Measuring apparatus and method for measurement

Abstract

To provide a measuring apparatus capable of 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: a light source; a first diffusion plate; a second diffusion plate disposed between the first diffusion plate and the object to be measured; and a light shielding part disposed on the object-to-be-measured side of the second diffusion plate. The apparatus further 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 light shielding part includes an opening portion including the optical axis of light emitted from the light source in the second diffusion plate.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Inspection devices for inspecting defects in the painted surface of a vehicle body are known. For example, Patent Document 1 discloses an inspection device that uses a three-dimensional shape measurement method in which a pattern of 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] When inspecting defects in the painted surface of an object by illuminating the object with light containing multiple colors from multiple linear light sources in the array direction and receiving specularly reflected light from the illuminated object, it is difficult to maintain uniformity in the illumination pattern at both ends of the array direction, which causes variations in the measurement and makes it difficult to measure the object with high accuracy.

[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 a light source, a first diffuser, a second diffuser arranged between the first diffuser and the measurement object, and a shading unit arranged on the measurement object side of the second diffuser, 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, and the shading unit includes an opening portion in the second diffuser that includes the optical axis of the light emitted from the light source. [Effects of the Invention]

[0006] According to the present invention, highly accurate measurements are possible. [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] 1 is an optical layout diagram of a measurement device according to an embodiment of the present invention. [Figure 5] 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 6] 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 7] 10 is a diagram for explaining the width of an opening portion provided on the measurement object side of the second diffusing plate in the measurement device according to one embodiment of the present invention. FIG. [Figure 8] 10 is a diagram for explaining the width of an opening portion provided on the measurement object side of the 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 the state of a surface 2P of 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 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] 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 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 measuring device 1 is set in advance. It is not necessary that the entire measurement object 2 is the measurement area. For example, if the measurement object 2 is a car body, areas with large curved surfaces 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] <Optical Arrangement of Measuring Device 1 According to the Embodiment> FIG. 4 is an optical layout diagram of a measurement device 1 according to one embodiment of the present invention. In FIG. 4, (a) is a plan view, and (b) is a front view. Also, FIG. 4(c) is a diagram showing details of the light source 13. FIG. 4 shows an arrangement direction Fa and an orthogonal direction Fb. The arrangement direction Fa indicates the arrangement direction in which the linear light sources 13B, 13G, and 13R are arranged. The orthogonal direction Fb indicates an orthogonal direction perpendicular to the arrangement direction Fa. Also, w in the figure indicates the width of the opening portion 17. Components that are the same as those already described are assigned the same reference numerals, and duplicate explanations will be omitted.

[0024] As shown in FIG. 4(a), the measuring device 1 includes an illumination unit 11 and a light receiving unit 12. The illumination unit 11 includes a light source 13, a first diffusion plate 14, a second diffusion plate 15, and a light blocking unit 16. 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 is at a predetermined angle with respect to the horizontal direction of the surface of the vehicle body.

[0025] 4(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.

[0026] 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 13A emitting light of different wavelengths may be arranged in a predetermined order in the arrangement direction Fa.

[0027] As shown in the example of Fig. 4(c), light source 13 includes light sources 13B, 13G, and 13R. Each of light sources 13B, 13G, and 13R has a plurality of point light sources 13b, a plurality of point light sources 13g, and a plurality of point light sources 13r arranged in the orthogonal direction Fb. Light sources 13B, 13G, and 13R include red linear light source 13R, green linear light source 13G, and blue linear light source 13B. Red linear light source 13R is formed by arranging red point light sources 13r in a predetermined order in arrangement direction Fa and arranging red point light sources 13r in the orthogonal direction Fb.

[0028] Similarly, green linear light source 13G is formed by arranging green point light sources 13g in a predetermined order in arrangement direction Fa and arranging green point light sources 13g in the orthogonal direction Fb. Blue linear light source 13B is formed by arranging blue point light sources 13b in a predetermined order in arrangement direction Fa and arranging blue point light sources 13b in the orthogonal direction Fb.

[0029] As shown in the figure, one or more sets G of linear light sources each including one red linear light source 13R, one green linear light source 13G, and one blue linear light source 13B are arranged in a predetermined order in the arrangement direction, and three sets G of linear light sources are arranged in the example of Fig. 4. In the following, when there is no need to distinguish between the red linear light source 13R, the green linear light source 13G, and the blue linear light source 13B, they will be simply referred to as linear light source 13A.

[0030] In FIG. 4, the colors 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.

[0031] 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.

[0032] 4(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 such an arrangement, the light source 13 may be used as including linear light sources 13A of multiple colors.

[0033] 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.

[0034] 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 attached, for example, to the chip of each point light source 13a. By including 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.

[0035] 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 attached to 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.

[0036] The first diffuser 14 is attached between the light source 13 and the measurement object 2. The second diffuser 15 is attached between the first diffuser 14 and the measurement object 2. An illumination pattern of light that illuminates the measurement object 2 is formed on the second diffuser 15. The formed illumination pattern can be used as a secondary light source for the measurement object 2.

[0037] 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.

[0038] The light-shielding portion 16 is attached to the second diffusing plate 15 on the side of the object to be measured 2. It may be a member such as a black-painted metal plate, but is not limited to this, and various light-shielding members can be used. The light-shielding portion 16 includes an opening portion 17 in the second diffusing plate 15 that includes the optical axis of the light emitted from the light source 13. The light-shielding portion 16 is attached so as to limit the irradiation range of the light that reaches the object to be measured 2 by allowing only the opening portion 17 to pass the light emitted from the light source 13.

[0039] The illumination pattern formed by the second diffuser 15 passes through the opening 17 and illuminates the measurement object 2. Therefore, the non-uniform regions of the wavy pattern of the illumination light formed at both ends of the illumination light in the arrangement direction Fa are blocked by the light blocking portion 16. As a result, an illumination pattern is formed on the measurement object 2, which is a uniform stripe pattern that combines light and dark patterns in which the brightness of light changes sinusoidally in the arrangement direction Fa.

[0040] Furthermore, the light-shielding portion 16 may be formed integrally with the second diffusion plate 15. In this case, the light-shielding portion 16 may be formed by painting the second diffusion plate 15 with black ink. Alternatively, the light-shielding portion 16 may be formed by bonding and integrating a member such as a black-painted metal plate to the second diffusion plate 15. By forming the light-shielding portion 16 integrally with the second diffusion plate 15, the number of parts required during assembly can be reduced.

[0041] Fig. 5 is a diagram showing the arrangement 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. 5, the same components as those shown in Fig. 4 are denoted by the same reference numerals, and redundant explanations will be omitted.

[0042] 5 differs from FIG. 4(c) in that 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.

[0043] Fig. 6 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. 6, (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 explained are given the same reference numerals, and redundant explanations will be omitted.

[0044] 6(a), the light sources 13 are arranged in the arrangement direction Fa in the order of linear light source 13R, linear light source 13G, and linear light source 13B. The linear light source 13R includes a plurality of point light sources 13r, the linear light source 13G includes a plurality of point light sources 13g, and the linear light source 13B includes a plurality of point light sources 13b.

[0045] FIG. 6(b) shows the luminances Iar, Iag, and Iab. The luminances Iar, Iag, and Iab respectively indicate the luminances of the red, green, and blue lights of the linear light source 13R in the array direction Fa. In order to perform a phase shift operation executed during defect detection to calculate phase information, it is preferable that the distribution of the luminance of each light is sinusoidal, but a distribution close to a sine wave may also be acceptable.

[0046] FIG. 6(c) shows the luminances Ibr, Ibg, and Ibb. The luminances Iar, Iag, and Iab respectively indicate the luminances of the red, green, and blue lights of the linear light source 13R in the orthogonal direction Fb. In order to use the light source 13 as a plurality of linear light sources 13A, it is preferable that the distribution of the luminance of each light is uniform.

[0047] FIG. 6(d) shows the luminance distribution for each of red, green, and blue as an illumination pattern formed on the second diffusion plate 15. The sine waves in the array direction Fa corresponding to red, green, and blue are respectively shifted in phase by 2π / 3 (rad) and overlap. In order to accurately calculate phase information by the phase shift operation executed during defect detection, the illumination pattern is preferably a stripe pattern in which a light and dark pattern in which the luminance of light changes sinusoidally in the array direction Fa for each wavelength is combined.

[0048] Here, let Ax be the diffusion angle in the array direction Fa of the first diffusion plate 14, and Ay be the diffusion angle in the orthogonal direction Fb. When a plurality of point light sources 13a are arranged in the orthogonal direction Fb, in order to remove ripples and equalize the luminance, it is necessary to increase the diffusion angle Ay in the orthogonal direction Fb of the first diffusion plate 14. Further, 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 source 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. 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.

[0049] In order to form such an illumination pattern, it is preferable to appropriately set the distance L1, the distance L2, and the diffusion angle Ax of the first diffusing plate 14 in the arrangement direction Fa.

[0050] Here, if the distances L1 and L2 and the diffusion angle Ax of the first diffuser 14 in the arrangement direction Fa are set with priority so that the illumination pattern in the arrangement direction Fa becomes sinusoidal, the illumination pattern in the orthogonal direction Fb may become non-uniform. In this case, the illumination pattern in the orthogonal direction Fb can be made closer to uniformity by further increasing the diffusion angle Ay of the first diffuser 14 in the orthogonal direction Fb.

[0051] The first diffusing plate 14 is an anisotropic diffusing plate having a different diffusion angle Ax in the arrangement direction Fa and a different diffusion angle Ay in the perpendicular direction Fb, but the second diffusing plate 15 may be either isotropic or anisotropic.

[0052] 7 shows an arrangement for explaining the width w of the opening portion 17 provided on the measurement object side of the second diffuser, (b) shows the distribution of light luminance in the arrangement direction Fa in the case of (a), (c) shows an arrangement of light sources including seven linear light sources 13A, and (d) shows the distribution of light luminance in the arrangement direction Fa in the case of (c). Note that the arrangement of the colors of the linear light sources 13A shown in (a) and (c) is not limited to the order shown in the figures.

[0053] As shown in Fig. 7(a), when the light source 13 includes six linear light sources, the region R where all the sine waves of the luminance of each color are formed has a width of 1.33 periods of the sine wave. Here, the "width of one period" refers to the width of one period of the sine wave of the luminance of the light included in the illumination pattern formed on the measurement object 2, and means, for example, from the peak of the luminance of blue to the peak of the adjacent blue in Fig. 7(b).

[0054] Similarly, as shown in Figure 7(c), when the light source 13 includes seven linear light sources 13A, the region R where all the sine waves of the brightness of each color are formed has a width of 1.67 periods of the sine wave.

[0055] In order to reduce the measurement variation of the measurement object 2 and improve the measurement accuracy, it is preferable that the width w of the opening portion 17 does not include regions other than the region R where the sine waves of the luminance of each color are all formed. Therefore, when the width of one period of the sine wave of the luminance of the light included in the illumination pattern formed on the measurement object 2 is m, the number of linear light sources 13A included in the light source 13 is n, and the width of the opening portion 17 is w, the width w of the opening portion 17 satisfies the relationship of m < w ≤ (n - 2) / 3. However, m is a natural number, and n is a natural number of 3 or more.

[0056] For calculating the phase information performed by the defect detection unit 24, when k is a natural number, image information including sine waves for k periods is required. Therefore, it is preferable that the width w of the opening portion 17 provided on the measurement object 2 side of the second diffusion plate 15 is equal to or greater than the width for k periods and equal to or less than the width for {(n - 2) / 3} periods.

[0057] Specifically, when six linear light sources 13A are arranged in the light source 13 as shown in Fig. 7(a), the region R where the sine waves of the luminance of each color are all formed has a width corresponding to 1.33 periods when expressed in terms of the period of the sine wave. Therefore, it is preferable that the width w of the opening portion 17 is equal to or greater than the width for one period and equal to or less than the width for 1.33 periods. More preferably, when the width w of the opening portion 17 is equal to or greater than the width for 1.1 periods and equal to or less than the width for 1.2 periods, it is less affected by the installation error of the length corresponding to the width for 0.1 period in the opening portion 17.

[0058] Also, when seven linear light sources 13A are arranged in the light source 13 as shown in Fig. 7(c), the region R where the sine waves of the luminance of each color are all formed has a width corresponding to 1.67 periods when expressed in terms of the period of the sine wave. Therefore, it is preferable that the width w of the opening portion 17 is equal to or greater than the width corresponding to one period and equal to or less than the width for 1.67 periods. More preferably, when the width w of the opening portion 17 is equal to or greater than the width for 1.1 periods and equal to or less than the width for 1.5 periods, it is less affected by the installation error of the length corresponding to the width for 0.1 period in the opening portion 17.

[0059] Furthermore, for example, when arranging nine linear light sources 13A in the light source 13, the region R where the sine waves of the luminance of each color are all formed has a width corresponding to 2.33 periods when expressed in terms of the period of the sine wave. Therefore, the width w of the aperture portion 17 is preferably not less than the width corresponding to two periods and not more than the width corresponding to 2.33 periods. More preferably, when the width w of the aperture portion 17 is not less than the width corresponding to 2.1 periods and not more than the width corresponding to 2.2 periods, the aperture portion 17 is less affected by the installation error of the length corresponding to the width of 0.1 period.

[0060] Thus, assuming that the light source 13 includes n linear light sources 13A, it can be expressed as n = 3(m + 1) or n = 3(m + 1)+1. From this, taking the width of one period of the sine wave of the luminance of the light included in the illumination pattern formed on the measurement object 2 as m, the number of linear light sources 13A included in the light source 13 as n, and the width of the aperture portion 17 as w, when n = 3(m + 1) or n = 3(m + 1)+1, the width w of the aperture portion 17 satisfies the relationship m + 0.1 < w ≦ m + 0.2. However, m is a natural number and n is a natural number of 3 or more.

[0061] In addition, considering the cost aspect, since it is preferable that the number of linear light sources 13A included in the light source is small, for the calculation of the phase information performed by the defect detection unit 24, it is sufficient to have image information including a sine wave of one period. In this case, the number of linear light sources 13A is six. At this time, two sets of the linear light source groups G are arranged in the arrangement direction Fa.

[0062] Also, when not considering the installation error of the length corresponding to the width of 0.1 period in the aperture portion 17, the width w of the aperture portion 17 provided on the measurement object 2 side of the second diffuser plate 15 can be set to a width corresponding to exactly k periods. At this time, when the number of linear light sources 13A is set to n (= 3(m + 1)-1), m can be set to (n - 2) / 3.

[0063] That is, if the width of one period of the sine wave of the brightness of the light included in the illumination pattern formed on the measurement object 2 is m, the number of linear light sources 13A included in the light source 13 is n, the width of the opening portion 17 is w, and n = 3(m + 1) - 1, then the width w of the opening portion 17 satisfies the relationship w = m, where m is a natural number and n is a natural number of 3 or more.

[0064] Fig. 8 is a diagram illustrating the width w of the opening portion 17 provided on the measurement object side of the second diffuser. In Fig. 8, unlike Fig. 7, the light source 13 includes only one green linear light source 13G, and two red linear light sources 13R and two blue linear light sources 13B.

[0065] 8, when the light source 13 includes five linear light sources 13A, the region R where all the sine waves of the luminance of each color are formed corresponds to one sine wave period. Therefore, the width of the opening portion 17 corresponds to the width of one set G of linear light sources. Therefore, the minimum number of linear light sources 13A required for the defect detection unit 24 to calculate phase information is five.

[0066] <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.

[0067] 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.

[0068] 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).

[0069] 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.

[0070] The defect detection unit 24 detects defects by measuring the state of 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.

[0071] 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.

[0072] 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.

[0073] <Measurement method> 11 is a flowchart illustrating a measurement method according to one embodiment of the present invention. The measurement method uses a measurement device 1.

[0074] 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).

[0075] 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.

[0076] 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).

[0077] 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.

[0078] <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.

[0079] 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.

[0080] First, the light receiving unit 12 receives specularly reflected light from the measurement object 2 and acquires image information (step S201). At this time, the light receiving unit 12 may store the acquired image information in the HDD 104 of the measurement device 1 or the like.

[0081] 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.

[0082] 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.

[0083] Thereafter, the defect detection unit 24 performs edge extraction processing based on the phase image 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.

[0084] 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.

[0085] First, the defect detection unit 24 extracts defect candidate regions 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 regions. At this time, defect candidate regions may be extracted by comparing with a defect-free region of the measurement object 2 as a reference.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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 characteristic values ​​based on phase information and brightness to detect defects. Note that, since there are many types of defects, characteristic values ​​according to the characteristics of the defects are required.

[0090] <Action and effect> In the measuring device 1 according to this embodiment, a first diffusing plate 14 is attached between the light source 13 and the object to be measured 2, and a second diffusing plate 15 is attached between the first diffusing plate 14 and the object to be measured 2. A light-shielding portion 16 attached to the object to be measured 2 side of the second diffusing plate 15 allows only an opening portion 17 of the light irradiated from the light source 13 to pass through, thereby limiting the irradiation range of the light that reaches the object to be measured 2.

[0091] Therefore, the non-uniform areas of the wavy pattern of the illumination light formed at both ends of the illumination light in the arrangement direction Fa are blocked by the light blocking portion 16. As a result, an illumination pattern is formed on the measurement object 2, which is a uniform stripe pattern that combines light and dark patterns in which the brightness of light changes sinusoidally in the arrangement direction Fa.

[0092] As a result, the measuring device 1 according to this embodiment can reduce variations in measurement of the measurement target 2. Furthermore, the measuring device 1 can improve measurement accuracy.

[0093] 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.

[0094] For example, aspects of the present invention are as follows.

[0095] <1> A measuring device for measuring a measurement object conveyed in a conveying direction, an illumination unit that includes a light source, a first diffusion plate, a second diffusion plate that is disposed between the first diffusion plate and the measurement object, and a light blocking unit that is disposed on the measurement object side of the second diffusion plate, and 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 light-shielding portion includes an opening portion in the second diffusion plate that includes an optical axis of the light emitted from the light source. Measuring equipment.

[0096] <2> The light source includes a plurality of point light sources. The aforementioned <1> The measuring device according to claim 1.

[0097] <3> The point light sources emit light of different wavelengths. The aforementioned <2> The measuring device according to claim 1.

[0098] <4> The light source includes a plurality of linear light sources formed by arranging the point light sources in an arrangement direction in a predetermined order and arranging the point light sources in an orthogonal direction perpendicular to the arrangement direction, The aforementioned <2> or the above <3> The measuring device according to claim 1.

[0099] <5> The first diffusion plate is disposed between the light source and the measurement object. The aforementioned <1> From the above <4> 10. The measuring device according to claim 9, wherein:

[0100] <6> The light-shielding portion is formed integrally with the second diffusion plate. The aforementioned <1> From the above <5> 10. The measuring device according to claim 9, wherein:

[0101] <7> The light source is red point light sources are arranged in a predetermined order in the arrangement direction, and a red linear light source is formed by arranging the red point light sources in the orthogonal direction; a green linear light source formed by arranging green point light sources in the arrangement direction in a predetermined order and arranging the green point light sources in the orthogonal direction; A blue point light source is arranged in the array direction in a predetermined order, and a blue linear light source formed by arranging the blue point light sources in the orthogonal direction are included. One or more sets of linear light sources, each including a red linear light source, a green linear light source, and a blue linear light source, are arranged in the array direction in a predetermined order. An illumination pattern is formed on the object to be measured, which is a uniform stripe pattern combined with a light and dark pattern in which the luminance of light changes sinusoidally in the array direction. When the width of one period of the sine wave of the luminance of the light included in the illumination pattern formed on the object to be measured is m, the number of the linear light sources included in the light source is n, and the width of the opening portion is w, the width w of the opening portion satisfies the relationship of m < w ≤ (n - 2) / 3. The measuring device according to any one of <4> to <6>. However, m is a natural number, and n is a natural number of 3 or more.

[0102] <8> When the width of one period of the sine wave of the luminance of the light included in the illumination pattern formed on the object to be measured is m, the number of the linear light sources included in the light source is n, and the width of the opening portion is w, and assuming n = 3(m + 1) or n = 3(m + 1)+1, the width w of the opening portion satisfies the relationship of m + 0.1 < w ≤ m + 0.2. The measuring device according to <7>.

[0103] However, m is a natural number, and n is a natural number of 3 or more.

[0104] <9> Two sets of the linear light sources are arranged in the array direction. The measuring device according to any one of <4> to <8>.

[0105] <10> When the width of one period of the sine wave of the luminance of the light included in the illumination pattern formed on the object to be measured is m, the number of the linear light sources included in the light source is n, and the width of the opening portion is w, and assuming n = 3(m + 1)-1, the width w of the opening portion satisfies the relationship of w = m. The aforementioned <7> From the above <9> 10. The measuring device according to claim 9, wherein: Here, m is a natural number and n is a natural number greater than or equal to 3.

[0106] <11> the light source includes five of the linear light sources; The width of the opening corresponds to the width of one set of the linear light sources. The aforementioned <10> The measuring device according to claim 1.

[0107] <12> a defect detection unit that generates image information based on the specularly reflected light from the measurement object received by the light receiving unit, calculates phase information based on the generated image information, and detects defects in the measurement object based on the calculated phase information, The aforementioned <1> From the above <11> 10. The measuring device according to claim 9, wherein:

[0108] <13> The measurement object is a vehicle body. The aforementioned <1> From the above <12> 10. The measuring device according to claim 9, wherein:

[0109] <14> The aforementioned <1> From the above <13> 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]

[0110] 1. Measuring equipment 2. Measurement object 2P surface 3. Conveyor 11 Lighting Department 12 Light receiving part 13 Light source 13a Point light source 14 First diffuser 15 Second diffuser 16 Light blocking section 17 Opening part 24 Defect detection section Fa array direction Fb Orthogonal direction G Linear light source set m Width of one set of linear light sources n is the number of linear light sources included in the light source w Width of opening [Prior art documents] [Patent documents]

[0111] [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, the illumination unit including a light source, a first diffusion plate, a second diffusion plate that is disposed between the first diffusion plate and the measurement object, and a light blocking unit that is disposed on the measurement object side of the second diffusion plate; a light receiving unit that receives specularly reflected light from the object to be measured illuminated by the illumination unit; Equipped with the light-shielding portion includes an opening portion in the second diffusion plate that includes an optical axis of the light emitted from the light source. Measuring device.

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 light source includes a plurality of linear light sources formed by arranging the point light sources in an arrangement direction in a predetermined order and arranging the point light sources in an orthogonal direction perpendicular to the arrangement direction. The measuring device according to claim 2 .

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

6. The light-shielding portion is formed integrally with the second diffusion plate. The measuring device according to claim 1 .

7. The light source is red point light sources are arranged in a predetermined order in the arrangement direction, and a red linear light source is formed by arranging the red point light sources in the orthogonal direction; a green linear light source formed by arranging green point light sources in the arrangement direction in a predetermined order and arranging the green point light sources in the orthogonal direction; blue point light sources are arranged in a predetermined order in the arrangement direction, and a blue linear light source is formed by arranging the blue point light sources in the orthogonal direction, one or more sets of linear light sources each including one red linear light source, one green linear light source, and one blue linear light source are arranged in a predetermined order in the arrangement direction, An illumination pattern is formed on the measurement object, which is a uniform stripe pattern that combines light and dark patterns in which the brightness of light varies sinusoidally in the array direction, where m is the width of one period of a sine wave of the luminance of light included in the illumination pattern formed on the measurement object, n is the number of the linear light sources included in the light source, and w is the width of the opening portion, the width w of the opening portion satisfies the relationship m<w≦(n−2) / 3.

5. The measuring device according to claim 4. Here, m is a natural number and n is a natural number of 3 or more.

8. where m is the width of one period of the sine wave of the luminance of light included in the illumination pattern formed on the measurement object, n is the number of the linear light sources included in the light source, and w is the width of the opening portion, and n = 3(m + 1) or n = 3(m + 1) + 1, the width w of the opening portion satisfies the relationship m + 0.1 < w ≦ m + 0.

2.

8. The measuring device according to claim 7. Here, m is a natural number and n is a natural number of 3 or more.

9. Two sets of the linear light sources are arranged in the arrangement direction.

5. The measuring device according to claim 4.

10. When the width of one period of the sine wave of the luminance of light included in the illumination pattern formed on the measurement object is m, the number of the linear light sources included in the light source is n, and the width of the opening portion is w, where n = 3(m + 1) - 1, the width w of the opening portion satisfies the relationship w = m.

8. The measuring device according to claim 7. Here, m is a natural number and n is a natural number of 3 or more.

11. the light source includes five of the linear light sources; The width of the opening corresponds to the width of one set of the linear light sources. The measuring device according to claim 10.

12. a defect detection unit that generates image information based on the specularly reflected light from the measurement object received by the light receiving unit, calculates phase information based on the generated image information, and detects defects in the measurement object based on the calculated phase information, The measuring device according to claim 1 .

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

14. 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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