BACKGROUND Conventional swimming goggles have a transparent lens portion-usually a rigid material such as polycarbonate- facing forwardly and mounted in a face piece which includes a rearwardly-directed peripheral seal portion which is adapted to seal back against the wearer's face to enclose the space behind the lens portion. Usually there are two lens portions, one for each eye, each with its own peripheral seal portion. Or, a single seal portion may be provided to enclose a single space for both eyes, traversing the nose. There may be a single lens portion spanning both eyes. In some conventional constructions there is a discrete frame mounting the lens portion (s), the rear seal portion being a further discrete element attached behind or around the frame. In other constructions the seal portion and frame are formed in one piece.

In racing goggles each eye piece may be simply a rigid one-piece polycarbonate cup, small enough to recede into the eye socket when worn. Generally speaking however the rear seal portion is provided by a resiliently flexible skirt of elastomeric material, e. g. chloroprene, neoprene or, silicone rubber, having a rear face-contacting edge.

The edge itself may have a curl to promote free flexion and reduce local pressure on the face. This face-contacting edge of the seal portion is shaped to correspond with a typical face profile. When worn, the goggles are pulled back onto the face by a strap which creates a seal by pressing the flexible edge of the seal portion against the skin. This involves resilient deformation of the flexible seal portion and/or of the surface of the face, to relative extents which depend on the local pressure and the shape, size and bone structure of the face. It is well known that when goggles are tight enough to form a good seal they can be uncomfortable, and may cause unsightly or uncomfortable indentations on the face around the eyes.

THE INVENTION One aspect of what we propose herein is to form the seal portion of the goggles using a cushion of deformable material capable of a substantially non-resilient and/or inelastic deformation. Such a material, when urged against the face surface, can be brought to precise conformity to the face surface without necessarily localising pressure on the skin at those regions where the greatest deformation has taken place.

One particularly preferred form of our proposals uses in the seal portion a gel or polymeric material which is convertible in situ between a relatively viscous, more flowable state and a stiff and/or more resilient state e. g. gelled state. Such materials-which for the present purposes may be encapsulated in a flexible membrane-are

known as such and are popularly called"smart"or memory gels. The transition is generally reversible. In particular, gels of this kind are available, and can be made using current knowledge, which are convertible between the relatively flowable and relatively resilient states by means of any one or more of various stimuli including magnetic changes, irradiation and (in particular) temperature changes around a transition temperature, which may be approximate to or at least not higher than a body surface temperature. Such thermoreversible gels are described for example (in another use) in WO-A-00/32715, and relevant types of gel composition described in that document may be used here. Reference may also be made to Tanaka, T. (1978) Phys Rev Lett 40,820-823. A feature of one class of gels of a relevant type is a substantial reduction in volume at the phase transition, and this phenomenon may also be exploited herein to relieve pressure at close contact areas.

In an alternative preferred embodiment a phase transition in the material may be pressure-or flow- actuated as opposed to (or in addition to) being temperature actuated. Work done on the material during its deformation, as the goggles are fitted to the face, may then be effective to cause it to gel, set or remain in the conformed shape with no restoring force, or with a restoring force substantially less than proportional to the displacement in terms of the Young's modulus at the free (non-deformable) conformation, e. g. less than half or less

than a quarter of what the restoring force would be at that modulus if it were constant.

A more general aspect of the present proposals is to form a contact region of the cushion-form seal portion, preferably localised at a part where it contacts the face, using a deformable material which is more conforming or substantially less resilient than the material in a front part of the rearwardly-extending portion, the front material being more resilient or indeed stiff. Such low- resilience or non-resilient (generally, having a lower Young's modulus) deformable contact portions can spread or broaden most at the regions of greatest deformation, and therefore, by virtue of the larger area per unit perimeter length applied to the face, avoid the higher pressure which would otherwise be associated with the greater force applied at these regions, especially because the larger deformations need not be associated with the higher force.

They can distribute pressure around the goggle periphery.

Preferably the cushion is hollow. An alternative definition of a class of materials usable in or for a cushion body is that their Young's modulus decreases with deformation from a rest condition, e. g. by at least 50% over the operational range of deformation. Preferably they are nevertheless resilient with respect to the rest condition.

Various polymeric or gel materials may be used in the above aspects, for example viscoelastic polymers, silicone gels, hydrogels in general and urethane polymers. Where

necessary for structural integrity and/or hygiene such readily-deformable polymer materials may be encapsulated in a flexible e. g. polymeric membrane. This membrane may form an enclosed pocket running around the edge of the goggles seal, preventing escape of compressible material in the pocket and/or where necessary providing protection against chemical damage to the cushion polymer e. g. against attack by chlorine.

A further possibility for providing greater deformability/lower resilience of the seal portion adjacently the face is the incorporation of one or more gas pockets, or the use of foamed material. A gas pocket or foamed region may extend around the rim of the seal, and may if wished be formed integrally with a non-foamed or non-pocketed stiffer or more resilient region forwardly of the rim. Foamed materials e. g. foamed polyurethanes are available which hold a shape after deformation under pressure.

THE DRAWINGS Fig. 1 is a perspective view of goggles.

Fig. 2 and 3 are sectional views through goggles peripheries.

The attached drawing Fig. 1 illustrates a conventional disposition of components in swimming goggles, including two eye pieces 1 with lenses 2, stiff frames 3 and flexible seal portions 4. The skilled person will readily deduce

various ways of applying the above proposals to achieve the desirable effects mentioned herein. Fig. 2 shows how a said portion 4 is provided as a solid continuous cushion (not however excluding the possible use of foam material) that deforms by squashing, as opposed to the conventional silicone seal which is a bending lip. Fig. 3 shows that a cushion material body 41 having the desired deformation properties but poor surface properties, e. g. vulnerability to chlorine attach or staining, may be encapsulated in a thin impermeable membrane or cover layer 42.