Measuring device and measuring method

Abstract

The objective is to provide a measuring device that can improve the accuracy of measuring objects. [Solution] A measuring device according to one aspect of the present invention is a measuring device for measuring an object to be measured that is being transported in a transport direction, comprising: an illumination unit that illuminates the object to be measured and is fixedly installed; a light receiving unit that receives specularly reflected light from the object to be measured illuminated by the illumination unit; a distance measuring unit that measures a measurement distance, which is the distance from the object to be measured side of the illumination unit to the object to be measured; an illumination angle, which is the angle between a perpendicular line to a virtual plane in the transport direction including the position illuminated by the illumination unit on the surface of the object to be measured and the optical axis of the specularly reflected light from the object to be measured, and a change in the measurement distance, to calculate a movement distance, which is the distance to move the light receiving unit; and a drive unit that moves the light receiving unit by the calculated movement distance.

Description

Technical Field

[0001] The present invention relates to a measuring device and a measuring method.

Background Art

[0002] As a measurement object, for example, an inspection device for inspecting defects on the painted surface of a vehicle body is known. Patent Document 1 discloses a vehicle body inspection device including a lighting unit that illuminates the surface of the vehicle body, an imaging unit that images the surface of the vehicle body, and a moving unit that moves at least one of the lighting unit and the imaging unit.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In the vehicle body inspection device of Patent Document 1, the lighting unit and the imaging unit each move, and the stability of the operation is not always sufficient, so there is a possibility that the accuracy of measuring the measurement object is not always sufficient.

[0004] An object of the present invention is to provide a measuring device capable of improving the accuracy of measuring a measurement object in order to solve the above problems.

Means for Solving the Problems

[0005] A measuring device according to an aspect of the present invention is a measuring device that measures a measurement object conveyed in a conveyance direction, and includes a lighting unit that illuminates the measurement object and is fixedly installed, a light receiving unit that receives regular reflection light from the measurement object illuminated by the lighting unit, a distance measuring unit that measures a measurement distance that is the distance from the measurement object side of the lighting unit to the measurement object, a lighting angle that is an angle formed by a perpendicular line to a virtual plane in the conveyance direction including a position illuminated by the lighting unit on the surface of the measurement object and an optical axis of the regular reflection light from the measurement object, and a change amount of the measurement distance, and a calculation unit that calculates a movement distance that is a distance for moving the light receiving unit based on the lighting angle and the change amount of the measurement distance, and a drive unit that moves the light receiving unit by the calculated movement distance.

Effects of the Invention

[0006] According to the present invention, the accuracy of measuring objects can be improved. [Brief explanation of the drawing]

[0007] [Figure 1] This is a configuration diagram of a measuring device according to one embodiment of the present invention. [Figure 2] This figure shows the configuration of the optical unit according to one embodiment of the present invention. [Figure 3] This figure shows the relationship between the optical unit of the measuring device according to the first embodiment of the present invention and the object to be measured. [Figure 4] This is an optical arrangement diagram of a measuring device according to the first embodiment of the present invention. [Figure 5] This figure illustrates the illumination pattern formed on the second diffuser plate in a measuring device according to the first embodiment of the present invention. [Figure 6] This is a block diagram showing the hardware configuration of the processing unit of the measuring device according to the first embodiment of the present invention. [Figure 7] This is a block diagram showing the functional configuration of a measuring device according to the first embodiment of the present invention. [Figure 8] This is a diagram illustrating the operation of the optical unit in the comparative example. [Figure 9] This is a diagram illustrating the operation of the optical unit according to the first embodiment of the present invention. [Figure 10] This figure shows an optical arrangement according to a modified example of the measuring device according to the first embodiment of the present invention. [Figure 11] This figure shows an optical arrangement according to a modified example of the measuring device according to the first embodiment of the present invention. [Figure 12] This figure shows an optical arrangement according to a modified example of the measuring device according to the first embodiment of the present invention. [Figure 13] This is a flowchart illustrating the measurement method according to the first embodiment of the present invention. [Figure 14] This is a flowchart illustrating the defect detection process performed by the defect detection unit of the measuring device according to the first embodiment of the present invention. [Figure 15] This figure illustrates the operation of the optical unit in a measuring device according to a second embodiment of the present invention. [Modes for carrying out the invention]

[0008] The embodiments for carrying out the invention will be described below with reference to the drawings. In each drawing, the same reference numerals are used for identical components, and redundant explanations may be omitted.

[0009] [First Embodiment] <Optical System Configuration> Figure 1 is a configuration diagram of a measuring device 1 according to a first embodiment of the present invention. The measuring device 1 measures an object to be measured 2 that is being transported in the transport direction. The state of the object to be measured 2 may be represented by one or more characteristic values ​​based on an image of its surface 2P. The object to be measured 2 is transported by a transport unit 3. The object to be measured 2 is, for example, the body of a painted large automobile, passenger automobile, or small automobile. The body is, for example, the surface 2P of the body, and the surface 2P of the body may be painted. Note that the object to be measured 2 may be something other than a car body, and the surface 2P does not have to be painted.

[0010] The measuring device 1 includes an optical unit 10. The details of the optical unit 10 will now be described with reference to Figure 2. Figure 2 is a diagram showing the configuration of the optical unit 10 according to the first embodiment of the present invention. The optical unit 10 also comprises an illumination unit 11, a light receiving unit 12, and a drive unit 16. 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 object to be measured 2 and receives specularly reflected light from the illuminated object to be measured 2. The illumination unit 11 is fixedly installed, for example, on the housing of the optical unit 10, and illuminates the measurement point of the object to be measured 2. The measurement point is the position illuminated by the illumination unit 11. In the following, "the measurement point of the object to be measured 2" will also be simply referred to as "object to be measured 2" and "measurement point".

[0012] As an example of the light-receiving unit 12, 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) can be mentioned. The light-receiving unit 12 receives the specularly reflected light from the measurement object 2 illuminated by the illumination unit 11.

[0013] The light-receiving unit 12 may focus on the surface 2P of the measurement object 2 and receive and measure the reflected light from the measurement object 2 at a predetermined time interval or in response to a trigger signal from the outside. The illumination direction from the light source 13 and the light-receiving direction of the light-receiving unit 12 are arranged along the optical axis so as to be specularly reflected with respect to the surface 2P.

[0014] The light-receiving unit 12 is installed movably within the housing of the optical unit 10. The movement of the light-receiving unit 12 is performed by a driving unit 16 such as an actuator (not shown). The light-receiving unit 12 moves by the driving unit 16 such as an actuator so as to focus on the surface of the measurement object 2 in response to the width, positional deviation, and meandering of the measurement object 2, etc. Note that the measuring device 1 stores width information including information regarding the width of the measurement object 2 in a direction perpendicular to the conveyance direction in advance, and the movement of the light-receiving unit 12 may be performed based on the distance measurement data from the distance measurement sensor 7 and the width information of the measurement object 2.

[0015] In the measurement object 2, an area to be measured in advance by the measuring device 1 is set. Note that it is not necessary for all of the measurement object 2 to be the measurement area. For example, when the measurement object 2 is a vehicle body, it is common for areas with large curved surfaces such as door knobs and the vicinity of the edge portions of the vehicle body to be excluded from the measurement area. Therefore, the illumination unit 11 and the light-receiving unit 12 may set a region where measurement is possible as the measurement region in advance and be arranged accordingly.

[0016] When the light-receiving unit 12 is an imaging device, image information of the measurement object 2 is generated. The image information may be, for example, a two-dimensional color image. Examples of the light-receiving unit 12 include a visible light camera such as an area camera.

[0017] The surface 2P of the object to be measured 2 may be a smooth surface with a glossy finish. Light incident on 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, surface 2P is a collection of multiple curved surface regions with different normal directions and curvatures.

[0018] Furthermore, the measuring device 1 includes an encoder 4, a reader 5, a position sensor 6, a distance measuring sensor 7, a processing unit 20, and a result output unit 30. The processing unit 20 controls the timing of the operation of the measuring device 1. The encoder 4, reader 5, position sensor 6, and distance measuring sensor 7 are connected to the processing unit 20. The encoder 4 monitors the transport status of the transport unit 3, such as the transport speed. The reader 5 acquires information about the object to be measured 2 (unique ID, vehicle type, color, etc.) and width information including information about the width of the object to be measured 2 in a direction perpendicular to the transport direction.

[0019] The position sensor 6 acquires positional information of the object to be measured 2, such as information on its approach to the measurement area or whether or not it is present in the measurement area. The distance measuring sensor 7 uses TOF (Time of Flight) sensors, stereo cameras, and LiDAR (Light Detection And Ranging) sensors, etc., to measure the distance to the object to be measured 2.

[0020] The processing unit 20 measures the state of the object to be measured 2 based on the specular reflected light from the object to be measured 2 received by the light receiving unit 12, and detects defects. The result output unit 30 outputs characteristic values ​​and defect information at each measurement position of the object to be measured 2 in the form of a monitor, printer, or electronic data.

[0021] The measuring device 1 can provide information useful for identifying the cause of defects in the preceding process and for repairing defects in the subsequent process, based on the type of defect it has determined.

[0022] If the object to be measured 2 is a painted car body, the measuring device 1 measures the presence or absence of defects on the painted surface 2P of the car body, including the doors, hood, roof, trunk lid, and rear bumper. Here, defects on surface 2P refer to, for example, scratches, cracks, unevenness, dirt, discoloration defects, etc. Paint defects include, for example, blemishes, paint blemishes, pinholes, orange peel, etc.

[0023] In the example shown in Figure 1, the measuring device 1 is positioned on only one side of the transport unit 3, but this is not limited to this arrangement; it may be positioned on both sides of the transport unit 3. When the measuring device 1 is positioned on both sides of the transport unit 3, it may be positioned facing each other so as to sandwich the object to be measured 2, or it may be positioned offset from each other in the transport direction.

[0024] Figure 3 is a diagram showing the relationship between the optical section 10 and the object to be measured 2 of the measuring device 1 according to the first embodiment of the present invention. In Figure 3, (a) is a plan view and (b) is a front view. The object to be measured 2 is transported in the transport direction by the transport section 3. The optical section 10 is arranged in a gate shape so as to surround the transported object to be measured 2. The object to be measured 2 is transported at a constant speed inside the gate-shaped optical section 10 and measured. When the object to be measured 2 passes through the gate-shaped optical section 10, the entire object to be measured 2 is measured.

[0025] Figure 4 is an optical arrangement diagram of a measuring device 1 according to the first embodiment of the present invention. In Figure 4, (a) is a plan view and (b) is a front view. Figure 4(c) is a diagram showing the details of the light source 13. Figure 4 shows the arrangement direction Fa and the orthogonal direction Fb. The arrangement direction Fa indicates the arrangement direction in which the light sources 13B, 13G, and 13R are arranged. The orthogonal direction Fb indicates the direction perpendicular to the arrangement direction Fa. Components identical to those already described are denoted by the same reference numerals, and redundant explanations are omitted.

[0026] As shown in Figure 4(a), the measuring device 1 comprises an illumination unit 11 which includes a light source 13, a first diffuser plate 14, and a second diffuser plate 15.

[0027] Light source 13 includes multiple light sources 13B, 13G, and 13R. Light sources 13B, 13G, and 13R each emit light at a different wavelength. For example, light sources 13B, 13G, and 13R may emit light in blue, green, and red, respectively. Light sources 13B, 13G, and 13R are arranged along the arrangement direction Fa. The arrangement direction Fa has a predetermined angle with respect to the horizontal direction of the surface of the vehicle body.

[0028] Figure 4(b) shows the light-receiving unit 12 and light source 13 relative to the surface 2P of the object to be measured 2. The light source 13 has a long, directional beam in the orthogonal direction Fb. Multiple light-receiving units 12 are provided in the orthogonal direction Fb.

[0029] Furthermore, in light source 13, point light sources 13r, 13g, and 13b that emit light of the same wavelength are arranged in the orthogonal direction Fb. Therefore, linear light sources that emit light of different wavelengths may be arranged in a predetermined order in the arrangement direction Fa. Note that "point light sources 13r, 13g, and 13b" include a red point light source 13r, a green point light source 13g, and a blue point light source 13b, respectively, and when there is no need to distinguish between them, they are simply referred to as point light sources 13r, 13g, and 13b.

[0030] As shown in Figure 4(c), light source 13 includes light sources 13B, 13G, and 13R. Furthermore, light sources 13B, 13G, and 13R each consist of multiple point light sources 13b, 13g, and 13r arranged in an orthogonal direction Fb. In Figure 4, the colors are arranged in a predetermined order of blue, green, and red, but the order may differ, and may include colors other than blue, green, and red.

[0031] Furthermore, red, green, and blue are the minimum necessary colors for the phase shift calculation performed during defect detection, and are also versatile as they are the three primary colors of visible light.

[0032] Furthermore, in Figure 4(c), the blue point light source 13b, the green point light source 13g, and the red point light source 13r are each arranged in two rows in the orthogonal direction Fb, but they are not limited to two rows; they may be arranged in one row, three rows, or other multiple rows. The blue point light source 13b, the green point light source 13g, and the red point light source 13r are arranged in the orthogonal direction Fb at a pitch of, for example, several millimeters to several tens of millimeters. With such an arrangement, the light source 13 is used as a system that includes linear light sources of multiple colors.

[0033] Note that the number of blue point light sources 13b, green point light sources 13g, and red point light sources 13r does not necessarily have to be the same, and can be changed according to the luminous intensity, spectral sensitivity of the light receiving unit 12, etc.

[0034] Furthermore, the point light sources 13r, 13g, and 13b may be equipped with lens members that guide the optical path of the emitted light to the object to be measured 2. The lens members are provided, for example, on the chips of each of the point light sources 13r, 13g, and 13b. By providing lens members, the divergence angle of the light emitted by the point light sources 13r, 13g, and 13b can be reduced, and the directivity is increased. As a result, a high-power illumination pattern can be formed on the second diffuser plate 15. Moreover, the degree of freedom of the divergence angle of the light emitted by the point light sources 13r, 13g, and 13b is increased when forming a sinusoidal illumination pattern in the array direction Fa and a uniform illumination pattern in the orthogonal direction Fb.

[0035] The point light sources 13r, 13g, and 13b may be LED (Light Emitting Diode) elements, organic EL (Electro Luminescence) elements, or laser elements. Furthermore, in order to form a higher brightness illumination pattern on the second diffuser plate 15, optical elements may be added to the illumination section 11. For example, optical elements may be inserted between the point light sources 13r, 13g, and 13b and the first diffuser plate 14, or optical elements may be inserted in other areas.

[0036] The first diffusion plate 14 is disposed between the light source 13 and the measurement object 2. The second diffusion plate 15 is disposed between the first diffusion plate 14 and the measurement object 2. The second diffusion plate 15 forms an illumination pattern of the light that illuminates the measurement object 2. The formed illumination pattern can be used as a secondary light source for the measurement object 2.

[0037] The light source 13, the first diffusion plate 14, and the second diffusion plate 15 are arranged parallel to each other. That is, the arrangement direction Fa of the plurality of light sources 13B, 13G, 13R and the first diffusion plate 14 and the second diffusion plate 15 are arranged parallel to each other. Also, it is preferable that the lengths of the first diffusion plate 14 and the second diffusion plate 15 in the arrangement direction Fa are equal, and it is preferable that the length is larger than the length of the light source 13.

[0038] Also, FIG. 4(a) shows the distances L1 and L2. The distance L1 indicates the distance between the light source 13 and the first diffusion plate 14, and L2 indicates the distance between the first diffusion plate 14 and the second diffusion plate 15. In order to equalize the luminance distribution in the orthogonal direction Fb of the illumination pattern formed on the second diffusion plate 15, it is preferable to satisfy the relationship L1 < L2.

[0039] FIG. 5 is a diagram for explaining the illumination pattern formed on the second diffusion plate 15 in the measuring device 1 according to the first embodiment of the present invention. In FIG. 5, (a) shows the arrangement of the light source 13, (b) shows the distribution of the luminance of the light in the arrangement direction Fa, (c) shows the distribution of the luminance of the light in the orthogonal direction Fb, and (d) shows the illumination pattern formed on the second diffusion plate 15. Also, I shown in (b) and (c) indicates the luminance of the light. In the following description, the same components as those already described are denoted by the same reference numerals, and redundant descriptions are omitted.

[0040] As shown in FIG. 5(a), the light source 13 has a plurality of light sources 13R, 13G, 13B arranged in this order in the arrangement direction Fa. The light source 13R includes a plurality of red point light sources 13r, the light source 13G includes a plurality of green point light sources 13g, and the light source 13B includes a plurality of blue point light sources 13b, respectively.

[0041] Figure 5(b) shows the luminances Iar, Iag, and Iab. Luminances Iar, Iag, and Iab represent the luminances of the red light from light source 13R, the green light from light source 13G, and the blue light from light source 13B, respectively, in the array direction Fa. In order to calculate phase information by performing a phase shift operation performed during defect detection, it is preferable that the luminance distribution of each light be sinusoidal, but a distribution close to a sinusoid is also acceptable.

[0042] Figure 5(c) shows the luminances Ibr, Ibg, and Ibb. Luminances Ibr, Ibg, and Ibb represent the luminances of the red light from light source 13R, the green light from light source 13G, and the blue light from light source 13B, respectively, in the orthogonal direction Fb. As shown in the figure, the luminances Ibr, Ibg, and Ibb are all approximately the same in the orthogonal direction Fb. For light source 13 to be used as a linear light source, it is preferable that the luminance distribution of each light is uniform.

[0043] Figure 5(d) shows the brightness distribution for each of the red, green, and blue colors as an illumination pattern formed on the second diffuser plate 15. The sine waves in the array direction Fa corresponding to red, green, and blue are superimposed with a phase shift of 2π / 3 (rad) each. 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 striped pattern in which light and dark patterns are combined, in which the brightness of the light changes sinusoidally in the array direction Fa for each wavelength.

[0044] <Configuration of measuring device 1> Figure 6 is a block diagram showing the hardware configuration of the processing unit 20 of the measuring device 1 according to the first embodiment of the present invention. The processing 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 are electrically connected to each other via a bus 109.

[0045] The CPU 101 controls the operation of the processing unit 20. The ROM 102 stores programs and other data executed by the CPU 101. The RAM 103 is used as the work area for the CPU 101. The HDD 104 stores various data such as programs. The input / output interface 105 is an interface for inputting and outputting various signals and data to and from external devices.

[0046] Some or all of the functions of the CPU 101 may be implemented by electronic circuits such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). Alternatively, a GPU (Graphics Processing Unit) may be provided instead of the CPU 101.

[0047] Figure 7 is a block diagram showing the functional configuration of a measuring device 1 according to a first embodiment of the present invention. The measuring device 1 includes an illumination unit 11, a light receiving unit 12, a drive unit 16, a distance measuring unit 21, a calculation unit 22, a control unit 23, an information acquisition unit 24, and a defect detection unit 25. The measuring device 1 may also have a database 26 on other devices configured to communicate with it and on a server in the cloud, or it may have a database 26 on the measuring device 1 itself.

[0048] The illumination unit 11 is fixed in place and illuminates the object to be measured 2. The light receiving unit 12 receives specular reflected light from the object to be measured 2 illuminated by the illumination unit 11. The distance measuring unit 21 measures the distance from the illumination unit 11 on the object to be measured 2 side to the object to be measured 2. The distance measuring unit 21 measures the distance by acquiring distance measurement data from the distance measuring sensor 7.

[0049] The measurement distance may be, for example, the distance from the surface of the housing including the optical unit 10 on the side facing the object to be measured 2 to the object to be measured 2, but is not limited to this; it may be based on distance measurement data from a distance measuring sensor 7 installed on a fixed device such as the illumination unit 11. The measurement distance shall be the length of the perpendicular line from the surface of the housing of the optical unit 10 on the side facing the object to be measured 2 to a virtual plane. The virtual plane is the surface of the object to be measured 2 and is a virtual plane in the transport direction that includes the measurement point illuminated by the illumination unit 11.

[0050] The calculation unit 22 calculates the distance to move the light receiving unit 12, based on the illumination angle, which is the angle between the perpendicular to the virtual plane in the transport direction including the measurement point on the surface of the object to be measured 2 and the optical axis of the specularly reflected light from the object to be measured 2, and the change in the measurement distance. The change in the measurement distance is a value based on the change in distance measurement data at predetermined time intervals, and is a value corresponding to the change in the width, positional displacement, and meandering of the object to be measured 2.

[0051] The control unit 23 moves the light receiving unit 12 to the drive unit 16 by a calculated distance in the direction of transport, in the direction in which the measurement point illuminated by the illumination unit 11 has changed. More specifically, the control unit 23 moves the light receiving unit 12 to the drive unit 16 by a distance calculated by the calculation unit 22 in the direction in which the measurement distance has changed, in a direction parallel to the optical axis of the light incident on the object to be measured 2. In other words, the measurement distance changes due to the width, positional displacement, and meandering of the object to be measured 2, and the light receiving unit 12 moves in accordance with this change in measurement distance.

[0052] The information acquisition unit 24 acquires width information, including information about the width of the object to be measured 2 in a direction perpendicular to the transport direction. The width information can be acquired from the reader 5. In addition to width information, the information acquisition unit 24 may also acquire information about the shape of the object to be measured 2. At this time, the calculation unit 22 calculates the movement distance of the light receiving unit 12 based on the change in measurement distance and the width information, etc. By using the width information, it becomes possible to verify the calculation result of the movement distance of the light receiving unit 12 by the calculation unit 22 and to detect errors.

[0053] The defect detection unit 25 detects defects by measuring the state of a measurement point on the object 2 based on the specularly reflected light from the object 2 received by the light receiving unit 12. More specifically, the defect detection unit 25 generates image information based on the specularly reflected light from the object 2 received by the light receiving unit 12, calculates characteristic values ​​based on the generated image information, and measures the state of the object 2 according to the calculated characteristic values.

[0054] More specifically, the defect detection unit 25 generates image information based on specularly reflected light from the object to be measured 2 received by the light receiving unit 12, and calculates phase information based on the distribution of light luminance included in the image information. The defect detection unit 25 calculates characteristic values ​​based on at least the phase information, and detects defects by measuring the state of the object to be measured 2 according to the characteristic values.

[0055] Furthermore, the defect detection unit 25 may calculate one or more characteristic values ​​based on a predetermined algorithm. The defect detection unit 25 may also calculate characteristic values ​​based on luminance information, phase information, color information, and information combining these multiple pieces of information. Examples of characteristic values ​​include the magnitude of the peak value of the signal level in a region that is a candidate for a defect, the amount of change in the slope of the signal, and the area of ​​the region.

[0056] Furthermore, the defect detection unit 25 detects defects based on the calculated characteristic values ​​and defect judgment criteria. The defect detection unit 25 also detects defects using a defect inspection algorithm based on the characteristic values, the state of the surface 2P, and inspection criteria set for each type of defect.

[0057] Database 26 stores width information, including information about the width of the object to be measured 2 in the direction perpendicular to the transport direction. Database 26 may be provided on other devices configured to communicate with the measuring device 1, or on a server in the cloud, or it may be provided on the measuring device 1.

[0058] <Operation of the optical unit 90 in the comparative example> Figure 8 is a diagram illustrating the operation of the optical unit 90 in a comparative example. Figure 8 shows an example of the operation of the optical unit 90 when the measurement distance, which is the distance from the surface of the housing of the optical unit 90 on the side facing the object to be measured 2 to the object to be measured 2, changes, with (a) showing the state before the light receiving unit 92 moves and (b) showing the state after the light receiving unit 92 moves.

[0059] In the diagram, P0, P1, and P2 represent virtual planes, with P0 being the reference virtual plane. Virtual plane P1 is the plane in the transport direction that contains the measurement point when the width of the object to be measured 2 in the direction perpendicular to the transport direction is maximum. Virtual plane P2 is the plane in the transport direction that contains the measurement point when the width of the object to be measured 2 in the direction perpendicular to the transport direction is minimum. The reference virtual plane P0 is a plane parallel to virtual planes P1 and P2, and is located between virtual planes P1 and P2.

[0060] Furthermore, Fc in the figure indicates the transport direction. W0, W1, and W2 indicate the measurement distance when the measurement point is located on the reference virtual plane P0, virtual plane P1, and virtual plane P2, respectively. In the illustrated example, the measurement point changes from point M0 to point M2, and the change in measurement distance is assumed to be p2.

[0061] The optical unit 90 in the comparative example comprises an illumination unit 91 and a light receiving unit 92. The illumination unit 91 illuminates the object to be measured 2 with linear light. The light receiving unit 92 receives specular reflected light from the object to be measured 2 illuminated by the illumination unit 91. The illumination unit 91 also includes a plurality of linear light sources 93. The linear light sources 93 are arranged in an order that alternates between red linear light sources, green linear light sources, and blue linear light sources. The light receiving unit 92 receives specular reflected light from the illuminated object to be measured 2. The first diffuser plate 94 and the second diffuser plate 95 are placed between the linear light sources 93 and the object to be measured 2.

[0062] As shown in Figure 8(a), the distribution of reflected light from the object being measured changes as the width of the object being measured changes. Also, because the measurement point becomes point M2, the positional relationship with the optical axis of the light receiving unit 92 changes, and the distribution of reflected light on the captured image changes. These changes affect the accuracy of defect detection in the object being measured 2, making accurate defect detection difficult.

[0063] As a countermeasure, the light-receiving unit 92 is moved in the direction of the reflected light's optical axis, as indicated by the arrow in Figure 8(b), using the drive unit 96. In this case, although the light-receiving unit 92 is in focus with respect to point M2 where the measurement point is located, the positional relationship between point M2 and the optical axis of the light-receiving unit 92 becomes misaligned. Therefore, even if the light-receiving unit 92 is moved in the optical axis direction to adjust the focus, the resulting image is not desirable, and accurate detection of defects is difficult.

[0064] <Operation of the optical unit 10 according to the first embodiment> Figure 9 is a diagram illustrating the operation of the optical unit 10 according to the first embodiment of the present invention. In Figure 9, (a) shows the case where the measurement point is point M0 on the reference virtual plane P0, and (b) shows the case where the measurement point moves to point M2. In this case, the amount of change in the measurement distance is p2. For simplicity, the illustration of the object to be measured 2 is omitted. Also, the same reference numerals are used for components that have already been described, and redundant explanations are omitted.

[0065] Furthermore, θ in the figure represents the illumination angle between the perpendicular to the virtual plane P2 and the optical axis of the specularly reflected light from the object being measured 2. The measurement point is located at point M2, which is the intersection of the virtual plane P2 and the optical axis of the light incident on the object being measured 2. Also, arrow A in the figure indicates the direction in which the measurement point has changed, and is in line with the optical axis of the light incident on the object being measured 2. w in the figure represents the width of the arrangement direction Fa of the light source 13.

[0066] Even if the width of the object to be measured 2 changes and the position of the measurement point changes, the illumination conditions from the illumination unit 11 are set so that the distribution of light illuminating the surface of the object to be measured 2 remains almost constant. The illumination conditions are that the illumination light from the light source 13 is shone onto the measurement point in roughly parallel directions, and that the change in the position of the measurement point is sufficiently small relative to the distance from the light source 13 to the measurement point. In this case, the change in the positional relationship between the light source 13 and the measurement point is negligible from the standpoint of the width W of the arrangement direction Fa of the light source 13 and the detection of defects.

[0067] Furthermore, it is desirable to move the light-receiving unit 12 so that the positional relationship between the measurement point and the light-receiving unit 12 does not change even if the width, positional displacement, or meandering of the object to be measured 2. In this case, the light-receiving unit 12 is moved by the drive unit 16 in the same direction as arrow A, which is parallel to the optical axis of the light incident on point M2, which is the measurement point of the object to be measured 2. The distance the light-receiving unit 12 moves at this time is p2 / cosθ.

[0068] In the measuring device 1 according to this embodiment, when the measurement point changes, instead of moving the entire optical unit 10, the illumination unit 11 is fixed, and only the light-receiving unit 12 is moved as shown by arrow A. As a result, the positional relationship between the measurement point and the light-receiving unit 12 does not change, and the measurement point in the captured image is in focus. Therefore, a good captured image can be obtained, and defects can be detected accurately.

[0069] Furthermore, since the illumination angle θ is a fixed value, the calculation unit 22 can uniquely calculate the distance to be moved to the light receiving unit 12. The control unit 23 moves the light receiving unit 12 in the direction of movement and the result of the distance to be moved calculated by the calculation unit 22. More specifically, the control unit 23 moves the light receiving unit 12 using a drive unit 16 such as an electric actuator. The drive unit 16 moves the light receiving unit 12 by the distance to be moved calculated by the calculation unit 22. The drive unit 16 moves the light receiving unit 12 between the time the object to be measured 2 has been transported by the transport unit 3 and the time the next object to be measured 2 is brought in, and does not move the light receiving unit 12 while the object to be measured 2 is being measured.

[0070] Furthermore, it is preferable that the reference virtual plane P0 is a reference plane where the measurement distance is midway between the distance when the width of the object to be measured 2 is maximum and the distance when the width of the object to be measured 2 is minimum. In this case, the measurement distance w0 is midway between measurement distances w1 and w2, and p1 = p2. The position of the light receiving unit 12 when the measurement point is at position M0 and the measurement distance is w0 is then used as the reference position.

[0071] The light-receiving unit 12 moves by a distance calculated by the calculation unit 22 in response to changes in the measurement distance, starting from the reference position. This has the advantage of minimizing the movement distance of the light-receiving unit 12, resulting in lower costs for components such as the electric actuator included in the drive unit 16. The reference position of the light-receiving unit 12 is not limited to this; it may also be set based on the width information of the object to be measured 2, with weighting based on the shape of the object to be measured 2, so that the cumulative movement distance of the light-receiving unit 12 decreases.

[0072] <Example 1> Figure 10 shows an optical arrangement according to a modified example of the measuring device 1 according to the first embodiment of the present invention. In Figures 10 to 12, the same reference numerals are used for components that have already been described, and redundant explanations are omitted.

[0073] Unlike in the first embodiment, the light source 13 of the illumination unit 11 is a multiple white directional light source that creates a periodic pattern of light and dark. As a result, a striped pattern is formed on the illuminated object to be measured 2. The light receiving unit 12 is composed of multiple area cameras and receives specularly reflected light from the illuminated object to be measured 2. The light receiving unit 12 is configured to be movable by the drive unit 16.

[0074] In the illustrated example, three white LEDs are arranged at equal intervals in the light source 13. The illumination direction from the light source 13 and the optical axis direction of the light receiving unit 12 are arranged to be specularly reflected with respect to the object to be measured 2. Also, unlike the first embodiment, in the illustrated example, the second diffuser plate 15 is not provided, and only the first diffuser plate 14 is present. Note that the second diffuser plate 15 may be provided in other examples as well. The number of white LEDs is not limited to three, but can be any number. Even without using light of multiple wavelengths in the light source 13, the light beam is diffused by the first diffuser plate 14 as in the embodiment, making it possible to measure the object to be measured 2 at a lower cost.

[0075] <Modification 2> Figure 11 shows an optical arrangement according to a modified example of the measuring device 1 according to the first embodiment of the present invention. Unlike the first embodiment, the light source 13 of the illumination unit 11 is a plurality of white directional light sources that form a periodic pattern of light and dark, and the light source 13 and the first diffuser plate 14 are provided parallel to the transport direction Fc.

[0076] In this modified example, the second diffuser plate 15 is not provided, and only the first diffuser plate 14 is present, however, the second diffuser plate 15 may also be provided. Furthermore, the light source 13 includes multiple light sources 13B, 13G, and 13R, similar to the embodiment, and for example, light sources 13B, 13G, and 13R may emit blue, green, and red light, respectively. Since the measurement point of the object to be measured 2 is illuminated by the first diffuser plate 14, measurement of the measurement point can be performed in the same manner as in this embodiment.

[0077] <Variation 3> Figure 12 is a diagram showing an optical arrangement according to a modified example of the measuring device 1 according to the first embodiment of the present invention. The illustrated example shows another example of the arrangement of point light sources 13r, 13g, and 13b. In Figure 12, the same reference numerals are used for components that have already been described, and redundant explanations are omitted.

[0078] Unlike Figure 4(c), in Figure 12, the multiple blue point light sources 13b, multiple green point light sources 13g, and multiple red point light sources 13r are arranged in a staggered pattern with respect to the orthogonal direction Fb.

[0079] <Measurement method> Figure 13 is a flowchart illustrating a measurement method according to a first embodiment of the present invention. The measurement method is performed in the measuring device 1. First, the illumination unit 11 of the measuring device 1 illuminates the object to be measured 2 (step S101). Subsequently, the light receiving unit 12 of the measuring device 1 receives the specular reflected light from the object to be measured 2 illuminated by the illumination unit 11 (step S102).

[0080] The distance measuring unit 21 measures the measurement distance, which is the distance from the side of the illumination unit 11 that illuminates the object to be measured 2 to the object to be measured 2 (S103). The calculation unit 22 calculates the movement distance, which is the distance to move the light receiving unit 12 that receives specular reflected light from the object to be measured 2, based on the illumination angle θ and the amount of change in the measurement distance (S104). The control unit 23 moves the light receiving unit 12 to the drive unit 16 by the movement distance calculated by the calculation unit 22 in the transport direction and in the direction in which the measurement point illuminated by the illumination unit 11 has changed (S105).

[0081] The defect detection unit 25 generates image information based on specularly reflected light from the object to be measured 2 received by the light receiving unit 12 (step S106). If there are multiple light receiving units 12, image information for multiple regions of the object to be measured 2 may be generated. The defect detection unit 25 calculates characteristic values ​​based on the generated image information (step S107). The defect detection unit 25 detects defects in the object to be measured 2 according to the calculated characteristic values ​​(step S108).

[0082] These steps carry out the measurement method according to one embodiment of the present invention. 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.

[0083] <Processing performed by the defect detection unit 25> Figure 14 is a flowchart illustrating the defect detection process performed by the defect detection unit 25 of the measuring device 1 according to the first embodiment of the present invention. In this case, the light source 13 uses three colors: red, green, and blue.

[0084] The processing performed by the defect detection unit 25 can be broadly divided into two parts: pre-processing to highlight defects in the object to be measured 2, and post-processing to detect defects based on the image obtained in the pre-processing. In Figure 14, the pre-processing is shown in steps S201 to S205, and the post-processing is shown in steps S206 to S208.

[0085] First, the light receiving unit 12 receives specularly reflected light from the object to be measured 2 and acquires image information (step S201). This image information is used for defect detection in the defect detection unit 25. At this time, the light receiving unit 12 may store the acquired image information in the HDD 104 or the like of the measuring device 1.

[0086] Next, the defect detection unit 25 decomposes the image information of the object to be measured 2 acquired in step S201 into RGB colors (step S202). Specifically, it extracts the R signal, which represents red, the G signal, which represents green, and the B signal, which represents blue, from the image information. Since the spectral sensitivity curve of the light receiving unit 12 generally has overlap between the R, G, and B signals, the simply decomposed signals of each color contain crosstalk. The defect detection unit 25 performs a correction process called crosstalk correction in order to extract the R, G, and B signals that do not contain crosstalk.

[0087] The defect detection unit 25 calculates phase information based on the image information acquired in step S201 (step S203). Specifically, it performs smoothing on each RGB color signal decomposed in step S202 based on the distribution of light luminance contained in the image information. Known averaging filters and bilateral filters that preserve edges are used in the smoothing process. Then, the defect detection unit 25 calculates phase information by performing a phase shift operation using each smoothed signal. As a result, a two-dimensional phase image is acquired. For the defect detection unit 25 to perform a phase shift operation and calculate phase information, it is preferable that the distribution of light luminance is sinusoidal, but a distribution of light luminance that is close to a sinusoid is acceptable.

[0088] Subsequently, the defect detection unit 25 performs edge extraction processing based on the phase information calculated in step S203 (step S204). Specifically, edge extraction processing is performed on the two-dimensional phase image, and known differential filters such as the Sobel filter, the Laplacian filter, and second-order differential filters such as the LoG filter are used.

[0089] The defect detection unit 25 creates a two-dimensional defect-enhanced image in which defects of the object to be measured 2 are highlighted by performing the pre-processing steps S201 to S205. In the following post-processing steps, the defect detection unit 25 detects defects based on the defect-enhanced image. The defect-enhanced image is an image based on phase information, and at least one characteristic value is an image based on phase information.

[0090] First, the defect detection unit 25 extracts regions that are candidates for defects from the two-dimensional defect-enhanced image (step S205). The extraction process extracts regions that are candidates for defects by combining processes such as binarization and shrinking / expanding. At this time, regions that are candidates for defects may be extracted based on regions without defects in the object 2 being measured.

[0091] Next, the defect detection unit 25 calculates characteristic values ​​based on phase information for regions of the object 2 that are candidates for defects (step S206). The defect detection unit 25 may calculate one or more characteristic values ​​based on a predetermined algorithm. The defect detection unit 25 may also calculate characteristic values ​​based on luminance information, phase information, color information, and information combining these multiple pieces of information. The characteristic values ​​are, for example, the magnitude of the signal level (e.g., peak value) of the region that is a candidate for a defect, the amount of change in the signal (e.g., slope), and the area of ​​the region.

[0092] The defect detection unit 25 detects defects in the object to be measured 2 according to the characteristic value calculated in step S206 (step S207). In detecting defects, the presence or absence of defects may be determined by comparing the characteristic value with the defect judgment criteria. Note that the characteristic value is not limited to one. The defect detection unit 25 can calculate multiple characteristic values ​​and comprehensively detect defects by comparing each characteristic value with the defect judgment criteria.

[0093] Furthermore, characteristic values ​​can be calculated from image information acquired by the light-receiving unit 12, brightness based on decomposed RGB colors, etc., or from a combination of this information and phase information. For example, the defect detection unit 25 may calculate characteristic values ​​based on phase information and characteristic values ​​based on brightness to detect defects. Since there are many types of defects, characteristic values ​​corresponding to the characteristics of the defects are required.

[0094] <Effects and Effects> In the measuring device 1 according to this embodiment, a fixedly installed illumination unit 11 illuminates the object to be measured 2 as it is being transported in the transport direction, and a light receiving unit 12 receives specularly reflected light from the object to be measured 2. Since the measurement distance, which is the distance from the illumination unit 11 to the object to be measured 2, changes according to the width, displacement, and meandering of the object to be measured 2, the light receiving unit 12 is moved based on the illumination angle θ and the amount of change.

[0095] The light-receiving unit 12 moves in the transport direction, in the direction in which the measurement distance changes, by the distance calculated by the calculation unit 22. As a result, in the captured image of the object to be measured 2, the measurement point is in focus, and the misalignment of the optical axis between the measurement point and the light-receiving unit 12 is so small that it can be ignored from the viewpoint of measurement accuracy. Therefore, the measurement accuracy of the object to be measured 2 is improved by the measuring device 1.

[0096] Furthermore, the measuring device 1 has a fixed illumination unit 11, and only the light-receiving unit 12, which is smaller and lighter than the illumination unit 11, moves. Therefore, the mechanism of the optical unit 10 can be constructed at a low cost. Also, in a production line where various types of objects to be measured 2 are produced, the movement of only the light-receiving unit 12 allows for stable and repeated movement according to the width of the objects to be measured 2 being transported. Thus, according to the measuring device 1 of this embodiment, the accuracy of measuring the objects to be measured 2 is improved, and it is possible to suppress introduction costs and maintain operational stability.

[0097] [Second Embodiment] Figure 15 is a diagram illustrating the operation of the optical unit 10 in the measuring device 1 according to the second embodiment of the present invention. The measuring device 1 according to this embodiment includes the optical unit 10. The optical unit 10 comprises an illumination unit 11, a light receiving unit 12, and a drive unit 16. The illumination unit 11 comprises a light source 13, a first diffuser plate 14, and a second diffuser plate 15. Components identical to those already described are denoted by the same reference numerals, and redundant explanations are omitted.

[0098] In Figure 15, (a) shows the range of movement of the light-receiving unit 12 when the measurement point moves from point M1 to point M2, as indicated by arrow B, and (b) shows the arrows B and C that indicate the movement of the light-receiving unit 12 extracted from Figure (a). Arrow C indicates the range of movement of the light-receiving unit 12 according to the depth of field (DOF) of the light-receiving unit 12. Also, d in the figure indicates the depth of field of the light-receiving unit 12.

[0099] Furthermore, the origin O in Figure 15(b) is point M0, which is the reference position of the measurement point. In the illustrated example, the measurement distance w0 is assumed to be midway between measurement distances w1 and w2. The virtual plane P1 when the width of the reference virtual plane P0 and the object being measured 2 is at its maximum, and the virtual plane P2 when the width of the reference virtual plane P0 and the object being measured 2 is at its minimum, are each separated by a distance p.

[0100] Furthermore, in the figure, θ represents the illumination angle formed by the perpendicular to the reference virtual plane P0 and the optical axis of the light incident on the object to be measured 2, and δ represents the angle formed by the perpendicular to the reference virtual plane P0 and the direction in which the light receiving unit 12 moves.

[0101] As shown in Figure 15(a), when the width of the object to be measured 2 is at its maximum, that is, when the measurement point is point M1, the light-receiving unit 12 allows for a depth of field up to the front and moves the light-receiving unit 12 by d / 2 in the direction toward the measurement point. On the other hand, when the width of the object to be measured 2 is at its minimum, that is, when the measurement point is point M2, the light-receiving unit 12 allows for a depth of field up to the rear and moves the light-receiving unit 12 by d / 2 in the direction toward the measurement point.

[0102] Therefore, as shown in Figure 15(b), if the depth of field of the light-receiving unit 12 is not considered, the light-receiving unit 12 moves between arrow B, which is between points M1 and M2. If the depth of field of the light-receiving unit 12 is considered, the light-receiving unit 12 moves between arrow C, which is between points Pa and Pb. Thus, comparing arrows B and C, it can be seen that the distance traveled by the light-receiving unit 12 is shorter when the depth of field is considered.

[0103] When the illumination angle is θ, the change in measurement distance is p, the movement distance of the light-receiving unit 12 considering the depth of field is L, and the angle between the perpendicular to the virtual planes P0, P1, P2 and the direction in which the light-receiving unit 12 moves is δ, the movement distance L and angle δ satisfy the following relationships (1) and (2). tanδ=(psinθ / cosθ+dsinθ / 2) / (-p+dcosθ / 2) ···(1) L = √{(p / cosθ)} 2 -pdcos2θ / cosθ+(d / 2)2} ···(2)

[0104] <Effects of the measuring device 1 according to this embodiment> According to the measuring device 1 of this embodiment, as long as the imaging surface of the light-receiving unit 12 is within the depth of field, it is possible to capture an image of the object to be measured in good condition. Therefore, the movement distance of the light-receiving unit 12 in response to changes in the measurement distance of the object to be measured can be shortened.

[0105] Although embodiments have been described above, the present invention is not limited to the embodiments described above, and various modifications and improvements are possible within the scope of the present invention.

[0106] Examples of the present invention are as follows: <1> A measuring device for measuring an object being transported in the transport direction, The aforementioned object to be measured is illuminated by a fixedly installed lighting unit, A light receiving unit that receives specularly reflected light from the object to be measured illuminated by the illumination unit, A distance measuring unit measures the distance from the side of the lighting unit to the object to be measured, which is the distance to the object to be measured. A calculation unit calculates a distance to move the light receiving unit based on the illumination angle, which is the angle between the perpendicular to the virtual plane in the transport direction including the position illuminated by the illumination unit on the surface of the object to be measured, and the optical axis of the specularly reflected light from the object to be measured, and the amount of change in the measurement distance. A drive unit moves the light receiving unit by the calculated distance, A measuring device equipped with this device. <2> The drive unit moves the light receiving unit by the specified distance in a direction parallel to the optical axis of the light incident on the object to be measured, in the direction in which the position illuminated by the illumination unit has changed. The aforementioned <1> The measuring device described above. <3> The distance measuring unit measures the distance from the surface of the housing, which includes the illumination unit and the light receiving unit, on the side facing the object to be measured, to the object to be measured, using a distance measuring sensor. The measurement distance is the length of the perpendicular from the surface of the housing on the side of the object to be measured to a virtual plane in the transport direction that includes the position illuminated by the illumination unit on the surface of the object to be measured. The aforementioned <1> or the above <2> The measuring device described above. <4> When the change in the measurement distance is p and the illumination angle is θ, The movement distance of the light-receiving unit calculated by the calculation unit is p / cosθ. The aforementioned <3> The measuring device described above. <5> When the change in the measurement distance is p, the illumination angle is θ, the depth of field of the light-receiving unit is d, the movement distance of the light-receiving unit is L, and the angle between the perpendicular to the virtual plane and the direction in which the light-receiving unit moves is δ, the movement distance L and the angle δ satisfy the following relationships (i) and (ii): The aforementioned <3> The measuring device described above. tanδ=(psinθ / cosθ+dsinθ / 2) / (-p+dcosθ / 2) ···(i) L = √{(p / cosθ)} 2 -pdcos2θ / cosθ+(d / 2) 2} ···(ii) <6> The system further includes an information acquisition unit that acquires width information, including information regarding the width of the object to be measured in a direction perpendicular to the transport direction. The calculation unit calculates the movement distance of the light receiving unit based on the amount of change in the measured distance and the width information. The aforementioned <1> from the above <5> A measuring device as described in any one of the following. <7> The calculation unit calculates the travel distance using the position of the light-receiving unit as the reference position when the measurement distance is the intermediate distance between the case where the width of the object to be measured is maximum and the case where the width of the object to be measured is minimum. The drive unit moves the light receiving unit by the distance described above, starting from the reference position. The aforementioned <6> The measuring device described above. <8> The system further includes a defect detection unit that detects defects in the object to be measured based on specularly reflected light from the object to be measured received by the light receiving unit. The aforementioned <1> from the above <7> A measuring device as described in any one of the following. <9> The object to be measured is the vehicle body. The aforementioned <1> from the above <8> A measuring device as described in any one of the following. <10> A measurement method performed by a measuring device that measures an object to be measured as it is being transported in the transport direction, The step of illuminating the object to be measured, The steps include receiving specularly reflected light from the illuminated object to be measured, The steps include measuring the measurement distance, which is the distance from the side of the lighting unit that illuminates the object to be measured to the object to be measured, A step of calculating a movement distance, which is the distance by which a light-receiving unit that receives specularly reflected light from the object to be measured is moved, based on the illumination angle, which is the angle between the perpendicular line to the virtual plane in the transport direction including the position illuminated by the illumination unit on the surface of the object to be measured, and the optical axis of the specularly reflected light from the object to be measured, and the amount of change in the measurement distance. The steps include moving the light-receiving unit by the calculated distance, A measurement method that includes [details omitted]. [Explanation of Symbols]

[0107] 1. Measuring device 2. Object to be measured 2P surface 3. Conveying section 7 Distance measuring sensor 10 Optics Department 11 Lighting Section 12 Light receiving part 16 Drive unit 20 Processing Units 21 Ranging section 22 Calculation Section 23 Control Unit 24 Information Acquisition Department 25 Defect detection unit P0 Reference Virtual Plane P1, P2 virtual plane θ illumination angle [Prior art documents] [Patent Documents]

[0108] [Patent Document 1] Japanese Patent Publication No. 2024-134409

Claims

1. A measuring device for measuring an object being transported in the transport direction, The aforementioned object to be measured is illuminated by a fixedly installed lighting unit, A light receiving unit that receives specularly reflected light from the object to be measured illuminated by the illumination unit, A distance measuring unit measures the distance from the side of the lighting unit to the object to be measured, which is the distance to the object to be measured. A calculation unit calculates a distance to move the light receiving unit based on the illumination angle, which is the angle between the perpendicular to the virtual plane in the transport direction including the position illuminated by the illumination unit on the surface of the object to be measured, and the optical axis of the specularly reflected light from the object to be measured, and the amount of change in the measurement distance. A drive unit moves the light receiving unit by the calculated distance, A measuring device equipped with this device.

2. The drive unit moves the light receiving unit by the specified distance in a direction parallel to the optical axis of the light incident on the object to be measured, in the direction in which the position illuminated by the illumination unit has changed. The measuring device according to claim 1.

3. The distance measuring unit measures the distance from the surface of the housing, which includes the illumination unit and the light receiving unit, on the side facing the object to be measured, to the object to be measured, using a distance measuring sensor. The measurement distance is the length of the perpendicular from the surface of the housing on the side of the object to be measured to a virtual plane in the transport direction that includes the position illuminated by the illumination unit on the surface of the object to be measured. The measuring device according to claim 1.

4. When the change in the measurement distance is p and the illumination angle is θ, The movement distance of the light-receiving unit calculated by the calculation unit is p / cosθ. The measuring device according to claim 3.

5. When the change in the measurement distance is p, the illumination angle is θ, the depth of field of the light-receiving unit is d, the movement distance of the light-receiving unit is L, and the angle between the perpendicular to the virtual plane and the direction in which the light-receiving unit moves is δ, the movement distance L and the angle δ satisfy the following relationships: (i) and (ii). The measuring device according to claim 3. tanδ=(psinθ / cosθ+dsinθ / 2) / (-p+dcosθ / 2) ・・・(i) L=√{(p / cosθ) 2 -pdcos2θ / cosθ+(d / 2) 2 } ・・・(ii)

6. The system further includes an information acquisition unit that acquires width information, including information regarding the width of the object to be measured in a direction perpendicular to the transport direction. The calculation unit calculates the movement distance of the light receiving unit based on the amount of change in the measured distance and the width information. The measuring device according to claim 1.

7. The calculation unit calculates the travel distance using the position of the light-receiving unit as the reference position when the measurement distance is an intermediate distance between the case where the width of the object to be measured is at its maximum and the case where the width of the object to be measured is at its minimum. The drive unit moves the light receiving unit by the distance described above, starting from the reference position. The measuring device according to claim 6.

8. The system further includes a defect detection unit that detects defects in the object to be measured based on specularly reflected light from the object to be measured received by the light receiving unit. The measuring device according to claim 1.

9. The object to be measured is the vehicle body. The measuring device according to claim 1.

10. A measurement method performed by a measuring device that measures an object to be measured as it is being transported in the transport direction, The step of illuminating the object to be measured, The steps include receiving specularly reflected light from the illuminated object to be measured, The steps include measuring the measurement distance, which is the distance from the side of the lighting unit that illuminates the object to be measured to the object to be measured, A step of calculating a movement distance, which is the distance by which a light-receiving unit that receives specularly reflected light from the object to be measured is moved, based on the illumination angle, which is the angle between the perpendicular to the virtual plane in the transport direction including the position illuminated by the illumination unit on the surface of the object to be measured and the optical axis of the specularly reflected light from the object to be measured, and the amount of change in the measurement distance. The steps include moving the light-receiving unit by the calculated distance, Measurement methods including

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