Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60S—SERVICING, CLEANING, REPAIRING, SUPPORTING, LIFTING, OR MANOEUVRING OF VEHICLES, NOT OTHERWISE PROVIDED FOR
  • B60S1/00—Cleaning of vehicles
  • B60S1/02—Cleaning windscreens, windows or optical devices
  • B60S1/04—Wipers or the like, e.g. scrapers
  • B60S1/06—Wipers or the like, e.g. scrapers characterised by the drive
  • B60S1/08—Wipers or the like, e.g. scrapers characterised by the drive electrically driven
  • B60S1/0818—Wipers or the like, e.g. scrapers characterised by the drive electrically driven including control systems responsive to external conditions, e.g. by detection of moisture, dirt or the like
  • B60S1/0822—Wipers or the like, e.g. scrapers characterised by the drive electrically driven including control systems responsive to external conditions, e.g. by detection of moisture, dirt or the like characterized by the arrangement or type of detection means
  • B60S1/0833—Optical rain sensor
  • B60S1/0844—Optical rain sensor including a camera
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/55—Specular reflectivity
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60S—SERVICING, CLEANING, REPAIRING, SUPPORTING, LIFTING, OR MANOEUVRING OF VEHICLES, NOT OTHERWISE PROVIDED FOR
  • B60S1/00—Cleaning of vehicles
  • B60S1/02—Cleaning windscreens, windows or optical devices
  • B60S1/04—Wipers or the like, e.g. scrapers
  • B60S1/06—Wipers or the like, e.g. scrapers characterised by the drive
  • B60S1/08—Wipers or the like, e.g. scrapers characterised by the drive electrically driven
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/55—Specular reflectivity
  • G01N21/552—Attenuated total reflection
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
  • G06V20/00—Scenes; Scene-specific elements
  • G06V20/50—Context or environment of the image
  • G06V20/56—Context or environment of the image exterior to a vehicle by using sensors mounted on the vehicle
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
  • G01N21/43—Refractivity; Phase-affecting properties, e.g. optical path length by measuring critical angle
  • G01N2021/435—Sensing drops on the contact surface

Definitions

• the invention relates to an apparatus and a method for detecting raindrops on a pane by means of a light source and a camera.
• WO2010 / 072198 A1 describes rain detection with the aid of a camera, which is used for automotive driver assistance functions.
• a bifocal optics is used, which images a portion of the windshield sharply on a partial surface of the image chip or image sensor of the camera.
• a disadvantage of this idea is that an additional optical element is introduced whose edge causes considerable disturbances both in the beam path for the rain sensor region of the image chip and in the region for the driver assistance functions in the vicinity of the edge.
• the focus conditions for the driver assistance area and the rain sensor area are very different, which must be compensated for by an increased thickness of the optical element and thereby increased interference and a wide, unusable area on the image chip around the edge leads .
• WO 2010/072198 A1 In order to be able to recognize raindrops at night, it is proposed in WO 2010/072198 A1 to couple light via a coupling element into the windshield and to guide it via total reflection in the windshield. Through a decoupling element, the totally reflected light is coupled out in the direction of the camera. If there are drops of water on the windshield, part of the light is decoupled and no longer totally reflected to the decoupling element. Another disadvantage is that the integrated camera lighting unit is mechanically adapted to the changed installation conditions for every changed wheel tilt. In US Pat. No. 7,259,367 B2, a rain sensor is also proposed by means of a camera, which provides large-area illumination of the passage window of the camera opening angle with the window.
• the camera is focused almost at infinity and can therefore be used simultaneously for driver assistance applications. Because of the imaging on the far field, raindrops are only noticeable as disturbances in the image, which are detected by complex differential measurements of the images recorded in synchronization with the pixel clock pulsed or modulated light. Simulation calculations and measurements show, however, that in this type of lighting, only a very small proportion of the light at the raindrops is reflected back into the camera. This circumstance leads to a poor signal-to-noise ratio and consequently to an uncertain rain detection.
• the object of the present invention is to overcome the mentioned disadvantages of the devices or methods known from the prior art.
• a device for detecting rain which comprises a camera and a lighting source.
• the camera is placed behind a disk, in particular inside a vehicle e.g. behind a windshield, and focused on a distant area that lies in front of the disc.
• the camera preferably comprises a lens for focusing and an image sensor, e.g. a CCD or CMOS sensor.
• the illumination source for generating at least one light beam directed onto the pane directs the at least one light beam onto the pane such that at least one beam (or partial beam of the light beam directed onto the pane) from the outside of the pane impinges on the camera.
• the illumination source can be designed as one or more light-emitting diodes (LEDs) or as a light band.
• the amount of light of the at least one beam impinging on the camera can be measured by the camera.
• the invention provides a simple but reliable way to detect rain with a vehicle camera, in particular with a driver assistance camera. Since essentially only one quantity of light has to be measured, no complex image processing algorithm is necessary. Due to the active illumination, the device is relatively susceptible to external influences such as sun reflexes and shadows.
• the amount of rain can e.g. In the case of multi-beam illumination sources, a reduction in the amount of light in the light reflections (on the image sensor) of the outer windscreen and / or the number of light reflections affected are determined.
• the angle of incidence of the light beam generated by the illumination source is set so that more of the beam (portion) which strikes the outside of the disc than the disc is coupled out, if no rain on the outside the disc is.
• the device comprises an evaluation unit which determines from the measured amount of light of the beam reflected on the outside of the disk, if and if so, how much rain is present on the outside of the disk.
• the evaluation unit for rain detection can preferably compare the measured amount of light of the beam reflected on the outside of the pane with a threshold value.
• the threshold value can be changed in particular to a changed strength the illumination and / or adapted to a changed sensitivity of the camera, for example by regular calibrations with a dry disc. Also several thresholds can be used.
• the evaluation unit determines a temporal change of the light values, measured by the image sensor of the camera, of the beam reflected on the outside of the pane. For this, a sequence of pictures can be taken with the camera.
• the illumination source directs the at least one light beam onto the pane in such a way that the rays reflected from the inside and outside of the pane impinge on the camera as at least two spatially separated rays.
• the amounts of light of the at least two impinging on the camera beams can be measured by the camera in this case.
• This type of detection with the illumination proposed here is not necessarily dependent on a camera, but can be used by any optical sensor that can determine the amount of light from two spatially separated beams.
• the advantage of the detection method presented here in comparison to conventional diode rain sensors is based on the fact that no coupling optics is required and at the same time a reference beam for a comparison measurement is available.
• the camera is used for one or more additional driver assistance functions, which are based on an evaluation of the focussed distant range.
• the illumination source is structurally integrated into the camera or into the housing of the camera.
• the illumination source can preferably be arranged under a screen or a view funnel of the camera within the camera body.
• the illumination source advantageously generates light in the infrared wavelength range
• the viewing diaphragm is transparent in the infrared wavelength range, at least in a partial area which is located above the illumination source or in the beam direction of the illumination source.
• the illumination source can in this case be arranged in particular on a circuit carrier or a circuit board of the camera.
• the illumination source preferably only generates light having a wavelength in a specific wavelength range, for example in the (near) infrared wavelength range.
• a first spectral filter is arranged in the region in which run the at least two spatially separated reflected beams.
• the first spectral filter allows light of one wavelength to be SEM certain wavelength range at least largely by (eg infrared-transmissive).
• a second spectral filter is arranged in the area of the beam path in which the at least two spatially separated reflected beams do not run, the second spectral filter blocking light having a wavelength in the particular wavelength range (e.g., infrared cutoff filters).
• the first or both spectral filters can preferably be applied directly to pixels of the image sensor of the camera.
• the illumination source generates a collimated light beam.
• the light beam generated by the illumination source can be detected by means of a light guide, such as a light guide.
• a glass fiber to be directed to the disc.
• the invention further relates to a method for detecting rain on the outside of a disc.
• a prerequisite for this is also a camera arranged behind the pane, which is focused on a distant area in front of the pane, and an illumination source for producing at least one light ray directed onto the pane.
• the illumination source directs the at least one light beam onto the disk such that at least one beam reflected from the outside of the disk strikes the camera.
• the amount of light of the at least one beam reflected from the outside of the disk is detected by means of the camera. measure up. By evaluating the measured amount of light of the at least one beam reflected from the outside of the disk, rain on the outside of the disk can be detected.
• a preferred method for detecting rain on the outside of a pane uses a device according to the invention.
• the camera first takes a first picture with the illumination source switched off. Subsequently, a second image is taken with the illumination source switched on. The difference image from the second and first image is formed. In the differential image, the amount of light of the at least one reflected beam on the outside of the disc for the detection of rain on the outside of the disc is evaluated.
• a short visible light pulse adapted to the intensity of the external brightness. This would require only a short exposure time and image capture time for the rain sensor image, which in turn has little effect on the driver assistance function.
• Such a light pulse would be perceived in daylight only when looking directly at the lighting. At night, little light is needed for rain detection.
• the intensity can be regulated down accordingly, so that the lighting does not disturb at night.
• a preferred adjustment of the illumination intensity - regardless of the wavelength range used - brings a further advantage.
• the rain sensor light reflections are well visible even during the day and at night it is avoided that the images get saturated and thus a quantitative evaluation would be prevented.
• the illumination may be advantageous over individual light emitting diodes, e.g. arranged in series can be realized. It could alternatively be used a light band. Preferably, a sufficiently directed radiation characteristic of e.g. less than ⁇ 20 ° ensured.
• FIG. 1 shows schematically the basic principle of a possible arrangement of the illumination source and the camera with beam paths in the case of a dry pane
• FIG. 3 shows signals detected by an image sensor of a camera, which indicate rain
• Fig. 6 a shows a Bayer pattern as a filter pixel matrix
• Fig. 6b shows a modified Bayer pattern with a colorless filter pixel element
• FIG. 7 schematically shows an alternative arrangement of illumination source and camera, in which the illumination source is arranged on a circuit carrier below the viewing aperture of the camera;
• Fig. 8 shows schematically the changed beam paths of the alternative arrangement in the rain on the disk
• FIGS. 9 and 10 schematically show an additional possibility with the alternative arrangement of detecting rain by measuring a portion of the main beam of the illumination source which is reflected in the raindrop and which strikes the camera when it rains;
• Fig. 11 shows an arrangement in which the light from the illumination source is guided via a light guide to the disc.
• Fig. 1 illustrates the principle of operation of a first embodiment of the invention.
• the rain detection presented here is based on a far-field-focused camera (1) and illumination (3), which uses one or more focused beams (h) in contrast to the large-area illumination of US Pat. No. 7,259,367 B2.
• a light beam (h) generated by an illumination source (3) is directed onto the disc (2) in such a way that the light beam from the Inside (2.1) and outside (2.2) of the disc reflected rays as two spatially separated rays (r1, r2) impinge on the lens or the camera (1). Because of the focus on the far field, the border of the ray bundles is only imaged on the image chip (5). But both beams (r1, r2) are sufficiently separated and their respective amount of light can be measured with the image sensor (5).
• the main beam (h) of the illumination source (3) is used, therefore, the light of the illumination source may be preferably bundled.
• the portion (rl) of the main beam reflected at the air-disk interface (or disk inside (2.1)) serves as a reference beam. From the portion that is transmitted (tl) into the disk, the portion serves as measuring beam (r2), which is reflected at the disk-air interface (or disk outside (2.2)) and hits the camera (1). Not shown is the proportion of the beam, which is reflected several times within the disc (2) (on the inside (2.1) disc-air after it has been reflected on the outside (2.2) disc - air).
• This arrangement offers the advantage of a pronounced signal change in the presence of rain (4) on the outside of the pane (2.2), as will be explained with reference to FIG. 2.
• the signal (r2') which is reduced in the rainfall (4) can be measured so easily and a windshield wiper can be controlled accordingly.
• the CCD or CMOS image chips (5) used have a high sensitivity.
• the CCD or CMOS image chips (5) used have a high sensitivity.
• the section of the picture chip (5) which is hit by the beam pairs (r1, r2 / r2 '), can be provided with a spectral bandpass, which provides a high transmittance for the wavelength of the illumination (3).
• FIG. 3 shows, in the upper part (6) of the image sensor (5), which serves rain detection, seven pairs of illumination reflections (8, 9) which are illuminated by seven LEDs, for example. be generated source (3). These are due to the focus on infinity camera (1) not sharply displayed but perceptible. In particular, the light intensity or quantity can be measured.
• the upper illuminating reflections ⁇ 8 ⁇ are generated by rays (rl) reflected on the inside (2.1) of the windshield (2), which generates lower (9) of rays (r2, r2 ') reflected on the outside of the windshield.
• the light bundle pairs (8, 9) must not disturb the driver assistance image (7).
• a region (6) is selected in Fig. 3, which lies outside the driver assistance image (7) on the image chip (5).
• FIG. 3 thus shows an exemplary division of the driver assistance area (7) and the rain sensor area (6) on the image chip (5).
• the illumination reflections from the outer windshield (9) over which a raindrop (4) lies are attenuated in intensity.
• These illuminating reflections (9) originate from rays (r2 ') reflected on the outside (2.2) of the windshield (2) and are of reduced intensity because a large part of the beam (t1) transmitted into the windshield (2) is separated by raindrops (4). decoupled from the windshield (t2 ') and thus not reflected back to the camera (1) (r2') is.
• These illuminating reflections (9) thus bear the information as to whether rain (4) is present on the outside (2.2) of the pane (2), and their amount of light could be used as measuring signal alone.
• the evaluation can eg by comparison with a threshold value, by comparing the amounts of light of a plurality of these illumination reflections (9) with one another and / or by analyzing the temporal changes of the amount of light of at least one of these illumination reflexes (9).
• an infrared blocking filter can additionally be vapor-deposited on a cover glass of the image chip (5) up to the upper edge of the driver assistance area (7).
• a bandpass filter for the wavelength of the illumination (3) can be deposited over the rain sensor detection area (6).
• the filters could also be applied directly to the pixels of the image sensor (5). This would have the advantage that a parallax offset, which is generated by the edge of the different filters for the rain sensor area (6) and driver assistance area (7) on the cover glass, is avoided.
• An advantage here would be a process that corresponds to the current application of the pixel color filter.
• the two areas (6, 7) can be separated with pixel precision, thus avoiding additional mechanical tolerance reserves resulting from the production process.
• 4 shows a partial illustration of the illumination spots or reflections (8) on the image chip (5).
• the upper area for the rain sensor (6) need not necessarily contain the reflections (8) from the inner surface of the windshield (2.1), since the change of light by rain (4) on the lower light spots (9) is visible , These alone can therefore suffice as a measuring signal and e.g. be compared with a Lichtmen- genschwellwert. If the measurement signal is greater than or equal to the threshold value, it is detected that the disc is dry. On the other hand, if the measurement signal lies below the threshold value, rain (4) is detected on the outside (2.2) of the disk (2). The more the measuring signal falls below the threshold, the more rain is present on the disc (2). This embodiment variant offers the possibility that the area for the rain sensor (6) can be greatly reduced.
• the upper rain sensor region (6) can preferably only be reduced to the extent that the upper light spots (8) are still partially visible. This is shown in Fig. 4.
• FIG. 5 shows a spatial overlap of the driver assistance area (7) or of the far-range imaging with the rain sensor area (6) or the blurred image of the illumination reflexes (8, 9). If the image chip (5) or the structural integration of the lighting is not sufficient Allow size for the spatially separated image of the light spots (8, 9) and the driver assistance area (7), as could be recorded alternately with the driver assistance image an extra image of the rain sensor light spots. For this purpose, the lighting (3) is turned off during the recording of the driver assistance image and turned on again for recording the rain sensor image.
• this offers the advantage for rain sensing that a differential image can be formed with the preceding driver assistance image, whereby the background signal is greatly reduced and ideally only the rain sensor image of the light spots (8, 9) remains.
• driver assistance cameras (1) have an infrared cut filter to reduce the spectral requirements on the optics and / or to enable better color recognition.
• the color filters (R, G, B) on the individual pixels of the image chips (5) used today frequently have a high transmission in the infrared spectral range and thus impair the color selectivity.
• either no infrared blocking filter can be used, or the wavelength of the illumination (3) should be pushed into the visible area.
• Fig. 6a shows the very common Bayer Pattern R-G-G-B, red-green-green-blue.
• Fig. 6b shows an example of a modified pattern R-N-G-B in which the neutral pixel (N) has no color filter at all and thus is transparent to the visible and infrared light. Only these "white" pixels (N) are used for rain sensing, and they could also be used for the driver assistance functions, with the temporal separation of the two shots, to increase the dynamics of the image chip (5) and the sensitivity in dark situations. 1 and 2, an illumination (3) with a beam path is shown which is close to the angle of total reflection in the disc 2. In the arrangement shown there, the signal change when raindrops (4) appear on the disc (FIG. 2) particularly pronounced.
• Figures 7 and 8 show an alternative arrangement which offers the advantage that the illumination source (3) can be integrated into the camera (1), more precisely into the camera body.
• the illumination source (3) also within the camera (1) are placed on a board (12) of the camera body. This results in a significant integration advantage.
• the relative effect between the beam (r2) reflected on the outside (2.2) and the beam (rl) of the secondary beam (n) of the illumination source (3) reflected on the inside proves to be readily measurable and sufficient to allow raindrops (4 ) on the disc (2) reliably detect.
• the viewing aperture (11) must be at least in the area through which the light ray (s) from the illumination source
• Fig. 8 shows the change in the presence of raindrops
• Raindrops (4) also cause a stronger coupling (t2 ') of light from the disk into the area in front of the disk.
• the camera (1) measures a reduced intensity of the partial beam ⁇ r2 ') which has been reflected on the outside (2.2) of the pane (2).
• a secondary beam (s) the reflections on the disc (2) than at least two spatially separated partial beams (r1; r2; r2 ') strike the camera (1).
• the beam paths and components are comparable to those shown in FIGS. 1 and 2, the reference numerals are used identically.
• the detection method illustrated in FIGS. 1 and 2 and FIGS. 7 and 8 is based on detecting a reduction in light, comparable to the classical optical rain sensor, when the outside (2.2) of the pane (2) is wet.
• the light (rh) of the main beam (h) reflected by the raindrop (4) can also be used to detect rain. This is shown in FIGS. 9 and 10.
• FIG. 9 shows the situation with a dry disk (2): while, as in FIG. 7, the secondary beam (n) of the portion (rnl) reflected on the inside (2.1) of the disk (2) causes a reference intensity on the image sensor (5) , the main beam (h) is not displayed on the image sensor. As long as only illumination reflections of the reference beam (rnl) are detected, it can therefore be recognized that there is no rain (4) on the disc (2). As shown in FIG. 10, raindrops (4) on the outside (2.2) of the windshield (2) cause a small portion (rh) of the main jet in the raindrop (4) to be reflected so as to reach the camera (1). meets. In this case, the occurrence of one or more illumination reflexes in addition to illumination reflexes of the Reference jet (rnl) on the presence of rain (4) are closed.
• FIG. 11 shows a further embodiment in which the arrangement comprises a light guide (13).
• the arrangement comprises a light guide (13).
• an optical waveguide (13) is used here.
• the principle of rain detection is the same as explained in FIGS. 7 and 8, but instead of the secondary beam (n in FIGS. 7 and 8) of the illumination (3), the main beam (h) is guided accordingly by means of the light guide (13).
• r2 ' corresponds to r2 in the rain on the outside of the window t2' corresponds to t2 in rain on the outside of the window th1 proportion of the main beam transmitted to the inside of the disk
• th.2 equals th.2 in case of rain on the outside of the disk rh Share of th2' reflecting itn raindrops to the camera
• R Filter element that transmits light in the red wavelength range
• G Filter element that transmits light in the green wavelength range
• N Filter element that lets light through in the visible and / or infrared wavelengths

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• 2011
  • 2011-09-20 JP JP2013542369A patent/JP5944405B2/ja not_active Expired - Fee Related
  • 2011-09-20 WO PCT/DE2011/001749 patent/WO2012092911A1/de active Application Filing
  • 2011-09-20 EP EP11815609.0A patent/EP2646802A1/de not_active Withdrawn
  • 2011-09-20 CN CN201180056008.4A patent/CN103221805B/zh active Active
  • 2011-09-20 DE DE112011102968T patent/DE112011102968A5/de active Pending
  • 2011-09-20 KR KR1020137016837A patent/KR101903981B1/ko active IP Right Grant
  • 2011-09-20 US US13/885,552 patent/US9335264B2/en active Active

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