JP2010043985A - Optical fiber inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a precise optical fiber inspection apparatus that is compact and is easily controlled. <P>SOLUTION: The optical fiber inspection apparatus 10 includes: a light introduction section 12; an image acquisition section 14; and an image processing section 16. The light introduction section 12 includes: a light source 18; and a shielding chamber 20 capable of essentially confining light L emitted by the light source 18. The shielding chamber 20 introduces the confined light L from the entire periphery of one portion F1 of an optical fiber F to the optical fiber F. The image acquisition section 14 has one or a plurality of cameras 22 disposed at the side of another portion F2 of the optical fiber F located outside the shielding chamber 20 independently of the shielding chamber 20. The camera 22 images the side of another portion F2 of the optical fiber F for radiating one portion of light L introduced in the shielding chamber 20 from a plurality of directions at a predetermined angle of field V, and obtains a plurality of side images I expressing images over the entire periphery of another portion F2. The image processing section 16 processes a plurality of side images I obtained by the camera 22 each, and detects defects D in the respective side images I. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical fiber inspection apparatus.

  Of various optical fibers as optical transmission devices, side-emitting optical fibers that emit light by radiating part of visible light transmitted in the length direction from the outer peripheral surface are used for lighting, signs, displays, etc. Widely used. Patent Document 1 discloses a core material made of a light-transmitting resin capable of transmitting light in a side-emitting optical fiber, and a cladding material covering the periphery of the core material, in which light scattering particles are dispersed in the light-transmitting resin The structure provided with the clad material made to be described is described. Patent Document 1 describes a technique for injecting and polymerizing a raw material of a core material into an extruded hollow clad material as a method for producing this optical fiber.

  In the above-described side-emitting optical fiber, defects such as contamination of foreign materials and bubbles, damage to the cladding material, and adhesion of foreign materials may occur in the manufacturing process. When such a defect is to be detected by the operator's visual observation, there is a concern that the operator may have a difference in judgment criteria or cause erroneous detection or oversight.

  Regarding detection of defects in a resin optical fiber, Patent Document 2 describes an apparatus for automatically detecting internal defects in an optical fiber continuously running on a production line. This defect detection apparatus shoots a light irradiating means for irradiating light from a direction intersecting the axis of the optical fiber and an optical fiber irradiated by the light irradiating means from a direction intersecting with the irradiation light of the light irradiating means. Light intensity distribution acquisition means for obtaining a light intensity distribution in the radial direction, and light intensity distribution from the light intensity distribution acquisition means are continuously acquired in the axial direction of the optical fiber, and internal defects are determined based on the light intensity distribution. Determination means. As an embodiment, there is described a configuration in which three combinations of a light irradiator and a line sensor camera are provided, and these combinations are arranged at regular intervals in the traveling direction of the optical fiber and shifted by 120 ° in the circumferential direction. .

  Patent Document 2 states that “in order to inspect the outer circumference without omission, inspection from at least three directions is necessary, but the number of directions in which the inspection apparatus is arranged may be increased. Most preferably, there are three directions, because if the arrangement direction of the inspection apparatus is increased too much, it is necessary to dispose the inspection apparatus at regular intervals so that illumination light from other inspection systems does not become disturbance light. A large number of inspection devices are arranged on the traveling path, which is not preferable because the inspection device becomes excessively large, and the duplication of the inspection part becomes large, so that the control becomes complicated in order to synchronize with another inspection device. (Paragraph [0018]).

JP 2006-317844 A JP-A-2005-283465

  When the light irradiator and the line sensor camera are arranged at positions where the optical axes intersect each other with the optical fiber as the center, as in the optical fiber defect detection device described in Patent Document 2, the optical fiber In order to dispose a plurality of line sensor cameras around the optical fiber, it is necessary to dispose them at a sufficient interval in the traveling direction of the optical fiber, resulting in an excessively large apparatus size. Further, the control of each imaging operation is complicated for a plurality of line sensor cameras arranged at intervals in the traveling direction of the optical fiber. In addition, the light intensity distribution in the radial direction of the optical fiber is obtained using the light emitted from the light irradiator in an open environment, so the efficiency of light introduction into the optical fiber is low, and highly accurate defect determination It is considered difficult to perform.

  An object of the present invention is to provide a high-precision optical fiber inspection apparatus that is small and easy to control in an optical fiber inspection apparatus that detects defects in an optical fiber.

  In order to achieve the above object, one embodiment of the present invention is a light introduction unit that introduces light into an optical fiber, which can substantially confine light emitted from the light source and the light emitted from the light source and the length of the optical fiber. A light introducing portion configured to introduce the confined light into the optical fiber from the entire circumference of a portion of the received optical fiber, and introduce the light. An image acquisition unit for acquiring a side image of the optical fiber, wherein one or a plurality of cameras are arranged independently of the shielding room on the side of the other part in the longitudinal direction of the optical fiber outside the shielding room. One or more cameras image the side of the other part of the fiber that emits part of the light introduced in the shielding room from a plurality of directions at a predetermined angle of view, and the entire circumference of the other part Multiple side images that represent images across An image acquisition unit, and processing one or more of the side view image in which a plurality of cameras are acquired individually, to provide an optical fiber inspection apparatus includes an image processing unit for detecting a defect in each of the side image.

  According to the optical fiber inspection apparatus of one aspect of the present invention, light can be introduced into an optical fiber very efficiently from the entire circumference of a part of the optical fiber in a shielding chamber that can confine light from the light source. . In addition, since the camera arranged independently from the shielding room is configured to capture the other side of the optical fiber that emits side light in the same manner as in actual use and acquire the side image of the other part, the light introduction unit Regardless of the configuration, the image acquisition unit can be freely designed with priority given to the ease of camera placement and control. Therefore, the optical fiber inspection apparatus can effectively reduce the overall dimensions, can easily control the imaging operation of the camera, and can perform highly accurate defect detection with a sufficient amount of light.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Corresponding components are denoted by common reference symbols throughout the drawings.
FIG. 1 shows a basic configuration of an optical fiber inspection apparatus 10 according to the present invention. The optical fiber inspection apparatus 10 can be suitably used for automatically detecting defects in a side-emitting optical fiber.

  The optical fiber inspection apparatus 10 includes a light introducing unit 12 that introduces light L into the optical fiber F, an image obtaining unit 14 that obtains a side image I of the optical fiber F into which the light L has been introduced, and a side surface of the obtained optical fiber F. And an image processing unit 16 that processes the image I and detects a defect D in the side image I. The light introducing unit 12 includes a light source 18 and a shielding chamber 20 that can substantially confine the light L emitted from the light source 18 and can receive a part F1 in the length direction of the optical fiber F. The shielding chamber 20 is formed so as to introduce the confined light L into the optical fiber F from the entire circumference of the portion F1 of the received optical fiber F. The image acquisition unit 16 includes one or a plurality of cameras 22 arranged independently of the shielding chamber 20 on the side of the other portion F2 in the length direction of the optical fiber F outside the shielding chamber 20. The one or more cameras 22 image the side surface of the other portion F2 of the optical fiber F that emits a part of the light L introduced in the shielding room 20 from a plurality of directions at a predetermined angle of view V, A plurality of side images I representing images over the entire circumference of the other portion F2 are acquired. The image processing unit 16 individually processes a plurality of side images I acquired by one or a plurality of cameras 22 to detect a defect D in each side image I.

  As shown in FIG. 2, the optical fiber F as an inspection object of the optical fiber inspection apparatus 10 is composed of a core material C1 made of a light transmissive resin capable of transmitting light and a light transmissive resin covering the periphery of the core material C1. For example, it has a side emission type configuration described in Patent Document 1 described above. The side-emitting optical fiber F is intentionally formed from the outer peripheral surface through the clad material C2 while transmitting the light introduced into the core material C1 from the one end surface E1 in the length direction toward the other end surface E2 in the length direction. Side leakage (self-emission) can be performed over the entire length by leaking a part of the light. As described in Patent Document 1, this type of optical fiber F can be produced by injecting and polymerizing the raw material of the core material C1 into the extruded hollow clad material C2. In this manufacturing process, Defects such as contamination of foreign material and bubbles into the material C1, damage to the clad material C2, and foreign material adhesion may occur. These defects may be observed by human vision as local defects (light defects or dark defects) in the light emitting surface when the optical fiber F emits side light.

  In the side-emitting optical fiber F, a visible defect that occurs on the light-emitting surface generally lowers the commercial value. Therefore, it is desirable to remove a portion that causes such a defect before shipping the optical fiber F as a product. It is. The optical fiber inspection apparatus 10 introduces light L into the core material C1 from the entire circumference of the part F1 having a predetermined length of the optical fiber F, so that the optical fiber F is in a self-light-emitting state similar to the actual use state. By taking the side image I of the light-emitting optical fiber F with the camera 22 and appropriately processing the image, the defect (bright defect or dark defect) D in the side image I is automatically replaced instead of human vision. It is to detect automatically. The image processing method will be described later.

  Here, for simplification, when the light transmission characteristic (that is, the light emission characteristic) of the optical fiber F is introduced into the core material C1 from the one end face E1 of the optical fiber F having the full length K, While the light L is transmitted to the end face E2, it is assumed that the light L having a light quantity of 0.5α is uniformly emitted from the entire circumference of the cladding material C2 over the entire length K (that is, transmission loss of 50%) ( Figure 2). Then, a configuration in which the portion F1 having the length K / 20 is received in the shielding chamber 22 and the light L is introduced into the core material C1 from the entire circumference of the portion F1 will be considered. In this case, since the leakage rate (transmission loss) in the portion F1 is 2.5%, if the light introduction rate is regarded as the same as the leakage rate, the portion F1 is irradiated with the light L having the light amount 40α in the shielding chamber 22. By doing so, it is considered that the light L having the light amount of 0.5α can be emitted from the side surface at the portion F2 outside the shielding chamber 22 in the same manner as when the light L having the light amount α is introduced from the one end face E1.

  Based on the above theory, the optical fiber inspection apparatus 10 having the above-described configuration is very efficient for the light L from the entire circumference of the portion F1 of the optical fiber F in the shielding chamber 20 in which the light L of the light source 18 can be confined. (That is, approximate to the theoretical value) can be introduced into the optical fiber F. Further, the camera 22 arranged independently from the shielding room 20 images the other part F2 of the optical fiber F that emits side light (self-emission) in the same manner as in actual use, and obtains a side image I of the other part F2. Since it is the structure to acquire, the desired number of cameras 22 can be arrange | positioned in a desired position, without considering the influence of the light L in the light introduction part 12. FIG. That is, regardless of the configuration of the light introduction unit 12, the image acquisition unit 14 can be freely designed with priority given to the ease of arrangement and control of the camera 22. Therefore, the optical fiber inspection apparatus 10 can effectively reduce the overall dimensions, can easily control the imaging operation of the camera 22, and can perform highly accurate defect detection with a sufficient amount of light.

  The optical fiber inspection device 10 uses the high leakage rate of light that has passed through the cladding material C2 of the side-emitting optical fiber F, and the core material C1 from the entire outer peripheral surface of the cladding material C2 in the portion F1 having a predetermined length. In this configuration, light L is introduced. With such a configuration, the optical fiber inspection apparatus 10 can uniformly inspect the optical fiber F that is continuously sent in the length direction as the molding process proceeds, for example, in an optical fiber production line. By incorporating the optical fiber inspection device 10 into the optical fiber production line, for example, a control device (not shown) that controls the production line in an integrated manner has a defect in the side image I of the optical fiber F detected by the image processing unit 16. The actual position of the defect of the optical fiber F that is continuously fed is specified from the position information of D, and the part having the defect of the optical fiber F is cut and removed in the cutting process subsequent to the inspection process. Can do.

  Here, an area sensor camera having a predetermined angle of view V can be employed as the camera 22 of the image acquisition unit 14. According to this configuration, regardless of the feeding speed of the optical fiber F and even when the feeding speed fluctuates during the inspection, the predetermined length region of the other portion F2 of the optical fiber F corresponding to the angle of view V can be reduced. Since the side still image can be acquired, the detection accuracy of the defect D by the image processing unit 16 can be maintained. On the other hand, when the camera 22 is a line sensor camera, when the feeding speed of the optical fiber F varies during inspection, the dimension of the defect D processed by the image processing unit 16 in the fiber feeding direction varies on the image. Therefore, for example, it becomes difficult to stably identify the defect D by comparison with the threshold value. Further, by adopting an area sensor camera as the camera 22, in the optical fiber inspection device 10, the optical fiber F that has been cut to a predetermined length in a stationary manner with respect to the light introduction unit 12 and the image acquisition unit 14. Defect inspection can also be performed. In this case, the camera 22 can be configured to be movable in the length direction of the optical fiber F as necessary.

  In the optical fiber inspection apparatus 10, in order for the image acquisition unit 14 to acquire a plurality of side images I representing an image over the entire outer peripheral surface of the other part F2 of the optical fiber F, for example, the other part F2 of the optical fiber F A plurality of cameras 22 can be distributed and fixedly arranged in the circumferential direction. In this case, the plurality of cameras 22 captures the side surface portions of the other portion F2 of the optical fiber F that is emitting light over different central angle regions from a plurality of different directions at respective predetermined angles of view V. , Different side images I are acquired. Then, when all of these side images I are combined, a composite image (preferably a certain amount of overlapped portions) that expresses the entire side surface (outer peripheral surface) of the other portion F2 of the optical fiber F so that a non-imaging portion does not occur. It is only necessary to position the individual cameras 22 so as to obtain the above. Here, since the individual cameras 22 are independent of the shielding box 20 of the light introducing unit 12, the cameras 22 can be collectively arranged on one virtual plane orthogonal to the axis of the optical fiber F. it can. According to such an arrangement, it is only necessary for the plurality of cameras 22 to simultaneously acquire the side images I assigned to the optical fiber F that is continuously fed, so that the control of the imaging operation of the cameras 22 is extremely easy. become.

  Instead of the above configuration in which the image acquisition unit 14 includes a plurality of cameras 22, the image acquisition unit 14 includes a single camera 22 that is arranged to be movable in the circumferential direction around the other portion F2 of the optical fiber F. It can also be configured. In this case, one camera 22 moves in the circumferential direction around the other portion F2 on one virtual plane orthogonal to the axis of the optical fiber F, and the side surface across different central angle regions of the other portion F2. A part is imaged sequentially and the several side image I is acquired. Then, when all of these side images I are combined, a composite image (preferably a certain amount of overlapped portions) that expresses the entire side surface (outer peripheral surface) of the other portion F2 of the optical fiber F so that a non-imaging portion does not occur. It is only necessary to set the imaging timing of the camera 22 so that it can be obtained.

  When the optical fiber inspection apparatus 10 inspects the optical fiber F sent continuously in the length direction, either of the configuration using the plurality of cameras 22 described above or the configuration using one camera 22 is used. The camera 22 also acquires a plurality of side images I at time intervals set in accordance with the feed speed of the optical fiber F so that no non-imaging portion is generated when viewed in the length direction of the optical fiber F. It is desirable. Thereby, the entire optical fiber F continuously fed in accordance with the progress of the molding process in the production line can be inspected uniformly and surely. The control of the imaging operation of the camera 22 can be executed by, for example, a CPU (central processing unit) of the image processing unit 16 or by a camera control device (not shown) prepared separately from the image processing unit 16. It can also be executed.

  Next, the configuration of the optical fiber inspection device 30 according to one embodiment of the present invention will be described with reference to FIGS. Since the optical fiber inspection device 30 has the same basic configuration as the optical fiber inspection device 10 described above, the corresponding components are denoted by common reference numerals, and detailed description thereof is omitted.

  The optical fiber inspection device 30 includes a base 32, a pair of shielding chambers 20 fixed on the base 32 with a space therebetween, and a pair of light sources 18 individually connected to the shielding chambers 20. (FIGS. 3 and 4). Each shielding chamber 20 includes a surrounding wall 34 that defines an internal section, and a pair of openings 36 and 38 that communicate the internal space and the external environment are coaxially formed at positions facing each other on the surrounding wall 34 ( FIG. 5). The openings 36 and 38 function as an inlet 36 and an outlet 38 of the optical fiber F that is continuously fed. Further, the pair of shielding chambers 20 are arranged on the base 32 with the outlet 38 of the shielding chamber 20 upstream in the fiber feeding direction and the inlet 36 of the shielding chamber 20 downstream in the fiber feeding direction facing each other in a coaxial arrangement. Installed (FIG. 5). The optical fiber F is smoothly fed in the length direction through both the shielding chambers 20 with its own axis Fa extending straight.

  A pair of guide bushes 40 having guide holes arranged coaxially with respect to all the inlets 36 and the outlets 38 are fixedly installed on the base 12 outside the pair of shielding chambers 20. The guide bushes 40 support the optical fiber F so that the optical fiber F can be continuously fed with its axis Fa extending straight. Further, on the outside of one guide bush 40, a cross guide roller device 42 (FIG. 6) capable of adjusting the guide diameter according to the change of the outer diameter of the optical fiber F is installed. The cross guide roller device 42 centers and supports the optical fiber F that is continuously fed with high accuracy.

  Each light source 18 includes a metal halide lamp and a halogen lamp, and is connected to a corresponding shielding chamber 20 via a light supply tube 44 containing an optical waveguide (for example, an optical fiber). A pipe connection port 46 for connecting the light supply pipe 44 is formed in the surrounding wall 34 of the shielding chamber 20 independently of the inlet 36 and the outlet 38 (FIGS. 5 and 6). With this configuration, the internal space of the shielding chamber 20 is isolated from the heat generated by the light source 18. One common light source 18 can be connected to the pair of shielding chambers 20. Alternatively, when the amount of light is insufficient, a plurality of light sources 18 can be connected to each shielding chamber 20 via a plurality of light supply tubes 44.

  The shielding chamber 20 substantially confines the light supplied from the light source 18 in the internal space by the surrounding wall 34 (that is, only allowing slight leakage through the gap between the inlet 36 and the outlet 38 and the optical fiber F). be able to. Here, a reflection surface 48 that internally reflects light from the light source 18 is formed on the inner surface of the surrounding wall 34. As schematically shown in FIG. 7, the reflecting surface 48 of the surrounding wall 34 is reflected by the outer surface of a part F1 of the optical fiber F received in the inner space by internally reflecting the light L supplied from the light source 18. The light L and the light L emitted from the portion F1 are reused, and the light L is introduced into the portion F1 with high efficiency (FIG. 7A). As a result, side light emission with a sufficient amount of light can be stably generated in the other portion F2 of the optical fiber F outside the shielding chamber 20, and the image acquisition unit 14 (camera 22) and the image processing unit 16 can further increase the height. Accurate defect detection (including accurate shape recognition of defects) can be performed. The reflecting surface 48 is formed, for example, by forming a thin film layer (nickel plating, gold plating, multilayer dielectric film, etc.) on the surface of the surrounding wall 34 made of carbon steel, or polishing the surface of the stainless steel surrounding wall 34. Can be formed.

  Further, the shielding chamber 20 can be provided with a fiber guide tube 50 extending outward from the shielding chamber 20 in at least one of the inlet 36 and the outlet 38 (both in the drawing) (FIG. 5). The fiber guide tube 50 functions as an auxiliary guide that suppresses unintentional misalignment of the optical fiber F, and acts to prevent leakage of the light L from the internal space of the shielding chamber 20 as much as possible (FIG. 7). (B)). With this configuration, the influence of the light L in the shielding room 20 on the camera 22 can be significantly reduced.

  In the optical fiber inspection device 30, four cameras 22 are fixedly arranged at equal intervals in the circumferential direction on the side of the other portion F <b> 2 of the optical fiber F extending between the pair of shielding chambers 20. (FIG. 3, FIG. 4, FIG. 6). The cameras 22 extend so that each lens optical axis 22a intersects the axis Fa on one virtual plane orthogonal to the axis Fa of the optical fiber F, and the lens optical axes 22a of the cameras 22 adjacent in the circumferential direction. Are fixedly installed on the base 32 at positions extending so as to intersect at an angle of 90 ° with respect to the axis Fa of the optical fiber F. Each camera 22 images the side surface portion of the other portion F2 of the optical fiber F that is emitting light over different central angle regions from four different directions at respective predetermined angles of view V (FIG. 1), Different side images I are acquired. A through hole 52 is formed at a corresponding position of the base 32 in order to enable imaging by the camera 22 installed below the base 32 (FIG. 5).

  For example, when four side images I acquired by four cameras 22 arranged at a central angle of 90 ° are combined with an optical fiber F having a diameter of several mm to several tens of mm, the other part F2 of the optical fiber F is combined. In order to obtain a composite image (preferably including some overlapped portion) that expresses the entire side surface (outer peripheral surface) of the optical fiber so that a non-imaging portion does not occur, each camera 22 has an optical fiber. It is only necessary to have an angle of view V of several mm to several tens of mm that approximates the diameter of F. Here, as the two-dimensional image of the side surface of the optical fiber F that is a cylindrical bulging curved surface, a relatively high-precision image can be obtained for the central region in the radial direction where the rate of change in the distance from the camera 22 is small. In the regions at both ends in the radial direction where the rate of change of the distance from the camera 22 is large, the contour of the image tends to be unclear. Therefore, even if one camera 22 can image the side surface of the other portion F2 of the optical fiber F over the entire radial direction (that is, over a central angle of 180 °), it includes high accuracy including accurate shape recognition of defects. In order to realize this defect detection, it is desirable to use three or more cameras 22 arranged at equal intervals in the circumferential direction.

  In the optical fiber inspection device 30, the length of the optical fiber F is determined based on the feed speed of the optical fiber F acquired by the image processing unit 16 or another camera control device (not shown) from a speed detector (not shown) (not shown). The imaging timings of the four cameras 22 are set so that a non-imaging part does not occur when viewed in the vertical direction, and the cameras 22 are caused to capture a plurality of side images I at regular time intervals. At this time, the defect detection accuracy can be improved by acquiring the side image I so that the overlapping portion of the optical fiber F in the length direction becomes sufficiently large.

  By being incorporated in the optical fiber production line, the optical fiber inspection device 30 can uniformly and reliably inspect the entire optical fiber F that is continuously sent in the length direction as the molding process proceeds. Then, for example, a control device (not shown) that integrates and controls the production line continuously feeds the optical fiber F from the position information of the defect D in the side image I of the optical fiber F detected by the image processing unit 16. The actual position of the defect of the optical fiber F can be specified, and the part having the defect of the optical fiber F can be cut and removed in the subsequent cutting process (not shown) of the optical fiber inspection apparatus 30.

  According to the optical fiber inspection apparatus 30 having the above-described configuration, an exceptional effect equivalent to that of the optical fiber inspection apparatus 10 described above can be achieved. In particular, in the optical fiber inspection apparatus 30, since the reflection surface 48 that internally reflects the light L from the light source 18 is formed on the inner surface of the shielding chamber 20, the light L is introduced into the portion F 1 of the optical fiber F with extremely high efficiency. Can do. In addition, since the shielding chamber 20 is disposed on both sides of the image acquisition unit 14 (camera 22) when viewed in the length direction of the optical fiber F, the amount of side light emission in the other portion F2 of the optical fiber F is increased to increase the length. Side light can be emitted with a uniform amount of light over the entire length. As a result, the optical fiber inspection device 30 stably generates side light emission with a sufficient amount of light in the other part F2 of the optical fiber F, and the defect detection (more accurately detected by the image acquisition unit 14 and the image processing unit 16). Accurate shape recognition of defects) can be performed.

  An example of the image defect detection method by the image processing unit 16 in the optical fiber inspection apparatus 30 described above will be described below with reference to the image example of FIG. 8 and the flowchart of FIG.

  First, it is assumed that the side image I of the other portion F2 of the optical fiber F as shown in FIG. The image processing unit 16 stores the side image I received from the camera 22 in an image memory (not shown). As the first stage of image processing, the image processing unit 16 performs shading correction on the side image I so as to make the brightness of the entire image uniform (step S1). Next, normalization is performed on the corrected side image Is to obtain a normalized image In in which the average value of gradation for each pixel is 128 in 256 gradations (step S2).

  Next, the image processing unit 16 binarizes the normalized image In using two gradation threshold values T1 (for example, T1 = 140) and T2 (for example, T2 = 115), and performs the first processing based on T1. A binarized image Ib1 and a second binarized image Ib2 based on T2 are generated (step S3). Next, blob processing is performed on white pixels in the first binarized image Ib1, and blob processing is performed on black pixels in the second binarized image Ib2 (step S4). FIG. 8B shows the first binarized image Ib1 after the blob processing in step S4. In the image, a portion surrounded by a broken line is a blob.

  Then, the image processing unit 16 compares each blob with a predetermined reference value with respect to a specific inspection parameter in each of the first and second binarized images Ib1 and Ib2, and regards each blob as a defect. Is determined (step S5). Here, as the inspection parameter, a blob area (number of pixels), a major axis dimension (number of pixels), a minor axis dimension (number of pixels), a long / short aspect ratio, and the like can be adopted. As an example, a white blob having a major axis dimension of 0.7 mm or more is regarded as a bright defect, and a black blob having a major axis dimension of 0.3 mm or more is regarded as a dark defect.

  In step S5, the blob that is regarded as a defect in the first binarized image Ib1 is treated as meaning a bright defect that can be recognized by human eyes when the optical fiber F emits side light. The position information and the like are stored in the memory by the image processing unit 16 (step S6). In addition, the blob that is regarded as a defect in the second binarized image Ib2 is treated as a dark defect that can be recognized visually by humans when the optical fiber F emits side light, and its position information Are stored in the memory by the image processing unit 16 (step S6). In this way, detection of defects in one side image I is completed.

  The image processing unit 16 performs the above-described defect detection flow on all the side images I acquired by the four cameras 22. Thereby, the position of the defect of the optical fiber F is automatically specified in the production line. Here, as a defect in the optical fiber F, for example, the mixing of bubbles in the core material C1 is visually recognized as a bright defect when the optical fiber F emits side light, and the adhesion of foreign matter to the cladding material C2 is caused by the optical fiber. When F emits side light, it is visually recognized as a dark defect. The optical fiber inspection apparatus 30 automatically detects defects (bright defects or dark defects) generated during the light emission of the optical fiber F due to such defects automatically instead of human vision and with high accuracy as described above. Can be detected.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the structure and the number of the light source 18, the shielding room 20, and the camera 22 can be selected as appropriate in consideration of the required inspection accuracy and inspection cost. In addition, as an inspection object, other optical fibers such as a side-emitting optical fiber having only a core without a clad and a communication optical fiber before attaching a jacket (jacket) can be inspected.

It is a functional block diagram which shows the basic composition of the optical fiber inspection apparatus which concerns on this invention. It is sectional drawing of the optical fiber to be examined. 1 is a front view schematically showing an overall configuration of an optical fiber inspection apparatus according to an embodiment of the present invention. It is a schematic plan view of the optical fiber inspection apparatus of FIG. It is a figure which shows one component of the optical fiber test | inspection apparatus of FIG. 3, (a) A cross-sectional view and (b) A longitudinal cross-sectional view. It is a perspective view which shows the principal part of the optical fiber test | inspection apparatus of FIG. It is a figure which shows typically one component of the optical fiber test | inspection apparatus of FIG. 3, (a) Sectional drawing orthogonal to an optical fiber axis line, (b) Sectional drawing parallel to an optical fiber axis line. It is a figure explaining an example of the image processing in the optical fiber inspection apparatus of this invention, (a) The example of an image which the camera acquired, (b) The example of an image in the middle of image processing is shown. It is a flowchart explaining an example of the image processing in the optical fiber inspection apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 30 Optical fiber inspection apparatus 12 Light introducing part 14 Image acquisition part 16 Image processing part 18 Light source 20 Shielding room 22 Camera 36 Inlet 38 Outlet 48 Reflecting surface 50 Fiber guide cylinder

Claims (7)

A light introducing portion for introducing light into an optical fiber, comprising: a light source; and a shielding chamber capable of substantially confining light emitted from the light source and receiving a part of the length of the optical fiber. A light introducing portion formed to introduce the confined light into the optical fiber from the entire circumference of the received portion of the optical fiber;
An image acquisition unit for acquiring a side image of an optical fiber into which light has been introduced, the image acquisition unit being arranged independently of the shielding chamber on the side of the other portion in the longitudinal direction of the optical fiber outside the shielding chamber Or a plurality of cameras, wherein the one or more cameras emit a plurality of side surfaces of the other part of the optical fiber that emits a part of the light introduced in the shielding chamber at a predetermined angle of view. An image acquisition unit that captures images from the direction and acquires a plurality of side images representing an image over the entire circumference of the other part;
An image processing unit that individually processes the plurality of side images acquired by the one or more cameras and detects defects in each of the side images;
An optical fiber inspection apparatus.   The optical fiber inspection apparatus according to claim 1, wherein the shielding chamber has a reflection surface that internally reflects the light.   The light introduction section includes a pair of shielding chambers that individually receive light emitted from the light source, and the one or more cameras are provided on the other portion of the optical fiber that extends between the pair of shielding chambers. The optical fiber inspection device according to claim 1, wherein the optical fiber inspection device is disposed laterally.   The image acquisition unit includes a plurality of the cameras that are fixedly distributed in a circumferential direction around the other part of the optical fiber, and the plurality of cameras have different central angle regions of the other part. The optical fiber inspection apparatus according to any one of claims 1 to 3, wherein a plurality of side images are acquired by imaging each side portion extending over a plurality of sides.   The image acquisition unit includes one camera arranged to be movable in the circumferential direction around the other part of the optical fiber, and the one camera moves in the circumferential direction around the other part. The optical fiber inspection apparatus according to any one of claims 1 to 3, wherein the plurality of side images are acquired by sequentially imaging side portions of the other portions over different central angle regions. The optical fiber inspection device according to any one of claims 1 to 5, wherein an optical fiber continuously sent in a length direction is inspected.
The shielding chamber has an optical fiber inlet and outlet coaxially arranged, and at least one of the inlet and the outlet is provided with a fiber guide tube that extends outward from the shielding chamber to prevent leakage of the light. The optical fiber inspection device according to any one of claims 1 to 5.   The one or more cameras acquire the plurality of side images at a time interval set according to a feeding speed of the optical fiber so that a non-imaging portion does not occur in the length direction of the optical fiber. Item 7. The optical fiber inspection device according to Item 6.

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