JP4496257B2 - Defect inspection equipment - Google Patents

Description

The present invention relates to a defect inspection apparatus. A sheet-like member made of a film, metal, or the like may cause defects such as depressions and bulges on the surface in the manufacturing process.
The present invention relates to a defect inspection apparatus used for detecting a defect of such a sheet-like member.

  Conventionally, a technique using light has been developed to detect surface defects to be inspected. In this technique, light is irradiated from the light source onto the surface of the inspection object, and the reflected light is measured by an imaging device such as a CCD. In such a configuration, the concavo-convex portion is photographed brighter or darker than the other portions. Therefore, if the photographed image is analyzed, the presence / absence of the concavo-convex portion can be detected based on the brightness of the image.

  However, when the unevenness or the like is small or when the unevenness is gentle, the difference in brightness between the flat portion and the uneven portion is small in the photographed image. In addition, the difference between brightness and darkness is further reduced due to the influence of scattered light from other than the uneven portion, so that it is difficult to detect the uneven portion.

Therefore, in order to increase the accuracy of detecting the presence or absence of unevenness or the like, a technique using a patterned light source capable of forming a striped pattern on an inspection target and a member having a pinhole has been developed (Patent Document 1). ).
In the technique of this patent document 1, since only the chief ray is selected by the pinhole and the patterned light source image is formed on the camera for the light irradiated to the inspection object, it becomes possible to emphasize the defect and specify the defective part. There is a statement to that effect.

  However, in the technique of Patent Document 1, since only the chief ray is selected by the pinhole, it is preferable in that the influence of scattered light from other than the uneven portion can be reduced, but the light is incident through the pinhole. The amount of light is very low. Then, since the technique of patent document 1 detects the defect only by the difference in brightness between the flat portion and the uneven portion, it is difficult to distinguish between the change in the light amount due to the unevenness and the change in the light amount due to the noise. .

JP-A-5-18905

  In view of the above circumstances, an object of the present invention is to provide a defect inspection apparatus that can accurately detect defects such as irregularities with a simple configuration.

Defect inspection apparatus of the first invention is an apparatus for inspecting defects such as unevenness of the inspection object, a light source for irradiating light to said object to be examined, the light reflected by the surface to be inspected An imaging device for receiving light, wherein the light source irradiates the object to be inspected with substantially sheet-like light, and the imaging means receives reflected light reflected by the object to be inspected. And a diaphragm member that is provided between the imaging device and the inspection target and has a slit that restricts the reflected light that enters the imaging device, and the slit of the diaphragm member has its axial direction Is formed so as to obliquely intersect with the reflected light of the substantially sheet-like light reflected on the surface of the object to be inspected.
The defect inspection apparatus according to a second aspect of the present invention is the defect inspection apparatus according to the first aspect, wherein the slit of the diaphragm member is inclined with respect to a plane including the intersection line between the substantially sheet-shaped light and the inspection target and the optical axis of the imaging apparatus. It is formed so that it may cross | intersect.
The defect inspection apparatus according to a third aspect of the present invention is the defect inspection apparatus according to the first aspect, wherein the substantially sheet-shaped light is formed so that a cross-sectional shape thereof is a saw blade, and the slit of the diaphragm member has an axial direction thereof, It is formed so as to be orthogonal to the width direction of the reflected light.
A defect inspection apparatus according to a fourth invention is the defect inspection apparatus according to the first invention, wherein the object to be inspected is a sheet-like member that is continuously conveyed, and the light source includes the substantially sheet-like light and the object to be inspected. It is characterized in that the substantially sheet-like light is irradiated to the object to be inspected so that the intersecting line intersects the conveyance direction of the object to be inspected.
According to a fifth aspect of the defect inspection apparatus, in the first, second, third, or fourth aspect, the light source includes a light emitter, and a light shielding member provided between the light emitter and the inspection target. Thus, the light shielding member is formed with a slit.

According to the first invention, the imaging device of the imaging means receives the light reflected by the surface of the inspection object through the slit of the diaphragm member. Therefore, the influence of scattered light reflected at a portion other than the position to be photographed can be reduced, so that the detection accuracy of defects such as irregularities can be increased. In addition, since a slit is used as a method for limiting the area to be photographed, a certain amount of light can be incident on the imaging apparatus while restricting the area to be photographed, and the influence of noise on detection accuracy can be achieved. Can be suppressed. In addition, since the slit is formed so that its axial direction obliquely intersects the width direction of the reflected light, the change in the amount of light is emphasized when the light is reflected by a defect such as unevenness of the object to be inspected. Therefore, the detection accuracy can be increased.
According to the second aspect of the invention, when light is reflected by a defect such as unevenness to be inspected, the change in the amount of light is emphasized, so that detection accuracy can be increased even with small unevenness.
According to the third aspect of the present invention, pattern distortion occurs when a sawtooth pattern is reflected by a defect such as irregularities, and this pattern distortion is detected as a signal in which the intensity of light intensity is continuous. For this reason, since the change of the detected signal strength is emphasized, it is possible to accurately detect even if the object to be inspected is a large bulge or dent.
According to the fourth invention, even if the object to be inspected is a sheet-like member that is continuously conveyed, the portion where the intersection of the substantially sheet-shaped light and the object to be inspected is continuously inspected. be able to.
According to the fifth aspect of the invention, since the light is substantially sheet-shaped by the slit of the light shielding member, the light source can be configured simply. In addition, since the thickness of the substantially sheet-like light can be adjusted simply by changing the slit width of the light shielding member, the adjustment of the region irradiated with light, that is, the inspection region can be simplified.

Next, an embodiment of the present invention will be described with reference to the drawings.
1A and 1B are explanatory views of a defect inspection apparatus 1 according to an embodiment of the present invention, in which FIG. 1A is a schematic perspective view, and FIG. 1B is a schematic side view. 2A is an explanatory diagram of the light shielding member 12 of the light source 10, and FIG. 2B is a diagram showing the positional relationship between the diaphragm member 23 of the photographing means 20, the imaging element 21s of the line sensor 21, and the plane CF. . 3A is a diagram showing the positional relationship among the line sensor 21, the lens 22, the diaphragm member 23, and the inspection target S, and FIG. 3B is an image RI of the reflected light on the virtual plane IS, the slit region SA, and It is the schematic explanatory drawing which showed the relationship of plane CF.
In each drawing, relative sizes are described with dimensions different from actual dimensions in order to make it easy to understand the arrangement and the like of each device.

  As shown in FIG. 1, the defect inspection apparatus 1 of the present embodiment includes a light source 10 that irradiates light to an inspection target S such as a sheet-like member made of a film or metal, and the surface of the inspection target S. And a photographing means 20 for receiving the reflected light reflected by.

First, the light source 10 will be described.
As shown in FIG. 1B, the light source 10 includes a light emitter 11 such as a fluorescent lamp or an LED that emits light toward the surface of the inspection target S.
A light shielding member 12 formed of a material that does not transmit the light emitted from the light emitter 11 is provided between the light emitter 11 and the inspection target S. The light shielding member 12 is provided with slits 12s, and is arranged so that the axial direction 12a of the slits 12s is parallel to the surface of the inspection object S (FIG. 2A).

For this reason, only the light that has passed through the slit 12 s of the light shielding member 12 among the light emitted from the light emitter 11 of the light source 10 is irradiated on the surface of the inspection object S. The light that has passed through the slit 12s of the light shielding member 12 becomes substantially sheet-like light whose thickness is approximately the same as the width w of the slit 12s. That is, the light source 10 can irradiate the inspection object S with the light emitted from the light emitter 11 as substantially sheet-like light.
Hereinafter, the substantially sheet-like light irradiated from the light source 10 onto the surface of the inspection object S is simply referred to as irradiation light.

If the light source 10 is configured as described above, the substantially sheet-shaped irradiation light can be formed with a simple configuration, so that the light source 10 itself can have a simple configuration. In addition, since the thickness of the irradiation light can be adjusted simply by changing the width w of the slit 12s of the light shielding member 12, the region to be irradiated with the irradiation light (the portion of the intersection line CL in FIG. 1) in the inspection target S, that is, The width of the inspection area of the inspection object S can be easily adjusted.
The light source 10 is not limited to the above-described configuration, and is not particularly limited as long as it can irradiate the surface of the inspection target S with a substantially sheet-like light.
Further, in FIG. 1, the light source 10 is disposed so as to irradiate the irradiation light obliquely with respect to the surface of the inspection target S. However, the angle of the light irradiation is not particularly limited, and the surface of the inspection target S is not limited. An optimal angle can be set according to the material, the defect to be detected, and the like. For example, if the object S to be inspected is a soft film, for example, the angle at which light is irradiated is shallow, that is, the smaller the angle between the irradiated light and the object S to be inspected, the higher the defect detection accuracy. .

Next, the photographing means 20 will be described.
As shown in FIG. 1, the imaging means 20 includes a line sensor 21 that receives the reflected light reflected by the object S to be inspected, a lens 22 that collects the reflected light and enters the line sensor 21, and a line sensor. And a diaphragm member 23 provided between the lens 21 and the lens 22.

As shown in FIG. 2, the line sensor 21 has a plurality of image sensors 21s arranged in a line. The line sensor 21 is arranged such that a plurality of imaging elements 21s are parallel to the surface of the inspection object S. In other words, the line sensor 21 is arranged such that the plurality of imaging elements 21s are arranged in parallel with the axial direction 12a of the slit 12s of the light shielding member 12.
In addition, the line sensor 21 is arranged so that the optical axis LA of each imaging element 21s passes through the intersection line CL of the irradiation light and the inspection target S (FIG. 1A).
The optical axis LA of each image sensor 21s means a line connecting each image sensor 21s and the center of the lens 22, and each image sensor 21s images the intersection of the optical axis LA and the inspection object S. (FIG. 3A).

The diaphragm member 23 limits the reflected light that enters the line sensor 21. The diaphragm member 23 is formed of a material that does not transmit reflected light, and is provided with a slit 23s that is a through hole formed in a substantially rectangular shape.
The diaphragm member 23 is disposed so that the axial direction 23a of the slit 23s obliquely intersects the direction in which the plurality of imaging elements 21s in the line sensor 21 are arranged (FIG. 2B). That is, the diaphragm member 23 has a plane in which the axial direction 23a of the slit 23s includes both the optical axis LA of the plurality of imaging elements 21s in the line sensor 21 and the intersection line CL of the irradiation light and the surface of the inspection target S. It is formed so as to cross the CF diagonally.

Since the configuration is as described above, the plurality of imaging elements 21 s in the line sensor 21 receive only the reflected light that passes through the slit 23 s of the diaphragm member 23 among the reflected light reflected from the surface of the inspection target S from the light source 10. Will do.
That is, as shown in FIG. 1B, when a virtual plane IS orthogonal to the plane CF is set between the object to be inspected S and the line sensor 21, each imaging element 21s substantially has each imaging. Reflected light from the vicinity of the region where the optical axis LA of the element 21s intersects the surface of the object S to be inspected, and the slits 23s of the diaphragm member 23 are placed on the virtual plane IS along the optical axis LA of each imaging element 21s. The reflected light that passes through the projected area (hereinafter referred to as slit area SA) is received (FIG. 3B).
Then, although the amount of light entering each imaging element 21s is smaller than when no diaphragm member 23 is provided, the slit 23s of the diaphragm member 23 is substantially rectangular, so compared with the case where a pinhole is provided, A large amount of light entering each imaging element 21s can be secured.
Therefore, since the intensity of the signal output from each imaging element 21s due to the incident light amount can be increased, it is possible to suppress the influence of various noises or the like on the detection accuracy.

  In addition, the slit 23s of the diaphragm member 23 is formed so as to obliquely intersect the plane CF including the intersection line CL with the optical axis of each imaging element 21s. When the light is reflected by this defect, the change in the amount of reflected light entering each imaging element 21s is emphasized. That is, in the inspection target S, it becomes easy to detect a change in the amount of light incident on each imaging element 21s when the irradiation light is reflected by a defect portion such as an unevenness, and the accuracy of detecting a defect such as an unevenness is increased. The reason for this will be described later.

Next, an operation for detecting a defect by the defect inspection apparatus 1 of the present embodiment will be described.
4A and 4B are explanatory views when the surface of the inspection object S is flat, FIG. 4A is a schematic explanatory view showing the relationship between the irradiation light and the reflected light, and FIG. 4B is a reflection on the virtual plane IS. It is the schematic explanatory drawing which showed the relationship between light image RI and slit area | region SA, (C) is the figure which showed the change by the position of the detected light quantity. 5A and 5B are explanatory diagrams in the case where the surface of the inspection object S has a bulge P, where FIG. 5A is a schematic explanatory diagram showing the relationship between irradiation light and reflected light, and FIG. 5B is on the virtual plane IS. FIG. 6 is a schematic explanatory view showing a relationship between an image RI of reflected light and a slit area SA, and FIG. 8C is a view showing a change according to a position of a detected light amount.
In FIG. 4C and FIG. 5C, the vertical axis indicates the amount of light detected by each image sensor 21s, and the horizontal axis indicates the position at which each image sensor 21s detects the amount of light. Further, an area (hatched portion) where the reflected light image RI and the slit area SA in FIGS. 4B and 5B intersect is indicated by an area CA below.

First, as shown in FIG. 4A, when the surface of the inspection target S is flat, almost the same reflection is exhibited at any position on the surface of the inspection target S.
For this reason, as shown in FIG. 4B, the image RI of the reflected light on the virtual plane IS is similar to the cross section of the irradiated light, that is, similar to the shape of the slit 12s of the light shielding member 12 in the light source 10. Become. In this case, on the virtual plane IS, the area of the area CA (hatched part) where the reflected image RI and the slit area SA intersect is the same at any position.
Then, as shown in FIG. 4C, the amount of light incident on each image sensor 21s is almost the same regardless of the position where each image sensor 21s captures an image. Since the strength is almost the same, it can be confirmed that the surface of the inspection object S has no defects.

On the other hand, as shown in FIG. 5 (A), when the bulge P exists in the inspection object S, the reflected light reflected by the portion of the bulge P reflects the reflected light reflected by the flat portion. The state changes, and the image RI of the reflected light on the virtual plane IS is in a state in which the image of the portion of the bulge P is distorted (FIG. 5B).
Then, the slit 23s of the diaphragm member 23 is formed so as to obliquely intersect the plane CF including the optical axis of each imaging element 21s and the intersection line CL (FIG. 3B), and therefore on the virtual plane IS. , The area CA of the reflected light image RI and the slit area SA varies depending on the position, and is different between the bulge P part (A to C area) and the flat part (D area). . Moreover, the area of the area CA is not constant even in the bulge P, and in the case of FIG. 5B, the area of the area CA increases in the order of A, B, and C. In addition, in the portion B, that is, in the vicinity of the apex of the bulge P portion, the area of the region CA is almost the same as the area CA in the flat portion.
For this reason, the amount of light incident on each image sensor 21s photographed in the vicinity of the portion B is substantially the same as the amount of light incident on each image sensor 21s photographed on the flat portion (D portion). The amount of light that enters the image sensor 21s that captures the vicinity of the portion of the image becomes smaller than the amount of light that enters the image sensor 21s that captures the flat portion. On the contrary, the amount of light incident on the image pickup device 21s that captures the vicinity of the portion C is larger than the amount of light incident on the image pickup device 21s that captures the flat portion.

Therefore, in the defect inspection apparatus 1 according to the present embodiment, even when one bulge P portion is photographed, the amount of light incident on each imaging element 21s is larger than that of a flat portion at the apex of the bulge P portion. A waveform in which a portion with a small amount of light and a portion with a large amount of light are continuous (FIG. 5C). That is, a waveform having one peak and one valley for each bulge P is formed.
Then, since the defect inspection apparatus 1 of this embodiment can determine the presence or absence of the bulge P including the waveform of the detected signal, the detection accuracy of the bulge P can be increased.

In FIG. 6, the photograph which image | photographed the sheet | seat in which the swelling was formed with the defect inspection apparatus 1 of this embodiment is shown. In this photograph, the defect inspection apparatus 1 of this embodiment is arranged and photographed so that the intersection line CL is formed along the vertical direction. In the photograph of FIG. It can be confirmed that there are bright areas and dark areas along the vertical direction. That is, the bright area corresponds to the area C in FIG. 5, and the dark area corresponds to the area A in FIG.
From the above results, it can be confirmed that the defect inspection apparatus 1 of the present embodiment is effective for detecting surface defects in a sheet or the like.

  The angle θ formed by the slit 23s of the diaphragm member 23 with respect to the plane CF is not limited. However, if the formed angle θ is 30 to 45 degrees, light is reflected by a defect such as irregularities of the object S to be inspected. Since the change in the amount of light is more emphasized, the detection accuracy can be increased.

  In the above example, the case where the bulge P is present on the surface of the inspection target S has been described as an example, but it goes without saying that the defect inspection apparatus 1 of the present embodiment can be applied to detection even if it is a dent. .

Further, the relative positions of the slit 23s of the diaphragm member 23 and the light source 10 do not necessarily have the above-described configuration, and the axial direction 23a of the slit 23s is oblique to the reflected light reflected from the surface of the object S to be inspected. If the intersection, that is, the axial direction 23a of the slit 23s intersects the surface of the reflected light, the detection accuracy of the bulge P, the dent, etc. can be improved.
In particular, when the bulge P or the dent is large, that is, when the area of one bulge P or the like is large, if the relative positions of the slit 23s of the diaphragm member 23 and the light source 10 are configured as follows, The detection accuracy can be improved, and the bulge P and the dent can be accurately detected.

As shown in FIG. 7A, the light shielding member 12 of the light source 10 is formed so that the gap between the slits 12 s changes in a sawtooth shape along the width direction of the light shielding member 12. Then, since the cross-sectional shape of the substantially sheet-shaped irradiation light irradiated to the inspection object S is a saw blade, the reflected image RI formed on the virtual plane IS is also a saw blade along the width direction. It becomes an image that changes.
On the other hand, the slit 23s of the diaphragm member 23 is disposed so that its axial direction 23a is orthogonal (θ = 90 °) to the direction in which the plurality of image pickup devices 21s in the line sensor 21 are arranged (FIG. 7B). )).
With this configuration, as shown in FIG. 8A, the reflected light image RI formed on the virtual plane IS becomes an image that changes in a saw-tooth shape along the width direction. , The reflected light image RI and the slit area SA cross each other obliquely. That is, the axial direction 23a of the slit 23s crosses the reflected light obliquely.

Then, when the surface of the inspection target S is flat, since almost the same reflection is shown at any position on the surface of the inspection target S, the image RI of the reflected light on the virtual plane IS is irradiated light. Therefore, the reflected light image RI and the slit area SA intersect on the virtual plane IS as in the case where the slit 23s of the diaphragm member 23 and the light source 10 are configured as shown in FIG. The area of the area CA (hatched portion) is the same at any position.
Therefore, regardless of the position at which each image sensor 21s shoots, the amount of light incident on each image sensor 21s is substantially the same, and the intensity of the signal output by each image sensor 21s is also approximately the same. It can be confirmed that the surface of this has no defects.

On the other hand, when there is a bulge in the inspection target S, the reflected state of the reflected light reflected by the bulge portion changes with respect to the reflected light reflected by the flat portion, and the reflected light on the virtual plane IS is changed. The image RI of the reflected light is in a state where the image of the bulge portion is distorted.
Then, on the imaginary plane IS, the bulge portion is formed with a flat portion and a portion having a different area of the area CA, so that it can be confirmed that the bulge exists (see FIG. 8B).

In addition, in the bulge portion, the area CA changes continuously and in small increments corresponding to an image that changes in a sawtooth shape. Then, the signal detected when the slit 23s of the diaphragm member 23 and the light source 10 are configured as shown in FIG. 2 has one unit waveform (a waveform having one peak and one valley) for one bulge. The signal detected when the slit 23s of the diaphragm member 23 and the light source 10 are configured as shown in FIG. 7 is continuous with a plurality of unit waveforms for one bulge. It becomes a signal with a part.
That is, the signal detected by the defect inspection apparatus 1 is a continuous signal of strength and weakness, and the change in the signal strength is emphasized. Therefore, the area of one bulge P or dent formed on the surface of the inspection target S is Even if it is wide, it can be accurately detected.

  As shown in FIG. 9, when the inspection target S is a sheet-like member that is continuously conveyed in, for example, a production line or an inspection line, the light source 10 moves to the surface of the inspection target S. If the irradiation light is irradiated to the inspection target S so that the intersection line CL between the incident irradiation light and the inspection target S intersects the transport direction of the inspection target S, the inspection target S is continuously provided. Can be detected.

In the above example, the case where the line sensor is adopted as the photographing device of the photographing means 20 has been described. However, the photographing device is not limited to the line sensor, and a CCD area camera, an imaging device using other lenses, or the like is also adopted. can do.
In the above example, the case where the diaphragm member 23 is disposed between the lens 22 and the photographing apparatus 21 in the photographing unit 20 is described. However, the diaphragm member 23 is disposed between the lens 22 and the object S to be inspected. In this case, the same effect can be obtained.

  The defect inspection apparatus of the present invention is an apparatus suitable for detecting depressions and bulges in a sheet-like member made of a film or metal.

It is a schematic explanatory drawing of the defect inspection apparatus 1 concerning one Embodiment of this invention, (A) is a perspective view, (B) is a side view. (A) is a single explanatory diagram of the light shielding member 12 of the light source 10, and (B) is a diagram showing the positional relationship between the diaphragm member 23 of the photographing means 20, the imaging element 21s of the line sensor 21, and the plane CF. (A) is a diagram showing a positional relationship among the line sensor 21, the lens 22, the diaphragm member 23, and the inspection target S, and (B) is an image RI of reflected light, a slit region SA, and a plane CF on the virtual plane IS. It is the schematic explanatory drawing which showed this relationship. It is explanatory drawing when the surface of to-be-inspected object S is flat, (A) is the schematic explanatory drawing which showed the relationship between irradiated light and reflected light, (B) is the image of the reflected light on virtual plane IS. It is the schematic explanatory drawing which showed the relationship between RI and slit area | region SA, (C) is the figure which showed the change by the position of the detected light quantity. It is explanatory drawing in case there exists bulge P on the surface of to-be-inspected object S, (A) is the schematic explanatory drawing which showed the relationship between irradiated light and reflected light, (B) is reflected light on virtual plane IS. It is the schematic explanatory drawing which showed the relationship between image RI of this, and slit area | region SA, (C) is the figure which showed the change by the position of the light quantity detected. It is the photograph which image | photographed the sheet | seat in which the swelling was formed by the defect inspection apparatus 1 of this embodiment. It is a schematic explanatory drawing of the defect inspection apparatus 1 of other embodiment, Comprising: (A) is single-piece explanatory drawing of the light shielding member 12 of the light source 10, (B) is the aperture member 23 of the imaging means 20, and the line sensor 21 It is a figure showing the positional relationship of the image pick-up element 21s and plane CF. FIG. 8 is a schematic explanatory view showing the relationship between the image RI of reflected light on the virtual plane IS and the slit area SA in the defect inspection apparatus 1 of FIG. 7, and (A) shows a case where the surface of the inspection target S is flat. It is explanatory drawing, (B) is a partial expansion explanatory view in case the swelling P exists on the surface of the to-be-inspected object S. FIG. It is a schematic explanatory drawing of the defect inspection apparatus 1 in the state which is inspecting the to-be-inspected object S conveyed continuously, (A) is a perspective view, (B) is a side view.

DESCRIPTION OF SYMBOLS 1 Defect inspection apparatus 10 Light source 11 Light-emitting body 12 Light-shielding member 12s Slit 20 Image | photographing means 21 Line sensor 21s Image sensor 23 Diaphragm member 23s Slit S Inspection object CL Irradiation light and surface of inspection object S intersection CF Image sensor light Plane including axis and intersection line CL

Claims (5)

An apparatus for inspecting defects such as irregularities to be inspected,
A light source for irradiating light to said object to be inspected,
An imaging means for receiving the light reflected by the surface of the object to be inspected,
The light source is
Irradiating the object to be inspected with substantially sheet-shaped light,
The photographing means includes
An imaging device that receives reflected light reflected by the object to be inspected;
A diaphragm member provided between the imaging device and the object to be inspected, and having a slit that restricts the reflected light entering the imaging device;
The slit of the diaphragm member is
A defect inspection apparatus, wherein the axial direction is formed so as to obliquely intersect the reflected light of the substantially sheet-like light reflected by the surface of the inspection object. The slit of the diaphragm member is
The defect inspection according to claim 1, wherein the defect inspection is formed so as to obliquely intersect a plane including an intersection line between the substantially sheet-shaped light and the inspection target and an optical axis of the imaging device. apparatus. The substantially sheet-like light is
The cross-sectional shape is formed to be a saw blade,
The slit of the diaphragm member is
The defect inspection apparatus according to claim 1, wherein the axial direction is formed so as to be orthogonal to the width direction of the reflected light. The inspection object is a sheet-like member that is continuously conveyed,
The light source is
The substantially sheet-shaped light is irradiated to the object to be inspected so that an intersection line between the substantially sheet-shaped light and the object to be inspected intersects the transport direction of the object to be inspected. The defect inspection apparatus according to claim 1, wherein: The light source is
A light emitter;
A light shielding member provided between the light emitter and the object to be inspected,
The defect inspection apparatus according to claim 1, wherein a slit is formed in the light shielding member.