Household appliance, particularly a refrigeration apparatus, with a control system using sensor means based on RFID technology

0001The present invention relates to a household appliance having an electronic control system and sensor means for detecting one or more physical quantities.

0002Household appliances control systems require, as every other kind of control system, proper sensors for detecting the value of physical quantities to be controlled, and the result of their action is more effective, as greater is the number and the quality of the used sensors. The use of a proper number of sensors, however, is often limited especially by their cost, which in the case of household appliances represents an important bond to be respected.

0003By analyzing the cost components associated with a generic sensor for household appliances (such as a temperature, water level, pressure, humidity, ice, smells, etc. sensor) it is noted that most of the cost is to be assigned not so much to the sensitive element, namely the real sensor, as to the container and the wiring thereof. In order to better explain this aspect, it can be considered the case of control systems and sensors concerning the equipments sector for the home refrigeration. In this case, the used sensors which are mainly dedicated to the temperature detection within the different compartments assigned to the preservation of different kinds of food, typically consist of three main parts, as diagrammatically pointed out in figure 1: <ul id="ul0001" list-style="dash" compact="compact"><li>a sensitive element 1 detecting the temperature value,</li><li>a plastic shell 2 in which the sensitive element 1 is tightly encapsulated by an appropriate protective resin 3,</li><li>a cable connecting the sensitive element to the control system of the household appliance.</li></ul>

0004The temperature-sensitive element 1 can be embodied with different technologies, but the sensor type usually used in the household appliances sector consists of a NTC-like thermistor, that is a non linear economical resistor obtained by mixing proper oxides, the resistance of which varies in a reverse way with the room temperature in which it is placed. The cable connecting the sensitive element 1 to the control system typically consists of two wires 4 which end with a proper connector 5; in applications in which, for electrical safety reasons, a strengthened galvanic insulation is requested, the two-wires cable 4 is further protected with an appropriate insulating sheath 6.

0005The number of temperature sensors used for home refrigerators and/or freezers depends on the complexity of the same and, in particular, on the numbers of compartments with a different temperature to be controlled. This temperature sensor number usually changes from a minimum of one unit to a maximum of five or six units; a further increase of this number, although it should be desirable in the case of complex products, is prevented by the typical limits of the present technology. These limits mainly concern the following three aspects: the cost, the wiring and connections complexity, the difficult in placing each sensor within the household appliance. The sensor cost is of the order of one Euro (a non negligible value for the household appliances sector) and does not concern so much the sensitive element 1, which usually does not exceed 10 Euro cents, as rather the air tight container 2-3 of the sensitive element 1 and the connecting means 4-6 of the same with the control system. The wiring and connections complexity is due to the fact that each sensor requires an own supply cable 4, 6 and an own connector 5, as the possible consolidation in a single wiring should result difficult to handle during the product assembly, the different sensors usually being placed in positions rather far therebetween. It is also to be considered that in the case, for instance, of home refrigerators, the length L1 between the connector and the shell 2 of the sensitive element may be up to 2-2,5 meters. The positioning difficulty depends on that cables 4, 6 associated with each sensor must be suitably integrated within the refrigerator body, for ensuring a suitable protection and meeting the aesthetical requirements associated with this kind of product. Such integration is typically carried out by the aid of appropriate cable troughs, wherein the temperature sensors and the respective wirings are inserted, and such cable troughs are generally obtained by integrating proper sheaths within the refrigerator walls. Consequently, with the increasing number of the temperature sensors, also the cable troughs needed for their positioning are increasing, and this involves an obvious rise of assembly times and costs of the product and a total decrease of the thermal insulation of the walls thereof, caused by the tunnel passages of the different temperature probes, which render less homogeneous the polyurethane foam typically used as insulating material, by increasing thermal dispersions in the surroundings.

0006Remarks like those above mentioned further apply to other types of sensors, which are usually used in the household appliances sector.

0007The present invention intends to overcome the aforesaid prior art limits, for improving the overall performances of an household appliance, particularly a refrigeration apparatus, by reducing its cost and simplifying at the same time the manufacturing and use procedures thereof.

0008This and other purposes are achieved, according to the present invention, by a household appliance having the features of the appended claims, which are to be intended as an integral part of the present invention.

0009Further aims, features and advantages of the invention will become apparent from the following description with reference to the enclosed drawings, which are given as not limitative example, wherein: <ul id="ul0002" list-style="dash" compact="compact"><li>figure <b>1</b> diagrammatically shows a temperature sensor of a known type, typically used in the home refrigerators sector;</li><li>figure <b>2</b> diagrammatically shows a household appliance carried out according to the invention;</li><li>figure <b>3</b> diagrammatically shows a first type transponder, equipped with read/write memory by an external antenna, used for a particularly advantageous implementation of the invention;</li><li>figure <b>4</b> diagrammatically shows a second type transponder, used in the basic implementation of the present invention, equipped with sensor means capable of measuring a determined quantity and sending this value to an external antenna;</li><li>figure <b>5</b> diagrammatically shows the layout of a sensor device which, according to the invention, can advantageously replace the sensor of figure 1 in the same application;</li><li>figure <b>6</b> shows a possible block diagram of a control system for household appliances according to the invention;</li><li>figure <b>7</b> diagrammatically shows a particularly advantageous application of the present invention.</li></ul>

0010According to the invention, it is proposed a household appliance equipped with a control system which uses at least one sensor device lacking of wiring, equipped with at least one physical quantity-sensitive element and a proper local control electronics, which supply is obtained from the energy irradiated by an external transceiver antenna.

0011According to the invention, the aforesaid local control electronics is carried out using the known transponders technology (RFID technology), that is radio-frequency electronic devices without an autonomous supply, which are well known per se and do not need a detailed description herein.

0012For the purposes of the invention, in fact, it suffices to remember that a transponder is an electronic device provided with a nonvolatile memory and proper means allowing an external apparatus to read and write data within said memory through a radio-frequency communication system; moreover, not having typically an autonomous supply system, said device takes its supply voltage by drawing energy from the same electromagnetic field used by the transceiver external apparatus connected therewith.

0013The use of transponders has already been proposed in the household appliances sector, but with different implementation and aims with respect to the present invention. In particular, EP-A-0 911 710 discloses a process for treating clothes in a washing-machine, wherein the clothes to be washed are provided with a product information containing-transponder (for instance the kind of fabric, colour and weight thereof, recommended washing parameters and so on) which are read, when each cloth is introduced in the washing-machine, by a proper radio-frequency reading device placed near the inlet opening of the machine.

0014In figure 2, a household appliance carried out according to the invention, in the specific case a refrigerator, is indicated by 10. The main feature of the control system of the household appliance 10 is represented by the presence of "transponder sensors" TS, TS', provided with one or more physical quantity sensitive elements and used for controlling the functionality of the household appliance, wherein the information generated by said sensors may be "read" by a suitable reader device, in the following designated by 11. Said reader device 11 is preferably able to simultaneously read transponders TM as well, provided with a memory containing useful information concerning the optimal procedures for treating the consumer material or, more generally, the item or product on which the action of the household appliance 10 is carried on (foods, drinks, fabric items, etc.), the transponders TM being suitably associated with such items, for instance in the form of labels.

0015The reading of the information associated with the above said two types of transponders TS, TM is carried out with procedures per se known, by means of one or more antenna 12, properly placed within the household appliance 10 and connected with the electronic control system of the same; the communication standard associated with the two types of transponders TS, TM is preferably the same, for example any one of those now available or which can be developed in the future. In the preferred embodiment of the present invention, relating to refrigerators and/or freezers, both the two kinds of transponders TS, TM use ISO-15693 standard, already adopted by various transponder manufacturers, such as Philips, Texas Instruments, Fujitsu, Hitachi, Motorola.

0016A non limitative example of the architecture of the transponder TM possibly associated with the consumer material treated by the household appliance 10 is illustrated in detail in figure 3, in which the block 21 represents the principle diagram, known per se, of the circuit with which the supply voltage of the local electronics is generated by drawing energy from the magnetic field associated with a carrier F1 of the signal irradiated by a transceiver antenna 12 of the aforesaid reader 11: this occurs by rectifying with a proper diode D the alternating current, which is induced by the Faraday's law upon the coil L by the said carrier F1 received through an antenna 20 of the transponder TM, and by charging with this current an appropriate capacitor C. The modulation signal of the carrier F1, transmitted by the external antenna 12 and received by the antenna 20 of the transponder TM, is opportunely obtained by a receiver 22 and decoded by a decoder 23 in such a way that the transponder control logic may carry out possible writing operations through writing means 24, or reading operations through reading means 25, concerning a nonvolatile memory M.

0017The control logic of the transponder TM is capable as well, in turn, to selectively transmit, by a transmitter 26 through the same antenna 20, the data contained in the memory M, through the proper modulation of a second carrier F2 that the reader 11 is able to receive through the antenna 12 thereof.

0018The architecture of the transponder sensor TS, illustrated in figure 4, is substantially the same than the transponders TM, except that it is characterized by a more sophisticated control logic, based on a small low consumption micro-controller MC or upon an equivalent dedicated control logic (ASIC), by a measuring device 27 including one or more sensitive elements S and by a nonvolatile memory M which, in addition to the data received through the antenna 20, may also contain the values generated by the measuring device 27.

0019In figure 5, a possible physical layout of a transponder sensor TS or TS' is diagrammatically represented, relating to the preferred embodiment of the invention concerning the control systems for refrigerators and freezer.

0020This transponder sensor TS, which has a sensitive element S for detecting the room temperature in which it is placed, has very reduced dimensions (typically in the order of 2-3 cm²) with regards to a temperature probe such as that of figure 1, and does not need any wiring toward the control system of the household appliance 10. The same also applies in the case in which the physical quantity detected by the sensitive element S of the transponder TS is different from the temperature, being for instance humidity, thickness of ice accumulated upon the internal wall of the refrigerator, smells, etc.

0021The control electronics 28 (represented by blocks 21-26, MC and M of figure 4), the antenna 20 and the sensitive element S are incorporated within a proper protective membrane 29, according to known transponder industrialization techniques.

0022In a preferred embodiment of the invention, at least one of the transponder sensors TS, namely the one indicated by TS' in figure 2, is opportunely positioned in the household appliance 10 in order to detect information concerning the outside environment (such as, for instance, the room temperature and/or air moisture value) in which it is operating; furthermore, this transponder sensor TS' can have advantageously a nonvolatile memory M which can be read and written through an electromagnetic field by a unit being external to the household appliance 10 as well, for favouring the logistic management and the technical assistance thereof on place and finally the manufacturer identification, for a proper disposal at the end of the service life, as described below.

0023The information supplied by the transponder sensors TS, TS' resulting from detections executed through the respective sensitive elements S are used for managing, with procedures per se known, the functionality of the household appliance 10.

0024The information supplied by the transponder TM, associated with the items or materials treated by the household appliance (such as foods or drinks in case of refrigerators and freezers, foods and dishes in case of ovens, fabric clothes in case of washing-machine, etc.) are instead used for improving the treatment itself by the household appliance, and facilitating the use by the user (for instance: setting or correction of parameters of a washing program, alarm emission with the approaching of the expiry date of a preserved food, etc.), also in this case with known procedures.

0025Positioning of the transponder sensors TS can be associated with fixed elements belonging to the household appliance body, for instance walls, fixed support shelves, inner spaces. In a particularly advantageous embodiment, sensors TS are associated with moving elements of the household appliance, such as removable support shelves of refrigerators and ovens, "ball" shaped movable dispenser of washing-machine detergents and so on; in this case, in fact, the lacking of wirings allows a transponder sensor to detect the value of the respective physical quantity exactly in the point or place in which one wishes to detect it, in order to optimize the household appliance control.

0026In the case exemplified in figure 2, concerning a refrigeration home apparatus, it can be seen for this purpose: <ul id="ul0003" list-style="dash" compact="compact"><li>the transceiver antenna 12 used for the dialog with the transponders TS, TS', TM;</li><li>first transponder sensors TS provided with a temperature sensitive element, or possibly sensitive to an other physical quantity typical of a refrigeration apparatus, inserted within the walls of the refrigerator 10 and within the fixed support shelf 10A of the cabinet of this latter;</li><li>second transponder sensors TS provided with a temperature sensitive element, or possibly sensitive to an other physical quantity typical of a refrigeration apparatus, inserted within the movable support shelf 10B of the cabinet;</li><li>a transponder sensor TS', whose sensitive element/s are measuring the outside environment temperature and/or humidity;</li><li>transponders TM associated with preserved food packages, placed for example upon containers 10C of the refrigerator 10 or upon the inner shelves thereof. Transponders TM can be associated, for example, in the form of labels, directly to the items or materials used in the household appliance.</li></ul>

0027Figure 6, which diagrammatically represents a control system according to the invention, points out three main blocks: <ul id="ul0004" list-style="dash" compact="compact"><li>block SC, describing the real control system of the household appliance 10;</li><li>block TSn, generally representing the ensemble of the transponder sensors TS (TS1, TS2,...TS') stably associated with the household appliance 10, and</li><li>block TMn, generally representing the ensemble of the transponders TM (TM1, TM2,...) possibly associated with the consumer goods to be treated by the household appliance 10.</li></ul>

0028The control system SC is based on the use of a micro-controller MC1 which manages, through a proper interface UI equipped with buttons and/or knobs and/or numerical o graphic displays, the dialog with the user and which controls by way of proper actuators D1, D2, ...Dn, consisting of mechanical and/or electronic relays (triac), the different electrical loads L1, L2, ... Ln of the household appliance which are fed by the mains voltage Vac. The micro-controller MC1 then controls the transponder reader means consisting of the reader 11 and the respective antenna 12.

0029In the control system SC, the micro-controller MC manages the operation of the household appliance 10 according to information generated by the means S belonging to the transponder sensors TS, in addition to information possibly arising from traditional sensors (not represented). As above-mentioned, at least one among these sensor means, that is the one associated with the transponder sensor TS', is able to detect the value of one or more physical quantities related to the outside environment (such as temperature, humidity, etc.). Sensor means 11, 12 within the household appliance 10 are also provided for reading/writing the content of the memories M of the transponders TM possibly associated with the consumer material treated by the household appliance 10.

0030The preferred embodiment of the present invention refers to the control systems for home refrigeration apparatus, such as refrigerators and freezers.

0031A first advantage of this embodiment according to the invention is that conventional temperature sensors, represented by temperature probes (figure 1) with different length and hard positioning, are replaced with wireless sensors TS, TS', which are less expensive and can be easily positioned within the inner walls of the household appliance and within the moving shelves thereof as well, so allowing a more effective temperature control at the different inner zones of the household appliance.

0032A second advantage is that, according to the invention, at least one TS'-like transponder sensor, with one or more sensitive elements S therein, is placed in such a way that the value of one or more physical quantities outside the refrigerator can be detected, such as the outside environment temperature and humidity.

0033Finally, a third advantage according to the invention is that the antenna 12 used for the dialog with the sensors TS is also able to read the content of the memory M of the transponders TM, possibly associated with the food packages being stored, by using a same communication standard.

0034In figure 7 there is diagrammatically illustrated a possible, particularly advantageous alternative embodiment of the invention. According to this variation, the transponder sensor TS' is located in such a way that its inner memory M can be read and written, in addition to the above-mentioned reader means 11 and 12 within the household appliance, by appropriate external means, represented by a reader 11' equipped with a respective antenna 12' and belonging to an external electronic device DE, provided for managing complementary functions. In this way, the transponder sensor TS' is able to dialog both with the control system SC of the household appliance 10, through the reader 11 and the antenna 12, and with the outside represented by the device DE, through the reader 11' and the antenna 12', in order to carry out the following functions: <ul id="ul0005" list-style="dash" compact="compact"><li>logistic functions, concerning the sorting and the drawing ability of the household appliance, for instance during the productive and storage steps, based on the known concept of "electronic bar code", typically associated with the transponder devices;</li><li>maintenance and technical assistance functions of the household appliance, concerning the possibility of leaving a trace, e.g. within the memory M of the sensor TS' (shared between the control system SC and appropriate external devices DE), concerning the mistory of the different maintenance operation;</li><li>aid functions for the proper disposal of the household appliance at the end of its service life, based on the possibility of exploiting appropriate information, initially stored, for instance, within the memory M of the transponder TS', concerning the manufacturer, used materials and their recycling degree.</li></ul>