WO2022239568A1 - ピンホール検出装置 - Google Patents
ピンホール検出装置 Download PDFInfo
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- WO2022239568A1 WO2022239568A1 PCT/JP2022/016408 JP2022016408W WO2022239568A1 WO 2022239568 A1 WO2022239568 A1 WO 2022239568A1 JP 2022016408 W JP2022016408 W JP 2022016408W WO 2022239568 A1 WO2022239568 A1 WO 2022239568A1
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- Prior art keywords
- light source
- light
- optical
- inspected
- pinhole
- Prior art date
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- 238000001514 detection method Methods 0.000 title claims abstract description 38
- 230000003287 optical effect Effects 0.000 claims abstract description 83
- 239000013307 optical fiber Substances 0.000 claims abstract description 50
- 230000000644 propagated effect Effects 0.000 claims abstract description 8
- 230000010287 polarization Effects 0.000 claims description 16
- 230000001902 propagating effect Effects 0.000 claims description 3
- 230000001678 irradiating effect Effects 0.000 claims description 2
- 238000007689 inspection Methods 0.000 description 23
- 239000000835 fiber Substances 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 230000007547 defect Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
- G01N21/892—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles characterised by the flaw, defect or object feature examined
- G01N21/894—Pinholes
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8806—Specially adapted optical and illumination features
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
- G01N21/8901—Optical details; Scanning details
- G01N21/8903—Optical details; Scanning details using a multiple detector array
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8806—Specially adapted optical and illumination features
- G01N2021/8848—Polarisation of light
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
- G01N21/8901—Optical details; Scanning details
- G01N2021/8908—Strip illuminator, e.g. light tube
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
- G01N21/8914—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles characterised by the material examined
- G01N2021/8917—Paper, also ondulated
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
- G01N21/8914—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles characterised by the material examined
- G01N2021/8918—Metal
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2201/00—Features of devices classified in G01N21/00
- G01N2201/06—Illumination; Optics
- G01N2201/061—Sources
- G01N2201/06166—Line selective sources
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2201/00—Features of devices classified in G01N21/00
- G01N2201/06—Illumination; Optics
- G01N2201/063—Illuminating optical parts
- G01N2201/0638—Refractive parts
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2201/00—Features of devices classified in G01N21/00
- G01N2201/08—Optical fibres; light guides
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2201/00—Features of devices classified in G01N21/00
- G01N2201/08—Optical fibres; light guides
- G01N2201/0833—Fibre array at detector, resolving
Definitions
- the present invention relates to a pinhole detection device.
- Patent Document 1 aims to provide a surface defect inspection apparatus that can accurately detect even through defects that are inclined with respect to the thickness direction of an object to be inspected (column 3, line 10- line 13).
- the surface defect inspection apparatus of Patent Document 1 has a light source that irradiates light onto an inspection surface of an object to be inspected, and a detector that detects the amount of transmitted light of the irradiation light.
- An optical lens is provided between the light source and focused onto the detector (column 3, lines 15-20, FIG. 1).
- Patent Document 2 aims to provide a pinhole detection device for a sheet-like object that detects an abnormal portion such as a pinhole formed obliquely to the surface of the sheet-like object (Second column No. line 19 to column 3, line 2).
- the apparatus for detecting an abnormal portion of a sheet-like object of Patent Document 2 includes a laser light source, a lens that disperses a laser beam from the laser light source and converts it into a dispersed beam, and a lens that disperses the laser beam from one side. and a light sensitive means arranged to be sensitive to the transmitted light of said divergent beam on the other side of said sheet-like object.
- the light-sensitive means comprise a photoconductor FO, such as a fiber optic, and a photoelectric conversion element PH (column 4, lines 12-14, drawing).
- Patent Document 3 aims to provide a sheet material pinhole detection device with high detection accuracy (page 4, lines 7 to 8).
- light is irradiated from one side of a traveling sheet material, and light passing through pinholes in the sheet material on the other side is arranged at right angles to the traveling direction of the sheet material.
- the light-receiving ends of the optical transmission fiber are arranged in a plurality of rows in the form of a stack of bales (claim Item 1, Figures 4 to 6).
- Patent Document 1 Although it is explained that the detector (3) detects the transmitted light amount of the irradiation light (column 3, lines 16 to 17, etc.), the specific configuration of the detector (3) is Not explained. Further, in Patent Document 2, a photoconductor FO such as fiber optics and a photoelectric conversion element PH are described as the photosensitive means (Column 4, lines 12 to 14, drawings). No specific consideration has been given to the specification of the FO (optical fiber).
- Patent Document 3 discloses the cross-sectional shape and arrangement of the optical transmission fiber 7 (optical fiber) (page 3, lines 16 to 20, FIGS. 4 to 6, etc.), the optical transmission Other specifications of fiber 7 have not been considered. Therefore, there is room for improvement in pinhole detection accuracy.
- the present invention has been made in consideration of the above problems, and aims to provide a pinhole detection device capable of improving pinhole detection accuracy.
- the pinhole detection device is a light source for irradiating an object to be inspected with light; an optical lens positioned between the light source and the inspected object; a detector for detecting light converged by the optical lens and transmitted through the pinhole of the object to be inspected, the detector comprises an optical fiber that propagates light transmitted through a pinhole in the inspected object;
- the maximum detectable angle of the pinhole with respect to the optical axis of the light source is ⁇
- the maximum incident angle of light that can be propagated through the optical fiber with respect to the optical axis of the light source is in the range of ⁇ + 0° to ⁇ + 5°. characterized by being
- the present invention it becomes easier to prevent disturbance light (or leak light) from entering the optical fiber while ensuring detection of pinholes to be detected. As a result, it is possible to increase the signal/noise ratio (S/N ratio) of the transmitted light and the ambient light, thereby improving the pinhole detection accuracy.
- S/N ratio signal/noise ratio
- the present invention it is possible to suitably use when the inspection object is, for example, strip-shaped.
- the object to be inspected is an object that is stretched in the conveying direction (for example, a steel plate, a film that does not transmit light, or paper), inclined pinholes are likely to occur. In the present invention, it becomes easy to detect pinholes inclined in the conveying direction.
- the light source is a linear light source that linearly irradiates the object to be inspected with light
- the optical lens irradiates the light source and spreads the light in a direction away from the optical axis of the light source.
- the light source converges in a direction approaching the optical axis
- the detector includes a plurality of the optical fibers arranged side by side with respect to the light source, and when the maximum polarization angle of the optical lens is ⁇ 1, the maximum The polarization angle ⁇ 1 may be set to be greater than or equal to the maximum detectable angle ⁇ .
- the maximum incident angle of the light propagating through the optical fiber and the optical axis of the light source is within the range of ⁇ 1+0° to ⁇ 1+5°.
- the present invention has a transport device for moving the object to be inspected in a direction perpendicular to the longitudinal direction of the light source and in a direction perpendicular to the optical axis of the light source, and the
- the end surface of the optical fiber may be arranged at the focal position of the optical lens, or may be arranged closer to the object to be inspected than the focal position of the optical lens.
- pinholes can be easily detected even when the object to be inspected is moved with respect to the pinhole detection device. That is, when the end face of the optical fiber is placed at the focal position of the optical lens, the detector detects the light transmitted through the pinhole with a very sharp rise, but the time to detect the rise is relatively short. . On the other hand, if the end face of the optical fiber is placed closer to the object to be inspected than the focal position of the optical lens, the rise of the pinhole detected by the detector due to the transmitted light is smaller than the former, but the rise can be detected. time is relatively long.
- the judgment criteria include, for example, the signal intensity of the detector and the number of data used for calculating the moving average.
- a first linear Fresnel lens on the light source side arranged along the longitudinal direction of the light source and the first linear Fresnel lens arranged along the longitudinal direction of the light source are arranged between the light source and the detector.
- a second linear Fresnel lens disposed closer to the detector than the Fresnel lens; the first linear Fresnel lens refracts light emitted from the light source into parallel light;
- the maximum polarization angle of light refracted by the second linear Fresnel lens when viewed in the longitudinal direction of the light source is equal to the maximum incident angle with respect to the end surface of the optical fiber, or the maximum incident angle
- the parallel light may be refracted so as to be smaller than . According to the present invention, since parallel light is emitted between the first linear Fresnel lens and the second linear Fresnel lens, it becomes easy to adjust the distance between the two Fresnel lenses.
- FIG. 1 is a perspective view schematically showing the configuration of a pinhole detection device according to one embodiment of the present invention.
- FIG. It is a figure explaining the optical characteristic of the optical lens in the embodiment, and an optical fiber.
- FIG. 1 is a perspective view schematically showing the configuration of a pinhole detection device 10 according to one embodiment of the invention.
- the pinhole detection device 10 detects pinholes 110 produced in an object 100 to be inspected.
- the pinhole detection device 10 has a light source 20 , optical lenses 22 a and 22 b , a detector 24 and a transport device 26 .
- Detector 24 has a plurality of optical fibers 30 and at least one detector element 32 .
- the inspected object 100 is transported by the transport device 26 in the direction of the arrow 120 in FIG.
- the light source 20 irradiates the inspected object 100 with the light 50 .
- the light source 20 is, for example, a linear light source that linearly irradiates the inspected object 100 with light by arranging a plurality of lamps (not shown) in a straight line.
- optical lenses 22a and 22b are positioned between the light source 20 and the inspected object 100. As shown in FIG. When viewed from the light source 20 toward the detector 24 (downward direction in FIG. 1), the optical lenses 22a, 22b converge the light 50 from the light source 20 in a direction perpendicular to the longitudinal direction of the light source 20. . That is, the optical lenses 22a and 22b converge the light emitted from the light source 20 and spreading away from the optical axis of the light source 20 toward the optical axis of the light source 20 .
- the optical lens 22a is a first linear Fresnel lens arranged closer to the light source 20 than the optical lens 22b (hereinafter also referred to as "first linear Fresnel lens 22a" or “first lens 22a”).
- the first lens 22a is arranged along the longitudinal direction of the light source 20, and refracts the light 50 emitted from the light source 20 so as to become parallel light. That is, the first lens 22a refracts the light emitted from the light source 20 and spreading away from the optical axis of the light source 20 so that the light is parallel to the optical axis.
- the optical lens 22b is a second linear Fresnel lens arranged closer to the detector 24 than the first optical lens 22a (hereinafter also referred to as "second linear Fresnel lens 22b" or “second lens 22b").
- the second lens 22b is arranged along the longitudinal direction of the light source 20, and when viewed from the light source 20 toward the detector 24 (downward direction in FIG. 1), the parallel light from the first lens 22a is Converge in a direction perpendicular to the longitudinal direction of the light source 20 . That is, the second lens 22b converges light parallel to the optical axis in a direction approaching the optical axis of the light source 20. As shown in FIG.
- FIG. 2 is a diagram explaining the optical characteristics of the optical lens 22b and the optical fiber 30 in this embodiment.
- ⁇ 1 is the maximum polarization angle of the light 50 refracted by the second lens 22b.
- ⁇ 2 is the maximum angle of incidence of the light 50 that can be propagated through the optical fiber 30 with respect to the optical axis 60 of the light source 20 .
- ⁇ 2′ is an angle of ⁇ 2+5°.
- the second lens 22b refracts parallel light so that the maximum polarization angle ⁇ 1 of the light 50 refracted by the second lens 22b is equal to the maximum incident angle ⁇ 2 with respect to the end face of the optical fiber 30.
- the second lens 22b may refract parallel light so that the maximum polarization angle ⁇ 1 is smaller than the maximum incident angle ⁇ 2.
- the detector 24 detects the light 50 converged by the optical lenses 22 a and 22 b and transmitted through the pinhole 110 of the inspected object 100 .
- the light 50 is transmitted through the oblique pinholes 110 as well.
- the detector 24 has a plurality of optical fibers 30 (optical fibers), at least one detection element 32, and a pinhole determination section (not shown).
- Each optical fiber 30 propagates the light 50 transmitted through the inspected object 100 to the detection element 32 (however, the light 50 with an incident angle larger than the maximum incident angle ⁇ 2 is not propagated by the optical fiber 30).
- the optical fibers 30 are arranged linearly along the longitudinal direction of the light source 20 .
- the end face of the optical fiber 30 on the inspection object 100 side is arranged so as to be parallel to the optical lenses 22 a and 22 b and the inspection object 100 .
- the end face of the optical fiber 30 facing the inspected object 100 is arranged at the focal position of the optical lens 22b.
- the detection element 32 is an element that converts light propagating through the optical fiber 30 into an electrical signal, and may be, for example, a photomultiplier tube, a CdS cell, or the like.
- the pinhole determination section determines the presence or absence of the pinhole 110 based on the output of the detection element 32 .
- the pinhole determination unit is configured to be able to switch the settings of the pinhole 110 determination criteria (signal intensity, the number of data used for calculating the moving average, etc.) according to the type of the inspection object 100, the transport speed, and the like. good too.
- the transport device 26 moves the inspection object 100 in a direction perpendicular to the longitudinal direction of the light source 20 and perpendicular to the optical axis of the light source 20 .
- the conveying device 26 has a roll or the like rotated by an electric motor (not shown), and conveys the inspected object 100 .
- transport device 26 moves inspection object 100 in a direction perpendicular to the longitudinal direction of light source 20 (direction of arrow 120 in FIG. 1). In this embodiment, the inspection object 100 moves, but the light source 20, the optical lenses 22a and 22b, and the detector 24 are fixed.
- the inspected object 100 is strip-shaped and can be, for example, a steel plate, a film that does not transmit light, paper, or the like.
- the inspected object 100 may be extended in the transport direction (the direction of the arrow 120). If the inspection object 100 is a steel plate, its width (the length in the direction perpendicular to the direction of travel) can be, for example, 50 cm to 1 m.
- An example manufacturing method (design method) is as follows.
- the manufacturer determines the maximum detectable angle ⁇ of the pinhole 110 based on the thickness (designed value or actual measurement value) of the inspection object 100 and the hole diameter (assumed value or past actual measurement value) of the pinhole 110. decide.
- the maximum detectable angle ⁇ is the maximum angle that the pinhole 110 to be detected makes with the optical axis 60 ( FIG. 2 ) of the light source 20 when viewed in the longitudinal direction of the light source 20 .
- the maximum detectable angle ⁇ is decreased.
- the manufacturer determines the maximum incident angle ⁇ 2 ( FIG. 2 ) that the light 50 that can be propagated through the optical fiber 30 makes with respect to the optical axis 60 of the light source 20 .
- the maximum incident angle ⁇ 2 is, for example, in the range of the maximum detectable angle ⁇ +0° to ⁇ +5°.
- the specification of the optical fiber 30 that achieves the maximum incident angle .theta.2 is selected.
- the maximum incident angle ⁇ 2 is substantially synonymous with the numerical aperture (NA), and varies depending on the material of the optical fiber 30, the refractive indices of the core and the clad, and the like. Therefore, the manufacturer (designer) selects the optical fiber 30 that achieves the maximum incident angle ⁇ 2.
- the manufacturer sets the specifications of the light source 20 and the lenses 22a and 22b. For example, when the maximum polarization angle of the optical lens 22b is ⁇ 1 (FIG. 2), the manufacturer (designer) sets the maximum polarization angle ⁇ 1 so that the maximum incident angle ⁇ 2 is within the range of ⁇ 1+0° to ⁇ 1+5°. do.
- the maximum detectable angle formed by the pinhole 110 to be detected with respect to the optical axis 60 of the light source 20 is ⁇ .
- the maximum incident angle ⁇ 2 of the light 50 that can be propagated by the light 30 with respect to the optical axis 60 is set in the range of ⁇ +0° to ⁇ +5°.
- the maximum detectable angle of the pinhole 110 with respect to the optical axis 60 of the light source 20 is ⁇
- the maximum incident angle of the light 50 that can be propagated through the optical fiber 30 with respect to the optical axis 60 of the light source 20 is ⁇ +0° to The range is ⁇ +5°.
- the light source 20 is a linear light source that linearly irradiates the inspection object 100 with light. , converges in a direction approaching the optical axis 60 of the light source 20 .
- the detector 24 has a plurality of optical fibers 30 arranged side by side facing the light source 20.
- the maximum polarization angle of the optical lens 22b is ⁇ 1
- the maximum polarization angle ⁇ 1 is set to be greater than or equal to the maximum detectable angle ⁇ . do. This makes it easier to secure the amount of light necessary for detecting the pinhole 110 .
- the end face of the optical fiber 30 facing the inspection object 100 is arranged at the focal position of the optical lens 22b (Fig. 1).
- the end surface of the optical fiber 30 facing the inspection object 100 may be arranged closer to the inspection object 100 than the focal position of the optical lens 22b. This makes it easier to detect the pinholes 110 even when the object to be inspected 100 is moved with respect to the pinhole detection device 10 . That is, when the end surface of the optical fiber 30 is arranged at the focal position of the optical lens 22b, the detector 24 detects the light transmitted through the pinhole 110 with a very sharp rise, while the time required to detect the rise is is relatively short.
- the end face of the optical fiber 30 is arranged closer to the inspected object 100 than the focal position of the optical lens 22b, the rise due to the transmitted light of the pinhole 110 detected by the detector 24 is smaller than the former. , the time to detect the rise is relatively long. Therefore, even if the pinhole 110 cannot be detected with the former arrangement (arrangement at the focal position of the optical lens 22b) due to the movement speed of the inspected object 100, the latter arrangement (with the inspected object 100 side of the focal position) ), a detectable case may occur. Therefore, in the latter arrangement, it is possible to increase the moving speed of the inspected object 100 .
- the transport device 26 moves the inspection object 100 in a direction perpendicular to the longitudinal direction of the light source 20 and perpendicular to the optical axis 60 of the light source 20 (direction of arrow 120) (see FIG. 1).
- the inspected object 100 for example, in a strip shape.
- the conveying direction for example, a steel plate, a film that does not transmit light, paper, etc.
- inclined pinholes are likely to occur.
- a first linear Fresnel lens 22a on the side of the light source 20 arranged along the longitudinal direction of the light source 20 and a first linear Fresnel lens 22a arranged along the longitudinal direction of the light source 20 are provided between the light source 20 and the detector 24 .
- a second linear Fresnel lens 22b arranged closer to the detector 24 than the linear Fresnel lens 22a is provided (FIG. 1).
- the first linear Fresnel lens 22a refracts the light 50 emitted from the light source 20 into parallel light (FIG. 1).
- the second linear Fresnel lens 22b converts parallel light so that the maximum polarization angle ⁇ 1 of the light refracted by the optical lens 22b is equal to or smaller than the maximum incident angle ⁇ 2 with respect to the end face of the optical fiber 30. Bend (FIGS. 1 and 2). As a result, parallel light beams are emitted between the first linear Fresnel lens 22a and the second linear Fresnel lens 22b, making it easy to adjust the distance between the two Fresnel lenses 22a and 22b.
- the present invention is not limited to the above-described embodiments, and can of course adopt various configurations based on the descriptions of this specification. For example, the following configuration can be adopted.
- the light source 20 is a linear light source in the above embodiment (FIG. 1), it may be a light source other than a linear light source. Although one linear light source is used in the above embodiment (FIG. 1), a plurality of light sources 20 may be used as shown in FIG. 5 of Patent Document 1, for example. In the above embodiment, the light source 20 is on the upper side and the detector 24 is on the lower side, but the reverse is also possible.
- the optical fibers 30 are arranged linearly (FIG. 1). However, for example, from the viewpoint of detecting the pinhole 110 over the entire width of the inspection object 100 (the length in the longitudinal direction of the light source 20), the invention is not limited to this.
- the optical fibers 30 may be offset from each other longitudinally of the light source 20 in other arrangements.
- the end surface of the optical fiber 30 facing the inspection object 100 is arranged closer to the inspection object 100 than the focal position of the optical lens 22b (Fig. 1).
- the end surface of the optical fiber 30 may be arranged at the focal position of the optical lens 22b depending on the transport speed of the inspection object 100 or the like.
- the carrier device 26 is used to move the inspection object 100 (FIG. 1), but if attention is paid to the detection of the pinholes 110, the carrier device 26 can be omitted.
- 10 pinhole detector 20 light source (linear light source), 22a optical lens (first linear Fresnel lens), 22b optical lens (second linear Fresnel lens), 24 detector, 26 conveying device, 30 optical fiber, 32 detection element , 50 light, 60 optical axis, 100 inspection object, 110 pinhole, ⁇ maximum detectable angle, ⁇ 1 maximum polarization angle, ⁇ 2 maximum incident angle
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Abstract
Description
被検査対象物に光を照射する光源と、
前記光源と前記被検査対象物の間に配置される光学レンズと、
前記光学レンズにより収束されて前記被検査対象物のピンホールを透過した光を検出する検出器と
を有するものであって、
前記検出器は、前記被検査対象物のピンホールを透過した光を伝播する光学繊維を備え、
前記光源の光軸に対する前記ピンホールを検出可能な最大検出可能角度をθとすると、前記光源の光軸に対する前記光学繊維が伝播可能な光の最大入射角は、θ+0°~θ+5°の範囲である
ことを特徴とする。
[A-1.構成]
(A-1-1.全体構成)
図1は、本発明の一実施形態に係るピンホール検出装置10の構成を簡略的に示す斜視図である。ピンホール検出装置10は、被検査対象物100に生じたピンホール110を検出する。ピンホール検出装置10は、光源20と、光学レンズ22a、22bと、検出器24と、搬送装置26とを有する。検出器24は、複数の光学繊維30と、少なくとも1つの検出素子32とを有する。被検査対象物100は、搬送装置26により図1中、矢印120の方向に搬送される。
光源20は、被検査対象物100に光50を照射する。光源20は、例えば複数のランプ(図示せず)を直線状に配置して被検査対象物100に対して線状に光を照射するリニア光源である。
図1に示すように、光学レンズ22a、22bは、光源20と被検査対象物100の間に配置される。光源20から検出器24に向かう方向(図1における下向き方向)に見たとき、光学レンズ22a、22bは、光源20からの光50を、光源20の長手方向に対して垂直な方向に収束させる。つまり、光学レンズ22a、22bは、光源20から照射され光源20の光軸から離れる方向に広がる光を、光源20の光軸に接近する方向に収束させる。
検出器24は、光学レンズ22a、22bにより収束されて被検査対象物100のピンホール110を透過した光50を検出する。本実施形態では、光学レンズ22a、22bにより光50が収束されているため、斜めのピンホール110についても光50が透過する。
搬送装置26は、光源20の長手方向に対して垂直な方向でかつ光源20の光軸に直交する方向に被検査対象物100を移動させる。搬送装置26は、図示しない電動モータで回転するロール等を有し、被検査対象物100を搬送する。光源20から検出器24に向かう方向に見たとき、搬送装置26は、光源20の長手方向に対して垂直な方向(図1の矢印120の方向)に被検査対象物100を移動させる。なお、本実施形態において、被検査対象物100は移動するが、光源20、光学レンズ22a、22b及び検出器24は固定されている。
被検査対象物100は、帯状であり、例えば鋼板、光を透過しないフィルム、紙等とすることができる。被検査対象物100は、搬送方向(矢印120の方向)に延伸されたものであってもよい。被検査対象物100が鋼板である場合、その幅(進行方向に垂直な方向の長さ)は、例えば、50cm~1mとすることができる。
次に、本実施形態のピンホール検出装置10の製造方法(設計方法)について説明する。本実施形態では、ピンホール検出装置10の検出精度を向上するために各部の仕様を詳細に設定する。一例としての製造方法(設計方法)は下記のようなものである。
本実施形態によれば、光源20(ライン光源)の長手方向に見たとき、検出対象とするピンホール110が光源20の光軸60に対してなす最大検出可能角度をθとすると、光学繊維30が伝播可能な光50が光軸60に対してなす最大入射角θ2は、θ+0°~θ+5°の範囲に設定される。つまり、光源20の光軸60に対するピンホール110を検出可能な最大検出可能角度をθとすると、光源20の光軸60に対する光学繊維30が伝播可能な光50の最大入射角は、θ+0°~θ+5°の範囲である。これにより、検出対象とするピンホール110の検出を確実にしつつ、光学繊維30に外乱光(又は漏洩光)が入り込むことを防ぎ易くなる。その結果、透過光と外乱光の信号/雑音比(S/N比)を高めて、ピンホール110の検出精度を向上させることが可能となる。
なお、本発明は、上記実施形態に限らず、本明細書の記載内容に基づき、種々の構成を採り得ることはもちろんである。例えば、以下の構成を採用することができる。
上記実施形態では、光源20はリニア光源であったが(図1)、リニア光源以外であってもよい。上記実施形態では、1つのリニア光源を用いたが(図1)、例えば特許文献1の第5図のように複数の光源20を用いてもよい。上記実施形態では、光源20が上側、検出器24が下側であったが、逆であってもよい。
上記実施形態では、第1リニアフレネルレンズ22a及び第2リニアフレネルレンズ22bを用いた(図1)。しかしながら、その他のレンズを用いることも可能である。
上記実施形態では、光学繊維30を直線状に配置した(図1)。しかしながら、例えば、被検査対象物100の幅(光源20の長手方向における長さ)全体についてピンホール110を検出する観点からすれば、これに限らない。光学繊維30は、その他の配置で、光源20の長手方向に互いに偏位させてもよい。
上記実施形態では、被検査対象物100を移動させるために搬送装置26を用いたが(図1)、ピンホール110の検出に着目すれば、搬送装置26を設けないことも可能である。
Claims (5)
- 被検査対象物に光を照射する光源と、
前記光源と前記被検査対象物の間に配置される光学レンズと、
前記光学レンズにより収束されて前記被検査対象物のピンホールを透過した光を検出する検出器と
を有するピンホール検出装置であって、
前記検出器は、前記被検査対象物のピンホールを透過した光を伝播する光学繊維を備え、
前記光源の光軸に対する前記ピンホールを検出可能な最大検出可能角度をθとすると、前記光源の光軸に対する前記光学繊維が伝播可能な光の最大入射角は、θ+0°~θ+5°の範囲である
ことを特徴とするピンホール検出装置。 - 前記光源は、前記被検査対象物に対して線状に光を照射するリニア光源であり、
前記光学レンズは、前記光源から照射され該光源の光軸から離れる方向に広がる光を、前記光源の光軸に接近する方向に収束させ、
前記検出器は、前記光源に対向して複数の前記光学繊維が並んで配置され、
前記光学レンズの最大偏光角をθ1とするとき、前記最大偏光角θ1を前記最大検出可能角度θ以上に設定する
ことを特徴とする請求項1に記載のピンホール検出装置。 - 前記光学繊維が伝播可能な前記光が前記光源の光軸となす最大入射角は、θ1+0°~θ1+5°の範囲に含まれる
ことを特徴とする請求項2に記載のピンホール検出装置。 - 前記光源の長手方向に対して垂直な方向でかつ前記光源の光軸に直交する方向に前記被検査対象物を移動させる搬送装置を有し、
前記被検査対象物に面する前記光学繊維の端面は、前記光学レンズの焦点位置に配置される、又は前記光学レンズの焦点位置よりも前記被検査対象物側に配置される
ことを特徴とする請求項1から請求項3のいずれか一項に記載のピンホール検出装置。 - 前記光源と前記検出器の間には、
前記光源の長手方向に沿って配置された前記光源側の第1リニアフレネルレンズと、 前記光源の長手方向に沿って、前記第1リニアフレネルレンズよりも前記検出器側に配置された第2リニアフレネルレンズと
が設けられ、
前記第1リニアフレネルレンズは、前記光源から出射された光を平行光になるように屈折させ、
前記第2リニアフレネルレンズは、前記光源の長手方向に見たときに前記第2リニアフレネルレンズにより屈折した光の最大偏光角が、前記光学繊維の端面に対する最大入射角と同等になる、又は前記最大入射角よりも小さくなるように前記平行光を屈折させる
ことを特徴とする請求項1から請求項4のいずれか一項に記載のピンホール検出装置。
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- 2021-05-10 JP JP2021079607A patent/JP2022173728A/ja active Pending
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2022
- 2022-03-31 EP EP22807272.4A patent/EP4339599A1/en active Pending
- 2022-03-31 WO PCT/JP2022/016408 patent/WO2022239568A1/ja active Application Filing
- 2022-03-31 KR KR1020237041538A patent/KR20240007189A/ko unknown
- 2022-03-31 CN CN202280029381.9A patent/CN117203517A/zh active Pending
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JPS5034586A (ja) | 1973-07-27 | 1975-04-02 | ||
JPS5360284A (en) * | 1976-11-11 | 1978-05-30 | Matsumoto Kikai Setsukei Jimus | Pinhole detector |
JPS55116256U (ja) | 1979-02-09 | 1980-08-16 | ||
JPS6125042A (ja) | 1984-07-13 | 1986-02-03 | Sumitomo Metal Ind Ltd | 表面欠陥検査装置 |
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JP2022173728A (ja) | 2022-11-22 |
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