Camera in a vehicle

State of the art

The invention relates to a camera in a motor vehicle with at least one image sensor.

Motor vehicle manufacturers are planning to equip vehicles with cameras to give the driver Driver assistance functions such forbearance assistance, lane departure warning and / or To provide traffic sign recognition and / or reversing aid available. These Driver assistance functions are primary functions of the cameras. Cameras for this Features Watch the automotive environment, in particular the motor vehicle ahead, and therefore have a depth of field ranging from about 2 m to infinity. For example proposes a night vision system with a camera in the DE 40 32 927 A1. The Cameras are preferably mounted near the rear-view mirror in such a way that the Section of the camera field of view with the windshield wiper in the field of Wiper is.

It is also known to equip motor vehicles with so-called rain sensors detect existing precipitation on a disk and depending on the Rainfall affect an associated wiper system. The advantage is this is that the driver of the motor vehicle can concentrate on the road, while the setting of the wiper is carried out automatically.

The German patent DE 197 49 331 A1, for example, a method and a camera for detecting on a windshield of a motor vehicle contained objects such as water drops or other pollution objects known. The camera is focused on the outer side of the windshield.

European Patent Application EP 0832798 A2 proposes an image recognition system for Detection of water droplets on a windshield of a motor vehicle in front, which a focusing screen is applied to the windshield, so that objects in greater Removal of the windshield are not sharp.

In the international publication WO 03/002388 A2 it is proposed that the outer Surface of a disk from two different directions to observed, with the cameras are focused onto the windshield.

The German patent DE 197 04 818 A1 is a sensor system with a opto-electric conversion element known to the optical radiation of a first and a second environment of the sensor system detects, with the sensor system is designed such that it is a combination of illumination and a wiper sensor.

ADVANTAGES OF THE INVENTION

The camera described below in a motor vehicle having the features of independent patent claim has the advantage that by the simultaneous detection of first optical radiation of the traffic area of ​​the surroundings of the motor vehicle by the Much of the light-sensitive surface of the image sensor and the second optical radiation only through a small part of the image sensor, the camera at least one primary function, as Tolerance Support (night vision) and / or lane departure warning and / or Traffic sign recognition and / or reversing aid, provides and at the same time Camera function of a rain sensor realized. The part of the image sensor, the second optical radiation detected comprises equal to or less than 10%, preferably equal to or less than 2%, the light-sensitive surface of the image sensor. This has the additional advantage that the competition for the limited installation space on the windshield, For example, near the interior mirror, eliminating that arises because, as rain sensors automatic activation of windscreen wipers similar location as cameras (Video sensors) are placed. Furthermore, the competition for the scarce Wiping room defused. The integrated rain sensor function in the camera to be in Advantageously, the cost of the rain sensor is reduced, since a separate rain sensor can be omitted. This has a favorable effect on the total cost of the camera and rain sensor. Furthermore, this integration has the advantage that the computing power and the interfaces of the Camera for the primary functions as well as for the integrated rain sensor function used will. As computing unit for the rain sensor function is the powerful computers the Camera shareable. Therefore, for the rain sensor function, a separate microcontroller and an interface to the motor vehicle, for example, the CAN bus, saved. This creates Another advantage in terms of cost of the camera compared to an additional Rain sensor. In summary, there are advantages of cost and space reasons. furthermore it is advantageous that the rain information of the primary function is not available, the resulting turn can derive conclusions about the sight or the reliability of their results.

A further advantage is that for the rain sensor function many photosensitive elements (pixels) be used, for example, by the use of 10 lines with 640 pixels compared to few, for example four, photodiodes and / or phototransistors in conventional Rain sensors. This leads to a high redundancy and robustness in the realization of a Rain sensor by a camera according to the features of the independent Claim.

Another advantage of the camera described below is that the camera at least one element of the lens is focused on the distance and thus the camera Primary functions available. The windscreen is not in Depth of field of the camera, so do not focus on the image sensor (imager) ready. An advantage is that the camera is designed such that optical from the first Radiation for the primary function of different, second optical radiation for Rain sensor functionality is only supplied to another part of the image sensor, wherein with a function of the second optical radiation, the humidity or the wetting is water drops an external surface of a windshield of the motor vehicle can be determined.

Particularly advantageous is a first optical element, the second optical radiation limited only to a part of the image sensor supplies. It is advantageous that the first optical element the second optical radiation is collimated, that is in a substantially parallel optical Radiation converts since then focused on the optical radiation on the on the distance Displays Lens Focus on the part of the image sensor. It is also advantageous if the first optical element deflects the second optical radiation, because then second optical Radiation outside the scope defined by the lens and the image sensor of the camera is detected. This is particularly advantageous also in the realization of passive rain sensor function without active illumination by a radiation source, since this a large measuring field for the second optical radiation is present. The realization of a passive Rain sensor function will total the advantage of a simple structure, a simple Adjustment and therefore an inexpensive camera.

A further advantage is a concave mirror, in particular a parabolic mirror, as the first optical Member since concave mirror simultaneously collimate optical radiation as well as redirect. This allows the sharp image of the external surface of a disk of a Motor vehicle on the focused on the distance lens to the image sensor, wherein the external surface preferably outside through the lens and the image sensor formed detection range of the camera befmdet without an active radiation source necessary is.

In order to realize the active rain sensor function, it is advantageous when the first optical Element is a decoupling element which at for example by means of an optically transparent adhesive the inner surface of a windshield of the motor vehicle is secured and the second optical Radiation from the window of the motor vehicle decouples.

Another advantage is the realization of both passive and active Rain sensor function is achieved in that in addition to the first optical element, for example, the decoupling element, at least one further first optical element for deflecting the the second optical radiation is used. This is, for example, at least one optical Mirrors and / or at least one prism and / or at least one optical grating and / or at least one optical waveguide. The same applies alternatively or additionally for the second optical element, the coupling element. Furthermore, it is advantageous if the at least one first optical element, for example, the decoupling element, and the least a second optical element, for example, the injection element, as light conducting a unit form, since this leads to a particularly compact design of the camera.

For providing the second optical radiation in the realization of the active Rain sensor function is in a particularly advantageous manner, at least one radiation source used, wherein the second optical radiation is collimated or is collimated after generation. The collimated radiation causes a sharp image on the distance focused image sensor is achieved even though neither the radiation source nor the Windshield in depth of field of the camera befmden. Advantageously low Beam divergence of the second optical radiation, because in spite of the beam path of some Centimeters then takes only small areas of the image sensor for the rain sensor function are and this leaves a large active image area for the primary function. Further, advantageous that both visible and infrared light as a second optical radiation can be used. When infrared light is advantageous in that the from the camera (video sensor) used windshield area, the heat protector is cut out already when the Camera for night vision function support (night vision), specifically for the function Night-vision in the near infrared spectral range (NIR night vision) is used. A further recess of the heat protector for the rain sensor can be omitted. Of the Use of visible light is useful when there is no recess of the heat protector is provided or the damping of the disc is very high in the infrared, for example, if provided as a primary function of only the Lane Departure Warning (Lane departure warning) is. By collimated radiation low divergence is also advantageously achieved that in the absence of water droplets no light rain sensor function in Pixel regions of the primary function passes. If water is present, the optical Radiation from the radiation source of the rain sensor function by scattering at the raindrops enter the pixel regions of the primary function, but is not ready to sharply since it claimed Scattering the raindrops is not collimated and is therefore unproblematic. At a Primary function only in the visible range, such as the lane departure warning function, only in Infrared, as night vision support function, or in other spectral Subregions of the spectral sensitivity range of the image sensor is working, can the Workspace primary function through the use of optical filters spectrally from the workspace the rain sensor function are separated. This is advantageously characterized performed by the optical filter on the pixels of the image sensor used in each case Primary function are applied. Then falls even in the presence of moisture no second radiation pixel of the primary function. For example, this occurs when using Infrared spectral regions for the primary function characterized by a filter which only infrared-permeable, in the offices of the primary function of the subregion Image sensor is applied and the second radiation outside the infrared Wavelength range, ie for example in the visible spectral range and / or in ultraviolet spectral range. General enters the first optical radiation for Realizing the primary function on the optical filter on the primary function used part of the area of ​​the image sensor, while the second radiation before for is blocked primary function used subregion and only on the part of the image sensor is detected. The primary function is therefore of the rain sensor function and / or of other functions spectrally separated.

Advantageously, a second optical element, the second optical radiation to such a inner surface of a windshield of the motor vehicle, for example the windscreen, couples, that the second optical radiation in front of the exit on the inner surface of the Disk at least once totally reflected at the external surface, when no Moisture and / or wetting with water drops on the external surface of the disc is available. In the absence of moisture on the outer surface formed in the collimated optical radiation no stray light for the primary function. On the other hand, in the moisture level of the optical radiation is varied such that the functional Related to detect the moisture on the outer surface of the disk is usable. It is particularly advantageous when the second optical element is a is coupling element, which, for example, by optically transparent adhesive on the inner Surface is attached to a window of the motor vehicle. Furthermore, the variant is advantageous, when the second optical radiation in front of the exit on the inner surface of the disk more than once, is reflected at the external surface, as then both a greater Measuring surface is covered, as well as a stronger drop in intensity in the presence of Moisture and / or water droplets is registered.

It is advantageous if the at least one radiation source and / or the at least one first optical element and / or the at least one second optical element in a Lens shade the camera and / or a housing in / or other packaging-relevant (Packing relevant) component of the camera are integrated, as this especially at a compact design of the camera with integrated rain sensor function leads and no additional space is needed.

By a diaphragm, wherein the diaphragm is configured such that the first optical radiation from is blocked the part of the image sensor, while the second optical radiation part before the image sensor is captured, is achieved in an advantageous manner that the accuracy of the Rain sensor function and the at least one primary function of the camera is increased. At the same time, the reliability is increased. It is particularly advantageous if these Aperture in a lid (cover), in particular in a Glaslid, the image sensor is accommodated, since the blocking of the first optical radiation in this arrangement, is particularly efficient for small size of the aperture. The aperture is above explained specifically designed and different from the normally used rotationally symmetrical aperture of the camera, which adjust the exposure.

Further, a camera is advantageous to alternatively or additionally at least one optical filter, in particular an optical bandpass filter covers, which located in a beam path of the first and / or the second optical radiation befmdet to increase the immunity. Especially is advantageous if the optical filter directly on a pixel and / or on the first optical element, such as the output coupler, is attached.

Advantageously, a camera which is designed in such a way that at least one exposure parameter the image sensor is adjusted in dependence of the second optical radiation, as this in Advantageously, a high reliability and accuracy of the rain sensor function contributes. Further, the radiation source is advantageous when, additionally or alternatively in such a way is adjustable such that the intensity and / or time course of the second optical radiation is changeable. It is particularly advantageous if the image capturing by the image sensor and the second optical radiation are synchronized, for example by the second optical Radiation is pulsed by the radiation source is synchronized with the image capture of the image sensor is discharged.

A camera having means alternatively or additionally, a determination of the brightness the surroundings of the motor vehicle as a function of a second portion of the image sensor, the of the first part is different, and / or a determination of the humidity and / or the Wetting with water drops an internal surface of the wheel of the motor vehicle allow, has the advantage that in addition to the rain sensor function is also a Light sensor function and / or a condensation sensor function covered by the camera will. This has cost and space reasons advantages, since no separate light rain sensor modules required are.

Further advantages result from the following description of exemplary embodiments with reference to the figures and from the dependent patent claims.

drawing

The invention is described with reference to the embodiments shown in the drawing explained in more detail.

Show it:<ul><li>Figure 1 is a general drawing of a camera of the first embodiment,</li><li>Figure 2 is a detailed view of the general arrangement drawing,</li><li>Figure 3 is a general drawing of the second embodiment,</li><li>Figure 4 is an overview diagram of the third embodiment,</li><li>Figure 5 is a block diagram.</li></ul>

Description of embodiments

Next, a camera is described in a motor vehicle with an image sensor, wherein the camera primary functions, such as night vision assist and / or Lane departure warning and / or traffic sign recognition and / or reversing aid, by Detecting the optical radiation of the traffic space around the motor vehicle and a rain sensor function provides.

The camera described below in a motor vehicle of the first two Embodiments having an image sensor with integrated active rain sensor function uses, a total reflection of light at the disc outer side in the absence of raindrops out. For the realization of active rain sensor function is at least one active used radiation source which operates in the visible and / or near infrared spectral range. The wavelength of the used inter alia on the spectral characteristics of Image sensor (imager) and the transmittance of the windshield for certain Wavelengths determined. As detectors smaller pixel areas come (less than about 10% the image sensor surface) of the image sensor on the edge of the usable pixel matrix used. As Image sensors are CCD image sensors and / or CMOS image sensors used. A large (Preferably greater than about 90% of the image sensor surface) contiguous pixel area of ​​the Image sensor will continue for at least one primary function, such as night vision support and / or lane departure warning and / or traffic sign recognition and / or reversing aid, used. The camera (video sensor) is focused on its lens on the distance. The Sensing the surface of the windshield by means of collimated light. To this end, is the light of a light-emitting diode (LED) and / or a laser, and / or other Ray source collimated with a beam shaping optics, such that all the light rays approximately parallel, ie running with low beam divergence in one direction. This collimated light beam as optical radiation by means of an optical coupling element as in coupled, the disk to be larger at an angle to the critical angle of the Total reflection is incident on the surface of the disk (disk interface-air). Depending on Embodiment, after one or repeated total reflection at the surface of the disk coupled out of the collimated light beam through a decoupling element from the disc and open distribution over the lens supplied to the image sensor. Through the use of a collimated Light beam is a sensing and outside the depth of field of the camera possible since the radiation source will appear due to the collimation lens at infinity. The compared to a conventional camera without rain sensor functionality additional components, as the radiation source with collimator and / or coupling elements are preferably in the Space of the video sensor, for example in the housing and / or the lens hood and / or Covers the camera integrated. Power supply and control of Radiation source via the camera. Communication with the vehicle via the communication interface of the camera, for example, with a Automobilbus how the CAN.

In the third embodiment, a camera, the raindrop is described by purely passive Observation of the outside of the window of a motor vehicle, with a part of a Image sensor detects, thus realizing a passive rain sensor function.

The night vision support function is a driver assistance function in which information from the environment of the motor vehicle, which the driver, for example, due to Darkness or fog can not perceive directly, by imaging and / or warning the Driver via a display unit, such as a display or a head-up display, are displayed. A function for lane departure warning is an optical and / or haptic and / or audible warning if the vehicle leaves its lane. On System for traffic sign recognition assists the driver in detecting Traffic signs. When reversing aid is a driver assistance function, the driver brings the rear passenger space for display.

Figure 1 shows an overview diagram of a camera 8 of the first embodiment to Realization of an active rain sensor function, consisting of a radiation source, a first optical element, a second optical element and an image sensor 24. In the first Embodiment, the radiation source is an LED 16. The light 30 of the LED 16 as a second optical radiation is through a not shown in Figure 1 at the collimator collimated exit surface of the radiation from the LED 16 and a coupling element 18 as coupled into the second optical element disc, said disc in the first is embodiment, the windshield 10 of a motor vehicle. After three Total reflection at the pane surfaces 12, 14 - twice on the outer surface 12 and once on the inner surface 14 - is effected a coupling via a decoupling element 20 the first optical element. The still collimated light 30 (beam) of so integrated rain sensor function is then free through the lens 22 on a pixel of the bottom rows of the image sensor 24 (imager) ready. The lens 22 consists of at least one lens. In the first embodiment, the camera 8 is attached to the Windshield 10 is fixed, and the detection range 32 of the image sensor 24 in Direction of travel of the vehicle aligned. The image sensor 24 detects light Detection area 32 as a first optical radiation. In a variant of the first Embodiment, the camera 8 in a different window of the motor vehicle, For example, on the rear wheel to realize a reversing camera to the receives back space arranged. As the image sensor 24 is the preferred Embodiment, a CMOS image sensor used. Alternatively or additionally, are CCD image sensors and / or other equivalent image sensors used. In the first Embodiment, the LED 16 as a radiation source, the coupling element 18 as second optical element and the decoupling element as the first optical element 20 in the Baffles 34 of the camera 8 is integrated. The lens hood 34 is a part of the housing the camera 8 and serves to incident light (stray light) to shield the environment. Furthermore, the camera 8 includes a special diaphragm 28, as in the Glaslid 26 cover is the image sensor 24 is integrated. The function of the diaphragm 28 is illustrated in FIG. 2 at direct coupling the collimated light 30 towards the lens 22 of the camera 8 without directional deflection Note the mounting position of the camera 8 to the disc: The optical axis 44 of the camera 8 is approximately horizontal in the preferred embodiment installed, while the windshield 10 is an inclination relative to the horizontal of comprises about 25 ° to 32 °. With a refractive index of the disc of about 1:52 and a refractive index of water of about 1:33 found from an angle of 61 ° always total reflection takes so then no distinction is possible if water is present on the disc. Of the So selected coupling angle is between about 41 ° (critical angle of total reflection glass-air) and 61 ° (critical angle of total internal reflection glass of water). Now it should be noted that from the Slice decoupled light 30 has yet to meet an edge pixel of the image sensor 24th at the conditions described are therefore the preferred embodiment of pixels used the middle portion of the lowermost rows of the image sensor 24th

Figure 2 shows a detail of the drawing of the camera of the first Embodiment of Figure 1. On the basis of Figure 2 will be explained below, as stray light hidden from the same direction as the actual useful signal of the rain sensor function becomes. Since parallel beams from a direction focused on a point of the focal plane be, in which the image sensor 24 is approximately, applies in the absence of Aperture 28 on the space reserved for the rain sensor function pixel region 38 not only the the disc emitted light 30 as the second optical radiation of the rain sensor, but also stray light 42 as a first optical radiation from the vehicle ahead, the same direction having. In addition to the space reserved for the rain sensor function pixel area 38 includes the Image sensor 24 a pixel region 36 for realizing at least one primary function. to 42 to prevent superposition of this interference light with the light 30 of the rain sensor function, is the flare in the first embodiment 44 by a mechanical shutter 28 hidden. The direction of the collimated light 30 (beam) of the rain sensor function is chosen such that its angle of incidence just about the maximum opening angle of the camera and corresponds it to the bottom line (the reserved for the rain sensor function Pixel region 38) of the image sensor 24 falls. The Durchtrittsort through the lens 22 is so far voted top as possible but limited by a non-illustrated field limiting Aperture. In parallel to this used as a primary beam of light 30, the rain sensor function from the apron of the vehicle incident stray light 42 by a mechanical shutter 28 immediately before the unused pixels of the offices for the rain sensor function Pixel region 38 is blocked. The selected Durchtrittsort of light 30 at the top of Lens 22 is particularly advantageous, since no additional further diaphragm for shielding Another beam is required above the rain sensor bundle. Furthermore, Figure 2 shows the optical axis 44 of the camera. be For the technical realization of the aperture 28 different variants used. It is well known, image sensors 24 for protection of the bonding wires fitted with a Glaslid 26 as a cover, wherein the Glaslid 26 preferably is adhered directly to the image sensor 24th In a first variant, this Glaslid 26 with an opaque layer on the top and / or bottom, depending on the required position of the diaphragm 28 partially coated. Alternatively or additionally, the Glaslid 26 from two superposed composed part plates, so that the Alternatively or additionally, shutter layer at positions between the top and bottom of the Glaslids 26 can be applied. Alternatively or additionally, the image sensor 24 is a Coating, wherein the coating is, for example, an angle-dependent filter, which configured such that stray light is suppressed 42 (light from the Störrichtung) and light 30 of Useful direction passes. In a variant of the first embodiment flare 42 alternatively or additionally computationally considered. Here are two images are immediately recorded successively, wherein an image with activated radiation source is taken, the other without. The influence of the disturbance light 42 is then calculated separated. The stray light 42 is regarded as a quasi-stationary. This approximation is at the Most natural scenes allowed.

Figure 3 shows an overview drawing as seen from the top of the camera of the second Embodiment, wherein only the opposite to the first modified embodiment we have measures and are described below. Further, for corresponding elements of the second versus the first embodiment, the same Numeral used. In the second embodiment, in addition to the rain sensor function also integrates a light sensor in the camera function. Under a light sensor function in Motor vehicles is hereby wakeup and / or off the Automotive lighting, for example, the low beam and / or the driving beam and / or front fog lamps and / or the rear fog lamp and / or the interior light and / or understood the dashboard lights and / or the like. To determine the brightness of the Environment of the motor vehicle is in addition to the light from the detection area Camera (light from the first direction) light from at least a second direction used. The light from the second direction is preferably derived from a range above the motor vehicle. For this purpose, a means for deflecting light from the at least a second direction on a second portion of the image sensor 24 used. The Means for deflecting light in this second embodiment two mirrors 46th

The light from the second direction by the mirror 46 via the objective 22 on two mapped pixel areas 50 for the light sensor function, while the light for the Rain sensor function by the extraction element 20 through the lens 22 to a Pixel region 48 is ready for the rain sensor function. The pixel areas 48, 50 of Light sensor function and the rain sensor function the same line of the image sensor 24. The unused lines are divided, for example, in 3 pixel regions 48, 50th The middle one Pixel region 48 serves as a rain sensor, the outer two pixel regions 50 as light sensors. Just as in the first embodiment with only the rain sensor function is a provide blocking by a mechanical shutter immediately before the pixels to stray to block from the same direction.

The immunity is in a variant of the embodiments described above performed by tuning the wavelength of the radiation source to the image sensor. The Detectors (pixels of the rain sensor functionality) are optical bandpass filter, For example, interference filters adapted to the wavelength of the radiation source. To this end, is an interference filter layer in a variant directly to at least one pixel of the applied image sensor and / or in a second variant of an other favorable point Beam, attached.

Alternatively or additionally, the immunity is time synchronization between Radiation source and image sensor increases. For the suppression of ambient light influences the radiation source is pulsed in synchronism with the exposure phase of the image sensor. So will achieved a higher signal to noise ratio. In one variant, are alternately switched on and images switched radiation source are taken so that the ambient light component, the is determined when switched radiation source, is taken into account by calculation. In a further variant, alternatively or additionally against a divergent beam path the detection by the image sensor collimated again. This is, for example, through a lens and / or made a concave mirror. In a further variant, light with greater Beam divergence used to cover larger areas of the disc.

In the coupling of the light beam will be available in other versions besides the direct Coupling the collimated beam via the coupling element additional optical elements, as a reflecting mirror, and / or light-guiding elements such as optical fibers, are used. This has made Space reasons advantages since the installation location of the radiation source can be freely selected.

The same applies for the coupling out of the light beam from the disk in the direction of Camera. For this purpose, additional optical elements such as reflecting mirror, and / or light-guiding elements such as optical fibers, used. In a further variant, the decoupled light rain sensor function by bypassing the lens directly to the selected pixels of the image sensor is coupled.

Figure 4 shows an overview diagram of the third embodiment for realizing a passive rain sensor function, consisting of a parabolic mirror 51 as the first optical Element and an image sensor 24, whereby only the opposite of the first two listed embodiments revised measure and is described below. Further, for the corresponding elements of the third compared to the first two Embodiments, the same reference numerals are used. In this third Embodiment, the moisture and / or wetting with raindrops on the Windshield 10 passively detected. The outside of the windshield 10 is with a matrix-type image sensor 24 detected, the camera focuses at infinity; also a driver assistance function as a primary function, such as the Night vision support function and / or lane departure function provides. Of the Focusing conflict is like in the first two embodiments is that the Primary function focusing on infinity required, while for the is rain sensor function to focus on a few cm necessary. In the third Embodiment, a parabolic mirror 51 is used, wherein the, from an object For example, a raindrop, divergent outgoing light 30 by the parabolic mirror 51 so is bundled such that the light 30 then runs parallel and so sharply over the lens 22 a portion of the image sensor 24 of the camera are displayed. The parabolic mirror 51 is such designed and oriented so that its focal plane on the outside of the windshield 10. Furthermore, the parabolic mirror 51 performs a deflection of the same beam path of the Light 30 through. also for the rain sensor function a part of the image sensor 24, preferably an edge area used. In the third embodiment also, the used bottom lines of the image sensor 24 for the rain sensor function. The aperture 28 is mounted directly in front of the image sensor 24, makes a parallel with the useful signal of the Rain sensor incident stray light from 42, the aperture 28 on a 26 Glaslid is attached. The measuring range for the rain sensor function is an approximately rectangular Area on the windshield 10. Furthermore, Figure 4 shows the optical axis 44 of the camera. In a variant of the third embodiment, alternatively or in addition to Redirection and collimation of a concave mirror which deviates from the paraboloid, and / or a combination of at least one plane mirror and at least one lens used.

5 shows a block diagram of the above-described embodiments, consisting of an LED 16 as a radiation source, the image sensor 24 and an evaluation unit 52. The image sensor 24 transmits a signal over line 56 to image signals of the evaluation unit 52. The evaluation unit 52 through the signal line 58 at least one parameter of Image sensor, a 24th Further, the evaluation unit 52 through the signal line 60, the LED 16 on. The evaluation unit 52 evaluates the image signals of the image sensor 24 and is on the Signal line 54 primary functions and / or the rain sensor function and / or the Light sensor function and / or other functions subsequent systems. The Transmission on the signal lines 54, 56, 58, 60 takes place electrically and / or optically and / or via radio, preferably via a Kraftfahrzeugkommunikationsbus, such as the CAN bus. Alternatively or additionally, the transmission takes place on signal lines 54, 56, 58, 60 by means of parallel LVDS lines (Low Voltage Differential Signaling ¯ lines) and / or Firewire and / or USB preferably with bandwidths over 10Mbyte / sec. As FireWire or i.LINK refers to the IEEE 1394 technology. The FireWire interface allows Transmitting digital data at 400 Mbit / s or preferably even higher data rates. Of the Universal Serial Bus (USB) is a fast bus system through which a plurality of terminals on a Terminal can be connected. The evaluation unit 52 is designed such that it the humidity and / or wetting with water drops an external surface determined. to Derivation of wiping strategy are defined different intensity thresholds. The Areas between these threshold values ​​corresponding to the various Wischmodi the windshield wiper as interval normal wiping operation and / or faster wiping operation. The current intensity value is a function of the portion of the image sensor, for example as Mean and / or median determined for all exploited pixels rain sensor functionality. the wiping strategy is then determined by comparison to the fixable threshold. Alternatively or in addition, the histogram is used over all pixels and / or the evaluated histograms certain pixel areas and on the formation of percentiles refined humidity calculation performed. Thus, also from the distribution of the histogram be closed to certain moisture conditions.

Alternatively or additionally, an exposure adjustment of the image sensor is performed. at Cameras that provide primary functions, the exposure setting is such performed so that a high contrast image is present. To ensure the Rain sensor functionality, individually or together, at least one of the following Measures taken. In a first variant, the absolute irradiance by Consideration of the adjusted exposure parameters recalculated. Here, However, the case may occur that the pixels of the rain sensor functionality their active leaving work area and take the minimum or maximum value, so that no recalculation is possible. This is known as clipping. For this purpose, in another Variants least carried out one of the following solutions.<ul><li>Readjustment of the radiation source of the rain sensor, so that again the active region is reached, and / or</li><li>Use of a high dynamic range image sensor, so that the active region will never leave, and or</li><li>Use separately exposed images, for example, every 10th image, for Rain sensor functionality. For these images, the exposure setting is only on the Pixel rain sensor functionality applied, while all other images of based Pixels of the primary function are exposed. The separately-exposed images can vary depending Execution of the image sensor in the pixels of the rain sensor functionality or be limited primary function by selecting a selection area (Windows-of-interest). In a further variant selected, specific pixel areas of subjected to the image sensor of a local exposure settings (exposure control), so that simultaneously the pixels of the primary function and / or the rain sensor function and / or the Light sensor function are exposed contrasty.</li></ul>

The pixels of the rain sensor function in a first variant directly evaluated and / or are formed in a second variant histograms certain pixel areas. In addition, the evaluation strategy will be dependent on others in a further variant, Information, such as navigation signals and / or weather data, adjusted.

In another variant, a condensation sensor in the camera is integrated, of the fitting the inside of the windshield detected. Here also are subregions of The image sensor is used to provide a primary function utilized. Starting from Figure 3 is on one of the two pixel regions, which are designated in figure 3 with reference numeral 50, a polarizing filter applied. This pixel area is used as a condensation sensor, obtained during the second pixel region as a rain sensor remains. In the geometric Interpretation of the condensation sensor is considered that the beam passing through the Reflection at the disk inner side facing the rain sensor changes. little one Fog particles act as opposed to the larger raindrops polarizing, so that after reflecting linearly polarized light is produced at a fogged surface. Light, which overcomes the polarization filter, therefore predominantly based on reflection on the fitting of the disc inside. Along with the different reflection site (Disk inside instead of outside pane) are two mechanisms for distinguishing between rain and fog. The evaluation of the pixel regions of the condensation sensor is analogous to the analysis described above, when rain sensor.

Alternatively or additionally, the rain sensor functionality described above is to Control the rear wiper are used. Preferably, the integrated rain sensor functionality in the rear-view camera or the front camera. alternative or in addition, a light sensor functionality and / or functionality in a sensor fitting integrated reversing camera.

In a further variant of the embodiments described, the camera comprising at least two or more than two image sensors, wherein in two image sensors in the camera is carried out a further variant as a stereo camera.