Camera-based control of the light emission angle of a vehicle's headlight

Abstract

A method for controlling the light emission angle (4) of a headlight (2) of a vehicle (1) is described, comprising a front camera (6) and a device for adjusting the light emission angle of the headlight (2). The method comprises the following steps: positioning (11) the vehicle (1) in front of a projection surface (27); capturing (12) at least one first image of the environment in front of the vehicle (1) in a first operating state of the headlight (2) using the front camera (6); capturing (13) at least one second image of the environment in front of the vehicle (1) in a second operating state of the headlight (2) using the front camera (6); determining (14) an image (20) of the projection of the light image (3) emitted by the headlight (2) using the captured at least one first image and the captured at least one second image;Identifying a feature (25) of the emitted light pattern (3) in the determined image (20, 23) of the projection of the light pattern (3) emitted by the headlight (2) that characterizes the light emission angle (4) of the headlight (2); controlling the light emission angle (4) of the headlight (2) based on the feature (25) of the emitted light pattern (3) that characterizes the light emission angle (4) of the headlight (2) by means of the device for adjusting the light emission angle (4) of the headlight (2).

Description

[0001] The present invention relates to a method for controlling, in particular adjusting and / or regulating, the light emission angle of a vehicle's headlight. The invention further relates to a control device for controlling the light emission angle of a vehicle's headlight, a vehicle, a computer-implemented method, a computer program product, a computer-readable data carrier, and a data carrier signal.

[0002] In light of current and upcoming legal requirements and with road safety in mind, the correct adjustment of vehicle headlights and reliable headlight range control are of particular importance. The beam range of a headlight can usually be adjusted or corrected manually and / or automatically, for example, using a stepper motor. Furthermore, so-called glare-free high beam systems (ADB) and headlights with camera-based dynamic headlight range control (CbADL) are also available.

[0003] The light emission direction of each headlight is subject to individual manufacturing tolerances, which can be several degrees and are due to the specific optics and the headlight's mounting within the vehicle. The "aiming" required at the end of the manufacturing process, in which the headlight's orientation is adjusted to the vehicle, is traditionally done using adjustment screws. Electronic actuation via an electric motor, pixel adjustment, or simply detecting the deviation of the current setting from a target setting are also possible.

[0004] The headlight range adjustment of a vehicle typically involves the following steps. First, the headlight's adjustment position is determined. This requires adjusting the zero angle. Therefore, with the stepper motor angle nominally set, the headlight is calibrated as part of the assembly process to achieve a defined light emission angle. Normally, at the end of the production line, the headlight (on the control side) is set to a "zero position." Since the headlight as a component, as well as its assembly within the overall vehicle system, has significant mechanical tolerances, the angle is subsequently corrected using adjusting screws or electronic control so that the light is emitted at a fixed angle. This process is also referred to as "setting" or "aiming" and provides the adjustment position as a prerequisite for any further compensation.The subsequent headlight range adjustment, also called "leveling", determines changes in the angle between the vehicle and the ground and compensates for the fixed light emission angle or the required deviation from the adjustment position.

[0005] The state of the art in this regard is disclosed, for example, in documents DE 10 2019 207 838 A1, which describes a method for aligning the light beams emitted by the headlights of a motor vehicle, US 10 227 032 B2, which describes a system for adjusting a headlight of a motor vehicle, CN 202 794 722 U and CN 103 373 274 B.

[0006] To measure and adjust the current beam angle of a headlight, special light collection boxes are typically used during manufacturing processes. These boxes are positioned directly in front of the headlight. Similar boxes are also used in workshops to adjust headlights after repairs or during service checks. However, these light collection boxes are expensive, space-consuming, and impact spatial and temporal flexibility in a manufacturing plant or workshop. Furthermore, the boxes require regular maintenance to ensure the necessary precision and functionality. In addition, the precision, especially for horizontal aiming, depends on the exact positioning of the vehicle relative to the test station containing the light collection box.Therefore, the vehicle is typically aligned using pneumatic systems or guide rails before the headlights are adjusted or calibrated. In the field, the availability of suitable light collection boxes is significantly limited. Not all workshops have access to high-quality light collection boxes, a suitable test environment, or personnel qualified for this application.

[0007] Methods for aiming a headlight and / or adjusting or calibrating the beam angle of a front headlight are known, which utilize a camera installed in the vehicle to capture the projection of the headlight's light pattern onto a projection surface. In this case, the quality of the ambient conditions is a crucial factor. Among other things, a dark environment is required in which the headlight's light pattern stands out clearly from the surroundings. Furthermore, the projection surface should be sufficiently defined, in particular homogeneous, and ideally free of any features that could be interpreted as part of the projected light pattern.However, it is desirable to be able to identify and evaluate patterns of a projection of the emitted light image of a spotlight even in less specified or specialized environments, i.e., also under less defined environmental conditions, such as in daylight or generally in bright environments and / or on non-homogeneous projection surfaces and / or in the vicinity of other light sources.

[0008] Against this background, it is an object of the present invention to provide advantageous methods for controlling the light emission angle of a vehicle's headlight. Further objects are to provide an advantageous control device for controlling the light emission angle of a vehicle's headlight, a vehicle, a computer-implemented method, a computer program product, a computer-readable data carrier, and a data carrier signal.

[0009] These problems are solved by a method for controlling the light emission angle of a vehicle's headlight according to claim 1, a control device according to claim 9, a vehicle according to claim 10, a computer-implemented method according to claim 11, a computer program product according to claim 12, a computer-readable data carrier according to claim 13, and a data carrier signal according to claim 14. The dependent claims contain further advantageous embodiments of the invention.

[0010] The inventive method for controlling, in particular aiming or calibrating, and / or leveling or adjusting, the light emission angle, e.g., the vertical and / or horizontal light emission angle, of a vehicle's headlight relates to a vehicle comprising a front camera and a device for adjusting, e.g., controlling, aiming, or leveling, the light emission angle of the headlight, for example, by mechanical or digital actuation. The vehicle, in particular the device for adjusting the light emission angle, can be designed to determine a correlation between the camera's orientation and the orientation of the light emission angle based on images from the front camera. For the sake of simplicity, the front camera will hereinafter be referred to simply as the camera.It can be installed, for example, in the windshield or at the front of the vehicle, on the roof or on other vehicle components.

[0011] The method according to the invention comprises the following steps: In a first step, the vehicle is positioned in front of a projection surface. The vehicle can be positioned at a defined distance to the projection surface, or the distance can be determined using distance sensors.

[0012] In a second step, at least one image of the area in front of the vehicle is captured using the front camera in a first operating state of the headlights, e.g., with the headlights switched off. In a third step, at least one second image of the area in front of the vehicle is captured using the front camera in a second operating state of the headlights, e.g., with the headlights switched on.

[0013] In a further step, an image of the projection of the light emitted by the headlight is determined using at least one first image and at least one second image. In other words, the captured images are evaluated with the aim of isolating an image of the projection of the light emitted by the headlight.

[0014] In a further step, a feature characterizing the light emission angle of the headlight, e.g. a geometric feature, of the emitted light image is identified in the determined image of the projection of the light image emitted by the headlight.

[0015] Subsequently, based on the characteristic of the emitted light pattern that defines the headlight's light emission angle, the headlight's light emission angle is controlled by the headlight adjustment device. Optionally, the distance between the headlight and the projection surface can be determined, for example, using a distance sensor, and used to determine the current light emission angle.

[0016] The described method according to the invention has the advantage of significantly expanding and improving the range of applications and uses of camera-based methods for controlling the light emission angle of a vehicle's headlight. Headlight calibration can thus be performed even at service stations or workshops with limited equipment, or by the user themselves. Compared to calibration methods and systems known from the prior art, which are expensive and complex both during vehicle manufacturing and during operation and maintenance, require installation space, and necessitate trained personnel, special measuring instruments, and a specific calibration stand or setup, the present invention offers a simple, cost-effective, reliable, and robust alternative that can be used flexibly without a special setup or specialized personnel.The present invention also allows lamp adjustment services to be performed outside of workshops. This eliminates the need to adapt workshop equipment for lamp adjustment services.

[0017] In connection with the present invention, the vehicle can be, for example, a motor vehicle or a rail vehicle. The term "control" encompasses both control engineering and regulation. This includes setting in the sense of calibration or aiming, and regulating in the sense of adjustment or leveling. A front camera is understood to be a camera designed to capture images in the forward direction of the vehicle or in the direction of travel. The aforementioned device for adjusting the light emission angle of the front headlight can, for example, include a stepper motor. Alternatively, the adjustment can also be made mechanically, in particular manually.

[0018] A screen or a wall, such as a house or garage wall, can be used as a projection surface. In principle, any background can be chosen onto which the light pattern from the spotlight can be projected.

[0019] In an advantageous variant, the first operating state of the headlight can be an off state, and the second operating state can be an on state. This allows for a very simple and quick execution of the procedure.

[0020] In another variation, the first operating state of the headlight can represent a first beam angle setting, and the second operating state a second beam angle setting. In other words, the two operating states differ with regard to the beam angle. Different angle settings can be achieved, for example, using a stepper motor. This also allows for a very simple and quick execution of the process. Furthermore, features in the images, especially glare at certain angles, which can be incorrectly interpreted as features of the light pattern, can be identified and effectively eliminated. This improves the reliability and accuracy of the process.

[0021] Optionally, the first operating state of the headlight can be a first emission intensity, and the second operating state a second emission intensity. In other words, images of the emitted light pattern can be captured at different intensities, for example, at 0%, 20%, 50%, and 100%. Capturing and evaluating images at different intensities improves the accuracy of the method. In particular, a feature of the emitted light pattern exhibits a defined intensity dependency in the images at different intensities, which can be used to validate that feature.

[0022] Preferably, an image of the projection of the light pattern emitted by the headlight is determined by subtracting the intensities of the first and second images from the captured images. This effectively isolates the image of the beam cone from the background, significantly simplifying further analysis. This allows for reliable application of the method even under daylight conditions or in illuminated environments.

[0023] The characteristic feature of the emitted light pattern in the determined projection of the light pattern emitted by the headlight, which characterizes the light emission angle of the headlight, can be identified as a vertically upper edge and / or a horizontally lateral edge of the projection. For this purpose, the intensity distribution of the determined image can be evaluated, e.g., with regard to areas with a maximum gradient.

[0024] Advantageously, the vertical and / or horizontal light emission angle of the headlight is controlled by means of the method according to the invention.

[0025] The control device according to the invention for controlling, in particular adjusting and / or regulating, the light emission angle of a front headlight of a vehicle, which comprises a front camera and a device for adjusting the light emission angle of the front headlight, is designed for receiving and evaluating images captured by the front camera and for carrying out a previously described method according to the invention. The control device according to the invention has the features and advantages already described above.

[0026] The vehicle according to the invention comprises at least one headlight, a front camera, and a device for adjusting, e.g., controlling, setting, or altering, the light emission angle of the at least one headlight. The vehicle includes a control device according to the invention as described above. The vehicle according to the invention has the advantages already described. The vehicle can be a motor vehicle or a rail vehicle. The motor vehicle can be a passenger car, a truck, a bus, a minibus, a motorcycle, or a moped.

[0027] The computer-implemented method according to the invention comprises instructions that, when the program is executed by a computer, cause it to execute a method according to the invention as described above. The computer program product according to the invention comprises instructions that, when the program is executed by a computer, cause it to execute a method according to the invention as described above. The computer program product according to the invention is stored on the computer-readable data carrier according to the invention. The data carrier signal according to the invention transmits the computer program product according to the invention. The computer-implemented method according to the invention, the computer program product according to the invention, the computer-readable data carrier according to the invention, and the data carrier signal according to the invention have the features and advantages already mentioned above.

[0028] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying figures. Although the invention is illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived from them by a person skilled in the art without departing from the scope of protection of the invention.

[0029] The figures are not necessarily detailed or to scale and may be enlarged or reduced to provide a better overview. Therefore, the functional details disclosed here are not to be understood as limiting, but merely as an illustrative basis to guide those skilled in this field of technology in using the present invention in a variety of ways.

[0030] The expression "and / or" used here, when used in a series of two or more elements, means that each of the listed elements can be used alone, or any combination of two or more of the listed elements can be used. For example, when describing a composition containing the components A, B, and / or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination. Fig. Figure 1 schematically shows a vehicle and a calibration of the light emission angle of a headlight. Fig. Figure 2 schematically shows a method according to the invention for controlling and / or regulating the light emission angle of a front headlight of a vehicle in the form of a flowchart. Fig. Figure 3a schematically shows an image produced without applying the method according to the invention. Fig. Figure 3b schematically shows an image produced within the framework of the method according to the invention. Fig. Figure 4 schematically shows a sub-area of ​​the area in the Fig. Figure 3 shown. Fig. Figure 5 schematically shows the intensity distribution of the [subject] in the Fig. 4 shown sub-area of ​​the illustration of the Fig. 3 in the form of a diagram. Fig. Figure 6 schematically shows the result of an evaluation of the intensity distribution. Fig. Figure 7 schematically shows the evaluation of the intensity distribution in the form of a diagram. Fig. Figure 8 schematically shows a representation of the projection surface with a marking of the area shown in the Fig. 4 and Fig. 6 shown partial area and a marking of the vertical upper edge of the headlight's light image. Fig. Figure 9 schematically shows a vehicle according to the invention with a control device according to the invention.

[0031] The Fig. Figure 1 schematically depicts a vehicle 1, e.g., a motor vehicle. The vehicle 1 includes a headlight 2 and a front camera 6. The light emitted by the headlight 2 has a slope that determines or is influenced by the angle of emission. The reference point is, for example, the upper vertical edge of the light pattern 3. Before calibration (aiming), different headlights 2 typically exhibit different beam angles or slopes of the emitted light 3 relative to the ground or a flat road surface. For various headlights 2 before calibration, exemplary slopes are indicated by lines with reference numerals 4. The desired nominal slope is indicated by a dash-dot line with reference numeral 5.Vehicle headlights are typically calibrated to the nominal light emission angle or gradient 5 after the manufacturing process. This can be done electronically or using adjusting screws. During calibration, the vehicle 1 is usually unloaded.

[0032] The calibrated slope can change over time, particularly due to load, so adjustment or leveling may be necessary. Recalibration ("aiming") may also be required after a headlight repair. Both adjustment and calibration can be performed using a camera, as described earlier, for example, with the front camera 6.

[0033] The following will be based on the Fig. 2. A method according to the invention for controlling, in particular aiming or calibrating, and / or leveling or adjusting, the light emission angle of a headlight 2 of a vehicle 1 is described by means of a flowchart. The method relates to a vehicle 1 which comprises a front camera 6 and a device for adjusting, e.g., controlling or leveling or adjusting, the light emission angle, in particular the horizontal and / or vertical light emission angle, of the headlight.

[0034] The method according to the invention comprises the following steps: In a first step 11, the vehicle is positioned in front of a projection surface, e.g., a wall or a screen. In a second step 12, at least one first image of the environment in front of the vehicle is captured by the front camera in a first operating state of the headlight, e.g., with the headlight switched off, or with a first light intensity of the emitted light, or with a first direction of emission. The method can be carried out individually for each headlight or for several headlights together.

[0035] In a third step 13, at least a second image of the area in front of the vehicle is captured by the front camera under a second operating state of the headlight, e.g., with the headlight switched on, with a second light intensity, or with a second beam direction. The first and second operating states differ from each other with respect to at least one parameter or quantity, for example, with respect to light intensity or beam angle.

[0036] In a fourth step (14), an image of the projection of the light emitted by the headlight is determined using at least one first image and at least one second image. In other words, the captured images are evaluated with the aim of isolating an image of the projection of the light emitted by the headlight. The intensities of the two images can be subtracted pixel by pixel. Thus, an image can be formed from the difference between the two captured images.

[0037] In a fifth step, a feature characterizing the light emission angle of the headlight, e.g., a geometric feature, of the emitted light pattern is identified in the determined image of the projection of the light pattern emitted by the headlight. The feature characterizing the light emission angle of the headlight can be, for example, a sudden drop in intensity in the vertical direction, i.e., an upper or horizontal edge of the projection of the light pattern, and / or a sudden drop in intensity in the horizontal direction, i.e., a lateral or vertical edge of the projection of the light pattern.

[0038] Subsequently, in a sixth step 16, the light emission angle of the headlight is controlled based on the characteristic of the emitted light pattern that characterizes the light emission angle of the headlight by means of the device for adjusting the light emission angle of the headlight.

[0039] The following describes individual steps of the procedure using the Fig. Sections 3a to 8 are explained in more detail. Fig. 3a schematically shows a product produced without application of the inventive method Fig. . In this process, interfering objects 18 are visible both on the projection screen and in the surroundings, which make it difficult to unambiguously identify the characteristic feature (here the horizontal light / dark boundary 19). Fig. Figure 3b schematically shows a diagram created as part of step 14. Fig. For this purpose, the intensity distribution I was used. environment+patternan image captured in step 13 with the headlight switched on, with an intensity distribution l environment subtract from an image captured in step 12 with the headlights switched off l environment+pattern - l environment = I pattern and then the contrast is increased. The image captured in step 12 shows, in this example, only the surroundings, i.e., the projection surface, in this case the projection screen used, as well as the rest of the background with the interfering objects. The image captured in step 13 shows the surroundings, like the image captured in step 12, and additionally a projection of the light emitted by the headlight. The intensity distribution I generated by subtraction pattern isolates the projection pattern 21 of the photograph from the environment 22 and thus enables evaluation even in daylight.

[0040] A possible evaluation of selected sub-areas of the generated Fig. is marked with the reference number 23 and in the Fig. 4 shown enlarged. Fig. Figure 5 schematically shows the intensity distribution 24 of the in the Fig. The section 23 shown in section 4 is presented in the form of a diagram. The x-axis and y-axis represent the pixels of the area in the... Fig. The image plane (xy) shown in Figure 4 is plotted. The z-axis represents the light intensity in arbitrary units. The transition between the projection of the image 21 and the surroundings 22 is characterized by a sudden increase in intensity.

[0041] The further evaluation of the intensity distribution 24 according to step 15 of the method according to the invention is described below using the Fig. 6, Fig. 7 to Fig. 8 illustrated. First, as in the Fig. 6 and Fig. Figure 7 shows the increase or gradient of intensity 24 in the x-direction and the maximum gradient for each y-position. The result, i.e., the positions with the maximum gradient, are shown in the Fig. 6 and Fig. 7 is marked by a line 25 or a plane 25. The line 25 thus determined, extending in the x-direction, marks the upper edge in the vertical direction (y-direction) of the projection of the photograph 21.

[0042] In the Fig. 8 is sub-area 23 and the determined line 25 into the one recorded in step 13 Fig. marked. Fig. Figure 27 shows two screens 27 used for projection in a factory hall in daylight. The projection of the light image from the headlight is very difficult to see with the naked eye; in particular, only the method according to the invention enables a precise identification of the upper edge of the projection of the light image, i.e., line 25.

[0043] In step 16, the beam angle of the headlight can now be controlled or regulated using line 25. Determining the position of line 25 on screen 27 may be sufficient for this purpose. Optionally, the procedure according to steps 12-16 can be repeated as often as necessary to achieve the desired accuracy of the beam angle.

[0044] The described method can be used analogously to adjust the horizontal light emission angle.

[0045] A vehicle 1 according to the invention is used in the Fig. Figure 9 shows schematically. It comprises a control device 10 according to the invention for controlling the light emission angle of a front headlight 2. The control device 10 is for receiving 8 and evaluating images captured by means of the front camera 6 and for executing a function based on the Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7 to Fig. 8 exemplary described methods for controlling 9 the light emission angle of the front headlight 2. Reference symbol list: 1 vehicle 2 headlights 3 photographs 4 slopes of the emitted light of different vehicles before calibration of the light emission angle. 5 nominal slope 6 Front camera 7 Device for adjusting the light emission angle of the front headlight 8 Data and / or signal transmission 9 Data and / or signal transmission 10 Control device 11. Positioning the vehicle in front of a projection surface 12. Capturing at least one initial image of the area in front of the vehicle during an initial operating state of the headlight using the front camera 13. Capturing at least one second image of the area in front of the vehicle during a second operating state of the headlight using the front camera 14 Determining an image of the projection of the light image emitted by the front headlight using the captured at least one first image and the captured at least one second image 15. Identifying a feature of the emitted light pattern in the determined image of the projection of the light pattern emitted by the headlight that characterizes the light emission angle of the headlight. 16 Controlling the light emission angle of the headlight based on the characteristic of the emitted light pattern that characterizes the light emission angle of the headlight by means of the device for adjusting the light emission angle of the headlight. 17. Image produced without application of the method according to the invention 18 disturbing objects 19 Light / Dark Boundary 20 image produced when applying the method according to the invention 21 Patterns of the projection of the photograph 22 surroundings 23 Sub-area of ​​the generated image 24 Intensity distribution 25 maximum gradient 26 captured images 27 projection screen x coordinate axis y coordinate axis z coordinate axis QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2019 207 838 A1

[0005] US 10 227 032 B2

[0005] CN 202 794 722 U

[0005] CN 103 373 274 B

[0005]

Claims

[1] Method for controlling the light emission angle (4) of a front headlight (2) of a vehicle (1), comprising a front camera (6) and a device for adjusting the light emission angle of the front headlight (2), characterized by that the procedure includes the following steps: - Positioning (11) the vehicle (1) in front of a projection surface (27), - Capturing (12) at least one initial image of the area in front of the vehicle (1) during an initial operating state of the headlight (2) using the front camera (6), - Capturing (13) at least one second image of the area in front of the vehicle (1) during a second operating state of the headlight (2) using the front camera (6), - Determining (14) an image (20) of the projection of the light image (3) emitted by the front headlight (2) by means of the detected at least one first image and the detected at least one second image, - Identifying a feature (25) characterizing the light emission angle (4) of the front headlight (2) of the emitted light pattern (3) in the determined figure (20, 23) of the projection of the light pattern (3) emitted by the front headlight (2), - Controlling the light emission angle (4) of the front headlight (2) based on the feature (25) of the emitted light pattern (3) that characterizes the light emission angle (4) of the front headlight (2) by means of the device for adjusting the light emission angle (4) of the front headlight (2). [2] Method according to claim 1, characterized by , that a screen or a wall is used as the projection surface (27). [3] Method according to claim 1 or 2, characterized by , that the first operating state of the front headlight (2) is an off operating state and the second operating state of the front headlight (2) is an on operating state. [4] Method according to any one of claims 1 to 3, characterized by , that the first operating state of the front headlight (2) is a first beam angle setting and the second operating state of the front headlight (2) is a second beam angle setting. [5] Method according to any one of claims 1 to 4, characterized by , that in the first operating state of the front headlight (2) there is a first emission intensity and in the second operating state of the front headlight (2) there is a second emission intensity. [6] Method according to any one of claims 1 to 5, characterized by , that an image of the projection of the light image (3) emitted by the front headlight (2) is determined by means of the captured at least one first image and the captured at least one second image by taking the difference between the intensities of the second image and the first image. [7] Method according to any one of claims 1 to 6, characterized by , that as a characteristic feature of the emitted light pattern (3) in the determined figure (20, 23) of the projection of the light pattern (3) emitted by the front headlight (2) a vertically upper edge (25) and / or a horizontally lateral edge of the projection of the light pattern (3) is identified as the light emission angle (4) of the front headlight (2). [8] Method according to any one of claims 1 to 7, characterized by , that the vertical and / or horizontal light emission angle (4) of the front headlight (2) is controlled. [9] Control device (10) for controlling the light emission angle (4) of a front headlight (2) of a vehicle (1), comprising a front camera (6) and a device for adjusting the light emission angle (4) of the front headlight (2), characterized by, that the control device (10) is designed to receive (8) and evaluate images captured by means of the front camera (6) and to execute a method according to one of claims 1 to 8. [10] Vehicle (1) comprising at least one front headlight (2), a front camera (6) and a device for adjusting the light emission angle (4) of the at least one front headlight (2), characterized by , that the vehicle (1) comprises a control device according to claim 9. [11] Computer-implemented method comprising instructions which, when the program is executed by a computer, cause it to execute a method according to any one of claims 1 to 8. [12] Computer program product comprising instructions which, when the program is executed by a computer, cause it to execute a method according to any one of claims 1 to 8. [13] Computer-readable data carrier on which the computer program product according to claim 12 is stored. [14] Data carrier signal that transmits the computer program product according to claim 12.

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