Technological background In the technical field to which the invention relates, there are known hinge devices of resilient type, in which springing is provided acting along the hinge axis arranged to return the arm resiliently towards preferred angular positions, for example when the arm is swiveled beyond the normal open position with respect to the front of the spectacles.

A device having the characteristics cited above is known for example from the international patent application published under the number W097/01125.

This proposes a hinge device in which the two hinge elements, respectively connected to the arm and the front structure of the spectacles, are loaded against each other by means of springing acting along the hinge axis. The contact surfaces of the two elements are also shaped with a projection with inclined sloping sides cooperating with one or more cavities, in such a way that at any relative angular position between them, resulting from one hinge element being swivelled relative to the other, the axial distance between the latter is varied, counter to (or assisted by) the action of the springing.

A limitatioh found in this type of hinge consists in the fact that the resilient springing and the two hinge elements are held in position by a screw, also constituting the hinge pin, which may loosen ih use and therefore be lost.

Description of the invention The problem addressed by the invention is that of making available a hinge device for connecting the arms to a front structure of a spectacle frame, structurally and functionally designed to overcome the limitations indicated above with reference to the known technology cited.

In connection with this problem, a further purpose of the invention is to produce a hinge device of resilient type in which the parts of the device in movement are protected and masked from view, so as to shield the hinge on the outside and at the same time ensure a pleasing appearance.

This problem is solved by the invention by means of a hinge device produced in accordance with the claims which follow.

Brief description of the drawings The characteristics and advantages of the invention will become clearer from the detailed description of a preferred example of embodiment illustrated, purely by way of non-limiting example, with reference to the appended drawings, in which: - figure 2 is an exploded perspective view of a hinge device produced according to the invention, - figure 1 is a view in axial section of the device in figure 2, in the assembled configuration, - figure 3 is a schematic view of a detail of the device in the preceding figures.

Preferred mode of embodiment of the invention With reference to the drawings cited, the number 1 indicates as a whole a resilient hinge device for spectacles produced according to the invention.

The hinge device 1 comprises a first and a second hinge element 2,3, respectively connected to an arm 4 and to a front structure, shown only partly in the drawings.

The first and the second hinge elements 2,3 are capable of swivelling relative to each other about a hinge axis X, substantially perpendicular to the direction of longitudinal development of the arm 4.

The first hinge element 2 comprises a cylindrical sleeve 6, closed at one axial end by an end piece 7 and open at the opposite end. The sleeve is coaxial with the hinge axis and is also held rotatably about said axis between a pair of lugs 8,9, facing each other, of a fork element 10 of the second hinge element 3, with the possibility of relative axial sliding along the axis X relative to the lugs 8,9.

At the end piece 7, the sleeve 6 is accommodated rotatably, with radial play, in a hole 11 in the fork lug 9.

In the fork lug 8, coaxial with the hole 11, there is a second through hole 12 threaded internally into which is fitted by screwing a tubular body 13 externally threaded over a first axial length, which is further extended into a second length projecting from the first fork lug 8 in the direction of the second lug 9.

The tubular body 13 is closed at one axial end by a head 14 which has a screwdriving slot 15, and also forms, inside the body 13, a blind cavity 16 coaxial with the sleeve 6. sliding coupling means, indicated as a whole by the number 17, are provided between the sleeve 6 and the tubular body 13 and are such as to allow relative axial movement between the sleeve and the tubular body along the axis X while providing each other with support rotatably about said axis.

The means 17 comprise respective end portions of the sleeve 6 and of the body 13, facing towards each other and including respectively annular lip formations 18, 19, coupled with each other. In the example described, the lip 19 is made in the body 13 and coupled telescopicaliy to the lip 18 by the

inside of the sleeve, the relative axial sliding being guided along reduced portions of the respective cylindrical shells formed by the lips 18,19, as shown in figure 1.

The number 20 indicates a tubular element extending between the fork lugs 8, 9 which is arranged to be fitted, with radial clearance, onto the sleeve element 6.

The tubular element 20 is also provided with a first and second slotted through opening, respectively indicated as 21 and 22.

The first opening 21 extends parallel to the hinge axis, starting from one axial end of the tubular element 20. Running through the opening 21 is an attachment member 23 connected to the sleeve 6, arranged for connecting to the arm 4 of the spectacles.

Because of the slotted opening 21, the attachment member 23 can slide freely relative to the tubular element 20 along the axis X, being limited to the extension of the slot 21.

The second slotted opening 22 extends circumferentially in the cylindrical shell of the tubular element 20 and is of such dimensions as to be engaged slidably by the free end of an appendage 24 projecting from the fork element 10 transversely to the hinge axis X.

The hinge device 1 also comprises contact surfaces located on the first and on the second hinge element 2,3, capable of sliding one upon the other when there is relative swiveling between said elements about the hinge axis. said surfaces are loaded in contact against each other due to the resilient action of a spring 25 accommodated, coaxially with the axis X, partly in the sleeve 6 and partly in the tubular body 13, and also acting between the end piece 7 and the head 14.

The contact surfaces comprise respectively a projection 26 on the first hinge element and a recess 27 on the second hinge element, capable of fitting together with each other at defined preset angular positions in the relative swivelling of the two hinge elements.

More particularly, the projection 26 is formed by the rounded section of a cylindrical pin 28 driven into the fork lug 9 and the recess 27 comprises a pair of grooves 29,30 made in the sleeve 6 at the opposite end to the end piece 7.

The grooves 29,30 intersect each other and have respective rounded groove cavities with a radius of curvature such as to accommodate the rounded section of the cylindrical pin 28.- Advantageously, the grooves 29,30 extend longitudinally perpendicularly to each other so as to provide two preferred angular swivel positions of the arm 4 arranged angularly at 90° relative to each other. In particular, the grooves 29, 30 are formed in the sleeve 6 so that the cylindrical pin 28 is accommodated in one or other of the grooves when the arm 4 is swivelled into the normal closed position or into the normal open position, with respect to the front structure. The changeover from one position to the other is obtained by the uncoupling of the pin 28 from the respective groove 29,30, counter to the resilient action of the spring 25 and relative sliding between the contact surfaces until the next groove is reached.

With reference to figure 3, the slotted opening 22 is extended-by a circumferential arc greater than the angle of 90° included between the grooves 29,30. In this way, when the arm 4 is swiveled open, further angular travel Is permitted, equal to an angle A preferably of about 20°, Until the limit imposed by the appendage 24 coming to rest against the end of the slot 22 in which it is engaged is reached. It should be noted that in this additional travel, the pin is not completely disengaged from the corresponding groove so that

the resilient return action of the spring 25 is such as to return the arm 4 to the preset angular position.

The hinge device 1 is assembled firstly by inserting the sleeve 6 into the tubular element 20 and positioning both between the lugs 8,9 of the fork, in a position coaxial with the hinge axis X. It should be noted that the distance between the lugs of the fork is such as to allow the tubular element 20 to be inserted transversely between them, with the sleeve 6 then being accommodated in the hole 11 in the lug 9.

Then, the spring 25 having first been inserted inside the sleeve 6, the body 13 is inserted from the outside of the fork into the lug 8 of the fork and screwed into the corresponding hole 12 until tight relative to it. This assembly is carried out coaxially with the hinge axis so as to ensure the sliding coupling between the sleeve 6 and the tubular body 13.

It should also be noted how the coupling means 17 between the sleeve and the tubular body relative to the X axis contribute, on the one hand, to the guiding action between the hinge elements and, on the other, perform a function of masking the spring 25 on the outside, at any stage of operation of the hinge device. These may however be omitted since the guiding function is performed mainly by the remaining structure (parts 20,6, 13).

In use, when the first hinge element is swivelled about the axis X, the projection with the cylindrical pin is caused to slide relative to the contact surface facing it, changing over from one groove to the other. This involves an axial movement of the sleeve relative to the fork and consequent compression of the spring.

The invention therefore solves the problem proposed, offering numerous advantages compared with known solutions.

A first advantage consists in the fact that the hinge joint of the device according to the invention is obtained by the rotatable/slidable coupling of tubular elements without the use of any screw constituting the hinge pin, which may possibly loosen in use.

Another advantage lies in the fact that the springing acting on the resilient hinge according to the invention, and also the contact surfaces are completely masked within the structure of the device, with a consequent appreciable improvement in the overall appearance of the hinge.

Not least is the advantage relating to greater ease and simplicity of assembly of the hinge device.