AU2004100251A4 - Lock guard - Google Patents

Description

TITLE

"LOCK GUARD" FIELD OF THE INVENTION THIS INVENTION relates to a device for use in a door and, in particular, a security screen door. The invention particularly relates to a lock guard that may be easily applied to a conventional metal framed door which incorporates a spline channel.

BACKGROUND OF THE INVENTION Security screen doors have the advantage of allowing circulation of air while preventing access to the interior of a building by insects. Security screen doors also resist intruders by the use of metal lattice-type screens.

In general, it is advisable to use a barrier plate to prevent or limit access to the inside component of the door lock. This prevents tampering with the locking snib with is a mechanism for locking the door without the key. Typically, such plates are welded or screwed in position which requires additional time and labour costs during assembly of the doors.

Reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia.

SUMMARY OF THE INVENTION Throughout this specification, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or integer or group of elements or integers but not the exclusion of any other element or integer or group of elements or integers.

In a first aspect, the invention resides in a lock guard for use on a security screen door or similar, the lock guard comprising: a planar section; a tongue offset from and continuous with one edge of the planar section; a projection from the tongue, the projection adapted to engage a wall of a spline channel of a frame of the door.

The planar section is preferably dimensioned to provide adequate coverage as a lock guard.

-2- The tongue preferably extends from the edge of the planar section at an acute angle, preferably in the range of 700 to 850.

The tongue preferably extends the full length of the edge of the planar section.

The projection is preferably adapted to engage with a serrated wall of the spline channel. The projection may be formed as a barb and preferably a continuous linear barb along the tongue. The barb is preferably adapted to insert into a channel in the wall of the spline groove.

The lock guard may be formed from any suitable material but is preferably formed from metal, such as aluminium, or a rigid plastic. Polycarbonate or similar material may be particularly effective.

The lock guard is preferably dimensioned to snap into position with the tongue and barb inserted into the spline channel and an outer edge of the planar section abutting, at least in part, the infill material.

In a further aspect, the invention resides in a method of forming and positioning a lock guard for a security screen door, the method comprising the steps of: forming a lock guard comprising a planar section, a tongue extending from the planar section, the tongue having a linear barb; positioning the lock guard with the tongue and linear barb aligned with a spline channel of a door frame; and urging the barb and tongue into the spline channel so that the lock guard is locked into position.

The lock guard may be formed substantially with the features described above.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a top view of a first embodiment of a lock guard of the present invention; FIG. 2 is a side view of the lock guard of FIG. 1 with FIG. 2A showing representative dimensions and angles of a ledge and barb arrangement; FIG. 3 is a lower isometric view of the embodiment of FIG. 1; FIG. 4 is an isometric view of the positioning of a lock guard relative to a -3section of a door; FIG. 5 shows the arrangement of FIG. 4 with a lock guard advanced towards its operative position; FIG. 6 shows the arrangement of FIG. 5 further advanced into operating position; FIGS. 7 to 9 show side views of the process of FIGS. 4 to 6.

DETAILED DESCRIPTION OF THE DRAWINGS Referring to FIG. 1, there is seen a lock guard 10 having a front edge 11, rear edge 12 and side edges 13, 14. A tongue 16 is shown in hidden detail.

FIG. 2 shows the embodiment of FIG. 1 in side view. The lock guard can be seen to have a substantially planar section which extends away from side edge 13.

At its front edge 11, the planar section is continuous with the tongue 16 which is shown projecting from the planar section 17 at an acute angle. That is, the tongue 16 extends at an angle less than 900 and, in this case, approximately 80 in a fashion that creates a slight return. The tongue 16 has a barb 18 which projects in a direction back towards the planar section. Representative angles and dimensions are shown in FIG. 2A wherein the acute angle is around 80'. The barb has an outer angle of approximately 30' relative to an axis parallel to the planar section 17 ahd the barb point is formed by a 350 truncation of the outer edge of the barb.

FIG. 3 shows a lower isometric view of the arrangement of FIGS. 1 and 2.

In FIG. 4, a lock guard 10 is positioned relative to a section of a screen door comprising a frame member 20 and security screen infill material 21 forming a mesh. The frame member 20 is formed with an internal channel 22 and inner projecting ledge 23 which supports a spline channel 24. The spline channel 24 has serrated or ribbed walls.

The tongue 16 is lined up with the spline channel 24 and the rear edge 12 is positioned inwardly of the frame member 20. The infill material 21 is preferably of rigid material formed as a series of interconnected components in a repeating pattern to provide apertures for air movement while excluding intruders. The apertures may be dimensioned small enough to exclude at least some insects. A fine mesh material may be overlaid on the rigid web.

In FIG. 5, the arrangement of FIG. 4 has been advanced so that the -4tongue 16 and barb 18 are entered into the spline channel 24.

This process is continued until the arrangement of FIG. 6 is obtained as the tongue 16 and barb 18 snap into position in the spline channel with the barb locking against one or more of the grooves 26. The rear edge 12 has also advanced into abutting contact with the infill material 21 to provide a locking action which will be further described below.

FIGS. 7, 8 and 9 show a sideway view of the process of FIGS. 4 to 6. The lock guard 10 is aligned in FIG. 7 with the tongue 16 positioned above the spline channel 24 and the rear edge 12 of the lock guard clear of the infill material 21. The lock guard 10 is advanced in FIG. 8 so that the tongue 16 and barb 18 are positioned in the spline channel 24 and the rear edge 12 abuts the infill material 21.

In FIG. 9, the lock guard 10 has been snapped into position so that the barb 18 is urged against a rib of the spline channel 24. The rear edge 12 is forced against the infill material 21 so that the linear barb engages with the rib or serrated edge of the door frame spline channel. When fully engaged, competing forces are generated between the barb 18, particularly the barb point, an upper outer corner 28 of the tongue and the rear edge 12 of the lock guard being forced against the infill material 21. If necessary, the lock guard may be removed by applying force to the middle of the planar section and directed towards the infill material and an outwardly directed force at point 30 to disengage the barb and free the lock guard.

The present lock guard has a number of advantages including efficiency in manufacture and installation. The lock guard may simply be snapped into position to provide a useful, long wearing and safe arrangement. The lock guard may be formed with any suitable dimensions. One preferred size is around 240mm long by 100mm wide. The tongue may extend approximately 12.5mm inwardly. If a mosquito mesh is used, the lock guard may be applied as a locking point over the section of frame to which it is applied. A locking spline may be fitted into the spline channel to retain the mosquito mesh in traditional fashion but ending at either side of the lock guard. The present invention provides a useful and easily produced addition to a door construction which enhances security for a user.

Throughout the specification, the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. Those of skill in the art will therefore appreciate that, in light of the instant disclosure, various modifications and changes can be made in the particular embodiments exemplified without departing from the scope of the present invention. All such modifications and changes are intended to be included within the scope of the appendant claims.

Claims (4)

1. A lock guard for use on a security screen door or similar, the lock guard comprising: a planar section; a tongue offset from and continuous with one edge of the planar section; a projection from the tongue, the projection adapted to engage a wall of a spline channel of a frame of the door.

2. The lock guard of claim 1, wherein the tongue preferably extends from the edge of the planar section at an acute angle, preferably in the range of 700 to 850.

3. The lock guard of either one of claim 1 or claim 2, wherein the projection is formed as a continuous linear barb along the tongue, the barb adapted to insert into a channel or serration in the wall of the spline groove and wherein the lock guard is dimensioned to snap into position with the tongue and barb inserted into the spline channel and an outer edge of the planar section abutting, at least in part, an infill material.

4. The lock guard of any one of claim 1 to claim 3, wherein the lock guard is formed from a metal, such as aluminium, or a rigid plastic such as polycarbonate. A method of forming and positioning a lock guard for a mesh door, the method comprising the steps of: forming a lock guard comprising a planar section, a tongue extending from the planar section, the tongue having a linear barb; positioning the lock guard with the tongue and linear barb aligned with a spline channel of a door frame; and urging the barb and tongue into the spline channel so that the lock guard is locked into position. DATED this second day of April 2004. Moonbush Pty Ltd by DAVIES COLLISION CAVE Patent Attorneys for the Applicant