Lockable letter box assembly

Abstract

A letterbox assembly suitable for mounting on a wall or a door includes a flap 10 connected to a frame 12. The flap 10 is biased to its closed position by a spring 18. The flap 10 can be locked using

Description

This invention relates to a lockable letter box for location in an outer door or wall (hereinafter referred to simply as a "door") of a building and more especially to a selectively lockable letter box which, when unlocked, provides access to suitably dimensioned articles from the exterior to the interior of said building and which when locked, prevents such access. The invention further relates to such a letter box which prevents or inhibits the passage of ignited items. BACKGROUND TO THE INVENTION In addition to its conventional function of enabling letters and other suitably dimensioned items to be conveniently delivered to a household or business, letter boxes have in the past been used by unscrupulous members of the public to introduce into a building a variety of unpleasant and sometimes highly dangerous items. Indeed, on occasions fires have been initiated by flammable items being introduced into buildings through letter boxes causing extensive damage and potential harm not only to the fabric of the buildings but, more importantly, to residents of such buildings. The present invention sets out to provide a letter box which can selectively be locked from the inside of a building to prevent unwanted items being introduced into said building. The invention further sets out to provide such a letter box which additionally prevents or inhibits the passage of ignited items. SUMMARY OF THE INVENTION In one aspect the invention provides a letter box assembly for installation within a suitably dimensioned opening formed in a door of a building, the assembly including a frame and a spring loaded metallic flap supported on a spindle which, in turn, is supported by side walls of said frame, said metallic flap being operable, in use, selectively to open or fully close said opening to allow or prevent the passage of articles, said metallic flap including on its intended innermost side following installation, a locking mechanism which is operable selectively to either prevent or permit the passage of items through said opening. The inner side of the metallic flap preferably includes a coating of a material which intumesces in the presence of fire and / or excessive heat. Additionally, or alternatively, the letter box may include an internal liner which is coated or lined with a material which intumesces in the presence of excessive heat. The locking mechanism may comprise a rotatable key member which projects from said frame and through an opening formed in the metallic flap when said flap is in its closed position, the key member being selectively turned from a first position in which it allows the flap to open and a second position in which it prevents such opening. In another aspect the invention provides a letter box assembly which comprises an open-ended frame for location in a suitably dimensioned opening formed in a door of a building and which supports a spring-loaded metallic flap which is operable selectively to open or close said opening and which is lined with a material which intumesces in the presence of fire and / or excessive heat, said assembly including on its intended innermost side a locking mechanism operable selectively to prevent or permit the passage of items through said opening. BRIEF DESRIPTION OF THE DRAWINGS The invention will now be described by way of example only with reference to the accompany diagrammatic drawings in which: - Figure 1 is a front view of a letter box in accordance with the invention when closed; and Figure 2 is a front view of the letter box illustrated in Figure 1 when open. DETAILED DESCRIPTION OF THE DRAWINGS The letter box illustrated in in the drawings comprises a generally rectangular door or wall mounted metallic flap 10 connected to a frame 12 by an elongate horizontally extending pin 14 which extends through and is supported within suitably dimensioned openings formed inside walls 16 of the frame 12. A helical spring 18 is located on each end of the pin 14 to bias the flap to its closed position. As will be seen from Figure 2, the central part of the pin 14 locates within a channel defined by bending the lower edge section 20 of the flap 10 through an angle approximating to 180 degrees to define an open-topped channel. A sealing strip 22 is adhered to the inner face of the lid 10. The frame 12 is securable to a selected door or wall of a building by screws which project through openings 24. The closable central opening of the letter box is referenced 26. The metallic flap 10 is formed with an elongate opening 28 which is dimensioned to receive as a relatively close fit a locking member 30 which projects from a base 32 secured to the frame 12. The locking member can selectively be turned by hand through 90 degrees from the position shown in Figure 1 in which items are prevented from being passed from one side of the door or wall opening to the other, to the position shown in Figure 2 in which the flap is not restrained to enable suitably dimensioned items to pass freely from one side of said door or wall opening to the other side. In this way, the user is able to physically and effectively close the opening 24 during, for example, times of darkness or other times when postal or other similar items are unlikely to be received. It will be appreciated that the foregoing is merely exemplary of letter boxes in accordance with the invention and that modifications can readily be made thereto without departing from the true scope of the invention as set out in the appended claims.

Claims

1. A letter box assembly for installation within a suitably dimensioned opening formed in a door of a building, the assembly including a frame and a spring loaded metallic flap supported on a spindle which, in turn, is supported by side walls of said frame, said metallic flap being operable, in use, selectively to open or fully close said opening to allow or prevent the passage of articles, said metallic flap including on its intended innermost side following installation a locking mechanism which is operable selectively to either prevent or permit the passage of items through said opening.

2. An assembly as claimed in claim 1 wherein the inner side of the metallic flap includes a coating of a material which intumesces in the presence of fire and / or excessive heat.

3. An assembly as claimed in claim 1 wherein the letter box includes an internal liner which is coated or lined with a material which intumesces in the presence of fire and / or excessive heat.4 . An assembly as claimed in any one of the preceding claims wherein said locking mechanism includes a rotatable key member which projects from said frame and through an opening formed in said metallic flap when in its closed position, the key member being selectively turned from a first position in which it permits the flap to open and a second position in which it prevents such opening.

5. A letter box assembly which comprises an open-ended frame for location in a suitably dimensioned opening formed in a door of a building and which supports a spring-loaded metallic flap operable selectively to open or close said opening and which is lined with a material which intumesces in the presence of fire and / or excessive heat, said assembly including on its intended innermost side a locking mechanism operable selectively either to prevent or permit the passage of items through said opening.

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