GB2316537A

GB2316537A - Pressure sensitive mat switch

Info

Publication number: GB2316537A
Application number: GB9617222A
Authority: GB
Inventors: John Cocker
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-08-16
Filing date: 1996-08-16
Publication date: 1998-02-25
Also published as: GB9617222D0

Abstract

A pressure mat comprises a pair of electrically conductive layers 10, 11, separated by an insulating layer 12 of foamed plastics material, and an upper covering layer 14 of an elastomeric material. One of the electrically conductive layers 10 is provided with an array of conductive pyramid-shaped projections 13 on its rear surface. The layers 10, 11, 12, 14 are retained together at their edges by a channel-section frame member 15, which extends around the periphery of the mat. In use, when pressure is applied to the mat, the projections 13 penetrate the insulating layer and short-circuit the electrically conductive layers 10,11, thereby allowing current to flow between the layers.

Description

Pressure Sensitive Switch This invention relates to a pressure sensitive switch, for example in the form of a pad or mat.

Pressure sensitive switches are well known, one such switch comprises a mat for placing on the floor. In use, when a person steps on the mat its terminals become short-circuited, thereby allowing a bell or alarm to be activated. A disadvantage of these pressure mats is that they are complicated in construction, and are correspondingly relatively expensive.

I have now devised a pressure sensitive switch which alleviates the above mentioned problems.

In accordance with this invention there is provided a pressure sensitive switch comprising a pair of electrically conductive layers separated by a layer of insulating material, a said electrically conductive layer being provided with an electrically conductive projection on its rear surface, which projects towards said insulating layer, the projection being arranged to penetrate the insulating layer and thereby shortcircuit the electrically conductive layers when the layers are compressed.

A switch in accordance with this invention is thus simple in construction and cheap to manufacture.

Preferably the insulating layer is formed of a resiliently flexible material, so that the projection is withdrawn from the insulating layer to its original position, when the compressive force is removed. Preferably the resiliently flexible material comprises an open cell foamed plastics material.

The switch may comprise a mat or pad, in which case an array of projections are preferably provided on said electrically conductive layer.

Preferably one or more outer layers of a protective material, such as an elastomer, are provided.

Preferably the layers are mounted in a channel section frame. The frame may be integrally formed with one of said outer layers.

In one embodiment the projection comprises a spike. In an alternative embodiment, the projection comprises a pyramidshaped formation.

An embodiment of this invention will now be described by way of example only and with reference to the accompanying drawing, the single figure of which is perspective view of a pressure mat in accordance with this invention, with some parts being shown cut away.

Referring to the drawing, there is shown a pressure mat comprising a pair of electrically conductive layers 10, 11, separated by an insulating layer 12 of foamed plastics material, and an upper covering layer 14 of an elastomeric material. One of the electrically conductive layers 10 is provided with an array of conductive pyramid-shaped projections 13 on its rear surface. The layers 10, 11, 12, 14 are retained together at their edges by a channel-section frame member 15, which extends around the periphery of the mat. The lower side of the frame member 15 may be closed by a layer (not shown), which forms a lower covering layer.

Electrical connections (not shown) extend from the electrically conductive layers 10, 11. In use, when pressure is applied to the mat, the pyramid-shaped projections 13 that are disposed underneath the point of pressure are forced to penetrate through the insulating layer 12, thereby shortcircuiting the electrically conductive layers 10, 11. The electrical connections to the layers 10, 11 may be connected to an alarm or other warning device, which provides an indication that pressure has been applied to the mat. The insulating layer 12 of foamed plastics material recovers its shape when the pressure is removed from the mat, so that the layers 10, 11 are no longer short-circuited.

One of the benefits of a pressure mat in accordance with this invention is that its performance is very uniform regardless of where the pressure is applied. One use of the pressure mat is as a door bell activator, which is primarily intended for use by dogs, the purpose being to allow the animal to attract its owner's attention to be let in, without scratching at the door. The mat could be situated on the door step, so that the bell is activated when the dog stands on the mat. Alternatively, the mat could be fixed to the door or wall, the dog having to apply pressure to the mat using a part of its body.

Claims

1) A pressure sensitive switch comprising a pair of electrically conductive layers separated by a layer of insulating material, a said electrically conductive layer being provided with an electrically conductive projection on its rear surface, which projects towards said insulating layer, the projection being arranged to penetrate the insulating layer and thereby short-circuit the electrically conductive layers when the layers are compressed.

2) A pressure sensitive switch as claimed in claim 1, in which the insulating layer is formed of a resiliently flexible material.

3) A pressure sensitive switch as claimed in claim 2, in which the resiliently flexible material comprises an open cell foamed plastics material.

4) A pressure sensitive switch as claimed in any preceding claim, comprising an array of said projections disposed on said electrically conductive layer.

5) A pressure sensitive switch as claimed in any preceding claim, comprising an array of said projections disposed on said electrically conductive layer.

6) A pressure sensitive switch as claimed in any preceding claim, in which the layers are mounted in a channel section frame.

7) A pressure sensitive switch as claimed in any preceding claim, comprising one or more outer layers of a protective material.

8) A pressure sensitive switch as claimed in claim 7 as appended to claim 6, in which the frame is integrally formed with one of said outer layers.

9) A pressure sensitive switch as claimed in any preceding claim, in which the projection comprises a spike.

10) A pressure sensitive switch as claimed in any of claims 1 to 8, in which the projection comprises a pyramid-shaped formation.

11) A pressure sensitive switch substantially as herein described with reference to the accompanying drawing.