MODULAR DISPLAY STRUCTURE FOR PRESERVING OBJECTS IN A PROTECTIVE ATMOSPHERE The present invention relates to a modular display structure for preserving objects in a protective atmosphere. As is known, in order to ensure the risk-free display and the preservation of works of art and of many objects of symbolic value, such as for example relics or archaeological finds, and in any case objects that require a particular protective atmosphere, caskets, display cases or showcase are used very often in museums or in exhibitions. In particular, when those objects have to be preserved in very specific protective atmospheric and climate conditions, they are placed in display apparatuses normally provided with a passive system, with appropriate salts that interact with the air, that is inevitably exchanged with the outside, attempting to keep its relative humidity constant at least until external influences, due to the opening actions, exhaust the effectiveness of the salts. The best currently available display systems are also provided with refrigeration units for keeping the temperature at values that are as constant as possible. However, those apparatuses have several problems linked in particular to the exhaustion of the effectiveness of the salts in a more or less short time and therefore to the impossibility to keep the relative humidity constant for long periods, unless the exhausted salts are continuously replaced with new saturated salts. As a consequence of the exhaustion of the effectiveness of the salts, the conditioning unit, if provided, also decreases in effectiveness, and in any case it is not possible to provide an ad-hoc protective atmosphere for preserving objects. An aim of the present invention is to solve the problems described above, by providing a modular display structure that allows to preserve works of arts and valuable objects in very specific protective atmospheric and climate conditions, that are kept constant. An object of the invention is to provide a modular display structure that can minimize the influence of the conditions outside the display structure on the conditions created and maintained inside it, and to allow monitoring and control of all the internal climate
and atmospheric parameters. A further object of the invention is to provide a modular display structure in which the individual display cases can be connected in a network, thus allowing an advantageous installation thereof in museums, fairs, shows and similar exhibitions. The above aim and those and other objects that will become better apparent hereinafter are achieved by a modular display structure for preserving objects in a protective atmosphere, comprising a main structure provided with at least one portion made of transparent material, characterized in that it comprises at least one hermetic display chamber, the hermetic display chamber being formed by the main structure and by the portion made of transparent material, the atmosphere inside the hermetic display chamber being adjusted by an atmosphere monitor and control means. Further characteristics and advantages will become better apparent from the following detailed description of two preferred but not exclusive embodiments of modular display structures according to the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein: Figure 1 is a perspective view of the modular display structure according to the invention; Figure 2 is a sectional view, taken along the line Il-ll of Figure 1, of the modular display structure during its operation; Figure 3 is a sectional view, taken along the line Ill-Ill of Figure 1 , of the modular display structure during its operation; Figure 4 is a block diagram of a first embodiment of a network of connected modular display structures; Figure 5 is a block diagram of a second embodiment of the network of connected modular display structures; Figure 6 is a perspective view of the modular display structure according to a further aspect of the invention; Figure 7 is a sectional view, taken along the line VII-VII of Figure 6, of the modular display structure during its operation; Figure 8 is a sectional view, taken along the line VIII-VIII of Figure 6, of the modular
display structure during its operation. With reference to the cited figures, a modular display structure according to the invention, generally designated by the reference numeral 1 , comprises a main structure 2 provided with at least one portion 3 made of transparent material. The portion 3 made of transparent material is generally shaped so as to constitute a casket or showcase and is provided with a sealing means 5, which is preferably constituted by gaskets. According to the invention, the main structure 2 has a hermetic display chamber 6, which is constituted by the portion 3 made of transparent material and by a hermetic containment tray 4, formed by the main structure 2, between which the sealing means 5 is interposed. An object 8 is generally placed for display on a support 7 inside the hermetic display chamber 6. A computer 9, preferably constituted by a PLC or by any other microprocessor system which collects data provided by a sensor 10 for detecting the partial pressure of the oxygen, by the temperature sensor 11 and by a humidity sensor 12, constitutes, together with a central analyzer 27, an integral part of an atmosphere monitor and control means provided in the modular display structure. The atmosphere monitor and control means also comprises a pressure compensation means, generally designated by the reference numeral 13, which includes a compensation chamber 16 and a safety valve 17 against negative pressures and overpressures, which is preferably set to a pressure of approximately 20 millimeters H2O
(20 millimeters of water head) and is connected to the hermetic containment tray 4 in order to discharge overpressures and negative pressures, between the inside of the hermetic display chamber 6 and the surrounding environment, that exceed the set value. The compensation chamber 16, made of impermeable and deformable material and preferably shaped like a bag, is connected to the hermetic containment tank 4 in order to compensate for variations in pressure between the inside and the outside by changing its volume. The main structure 2 includes a temperature adjustment means, generally designated
by the reference numeral 14, and a humidity adjustment means, generally designated by the reference numeral 15, which once again constitute an atmosphere monitor and control means. The temperature adjustment means 14 includes a refrigeration unit 18 having a condensing unit 19 contained in the main structure 2 and an evaporator 20 arranged inside the hermetic display chamber 6. A ventilation system 21 arranged below the evaporator 20 allows an optimum distribution of the cold, by directing the air streams that interact with the evaporator 20 towards the heat exchange walls of the hermetic display chamber 6, as shown in Figures 2 and 3. The modular display structure is completed by the humidity adjustment means 15, which is constituted first of all by a tank of pre-adjusted salts 22, which is affected directly by the air stream produced by the ventilation system 21 , and by an external active system for rehydrating the salts, which is useful if the salts are exhausted. In a first embodiment of the modular display structure, shown schematically in Figure
4, the salt rehydration system includes a remote humidifier 23 which restores the amount of water lost by the salts by supplying a mixture of gas to each compartment. The gas mixture is humidified by passing through the remote humidifier. In a second embodiment of the modular display structure, shown schematically in Figure 5 and particularly suitable in the case of very large hermetic display chambers, the salt rehydration system includes a water supply system 24 which directly supplies small amounts of water to the salts of each tank of pre-adjusted salts 22. A nitrogen tank 25, connected to each hermetic display chamber 6, is connected to a nitrogen generator 26, which is controlled by the computer 9 or by a central analyzer 27. The operation of the modular display structure according to the invention is as follows. The object 8, for example an archaeologic find, to be exhibited and preserved, is arranged on the support 7 contained inside the hermetic display chamber 6, which is obtained by joining, by the sealing means 5, the portion 3 made of transparent material to the hermetic containment tank 4.
The pressure compensation means 13 compensates for the pressure gradient that occurs between the inside of the hermetic display chamber 6 and the surrounding environment, preventing the external atmosphere from penetrating inside and altering the characteristics of the generated protective atmosphere and in practice making the modular display structure ineffective in preserving the objects. In particular, the compensation chamber 16 is adapted to compensate for pressure variations between the inside and the outside by modifying its volume, while in the case of sudden pressure variations that the compensation chamber is unable to absorb, and which might damage the modular display structure due to the intensity of the gradient, the safety valve 17 against negative pressures and overpressures is activated. Heat exchange between the inside and the outside of the hermetic display chamber
6, which is caused by the difference in temperature between the two environments and is mainly concentrated, as is normal, on the portion 3 made of transparent material and on the walls of the hermetic containment tank 4, is adjusted by the temperature adjustment means 14. The refrigeration unit 18 lowers the temperature inside the hermetic display chamber
6 by means of the evaporator 20, whose action is increased in effectiveness by the ventilation system 21 which directs the air that passes through the evaporator 20 towards the heat exchange walls, also preventing any interference with the atmosphere around the find 8 as much as possible. This refinement allows to contrast to the effects of the difference in temperature between the inside and the outside of the hermetic display chamber 6 directly on the heat exchange walls, as shown in Figures 2 and 3, away from the find 8, which accordingly benefits from a microclimate that is kept, as statically as possible, close to the intended values. Controlling and maintaining a given rate of relative humidity of the atmosphere inside the display hermetic display chamber 6 is entrusted to the humidity adjustment means
15 which, by means of the tank of pre-adjusted salts 22, keeps the relative humidity inside the closed environment constant, even if the temperature of the environment changes significantly.
The ventilation system 21 makes the air stream pass directly through the tank of pre- adjusted salts 22 before directing it toward the evaporator 20 of the refrigeration system 18. Assuming that the portion 3 made of transparent material is certainly removed periodically, it is necessary to take into account the fact that the tank of pre-adjusted salts 22 dehydrates, releasing its moisture over a period of time that is difficult to estimate. Therefore, the moisture must periodically be restored either by replacing the salts or by providing the salts with small amounts of water by means of the external active salt rehydration system. According to a first solution that has been perfected and is shown in Figure 4, the remote humidifier 23 restores the lost amount of water, providing a mixture of moistened gas, every time it is necessary to also change the protective mixture of gases inside the hermetic display chambers. In this way it is possible to supply relatively modest amounts of water, giving time to the atmosphere inside the hermetic display chambers and to the humidity sensors to stabilize on the new values, as allowed by their inertia. A second embodiment of the modular display structure includes the presence of a water supply system 24, which directly supplies small amounts of water to the salts contained in the hermetic display chambers. All the operations are controlled by the computer 9 which collects the data by means of the oxygen partial pressure sensor 10, the temperature sensor 11 , and the humidity sensor 12, and is capable, depending on whether the modular display structure is isolated or is part of a network of connected modular display structures, as might occur in a museum, of actuating the various mechanisms adapted to maintain the protective atmosphere or to pass the data to the central analyzer 27, which manages the priority1 policies and the actuation times of the mechanisms assigned to maintain the protective atmosphere, and to communicate with an optional personal computer, not shown in the figures, for storing and subsequently optionally processing the stored history data. Controlling and maintaining the required atmospheric values requires the presence of the nitrogen generator 26, which accumulates nitrogen in the tank 25 and then
distributes it, under the control of the computer 9 or of the central analyzer 27, to all the modular display structures that are present. In practice it has been found that the modular display structure for preserving objects in a protective atmosphere according to the invention fully achieves the intended aim and objects, preserving works of art and valuable objects in very definite protective atmospheric and climate conditions, which are kept as constant as possible even as the external environmental conditions vary. The modular display structure thus conceived is susceptible of numerous modifications and variations, within the scope of the appended claims. All the details may be replaced with other technically equivalent elements. Figures 6-8 in fact illustrate a modular display structure according to a further aspect of the invention, generally designated by the reference 101 , in which the elements that are similar to the first embodiment are designated by the same reference numerals increased by 100. The structure 101 includes, in addition to what has been described for the structure 1 , a high-efficiency filter 150, such as EPA or ULPA, drawing air from the display case. The function of the filter 150 is to eliminate any fine and ultrafine dust that may be present in suspension in the atmosphere of the display system. The structure 101 includes an air sterilization module 151, which is arranged on the air output channel, as shown in Figure 6. The sterilization module includes a battery of LEDs that emit ultraviolet rays, particularly in the UVC band. The adoption of the sterilization module 151 and of the filter 150 allows to provide a display structure with total protection, in which in addition to conditioning and modifying the atmosphere to create the ideal preservation conditions, the preservation characteristics are further improved by eliminating the dust and the bacterial load dispersed in the air. In practice, the materials employed, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to requirements and to the state of the art.