Camera system for a motor vehicle

Abstract

A camera system (3) for being mounted on a windshield (2) of a motor vehicle (1) is presented, wherein the camera system (3) comprises a lens unit (14). The camera system (3) comprises a liquid crystal unit (11), which is arranged in the field of view (16) of the lens unit (14), wherein an optical axis (15) of the lens unit (14) passes through the liquid crystal unit (11). The liquid crystal unit (11) is configured to adapt a field of view (16) of the lens unit (14).

Description

[0001] Camera system for a motor vehicle

[0002] The present invention is directed at a camera system for being mounted on a windshield of a motor vehicle, wherein the camera system comprises a lens unit. The invention is further directed at a camera arrangement comprising such a camera system and a windshield for a motor vehicle and at a motor vehicle comprising such a camera arrangement.

[0003] Cameras depicting an outer environment of a motor vehicle are employed for various driver assistance functions or other functions for driving a motor vehicle at least in part or completely automatically. A common position for mounting a camera for the monitoring of the front environment of the motor vehicle is the inner surface of the windshield of the motor vehicle.

[0004] Generally, and in particular when the optical axis of the camera is approximately in parallel to the road surface, the windshield is inclined with regard to the road surface and with regard to the optical axis. Since motor vehicle cameras have a relatively large field of view, in particular also a particularly large vertical field of view, this means that light may be reflected for example from the dashboard and / or from the windshield before thoentering the camera, which may lead to a degraded image quality. To avoid such reflections, a mechanical component, also referred to as shutter or bracket, is employed, which covers part of the windshield and therefore blocks such reflections.

[0005] Since the shutter consists of an optically opaque material, for example a grey or black plastic material, the shutter leads to a blind spot in the field of view of the driver. This may be a disadvantage in terms of aesthetics, but also in terms of safety since it impairs the free view of the driver. In particular, the size of the shutter also increases with increasing fields of view of modern motor vehicle cameras, which even intensifies the problem.

[0006] Due to the inclination of the optical axis of the camera with regard to the windshield, a camera housing or a lens housing at a bottom end may be distant from the windshield, but at a top end already may be located very close to the windshield. Therefore the problem cannot be overcome by shifting the camera closer to the windshield.

[0007] From document DE 10 2021 127 662 A1 a camera system for being mounted on a windshield of a motor vehicle is known. The mounted camera system comprises a camera with a lens unit and an optical element, which comprises a structure forming a plurality of prisms on a first side of the optical element. The optical element is arranged in a field of view of the camera and an optical axis of the lens unit passes through the optical element.

[0008] Such arrangement due to the physical properties of the plurality of prisms may involve a reduction of the image quality through edge effects due to scattering of light. In certain light conditions this effect may be differently pronounced and thus entail a source of error for downstream evaluations.

[0009] A further difficulty for a camera for being mounted in a motor vehicle may derive if the camera is mounted in a very high position in comparison with the road surface, as this may for example be the case with a truck. In such a mounting situation it may happen that the field of view of the camera does not cover a portion immediately in front of the motor vehicle. An adaptation of the field of view downwards, that is in a direction along a vertical axis in parallel to the direction of gravitation, may for example at least in certain driving situations help to render at least a part of this portion visible for the camera. Such driving situations may for example be driving at low speed. In other driving situations, which for example may be weather-dependent, an adaptation of the field of view may be equally advantageous, for example to reduce an overexposure by raised sun exposure.

[0010] It is an objective of the present invention to adapt the field of view of a lens unit of a camera for being mounted on a windshield of a motor vehicle in such a way that interfering reflections are avoided and / or that portions outside the field of view by the adaptation of the field of view move into the field of view, wherein the scattering of light is reduced by the measure for adapting the field of view.

[0011] This objective is achieved by the subject matter of the independent claim. Further implementations and preferred embodiments are a subject matter of the dependent claims.

[0012] The invention is based on the idea to provide a liquid crystal unit in the field of view of the lens unit. In this way, the beam path of light beams, which enter the lens unit, may be effectively convoluted, without having to take on board strong edge effects.

[0013] According to an aspect of the invention, a camera system for being mounted on a windshield of a motor vehicle is presented. The camera system comprises a lens unit. The camera system comprises a liquid crystal unit, which is arranged in the field of view of the lens unit, wherein an optical axis of the lens unit passes through the liquid crystal unit. The liquid crystal unit is configured to adapt the field of view of the lens unit.

[0014] In particular the camera system is suited to be mounted on the windshield such that it can take images which represent an outer environment of the motor vehicle through the windshield.

[0015] The lens unit, which may also be referred to as objective lens or lens of the camera system comprises one or several lenses having a common optical axis, which corresponds to the optical axis of the lens unit or the camera system, respectively.

[0016] The liquid crystal unit may for example contain one or more liquid crystals. Liquid crystal refers to a substance, which may both have physical properties of a liquid as well as physical properties of a crystal. By an electric field the properties of the liquid crystal, in particular its index of refraction, may be changed in a targeted way.

[0017] In particular, the camera system may contain a control unit, which is configured to control the liquid crystal unit by changing the electric field in the one or the several liquid crystals, and thus adapt the field of view by changing the index of refraction of the one or the several liquid crystals.

[0018] Due to the manifold ways of controlling and the resulting refractive and diffractive properties of the one or the several liquid crystals it is possible to affect light that is passed through the one or the several liquid crystals in different ways. Such an influence may for example be a refraction and / or a diffraction of the light, in particular a wavelengthdependent refraction or diffraction of the light. Equally, a transmission of the incident light by one or several liquid crystals may for example be polarization-dependent. In other words, a first portion of light with a certain polarization may undergo a first refractive and / or diffractive behavior and a corresponding first transmission by the one or the several liquid crystals and a second portion of light with a deviating polarization may be a deviating refractive and / or diffractive behavior and a corresponding second transmission.

[0019] This also allows for the effect of the liquid crystal unit adapting the field of view of the lens unit to occur only for a certain portion of light, for example a portion of light with a certain polarization, of the incident light or to occur to a larger degree for such a portion of light. Since the field of view, however, is adapted at least for this portion of light, the initially named disadvantages are reduced at least for this portion of light.

[0020] In particular, a liquid crystal unit may be operated as variable in terms of its optical properties. This means it may be possible to configure a first spatial portion of the liquid crystal unit at a first point in time in such a way that a first optical property is predominant and in a second spatial portion at a first point in time a second optical property is predominant. Equally, for example in the first spatial portion the liquid crystal unit at a second point in time a third optical property may be predominant. The same may apply to the second spatial portion.

[0021] In this connection, the optical properties may for example be influenced by applying the electric field. In particular, liquid crystals may have different properties, when they are exposed to a different electric field strength.

[0022] The field of view of the lens unit may be considered as a solid angle range or as a combination of an angular range, which defines a vertical field of view, and an angular range, which defines a horizontal field of view. The adaptation of the field of view of the lens unit by the liquid crystal unit may for example be effected by a refraction and / or diffraction of the incident light of the lens unit. The adaptation by the liquid crystal unit in this connection may be differentiated into an adaptation of the vertical field of view and a deviating adaptation of the horizontal field of view. In particular, the liquid crystal unit may be configured to cause an adaptation of the vertical field of view in the downward direction, that is an extension of the vertical field of view downwards. It is also possible that only the vertical field of view is adapted.

[0023] The adaptation of the field of view may in particular be wavelength-dependent and / or polarization-dependent. In other words, the liquid crystal unit may be configured to refract or diffract light with different wavelengths in different ways. The same may apply to light with different polarization, meaning that for example in a first direction linearly polarized light undergoes an adaptation, that is refraction or diffraction, and in a second direction, in particular a second direction that is perpendicular to the first direction, linearly polarized light undergoes no refraction or diffraction. This may apply in analogy to circular polarizations. Due to the arrangement of the liquid crystal unit in the field of view of the lens unit a resulting field of view of the camera system may be generated, which deviates from the field of view of the lens unit without the liquid crystal unit. In particular, the adaptation of the field of view of the lens unit may be understood as the resulting field of view of the camera system.

[0024] The field of view of the lens unit, which in the case of use according to the intended purpose is vertical, that is without the liquid crystal unit, may for example correspond to a vertical angle range of up to 100° or up to 120° and may in particular be arranged symmetrically around the optical axis of the lens unit. In other words, the field of view of the lens unit may amount both towards the top as well as towards the bottom for example 50° or up to 60° in the direction away from the optical axis. An adaptation of the field of view of the lens unit by the liquid crystal unit may in particular lead to the resulting field of view of the camera system not being adapted in symmetrical way around the optical axis of the lens unit, but rather being extended at least in one direction. For example, the resulting field of view of the camera system downwards may amount to 60° or up to 80° in the direction away from the optical axis. “Down" in this connection in the case of installation into the camera system on the motor vehicle according to the intended purpose may refer to a height axis of the motor vehicle.

[0025] In particular, the liquid crystal unit is substantially flat. This means that the width and the length of the liquid crystal unit, which are defined according to the main plane of the liquid crystal unit, are significantly larger than the thickness of the liquid crystal unit, which is defined in a direction perpendicular to the main plane. In this connection, significantly larger may be understood to the effect that the length and the width both are at least ten times the thickness, in particular at least one hundred times the thickness.

[0026] In particular, the liquid crystal unit comprises an outer face, which may be perpendicular to the optical axis of the lens unit.

[0027] An advantage of the camera system according to the invention is the flexible and uniform adaptation of the field of view of the lens unit by the liquid crystal unit, which may lead to the camera system being capable of being mounted closer to the windshield or at a different angle to the windshield without thereby generating edge effects due to scattering of light. In particular, thereby the size of a shutter, which is intended to lead to the reduction of reflections on the windshield, may turn out smaller than in the case of a camera system that does not comprise such arrangement. Moreover, by the flexible adaptation of the field of view of the lens unit portions that were previously invisible for the camera system, that is portions lying outside the field of view of the lens unit, may lie in the resulting field of view of the camera system, may be captured.

[0028] According to at least one further embodiment, the liquid crystal unit comprises a liquid crystal layer, which in particular contains the liquid crystal or the liquid crystals, and at least one electrode layer, which is configured to generate a spatially modulated electric field in the liquid crystal layer.

[0029] In other words, the liquid crystal unit is set up in the form of layers and may be constructed by several layers with different properties. In particular, liquid crystals in the liquid crystal layer may change their optical properties, in particular the index of refraction, in locally different ways, if they are exposed to the spatially modulated electric field so that the field of view is adapted as described.

[0030] The at least one electrode layer may contain a plurality of electrode structures, which are designed in such a way that they may generate the spatially modulated electric field, which may affect the liquid crystal layer. Electrode structure here refers to a surface on the at least one electrode layer, which contains a conductive material and to which thus an electrical voltage may be applied. Such a surface may also be referred to as active surface. Equally, the at least one electrode layer may contain other surfaces which consist of non-conductive material and which are located in particular between the electrode structures. The geometrical shape of the plurality of electrode structures may affect the characteristic of the spatially modulated electric field and thus the optical properties of the liquid crystal layer. A spatial modulation of the electric field may be caused by the geometrical layout of the plurality of electrode structures or at least be influenced thereby. Equally, the controlling of the at least one electrode layer with a voltage may influence the spatial modulation. In particular, also different electric potentials may be provided at different electrode structures to influence the spatial modulation in a targeted way.

[0031] For example, by a layout of the electrode structures the spatially modulated electric field may be generated in such a way that the liquid crystal layer is influenced in such a way that it leads to the adaptation of the field of view of the lens unit. In particular, this may be effected by refraction and / or diffraction of light such that the field of view of the lens unit is enlarged in a certain spatial direction, for example vertically downwards.

[0032] In some embodiments the at least one electrode layer may contain exactly one or two electrode layers.

[0033] An advantage of this embodiment is the flexible and variable setup of the liquid crystal unit. The individual layers may be arranged differently, depending on which optical property is required. The layout of the plurality of electrode structures may be adapted to the requirements and in particular the sought adaptation of the field of view.

[0034] According to at least one further embodiment, the liquid crystal unit on an outer face of the liquid crystal unit, which is arranged in parallel to the at least one electrode layer, comprises a transparent protection layer.

[0035] In other words, parts of the liquid crystal unit at least on one of their outer faces of the transparent protection layer may be protected against influences from outside the liquid crystal unit. These parts may in particular be the at least one electrode layer or the liquid crystal layer.

[0036] Equally, the liquid crystal unit may comprise a further protection layer on a further outer face of the liquid crystal unit opposite the outer face of the liquid crystal unit. This further protection layer may achieve the same effect for the further outer face as does the protection layer for the outer face.

[0037] The protection layer may contain a glass or a glass composite material. Equally, the protection layer may contain a plastic material. In any case, the contained material has transparent properties, meaning it is permeable to visible light.

[0038] An advantage of this embodiment is that the liquid crystal unit provides a protection against influences from outside the liquid crystal unit. In particular in the case of being mounted within a motor vehicle, such protection may be beneficial to the long service life of the camera system. According to at least one further embodiment, the outer face of the liquid crystal unit is perpendicular to the optical axis of the lens unit.

[0039] In particular, the liquid crystal layer thus may be arranged in parallel to the one or the several lenses of the lens unit or their main planes, respectively.

[0040] An advantage of these embodiments is a particularly compact setup of the camera system.

[0041] According to at least one further embodiment the at least one electrode layer comprises a plurality of strip-shaped electrode structures.

[0042] In other words, a subset of the at least one electrode layer, in particular exactly one electrode layer, may comprise a plurality of strip-shaped electrode structures. This plurality may in some embodiments be at least two, for example at least five, in particular at least ten. The plurality may in some embodiments be understood as a maximum of 1000, for example a maximum of 100, in particular a maximum of 20. Strip-shaped in this connection may be understood as rectangular or substantially rectangular, wherein the length is a multiple of, for example at least twice, the width.

[0043] In particular, the electrode structures may be arranged in parallel to one another and / or have equal distances to one another. Equally, an arrangement is conceivable, in which the electrode structures have an angle deviating from 0° from one another.

[0044] Alternatively, the at least one electrode layer in a further embodiment may also comprise one or several electrode structures arranged in a spiral shape.

[0045] An advantage of this embodiment is the improved possibility for spatial modulation of the electric field and thus the optical properties of the liquid crystal layer.

[0046] According to at least one further embodiment, the at least one electrode layer is designed to be transparent.

[0047] This means that the at least one electrode layer is in particular permeable to visible light. It is advantageous, if in this embodiment the field of vision of the lens unit remains largely unaffected by the at least one electrode layer. This may in particular have positive effects upon an image quality of received images of the camera system.

[0048] According to at least one further embodiment, the camera system contains a control unit, which is configured to control the at least one electrode layer in such a way that the liquid crystal layer due to the spatially modulated electric field emulates a periodic array of prisms.

[0049] In other words, by adapting the field of view of the lens unit a reference adaptation of the field of view of the lens unit, as it would be generated by a periodic array of prisms, is emulated.

[0050] The reference adaptation of the field of view of the lens unit by a periodic array of prisms may in particular result from the refraction and / or diffraction of the incident light. Since a material of the periodic array of prisms has a higher index of refraction than air, a beam path through the periodic array of prisms may be effectively convoluted. Such influence upon the incident light of the camera system may be emulated by the liquid crystal unit.

[0051] The control unit in this connection may for example control the voltage at the at least one electrode layer, but also other parameters of the liquid crystal unit, such as the temperature.

[0052] An advantage of this embodiment is that the reference adaptation offers an orientation for the optical properties of the camera system. Added to this are the advantages of the liquid crystal unit, which does not have any edge effects due to scattering of light.

[0053] According to at least one further embodiment, the liquid crystal unit is configured to adapt the field of view of the lens unit in a direction-dependent way.

[0054] Direction-dependent in this connection may be understood in particular in such a way that the field of view is adapted only in certain directions or is adapted in certain directions more strongly and / or differently than in others. It may also comprise that the field of view is enlarged in some directions, for example in the downward direction, and is reduced in size in other directions, for example in the upward direction. For example, the liquid crystal unit is configured to adapt the field of view of the lens unit in the vertical direction differently than in the horizontal direction and / or in the upward vertical direction differently than in the downward vertical direction. In the installation according to the intended use it may be desirable that the camera system in the horizontal direction has an as large as possible field of view. This field of view may for example amount to 100° or up to 120°. On the other hand, by the described reflection effects for example from the dashboard it may be desirable to restrict the field of view of the lens unit in the vertical direction, in particular downwards, that is for example to a value smaller than 100°.

[0055] Equally, other direction-dependent adaptations are possible, such as for example the adaptation of the field of view of the lens unit in the vertical direction, in particular the expansion of the field of view in the downward direction.

[0056] An advantage of this embodiment is that certain portions of the field of view of the lens unit can be hidden or shown in a direction-dependent manner, that is may be made either visible or invisible for the camera system.

[0057] According to at least one further embodiment, the liquid crystal unit is configured to expand the field of view of the lens unit at a bottom boundary of the field of view of the lens unit in a direction away from the optical axis.

[0058] The bottom boundary of the field of view in this connection may be understood in the case of the installation according to the intended purpose as the bottom boundary of the field of view extending perpendicular to a vertical axis in parallel to the height axis of the motor vehicle.

[0059] In other words, the expansion in the direction away from the optical axis describes an increase of the angle between the optical axis and the bottom boundary of the field of view of the lens unit.

[0060] An expansion of the field of view of the lens unit at the bottom boundary may for example also be desired if the optical axis of the camera system does not extend horizontally, that is perpendicular to the height axis of the motor vehicle, and the resulting field of view of the camera system without this expansion could not capture relevant parts of the outer environment of the motor vehicle.

[0061] An advantage of this embodiment is that the camera system may be mounted to the windshield at an angle of the optical axis deviating from the horizontal direction and nevertheless the relevant parts of the outer environment of the motor vehicle can be captured by the camera system.

[0062] According to at least one further embodiment, the camera system comprises a polarization filter, which is arranged in the field of view of the lens unit, wherein the optical axis of the lens unit passes through the polarization filter. The polarization filter is configured to transmit a portion of light. The liquid crystal unit is configured to adapt the field of view of the lens unit with regard to the portion of light, in particular only with regard to the portion of light.

[0063] Generally, the light incident upon the lens unit may be assumed as waves with different polarizations. The incident light may consist of different portions of light, which have a different polarization. It may for example be differentiated between a linear, a circular, and an elliptic polarization. In the case of a linear polarization the direction of the oscillation is constant and forms an angle with a determined reference direction. Thus, for example a linear polarization with an angle of 0° may be defined as vertical polarization and a linear polarization with an angle of 90° as horizontal polarization.

[0064] The polarization filter may be configured to transmit the portion of light hitting the polarization filter and having for example a defined polarization, in other words to hand it over unhindered from a first side of the polarization filter to a second side of the polarization filter. In particular, this defined polarization may be a linear polarization or for example a horizontal polarization. Equally it is possible that the polarization filter absorbs a further portion of light, which hits the polarization filter and for example has a further polarization that deviates from the defined polarization. Alternatively the further portion of light may be reflected by the first side of the polarization filter. The further polarization may for example be a vertical polarization. In the case of a circular or elliptic polarization the polarization filter may partially transmit the further portion of light.

[0065] The liquid crystal unit may in particular have deviating properties with regard to the portion of light and the further portion of light. In particular, the liquid crystal unit may adapt for example the field of view of the lens unit for the portion of light. Moreover, in several embodiments the lens unit may adapt the field of view of the lens unit only for the portion of light and not adapt the field of view of the lens unit for the further portion of light. The portion of light may be transmitted for example by the polarization filter.

[0066] An arrangement of the polarization filter with regard to the liquid crystal unit may be designed in such a way that incident light, to start with, hits the polarization filter and subsequently the liquid crystal unit. Equally, the inverse case is possible so that the incident light, to start with, hits the liquid crystal unit and subsequently the polarization filter.

[0067] An advantage of this embodiment is an improved image quality since an image of the camera system does not contain interfering portions of light since these were absorbed or reflected by the polarization filter.

[0068] According to at least one further embodiment, the camera system comprises a lens housing which encloses the lens unit. The liquid crystal unit is arranged outside the lens housing.

[0069] The lens housing may for example comprise a hollow shaft or a tube, which comprises an essentially cylindrical inner surface. The lens unit, in particular the one or the several lenses of the lens unit, may be arranged within the tube or shaft.

[0070] An advantage of the arrangement of the liquid crystal unit outside the lens housing is the raised flexibility of the choice of a special design for the camera system, on the one hand, and the liquid crystal unit, on the other hand.

[0071] The liquid crystal unit may for example be fastened to the windshield, in particular to the inner surface of the windshield, or may be arranged between the windshield and the lens housing and the lens unit accordingly.

[0072] According to other embodiments, the lens housing also encloses the liquid crystal unit, in particular circumferentially. In particular, the liquid crystal unit may be arranged within the tube or the shaft or within a further concentric tube or shaft of the lens housing. In this way, a particularly compact design of the camera system may be achieved.

[0073] In particular, the liquid crystal unit with regard to the field of view of the lens unit is arranged in such a way that all light entering the lens unit by necessity has previously passed through the liquid crystal unit. This may be the case for camera systems, in which the liquid crystal unit is arranged outside the lens housing, or for camera systems, in which the liquid crystal unit is arranged within the lens housing.

[0074] According to a further aspect of the invention, a camera arrangement for a motor vehicle is provided. The camera arrangement comprises a camera system according to the invention and a windshield for the motor vehicle. The camera system is mounted on the windshield, in particular on the inner surface of the windshield.

[0075] According to several implementations of the camera arrangement, the optical axis of the lens unit is perpendicular to the windshield.

[0076] In this way, the size of a shutter for blocking unwanted reflections prior to entering the lens unit by minimizing the distance between the lens unit and the windshield may be minimized.

[0077] In some implementations, the optical axis forms an angle with the windshield, in particular with the inner surface of the windshield, which lies within the interval [80°, 100°] or within the interval [88°, 102°] or is equal to 90°.

[0078] In other words, the normal direction or the local normal direction relative to the inner surface of the windshield in the position, in which the optical axis passes through the windshield, forms an angle with the optical axis in the interval [-10°, 10°] or within the interval [-2°, 2°] or an angle of 0°, respectively.

[0079] According to several implementations of the camera arrangement, in which the liquid crystal unit is arranged outside the lens housing, the liquid crystal unit is arranged between the inner surface of the windshield and the lens unit.

[0080] In particular, the protection layer of the liquid crystal unit of the inner surface faces the windshield and may be in parallel to the inner surface of the windshield. The liquid crystal unit in some implementations may also be fastened to the windshield.

[0081] According to a further aspect of the invention, a motor vehicle with a camera arrangement according to the invention is provided. Further features of the invention are evident from the claims, the figures, and the description of the figures. The features and feature combinations previously mentioned in the description as well as the features and the feature combinations mentioned in the following in the description of the figures and / or shown in the figures may be contained by the invention not only in the respective indicated combination, but also in other combinations. In particular, embodiments and feature combinations, which do not comprise all features of an originally formulated claim, are also comprised by the invention. Moreover, embodiments and feature combinations, which go beyond the feature combinations set out in the recitations of the claims or deviate from these, are comprised by the invention.

[0082] In the following the invention is explained in detail with regard to special exemplary implementations and respective schematic drawings. In the drawings, identical or functionally identical elements may be equipped with the same reference signs. The description of identical or functionally identical elements is not necessarily repeated with regard to various figures.

[0083] The figures show in

[0084] Fig. 1 schematically a motor vehicle with an exemplary implementation of a camera arrangement according to the invention;

[0085] Fig. 2 a schematic lateral view of a camera arrangement;

[0086] Fig. 3 a schematic top view of the camera arrangement from Fig. 2;

[0087] Fig. 4 schematically a windshield with a shutter;

[0088] Fig. 5 schematically a lateral view of an exemplary implementation of the camera arrangement according to the invention;

[0089] Fig. 6 schematically a lateral view of a further exemplary implementation of a camera system according to the invention;

[0090] Fig. 7 a schematic view of a liquid crystal unit for use in an exemplary implementation of the camera system according to the invention, and Fig. 8 schematically a top view of an electrode layer of the liquid crystal unit for use in an exemplary implementation of the camera system according to the invention.

[0091] Fig. 1 shows schematically a motor vehicle 1 comprising a camera arrangement 5 according to the invention. The camera arrangement 5 comprises a camera system 3 according to the invention, which comprises a liquid crystal unit 11 . The camera arrangement 5 comprises for example a windshield 2 of the motor vehicle 1 and the camera system 3 is mounted on an inner surface of the windshield 2.

[0092] The motor vehicle 1 may also comprise an electronic control unit or domain control device, ECU, 4, which is coupled to the camera system 3 for receiving, processing, and / or forwarding camera images or video streams, which are generated by the camera system 3. The camera system 3 is in particular arranged for capturing an outer environment of the motor vehicle 1 through the windshield 2.

[0093] The camera arrangement 5 and the camera system 3 according to the invention are explained in the following in further detail with reference to Fig. 5 to Fig. 8.

[0094] Fig. 2 and Fig. 3 schematically show a lateral view or a top view of a known camera system 3', which equally may be mounted on an inner surface 6' of a windshield 2 of a motor vehicle.

[0095] The camera system 3' comprises a camera 8' and a camera housing for mounting the camera 8' on an inner surface 6'. As may be seen from Fig. 2, a top section of the camera 8' is located close to the inner surface 6' or even touches the inner surface 6', whereas a bottom section of the camera 8' due to the inclined orientation of the optical axis of the camera 8' with regard to the windshield 2' is distanced from the windshield 2'. In order to avoid reflections from a dashboard and / or internal part of the windshield of the motor vehicle entering the lens unit of the camera 8', therefore a shutter 9' may be provided, which blocks corresponding reflections. The shutter 9' comprises an opening 10', which is directed at the camera 8' and its optical axis, as schematically shown in Fig. 4. As the shutter 9' causes a blind spot in the field of view of the driver of the motor vehicle, it is desired to keep the shutter 9' as small as possible or even to completely omit the shutter 9'.

[0096] In Fig. 5 a schematic lateral view of an exemplary implementation of a camera arrangement 5 according to the invention, as it may be used for example in the motor vehicle 1 of Fig. 1 , is shown.

[0097] The camera system 3 comprises a lens unit 14 with one or several lenses, which has an optical axis 15. The liquid crystal unit 11 is in particular configured to adapt a field of view 16 of the lens unit 14. The liquid crystal unit 11 is arranged in the field of view 16 of the lens unit 14 and the optical axis 15 of the lens unit 14 passes through the liquid crystal unit 11 . Moreover, in Fig. 5 a camera 8 is represented, which is comprised in the camera system 3.

[0098] The optical axis 15 of the lens unit 14 in the shown example of Fig. 5 is not arranged horizontally and also not perpendicular to the surface 6 of the windshield 2. Various arrangements of the optical axis 15 of the lens unit 14 are conceivable and in particular the adaptation of the field of view 16 of the lens unit 14 can expand the technically reasonable arrangements of the optical axis 15 of the lens unit 14. Due to the liquid crystal unit 14 a further angle range of the optical axis 15 may be facilitated. Since an inclination of the windshield 2 may deviate for each motor vehiclel , this expansion is an advantage of the invention, in particular the optical axis 15 of the lens unit 14 may be perpendicular to the surface 6 of the windshield 2.

[0099] Fig. 5 shows an exemplary embodiment of the camera system 3, in which the liquid crystal unit 11 is connected with an inner surface 6 of the windshield 2.

[0100] Another embodiment of the camera system 3 according to the invention is represented in Fig. 6. Therein, the liquid crystal unit 11 is enclosed by a lens housing 13, in particular on the circumference.

[0101] In particular the liquid crystal unit 11 is in the field of view 16 of the lens unit 14 so that it fully covers the respective cross section of the field of view 16. In other words, all light beams entering the lens housing 13 and passing through the lens unit 14 by necessity have previously passed through the liquid crystal unit 11 . In the exemplary embodiment the liquid crystal unit 11 is not arranged perpendicular to the optical axis 15 of the lens unit 14. However, it is equally conceivable that the optical axis 15 of the lens unit 14 is perpendicular to a surface of the liquid crystal unit 11 .

[0102] Both in the view in Fig. 5, which means also in Fig. 6, the camera system 3 may comprise a polarization filter (not shown). The polarization filter may be arranged both between the liquid crystal unit 11 and the windshield 2, as well as between the liquid crystal layer 17 and the lens unit 14.

[0103] In Fig. 7 a schematic setup of a liquid crystal unit 11 according to the invention is represented. The liquid crystal unit 11 comprises a liquid crystal layer 17 and at least one electrode layer 18. In the representation both on an outer face of the liquid crystal unit 11 a protection layer 12 is comprised, as well as on a further outer face a further protection layer 12‘.

[0104] When activating a control unit (not shown), in particular by applying a voltage, through the at least one electrode layer 18 an electric field, in particular a spatially modulated electric field, may be generated and have an effect upon the liquid crystal layer 17. Due to the electric field optical properties, in particular the index of refraction, of the liquid crystal layer 17 and thus the liquid crystal unit 11 may change.

[0105] Fig. 8 exemplarily shows a top view of the electrode layer 18 of the liquid crystal unit 11 . In the shown example a plurality of strip-shaped electrode structures 19 in parallel arrangement are discernable. The purpose of this arrangement is a spatial modulation of the electric field, which may lead to the desired adaptation of the field of view. It is equally conceivable that the plurality of the electrode structures 19 shown in Fig. 8 may be smaller or larger than in the representation. In particular, also the shape of the plurality of the electrode structures 19 may deviate from the representation and may for example be ring- or spiral-shaped. Equally, an embodiment is possible, in which the further electrode layers 18 are connected to one another in a sandwich design and thus may form a resulting electric field, which has an effect upon the liquid crystal layer 17.

Claims

Claims1 . Camera system (3) for being mounted on a windshield (2) of a motor vehicle (1 ), wherein the camera system (3) comprises a lens unit (14), characterized in that the camera system (3) comprises a liquid crystal unit (11), which is arranged in a field of view (16) of the lens unit (14), wherein an optical axis (15) of the lens unit (14) passes through the liquid crystal unit (11); and the liquid crystal unit (11 ) is configured to adapt the field of view (16) of the lens unit (14) and. the liquid crystal unit (11) comprises a liquid crystal layer (17) and at least one electrode layer (18), which is configured to generate a spatially modulated electric field in the liquid crystal layer (17) while the camera system (3) comprises a control unit, which is configured to control the at least one electrode layer (18) such that the liquid crystal layer (17) due to the spatially modulated electric field emulates a periodic array of prisms.

2. Camera system (3) according to claim 1 , characterized in that the liquid crystal unit (11) on an outer face of the liquid crystal unit (11), which is arranged in parallel to the at least one electrode layer (18), comprises a transparent protection layer (12).

3. Camera system (3) according to claim 2, characterized in that the outer face of the liquid crystal unit (11) is perpendicular to the optical axis (15) of the lens unit (14).

4. Camera system (3) according to any one of claims 1 to 3, characterized in thatthe at least one electrode layer (18) comprises a plurality of strip-shaped electrode structures (19).

5. Camera system (3) according to any one of claims 1 to 4, characterized in that the at least one electrode layer (18) is designed to be transparent.

6. Camera system (3) according to any one of the preceding claims, characterized in that the liquid crystal unit (11) is configured to adapt the field of view (16) of the lens unit (14) direction-dependently.

7. Camera system (3) according to the preceding claims, characterized in that the liquid crystal unit (11) is configured to extend the field of view (16) of the lens unit (14) at a bottom boundary of the field of view (16) of the lens unit (14) in the direction away from the optical axis (15).

8. Camera system (3) according to any one of the preceding claims, characterized in that the camera system (3) comprises a polarization filter, which is arranged in the field of view (16) of the lens unit (14), wherein the optical axis (15) of the lens unit (14) passes through the polarization filter; and the polarization filter is configured to transmit a portion of the light; and the liquid crystal unit (11 ) is configured to adapt the field of view (16) of the lens unit (14) with regard to the portion of light.

9. Camera system (3) according to any one of the preceding claims, characterized in that the camera system (3) comprises a lens housing (13), which encloses the lens unit (14); and the liquid crystal unit (11) is arranged outside the lens housing (13).

10. Camera system (3) according to any one of claims 1 to 8, characterized in thatthe camera system (3) comprises a lens housing (13), which encloses the lens unit (14); and the lens housing (13) encloses the liquid crystal unit (11 ).11 . Camera arrangement (5) for a motor vehicle (1 ), wherein the camera arrangement (5) comprises a windshield (2) for a motor vehicle (1 ) and a camera system (3), which is mounted to the windshield (2) and is designed according to any one of the preceding claims.

12. Camera arrangement (5) according to claim 1 1 , characterized in that the camera system (3) is designed according to claim 9; and the liquid crystal unit (1 1 ) is arranged between an inner surface of the windshield (2) and the lens unit (14).

13. Camera arrangement (5) according to any one of claims 11 or 12, characterized in that the optical axis (15) of the lens unit (14) includes an angle with the windshield (2), which lies within the interval [80°, 100°] or within the interval [88°, 102°] or is equal to 90°.

14. Motor vehicle (1 ) with a camera arrangement (5) according to any one of claims 1 1

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