Measuring apparatus and method for measurement

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 light source, a first diffusion plate, and a second diffusion plate, the light source being arranged in a plurality along a predetermined arrangement direction. When the diffusion angle of the first diffusion plate in the arrangement direction is defined as Ax and the diffusion angle of the second diffusion plate in the arrangement direction is defined as Bx, the relationship of Ax≤Bx is satisfied.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] As an example of a measurement object, an inspection device that inspects defects in the painted surface of a car body is known. For example, Patent Document 1 discloses an inspection device that uses a three-dimensional shape measurement method in which a pattern light created by synthesizing data on a plurality of sinusoidal slit patterns having different frequency components and color components is projected onto an object to obtain an image. Summary of the Invention [Problem to be solved by the invention]

[0003] However, there is a problem in that it is difficult to perform high-precision measurements on the painted surface of a vehicle body, for example, as a measurement object.

[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 includes 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 light source, a first diffuser, and a second diffuser, and the light sources are arranged in a predetermined arrangement direction, and when the diffusion angle of the first diffuser in the arrangement direction is Ax and the diffusion angle of the second diffuser in the arrangement direction is Bx, the relationship Ax≦Bx is satisfied. [Effects of the Invention]

[0006] According to the present invention, a measuring device capable of performing highly accurate measurements can be provided. [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] 1 is a diagram showing an overview of an optical unit of a measurement device according to an embodiment of the present invention. [Figure 3] 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 4] FIG. 10 is an optical layout diagram of a measurement device according to a comparative example. [Figure 5] 1 is an optical layout diagram of a measurement device according to an embodiment of the present invention. [Figure 6] FIG. 10 is a diagram showing an arrangement of point light sources in another example of a measurement device according to an embodiment of the present invention. [Figure 7] 5A and 5B are diagrams for explaining an illumination pattern formed on a second diffuser plate in the measurement device according to one embodiment of the present invention. [Figure 8] 5 is a diagram for explaining the relationship between a first diffusing plate and a second diffusing plate in the measurement device according to one embodiment of the present invention. FIG. [Figure 9] 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 10] 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 11] 1 is a flowchart illustrating a measurement method according to an embodiment of the present invention. [Figure 12] 5 is a flowchart for explaining a defect detection process performed by a defect detection unit of an information processing apparatus 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] [Embodiment] <Configuration of Measuring Device 1> An example of the configuration of a measuring device 1 according to one embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a configuration diagram of the measuring device 1 according to one embodiment of the present invention. The measuring device 1 measures a measurement object 2 being transported in a transport direction. By measuring the measurement object 2 with the measuring device 1, the state of the measurement object 2 may be represented by one or more characteristic values ​​based on an image of the measurement object 2. The measurement object 2 is transported by a transport unit 3. The measurement object 2 is, for example, a painted vehicle body such as a large automobile, a standard automobile, or a compact automobile. 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 measurement 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 measuring device 1 also includes an illumination unit 11 and a light receiving unit 12. Hereinafter, the components 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] 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 surface 2P of the measurement object 2, and receive and measure the reflected light from the measurement object 2 at predetermined time intervals or in response to an external trigger signal. The direction of illumination from the light source 13 and the direction of the optical axis of the light receiving unit 12 are arranged so as to cause specular reflection from the surface 2P.

[0014] In the measurement object 2, an area to be measured by the measurement device 1 is set in advance. Note that it is not necessary that the entire surface 2P of the measurement object 2 is the measurement area. For example, if the measurement object 2 is a car body, areas with large curves such as door handles and areas near the edges of the car body are generally excluded from the measurement area. Therefore, the illumination unit 11 and the light receiving unit 12 may be arranged according to a measurement area set in advance as an area that can be measured.

[0015] When the light receiving unit 12 is an imaging device, it generates image information of the measurement object 2. The image information may be, for example, a two-dimensional color image. The light receiving unit 12 may be a visible light camera such as an area camera.

[0016] The surface 2P of the measurement object 2 may be a glossy, smooth surface. The light incident on the surface 2P 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.

[0017] The measuring device 1 further 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 measures the state of the measurement object 2 and detects defects based on the specularly reflected light from the measurement object 2 received by the light receiving unit 12.

[0018] The result output unit 30 outputs the characteristic values ​​and defect-related information at each measurement position on the measurement object 2 to a monitor, a printer, or in the form of electronic data.

[0019] 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.

[0020] When the measurement object 2 is a painted car body, the measuring device 1 measures the presence or absence of defects on the surface 2P of the painted surface of the car body, such as the doors, hood, roof, trunk lid, and rear bumper. Here, defects on the surface 2P 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.

[0021] 1, the measuring device 1 is placed on only one side of the transport section 3, but this is not limiting and the measuring devices 1 may be placed on both sides of the transport section 3. When the measuring devices 1 are placed on both sides of the transport section 3, they may be placed facing each other with the measurement object 2 in between, or may be placed offset from each other in the transport direction.

[0022] FIG. 3 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. 3, (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.

[0023] <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. 4 is an optical layout diagram of a measuring device 9 according to a comparative example.

[0024] 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 multiple linear light sources 93. The linear light sources 93 are arranged in a repeating order of red, green, and blue linear light sources. The illumination pattern formed on the illuminated measurement object 2 is a striped pattern combining light and dark patterns in which the light brightness varies sinusoidally for each wavelength in the arrangement direction of the linear light sources 93. The light receiving unit 92 is composed of multiple area cameras and receives specularly reflected light from the illuminated measurement object 2. A diffuser 94 is arranged between the linear light source 93 and the measurement object 2.

[0025] Fig. 4(a) shows a measuring device 9 in which the illumination direction from a linear light source 93 and the optical axis direction of a light receiving unit 92 are arranged so as to cause specular reflection with respect to a surface 2P. Fig. 4(b) shows a measuring device 9 in which the surface 2P is tilted with respect to Fig. 4(a). Although the position of the linear light source 93 required for measuring specular reflection light is shifted in the arrangement direction, measurement is still possible.

[0026] Figure 4(c) shows a measuring device 9 in which the number of linear light sources 93 is reduced compared to Figures 4(a) and (b). Figure 4(c) also shows a measuring device 9 in the case where the surface 2P is tilted, similar to Figure 4(b). In the case of Figure 4(c), the linear light source 93 is not present in the position required for measurement, so the light receiving unit 92 cannot receive specularly reflected light from the measurement object 2.

[0027] The surface 2P includes a plurality of regions with different surface normal directions and different 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, in contrast to when the surface 2P of the measurement object 2 is not tilted, there are no linear light sources 93 at positions required for measurement, so it is necessary to increase the number of linear light sources 93 that illuminate the measurement object 2.

[0028] 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.

[0029] <Optical Arrangement of Measuring Device 1 According to the Embodiment> FIG. 5 is an optical layout diagram of a measurement device 1 according to one embodiment of the present invention. In FIG. 5, (a) is a plan view, (b) is a front view, and (c) is a diagram showing details of the light source 13. FIG. 5 shows the arrangement direction Fa and the orthogonal direction Fb. FIG. 5(a) also shows distances L1 and L2. Distance L1 indicates the distance between the first diffuser plate 14 and the second diffuser plate 15, and distance L2 indicates the distance between the second diffuser plate 15 and the measurement object 2. Furthermore, arrangement direction Fa indicates the arrangement direction in which light sources 13B, 13G, and 13R are arranged. Orthogonal direction Fb indicates the orthogonal direction orthogonal to arrangement direction Fa. Components that are the same as those already described are assigned the same reference numerals, and redundant description will be omitted.

[0030] As shown in FIG. 5(a), the measurement device 1 includes an illumination unit 11 and a light receiving unit 12. The illumination unit 11 includes a light source 13, a first diffuser 14, and a second diffuser 15. The light source 13 includes a plurality of light sources 13B, 13G, and 13R. The light sources 13B, 13G, and 13R each emit light of a different wavelength. For example, the light sources 13B, 13G, and 13R may emit light in blue, green, and red, respectively. The light sources 13B, 13G, and 13R are arranged along an arrangement direction Fa. The arrangement direction Fa has a predetermined angle with respect to the surface 2P of the measurement object 2. 5(b) shows the light receiving unit 12 and the light source 13 relative to the surface 2P of the measurement object 2. The light source 13 has a directionality that is elongated in the orthogonal direction Fb. A plurality of light receiving units 12 are provided in the orthogonal direction Fb.

[0031] Furthermore, in the light source 13, point light sources 13a emitting light of the same wavelength are arranged in the orthogonal direction Fb, so that linear light sources emitting light of different wavelengths may be arranged in a predetermined order in the arrangement direction Fa.

[0032] As shown in Fig. 5(c), light source 13 includes light sources 13B, 13G, and 13R. Each of light sources 13B, 13G, and 13R includes a plurality of point light sources 13b, a plurality of point light sources 13g, and a plurality of point light sources 13r arranged in orthogonal direction Fb. In Fig. 5, the light sources are arranged in the predetermined order of blue, green, and red, but the order may be different from this order, or may include colors other than blue, green, and red.

[0033] Red, green, and blue are the minimum colors required for the phase shift calculation performed during defect detection, and are the three primary colors of visible light, making them versatile.

[0034] 5(c), the blue point light sources 13b, the green point light sources 13g, and the red point light sources 13r are each arranged in two rows in the orthogonal direction Fb, but this is not limited to two rows, and they may be arranged in multiple rows such as one row or three rows. The blue point light sources 13b, the green point light sources 13g, and the red point light sources 13r are arranged in the orthogonal direction Fb at a pitch of, for example, several mm to several tens of mm. With this arrangement, the light source 13 is used as including linear light sources of multiple colors.

[0035] The numbers of blue point light sources 13b, green point light sources 13g, and red point light sources 13r do not necessarily have to be the same, and can be changed depending on the light emission luminance, the spectral sensitivity of the light receiving section 12, and the like.

[0036] Furthermore, the point light source 13a may include a lens member that guides the optical path of the emitted light to the measurement object 2. The lens member is provided, for example, on the chip of each point light source 13a. By providing the lens member, the divergence angle of the light emitted by the point light source 13a can be reduced, thereby increasing the directivity. Therefore, a high-output illumination pattern can be formed on the second diffuser 15. Furthermore, in forming a sinusoidal illumination pattern in the array direction Fa and a uniform illumination pattern in the orthogonal direction Fb, the degree of freedom in the divergence angle of the light emitted by the point light source 13a increases.

[0037] The point light source 13a may be an LED (Light Emitting Diode) element, an organic EL (Electro Luminescence) element, or a laser element. Furthermore, in order to form an illumination pattern with even higher brightness on the second diffuser plate 15, an optical element may be additionally provided in the illumination unit 11. For example, an optical element may be inserted between the point light source 13a and the first diffuser plate 14, or an optical element may be inserted in another region.

[0038] The first diffusing plate 14 is disposed between the light source 13 and the measurement object 2, and diffuses the light from the light source 13. The second diffusing plate 15 is disposed between the first diffusing plate 14 and the measurement object 2, and diffuses the light from the light source 13. An illumination pattern of light that illuminates the measurement object 2 is formed on the second diffusing plate 15. The formed illumination pattern can be used as a secondary light source for the measurement object 2.

[0039] The light source 13, the first diffuser plate 14, and the second diffuser plate 15 are arranged parallel to one another. That is, the arrangement direction Fa of the plurality of light sources 13B, 13G, and 13R is arranged parallel to the first diffuser plate 14 and the second diffuser plate 15. Furthermore, the lengths of the arrangement direction Fa of the first diffuser plate 14 and the second diffuser plate 15 are preferably equal to one another and are preferably longer than the length of the light source 13.

[0040] Fig. 6 is a diagram showing details of point light sources 13b, 13g, and 13r in another example of the measuring device 1 according to one embodiment of the present invention. In Fig. 6, the same components as those shown in Fig. 5 are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0041] In FIG. 6, unlike FIG. 5(c), the plurality of blue point light sources 13b, the plurality of green point light sources 13g, and the plurality of red point light sources 13r are arranged in a staggered pattern with respect to the orthogonal direction Fb.

[0042] Fig. 7 is a diagram for explaining the illumination pattern formed on the second diffuser plate 15 in the measurement device 1 according to one embodiment of the present invention. In Fig. 7, (a) shows the arrangement of the light sources 13, (b) shows the distribution of light luminance in the arrangement direction Fa, (c) shows the distribution of light luminance in the perpendicular direction Fb, and (d) shows the illumination pattern formed on the second diffuser plate 15. Components that are the same as those already described are given the same reference numerals, and redundant description will be omitted.

[0043] 7(a), the light sources 13 are arranged in the arrangement direction Fa in the order of light source 13R, light source 13G, and light source 13B. Light source 13R includes a plurality of point light sources 13r, light source 13G includes a plurality of point light sources 13g, and light source 13B includes a plurality of point light sources 13b.

[0044] 7(b) shows the luminances Iar, Iag, and Iab. The luminances Iar, Iag, and Iab respectively represent the luminance of the red light from light source 13R, the green light from light source 13G, and the blue light from light source 13B in the arrangement direction Fa. In order to calculate phase information by performing a phase shift calculation during defect detection, it is preferable that the distribution of the luminance of each light be sinusoidal, but a distribution close to a sine wave is also acceptable.

[0045] 7(c) shows the luminances Ibr, Ibg, and Ibb. Luminances Iar, Iag, and Iab respectively represent the luminance of the red light from light source 13R, the green light from light source 13G, and the blue light from light source 13B in the orthogonal direction Fb. In order to use light source 13 as a linear light source, it is preferable that the luminance distribution of each light be uniform.

[0046] 7(d) shows the luminance distribution for each of the red, green, and blue colors as an illumination pattern formed on the second diffuser 15. The sine waves in the arrangement direction Fa corresponding to the red, green, and blue colors overlap with a phase shift of 2π / 3 (rad). In order to calculate accurate phase information by the phase shift calculation performed during defect detection, it is preferable that the illumination pattern be a stripe pattern that combines light and dark patterns in which the luminance of light varies sinusoidally for each wavelength in the arrangement direction Fa.

[0047] 8 is a diagram illustrating the relationship between the first diffusing plate 14 and the second diffusing plate 15 in the measuring device 1 according to one embodiment of the present invention. In the diagram, θ is the angle of the surface 2P of the measurement object 2 with respect to the transport direction. θmax is the maximum value of the angle θ of the surface 2P at which the light receiving unit 12 can receive specularly reflected light from the measurement object 2.

[0048] Let the diffusion angle in the array direction Fa of the first diffusion plate 14 be Ax, and the diffusion angle in the orthogonal direction Fb be Ay. Let the diffusion angle in the array direction Fa of the second diffusion plate 15 be Bx, and the diffusion angle in the orthogonal direction Fb be By. α represents the angle between the optical axis and the light beam in the first diffusion plate 14, and β represents the angle between the optical axis and the light beam in the second diffusion plate 15. The angles α and β satisfy the relationships α≦Ax and β≦Bx, respectively.

[0049] In order for the light receiving part 12 to receive the specularly reflected light from the measurement object 2 illuminated by the light source 13, it is necessary for the diffusion angle Bx and the angle θmax of the second diffusion plate 15 to satisfy the relationship Bx≧2θmax. Also, in order to increase the illuminance of the surface 2P, it is preferable to set Bx = 2θmax. Note that θmax is, for example, about 15 to 25 degrees and depends on the type of the measurement object 2.

[0050] When a plurality of point light sources 13a are arranged in the orthogonal direction Fb, in order to remove ripples and uniformize the luminance, it is necessary to increase the diffusion angle Ay in the orthogonal direction Fb of the first diffusion plate 14.

[0051] Also, when a plurality of point light sources 13a are arranged in the array direction Fa, in order to make the luminance sinusoidal, the light emitted from the point light sources 13a is diffused to such an extent that the luminance does not become uniform. Therefore, it is preferable that the diffusion angle Ax in the array direction Fa of the first diffusion plate 14 is smaller than Ay.

[0052] That is, in the first diffusion plate 14, it is preferable that the diffusion angle Ax in the array direction Fa and the diffusion angle Ay in the orthogonal direction Fb satisfy the relationship Ax < Ay.

[0053] The relationship between the diffusion angles in the array direction Fa and the orthogonal direction Fb of the second diffusion plate 15 will be described. In order to widen the measurable range in the measurement object 2, it is preferable that the diffusion angle Bx in the array direction Fa of the second diffusion plate 15 is large. Also, in order to illuminate the measurement object 2 with higher luminance, it is preferable that the diffusion angle By in the orthogonal direction Fb of the second diffusion plate 15 is small.

[0054] That is, in the second diffusing plate 15, the diffusion angle Bx in the arrangement direction Fa and the diffusion angle By in the perpendicular direction Fb preferably satisfy the relationship Bx>By.

[0055] The first diffuser 14 is an optically anisotropic diffuser having a diffusion angle Ax in the arrangement direction Fa and a diffusion angle Ay in the perpendicular direction Fb that are different from each other. The second diffuser 15 may be optically isotropic or anisotropic, but an optically isotropic diffuser is easier to process.

[0056] Because the angle θ takes a different value depending on the position of the measurement object 2, it is preferable to widen the measurable range and to increase the brightness of the light illuminating the measurement object 2. In order to widen the measurable range, it is preferable that the diffusion angle Bx in the arrangement direction Fa of the second diffuser plate 15 is large. Furthermore, in order to increase the brightness of the light irradiating the measurement object 2, it is preferable that the diffusion angle Ax in the arrangement direction Fa of the first diffuser plate 14 is small. Due to these conditions, it is preferable that the diffusion angles Ax and Bx satisfy the relationship Ax≦Bx.

[0057] On the other hand, in order to widen the measurable range, it is preferable that the diffusion angle Bx in the orthogonal direction of the second diffusing plate 15 is small. Also, in order to increase the brightness of the light illuminating the measurement object 2, it is preferable that the diffusion angle By in the orthogonal direction Fb of the second diffusing plate 15 is small.

[0058] For the above reasons, it is preferable that the diffusion angles Ax, Ay of the first diffuser 14 and the diffusion angles Bx, By of the second diffuser 15 respectively satisfy the relationships Ax≦Bx and Ay≧By. By satisfying these relationships, the first diffuser 14 and the second diffuser 15 can share the function of widening the measurable range of the measurement object 2 in the arrangement direction Fa and the perpendicular direction Fb, and illuminating the measurement object 2 with high brightness.

[0059] When the angle of the surface 2P of the measurement object 2 with respect to the conveyance direction is θ, the condition under which specularly reflected light from the measurement object 2 can be received is given by the following formula (1). L1×α ≒ L2×β (1)

[0060] Since formula (1) can also be expressed as α / β≈L2 / L1, and considering the condition Ax≦Bx, it is preferable that α≦β, and therefore it is preferable to satisfy the following formula (2): By satisfying formula (2), the luminance distribution of the illumination pattern formed on the second diffuser plate 15 in the orthogonal direction Fb can be made uniform. L1>L2 (2)

[0061] Although the light beam emitted from the light source 13 is diffused in an angular direction wider than the full angle at half maximum, the radiation intensity is small. Therefore, the diffusion angle Ax of the first diffuser 14 and the diffusion angle Bx of the second diffuser 15 are defined as the full angle at half maximum, i.e., the full angle at half maximum, at which the radiation intensity is half the peak radiation intensity. By defining the diffusion angles Ax and Bx in this way, it is possible to ensure that the radiation intensity received by the light receiving unit 12 is sufficient to not affect defect detection by the defect detection unit 24.

[0062] <Hardware configuration of the control unit 20> 9 is a block diagram showing the hardware configuration of the control unit 20 of the measurement 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.

[0063] 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.

[0064] 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).

[0065] 10 is a block diagram showing the functional 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 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.

[0066] The defect detection unit 24 detects defects by measuring the measurement object 2 based on the specularly reflected light from the measurement object 2 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 measures the measurement object 2 in accordance with the calculated characteristic values.

[0067] 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, and calculates phase information based on the luminance distribution of the light contained in the image information. The defect detection unit 24 calculates characteristic values ​​based on at least the phase information, and detects defects by measuring the measurement object 2 according to the characteristic values. The defect detection unit 24 may also calculate one or more characteristic values ​​based on a predetermined algorithm. The defect detection unit 24 may calculate the characteristic values ​​based on luminance information, phase information, color information, or a combination of these pieces of information. The characteristic values ​​may be, for example, the magnitude of the peak value of the signal level in a region that is a defect candidate, the amount of change in the signal slope, or the area of ​​the region.

[0068] The defect detection unit 24 detects defects based on the calculated characteristic values ​​and defect judgment criteria. The defect detection unit 24 also detects defects using a defect inspection algorithm based on the characteristic values, the state of the measurement object 2, and inspection criteria set for each of various defect types.

[0069] <Measurement method> 11 is a flowchart illustrating a measurement method according to one embodiment of the present invention. The measurement method is performed in a measurement device 1.

[0070] First, the illumination unit 11 of the measurement device 1 illuminates the measurement object 2 (step S101). Subsequently, 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 (step S102).

[0071] 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 (step S103). If there are multiple light receiving units 12, image information of multiple regions of the measurement object 2 may be generated.

[0072] The defect detection unit 24 calculates the characteristic values ​​based on the generated image information (step S104), and detects defects in the measurement object 2 according to the calculated characteristic values ​​(step S105).

[0073] 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.

[0074] <Processing Performed by Defect Detection Unit 24> 12 is a flowchart for explaining the defect detection process performed by the defect detection unit 24 of the measurement device 1 according to one embodiment of the present invention. Here, it is assumed that the light source 13 uses three colors: red, green, and blue.

[0075] The processing performed by the defect detection unit 24 can be roughly divided into two: pre-processing for emphasizing defects in the measurement object 2, and post-processing for detecting defects based on the image obtained in the pre-processing. In Fig. 12, the pre-processing indicates steps S201 to S205, and the post-processing indicates steps S206 to S207.

[0076] First, the light receiving unit 12 receives specularly reflected light from the measurement object 2 and acquires image information (step S201). This image information is used for defect detection in the defect detection unit 24. At this time, the light receiving unit 12 may store the acquired image information in the HDD 104 of the measuring device 1 or the like.

[0077] Next, the defect detection unit 24 separates the image information of the measurement object 2 acquired in step S201 into RGB colors (step S202). Specifically, an R signal indicating red, a G signal indicating green, and a B signal indicating blue are extracted from the image information. Since the spectral sensitivity curves of the light receiving unit 12 generally have overlap between the R signal, the G signal, and the B signal, crosstalk is included in the simply separated signals for each color. The defect detection unit 24 performs a correction process called crosstalk correction to extract the R signal, the G signal, and the B signal that do not include crosstalk.

[0078] The defect detection unit 24 calculates phase information based on the image information acquired in step S201 (step S203). Specifically, smoothing processing is performed on each of the RGB color signals decomposed in step S202 based on the distribution of light luminance contained in the image information. A known averaging filter, a bilateral filter that preserves edges, or the like is used in the smoothing processing. The defect detection unit 24 then performs a phase shift calculation using each smoothed signal to calculate phase information. As a result, a two-dimensional phase image is acquired. In order for the defect detection unit 24 to perform a phase shift calculation and calculate phase information, it is preferable that the distribution of light luminance be sinusoidal, but it is sufficient if the distribution of light luminance is close to a sine wave.

[0079] Thereafter, the defect detection unit 24 performs edge extraction processing based on the phase information calculated in step S203 (step S204). Specifically, the edge extraction processing is performed on the two-dimensional phase image, and a known differential filter such as a Sobel filter, a Laplacian filter, and a second-order differential filter such as a LoG (Laplacian of Gaussian) filter is used.

[0080] The defect detection unit 24 performs pre-processing in steps S201 to S205 to create a two-dimensional defect-enhanced image in which defects in the measurement object 2 are emphasized. In the following post-processing, the defect detection unit 24 detects defects based on the defect-enhanced image. Note that the defect-enhanced image is an image based on phase information, and at least one characteristic value is an image based on the phase information.

[0081] First, the defect detection unit 24 extracts defect candidate areas from the two-dimensional defect-enhanced image (step S205). The extraction process combines binarization processing, contraction / expansion processing, and the like to extract defect candidate areas. At this time, defect candidate areas may be extracted by comparing with a defect-free area of ​​the measurement object 2 as a reference.

[0082] Next, the defect detection unit 24 calculates a characteristic value based on at least the phase information for a region of the measurement object 2 that is a defect candidate (step S206). The defect detection unit 24 may calculate one or more characteristic values ​​based on a predetermined algorithm. The defect detection unit 24 may calculate the characteristic value based on brightness information, phase information, color information, or a combination of these pieces of information. The characteristic value may be, for example, the magnitude of the signal level (e.g., peak value) of the defect candidate region, the amount of change in the signal (e.g., slope), or the area of ​​the region.

[0083] The defect detection unit 24 detects defects in the measurement object 2 according to the characteristic value calculated in step S206 (step S207). When detecting defects, the presence or absence of a defect may be determined by comparing the characteristic value with a defect determination criterion. The characteristic value can be calculated using the magnitude of the peak value or the like of the signal level of the region that is a defect candidate, the amount of change in the signal slope or the like, the area of ​​the region, etc.

[0084] The characteristic value is not limited to one, and the defect detection unit 24 can calculate a plurality of characteristic values ​​and check each characteristic value against the defect determination criteria to comprehensively detect defects.

[0085] The characteristic values ​​can also be calculated from the image information acquired by the light receiving unit 12, brightness based on the resolved RGB colors, etc., or can be calculated from a combination of this information with phase information. For example, the defect detection unit 24 may calculate a characteristic value based on phase information and a characteristic value based on brightness to detect defects. Note that, since there are many types of defects, it is preferable to have characteristic values ​​according to the characteristics of the defects.

[0086] <Action and effect> According to the measurement device 1 of this embodiment, a first diffuser 14 and a second diffuser 15 that diffuse the light beam in the arrangement direction Fa of the light sources 13 are arranged between the light sources 13 and the measurement object 2. With this configuration, even if the surface 2P is inclined, the light receiving unit 12 can easily receive the specularly reflected light from the measurement object 2.

[0087] More specifically, the measurable range can be widened by increasing the diffusion angle Bx in the arrangement direction Fa of the second diffuser 15, and the luminance of the light irradiated onto the measurement object 2 can be increased by decreasing the diffusion angle Ax in the arrangement direction Fa of the first diffuser 14. In other words, when the diffusion angles Ax and Bx satisfy the relationship Ax≦Bx, it becomes possible to measure the measurement object 2 even if the number of linear light sources included in the light source 13 is reduced.

[0088] 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.

[0089] For example, aspects of the present invention are as follows.

[0090] <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 light source, a first diffusion plate, and a second diffusion plate; The light sources are arranged in a plurality in a predetermined arrangement direction, When a diffusion angle of the first diffusion plate in the arrangement direction is Ax and a diffusion angle of the second diffusion plate in the arrangement direction is Bx, a relationship of Ax≦Bx is satisfied. Measuring equipment.

[0091] <2> The light source includes a plurality of point light sources. The aforementioned <1> The measuring device according to claim 1.

[0092] <3> The point light sources emit light of different wavelengths. The aforementioned <2> The measuring device according to claim 1.

[0093] <4> The first diffusion plate is disposed between the light source and the measurement object. The aforementioned <1> From the above <3> 10. The measuring device according to claim 9, wherein:

[0094] <5> the measurement device includes the second diffuser between the light source and the first diffuser, The aforementioned <1> From the above <4> 10. The measuring device according to claim 9, wherein:

[0095] <6> An illumination pattern of light that illuminates the measurement object is formed on the second diffusion plate. The aforementioned <1> From the above <5> 10. The measuring device according to claim 9, wherein:

[0096] <7> When the distance between the first diffusion plate and the second diffusion plate is L1 and the distance between the second diffusion plate and the measurement object is L2, the relationship of L1>L2 is satisfied. The aforementioned <1> From the above <6> The measuring device according to claim 1.

[0097] <8> When a diffusion angle of the first diffuser in an orthogonal direction orthogonal to the arrangement direction is defined as Ay and a diffusion angle of the second diffuser in the orthogonal direction is defined as By, a relationship of Ay≧By is satisfied. The aforementioned <1> From the above <7> 10. The measuring device according to claim 9, wherein:

[0098] <9> 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 <8> 10. The measuring device according to claim 9, wherein:

[0099] <10> The light sources include a plurality of point light sources that emit red light, a plurality of point light sources that emit green light, and a plurality of point light sources that emit blue light. The aforementioned <2> From the above <9> 10. The measuring device according to claim 9, wherein:

[0100] <11> The point light source includes a lens member that guides the optical path of the emitted light to the measurement object. The aforementioned <2> From the above <10> 10. The measuring device according to claim 9, wherein:

[0101] <12> The point light source is an LED element. The aforementioned <2> From the above <11> 10. The measuring device according to claim 9, wherein:

[0102] <13> the second diffuser plate is optically isotropic; The aforementioned <1> From the above <12> 10. The measuring device according to claim 9, wherein:

[0103] <14> The measurement object is a vehicle body. The aforementioned <1> From the above <13> 10. The measuring device according to claim 9, wherein:

[0104] <15> The aforementioned <1> From the above <14> A measurement method performed in the measurement device according to any one of the preceding claims, illuminating the object to be measured with light including a plurality of colors; receiving specularly reflected light from the illuminated measurement object; Measurement methods including: [Explanation of symbols]

[0105] 1. Measuring equipment 2. Measurement object 2P surface 3. Conveyor 11 Lighting Department 12 Light receiving section 13 Light source 13a Point light source 14 First diffuser 15 Second diffuser 24 Defect detection section Fa array direction Fb Orthogonal direction L1: Distance between the first and second diffusers L2: Distance between the second diffuser and the object to be measured [Prior art documents] [Patent documents]

[0106] [Patent Document 1] Japanese Patent Application Publication No. 9-21620

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 light source, a first diffusion plate, and a second diffusion plate; The light sources are arranged in a plurality in a predetermined arrangement direction, When a diffusion angle of the first diffuser in the arrangement direction is Ax and a diffusion angle of the second diffuser in the arrangement direction is Bx, a relationship of Ax≦Bx is satisfied. Measuring equipment.

2. The light source includes a plurality of point light sources. The measuring device according to claim 1 .

3. The point light sources emit light of different wavelengths. The measuring device according to claim 2 .

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

5. the measurement device includes the second diffuser between the light source and the first diffuser, The measuring device according to claim 1 .

6. an illumination pattern of light that illuminates the measurement object is formed on the second diffusion plate; The measuring device according to claim 1 .

7. When a distance between the first diffusion plate and the second diffusion plate is L1 and a distance between the second diffusion plate and the measurement object is L2, a relationship of L1>L2 is satisfied. The measuring device according to claim 1 .

8. a diffusion angle of the first diffuser in an orthogonal direction orthogonal to the arrangement direction is defined as Ay, and a diffusion angle of the second diffuser in the orthogonal direction is defined as By, satisfying a relationship of Ay≧By; The measuring device according to claim 1 .

9. 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 .

10. The light sources include a plurality of point light sources that emit red light, a plurality of point light sources that emit green light, and a plurality of point light sources that emit blue light. The measuring device according to claim 2 .

11. The point light source includes a lens member that guides the optical path of the emitted light to the measurement object. The measuring device according to claim 2 .

12. The point light source is an LED element. The measuring device according to claim 2 .

13. the second diffuser plate is optically isotropic; The measuring device according to claim 1 .

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

15. A measurement method performed in the measurement device according to claim 1, comprising: illuminating the object to be measured with light including a plurality of colors; receiving specularly reflected light from the illuminated measurement object; Measurement methods including:

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