At the present state of the art spectacles are well known. These accessories, always more frequently used by both adults and children, as already observed, can be of the corrective type, to cure eye pathologies, or of the sunglass type, used subjectively as a protection against solar radiation.
Spectacles, as a rule, are composed likewise of a frame, and of the respective lenses supported by it which are adapted by shaping them peripherally, according to the internal conformation of the respective, so-called, circles or lens surrounds. In other cases again, variations can be made to the support means of the lenses and can concern portions or parts of frame not joined at their ends, on which, previously, the respective lenses are fixed by screwing means. In this last hypothesis a successive adaptation of the lenses to the frame of the spectacles may not be necessary.
Generally, however, the traditional type frames can be subdivided into two large categories depending on the material from which they are made. The first are made of metal, while the second are of plastic material, furthermore alternative solutions could be provided that combine the two materials differently. Both then, have a common structure which provides circles or lens surrounds, held together by one or more connecting bridges depending on the aim. As regards the metallic frame, the use of the bridge, besides having an aesthetic factor, provides a stiffening means for the structure, mainly with the aim to avoid the phenomenon of buckling of the lens surrounds. And a certain rigidity of the structure is surely necessary also for maintaining a correct wearing of the spectacles, ensuring the focusing of the lens with respect to the eye to be corrected. Furthermore nose pads are associated to the frame of the spectacles, which have the function of supporting the frame by causing it to rest with the pad on the surface of the nose. Both for the bridge, and for the anchorage of the nose pads to the frame of the spectacles, one currently resorts to a simple welding of the ends, fixing the whole firmly to the profile of the lens surrounds. In a few variations, the nose pads can also be hinged to the support means to allow a greater adaptability of the frame with respect to the surface of the nose, and therefore avoiding the annoying sliding forwards of the spectacles.
However in the above mentioned solution, drawbacks appear, which are in fact that the frame is not sufficiently resistant to knocks and accidental deformation, causing the breaking of the weakest parts, as for example, the joint of the bridge to the lens surrounds, or even causing the deformation of the support arms of the nose pads. The rigidity of the frame, if subjected to an involuntary deformation, could also cause the lens to fall out of the surrounds and possibly break on reaching the ground. Such problems are greater amongst the younger public who are less careful with their spectacles, and also for example when playing games or participating in sports activities, breakages could occur.
A proposal to resolve even such a problem, has consisted in providing frames made entirely of a more or less rigid plastic material, for example of nose pads formed monolithically, these last being an increase of the border of the lens frame in correspondence with the resting arch at the bridge of the nose. The drawback of this type of frame is that it does not allow for a correct wearing, above all due to the absence of pronounced nose pads, therefore involving an inability to focus the lens so mounted in the lens surrounds. In the second place, having to guarantee a certain structural rigidity that should tend to prevent natural phenomena of elastic recall of the frame, they are not sufficiently flexible and able to avoid possible breakages in the critical stiffening points of the structure.
Some alternatives have intended subdividing the spectacle into two halves providing the use of hinges in an intermediate position with respect to the bridge, or have made only the lens surrounds flexible, playing on the type of material used, while in such a case the bridge and the nose pads have maintained their rigidity. Finally there exist devices, like those for the measurement of the diopters, that act by means of a screw positioned in proximity to the nose pads, that are able to adjust the amplitude of the lens surrounds, extending a telescopic element with bridge function for the connection between the same. But even in these umpteenth solutions it isn't difficult to discover drawbacks, which consist in the fact that both the nose pads and said bridge are always made of rigid elements and as such susceptible to breakage or at least deformation.