GLAZING WITH A CAPACITIVE HUMIDITY SENSOR

Abstract

Glazing (1) comprising at least one capacitive humidity sensor (2) with a humidity detection function having two spaced electrodes, characterized in that said capacitive humidity sensor (2) with a detection function also has a humidity prediction function. Figure to be published with the abbreviation: Fig. 1

Description

Title of the invention: GLAZING EQUIPPED WITH A CAPACITIVE HUMIDITY SENSOR

[0001] The invention relates to a glazing comprising at least one capacitive humidity sensor.

[0002] The invention will be more particularly described with regard to vehicle glazing without however being limited thereto.

[0003] It is known to equip vehicle glazing, in particular the windshield, with sensors, including humidity sensors. Humidity sensors are designed to provide their information to an electronic control unit that can automatically control the vehicle's heating system. A vehicle's heating system is commonly referred to by the acronym HVAC (heating, ventilation, and air-conditioning). Automatic control of the heating system saves the driver from having to adjust it manually.Indeed, manual control is not optimal because it can easily be associated with a waste of energy, a vehicle window can for example be heated for defrosting more than necessary, or when the fog is already on the window, manual operation generally combining heating and ventilation to remove the fog quickly generates significant energy consumption. On the contrary, automatic control allows for more energy savings, and has the advantage for the user of not having to manage anything.

[0004] There are two types of capacitive humidity sensors: the capacitive humidity sensor for detecting that there is already condensation on the glazing, and the capacitive sensor for predicting the humidity phenomenon.

[0005] The capacitive humidity detection sensor comprises two electrodes which have on the surface of the glazing the appearance of electrically conductive paths, for example in the form of a comb, and are spaced from each other while being electrically insulated from each other by the space separating them. The capacitive humidity sensor is based on the measurement of the relative capacitance between the two electrodes, the presence of humidity on the glazing of the vehicle modifying the capacitance. The electronic control unit converts the capacitance into a relative humidity value. Depending on the relative humidity value measured in real time, the electronic control unit turns on or off the HVAC.

[0006] As for the predictive capacitive humidity sensor, it has the same elements as the capacitive detection sensor, namely two spaced electrodes, and it also comprises a hygroscopic layer which completely covers the surface of the two electrodes. In the remainder of the description, the term "completely covers the surface of the electrodes" means that the covering layer forms a covering surface whose periphery is circumscribed to the electrodes except at the electrical connection points of the electrodes. When the humidity varies, the dielectric properties of the hygroscopic layer change, as does the capacitance of the sensor. A relative humidity is deduced from the capacitance value of the sensor. By coupling this relative humidity to a temperature measurement (via a temperature sensor), the proximity or otherwise of the dew point is deduced, the dew point corresponding to the formation of fog.Depending on the estimated relative humidity and temperature, if the dew point is approached, the electronic control unit will activate the HVAC, allowing for even more energy savings through this automated configuration.

[0007] Generally, glazings include either a capacitive detection humidity sensor or a predictive capacitive humidity sensor, because the use of two humidity sensors on the same glazing has the disadvantage of increasing the manufacturing cost and having two different types of signals to process. However, the detection sensor is essential, because it is particularly necessary when starting the vehicle if mist is already present or if mist appears very quickly on the glazing, while the predictive sensor is very useful for optimal regulation of the HVAC in order to save energy as much as possible.

[0008] The invention therefore aims to propose a glazing comprising at least one capacitive humidity sensor, which does not have the aforementioned drawbacks, the glazing being designed to detect humidity as soon as it is present on the glazing, but also, before any appearance of humidity, to predict it so as to optimize the control of the heating system, and this without affecting the manufacturing cost of the glazing or complicating the processing of the measured information.

[0009] Thus, the invention relates to a glazing comprising at least one capacitive humidity sensor with a humidity detection function comprising two spaced electrodes (intended to be electrically connected to electronic processing means, in particular to the electronic control unit (ECU) of the vehicle in which the glazing is installed), characterized in that said capacitive humidity detection sensor also has a humidity prediction function.

[0010] Therefore, the same capacitive humidity sensor has two functions, both detection and prediction, which makes it possible to impose only one electrical signal to be processed since only two electrodes are used, and which does not increase not significantly reduce the manufacturing cost of the glazing compared to glazing which would include two separate capacitive sensors.

[0011] According to one feature, the capacitive humidity sensor comprises a hygroscopic coating (humidity absorbing layer) which partially covers the two electrodes (a part of the electrodes is covered by the hygroscopic coating and another part of the electrodes is not covered). In particular, the electrodes travel in a longitudinal direction along two respective lines facing each other and have a part of their length covered by the hygroscopic coating, while the other part of the length is devoid of hygroscopic coating.

[0012] According to one feature, each electrode comprises an electrical connection point (for electrically powering each electrode and connecting it to the ECU), and the hygroscopic coating (providing the predictive function) is located on the side of the electrical connection points of the electrodes (while the uncovered portion of the electrodes (providing the detection function) is located opposite the electrical connection points). Alternatively, the uncovered portion of the electrodes may be located on the side of the electrical connection points and the hygroscopic coating is located opposite the electrical connection points.

[0013] Preferably, a single continuous zone along a portion of the length of the two electrodes is covered by a hygroscopic coating. The covering has the shape of a solid surface extending along a portion of the length of the electrodes and along at least the entire distance separating the outermost longitudinal edges of the two combined electrodes in the direction orthogonal to the longitudinal direction of the two electrodes. The covering surface forms, for example, a rectangle by extending beyond the outer longitudinal edges of the electrodes. The extension beyond the electrodes in the direction orthogonal to the longitudinal direction makes it possible to properly encompass the outer longitudinal edges of the electrodes. This overlap extension beyond the electrodes is, for example, 5 mm to take into account a tolerance of 2 or 3 mm depending on the method of depositing the hygroscopic coating.

[0014] Unexpectedly, the hygroscopic coating which is only on a certain part of the electrodes does not disturb the detection of humidity by the part of the electrodes not covered by the hygroscopic coating layer when mist appears on the glazing. There is indeed only one signal which is transmitted to the electronic processing means since only a pair of electrodes arranged in a capacitive manner is used. As long as there is no mist on the glazing, the value of the measured capacitance increases only as a function of the water which the hygroscopic layer can absorb, and when mist appears, the measured capacitance increases again but according to a greater variation. This is the magnitude of this change in the value of the capacity as a function of the relative humidity which is intended to be analyzed by electronic processing means from a single signal measured over time.

[0015] According to one characteristic, the electrodes have a thickness in the direction orthogonal to the plane of the glazing comprised in a range of 5 to 20 μm, preferably above 8 μm. The term "thickness in the direction orthogonal to the plane of the glazing" means the height of deposition on the glazing of the electrically conductive coating. Advantageously, the hygroscopic coating has a thickness (dimension orthogonal to the plane of the glazing) which is comprised in a range of 5 to 50 μm, preferably 10 to 20 μm. The hygroscopic coating is thicker than the thickness of the electrodes.

[0016] Advantageously, the hygroscopic coating extends over a length of the electrodes which corresponds to 25% to 75% of the length of the electrodes, in particular which corresponds to 50% of the length of the electrodes. The electrodes each have the same length. The “length” of an electrode within the meaning of the invention is understood to be the longitudinal extension of the electrode relative to the glass surface (longitudinal dimension and not linear dimension with the meanders). The length of an electrode begins from the place where the covering by the hygroscopic layer begins (electrical connection point side) to the termination of the electrode opposite the hygroscopic layer (and therefore opposite the electrical connection point). The two dimensions of the electrodes in the plane of the glazing will be adapted to provide sufficient detection.The length of the electrodes may be, for example, in the range of 3 to 7 cm, and the distance between the outermost longitudinal edges of the electrodes may be, for example, in the range of 1 to 3 cm. The distance between the electrical connection points and the start of the electrode length (start of the covering layer) will be adapted according to the location of the sensor on the glazing; this distance has no influence on the measurements.

[0017] Advantageously, the hygroscopic coating is a polymeric layer based on polyvinyl alcohol (PVA), or polyvinylpyrrolidone (PVP), or polyamide(s), optionally further comprising an electrolyte such as sodium polystyrene sulfonate (PSSD), or sodium chloride (NaCl) or disodium benzenedisulfonate (MBSD), or dioctyl sodium sulfosuccinate (DOSS NA). The electrolyte in the composition of the hygroscopic coating layer makes it possible in particular to improve the sensitivity to humidity of the capacitive sensor, which provides predictive information further in advance.

[0018] The hygroscopic coating can be deposited by different techniques, for example by film applicators of the spiral applicator type ("bar coater" in English), by roller applicators, pad printing, screen printing or spraying. If the composition has been diluted in water or solvent for its application, it will be necessary to dry it after application (by passing it through an oven or under infrared radiation, or by blowing hot air).

[0019] According to another characteristic, the two electrodes are based on electrically conductive ink or electrically conductive paste such as carbon paste or silver-based paste, in particular deposited by screen printing or printing, like the heating wires or antenna wires usually deposited on glazing. As a variant, the two electrodes may be a transparent electrically conductive coating such as a transparent electrically conductive ink deposited by printing. In another variant, the transparent electrically conductive coating is for example an electrically conductive layer based on a transparent conductive oxide (TCO), such as of the heating coating type, such as 1TTO (indium tin oxide), preferably the layer being deposited by magnetic field-assisted cathode sputtering and the space between the two electrodes which constitutes an electrical insulation zone being produced by laser stripping.The process of depositing the two electrodes will be adapted in particular according to the nature of the electrode material.

[0020] According to another characteristic, the electrodes are nested within each other while being spaced apart, forming combs or spirals or serpentines or geometric shapes with meanders.

[0021] The width (direction in the plane of the glazing) of each electrode is for example in a range between 200 and 500 pm. A width of 250 pm may be preferred, it makes it possible to optimize (minimize) the size of the sensor. The width of each electrode will be a function of the length of the electrode. For example, the width will be 250 pm for a length of 3.5 cm, and will be 500 pm for a length of 7 cm. As for the distance between the electrodes, said electrodes are spaced with the same spacing along their entire length. The space between the two electrodes is in a range between 200 and 500 pm.

[0022] The glazing is in particular a vehicle glazing, in particular a motor vehicle, in particular a motor vehicle, said capacitive humidity sensor with predictive and detection functions being arranged on the face of the glazing for which the prediction and detection of humidity are desired. The capacitive humidity sensor with predictive and detection functions may be arranged on the internal face of the glazing (the one intended to be inside the passenger compartment of the vehicle) or on the external face (the one in contact with the environment outside the vehicle). Two capacitive humidity sensors with predictive and detection functions may be arranged, respectively, one on the external face of the glazing and the other on the internal face. The glazing may be a single or laminated glazing. The humidity sensor is in any case not inside the glazing, for example, it is not inside laminated glazing. The humidity sensor is in direct contact with the ambient air whose humidity is to be detected (air from the exterior or interior environment of the vehicle).

[0023] The invention also relates to an assembly comprising a aforementioned glazing of the invention and electronic processing means such as a vehicle electronic control unit, the electronic processing means being capable of analyzing the capacitance values ​​received from said capacitive humidity sensor with predictive and detection functions to detect the risk of fogging on the glazing and the presence of fogging on the glazing, in particular the electronic processing means being capable of calculating the derivative of the mathematical function of the capacitance as a function of the relative humidity and analyzing this derivative by detecting the change in value of the derivative (over time). The mathematical function of the capacitance as a function of the relative humidity is a straight line. The derivative corresponds to the magnitude of the variation in the capacitance relative to the variation in relative humidity.In particular, when the electronic processing means detect a first change in the value of the derivative, i.e. a first change in the slope of the straight line relative to an initial straight line with zero slope (and an initial capacity of insignificant value or less than a minimum threshold value), said electronic processing means then detect a risk of fogging, and when they detect a second change in the value of the derivative, i.e. a second change in the slope of the straight line relative to the first slope, they detect the presence of fogging.

[0024] Depending on the changes in the values ​​of the derivative and the value of the capacitance and therefore the relative humidity, the electronic processing means are able to act in an automated manner on the HVAC and its regulation. A temperature sensor is not essential with the capacitive humidity sensor of the invention, unlike the state of the art which necessarily combines a temperature sensor with a predictive capacitive humidity sensor. However, the presence of a temperature sensor will allow for more precise control of the HVAC.

[0025] The present invention is now described using examples which are solely illustrative and in no way limitative of the scope of the invention, and from the attached illustrations, in which: - [Fig.l] or [Fig.l] represents a schematic view of a glazing comprising a capacitive humidity sensor of the invention. - [Fig.2] or [Fig.2] represents a view of an exemplary embodiment of a capacitive humidity sensor of the invention. - [Fig.3] or [Fig.3] illustrates a partial view of another form of the electrodes of the capacitive humidity sensor of the invention. - [Fig.4] or [Fig.4] is yet another variant of the shape of the electrodes. - [Fig.5] or [Fig.5] is yet another variant of the shape of the electrodes. - [Fig.6] or [Fig.6] illustrates a schematic view of the evolution of the capacity as a function of relative humidity for the capacitive humidity sensor of the invention of [Fig.2] as well as for two comparative sensors, respectively, detection only and prediction only.

[0026] The glazing 1 of the invention illustrated in [Fig.l], for example a motor vehicle glazing, comprises a capacitive humidity sensor 2 which has the function of both detecting condensation or mist on the glazing, and of predicting the risk of mist on the glazing. In a single capacitive humidity sensor, two functions are thus combined according to the invention, that of prediction and that of detection. In the same vehicle, the capacitive humidity sensor 2 of the invention can be affixed to several of the vehicle's glazings to provide information on the presence of humidity and the risk of humidity associated with each glazing comprising such a capacitive humidity sensor 2.

[0027] The capacitive humidity sensor 2 is intended to be electrically connected to electronic processing means 3 such as the electronic control unit 3 (ECU) which is integrated in the vehicle (in the on-board electrical system or the vehicle electronics). The information measured by the capacitive humidity sensor 2 is intended to be transmitted to the electronic control unit 3 for electronic processing.

[0028] The electronic control unit 3 controls various equipment of the vehicle including the HVAC system. Depending on the information from the capacitive humidity sensor 2 and the result of electronic processing of the information, the electronic control unit 3 is able to automatically trigger the HVAC if the risk of condensation forming is detected, or if fog or frost is already present and is detected on the glazing, and to regulate the HVAC according to the evolution of the variation in capacity measured as a function of the relative humidity.

[0029] As shown in [Fig. 2], the capacitive humidity sensor 2 comprises two electrodes 20 and 21 extending in a longitudinal direction, each having an electrical connection point 22 and 23 respectively. The electrical connection points 22 and 23 of the electrodes are arranged opposite each other. The capacitive humidity sensor 2 further comprises a hygroscopic coating 24 consisting of a layer of moisture-absorbing polymeric material, hereinafter referred to as the hygroscopic layer 24.

[0030] The two electrodes 20 and 21 run opposite each other in parallel and are spaced apart while being electrically insulated from each other.

[0031] Each electrode 20, 21 is made of an electrically conductive material, for example based on silver paste and glass frits with around 80 to 85% silver. The electrically conductive material has for example been deposited by screen printing.

[0032] The electrodes 20 and 21 shown in [Fig. 2] are in the form of two combs arranged opposite each other and nested within each other without touching. Other variants than the comb embodiment are conceivable, such as serpentine ([Fig. 3]) or spiral ([Fig. 4]), or according to another geometry with meanders ([Fig. 5]).

[0033] The length L of each electrode ([Fig.2]), considered from the start of the hygroscopic layer 24 to the termination of each electrode opposite the electrical connection point 22 23, is for example 7 cm. Each electrode 20, 21 forms over its length L an electrically conductive line in the form of a comb.

[0034] The distance D ([Fig.2]) separating the outermost longitudinal edges 20A and 21A of the two combined electrodes 20 and 21 is for example 2.5 cm.

[0035] The spacing between the electrodes 20 and 21 is constant over the entire length of the electrodes. The spacing is for example 250 μm.

[0036] The width 1 ([Fig.2]) of each electrode (dimension in the plane of the glazing) is here 500 pm. This width corresponds to the length L of the electrode. In particular, if the length of the electrode is divided by two, the width 1 is divided by two.

[0037] The hygroscopic layer 24 partially covers the electrodes, and for the part that it covers, it is such that the electrodes are embedded in said layer. The thickness of the layer (in the direction orthogonal to the plane of the glazing) is 20 μm in the example of [Fig.2].

[0038] The hygroscopic layer 24 therefore covers a part of the length L of the electrodes 20 and 21. The hygroscopic layer 24 extends in the longitudinal direction of the electrodes along a partial length of the electrodes 20 and 21. The length of the hygroscopic layer 24 corresponds in the present example of [Fig.2] to half the length of the electrodes 20 and 21. In this example, the hygroscopic layer 24 extends over a length of 3.5 cm.

[0039] The hygroscopic layer 24 extends in the direction orthogonal to the longitudinal direction by a width which corresponds at least to the separation distance of the outer longitudinal edge 20A of the first electrode 20 to the opposite outer longitudinal edge 21A of the second electrode 21.

[0040] Preferably, the hygroscopic layer 24 protrudes in width towards the outside of the capacitive humidity sensor 2 beyond the outer longitudinal edges 20A and 21A so as to perfectly cover the electrodes. The protrusion width is for example 5 mm.

[0041] The capacitance between the electrodes 20 and 21 is regularly measured and the information is communicated to the electronic processing and control unit 3. The electronic processing and control unit 3 operates as soon as the vehicle is started. The electronic control unit 3 records the measurement data from the capacitive humidity sensor 2; it records the capacitance values ​​over time. For example, the sampling frequency is 20 measurements per second. Since the presence of humidity influences the capacitance between the electrodes 20 and 21, the electronic control unit 3 is able to process the capacitance values, its changes (the variation in capacitance) and its evolution over time, and to deduce the relative humidity (percentage) therefrom. The electronic control unit 3 has been calibrated in the factory to be able to deduce the correspondence between the variation in capacitance and the relative humidity.The electronic control unit 3 is capable, depending on the change in capacity as a function of relative humidity, of predicting the formation of fog and of detecting fog. In particular, humidity is first detected thanks to the presence of the hygroscopic layer 24 well before condensation has formed on the glazing, which makes it possible to anticipate the triggering of the HVAC.

[0042] The electronic control unit 3 comprises a microprocessor which is capable of processing the information received and executing commands, based on appropriate processing and control algorithms.

[0043] The electronic control unit 3 is capable of processing, that is to say of analyzing the values ​​of the capacitance over time, and as a function of the change and the evolution of the values ​​of the capacitance as a function of the relative humidity, is capable of predicting the risk of the presence of fogging on the glazing and of detecting fogging when there is fogging. In the mathematical representation of the evolution of the capacitance as a function of the relative humidity, the function (the curve) is a straight line. The electronic control unit 3 is capable of calculating the slope of this straight line over time as a function of the succession of the measured capacitance values. As a function of the slope and the value of the capacitance at time t, the electronic control unit 3 deduces the risk of fogging or the presence of fogging.The analysis by the electronic control unit 3 of the risk of fogging or the presence of fogging relates to the analysis of the break in the slope of the curve of the capacity as a function of the relative humidity. The change in slope is equivalent to the change in the value of the derivative of the function of the capacity as a function of the relative humidity. The electronic control unit 3 is able to calculate the derivative of the function of the capacity dependent on the relative humidity.

[0044] From the start of operation of the control unit 3, the analysis is a function of the measurement of the first value of the capacity and the following values: a. Case No. 1: • As long as the first measured capacitance value is of the order of a pre-recorded (and recalibrateable) threshold value (for example 150 pF) and the slope of the curve, i.e. the derivative of the function, remains zero over time, there is no fogging; • when the slope changes (the value of the derivative changes) and is therefore no longer zero, there is therefore detection of a first break in slope, the risk of fogging is then detected; • when the slope other than zero changes again (the derivative changes value again, in particular to a larger value), there is therefore detection of a second break in slope (in particular with a larger slope), this corresponds to the detection of the presence of mist. b. Case No. 2: If the first measured capacitance value is significantly higher than at least one pre-recorded threshold value, and the slope of the curve remains zero over time, then there is a risk of fogging or the presence of fogging. Advantageously, two capacitance threshold values ​​are pre-recorded, one being lower than the other and the second threshold value corresponding to a capacitance value for which humidity is likely to be highly present. To confirm the presence of fogging, the measured capacitance value can be correlated with a temperature value which is generally accessible because a temperature sensor is always present in a vehicle. However, the temperature measurement is not systematic in the capacitive humidity sensor of the invention with both predictive and detection functions.

[0045] In case No. 1, upon detection of the first break in slope, the control unit 3 is able to trigger the HVAC by operating a heating element of the glazing (heating layer or heating wires) and / or the ventilation to anticipate the presence of mist. Depending on the change in the value of the capacity (of the change in the relative humidity) over time, the control unit 3 regulates the HVAC appropriately. If a second break in slope is detected, and the slope is positive, mist is then detected, the heating was then not powerful enough and the control unit 3 is able to control the HVAC appropriately to eliminate the mist.If after starting the HVAC (possibly more powerfully when fogging has been detected), the capacity curve again shows a zero slope, the control unit 3 will deduce that there is no more fogging and will be able to stop the HVAC, while being able to detect, depending on the capacity value, that there may still be a risk of fogging.

[0046] To illustrate the operation of the capacitive humidity sensor 2 of the invention which has the combined functions of detecting the presence of fog and predicting the risk of fog, [Fig. 6] schematically shows the evolution of the capacitance as a function of the humidity for the capacitive humidity sensor 2 of the invention as well as for a capacitive humidity sensor for detection alone and a capacitive humidity sensor for prediction alone. Each curve is one above the other to facilitate reading. The relative humidity expressed starts at a value RH1. The three capacitive humidity sensors, that of the invention, that of detection and that of prediction each comprise the same nature of electrodes 20 and 21 (from silver paste and glass frits), and of length 70 mm for the electrodes of the sensor of the invention, 35 mm for the detection sensor and 35 mm for the prediction sensor.The predictive sensor and the sensor of the invention comprise the same hygroscopic layer 24 in PVP 20 μm thick, with for the predictive sensor a total covering of the electrodes, that is to say a covering of the entire part of nesting of the electrodes one in the other, and for the sensor of the invention a covering of 50% of the length of the electrodes.

[0047] It can be seen that for the CD curve which corresponds to the capacitive humidity detection sensor, the slope remains zero and a single sudden change in slope occurs at a humidity value RH2 (greater than RH1), meaning that mist present on the glazing is detected. On the other hand, this capacitive humidity detection sensor did not make it possible to anticipate the formation of mist.

[0048] For the CP curve which corresponds to the predictive capacitive humidity sensor, the slope remains zero and a single sudden change in slope occurs at a humidity value RH3 (RH3 is greater than RH1 and less than RH2). The change in slope occurs well before that of the CD curve, which is normal since the sensor, through its predictive function, detected the increase in humidity more quickly due to the absorption of water molecules by the hygroscopic layer. However, after the break in slope, the slope remains the same, making it impossible to detect when fogging becomes present on the glazing (when the humidity reaches the RH2 value).

[0049] For the CPD curve which corresponds to the capacitive humidity sensor 2 of the invention, a zero slope is observed, then a first break in slope at a first inflection point R and finally a second break in slope at a second inflection point I2. The first break in slope corresponds to the prediction that fogging may form and is consistent with the CP curve of the predictive capacitive humidity sensor with the first inflection point also at the relative humidity value RH3. The first slope from the first inflection point R corresponds to the absorption of humidity by the hygroscopic layer 24. The second break in slope corresponds to the detection of fogging and is consistent with the CD curve of the capacitive humidity sensor with the second inflection point I2 also at the relative humidity value RH2. The second slope from the second inflection point I2 is greater than the slope of the CD curve of the capacitive humidity sensor because the capacitance corresponds to the addition of the measured capacitance between the electrodes 20 and 21 covered with the hygroscopic layer 24 and the measured capacitance of the electrodes 20 and 21 without the hygroscopic layer 24.

[0050] Consequently, with the single capacitive humidity sensor 2 of the invention and therefore a single signal, in particular by using only two electrodes which are partially covered with a hygroscopic layer, it is possible to predict the risk of fogging occurring and to act in an automated manner (thus allowing a saving in costs) via the control unit 3 which controls the HVAC to prevent fogging, and it is also possible to detect fogging as soon as the sensor is put into operation (when the electronic control unit 3 is switched on), or to detect fogging after the prediction when, for example, the HVAC regulation has not been sufficient and / or the humidity has increased much more quickly than expected (in particular if several people have entered the vehicle while the cold outside the vehicle was significant), the HVAC then being controlled accordingly.

Claims

Claims

1. Glazing (1) comprising at least one capacitive humidity sensor (2) with humidity detection function comprising two spaced electrodes (20, 21), characterized in that the capacitive humidity sensor (2) comprises a hygroscopic coating (24) which partially covers the two electrodes (20, 21).

2. Glazing according to claim 1, characterized in that a single continuous zone along part of the length of the two electrodes is covered by the hygroscopic coating.

3. Glazing according to the preceding claim, characterized in that each electrode (20, 21) comprises an electrical connection point (22, 23) and in that the hygroscopic coating (24) is located on the side of the electrical connection points (22, 23) of the electrodes.

4. Glazing according to any one of claims 2 to 3, characterized in that the hygroscopic coating (24) has a thickness in a range of 5 to 50 μm, preferably 10 to 20 μm.

5. Glazing according to any one of claims 2 to 4, characterized in that the hygroscopic coating (24) extends over a length of the electrodes which corresponds to 25% to 75% of the length of the electrodes, in particular which corresponds to 50% of the length of the electrodes.

6. Glazing according to any one of claims 2 to 5, characterized in that the hygroscopic coating (24) is a polymeric layer based on polyvinyl alcohol (PVA), or polyvinylpyrrolidone (PVP), or polyamide(s), optionally further comprising an electrolyte such as sodium polystyrene sulfonate (PSSD), or sodium chloride (NaCl) or disodium benzenedisulfonate (MBSD), or dioctyl sodium sulfosuccinate (DOSS NA).

7. Glazing according to any one of the preceding claims, characterized in that the two electrodes (20, 21) are based on electrically conductive ink or electrically conductive paste such as carbon paste or silver-based paste.

8. Glazing according to any one of claims 1 to 6, characterized in that the two electrodes (20, 21) are a transparent electrically conductive coating such as a transparent ink electrically conductive layer deposited by printing, or such as an electrically conductive layer based on a transparent conductive oxide, preferably the layer being deposited by magnetic field-assisted sputtering and the space between the two electrodes which constitutes an electrical insulation zone being produced by laser stripping.

9. Glazing according to any one of the preceding claims, characterized in that the two electrodes (20, 21) are nested within each other while being spaced apart, forming combs or spirals or serpentines or geometric shapes with meanders.

10. Glazing according to any one of the preceding claims, characterized in that the two electrodes (20, 21) are spaced with the same spacing along their entire length, and the space between the two electrodes is in a range between 200 and 500 μm.

11. Glazing according to any one of the preceding claims, characterized in that the width of each electrode (20, 21) is in a range between 200 and 500 μm.

12. Glazing according to any one of the preceding claims, characterized in that the glazing is a vehicle glazing, in particular a motor vehicle glazing, said capacitive humidity sensor (2) being arranged on the face of the glazing for which the prediction and detection of humidity are desired.

13. Glazing according to claim 12, characterized in that two capacitive humidity sensors are arranged, respectively, one on the external face of said glazing and the other on the internal face.

14. An assembly comprising a glazing (1) according to any one of the preceding claims, and electronic processing means (3) such as a vehicle electronic control unit, the electronic processing means (3) being capable of analyzing the capacitance values ​​received from said capacitive humidity sensor (2) to detect the risk of fogging on the glazing and the presence of fogging on the glazing, in particular the electronic processing means (3) being capable of calculating the derivative of the mathematical function of the capacitance as a function of the relative humidity and analyzing this derivative by detecting the change in value of the derivative.

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