Patent Application
20170016837
This Nonprovisional application claims priority under 35 U.S.C. §119 on Patent Application No. 2015-143382 filed in Japan on Jul. 17, 2015, the entire contents of which are hereby incorporated by reference.
The present invention relates to a method of inspecting a defect of a film being carried.
An optical technique is often used in inspection of a defect of a film being carried. Patent Literature 1 discloses defect inspection in which an object to be inspected, such as a film, is inspected for defect in such a manner that visible light and invisible light from a light source are applied to the object and light reflected from the object is received. Patent Literature 2 discloses the use of defect inspection in which an image of light applied to both sides of a film is captured and the image is processed. In a film defect inspection that uses reflection of light in order to inspect a film for defect, a light source and a light-receiving device are arranged on a same side with respect to the film, and light which is emitted from the light source, applied to the film, and then reflected due to a defect such as the presence of a foreign matter is collected at the light-receiving device.
Patent Literature 1
Japanese Patent Application Publication, Tokukai, No. 2014-20910 A (Publication Date: Feb. 3, 2014)
Patent Literature 2
Japanese Patent Application Publication, Tokukai, No. 2008-116437 A (Publication Date: May 22, 2008)
A film being carried often ‘wobbles’, that is, becomes displaced in a direction perpendicular to a surface of the film. The displacement can be suppressed to some extent by creating tension in the film in a longitudinal direction of the film. However, as the tension increases, it becomes more likely that the film being carried stretches or breaks. It is therefore necessary to keep the tension under a certain degree. Further, in a case where the film wobbles, a change unrelated to a defect of the film is caused in intensity of reflected light that is collected at the light-receiving device. The change prevents obtaining an accurate inspection result. This tendency is particularly prominent in a case where the film is a porous separator for a secondary cell or the like, the separator having a low mechanical strength. The problem above is not taken into consideration in the conventional techniques described in Patent Literatures 1 and 2. The present invention is accomplished in view of the problem above. An object of the present invention is accurate measurement of a defect of a film being carried.
In order to attain the object, a film inspection device according to the present invention is a film inspection device including: a light-receiving device generating a signal by receiving light which returns via a film after having been applied to the film, the signal being for detecting a defect included in the film; and a first roller carrying the film while supporting the film from a side opposite to the light-receiving device in a field of view of the light-receiving device.
A film inspection method according to the present invention is a film inspection method including the steps of: (a) generating a signal by receiving light which returns via a film after having been applied to the film, the signal being for detecting a defect included in the film; and (b) carrying the film while supporting the film from a side opposite to the light-receiving device in a field of view of the light-receiving device.
A film production method according to the present invention is a film production method including: each step included in the film inspection method above; and the step of (c) removing a defective portion of the film inspected on the basis of the signal generated in the step (a).
According to the present invention, it is possible to inspect a defect of a film more accurately as compared with a conventional technique. Further, the present invention makes it possible to produce a film having fewer defects as compared with a conventional technique.
The film inspection device 1 is a device which inspects a defect of a film 2 being carried in a Y-axis positive direction. As illustrated in (a) and (b) of
(Film 2)
The film 2 is an imperforate film which has not been processed into a separator for a secondary cell. Note that a separator for a secondary cell is a porous film which separates a positive electrode and a negative electrode of, for example, a lithium ion secondary cell from each other while allowing lithium ions between the positive electrode and the negative electrode to be movable.
Specifically, the film 2 is a film obtained by molding a polyethylene resin composition that is obtained by kneading ultrahigh molecular weight polyethylene and (i) inorganic filler (filler: for example, calcium carbonate or silica) or (ii) plasticizer (for example, low molecular weight polyolefin or liquid paraffin). The polyethylene resin composition is obtained by, for example, kneading 100 parts by weight of ultrahigh molecular weight polyethylene, 100 parts by weight to 400 parts by weight of an inorganic filler, and 5 parts by weight to 200 parts by weight of low molecular weight polyolefin that has a weight-average molecular weight of 10,000 or less.
Note that an object inspected by the film inspection device 1 is not limited to the film 2 described above, and can be any of items listed below. The object to be inspected preferably transmits light to some extent. In this case, it is possible to attain an advantageous effect, described later in the section “Influence of Color and Surface Roughness of Outer Circumferential Surface of Reflecting Roller 13,” by the reflecting roller 13 (i.e., in an electrical signal corresponding to inspection light, a contrast between a normal portion and a defective portion of the film 2 can be enhanced or a noise component can be reduced). Note, however, that the object to be inspected can be a film that does not transmit light at all, such as a metal film having a certain degree of thickness. Also in this case, it is possible to achieve suppression of changes in position and posture of the film 2 in an inspection region with respect to the light-receiving device 12.
A film obtained by removing the inorganic filler or the plasticizer from the above-described film that is obtained by molding the polyethylene resin composition
A stretched film obtained by uni-axially or bi-axially stretching the above film
A film obtained by coating a stretched film with a solution containing aramid, and a laminated film on one side or both sides of which an aramid heat resistant layer is formed by removing a solvent from the solution
A film obtained by coating a stretched film with a solution containing alumina/carboxymethylcellulose, and a laminated film on one side or both sides of which an alumina heat resistant layer is formed by removing a solvent from the solution
A film obtained by coating a stretched film with a solution containing polyvinylidene-fluoride, a laminated film on one side or both sides of which an adhesion layer is formed by removing a solvent from the solution
An optical film
Cloth, paper, pulp, or cellulose
The stretched films and the laminated films above are used as a separator for a secondary cell. In recent years, demand for reducing a thickness of a separator for a secondary cell is increasing, as secondary cells have an increasingly higher capacity. Specifically, a separator having a film thickness of 5 μm to 10 μm for a secondary cell is in demand. Such a film has a particularly low strength and therefore has a particularly high possibility of wobbling, stretching, or breaking. The present invention therefore has a great advantageous effect, which will be described later, on inspection of the above-described separator for a secondary cell.
(Defect of Film 2)
A defect for which the film 2 is inspected by the film inspection device 1 is, for example, the following foreign matter mixed in the film 2.
Metal (iron, stainless steel, aluminum, copper, zinc, brass, etc.)
Gel (ultrahigh molecular weight polyethylene etc.)
Aggregate of filler (calcium carbonate etc.)
Oil droplet
Roller abrasive
Metal oxide (aluminum oxide, chrome oxide, etc.)
Anti-seizure agent (metallic salt)
A foreign matter for which the film 2 is inspected by the film inspection device 1 thus has an optical property different from that of the film 2. Note that a hole, a crease, unevenness, and the like in the film 2 are also encompassed in the examples of a defect for which the film 2 is inspected by the film inspection device 1.
(Carrying Rollers 3a and 3b)
The carrying rollers 3a and 3b are rollers which carry the film 2 in the Y-axis direction by rolling while in contact with the film 2. As illustrated in (a) of
(Light Sources 11a and 11b)
The light sources 11a and 11b applies light to the film 2. Light applied by the light source 11a is visible light. Light applied by the light source 11b is ultraviolet light or infrared light.
As illustrated in (b) of
Note that in a case where light applied from outside of the film inspection device 1 to the film 2 can be used as the light applied to the film 2, the film inspection device 1 does not have to include the light sources 11a and 11b.
(Light-Receiving Device 12)
The light-receiving device 12 is a device which generates a signal for detecting a defect included in the film 2 by receiving light that returns in a Z-axis positive direction via the film 2 after being applied to the film 2 by the light sources 11a and 11b.
Note that examples of the light that returns from the film 2 encompasses (i) light reflected from a surface or an inside of the film 2, (ii) light scattered from the surface or the inside of the film 2, and (iii) light which is transmitted through the film 2 and then reflected or scattered by the reflecting roller 13 so as to be transmitted through the film again. These examples of light are hereinafter correlatively referred to as ‘inspection light’.
The light-receiving device 12 includes a lens which collects inspection light. As illustrated in (b) of
The light-receiving device 12 further includes two charge coupled devices (CCDs) and two optical filters corresponding the respective CCDs. Each of the two CCDs converts collected inspection light into an electrical signal. The two optical filters are provided for the respective two CCDs, and only transmit respective specific light so that one of the two CCDs can convert an optical component from the light source 11a into an electrical signal and the other one of the two CCDs can convert an optical component from the light source 11b into an electrical signal. This allows the light-receiving device 12 to divide collected inspection light into an optical component from the light source 11a and an optical component from the light source 11b and convert each optical component into an electrical signal.
(Reflecting Roller 13)
As illustrated in (a) and (b) of
Accordingly, inspection light received by the light-receiving device 12 is inspection light that is received via a part of the film 2 which part is supported by the reflecting roller 13 on the one surface, that is, via a part at which changes in position and posture of the film 2 with respect to the light-receiving device 12 are suppressed.
Note that the carrying rollers 3a and 3b which carry the film 2 are provided on a same side as the reflecting roller 13 with respect to the film 2, and in a position immediately before the reflecting roller 13 and a position immediately after the reflecting roller 13, respectively, along a carrying path of the film 2.
The reflecting roller 13 reflects or scatters light that is transmitted through the film 2 among light applied by the light sources 11a and 11b to the film 2. An outer circumferential surface, which comes in contact with the film 2, of the reflecting roller 13 is constituted by unmatted white- to ivory-colored vinyl chloride.
In the present application, ‘unmatted’ means that a glossiness (surface state) of the outer circumferential surface, which comes in contact with the film 2, of the reflecting roller 13 as measured by use of, for example, GlossChecker IG-331 (manufactured by HORIBA) is not less than 10 but less than 76 relative to a glossiness of 100 which corresponds to a reflectivity of 10%, according to specular gloss at 60° which is a type of specular gloss measuring method under Japanese Industrial Standard JIS-Z8741.
On the other hand, ‘matted’ means that the glossiness above is not less than 0 but less than 10. In a case where the glossiness is not less than 76, the outer circumferential surface is defined to be a specular surface. For example, the outer circumferential surface which is constituted by vinyl chloride has a glossiness of not less than 60 but not more than 70.
Note that a color of the outer circumferential surface of the reflecting roller 13 in the present embodiment does not need to be white of what is called an achromatic color, as long as the color allows the outer circumferential surface to reflect or scatter light sufficiently. Specifically, it is preferable that the outer circumferential surface has a lightness of not less than 7.0 but not more than 9.5 and a chroma of not less than 0.5 but not more than 3 according to the Munsell color system, although a hue of the outer circumferential surface is not particularly limited. For example, the outer circumferential surface in Embodiment 1 has a hue of 5Y, a lightness of 9, and a chroma of 0.5. In Embodiment 2 which is described later, the outer circumferential surface has a hue of 2.5Y, a lightness of 7.5, and a chroma of 2.
(Inspection Section 14)
As illustrated in (a) and (b) of
The inspection section 14 may be realized by a logic circuit (hardware) provided in an integrated circuit (IC chip) or the like or may be realized by software as executed by a CPU (Central Processing Unit).
In the latter case, the inspection section 14 includes: a CPU that executes instructions of a program that is software realizing the foregoing functions; ROM (Read Only Memory) or a storage device (each referred to as “storage medium”) storing the program and various kinds of data in such a form that they are readable by a computer (or a CPU); and RAM (Random Access Memory) that develops the program in executable form. The object of the present invention can be achieved by a computer (or a CPU) reading and executing the program stored in the storage medium. The storage medium may be “a non-transitory tangible medium” such as a tape, a disk, a card, a semiconductor memory, and a programmable logic circuit. Further, the program may be supplied to or made available to the computer via any transmission medium (such as a communication network and a broadcast wave) which enables transmission of the program. Note that the present invention can also be implemented by the program in the form of a computer data signal embedded in a carrier wave which is embodied by electronic transmission.
<<Operation of Film Inspection Device 1>>
(Inspection of Presence or Absence of Defect)
An intensity of an electrical signal received by the inspection section 14 from the light-receiving device 12 corresponds to an intensity of inspection light from the film 2. In a case where the film 2 has a defect, the intensity of the inspection light changes. As such, the inspection section 14 can inspect whether or not a film 2 to be inspected for a defect has a defect by (i) holding, as a reference value, an electrical signal corresponding to an intensity of inspection light from another film 2 that is defect-less and obtained in advance and (ii) comparing the reference value with an electrical signal to be inspected which corresponds to an intensity of inspection light from the film 2 to be inspected. For example, the inspection section 14 can inspect the presence or absence of a defect by deciding that ‘a defect is present’ in a case where a value obtained by dividing the electrical signal to be inspected by the reference value is smaller than a certain value.
Note that the inspection section 14 can be configured such that the inspection section 14 receives from the light-receiving device 12 a plurality of electrical signals over multiple times, and using an average of the plurality of electrical signals as the reference value or the electrical signal to be inspected. Note here that an electrical signal undergoes variations according to a surface condition of a film 2 even in a case where the film 2 has no defect. By averaging a plurality of electrical signals, the inspection section 14 can obtain an electrical signal in which the variations are suppressed.
(Inspection of Position of Defect)
As illustrated in (a) of
(Inspection of Size of Defect)
As a defect of the film 2 increases in size in the X-axis direction, a range in which the intensity of the electrical signal shown in (a) of
As a defect of the film 2 increases in size in the Y-axis direction, a time period in which an intensity of an electrical signal shown in the graph of (a) of
As described above, the inspection section 14 can inspect a size of the film 2 in X-axis and Y-axis directions.
(Inspection of Type of Defect)
In a case where a type of a defect of the film 2 varies, a degree of a difference between (i) a degree of change, caused between a case where the defect is present and a case where the defect is absent, in intensity (hereinafter referred to as ‘first intensity’) of inspection light corresponding to visible light from the light source 11a and (ii) a degree of change, caused between a case where the defect is present and a case where the defect is absent, in intensity (hereinafter referred to as ‘second intensity’) of inspection light corresponding to infrared light or ultraviolet light from the light source 11b varies. In a case where a defect of the film 2 is, for example, metal, the first intensity and the second intensity change to a similar extent. In a case where a defect of the film 2 is, for example, oil, the second intensity changes by a greater ratio than a ratio by which the first intensity changes. Therefore, it is possible to specify a type of a defect of the film 2 by (i) simultaneously measuring, by use of the light-receiving device 12, the first intensity of the visible light applied by the light source 11a and the second intensity of the infrared light or the ultraviolet light applied by the light source 11b and (ii) comparing the first intensity with the second intensity by use of the inspection section 14.
Note that in a case where of not performing the above-described inspection of a type of a defect, the film inspection device 1 can be configured to include a single light source instead of two light sources.
<<Advantageous Effect of Film Inspection Device 1>>
Since the film inspection device 1 includes the reflecting roller 13 as shown in (a) and (b) of
Therefore, the film inspection device 1 has an advantageous effect of being able to inspect a defect of the film 2 more accurately as compared with a conventional technique. Note that this advantageous effect is achieved not only in a case where the light-receiving device 12 and the reflecting roller 13 are arranged as illustrated in
(Relation Between Field of View of Light-Receiving Device 12 and Positional Arrangement of Reflecting Roller 13)
As shown by broken lines in
Note that a relation between the field of view V of the light-receiving device 12 and a positional arrangement of the reflecting roller 13 is not limited to the above, as long as the film 2 is carried while being supported from the side opposite to the light-receiving device 12 in the field of view of the light-receiving device 12.
For example, the light-receiving device 12 can be moved to a position 12a. In this case, the field of view V is changed to a field of view Va, and the film 2 in the field of view Va is carried while being supported by the reflecting roller 13 from the side opposite to the light-receiving device 12 at an end part of the field of view Va in the Y-axis direction. Note that the position 12a illustrated in
Further, it is also possible to move the light-receiving device 12 to a position 12b and tilt the posture of the light-receiving device 12. Also in this case, the field of view V is changed to the field of view Va and as described above, the film 2 in the field of view Va is carried while being supported by the reflecting roller 13 from the side opposite to the light-receiving device 12 at the end part of the field of view Va in the Y-axis direction. Note that the position 12b illustrated in
In the cases above, inspection light received by the light-receiving device 12 includes inspection light which returns via a part P of the film 2 which part is supported by the reflecting roller 13, that is, via a part P at which changes in position and posture of the film 2 with respect to the light-receiving device 12 are suppressed. Consequently, a change unrelated to a defect of the film 2 is less likely to occur in light intensity of inspection light received by the light-receiving device 12, as compared with an arrangement in which the reflecting roller 13 is not provided. As such, according to the film inspection device 1, the light-receiving device 12 can output a signal which reflects a defect of the film 2 more accurately as compared with a conventional film inspection device that does not include the reflecting roller 13.
Therefore, the film inspection device 1 has an advantageous effect of being able to inspect a defect of the film 2 more accurately as compared with a conventional technique.
(Relation Between Optical Axis of Light-Receiving Device 12 and Positional Arrangement of Reflecting Roller 13)
The light-receiving device 12 collects inspection light by using, as a central axis, an optical axis OA which is a straight line connecting between a center of the lens of the light-receiving device 12 and a focal point of the lens, as indicated by a chain line in
The optical axis OA is in such a positional relation with a rotational axis of the reflecting roller 13 that the optical axis OA perpendicularly intersects with the rotational axis. It is also possible to move the light-receiving device 12 to a position 12c and tilt the posture of the light-receiving device 12, so that the optical axis OA changes to an optical axis OAa. Note that although the position 12c illustrated in
In the cases above, inspection light received by the light-receiving device 12 includes an increased proportion of inspection light that returns via the part P, at which changes in position and posture of the film 2 are suppressed, of the film 2. Accordingly, a change in light intensity that is unrelated to a defect of the film 2 is even less likely to occur.
Note that in a case where the optical axis OA is in such a positional relation with the reflecting roller 13 that the optical axis OA passes through a position of contact between the film 2 and the reflecting roller 13 and perpendicularly intersects with the rotational axis of the reflecting roller 13, that is, in a case where the reflecting roller 13 is in a position facing the light-receiving device 12 via the film 2, inspection light received by the light-receiving device 12 includes an increased proportion of inspection of light that returns via the part P of the film 2. Accordingly, a change unrelated to a defect of the film 2 is still even less likely to occur in light intensity.
(Influence of Color and Surface Roughness of Outer Circumferential Surface of Reflecting Roller 13)
Suppression of changes in position and posture of the film 2 with respect to the light-receiving device 12 in the inspection region is achieved even in a case where inspection light does not include light which is transmitted through the film 2 and then reflected or scattered by the reflecting roller 13 so as to be transmitted through the film 2 again.
On the other hand, in a case where inspection light includes light which is transmitted through the film 2 and then reflected or scattered by the reflecting roller 13 so as to be transmitted through the film 2 again, the following things become possible by adjusting properties (color, surface roughness, etc.) of an outer circumferential surface, which comes in contact with the film 2, of the reflecting roller 13. That is, as shown in the graph of (a) of
As described above, the electrical signal shown in the graph of (a) of
An electrical signal shown in the graph of (b) of
An electrical signal shown in the graph of (c) of FIG. 2 is an electrical signal outputted from the light-receiving device 12 in a case of using a reflecting roller 13 whose outer circumferential surface coming in contact with the film 2 is gray and not matted. As shown in the graph of (c) of
An electrical signal shown in the graph of (d) of
(Film Inspection Method)
The present invention also includes a film inspection method carried out by the film inspection device 1. The film inspection method includes a step (a) of generating a signal by receiving, with use of the light-receiving device 12, inspection light which returns via the film 2 after having been applied to the film 2, the signal being for detecting a defect included in the film 2 and a step (b) of carrying the film 2 while supporting the film 2 from a side opposite to the light-receiving device 12 in the field of view V or the field of view Va of the light-receiving device 12.
The step (a) is a step in which the light-receiving device 12 generates the electrical signal shown in the graph of (a) of
The film inspection method described above makes it possible to inspect a defect of the film 2 more accurately as compared with a conventional technique.
(Film Production Method)
The present invention also encompasses a film production method in which the film inspection method described above is used. The film production method includes a step (c) of removing a defective portion of the film on the basis of a result of receiving light in the step of receiving light, as well as the steps (a) and (b) included in the film inspection method described above.
The step (c) is a step which is carried out on a Y-axis positive direction side of the film inspection device 1 illustrated in (a) and (b) of
The film production method described above enables production of a film 2 having less defects as compared with a film produced by a conventional technique.
In the present embodiment, the same reference signs will be given to members each having the same function as a member described in the embodiment above, and descriptions on such a member will be omitted. The same applies to other embodiments described below.
<<Arrangement of Film Inspection Device 1A>>
<<Operation and Advantageous Effect of Film Inspection Device 1A>>
The film inspection device 1A operates in the same manner as the film inspection device 1, and can inspect a defect of the film 2 more accurately than a conventional technique. Further, in the film inspection device 1A, the carrying rollers 3a and 3b work so as to press the film 2 against the reflecting roller 13. This allows further suppression of changes in position and posture of the film 2 with respect to the light-receiving device 12. Accordingly, the film inspection device 1A can inspect a defect of the film 2 more accurately.
Note, however, that in the film inspection device 1, the carrying rollers 3a and 3b and the reflecting roller 13 are provided on the same side with respect to the film 2. This allows the film inspection device 1 to secure more space for the light sources 11a and 11b and the light-receiving device 12 as compared with the film inspection device 1A. Accordingly, there is more flexibility in providing the light sources 11a and 11b and the light-receiving device 12 in the film inspection device 1.
Note that the present invention encompasses both (i) the above-described film inspection method carried out with use of the film inspection device 1A and (ii) the above-described film production method carried out with use of the film inspection method.
Unlike the reflecting roller 13, the concave reflecting roller 13A has such a shape that a diameter at a central part of the reflecting roller 13A in a rotational axis direction of the reflecting roller 13A gradually decreases as compared with a diameter at both end parts of the reflecting roller 13A. A roller having this shape is often called “reverse crown roller.” The concave reflecting roller 13A thus has a shape by which the film 2 is stretched in the rotational axis direction of the concave reflecting roller 13A.
A depth of the concave reflecting roller 13A at the central part thereof is a value obtained by dividing, by two, a difference between the diameter at both end parts and the diameter at the central part. An optimum value of the depth in inspection of a defect of the film 2 depends on a length of the concave reflecting roller 13A in the rotational axis direction. For example, in a case where the length in the rotational axis direction is 1000 mm, the depth is preferably not greater than 1 mm. Note that an outer circumferential surface, facing the film 2, of the concave reflecting roller 13A is constituted by unmated white vinyl chloride, in the same way as the reflecting roller 13.
<<Operation and Advantageous Effect of Film Inspection Device 1B>>
The film 2 is carried while being in contact with an outer circumferential surface of the concave reflecting roller 13A at both end parts in the rotational axis direction. This causes the film 2 being carried to be stretched outward on the outer circumferential surface at the both end parts, so that a crease or the like that is formed in the film 2 while the film 2 is being carried can be stretched. As a result, formation of a crease or the like in the film 2 is suppressed and, accordingly, a surface state of the film 2 can be more approximated to uniformity. Therefore, with the film inspection device 1B, a change in surface state of the film 2 at a position where the film 2 is inspected for a defect is suppressed, so that a defect of the film 2 can be inspected more accurately.
Note that also in a case where the reflecting roller of the film inspection device 1B is a convex reflecting roller, formation of a crease or the like in the film 2 can be suppressed and, accordingly, the surface state of the film 2 can be more approximated to uniformity. The convex reflecting roller is a reflecting roller whose diameter at a central part of the reflecting roller in a rotational axis direction thereof gradually increases as compared with a diameter at both end parts of the reflecting roller. The present invention encompasses both (i) the above-described film inspection method carried out with use of the film inspection device 1B and (ii) the above-described film production method carried out with use of the film inspection method.
(Replacement of Carrying Roller 3a with Concave Roller Etc.)
The present invention also encompasses a film inspection device in which the carrying roller 3a of the film inspection device 1 illustrated in (a) of
Further, the present invention also encompasses a film inspection device in which the carrying roller 3a of the film inspection device 1B is replaced with a concave roller, a convex roller, or an expander roller. With the film inspection device described above, a change in surface state of the film 2 at a position where the film 2 is inspected for a defect is even more reliably suppressed, so that a defect of the film 2 can be inspected more accurately.
Note, however, that in a case where the carrying roller 3a has a sufficiently well-working function of stretching a crease in the film 2, it may be more preferable that the reflecting roller 13, which is a general reflecting roller (having an outer circumferential surface that is a cylindrical surface), be used instead of the concave reflecting roller 13A having a crease-stretching function. This is for the following reason. That is, in a case where the concave reflecting roller 13A is used, a crease in the film 2 may be stretched in the inspection region due to a crease-stretching function of the concave reflecting roller 13A, then a defect of the film 2 in the inspection region may be shifted, if slightly, in accordance with the stretching, and consequently an error may be included in a position and size of the defect measured by the inspection section 14. In a case where the general reflecting roller 13 is used, on the other hand, such an error is less likely to occur.
As illustrated in (a) of
The arrangement above allows reducing an area of the film 2 from which area each of the plurality of light-receiving devices 12 collects inspection light. This enables, for example, a reduction in diameter of the lens of each of the plurality of light-receiving devices 12. This suppresses deformation of the field of view of the lens and color aberration of the lens. Therefore, the film inspection device 1E can inspect a defect of the film 2 more clearly than the film inspection devices 1 and 1A through 1D, each of which has only a single light-receiving device 12.
As illustrated in (b) of
In contrast to the light-receiving device 12 which includes two CCDs and two optical filters corresponding to the two CCDs, each of the light-receiving devices 12A and 12B includes a pair made up of a CCD and an optical filter.
The optical filter of the light-receiving device 12A transmits only inspection light from the light source 11a. As such, the light-receiving device 12A can detect only inspection light from the light source 11a. The optical filter of the light-receiving device 12B transmits only inspection light from the light source 11b. As such, the light-receiving device 12B can detect only inspection light from the light source 11b. Thus, wavelengths of inspection light respectively received by the light-receiving devices 12A and 12B are different from each other. Note that the inspection section 14 is connected to each of the light-receiving devices 12A and 12B (not shown).
As illustrated in (c) of
With the arrangement above, the film inspection device 1G can inspect a defect of the film 2 more clearly than the film inspection devices 1 and 1A through 1D, each of which has only a single light-receiving device 12.
(Other Light-Receiving Devices)
The light-receiving device 12 can be a light-receiving device which includes (i) a photoreceiver including a lens and (ii) a spectrometer for dispersing inspection light collected by the photoreceiver. In this arrangement, the spectrometer disperses inspection light into spectra so as to divide the inspection light into a component of light from the light source 11a and a component of light from the light source 11b, and converts each of the components into an electrical signal.
Further, the light-receiving device 12 can be a contact image sensor (CIS) module. The CIS module includes a plurality of image pickup devices (e.g., CCDs) arranged in a single direction, optical filters, and a lens array. The optical filters are provided so as to correspond to the respective plurality of image pickup devices, and each of the optical filters transmits only specific light so that a specific image pickup device can convert only specific light into an electrical signal. The lens array is constituted by small lenses which are arranged in the single direction above. The arrangement above allows the CIS module to (i) split collected inspection light into a component of light from the light source 11a and a component of light from the light source 11b and (ii) convert each of the components into an electrical signal.
A film inspection device according to the present invention is a film inspection device including: a light-receiving device generating a signal by receiving light which returns via a film after having been applied to the film, the signal being for detecting a defect included in the film; and a first roller carrying the film while supporting the film from a side opposite to the light-receiving device in a field of view of the light-receiving device.
According to the arrangement above, the light-receiving device receives light which returns via the film after having been applied to the film. The film is carried while being supported by the first roller from the side opposite to the light-receiving device in the field of view of the light-receiving device.
Accordingly, light received by the light-receiving device includes light which returns via a part of the film which part is supported by the first roller, that is, via a part at which changes in position and posture of the film with respect to the light-receiving device are suppressed. Consequently, according to the arrangement above, a change unrelated to a defect of the film is less likely to occur in light intensity of light received by the light-receiving device, as compared with an arrangement in which the first roller is not provided. As such, according to the film inspection device, the light-receiving device can output a signal which reflects a defect of the film more accurately as compared with a conventional film inspection device that does not include the first roller.
Therefore, the film inspection device above can inspect a defect of a film more accurately as compared with a conventional technique.
Note that examples of the ‘light that returns from the film’ encompasses (i) light which returns by being reflected from a surface or an inside of the film, (ii) light which returns by being scattered from the surface or the inside of the film, and (iii) light which, after having been transmitted through the film and then reflected or scattered by the first roller, returns by being transmitted through the film again.
Further, the film inspection device according to the present invention is preferably arranged such that the first roller supports a part of the film which part is passed by an optical axis of the light-receiving device.
According to the arrangement above, light received by the light-receiving device includes an increased proportion of light that returns via the part of the film at which part changes in position and posture of the film with respect to the light-receiving device are suppressed. Accordingly, a change unrelated to the defect of the film is even less likely to occur in light intensity. This makes it possible to inspect the film while carrying the film at high speed.
Further, the film inspection device according to the present invention is preferably arranged such that the first roller is provided at a position facing the light-receiving device via the film.
According to the arrangement above, light received by the light-receiving device includes an increased proportion of light that returns via the part of the film at which part changes in position and posture with respect to the light-receiving device are suppressed. Accordingly, a change unrelated to the defect of the film is still even less likely to occur in light intensity.
Further, the film inspection device according to the present invention is preferably arranged such that light received by the light-receiving device includes the light received by the light-receiving device includes light which, after having been transmitted through the film and then reflected or scattered by the first roller, returns by being transmitted through the film again.
According to the arrangement above, the first roller can function as a reflecting roller. As such, by adjusting properties (color, surface roughness, etc.) of an outer circumferential surface, which comes in contact with the film, of the first roller, (i) a contrast between a part corresponding to a normal part of the film and a part corresponding to a defective part of the film can be enhanced in light received by the light-receiving device and (ii) a noise component included in the light can be reduced. This allows the film inspection device to inspect a defect of the film more accurately.
Further, the film inspection device according to the present invention is preferably arranged such that an outer circumferential surface, which comes in contact with the film, of the first roller has a lightness of not less than 7 but not more than 9.5 according to the Munsell color system and a chroma of not less than 0.5 but not more than 3 according to the Munsell color system.
Further, the film inspection device according to the present invention is preferably arranged such that an outer circumferential surface, which comes in contact with the film, of the first roller has a glossiness of not less than 10 relative to a glossiness of 100 which corresponds to a reflectivity of 10%, according to specular gloss at 60° which is a type of specular gloss measuring method under Japanese Industrial Standard JIS-Z8741.
A foreign matter contained in the film often has a dark color. With the arrangement above, the above-described contrast can be enhanced, so that the film inspection device can inspect a defect of the film more accurately.
Further, the film inspection device according to the present invention is preferably arranged such that the film inspection device further includes a second roller provided at a position immediately before or after the first roller along a carrying path of the film and on a same side as the first roller with respect to the film.
According to the arrangement above, the first roller and the second roller are provided on the same side with respect to the film. This allows securing more space for the light-receiving device. Accordingly, there is more flexibility in providing the light-receiving device in the film inspection device.
Further, the film inspection device according to the present invention is preferably arranged such that the film inspection device further includes a second roller provided at a position immediately before or after the first roller along a carrying path of the film and on a side opposite to the first roller with respect to the film.
According to the arrangement above, the second roller works so as to press the film against the first roller. This allows further suppression of changes in position and posture of the film with respect to the light-receiving device. Accordingly, the film inspection device can inspect a defect of the film more accurately.
Further, the film inspection device according to the present invention is preferably arranged such that the second roller is provided at the position immediately before the first roller along the carrying path of the film, and the second roller has a shape or a mechanism by which the film is stretched in a rotational axis direction of the second roller.
According to the arrangement above, a crease or the like in the film is reliably stretched by the second roller before the film is carried to the first roller. Therefore, with the film inspection device, a change in surface state of the film at a position where the film is inspected for a defect is reliably suppressed, so that a defect of the film can be inspected more accurately.
Further, the film inspection device according to the present invention is preferably arranged such that the first roller has a shape by which the film is stretched in a rotational axis direction of the first roller.
The arrangement above allows the first roller to stretch a crease or the like which is formed in the film while the film is being carried. As a result, formation of a crease or the like in the film is suppressed and, accordingly, a surface state of the film can be more approximated to uniformity. Therefore, with the film inspection device, a change in surface state of the film at a position where the film is inspected for a defect is suppressed, so that a defect of the film can be inspected more accurately.
A film inspection method according to the present invention is a film inspection method including the steps of: (a) generating a signal by receiving light which returns via a film after having been applied to the film, the signal being for detecting a defect included in the film; and (b) carrying the film while supporting the film from a side opposite to the light-receiving device in a field of view of the light-receiving device.
The film inspection method above makes it possible to inspect a defect of a film more accurately as compared with a conventional technique.
A film production method according to the present invention is a film production method including each step included in the film inspection method above; and the step of (c) removing a defective portion of the film inspected on the basis of the signal generated in the step (a).
The film production method above makes it possible to produce a film having fewer defects as compared with a conventional technique.
[Additional Matter]
The present invention is not limited to the embodiments, but can be altered by a skilled person in the art within the scope of the claims. An embodiment derived from a proper combination of technical means each disclosed in a different embodiment is also encompassed in the technical scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-143382 | Jul 2015 | JP | national |
