Measuring apparatus and method for measuring state

Abstract

To provide a measuring apparatus capable of performing highly accurate measurement.SOLUTION: The measuring apparatus according to one aspect of the present invention is a measuring apparatus for measuring an object to be measured conveyed in a conveying direction, and includes: an illumination unit for illuminating the object to be measured and a light receiving unit for receiving specularly reflected light from the object to be measured illuminated by the illumination unit. The illumination unit includes a diffusion plate for diffusing a light flux from a light source. When the distance between the light source and the diffusion plate is defined as L1 and the distance between the diffusion plate and the object to be measured is defined as L2, the relationship of L1>L2 is satisfied.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a measurement device and a measurement method. [Background technology]

[0002] There is known an inspection device that inspects the paint surface of a vehicle body as an object to be measured for defects. For example, Patent Document 1 discloses an apparatus that detects defects by acquiring multiple images of a measurement portion of a workpiece while moving a light and dark pattern generated by an illumination device relative to the workpiece, which is the object to be detected for defects. Summary of the Invention [Problem to be solved by the invention]

[0003] However, the object being measured, such as the painted surface of a car body, contains multiple areas with different surface normal directions and curvatures, making it difficult to perform high-precision measurements.

[0004] SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a measuring device capable of performing highly accurate measurements. [Means for solving the problem]

[0005] A measuring device according to one aspect of the present invention is a measuring device that measures a measurement object being transported in a transport direction, and is equipped with an illumination unit that illuminates the measurement object, and a light receiving unit that receives specularly reflected light from the measurement object illuminated by the illumination unit, wherein the illumination unit includes a diffuser plate that diffuses a light beam from a light source, and when the distance between the light source and the diffuser plate is L1 and the distance between the diffuser plate and the measurement object is L2, the relationship L1 > L2 is satisfied. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a measuring device capable of performing highly accurate measurements. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a configuration diagram of a measurement device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing details of an optical unit of a measurement device according to an embodiment of the present invention. [Figure 3] 2 is a block diagram showing the hardware configuration of a control unit of a measurement device according to an embodiment of the present invention. FIG. [Figure 4] 2 is a block diagram showing the functional configuration of a control unit of a measurement device according to an embodiment of the present invention. FIG. [Figure 5] 1 is a diagram showing a relationship between an optical unit and a measurement object of a measurement device according to an embodiment of the present invention. [Figure 6] FIG. 10 is an optical layout diagram of a measurement device according to a comparative example. [Figure 7] 1 is an optical layout diagram of a measurement device according to an embodiment of the present invention. [Figure 8] FIG. 10 is a plan view of an optical arrangement of another example of a measurement apparatus according to an embodiment of the present invention. [Figure 9] 1 is a flowchart illustrating a measurement method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes the preferred embodiments of the present invention with reference to the accompanying drawings. In the drawings, the same components are designated by the same reference numerals, and redundant explanations may be omitted.

[0009] [First embodiment] <Configuration of Measuring Device 1> FIG. 1 is a configuration diagram of a measuring device 1 according to one embodiment of the present invention. The measuring device 1 measures a measuring object 2 being transported in a transport direction. By measuring the measuring object 2 with the measuring device 1, defects on a surface 2P of the measuring object 2 can be detected. The measuring object 2 is transported by a transport unit 3. The measuring object 2 is, for example, a painted vehicle body such as a large, standard, or compact vehicle. The vehicle body is, for example, a surface 2P of the vehicle body, and the surface 2P of the vehicle body may be painted. Note that the measuring object 2 may be an object other than a vehicle body, and the surface 2P may not be painted.

[0010] The measuring device 1 includes at least an optical unit 10. Details of the optical unit 10 will now be described with reference to FIG. 2. FIG. 2 is a diagram showing details of the optical unit 10 according to one embodiment of the present invention. The optical unit 10 also includes an illumination unit 11 and a light receiving unit 12. Hereinafter, the component including the illumination unit 11 and the light receiving unit 12 will be referred to as the "optical unit 10."

[0011] The optical unit 10 illuminates the measurement object 2 and receives specularly reflected light from the illuminated measurement object 2. The surface 2P is gently curved. Therefore, the surface 2P will be described as an imaginary plane that is parallel to the conveyance direction.

[0012] The illumination unit 11 illuminates the measurement object 2. The light receiving unit 12 receives specularly reflected light from the measurement object 2 illuminated by the illumination unit 11. An example of the light receiving unit 12 is an imaging device such as a camera equipped with an imaging element such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor).

[0013] If the light receiving unit 12 is an imaging device, it acquires image information of the measurement target 2. If the light receiving unit 12 is a visible light camera, it acquires color image information. The light receiving unit 12 may use an infrared camera or the like as an imaging device, or may acquire monochrome image information. The light receiving unit 12 may also be configured as an area camera equipped with an optical lens.

[0014] The surface 2P of the measurement object 2 may be a glossy, smooth surface. As a result, the light incident on the measurement object 2 from the illumination unit 11 is specularly reflected because the angle of incidence and the angle of reflection are equal. On the other hand, the surface 2P is a collection of multiple curved surface areas with different normal directions and curvatures.

[0015] Furthermore, the measuring device 1 includes a control unit 20, a result output unit 30, an encoder 21, a reader 22, and a position sensor 23. The control unit 20 controls the timing of the operation of the measuring device 1, etc. The control unit 20 is connected to the encoder 21, the reader 22, and the position sensor 23. The encoder 21 monitors the conveying state, such as the conveying speed, of the conveying unit 3. The reader 22 acquires information about the measurement object 2 (unique ID, model and color, etc.). The position sensor 23 acquires position information about the measurement object 2, such as information about the measurement object 2's approach to the measurement area or its presence or absence in the measurement area. The control unit 20 detects defects in the measurement object 2 based on the specularly reflected light from the measurement object 2 received by the light receiving unit 12.

[0016] The result output unit 30 outputs the characteristic values ​​at the measurement position of the measurement object 2, information about defects, etc., to a monitor, a printer, or in the form of electronic data, etc.

[0017] Based on the determined type of defect, the measuring device 1 can provide information that is useful for identifying the cause of the defect in the pre-process and for repairing the defect in the post-process.

[0018] When the measurement object 2 is a painted car body, the measuring device 1 measures the presence or absence of defects on the painted surfaces of the car body's doors, hood, roof, trunk lid, rear bumper, etc. Here, surface defects refer to, for example, scratches, cracks, irregularities, stains, discoloration, etc. formed on the painted surface. Paint defects include, for example, lumps, cissing, pinholes, orange peel, etc.

[0019] 1, the measuring device 1 is disposed on only one side of the transport section 3, but this is not limiting and the measuring devices 1 may be disposed on both sides of the transport section 3. When the measuring devices 1 are disposed on both sides of the transport section 3, they may be disposed facing each other with the measurement object 2 in between, or may be disposed offset from each other in the transport direction.

[0020] 3 is a block diagram showing the hardware configuration of the control unit 20 of the measuring device 1 according to one embodiment of the present invention. The control unit 20 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an HDD (Hard Disk Drive) 104, and an input / output I / F (Interface) 105. These components are electrically connected to one another via a bus 109.

[0021] The CPU 101 controls the operation of the control unit 20. The ROM 102 stores programs executed by the CPU 101. The RAM 103 is used as a work area for the CPU 101. The HDD 104 stores various data such as programs. The input / output I / F 105 is an interface for inputting and outputting various signals and data to and from external devices.

[0022] Some or all of the functions of the CPU 101 may be realized by an electronic circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0023] 4 is a block diagram showing details of the control unit 20 of the measuring device 1 according to one embodiment of the present invention. The control unit 20 includes a defect detection unit 24. The control unit 20 controls the timing of the operations of the illumination unit 11 and the light receiving unit 12, etc.

[0024] The defect detection unit 24 detects defects in the measurement object 2 based on the specularly reflected light received by the light receiving unit 12. More specifically, the defect detection unit 24 generates image information based on the specularly reflected light from the measurement object 2 received by the light receiving unit 12, calculates characteristic values ​​based on the generated image information, and detects defects in the measurement object 2 according to the calculated characteristic values. Even more specifically, the defect detection unit 24 calculates one or more characteristic values ​​based on the generated image using a predetermined algorithm. The characteristic values ​​are calculated based on brightness information, phase information, color information, and information combining these multiple pieces of information.

[0025] The defect detection unit 24 can evaluate whether the state of the surface 2P is good or not based on the calculated characteristic values ​​and the surface goodness algorithm. If the defect detection unit 24 detects a defect, it uses a defect inspection algorithm based on the characteristic values, the state of the measurement object 2, and inspection standards set for each of the various defect types.

[0026] FIG. 5 is a diagram showing the relationship between the optical unit 10 and the measurement object 2 of the measurement device 1 according to one embodiment of the present invention. In FIG. 5, (a) is a plan view, and (b) is a front view. The measurement object 2 is transported in the transport direction by the transport unit 3. The optical unit 10 is arranged in a gate shape so as to surround the transported measurement object 2. The measurement object 2 is transported inside the gate-shaped optical unit 10 at a constant speed and measured. When the measurement object 2 passes through the gate-shaped optical unit 10, the entire measurement object 2 is measured.

[0027] <Background of the study leading to the idea of ​​the measuring device 1 according to the embodiment> Here, the details of the investigations that led to the idea of ​​the measuring device 1 according to the embodiment will be described. Fig. 6 is an optical layout diagram of a measuring device 9 according to a comparative example.

[0028] The measuring device 9 according to the comparative example includes a light receiving unit 92 and an illumination unit 91. The illumination unit 91 illuminates the measurement object 2 with linear light. The light receiving unit 92 receives specularly reflected light from the measurement object 2 illuminated by the illumination unit 91. The illumination unit 91 also includes a plurality of light sources 93. The light sources 93 are a plurality of white directional light sources that form a periodic light and dark pattern. Therefore, a stripe pattern is formed on the illuminated measurement object 2. The light receiving unit 92 is composed of a plurality of area cameras and receives specularly reflected light from the illuminated measurement object 2.

[0029] 6(a) shows a measuring device 9 in which five light sources 93 are arranged at equal intervals in an illumination unit 91. The illumination direction from the light sources 93 and the optical axis direction of the light receiving unit 92 are arranged so as to cause specular reflection on the measurement object 2. In the figure, the hatched areas on both sides of each light source 93 indicate that there is no light source.

[0030] FIG. 6(b) shows the measurement device 9 when the surface 2P is tilted compared to FIG. 6(a). The position of the light source 93 required to measure the specularly reflected light is shifted in the array direction, but measurement is still possible. FIG. 6(c) shows the measurement device 9 in which the number of light sources 93 is reduced to one compared to FIGS. 6(a) and (b). FIG. 6(c) also shows the measurement device 9 when the surface 2P is tilted, similar to FIG. 6(b). In the case of FIG. 6(c), the light source 93 is not present in the position required for measurement, so the light receiving unit 92 cannot receive the specularly reflected light from the measurement object 2.

[0031] The surface 2P includes a plurality of regions with different normal directions and magnitudes of curvature depending on the position of the measurement object 2, such as when the surface 2P is tilted. When measuring the measurement object 2 in this way, it is necessary to increase the number of light sources 93 that illuminate the measurement object 2, since there are no light sources 93 at positions required for measurement when the surface 2P of the measurement object 2 is not tilted.

[0032] This led to the development of the measuring device 1 according to this embodiment. The optical arrangement of the measuring device 1 according to one embodiment of the present invention will now be described.

[0033] <Optical Arrangement of Measuring Device 1 According to the Embodiment> 7 is an optical layout diagram of a measurement device 1 according to one embodiment of the present invention. In FIG. 7, (a) is a plan view, and (b) is a front view. Components that are the same as those already described are given the same reference numerals, and duplicated explanations will be omitted.

[0034] As shown in FIG. 7(a), the measuring device 1 includes an illumination unit 11 and a light receiving unit 12, and the illumination unit 11 includes a light source 13 and a diffuser 14. The light source 13 illuminates a linear light onto the measurement object 2. In FIG. 7(a), the hatched areas on both sides of the light source 13 indicate that there is no light source. As shown in FIG. 7(b), the light source 13 is a directional light source that is elongated in the direction perpendicular to the paper surface, and multiple light receiving units 12 are provided in the direction perpendicular to the paper surface.

[0035] The light source 13 may be a single long light source, or may be a long light source formed by combining a plurality of short light sources. The illumination unit 11 may include one or more light sources 13.

[0036] Light source 13 may include one or more LED (Light Emitting Diode) elements, but is not limited to this and may also be a fluorescent lamp, a halogen lamp, etc. Light source 13 preferably emits visible light, but may also emit light in other wavelength bands such as infrared light.

[0037] The diffusion plate 14 diffuses the light beam from the light source. The diffusion plate 14 is disposed between the light source 13 and the measurement object 2, and diffuses the light beam in the arrangement direction F of the light source 13. The diffused light beam illuminates the measurement object 2.

[0038] The light receiving unit 12 receives specularly reflected light from the measurement object 2 illuminated by the illumination unit 11. The light receiving unit 12 may be focused on the measurement object 2 and receive reflected light from the measurement object 2 at predetermined time intervals or in response to an external trigger signal. The illumination direction from the light source 13 and the optical axis direction of the light receiving unit 12 are arranged so as to cause specular reflection from the measurement object 2.

[0039] In the measurement object 2, an area to be measured in advance by the measuring device 1 is set. Note that it is not necessary for all areas of the measurement object 2 to be the measurement area. For example, when the measurement object 2 is a vehicle body, it is common for parts with large curved surfaces such as doorknobs and the vicinity of the edge of the vehicle body to be excluded from the measurement area. Therefore, the illumination unit 11 and the light receiving unit 12 may be arranged according to a region that can be measured, which is set as the measurement region in advance.

[0040] Let the diffusion angle of the light source 13 in the plane parallel to the conveyance direction be A, and the diffusion angle of the diffusion plate 14 in the plane parallel to the conveyance direction be B. Although the light beam irradiated from the light source 13 is also diffused in an angular direction wider than the full angle at half maximum, its radiation intensity is small. Therefore, the diffusion angle A of the light source 13 and the diffusion angle B of the diffusion plate 14 use the full angle at half maximum and are defined as the full angle at which the radiation intensity becomes 1 / 2 with respect to the peak radiation intensity. By defining the diffusion angle A and the diffusion angle B in this way, it is possible to ensure a radiation intensity that does not affect the detection of defects by the light receiving unit 12 and the defect detection unit 24.

[0041] In Fig. 7(a), the angle α, the angle β, the angle θ, the distance L1, and the distance L2 are also shown. The angle α indicates the angle between the optical axis and the light beam in the first diffusion plate 14, and the angle β indicates the angle between the optical axis and the light beam in the second diffusion plate 15. The angle α and the angle β satisfy the relationships α≦A and β≦B, respectively. The angle θ is the angle of the surface 2P of the measurement object 2 with respect to the conveyance direction. When the angle of the surface 2P of the measurement object 2 with respect to the conveyance direction is θ, the light beam irradiated from the light source 13 at an angle α (α < A) and diffused from the diffusion plate 14 at an angle β (β < B) in the direction of the angle 2θ is received by the light receiving unit 12 through the specular reflection path.

[0042] Here, if θmax is the maximum value of the angle of the surface 2P of the measurement object 2 with respect to the conveyance direction in the measurement region, the diffusion angle B of the diffusion plate 14 and the angle θmax satisfy the relationship B≧2θmax. Note that θmax is, for example, about 15 to 25 degrees and depends on the type of the measurement object 2.

[0043] Distance L1 indicates the distance between light source 13 and diffuser plate 14. Distance L2 indicates the distance between diffuser plate 14 and measurement object 2. When the angle of surface 2P of measurement object 2 with respect to the conveying direction is θ, the condition under which specularly reflected light from measurement object 2 can be received is given by the following formula (1). L1×α ≒ L2×β (1)

[0044] Furthermore, the smaller the angle α, the higher the radiance that can be used to illuminate the measurement object 2. When the angle β is set based on the angle θmax, it is preferable that the relationship β>α is satisfied. Therefore, from equation (1), it is preferable that the relationship between the distance L1 and the distance L2 satisfy the following equation (2). L1>L2 (2)

[0045] Figure 8 is a plan view of another example of the optical arrangement of the measurement device 1 according to one embodiment of the present invention. In Figure 8, the same components as those shown in Figure 7 are given the same reference numerals, and duplicated explanations will be omitted. Unlike the case of Figure 7, two light sources 13a and 13b are provided.

[0046] 8, light source 13b has a smaller angle of incidence with respect to diffuser 14 than light source 13a. Therefore, light source 13b can illuminate measurement object 2 with higher radiance than light source 13a. Therefore, by providing two light sources 13, more accurate measurements are possible.

[0047] <Measurement method> 9 is a flowchart illustrating a measurement method according to one embodiment of the present invention. The measurement method is performed in the measurement device 1.

[0048] First, in step S11, the illumination unit 11 of the measurement device 1 illuminates the measurement target 2.

[0049] Subsequently, in step S12, the light receiving unit 12 of the measurement device 1 receives specularly reflected light from the measurement object 2 illuminated by the illumination unit 11.

[0050] Subsequently, in step S13, the defect detection unit 24 generates image information based on the specularly reflected light from the measurement object 2 received by the light receiving unit 12. If there are multiple light receiving units 12, image information of multiple regions of the measurement object 2 may be acquired.

[0051] Subsequently, in step S14, the defect detection unit 24 calculates characteristic values ​​based on the generated image information.

[0052] Subsequently, in step S15, the defect detection unit 24 detects defects in the measurement object 2 according to the calculated characteristic values.

[0053] The measurement method according to one embodiment of the present invention is carried out through these steps. However, the measurement method according to one embodiment of the present invention may include other steps as appropriate depending on the measurement conditions, measurement environment, etc.

[0054] <Action and effect> According to the measurement device 1 of this embodiment, a diffuser 14 that diffuses the light beam in the arrangement direction F of the light sources 13 is disposed between the light sources 13 and the measurement object 2. By disposing the diffuser 14, the light receiving unit 12 can more easily receive specularly reflected light from the measurement object 2 even if the surface 2P is inclined. This allows the number of light sources 13 to be reduced, and measurement of the measurement object 2 is possible even if the width of the light source in the arrangement direction is shortened. This therefore allows the number of light sources 13 used to irradiate the measurement object 2 to be reduced.

[0055] Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and various modifications and improvements are possible within the scope of the present invention.

[0056] For example, aspects of the present invention are as follows.

[0057] <1> A measuring device for measuring a measurement object conveyed in a conveying direction, an illumination unit that illuminates the measurement object; a light receiving unit that receives specularly reflected light from the object to be measured illuminated by the illumination unit; Equipped with the illumination unit includes a diffusion plate that diffuses a light beam from a light source, When the distance between the light source and the diffuser plate is L1 and the distance between the diffuser plate and the measurement object is L2, the relationship of L1>L2 is satisfied. Measuring device.

[0058] <2> The diffusion plate is disposed between the light source and the measurement object. The aforementioned <1> The measuring device according to claim 1.

[0059] <3> where B is the diffusion angle of the diffusion plate in a plane parallel to the transport direction, and θmax is the maximum angle of the surface of the object to be measured with respect to the transport direction, the relationship B≧2θmax is satisfied. The aforementioned <1> or the above <2> The measuring device according to claim 1.

[0060] <4> further comprising a defect detection unit that detects defects in the measurement object based on the specularly reflected light from the measurement object received by the light receiving unit; The aforementioned <1> From the above <3> 10. The measuring device according to claim 9, wherein:

[0061] <5> the defect detection unit generates image information based on the specularly reflected light from the measurement object received by the light receiving unit, calculates a characteristic value based on the generated image information, and detects defects in the measurement object according to the calculated characteristic value. The aforementioned <4> The measuring device according to claim 1.

[0062] <6> The illumination unit includes one of the light sources. The aforementioned <1> From the above <5> 10. The measuring device according to claim 9, wherein:

[0063] <7> The light source comprises a plurality of LED elements. The aforementioned <1> From the above <6> 10. The measuring device according to claim 9, wherein:

[0064] <8> The measurement object is a vehicle body. The aforementioned <1> From the above <7> 10. The measuring device according to claim 9, wherein:

[0065] <9> The aforementioned <1> From the above <8> A measurement method performed in the measurement device according to any one of the preceding claims, illuminating the measurement object; receiving specularly reflected light from the illuminated measurement object; Measurement methods including: [Explanation of symbols]

[0066] 1. Measuring equipment 2. Measurement object 2P surface 3. Conveyor 11 Lighting Department 12 Light receiving part 13 Light source 14 Diffuser 20 Control Unit 24 Defect detection section F Array direction L1 Distance between the light source and the diffuser L2: Distance between the diffuser and the object being measured [Prior art documents] [Patent documents]

[0067] [Patent Document 1] Patent Publication No. 2021-056182

Claims

1. A measuring device for measuring a measurement object conveyed in a conveying direction, an illumination unit that illuminates the measurement object; a light receiving unit that receives specularly reflected light from the object to be measured illuminated by the illumination unit; Equipped with the illumination unit includes a diffusion plate that diffuses a light beam from a light source, When the distance between the light source and the diffuser plate is L1 and the distance between the diffuser plate and the measurement object is L2, the relationship of L1>L2 is satisfied. Measuring equipment.

2. The diffusion plate is disposed between the light source and the measurement object. The measuring device according to claim 1 .

3. a diffusion angle of the diffusion plate in a plane parallel to the transport direction is B, and a maximum angle of the surface of the object to be measured with respect to the transport direction is θmax, the relationship B≧2θmax is satisfied; The measuring device according to claim 1 .

4. further comprising a defect detection unit that detects defects in the measurement object based on the specularly reflected light from the measurement object received by the light receiving unit; The measuring device according to claim 1 .

5. the defect detection unit generates image information based on the specularly reflected light from the measurement object received by the light receiving unit, calculates a characteristic value based on the generated image information, and detects defects in the measurement object according to the calculated characteristic value.

5. The measuring device according to claim 4.

6. The illumination unit includes one of the light sources. The measuring device according to claim 1 .

7. The light source includes a plurality of LED elements. The measuring device according to claim 1 .

8. The measurement object is a vehicle body. The measuring device according to claim 1 .

9. A measurement method performed in the measurement device according to claim 1, comprising: illuminating the measurement object; receiving specularly reflected light from the illuminated measurement object; Measurement methods including:

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