GB2050757A

GB2050757A - Earpiece for fastening to a protective helmet

Info

Publication number: GB2050757A
Application number: GB8011247A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-04-20
Filing date: 1980-04-03
Publication date: 1981-01-07
Also published as: GB2050757B; FR2454739B1; ATA151480A; AT364397B; FR2454739A1; SE8002918L; CH652265A5; DE2915990B2; DE2915990A1; DE2915990C3

Abstract

A radio earpiece, e.g. for a motor cyclist or fireman, comprises a casing 2 fitted to a hole in an ear region 19 of a helmet (1, Fig. 1) so as to be externally disposed relative to the helmet with a sealing ring 14 located in a groove in annular end face 13 of the casing sealing the latter against the outer surface of the helmet. In the illustrated case, the casing 2 is secured by a flanged fixing ring 17 which screws into the casing 2 but the casing 2 could have an extension which projects into the hole and is held by means within the helmet. <IMAGE>

Description

SPECIFICATION Earpiece for fastening to a protective helmet This invention concerns an earpiece for fastening to a protective helmet.

Such earpieces are used, for example, by policemen, firemen, military personnel, building workers, miners and other persons who wear protective helmets whiist at work and are furnished with radio receiving apparatus of which an earpiece forms part.

Hitherto, such earpieces have been designed so that they can be fastened to the inside of a protective helmet, for example in a space in padding of the helmet. An arrangement having a receiving capsule mounted thus in an outwardiydirected bowl-shaped protruberance of the protective helmet is described, for example, in the specification of Gebrauchsmuster No. 7,811 1,272 of the Federal Rebublic of Germany.

The mounting of known earpieces, if they are to be used in a normal helmet without such a protniberance, would only be possible if they are designed to occupy only a very small space available in the helmet; being so small, they cannot be designed to posses optimal acoustic properties, and can have only small capacity. In addition earpieces mounted inside the helmet are troublesome for the wearer of the helmet, more particularly because of the presence of wires which lead from the earpiece to the radio. These wires are a continual nuisance, and come into contact with the wearer's neck when he turns his head.

An object of the invention is to provide an earpiece which is mountable in a simple way in a protective helmet, which can be built to have good acoustic properties and so as to be protected from outside influences, and which is not troublesome to the helmet wearer. A further object is to provide a form of earpiece as aforesaid which can be so constructed that it can be fitted to a helmet without the use of tools or without the use of special tools.

With these objects in view, the present invention provides an earpiece for fastening to a protective helmet characterised in that it comprises an electro-acoustic transformer accommodated in a casing which is open at one end and is watertightly closed at its other sides, the casing opening being surrounded by a hollow cylindrical casing wall part having an annular end face in which there is a sealing ring; and in that the casing is adapted to be fastened, from the outside of a helmet, in a hole provided in an ear region of the helmet, so that the annular face abuts by the sealing ring against the outside of the part of the helmet wall which surrounds the hole.

Preferred features of the proposal of the invention are set forth in the claims, appendant to claim 1, appearing at the end of this specification.

Many protective helmets have, at each side thereof, each in an ear region of the helmet, a respective hole disposed so that the helmet wearer can hear well. The receiver in accordance with the invention can be mounted in one of these two holes without the slightest intrusion into the helmet being necessary.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a side view illustrating a protective helmet having a preferred embodiment of the earpiece of the invention fastened to it; Fig. 2 is an enlarged section through the earpiece shown in Fig. 1 , the section having been taken on the line Il-Il of Fiy. 2; Fig. 3 is an elevation, seen from the inside of the helmet, showing a ring which holds the earpiece in position on the helmet, as well as half of a seive-mesh and a half cf a filter-cover which protect a membrane of a transformer of the earpiece; Fig. 4 is a section similar to Fig. 2, but showing a second embodiment of the earpiece; and Fig. 5 is a similar section but showing a further embodiment of the earpiece.

The earpiece shown in Figs. 1 to 3 comprise a cylindrical pot-shaped casing 2 adapted to be fitted on the outisde of a protective helmet 1 and in which is accommodated a dynamic receiving capsule 3 whose front side is abutted by a holding ring 22 and whose rear wall abuts an elastic ring 5 which encircles a resonance space 4. The resonance space 4 communicates through an acoustic resistance 23 and a hole 24 in the rear wall of the receiving capsule 3 with the space in said capsule 3 behind its membrane 3a. To protect the membrane 3a of the capsule 3, a sieve-mesh 7, and a filter cover 6 in the form of a perforate sheet, are fitted at the front side of the receiving capsule 3, which cover 6 and mesh 7, together with the space in front of the membrane 3a, can form an acoustic filter. Instead of the parts 6 and 7, or in addition thereto, a protective membrane (not shown) may be provided.The receiving capsule 3 is connected to a connecting wire 9 (Fig. 1) by way of a separable connector 8 which is impervious to moisture and screws onto a spigot formed integrally with the casing 2.

Casing wall part 11, which is in the form of a hollow cylinder and surrounds front opening 10 of the casing 2, has an internal thread 12. On its front face 13 which is an annular end surface of the casing, an O-ring 14 is located in a circular groove.

A fixing ring 17, which is provided at one end with an externally-threaded part 1 5 and at its other end with an outwardly-protruding flange 1 6, is screwed by its threaded part 1 5 from the inside of the helmet 1, through a hole provided in an ear region of the helmet 1, into the casing wall part 11 which is disposed outside the helmet 1. The ring 17 has four blind holes 18 so that it can be screwed tightly to the casing wall part 11 by means of a corresponding spanner. Upon it being so screwed in place, portion 1 9 of the helmet wall which surrounds the hole is clamped between the flange 1 6 and the O-ring 14, so that the casing 2 is secured firmly and watertightly to the helmet 1.

The watertight property of the casing 2 and the way it is mounted are important, particularly for protective helmets for police, firemen and motor cyclists since the casing 2, which is unprotected on the oustide of the helmet 1, may frequently be exposed to moisture, e.g. as rain or from water jets.

With the embodiment shown in Fig. 4, the casing 2 has a hollow cylindrical extension 123, with an outer thread 124, which penetrates the hole in the helmet 1 and has screwed thereon a nut 25 which is also provided with blind holes 1 8 to enable it to be turned. This nut 25 is inside the helmet wall and engages with the outer thread 24 of the extension 23. The helmet material 19 around the hole is clamped fast then between the nut 25 and the O-ring 14 which sits in its groove in the annular surface 13 which in this case is provided as a shoulder at the junction between the casing portion 11 and the extension 23.

In the embodiment shown in Fig. 5, the casing 2 also has a hollow cylindrical extension 26 formed on the portion 11. This extension 26, as also does the whole casing 2, consists of a resilient material and has, at its free end, an outwardly-projecting rim 27. Axial slits 28 extend through the extension 26 and its surrounding rim 27. Because of the presence of these slits 28, the extension 26, with its rim 27, can be compressed radially for passing into the hole in the helmet 1, whereafter the rim 27 locates against the inside of that part of the helmet wall 1 9 which surrounds the hole, so that this is clamped fast between the rim 27 and the washer 14.To guarantee this, naturally the spacing between the rim 27 and the surface must be measured to correspond to the aggregate of the thickness of the wall part 1 9 with the addition of the thickness of the part of the O-ring 14 which projects from the annular face 13, when said in compressed condition.

With other embodiments (not shown) elastic or resilient tongues are provided on the hollow cylindrical part of the casing wall which surrounds the casing opening, these tongues having their free ends projecting radially outwards in the form of hooks. These tongues yield elastically when passed through the hole in the helmet, whereupon their hook shaped ends hook into the inside of the helmet wall 1 9. With corresponding dimensioning of the spacing between the hook-shaped ends of the tongues and the annular surface 1 3 it can be ensured that the wall part 1 9 is clamped between the hook shaped ends of the tongues and the O-ring 14.

In another variation of the earpiece (which is not shown) a hollow cylindrical extension is formed on the inner wall of the part 11 in a manner similar to that of the embodiment of Fig.

4. This extension has no thread, however, but has, at its free end, a peripheral groove to take a Seeger ring or other resilient ring. Like the extension 23 of Fig. 4, this extension is pushed through the hole in the helmet, whereupon the Seeger ring, at the inside of the helmet, fits itself into the peripheral groove so that the part 19 of the helmet wall is clamped fast between the Seeger ring and the O-ring which locates in the annular surface 13.

In another modification, (shown by the dotted lines in Fig. 2) there is at least one control element set in the end wall of the pot-shaped casing 2 and projecting into the resonance space 4. This control element may be, for example, a tactile switch for a transformer or a volume control 20 with a turning knob 21 for a radio to which the earpiece is to be connected. Naturally the control element is fitted in a watertight manner. This is particularly advantageous if the earpiece belongs to the receiving equipment of a radio which may itself be equipped with a volume control for the earpiece.

Such a radio is often worn in the user's clothing, e.gg under a coat, so that its control elements can only be reached with difficulty, whereas a volume control on the earpiece casing provided on the outside of the helmet, as at 20, 21 in Fig. 2 is always conveniently accessible.

Because the casing 2 is fitted on the outside of the helmet and not - as heretofor - on the inside of the helmet, neither its size nor that of the receiving capsule 3 is inhibited in any way. Thus a large receiving capsule with good capacity can be used and the resonance space can be built so as to have optimum acoustic properties. The volume can then always be set so high that good definition is ensured even when there are loud surrounding noises such as may be the case with police and fire brigage equipment The separable connector 8 serves as a safety device. It enables the wire 9 to disconnect itself from the casing 2 on the helmet 1 if the wire 9 should become caught up.With the embodiment shown in Fig. 5, on the other hand, the connecting wire 29 for the electro-acoustic transformer is fastened to the casing 2. If the wire 29 should get caught up anywhere, with this embodiment the whole casing 2 comes away from the helmet 1 because the extension 26, with its peripheral rim 27, becomes compressed by any forces tending to pull the extension 26 for the hole in the helmet.

In a further variation of the earpiece (not shown) at the open side of the casing 2 a resonance space is incorporated, so as to be coupled acoustically to the front side of the membrane of the transformer, in the form of an acoustically-defined hearing canal.

The fastening of the hollow cylindrical casing wall part to the portion 1 9 of the helmet wall which surrounds the hole can be achieved otherwise than has been shown in the drawings.

For instance it could be stuck, screwed or snapped in any suitable manner.

In contrast to the casing 2 shown in the drawing, the earpiece casing could be flat. Then the electro-acoustic transformer could be fitted in the region of the casing opening and project partly therefrom, so that the transformer in the earpiece, when fastened to the helmet, projects at least partly through the hole in the helmet.

Claims

1. An earpiece for fastening to a protective helmet characterised in that it comprises an electro-acoustic transformer accommodated in a casing which is open at one end and is watertightly closed at its other sides, the casing opening being surrounded by a hollow cylindrical casing wall part having an annular end face in which there is a sealing ring; and in that the casing is adapted to be fastened from the outisde of a helmet, in a hole provided in an ear region of the helmet, so that the annular face abuts by the sealing ring against the outside of the part of the helmet wall which surrounds the hole.

2. An earpiece as claimed in claim 1 characterised in that the hollow cylindrical part of the casing wall which surrounds the casing opening has an internal thread and serves to receive a fixing ring is provided at one end with a corresponding external thread and at the other end with a radially outwardly projecting flange, so that fixing of the earpiece can be effected by pushing the externally threaded end of the fixing ring, from the inside of the helmet, through the hole and screwing it into the said hollow cylindrical part of the casing wall, thereby to clamp the part of the helmet wall which surrounds the hole between the flange of the fixing ring flange and the sealing ring which is located in the annular free end of the casing wall.

3. An earpiece as claimed in claim 1 characterised in that the hollow cylindrical part of the casing wall which surrounds the casing opening has an externally threaded extension, there being an annular shoulder at the junction between the said part and the extension so that fixing of the earpiece can be erected by pushing the extension inwards from outside the helmet through the hole and engaged by a nut inside the helmet, thereby to clamp the part of the helmet wall which surrounds the hole between the nut and the sealing ring which is located in the annular shoulder.

4. An earpiece as claimed in claim 1 characterised in that the hollow cylindrical part of the casing wall which surrounds the casing opening has an extension with a peripheral rim at its free end, consists of resilient material, and has slits which extend axially through the peripheral rim, and in that the annular end face is spaced from the peripheral rim by a distance which equals the aggregate of the thickness of the part of the sealing ring which projects from the annular end face and thickness of the helmet wall so that when the extension with its rim is inserted into the hole from the outside of the helmet the rim is elastically compressed and thereafter engages against the inside of the part of the helmet wall which surrounds the hole which is then gripped between the peripheral rim and the sealing ring.

5. An earpiece as claimed in claim 1 characterised by the provision, on the hollow cylindrical part of the casing wall which surrounds the casing opening, of elastic tongues whose free ends projects radially outwards as hooks so that the tongues upon being passed inwards through the hole from the outside of the helmet yield elastically and when passed through, engage by their hook-shaped ends against the inside of the part of the helmet wall which surrounds the hole to hook therewith, so that the helmet wall is then gripped between the hook-shaped ends of the tongues and the sealing ring.

6. An earpiece as claimed in claim 1 characterised in that the hollow cylindrical part of the casing wall which surrounds the casing opening has, at its free end, a peripheral groove to take an elastic ring, e.g. a Seeger ring, so that upon part of the casing wall being inserted the hole from outside the helmet, the elastic ring fits itself into the peripheral grcove on the inside of the helmet so that the part of the helmet wall which surrounds the hole is clamped between the elastic ring and the sealing ring.

7. An earpiece as claimed in any preceding claim characterised in that the casing is in the form of a pot whose free edge which surrounds the opening of the pot forms the hollow cylindrical part of the casing wall.

8. An earpiece as claimed in any preceding claim characterised in that the electro-acoustic transformer is connected with a separable connector which is watertight projects from the casing wall or end.

9. An earpiece as claimed in any of claims 1 to 7 characterised in that the electro-acoustic transformer is connected by a wire fastened watertightly to the casing wall or end.

10. An earpiece as claimed in any preceding claim characterised in that at least one control element is fitted in a watertight manner in the casing wall or in the floor thereof.

1 An earpiece as claimed in claim 10 wherein the control element is a tactile switch or a volume control for the electro-acoustic transformer or for a radio to which the earpiece is to be connected.

12. An earpiece as claimed in any preceding claim characterised in that the electro-acoustic transformer is a dynamic receiving capsule which is situated resiliently in the casing.

1 3. An earpiece as claimed in any preceding claim characterised in that there is fitted at the inner end of the casing opening, at least one protective membrane or sheet provided with holes through which sound can travel, being in the form of a mesh or a perforate sheet.

14. An earpiece as claimed in any preceding claim characterised in that the casing includes a resonance space acoustical!y coupled to the rear side of the membrane of the transformer.

1 5. An earpiece as claimed in any preceding claim characterised in that at the open end of the casing there is a resonance space acoustically coupled to the front side of the membrane of the transformer, which forms an acoustically defined hearing canal.

16. An earpiece as claimed in any preceding claim characterised in that the casing is of elastic material.

17. An earpiece as claimed in claim 1 characterised in that the hollow cylindrical part of the casing wall is stuck or screwed to the part of the helmet wall which surrounds the hole, or is fixed or snapped into it.

18. An earpiece as claimed in claim 1 characterised in that at least one part of the electro-acoustic transformer is fitted in the region of the casing opening so that the transformer in a receiver which is fastened to the helmet stretches at'least partly into the region of the hole provided in the helmet.

19. An earpiece for fastening to a protective helmet substantially as hereinbefore described with reference to and as illustrated in Figs. 1 and 2, or in Fig. 3 or in Fig. 4 of the accompanying drawings.