Apparatus and method for inspecting a surface by wavelength analysis - Patents.com

Abstract

The apparatus (1) for investigating the surface properties of lacquered surfaces, in particular automobiles, comprises a first illumination device (2) for illuminating the surface (10) to be investigated at a first illumination angle (a1), a second illumination device (12) for illuminating the surface (10) at a second illumination angle (a2), and a first sensor device (4) for recording radiation reflected and / or scattered by the surface illuminated at the first recording angle by the second illumination device (2) and for outputting at least one value which is characteristic of the radiation reaching the sensor device from the surface, the apparatus (1) comprising a radiation analysis device (4) for analyzing the radiation scattered and / or reflected by the surface in terms of its wavelength.

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for investigating surface properties, particularly optical surface properties. [Background technology]

[0002] Such devices are known from the state of the art for inspecting surfaces, for example surfaces of motor vehicles, which may be highly complex coatings that in addition to the base coat also have other lacquer layers, in particular lacquer layers with effect pigments. Such effect pigments create different optical impressions that also depend on the direction of observation and / or the type of incident light, for example diffuse or directional lighting. Summary of the Invention

[0003] The object of the present invention is to enable such surfaces to be evaluated as comprehensively and accurately as possible. According to the invention, this is achieved by the subject matter of the independent patent claims. Advantageous embodiments and further developments are the subject matter of the dependent claims.

[0004] An apparatus according to the invention for inspecting lacquered surfaces, in particular automotive surfaces, in particular for inspecting surface properties, has a first illumination device and / or a radiation device which illuminates the surface to be inspected at a first illumination angle (and / or emits radiation onto this surface).

[0005] Additionally, the apparatus has a second illumination device for illuminating the surface at a second illumination angle. Preferably, the first illumination angle and the second illumination angle are different from each other.

[0006] Further, the apparatus has a first sensor device which records reflected and / or scattered radiation from the surface illuminated by the second illumination device at a first recording angle and outputs at least one value which is characteristic of the radiation reaching the sensor device from the surface.

[0007] According to the invention, the apparatus comprises a radiation analysis device for analyzing the radiation scattered and / or reflected by the surface in terms of its wavelength.

[0008] Preferably, the radiation analysis device records the radiation illuminated by the first illumination device onto the surface and scattered and / or reflected by the surface, in particular the scattered radiation.

[0009] The applicant has determined that in multi-angle color measurements, the main focus of obtaining information about a surface, i.e. color measurement at different angles, can be supplemented by measuring gloss behavior. In the case of an automotive lacquer with a base coat and clear coat finish, a spectrally resolved gloss measurement using a radiometric device can take into account the influence of the base coat color on the measurement of the gloss level of the clear coat.

[0010] This allows for a wider range of evaluation options than classical non-spectrally resolved gloss measurements, where illumination is done with a specified standard light and detected using v-λ filtering (corresponding to the sensitivity of the human eye).

[0011] The value which is characteristic of the radiation reaching the sensor device from the surface is preferably the intensity of this radiation.

[0012] Preferably, the sensor device detects an integral characteristic of the recorded radiation, in particular an integral over multiple wavelengths.

[0013] As will be explained in more detail below, the radiation analysis (by performing integration) preferably also functions as the first sensor device.

[0014] Thus, preferably, the radiation analyzing device performs a spectral analysis of the radiation impinging on it, in particular of the radiation originating from the first illumination device, while it also integrates these spectral components to obtain an intensity integrated over wavelength, in particular of the radiation originating from the second illumination device.

[0015] Preferably, the apparatus comprises a housing in which the first sensor device, the radiation analysis device and / or the illumination device are arranged.

[0016] In a further advantageous embodiment, the apparatus comprises a control device for controlling the illumination device. This control device can be designed to control the illumination of the surface by the illumination device in an alternating and / or time offset manner. In this way, the surface to be illuminated from different directions and the scattered radiation can be analyzed by the radiation analysis device, while the surface to be illuminated and the radiation reflected from the surface can be detected by the sensor device.

[0017] In a further preferred embodiment, the directions of incidence or illumination of all incoming and outgoing radiation lie in one plane, which means that the illumination and observation of the surface takes place in one plane, which is preferably perpendicular to the surface to be examined.

[0018] In a further advantageous embodiment, the at least one lighting device comprises a light emitting diode (LED). In particular, the at least one lighting device comprises a white light LED. Preferably, the at least one lighting device emits standard light, in particular D65 standard light. Standard light refers to a standardized spectral radiation distribution curve of a characteristic emitter. The D65 standard light type is a radiation distribution with a color temperature of 6504 Kelvin (approximately corresponding to a gray cloudy sky).

[0019] In a further preferred embodiment, the device has at least one, preferably at least two lens devices, in particular achromatic lens devices. In a further advantageous embodiment, the device has at least one segmented lens device. In this way, installation space can be saved. These lens devices are preferably arranged in the beam path between the illumination device and the surface to be examined.

[0020] In a further preferred embodiment, the one or more lens devices are arranged in the beam path between the surface and the sensor device and / or the radiation device. In a further advantageous embodiment, the one or more lens devices are arranged between the one or more illumination devices and the (to be inspected) surface.

[0021] Preferably, the at least one illumination device emits diffuse light onto the surface to be inspected. Preferably, the at least one illumination device emits directional radiation onto the surface to be inspected. Particularly preferably, the illumination device, the illumination of which is recorded by the radiation analysis device, emits directional radiation onto the surface.

[0022] In a further preferred embodiment, the radiation analysis device and the first sensor device record the radiation scattered and / or reflected by the surface at the same recording or detection angle.

[0023] In a further preferred embodiment, the radiation analyzing device and the first sensor device are arranged at the same location and / or at the same (angular) position.

[0024] In a further advantageous embodiment, the radiation analysis device is also a component of the sensor device and / or the radiation analysis device also functions as the first sensor device. The sensor device and the radiation analysis device are preferably one and the same component, i.e. preferably a spectrometer. This embodiment is particularly cost-effective. However, it is also conceivable to design the sensor device and the radiation analysis device as separate components and / or separately.

[0025] In a further advantageous embodiment, the radiation analysis device comprises a spectrometer and / or a monochromator, preferably capable of analyzing wavelengths in particular in the visible wavelength range, ie in particular in the range from 400 nm to 700 nm.

[0026] In a further advantageous embodiment, the radiation analysis device is arranged to record the radiation irradiated onto the surface by the at least one illumination device and the radiation scattered by the surface, and furthermore, the radiation analysis device is also arranged to record the radiation irradiated onto the surface by the at least one illumination device and the radiation reflected from the surface.

[0027] In a further preferred embodiment the apparatus comprises a third illumination and / or radiation device arranged relative to the surface at a third illumination angle and / or irradiating the surface with radiation at a third illumination or irradiation angle.

[0028] Preferably, the radiation analyzing device also records the radiation that is illuminated by the third illumination device onto the surface and scattered thereby (also in the direction of the radiation analyzing device). Preferably, the radiation analyzing device outputs a spectrally resolved signal for this radiation.

[0029] In a further preferred embodiment, at least one illumination angle is between 30° and 60°, preferably between 35° and 55°, preferably between 40° and 50°, particularly preferably 45°. An angle of 0° is understood to be the angle at which one direction is perpendicular to the surface to be examined or inspected.

[0030] In a further preferred embodiment, the at least one illumination angle is between 5° and 40°, preferably between 5° and 30°, preferably between 10° and 20°, particularly preferably about 15°. An angle of 0° is understood to be the angle at which one direction is perpendicular to the surface to be examined or inspected.

[0031] In a further advantageous embodiment, at least one illumination angle is greater than 60° (relative to the vertical), preferably greater than 65°, preferably greater than 70°, preferably greater than 75°, particularly preferably greater than 80°. This means that the radiation is emitted at a very flat angle onto the surface to be inspected. At such angles, the aforementioned effect pigments preferably have a relatively small influence on the illumination of the observation.

[0032] Preferably, the radiation is observed or analyzed by the radiation analysis device at an angle of (+ or -) 45°. Irradiation is therefore preferably performed at an angle of - or + 45°. This means that the radiation analysis device preferably also records the reflected radiation.

[0033] In a further advantageous embodiment, the apparatus comprises a fourth illumination device, which is arranged at a fourth illumination angle relative to the surface. Thus, in this embodiment, the apparatus preferably comprises a total of four illumination devices, which are particularly preferred for illuminating and / or irradiating the surface at four different angles. Preferably, all of these illumination devices are arranged such that all of the radiation incident on the surface is in one plane.

[0034] Preferably, the radiation analyzing device also records the radiation that is illuminated by the fourth illumination device onto the surface and scattered thereby (also in the direction of the radiation analyzing device). Preferably, the radiation analyzing device outputs a spectrally resolved signal for this radiation.

[0035] In a further preferred embodiment, at least one illumination device is suitable and adapted to irradiate radiation of different wavelengths onto the surface. This can be done, for example, by different color filter elements arranged between the illumination device and the surface. For example, the different color filters can be arranged on a filter wheel. It is particularly preferred that this type of filter device is between the illumination device and the surface to be inspected.

[0036] It is also possible to place a filter element between the illuminated surface or the surface to be inspected and the image capture device.

[0037] In a preferred embodiment, the device is movable relative to the surface to be interrogated, for example the device can be a portable device or can be located on a robotic device.

[0038] In a preferred embodiment, the (especially relative) position of the device with respect to the surface to be examined can be recorded. For example, several measurements can be recorded at different positions of the surface and these measurements can be compared with each other. In particular, the relative position of a first measurement position with respect to a second measurement position can also be recorded.

[0039] In a further advantageous embodiment, the apparatus comprises a memory device suitable and adapted to at least temporarily store the recorded measurement results, in particular both the values ​​recorded by the sensor device and the values ​​recorded by the radioanalytical device. Preferably, these values ​​can be stored in particular together with an assignment to an area or location of the recording.

[0040] The invention further relates to a method for investigating surface properties, in particular of a lacquered surface of a motor vehicle (and in particular of the exterior surface of a motor vehicle), wherein a first lighting device illuminates the surface to be investigated under a first lighting angle.

[0041] Further, the second illumination device illuminates the surface at a second illumination angle, and the first sensor device records radiation reflected and / or scattered from the surface illuminated by the second illumination device at the first recording angle and outputs at least one value that is characteristic of the radiation reaching the sensor device from the surface.

[0042] According to the invention, the radiation analysis device analyses radiation scattered and / or reflected by a surface, in particular with respect to its wavelength, in particular radiation scattered and / or reflected from the surface as a result of illumination by at least one illumination device.

[0043] Particularly preferably, the radiation analysing device outputs at least one value, preferably a plurality of values, which are characteristic of the spectral properties of the radiation impinging on the radiation analysing device.

[0044] Therefore, the method also proposes to perform a wavelength-dependent analysis of the radiation falling on the radiation analysis device.

[0045] In a preferred method, said radiation and / or lighting devices are activated with a time delay.

[0046] In a further preferred method, both the measurements output by the image recording device (which are particularly characteristic of the intensity of the incident radiation) and the data recorded by the radiation analysis device are taken into account for the assessment of the surface properties.

[0047] In a further preferred method, an illumination device illuminates the surface with radiation and a radiation analysis device records the radiation illuminated by the illumination device and reflected by the surface.

[0048] In a further preferred method, the radiation analyzing device analyzes the radiation or light using a spectrometer.

[0049] Preferably, the radiation analysis device outputs a signal characteristic of the wavelength or wavelength distribution of the radiation impinged on and / or emitted by the surface, in particular this makes it possible to evaluate the frequency spectrum at which the surface reflects the radiation, which is particularly important for the evaluation of lacquer coatings with effect pigments.

[0050] Preferably, the wavelength-dependent distribution detected by the radiation analysis device is also integrated over a wavelength range and the integrated intensity of the incident radiation is thus determined, in particular for radiation applied at a reflection angle, i.e. in particular for radiation applied by the second illumination device.

[0051] In a further preferred method, a third illumination device illuminates the surface at a third angle, preferably different from the aforementioned first and second angles. Preferably, radiation emitted from the third illumination device and scattered by the surface is also recorded (at least in part) by a radiation analysis device and analysed with respect to its wavelength (i.e. in particular spectrally).

[0052] In a further preferred method, the colour of at least one of the illumination or illumination radiation is at least temporarily changed.

[0053] In a further preferred method, the radiation detection device records and analyzes the radiation emitted onto and reflected from the surface at several positions on the surface to be examined, in this way measurement data can be recorded from several areas of the surface.

[0054] Preferably, the data and / or values ​​recorded at several points on the surface are compared with each other. In this way, the gloss behavior of the surface to be investigated (i.e. the behavior that can be determined by the radiometric analysis device) can preferably be determined and evaluated over a larger area of ​​the surface.

[0055] Preferably, the recorded data is assigned to the location on the surface where each measurement was made.

[0056] Further advantages and embodiments are shown in the accompanying drawings. [Brief description of the drawings]

[0057] [Figure 1] 1 shows a schematic diagram of an apparatus according to the present invention. [Diagram 2] FIG. 1 shows a diagram for explaining beam analysis. [Diagram 3] 1 shows a further example of a state of the art device. [Figure 4] Further examples of the present invention are given below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] 1 shows a schematic diagram of an apparatus 1 according to the invention, comprising a first illumination device 2 which illuminates or emits light at a first illumination angle a1 onto a surface 10 to be inspected. A sensor device 4 records radiation scattered or reflected by the illuminated surface, in particular the scattered radiation.

[0059] Reference number 16 denotes a housing inside which the described components are arranged. Preferably, the inner walls of this housing are designed to absorb radiation. Reference number O denotes an opening through which the surface 10 can be illuminated and / or observed.

[0060] Reference number 12 identifies a second illumination device, which also emits radiation onto the surface at a predetermined angle a2, here 45°. Reference number 14 identifies a radiation analysis device, which records the radiation emitted by the illumination device 12 onto the surface and reflected by it, and analyzes the radiation in terms of its wavelength. The radiation analysis device also functions as the sensor device 4.

[0061] Reference number 6 denotes a further illumination device which illuminates the surface at a very flat angle. The radiation analysis device 14 preferably records radiation from the surface illuminated by the illumination device 6 (or records radiation illuminated on the surface by the illumination device 6 and reflected and / or scattered by the surface, in particular the scattered radiation). It is therefore proposed that the surface 10 is illuminated at different angles and that the radiation reflected and / or scattered by the surface is in each case recorded by the radiation analysis device.

[0062] Reference number 8 denotes a further illumination device which here also illuminates the surface 10. A radiation analysis device 14 also records the radiation emitted by the further illumination device and reflected and / or scattered by the surface.

[0063] Thus, in the embodiment shown, the surface is illuminated from three different angles and the radiation analysis device records the radiation scattered by the surface in each case and performs a spectral analysis of this radiation.

[0064] Reference sign a1 denotes a first angle of incidence or illumination (relative to the vertical) at which the first lighting device 2 illuminates the surface 10. This angle is 30° in this case. Reference sign b1 denotes a fourth angle of incidence at which the lighting device 8 illuminates the surface 10. This is here 0°, so that the illumination is perpendicular to the surface 10. However, this illumination can also be at a predefined angle that is not 0° but is preferably less than 20° (relative to the vertical), preferably less than 10°.

[0065] Reference a2 identifies a second angle of incidence and / or illumination at which the second radiation device 12 emits radiation onto the surface 10. This second angle of incidence and / or illumination angle is here 45°. Reference b2 denotes a second recording angle at which the radiation analysis device 14 and the sensor device are positioned relative to the surface 10 or at which the reflected radiation is recorded. In this case this angle is -45° relative to the surface 10.

[0066] Reference sign a3 denotes a third angle of incidence and / or illumination at which the third radiation device 6 illuminates the surface 10. In this case this is approximately -70°. Optionally, a fourth radiation device may be provided which illuminates the surface at a further angle of incidence and / or illumination.

[0067] Reference number 20 generally identifies a control device which causes the illumination of the surface from different angles with a time delay.Furthermore, the apparatus preferably comprises a storage device (not shown) in which the data recorded by the radiation analysis device are stored.

[0068] The sensor device 4 used to detect radiation reflected from the surface 10 also uses a radiation analysis device, but an integrating device (not shown) again integrates the recorded spectrum over wavelength and therefore outputs an integral value for intensity.

[0069] Figure 2 shows the gloss measurement process in more detail. Preferably, the second illumination device 12 emits radiation onto the surface 10 at an angle of 45° (relative to the vertical) and the radiation analysis device records the radiation reflected from the surface at the reflection angle (here -45°). Preferably, the illumination device emits standard light, in particular D65 standard light. Furthermore, the illumination device preferably emits directional radiation onto the surface.

[0070] The sensor device 4 records the reflected radiation. The radiation analysis device 14 can analyze the radiation impinging on it more precisely, preferably with respect to its wavelength, and can output an intensity distribution in the wavelength range preferably from 300 nm to 900 nm, preferably from 350 nm to 800 nm, particularly preferably from 400 nm to 700 nm. However, as a measured value for this measurement, the integral of the intensity over the wavelength is output. Due to this integral, the radiation analysis device is also referred to here as sensor device 4.

[0071] Figure 3 shows an apparatus according to the applicant's internal prior art: here again one can see the illumination devices 2, 6 and 8, each of which emits radiation onto a surface, and the sensor device 4, which records the radiation reflected and / or scattered by the surface.

[0072] Figure 4 shows a schematic diagram of an apparatus 1 according to the invention. Here, an illumination device 12 is also provided, which illuminates the surface at an angle of 45° in this case. This illumination device is preferably a white light LED. This illumination device is preferably arranged in a light trap 13. A collimating lens device (not shown) can be arranged in front of this illumination device. This illumination device 12 is preferably positioned at an angle of specular reflection in the direction of a radiation analysis device 14 or a spectrometer.

[0073] Thus, reference 14 denotes a radiation analysis device, which at the same time also functions as a sensor device 4. The device 14 comprises a spectrometer, reference 15 denotes a dispersive element.

[0074] This allows the incident radiation to be resolved across many wavelengths.

[0075] Furthermore, the spectrum analyzing device also comprises an integrating device 17 which integrates the signal from the spectrum analyzing device outputted via all channels, this integration being performed in particular via the radiation emitted by the illumination device 12 and reflected to the radiation analyzing device 14.

[0076] In this way, a very simple and inexpensive gloss measurement can be realized, which can in particular be supplemented by the color measurement by using a spectral analysis device for gloss measurement purposes, without in any way interfering with the actual color measurement. The available spectrally resolved gloss values ​​allow all the freedom for further computational processing, i.e. the calculation of standard-compliant (v-lambda weighted) gloss values ​​or the output of other color-dependent (user-defined) gloss values. In particular, in the case of automotive lacquers with a base coat (possibly with effect pigments) and a clear coat finish, both the influence of the gloss level of the base coat on the color measurement of the base coat and the influence of the color of the base coat on the gloss measurement of the clear coat can be metrically separated.

[0077] Here, it can be seen in particular that a number of lenses 22 are also incorporated in the apparatus. These lenses are arranged at least partially in front of the radiation or illumination devices 2, 6 and 8.

[0078] A radiation channel 24 is disposed between these lenses 22 and a radiation device (only one of which is designated).

[0079] In order to collimate the beam path, an aperture is preferably arranged between the second radiation and / or illumination device 12 and the surface 10 (i.e. in the beam path between the radiation and / or illumination device 12 and the surface 10). Preferably, the second illumination device is arranged in the beam trap 13. Reference number 34 denotes a further aperture.

[0080] The applicant reserves the right to claim all features disclosed in the application as essential to the invention, provided that they, individually or in combination, are new compared to the prior art. It should also be noted that the individual figures also describe features that may be advantageous in themselves. Those skilled in the art will immediately recognize that a particular feature described in a figure may be advantageous without adopting further features from this figure. Moreover, those skilled in the art will recognize that advantages may result from a combination of several features shown in the individual figures or in different figures.

Claims

1. An apparatus (1) for investigating the surface properties of lacquered surfaces, comprising: a first illumination device (2) for illuminating a surface (10) to be investigated at a first illumination angle (a1), a second illumination device (12) for illuminating said surface (10) at a second illumination angle (a2), and a first sensor device (4) for detecting radiation reflected and / or scattered by said surface illuminated by said second illumination device (2) at a first recording angle (b2), The apparatus (1) comprises a radiation analysis device (4) for analyzing the radiation scattered and / or reflected by the surface in terms of its wavelength.

2. The apparatus (1) according to claim 1, wherein the radiation analysis device (14) comprises a spectrometer (14).

3. 2. The apparatus (1) according to claim 1, wherein the radiation analysis device (14) is arranged to record the radiation irradiated onto the surface (10) by at least one of the illumination devices and scattered and / or reflected by the surface.

4. The apparatus (1) according to any one of claims 1 to 3, wherein the radiation analysis device is also a component of the sensor device (4).

5. The apparatus (1) according to any one of claims 1 to 3, wherein the apparatus (1) comprises an integrating device for integrating the signal output by the radiation analysis device.

6. 4. The apparatus (1) according to any one of claims 1 to 3, wherein the apparatus (1) comprises a third lighting device (6) arranged at a third lighting angle (a3) relative to the surface.

7. 4. The device (1) according to any one of claims 1 to 3, wherein at least one illumination angle is between 30° and 60°, preferably between 35° and 55°, preferably between 40° and 50°, particularly preferably 45°, and / or at least one illumination angle is greater than 60°, preferably greater than 65°, preferably greater than 70°, preferably greater than 75°, particularly preferably greater than 80°.

8. 4. The apparatus (1) according to any one of claims 1 to 3, wherein the radiation analysis device is suitable and adapted to analyze radiation irradiated onto the surface by the first illumination device and / or the third illumination device and scattered by the surface in terms of its wavelength.

9. 4. The apparatus (1) according to any one of claims 1 to 3, wherein the apparatus (1) comprises a fourth lighting device (16) arranged at a fourth lighting angle (a4) relative to the surface.

10. 4. Apparatus (1) according to any one of claims 1 to 3, wherein at least one lighting device is suitable and adapted to illuminate radiation of different wavelengths onto said surface.

11. A method for investigating surface properties of a lacquered surface, comprising: a first illumination device (2) illuminating a surface (10) to be investigated at a first illumination angle (a1), a second illumination device (12) illuminating said surface (10) at a second illumination angle (a2), a first sensor device (4) recording radiation reflected and / or scattered by said surface illuminated by said second illumination device (2) at a first recording angle and outputting at least one value characteristic of said radiation reaching said sensor device (4) from said surface, A method wherein a radiation analysis device analyzes the radiation scattered and / or reflected by said surface for its wavelength.

12. The method of claim 11 , wherein both the values determined by the sensor device and the data recorded by the radiation analysis device are taken into account for the assessment of the surface properties.

13. 12. The method of claim 11, wherein an illumination device (2, 12) emits radiation onto the surface, and the radiation analysis device records the radiation emitted by the illumination device and reflected by the surface.

14. 14. The method of any one of claims 11 to 13, wherein the radiation analysis device analyzes radiation by means of a spectrometer.

15. 14. The method of claim 11, wherein a third lighting device illuminates the surface at a third angle.

Images