DESCRIPTION FIELD OF THE INVENTION The present invention concerns a method and an apparatus for carrying out the sterilization of footwear, particularly the sterilization of shoes. More in detail, the method and the apparatus according to the present invention allow to cany out the sterilization of shoes at the end of their production process, before proceeding with their storage and the subsequent transportation for the product selling. The sterilization process, at the end of the footwear production process, is necessary for eliminating bacteria, mildews and fungi eventually present and for impeding their proliferation during the stocking and transportation period, until the footwear selling. KNOWN PREVIOUS ART For carrying out said footwear sterilization, and hence for eliminating bacteria, mildews and fungi, it is known art to treat the object to be sterilized with the action of ultraviolet-type rays, in fact, such organisms cannot withstand such a type of radiation that causes their death. The previous art comprises some apparatuses for footwear sterilization taking advantage of the ultraviolet ray action, such as for example that described in the Japanese Patent JPl 1056982 intended for the sterilization of slippers.

The sterilization apparatus described in JPl 1056982 comprises a conveyor belt for translating the slippers through a sterilization tunnel provided inside with a bactericidal lamp generating ultraviolet rays. One of the most important drawbacks of the conventional sterilization apparatuses is the ineffectiveness of the sterilization process causing the survival of some bacteria, mildew and fungi, which could thereby start reproducing again. In fact, depending on the type of bacteria and fungi, and relating to their number, the bactericide action of the lamp generating ultraviolet rays may be ineffective if, for example, the exposition time of footwear to rays is too much short. Object of the present invention is to get over such problems of the known art and propose a method and an apparatus for the footwear sterilization being able to eliminate most of the bacteria and fungi present therein, if not all. Further object of the present invention is to provide a method and an apparatus for sterilizing footwear that would be at the same time fast and effective and that could be used for sterilizing footwear already housed inside the corresponding packages. In fact, it is a further object of the present invention to allow the sterilization of footwear at the end of the production process, in such a way to save the footwear from the bacteria proliferation and the mildew production during the storage and transportation period, before selling. SUMMARY OF THE INVENTION These and other objects are fulfilled thanks to the method, according to claim 1, and to the apparatus, according to claim 12, for carrying out the sterilization of footwear, particularly shoes. Further specific characteristics of the present invention are reported in the corresponding dependant claims. The method for sterilizing footwear is earned out by a sterilization apparatus comprising one or more sterilization chambers, first means for generating heat and second means for generating ultraviolet rays, as well as at least one device for carrying the footwear from the entrance to the exit of the sterilization chamber/chambers . The method is characterized by comprising a first step wherein the footwear are earned from the entrance to the exit of the sterilization chamber, or chambers, and a second step of sterilizing the footwear by heat and ultraviolet rays inside the sterilization chamber, or chambers. The method may in addition comprise a further step for delivering on the footwear at least one liquid, or generically a fluid, for sanitizing. It has to be observed that, herein and after, with the term "liquid, or fluid for sanitizing" it has to be intended any liquid, or more generally speaking any fluid, provided with disinfectant or sanitizing proprieties for the footwear leather, such as for example antimycotic liquids, bactericides, disinfectant gases, or other sanitizing fluids known in the art. Preferably the step of sterilizing comprises a first step of sterilizing only by heat and a subsequent step of sterilizing only by ultraviolet rays. In fact, the sterilization apparatus preferably comprises two distinct sterilization chambers in succession, wherein such means for generating heat are disposed in the first chamber and the means for generating ultraviolet rays are disposed in the second chamber. In this last embodiment, to carry out the sterilization step, the footwear is carried from the entrance of the first chamber to the exit of the second chamber. In a possible embodiment of the present invention, the apparatus according to the present invention comprises further means for delivering at least one sanitizing liquid, or more generally a fluid, disposed in a (third) sanitizing chamber wherein such footwear are carried. The method according to the present invention comprises a step of packing the footwear in a relevant box or package by packing means disposed upstream or downstream of the sterilization chamber or chambers, so that the packing step is carried out preferably before the step of carrying the footwear and before the step of sterilizing thereof. Afterwards a step of sealing the footwear is carried out by film or heat-sealed bag; in fact, a sealing device is disposed downstream of the sterilization chamber, or chambers.

The combined use of ultraviolet rays and heat, inside the same sterilization chamber, or preferably in two distinct chambers, allows to considerably improve the sterilization effectiveness, assuring the bacteria, mildews and fungi removal in short exposition periods.

Such improvements are better appreciable in the embodiment wherein at least two distinct sterilization chambers are provided, one provided with means for generating heat and the other provided with means for generating ultraviolet rays. Further, the footwear sterilization by the subsequent heat and ultraviolet ray administration in two distinct sterilization chambers and preferably reciprocally in succession, would assure a better results regarding the effectiveness of the sterilization by reducing the periods respective to the conventional sterilization methods and apparatuses, such as for example that described in JPl 1056982. Further, the possibility of sterilizing footwear also inside the corresponding boxes or packages wherein they will be subsequently stocked, carried and sold, would constitute a great advantage of the present invention. In fact, by doing so, the risk of contaminating again the footwear, with the bacteria and fungi reintroduction during their disposal inside the packages in a step subsequently the sterilization, is removed. At last, proceeding with the footwear packaging before their passing through the sterilization chambers, it is possible to treat with heat and ultraviolet rays the packages too, impeding the latter from transferring bacteria, mildews and fungi inside the footwear.

The final sealing step is carried out downstream of the sterilization chamber, or chambers, by the use of a film or heat-sealed plastic bag. Consequently, the footwear and the packages inside which they are disposed, are completely sealed in the corresponding bags at the end of the sterilizing step, removing the risk of reintroduction of bacteria and fungi during the stocking and transportation until selling. The method and the apparatus for sterilization according to the present invention may be easily used inside the process for producing footwear, particularly at the ending part thereof. In fact, the already formed footwear, preferably disposed inside the packages, are easily and rapidly carried through the distinct sterilization chambers and preferably reciprocally in succession, inside which they are firstly treated with heat and then with ultraviolet rays. BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will become more evident in the following description, for illustrative purposes, with reference to the attached figures, wherein:

• figure 1 is a schematic side view of the apparatus for footwear sterilization according to the present invention;

• figure 2 is a block diagram of the sterilization method according to the present invention;

• figure 3 is a prospective view of a further possible embodiment of the sterilization apparatus according to the present invention; • figure 3 A is a schematic plant view of the sterilization apparatus of figure

3; • figure 4 is a schematic side view of a further possible embodiment of the sterilization apparatus according to the present invention provided with means for delivering a sanitizing liquid or fluid.

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE PRESENT INVENTION

Referring to figure 1, the device for sterilizing footwear according to the present invention, in its preferred embodiment herein illustrated, comprises two sterilization chambers 1 and 2 and a device 3 for carrying the footwear 10 from the entrance to the exit of chambers 1 and 2. The embodiment herein described comprises two sterilization chambers 1 and 2, distinct and reciprocally in succession, even if, as will be evident for a person skilled of the art, according to the desired sterilization level, further chambers may be provided inside which the footwear could be moved by the carrying device 3. Every sterilization chambers 1 and 2 is provided with an entrance section and an exit section through which the footwear are carried for carrying out the sterilizing step. The chambers 1 and 2 are provided with means for generating heat 4 and means for generating ultraviolet rays 5, in themselves known in the art, for carrying out the footwear sterilization. The chambers are preferably shaped such that the footwear inserted therein would receive heat and ultraviolet rays avoiding dispersions. According to a preferred embodiment, illustrated in figure 1, the two sterilization chambers 1 and 2 are distinct and disposed in succession, the first chamber is provided with means for generating heat 4 and the second chamber is provided with means for generating ultraviolet rays 5. It has to be noticed that, although it has been explicitly referred to two distinct sterilization chambers, an apparatus provided with only one sterilization chamber, provided with means for generating heat 4 and means for generating ultraviolet rays 5, will fall within the scope of protection of the present invention. In such an apparatus type, the footwear carried inside the single chamber are subjected to the sterilizing action of the heat and ultraviolet rays at the same time. Alternatively, it is possible to use only one sterilization chamber inside which the heat and the ultraviolet rays are applied to the footwear in succession. As can be seen in figure 1, the means for generating heat 4 of the sterilization chamber 1 comprise a plurality of electric resistances 6 connected to the mains, or to one or more batteries, generating heat because of Joule effect. A fan 7, driven by an electric motor, diffuses heat over the footwear 10 inside the chamber uniformly, as it is illustrated by the arrows in figure 1. Alternatively one or more infrared lamp may be used. The temperature reached inside the sterilization chamber 1 is preferably comprised in the range between 20 - 120 °C, and would allow to obtain a high effectiveness of the footwear sterilization without the heat causing the deterioration of the material of which the footwear are realized. The second sterilization chamber 2 is provided with means for generating ultraviolet rays 5, for example a plurality of UV lamps 8 of a known type for such a use. The rays emitted by the lamps 8 will hit the footwear 10 inside the chamber. It has to be noticed that the number of lamps and the power of each one of them may change, and anyway they should assure the correct sterilization of the footwear and thereby the removal of bacteria, mildew and fungi.

As can be seen in figure 1 , the device 3 for carrying the footwear from the entrance to the exit of the sterilization chambers, comprises a flat conveyor belt 11 passing through the two sterilization chambers 1 and 2. The motion direction of the conveyor belt 11 is indicated by the arrows in figure 1, and it allows the conveyance of footwear 10 from the entrance to the exit of the first chamber 1 and subsequently from the entrance to the exit of the second chamber 2. In fact, the conveyor belt 11 passes through each sterilization chamber entering and coming out from two opposite side walls of the chamber. The footwear 10 enter into the sterilization chamber 1 inside which they are subjected to heat and subsequently they enter into the second sterilization chamber 2 inside which they are subjected to the ultraviolet rays. In fact, the sterilization chambers are disposed in succession along the motion direction of the conveyor belt 11 , and preferably, although not necessarily, the two chambers 1 and 2 are in communication because the exit section of the first sterilization chamber 1 is communicating with, that is facing to, the entrance section of the second sterilization chamber 2. The speed of the conveyor belt 11 is such as to allow the permanence of footwear 10 inside the chambers for a time period that is sufficient for carrying out the sterilizing step, that is to say a time period sufficient for removing bacteria, mildews and fungi.

Although it is not represented in detail in figure 1, the two sterilization chambers 1 and 2 may be separated by a separating curtain, or similar means, placed between the exit section of the first sterilization chamber 1 and the entrance section of the second sterilization chamber 2.

According to a preferred aspect of the present invention, the footwear are placed on the conveyor belt 11, once housed inside the packages 20, inside which they will be next stocked and sold. That is an important advantage, because the footwear, when the sterilizing operations are finished, have not subsequently to be disposed in the packages, thereby avoiding the risk of a new contamination. Further, by housing the footwear 10 inside the packages 20 before they pass inside the sterilization chambers, it is possible to treat the packaging 20 too with the sterilizing action of the heat and ultraviolet rays, so that to eliminate possible bacteria, mildews and fungi being present both on packages 20 and footwear 10 placed inside thereof.

The apparatus according to the present invention may comprise as well packing means for the footwear placed inside their relevant box or package. Such packing means, not shown in figure 1, are preferably disposed upstream of both the sterilization chambers 1 and 2, and they can be of a completely automatic type, or they may require the attendance of an operator. The packages 20, inside which the footwear are disposed, are rested over the conveyor belt 11 , allowing the movement thereof from the entrance to the exit of the sterilization chambers 1 and 2. In a possible embodiment, the packing means of the footwear 10 are disposed downstream of the first sterilization chamber 1 and upstream of the second sterilization chamber 2, that is between the two chambers. That allows to carry out a first sterilization by heat of the footwear 10 only, and then, after the packaging upstream of the second chamber 2, a subsequent sterilization of both the footwear 10 and the packages 20, inside which the footwear have been disposed, by the action of the ultraviolet rays inside the second sterilization chamber 2. Further, the sterilization apparatus is provided with a device 16 for sealing the packages 20 of the footwear 10 at the end of the sterilizing process. The sealing is carried out by the use of film or heat-sealed plastic bags 22. As can be seen in figure 1, the sealing device 16 is placed downstream of the second sterilization chamber 2, such that the packages 20 are sealed at the end of the sterilizing process. Figures 3 and 3A show another possible embodiment of the sterilization apparatus according to the present invention, wherein the device 3 for carrying the footwear from the entrance to the exit of the sterilization chambers 101 and 102, comprises a rotatable carrying plane 111.

The direction of the rotating motion of the conveyor plane 111 is indicated by the arrow in figure 3 A, and it allows the movement of footwear 110 and of the corresponding packages 120 from the entrance to the exit of the first sterilization chamber 101 and subsequently from the entrance to the exit of the second sterilization chamber 102. The first chamber 101 is provided with means for generating heat 104 comprising a plurality of electric resistances 106, whereas the second chamber 102 is provided with means for generating ultraviolet rays 105, for example a plurality of UV lamps 108.

As shown in the schematic top view of figure 3 A, the two sterilization chambers 101 and 102 are disposed in succession along the motion direction of the rotatable carrying plane 111, and they are communicating thereby allowing the sterilization of the footwear 110 applying heat and ultraviolet rays in succession. This embodiment, differently from that before described referring to figure 1, presents reduced dimensions for a limited bulk, in the meanwhile assuring a high effectiveness of the sterilizing process.

Referring to figures 1 and 2, the steps of the method for sterilizing the footwear according to the present invention will be described. The packages 20, comprising one or more footwear 10, are disposed in succession on the carrying device 3, that allows the movement thereof from the entrance to the exit of the sterilization chambers 1 and 2. The packages are disposed in succession in the starting portion of the conveyor belt 11, the translating direction thereof is represented by arrows. The packing step, wherein the footwear are housed into the corresponding packages inside which they will be stocked and sold, is carried out upstream of the sterilization chambers 1 and 2, automatically or manually. As afore said, this operation allows to treat the packages 20 too with the sterilizing process with the footwear contained therein. Obviously, the sterilizing step according to the present method can be applied to the footwear 10 only, even if, in the appended figures and herein below, reference will be made to the sterilization of the footwear 10 housed inside the corresponding packages 20.

The conveyor belt 11 moves the packages 20 in succession from the entrance to the exit of the two sterilization chambers 1 and 2, the first of which is provided with means for generating heat 4, whereas the second is provided with means for generating ultraviolet rays 5. The method according to the present invention may contemplate the movement of the footwear inside further sterilization chambers different from those until now described, for assuring more effectiveness in the sterilizing process. As shown in figure 1, the sterilization chambers 1 and 2 may preferably be reciprocally distinct, even if they are disposed in succession, to constitute a tunnel inside which the packages 20 pass in succession, moved by the conveyor belt 11. In fact, each packages 20 is firstly carried from the entrance to the exit of the first sterilization chamber 1 , inside which the heat produced by appropriate means for its generation, for example a plurality of electric resistances 6 and a fan 7, causes at least partially the death of the bacteria, mildews and fungi being present on the footwear 10 and inside the package 20, during the sterilizing step. Then the package 20 is carried from the entrance to the exit of the second sterilization chamber 2, inside which the ultraviolet rays produced by the plurality of LIV lamps 8 will remove the bacteria, mildews and fungi still present on the package 20 and in the footwear 10 contained therein. Afterwards, said sealing step is caπied out by a sealing device 16 preparing the packages 20 for stocking and transportation, preserving them from further contaminants. The sealing device is disposed upstream of the second chamber 2 and applies a film or a heat-sealed bag 22 over the packages 20 moved by the conveyor belt 11. Referring to the method steps before described, it will be evident for a person skilled in the art that the essential steps of the sterilizing method according to the present invention are two, that is to sayj the step wherein the footwear are carried from the entrance to the exit of the sterilization chamber, or chambers, and the step for sterilizing the footwear by heat and ultraviolet rays inside the sterilization chamber, or chambers. It has to be noticed as well that the translation motion of the conveyor belt 11 may be also temporarily stopped by a controller, when the package 20 is inside one of the sterilization chambers in such a way to increase the permanence period therein and thereby improving the bactericide effect of the sterilizing step. Further, as will be evident to a person skilled in the art, the sterilization chambers may be shaped in a different way from that herein described, without for this reason come out from the scope of protection of the present invention. For example, in a further possible embodiment, the sterilization chambers may have one opening only, allowing both entrance and exit of the footwear, and they can be disposed in overlapped or side by side relation. In this embodiment, the device for carrying the footwear from the entrance to the exit of the sterilization chambers, may be composed of a robot provided with a mechanical arm moving the footwear, or the packages housing them, into and outward the opening with which each chamber is provided, providing a permanence period therein for carrying out the sterilizing step. Figure 4 shows a further possible embodiment of the apparatus according to the present invention differing from that before described referring to figure 1 , because it is provided with further means for delivering 250 a sanitizing liquid or fluid, to further improve the effectiveness of the sterilization of the footwear. These means for delivering the sanitizing liquid or fluid 250, such a liquid or fluid being preferably composed by a fungicidal (antimycotic), bactericide or similar liquid, are accommodated inside a third sterilization chamber 200, distinct and disposed in succession relatively to the sterilization chamber 1 and 2, inside which the means for generating heat 4 and means for generating ultraviolet rays 5 are placed respectively. As can be seen in figure 4, the means for delivering the liquid 250 comprises a plurality of nozzles 251 , whereby the liquid is preferably atomized in the sanitizing chamber 200 wherein the footwear 10 are moved by the carrying device 3. The atomized, or anyway delivered, liquid is then removed by the sanitizing chamber 200 by one or more aspirators 252.

It has to be observed that the carrying device is conveniently shaped for carrying the footwear from the entrance of the first sterilization chamber 1 to the exit of the afore said sanitizing chamber 200, without interruption.

Obviously, the means for delivering the sanitizing liquid or fluid 250 may be disposed inside said two other sterilization chambers 1 and 2, without the need of a distinct chamber intended exclusively for the liquid delivering (or atomizing).