HEARING-PROTECTOR PLUG

Abstract: A hearing-protector plug is made of a plug material in which is distributed a detectable means in powder form, especially consisting of iron powder. If lost, e.g. in the food industry, the plug can be traced with the aid of detection equipment.

Description: HEARING-PROTECTOR PLUG Field of the Invention The present invention relates to a hearing-protector plug, in the following referred to as an ear plug, which is designed to be applied in the ear and comprises means that enable it to be detected if lost. Description of the Prior Art In the food industry in particular, it is important that foreign objects are not lost, thereby possibly ending up in the foodstuff. This also goes for ear plugs. Previously, efforts have been made to eliminate this inconvenience by interconnecting two ear plugs by a band or a cord. Under unfavourable conditions, however, an ear plug may nevertheless be lost. Further, the entire unit comprising the two ear plugs and the band or string may, of course, be lost as well. In recent years, ear plugs have therefore been equip¬ ped with special means that can be detected with the aid of conventional detection equipment usually operating mag¬ netically or electrically, whereby a lost ear plug can be traced. EP-Al-0,244,979 discloses the provision of a special metal ferrule in the shank portion of an ear plug, one end of a connecting cord being fixed in the metal ferrule which in turn is mounted by press fit in an axial hole formed in the shank of the plug. If a lost ear plug of this type is to be detected, the metal ferrule has to stay in place in the ear plug. However, this is not always the case, and the metal ferrule may instead stick to the end of the connecting cord. When it does, the lost ear plug, of course, cannot be detected. US-A-4,936,411 discloses an ear plug similar to that described in EP-A1-0,244,979. In this case, however, a detectable metal sphere is mounted in the hole formed in the shank of the ear plug, inwardly of the fixing point of the end of the associated connecting cord. This is meant to ensure that the metal sphere will at all times stay with the ear plug if this is lost. It will, however, be appreciated that a lost ear plug may easily be exposed to such conditions that it comes apart, in particular so that the shank portion of the ear plug detaches itself from the main body thereof. If so, the main body cannot possibly be detected. Object of the Invention The object of the present invention is to provide an improved ear plug of the type stated in the introduction to this specification, thereby obviating the above incon¬ veniences while affording advantages of manufacturing technique and economy, without adversely affecting the other properties of the ear plug. Summary of the Invention This object is achieved by an ear plug presenting the features recited in the appended claims. The ear plug according to the invention is thus mainly characterised in that the means added to give detectability is finely divided and distributed in the plug material, preferably homogeneously distributed throughout the plug. The detectable means can thus be in powder form and be an integral part of the plug material. According to the invention, the detectable means can be simply added to the plug material before the plug is manufactured. As will be appreciated, this involves con¬ siderable advantages as to processing technique and costs. With a homogeneous mixing of the means in the entire plug, also small pieces of a lost plug can be detected, e.g. magnetically or electrically, with the aid of con¬ ventional equipment used e.g. in the food industry. Distributing the means in the plug material accord¬ ing to the invention has been found to have no negative effects on the function of the ear plug or its wearing comfort. The detectable means advantageously consists of a metal powder, preferably iron powder. It will, however, be appreciated that any detectable powder material can be used. Use is advantageously made of iron powder of the type employed in the food and pharmaceutical industries, e.g. in iron tablets. It may thus be a question of water- atomised, sponge-iron-base or electrooxidised iron pow¬ ders. The powder particles are advantageously surface- treated prior to admixture so as to improve adhesion to the plug material and prevent oxidation. Conveniently, the particle size of the pulverulent means should not exceed about 300 μm. The particle size is advantageously between about 50 μm and 200 μm, typically about 80 μm. When the ear plugs are moulded, especially of sili- cone material, the means can be admixed to the plug mate¬ rial prior to moulding. When the ear plugs are made of foamed plastic, the means can be admixed to the plastic material prior to foaming. When the ear plugs are made of fine glass fibres, so-called glass down, the means can be freely distributed in the down, particularly when the plug has a special outer casing. Also, the means can be applied by finishing technique. The invention will be described in more detail below with the aid of an Example. Example For a silicone plug of the type described in our US Patent 4,314,553, where more detailed information on the plug design and so forth can be found, about 40 parts by weight of iron powder type Hoganas E060 was employed per 100 parts by weight of silicone. The iron powder was sur- face-treated by phosphatisation before being admixed to the silicone material. Then, the plug was moulded in conventional manner. The detectability of the resulting plug corresponded to that of a metal sphere with a dia¬ meter of 2.5 mm. For a glass down plug of the type described in our US Patent 4,614,487, where more detailed information on the design, production and so forth can be found, iron powder of the above type was loosely applied on top of the glass down piece before this was formed into a plug around a plunger and simultaneously was provided with an outer casing. After remaining treatment and handling of the plug, the iron powder was found to be freely dis¬ tributed essentially throughout the plug. The amount of iron powder employed amounted to approximately three times the weight of the glass down. In the present application, the term 'hearing- protector plug' is to be interpreted in a broad sense, thus including also a band or cord connected to the plug proper. If so, also the band or cord may, in accordance with the invention, be provided with the detectable means in the same way as the plug or plugs connected thereto. This considerably increases the detectability in banded or corded ear plugs.

Claims: CLAIMS 1. Hearing-protector plug designed to be applied in the ear and comprising means that enable it to be traced if lost, e. g. in the food industry, with the aid of detection equipment preferably operating magnetically or electrically, c h a r a c t e r i s e d in that said means is distributed in the plug material in finely- divided form. 2. The plug of claim 1, c h a r a c t e r i s e d in that said means is homogeneously distributed through¬ out the plug. 3. The plug of claim 1 or 2, c h a r a c - t e r i s e d in that said means forms an integral part of the plug material. 4. The plug of any one of the preceding claims, c h a r a c t e r i s e d in that said means is added in powder form. 5. The plug of claim 4, c h a r a c t e r i s e d in that the particle size of said means is up to about 300 μm, preferably between about 50 μm and 200 μm, typically about 80 μm. 6. The plug of any one of the preceding claims, c h a r a c t e r i s e d in that said means consists of iron powder. 7. The plug of any one of the preceding claims, c h a r a c t e r i s e d by being moulded, especially of a silicone material, said means being admixed to the plug material prior to moulding. 8. The plug of any one of claims 1-6, c h a r a c ¬ t e r i s e d by being made of foamed plastic, said means being admixed to the plastic material prior to foaming. 9. The plug of any one of claims 1-6, c h a ¬ r a c t e r i s e d by being made of glass fibres, said means being freely mixed with the fibres, especially when the plug has a special outer casing, or applied to the fibres by finishing technique. 10. The plug of claim 7, c h a r a c t e r i s e d by comprising between about 10 parts by weight and about 50 parts by weight of iron powder per 100 parts by weight of silicone material.

Inventors: BERG BENGT GOERAN, BERG, BENGT, GOERAN
Applicants: BILSOM AB
Application year: 1992
Main classification: A61F11
IPC codes: A61B19, A61F11