The present invention relates to cushions and in particular to the types of cushions used on apparatus which is intended to be worn on the head of a user, for example ear defenders, headphones, masks, goggles and close fitting helmets.
In prior art headphones and ear defenders, each earpiece normally includes a rigid ear cup (which fits over an ear of the wearer) together with some cushioning material fixed around the perimeter of the ear cup to make the ear cup more comfortable to wear, to provide some level of acoustic seal, and provide some level of attenuation (in low frequency environments). One problem is that a relatively soft cushioning material, when combined with an ear cup provides a relatively high degree of comfort but poor acoustic sealing and attenuation. Likewise, relatively hard cushioning material, when combined with an ear cup provides good acoustic sealing and attenuation but low comfort.
‘Acoustic Seal’ may be defined as zero leak paths between the cushion and body of the user.
‘Acoustic Attenuation’ may be defined as the mean difference in decibels between the threshold of hearing with and without the hearing protector in place. (BS EN 352-1:1993 Hearing Protector, Part 1)
U.S. Pat. No. 4,856,118 describes a headphone cushion which includes two concentric rings on the perimeter of each ear cup. These concentric rings are made of a non-liquid gelatine-like silicone and are mounted on a layer of slow recovery foam enclosed in a thin stretchable layer of polyurethane skin. The aim is stated to be to provide a good acoustic seal between a headphone cover and the head and ear of a wearer while being relatively lightweight and comfortable to wear. However, as explained above, with the prior art designs these two parameters are to some extent mutually exclusive and so the present invention aims to provide a design which improves on this.
Accordingly, in a first aspect, the present invention provides apparatus for covering some or all of a wearer's body, including interface means which in use are adjacent the wearer's body, the interface means including a first region of material having a first compliance and a second region of material having a second compliance, the first compliance being greater than the second compliance, wherein both of the regions are adjacent respective parts of the wearer's body.
The use of two different regions of material having respectively different compliances enables the interface means to be designed so as to provide a better seal between the remainder of the apparatus and the relevant part of the wearer's body which the apparatus covers. In some practical examples, such as goggles, it is merely the “tightness” of the seal which is important and the present invention enables a suitably tight seal to be achieved at an increased level of comfort in comparison to the prior art. Additionally or alternatively, in examples where the acoustic attenuation of the cushion is important (for example headsets, ear defenders or headphones), for a given level of comfort the present invention enables an enhanced acoustic attenuation in comparison to the prior art
Preferably the part of the wearer's body on which the apparatus is worn is the head and in some examples may be the face region (e.g. a face mask), the eye region (e.g. goggles), the ear region (e.g. headsets, ear defenders, headphones) or the cranial region (e.g. helmets).
Usually the apparatus will have an area, often a perimeter, designed or shaped to fit the relevant part of the wearer's body. Generally, the interface means will be attached to this area or perimeter and preferably to the whole area or perimeter, so that, in some examples, the interface means is the only part of the apparatus to be adjacent or contact the relevant part of the wearer's body. Preferably the interface means covers the whole of the area or perimeter and more preferably the second region of the interface means does not cover the whole area or perimeter but only a part of it. The first region of the interface means may cover the whole area or perimeter or alternatively it may cover only a part of it also.
In some practical examples, the first region may cover substantially all of the area of perimeter and have sections where it is effectively replaced by the second region of material. The arrangement may be such that the first region wholly or partly encloses the second region for example, on the side of the interface means which is closest to the relevant part of the wearer's body in use, the second region may be as close to the wearer's body as the first region or may be covered by the first region.
Either or both of the regions may be covered with a suitable protective material e.g. may be skinned or integrally skinned. Alternatively, either or both of the regions may be uncovered.
In practice, the apparatus may be designed so that in use the first region is adjacent sensitive areas of the wearer's body (e.g. where arteries, veins and/or nerves are located near the surface) and the second region located adjacent less sensitive areas (e.g. where bone is close to the surface).
In a further aspect, the present invention provides a method of constructing apparatus for covering all or a part of a wearer's body, the apparatus including interface means which in use are adjacent the wearer's body, the method including providing a first region of material of a first compliance and the second region of material of a second compliance, the first compliance being greater than the second compliance wherein both regions are adjacent respective parts of the wearer's body in use.
Embodiments of the present invention will now be described with reference to the accompanying drawings in which:
In
The cushioning member 4 includes two regions of material, the first region 8 has a first compliance A and the second region 10 has a second compliance B, where compliance B is less than compliance A. In fact, in this example the region 10 is split into two parts 12 and 14. In use, part 12 is intended to lie adjacent the skull bone behind the upper area of a wearer's ear and part 14 is intended to lie adjacent the temporal process.
The aim of this embodiment of the present invention is to provide material of relatively high comfort (i.e. relatively high compliance or low density) adjacent or against those areas of the wearer's ear region (pinna) which are sensitive (such as the temple area and the area at the base of the ear), so the apparatus is comfortable to wear. In addition, areas of relatively low compliance (i.e. high stiffness or density) are provided so as to lie adjacent or press against relatively less sensitive areas of the wearer's ear region. This enables the cushion as a whole to provide a relatively more comfortable seal and, in the case of a hearing protector, better acoustic attenuation where it is useful.
Where the level of acoustic attenuation is significant, the attenuation is a function of the stiffness K of any given material (e.g. ear cushion material). Stiffness K is the inverse of the compliance C of a material i.e. C=1/K. In the above example, the stiffness of the second region 10 of material dominates the system under load (i.e. in use) and therefore the attenuation provided by the apparatus is largely determined by the stiffer region 10, whilst still providing levels of comfort according to region 8.
In
However, as shown in
Polyurethane Foam (possibly with a skin may be used as suitable cushion material.
In
In this example, the first region of material 8 encloses the region of material 10 on all sides other than that which contacts the substrate 32. This is clear from the cross-sectional view shown in
In this and other embodiments (including the embodiment of
The above embodiments are intended to be an example of the present invention and variants and modifications of those embodiments, such as would be readily apparent to the skilled person, are envisaged and may be made without departing from the scope of the present invention. For example, the above embodiments have been described with reference only to two regions of material of respectively different compliances, but it is possible to include further regions of material having other compliance levels as appropriate for the particular article to which the cushion is applied.
Number | Date | Country | Kind |
---|---|---|---|
02 23894.7 | Oct 2002 | GB | national |