Surface inspection apparatus and surface inspection method

Abstract

To provide a surface inspection device and surface inspection method which can correctly determine an optical axis deviation of a light receiver with respect to an inspection object.SOLUTION: A surface inspection device 10 is configured to irradiate an inspection object W that is web-conveyed with inspection light from a light source 2, receive the inspection light passing through the inspection object W by a light receiver 5, detect a defect in the inspection object W on the basis of an output signal of the light receiver 5, irradiate a path roll 1 arranged in a visual area SA of the light receiver 5 and outside an area of the inspection object W with laser light from laser pointers 3, 4, receive laser reflection light reflected on the path roll 1 by the light receiver 5, and determine an optical axis deviation of the light receiver 5 with respect to the inspection object W on the basis of the laser reflection light received by the light receiver 5.SELECTED DRAWING: Figure 1

Description

Technical Field

[0006] , ,

[0001] [[ID=j4]] The present invention relates to a surface inspection apparatus and a surface inspection method.

Background Art

[0002] As this type of surface inspection apparatus, there is disclosed one including a light source that irradiates light onto the surface of an inspection object to be conveyed, and a plurality of imaging devices that receive the reflected light from the inspection object (see Patent Document 1). The surface inspection apparatus of Patent Document 1 includes a laser pointer that irradiates the surface of the inspection object with laser light having a luminance different from that of the light of the light source, and a diagnostic unit. The diagnostic unit has a configuration for detecting a deviation in the installation state of the imaging device from the difference in the position of the image of the laser light irradiation in the captured image of each imaging device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the surface inspection apparatus described in Patent Document 1, since the object irradiated with laser light by the laser pointer is the surface of the inspection object, the amount of received reflected light varies depending on the surface state of the inspection object such as the surface shape, roughness, and color. There is a problem that there is a possibility that the presence or absence of a deviation in the installation state of the imaging device cannot be accurately detected.

[0005] The present invention has been made to solve such problems, and an object thereof is to provide a surface inspection apparatus and a surface inspection method capable of accurately determining the optical axis deviation of a light receiver with respect to an inspection object.

Means for Solving the Problems

[0006] (1) The surface inspection apparatus according to the present invention is a surface inspection apparatus that irradiates an object to be inspected being transported on a web with inspection light from a light source, receives the inspection light that has passed through the object to be inspected with a light receiver, and detects defects in the object to be inspected based on the output signal of the light receiver, characterized in that it irradiates an object to be irradiated, which is located within the field of view of the light receiver but outside the area of ​​the object to be inspected, with laser light from a laser, receives the laser reflected light reflected by the object to be irradiated with the light receiver, and determines the optical axis misalignment of the light receiver with respect to the object to be inspected based on the laser reflected light received by the light receiver.

[0007] (2) The surface inspection apparatus according to the present invention is the surface inspection apparatus described in (1), characterized in that it calculates the amount of optical axis misalignment based on at least one of the position, width, and intensity of the laser reflected light on the reflective surface of the object to be irradiated.

[0008] (3) The surface inspection apparatus according to the present invention is the surface inspection apparatus described in (2), characterized in that the position of the laser reflected light is measured with reference to the edge of the field of view area of ​​the light receiver.

[0009] (4) The surface inspection apparatus according to the present invention is the surface inspection apparatus according to any one of (1) to (3), characterized in that at least one laser for irradiating the laser light is provided on one end side in a direction perpendicular to the transport direction of the object to be inspected, and at least one on the other end side in a direction perpendicular to the transport direction.

[0010] (5) The surface inspection apparatus according to the present invention is a surface inspection apparatus according to any one of (1) to (4), characterized in that the object to be irradiated is either a stationary member or a roller member that transports the object to be inspected via a web.

[0011] (6) The surface inspection apparatus according to the present invention is a surface inspection apparatus according to any one of (1) to (5), characterized in that the surface of the object to be irradiated that is irradiated with the laser light and the surface of the object to be inspected that is irradiated with the inspection light are arranged at the same plane height position.

[0012] (7) The surface inspection method according to the present invention is characterized by comprising: an irradiation step of irradiating an object to be irradiated, which is located within the field of view of a light receiver that receives the inspection light that has passed through the object to be irradiated, and outside the area of ​​the object to be irradiated, with laser light from a laser; a light receiving step of receiving the inspection light that has passed through the object to be irradiated and the laser reflected light reflected by the light receiving step of detecting a defect in the object to be irradiated based on the inspection light received by the light receiving step and determining the optical axis misalignment of the light receiving the object to be irradiated based on the laser reflected light.

[0013] The surface inspection apparatus according to the present invention described in (1) above is a surface inspection apparatus that irradiates an object to be inspected being transported on a web with inspection light from a light source, receives the inspection light that has passed through the object to be inspected with a light receiver, and detects defects in the object to be inspected based on the output signal of the light receiver, and has a configuration in which laser light is irradiated from a laser to an object to be irradiated which is positioned within the field of view of the light receiver but outside the area of ​​the object to be inspected, the laser reflected light reflected by the object to be irradiated with a light receiver, and the optical axis misalignment of the light receiver with respect to the object to be inspected is determined based on the laser reflected light received by the light receiver.

[0014] In this configuration, the surface inspection device inspects the object being transported via a web and determines the optical axis misalignment of the photodetector relative to the object. In the surface inspection device, laser light is irradiated from the laser onto an object positioned within the photodetector's field of view but outside the area of ​​the object being inspected. The surface of the object being irradiated is a stable surface with less variation compared to the surface of the object being inspected, and the photodetector can receive the laser reflected light reflected from the stable surface of the object being irradiated. Therefore, the optical axis misalignment of the photodetector relative to the object being inspected can be accurately determined based on the stable laser reflected light, ensuring the reliability of the photodetector's calibration.

[0015] The surface inspection apparatus according to the present invention described in (2) above calculates the amount of optical axis misalignment based on at least one of the position, width, and intensity of the laser reflected light on the reflective surface of the object to be irradiated. This configuration makes it possible to determine the optical axis misalignment of the photodetector and to identify the pattern of optical axis misalignment.

[0016] The surface inspection apparatus according to the present invention described in (3) above measures the position of the laser reflected light with respect to the edge of the receiver's field of view. This configuration clarifies the criteria for determining the optical axis misalignment of the receiver, and since the position of the laser reflected light is within the receiver's field of view, the position of the laser reflected light received by the receiver can be determined.

[0017] The surface inspection apparatus according to the present invention described in (4) above has at least one laser that emits laser light on one end of the object to be inspected in a direction perpendicular to the transport direction, and at least one laser on the other end of the object in a direction perpendicular to the transport direction. With this configuration, when an abnormality occurs in which the optical axis of the photodetector is misaligned in the direction in which the photodetector rotates around the optical axis, the misalignment of the optical axis of the photodetector can be accurately determined.

[0018] The surface inspection apparatus according to the present invention, as described in (5) above, uses either a stationary member or a roller member that transports the object to be inspected via a web as the object to be irradiated. With this configuration, the laser light is not irradiated onto the surface of a moving object to be inspected, and is irradiated onto the stationary member and roller member, which have stable surface conditions with less variation in their surface state. Therefore, compared to the case where the laser light is irradiated onto the object to be inspected, more stable laser reflected light is obtained, and the optical axis misalignment of the photodetector relative to the object to be inspected is accurately determined. As a result, the reliability of the photodetector calibration is ensured.

[0019] In the surface inspection apparatus according to the present invention described in (6) above, the surface of the object to be irradiated that is irradiated with the laser light and the surface of the object to be inspected that is irradiated with the inspection light are arranged at the same plane and height.

[0020] With this configuration, the distance from the surface of the irradiation target irradiated with the laser light to the light receiver is the same as the distance from the surface of the inspection target irradiated with the inspection light to the light receiver. Therefore, the distance of the reflected light of the inspection light received by the light receiver and the distance of the reflected light of the laser light received by the light receiver are approximately the same, and the deviation of the optical axis of the light receiver can be accurately determined.

[0021] The surface inspection method according to the present invention described in the above (7) has a light source that irradiates inspection light on an inspection target conveyed by a web, and within the visual field area of a light receiver that receives the inspection light passing through the inspection target and outside the area of the inspection target. An irradiation step of irradiating the irradiation target with laser light from a laser, a light receiving step of receiving, with the light receiver, the inspection light passing through the inspection target and the laser reflected light reflected by the irradiation target, and based on the inspection light received by the light receiver. And a determination step of detecting a defect of the inspection target and determining an optical axis deviation of the light receiver with respect to the inspection target based on the laser reflected light.

[0022] With this configuration, in the surface inspection method according to the present invention, the inspection target conveyed by the web is inspected, and the optical axis deviation of the light receiver with respect to the inspection target is accurately determined. The surface inspection method according to the present invention irradiates a laser beam from a laser onto an irradiation target disposed within the visual field area of the light receiver and outside the area of the inspection target. The surface of the irradiation target irradiated with the laser light is a stable surface with less variation compared to the surface of the inspection target, and the light receiver can receive the laser reflected light reflected from the stable surface of the irradiation target. Therefore, based on the stable laser reflected light, the optical axis deviation of the light receiver with respect to the inspection target can be accurately determined, and the reliability of the calibration of the light receiver is ensured.

Effect of the Invention

[0023] According to the present invention, it is possible to provide a surface inspection apparatus and a surface inspection method capable of accurately determining the optical axis deviation of a light receiver with respect to an inspection target.

Brief Description of the Drawings

[0024] [Figure 1] It is a schematic diagram of a surface inspection apparatus according to an embodiment of the present invention. FIG. 1(1) shows a perspective view, and FIG. 1(2) shows a side view. [Figure 2] It is a diagram of a surface inspection apparatus according to an embodiment of the present invention. FIG. 2(1) shows an explanatory diagram for explaining inspection light and laser light irradiated on a pass roll and an inspection object, and FIG. 2(2) shows an explanatory diagram for explaining an output signal of a light receiver. [Figure 3] A schematic diagram of a part for inspecting an inspection object with a surface inspection apparatus according to an embodiment of the present invention. [Figure 4] An explanatory diagram for explaining an output signal of inspection light received by a light receiver of a part for inspecting an inspection object excluding laser reflected light with a surface inspection apparatus according to an embodiment of the present invention. [Figure 5A] A diagram for explaining an optical axis abnormality (optical axis deviation in the width direction) of a surface inspection apparatus according to an embodiment of the present invention. [Figure 5B] A diagram for explaining an optical axis abnormality (optical axis deviation in the longitudinal direction) of a surface inspection apparatus according to an embodiment of the present invention. [Figure 5C] A diagram for explaining an optical axis abnormality (optical axis deviation in the rotational direction) of a surface inspection apparatus according to an embodiment of the present invention. [Figure 6] A process diagram of a surface inspection method by a surface inspection apparatus according to an embodiment of the present invention. [Figure 7] A table showing patterns of optical axis abnormalities. [Figure 8] It is a schematic diagram of a surface inspection apparatus according to Modification 1 of an embodiment of the present invention. FIG. 8(1) shows a plan view, and FIG. 8(2) shows a side view. [Figure 9] It is a schematic diagram of a surface inspection apparatus according to another Modification 2 of an embodiment of the present invention. FIG. 9(1) shows a front view, and FIG. 9(2) shows a side view.

Embodiments for Carrying Out the Invention

[0025] A surface inspection apparatus 10 and a surface inspection method according to an embodiment to which the surface inspection apparatus and the surface inspection method according to the present invention are applied will be described with reference to the drawings.

[0026] First, a surface inspection apparatus 10 according to an embodiment will be described. As shown in Figures 1(1) and 1(2), the surface inspection apparatus 10 includes a pass roll 1, a light source 2, laser pointers 3 and 4, a light receiver 5, a signal processing unit 6, and a display unit 7.

[0027] The surface inspection device 10 is configured to detect defects in the object W on the manufacturing line, such as scratches, dirt, and foreign matter on the surface of the object W, and to determine the optical axis misalignment of the light receiver 5 using the signal processing unit 6, and to display these signals and / or the determination results on the display unit 7. The object W is made of so-called web material such as long sheet-shaped steel plates or films. The surface inspection device 10 can determine the optical axis misalignment of the light receiver 5 without interfering with so-called online inspection, which inspects the object W while the manufacturing line is in operation.

[0028] As shown in Figure 1(1), the pass roll 1 is composed of cylindrical roller members. The pass roll 1 is positioned so that its axial direction is parallel to the object to be inspected W and extends in a direction perpendicular to the transport direction of the object to be inspected W. It is supported so as to be rotatable about its axis and has a configuration in which it contacts the object to be inspected W at its central portion in the axial direction to transport the web. In this embodiment, it contacts the lower surface of the object to be inspected W, which is transported horizontally in the direction indicated by arrow a, and changes the transport direction to a downward direction. The pass roll 1 corresponds to the roller member of the surface inspection apparatus according to the present invention and the object to be irradiated with laser light. The transport direction of web transport may be in the direction opposite to arrow a.

[0029] The light source 2 is composed of a light-emitting device such as a light-emitting diode that irradiates the surface of the object W to be inspected with inspection light 2a. As shown in Figure 1(2), the light source 2 is positioned downstream in the transport direction of the object W to be inspected, and at a distance from the pass roll 1, with respect to the line where the axis J of the pass roll 1 and the optical axis CS of the light receiver 5 intersect. The light source 2 is fixed to a fixing member (not shown).

[0030] Although Figure 1(2) shows the light source 2 positioned downstream in the transport direction, the light source 2 and the light receiver 5 only need to be positioned so that the defective part E (see Figure 4) of the object to be inspected W can be detected by specular or diffuse reflection, and the light source 2 may be positioned at other locations, such as upstream.

[0031] Light source 2 emits light upon receiving power and irradiates inspection light 2a toward the surface of the object W to be inspected on the pass roll 1. As shown in Figures 1(1) and 2(1), the irradiation of inspection light 2a is performed over the entire area from one end 1a to the other end 1b of the pass roll 1, which is approximately the same as the field of view SA of the light receiver 5, and over the entire width of the area WA from one end to the other in the width direction of the object W to be inspected. As shown in Figure 1(2), light source 2 irradiates inspection light 2a toward a linear area where a virtual plane containing the axis J of the pass roll 1 and the optical axis CS of the light receiver 5 intersects the surface (outer surface) of the pass roll 1. Light source 2 irradiates inspection light 2a toward the pass roll 1 from below the virtual plane. Since light source 2 irradiates inspection light 2a in a direction that intersects the virtual plane at an oblique angle, the reflected light that is specularly reflected from the surface of the object W to be inspected and the pass roll 1 is not received by the light receiver 5, and the diffusely reflected light is received by the light receiver 5. The amount of reflected light received by the light receiver 5 is less than the amount of reflected light specularly reflected from the surface of the object W and the pass roll 1.

[0032] Laser pointers 3 and 4 each have an LD (Laser Diode) light source, for example, and are positioned near one end 1a and the other end 1b of the pass roll 1, respectively. Laser pointers 3 and 4 emit laser light 3a and 4a from the LD light source to calibrate the optical axis CS of the photodetector 5.

[0033] As shown in Figures 1(2) and 2(1), the laser pointers 3 and 4 are positioned on a virtual plane that includes the axis J of the path roll 1 and the optical axis CS of the light receiver 5, with the optical axis LS included, and outside the field of view SA of the light receiver 5, which is enclosed by a dashed line in Figure 2(1). The laser pointers 3 and 4 are fixed to a fixing member (not shown).

[0034] The laser pointers 3 and 4 irradiate the surface of the pass roll 1 with laser beams 3a and 4a within the field of view SA of the receiver 5 and outside the area of ​​the object to be inspected W. The object to be inspected W is thin, and the surface of the pass roll 1 irradiated with laser beams 3a and 4a is at approximately the same plane and height as the surface of the object to be inspected W.

[0035] In this embodiment, the irradiation shape of the laser beams 3a and 4a is circular, and the shape of the laser reflected light 3b and 4b formed on the surface of the pass roll 1 is also circular, with a size, for example, a diameter of about 5 mm to 10 mm. However, the irradiation shape of the laser beams 3a and 4a may be other than circular. For example, the shape of the laser reflected light 3b and 4b formed on the surface of the pass roll 1 may be a vertically elongated rectangle extending diagonally with respect to the circumferential direction of the pass roll 1. When the shape of the laser reflected light 3b and 4b is rectangular, by setting the angle of inclination (°) of the pass roll 1 with respect to the axis J, irradiating one end 1a, and then irradiating the other end 1b with a laser of the reversed shape, it is possible to determine both the amount of deviation of the optical axis CS of the light receiver 5 in the transport direction of the object to be inspected W and the amount of deviation of the optical axis CS of the light receiver 5 in a direction perpendicular to the transport direction of the object to be inspected W. If the shape of the laser reflected light 3b and 4b formed on the surface of the pass roll 1 is rectangular, there is no restriction on the angle of inclination, but if the angle of inclination is 45° with respect to the transport direction of the object to be inspected, the amount of deviation of the optical axis CS of the light receiver 5 can be easily calculated.

[0036] As shown in Figure 2, the laser pointer 3 is positioned such that the angle of incidence α1(°) and the angle of reflection α2(°) of the laser beam irradiated onto the pass roll 1 are equal. That is, the laser pointer 3 is positioned so that it irradiates the pass roll 1 with laser beam 3a, and the laser reflected light 3b, which is specularly reflected off the surface of the pass roll 1, is received by the light receiver 5.

[0037] The laser pointer 4 is configured similarly to the laser pointer 3, consisting of an LD light source that uses an LD as its light-emitting element, and is located near the other end 1b of the pass roll 1. Laser light 4a is emitted from the LD light source to calibrate the optical axis CS of the photodetector 5.

[0038] The incident angle β1(°) and reflection angle β2(°) of the laser beam 4a emitted from the laser pointer 4 are also arranged to be equal, similar to the laser pointer 3, so that the laser reflected light 4b, specularly reflected by the pass roll 1, is received by the light receiver 5. Note that either the laser pointer 3 or 4 may be used alone. Note that the laser pointers 3 and 4 correspond to the lasers in the surface inspection apparatus according to the present invention.

[0039] The photodetector 5 has multiple image sensors, such as a known CCD (Charge-Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor, and is configured as a line camera in which each image sensor is arranged in a straight line. The photodetector 5 is connected to the signal processing unit 6, as shown in Figures 1(1) and 1(2).

[0040] As shown in Figure 1(2), the light receiver 5 has a reference position where the optical axis CS of the light receiver 5, indicated by a dashed line in the virtual plane described above, is perpendicular to the axis J of the pass roll 1. The waveform of the laser reflected light at the reference position is recorded in advance along with the positions of the laser reflected light 3b and 4b. The light receiver 5 is fixed to a fixed member that can change the angle of the light receiver, such as a tripod head (not shown), and if the optical axis CS is misaligned from the reference position shown in Figure 1(2), it is possible to adjust the optical axis CS back to the reference position. The light receiver 5 may be misaligned from the reference position in at least one of the following directions: (1) along the axis J of the pass roll 1 (width direction of the object under inspection), (2) perpendicular to the optical axis CS of the reference position and away from the axis J of the pass roll 1 in the radial direction of the pass roll 1 (longitudinal direction of the object under inspection), and (3) rotating around the optical axis CS of the reference position.

[0041] As shown in Figure 3, the light receiver 5 receives the inspection light 2a that is irradiated from the light source 2 onto the object to be inspected being transported via the web in the transport direction indicated by arrow a, and reflected from the surface of the object to be inspected W, i.e., has passed through the object to be inspected W, and transmits an output signal to the signal processing unit 6.

[0042] As shown in Figure 4, the output signal is output as a voltage (V) signal at each position in the width direction (x direction) of the object W to be inspected, perpendicular to the transport direction of the web transport. The light receiver 5 does not receive specularly reflected inspection light from the light source 2, where the angle of incidence and the angle of reflection are equal and the light is reflected equally from the reflective surface, but rather receives diffusely reflected inspection light that is diffusely reflected from the reflective surface and diffused in various directions. In this embodiment, a surface inspection device in which the light receiver 5 receives diffusely reflected inspection light is used for explanation, but the present invention is also applicable to a surface inspection device in which the light receiver 5 receives specularly reflected inspection light.

[0043] In areas of the object W being inspected that have defects, the inspection light is diffusely reflected, while in areas without defects, the inspection light is specularly reflected. Therefore, the light receiver 5 receives relatively more light from the areas with defects and relatively less light from other areas without defects. As a result, as shown in Figure 4, the output signal of the light receiver 5 becomes a relatively high voltage exceeding the preset judgment criterion Th in the defective area E, and a relatively low voltage below the judgment criterion Th in the areas without defects.

[0044] Furthermore, as shown in Figure 2(1), the light receiver 5 receives the laser reflected light 3b and 4b that is irradiated from the laser pointers 3 and 4 and specularly reflected from the surface of the pass roll 1, converts the received laser reflected light 3b and 4b into electrical signals, and transmits them to the signal processing unit 6 as output signals. Since the light receiver 5 receives the laser reflected light 3b and 4b that is specularly reflected from the laser beams 3a and 4a irradiated from the laser pointers 3 and 4 on the surface of the pass roll 1, the voltage in the part where the laser reflected light 3b and 4b is received is high. By positioning the laser pointers 3 and 4 at an angle of specular reflection relative to the light receiver 5, a large amount of light can be secured to the light receiver 5, making it possible to clearly distinguish it from the inspection light.

[0045] The output signals of the laser reflected light 3b and 4b, like the output signal of the inspection light 2a, are output as voltage (V) signals at a position in the width direction (axial direction of the pass roll 1) perpendicular to the web transport direction of the pass roll 1, as shown in Figure 2(2). This output signal includes signals for the position, width, and intensity of the laser reflected light 3b and 4b on the surface of the pass roll 1. In Figure 2(2), the horizontal axis represents the position in the width direction of the pass roll 1, and the vertical axis represents the voltage height.

[0046] The voltage output from the photodetector 5 is higher at the position where the specularly reflected laser light 3b and 4b are received compared to the surrounding area. The position where the laser reflected light 3b and 4b are received is represented by the rectangular position of the peak voltage value obtained from the signal output from the photodetector 5, specifically by position x1 measured with reference to one end T1 of the field of view area SA of the photodetector 5 and position x2 measured with reference to the other end T2.

[0047] In the example shown in Figure 2(2), the position x1 of the laser reflected light 3b is at a distance δ1 from one end T1 of the field of view SA of the receiver 5, closer to the center of the pass roll 1. The width of the laser reflected light 3b is represented by the width t1 of the rectangular voltage obtained from the signal output from the receiver 5. The intensity of the laser reflected light 3b is represented by the height h1 of the voltage obtained from the signal output from the receiver 5.

[0048] Similarly, the position x2 of the laser reflected light 4b is located at a distance δ2 from the other end T2 of the field of view SA of the receiver 5, closer to the center of the pass roll 1. The width of the laser reflected light 4b is represented by the width t2 of the rectangular voltage obtained from the signal output from the receiver 5. The intensity of the laser reflected light 4b is represented by the height h2 of the voltage obtained from the signal output from the receiver 5.

[0049] In addition, the positions of the laser reflected beams 3b and 4b may also be represented by the length between the laser reflected beam signal at one end T1 and the laser reflected beam signal at the other end T2, obtained from the signal output from the photodetector 5.

[0050] The case in which a misalignment of the optical axis CS of the photodetector 5 occurs, resulting in an optical axis anomaly, will be explained with reference to the drawings, regarding the position, width, and intensity signals of the laser reflected light.

[0051] If the optical axis CS of the photodetector 5 is misaligned in the width direction, for example, as shown in Figure 5A(1), if the optical axis CS is misaligned from the reference position toward one end 1a of the pass roll 1, the positions of the laser reflected light 3b and 4b received by the photodetector 5 will be misaligned in the width direction. As a result, as shown in Figure 5A(2), the rectangular portion representing the laser reflected light 3b and 4b in the output signal of the photodetector 5 will be misaligned from the position shown by the solid line toward the other end T2, as shown by the dashed line.

[0052] In the output signal of the photodetector 5, the rectangular portion representing the laser reflected light 3b is located at position x1, which is a distance δ1 from one end T1 of the field of view SA of the photodetector 5, closer to the center of the pass roll 1, when the optical axis CS is at the reference position. When the optical axis CS is shifted from the reference position toward one end 1a of the pass roll 1, it becomes position x1', which is a distance δ1' from one end T1' of the field of view SA of the photodetector 5, closer to the center of the pass roll 1. Similarly, the position of the laser reflected light 4b is located at position x2, which is a distance δ2 from the other end T2 of the field of view SA of the photodetector 5, closer to the center of the pass roll 1, when the optical axis CS is at the reference position. When the optical axis CS is shifted from the reference position toward one end 1a of the pass roll 1, it becomes position x2', which is a distance δ2' from the other end T2' of the field of view SA of the photodetector 5, closer to the center of the pass roll 1.

[0053] If the optical axis CS of the light receiver 5 is misaligned in the longitudinal direction, i.e., in the direction of transport of the object to be inspected W, for example, as shown in Figure 5B(1), if the optical axis CS is misaligned upstream (upwards in the figure) in the transport direction of the object to be inspected W, the amount of laser reflected light 3b and 4b received by the light receiver 5 decreases. As a result, as shown in Figure 5B(2), the rectangular portion representing the laser reflected light 3b and 4b in the output signal of the light receiver 5 changes from the size shown by the solid line to the size shown by the dashed line.

[0054] As the optical axis CS shifts longitudinally from its reference position, the laser reflected light 3b reflected from the surface of the pass roll 1 moves to a position x1' where the rectangular portion representing the laser reflected light 3b in the output signal of the photodetector 5 shown in Figure 5B(3) is located, at a distance δ1' from one end T1' of the field of view SA of the photodetector 5, closer to the center of the pass roll 1. Its width t also narrows to width t', and its height h decreases to height h'. Similarly, the rectangular portion representing the laser reflected light 4b also narrows in width and decreases in height.

[0055] If the misalignment of the photodetector 5 occurs in the rotational direction, that is, in the direction in which the photodetector rotates around the optical axis CS, for example, as shown in Figure 5C(1), if it rotates counterclockwise around the optical axis CS, the amount of laser reflected light 3b and 4b received by the photodetector 5 decreases. As a result, as shown in Figure 5C(2), the rectangular portion representing the laser reflected light 3b and 4b in the output signal of the photodetector 5 shrinks from the size shown by the solid line to the size shown by the dashed line, and its position also changes so that it shifts closer to the center of the pass roll 1.

[0056] The laser reflected light 3b reflected from the surface of the pass roll 1 shifts in a counterclockwise rotation around the optical axis CS from its reference position. As a result, the rectangular portion representing the laser reflected light 3b in the output signal of the receiver 5, as shown in Figure 5C(3), moves to a position x1' located at a distance δ1' from one end T1' of the field of view SA of the receiver 5, closer to the center of the pass roll 1. Its width t also narrows to width t', and its height h decreases to height h'. Similarly, the rectangular portion representing the laser reflected light 4b also shifts in position, narrows in width, and decreases in height. Consequently, the width of the object W being inspected widens on both sides.

[0057] The signal processing unit 6 consists of a microcomputer that includes a central processing unit that executes arithmetic processing according to a program, and a memory device that stores programs, data, and the like.

[0058] The signal processing unit 6 detects defects in the object under inspection W based on the voltage output from the photodetector 5 upon reception of the inspection light. The signal processing unit 6 also determines whether there is a misalignment of the optical axis CS of the photodetector 5 relative to the object under inspection W based on the voltage output from the photodetector 5 upon reception of the laser reflected light. Furthermore, the signal processing unit 6 can calculate the amount of misalignment of the optical axis CS of the photodetector 5 based on at least one of the position, width, and intensity of the laser reflected light 3b and 4b. The signal processing unit 6 monitors the misalignment of the optical axis CS in the width, longitudinal, and rotational directions of the photodetector 5 as shown in Figures 5A, 5B, and 5C, enabling early detection of optical axis abnormalities.

[0059] In the judgment of the inspection light by the signal processing unit 6, as shown in Figure 4, it is determined whether or not the voltage of the inspection light signal exceeds the judgment criterion Th. If the voltage of the inspection light signal output for the object to be inspected W does not exceed the judgment criterion Th, it is processed as a good product. If there is a part where the judgment criterion Th is exceeded, it is processed as having a defect E in that part. The judgment criterion Th is appropriately selected based on the specifications of the object to be inspected W, such as its size, structure, material, and shape, and data such as the setting specifications and experimental values ​​of the surface inspection device 10.

[0060] In the signal processing unit 6's determination of the laser reflected light, it determines whether the voltage output from the photodetector 5 is within an acceptable range relative to the voltage at the reference position, i.e., whether there is any optical axis misalignment. It also calculates the amount of misalignment, i.e., the amount of misalignment of the optical axis CS of the photodetector 5, and determines whether the amount of misalignment is within an acceptable range. If the waveform of the signal voltage of the laser reflected light does not exceed the acceptable range relative to the voltage at the waveform reference position, it is determined that there is no optical axis misalignment. If it exceeds the acceptable range relative to the voltage at the waveform reference position, it is determined that there is optical axis misalignment, and these signals and / or determination results are transmitted to the display unit 7. In addition, the following calculations and determinations of optical axis misalignment amounts can be performed as needed.

[0061] If the calculated deviation amount is within the acceptable range, the result is sent to the display unit 7, indicating that there is no optical axis abnormality. If the deviation amount is outside the acceptable range, the result is sent to the display unit 7, indicating that there is an optical axis abnormality. The acceptable range for the deviation amount is appropriately selected based on the specifications of the object to be inspected W, such as its size, structure, material, and shape, and data such as the setting specifications and experimental values ​​of the surface inspection device 10.

[0062] For example, if the rectangular portions representing the laser reflected light 3b and 4b in the output signal of the light receiver 5 are both shifted in the direction of the other end T2, as shown by the dashed line in Figure 5A(2), then an optical axis abnormality in the width direction is determined based on the amount of shift relative to the reference position, and if the amount of shift exceeds the allowable range, it is determined that there is an optical axis abnormality in the width direction.

[0063] Furthermore, in the output signal of the photodetector 5, if the rectangular portion representing the laser reflected light shows a decrease in height h and a decrease in width t at one end T1, as indicated by the dashed line in Figure 5B(3), and the position remains almost unchanged, and the same is true for the rectangular portion at the other end T2, then a longitudinal optical axis anomaly is determined based on the amount of deviation from the reference position. If the amount of deviation exceeds the allowable range, it is determined that there is a longitudinal optical axis anomaly.

[0064] Furthermore, in the output signal of the photodetector 5, if the rectangular portion representing the laser reflected light has a lower height h and a smaller width t at one end T1, as shown by the dashed line in Figure 5C(2), and if the rectangular portion at the other end T2 also has a lower height h and a smaller width t, and is shifted in the direction of the one end T1, then an optical axis abnormality in the rotational direction is determined based on the amount of deviation from the reference position. If the amount of deviation exceeds the allowable range, it is determined that there is an optical axis abnormality in the rotational direction.

[0065] The display unit 7 consists of a display device such as an LED or a liquid crystal display and is connected to the signal processing unit 6. The display unit 7 can display the results of the determination sent from the signal processing unit 6, namely, optical axis abnormalities in the width direction, longitudinal direction, or rotation direction, and the amount of deviation of the optical axis CS of the photodetector 5.

[0066] Next, an example of a surface inspection method according to an embodiment will be described with reference to the drawings. As shown in Figure 6, the surface inspection method according to the embodiment includes the following steps: irradiation with laser light (step S1), reception of light by a light receiver (step S2), measurement of laser reflected light (steps S3 to S5), determination of the measurement result of the laser reflected light (step S6), determination and display of optical axis abnormality (step S7), and optical axis adjustment (step S8).

[0067] Furthermore, the surface inspection method includes the following steps: dimming (step S9), irradiation with inspection light (step S10), reception of light by a light receiver (step S11), defect determination (step S12), defective product handling (step S13), and determination of whether to continue surface inspection (step S14). Each step is performed in order.

[0068] The measurement of the laser reflected light (steps S3 to S5) includes measuring the position of the laser reflected light (step S3), measuring the width of the laser reflected light (step S4), and measuring the intensity of the laser reflected light (step S5).

[0069] Furthermore, the irradiation of laser light (step S1) in the surface inspection method by the surface inspection apparatus 10 according to the embodiment corresponds to the irradiation step of the surface inspection method according to the present invention, the reception of light by the light receiver (step S2) corresponds to the light reception step of the surface inspection method according to the present invention, and the measurement of laser reflected light (steps S3 to S5), the determination of the measurement result of the laser reflected light (step S6), and the determination and display of optical axis abnormality (step S7) correspond to the determination step of the surface inspection method according to the present invention.

[0070] In the laser beam irradiation (step S1), as shown in Figure 2(1), laser beams with a circular irradiation shape are irradiated from laser pointers 3 and 4 to the irradiation position on the surface of the pass roll 1, which is within the field of view SA of the light receiver 5 and outside the area of ​​the object to be inspected W, and is at approximately the same plane height as the surface of the object to be inspected W. The laser beam irradiation may occur while the object to be inspected W is being transported via the web by the surface inspection device 10 and surface inspection is being performed, or it may occur during the calibration of the light receiver 5 before surface inspection is performed.

[0071] In the light reception by the light receiver (step S2), the light receiver 5 receives the laser reflected light 3b and 4b that is irradiated from the laser pointers 3 and 4 and specularly reflected from the surface of the pass roll 1, as shown in Figure 2(1). The light receiver 5 converts the received laser reflected light 3b and 4b into electrical signals and transmits them as output signals to the signal processing unit 6.

[0072] The output signal is output as a voltage (V) signal at position x in the width direction of the path roll 1, perpendicular to the transport direction of web transport, as shown in Figure 2(2). This output signal includes signals for the position x, width t, and intensity h of the laser reflected light.

[0073] Next, the signal processing unit 6 performs a process to determine an abnormality in the optical axis of the photodetector 5 based on the output signal of the laser reflected light received by the photodetector 5. In the example shown in Figure 2(2), in the field of view SA of the photodetector 5, the voltage is highest in the portion of the laser reflected light reflected off the surface of the pass roll 1, followed by the portion of the surface of the pass roll 1 that is not laser reflected light, and the voltage is lowest in the region of the object to be inspected W.

[0074] In the measurement of the position of the laser reflected light (step S3), the distance δ from the side edges T1 and T2 of the field of view SA of the light receiver 5 to the rectangular portion is determined. In the measurement of the width of the laser reflected light (step S4), the width t of the rectangular portion is determined. In the measurement of the intensity of the laser reflected light (step S5), the height h of the rectangular portion is determined.

[0075] In step S6, a determination is made as to whether the measurement results of the laser reflected light (position x / width t / intensity h) from steps S3 to S5 are within the acceptable range. Here, the amount by which the signal-processed voltage deviates from the reference position, i.e., the amount of deviation of the optical axis CS of the photodetector 5, is calculated, and it is determined whether the calculated amount of deviation is within the acceptable range. The amount of deviation is calculated based on at least one of the following: the position of the laser reflected light, the width, and the intensity of the laser reflected light.

[0076] If the measurement result (deviation amount) of the laser reflected light in step S6 is determined to be within the acceptable range (YES in step S6), the optical axis of the light receiver 5 is considered to be normal, and the process proceeds to step S9 and beyond. At this time, the determination result that there is no optical axis abnormality of the light receiver 5 may be displayed on the display unit 7.

[0077] On the other hand, if the measurement result of the laser reflected light is determined to be outside the acceptable range (NO in step S6), the process proceeds to step S7, where the pattern of optical axis abnormality is determined and the determination is displayed on the display unit 7.

[0078] In the step S7, which involves determining and displaying optical axis anomalies, the measurement results from steps S3 to S5 are used to identify which of several optical axis anomaly patterns the anomaly falls under. Based on this identification result, the system determines whether the anomaly is in the width, length, or rotation direction of the optical axis, and / or calculates the amount of deviation, which is then displayed on the display unit 7.

[0079] Figure 7 is a table showing patterns of optical axis anomalies. For example, if the position measurement result in step S3 is abnormal, but the width measurement result in step S4 and the intensity measurement result in step S5 are both within the acceptable range, it is determined that there is a width-direction abnormality. If the position measurement result in step S3 is within the acceptable range, but the width measurement result in step S4 and the intensity measurement result in step S5 are both abnormal, it is determined that there is a longitudinal-direction abnormality. If the position measurement result in step S3, the width measurement result in step S4, and the intensity measurement result in step S5 are all abnormal, it is determined that there is a rotation-direction abnormality or some other optical axis abnormality.

[0080] In step S7, if an optical axis abnormality is detected and the optical axis abnormality of the light receiver 5 is displayed on the display unit 7, the process proceeds to step S8.

[0081] In optical axis adjustment (step S8), the optical axis CS of the photodetector 5 is adjusted to the normal position based on the optical axis abnormality pattern and the amount of deviation displayed by the display unit 7. The photodetector 5 is equipped with an optical axis adjustment device (not shown) that adjusts the optical axis CS. When the optical axis adjustment device determines that an optical axis abnormality has occurred, it automatically adjusts the optical axis CS of the photodetector 5 to the normal position based on the amount of deviation. Note that optical axis adjustment may also be performed by an operator.

[0082] Once the optical axis adjustment in step S8 is complete, the process proceeds to step S1, where laser light is irradiated again (step S1).

[0083] In the dimming process (step S9), the volume of the illumination, which is the inspection light irradiated onto the surface of the object to be inspected W by the light source 2, is adjusted so that the inspection light irradiated onto the surface of the object to be inspected W is set to the optimal brightness.

[0084] In the irradiation of the inspection light (step S10), as shown in Figures 1(1), 1(2), and 3, the surface of the object to be inspected W is irradiated with inspection light from the light source 2. The irradiation of the inspection light is performed within the same range as the field of view SA of the light receiver 5 shown in Figure 2(1).

[0085] In the light receiving by the light receiver (step S11), as shown in Figure 1(1), the light receiver 5 receives the inspection light that is irradiated from the light source 2 and reflected from the surface of the object to be inspected W. The light receiver 5 converts the received inspection light into an electrical signal and transmits it as an output signal to the signal processing unit 6. As shown in Figure 4, the output signal is output as a voltage (V) signal at a position in the width direction of the path roll 1 perpendicular to the transport direction of web transport.

[0086] Next, the signal processing unit 6 performs signal processing based on the inspection light signal received and output by the light receiver 5.

[0087] In defect detection (step S12), defects on the surface of the object W to be inspected, as shown in Figure 4, are detected. The signal processing unit 6 determines whether there is a portion of the voltage signal output from the photodetector 5 that exceeds the judgment criterion Th shown by the dashed line in Figure 4.

[0088] If there is no portion of the voltage signal output from the light receiver 5 that exceeds the judgment criterion Th, the inspected object W is deemed to have no defects (NO in step S12), and the process proceeds to the determination of whether to continue the surface inspection in step S14. On the other hand, if there is a portion of the voltage signal output from the light receiver 5 that exceeds the judgment criterion Th, the inspected object W is deemed to have defects on its surface (YES in step S12), and the process proceeds to the defective product processing in step S13.

[0089] In the defective product handling step (S13), an object W with a defect on its surface is treated as a defective product. The presence of a defect in the object W is fed back to the web production line control.

[0090] In the determination of whether to continue the surface inspection (step S14), it is determined whether further surface inspection is necessary for the object W being transported via the web. If it is determined that the surface inspection needs to be continued (YES in step S14), the process proceeds to irradiation with inspection light (step S10), and the surface inspection of the object W continues. On the other hand, if it is determined that the surface inspection does not need to be continued (NO in step S14), the surface inspection of the object W is terminated.

[0091] The following describes the effects of the surface inspection apparatus 10 and surface inspection method according to this embodiment.

[0092] (1) The surface inspection apparatus 10 according to the embodiment has a configuration in which inspection light is irradiated from a light source 2 onto the object to be inspected W being transported on a web, the inspection light that has passed through the object to be inspected W is received by a light receiver 5, and defects in the object to be inspected W are detected based on the output signal of the light receiver 5. Furthermore, the surface inspection apparatus 10 has a configuration in which laser light is irradiated from laser pointers 3 and 4 onto the surface of a pass roll 1 which is located within the field of view SA of the light receiver 5 but outside the area of ​​the object to be inspected W, the reflected laser light from the pass roll 1 is received by the light receiver 5, and the optical axis misalignment of the light receiver 5 with respect to the object to be inspected is determined based on the reflected laser light received by the light receiver 5.

[0093] This configuration allows the surface inspection device 10 to detect defects in the object W being inspected, accurately determine the optical axis misalignment of the photodetector 5 relative to the object W even while the object W is being inspected, and monitor fluctuations in the optical axis of the photodetector 5.

[0094] Furthermore, since the surface inspection device 10 irradiates the surface of the pass roll 1, which is positioned within the field of view SA of the light receiver 5 but outside the area of ​​the object to be inspected W, from laser pointers 3 and 4 respectively, it is possible to irradiate a stable surface with little variation with laser light. The surface inspection device 10 can also be used while the manufacturing line is in operation, and it can determine the optical axis misalignment of the light receiver 5 without interfering with so-called online inspection of the object to be inspected W, thus enabling early detection of optical axis misalignment of the light receiver 5.

[0095] Furthermore, since the laser reflected light from the stable surface of the pass roll 1 is received by the light receiver 5, the optical axis misalignment of the light receiver 5 relative to the object being inspected W can be accurately determined based on the stable laser reflected light, thereby ensuring the reliability of the calibration of the light receiver 5. Unlike conventional technology, when laser light is irradiated onto the surface of the object being inspected W, the amount of laser reflected light fluctuates depending on the surface condition of the object being inspected W, such as roughness, shape, and color, which makes accurate detection impossible.

[0096] (2) In the surface inspection apparatus 10 according to the embodiment, the amount of deviation of the optical axis CS of the photodetector 5 is calculated based on at least one of the position, width, and intensity of the laser reflected light received and output by the photodetector 5. This configuration provides the effect of determining the optical axis deviation of the photodetector 5 and identifying the pattern of the optical axis deviation.

[0097] (3) In the surface inspection apparatus 10 according to the embodiment, the position of the laser reflected light is measured with reference to the edge of the field of view SA of the light receiver 5. This configuration clarifies the reference for determining the optical axis misalignment of the light receiver 5, and since the position of the laser reflected light is within the field of view SA of the light receiver 5, it is possible to determine the position of the laser reflected light received by the light receiver 5.

[0098] (4) The surface inspection apparatus 10 according to the embodiment has laser pointers 3 and 4 that emit laser light, with at least one laser pointer 3 provided on one end side 1a in a direction perpendicular to the transport direction of the object to be inspected, and at least one laser pointer 4 provided on the other end side 1b in a direction perpendicular to the transport direction. With this configuration, when an abnormality occurs in which the optical axis CS of the light receiver 5 is misaligned in the direction in which the light receiver rotates around the optical axis CS, the misalignment of the optical axis CS of the light receiver 5 can be accurately determined.

[0099] (5) In the embodiment, the surface inspection apparatus 10 is configured such that the object to which the laser light is irradiated is a path roll 1 that transports the object to be inspected W via a web. With this configuration, the laser light is not irradiated onto the surface of the moving object to be inspected W, and the effect is obtained that the laser light is irradiated onto a component with a stable surface condition and less variation in the surface condition. Therefore, compared to the case in which the laser light is irradiated onto the object to be inspected W, a more stable laser reflected light is obtained, and the optical axis misalignment of the light receiver 5 relative to the object to be inspected W is accurately determined. As a result, the reliability of the calibration of the light receiver 5 is ensured.

[0100] (6) In the surface inspection apparatus 10 according to this embodiment, the surface of the pass roll 1 onto which the laser light is irradiated and the surface of the object to be inspected W onto which the inspection light is irradiated are positioned at the same plane height. With this configuration, the distance from the surface of the object to be irradiated onto which the laser light is irradiated to the receiver is the same as the distance from the surface of the object to be inspected onto which the inspection light is irradiated to the receiver. Therefore, the distance of the reflected light of the inspection light received by the receiver 5 and the distance of the reflected light of the laser light received by the receiver 5 are approximately the same, and the effect is obtained that the amount of deviation of the optical axis CS of the receiver 5 can be accurately determined. Furthermore, since the object to be inspected W is transported on the pass roll 1, the effect is obtained that the surface of the object to be inspected W onto which the inspection light is irradiated can be easily positioned at the same plane height as the surface of the pass roll 1 onto which the laser light is irradiated.

[0101] (7) The surface inspection method according to the embodiment includes an irradiation step (step S1) in which laser beams are irradiated from laser pointers 3 and 4 onto a path roll 1 positioned outside the area of ​​the object to be inspected, within the field of view SA of a light receiver 5 that receives the inspection light that has passed through the object to be inspected W, and outside the area of ​​the object to be inspected W; a light receiving step (step S2) in which the light receiver 5 receives the inspection light that has passed through the object to be inspected and the laser reflected light reflected by the path roll 1; and a determination step (steps S3 to S7) in which defects in the object to be inspected W are detected based on the inspection light received by the light receiver 5, and the optical axis misalignment of the light receiver 5 relative to the object to be inspected W is determined based on the laser reflected light.

[0102] This configuration allows the surface inspection method to detect defects in the object W being inspected, accurately determine the optical axis misalignment of the photodetector 5 relative to the object W even while the object W is being inspected, and monitor fluctuations in the optical axis of the photodetector 5.

[0103] Furthermore, the surface inspection method irradiates the surface of the pass roll 1, which is positioned within the field of view SA of the light receiver 5 but outside the area of ​​the object to be inspected W, with laser beams from laser pointers 3 and 4, respectively. This provides the advantage of irradiating a stable surface with minimal variation with laser beams. The surface inspection method can also be used while the manufacturing line is in operation, and it can determine the optical axis misalignment of the light receiver 5 without interfering with so-called online inspection of the object to be inspected W. Therefore, optical axis misalignment of the light receiver 5 can be detected at an early stage.

[0104] Furthermore, since the laser reflected light from the stable surface of the pass roll 1 is received by the light receiver 5, the optical axis misalignment of the light receiver 5 relative to the object being inspected W can be accurately determined based on the stable laser reflected light, thereby ensuring the reliability of the calibration of the light receiver 5. Unlike conventional technology, when laser light is irradiated onto the surface of the object being inspected W, the amount of laser reflected light fluctuates depending on the surface condition of the object being inspected W, such as roughness, shape, and color, which makes accurate detection impossible.

[0105] In the embodiment of the surface inspection apparatus 10, the inspection object W is transported by a pass roll 1, the surface of the inspection object W being transported on the pass roll 1 is inspected, and the apparatus is equipped with laser pointers 3 and 4 that irradiate the surface of the pass roll 1 with laser light. However, the surface inspection apparatus according to the present invention may be configured with a structure other than irradiating the surface of the pass roll 1 with laser light.

[0106] For example, the surface inspection apparatus according to the present invention may be configured as the surface inspection apparatus 10A according to Modification 1 or the surface inspection apparatus 10B according to Modification 2 below. Note that if the surface inspection apparatus 10A and surface inspection apparatus 10B have the same configuration as the surface inspection apparatus 10 according to the embodiment, the same reference numerals will be used and the description of their configuration will be omitted.

[0107] (Variation 1) The surface inspection apparatus 10A according to Modification 1 will be described below with reference to the drawings. The surface inspection device 10A according to Modification 1, as shown in Figures 8(1) and 8(2), includes a pass roll 1, a pass roll 1A having the same structure as pass roll 1, a light source (not shown), laser pointers 3 and 4, stationary members 11 and 12 as objects to be illuminated, a light receiver 5, a signal processing unit (not shown), and a display unit. Similar to the surface inspection device 10 according to the embodiment, the surface inspection device 10A has a configuration that detects defects on the surface of the object to be inspected W, determines the optical axis misalignment of the light receiver 5, and displays the results on the display unit.

[0108] In the surface inspection apparatus 10A according to Modification 1, the object to be inspected W is transported by pass rolls 1 and 1A. The light source 2 irradiates inspection light onto the object to be inspected W, which is located midway between the transport directions of pass rolls 1 and 1A and on a line L perpendicular to the transport direction. The inspection light is reflected from the surface of the object to be inspected W, i.e., passes through the object to be inspected W, and is received by the light receiver 5. The stationary member 11 is positioned in a direction perpendicular to the transport direction and at a distance from one end W1 of the object to be inspected W, and is fixed to a fixed member (not shown).

[0109] The stationary member 12, like the stationary member 11, is positioned in a direction perpendicular to the transport direction and spaced apart in the width direction of the object to be inspected W from the other end W2 of the object to be inspected W, and is fixed to a fixing member (not shown). The stationary member 11 and the stationary member 12 are positioned such that the line L connecting the center of the surface of the stationary member 11 and the center of the surface of the stationary member 12 overlap.

[0110] The surfaces of stationary member 11, stationary member 12, and the surface of the object W to be inspected are positioned at the same plane and height. Laser beams are shone from laser pointers 3 and 4 toward the surfaces of stationary member 11 and stationary member 12, and the reflected laser light is received by the light receiver 5.

[0111] In addition, the stationary members 11 and 12 of the surface inspection device 10A according to Modification 1 correspond to the object to be irradiated by the surface inspection device according to the present invention. This object to be irradiated may be a member other than the stationary members 11 and 12, for example, a reflective member with a smooth surface that reflects light.

[0112] This configuration allows the surface inspection device 10A according to Modified Example 1 to detect defects in the object to be inspected W, and to accurately determine the optical axis misalignment of the light receiver 5 relative to the object to be inspected W.

[0113] Furthermore, in the surface inspection device 10A, the surfaces of the stationary members 11 and 12 are positioned within the field of view of the light receiver but outside the area of ​​the object to be inspected W. Laser light is irradiated onto the surfaces of the stationary members 11 and 12 from the laser pointers 3 and 4, respectively, so that the laser light can be irradiated onto a stable surface with little variation. The surface inspection device 10A can also be used while the manufacturing line is in operation, and the optical axis misalignment of the light receiver 5 can be determined without interfering with so-called online inspection of the object to be inspected W, so the optical axis misalignment of the light receiver 5 can be detected early.

[0114] (Modification 2) The surface inspection apparatus 10B according to modified example 2 will be described below with reference to the drawings. As shown in Figures 9(1) and 9(2), the surface inspection device 10B according to Modification 2 includes a pass roll 1, a pass roll 1A with the same configuration as pass roll 1, a light source 2, laser pointers 3 and 4, stationary members 11 and 12 as objects to be illuminated, a light receiver 5, a signal processing unit, and a display unit. Similar to the surface inspection device 10 according to the embodiment, the surface inspection device 10B has a configuration that detects defects in the object to be inspected F, determines the optical axis misalignment of the light receiver 5, and displays the results on the display unit.

[0115] The object F being inspected is made of a transparent or translucent material such as a film and has the property of transmitting inspection light irradiated from the light source 2. Therefore, not only surface defects of the object F can be inspected, but also internal defects such as air bubbles and perforations.

[0116] In the surface inspection apparatus 10B according to Modification 2, the object to be inspected F is transported by pass rolls 1 and 1A. The light source 2 is positioned on the opposite side of the light receiver 5 from the transported object to be inspected F, and irradiates inspection light toward the back surface of the object to be inspected F. The inspection light is irradiated onto the object to be inspected F located midway along the transport direction of pass rolls 1 and 1A, on a line perpendicular to the transport direction. The inspection light passes through, i.e., through, the object to be inspected F and is received by the light receiver 5.

[0117] The stationary member 11 is positioned in a direction perpendicular to the transport direction of the object to be inspected F, and at a distance in the width direction of the object to be inspected F from one end F1 of the object to be inspected F, and is fixed to a fixing member (not shown). The stationary member 12 is positioned in a direction perpendicular to the transport direction of the object to be inspected F, and at a distance in the width direction of the object to be inspected F from the other end F2 of the object to be inspected F, similar to the stationary member 11, and is fixed to a fixing member (not shown). The stationary members 11 and 12 are positioned such that a straight line connecting the center of the surface of the stationary member 11 and the center of the surface of the stationary member 12 coincides with a line L perpendicular to the transport direction.

[0118] The surfaces of stationary member 11, stationary member 12, and the surface of the object to be inspected F are positioned at the same plane and height. Laser beams are shone from laser pointers 3 and 4 toward the surfaces of stationary member 11 and stationary member 12, and the reflected laser light is received by the light receiver 5. Stationary member 11 and stationary member 12 are located within the field of view of the light receiver but outside the area of ​​the object to be inspected F.

[0119] With this configuration, the surface inspection device 10B according to Modification 2 can obtain the same effects as the surface inspection device 10 according to the embodiment. Specifically, the surface inspection device 10B can detect defects in the object to be inspected F even if the object to be inspected F is a transparent or translucent web, and can accurately determine the optical axis misalignment of the light receiver 5 relative to the object to be inspected F.

[0120] Furthermore, in the surface inspection device 10B, the surfaces of the stationary members 11 and 12 are positioned within the field of view of the light receiver but outside the area of ​​the object to be inspected F. Laser light is irradiated onto the surfaces of the stationary members 11 and 12 from the laser pointers 3 and 4, respectively, so that the laser light can be irradiated onto a stable surface with little variation. The surface inspection device 10B can also be used while the manufacturing line is in operation, and the optical axis misalignment of the light receiver 5 can be determined without interfering with so-called online inspection of the object to be inspected F, so the optical axis misalignment of the light receiver 5 can be detected early.

[0121] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and various design modifications can be made without departing from the spirit of the invention as described in the claims. [Explanation of Symbols]

[0122] 1. 1A Pass Roll (Irradiation target object, stationary member, roller member) 1a, F1, W1 One end (one end in the direction perpendicular to the transport direction of the object being inspected) 1b, F2, W2 Other end (the other end in the direction perpendicular to the transport direction of the object being inspected) 2 light source 3, 4 Laser Pointer (Laser) 5 Receiver 6. Signal Processing Unit 7 Display section 10, 10A, 10B Surface Inspection Devices 11, 12 Stationary members 11a, 12a surface Optical axis of CS receiver F, W - Items to be inspected J Pass Roll axis LS laser pointer optical axis SA receiver field of view T1 One end (the edge of the receiver's field of view) T2 The other end (the edge of the receiver's field of view)

Claims

1. A surface inspection device that irradiates an object to be inspected, which is conveyed via a web using a roller member, with inspection light from a light source, receives the inspection light that has passed through the object to be inspected with a light receiver, and detects defects in the object to be inspected based on the output signal of the light receiver, Laser light is irradiated from the laser onto the end surface of the roller member, which is positioned within the field of view of the light receiver but outside the area of ​​the object to be inspected. The laser reflected light reflected from the end surface of the roller member is received by the light receiver. Based on the laser reflected light received by the light receiver, the misalignment of the light receiver's optical axis relative to the object being inspected is determined. A surface inspection apparatus characterized in that the laser is positioned so that the laser light emitted from the laser is specularly reflected from the end surface of the roller member and then received by the light receiver as laser reflected light.

2. The surface inspection apparatus according to claim 1, characterized in that it calculates the amount of optical axis misalignment based on at least one of the position, width, and intensity of the laser reflected light on the reflective surface of the roller member.

3. The surface inspection apparatus according to claim 2, characterized in that the position of the laser reflected light is measured with reference to the edge of the field of view area of ​​the light receiver.

4. The surface inspection apparatus according to any one of claims 1 to 3, characterized in that the lasers that irradiate the laser light are provided at least one on one end side in a direction perpendicular to the transport direction of the object to be inspected, and at least one on the other end side in a direction perpendicular to the transport direction.

5. The surface inspection apparatus according to any one of claims 1 to 4, characterized in that the surface of the roller member irradiated with the laser light and the surface of the object to be inspected irradiated with the inspection light are arranged at the same plane and height.

6. A light source for irradiating an object to be inspected that is transported on a web using a roller member, comprising an irradiation step of irradiating laser light from a laser onto the end surface of a roller member positioned within the field of view of a light receiver that receives the inspection light that has passed through the object to be inspected, and outside the area of ​​the object to be inspected, A light receiving step in which the light receiver receives the inspection light that has passed through the object to be inspected and the laser reflected light that has been specularly reflected from the end surface of the roller member, A determination step in which a defect in the object to be inspected is detected based on the inspection light received by the light receiver, and the optical axis misalignment of the light receiver relative to the object to be inspected is determined based on the laser reflected light, A surface inspection method characterized by including the following.

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