GB2335566A - Antimicrobial shield for a telephone handset or like acoustic apparatus - Google Patents

Abstract

A shield for a telephone handset 20 comprises a piece of material 1 which has sound transmitting qualities, for example expanded thermoplastic foam (PVC, PVA), natural or synthetic rubber, fabric or paper and which may be shaped to match the shape of the telephone handset. The material is treated with an antimicrobial compound to provide it with antimicrobial properties and is provided with means to attach it to the phone, for example adhesive with peelable release sheet, studs which engage the handset or it may be self stick. The material may incorporate a coloured dye which fades to indicate that the shield needs replacing and/or a porous carrier such as polyethelyne glycol. The antimicrobial substance may be chlorhexidine, possibly with azodicarbonate. The material may be treated with a fragrance and may have perforations 3 to improve the passage of sound. The shield can also be used with microphones, headphones, headsets etc.

Description

ANTIMICROBIAL SHIELD 2335566 This invention relates to an antimicrobial

shield and more particularly to such a shield for telephone mouthpieces, earpieces or other like devices.

The problem exists with items which are used close to the human respiratory systems, when these items are used by a large number of different people, that bacteria are transmitted from one user to the item, the bacteria then remaining in situ ready to infect other users.

Attempts in the past have been made to overcome this problem, to some extent, by regular sterilization and cleaning of the items and while this can cut down on the amount of bacteria present in the long term, it does not protect the user from bacteria which may be deposited on the item between sterilization& Particular problems arise when the items are public telephones which can be used very frequently by any one. It is aggravated by the very close proximity of the mouthpiece with the mouth and actual contact between the user's ear and the earpiece.

The present invention seeks to provide a shield which can be used in conjunction with telephones and like apparatus and which will inhibit or kill bacteria coming in contact with it but will readily pass sound therethrough.

According to the invention there is provided a shield for use in a telephone handset or like apparatus comprising a piece of material having sound transmitting qualities, the piece of material being treated with an antimicrobial compound which provides the treated material with antimicrobial qualities and means for the attachment of the piece of material to the telephone handset or like apparatus.

Example 1

A batch of antimicrobial material was prepared by mixing 10 grams of Chlorohexidine and 20 millilitres of Polyethylene Glycol with a molecular weight of 400, 25 grams of Azodicarbonate with 945 grams of PVC. The resultant mix was coated onto a release paper and expanded under heat to produce a sheet of expanded foam material of the closed cell type. This sheet was then cut to provide a number of disks, suitably of 33mm diameter which is the standard size of a telephone mouth or earpiece.

Example 2

A batch of antimicrobial material was prepared by mixing 10 grams of Chlorohexidine and 20 grams of Polyethylene Glycol with a molecular weight of 400, with 970 grams of PVC. The resultant mix was coated onto a release paper and expanded under heat to produce a sheet of expanded foam material of the closed cell type. This sheet was then cut to provide a number of disks, suitably of 33mm diameter.

In all of the above examples, a high level of plasticizer was used so as to render the surface in contact with the release sheet self adhesive thus avoiding the necessity of using an additional adhesive for fixing of the disks.

There are a number of possibilities to enhance the disks in use.

Firstly, the disks may be perforated to increase sound transmission although as later tests have shown, this would not normally be necessary.

The discs could be additionally impregnated with an antiseptic fragrance.

Figure 2 is a section of the shield of Figure 1 taken on the line 11 - 11, and Figure 3 is a perspective view of a telephone handset fitted with a shield as shown in figures 1 and 2.

The drawings show one example of a shield in accordance with the invention. It comprises a disc 1 of a foam material to which has been added, in the course of the production of the base material, an antimicrobial material. Examples of the material used will be given hereafter.

In the example shown, the surface is printed with indicia 3, which, in addition to the use of inks, may be indented as shown more particularly at 5 in figure 2.

The periphery 7 of the disc 1 is coated on the underside with a low peel adhesive 9. Other methods of securing the disc 1 will also be discussed hereafter. Preferably the underside of the disc 1 is covered with a release sheet 11, at least over the areas coated with adhesive.

In use, the release sheet 11 is peeled from the disk 1 and the disk is pressed firmly over the mouthpiece 21 of a handet 20. It will be understood that while the use of the shield is shown in figure 3 in connection with the mouth piece, it could also be used on the earpiece 23. Because of the nature of the adhesive, when it is desired to replace a used disk with a fresh one, the old disk can be simply pealed from its location and a new disk applied.

Other methods of attachment may be used. For example, the disc could be produced from heavily plasticised PVC or Polypropylene so that it exhibits self stick properties. Otherwise, the disc could, instead of being cut from sheet material, be injection moulded with studs which can fit snugly into the holes or apertures in a telephone mouth or ear piece.

Examples of the process for producing the shields will now be considered:The table below shows the inhibition zones on tests conducted by The Royal Hampshire County Hospital (Department of Microbiology). As can be seen from this table, the tested samples showed excellent antimicrobial properties.

ORGANISM STRAIN COUNT ZONE IN MM ZONE IN MM DTE READ 51101 51103 E.COLI 8196 8.8xl 0 5 2 28.11.93 S.AUREUS 8532 3.2xl 0 1 1 28.11.93 LEGIONELLA WILD 15 16 27.04.94 S.AURREUS 8532 2.4Xl 0 13 3 24.02.95 E.COL1 8196 6.8Xl 0 16 6 24.02.95 MRSA 11940 6 2 28.09.95 Acoustic Testing Testing was also carried out to determine the sound transmissive properties of the pads.

A sample circular pad of 40mm diameter was cut from a strip of foam plastics material prepared as above in Example 1. The pad was fitted centrally over the apertures in the mouthpiece of a telephone handset so that all apertures were covered, The pad was retained in place by a "PrittsticW adhesive, the handset being an Eagle type TH7SP.

The handset was held vertically using a retort stand 15cm in front of a Tannoy loudspeaker (cabinet dimensions 30cm by 50cm) with the handset mouth piece facing towards the loud speaker opposite to its centre point.

The output signal from the microphone in the handset was measured using a Bruel and Kajer sound level meter type 2203 fitted with octave band filters type 1613. The loudspeaker was fed with a white noise signal from a Bruel and Kajer sine-random signal generator and the signal from the mouthpiece microphone was measured in octave bands 125Hz to 8000Hz. The pad was then removed from the mouthpiece and the measurements were repeated.

The disks could incorporate or be printed with a dye or ink which is sensitive either to air or light such that the colour will fade when the disk needs to be replaced.

Indentations, such as those shown at 5 in figure 2, could be produced by printing the material before foaming with a pattern of inhibitor material prior to the application of the disk material so that foaming at these areas is inhibited. The above described disk examples are particularly intended to combat Gram positive and Gram negative bacteria and accordingly, samples made in accordance with the above examples were tested for effectiveness:- Antimicrobial Testing Petri dishes containing nutrient algar were seeded with one of the following test bacteria:

Escheria coli NCTS 8196 Escheria coli NCTS 9484 Escheria coli NCTS 10418 Staphylococcus aureus NCTC 4163 Staphylococcus aureus NCTC 8532 Staphylococcus aureus NCTC 8625 Listeria Wild strain Salmonella NCTC 4776 A 1 cm square sample of the antimicrobial disk was placed aseptically onto the surface of each seeded dish. The dishes were then placed in a refrigerator at 4 degrees Centigrade overnight to allow the antimicrobial agent to migrate into the algar. The dishes were then removed from the refrigerator and examined for growth inhibition, the inhibition zones being measured and photographed.

Claims (14)

1. A shield for use in a telephone handset or like apparatus comprising a piece of material having sound transmitting qualities, the piece of material being treated with an antimicrobial compound which provides the treated material with antimicrobial qualities and means for the attachment of the piece of material to the telephone handset or like apparatus.

2. A shield as claimed in claim 1, wherein the piece of material is cut from a sheet of the material.

A shield as claimed in claim 1, wherein the piece of material is injection moulded.

4. A shield as claimed in claim 1, 2, or 3, wherein the piece of material is formed from an expanded thermoplastics foam.

5. A shield as claimed in claim 1, 2, or 3, wherein the piece of material is formed of natural or synthetic rubber.

6. A shield as claimed in claim 1, 2, or 3, wherein the piece of material comprises a fabric or paper having the requisite sound transmitting properties.

7. A shield as claimed in any preceding claim, wherein the shield comprises a disk of the said material adapted to the dimensions of a telephone ear piece or mouth piece.

8. A shield as claimed in any preceding claim, wherein the means for attachment comprises a low peel adhesive coated on one side of the said piece of material.

The results showed that there was no measurable difference in any of the seven octave frequency bands between the sound pressure measurement with or without the pad. This proves that any differences were less than one decibel, which was the level of precision of these tests, and would be completely unnoticeable to the human ear.

While the above embodiments have been described in relation to the positioning of antimicrobial discs on a telephone mouthpiece, it will be appreciated that it could equally well be used on the earpiece. Instead of the use of disks just covering the apertures in the mouth or earpiece, a shroud like cover could be provided for the whole of the mouth or earpiece.

Alternatively, the shield could be fitted inside the handset if the handset was suitably modified during manufacture to receive it.

It will also be appreciated that the invention is equally applicable to like apparatus. Such apparatuses include hand microphones, stage and public address microphones and headsets.

9. A shield as claimed in claim 8, wherein the low peel adhesive is covered with a release sheet.

10. A shield as claimed in any preceding claim, wherein the material comprises PVC mixed with Chlorohexidine, and Polyethylene Glycol.

11. A shield as claimed in claim 10, wherein the material additionally comprises Azodicarbonate

12. A shield as claimed in any preceding claim, wherein the piece of material is formed with a pattern of indentations.

13. A shield as claimed in any preceding claim, wherein the piece of material incorporates a coloured dye or ink sensitive to ambient conditions such that the colour will fade over a predetermined period of time to indicate the need for replacement of the shield.

14. A shield for use with a telephone handset or like apparatus substantially as described herein with reference to the drawings.