JP2010101692A - Method and device for inspecting sheetlike article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique that facilitates performing transmitted light type inspection only by simple equipment without requiring complicated prior adjustment or treatment. <P>SOLUTION: The surface of a web W having light perviousness being an inspection target is irradiated with white light from a direction of an angle θ using a white-light source 22. Further, the same surface of the web W is irradiated with infrared rays from an infrared ray source 24 separately from white light. A line sensor 18 is arranged under the web W to take a transmitted light image. Since the line sensor 18 is installed at a position not opposed to the irradiation direction by the white-light source 22 and capable of receiving infrared rays as transmitted light, the brightness of the image is enhanced by the transmitted infrared rays. If there is an air bubble B in the web W, white light is variously diffracted or scattered to appear in the image as a dark region. Further, the foreign matter H mixed in the web W cuts off infrared rays to appear as the dark region. In either case, a sufficient contrast can be obtained by making the whole of the image bright. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inspection method and an inspection apparatus for a sheet-like article that inspects, for example, the presence or absence of bubbles or mixed foreign matters generated inside the sheet-like article having optical transparency.

  Conventionally, for example, when manufacturing a transparent or translucent light-transmitting film sheet or the like, there is known a method for inspecting a bubble defect, a foreign substance defect, a pinhole defect, or the like generated therein by image processing. (For example, refer to Patent Document 1). In this prior art, a light source is arranged on one side of a film sheet to be conveyed, a linear array camera is arranged on the other side, and imaging using transmitted light is performed and output from the linear array camera. A dark part signal in the video signal is detected as a defect.

In particular, in the above prior art, a polarizing plate is disposed between the film sheet and the light source, and between the film sheet and the linear array camera, and the polarization angle of each polarizing plate is within ± 20 degrees. Is set. In this case, since the perpendicularly polarized light component due to the molecular orientation unevenness and distortion of the film sheet is removed by the polarizing plate, it is possible to eliminate the brightening action at the time of imaging by the perpendicularly polarized light component. In addition, since the polarization direction of distortion inside and around the bubble defect or foreign object defect is rotated with respect to the linear polarization direction from the light source, and away from the polarization direction of the polarizing plate facing the linear array camera, It is possible to prevent the polarized light from the defective part from entering the linear array camera. For this reason, according to the above-described prior art, it is considered that not only mixed foreign substances but also defective portions such as bubbles can be manifested as dark portion signals in the video signal.
JP-A-11-30591

  However, in the above-described prior art method, if the deviation angle (± 20 degrees or less) between the two polarizing plates is not managed very severely, the polarization direction component from the defective portion immediately increases and passes, The image is captured by the linear array camera as a bright luminescent spot. For this reason, it is not possible to obtain an accurate inspection result simply by installing two polarizing plates, and it is not possible to proceed to an effective inspection without going through a procedure for strictly adjusting the deviation angle between the polarizing plates. There is a problem.

  In general, when defect inspection is performed by transmitting light through an inspection object, the entire image (video signal) becomes darker than reflected light, so that the contrast of the dark part signal is insufficient. For this reason, in the above-described prior art, it is basically not easy to extract a dark part signal from a video signal. If an attempt is made to extract a dark part signal from the video signal, it is necessary to use a complicated algorithm, and the processing is performed accordingly. There is a problem of increasing complexity.

  Furthermore, how much dark part signal becomes apparent as the defect part changes depending on the thickness, material, color, etc. of the film sheet to be inspected. Almost no contrast can be obtained, and in this case, an accurate inspection result cannot be expected.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a technique that can be easily inspected with simple equipment without requiring complicated prior adjustment and processing.

  In order to solve the above problems, the present invention employs the following solutions.

First, the present invention is an inspection method having the following steps.
(1) Irradiation process In this process, while irradiating the first inspection light from the first light source toward one surface of the light-transmitting sheet-like article that is the inspection object, the same one surface A second inspection light having a wavelength region different from that of the first inspection light is emitted from the second light source. In addition, when a sheet-like article has a certain length, it is preferable that the range which irradiates inspection light from the 1st light source and the 2nd light source, respectively overlaps.

(2) Imaging step In this step, the sheet-shaped article is placed at a position where the second inspection light can be received as transmitted light while having a predetermined angle without facing the irradiation direction of the first inspection light across the sheet-like article. The other surface of the sheet-like article is imaged using the imaged device. In addition, the angle between the direction in which the imaging device is installed on the other surface of the sheet-like article and the irradiation direction of the first inspection light can be appropriately set within a certain range, and the adjustment is so strict. Is not necessary.

(3) Inspection process And this process inspects the internal state of a sheet-like article from the brightness difference in the image obtained by the imaging process of said (2). The internal state to be inspected here includes, for example, the presence / absence of a non-uniform material density (for example, a gelled portion inside) in addition to the presence / absence of bubbles and mixed foreign matters as described above.

  As described above, in the inspection method of the present invention, the irradiation direction of the first inspection light and the light receiving direction of the imaging device do not face each other, and a predetermined angle (displacement) is provided between them. Therefore, for the first inspection light, the amount of light received at the time of imaging is basically the amount that refracts the inside of the sheet-like article and reaches the imaging device. On the other hand, the second inspection light is basically transmitted through the sheet-like article because the imaging device is provided at a position where it can be sufficiently received as transmitted light (a position at which refraction is not expected). Most of the light (including the amount refracted inside) becomes the amount of light received by the imaging device. In this way, in the present invention, since the sheet-like article as the inspection object is illuminated using two types of inspection light (light source), the amount of light during imaging is increased and the brightness of the entire image is improved. Can do.

  Further, the first inspection light and the second inspection light have the following effects due to the difference between the main wavelength regions. That is, for the first inspection light, if there are defects such as bubbles and cavities inside the sheet-like article, various refractions and scattering occur due to changes in the internal film structure. The amount of light reaching up to decreases. Since the decrease in the amount of received light at this time produces a clear dark region in the image, the presence or absence of a defect can be inspected satisfactorily from the difference in brightness.

  On the other hand, for the second inspection light, for example, by setting a main wavelength region longer than that of the first inspection light, a sheet-like article does not cause much refraction / scattering at a defective portion such as a bubble or a cavity. The inside of the can be permeated. Therefore, the second inspection light improves the brightness of the entire captured image regardless of the presence or absence of bubbles, cavities, and the like inside the sheet-like article, thereby exhibiting a function of increasing the contrast of the defective portion. However, since the second inspection light is shielded within the range when foreign matter is mixed inside, the reduced amount of transmitted light at this time forms a dark region in the image. Accordingly, it is possible to surely inspect the presence or absence of foreign matter mixed in from the difference in brightness in the image.

  More preferably, in the irradiation step (1), white light mainly used in the visible light wavelength region is used as the first inspection light, and mainly included in the infrared wavelength region as the second inspection light. Infrared light shall be used. As a result, the first inspection light is refracted or scattered with respect to the change in the film structure existing inside the sheet-like article to reduce the amount of light received by the imaging device, while the second inspection light is sheet-like. It is assumed that the amount of light received by the imaging device is reduced by reducing the transmittance due to foreign matter existing inside the article.

  In this way, when transmissive illumination is performed using two types of inspection light, white light and infrared light, white light is effective for defect inspection related to changes in internal film structures such as bubbles and cavities. Infrared light is effective for inspection of mixed foreign matters while improving the brightness of the image by transmitting the entire infrared light. Thus, by making good use of the properties of each light, it is possible to improve the contrast of the dark region representing the defective portion in the image and increase the inspection accuracy.

  Secondly, the present invention is a sheet-shaped article inspection apparatus suitable for executing the inspection method described above. That is, the inspection apparatus has a first light source that irradiates the first inspection light toward one surface of the light-transmitting sheet-like article, and one surface of the same sheet-like article as the first light source. A second light source that irradiates a second inspection light having a wavelength region different from that of the first inspection light, and a predetermined angle without facing the irradiation direction of the first inspection light across the sheet-like article And an imaging device that images the other surface of the sheet-like article at the position where the second inspection light can be received as transmitted light, and an image obtained by imaging with the imaging device And an inspection unit for inspecting the internal state of the sheet-like article from the difference in brightness.

  In addition, about the inspection apparatus, you may provide the conveyance mechanism which conveys the sheet-like article which is a test subject along a predetermined | prescribed conveyance path | route. In this case, the imaging device is a line sensor that continuously images the other surface of the sheet-like article along the main scanning line orthogonal to the conveyance direction as the sheet-like article is conveyed, and generates an image used for inspection. There may be.

  With such a configuration, for example, a long sheet-shaped article can be imaged in the main scanning direction with a line sensor while being conveyed in one direction, and inspection can be performed for each image accumulated for a certain conveyance distance. .

  In the inspection apparatus of the present invention, the first light source is a white light source that emits white light mainly included in the wavelength region of visible light as the first inspection light, and the second light source is the second inspection light. An infrared light source that emits infrared light mainly included in the infrared wavelength region as light is preferable.

  In this case, as described above, the brightness of the entire image is improved by using two different light sources, and a dark region is formed in the image by refraction or scattering of white light for defects such as bubbles and cavities. In addition, with respect to the foreign matter mixed in, a dark region can be formed in the image by reducing the amount of transmitted infrared light.

  Furthermore, the inspection apparatus of the present invention reflects the second inspection light emitted by the second light source, and an angle adjustment mechanism that can adjust the irradiation angle of the first inspection light with respect to one surface of the sheet-like article. You may provide the light reflection surface irradiated on one side of a sheet-like article.

  With such a configuration, the optimal setting for appropriately forming the first inspection light irradiation angle in accordance with the thickness, material, color, etc. of the sheet-like article and forming the defective portion as a dark region in the image. Can be easily obtained. Further, by reflecting the light emitted from the second light source and transmitting it through the sheet-like article, the second inspection light is diffused to some extent, and the center position of the second light source is emphasized extremely brightly in the image. (Imaged as a light spot) can be reduced. As a result, it is possible to prevent the dark area from being erased in the image and to eliminate the detection omission of the defective portion.

  According to the inspection method and the inspection apparatus of the present invention, the sheet is obtained from the difference in brightness in the obtained image only by imaging the other surface while irradiating two types of inspection light toward one surface of the sheet-like article. The internal state of the shaped article can be easily inspected.

  Moreover, the inspection apparatus of the present invention has only two types of light sources and an imaging device as a basic configuration, and there is no need to use a polarizing plate. Therefore, the inspection can be easily performed without requiring a complicated complicated adjustment procedure.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically illustrating a configuration example of an inspection apparatus 10 according to an embodiment. The inspection method for the sheet-like article can be realized by using this inspection apparatus 10. Here, first, a configuration row of the inspection apparatus 10 will be described.

  The inspection apparatus 10 according to the present embodiment performs, for example, a transmission light type inspection while using a long web W wound around a roll as an inspection target and conveying the web W in the longitudinal direction. The web W is a light-transmitting sheet-like article (for example, a cloudy translucent film or the like). The inspection apparatus 10 of this embodiment is suitable for inspection when the haze value (cloudiness value) of the web W is in the range of 50 to 70 Th.

  The inspection apparatus 10 includes a transport mechanism 12 for the web W, and the transport mechanism 12 includes a plurality of transport rollers 12a. These transport rollers 12a are arranged at intervals in the transport direction of the web W, and each transport roller 12a is provided with a pair of pinch rollers 12b. The long web W fed out from a roll (not shown) is conveyed in the longitudinal direction while being sandwiched between the conveying roller 12a and the pinch roller 12b.

  A plurality of guide rollers 12c are arranged on the conveyance path between the conveyance rollers 12a. Between the conveyance rollers 12a, the web W is supported in a horizontally stretched state by the guide rollers 12c, thereby suppressing fluttering, bending, and the like of the web W being conveyed. The web W is unwound from a roll (not shown), and is then wound around a roll (not shown) again at the transport destination.

  Each transport roller 12a receives power from a drive source such as a motor (not shown) and rotates in the same direction (clockwise as viewed in FIG. 1) at a constant speed. In addition, although the elongate web W is mentioned here as a sheet-like article, the sheet-like article may be cut | disconnected for every piece. In this case, the conveyance mechanism 12 uses a conveyance roller 12a that is arranged with a smaller interval than the entire length of the sheet-like article.

  For example, a rotary encoder 14 is connected to one of the transport rollers 12a. The rotary encoder 14 rotates with the transport roller 12a and generates a pulse signal at every fixed rotation angle.

  The inspection apparatus 10 includes a line sensor 18 as an imaging device, and the line sensor 18 is installed below the conveyance path of the web W. The line sensor 18 incorporates a large number of imaging elements arranged in a straight line with a certain width. For the image sensing device used for the line sensor 18, an electron tube type imaging tube or the like can be used in addition to a semiconductor type such as a CCD image sensor or a CMOS image sensor. In addition, a lens 20 is installed on the front surface of the line sensor 18 (in front of the light receiving surface) to image the transmitted light from the web W on the image sensor.

  The inspection apparatus 10 includes, for example, a white light source 22 and an infrared light source 24 as two types of light sources that irradiate the web W with inspection light. The white light source 22 and the infrared light source 24 are supported by support members 26 and 28 that also function as lamp housings, respectively. The light sources 22 and 24 irradiate the inspection light (white light and infrared light) obliquely downward toward the same upper surface of the web W while being supported by the support members 26 and 28, respectively.

  Further, the two support members 26 and 28 have a structure in which the base end portions of the two support members 26 and 28 are connected via a hinge 30, and the installation angles of the support members 26 and 28 with respect to the web W are centered on the hinge 30. Can be adjusted. For this reason, the irradiation angle from each light source 22 and 24 with respect to the web W can be arbitrarily adjusted by adjusting the installation angle of the supporting members 26 and 28 finely. The hinge 30 is supported by another support member (not shown).

  The inner surface of the support member 28 of the infrared light source 24 is formed as an infrared light reflecting surface (white surface or mirror surface). For this reason, the infrared light emitted from the infrared light source 24 is reflected on the inner surface of the support member 28 (the lower side surface in FIG. 1) and is irradiated on the upper surface of the web W while diffusing in a certain range. The inner surface of the support member 26 that supports the white light source 22 is also formed as a light reflecting surface.

  In addition, the inspection apparatus 10 includes an image processing unit 32 having a function as an electronic computer in addition to the mechanical elements described above. The image processing unit 32 is configured as an electronic computer having a central processing unit (CPU), a storage device (ROM, RAM), an input / output interface (I / O), and the like. Examples of electronic computers include general-purpose personal computers and workstations. The image processing unit 32 receives a pulse signal from the rotary encoder 14 and an image signal from the line sensor 18. The image processing unit 32 performs various processes on the image data based on these input signals. The processing performed by the image processing unit 32 will be further described later.

  FIG. 2 is a perspective view showing a process in which the web W is imaged by the line sensor 18 while irradiating the inspection light from the light sources 22 and 24. As described above, the line sensor 18 is arranged on the lower surface side of the web W, and the main scanning line (not shown) is positioned in the width direction (transverse direction) of the lower surface of the web W.

[Irradiation process]
The white light source 22 is installed on the upper surface of the web W at a position that irradiates white light on the main scanning line of the line sensor 18. At this time, the white light source 22 emits white light (first inspection light) from the direction of an angle θ (for example, within a range of 30 ° to 45 °) smaller than 90 ° with respect to the upper surface of the web W. . On the other hand, the line sensor 18 is installed vertically below the lower surface of the web W. Therefore, the line sensor 18 is disposed at a position that does not face the light irradiation direction from the white light source 22 with the web W interposed therebetween. In the present embodiment, it is assumed that white light is mainly in the visible light wavelength region (for example, 380 to 780 nm).

  One infrared light source 24 also irradiates infrared light (second inspection light) from a direction having an angle with respect to the upper surface of the web W. The infrared light is emitted from the support member 28 as described above. What is reflected by the reflective surface is also applied to the web W. For this reason, infrared light is diffused in a certain range (AD in the figure) and irradiated onto the web W, but most of the infrared light is irradiated downward toward the main scanning line of the line sensor 18. Therefore, the line sensor 18 is in a position where infrared light can be received as transmitted light below the web W. In this way, by reflecting infrared light and then transmitting it through the web W, it is possible to prevent light spots (eyes) from appearing in the image when the infrared light source 24 is, for example, LED illumination. In the present embodiment, infrared light is mainly in the infrared wavelength region (for example, 750 to 1000 × nm).

[Imaging process]
And when the web W is conveyed in such an illumination environment, the infrared light which permeate | transmitted the inside of the web W in the position of the main scanning line with the conveyance is the lens 20 (not shown in FIG. 2). Then, the light is received by the image sensor of the line sensor 18. As for the white light, for example, the inside of the web W is refracted or diffused at the position of the main scanning line, and light directed vertically downward therefrom is received by the line sensor 18 through the lens 20.

[Contrast generation principle]
At this time, for example, if bubbles B (which may be cavities) are generated inside the web W, white light is generated due to changes in the internal film structure (the medium changes from the resin material layer to the air layer and from the air layer to the resin material layer). Causes a variety of refraction and scattering. The direction of refraction and scattering at this time is not uniform as in refraction occurring at a healthy position where the bubble B does not exist, and refraction or scattering occurs in an irregular direction depending on the direction of the boundary surface. Accordingly, the amount of white light received by the line sensor 18 decreases at the position where the bubble B exists, and this reduced amount forms a dark region in the image.

  In addition, when foreign matter H (for example, human hair, fibers such as animals, fibers, etc.) is mixed in the web W, transmission of infrared light is blocked at that position. For this reason, the amount of infrared light received by the line sensor 18 decreases at the position where the foreign matter H is present, and this reduced amount forms a dark region in the image.

  On the other hand, since most of infrared light is received by the line sensor 18 as transmitted light, the brightness of the image captured by the line sensor 18 is basically improved by the infrared light. Thereby, the contrast of the dark area | region in an image and the other bright area | region can be raised, and the test | inspection precision by subsequent image processing can be improved.

  FIG. 3 is a block diagram showing the configuration of the image processing unit 32 in more detail. The image processing unit 32 includes an input unit 34, a data processing unit 36, a data storage unit 38, an inspection processing unit 40, and an output unit 42 as its constituent elements, and a CPU 44 that controls these operations. Hereinafter, each component will be described. Here, an example in which the data processing unit 36 and the inspection processing unit 40 are provided inside the image processing unit 32 in addition to the CPU 44 is described, but the functions of the data processing unit 36 and the inspection processing unit 40 are the resources of the CPU 44. You may implement | achieve using. In addition, the configuration described here with reference to the drawing is merely a preferable example, and other configurations can be adopted for the image processing unit 32.

  An image signal from the line sensor 18 and a pulse signal from the rotary encoder 14 are input to the input unit 34 via the input interface. The input unit 34 has a function of adjusting the attenuation of the image signal (analog signal) as necessary while referring to the input pulse signal, A / D converting the signal, and transmitting the result to the data processing unit 36.

  The data processing unit 36 processes the transmitted image signal in the form of image data (raster data) for one line. At this time, for example, gray scale density values (0 to 255 gradations) are assigned to each pixel in one line. The data processing unit 36 assigns a column address to each pixel included in one line and assigns a row address for each line.

  The image data for each line processed by the data processing unit 36 is transferred to the data storage unit 38 via the data bus 46. A fixed storage area is secured in the data storage unit 38, and memory addresses corresponding to the row address and the column address assigned to the image data are assigned to the storage area. The transferred image data (density value of 0 to 255) is written in the memory cell (for 1 byte) at the corresponding memory address.

  The inspection processing unit 40 accesses the data storage unit 38 via the data bus 46, reads image data from the storage area, and performs inspection processing. The inspection processing unit 40 writes the inspection result data in the data storage unit 38 and transfers the inspection result data to the output unit 42 as necessary. A specific aspect of the inspection processing performed by the inspection processing unit 40 will be further described later.

  In addition to outputting the inspection result data as described above, the output unit 42 outputs captured image data (transmitted light image of the web W) as necessary. The data output destination is, for example, an image display (not shown), another general-purpose computer, a recording medium, or the like. Thereby, the inspection result is displayed on the image display and the operator visually recognizes the transmitted light image on the screen, or the transmitted light image of the web W is displayed on the screen and the operator visually recognizes the image. be able to.

  In addition, although not particularly illustrated, the image processing unit 32 may include a data correction unit. The data correction unit reads the image data stored in the data storage unit 38 and performs the correction process. The correction processing is performed, for example, for the purpose of correcting unevenness in density due to a periodic change in the transport speed by the transport mechanism 12 and correcting changes in density difference due to flickering in room lighting. Further, such a function of the data correction unit may be realized using resources of the CPU 44.

[Generation of image data]
In the image processing unit 32, image data is generated through, for example, the following process. That is, when a pulse signal is input from the rotary encoder 14, the image processing unit 32 uses the line sensor 18 to perform imaging (imaging) for one line. Thereby, in the line sensor 18, each image sensor is activated (exposure state), and an image signal is generated based on the received light intensity from the main scanning line. Next, when a pulse signal is input, the image processing unit 32 ends the imaging for one line. Through the processing so far, image data for one line is generated.

  When the image processing unit 32 finishes the image data generation process for one line once, the image processing unit 32 repeats the next image data generation process again, accumulates a plurality of lines, and generates one unit of image data. When the web W is a long product as in the present embodiment, the image data generation process may be performed, for example, by dividing the web W in the longitudinal direction.

  That is, registration marks (not shown) are attached to one side edge portion of the web W at equal intervals, for example, and the registration mark sensor not shown in FIGS. It has. When the registration mark sensor detects a registration mark immediately before the main scanning line (upstream position in the transport direction), the image processing unit 32 starts the image data process. When the registration mark sensor detects the next registration mark, the image processing unit 32 ends the image data generation process for one unit and then starts the next image data generation process. The image data for each unit generated at this time is recorded in the data storage unit 38 in association with, for example, a registration mark number.

[Inspection process]
FIG. 4 is a flowchart showing a procedure example of the inspection process executed in the image processing unit 32. Hereinafter, the outline of the inspection process will be described step by step.

  Step S10: First, the image processing unit 32 performs a filtering process on an image captured by the line sensor 18. In this filtering process, noise components are removed from the image data used for inspection. Note that the image data to be filtered at this time may be divided into units of a two-dimensional image corresponding to a certain length of the web W as described above, for example.

  Step S12: Next, the image processing unit 32 executes an edge extraction process. In this process, for example, both ends of the web W included in the image are extracted using a first-order differential filter, and the image in the outer region is excluded from the inspection target.

  Step S14: Next, the image processing unit 32 executes binarization processing. In this processing, the density value of each pixel in the image data is converted to binary image data by comparing it with a predetermined threshold value. At this time, the pixels in the dark area formed at the positions of the bubbles B and the foreign matter H as described above are converted into black data (01H) by binarization processing, and the other pixels are converted into white data (00H). Is done. The converted binary image data is temporarily buffered in the data storage unit 38.

  Step S16: The image processing unit 32 executes a grouping process. This process groups the black data in the binary image data and combines the pixels in the dark area as one unit.

  Step S18: Next, the image processing unit 32 executes defect type selection processing in the inspection processing unit 40. In this process, among dark areas generated in the image, a dark area generated due to a different cause (for example, dust adhered to the surface of the web W) different from the internal bubbles B and the mixed foreign matter H is selected and inspected. Exclude from the target. The selection algorithm can be specified in advance by a program.

  Step S20: The image processing unit 32 executes determination processing in the inspection processing unit 40. In this processing, the presence or absence of a defect of the bubble B or the foreign matter H is determined from the dark region (a group of black data) in the finally remaining image, and the address of the pixel determined to be defective in the image is specified. .

  Step S22: Finally, the image processing unit 32 executes a result storage process. In this processing, in addition to the presence / absence of defects such as bubbles B and foreign matter H, information such as the position where the defect exists in the image, its size, range, etc. is stored in association with the image data. The information stored here can be displayed on the image display in a list format, for example, or output as an inspection report. In this process, the image processing unit 32 stores a peripheral image including a defective portion in the data storage unit 38. Note that the images stored here can be appropriately called up and displayed as thumbnails or output in thumbnail format.

[Example of image]
FIG. 5 is a diagram illustrating an example of an image captured by the line sensor 18. As described above, since the image captured by the line sensor 18 is a transmitted light image, a healthy region of the web W that occupies most of the image is also captured as a gray image.

  In addition, according to the inspection method using the inspection apparatus 10 of the present embodiment, as shown by the broken line in the figure, the dark areas where the bubbles B and the foreign matter H are clear are formed even in the gray image. To do. Further, since the brightness of the entire image is improved by the amount of transmitted infrared light, a sufficient contrast can be obtained in the dark region. Thereby, the presence or absence of the bubble B and the foreign material H can be inspected with high accuracy from the brightness difference between the dark region and the surroundings.

  The present invention can be implemented with various modifications without being limited to the above-described embodiment. In one embodiment, a structure in which the support members 26 and 28 of the two light sources 22 and 24 are connected by a hinge 30 is employed. However, the support members 26 and 28 may be supported by independent hinges.

  In one embodiment, the infrared light source 24 is disposed obliquely with respect to the upper surface of the web W. However, the infrared light source 24 may be disposed vertically with respect to the upper surface of the web W. In this case, it is preferable to arrange a diffusion plate having an infrared light diffusion effect between the infrared light source 24 and the web W.

  In addition, the arrangement of various devices described in the embodiment is a preferable example, and the arrangement of the devices can be changed as appropriate when the present invention is implemented.

It is the figure which showed schematically the example of a structure of the test | inspection apparatus. It is the perspective view which showed the process in which a web is imaged with a line sensor, irradiating inspection light. It is a block diagram which shows the structure of an image process part in detail. It is the flowchart which showed the example of the procedure of the inspection process. It is a figure which shows an example of the image imaged with the line sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inspection apparatus 12 Conveyance mechanism 12a Conveyance roller 12b Pinch roller 12c Guide roller 14 Rotary encoder 18 Line sensor 20 Lens 22 White light source 24 Infrared light source 26, 28 Support member 30 Hinge 32 Image processing part 34 Input part 36 Data processing part 38 Data Storage unit 40 Inspection processing unit 42 Output unit 44 CPU

Claims (5)

While irradiating the first inspection light from the first light source toward one surface of the sheet-like article having light transmittance, the first inspection light is mainly wavelength toward the same one surface. An irradiation step of irradiating a second inspection light having a different area from the second light source;
An imaging device that has a predetermined angle without facing the irradiation direction of the first inspection light across the sheet-like article and is installed at a position where the second inspection light can be received as transmitted light. An imaging step of imaging the other side of the sheet-like article using,
An inspection method for inspecting the internal state of the sheet-like article from the brightness difference in the image obtained in the imaging step. In the inspection method of the sheet-like article according to claim 1,
In the irradiation step,
By using white light mainly included in the wavelength region of visible light as the first inspection light, and using infrared light mainly included in the wavelength region of infrared as the second inspection light, The first inspection light is refracted or scattered by a change in the film structure existing inside the sheet-like article to reduce the amount of light received by the imaging device, while the second inspection light is sheet-shaped. A method for inspecting a sheet-like article, characterized in that the amount of light received by the imaging device is reduced by reducing the transmittance by a foreign substance existing inside the article. A first light source that irradiates the first inspection light toward one surface of the sheet-like article having light transparency;
A second light source for irradiating a second inspection light having a wavelength region different from that of the first inspection light toward one surface of the same sheet-shaped article as the first light source;
The sheet-shaped article is placed at a position that has a predetermined angle without facing the irradiation direction of the first inspection light and that can receive the second inspection light as transmitted light. An imaging device for imaging the other surface of the sheet-like article;
An inspection apparatus for a sheet-like article, comprising: an inspection unit that inspects an internal state of the sheet-like article from a difference in brightness in an image obtained by imaging with the imaging device. The inspection apparatus for a sheet-like article according to claim 3,
The first light source is a white light source that emits white light mainly included in a wavelength region of visible light as the first inspection light,
The sheet-like article inspection apparatus, wherein the second light source is an infrared light source that emits infrared light mainly included in an infrared wavelength region as the second inspection light. In the inspection apparatus of the sheet-like article according to claim 3 or 4,
An angle adjustment mechanism capable of adjusting an irradiation angle of the first inspection light with respect to one surface of the sheet-like article;
An inspection apparatus for a sheet-like article, further comprising: a light reflecting surface that reflects the second inspection light emitted from the second light source and irradiates one surface of the sheet-like article.