Description of the prior art As is known, fluorescent lamps, often also referred to as electronic lamps, are now being used to an ever greater extent on account of their smaller consumption and longer life and are gradually taking the place of the traditional incandescent lamps. However, these lamps have a relatively greater first cost and for this reason are frequently stolen when they are installed in such public places as hotels, exhibition halls, and the like.

Coming to grips with this problem, i. e. the search for a solution that will prevent or at least discourage the theft of the lamps, is however subject to a number of constraints that have to be taken into account. The solution must be obtained by means of a simple configuration of the antitheft device, which must be such as not to have a significant effect on the cost of the lamp, and must also be capable of being adapted to the largest possible number of lamp typologies. Furthermore, it must be such as to be capable of being installed very rapidly by anybody and with nothing other than tools in common use and, lastly, must not have any perceptible effects on the aesthetic appearance of the lighting equipment of which the lamp forms part, nor must it interfere with the proper functioning of this equipment.

Object and Summary of the invention Therefore, the object of the present invention is to provide a fluorescent lamp with an antitheft device that satisfies all the aforesaid requirements and, more particularly, proves capable of hindering the unscrewing of the lamp, thereby discouraging attempts to steal it, and to obtain all these results with an elementary structure that is versatile, easy to install and has negligible effects on the lamp's aesthetic appearance.

This aim is attained by means of the fluorescent lamp in accordance with the present invention, which comprises a lamp body comprising a side wall and a bottom wall defining a chamber within which there are housed the electronic components that make the lamp function, the electric contacts being carried by a central appendix extending from said bottom; at least one fluorescent element extending from one part of said body and a screw base extending from the opposite part and surrounding said appendix, which projects from the end of the base.

According to the invention, the screw base is inseparably, yet pivotably, fixed to the lamp body and means are provided for making the body and the screw base pivotally integral, said means being activable when it is desired to screw the lamp into the lamp holder or unscrew it therefrom and deactivable to prevent unauthorized unscrewing.

In a particularly preferred embodiment of the invention the screw base is fixed to a centrally hollow dish-shaped member, said member, in its turn, being fixed to the lamp body by means of a snap attachment and capable of being rotated with respect to the body. The dish-shaped member has at least one lateral pocket that, following an axial rotation of the dish-shaped element, can be aligned with an opening formed on said body, and a threaded

element is engageable either partly or wholly within said pocket, the element in the former case being also engaged with said opening, when that opening is aligned with the pocket, whereby the body is made integral with the screw base, while in the latter case, being wholly disengaged from said opening, whereby the body is allowed to freely rotate with respect to the screw base.

Brief description of the drawings Further characteristics and advantages of the fluorescent lamp in accordance with the present invention will be apparent from the following description of a particular embodiment thereof, which is to be considered as an example and not limitative in any way, said description making reference to the attached drawings, in which: - Figure 1 shows a bottom perspective view of the lamp in accordance with the invention as seen from below; - Figure 2 shows a partially exploded view of the lamp of Figure 1; - Figure 3 shows another partially exploded view of the lamp of Figure 1; - Figure 4 shows a section through the lower part of the lamp of Figure 1; - Figure 5 shows a partial cross section of the lamp of Figure 1 without the screw base Detailed description of the Invention Referring to these figures, the reference number 1 has been used to generically indicate a lamp body that comprises a side wall 2 and a bottom 3 and is closed at the top by a base-4 from which there extend fluorescent tubes of the conventional type. Body 1 defines within it a chamber 6 in which there are housed the electronic components of the lamp, generically indicated by the reference number 7 and not here described in detail,

because they are of the conventional type and do not come within the scope of the present invention.

In the embodiment of the invention illustrated in the figures side wall 2 of lamp body 2 is cylindrical, and its bottom 3 has the shape of a truncated cone, as is in any , case usual with lamps of this typology, and from bottom 3 there extends an appendix 8 ending with a first electric contact 9.

Appendix 8 is also provided with a second electric contact on its side, said contact being constituted by two blades 11 that extend from diametrically opposite points of the lateral surface of the appendix. In particular, each blade 11 is provided with a pair of projecting tabs lla, acting just as. electric contacts, and is arranged between two small ribs 12 formed on the lateral surface of appendix 8. Furthermore, each blade 11 is formed with a central window 13 that engages with a lead-in projection 14 extending radially from the lateral surface of appendix 8. Furthermore, each blade 11 is engaged at its upper end with a notch 15 cut in bottom 3 of lamp body 1, while a flap 16 at its lower end is bent inwards and rests against the edge of end 8a of appendix 8. In this way blades 11 are prevented from sliding in any direction, be it axial, circumferential or diametrical.

In the exemplifying embodiment of the invention illustrated by Figure 5 only one of blades 11 is connected to the power supply of the lamp by means of an electric conductor 17, while the other blade has been provided only for obvious reasons of balancing the pressure forces exerted by projecting tabs lla that serve as contacts.

Obviously, however, second blade 11 could likewise be connected to the power supply of the lamp.

For the purpose of connecting it to a lamp holder, the lamp is provided with a conventional screw base 10, which

according to the invention is attached to a dish-shaped element 18 comprising a tubular threaded portion 18a, to which screw base 10 is screwed and then fixed by means of mechanical seaming, and a dish portion 18b having the shape of a truncated cone and formed with two diametrically opposite pockets 19 sideways extending along the dish portion. The two pockets are threaded on their inside in order to enable them to accommodate respective threaded studs 20 having a length that does not exceed the depth of pockets 19. The assembly constituted by screw base 10 and dish-shaped member 18 is connected to lamp body 1 by inserting appendix 8 in screw base 10 and then sliding the screw base 10 until flared projection 14 becomes snap-fastened against free edge 21 of tubular portion 18a. In this way screw base 10 comes to be irreversibly fixed to lamp body 1, though allowing the latter to be rotated with respect to screw base 10 and yet assuring electric contact by means of projecting tabs lla that bear elastically against the inside of screw base 10.

Side wall 2 of lamp body 1 extends for a certain portion 2a around conical bottom 3 of lamp body 1. On this portion 2a of lamp body 1 there is formed a recess 22 that, thanks to the pivotal connection between screw base 10 and lamp body 1, can be brought into alignment with one of the two pockets 19 present on the conical portion of dish-shaped element 18. In these conditions, depending on the position of stud 20 relative to its pocket 19, lamp body 1 can either be locked to screw base 10 so as to rotate with it or be left free to rotate with respect to it. In fact, using an appropriate tool, possibly a dedicated tool, stud 20 may be partially unscrewed to the point of becoming engaged with recess 22, as shown in Figure 1. In this condition, obviously, the lamp can readily be screwed into the lamp holder, and also removed

from it, because lamp body lis integral with screw base 10 and rotates with it. But when stud 20 is completely screwed into pocket 19, as shown-for example-in Figure 4, lamp body 1 can obviously rotate with respect to screw base 10, so that any attempt to unscrew the lamp from its lamp holder is bound to fail.

In the embodiment of the fluorescent lamp according to the invention illustrated by Figure 4 dish-shaped element 18 is provided with a pair of'pockets 19. Even though a single pocket 19 would be formally sufficient, it is preferable to provide two such pockets on diametrically opposite sides, this for reasons of convenience in case of particular installations in which the lamp is screwed into the lamp holder in such a way as to make it difficult to gain access to one of the pockets.

Variations and/or modifications could be brought to the fluorescent lamp with antitheft device in accordance with the present invention without departing from the scope of the invention as defined by the claims hereinbelow.