DE10147182C1 - Rain sensor for motor vehicle windscreen wiper control, has holder for transmitter and receiver in form of housing in which they are arranged with variable distance between them - Google Patents

Abstract

The device has a first transmitter (2) for transmitting a beam, primarily at a threshold angle for total reflection at a medium transition between glass and air at the transparent panel, a receiver (3) for receiving at least part of the transmitted beam and a holder for the transmitter and receiver in the form of a housing (4) in which they are arranged so that a variable distance between them is possible.

Description

The present invention relates to a rain sensor according to the Preamble of claim 1.

The use of rain sensors in the automotive field, for example for controlling windshield wipers is well known.

For example, DE 40 06 174 C1 is a rain sensor known, according to the physical principle of total reflection is working. Here light, mainly in the infrared range, is emitted by one Transmitter is emitted, the light beam being so on the windscreen of a car is directed that in the case of a dry windscreen total reflection takes place at the glass-air transition and the Light beam with its entire intensity, here over one further deflecting mirror is directed to a receiver, whereby a reference value for a dry slice can be set. Because the critical angle for total reflection from the media transition is dependent, there is no total reflection in the case of dripped water, but a split into a reflected and a broken one Beams of light take place, their ratio measured by the receiver can be.

From US 3,947,131 is a rain sensor of the type mentioned Kind known, which also works on the principle of total reflection works, the transmitter and the receiver each on separate Locations of the disc can be attached, for example, the Use the entire reflection path of the windshield can.  

However, as already indicated, the way this works depends Arrangement of the angle of incidence or exit of the light beam on the Media transition from glass to air or glass to water. Hence arise at a constant critical angle for total reflection, for different slice thicknesses also different Impact points of the light beam after total reflection.

However, it proves to be disadvantageous in the case of existing designs of rain sensors that these by a predetermined distance between transmitter and receiver to a certain slice thickness are set. Especially in vehicles with armored Disks are equipped, but come much stronger Discs are used so that rain sensors according to the state of the Technology cannot be applied. But also with commercially available car glass panes come in different strengths used, which means that there is a different one for each type of disc Rain sensor results.

The object of the present invention is therefore in Providing a rain sensor that is universal to everyone Slice thickness is applicable.

This task is carried out by a rain sensor with the characterizing features of claim 1 solved. Through the Use of a rain sensor, which is designed as a housing Includes recording device in which the transmitter and the receiver are arranged such that a variable spacing between If the transmitter and receiver are possible, the rain sensor can be customized can be adapted to the thickness of the pane.  

The housing and also the transmitter or receiver are advantageous equipped with corresponding clip connections, the one simple and detachable attachment of the transmitter or Ensure the receiver in the housing.

It also proves advantageous for openings emitted or received beams in the housing provided. These through openings are advantageous formed by light coupling and decoupling elements, which consist of a for IR Radiation transparent plastic are made.

It also has the advantage of interference-free detection light rays proved to be especially in the infrared range To use light as a beam of rays to be reflected.

Other features and advantages of the present invention will be clearly more preferred based on the following description Embodiments with reference to the accompanying Illustrations. Show in it

FIG. 1 shows an inventive rain sensor in a view from below;

FIG. 2 shows an inventive rain sensor in a top view;

FIG. 3 shows an inventive rain sensor on a disk mounted in a lateral view;

Fig. 4 is a schematic diagram for operation of a rain sensor;

Fig. 5 is a schematic diagram of the problem with a thicker pane and a rain sensor according to the prior art.

First, reference is made to FIG. 1.

A rain sensor 1 according to the invention essentially comprises a housing 4 , a transmitter 2 and a receiver 3 . The transmitter 2 is essentially a light source which can emit a light beam, primarily in the infrared range, at a certain angle and with a certain diameter. The transmitter emits the light beam at a certain angle, the so-called critical angle of total reflection, onto a glass pane 7 , so that in the case of the dry pane 7 it is reflected toward the receiver 3 . If the pane 7 is wetted with water, the critical angle of the total reflection changes due to the new glass-water media transition. In this case only part of the light beam is reflected, whereas the other part is refracted. The resulting change in the light intensity can be determined by the receiver 3 and, for example, a windshield wiper motor can be controlled. However, if the thickness of the pane 7 changes , the light beam, with otherwise constant boundary conditions, cannot hit the receiver, as shown in FIGS. 4 and 5.

For this purpose, the housing 4 is equipped with fastening catches 11 which can accommodate different transmitters 2 or 3 receivers. The transmitters 2 or receivers 3 differ in the distance between the emitted light beam and the light beam received by the receiver 3 , which is created by clipping these components into the housing 4 .

Thus, with a housing 4 , different window thicknesses can be checked for their surface wetting with, for example, rain water. In addition, passage openings 6 are provided on the rear of the housing for the passage of the light beam. These passage openings are advantageously formed by light coupling and decoupling elements which are made of a plastic which is transparent to IR radiation.

In addition, the rain sensor is equipped with a socket 5 , which can be used for power supply and for querying the sensor information.

Claims (4)

1. Rain sensor ( 1 ) for detecting the degree of wetting of a transparent pane ( 7 ) with drop-shaped precipitation, primarily for detecting the onset of rain and controlling a windshield wiper control of a motor vehicle, comprising a first transmitter ( 2 ), which is used to emit a beam, primarily in one limit angle of total reflection on the transparent pane ( 7 ), determined by the media transition between glass and air, is suitable and a receiver ( 3 ) which is suitable for receiving at least a part of the emitted radiation beam, a receiving device (housing 4 ) for the transmitter ( 2 ) and the receiver ( 3 ) is provided, characterized in that the receiving device is designed as a housing ( 4 ) in which the transmitter ( 2 ) and the receiver ( 3 ) are arranged such that a variable spacing between the transmitter ( 2 ) and receiver ( 3 ) is possible. 2. Rain sensor according to claim 1, characterized in that the transmitter ( 2 ) and receiver ( 3 ) can be connected to the housing ( 4 ) via fastening catches ( 11 ). 3. Rain sensor according to claim 1 or 2, characterized in that the housing ( 4 ) is equipped with through openings ( 6 ). 4. Rain sensor according to one of claims 1 to 3, characterized characterized that the beam of rays is Rays of light, primarily in the area of infrared light is.