DE102005022913A1 - Capacitive windscreen rain sensor has internal condensation detector using temperature sensor - Google Patents

Abstract

A capacitive windscreen (3) rain sensor has an oscillator circuit (41) inside the glass structure and second detector with a moisture-sensitive element comprising a temperature sensor (43) with common processors (42, 45) on the internal surface (2). Independent claims are included for procedures using the rain sensor.

Description

The The invention relates to a device for humidification detection a first surface of a Window pane, for example a motor vehicle windshield and on a first side of the same, for example, on the surface of the outside the automobile windshield.

Out known prior art devices of the aforementioned Art have a first means for humidification detection, this first means comprises a resonant circuit, which is inside the windowpane is arranged. Furthermore, such a means has a first evaluation circuit, the outside the window pane is arranged and with the resonant circuit inductive is coupled. By moistening the window pane, be it on the first surface or on a second surface that to a second page is aligned (for example, to the vehicle interior) is the resonant circuit detuned. The detuning of the resonant circuit can be recognized by the first evaluation circuit. From the degree of Detuning can be a value for determines the humidification of the first or second surface of the window pane become.

such Means for humidification detection, for example, as so-called Rain sensors used. As soon as rainfall on the surface of the Windshield, d. H. falls on the first surface of the window pane is this detected and a windshield wiper driven to the disc to wipe freely. However, it can happen that due to a increased Indoor humidity precipitation on the second surface of the Windshield, d. H. on the second facing the interior surface the windshield is formed. Also this rainfall would be the wiper trigger. It can therefore come to a so-called mischief, because after the statement of the device for humidification detection humidification the windshield is detected, although only the windshield on their inner surface is fogged. Such mischief is undesirable.

Of the The invention is therefore based on the problem, a device of to improve the aforementioned type so that mischief is omitted.

ADVANTAGES OF INVENTION

These Task is inventively characterized solved, that the device has a second means for moistening detection comprising at least one moisture-sensitive element that has outside the window pane is arranged on a second side of the window pane is. This second means for moistening recognition recognizes the Moistening or at least the likelihood of moistening the second surface the windowpane. The values determined by the second means for the Humidification or the probability of humidification the second surface are independent from moistening the first surface of the windowpane. Considered the values of humidification of the second surface thus obtained can be determined sure statement about make a moistening of the first surface. The one from the first Means for moistening detection provided erroneous value on the Humidification of the first surface can by means of the value for the moistening of the second surface, that of the second agent for humidification detection is corrected.

According to the invention For example, the second means for detecting moisture may be a temperature sensor element for detecting the temperature on the second surface of Include window.

Further Is it possible, that the second means for humidification recognition a second evaluation circuit includes.

The first evaluation circuit and the second evaluation circuit can by a common evaluation circuit are formed.

The inventive device Advantageously has an output, the device with a control device for a Windscreen wiper for transmission an information about the moistening of the first surface of the window pane can be twisted is. about the same output can also be advantageous information about the Humidification of the second surface to a climate control unit to be delivered.

through the second evaluation circuit can be the humidification or the probability the humidification determined on the second surface of the window be while by means of the first evaluation circuit, the humidification on the first surface of the Window is detected, this of the first evaluation circuit determined value possibly due to moistening of the second surface falsified is.

According to a method for generating a determined information about the moistening on a first side of the surface of a windowpane, the value of the determined moistening of the first surface can be compared with at least one threshold value, which value is at least one threshold value from the determined moistening of the second surface depends. The information that can be transmitted via the output to a control unit and / or the determined moistening of the first and / or the second surface can be present as two- or multi-level or continuous signals.

According to a further method for generating a with information that can be transmitted about the moistening on a first surface of the window pane, for generating the communicable information according to the following equation from the determined moistening of the first surface can be determined: i = b 1 - f (b 2 ) * K.

DRAWINGS

One embodiment for the inventive device for moistening detection on a first surface of a Window on a first side of the same is based on the drawings described in more detail. It shows

1 a schematic cross-section through part of a window pane and the device according to the invention,

2 a block diagram of the device according to the invention and

3 possible signal curves of a determined moistening on a second surface of the window pane and of a threshold value for determining the transmissible information about the moistening on the first surface of the window pane.

DESCRIPTION THE EMBODIMENTS

The device according to the invention is suitable for providing information about the moistening of the first surface 31 the windowpane 3 to create. The first surface 31 the windowpane 3 is the surface, the first page 1 is aligned. It may be, for example, the outer surface of a motor vehicle windshield.

The device according to the invention for moistening detection has a first means for moistening detection, with which the moistening on the first surface 31 can be determined. This first means for humidification detection comprises a resonant circuit 41 that between two layers of the windowpane 3 is embedded. This resonant circuit 41 is caused by a moistening on the first surface 31 tune. The detuning of the resonant circuit 41 is from a first evaluation circuit 42 evaluated in order to convey the moistening of the first surface. Unfortunately, it is systemic, however, that not just a change in humidity on the first surface 31 to a detuning of the resonant circuit 41 leads. Also a change of humidification on a second surface 32 the window pane leads to a detuning of the resonant circuit. This second surface 32 is to a second page 2 it may be, for example, the inwardly facing surface of a windshield of a motor vehicle. Such humidification of the second surface 32 can come about, for example, in the case of a motor vehicle by fogging due to the interior humidity in the passenger compartment of the motor vehicle. However, moistening on the second surface falsifies the result of the moistening on the first surface 31 , The one of the first evaluation circuit 42 determined moistening value for moistening the first surface 31 is thus corrupted.

According to the invention, this problem is solved by the fact that the device according to the invention has a second means for moistening detection. This second humidification detection means may be a prior art system for detecting moisture deposition on the inside of a motor vehicle windshield. Second means for moistening detection of moistening on the second surface 32 the windowpane 3 has at least one moisture-sensitive element 44 on, not inside the windowpane 3 is arranged. With this moisture-sensitive element 44 can either the moisture on the second surface 32 the windowpane 3 be recognized immediately. But it is also possible that only the moisture in the interior of the motor vehicle is detected. With a humidity-sensitive element thus arranged, together with a temperature sensor located on the second surface 32 the windowpane 3 is arranged, the humidification or the probability of moistening the second surface 32 be determined.

From moistening b _{1 of} the first surface 31 and moistening b _{2 of} the second surface 32 For example, humidification information may be generated which is given to a controller, for example, to control a windshield wiper. The information is determined in the present case so that the humidification b _{1 of} the first surface 31 is compared with a threshold s. This threshold s depends on humidification b ₂ on the second surface 32 from. It is possible that the value for the humidification b _{2 of} the second surface is present as yes / no, ie as a two-stage value indicating whether or not there is moistening. If such a two-stage value for the humidification b _{2 of} the second surface is present, then, as soon as humidification is present, the threshold value s can be raised by a certain amount. This connection is in the with 1 designated curves in the 3 shown. Alternatively, the value of the humidification b _{2 of} the second surface 32 also present as a continuous signal. In response to this continuous humidification signal b _{2 of} the second surface, the threshold can then be changed continuously. This connection is in the 3 by the reference numeral 2 marked curves shown.

Claims (10)

Device for moistening detection on a first surface ( 31 ) a window pane ( 3 ) on a first page ( 1 ) thereof, comprising a first means for detecting moisture, wherein said first means for detecting moisture comprises a capacitive structure, preferably a resonant circuit ( 41 ), which within the window pane ( 3 ), and a first evaluation circuit ( 42 ), which is outside the window pane ( 3 ), characterized in that the device comprises a second means for moistening detection, which comprises at least one moisture-sensitive element ( 44 ), which outside the window pane ( 3 ) on a second page ( 2 ) of the window pane is arranged. Apparatus according to claim 1, characterized in that the second means for humidification recognition a temperature sensor element ( 43 ) for detecting the temperature on a second surface ( 32 ) of the window pane ( 3 ). Apparatus according to claim 1 or 2, characterized in that the second means for humidification recognition, a second evaluation circuit ( 45 ). Apparatus according to claim 3, characterized in that the first evaluation circuit ( 42 ) and the second evaluation circuit ( 45 ) are formed by a common evaluation circuit. Device according to one of claims 1 to 4, characterized in that the device has an output ( 46 via which the device is provided with a windscreen wiper control unit for transmitting information about the wetting of the first surface ( 31 ) of the window pane ( 3 ) is connectable. Device according to one of claims 1 to 5, characterized in that by means of the second evaluation circuit ( 45 ) the humidification (b ₂ ) or the probability of humidification (b ₂ ) on the second surface ( 32 ) of the window pane ( 3 ) can be determined. Apparatus according to claim 6, characterized in that by means of the first evaluation circuit ( 42 ) the moistening (b ₁ ) on the first surface ( 31 ) of the window pane ( 3 ) can be determined. Method for generating a transferable information (i) via moistening (b ₁ ) on a first surface ( 31 ) a window pane ( 3 ) with an apparatus according to claim 7, characterized in that for generating the transferable information (i) the determined moistening (b ₁ ) of the first surface ( 31 ) is compared with at least one threshold value (s), wherein said at least one threshold value (s) of the determined moistening (b ₂ ) of the second surface ( 32 ) depends. A method according to claim 8, characterized in that the information (i) and / or the determined humidification (b ₁ , b ₂ ) are two- or multi-stage or analog signals. Method for generating a transferable information (i) via moistening on a first surface ( 31 ) a window pane ( 3 ) with an apparatus according to claim 7, characterized in that for generating the transferable information (i) as follows from the determined moistening (b ₁ ) of the first surface ( 31 ) and the determined moistening (b ₂ ) of the second surface ( 32 ) be determined, i = b1 - f (b 2 ) * K, where k is a suitable proportionality factor.