DE2932461A1 - METHOD FOR EVALUATING THE QUALITY OF THE WIPER BLADE / DISC SURFACE SYSTEM - Google Patents

Description

ROBERT BOSCH GMBH ₃ 7OOO Stuttgart 1

Procedure for assessing the quality of the system
Wiper blade / windshield surface

In the field of automotive engineering, there is a need to Quality of the wiper blade / windshield system both in the development and manufacturing phase as well as after a longer period of operation on the vehicle can be assessed rationally and objectively. In addition to an integral evaluation, statements about the wiper blade quality in partial areas of the wiper field are required or on the surface quality of the window in partial areas of the window as well as an assessment of the wiper Water residues left behind or the scratched and contaminated pane according to their effect on perception of the driver taking into account his tasks in traffic. A suitable, automatically working one Measurement method is proposed.

It is known that if the wiper blade quality is poor, this is the case Residual water or, in the case of poor window surface quality, the scattered light resulting from scratches and impurities leads to a reduction in the contrast of the visual objects perceived by the driver. In the case of low-contrast visual objects which makes it difficult or impossible for the driver to perceive them.

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Driving at night on a road without stationary lighting with oncoming traffic proves to be particularly critical. Conditional more oncoming due to the high light intensity of the headlights Vehicles and the weak lighting of objects to be seen by the driver, e.g. pedestrians, becomes the Degree of contrast reduction and thus the influence on perception essentially due to the oncoming of the vision lights Vehicles outgoing and to the water residues on the hydrophobic pane or to the Scattered light is determined by scratches and dirt on the disc. It is therefore useful to check the wiper blade quality based on the location and time dependency, or the pane surface quality based on the location dependency of the scattered light intensity judge au.

Methods for assessing the quality of the wiper blades have already been described. Methods of assessing quality on the other hand, no motor vehicle eyewear surfaces are known. Two frequently used to assess the wisdom sheet quality The methods used are the "gray field method" and the "modified Töpler'sehe Schlieren method". Benefit from this the "gray field method" the different reflection properties wetted and unoccupied glass surfaces and makes the pane areas covered by water visible. The tester assesses the quality of the wiper blade on the basis of the water residues left in the wiper field by the wiper blade. The "modified Töpler's-see Schlieren method" records integrally the water emanating from a lighting device and on the water residue remaining in the wiping field during the wiping process diffused light. The scattered light produced in the wiped field is for this purpose with the help of optical means on a The photo receiver is shown and the time-dependent light intensity measured in this way is evaluated to assess the quality of the wiper blade .

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A disadvantage of one of these methods is that when assessing the quality of the wiper blade, the effect of the wiper blade Water residues left behind in the wiping field are not sufficiently taken into account on the driver's perception. In addition, when assessing Wischerm with the help of the "modified Töpler's view Schlieren method", only integrals are used Statements made about the wiper blade quality.

According to the invention a method is proposed that one automatic assessment of the wiper blade / screed surface system both in a test setup and in the installed state on the vehicle and the above! disadvantage avoids. The basic measurement setup, shown in FIG. 1 in a view from above and in FIG. 2 from the side, consists in addition to the wiper blade / windshield surface system, a lighting device 2 that illuminates a windshield 1 and an ffl image sensor 3, which detects the scattered light produced on the pane 1 recorded. It is essential here that no direct light from the lighting device 2 on the Measurements used photosensitive part of the image sensor falls. The output signal of the image sensor 3 thus provides information on the location and time dependency of the Disk 1 produced scattered light available for evaluation. The assessment of the wiper blade quality and the surface quality of the pane is now carried out by comparing the measured with the specified values of the scattered light intensity or by comparing parameters derived therefrom, with the Location and time dependency of the scattered light intensity, or the location dependency to assess the surface quality of the pane the scattered light intensity is taken into account.

Basically, this method is an assessment of the quality of the wiper blade / windshield system among a multitude different boundary conditions possible. As boundary conditions

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the lighting of the window and, in the case of the assessment of the wiper blade quality, also the condition of the window and the composition of the washer fluid are to be understood. They are to be selected in such a way that evaluable scattered light effects occur. In particular, when assessing the quality of the wiper blades, the possibilities range from a uniformly illuminated, hydrophilic window and a light-scattering additive, for example from 2 to 20 % latex balls or salt crystals to the wiper fluid, to real traffic situations simulating boundary conditions, for example an illumination of the window like you do when driving at night there is oncoming traffic and a realistic, hydrophobic one. Degree of wetting of the washer fluid / disc system. Under certain circumstances, however, to achieve an assessment taking into account the influence on the driver's perception, realistic boundary conditions are to be aimed for and, for reasons of effort, permitted deviations from reality when processing the measured values as well as when determining the standard for assessing the wiper blade or windshield surface quality Comparative values and parameters must be taken into account.

The actual effect of the light scattered on the windshield, that is, the effect on the driver's retina Scattered light distribution is determined by the fact that the image sensor, due to its position, the focal length and the The size of the aperture, its imaged optics and its distance from the photosensitive layer of the image converter, the window is out of focus analogous to the driver's eye. In addition, there is the possibility of sharply imaging the pane and the two-dimensional optical low-pass operation given in reality by the blurred image in the eye to be carried out exactly or approximately during the subsequent electronic processing of the measured values, or by a one-dimensional one Low-pass operation, for example to assess the wiper blade quality perpendicular to the wiper blade movement

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means to approach in a radially symmetrical wiped field along the wiped field radii.

The characteristics of the human visual system, the tasks of the driver in real traffic and those of the Conditions deviating from reality when assessing the wiper blade quality j or the windshield surface quality are used when determining the values for comparison with the measured values that are location- and time-dependent or location-dependent Scattered light intensity or the parameters derived from it are taken into account. So when assessing the Wiper blade quality - the same is done when assessing the windshield surface quality - for example the maximum permissible scattered light intensity in an area at a certain point in time after passing through the wiper blade determined in such a way that the perception performance during the optical recording of information through this area of the wiped field do not fall below a limit value. This limit value can be given, for example, by the requirement that the maximum Detection distance for a traffic-relevant obstacle, for example a pedestrian, is 50 m. As a maximum Detection distance is understood as the maximum distance from which an observer can decide whether an interesting Object exists or does not exist.

It is also proposed to compensate for changing boundary conditions, for example fluctuations in the ambient lighting, Changes in the surface condition of the disc, etc., an automatic one, for example before each series of measurements carried out adaptation of the specified for assessing the wiper blade quality or the windshield surface quality Carry out comparison values, parameters or the parameters that determine the processing of the measured values. A determination The current boundary conditions are better known through control measurements, for example with wiper blades or on windows Quality or through targeted measurements of some parameters,

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for example the degree of wetting of the washing liquid and Disc surface, surrounding lighting, etc. possible.

An assessment of the wiper blade quality, or the windshield surface quality, taking into account the wiping performance in the complete wiping field, or the scratches and contamination of the entire windshield surface is desirable, but by: For cost reasons, processing is only possible in special cases. It is therefore suggested that when assessing the wiper blade quality or the windshield surface quality, the part of the wiper field or the billets located in the driver's central viewing area should be limited, and / or to assess the wiper blade quality or the windshield surface quality, the location dependency of the To determine and evaluate the scattered light intensity one-dimensionally, for example in a radially symmetrical wiped field along a wiped field diameter, in one or a few representative areas of the wiped field or the window. If you see the addition of light-scattering substances or substances that increase surface tension, for example ζ wetting agents for washing water or of

the use of some of their washing liquids is a must A certain disadvantage of the method proposed above for assessing the wiper blade quality is that for the Kessungen an at least slightly hydrophobic wiping surface is necessary. This can be avoided if the different ones come to one Reflection properties of wetted and unwetted glass surfaces using methods passed over will.

The principle of the measuring arrangement proposed for this purpose is shown in a side view in FIG.

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The wiper blade 4 to be assessed runs on the test disc 5, which is illuminated by a, for example, flat or diffuse lighting device 6. The light reflected from wetted and unwetted parts of the pane 5 is detected by an image sensor 7. The contrast between wetted and unwetted areas is increased by a light-absorbing V / and 8 behind the pane or by a light-absorbing layer on the rear wall of the pane. Due to the lower reflectivity of the wetted window compared to the dry window *, the water residues remaining in the wiped area appear darker than the dry areas of the window. By comparing the luminance distribution measured during the wiping process with the dry pane, the water residues remaining in the wiping field can be detected. To assess the wiper blade quality, the location and the temporal disappearance of the water residues due to evaporation effects are evaluated. For example, at suitable times of the wiping process, the areas of the parts of the wiping field covered with water residues left behind by the wiper blade are determined and evaluated for assessment, with a location-dependent weighting of the individual area proportions being useful. It is further proposed to reasons of expense in assessing the wiper blade quality on the located in the central vision of the driver part of the mop ^f Eldes to restrict and / or remaining in the wiping field water residues one-dimensional, for example in a radially symmetrical wiping field along a wiping field diameter, in one or To determine a few representative areas of the wiper field and to evaluate them to assess the wiper blade quality.

The processing of the measured values required in the proposed method is carried out with methods known per se from analog and digital technology. Figure 4 shows as an example the signal processing stages of a simple evaluation circuit

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to assess the quality of the window cleaning or the Wiper blade. The output signal of the image sensor 9 is converted by an analog-to-digital converter 10 and by a comparator 11 compared word by word with given values.

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The comparison results / weighted with the aid of a multiplier 12 with predetermined weighting factors and the weighted values are added up by an adder 13. The sum thus obtained is output as a measurement result on a display unit 14. The comparison values and weighting factors are stored in memories 15, 16.

The image sensors are cameras with conventional pick-up tubes, or vidicons or semiconductor image converters, or one- and two-dimensional CCD arrays, are suitable. To increase the Several image sensors can be used for measuring accuracy or to simplify the processing of measured values.

In a ¹ with salt crystals dissolved in the washing liquid, for example 2 % to 20 % in Na CL or NHj, CL, / working method, the salt solution is applied to the window and wiped once with the wiper blade to be tested. Since the residual solution remaining on the pane evaporates quickly, ν-- the crystallized salt crystals are registered. This has the following advantages:

The process is independent of the condition of the pane (hydrophilic or hydrophobic), temperature, humidity and air currents.

The salt crystals scatter the light in all directions.

The scattered light provides an exact measure, largely free of interfering influences, for the various under the wiper lip The amount of water that has passed through the disc.

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The scattered light does not change during observation or measurement.

The scattered light from the salt crystals can also be registered from one side of the windshield. This simplifies the measuring device.

An optical arrangement suitable for this is shown in FIG. 5- An incandescent lamp 101 illuminates the intended test field of the windshield 103 via the condenser lens 102 'at an angle cC of approximately 20 to 30. The scattered light receiver with the lens 104, the field stop 105, the photo element 106 and the micro-ampereaeter 107 is approximately perpendicular to the window. After the window 103 has been sprayed with an aqueous salt solution, the wiper is actuated. After passing through the wiper blade, the remaining liquid and the salt evaporate within a few seconds. The scattered light can then be measured immediately. Standard wipers or a standard spreader, for example a dull gray paper sample, can be used to calibrate the scattered light measuring device.

An arrangement as in FIG. 6 can be used for the qualitative visual comparison of used wiper blades with new ones. the end In the vehicle interior, the driver looks from point 110 from his normal sitting position against a dark wall 111. A headlight 112 illuminates the windshield 103 from above, so that the point 110 is currently not illuminated. That after Salt that has crystallized out in one swipe becomes visible and used and new wiper blades can be compared.

The measurement value processing described above can also be used with this method be subordinated.

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Claims (1)

July 18, 1979 Sat / Sm ROBERT BOSCH GMBH, 7OOO Stuttgart 1 Expectations 1. Procedure for assessing the quality of the wiper blade / windshield surface system through optical observation of scattering, reflection and refraction of light during the wiping process Washing liquid residues remaining in the wiping field, characterized in that when the wiping field is illuminated, or the window with a light source at residues scattered and reflected by the wiper blade in the wiping field and refracted light detected with an image sensor and the thus determined location and time dependency, or the so determined Location dependence of the light intensity for assessing the wiper blade quality or the windshield surface quality is evaluated with per se known methods of analog and digital electronics. 130009/0367 ORiGfMAL INSPECTED - 2 - R. 56H Sat / Sm [NACHQERBOHTj 2. The method according to claim 1, characterized in that the assessment of the wiper blade quality by comparing the, v / uring the wiping process, location and time-dependent values of the scattered light intensity or values derived therefrom Parameters with predetermined values or parameters takes place. 3. The method according to claim 1, characterized in that the assessment of the disc surface quality by comparison the measured location-dependent values of the scattered light intensity or parameters derived therefrom with specified values Values or parameters. H. Method according to one of Claims 1 to 3, characterized in that the luminance distribution of the surrounding area, for example illuminating the pane with a strong light source in a darkened room, results in evaluable scattered light effects. 5. The method according to any one of claims 1, 2 or 4, characterized characterized in that by a 2 to 20 $ igen addition of a light-scattering substance to the washing liquid or by the Changing the surface tensions of the washing liquid and / or the pane surface, for example with surfactants and / or water repellants ^ evaluable scattered light effects arise. • • / 3 130009/0367 ORIGINAL INSPECTED - 3 - R-56ιU Sa / Sin NACHQEREIOHT 6. The method according to claim 5 _5, characterized in that microscopic latex balls are used as the light-scattering substance. 7. Method according to claim 5, characterized in that soluble salt crystals are used as the light-stabilizing substance. 8. The method according to claim 5, characterized in that insoluble salt crystals are used as the light-scattering substance. 9. Method according to one of Claims 5 to 8, characterized in that that the lighting and the scattered light measurement from one side, for example from the outside of the windshield made photoelectrically. 10. The method according to any one of claims 5 to 9 _3, characterized in that the scattered light emanating from the illuminated pane is assessed from the light-illuminated driver's seat. 11. The method according to any one of claims 1 or 2, characterized in that that for assessing the wiper blade quality based on real traffic situations, for example an illumination of the V. table field, as shown in 130009/0367 - ^Μ ORIGINAL INSPECTED R. Sa / Sm driving at night with oncoming traffic and a hydrophobic degree of wetting of the washing liquid / Disc surface are created. - 12. The method according to any one of claims 1 or 3j, characterized in that that for assessing the pane quality based on real traffic situations oriented boundary conditions, for For example, a lighting of the window, as it occurs when driving at night with oncoming traffic, can be set. Method according to one of Claims 1 to 9, characterized in that boundary conditions deviating from reality, for example an unrealistically illuminated window, are used when processing the measured values and when determining the comparison values and / or Parameters are taken into account. 14. The method according to any one of claims 1 to 13, characterized in, that by the position, the focal length and size of the aperture of its imaging optics and their distance from the photosensitive layer of its image converter, the image sensor analogous to the eye of the driver of a motor vehicle, the wiped field or the window is out of focus. ../5 130009/03 6 7 ORIGINAL INSPECTED Sat / Sm 15. Method according to one of Claims 1 to 14, characterized in that that one of the features of claim 14 deviating Measurement of the scattered light distribution is exactly or approximately compensated for in the processing of the measured values. 16. The method according to any one of claims 1 to 15, characterized in that that the for comparison with the measured location- and time-dependent or location-dependent values of the scattered light intensity or parameters derived therefrom, predetermined values or parameters of the properties of the human vissuelien system and the tasks of the driver in real traffic. 17. The method according to any one of claims 1 to l6, characterized in that that an automatic adjustment of the given comparison values, for example before each series of measurements, Characteristics or the parameters determining the measured value processing takes place on changing boundary conditions, and that the necessary determination of the current boundary conditions through control measurements, for example with wiper blades, or on panes of known quality or by targeted measurement of individual parameters, for example the degree of wetting of the washing liquid and the surface of the pane, the surrounding lighting etc., is performed. 130009/0367 ORIGINAL INSPECTED Sat / Sm [nachqerejoktJ 18. The method according to any one of claims 1 to 17, characterized in, that the assessment of the wiper blade quality or the windshield surface quality is based on the central The driver's field of vision is restricted to the part of the wiped field or the window. 19. The method according to any one of claims 1 to 18 _}, characterized in that the location dependency of the scattered light intensity is determined one-dimensionally, for example in a radially symmetrical wiped field along a wiped field diameter, in a few or a few representative areas of the wiped field or the window. 20. The method according to claim 1, characterized in that by comparing the during the wiping process in reflection ■ measured luminance distribution with that of the drier: the remnants of the disc remaining in the wiped field Washing liquid can be detected and that the location and / or the temporal disappearance of the washing liquid residues due to evaporation effects for assessing the wiping quality is evaluated. 21. The method according to any one of claims 1 or 20, characterized in, that the assessment of the wiper blade quality is limited to the central area of the wiped field. ../7 130009/0367 ORIGINAL INSPECTED - 7 - R. 56iU Sat / Sn 22. The method according to any one of claims 1, 20 or 21, characterized in that for assessing the wiper blade quality the remnants left in the wiped field one-dimensional, for example in a radially symmetrical wiped field along a wiped field diameter, determined and evaluated in one or a few representative areas of the wiped field will. 23. Procedure according to one of the. Claims 1 to 22, characterized in that that the image sensor is a camera with a conventional image pickup tube, for example Vidicon or with a solid-state image converter, for example a CCD array, is used. 2k. Method according to one of Claims 1 to 23 , characterized in that the location-dependent and time-dependent or the crts-dependent light intensity is recorded with a plurality of image sensors. 130009/0367 ORIGINAL INSPECTED