strike plate 30 causing 
the latch to recede within the door until it is aligned with a socket 32 
formed within an adjacent door jamb or frame 34 (see FIG. 3). Once 
aligned, the latch 12 springs into the socket 32 to retain the door 14 in 
the closed position. The inward travel of the door 14 is limited by a door 
stop 36 connected to the door frame 34 that is adapted to engage the back 
or inside surface 38 of the door when it is completely closed and the 
latch 12 is received within the socket 32. 
The door knob 28 on the inside surface 38 of the door 14 typically has a 
button-type locking mechanism (not shown) which, when engaged, prevents 
the door knobs 26 and 28 from being rotated to disengage the latch 12 from 
the socket 32. The other door knob 26 on the outside surface 16 of the 
door 14 typically has a key mechanism 40 to disengage the door's locking 
mechanism such that the door knobs 26 and 28 can be rotated to retract the 
latch 12 from the socket 32. The dead bolt lock 24 also has a latch (not 
shown) adapted to be received within a socket of the door frame 34 in a 
conventional manner. 
As shown best in FIGS. 1 and 3, the latch guard 10 comprises a cover plate 
42 having a first substantially flat portion 44 adapted to overlie the 
outside surface 16 of the door, and a second substantially flat portion 46 
adapted to overlie the adjacent door frame 34. If necessary, the second 
flat portion 46 of the cover plate 42 overlying the door frame 34 may be 
offset slightly from the first flat portion 44 overlying the door 14 in 
order to accommodate door trim 48 or the like connected to the door frame 
34. 
In accordance with the invention, the cover plate 42 further includes a 
third portion 50 between the first and second flat portions 44 and 46 
defining a groove 52 adapted to overlie the door 14 and the door frame 34 
and the space 54 therebetween. The groove 52 comprises a substantially 
flat outer section 56 at a location furthest from the outside surface 16 
of the door 14. As explained in more detail below, this flat section 56 
effectively widens the total width of the groove 52, such that the groove 
is adapted to receive a portion of the latch strike plate 30 protruding 
outwardly from the door frame 34, and such that the groove is wide enough 
to receive the latch strike plate for a lock installed in the door at a 
plurality of different backsets. 
In this regard, most residential locks are installed at a predetermined 
distance "d" from the edge 58 of the door 14 closest to the door frame 34. 
This distance "d" is called the backset. For example, most residential 
locks are installed at a backset of approximately 23/8 inches, while most 
commercial locks are installed at a backset of approximately 23/4 inches. 
By providing a relatively wide groove 52 with a relatively flat outer 
section 56, the latch guard 10 of the present invention is adapted to be 
mounted on the outside surface 16 of the door 14, without interfering with 
any door hardware 60 of the knob lock 22 or the dead bolt lock 24, yet 
still receive the protruding latch strike plate 30 when the locks 22 and 
24 are installed in the door 14 at a plurality of different backsets. 
More particularly, the third portion 50 of the cover plate 42 defining the 
groove 52 comprises a first tapered section 62 tapered outwardly from the 
door 14 and connected to the first flat portion 44 of the cover plate, and 
a second tapered section 64 tapered outwardly from the door frame 34 and 
connected to the second flat portion 46 of the cover plate. The flat outer 
section 56 connects the first and second tapered sections 62 and 64 to 
each other. In this way, the first tapered section 62, the second tapered 
section 64 and the flat outer section 56 define the groove 52 that is 
spaced outwardly from the door 14, the door frame 34 and a space 54 
therebetween. In the preferred embodiment, the width of the flat outer 
section 56 is approximately 0.5 inches, and the overall width of the 
groove 52 is approximately 1.5 inches. 
In a related aspect of the invention, the cover plate 42 is mounted to the 
door 14 by a pair of mounting flanges comprising an upper mounting flange 
66 and a lower mounting flange 68. The upper mounting flange 66 is spaced 
above the dead bolt lock 24, and the lower mounting flange 68 is spaced 
below the knob lock 22. This configuration of the upper and lower flanges 
66 and 68 effectively provides a cutout 70 in the first flat portion 44 of 
the cover plate 42 overlying the outside surface 16 of the door 14. In 
one-embodiment of the invention, the vertical distance "D" between the 
bottom edge of the upper mounting flange 66 and the top edge of the lower 
mounting flange 68 is approximately 83/4 inches. This vertical distance 
"D" of 83/4 inches is large enough to accommodate most doors having two 
locks installed one above the other, as shown in FIG. 1. 
The cover plate 42 is mounted to the outside surface 16 of the door 14 by 
an upper mounting bolt 18 and a lower mounting bolt 20. Each of these 
mounting bolts 18 and 20 is the same and, therefore, only the upper 
mounting bolt 18 will be described in connection with FIG. 2. The upper 
mounting bolt 18 has an enlarged head 76 for engagement with the outside 
surface of the upper mounting flange 66 and has a shaft 78 received 
through a mounting hole 80 in the upper mounting flange 66 and through a 
hole 82 in the door 14. A portion of the bolt shaft 78 protrudes from the 
inside surface 38 of the door 14 and has external threads for threaded 
engagement with an internally threaded retaining nut 84, such as an acorn 
nut. The lower mounting flange 68 is secured to the door 14 by the lower 
mounting bolt 20 in the same manner described above. 
The foregoing configuration of the cover plate 42, and the cooperation 
between the groove 52 and the cutout 70, enables the cover plate to be 
installed on an outwardly opening door 14 in which, for example, the knob 
lock 22 and the dead bolt lock 24 are installed in the door at a plurality 
of different backsets. Regardless of the backsets of the locks 22 and 24, 
the cover plate 42 can be mounted flat against the door 14, without 
interfering with the lock hardware 60, by virtue of the cutout 70 in the 
first flat portion 44 of the cover plate 42 between the upper and lower 
mounting flanges 66 and 68. 
For example, FIG. 3 shows the knob lock 22 installed in the door 14 in a 
commercial application, in which the knob lock is installed at a backset 
of approximately 23/4 inches. In this application, the inner edge 86 of 
the first flat portion 44 of the cover plate 42 is mounted in close 
proximity to the door hardware 60 of the knob lock 22. At this backset, 
the protruding portion of the latch strike plate 30 is received within the 
groove 52 at a location nearest the second flat portion 46 of the cover 
plate 42. However, if the knob lock 22 and dead bolt lock 24 were 
installed in a residential application at a backset of approximately 23/8 
inches, then it would be necessary to mount the cover plate 42 at a 
location on the door 14 closer to the edge 58 of the door. It is necessary 
to move the cover plate 42 in this manner so as not to interfere with the 
lock hardware 60, which is closer to the edge 58 of the door 14 by virtue 
of the smaller backset associated with the residential application. 
Nevertheless, when the cover plate 42 is moved closer to the edge 58 of 
the door 14, the protruding portion of the latch strike plate 30 is still 
received within the groove 52 without interfering with the cover plate. It 
will be appreciated that, by moving the cover plate 42 closer to the edge 
58 of the door 14 (to the right in FIG. 3), the protruding portion of the 
latch strike plate 30 will be received within the groove 52 at a location 
that is closer to the first flat portion 44 of the cover plate 42. 
The ability of the cover plate 42 to be installed on the door 14 at a 
plurality of different backsets, without interfering with the door lock 
hardware 60 or the protruding latch strike plate 30, provides several 
important advantages. One very significant advantage is that the installer 
does not need to carve out a portion of the cover plate 42 to accommodate 
the lock hardware 60 so that the cover plate can be installed flat against 
the door 14. This greatly reduces the amount of time necessary to install 
the latch guard 10. By eliminating carving of the cover plate 42 when two 
locks 22 and 24 are installed on the door 14 one above the other, the 
latch guard 10 of the present invention saves further time and trouble for 
the installer, since it is not necessary to make two separate cutouts in 
the cover plate. Thus, when double locks 22 and 24 are involved, 
installation time is reduced even further. Instead, the installer need 
only place the cover plate 42 on the outside surface 16 of the door 14 
centered over the latch 12 (or latches) of the door lock 22 (or locks) and 
free of interference with the door lock hardware 60. During this centering 
process, the cover plate 42 can be adjusted in a horizontal direction so 
that the protruding portion of the latch strike plate 30 is received 
freely within, and does not interfere with, the groove 52. The center of 
the mounting holes 80 in the upper and lower mounting flanges 66 and 68 is 
then marked on the door 14 by a pencil or other suitable marking 
instrument, and the cover plate 42 is removed. Two holes 82 are then 
drilled through the door 14 corresponding to the markings which in the 
preferred embodiment are 5/16 inch in diameter holes. The cover plate 42 
is repositioned on the door 14 and the mounting bolts 18 and 20 are 
inserted through the mounting holes 80 in the cover plate and through the 
holes 82 in the door and secured by the retaining nuts 84. 
In a further aspect of the invention, the mounting holes 80 in the upper 
and lower mounting flanges 66 and 68 of the cover plate 42 are positioned 
such that, when the retaining nuts 84 are installed on the bolt shaft 78 
at the inside surface 38 of the door 14, the nuts do not interfere with 
the door stop 36. This advantage of the invention is provided by providing 
sufficient vertical distance "D" between the upper and lower mounting 
flanges 66 and 68 such that they may be mounted, respectively, above and 
below the locks 22 and 24 (or lock) in the door 14. This allows the 
mounting holes 80 to be located on the upper and lower mounting flanges 66 
and 68 at a location that is spaced inwardly from the edge 58 of the door 
14 by a sufficient amount to avoid interference with the door stop 36 
abutting against the inside surface 38 of the door. 
This feature of the invention allows the cover plate 42 to be installed on 
the door 14 without requiring the installer to carve out a portion of the 
door stop 36 to receive the protruding nuts 84. Eliminating these carving 
procedures it is especially advantageous when steel door stops are 
involved. Oftentimes, these door stops and their associated door frames 
are filled with concrete for reinforcing purposes. Hence, the installer 
does not need to carry two drill bits, one for drilling through the steel 
door stop and one for drilling through the concrete behind it, since it is 
totally unnecessary to carve out any space in the door stop 36 to 
accommodate the retaining nuts 84. This greatly minimizes the amount of 
time needed to install the latch guard 10 of the present invention. 
As shown in FIG. 2, the latch guard 10 of the present invention also may be 
provided with an anti-spread pin 88 to prevent spreading of the door frame 
34 away from the door 14 by an intruder using a car-jack device (not 
shown) or the like. The anti-spread pin 88 is positioned in the second 
substantially flat portion 46 of the cover plate 42 such that the pin 
overlies the adjacent door frame 34. A hole 90 drilled in the door frame 
34, for example, a 3/8 inch diameter hole approximately 3/4 inch deep, is 
adapted to receive the anti-spread pin 88 when the door 14 is closed. In 
this way, attempts to spread the door frame 34 away from the door 14 are 
defeated because the anti-spread pin 88 effectively connects the door 
frame 34 to the door 14. 
The latch guard 10 of the present invention can be used on outwardly 
opening doors 14 having either one lock, such as a knob lock 22, or two 
locks, such as knob lock 22 and a dead bolt lock 24 mounted one above the 
other. The latch guard 10 also can be used to protect the latch on doors 
having mortise locks or locks having large escutcheons. 
From the foregoing, it will be appreciated that the present invention 
provides a latch guard 10 for outwardly opening doors 14 that protects the 
latches 12 on multiple locks positioned one above the other and which 
accommodates the protruding latch strike plate 30 for locks 22 and 24 
installed at a plurality of different backsets. Installation of the latch 
guard 10 is relatively quick and trouble free, since no special drilling 
or carving operations are necessary to install the latch guard. 
While a particular form of the invention has been illustrated and 
described, it will be apparent that various modifications can be made 
without departing from the spirit and scope of the invention. Accordingly, 
it is not intended that the invention be limited, except as by the 
appended claims.