SEAL ASSEMBLY FOR USE IN A FACE MASK OR SWIM GOGGLES

Abstract: Swim goggles 10 have a pair of eye pieces 11,12, each eye piece having a lens 17 with an essentially rigid peripheral frame 18. Each eye piece has a seal assembly 23 which includes a seal holder 28 and a seal gasket 30. The seal holder 28 is secured to the frame 18 and has a pair of spaced flanges 41,42 extending in a direction generally away from the respective lens 17. Space between the flanges of the seal holder provides a groove 58 extending around the eye piece and the seal holder is resiliently deformable but relatively stiff. The seal gasket 30 is fitted within the groove between the flanges 41,42 and has an outer face 60 standing clear of the flanges to contact the wearer's face. The seal gasket 30 is resiliently deformable and softer than the seal holder 28 to provide a secure but comfortable seal with the wearer's face. Selection of the relative resiliences of the seal holder 28 and seal gasket 30 permits accommodation to a wide variety of faces and extends use of the goggles. A face mask with a single lens provided with a seal assembly as above is an alternative.

Description: The present invention relates to a seal assembly for use in sealing a lens to a wearer's face to provide eye protection and is especially suitable for use in a face mask or swim goggles. Many varieties of swim goggles have been available to accommodate the variations between wearer's faces. Swim goggles should provide a good seal against water penetration, as well as being comfortable for extended wear. It is known to provide a resilient seal or gasket made from an expanded elastomer or rubber compound which extends from a rigid frame to contact the face. The seal is adapted to engage recesses and bulges of the face, so as to provide a water-tight but comfortable fit. If the seal is excessively soft, it usually deteriorates quickly in the chlorinated water commonly used in swimming pools. Soft seal gaskets can deform under a relatively low force which seems to be necessary for comfort when fitted directly against the face, and can deform in a direction normal to the face to accommodate curvature of the face. However, excessively soft seals which project too far from a rigid base can deform excessively in a direction parallel to the face i.e., fold over, which can reduce effectiveness of the seal and permit leakage. Harder types of seals require a greater force to deform them to fit the face, and correspondingly can become uncomfortable after a short time. The more rigid seals tend to resist deterioration better than the softer seals, and do not deform excessively but, in general, cannot accommodate such a wide variety of curvatures of the face. In general, goggles for long distance training swimming are softer for greater comfort than goggles used for racing. Racing goggles must be sufficiently stiff to resist the shock forces of a racing dive, and thus comfort is often sacrificed because such goggles are usually worn for shorter periods. US-A-1850538 and US-A-1741427 disclose goggles having seals of the resilient cushion type, but these goggles do not appear to be suitable for swimming - the seals of these goggles can be easily replaced when worn, but the structure for attaching the seals to the frame of the goggles is such that the goggle seals can accidentally be dislodged from the goggles, which could cause leakage, become uncomfortable and even distort vision through the goggles. It is also known from US-A-2393533, acknowledged in the preamble of the following independent claim, for a seal assembly for use in sealing a lens to a wearer's face to include a rigid peripheral frame for the lens; a seal holder secured to the frame and having a pair of spaced flanges extending in a direction generally away from the lens, space between the flanges providing a groove extending around the lens; and a seal gasket fitted within the groove and having an outer face standing clear of the flanges for contacting the wearer's face, the seal gasket being made of a material different from the seal holder and being resiliently deformable and softer than the seal holder. However, a seal assembly in accordance with the present invention is characterised in that the peripheral frame is made of a first material, the seal holder is made of a second material and the seal gasket is made of a third material, the first material being stiffer than the second material, and the second material being stiffer than the third material, so as to provide a secure but comfortable seal with the wearer's face. Preferably, in an unrestrained condition, the groove has a re-entrant cross-section with an inner width between the flanges greater than an outer width between the flanges, the flanges being curved inwardly towards each other so as to grip the seal gasket therebetween, at a location on the seal gasket intermediate of inner and outer faces of the seal gasket. The seal holder may have an inner portion for co-operating with the frame, an outer portion having the two flanges, and an intermediate portion disposed between the inner and outer portions thereof, with the flanges having flange roots adjacent the intermediate portion and flange tips at outer extremities of the flanges, the width between the flange tips being less than the width between the flange roots, in the unrestrained condition, so as to provide the groove with the re-entrant cross-section to grip the seal gasket. The seal gasket may have an inner portion having a width slightly greater than the width of the groove between the flanges in the unrestrained condition, and an outer portion extending from the flanges a distance sufficient to permit limited lateral deformation of the outer portion to accommodate contours of the wearer's face. In a preferred embodiment, the seal holder has a Shore A Durometer hardness within a range of 36 to 95, and the seal gasket has a Shore hardness within a range of Shore 00 Durometer 10 - 50 to Shore A 7 - 20. Although it is possible for the seal holder to be secured to engaging means on the frame, in which the engaging means is an L-sectioned lug extending around the frame, and the seal holder has an L-sectioned recess complementary to and receiving the L-sectioned lug, it is alternatively possible for the seal holder to be integrally moulded with the frame. The seal assembly of the present invention may be utilised by forming part of swim goggles having a pair of lenses in respective peripheral frames whose opposite portions are interconnected by head and nose straps or by forming part of a face mask having a single lens in a single peripheral frame whose opposite portions are interconnected by just a head strap. None of the prior art seal assemblies combines the comfort of resilient, soft, low density elastomeric cushion foam with the stiffness and accuracy of location arising from use of stiffer, higher density elastomeric materials. A preferred embodiment of the present invention will now be described in greater detail with reference to the accompanying drawings in which:- Figure 1 is a simplified, fragmented front view of a pair of swim goggles fitted with a seal assembly according to the invention; Figure 2 is a fragmented top plan view of one eye piece portion of the goggles of Figure 1; Figure 3 is a simplified fragmented sectional view on line 3-3 of Figure 1, showing a seal holder and seal gasket; Figure 4 is a simplified fragmented sectional view, generally as would be seen on line 3-3 of Figure 1, with the seal gasket removed from the seal holder so that the seal holder is shown in an unrestrained condition; and Figure 5 is a simplified cross-sectional view through the seal gasket shown in an unrestrained condition. As shown in Figures 1 and 2, swim goggles 10 have first and second eye pieces 11 and 12, a nose strap 13 and a head strap 14. The eye piece 11 has a transparent lens 17 and an essentially rigid peripheral frame 18. Preferably, for manufacturing simplicity and for improved peripheral vision, the eye piece 11 and frame 18 are integral and thus the frame is also transparent. The frame 18 has inner and outer portions 21 and 22 which provide releasable anchor means 25 and 26 respectively for the nose strap 13 and head strap 14. The eye piece 12 has structure generally similar to the eye piece 11, is a mirror image thereof and is not described in detail. The nose strap 13 interconnects the adjacent inner portions 21 of the frames to bridge the nose of a wearer, and the head strap 14 interconnects the outer portions 22 of the frames to pass around the back of the head as is common practice. A seal assembly 23 according to the invention includes a seal holder 28 and a seal gasket 30 provided on a side of each frame 18 remote from its lens 17 so as to contact the wearer's face. The frame 18 has an L-sectioned lug 32 extending around the frame as best seen in Figure 3. The L-sectioned lug faces inwardly towards the lens 17 around the frame 18. The seal holder 28 has an inner portion 35 which has an L-sectioned recess 37 which is complementary to the L-sectioned lug 32 and is adapted to receive the L-sectioned lug. Thus, the L-sectioned lug of the frame serves as an engaging means to cooperate with the seal holder but, if desired, the frame and seal holder can be integrally moulded together. The lug 32 and recess 37 can have other complementing shapes so that the inner portion of the seal holder 28 is adapted to cooperate with the engaging means of the frame 18. The seal holder 28 has an outer portion having inner and outer flanges 41 and 42, and an intermediate portion 45 disposed between the inner and outer portions of the flange. The flanges 41 and 42 extend in a direction generally away from the lens 17 and have respective flange roots 47 and 48 adjacent the intermediate portion, and flange tips 51 and 52 at outer extremities of the flanges. As best seen in Figure 4, in the unrestrained condition, an outer width 54 between the flange tips is less than an inner width 56 between the flange roots. It can be seen that space between the flanges provides a groove 58 extending around the eye piece, the groove having a depth 57. Thus, the groove 58 has a re-entrant cross-section with the inner width 56 between the flanges being greater than the outer width 54 between the flanges. The seal gasket 30 has an inner portion 64 fitted in the groove 58 between the flanges and has an outer portion 59 having a relatively flat outer face 60 standing clear of the flanges by a distance 62. The distance 62 is sufficient to permit only limited lateral deformation of the outer portion 59 of the seal gasket i.e., parallel to the face 60 to accommodate contours of the wearer's face. Slight lateral deformation of the outer portion 59 of the seal gasket 30 is shown in broken outline at 59.1. When the seal gasket is laterally deformed, an effective water-tight seal with the face is not lost because the outer face 60 remains relatively flat and in contact with the wearer's face 63, shown in broken outline. The seal gasket is resiliently deformable and fabricated from an expanded or foamed elastomer as will be described. It is softer than the seal holder so as to provide a secure but comfortable seal with the wearer's face. It can be seen that relative stiffness of the three components frame 18, seal holder 28 and seal gasket 30 increases in a direction away from the face, i.e., the softest component is closest to the face. The seal gasket 30, shown in its unrestrained condition in Figure 5, has a width 66 for the inner portion 64 which is greater than the inner width 56 of the groove 58 in the unrestrained condition of the seal holder 28 as shown in Figure 4. The seal gasket can be die cut from a flat sheet and is generally rectangular in cross-section when unrestrained. An inner face 65 of the gasket can be provided with a "low tack" contact adhesive which can releasably bond to the portion 45 of the seal holder so as to augment retention of the seal gasket in the seal holder. The seal gasket can be removed from the seal holder with a negligible deposit of the "low tack" adhesive remaining on the seal holder. Preferably, the seal gasket 30 has a depth 68, see Figure 5, which is approximately twice the depth 57 of the groove 58. In this way, approximately half the depth of the seal gasket is gripped and retained by the flanges, and the remaining half stands proud of the flanges and can accommodate contours of the face, while simultaneously providing a soft comfortable seal. Preferably, the flanges 41 and 42 are curved inwardly towards each other in the unrestrained condition as seen in Figure 4, so as to grip the seal gasket therebetween at a location on the seal gasket intermediate of the inner and outer faces of the seal gasket. The effectiveness and comfort of the seal assembly of the present invention is dependent on the correct selection of materials for the three components of the seal assembly. The seal holder 28 is moulded from thermoplastic rubber compounds which are resilient and yet relatively stiff. Suitable materials are manufactured by Shell Chemical Inc., under the trade mark KRATON D and KRATON G, and particular specifications of suitable compounds are as follows:- The typical properties outlined above for the KRATON G-2705, G-7705, G-7720, G-7820 and G-7827 are summarised for typical properties at 74 degrees Fahrenheit (23 degrees Centigrade). Such compounds have excellent ozone resistance which is essential for use in chlorinated water as is well known in the trade. The seal gasket 30 can be manufactured by cutting from flat sheets of high density cellular polyurethane, sold under the trade mark PORON, as manufactured by the Rogers Corporation of East Woodstock, Connecticut. Other suitable compounds include RUBBERTEX, registered trade mark of Rubbertex Corporation of Virginia, U.S.A., and ENSOLITE, a registered trade mark of Uniroyal Plastics Co., Inc., of Indiana U.S.A. A "low tack" contact adhesive can be applied to one side of the sheet to improve retention of the seal gasket within the seal holder. Typical properties of suitable seal gasket material are summarised below:- Tensile strength and elongation are not very important properties for the seal gasket as the seal gasket is supported by the seal holder. The permits use of a relatively soft gasket material when compared with prior art gaskets. Materials are selected also for their ageing properties, and ozone and chlorination resistance as well as tendency to resist adhering to the face. It will be appreciated that the swim goggles 10 are used in a normal manner, by adjusting the spacing between the eye pieces 11 and 12 by careful adjustment of the nose strap 13. Similarly, the force of the swim goggles 10 against the face is adjusted by the head strap 14. For racing use, goggles are usually worn for only a short time, and the seal must withstand the forces of a racing dive. Thus a relatively stiff seal gasket, and correspondingly stiffer seal holder are preferred. For training purposes, where forces are lower, and the goggles are worn usually for a longer time, comfort is preferred and correspondingly softer materials are selected for the seal holder and seal gasket. Alternatively the same seal holder can be used for both training and racing, and only the seal gasket need be changed for the different activities. In general, the seal gasket will deteriorate far faster than the seal holder, and it is relatively easy to replace a worn or deteriorated seal gasket with a new one. A face mask with a single lens can be fitted with a seal assembly according to the invention and obtain the benefits of comfort, accuracy of sealing fit and easy replacement of material substitution of the seal gasket, this type of mask being particularly appropriate for Scuba diving.

Claims: A seal assembly, for use in sealing a lens (17) to a wearer's face (63), comprising: a rigid peripheral frame (18) for the lens; a seal holder (28) secured to the frame and having a pair of spaced flanges (41,42) extending in a direction generally away from the lens, space between the flanges providing a groove (58) extending around the lens; and a seal gasket (30) fitted within the groove and having an outer face (60) standing clear of the flanges for contacting the wearer's face, the seal gasket (30) being made of a material different from the seal holder (28) and being resiliently deformable and softer than the seal holder (28); characterised in that the peripheral frame (18) is made of a first material, the seal holder (28) is made of a second material and the seal gasket (30) is made of a third material, the first material being stiffer than the second material, and the second material being stiffer than the third material, so as to provide a secure but comfortable seal with the wearer's face. A seal assembly according to claim 1, characterised in that, in an unrestrained condition, the groove (58) has a re-entrant cross-section with an inner width (56) between the flanges greater than an outer width (54) between the flanges. A seal assembly according to claim 2, characterised in that, in the unrestrained condition, the flanges (41,42) are curved inwardly towards each other so as to grip the seal gasket (30) therebetween, at a location on the seal gasket intermediate of inner (65) and outer (60) faces of the seal gasket. A seal assembly according to claim 2 or claim 3, characterised in that the seal holder (28) has an inner portion (35) for co-operating with the frame (18), an outer portion having the two flanges (41,42), and an intermediate portion (45) disposed between the inner and outer portions thereof, with the flanges having flange roots (47,48) adjacent the intermediate portion (45) and flange tips (51,52) at outer extremities of the flanges, the width (54) between the flange tips being less than the width (56) between the flange roots, in the unrestrained condition, so as to provide the groove with the re-entrant cross-section to grip the seal gasket (30). A seal assembly according to any preceding claim, characterised in that the seal gasket (30) has an inner portion (64) having a width slightly greater than the width of the groove (58) between the flanges in the unrestrained condition, and an outer portion (59) extending from the flanges a distance sufficient to permit limited lateral deformation of the outer portion to accommodate contours of the wearer's face. A seal assembly according to any preceding claim, characterised in that the seal holder (28) has a Shore A Durometer hardness within a range of 35 to 95, and the seal gasket (30) has a Shore hardness within a range of Shore 00 Durometer 10 - 50 to Shore A 7 - 20. A seal assembly according to any one of claims 1 to 6, characterised in that the seal holder (28) is secured to engaging means (32) on the frame (18). A seal assembly according to claim 7, characterised in that the engaging means is an L-sectioned lug (32) extending around the frame (18), and the seal holder (28) has an L-sectioned recess (37) complementary to and receiving the L-sectioned lug (32). A seal assembly according to any one of claims 1 to 6, characterised in that the seal holder (28) is integrally moulded with the frame (18). A seal assembly according to any preceding claim characterised by forming part of swim goggles having a pair of lenses in respective peripheral frames whose opposite portions are interconnected by head and nose straps or by forming part of a face mask having a single lens in a single peripheral frame whose opposite portions are interconnected by just a head strap.

Inventors: HASLBECK, JOSEPH
Applicants: SHARP PLASTICS MFG. LTD.
Application year: 1987
Main classification: A63B33
IPC codes: A61F9, A63B33, G02C3