FIELD OF THE INVENTION

The present invention refers to a removable signalling device of the exhaustion of a dispenser/dif fuser of liquid active substances , i . e . , a stand-alone acces sory which can be easily applied to the body of a dispenser/dif fuser of liquid active substances , and which is apt to send a warning signal when the reserve of liquid active substance inside said dispenser/dif fuser is exhausted . STATE OF THE PRIOR ART

The indoor use of dispensers /dif fusers of liquid active substances , whether by evaporation at room temperature or by heating, is now widespread, such liquid active substances having for example , a repellent ef fect against harmful insects , or a perfuming effect to eliminate bad smells .

Current dispensers/dif fusers of liquid active substances are prolonged run time appliances , which work autonomously from a minimum of a few days up to a maximum of about three months - and more rarely even beyond - depending on the distinct types . Furthermore, the effective useful life of every single appliance obviously depends on the conditions of temperature and humidity in the installation site , which can promote or slow down the evaporation of the liquid active substance , and, finally, on any discontinuous use of the appliance itself . A currently available dispenser/dif fuser typical drawback is therefore that it is not pos sible to exactly figure out their service life but only as sess it by periodically detecting the actual presence of residual liquid active substance in the container of said dispensers/dif fusers .

However, such outwardly trivial operation, is not easy to carry out because such appliances are often placed in inaccessible positions , to hide them from view, or inserted into an electrical socket near the floor, and thus a direct examination of the amount of liquid active substance still present in the container is inconvenient and requires a minimum waste of time . Thus , it frequently happens that the residual amount of liquid active substance in the container is only rarely checked in practical use, leading to a user finding himself noticing that the appliance no longer works , and consequently recharging it with a fresh reserve of liquid active substance only when the device itself has already ceased it s function for several days or even weeks .

The need has long been felt in the field for a more ef fective end-of-life indicator which could be more promptly detected by a user, and for this reason various solutions have already been provided in the known art for detecting and signalling - through electronic means - the complete consumption of the liquid active substance of a dispenser/dif fuser of such substance .

WO-2007 / 138247 ( 2007 ) , EP-1985316 ( 2008 ) and US-8857731 disclose diverse types of dispensers /dif fusers of liquid active substances comprising an emitter and a receiver of light or electrical signals . Such emitter and receiver mutually communicate to first determine whether a container of liquid active substance is installed on the dispenser/dif fuser, and subsequently whether a liquid active substance is contained in the same .

However, the above indicated known solutions necessarily require to completely redesign the device by integrating an intrusive emitter and receiver inside the device and/or the refill, which makes these components more expensive and requires that the user wishing to take advantage of such technological improvement discards the device already in use and buy a new one .

The technical problem addressed by the present invention is therefore that of providing a signalling device of the exhaustion of a liquid active substance inside a dispenser/dif fuser, which can be easily removably combined with any such appliance already present on the market , such device being also apt to detect the exhaustion of a liquid active substance in a respective container of the appliance in use , and to timely and effectively notify the user of such exhaustion .

Within this problem, a first obj ect of the invention is to provide a signalling device of this type which can be stably coupled with the dispenser/dif fuser whose content of liquid active substance is to be monitored, said coupling being quick and easy to accomplish without the need to use any additional fastening means or device .

A second obj ect of the invention is then to provide a signalling device as above, which does not need any electrical connection to the coupled dispenser/dif fuser . SUMMARY OF THE INVENTION

This problem is solved, and these ob ject s achieved, by means of a removable signalling device of the exhaustion of a liquid active substance inside a dispenser/dif fuser thereof , having the features defined in claim 1 . Other preferred features of said removable signalling device are defined in the secondary claims . BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the removable signalling device according to the present invention will anyhow become better evident from the following detailed description of a preferred embodiment of the same, given by mere way of non-limiting example and illustrated in the accompanying drawings , wherein :

Fig . 1 is a perspective view of the removable signalling device of the present invention;

Fig . 2 is a perspective view of the removable signalling device of Fig . 1 coupled to a dispenser/dif fuser appliance;

Fig . 3 is a front view of the coupled removable signalling device of Fig . 2 ; and

Fig . 4 is a side view of the coupled removable signalling device of Fig . 2 .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

According to the present invention, to solve the problem highlighted above by means of a structurally simple and immediately applicable solution, the removable signalling device consists of a self-standing and self-powered acces sory apt to stably engage with a dispenser/dif fuser of liquid active substances . Furthermore , the removable signalling device has no electrical connection to the dispenser/dif fuser nor, preferably, separate mechanical connecting means thereto, and is provided both with detection means for detecting the end of the useful life of the liquid active substance reserve of the dispenser/dif fuser, and with signalling means for signalling to the user the exhaustion of the liquid active substance in the respective container .

Preferably, the dispenser/dif fuser of liquid active substances is an appliance with a deodorizing or insecticidal effect , however, the present invention is aimed at detecting the exhaustion of any liquid active substance , regardless of the type of said substance and of the use such substance is intended for . It is therefore clear that the removable signalling device of the present invention can be used with any consumable liquid active substance and, more in general , with any appliance having a container filled with a gradually depleting liquid, whose exhaustion must be monitored .

With reference now to the specific embodiment of the removable signalling device of the invention illustrated in the drawings , it can be noted in Fig . 1 that such removable signalling device consist s of a central body 1 which extends into two opposing elastic lateral arms 2 on both sides and into an appendix 3 in its lower part .

Preferably, the removable signalling device of the invention is made by inj ection moulding of a suitable plastic material , and the arms 2 are C- or U-shaped and suf ficiently extended and thin to acquire a shape elasticity which allows a stable elastic snap coupling of said removable signalling device on the dispenser/dif- fuser D . In particular, the arms 2 preferably surround more than half of the dispenser/dif fuser D , while the appendix 3 extends alongside the container C of liquid active substance, as clearly shown in Fig . 4 .

Preferably, the arms 2 have such a shape as to also allow a precise and well-defined positioning of the removable signalling device onto the dispenser/dif fuser D , so that a liquid sensor 4 applied to the inner wall of the appendix 3 , hence facing the container C, is arranged in a position corresponding to the area wherein the liquid active substance contained in the container C can be measured for the last time . For example, the arms 2 can be provided with an internal rib which corresponds to an existing groove on the dispenser/dif fuser D .

However, since the removable signalling device of the invention must be used on any appliances D already existing on the market , and which therefore have been designed without providing for the use of such a type of signalling device, it is very likely that the dispenser/dif fuser D does not show any special feature for an easy positioning thereon of the removable signalling device of the invention . Such device must therefore fit to the already existing intrinsic features of the appliance in use . However, since many dispensers/dif fusers currently available on the market consist of an upper housing and a lower housing, a satis factory opportunity is to make use of the parting line between the upper and the lower housing as a groove for positioning the removable signalling device of the invention .

The liquid sensor 4 , apt to detect the presence/absence of liquid active substance in the container 3 , can be made by using various technologies , per se already well known to those skilled in the art , and is controlled by a microprocessor according to a predefined automatic routine . In a preferred embodiment , the liquid sensor 4 detect s the liquid level by detecting the electrical capacity of the assembly consisting of the walls of the container C and the liquid active substance contained therein or, alternatively, the electrical capacity of the same container C with no liquid active substance therein, i . e . , full of air .

Once the liquid sensor 4 detects the exhaustion of the liquid active substance, the control microproces sor sends a warning signal to the user . This signal can be , for example , a bright visual signal, such as a lit LED at the warning light 5 , or an audio signal, or any other type of signal which can be received and understood by a user . For example, the signal can be a notification to a smart device , such as a user ' s smartphone, and the communication can preferably occur via the BLUETOOTH transmission protocol .

The removable signalling device of the present invention is autonomously powered by a button cell . To save the battery energy, and thus extend the removable signalling device useful life , detection by the liquid sensor 4 is not made continuously but at regular intervals , which are separated by preset lengths of time wherein the liquid sensor 4 is not active . Ideally, such length of time wherein the liquid sensor 4 is not active equals the time needed by the wick of the dispenser/dif fuser D to completely clear itself of the liquid active substance , after there is no more liquid active substance visible in the container C; depending on the appliance D model, such length of time varies from 2 to 24 hours .

Every time the liquid sensor 4 performs a " sampling" of the detected signal, it uses a portion of the battery energy to perform the following operations : a . waking up the microproces sor; b . activating the liquid sensor 4 ; c . recording the reading from the liquid sensor 4 ; d . checking whether the afore-mentioned signal reading, based on a specific algorithm, defines the refill as exhausted;

1 . if YES, sending a predefined warning signal to the user;

2 . if NO, updating the system clock to the next microprocessor wake-up operation .

In an alternative embodiment , the removable signalling device of the invention consists of two elements which can mutually slide onto each other, so that the appendix 3 position, and hence that of the liquid sensor 4 , can be adjusted with respect to the central body 1 and the lateral arms 2 . In such embodiment , the liquid sensor 4 position can be more easily adapted to several types of dispenser/dif fuser D and container C .

From the foregoing description it is evident how the removable signalling device of the present invention has fully achieved the intended ob jects , in a particularly effective way . Said removable signalling device can be easily snapped onto the dis- penser/dif fuser D where it remains steadily fixed by the elastic arms 2 which cooperate with the same, whilst the self-powered liquid sensor 4 provides a visible/audible or directly readable signal as a direct notification on a user ' s smartphone via Bluetooth connection . The removable signalling device according to the present invention is therefore operatively fully independent from the dispenser/dif fuser D and can be easily reused on several types of dispenser/dif fuser D , according to the user ' s needs . However, it is understood that the invention should not be considered as limited to the specific arrangement s illustrated above , which are only exemplary embodiment s thereof , but that dif ferent variants are pos sible, all within the reach of a person skilled in the art , without thereby departing from the scope of protection of the invention it self , which is only defined by the following claims .