GB2320347A

GB2320347A - Inflatable cellular support cushion or mattress detector

Info

Publication number: GB2320347A
Application number: GB9625181A
Authority: GB
Inventors: Dieter Smith
Original assignee: Hodgkinson and Corby Ltd
Current assignee: Hodgkinson and Corby Ltd
Priority date: 1996-12-04
Filing date: 1996-12-04
Publication date: 1998-06-17
Also published as: GB2321136A; GB9625181D0; GB2321136B; GB9725780D0

Abstract

A detector or an inflatable cellular cushion or mattress, the detector including upper and lower frame members 10,12 with interposed foam material 14. A switching means is provided to operate an alarm, this means being shown as conductive compression springs 20, which contact a conductive layer formed on the lower and upper surfaces respectively of frame members 10,12, thereby setting off an alarm when the correct degree of compression of the mattress has been achieved.

Description

INFLATABLE CELLULAR SUPPORT CUSHION OR MATTRESS DETECTOR The patent invention relates to a detector for use in an inflatable cellular support cushion or mattress.

Such cushions or mattresses are commonly used to support patients who are, for example, confined to wheelchairs, or who are required to sit or lie for an extended period, thereby preventing the patient from bedsores or other soreness.

A typical example of such a cushion is that shown in US Patent No. 5,163,196. In such a device of this general type, a large number of upstanding inverted pockets are provided and these are inflated, usually by a hand pump, to a particular pressure and the cushion or mattress is then ready for use. However, it is of the utmost importance that the correct inflation should be achieved to suit the requirements of the particular patient whose weight and other physical characteristics will be different from those of another patient. Currently the only way is to guess at a correct value for a particular patient and perhaps use the preset pressure for that particular patient. This is far from satisfactory.

It is now proposed, according to the present invention, to provide a detector for use in an inflatable cellular support cushion or mattress, said detector comprising first and second substantially parallel frame members, compressible support means positioned between said frame members, said support means allowing said frame members to move resiliently towards and away from one another, electrical sensor means sensitive to the spacing between said frame members and an electrical alarm system, actuated by said electrical sensor means, when said sensor means indicates that said frame members are spaced apart by a predetermined distance or less.

The detector is placed between the pockets or cells of the cushion or mattress and the cushion or mattress is then inflated to a value which is clearly higher than that which is necessary for that particular patient. The cushion or mattress is then placed on the chair or bed and the detector according to the invention is positioned between the cells or pockets.

The patient then sits or lies on the cushion or mattress and air is then let out slowly until the alarm is actuated. The passage into the interior of the cushion or mattress is immediately closed and the detector device removed.

By use of such a device, it is possible to obtain a pressure within the inflatable cushion or mattress which is exactly right for that patient to ensure that the cells or pockets do not collapse completely and to ensure that they are not inflated, on the other hand, to too high a value which can subsequently produce discomfort.

The electrical sensor means may take a number of different forms. For example, they could comprise capacitor plates formed on the frame members and an electrical circuit associated therewith to detect when the capacitance of the resulting capacitor drops below a predetermined value and thereby actuates the alarm system.

In an alternative construction, the support means may comprise variable electrical resistance foam and an electrical circuit is associated with the foam to actuate the alarm system when the foam reaches a threshold conductivity upon the frame members being spaced apart by the predetermined distance or less.

A further form involves the use of the support means being electrically insulated, the electrical contact zones being provided at spaced locations along the length of the faces of the frame members directed towards the support means, and spaced conductors being positioned within the support means and arranged to be in electrical contact with the contact zones of both of the frame members, when the frame members are spaced apart by the predetermined distance or less, thereby to actuate the electrical alarm system.

With such a construction the frame members may be formed from rigid resin sheet material and the resin sheet material may be provided with a metallic coating on one of its faces to provide the contact zones.

The support means of such a structure may comprise plastic foam material provided with openings therein, the openings containing the conductors. In a particularly advantageous form the conductors are in the form of metallic compression springs.

In order to ensure complete safety, the frame members and the support means are preferably completely surrounded by a flexible insulation such as a sheet rubber housing.

The alarm means may include a light and/or a buzzer and a venting tube may be provided to allow air to be expelled from the interior of the detector. This venting tube may also serve to carry the electrical wiring connections from the detector to the alarm system.

In order that the present invention may more readily be understood, the following description is given, merely by way of example, reference being made to the accompanying drawings in which: Figure 1 is a plan view of one embodiment of detector according to the invention, partly in section; Figure 2 is a longitudinal section of the detector of Figure 1; Figure 3 is a circuit diagram for use with the detector; and Figure 4 is a schematic view illustrating one form of inflatable cushion or mattress with the detector of the invention positioned therein.

Referring first to Figures 1 and 2, the detector indicated therein is an elongate assembly, perhaps of the order of one third of a meter in length, and includes upper and lower substantially rigid frame members 10,12. These may be formed of a resin material of the type used to produce printed circuit boards. The lower surface of frame member 10 and the upper surface of frame member 12 are provided with metallic conducting faces, e.g. by tinning these faces.

The frame members 10,12 are adhered to a foam support 14, the reference numerals 16 indicating a number of different points for the application of adhesive.

The foam material support 14 is provided with several openings 18 along its length. These openings are at equally spaced locations along the length and define on the metallic coating spaced contact zones on the frame members 10,12.

Positioned within some or all of the openings 18 are electrical conductors, here shown in the form of coil compression springs 20.

The metallic inner surfaces of the frame members 10,12 are connected to a pair of wires 22,24 which pass out of the detector through a vent tube 26.

The whole assembly is encased in a flexible insulating housing a portion only of which is shown at 28, this being provided with a tube 30 which is sealed to the exterior of the vent tube 26.

The wires 22,24 are electrically connected to a separate unit including the electric circuitry shown in Figure 3. The electric wires 22,24 may be connected into a conventional jack (not shown) which may be inserted into a socket 32. One terminal of the jack will contact the socket 32 and the other terminal the connector 34.

The circuit shown in Figure 3 includes a battery 36, which may produce a potential of 9 volts, for example.

Connected across this potential is a buzzer 38 with a diode 40, and in parallel therewith a resistor 42, and an LED 44.

It will be appreciated that when pressure is placed on the upper frame member 10, the support 14 will be compressed steadily, and when the predetermined load has been placed on the frame member 10 the conductor 20 will connect to the metallic surface on both the upper frame member 10 and the lower frame member 12, thereby acting as a switch which will actuate the alarm in the form of the buzzer 38 and the LED 44.

This will tell either the patient or the carer that the pressure within the inflated cushion or mattress is correct.

Figure 4 illustrates a cushion 50 which is provided with an inflation tube 52, and itself comprises a plurality of upwardly extending pockets 54. The detector of the present invention, illustrated by the reference numeral 56 is inserted between lines of the pockets or cells 54. If desired more than one detector may be positioned in a cushion to give an accurate reading across the whole of a cushion.

When a patient sits on the cushion, the cushion will compress to an extent permitted by the degree of inflation.

The patient or the carer releases air from the cushion until such time as the buzzer sounds and the LED lights up indicating that the correct pressure has been achieved.

Claims

1. A detector for use in an inflatable cellular support cushion or mattress, said detector comprising first and second substantially parallel frame members, compressible support means positioned between said frame members, said support means allowing said frame members to move resiliently towards and away from one another, electrical sensor means sensitive to the spacing between said frame members and an electrical alarm system, actuated by said electrical sensor means, when said sensor means indicates that said frame members are spaced apart by a predetermined distance or less.

2. A detector according to claim 1, wherein said electrical sensor means comprise capacitor plates formed on said frame members and an electrical circuit associated therewith to detect when the capacitance of the resulting capacitor drops below a predetermined value and thereby actuates said alarm system.

3. A detector according to claim 1, wherein said support means comprise variable electrical resistance foam and an electrical circuit is associated with said foam to actuate said alarm system when said foam reaches a threshold conductivity upon said frame members being spaced apart by said predetermined distance or less.

4. A detector according to claim 1, wherein said support means is electrically insulating, wherein electrical contact zones are provided at spaced locations along the length of the faces of said frame members directed towards said support means, and wherein spaced conductors are position within said support means and arranged to be in electrical contact with said contact zones of both of said frame members, when the frame members are spaced apart by said predetermined distance or less to actuate said electrical alarm system.

5. A detector according to claim 4, wherein said frame members are formed from rigid resin sheet material and wherein said resin sheet material is provided with a metallic coating on one of its faces to provide said contact zones.

6. A detector according to claim 5, wherein said support means comprise plastic foam material provided with openings therein, said openings containing said conductors.

7. A detector according to claim 5 or 6, wherein said conductors are in the form of metallic compression springs.

8. A detector according to any preceding claim, wherein said frame members and support means are completely surrounded by a flexible insulation.

9. A detector according to any preceding claim, wherein said alarm means include a light and/or a buzzer.

10. A detector according to any preceding claim, wherein a venting tube is provided to allow air to be expelled from the interior of said detector.

11. A detector according to claim 10, wherein said venting tube also serves to carry electrical wiring connections from the detector to said alarm system.

12. A detector for use in an inflatable cellular support cushion or mattress, said detector means substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.