Foreign matter inspection device and foreign matter inspection method

Abstract

To provide a foreign matter inspection device that detects specific foreign matters adhering to a web, and that in addition, evaluates the number and sizes thereof, in an inspection of foreign matters adhered to a web surface.SOLUTION: A foreign matter inspection device inspects attachment of specific foreign matters on a web during conveyance. The foreign matter inspection device comprises: a collection part having a foreign matter collection area for collecting foreign matters including specific foreign matters adhering to a web; an irradiation part for irradiating the foreign matter collection area with light; and an observation part for observing the foreign matter collection area that is irradiated by the irradiation part. A material constituting a surface of the foreign matter collection area is a material having an excitation wavelength different from that of the specific foreign matters, a material whose fluorescent light emitting quantity due to excitation is equal to a detection limit of the observation part or less, or a material not having an excitation wavelength. With regard to a wavelength of the light irradiated from the irradiation part, a wavelength range of the full width at half maximum of the wavelength overlaps at least partly with the wavelength range of a wavelength range of the full width at half maximum of the excitation wavelength of the specific foreign matters.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for inspecting a web such as a film for foreign matter. [Background technology]

[0002] In processes for continuously producing webs such as films, airborne dust particles floating in the air or process dust particles generated during the process can adhere to the surface of the web, causing defects, which can be a problem. Common methods for inspecting for such foreign matter include directly observing the web during transport using a line camera, or cutting the web to a desired size and observing it with an area camera or microscope.

[0003] However, with the above-mentioned method of directly observing a web during transport, it is difficult to continuously capture images of the web in the transport direction while maintaining a resolution sufficient to recognize minute foreign particles. Furthermore, with the method of cutting the web to a desired size and then observing it, the process of cutting the web to the desired size is complicated, and problems arise such as the loss of foreign particles or their movement during sample handling, or the attachment of other foreign particles during sampling or observation.

[0004] To address the above-mentioned problems, for example, Patent Document 1 proposes a foreign matter inspection device and a foreign matter inspection method that are provided with a capturer that captures foreign matter adhering to the surface of a web during transport. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-79150 Summary of the Invention [Problem to be solved by the invention]

[0006] The foreign matter inspection device and foreign matter inspection method described in Patent Document 1 require the foreign matter to be separately sampled and subjected to elemental analysis when it is desired to identify the material of the foreign matter in order to identify the cause and location of the foreign matter. Therefore, there has been a demand for an inspection method that can more easily quantitatively determine the amount of adhesion of each type of foreign matter.

[0007] Furthermore, the foreign matter inspection device and foreign matter inspection method described in Patent Document 1 determine the presence or absence of foreign matter based on the difference in brightness during inspection. Therefore, there has been a demand for an inspection method that can also detect transparent foreign matter with only a small difference in brightness.

[0008] The present invention solves the above-mentioned problems and provides a foreign matter inspection device and method that can detect specific foreign matter adhering to a web and evaluate the number and size of the foreign matter adhering to the web surface. [Means for solving the problem]

[0009] [1] The present invention, which solves the above-mentioned problems, is a foreign matter inspection device that inspects a web during transport for adhesion of specific foreign matter, a collecting section having a foreign matter collecting area for collecting foreign matter including the specific foreign matter adhering to the web; an irradiation unit that irradiates the foreign matter collection area with light; an observation unit that observes the foreign matter collection area irradiated by the irradiation unit, the material constituting the surface of the foreign matter collection area is a material having an excitation wavelength different from that of the specific foreign matter, a material having an excitation fluorescence emission amount equal to or less than the detection limit of the observation section, or a material having no excitation wavelength; The wavelength range of the full width at half maximum of the wavelength of the light irradiated from the irradiating unit at least partially overlaps with the wavelength range of the full width at half maximum of the excitation wavelength of the specific foreign matter.

[0010] The foreign matter inspection device of the present invention is preferably in any one of the following aspects [2] to [4]. [2] The foreign matter inspection device according to [1] above, wherein the collection unit is an adhesive roll whose adhesive surface serves as the foreign matter collection area. [3] The foreign matter inspection device according to [1] or [2] above, further comprising a moving means for moving the foreign matter collection area from a position where the foreign matter is collected to a position where the collected foreign matter is observed by the observation unit while holding the foreign matter. [4] The foreign matter inspection device according to [3] above, further comprising a drive means for moving the collection unit, separate from the drive means for the transport system that transports the web.

[0011] [5] The present invention, which solves the above-mentioned problems, is a foreign matter inspection method for inspecting a web during transportation for adhesion of a specific foreign matter, comprising the steps of: foreign matter including the specific foreign matter adhering to the web is collected by a collection unit having a surface made of a material having an excitation wavelength different from that of the specific foreign matter, or a material having an excitation fluorescence emission amount below the detection limit of an observation means, or a material having no excitation wavelength; irradiating the surface of the collection unit that is collecting the foreign matter with light having a wavelength range of full width at half maximum that at least partially overlaps with the wavelength range of full width at half maximum of the excitation wavelength of the specific foreign matter; If the fluorescent wavelength of the specific foreign matter is observed, it is determined that the specific foreign matter has adhered to the web.

[0012] In the present invention, the specific foreign matter refers to a foreign matter made of a material that has been set as an object of inspection.

[0013] In the present invention, "at least a portion of the wavelengths overlap" means that in a spectral distribution where the horizontal axis is wavelength and the vertical axis is relative radiant intensity of light, the wavelength range of the full width at half maximum of the peak wavelength of the irradiated light and the wavelength range of the full width at half maximum of the excitation wavelength of the specific foreign substance being observed overlap over a range wider than 0 nm.

[0014] In the present invention, the term "fluorescence" refers to a phenomenon in which the specific foreign matter is excited by energy obtained from the outside and releases excess energy by luminescence when returning from the excited state to the ground state.

[0015] In the present invention, the excitation wavelength refers to the wavelength of the irradiated light necessary for the specific foreign matter to be in an excited state.

[0016] In the present invention, the full width at half maximum refers to the wavelength range in which the intensity of the peak wavelength of light is half of the maximum value. [Effects of the Invention]

[0017] The foreign matter inspection device and foreign matter inspection method of the present invention can detect specific foreign matter adhering to a web in an inspection for foreign matter adhering to the surface of the web, and can also evaluate the number and size of the specific foreign matter adhering to the web. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic side view showing a first embodiment of a foreign matter inspection device according to the present invention. [Figure 2] FIG. 4 is a schematic side view showing a second embodiment of a foreign matter inspection device according to the present invention. [Figure 3] FIG. 10 is a schematic side view showing a third embodiment of a foreign matter inspection device according to the present invention. [Figure 4] 1 is a schematic side view showing an example of the installation position of an observation unit of a foreign matter inspection device according to the present invention. [Figure 5] 1A and 1B are schematic diagrams showing examples of observation images obtained using the foreign matter inspection device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, examples of the best mode for carrying out the present invention will be described with reference to the drawings.

[0020] [First embodiment] Please refer to Figure 1. Figure 1 is a schematic side view showing a first embodiment of the present invention. The foreign matter inspection device 1 of this embodiment is composed of a collection unit 2 having a foreign matter collection area that collects foreign matter, including specific foreign matter 14, adhering to a web 11, an irradiation unit 3 that irradiates the foreign matter collection area with light, and an observation unit 4 that observes the foreign matter collection area irradiated by the irradiation unit 3.

[0021] The material that constitutes the surface of the foreign matter capture region of capture unit 2 is made of a material that has an excitation wavelength different from that of specific foreign matter 14, a material whose amount of fluorescent light emitted by excitation is below the detection limit of observation unit 4, or a material that has no excitation wavelength. By using such a material, there is no interference from fluorescent light emitted from the foreign matter capture region, and so if observation unit 4 detects fluorescent light at the excitation wavelength of specific foreign matter 14 (hereinafter sometimes referred to as specific excitation wavelength), it can be determined that specific foreign matter 14 is present.

[0022] More specifically, the following points (1) to (3) are included. (1) If the material constituting the surface of the foreign body capture area has an excitation wavelength different from the specific excitation wavelength, the light irradiated by the irradiation unit 3 will cause the specific foreign body 14 and the foreign body capture area to emit fluorescence at their respective excitation wavelengths. However, if the observation unit 4 is configured to detect only the wavelength range of the specific excitation wavelength, or if the light irradiated from the irradiation unit 3 is limited to a wavelength range that excites only the specific foreign body 14, then if the observation unit 4 detects fluorescence at the specific excitation wavelength, it can be determined that the specific foreign body 14 is present. (2) If the material constituting the surface of the foreign body collection area emits fluorescence upon excitation that is below the detection limit of the observation unit 4, even if the excitation wavelength of the foreign body collection area is the same as or overlaps with the specific excitation wavelength, the observation unit 4 cannot detect fluorescence from the foreign body collection area. Therefore, if the observation unit 4 detects fluorescence at the specific excitation wavelength, it can be determined that a specific foreign body 14 is present. (3) When the material that forms the surface of the foreign matter collection region does not have an excitation wavelength, if the observation unit 4 detects fluorescent light of a specific excitation wavelength, it can be determined that a specific foreign matter 14 is present.

[0023] For example, when the web 11 is a PP (polypropylene) film and the material of the specific foreign matter 14 is PET (polyethylene terephthalate), if cotton, which has a different excitation wavelength from PET, is used as the background fiber material 21 when observing with the observation unit 4, then by limiting the detection wavelength range of the observation unit 4 and the wavelength range of the light irradiated from the irradiation unit 3, only the fluorescent emission of the specific foreign matter 14 can be detected, making it possible to detect the specific foreign matter 14 that you want to observe, inspect, or count.

[0024] The collection unit 2 includes a fiber material 21, and the portion of the fiber material 21 that comes into contact with the web 11 forms the foreign matter collection region. The width of the foreign matter collection region is preferably larger than the width of the web 11 to be inspected. This makes it easier to collect foreign matter across the entire width of the web 11, and furthermore, even if the web 11 meanders, foreign matter adhering to the web 11 can be reliably collected.

[0025] It is preferable to use natural fibers such as cotton or synthetic fibers such as rayon or polyester as the material for the fiber material 21. By using such soft materials, it becomes easier to prevent scratches from occurring on the surface of the web 11 when collecting the specific foreign matter 14. Furthermore, synthetic fibers can be obtained more cheaply than natural fibers.

[0026] It is preferable that the structure of the fiber material 21 be a melt-blown nonwoven fabric manufactured by the melt-blowing method. By using a melt-blown nonwoven fabric, the number of fibers per unit area increases, making it easier to capture foreign matter adhering to the web 11 without letting it slip out.

[0027] While there are no particular limitations on the method for pressing the fibrous material 21 of the collection unit 2 against the web 11, it is preferable to install a rigid object as a support 22 on the surface of the fibrous material 21 opposite the web 11, as shown in Figure 1. Installing the support 22 makes it easier to bring the fibrous material 21 into uniform contact with the web 11. When inspecting the fibrous material 21 while it is fixed to the support 22, it is preferable that the material of the support 22 be a material with an excitation wavelength different from that of the specific foreign matter 14, a material whose amount of fluorescence emission due to excitation is below the detection limit of the observation unit 4, or a material that has no excitation wavelength. Furthermore, if the width of the support 22 is equal to or greater than the width of the fibrous material 21, it is easier to collect foreign matter across the entire width of the web 11.

[0028] Furthermore, it is preferable that the collection unit 2 has a means for moving the foreign matter to any position while maintaining the position of the foreign matter once collected. By providing a means for moving the foreign matter to any position, the collected foreign matter can be easily inspected even when it is difficult to install the irradiation unit 3 and the observation unit 4 due to reasons such as a short interval between the transport rolls 12 that transport the web 11.

[0029] When the foreign matter inspection device 1 has the above-described moving means, it can use a structure that allows the fiber material 21 to be easily attached and detached from the support 22, or a structure that allows the fiber material 21 to be moved while being fixed to the support 22. If the structure of the fiber material 21 is a melt-blown nonwoven fabric as described above, it is preferable because the collected foreign matter is held between the fibers even during movement, preventing the foreign matter from falling off or moving during movement.

[0030] It is also preferable to have a means for moving the foreign object to a desired position while holding it, and then further moving it on the XY plane at a desired speed. A commercially available movable stage can be used as the moving means. Furthermore, if there is a means for setting the moving speed to a constant, it becomes easier to obtain image data without noise or blur during inspection. The moving speed of the movable stage can be selected appropriately depending on the resolution of the camera used in the observation unit 4. If the stage is moved at a low speed, even a low-resolution camera can observe minute foreign objects, and if a high-resolution camera is used and the stage is moved at high speed, inspection can be performed in a shorter time.

[0031] Regarding the inspection position, in addition to the method of moving the collection unit 2 to any position while maintaining the position of the foreign matter collected as described above, an inspection configuration may be adopted in which the inspection is performed from the side of the web 11 where the collection unit 2 is not installed, as shown in Figure 1. This configuration allows the process of foreign matter collection to be observed in real time. In this case, the direction of irradiation with the irradiation light 32 may be either the opposite side of the collection unit 2 as shown in Figure 1 or the same side, and can be selected appropriately based on the space available in the foreign matter inspection device 1.

[0032] The irradiation unit 3 irradiates irradiation light 32 onto a part or the entire surface of a foreign matter collection area that collects all foreign matter, including specific foreign matter 14, adhering to the web 11. The full width at half maximum range of the peak wavelength of the irradiation light 32 at least partially overlaps with the full width at half maximum range of the excitation wavelength of the specific foreign matter 14. This allows the specific foreign matter 14 to emit fluorescence, making it easy to detect the specific foreign matter 14 during observation.

[0033] The peak wavelength of the irradiated light 32 can be selected according to the specific foreign matter 14. For example, if the material of the specific foreign matter 14 is PET, the peak wavelength of the irradiated light 32 can be preferably selected to be around 350 nm, if the material is PVC (polyvinyl chloride), the peak wavelength of the irradiated light 32 can be around 330 nm, and if the material is protein such as hair or sebum, the peak wavelength of the irradiated light 32 can be preferably selected to be around 400 to 500 nm.

[0034] The wavelength range of the illumination light 32 emitted from the illumination unit 3 is preferably in the range of approximately 5 nm to 20 nm in terms of full width at half maximum. A full width at half maximum of 20 nm or less facilitates fluorescence emission from only the specific foreign matter 14 to be inspected, while a full width at half maximum of 5 nm or more facilitates obtaining sufficient light for observation while suppressing noise. Methods for obtaining the above peak width include selecting a light source 31 that meets the specifications or installing a cutoff filter 33 between the light source 31 and the collection unit 2, as shown in Figure 1. The cutoff filter 33 can be one that can cut wavelengths shorter than approximately 10 nm shorter than the peak wavelength of the fluorescence emission of the specific foreign matter 14 and longer than approximately 10 nm longer. This method allows the light source 31 to be selected based solely on the wavelength position of the peak, without any restrictions on the full width at half maximum of the illumination light 32. Furthermore, if the illumination unit 3 has a means for adjusting the wavelength of the illumination light 32, a single illumination unit 3 can be adjusted to suit multiple specific foreign matters 14 and the materials of the collection unit 2, thereby reducing the cost of the illumination unit 3 in the foreign matter inspection device 1.

[0035] The intensity of the irradiated light 32 is not particularly limited, and since the intensity of the fluorescent emission is determined by the intensity of the irradiated light 32, it can be determined so that the amount of fluorescent emission from the specific foreign matter 14 is greater than the detection limit of the observation unit 4. Increasing the intensity of the irradiated light 32 is preferable because it increases the amount of fluorescent emission accordingly, allowing for shorter observation times. Here, the presence or absence of fluorescent emission is not affected by the intensity of the irradiated light 32.

[0036] The shape of light source 31 is not particularly limited, and can be selected from common light source 31 shapes such as spot, ring, line, and surface-emitting types, depending on the size, shape, and field of view of the camera serving as observation unit 4. It is preferable to irradiate an area onto which irradiating light 32 is emitted that is equal to or wider than the field of view of the camera, since this facilitates obtaining image data with uniform brightness. For example, when observing web 11 using area camera 41 from the side opposite to the side where collection unit 2 is installed while web 11 is being transported, as shown in FIG. 1, using a ring-shaped or surface-emitting light source 31 is preferable because it allows irradiating light 32 uniformly across the field of view of area camera 41, making it easier to obtain image data with uniform brightness.

[0037] Since normal fluorescent light is emitted in the wavelength range of 400 nm or less, the observation unit 4 can use commercially available cameras, such as an area camera 41 for observing any range or a line camera 44 for observing a rotating body, as long as they can detect light in the above wavelength range.

[0038] The resolution of the observation unit 4 is appropriately selected depending on the minimum size of the specific foreign matter 14 to be inspected and the inspection range. High resolution allows for the detection of minute foreign matter, while low resolution allows for the inspection of a wider range. For example, if the minimum size of the specific foreign matter 14 is approximately 10 μm square, setting the resolution to half that, approximately 5 μm square, allows for clear detection of the adhesion of the specific foreign matter 14. However, in the foreign matter inspection device 1 and foreign matter inspection method of the present invention, the specific foreign matter 14 is observed by emitting fluorescence, so the specific foreign matter 14 appears larger than its actual size. Therefore, even if the resolution of the observation unit 4 is approximately 10 to 20 percent lower than normal for the size of the foreign matter, the specific foreign matter 14 can be detected. For example, if the minimum size of the specific foreign matter 14 is approximately 10 μm square, it will be observed as approximately 15 μm square by emitting fluorescence, so the adhesion of the specific foreign matter 14 can be clearly detected even if the resolution of the observation unit 4 is approximately 8 μm.

[0039] The position of the observation unit 4 relative to the irradiation unit 3 is preferably such that the observation unit 4 does not capture specularly reflected light 34, as shown in Figure 4, that is, it is positioned at a distance of at least the lens radius from the optical axis of the specularly reflected light 34. By placing it in this position, the observation unit 4 is prevented from directly capturing the specularly reflected light 34, making it easier to capture only the fluorescent light. Furthermore, by installing a cut filter 33 that blocks all but specific wavelengths in either or both of the irradiation unit 3 and the observation unit 4, it is possible to capture only the fluorescent light, even when the observation unit 4 is positioned to capture the specularly reflected light 34.

[0040] The method for processing the observation image captured by the observation unit 4 is not particularly limited, but it can be captured and processed using a general PC. The foreign matter inspection device 1 of this embodiment observes the state in which only the specific foreign matter 14 is emitting fluorescence, so the specific foreign matter 14 is observed as a bright defect that is relatively bright compared to the background and other foreign matters 15, as shown in Figure 5. Depending on the material of the collection unit 2 and the shape of the other foreign matters 15, the other foreign matters 15 may be observed as a dark defect that is even darker than the formation. Therefore, if a threshold value is set using brightness for the captured observation image, it becomes easy to distinguish the specific foreign matter 14 of interest from other matters.

[0041] Furthermore, although there are no particular limitations on the environment in which the foreign matter inspection device 1 is installed, it is preferable to install it in a clean environment of class 10,000 or less, such as inside a clean booth. If the clean environment is class 10,000 or less, foreign matter other than the specific foreign matter 14 is less likely to adhere to the web 11, which prevents a decrease in the collection ability of the collection unit 2 and makes it easier to operate for longer periods of time. It also becomes easier to avoid a phenomenon in which other foreign matter 15 overlaps the specific foreign matter 14, making it impossible to detect the specific foreign matter 14.

[0042] [Second embodiment] Next, reference is made to Figure 2, which is a schematic side view showing a second embodiment of the present invention. In this embodiment, a non-contact web cleaner 23 is used in the collection unit 2, which blows air onto the web 11, sucks in the blown air together with foreign matter blown off the web 11, and passes the air through the filter 24, thereby capturing the foreign matter on the filter 24. In this way, the collection unit 2 does not come into direct contact with the web 11 and collects the foreign matter in a non-contact manner, thereby preventing scratches on the surface of the web 11 caused by contact with the collection unit 2.

[0043] In this embodiment, the filter 24 is removed from the non-contact web cleaner 23 and foreign matter collected on the filter 24 is inspected offline, so the irradiation unit and observation unit are not shown in FIG.

[0044] The shape of the non-contact web cleaner 23 and the method for non-contact foreign matter collection are not particularly limited, but commercially available non-contact web cleaners 23 are preferably used. The non-contact web cleaner 23 is preferably a type that blows air near the surface of the web 11 to remove foreign matter and then collects the foreign matter by suction, as shown in FIG. 2 . This type of non-contact web cleaner 23 is preferable because it is easier to prevent specific foreign matter 14 from scattering and is easier to suck up finer foreign matter with the same suction force compared to simple suction. Generally, the smaller the size of the specific foreign matter 14, the more difficult it is to collect by suction. Therefore, the collection capacity of the non-contact web cleaner 23 can be appropriately determined depending on the minimum size of the specific foreign matter 14 to be collected. The collection capacity of the non-contact web cleaner 23 is determined by factors such as the distance from the connected blower and web 11, the cross-sectional area of ​​the suction port, etc. For example, if the minimum size of specific foreign matter 14 adhering to a PET film conveyed at a speed of 200 m / min is about 50 μm, it is easy to capture almost all foreign matter by setting the distance between the non-contact web cleaner 23 and the web 11 to about 2 mm and the air discharge pressure to about 12 kPa.

[0045] The surface portion of the filter 24 that captures foreign matter constitutes the foreign matter capture region. Therefore, the material constituting the filter 24 is a material with an excitation wavelength different from that of the specific foreign matter 14, a material whose fluorescence emission upon excitation is below the detection limit of the observation unit 4, or a material with no excitation wavelength. The entire filter 24 may be made of such a material, or only the foreign matter capture region may be made of such a material. As in the first embodiment, using such a material allows for detection of only the fluorescence emission of the specific foreign matter 14 during inspection. Furthermore, the mesh size of the filter 24 can be appropriately selected from medium-efficiency filters, HEPA filters, ULPA filters, etc., depending on the size of the foreign matter to be captured. For example, if the size of the specific foreign matter 14 is 5 μm or less, a HEPA filter or ULPA filter can capture 99.9% or more of the specific foreign matter 14. Furthermore, in the case of HEPA filters, metal filters can be selected in addition to ordinary glass fiber filter paper.

[0046] When a non-contact web cleaner 23 is used in the collection unit 2, it is preferable to install a backing roll 13 at the position where the non-contact web cleaner 23 is installed, as shown in Figure 2, and to have the web 11 embraced by the backing roll 13 at an angle of at least 10 degrees. This configuration makes it easy to prevent the web 11 from flapping when foreign matter is collected.

[0047] A commercially available metal roll can be preferably used as the backing roll 13. By using a metal roll, the precision of the surface shape of the backing roll 13 can be easily improved and it can be manufactured inexpensively. Furthermore, if the face length of the backing roll 13 is equal to or greater than the width of the suction part of the non-contact web cleaner 23, it is easy to capture all foreign matter adhering to the web 11 and also easy to prevent the end of the web 11 from folding.

[0048] Non-contact web cleaners 23 are often configured such that it is difficult to directly observe the filter 24 when it is attached to the exhaust section 26, and so it is preferable that the filter 24 be configured to be easily removable. It is also preferable to spray an adhesive spray on the filter 24 beforehand or to use one with a large number of fibers per unit area, as this will prevent foreign matter from falling off during movement.

[0049] [Third embodiment] Next, reference is made to Figure 3, which is a schematic side view showing a third embodiment of the present invention. In this embodiment, an adhesive roll 27 is used in collection unit 2, and foreign matter adhering to the surface of web 11 is collected by the adhesive force of the surface of adhesive roll 27. Using adhesive roll 27 in collection unit 2 makes it easy to collect fine foreign matter, and further, because adhesive roll 27 rotates at the same speed as the conveyance speed of web 11, it is easy to prevent the surface of web 11 from being scratched during collection.

[0050] The surface of the adhesive roll 27 serves as a foreign matter collection area. Therefore, the material that constitutes the surface of the adhesive roll 27 is a material that has an excitation wavelength different from that of the specific foreign matter 14, a material whose amount of fluorescent light emitted by excitation is below the detection limit of the observation unit 4, or a material that has no excitation wavelength. As in the first embodiment, by using such a material, it is possible to detect only the fluorescent light emitted by the specific foreign matter 14. For example, silicone rubber is a material that does not have an excitation wavelength, making it easy to detect only the specific foreign matter 14.

[0051] The surface of the adhesive roll 27 is preferably coated with rubber having a hardness of approximately A10 to 60 degrees (JIS K 6253:2012). If the surface of the adhesive roll 27 is made of rubber having a hardness within the above range, the elasticity of the rubber will absorb minute irregularities on the surface of the adhesive roll 27 and on the surface of the web 11, making it easier to capture foreign matter, including specific foreign matter 14, on the surface of the web 11 without letting it slip out. Even if the adhesive roll 27 is deflected, if the deflection is approximately 500 μm, the deformation of the surface rubber will make it easier to capture foreign matter across the entire width of the web 11.

[0052] The adhesive strength of the adhesive roll 27 is preferably 40 to 200 hPa (JIS K 6256:2013). An adhesive strength of 40 hPa (JIS K 6256:2013) or more is preferable because it makes it easier to capture almost all of the specific foreign matter 14 on the surface of the web 11, and an adhesive strength of 100 hPa or more (JIS K 6256:2013) is even more preferable because it makes it easier to prevent foreign matter from falling off once captured and to prevent foreign matter from moving on the adhesive roll 27 while it is being transported. An adhesive strength of 200 hPa or less is also preferable because it makes it easier to prevent the web 11 from flapping when the adhesive roll 27 is peeled off from the web 11.

[0053] Furthermore, the friction withstand voltage, which indicates the electrostatic voltage generated on the adhesive roll 27 when friction occurs on the adhesive roll 27, is preferably 100 V (JIS L 1094:2014) or less. If the friction withstand voltage of the adhesive roll 27 is 100 V (JIS L 1094:2014) or less, the adhesive roll 27 becomes charged after collecting foreign matter, and it is easy to prevent other foreign matter 15, such as floating dust, other than the specific foreign matter 14 from being attracted, thereby preventing a decrease in collection ability and facilitating longer operation.

[0054] It is also preferable to install a backing roll 13 on the side of the web 11 where the adhesive roll 27 is not installed, as shown in Figure 3. By providing the backing roll 13, it is possible to prevent the web 11 from deforming during a free pass, which makes it less likely for wrinkles to occur in the web 11 after foreign matter collection, and also makes it easier to suppress transport problems such as meandering and flapping.

[0055] The receiving roll 13 can be appropriately selected from a metal roll or an adhesive roll 27. If a metal roll is selected, the precision of the surface shape of the receiving roll 13 can be easily improved, and the receiving roll 13 can be manufactured inexpensively. If an adhesive roll 27 is selected, foreign matter on both sides of the web 11 can be collected. Furthermore, if a roll with the same adhesive strength as the adhesive roll 27 in the collecting section 2 is used, it is easier to prevent the web 11 from being entangled in only one of the adhesive rolls, making it easier to prevent transport problems. It is preferable that the face length and diameter of the receiving roll 13 be the same size as the adhesive roll 27 used in the collecting section 2, as this makes it easier to collect all foreign matter adhering to the web 11.

[0056] The adhesive roll 27 used in the collection unit 2 preferably has a means for moving the roll to any position while maintaining the position of the foreign matter once collected. For example, a structure that can rotate to any phase around a certain fulcrum, as shown in Figure 3, can be preferably used. The above-mentioned structure makes it easy to bring the web 11 and the adhesive roll 27 into contact with each other with a uniform load.

[0057] It is also preferable to have a means for rotating the adhesive roll 27 at a desired speed after moving it to a desired position. As a moving means, a method of connecting the adhesive roll 27 to a motor to rotate it, or a method of contacting the adhesive roll 27 with a rotating metal pin connected to a motor to rotate it can be used. As with the XY stage, the rotation speed can be selected appropriately according to the camera resolution, etc. [Example]

[0058] The present invention will be explained in more detail below based on examples, but the present invention is not limited to these examples. Detailed implementation methods and various evaluation and measurement methods are also shown below.

[0059] [Web transport] The web was made of PET film, 100 mm wide and 50 μm thick. It was transported using a 50 mm diameter metal roll with an HCr-plated surface, at a speed of 100 m / min for 1 minute, i.e., 100 m.

[0060] [Method of manufacturing specific foreign objects] The PET film was sanded to create a specific foreign object made of PET material. The specific foreign object was observed with a laser microscope (OLS4100, manufactured by Olympus Corporation), and the area of ​​the foreign object was found to be approximately 25 to 5000 μm. 2 was within the range.

[0061] [Method of adhesion of specific foreign matter to web] The specific foreign matter was dropped from a height of 5 mm at a rate of approximately 1.0 g / min onto a 50 mm area in the width direction of a film being transported at 100 m / min, causing the specific foreign matter to adhere to the PET film.

[0062] [Distinguishing between specific foreign objects and other objects among the collected foreign objects] One hundred foreign objects detected as bright defects in each example and comparative example were collected with tweezers and subjected to IR analysis using a Fourier transform infrared spectrophotometer (IRSpirit-X, manufactured by Shimadzu Corporation).If more than 90% (more than 90 objects) could be identified as specific foreign objects, i.e., PET, it was determined that the specific foreign objects had been accurately identified.

[0063] [Minimum size of specific foreign matter] In each example and comparative example, all foreign matter that could be identified as specific foreign matter in the above "Distinguishing specific foreign matter from other collected foreign matter" was observed with a laser microscope (OLS4100, manufactured by Olympus Corporation). Observation was performed at 100x magnification, and the size of the smallest foreign matter among them was taken as the minimum size of the specific foreign matter.

[0064] [Detaching of captured foreign matter] In each example and comparative example, the collection section after foreign matter collection was observed at 10 random locations within a 100 μm × 100 μm area at 100x magnification using a laser microscope (OLS4100, manufactured by Olympus Corporation). The collection section was then brought into contact with a PET film being transported at a speed of 100 m / min for 10 seconds, and the same locations as the first observation were observed. If foreign matter seen in the first observation was not seen in the second observation, it was determined that foreign matter had fallen off.

[0065] [Scratches on the web surface] After the foreign matter collection, the web was visually inspected under a white light. The inspection was carried out at 10 random locations within a 100m area measuring 50mm in the conveying direction and 100mm in the width direction, transported at a speed of 100m / min. The average number of scratches at these 10 locations was recorded as the number of scratches.

[0066] [Example 1] Foreign matter collection and observation were performed using the foreign matter inspection device configuration of the first embodiment shown in Figure 1. However, since foreign matter observation was performed offline, the irradiation unit and observation unit were not installed on the conveying line. A melt-blown nonwoven fabric made of PP (polypropylene) (Toray Industries, Inc., Toray Micron®) was used as the collection unit to collect foreign matter adhering to a PET film conveyed at 100 m / min. The peak excitation wavelength of PET is approximately 350 nm (full width at half maximum: 5 nm), while the peak excitation wavelength of PP is approximately 300 nm (full width at half maximum: 5 nm). Therefore, this melt-blown nonwoven fabric is a material with an excitation wavelength different from that of the specific foreign matter. The melt-blown nonwoven fabric was fixed to a metal plate measuring 150 mm in the width direction and 20 mm in the conveying direction, with a thickness of 5 mm, within an area of ​​100 mm in the width direction and 20 mm in the conveying direction. The collection unit was not allowed to contact the web until the web conveying speed reached 100 m / min. In addition, a metal free roll with a diameter of 30 mm and hard chrome plating on the side not in contact with the collection unit was installed at the position where the collection unit would come into contact. The collection unit that collected the specific foreign matter was fixed to a movable XY stage and moved in the X direction (conveyance direction) at a speed of 2 m / min, while the entire area was observed with a line camera (Links Corporation, raL-4096-24gm). A light source (CS Corporation, LN-61UV-3-365) was used to irradiate the observation area with light having a peak wavelength of 365 nm and a full width at half maximum of 20 nm over an area of ​​100 mm in the width direction and 5 mm in the conveyance direction. The light source was also equipped with a cut filter that blocks wavelengths above 380 nm.

[0067] The observation results were subjected to image processing so that the background brightness value was 128, and brightness values ​​of 156 or higher were determined to be light defects, i.e., specific foreign matter, and brightness values ​​of 100 or lower were determined to be dark defects, i.e., foreign matter other than specific foreign matter.

[0068] [Example 2] Foreign matter was collected and observed using the foreign matter inspection device of the second embodiment shown in Figure 2. A non-contact web cleaner (UVU-W-320, manufactured by Shinko Co., Ltd.) was used as the collection unit, and it was installed directly above a metal roll with a hard chrome-plated surface that rotated at the same speed as the conveyance speed of a 300 mm diameter web. A melt-blown nonwoven fabric made of PP (polypropylene) (Torray Micron (registered trademark), manufactured by Toray Industries, Inc.) was used as the filter for collecting the sucked foreign matter. Other implementation conditions, such as the observation method and processing of the observation results, were the same as in Example 1.

[0069] [Example 3] Foreign matter was collected and observed using the foreign matter inspection device of the third embodiment shown in Figure 3. An adhesive roll (EC Dustrel M, manufactured by Kakanuki Roller Manufacturing Co., Ltd.) with a width of 120 mm and a diameter of 30 mm was used for the collection section, and a metal roll of the same size was previously installed on the side of the adhesive roll that was not in contact with the collection section at the position where the adhesive roll would come into contact. The adhesive roll was also a free roll, and rotated by contact with the film being transported.

[0070] The adhesive roll was moved from the contact position with the film to the observation position, and the adhesive roll was rotated at a speed of 2 m / min, and the entire circumference of the 100 mm range in contact with the film was observed with a line camera (RAL-4096-24gm, manufactured by Links Co., Ltd.) The other conditions, such as the processing of the observation results, were the same as in Example 1.

[0071] [Comparative Example 1] A meltblown nonwoven fabric (Toray Industries, Inc., Toray Micron®) that had collected foreign matter in the same manner as in Example 1 was fixed to a movable XY stage and moved at a speed of 2 m / min. The entire area in contact with the film was observed with a line camera (Links Corporation, raL-4096-24gm). During observation, an LED light source (CS Inc., HLDL3-150X28SW-DF-N) was used to irradiate an area of ​​100 mm in the width direction and 5 mm in the conveying direction with white light. Generally, the wavelength range of white light is approximately 380 nm to 780 nm. The specific foreign matter, PET, has an excitation wavelength peak wavelength of approximately 350 nm and a full width at half maximum of 5 nm. Therefore, the wavelength range of the white light does not overlap with the full width at half maximum range of the PET excitation wavelength. Other conditions, such as processing of the observation results, were the same as in Example 1.

[0072] The results of Examples 1 to 3 and Comparative Example 1 are shown in Table 1.

[0073] [Table 1]

[0074] [Evaluation results] In Examples 1 to 3, only the specific foreign matter (PET) emitted fluorescence when exposed to light, so that during inspection the specific foreign matter was detected as a bright defect and other foreign matter was detected as a dark defect, making it possible to selectively detect and count only the specific foreign matter.

[0075] Furthermore, in Examples 1 and 3, the contact-type collection method was used, so even minute particles could be collected. The minimum size of the specific particles was close to the minimum size measured before the particles were attached to the PET film.

[0076] In Example 3, the collected foreign matter was held in place by the adhesion of the adhesive roll surface, and therefore no foreign matter was observed to fall off after collection.

[0077] Regarding scratches on the web surface after foreign matter collection, in Example 2, foreign matter was collected without contact using a non-contact web cleaner, so no scratches were observed on the web surface after foreign matter collection. In Example 3, the adhesive roll rotated at the same speed as the web conveyance speed, so no scratches were observed on the web surface after foreign matter collection. [Industrial Applicability]

[0078] The present invention is not limited to the inspection of foreign matter adhered to the surface of a web, but can also be used in combination with an X-ray imaging inspection device or other auxiliary device to inspect for various types of foreign matter, but its range of application is not limited to these. [Explanation of symbols]

[0079] 1 Foreign body inspection equipment 2. Collection section 3. Irradiation unit 4 Observation section 5 Observation images 11. Web 12 Transport roll 13 Receiving roll 14 Specific foreign matter 15 Other foreign bodies 21 Fiber materials 22 Support 23 Non-contact web cleaner 24 filters 25 Air supply section 26 Exhaust section 27 adhesive roll 31 Light source 32 Irradiation Light 33 Cut Filter 34 Specular reflection light 41 Area Camera 42 Connection 43 Analysis means 44 line camera 51 Background (Collection Department) A Film transport direction

Claims

1. An apparatus for inspecting a web for adhesion of specific foreign matter during transport, comprising: a collecting section having a foreign matter collecting area for collecting foreign matter including the specific foreign matter adhering to the web; an irradiation unit that irradiates the foreign matter collection area with light; an observation unit that observes the foreign matter collection area irradiated by the irradiation unit, the material constituting the surface of the foreign matter collection region is a material having an excitation wavelength different from that of the specific foreign matter, a material having an excitation fluorescence emission amount equal to or less than the detection limit of the observation section, or a material having no excitation wavelength; the wavelength range of the full width at half maximum of the wavelength of the light irradiated from the irradiating unit at least partially overlaps with the full width at half maximum of the excitation wavelength of the specific foreign matter; Foreign object inspection device.

2. 2. The foreign matter inspection device according to claim 1, wherein the collection unit is an adhesive roll having an adhesive surface as the collection region.

3. 3. The foreign matter inspection device according to claim 1, further comprising a moving means for moving the foreign matter collection area from a position where the foreign matter is collected to a position where the collected foreign matter is observed by the observation unit while being held therein.

4. 4. The foreign matter inspection device according to claim 3, further comprising a driving means for moving said collecting section, separate from a driving means for driving a transport system for transporting the web.

5. A method for inspecting a web for adhesion of specific foreign matter during transport, comprising: foreign matter including the specific foreign matter adhering to the web is collected by a collection unit having a surface made of a material having an excitation wavelength different from that of the specific foreign matter, or a material having an excitation fluorescence emission amount below the detection limit of an observation means, or a material having no excitation wavelength; irradiating a surface of the collecting unit that is collecting foreign matter with light having a wavelength range of full width at half maximum that at least partially overlaps with a wavelength range of full width at half maximum of the excitation wavelength of the specific foreign matter; If the fluorescent wavelength of the specific foreign matter is observed, it is determined that the specific foreign matter has adhered to the web. Foreign object inspection method.

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