In the above-mentioned equipment, by"strap"is meant a ribbon or strip of elastic material (rubber, silicone rubber, elastomeric material, such as thermoplastic rubber, plasticated PVC, polyurethane, and the like) shaped so as to wrap round the part of the user's body at the point where the equipment is worn (the head in the case of goggles and masks, the heel in the case of flippers, and the calf of the leg in the case of knives). The strap normally has one face in a position corresponding to its left-hand end and its right-hand end, two relatively long areas provided with transverse ribs or serrations, i. e., a series of notches which are in relief, frequently having a saw- toothed shape, and the central portion usually assumes a wider or doubled shape.

State of the prior art The buckles traditionally used with the aforesaid straps include, for each serrated end portion of the strap, the following: a body having a take-up member, around which the said end portion of the strap winds; a catch, which is normally kept in a position of engagement with the serrations of said end portion of the strap against the take-up member, so as to prevent displacement of said end portion of the strap in at least one direction; and a manoeuvring part which can

be operated manually to disengage the catch from said end portion of the strap against the action of elastic thrust means.

With an arrangement of this sort, it is evident that the function of the serrations of the strap is that of engaging with the catch, so enabling fastening of the strap at the chosen useful length (the so-called "tensioned length").

In order to obtain variations of this useful length, it is necessary to manoeuvre the buckle appropriately so as to engage the catch in other serrations of the strap which are further away or closer to the ends of the strap. Normally, in order to shorten the length of the strap, the user just needs to exert a manual pull on the serrated end, normally backwards, so causing the serrations to slide underneath the catch. Instead, to lengthen the strap he must operate the manoeuvring member manually so as to move the catch positively away from the serrations of the strap. In practice, then, the catch and the serrations operate like a pawl-and-ratchet mechanism.

There is an extremely wide range of adjustment buckles of the above type, according to the sizes, according to the means for manoeuvring the catch, and according to the type of manoeuvre that the user must make.

In the specific sector of equipment for water sports, the most technologically advanced and most widely used buckles are essentially of two types, which are schematically illustrated in Figures 1 and 2 of the attached drawings. These figures are schematic, partially cross-sectional, views of two known buckles having a sprung ratchet mechanism that can be disengaged in one case (Figure 1) by pressing a button, and in the other case (Figure 2) by raising a

manoeuvring finger or tab.

The buckle of the former type, represented in Figure 1 and substantially corresponding to the one described in the document US-A-4 607 398, includes a support 1, which is integral with the structure of a mask or of a pair of goggles for swimming and which bears a pivot 2 for an oscillating push-button 3, and a roller 4. The oscillating push-button forms, at one end, a catch 5 facing the roller 4, and at the other end, a manoeuvring part 6. A thrust spring 7, set between the body 1 and the manoeuvring part 6, tends to keep the catch 5 in a position of engagement with serrations 8 of an end portion 9 of an elastic strap 10. With this arrangement, in order to shorten the tensioned length of the strap 10 (i. e., in order to tension the strap), it is sufficient to pull the end portion 9 of the strap 10 backwards in the direction of the arrow A. The catch 5 is automatically raised and jumps freely from one notch 8 to the next notch 8. In order to increase the length of the strap 10 (i. e., in order to relax the tension), it is necessary, instead, for the user to press the manoeuvring part 6 of the oscillating button 3 with his finger against the action of the spring 7. In this way, the catch 5 lifts up and leaves the strap 10 free to slide.

The above solution entails various problems. In the first place, for evident reasons of encumbrance, the oscillating button 3 is necessarily short (normally not longer than 20-22 mm). Consequently, in order to lengthen the strap 10 it is'necessary to apply, on the manoeuvring part 6, a considerable force, which is inconvenient and somewhat troublesome for the user.

Furthermore, frequently the user's finger inadvertently presses exactly in the area of the pivot 2. instead of on the manoeuvring part 6, and hence without any result

as regards strap adjustment.

The buckle of the second known type, represented in Figure 2 and substantially corresponding to the one described in the document EP-A-824029, is also provided with a support 1, which is integral with the structure of the equipment and bears the roller 4 (which can be replaced by a simple non-rotating cross member). The catch 5, which co-operates with the serrations 8 of the end portion 9 of the strap 10, is, in this case, carried by an elastic element 13, to which there may possibly be associated a return spring 14 and which is formed with a projecting tab or finger 11, which constitutes a manoeuvring finger. Also in this case, in order to shorten the strap 10, it is sufficient to pull the serrated end portion 9 backwards in the direction of the arrow A so as to cause the catch 5 to lift automatically and to jump freely on the serrations 8.

To slacken the strap, the user must insert a finger underneath the manoeuvring finger 11 and pull the latter outwards so as to free the serrations 8. For the adjustment manoeuvre to be successful, this known buckle must be installed on a rigid part of the structure of the equipment; otherwise, the user's finger would be unable to free the ratchet mechanism.

Also this second known buckle presents a number of drawbacks. In the first place, to provide sufficient space for the user's finger to get underneath the manoeuvring finger 11, the height, i. e., the thickness, of the buckle assembly becomes considerable, involving problems of aesthetics and hydrodynamics. Furthermore, if the manoeuvring finger 11 is raised by the user too much, the consequence may be that it breaks. To prevent this risk, in order to tension the strap 10 its end portion 9 must be pulled backwards in a direction roughly parallel to the body 1 of the buckle, and this,

in addition to requiring an action that is far from natural on the part of the user, compresses the equipment to an exaggerated extent against the part of the user's body to which it is applied (for example, the goggles against the face), with the risk, moreover, of pulling or tearing hairs, in that the strap is made to slide with its serrated part against the surface of the user's body.

Both of the known buckles described above with reference to Figures 1 and 2 further involve for the user inconvenient and troublesome manoeuvres in so far as they entail, in one case, a compressive force and, in the other, a tensile force applied by the user's finger against his body. The anatomical fulcrum of this manoeuvre is the user's shoulder, which is evidently at some distance from the point of application of the force, and for this reason in order to overcome the elastic reaction acting on the catch, it is necessary to exert a considerable effort and in any case an unbalancing force since it involves the user's entire arm.

Summary of the invention The object of the present invention is to overcome the above-mentioned drawbacks.

According to the invention, the above purpose is primarily achieved thanks to the characteristics specified in the attached Claim 1.

Further subordinate characteristics of the buckle are specified in the dependent claims.

In addition, a further subject of the invention is a piece of equipment for practising water activities and the like, provided with at least one, and more conveniently, two buckles according to the invention.

As will emerge from the ensuing detailed description, the buckle according to the invention is

conveniently structured on two planes, one on top of the other, below which two wedges are inserted, for fast adjustment of straps for swimming goggles, masks, flippers and the like. The buckle is conceived so as to be of extremely small thickness, and without points that are likely to get caught on things, as well as being operable with an extremely small effort by the user's hand alone, thanks to the opposition of the thumb to the other fingers. The buckle is devised in such a way that the point of actuation can be located without any possibility of error. The buckle has an ultraflat structure formed by two thin layers set on top of one another which constitute, in the case of one layer, the support that carries the take-up roller of the strap, and, in the case of the other layer, the flexible lamina that carries the catch. The manoeuvre for releasing the catch is performed thanks to two opposed wedges, which are inserted between the aforesaid two layers, these wedges being actuated by pressing, between the thumb and the forefinger, two opposed push-buttons, pushing them in opposite directions parallel to the serrations of the strap with an immediate and ergonomically advantageous manoeuvre.

All this is achieved with minimal encumbrance since the thickness is extremely small (e. g., less than 8 mm), without any protruding tabs that are liable to catch on things.

It should be noted that there are also known adjustable buckles that are applied in particular to bathing caps or clothing, the said buckles consisting of a non-elastic strap having a serrated surface in the form of a rack or of a ribbon for a zip fastener, on which a slider slides, the positioning of which can be blocked or else freed by the translation, on the part of the user, of a catch in a direction perpendicular to

that of adjustment. Buckles of this type, which do not use a sliding elastic strap or a take-up member and in which the catch is not raised but translated in a direction perpendicular to that of adjustment, are evidently not comparable in the least with the buckle according to the present invention.

Brief description of the drawings The invention will now be described in detail with reference to Figures 3-10 of the attached drawings, which are provided purely by way of non-limiting example, and in which: -Figure 3 is a schematic perspective view of one part of a pair of goggles for swimming equipped with a buckle according to the invention, for fast adjustment of the strap; -Figure 4 is a front elevation, at a larger scale, of the buckle; -Figure 5 is a side elevation of the buckle; -Figure 6 is a perspective view of the buckle; -. Figure 7 is a plan view showing one of the components of the buckle before assembling; -Figure 8 is a longitudinal cross-sectional view according to the line VIII-VIII of Figure 4; -Figure 9 is an exploded perspective view of the buckle; and -Figure 10 is a cross-sectional view, at a larger scale, according to the line X-X of Figure 7.

Detailed description of the invention The example that will now be described refers to the application of the buckle according to the invention to a pair of goggles for swimming, part of which is denoted by G in Figure 1. It should be noted, however, that the buckle may be likewise applied to other different pieces of equipment for practising water activities, such as protective goggles,

underwater masks, flippers for swimming, knives for use by scuba divers, and also to other different pieces of equipment for sporting activities or activities of another nature.

The part of the goggles for swimming G, represented in Figure 3, has a flexible side appendage F, which is elastically deformable for the reasons that will be clarified in what follows. Fixed to the aforesaid side appendage F is the buckle according to the invention, designated, as a whole, by 20.

With reference in greater detail to Figures 4-6,8 and 9, the buckle 20 basically comprises a support, designated as a whole by 21, which has a generally planar shape, and a flexible lamina 22, which is parallel and adjacent to the support 21.

As illustrated in Figure 7, the support 21 is in turn constituted, in a single piece of moulded plastic material, by a base 23 formed, at one end, with a pair of projecting tabs 24 for supporting in rotation a transverse take-up roller 25, and, at the other end, with a fork part 26. The said fork part 26 is, in fact, made up of two elastically sprung arms 27 joined on one side by a yoke 28 provided with a pair of transverse studs 29. The fork part 26 is connected to the base 23 by means of a hinged bridge or link 30, about which the aforesaid fork part 26 is, upon assembly, made to rotate starting from the position represented in Figure 7, so that it overlaps the base 23 in such a way as to cause the support 21 to assume the configuration depicted in Figures 4-6,8 and 9. According to this configuration, the studs 29 engage corresponding holes 31 of the base 23, and the sprung arms 27 set themselves along the lateral edges of said base 23.

Obviously, the fork part 26 could also be formed by a piece distinct and separate from the base 23.

Each of the two arms 27 is integrally formed with a respective enlarged portion 32, which, as will be seen, constitutes a control button, and with a respective wedge-shaped appendage 33 protruding from the inner side of the push-button 32. As may be seen from Figures 3,6 and 9, each push-button 32 has, on its front side, a visual indication in the form of'an arrow 34 designed to indicate the direction of its operation.

In the assembled condition illustrated in Figures 4-6,8 and 9, the push-buttons 32 are arranged at the side of the base 23, and the wedge-shaped projections 33 are housed in a slidable manner within corresponding recesses of said base 23.

The flexible lamina 22, which is also normally made of moulded plastic material, is fixed in cantilever fashion at one end of the region of the base 23 of the support 21 opposite to the take-up roller 25. This manner of fixing can be achieved with any suitable system, and, more conveniently, as in the case of the example illustrated, by means of integral appendages (Figures 5,8 and 9) slotted into an opening 37 of the base 23. At its free end, the lamina 22 defines a rounded-. off catch 38 facing the take-up roller 25.

The buckle 20 may be completed by a protective dome or cap 42 applied by snap action or slotted onto the support 21 for protecting the area of the take-up roller 25 and by a fixing member 39 (Figures 3 and 8) consisting of a stud inserted through the flexible appendage F of the goggles G and engaged in corresponding openings 40,41 respectively of the lamina 22 and of the base 23 of the support 21 for fast and disengageable anchorage of the buckle to the goggles G.

In the mounted condition, the end area of the flexible lamina 22 bearing the catch 38 extends above

the recesses 35, and hence above the wedge-shaped projections 33. In the absence of forces applied from outside on the push-buttons 32, the sprung arms 27 are undeformed, and the wedge-shaped projections 33 do not interfere with the sprung lamina 22, which, in this way, remains in the undeformed, resting, condition illustrated in Figure 8.

The strap, fast adjustment of which is obtained- with modalities that will be clarified in what follows -by means of the buckle 20 according to the invention, altogether corresponds to those according to the prior art described previously with reference to Figures 1 and 2. The strap consists, in fact, of a ribbon or strip of elastic material 10 (rubber, silicone rubber, elastomeric material, such as thermoplastic rubber, plasticated PVC, polyurethane, etc.) having an end portion 9 formed on one face with a series of ribs or serrations 8, i. e., a series of notches, normally having a saw-toothed shape. As may be clearly seen in Figure 8, the strap 10 winds onto the roller 25 with the serrations 8 facing the catch 38, and is guided through the protective cap 42. In the undeformed, resting, condition of the lamina 22, the catch 38 is thus engaged on one of the said serrations 8, in the way represented in Figure 8.

During operation, as explained previously, in the absence of actuation of the push-buttons 32, the catch 38 engages one of the serrations 8 of the strap 10. The extension of the said strap 10 is, in this way, prevented, whereas, in order to shorten the strap 10 it is sufficient to apply a tensile force on its end 9. As a result of this tensile force, which will be conveniently applied (thanks to the presence of the flexible appendage F to which the buckle 20 is connected) in the direction indicated by the arrow B,

i. e., towards the outside of the goggles G, automatic disengagement is obtained between the catch 38 and the serrations 8. In practice, the lamina 22 is elastically bent, so enabling the catch 38 to jump freely over the serrations 8.

In order to obtain lengthening of the strap 10, i. e., to ease off the tension when the user is wearing the goggles G on his head, it is sufficient to operate the two push-buttons 32 manually, bringing them closer to one another as a result of the elastic deformation of the corresponding arms 27. This manoeuvre simply requires a pressure applied by the user's thumb and forefinger on the two push-buttons 32, as a result of which the wedge-shaped projections 33 are introduced between the base 23 of the support 21 and the lamina 22, positively causing the elastic deflection of the latter. This causes disengagement of the catch 38 from the serrations 8, thus enabling the strap 8 to slide freely around the roller 25. As soon as the pressure of the user's thumb and finger on the push-buttons 32 is released, the lamina 22 returns to the undeformed, resting, condition, and the catch 38 engages the notch of the serration 8 facing it.

As already explained previously, the goggles G will be equipped, on the side opposite to the one illustrated in Figure 3, with a second identical buckle 20 for adjustment of the other end portion 9 of the strap 10.

The advantages resulting from the configuration and operation of the buckle according to the invention may be summed up as follows: -the total thickness of the buckle, thanks to the flat conformation of all its components, can be kept at very low values, for instance in the region of 6-8 mm, with evident advantages both in hydrodynamic terms and

from the aesthetic standpoint; -absence of protruding parts that might catch on things, such as the manoeuvring fingers or tabs of the known buckles described previously, which are both dangerous and fragile ; -possibility of precise operation requiring very little effort, thanks simply to the opposition of the thumb to the forefinger.

-possibility, thanks to the absence of rear manoeuvring fingers or tabs and thanks to connection, on goggles and similar equipment, via flexible attachment parts of the buckle, of adjustment of the strap (i. e., shortening its length) by pulling the two ends outwards instead of backwards.

It can be readily demonstrated that: * the said manoeuvre is possible because there does not exist the risk of breaking any manoeuvring fingers or tabs, in so far as there are no such items present ; * the said manoeuvre is facilitated by the fact that the buckles are connected to soft or flexible elements of the structure of the goggles or of the equipment to which the buckle is applied; the said manoeuvre is by far the most instinctive in that it is adopted spontaneously by the majority of users, including beginners; in the case of goggles or masks, the said. manoeuvre does not compress the goggles or mask on the face to an exaggerated extent (so preventing the extremely bothersome"suction pad"effect, which instead occurs with known buckles of the type described previously, which force the user to pull the strap backwards); and again in the case of masks and goggles, the said manoeuvre, when the buckles are pulled away from the temples, does not cause the hair to get entangled

inside the mechanism, and thus get pulled or torn out; for this reason, the buckle according to the invention is ideal, above all, for being used by children, It should be emphasized that the above advantages can be achieved also in the case where the manoeuvring system of the buckle according to the invention is constituted, instead of by a pair of opposed push- buttons, by a single push-button that can be displaced in a direction parallel to the serrations of the strap to operate a wedge-like or cam-like member having shape and dimensions such as to cause elastic deflection of the flexible lamina 22 in the way described previously.

To sum up, the buckle according to the invention can be applied to straps made of elastic material, the end regions of which, of adjustable useful length, are shaped like a strip or ribbon and have a face that is ribbed by means of transverse serrations, i. e., a series of notches which are either in relief or indented, possibly having a saw-toothed shape, in which the said end regions are wound through approximately 180° around a rotating roller (or even a simple fixed cross member) and are positioned with the smooth part in contact with the roller and with the serrations outwards, the roller constituting the reaction support which counters the action of a catch or pawl of a ratchet mechanism. The said mechanism, by an appropriate interplay of forces enabled by the geometry of the ensemble, when pulled, tends to wedge itself at the base of the serrations of the strap and thus prevents it from sliding in at least two directions, whilst in the remaining direction it is the serration that automatically raises the catch, the releasing action being obtained by raising the catch by means of one or more displaceable wedges, in a direction parallel to that of the serrations of the strap, by the

opposition of the user's thumb and forefinger.

Of course, the details of construction and the embodiments may vary widely with respect to what is described and illustrated herein, without thereby departing from the scope of the present invention as defined in the ensuing claims. Thus, the wedge-type operating system can be replaced by functionally equivalent solutions.