EP1632007B1 - Anticorrosive protection system for antenna glass, and corresponding antenna glass - Google Patents

Abstract

The corrosion protection circuit provides the windscreen antenna conductor structure with an electrical passivation voltage (Up), with circuit components, e.g. a bandpass filter (3B), a DC/DC converter (3W) and a smoothing stage (3S), allowing the passivation voltage to be used as the supply voltage for a HF component (3,3A) connected to the multi-pole line provided by parallel sections of the conductor structure. Also included are Independent claims for the following: (a) a method for operating an automobile windscreen antenna; (b) an automobile windscreen antenna.

Description

The invention relates to an anti-corrosion protection system for antenna glazing with a surface conducting structure having the features of claim 1.

Glass windows of vehicles, glass and / or plastic, are very often provided with electrically conductive structures, for example to heat them and / or to form antenna structures. Most of the time, the surface structures are screen printed (thick film technique) from an electrically conductive silver paste, which is then consolidated by firing.

Antenna lines or parts thereof are also often conducted on the surface of the transparent substrate; these can also be used for power supply (remote power supply, for example from a tuner) of high frequency electronic elements (HF), such as antenna amplifiers and the like, arranged directly on the glazed antenna. In this way, an active antenna can be formed in total. The lines themselves must not radiate and have a characteristic impedance defined, constant over the length. This requirement can be met by two or more parallel coplanar conductors with constant spacing and constant width.

Embodiments of such signal lines and active antennas are described in the document DE-A1-39 11 178 where, to form coplanar signal and power lines on an antenna glazing of dielectric material, the line itself is combined with one or two ground tracks laid in parallel.

A major disadvantage of such printed lines leading the normal service voltage of vehicles (about 12 V =) is however manifested in operation, when exposed to the weather. The supply voltage for the amplifier (s) is applied as an offset DC voltage on one of the conductors. Amplifiers are associated with electronic elements to separate the offset DC voltage as the operating voltage of the RF signals. At the signal line, a potential difference of 12 V _DC between the signal conductor and ground is applied in service. This difference in potential, applied to a coplanar line in the thick layer technique, already leads in 5 minutes to first corrosion phenomena, by the salt spray test according to DIN 50021-SS. After 10 minutes, there is a massive corrosion of the conductive structure. Said salt spray test simulates the corrosive effects for the lifetime of the component in a greatly shortened period of time; its application to antenna structures placed on vehicle windows is however not prescribed until now.

The corrosion damage that appears severely degrades the properties of the coplanar lines, in particular by reducing the high-frequency conductivity and by increasing the damping of the line, and then the disruption of the tuning of the system to its total failure. This damage also occurs when the printed structures are on an inner surface of a window pane in the mounted state. The above document does not discuss this problem.

It is certainly possible, with certain costs, to protect the lines against corrosive attacks by coatings, caps or the like. However, the costs of these protections have hitherto prevented their industrial exploitation.

It should be emphasized that corrosion damage can, in principle, also occur in other printed structures, for example in the heating field and the antenna itself, even if they do not affect their operating mode as seriously.

The problem underlying the invention is to provide effective protection against electrical corrosion for antenna glazings with a conductive structure with surface lines conducting the voltage.

It will also be necessary to describe a method for the use of such an antenna glazing as well as an antenna glazing equipped accordingly.

The invention proposes for this purpose an anti-corrosion protection system for an antenna glazing with a conductive structure, comprising the characteristics according to the independent claim 1.

The invention can make it possible to dispense with an additional passive coating on the line.

For electrical passivation and thus the active anti-corrosion protection, it is necessary between two electrical conductors not electrically connected to each other very close to one another on a surface of the substrate itself or in another way, a potential difference of the level of the passivation voltage. This can be done in a particularly simple manner for a capacitively coupled antenna glazing, which is thus passivable in a suitable spatial arrangement at an opposite pole.

For example, the multipole line which is conducted parallel to a ground rail (ground or + 12V), is passivable by the choice of an amplitude and, where appropriate, an appropriate signal frequency.

The value of the passivation voltage will be determined individually for the material of the line to be protected against corrosion. It is generally possible to determine a marked passivation range depending on the value of the external voltage or passivation, in which the corrosion current (proportional to the rate of disintegration of the metal) is minimized or even tends to zero, which means that no corrosion no longer occurs. In the case of external voltages that are too low, a sufficient corrosion inhibiting effect ("active" range) is not obtained, whereas in the case of voltages that are too high (greater than the "priming potential"), a a state called "transpassive" appears, in which the protective effect no longer acts and the corrosion current again increases sharply.

The electronic matching elements can be separated from the electronic element HF or even integrated in this element for its direct supply by the passivation voltage.

Preferred voltage values for passivation of the materials usually used for such conductive structures have been determined in the range of 0.75 to 1.8 V DC or AC voltage.

The voltage source is integrated into a device connected in service to the electronic element HF, such as a tuner.

The passivation voltage according to the invention may be alternating and preferably be sinusoidal and be in the frequency range greater than 2000 Hz, preferably between 2000 and 4000 Hz or around 3000 Hz. A maximum of passivation has been determined. with 1.1 V and 3000 Hz ± 100 Hz.

The possibility of electrical passivation by application of a relatively low (alternative) electrical voltage gives the possibility of economically implementing the silver-content conductive structures produced for example by screen printing.

The protective effect by applying a voltage consumes very little energy, which causes only negligible additional operating costs. With current densities measured <10 μA / cm ² , quiescent currents appear in the passivation mode, which are several orders of magnitude lower than the 1.5 mA values acceptable in the automotive sector.

If necessary, it is possible to dispense with the baking of printed structures, which is supposed to increase their mechanical and chemical resistance as a rule. This also simplifies the use of other substrates than glass, for example glazing made of synthetic material.

For the use of the invention, it is of course not envisaged not only lines arranged coplanar manner, so with two or more cords arranged one beside the other on the surface of the glazing. With modern screen printing processes, it is also possible for example to print one on the other several insulating layers insulated relative to each other. The anti-corrosion protection according to the invention can also be applied without difficulty to such multipole sandwich structures as well as to structures which are not deposited by screen printing (but for example by extrusion or by other methods of depositing conductive materials).

If it is provided on an antenna glazing several lines of the type which is in question here, one will naturally feed according to the possibilities their totality with the voltage of passivation (protection).

The invention also proposes a method of using an active antenna glazing with an antenna structure as well as with at least one multipole line formed by structural parts arranged parallel to each other on the glazing surface for transmitting RF signals as well as for connecting an RF electronic element to an operating voltage comprising the characteristics according to independent claim 7.

The invention also proposes a vehicle antenna glazing comprising an electronic element HF designed for a specific operating voltage and capable of being powered by a multipolar line (4) disposed on a surface of the glazing unit, according to claim 8 comprising the system protection device according to one of claims 1 to 6.

When the passivation voltage is an alternative, the glazing may comprise a rectifier and voltage converter which is associated with the electronic element HF, said rectifier and voltage converter converting said supplied AC voltage into a DC voltage suitable for supplying an amplifier of electronic element HF.

The electronic element HF can be fixed on a surface of the glazing.

The electronic element HF can be inserted into a laminated glazing unit.

The multipolar line may be composed coplanar of at least two conductive tracks deposited next to each other on a surface of the glazing, at a constant distance from one another.

The multipole line may also consist of at least two conductive tracks deposited one above the other on a surface of the glazing, at a constant distance from one another.

Other details and advantages of the subject of the invention will become apparent from the drawings of an exemplary embodiment and from its detailed description which follows.

• la Fig. 1 est une vue d'ensemble d'un vitrage d'antenne avec une structure d'antenne et une ligne coplanaire de signaux et d'alimentation réalisée sur la surface du vitrage;
• la Fig. 2 montre une vue de détail du montage d'un élément électronique HF et des éléments de la protection anti-corrosion.

In these drawings, which are schematic representations:

• the Fig. 1 is an overview of an antenna glazing with an antenna structure and a coplanar signal and power line made on the surface of the glazing;
• the Fig. 2 shows a detailed view of the mounting of an electronic element HF and the elements of the anti-corrosion protection.

According to Fig. 1 , an antenna glazing 1 is provided with a field of heating and antenna 2, which has been fabricated in known manner by screen printing a predetermined pattern of structure into an electrically conductive baking paste. Details of this structure known per se are not represented here; it will only be indicated that several narrow conductor tracks 2L extend transversely over the field of view of the glazing 1, between the two relatively wide lateral collector bars 2S, which are close to the edge of the glazing 1. The two collector bars 2S can be connected in a manner not shown in detail to an electric heating voltage, which circulates a current in the conductive tracks electrically connected in parallel with each other.

With a coupling conductor 2A (antenna foot) placed transversely with respect to said conductive tracks 2L, high frequency signals (HF) received by the antenna field 2 (for example radio signals or TV signals) are transmitted to an electronic element HF 3, whose assembly will be explained in more detail in relation to the Fig. 2 .

Starting from the electronic element HF 3 disposed in a manner known per se directly on the surface of the glazing unit 1, a signal and power supply line 4 made in a known manner in coplanar bipolar form on the surface of the glazing unit 1 along its edge. extends to an appropriate interface 5 (multiple connector, flat conductor, plug-in connection) on the edge of the glazing 1. Here, in the mounted state of the glazing 1, connections are made to the receiving apparatus ( radio, tuner, TV, ...) as well as to a voltage source not shown.

The supply voltage for the heating field itself can also be connected here. Such multipolar interfaces are in themselves part of the state of the art (see for example the document DE-PS 195 36 131 ) and will therefore not be discussed in detail here. No further attention will be given to shielding measures that may be necessary and the like, because these are commonplace for those skilled in the art.

It should be noted that the antenna field 2, the electronic element HF 3 and the line 4 do not necessarily have to be all on the same surface of the glazing. It is also not necessary for the application of the invention to use a printed antenna structure. For example, the line 4 to be protected can also be connected to a coating used as an antenna arranged inside a laminated glazing unit. Similarly, the electronic element HF 3 can be incorporated in a composite, if its overall assembly is sufficiently flat.

In principle, the line itself could of course also be incorporated in a composite, its electrical passivation is not mandatory, but it is still possible.

A peripheral line in phantom lines indicates the inner edge line of an opaque colored frame 7, which usually surrounds as an outer limit the field of vision of the antenna glazing 1, which is otherwise transparent, and extends to outer edge thereof. Such a colored frame also masks the electronic elements of the antenna structures described here. It is recognized that, in the plane projection of the glazing, the busbars 2S, the electronic element HF 3, the coplanar line 4 and the interface 5 are located on this colored frame 7.

By line 4, on the one hand, an HF (amplified) signal supplied by the electronic element HF 3 and, on the other hand, a supply voltage to the active electronic element HF 3 are supplied to a reception apparatus (not shown). . Line 4 is composed in the present example asymmetrically of a wide conductive strip 4G and a narrow conductive strip 4S parallel to a constant distance therefrom. It is preferably printed during the same operation as the heating field and antenna 2 and is, in the mounted state of the glazing 1, exposed to the weather. The conductive strip 4G is closer to the edge of the glazing 1 than the band 4S, so that the latter respects a distance as large as possible of a metal body, in which the glazing 1 must be installed later. The 4G wide conductor strip can also, if necessary, be connected directly, for example by an electrically conductive adhesive, to the chassis of the vehicle.

• Impédance caractéristique ZL :    50 ohm
• Largeur de la ligne de signaux 4S :    0,8 mm
• Largeur de la fente :    4,1 mm
• Largeur de la bande de masse 4G :    5,7 mm
• Épaisseur de la vitre (diélectrique) :    3,85 mm

For the asymmetric configuration shown, the following dimensions result:

• Characteristic impedance ZL: 50 ohm
• Width of the 4S signal line: 0.8 mm
• Width of the slot: 4.1 mm
• Width of the 4G mass band: 5.7 mm
• Glass thickness (dielectric): 3.85 mm

For the conductive strips 4S, 4G and the heating field 2S, 2L, it is possible, for example, to use a screen printing paste of the SP 1835 type of CERDEC with a silver content of 80%. The opaque colored frame 7 is printed with CERDEC black enamel 14252/80860. These two materials to be printed on one another are compatible with each other, and one can with them suitably respect the desired characteristic impedance of line 4.

If the line is deposited on laminated glass surfaces with a mixed dielectric (glass / adhesive layer / glass) and / or on panes with other thicknesses or other materials (plastics, eg polycarbonate), their geometrical dimensions and, where appropriate, the printing pastes should be suitably adapted, as should the line be designed for Z _L = 75 ohm.

The Fig. 2 shows a possible discrete embodiment of the electronic element HF 3 and elements of the active corrosion protection. On the left side, the connections of line 4 (4G, 4S) have been drawn, on the right side the connection 2A towards the antenna foot. The 4G connection serves as a ground, while the 4S connection leads both the RF signal level to a receiving device 8 (tuner) and a supply voltage superimposed on the RF signals. It goes without saying that the RF connection of the reception apparatus 8 is not sensitive to the presence of the supply voltage.

It goes without saying that such an electronic element HF can also be designed and used in an integrated form. In general, an assembly as flat as possible is interesting, which is little salient above the surface of the glazing or which can also be used incorporated in a laminated glazing.

In the exemplary embodiment shown, the passivation voltage is an alternating voltage U _P with an amplitude of 1.1 V and a frequency of 3000 ± 100 Hz, which is produced by a voltage source 9 shown only schematically.

This passivation voltage has been determined experimentally as being an optimum for active anti-corrosion protection of such lines respectively of such structures.

This passivation voltage is therefore used in accordance with the invention for feeding the line 4 subject to corrosion, at the place where the operating voltage was usually applied in the active components HF.

A typical operating voltage is used depending on the application case for standard series parts between 3.3 V and 12 V =. Such values showed no passivating effect in the tests.

The voltage source 9 could also be integrated directly into the receiving apparatus 8, unlike the representation.

The electronic element HF 3 comprises an antenna amplifier 3A, to which the antenna signals are transmitted immediately by 2A, and which is connected by a decoupling stage 3K to the line 4S.

When connected in parallel with the decoupling stage 3K, there is a bandpass 38 for filtering the supply voltage out of the HF signals, which sends the filtered voltage to a rectifier with a 3W AC / DC converter.

The rectifier with converter must convert the rectified voltage to the operating voltage of the electronic components possibly integrated in a module. This voltage is then sent to the amplifier 3A, by a filtering / smoothing stage 3S or alternatively directly.

The operating voltage U _B and the ground can of course also be used for the power supply of other possible electronic elements, not shown here, for example still other amplifiers, etc.

As a passivation voltage U _P , it would be possible to use according to the invention also a DC voltage of comparable level, unlike the representation, which is naturally not rectified, but which should only be raised to the level of the operating voltage. U _B.

The application case described here is based on the use of the usual electronic elements to date.

However, it is conceivable to also allow a direct use of the passivation voltage (and supply) supplied by correspondingly adapting the electronic components, in particular the amplifier.

In application cases like this, only very low currents and very low voltages appear. It will therefore miniaturize very strongly the components used and install them in a compact unit. Therefore, the mounting of the antenna glazing 1 (for example its bonding with a flange of the bodywork) is not affected, even when the components are, in the preferred arrangement, arranged near the edge on the face of the window mounted indoors in the assembled state.

Claims (13)

1. Corrosion-protection system for antenna glazing (1) having a conducting structure, comprising at least one multipole line (4; 4S, 4G) formed by at least two structure parts lying parallel to one another on the surface of the glazing and for transmitting HF signals by one of the so-called HF signal structure parts (AG) and for connecting an HF electronic component (3, 3A) to a service voltage (U_B), characterized in that the system includes a voltage source (9) for injecting, in the HF signal structure part and in the HF electronic component (3, 3A), a passivation electrical voltage (U_P) lying within the range for passivating the material of the line against corrosion and in that the system includes electronic adaption components (3B, 3W, 35) associated with the HF electronic element for exploiting said passivation voltage (U_P) as a service voltage in the HF electronic component (3).
2. Corrosion-protection system according to Claim 1, characterized in that the voltage source (9) for an AC or DC passivation voltage (U_P) lies within the 0.75 to 1.8 V range.
3. Corrosion-protection system according to either of Claims 1 and 2, characterized in that the voltage source (9) is integrated into a unit connected in service to the HF electronic component, such as a tuner (8).
4. Corrosion-protection system according to one of Claims 1, 2 and 3, characterized in that the passivation voltage (U_P) is an AC voltage with a frequency of more than 2000 Hz, preferably between 2000 and 4000 Hz.
5. Corrosion-protection system according to one of Claims 1 to 4, characterized in that the passivation voltage (U_P) is an AC voltage of 1.1 V with a frequency of about 3000 Hz.
6. Corrosion-protection system according to any one of the preceding claims, characterized in that, when the service voltage (U_B) of the HF electronic component (3, 3A) is different from the passivation voltage (U_P), the electronic adaption components (3B, 3W, 3S) include means (3W) for converting the passivation voltage (U_P) to the service voltage (U_B).
7. Method of using antenna glazing having an antenna structure and at least one multipole line formed by structure parts lying parallel to one another on the surface of the glazing for transmitting HF signals by one of the so-called HF signal structure parts (AG) and for connecting an HF electronic component to a service voltage, characterized in that the line and the HF electronic component that is connected thereto are supplied with a passivation voltage lying within the range for passivating the material of the line and superposable on the HF signals and in that this passivation voltage is used, directly or after adaptation, as service voltage for the HF electronic component.
8. Vehicle antenna glazing that includes an HF electronic component (3) designed for a specified service voltage (U_B) and capable of being supplied via a multipole line (4) placed on a surface of the glazing (1), characterized in that it includes the protection system according to one of Claims 1 to 6.
9. Antenna glazing according to Claim 8, characterized in that, when the passivation voltage (U_P) is an AC voltage, it includes a voltage rectifier and converter (3W) that is associated with the HF electronic component (3), said voltage rectifier and converter converting said delivered AC voltage into an appropriate DC voltage for supplying an amplifier (3A) of the HF electronic component (3).
10. Antenna glazing according to either of Claims 8 and 9, characterized in that the HF electronic component (3) is fixed to a surface of the glazing (1).
11. Antenna glazing according to either of Claims 8 and 9, characterized in that the HF electronic component (3) is inserted into laminated glazing.
12. Antenna glazing according to any one of Claims 8 to 11, characterized in that the multipole line (4) is made up, in a coplanar manner, of at least two conducting tracks (4G, 4S) deposited beside one another on a surface of the glazing, at a constant distance apart.
13. Antenna glazing according to any one of Claims 8 to 11, characterized in that the multipole line (4) is made up of at least two conducting tracks (4G, 4S) deposited one on top of another on a surface of the glazing, at a constant distance apart.

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