As it is known, the mirrors used at the present time for the most different uses, such for example in the traffic signals disposed on the cross-roads of more roads, the private and public baths and the public places (restaurants etc..) and the like, are constituted by a rejecting surface of glass or plastic material in front of which the persons or arti- cles to be reflected are arranged. However, such mirror reflecting surface is subjected to the ambient conditions, which influence the visibility thereof in presence of high moi- sture rate, vapours, rain, ice and atmospheric precipitations of various kind (fog, snow etc.), wherein the air moisture condensates itself on the same surface, which consequen- tly is breathed and cannot more be visible.

These mirror breathing conditions are critical particularly in the case in which parabolic mirrors are employed for traffic signals. for example on the cross-roads which are dan- gerous for the considerable traffic since under these circumstances the mirrors aren't able to perform their displaying function, with consequent dangerous situation for the persons. The present invention has the object to eliminate the inconvenience of the mir- ror breathing, by means of the use of a new kind of anti-breathing mirror which is made in such a way as to avoid any formation of condensate, moisture, ice etc.. onto its outer surface, even at unfavourable ambient conditions, thereby permitting the visibility of the same surface thereof practically at any ambient condition.

This anti-breathing mirror is realized with the constructive characteristics hereinafter de-

described, with particular reference to the accompanying patent claims.

The invention will be understood better from the following description, given solely by way of not-limiting example and with reference to the accompanying drawings, wherein: -Fig. I shows a front view of the anti-breathing mirror according to the invention ; -Fig. 2 shows a partially cutaway side view of the mirror of Fig. I, -Fig. 3 shows the electric diagram of the anti-breathing electric circuit installed on the present mirror ; -Fig. 4 shows schematically a possible additional electric control means of the pre- sent anti-breathing mirror. in the Figures referred to it is represented schematically the anti-breathing mirror 5 ac- cording to the invention, which is realized in such a way as to avoid the formation of the condensate, moisture, ice etc.. onto its outer reflecting surface, even under unfavo- urable ambient conditions, for example in the case of rime, fog, rain. snow etc..., there- by permitting the visibility of the outer surface thereof practically at any ambient condi- tion. In particular, in the case referred to the mirror 5 is made of parabolic type, used for the traffic signals and fitted on a pole at a certain height so as to be able to display the surrounding roads, for example confluent to each other on a cross-road, however this mirror may be made obviously also with other forms and applied on different pla- ces, as for exan ; ple in the private and public baths, in the public places of various kind (restaurants, swimming-pools etc..), to perform the function of displaying the persons and articles which are placed in front thereto.

With reference to the Figs. 1 and 2, it is noted that the anti-breathing mirror is substan- tially constituted by a mirror plate 6 made of suitable reflecting material (glass or pla-

stic material, in the present case preferably of plastic material), which is shaped on the desired form and in the present case with parabolic circular form having the parabola bent outwards, in the mirror lateral direction, said plate being enclosed by a periphe- ral frame 7 having the same form thereof and made of plastic material, which as usual is joined at the upper side to a covering 8 provided at the level of the outer reflecting surface 9 of the mirror plate 6, and projected outwards from such surface so as to protect it at least partially from the atmospheric precipitations (rain, hail, snow etc..).

Moreover, the peripheral frame 7 is joined at its rear side to an inclined flat surface 10. with inclination convergent toward the rear part of said frame, and which in turn is joined to a tlat and vertical bottom surface I I provided with projected ribs (not in- dicated) for supporting two metallic brackets 13 with vertical extent, which can be ap- plied and fitted at a certain height from the ground around a vertical pole 14.

The mirror referred to is constituted also by at least a junction box 15 made of suita- ble plastic material, containing an electric circuit realized in the manner and for the pur- poses set forth below, which box is supported on the frame 7 by fixing it to the metal- lic brackets 13. In order to avoid the breathing of the outer reflecting surface 9 of the mirror plate 6, in accordance to the invention there are provided electric heating ele- ments 16 of adequate heating power, which are applied preferably into contact with the back surface 17 of such plate and realized as heating resistances of conventional type, and so shaped as to be suitably distributed for the size of this surface, and which are supplied through the electric circuit referred to.

The scope of the heating resistances is to determine a temperature increase of such back surface and, through thermal transmission through the thickness of the glass pla- te 6, also of the outer reflecting surface 9 of the same plate, with consequent evapo-

ration and removal of the condensate, moisture, ice etc.. being formed onto this outer surface at the unfavourable atmospheric conditions previously cited, and restoration of the displaying fuction of the mirror.

The heating resistances may be, solely by way of example, shaped with an undula- ted form, as evident from the Fig. 1, or also with different forms depending on the size and form of the mirror surface to be de-breathed and the needed heating po- wer. The above mentioned heating resistances are associated to at least a heating power regulating element, realized as an electric or electronic thermostat 18 of per se known type. applied preferably with its sensing element to the back surface 17 of the mirror plate 6 and connected adequately in the electric circuit of such heating re- sistances, in a manner to turn on and off them repeatedly depending on the temperatu- re respectively attained on the mirror plate at the different ambient conditions.

This thermostat 18 is so calibrated as to turn the heating elements on in presence of a reduced value of temperature of the plate 6, which is comprised normally between 0° and + 1° C in case of parabolic mirror, and off when a determinate maximum tempera- ture is attained, which is compatible with the plate material and such that the same pla- te isn't damaged and the de-breathing thereof is obtained.

In turn, the thermostat 18 is connected in the electric circuit together with one or more moisture sensors 19, applied against the outer surface 9 of the mirror plate 6, at posi- tions appropriately distributed along such outer surface and adapted to sense perma- nently the respective moisture conditions thereof. Preferably, these moisture sensors are fixed to the mirror near its peripheral frame 7, with the application of an overlying circular sealing gasket 20 having such form and size as to permit it to be adapted on the mirror, along the peripheral zone thereof, and are each provided with a sensitive

portion 21 made of suitable metallic material with good electric conductivity and oxi- dationsproof, which portion is applied closely against the outer surface 9 of the mirror plate 6 for sensing the moisture conditions thereof, as well as a junction portion 22 covered by the gasket 20 and provided with the relative terminals for the connec- tion of the electric circuit conductors. In order to eliminate any possible condensate which has been formed in the hollow space defined between the gasket 20 and the mirror, under unfavourable ambient conditions, thereby avoiding wrong readings of the moisture sensors 19, at least a through hole 24 is provided on the mirror lower side through the peripheral frame 7, which is adapted to put into communication such hollow space with the outside and therefore to drain such condensate outside.

In the mirror referred to the moisture conditions of the outer surface 9 are sensed by means of the sensors by sensing the change of the electric conductivity of the same surface, which conductivity in turn depends from the temperature to which this surface is submitted. In particular, in the present case the moisture sensors 19 are so calibra- ted as to keep the heating resistances off until the temperature of the outer surface 9 of the plate 6 is higher than a pre-established level, wherein the condensation of the atmospheric moisture onto such surface does not occur, thereby maintaining the visi- bility of the same surface, and to turn such heating resistances on as soon as said tem- perature has been attained and tends to decrease, which circumstance permits to a- void the formation of such condensate, thereby maintaining always the visibility of the outer surface 9 of the mirror plate 6.

Consequently, the heating resistances are always controlled both by the moisture sen- sors 19, depending on the outer ambient temperature, and the thermostat 18 depen- ding on the temperature respectively attained on the mirror plate 6, in order to avoid

excessive heatings thereof by ensuring also a heat storage sufficient to keep the outer surface 9 of said plate de-breathed for long time periods.

In the Fig. 3 it is now represented schematically the heating electric circuit of the present anti-breathing mirror, which is contained in the above mentioned junction box 15, As evident, this circuit is substantially constituted by a transformer-power supply unit 25 connected by an electric cable 26 to an electric connector block 27, situated near the vertical pole 14, which unit is realized preferably as a printed cir- cuit board and so dimensioned as to supply with AC voltage the heating elements (and the thermostat 18 associated therewith), with an electric power sufficient to prevent any formation of condensate on the outer surface 9 of the plate 6, and to supply with a low DC voltage both the moisture sensors 19, together with a proper electronic control circuit 28 associated therewith and interacting with the electric heating elements 16, and a set of L. E. D., pilot lamps or similar indicators, of which in the Figure there are made evident a first, a second and a third indicator 29,30 and 31 provided for sensing respectively the circuit turned on or off condition, as well as the operative conditions respectively of the thermostat 18 and the moisture sensors [n particular, the electronic control circuit 28 is realized and calibrated in such a manner as to receive and recognize the electric (analog or digital) signals co- ming from the moisture sensors 19 and corresponding to the temperature of the ou- ter surface 9 of the mirror plate 6, and to affect the electric heating elements 16 and the associated thermostat) 18 depending on the level of such signals, with cut in and off operations of such heating elements, whose heating temperature is also controlled by the thermostat, with the operative sequences and for the scopes previously descri- bed. In order to perform these functions, such electronic control circuit 28 may be re-

alized for example as an analog or digital comparator, or a bridge circuit or with other sensing and regulating circuits well known in the art, a detailed description of which is omitted for simplicity, thus without departing from the protection sphere of the present invention. The present invention also refers to mirrors suitable to display any kind of writings such as luminous displays etc. used for traffic signals.

In the Fig. 4 it is now represented a possible additional electric control means, which can be connected to the electric circuit of the present anti-breathing mirror, in order to cut it off at certain atmospheric conditions and particularly under heavy rainfall conditions, wherein any heating operation of the present mirror would not provide at all the desired anti-breat effect thereof. This additional electric control means is substantially consti- tuted by an additional electric control circuit 32 realized as a card formed by at least a sensor sensitive to the sound frequency of the rain falling on the mirror outer surface and connected to the transformer-power supply unit 25 through an electric cable 33 and to the electronic control circuit 28 through at least a relay 34 or similar control device, provided with an electric contact 35, said relay being operated by such sensor in such a way as to open the contact 35 thereby cutting the control circuit 28 off when the sound frequency of the rain falling on the mirror outer surface is higher than a certain level, at heavy rainfall conditions wherein the heating of the mirror would not provide an anti-breathing effect, with consequent energy saving, and to close the contact 35 thereby cutting the control cir- cuit 28 in when the rain sound frequency is lower or equal than that level, wherein the hea- ting of the mirror causes the anti-breathing effect. Obviously, the sensor may be also of other type, sensitive to the quantity of rain falling on the mirror outer surface, and adapted to cut in and off the electric control circuit 32 with the same operative criteria, thus with- ) ut departing from the protection sphere of the present invention.