DE19700665C5 - Sensor for detecting foreign material and windshield wiper system with sensor for detecting foreign material, especially raindrops - Google Patents

Abstract

Sensor for the detection of foreign material on a transparent wall (17), the sensor comprising a camera device (21) passing through this wall (17) an image of a position at a distance from it on the side of the wall (17) opposite the camera device (21). 17) arranged object (15), and has a detection device (23) connected to the camera device (21), which receives the image of the object (15) from the camera device (21) and contains a memory (27) which contains a basic image of the object (15) in the event that the wall (17) is free of foreign material, the detection device (23) storing the basic image stored in the memory (27) with the image of the object (15) by the camera device (21) is compared to determine the presence of foreign material on this wall (17), characterized in that the object (15) is a non-self-illuminating object that emits light End element (16), which the light into the object ...

Description

The present invention relates on sensors for detecting foreign material, such as raindrops falling on a windshield of a vehicle, and a windshield wiper system that detects foreign matter.

When raindrops fall on the windscreen of a vehicle, a driver usually operates the wipers by hand to match the raindrops to the speed of the car and eliminate with the amount of falling rain. To such Manual controls unnecessary make facilities for detecting the presence of raindrops proposed. Windshield wipers are included Raindrop sensors, which detect the amount of rain. The time interval between wiping cycles of the wipers is doing in accordance adjusted with the amount of rain.

So far, a capacitance sensor, a vibration sensor and a photo sensor alongside other sensors for Determine the amount of raindrops used. The capacitance and vibration sensors detect the amount of raindrops in a predetermined Impact the area of the windshield and indicate the amount Appropriate detection signals from raindrops. The photo sensor detects changes the light radiation that passes through a predetermined area of the windshield falls. Such changes are from foreign material, such as falling on the windshield and rain absorbing light radiation. However is the area of the windshield associated with the capacity, vibration or photo sensor is covered, not the area primarily by the driver is used. Because of this, the driver may be able to perform the desired wiper movement do not reach.

Such raindrops can further Detecting wiper systems do not exactly determine whether the foreign material on the windshield really consists of raindrops. Further are such windshield wiper systems for the precise determination of Amount of raindrops unsuitable. This results in an automatic Control of wiper movement that is as good as manual Control of driving is trouble.

In the DE 4417 385 A1 It is proposed to use a CCD camera to record raindrops on the windshield and to use a pattern identifier to decide whether it is necessary to switch on the windshield wiper due to the amount of rain. The wipers are then switched on automatically.

The structure according to another document US 4,476,419 uses simple photo sensors and photo diodes located outside the driver's cab, which are aimed at the photo sensors with collimating optics. These can be used to identify a somewhat rough spatial resolution on the windshield and to use pattern recognition to decide whether a windshield wiper actuation should be initiated automatically.

From the JP 59-199347 A (Patent Abstracts of Japan, Vol. 9, No. 67 (M-366)) discloses a windshield wiper control device in which a windshield wiper in a vehicle is automatically switched on when a detection device detects that the windshield is dirty. In the process, a camera arranged inside the vehicle detects an image of the hood or an infrared lamp (not switched on) through the windshield of the vehicle during the day, a microcomputer processing the image recorded by the camera and. evaluates. This picture is used to determine whether the windshield is dirty by comparing it to an image with the windshield not contaminated. If this is the case, the wiper is triggered. In this mode, the well-known system works during the day. At night the infrared lamp is switched on and the picture of the switched on infrared lamp is recorded by the camera and a brightness number is calculated from the picture taken. Since the brightness of the image is altered by contamination or raindrops on the windshield, the calculated brightness is compared to a threshold to determine whether the windshield is dirty or not. If the windscreen is dirty, the windscreen wiper is operated. This known system is complicated and cumbersome and complex to implement.

The object of the invention is a another sensor for detecting foreign material and an improved one To provide wiper system.

The task is done by a sensor according to one System and a device according to the independent claims solved. preferred Further developments are specified in the subclaims.

According to the invention, the sensor detects foreign material on a transparent wall. The sensor has a camera device to capture an image through this wall one from this wall spaced, non-self-illuminating object that emits light Has element that feeds light into the object, object and a detection device connected to the camera device on. The detection device receives the image of the object from the camera device and uses it to assess whether foreign material is present on the wall.

According to a further training according to the invention the system detects foreign material on a windshield and drives a wiper. The system particularly points a sensor with a camera device and a detection device as well as a drive device.

The camera device captured by the windshield is a non-luminous object that is spaced is located from the windshield and forms an image of it Object. The detection device is connected to the camera, receives the image from the camera device and judged on the basis of this, whether there is any foreign material on the windshield. The drive device drives the wipers when based on the assessment of the sensor shows that Foreign material is on the windshield.

The present invention can be found in in many ways, both as a device and as a method, be realized. Other developments and advantages of the invention will be apparent from the following description in conjunction with the accompanying drawing clarifies, which exemplifies the principles of the invention. The features of the invention can be found essentially in the appended claims. The invention along with its properties and advantages can but referring to the following description of an embodiment can be best understood together with the drawing.

Show it:

1 a schematic drawing of a raindrop sensor according to the invention, which is installed in a vehicle;

2A a schematic drawing of a CCD camera according to the raindrop sensor 1 is provided;

2 B an optical fiber attached to the hood of a vehicle;

3 an electrical block diagram schematically illustrating a windshield wiper system for detecting raindrops;

4A a drawing of a basic image pattern of the light guide;

4B a current image pattern of the light guide;

5A an enlarged view of a section of the basic image pattern of 4A ;

5B an enlarged view of a section of the current image pattern of 4B and

6 a drawing of a predetermined area of the windshield through which the CCD camera of a raindrop sensor takes a picture.

A raindrop sensor and a foreign material Detecting windshield wiper system is referred to below described on the drawing.

As in 1 is shown is a raindrop sensor 13 in the passenger compartment 11a of a vehicle 11 arranged and on a rearview mirror 12 attached. A light guide serving as an object 15 is on the hood 14 of the vehicle 11 arranged. The light guide is preferably located 15 central and near the front end of the hood 14 , However, the raindrop sensor must 13 not necessarily at the mirror 12 can be arranged and can also be installed in other places, such as on the dashboard. The raindrop sensor is preferably 13 however, positioned to have an area within the wiping area of a wiper 18 detected.

As in 2A and 2 B is shown, contains the light guide 15 a light guide made of acrylic resin 15A and a stand 15B that the light guide part 15A wearing. The light guide 15A contains a circular outer area and an inner area which is cut out in an X-shape. Furthermore, the light guide part 15A with its flat surface of the windshield 17 of the vehicle 11 facing. An infrared light emitting diode (LED 16 ) is in the center of the inner area of the light guide 15A embedded. A luminescence of the infrared LED 16 leads to the emission of infrared light rays from the entire light guide part 15A against the windshield 17 , This structure can also hold more than one infrared LED 16 be used. An LED with visible light can also be used instead of the infrared LED 16 be used. However, if an LED with visible light is used, a filter should preferably be placed in front of the CCD camera described later 21 be arranged to turn off stray light.

If infrared rays from the light guide 15 are emitted, the raindrop sensor receives 13 infrared radiation passing through a predetermined area F ( 6 ) the windshield 17 penetrates and into the passenger compartment 11A incident. The raindrop sensor 13 then generates image data from the light guide and assesses whether raindrops are present on the windshield. The raindrop sensor 13 also detects the amount of raindrops and emits a corresponding signal. The movement of the wiper 18 is controlled so that the foreign material or the raindrops from the windshield 17 be removed. In addition to raindrops, the foreign material can contain snow, ice, dew, sand (dust) and small dirt particles such as leaves.

As in 3 is shown, the windshield wiper system which detects raindrops contains a raindrop sensor 13 , a drive circuit 31 , a wiper motor 32 and the wiper 18 , The raindrop sensor 13 has a CCD (charged coupled devices) camera 21 , a tuning circuit 22 , an image pattern recognition circuit 23 who have favourited Infrared LED 16 and a modulatable driver circuit 24 for the LED on. As in 2A is shown is for the CCD camera 21 a lens 25 and a CCD 26 intended. The Lens 25 is designed for a focal length of approximately one meter. This will capture the CCD 26 the image of the light guide 15 on the CCD 26 while a pictures Detection of the surroundings of the vehicle 11 is largely excluded. Image recording systems such as phototransistor and photodiode arrays can also be used instead of the CCD 26 be used.

A monochrome CCD with 10,000 (100 × 100) pixels arranged in two dimensions can be used as a CCD 26 be used. The CCD 26 is for the absorption of infrared rays through the predetermined area F, the 50 mm × 50 mm area of the windshield in this exemplary embodiment 17 , fall through, over the lens 25 suitable. The area of area F is larger than the area covered by prior art raindrop sensors. Furthermore, the area F is within the wiping area of the wiper 18 certainly. After receiving the infrared rays from the light guide 15 have been emitted and passed through the predetermined area F, the CCD transmits 26 the image data signal from the light guide 15 to the tuning circuit 22 , The image data contain a number of pixel data corresponding to the number of pixels. The number of pixels for the CCD 26 and the area of the predetermined area F can be changed if necessary.

The modulation circuit 24 as a driver for the LED, the infrared LED is triggered within a predetermined time interval 16 to glow when receiving luminescence control signals from the image pattern recognition circuit described later 23 receives. The modulation circuit 24 also sends luminescence signals for the glow of the infrared LED 16 to the tuning circuit 22 , While the infrared LED 16 lights up, sends the modulation circuit 24 Luminescence signals at high potential for the tuning circuit 22 ,

When the high potential luminescence signals from the modulation circuit 24 are sent out, transmits the voting circuit 22 the data signals from the CCD camera 21 to the image pattern recognition circuit 23 , The detection circuit 23 has a memory 27 in which a basic pattern P1 of the light guide 15 is saved. The basic pattern P1 corresponds to an image pattern for the light guide 15 that in the CCD camera 21 is formed when the windshield 17 is completely free of raindrops, such as in 4A is shown. The basic pattern P1 is constructed from a large number of pixel data. Each pixel date corresponds to one pixel of the CCD 26 and contains luminescence data.

The detection circuit 23 receives the image data signals from the tuning circuit 22 , The detection circuit recognizes on the basis of the data signals 23 a current image pattern P2 of the light guide 15 , each from the CCD 26 ( 4B ) was recorded. The current pattern P2 is made up of a large number of pixel data and is in the memory 27 stored. The detection circuit 23 confirms whether the current pattern P2 data of a current image of the light guide 15 contains by referring to a luminescence data value in each pixel. In other words, if the value of the luminescence date is greater than the value of a predetermined reference luminescence K ₀ , the recognition circuit determines 23 that the current pattern P2 contains data for a current image acquisition. The reference luminescence K ₀ indicates the luminous value for which the detection circuit 23 a suitable evaluation of the image data from the light guide 15 can make. The value of the reference luminescence K ₀ can be determined by a switch field 23A can be changed by operating input switches, not shown. The input value of the reference luminescence K ₀ is in the memory 27 stored. The reference luminescence K ₀ can be changed to suppress the influence of stray light on the CCD.

The detection circuit 23 compares the basic pattern P1 with the current pattern P2. In particular, the detection circuit compares 23 the data of each pixel of the current pattern P2 with the data of the corresponding pixel of the basic pattern P1 and calculates the number of pixels that match or substantially match.

5A shows an enlarged diagram which shows a section A of the basic pattern P1. 5B shows an enlarged diagram of section B of the current pattern P2. In 5A circles for pixel data are drawn in, which form part of the basic pattern P1. In 5B circles and crosses are shown for pixel data that are part of the current pattern P2. In 5B a double broken line surrounds a pixel group G1, the data of which essentially coincide with the pixel data of the basic pattern P1. In contrast, the pixel data of the data group G2 do not match the pixel data in the basic pattern P1. This is caused by raindrops falling on the windshield 17 have fallen.

A disturbance or deformation of the current pattern P2 arises when raindrops fall on the windshield 17 fall. The disturbance reduces the number of pixel data which essentially coincide between the basic pattern P1 and the current pattern P2. That is, the number of non-matching pixels is increased. If the number of substantially matching pixels is relatively small, it is decided that raindrops will fall on the windshield 17 have fallen.

A threshold value S ₀ is set on the control panel 23 entered into the detection circuit and in memory 27 stored. The threshold value S ₀ is a reference value for assessing the amount of raindrops on the windshield 17 , that is, the transparency of the windshield 17 , The threshold value S ₀ determines the number of matching pixels for a state in which the Re Gene drops on the windshield 17 lower visibility to the front and controls the driver to operate the wiper 18 , The threshold value S ₀ is determined experimentally.

The detection circuit 23 compares the number of matching pixel data or a match value S with the threshold value S ₀ and determines the amount of raindrops on the windshield 17 or visibility through the windshield 17 , If the match value S is greater than the threshold value S ₀ , the detection circuit decides 23 that there are no raindrops or that the amount of raindrops is relatively small. The detection circuit 23 then sends a detection signal that indicates the condition of the windshield (raindrops relatively low) 17 indicates to the driver circuit 31 ,

If the match value S is equal to or less than the threshold value S ₀ , the detection circuit determines 23 that a relatively large amount of raindrops on the windshield 17 has fallen, and sends a detection signal indicating the condition of the windshield 17 (relatively many raindrops) indicates to the driver circuit 31 , Instead of the matching value S, which indicates the number of matching pixels, the number of non-matching pixel data between the basic pattern P1 and the current pattern P2 can also be used to decide the transparency. In this case, a decision is made for a large amount of falling raindrops if the number of mismatched pixel data is greater than a predetermined threshold value.

The driver circuit 31 drives the wiper motor 32 depending on the detection signal indicating the presence of a large amount on the windshield 17 fallen raindrops. The wiper motor 32 is a sensor 33 , for example a limit switch, for the rest position for detecting a reference position of the wiper 18 connected. The sensor 33 for the rest position is with the detection circuit 28 connected, detects the position of the wiper 18 and sends a position signal to the detection circuit 28 , The driver circuit 31 and the wiper motor 32 form a wiper drive circuit.

The driver circuit 31 is on a manually operated switch 34 and an automatic switch 35 connected, both in the passenger compartment 11a are arranged. The manually operated switch 34 corresponds to the normal wiper control switch used by the driver to move the wiper 18 is operated. The automatic switch 35 when the wipers 18 automatically depending on the detection signal from the raindrop sensor 13 is to be moved.

When the weather is clear, the raindrop sensor may 13 a current pattern due to scattered rays 2 incorrectly recognizes, even if there are no raindrops on the windshield 17 are located. This results in unnecessary wiping using the windshield wiper 18 , In this case, the influence of scattered rays can be adjusted by setting the reference luminescence K ₀ on the control panel 23a can be reduced so that an accurate recognition of the current pattern P2 is possible. The detection accuracy of the raindrop sensor 13 To improve, is preferably the oil film that is on the windshield 17 forms, eliminates.

In the present invention, this creates within the passenger compartment 11a of the vehicle 11 provided CCD camera 21 Image data of the light guide 15 and determined the amount of raindrops falling on the windshield 17 have fallen. This will drop raindrops alongside foreign material onto the windshield 17 falls exactly different from other material. The number of raindrops can also be determined. Correspondingly, the transparency of the windshield 17 be determined from the results obtained.

The image acquisition of the light guide 15 through the CCD camera 21 simulates the condition in which a driver goes through the windshield 17 sees. Accordingly, a reference to those made possible by the CCD camera 21 image data obtained an assessment of the transparency of the windshield 17 , including the amount of raindrops on the windshield 17 is proven. Next is the raindrop sensor 13 located near the driver's point of view. This can reduce the transparency of the windshield 17 at a position close to the driver. In other words, the driver's field of vision is through the windshield 17 and the predetermined area F on the windshield 17 is substantially coincident with each other. This allows the transparency of the windshield to be determined 17 regarding the driver's field of vision.

The comparison between the basic pattern P1 and the current pattern P2 allows an exact assessment of the amount of raindrops. The calculation of the match value S, which is obtained by comparing the data from each pixel of the current pattern P2 with that of the basic pattern P1, allows the transparency of the windshield to be determined 17 , The comparison between the agreement value S and the threshold value S ₀ facilitates the assessment of the transparency of the windshield 17 (ie an assessment of the need to windshield 17 to wipe). Instead of a single threshold value S ₀ , more than one threshold value can also be used. A variety of threshold values allows the number of raindrops on the windshield 17 to be determined in stages. In this case, the wiper 18 are controlled so that the time interval between each wiping operation in intermittent operation or the wiping speed are changed in accordance with the amount of raindrops taken up. For example, if the amount of raindrops on the windshield 17 increased, the interval between each wipe of the wiper 18 can be controlled so that the interval between each wipe is reduced or the wiping speed is increased by the raindrops on the windshield 17 to eliminate immediately.

Although here is only one embodiment of the invention, it should be understood by those of ordinary skill in the art be clear that the present invention also in many other specific forms accomplished can be without deviated from the nature or scope of the invention. In particular The present invention can also be implemented in the following embodiments be realized.

The wiper that detects raindrops according to the invention can be used on a rear window as well as on the front windshield 17 be used.

The light guide 15a is not limited to the form described above, but can also be carried out in any other form. In this regard, the light guide part 15a , especially to improve the raindrop detection sensitivity, a relatively complicated shape in accordance with the total number of pixels in the CCD camera 21 or the resolution of the camera 21 to have. For example, the light guide part 15a have a plurality of notches, cracks and / or pins or the like on its circumference.

Therefore, the examples shown are and embodiments only to be regarded as purely illustrative and not as restrictive. The invention is therefore not limited to the details given above, but may be modified within the scope of the appended claims.

Claims (17)

Sensor for the detection of foreign material on a transparent wall ( 17 ), the sensor being a camera device ( 21 ) through this wall ( 17 ) an image of a in a position spaced from this on that of the camera device ( 21 ) opposite side of the wall ( 17 ) arranged object ( 15 ) and one to the camera device ( 21 ) connected detection device ( 23 ) that the image of the object ( 15 ) from the camera device ( 21 ) receives and a memory ( 27 ) that contains a basic image of the object ( 15 ) in case the wall ( 17 ) is free of foreign material, the detection device ( 23 ) that in the memory ( 27 ) stored basic image with the image of the object ( 15 ) by the camera device ( 21 ) is compared to the presence of foreign material on this wall ( 17 ), characterized in that the object ( 15 ) is a non-self-illuminating object that contains a light-emitting element ( 16 ), which the light into the object ( 15 ) feeds. Sensor according to claim 1, characterized in that the image of the object ( 15 ) and the basic image are each formed by a large number of pixel data, the detection device ( 23 ) the large number of pixel data of the image from the object ( 15 ) with the multiplicity of pixel data of the basic image and then calculates a value for the number of pixel data which essentially match in order to decide whether foreign material is on the wall ( 17 ) is available. Sensor according to claim 2, characterized in that the detection device ( 23 ) compares the value of the number of essentially matching pixel data with a predetermined first threshold value and the presence of foreign material on this wall ( 17 ) determines if the value of the number of substantially matching pixel data is equal to or less than the predetermined first threshold value. Sensor according to claim 3, characterized in that a control panel ( 23a ) is provided for changing the predetermined first threshold value. Sensor according to claim 1, characterized in that the image of the object ( 15 ) and the basic image is formed by a large number of pixel data, the detection device ( 23 ) the large number of pixel data of the image of the object ( 15 ) with the large number of data of the basic image and then calculates a value for the number of essentially inconsistently matching pixel data in order to determine the presence of foreign material on the wall ( 17 ) to determine. Sensor according to claim 5, characterized in that the detection device ( 23 ) compares the value indicating the number of non-matching pixel data with a predetermined second threshold value and determines whether foreign material is on the wall ( 17 ) is present if the number of mismatched pixel data is equal to or greater than the predetermined second threshold value. Sensor according to claim 6, characterized in that a control panel ( 23a ) intended is to change the predetermined second threshold. System for detecting foreign material on a windshield ( 17 ) and to drive a wiper ( 18 ), the system comprising a sensor with a camera device ( 21 ) and with a detection device ( 23 ) and a drive device ( 31 . 32 ) comprises the camera device ( 21 ) through the windshield a distance from the windshield that is not self-illuminating and is opposite the camera device ( 21 ) lying object ( 15 ), which is a light-emitting element ( 16 ), which the light into the object ( 15 ) feeds in, takes a picture of the object ( 15 ) is generated, furthermore the detection device ( 23 ) with the camera device ( 21 ) is connected, the image from the camera device ( 21 ) receives and a memory ( 27 ) that contains a basic image of the object ( 15 ) in the event that the windshield ( 17 ) is free of foreign material, and that in the memory ( 27 ) stored basic image with the image of the object ( 15 ) by the camera device ( 21 ) is compared to the presence of foreign material on the windshield ( 17 ) and the drive device ( 31 . 32 ) the wiper ( 18 ) drives when the sensor detects the presence of foreign material on the windshield ( 17 ) has detected. System according to claim 8, characterized in that the image of the object ( 15 ) and the basic image are each formed by a large number of pixel data, the detection device ( 23 ) the large number of pixel data of the image of the object ( 15 ) with the plurality of pixel data of the basic image and then calculates a value for the number of pixel data that match essentially coincidentally in order to decide whether foreign material is present on the windshield. System according to claim 9, characterized in that the detection device ( 23 ) compares the value indicating the number of substantially matching pixel data with a predetermined first threshold value and determines the presence of foreign material on this windshield if the value indicating the number of substantially matching pixel data is equal to or less than that predetermined first threshold value. System according to claim 10, characterized in that the sensor further comprises a control panel ( 23a ) for changing the predetermined first threshold value. System according to claim 8, characterized in that the image of the object ( 15 ) and the basic image is formed by a large number of pixel data, the detection device ( 23 ) the large number of pixel data of the image of the object ( 15 ) with the large number of data of the basic image and then calculates a value for the number of essentially inconsistently matching pixel data in order to determine the presence of foreign material on the windshield. System according to claim 12, characterized in that the detection device ( 23 ) compares the value for the number of non-matching pixel data with a predetermined second threshold value and determines whether there is foreign material on the windshield if the value for the number of non-matching pixel data is equal to or greater than the predetermined second threshold value. System according to claim 13, characterized in that the sensor further comprises a control panel ( 23a ) in order to change the predetermined second threshold value. System according to one of claims 8 to 13, characterized in that the object ( 15 ) on the front of a vehicle ( 11 ) is arranged and the sensor inside the vehicle ( 11 ) near a rearview mirror ( 12 ) is arranged so that the camera device ( 21 ) the object ( 15 ) through the windshield ( 17 ) of the vehicle ( 11 ) can capture. Device for detecting raindrops and other foreign material on the windshield of a vehicle ( 11 ), the device being a non-self-illuminating, a light-emitting element ( 16 ) object ( 15 ) near the front of the vehicle ( 11 ) on one of the windshield ( 17 ) spaced position, a sensor ( 13 ) with a camera ( 21 ) in the interior of the vehicle and a detection device ( 23 ), the camera ( 21 ) takes an image of the object through the windshield and the image as a data record to the detection device ( 23 ) which compares the data of the image obtained from the camera with a data record representing a reference image and judges on the basis of the number of essentially matching data whether foreign material is present on the windshield. Apparatus according to claim 16, characterized in that this image taken by the camera and the reference image by a Variety of data points are formed.