Document WO-A-02061222 of the same Assignee of the present application discloses an anti-theft device for eyeglasses that is the closest prior art for the device of the present application. The device of document WO-A-02061222, whose characteristics are scarce encumbrance, practical use and easy handling, has a wheel for adjusting the grip on the arm member that is accessible from the user and therefore, in particularly harsh environments, the wheel could be tampered with tools adapted to force or break it.

Object of the present invention is solving the above prior-art problems, by providing an anti- theft device in which the means for adjusting the gripping pressure on the arm member are not directly accessible by the end user that wears the glasses.

A further object of the present invention is providing an anti-theft device of the above- mentioned type that is scarcely encumbrant, of light weight, has high strength against thefts and can be easy activated by the sales personnel that must place it on the objects to be protected.

The above and other objects and advantages of the invention, as will appear from the following description, are obtained by an anti-theft device as claimed in Claim 1. Preferred embodiments and non-trivial variations of the present invention are claimed in the dependent Claims.

The present invention will be better described by some preferred embodiments thereof, given as a non-limiting example, with reference to the enclosed'drawings, in which: - Figure 1 is an exploded perspective view of the main components of an embodiment of the anti- theft device of the present invention; - Figure 2 is a side sectional view of the anti-theft device in Fig. 1 ; - Figure 3 is a perspective sectional view of the anti-theft device in Fig. 1; and - Figures 4 to 8 are views that show the main detachment operations of the anti-theft device of the invention from a pair of glasses.

With reference to the Figures, a preferred embodiment of the anti-theft device of the present invention is shown and described. It will be immediately obvious to the skilled people in the art that numerous variations and modifications (for example related to shape, sizes and parts with equivalent functionalities) could be made to the described device without departing from the scope of the invention as claimed in the enclosed Claims.

The Figures show the anti-theft device 1 of the present invention in its most common application for protecting eyeglasses 2. It will be immediately obvious for the skilled people in the art that such device 1 can be applied efficiently as well to any object equipped with elongated members, arm members, etc. , for which protection is needed.

With reference to the Figures, the anti-theft device 1 for objects 2 equipped with at least one arm-member 4, particularly for eyeglasses 2, comprises: - tightening means 3 of the arm-member 4, in which the tightening means 3 are adapted to assume an open position in which they receive . therein or free therefrom the arm member 4 and a closed position in which they are unmovably tightened against the arm member 4; control means 5 of the tightening means 3, in which the control means 5 are adapted to move the tightening means 3 between their two opened and closed operating positions; containment means 7 containing therein anti- theft means 8 and the control means 5: the containment means 7 are adapted to be opened to allow accessing the control means 5 and to be closed to prevent accessing the control means 5, while the tightening means 3 are connected to the containment means 7 in order to project outside them without allowing accessing the control means 5 from a side where the tightening means 3 are located; engagement and disengagement means 9 of the containment means 7, in which the engagement and disengagement means 9, in their engagement and closure position, are adapted to engage the containment means 7 keeping them closed and preventing accessing the control means 5, while the same engagement and disengagement means 9 are attracted into their disengagement and opening position by external magnetic means 10 in order to disengage the containment means 7 by opening them and allowing accessing the control means 5 ; such engagement and disengagement means 9 are contained inside a housing 11 that cannot be accessed from the outside and is connected to the containment means 7.

In particular, the tightening means 3 are composed of at least one pair of plates 12,14, one 12 of these plates 12,14 being fixed and another one 14 of the plates 12,14 being operatively connected to a vertically moving control pin 18.

The plates 12,14 are housed inside two ring-shaped parts 15', 15''for containing the arm member 4.

Each one of such plates 12, 14 is wholly composed (as shown) of or is equipped with at least one layer of rubber adapted to improve the grip on the arm member 4 to be tightened.

Still in particular, the control means 5 are composed of a small rod 20 equipped with a threaded shank 16 and operatively connected to the vertically moving control pin 18: the rotation of the small rod 20 by means of fingers of a hand vertically moves the control pin 18, in order to mutually approach or move away the plates 12,14 through the control pin 18.

The control pin 18 is operatively connected to the threaded shank 16 of the small rod 20 through a . circular crown 21 adapted to engage a corresponding circular crown 23 obtained inside the threaded shank 16.

The control means 5 further comprise retainer means (not shown) adapted to keep the small rod 20 in a closure position, once having obtained the tightening of the arm member 4.

Instead, the containment means 7 are composed of a box-shaped body equipped with a base 22, containing the anti-theft means 8 and the control means 5, and of a cover 24 hinged (in 26) to the base 22 in order to be able to be opened and closed onto the base 22. The base 22 and the cover 24 are both equipped with at least one hole 26,28 : the holes 26, 28 are mutually coaxial and are adapted to simultaneously pass therein the engagement and disengagement means 9 when closing the containment means 7.

In order to realise a compact structure with scarce encumbrance, in addition to improve the device strength and increase its resistance against tampering attempts, the cover 24 is adapted, when closing, to be completely contained within the encumbrance of the base 22.

In a known way, the anti-theft means 8 are composed of at least one electric wire wound in coils and adapted to activate theft-detecting means (not shown) upon passing inside a magnetic field generated by the theft-detecting means, an activation of the theft-detecting means activating in turn acoustic and sound signalling means (not shown), common in the shops where such type of global anti-theft system is installed.

The engagement and disengagement means 9 are composed of at least one small elongated cylinder 35 cooperating with a spring 37 abutted against abutment means 39: such spring 37 is adapted to push the small cylinder 35 in its operating closure position of the containment means 7 making it penetrate into the holes 26, 28. The small cylinder 35, when is made approach the external magnetic means 10, is adapted to be attracted in an opening *. position outside the holes 26,28 by the external magnetic means 10 that exert an attraction force that opposes a counteracting thrusting force of the spring 37.

With reference now to Figures 4 to 8, the main operating steps for detaching the anti-theft device 1 from the glasses 2 will be described; it is obvious that, by suitably reverting the steps, the attachment of the device 1 to the arm 4 of the glasses 2 to be protected, could be realised.

In Fig. 4 it is noted how the glasses 2 with the device 1 are made approach the magnetic detachment-means 10, by inserting the housing 11 in a suitably obtained recess 40 of the magnetic means 10. Upon inserting the device 1 into the recess 40, the small cylinder 35 is attracted downwards (in the Figures) exceeding the force of the spring 37, thereby freeing the cover 24 that can be opened (Figure 5). The complete opening of the cover 24 (Figure 6) makes the control rod 20 accessible to the authorised user (usually the cashier of the shops selling the glasses 2).

The user takes then care of rotating the small rod 20 till a complete opening of the tightening means 3 occurs (Figure 7), namely till a complete mutual separation movement occurs where the plates 15', 15''separate one from the other.

It will then be possible (Figure 8) to remove the arm 4 of the glasses 2 from the device 1, that remain ready to be inserted onto another article 2 to be protected.