GB2205670A

GB2205670A - Letter box flap opening signalling system

Info

Publication number: GB2205670A
Application number: GB08711659A
Authority: GB
Inventors: Shaun William Thomas; Brian Leslie Thomas
Original assignee: THOMAS LESLIE REUBEN
Current assignee: THOMAS LESLIE REUBEN
Priority date: 1987-05-18
Filing date: 1987-05-18
Publication date: 1988-12-14
Anticipated expiration: 2007-05-18
Also published as: GB2205670B; GB8711659D0

Abstract

The system comprises detecting means 8. e.g. a switch for location adjacent a letter-box opening, and for detecting movement of a letter-box flap 3 and providing an output electrical signal upon such detection, and an alarm device 10 for providing a warning upon opening of the flap. The output electrical signal provided by the detection means may be supplied to one or more bells, buzzers or lights to provide either an audible or a visual warning that the flap is opened or both audible and visual warnings. The detecting means may be connected to bells which form part of the alarm system or may be connected to a conventional doorbell. <IMAGE>

Description

ALARM SYSTEM This invention relates to an alarm system, and more particularly to an alarm system for alerting the occupier of a building that the letter-box of the building is open or has been opened.

It is usual to provide the front door of a dwelling with a letter-box, an opening provided for the delivery of mail and other items such as newspapers.

The opening usually has a flap at the outside, which may open either outwardly or inwardly, and may also have an inwardly opening flap at the inside.

As the front door of a building often opens into a hallway or a room, a person resident in the building may be alerted that, for example, mail has been delivered, by hearing the opening of the letter-box and the mail falling in through the door. Often, however, since the hallway or room is not permanently occupied, this noise will not be loud enough to overcome other sounds within the building, and the delivery will go unnoticed until the delivered mail is seen by the occupier.

In particular, this may be a problem where a delivery is being specifically awaited, or if the occupier is either deaf, and hence unable to hear the delivery, or blind, and hence unable to see that something has been delivered.

Moreover, while it is possible to protect most vulnerable parts of a building against entry, for example by fitting alarm systems on doors and windows, letter-boxes have been used as a means for putting burning materials into homes, often causing serious damage.

Thus, the present invention seeks to provide a device which can be used to alert the occupier of a building that the letter-box is open or has been opened.

According to the present invention, there is provided an alarm system, comprising detecting means, for location adjacent a letter-box opening, and for detecting movement of a letter-box flap and providing an output electrical signal upon such detection.

The alarm system may conveniently be combined with the letter-box to form a unit which can be built into a door. Alternatively, the detecting means may be able to be located such that it can detect movement of a flap of a letter-box which is already installed.

The output electrical signal provided by the detection means may be supplied to one or more bells, buzzers or lights to provide either an audible or a visual warning that the flap is opened, or both audible and visual warnings. The detecting means may be connected to bells which form part of the alarm system or may be connected to a conventional doorbell.

The detecting means may comprise a piston switch, located within the letter-box, if the external flap opens outwardly, or a rotary slider switch, located on a sidewall of the letter-box, if the external flap opens inwardly, or any other suitable switch for detecting movement of a flap.

Timer means may be incorporated to provide or maintain an alarm operating signal for a limited or specified time after a single opening of the flap or, if the flap is left open, to prevent continuous sounding of an alarm signal.

For a better understanding of the present invention, and to show how it may be brought into effect, reference will now be made, by way of example, to the accompanying drawings, in which:- Figure 1 shows an alarm system in accordance with this invention.

The alarm system is housed in a casing 1 adjacent a letter-box 2 which has an outwardly opening flap 3.

The system has an on-off switch 4, which may be operated manually. The casing 1 is connected to a door 5 by screws, of which two 6a,6b are shown, and one of which 6a also acts, via lead 7, as a terminal for an electric lead.

Located partly in the opening of the letter-box is a piston slider switch 8, which is positioned such that movement of the letter-box flap by a predetermined amount, say 10mum, will cause a contact to be broken, and hence cause a signal to be passed along a lead 9 to an electric bell, located remotely from the letter-box in a housing 10, which also holds batteries which power the system. A return lead from the electric bell has zh omitted from the Figure for clarity, as has a return lead from the switch 8.

The casing 1 may, for example, be made of a plastics material or a metal alloy, and may be formed into an approximately cubic shape, with each side being approximately 50mm long. The switch 8 may be a piston slider switch, as illustrated, or may be any switch which will detect motion of the flap 4 by providing an electrical signal when such motion causes an electrical contact to be either made or broken. Thus, it may be adapted for use either with a letter-box flap which opens outwards or one which opens inwards. The switch 8 is connected to the on-off switch 4, in this illustrated embodiment, by a spring contact 11.

Conveniently, the on-off switch 4 may be used to switch the system off at times when deliveries are expected or when the room, into which the letter-box opens, is occupied. The system may more usefully be left on when deliveries are not expected, and thus it is desired to receive an indication that the letterbox has been opened, or when the room into which the letter-box opens is empty, but the occupier of the building is in an area provided with a bell, buzzer or light which indicates that the letter-box has been opened.

If the letter-box is of the type in which the letter-box flap serves as a door knocker, then this system may also be used to provide a visual indication that the door has been knocked, or to provide an audible indication in a part of the building where the knocker would normally be inaudible.

To provide a warning if the letter-box is used to put burning materials into the building, the alarm system of the present invention may be combined with a smoke detector located above the letter-box, for providing an alarm signal when the letter-box is opened and smoke is detected shortly afterwards.

It will be appreciated that the system shown in the accompanying Figure is merely illustrative of the broad concept of the invention, and that many alternative configurations are possible. For example, the switch 8 may be a slider switch as shown and, if so, may either be a two-pole microswitch or may have a return lead connected to the power source in the housing 10. Contained in the casing 1 may also be one or more relays or timers, for example so that opening of the letter-box flap causes the generation of an output electric signal of at least a predetermined minimum and/or at most a predetermined maximum time duration.

Thus, the present invention provides an alarm system which may be of considerable assistance to those concerned about the vulnerability of their homes to such attacks. Further, when combined with suitable audible or visual signals, the system may be useful for the blind or deaf, or to anyone who wants an indication that their letter-box has been opened.

Claims

1. An alarm system, comprising: detecting means, for location adjacent a letterbox opening, and for detecting movement of a letter-box flap and providing an output electrical signal upon such detection.

2. An alarm system as claimed in claim 1, further comprising an alarm device, to which the output electrical signal may be fed in order to provide a warning upon opening of the flap.

3. An alarm system as claimed in claim 2, wherein the detecting means is connected to a conventional doorbell.

4. An alarm system as claimed in any preceding claim, wherein the detecting means comprises an electrical switch.

5. An alarm system as claimed in any preceding claim, wherein the detecting means comprises a piston switch, for location within the letter-box.

6. An alarm system as claimed in one of claims 1 to 4, wherein the detecting means comprises a rotary slider switch, for location on a sidewall of the letter-box.

7. An alarm system as claimed in any preceding claim, further comprising timer means, for providing or maintaining an alarm operating output electrical signal for a limited or specified time after a single opening of the flap or, if the flap is left open, to prevent continuous output of the alarm operating signal.

8. An alarm system as claimed in any preceding claim, combined with the letter-box to form a unit which can be built into a door.

9. An alarm as claimed in one of claims 1 to 7, wherein the detecting means is able to be located such that it can detect movement of a flap of a letter-box which is already installed.,

10. An alarm system, substantially as herein described with reference to, and as shown in, the accompanying drawing.