Method of manufacturing an inspection device

Abstract

To detect a foreign substance mixed in a filamentous body, which is smaller than before.SOLUTION: An inspection device 1 for a filamentous body F comprises: an oscillator 10 that emits electromagnetic waves having a frequency of 30GHz or more; a first waveguide 20 that is connected at one end to the oscillator 10 and forms a waveguide for the electromagnetic waves; a cavity resonator 30 that has an inlet 31 to which the other end of the first waveguide 20 is connected and into which the electromagnetic waves are introduced, a cavity 32 in which the electromagnetic waves resonate in a specific oscillation mode, an outlet 33 from which the electromagnetic waves are derived from the cavity 32, and a communication outlet 34 that forms a communication channel 35 through which the filamentous body F is passed; a second waveguide 40 that is connected at one end to the outlet 33 and guides the electromagnetic waves from the cavity resonator 30; a receiver 50 that receives the electromagnetic waves derived from the cavity resonator 30; and a calculation section 60 that evaluates a state of the filamentous body F on the basis of fluctuations in the electromagnetic waves within the cavity resonator 30.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an inspection apparatus and an inspection system.

Background Art

[0002] In a production line for thread-like bodies such as glass fibers, due to facilities, surrounding environment, production processes, etc. foreign matter such as metal pieces may be mixed into or adhere to the thread-like bodies. As a method for detecting foreign matter such as metal pieces contained in an inspection target, a metal detector utilizing the Doppler effect may be used. Further, to detect foreign matter contained in the thread-like body, an inspection apparatus that irradiates electromagnetic waves to the thread-like body as the inspection target in a cavity resonator is used. When a detection wave (electromagnetic wave) is incident on such an inspection apparatus, resonance occurs in the cavity resonator at a frequency determined by the dielectric constant of the internal medium and the inspection target. If foreign matter with a different dielectric constant is contained in the inspection target, this frequency will change, so the foreign matter can be detected by capturing this change (for example, see Patent Documents 1 to 2). 器内で検査対象たる糸状体に電磁波を入射する検査装置が利用されている。かかる検査装 置において検波(電磁波)を入射すると、空洞共振器内では内部の媒質と検査対象の誘電 率によって決まる周波数で共振が起こるところ、誘電率に差がある異物が検査対象に含ま れているとこの周波数に変化が生じるので、この変化を捉えることで異物を検出すること ができる(たとえば、特許文献1~2参照)。

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of Invention

Problems to be Solved by the Invention

[0004] However, when adopting the metal detection method utilizing the Doppler effect, the detection accuracy In order to ensure this, the transport speed of the items to be inspected must be kept above a certain level. When maintaining the elephant's transport speed above a certain level, it is necessary to determine the location of the foreign object within the object being inspected. In some cases, it was difficult to accurately identify the foreign object. As a result, among the items being inspected, some contained foreign objects. It became necessary to discard even the parts that were not being used.

[0005] Furthermore, metal detection methods utilizing the Doppler effect, and conventional methods described in the above-mentioned patent documents. Inspection devices have limitations in the size of foreign objects they can detect. For example, Patent Document 1 describes the target of inspection. A waveguide having a through-hole through which a microwave is supplied, and if the object being inspected contains a foreign object... It is noted that the increased intensity of the reflected wave is used to detect foreign objects such as metal fragments. It is described therein. Furthermore, Patent Document 2 describes a cavity having a through-hole through which the filamentous material to be inspected passes. Microwaves are supplied into the resonator, and if foreign matter is present in the object being inspected, it will be generated inside the cavity resonator. It is described that foreign objects such as metal fragments can be detected by utilizing the fluctuations in the waveform of the standing wave. It is listed.

[0006] Here, since the intensity of the reflected wave weakens as the size of the foreign object decreases, Patent Document 1 With the described technology, the smaller the foreign object, the more difficult it becomes to detect. Also, the size of the detectable foreign object... The size varies depending on the frequency band of the electromagnetic waves used, as described in Patent Documents 1 and 2. The frequency band of microwaves is approximately 3 GHz to less than 30 GHz, and this frequency band The size of foreign objects such as metal fragments that can be detected using electromagnetic waves can range from a few millimeters to at least 10 It is approximately 0 micrometers. Therefore, by applying electromagnetic waves in this frequency band to filamentous material When attempting to detect foreign matter mixed in, the foreign matter presents continuously for a certain length along the length of the filamentous material. Only objects could be detected. Thus, the conventional technology described above had limitations in terms of detection accuracy and detectability. The size of the foreign object was large and not satisfactory.

[0007] To detect even smaller foreign objects, electromagnetic waves with wavelengths shorter than microwaves are used, and 30 It is assumed that millimeter waves with frequencies above GHz will be used. On the other hand, simply using micro Simply replacing the waves with millimeter waves to create an inspection device will not allow it to function adequately as an inspection device. It was also found that this is not the case. For example, when using electromagnetic waves in a shorter wavelength range, the filamentous material being examined The difficulty lies in continuously generating a predetermined electromagnetic wave effective for detecting foreign objects within the space through which the object passes. It became clear that it would be difficult.

[0008] Therefore, the present invention makes it possible to detect smaller foreign matter, such as that mixed in with filamentous material, than before. The objective is to provide inspection equipment and inspection systems. [Means for solving the problem]

[0009] One aspect of the present invention is a device for inspecting filamentous bodies, An oscillator that emits electromagnetic waves with a frequency of 30 GHz or higher, A first waveguide, one end of which is connected to an oscillator and which forms a waveguide for electromagnetic waves, The other end of the first waveguide is connected to an inlet into which electromagnetic waves are introduced, and the electromagnetic waves are in a specific vibration mode. A cavity that resonates at the radiator, an outlet from which electromagnetic waves are emitted from the cavity, and a connecting passage through which the filamentous material passes. A cavity resonator having a communication port that forms, A second waveguide, one end of which is connected to the outlet, derives electromagnetic waves from the cavity resonator, A receiver that receives electromagnetic waves derived from a cavity resonator, A calculation unit that evaluates the state of the filamentous material based on the fluctuations of electromagnetic waves inside the cavity resonator, The inspection apparatus is provided with the following.

[0010] As described above, the detectable size of a foreign matter depends on the wavelength of the detection wave (electromagnetic wave). This detection wave In conventional inspection apparatuses using microwaves (wavelength: approximately several mm to 30 cm), the detectable size of foreign matter is limited to at least about several hundred micrometers at the minimum, and foreign matter smaller than this cannot be detected. In this regard, by using an electromagnetic wave with a frequency of 30 GHz or higher, typified by millimeter waves, and arranging a waveguide, a cavity resonator, and a waveguide between an oscillator and a receiver to cause resonance inside the cavity resonator, and measuring the degree of fluctuation of the electromagnetic wave inside the cavity resonator to evaluate the presence or absence of foreign matter According to the inspection apparatus of this embodiment, which performs such evaluation, it becomes possible to detect foreign matter that is even smaller than those of about several hundred micrometers, for example, foreign matter of several micrometers (μm).

[0011] Inside the cavity resonator in the inspection apparatus as described above, one or more antinodes of a standing wave may be formed from the introduction port to the discharge port of the cavity portion.

[0012] The cavity resonator in the inspection apparatus as described above may be configured such that the number n of antinodes of the standing wave generated inside the cavity portion is an odd number.

[0013] In the inspection apparatus as described above, the cavity resonator may be configured such that the number n of antinodes of the standing wave generated inside the cavity portion is 3 or more.

[0014] In the inspection apparatus as described above, the communication path may be formed at a position where the filamentous body passes through a predetermined range from the antinode of the standing wave generated inside the cavity portion in the vibration mode.

[0015] ​​​​​​In the inspection apparatus described above, the cavity resonator may have a rectangular parallelepiped-shaped cavity. .

[0016] In the inspection device described above, the inlet and outlet are formed by an iris. That's fine.

[0017] In the inspection device described above, the inner surface of the cavity may be made of metal.

[0018] In the inspection apparatus described above, the cavity resonator is a multiple device for passing multiple filamentous materials through A connecting passageway may also be provided.

[0019] In the inspection device described above, each of the multiple connecting passages is such that the filamentous material is inside the cavity. They are provided at predetermined intervals so as to pass through a predetermined range of regions from the antinodes of the generated standing waves. It's fine if you do that.

[0020] In the inspection apparatus described above, the calculation unit calculates the intensity of a predetermined resonant frequency contained in the electromagnetic wave. Based on the fluctuations of and the fluctuations of the electromagnetic wave generation frequency, filamentous It may also be used to assess the physical condition.

[0021] In the inspection apparatus described above, the oscillator operates within a first range centered on a predetermined resonant frequency. It may also be a device that generates a continuous wave containing the frequency.

[0022] In the inspection apparatus described above, the oscillator has a continuous repeating resonant frequency including a char It may also be a device that generates PU waves.

[0023] In the inspection apparatus described above, the calculation unit is configured to receive signals from an oscillator and through a cavity resonator. The first chirp wave received by the receiver and the chirp wave emitted by the oscillator have different frequencies depending on the time. The difference in frequency and signal strength between the second chirp wave, which has a different degree of variation in its number, is small. The presence or absence of filamentous abnormalities may be evaluated based on either one of these factors.

[0024] The inspection device described above is placed inside the cavity resonator, and the communication passage and the inside of the cavity resonator A protective tube may be provided to separate the cavity from the surrounding area.

[0025] The communication port in the inspection device described above is defined by the cutoff frequency of the waveguide. The electromagnetic waves having frequencies within a predetermined measurement range are set to a level that does not leak out of the cavity. That's fine.

[0026] In the inspection apparatus described above, the inner diameter of the inlet and the inner diameter of the outlet are such that the inlet and outlet are From 15% of the cross-sectional area of ​​the cavity in the cavity resonator in the direction perpendicular to the line segment connecting the two points It can be small as well.

[0027] Furthermore, an inspection system according to one aspect of the present invention comprises a plurality of cavity resonators as described above, The filamentous material is configured to pass through the communication passage of two or more of the multiple cavity resonators. It is something that is done. [Effects of the Invention]

[0028] According to the present invention, it is possible to detect smaller foreign matter, such as that mixed in with filamentous material, than before. It is possible. [Brief explanation of the drawing]

[0029] [Figure 1] This diagram schematically shows an example of the configuration of an inspection device. [Figure 2] This diagram shows examples of cavity resonator shapes. [Figure 3] This image shows an example of the electric field strength inside a cavity resonator, specifically for the case with n=3 antinodes. [Figure 4] This diagram shows how a thread-like material is passed through the communication passage of a cavity resonator. [Figure 5] This diagram shows the electric and magnetic field lines when viewed from above through the communication opening. [Figure 6] This figure shows the electric field strength plot for TM11. [Figure 7] This graph shows the relationship between the waveguide radius and the TM11 mode cutoff frequency. [Figure 8] This graph shows a comparison of spectra when the iris diameter is changed. [Figure 9] This graph shows the relationship between iris diameter and Q value (sensitivity to foreign matter M). [Figure 10] (A) is a graph showing an example of a chirp wave waveform, and (B) is a graph showing an example of a chirp wave frequency change. [Figure 11] This diagram shows a schematic configuration in which two different chirp waves are emitted from separate oscillators. [Figure 12] (A) A graph showing two different chirp wave examples, and (B) A graph showing the change in the frequency difference between the two different chirp waves. [Figure 13] (A) A graph showing the relationship between the difference in frequencies (IF frequency) of two different chirp waves and the intensity of chirp wave 1. (B) A graph showing the relationship between the original frequency of chirp wave 1 and the intensity of chirp wave 1. [Figure 14] This graph shows examples of changes in the resonant frequency of the normal portion of a filamentous material and the portion containing foreign matter. [Figure 15] This graph shows examples of detection waveforms for the normal portion and the portion containing foreign matter in Example 1 of the present disclosure. [Figure 16] This figure shows a schematic perspective view of the cavity resonator designed in Example 2 of this disclosure, and a magnified view of a part of it. [Figure 17] This graph shows examples of detection waveforms for both the normal portion of the filamentous material and the portion containing foreign matter. [Modes for carrying out the invention]

[0030] Hereinafter, with reference to the drawings, preferred embodiments of the inspection apparatus and inspection system according to the present invention This will be explained in detail (see Figures 1 to 13).

[0031] The inspection apparatus relating to this disclosure is manufactured through various manufacturing processes, for example, glass fiber The filamentous material F is the target of measurement, and metal fragments etc. are detected due to equipment, surrounding environment, manufacturing process, etc. This is an inspection to check whether there are any abnormalities such as foreign matter M being mixed in or attached to the material. This is a device. In such an inspection device, electromagnetic waves are incident on a filamentous body F within a cavity resonator, and the internal medium Resonance occurs at a predetermined frequency determined by the quality and dielectric constant of the filamentous material F, and there, different dielectric constants... The principle is to detect foreign matter M by capturing the change in frequency that occurs when foreign matter M is present. The test will be conducted there. Furthermore, the inspection apparatus relating to this disclosure uses standing waves of electromagnetic waves having a predetermined resonant frequency to detect cavities together. It is generated inside the vibrator. In this disclosure, the frequency is 3 GHz or higher and less than 30 GHz, and the wavelength is Electromagnetic waves with a frequency band of approximately 10 centimeters to 1 centimeter are used. These are called microwaves, and their frequencies are between 30 GHz and 300 GHz, with wavelengths of millimeters. The electromagnetic waves emitted by the Torstand are called millimeter waves. However, millimeter waves and microwaves are strictly defined as 30 GHz. It goes without saying that this is not defined as a boundary.

[0032] The inspection apparatus 1 of this embodiment includes an oscillator 10, a first waveguide 20, a cavity resonator 30, and a second The device is configured to include a waveguide 40, a receiver 50, and a processing unit 60 (see Figure 1, etc.). .

[0033] (Oscillator) The oscillator 10 includes frequencies within a predetermined range (first range) centered on a predetermined resonant frequency. This is a device that generates continuous waves. In this embodiment, it mainly generates millimeter waves (30 GHz or higher). The oscillator 10 and other components are configured assuming the use of electromagnetic waves belonging to the band (below 300 GHz). However, it is also possible to apply electromagnetic waves with frequencies of 300 GHz or higher.

[0034] (waveguide) The first waveguide 20 is used to guide the electromagnetic waves generated in the oscillator 10 to the cavity resonator 30. It is a component, with one end connected to the oscillator 10 and the other end connected to the cavity resonator 30. (See Figure 1). The second waveguide 40 extracts electromagnetic waves from the cavity resonator 30 and transmits them to the receiver 50. This component is used to guide the signal, with one end connected to the cavity resonator 30 and the other end connected to the receiver 50. They are connected (see Figure 1). These first waveguide 20 and second waveguide 40 are each The configuration may be the same as that used in previous inspection devices. These are shown in a simplified form in the schematic diagram labeled 1. The cross-sectional areas of the first waveguide 20 and the second waveguide 40 are generated inside the cavity resonator 30. This can be determined by the resonant frequency of the electromagnetic wave. In this embodiment, the first Waveguide 20 and the second waveguide 40 have the same dimensions a and b as the cavity resonator 30 (Figure It has a rectangular cross-section (see 2). The first waveguide 20 and the second waveguide 4 The cross-sectional area and cross-sectional shape of 0 do not have to be the same as those of the cavity resonator 30. Also, the first The lengths of the first waveguide 20 and the second waveguide 40 are not particularly limited. The second waveguide 40 is, for example, EIA (Electronic Industries Alliance). As defined in the Alliance standard, the dimensions corresponding to electromagnetic waves in a specified frequency band Waveguides (waveguides) with a specific shape can be appropriately selected and used.

[0035] (cavity resonator) The cavity resonator 30 consists of a housing (structure) 39 with a cavity 32 formed inside it. In the cavity 32, there is a medium that transmits electromagnetic waves in the band of the resonant frequency well, and in this embodiment In this case, the medium is air. The cavity resonator 30 generates standing waves (steady waves) within the cavity 32. It is configured to generate a standing wave within the cavity 32 at a predetermined resonant frequency. It has wavenumber components. At least the inner circumferential surface of the cavity 32 is made of metal. In this configuration, the housing 39 is made of metal walls. Furthermore, in the rectangular parallelepiped shape of each dimension shown in Figure 2 The resonant frequency f of a certain cavity resonator 30 can be expressed by the following equation 1. Thus, the dimensions of the cavity resonator 30 are small, and the medium (example of the internal space of the cavity resonator 30) For example, the lower the dielectric constant of air, the higher the frequency f of the electromagnetic waves generated inside the cavity resonator 30. It will acquire the property of vibrating. Note that the dimensions a, b, and c shown in Figure 2 are the cavities, respectively. 32 dimensions, that is, the dimensions of the space that produces a standing wave having a predetermined resonant frequency component. show.

number

[0036] Here, if the dimensions are reduced and the cavity resonator 30 is miniaturized, when millimeter waves are used, Even if a standing wave having a predetermined resonant frequency is generated inside the cavity resonator 30, Furthermore, the generation of standing waves adjusts the electric field strength distribution inside the cavity resonator 30. This can be done. As a result, the amplitude of a standing wave having a predetermined resonant frequency can be increased, that is, This allows the electric field strength to be concentrated and strengthened in a specific range (region). In the cavity resonator 30, the thread of the object to be measured, which contains foreign matter M, is in a range of relatively strong electric field strength. When state F passes through, the range of change in the frequency or intensity of the emitted electromagnetic waves increases, and detection precision improves. The degree can be improved.

[0037] As an example, in this embodiment, the dimensions shown in Figure 2 are a=3.0mm and b=1.5mm. Furthermore, by adopting n=3, that is, 3, where the number of antinodes of the standing wave is odd, we set c=7.2mm. A cavity resonator 30 was used. This allowed a standing wave with a resonant frequency of 79 GHz to be resonated through the cavity. It can be generated within the vibrator 30. Note that the rectangular cavity resonator 30 conforms to EIA standards. A structure conforming to WR12, with dimensions a=1.549mm and b=3.099m A structure adjusted to m may also be used. Note that the resonant frequency set to 79 GHz is Due to the presence and dimensions of the inlet 31 and outlet 33, which will be described later, and the dimensions of the communication port 34, Needless to say, this will result in a value deviation of several GHz.

[0038] Note that the above dimensions a, b, and c are merely examples, and the dimensions of the cavity resonator 30 are as follows: It is possible to adjust the settings appropriately based on the desired electromagnetic waves to be generated. According to the inspection device, it is possible to detect smaller foreign objects compared to conventional methods, and the detection accuracy has been improved. ru.

[0039] The inspection device 1 is described in more detail below. Compared to conventional devices, it uses millimeter waves in the high-frequency band. This improves sensitivity to foreign substances M, such as metal fragments, contained in the filamentous body F, while the filamentous body F It is difficult to generate a predetermined electromagnetic wave inside the cavity resonator 30 (cavity 32) through which the wave passes. There were cases where this was the case. For example, the precision of the method of introducing electromagnetic waves, leakage of electromagnetic waves from the cavity resonator 30, etc. In some cases, it was difficult to generate the specified electromagnetic waves inside the cavity resonator 30.

[0040] From the above perspective, a predetermined electromagnetic wave is generated in the space through which the filamentous material F to be inspected passes. To achieve this, it is preferable to appropriately introduce electromagnetic waves into the space (cavity 32). In the configuration of the inspection device 1, the electromagnetic waves generated by the oscillator 10 are transmitted through the first waveguide 20. The fluid is introduced into the cavity 32 of the cavity resonator 30 via the inlet 31, and then into the outlet 33, the second waveguide 40 The configuration adopted involves receiving the signal at receiver 50 via the oscillator 10 and receiver 5. 0, and the electromagnetic waveguides (first waveguide 20 and second waveguide 40) are the subject of inspection. A space (cavity resonator 3) that requires the generation of electromagnetic waves in a predetermined vibration mode in order to pass through it. It can be functionally separated from the cavity 32, and as a result, the desired electricity can be charged within the cavity 32. It becomes easier to generate magnetic waves.

[0041] In this embodiment, when applying electromagnetic waves with a frequency of 30 GHz or higher, the following further applies: A cavity resonator 30 with the above configuration is constructed to improve the detection accuracy.

[0042] (Overview of cavity resonators) The cavity resonator 30 of this embodiment includes an inlet 31 into which electromagnetic waves are introduced, a cavity 32, and a cavity An outlet 33 from which electromagnetic waves are emitted from 32, and a connecting passage 35 through which the filamentous body F passes are formed. It has a pair, or at least two, communication ports 34 (see Figure 1, etc.).

[0043] The shape of the cavity 32 is not particularly limited, but can be, for example, a rectangular parallelepiped. 1 and outlet 33 are positioned to face each other inside the cavity 32. 32 is one or more antinodes extending from the inlet 31 toward the outlet 33, and the number of such antinodes n is odd. It is configured to generate a number of standing waves. As an example, in this embodiment, the cavity 3 The number of antinodes n of standing waves generated inside 2 is set to 3 (see Figure 3), and the electromagnetic wave is set to a specific vibration. It is designed to resonate in dynamic mode. Furthermore, within the three roughly circular electric field strengths shown in Figure 3, In each case, the strength increases towards the center. Let me add a few more points about Figure 3. Therefore, since the electric field strength image, which was originally represented in color, is now represented in shades of black and white, The electric field strength appears denser in the outer, roughly circular area, but the actual electric field strength is further away from the center of the circle. It has become considerably weaker.

[0044] The communication port 34 is provided in the housing 39 of the cavity resonator 30 as a hole through which the filamentous material F can pass. It is formed to create a passage 35 through which the filamentous body F passes (see Figure 4, etc.). Body F moves within the connecting passage 35 from top to bottom (or from bottom to top) at a predetermined speed. , passes through (see Figures 1 and 4). That is, the filamentous body F passes through the cavity 32 of the cavity resonator 30. , passing in the direction of the amplitude of the standing wave generated in the cavity 32. In this embodiment, the housing 39 The widest surface is the top surface (indicated by reference numeral 39a) in Figure 2, which has a width a and a length c, and A pair of communication openings 34 are provided on each of the opposing lower surfaces. The connecting passage 35 formed is where the electric field strength is strong among the standing waves formed within the cavity resonator 30. It is desirable that it be formed so that it passes through a portion. That is, by a pair of communication openings 34 The connecting passage 35 is configured such that the peak of the antinode of the standing wave formed in the cavity resonator 30 occurs. It is preferable that it be formed in the location where it occurs. The number of antinodes n of standing waves generated inside the cavity 32 is 3. In this embodiment (see Figure 3), the middle of the three antinodes with the strongest electric field strength is the one that is strongest. The connecting passage 35 passes through the central part of the belly, with the upper surface 39a and the lower surface of the housing 39 respectively A pair of communication openings 34 are provided in the central part (see Figure 4).

[0045] Even if a protective tube 36 is provided to separate the communication passage 35 from the cavity portion 32 inside the cavity resonator 30, Good. The protective tube 36 is preferably made of a material that absorbs little electromagnetic waves generated in the cavity 32. For example, ceramics and resins can be cited as concrete examples. Also, protective tube 3 Material 6 is a material that does not damage the filamentous body F, and even if contact with the filamentous body F occurs, friction will not occur. It is preferable that the material does not wear down or has extremely low frictional resistance. In this respect, many For the filamentous material F of the type described above, ceramic is more preferred in light of the above conditions, and especially for the subject of inspection If the filamentous material F is a glass fiber, it is most preferably a ceramic material. In this way, by providing the protective tube 36, dust and other particles generated in the external environment can be removed from the cavity resonator 30. It can prevent intrusion into the interior. As a result, inspection device 1 is installed on the manufacturing line, continuously Even when used for specific purposes, it can maintain high inspection accuracy.

[0046] In this embodiment, a single communication passage 35 is formed by a pair of communication openings 34. This is just one example. For instance, multiple connecting passages 35 are provided, and multiple filamentous bodies F are connected to each other. It may also be possible to allow them to pass through the connecting passage 35 simultaneously. In this case, even If, as in this embodiment, the number of antinodes of the standing wave is set to n=3, then the three strongest electric field strengths Each connecting passage 35 passes through a predetermined range area from each of the sides of the bellies at a predetermined interval. It is preferable to provide each communication port 34 in such a way (see Figure 4). This creates a pair of communication ports Each of the multiple connecting passages 35, which are composed of 34, is formed within the cavity resonator 30. It forms at the location where the antinode peak of the present wave occurs.

[0047] (Diameter of the communication opening) When inspecting for foreign objects in the filamentous material F, the cavity resonator 30 is equipped with a wire for passing the filamentous material F through. It is necessary to provide a passage 34, which allows the cavity 32 to communicate with the external environment. The larger the aperture of the 34, the easier it is to pass the filamentous material F through, resulting in better operability, especially in the millimeter wave band. When performing foreign object inspection using electromagnetic waves, as described above, leakage of electromagnetic waves from the communication port 34 may occur. Furthermore, the influence of electromagnetic waves within the cavity resonator 30 is greater than in conventional methods, and the desired electromagnetic waves that contribute to the inspection... It is difficult to generate this. Therefore, the structure of the cavity resonator 30, including the diameter of the communication port 34, The impact on inspection accuracy due to the construction becomes more pronounced than before. In that case, the communication port 34, It is desirable to have the largest possible pore diameter while suppressing electromagnetic wave leakage. An example of the procedure (flowchart) for determining the size of the obtained pores is shown below. 1. Determine the resonant frequency of the electromagnetic wave (standing wave) generated within the cavity resonator 30. 2. The communication port 34 of the filamentous body F is positioned directly above the antinode of the electromagnetic wave (standing wave) having the above-mentioned resonant frequency. do. 3. The length of the communication opening 34 (in other words, the length of the metal wall of the cavity resonator 30 in which the communication opening 34 is formed) Considering its thickness, the communication opening 34 of the filamentous body F can be treated electromagnetically in the same way as a circular waveguide. Consider becoming a Noh performer. 4. From the above-mentioned resonant frequency and the length of the circular waveguide, the propagation mode inside it can be determined. 5. The k value included in the cutoff frequency formula (Equation 2) is determined by the identified propagation mode. circle. 6. Set fc as the upper limit of the frequency included in the electromagnetic waves generated inside the cavity resonator 30, and cut off The diameter (radius) r of the communication port 34 is determined by the following equation 2 for the frequency.

number

[0048] The decision-making procedure (flow) described above is further explained below (see Figures 6 and 7). The above concept is The communication port 34 is treated as a cutoff waveguide, and electromagnetic waves (electricity) leaking from the cavity 32 are... The goal is to reduce it. As mentioned above, the communication port 34 is the housing that constitutes the cavity resonator 30. It functions as a circular waveguide having a length equal to the thickness of the body (metal wall). Here, the circular waveguide is As the term "cutoff waveguide" suggests, it operates as a high-pass filter, and above a certain frequency... It only allows electromagnetic waves of a certain type to pass through. Therefore, the diameter of the circular waveguide (communication port 34) is set to a predetermined size. By adjusting the diameter, leakage of electromagnetic waves from the cavity resonator 30 is prevented, and the inside of the cavity resonator 30 The unit can generate electromagnetic waves of a desired vibration mode.

[0049] As mentioned above, the value of the constant k in the cutoff frequency equation (Equation 2) is related to the propagation mode in the waveguide. This is determined by [the following factors]. Furthermore, the propagation mode is determined by the radius and length of the waveguide. For example, As mentioned above, standing waves with electromagnetic waves in the frequency band of approximately 79 GHz are used for cavity resonance. When generated inside the device 30, and the length of the communication port 34 (circular waveguide) is 1.2 mm, the transmission The broadcasting mode will be TM mode (Transverse Magnetic mode). This is common practice, and as shown in Figure 6, the simulation results indicate that the communication port 34 The mode of electromagnetic waves passing through is TM11 (a mode where there are two antinodes of the electric field within the communication port 34). They are confirming that D) is dominant.

[0050] In this embodiment, as an example, as described above, a resonant frequency is generated within the cavity resonator 30. When generating electromagnetic waves of several 79 GHz, the generation error of the electromagnetic waves must be taken into consideration. Cutoff frequency fc (the upper limit of the frequency contained in the electromagnetic waves generated within the cavity resonator 30) Set to 82GHz, and electromagnetic waves with frequencies above this cutoff frequency fc pass through. The radius of the communication port 34, which does not exist, is derived by the determination procedure flow described above. The radius of the opening 34 must be 2.23 mm or less. This will allow the filamentous body F to The upper limit of the hole diameter of the communication opening 34 is determined. Note that the cutoff frequency fc is, for example, used The oscillator 10 may be set based on the upper limit of the frequency it can generate. stomach.

[0051] (Inlet and outlet) The inlet 31 is the part through which electromagnetic waves are introduced into the cavity 32 via the first waveguide 20, and the outlet The opening 33 is the part through which electromagnetic waves are discharged from the cavity 32. (Inlet 31 and Outlet 33) They are arranged to face each other, and are located in the cavity 32 perpendicular to the direction of electromagnetic wave propagation. It has an area smaller than the cross-sectional area of ​​the cross-section. More specifically, in this embodiment, The opening 31 and outlet 33 are perpendicular to the direction of electromagnetic wave propagation in the rectangular cavity 32. It has an area smaller than the cross-sectional area of ​​the cavity 32 as defined in laws a and b.

[0052] Furthermore, the inlet 31 and outlet 33 have a fixed resonant frequency within the cavity 32. To generate waves, it is configured to be of a size that does not leak electromagnetic waves of a predetermined frequency. It is preferable that the inlet 31 and outlet 33 are excessively large. Furthermore, electromagnetic waves leaking from outlet 33 have a predetermined resonant frequency within the cavity 32. It becomes difficult to generate standing waves. This is because leakage occurs from the inlet 31 and outlet 33. When the amount of electromagnetic waves becomes excessive, the first waveguide 20 and the second waveguide 40 resonate. This is because it functions as a container. From the above viewpoint, in this embodiment, the inlet 3 1 and outlet 33 are configured to have an area smaller than 15% of the cross-sectional area of ​​the cavity 32. This has been done. The method for calculating the upper limit of the area of ​​the inlet 31 and outlet 33 will be described later. do.

[0053] The inlet 31 and outlet 33 are arranged by forming predetermined through-holes in the cavity resonator 30. This may be done, and between the cavity resonator 30 and the first waveguide 20 or the second waveguide 40, It may be formed by arranging irises having through-holes of a fixed area. In this configuration, the inlet 31 and outlet 33 are formed by irises (small holes). Yes, they are.

[0054] Furthermore, the members forming the inlet 31 and outlet 33 are conductive so as not to transmit electromagnetic waves. It is preferable that it be made up of a body. Also, the thickness of the members forming the inlet 31 and outlet 33 The thickness of the iris is ideally thin, while still ensuring a sufficient length to prevent electromagnetic waves from passing through. This is a suitable length. For example, it is between 1 μm and less than 100 μm. Therefore, an iris is formed by creating an inlet 31 and an outlet 33 on a metal plate with a thickness of 50 μm.

[0055] Furthermore, an example of how to determine the upper limit of the area (size) of the inlet 31 and outlet 33 is shown below. As shown below (see Figure 9). As previously mentioned, the cavity resonator 30 having predetermined dimensions With a standing wave having a resonant frequency of 79 GHz generated inside, the inlet 31 and guide When the area of ​​the outlet (iris) 33 is varied, as shown in Figure 9, the inlet 31 and outlet The Q-value (Quality Factor) varies depending on the area of ​​the opening (iris diameter). A large Q factor means that the waveform of the electromagnetic wave, with its peak at the resonant frequency, is relatively steep. This indicates that the change in the waveform of electromagnetic waves when the object being inspected, which contains foreign matter M, passes through is significant. , it has high sensitivity to foreign matter M. Here, for detecting foreign matter using the cavity resonator 30, generally Specifically, the Q value must be greater than 1000. Therefore, in this embodiment, The area (iris diameter) of the inlet 31 and outlet 33 should preferably be φ0.9 mm or less. It is preferable that this is 15% or less of the cross-sectional area of ​​the cavity 32. The inner diameter of the inlet 31 and the inner diameter of the outlet 33 of the cavity resonator 30 are such that the inlet 31 and the outlet 33 are 15 of the cross-sectional area of ​​the cavity 32 provided in the cavity resonator 30 in the direction perpendicular to the line segment connecting them. It is preferable that the percentage be less than %.

[0056] Furthermore, the lower limit of the area (iris diameter) of the inlet 31 and outlet 33 is greater than 0. It is not particularly limited as long as it is possible to measure electromagnetic waves. On the other hand, the electromagnetic waves acquired by the receiver 50 In order to ensure strength is above a certain level, the inlet 31 and outlet 33 are of a size greater than predetermined. It is preferable to do so. As described above, the smaller the inlet 31 and outlet 33, the more the after passing through these through holes. The level of electromagnetic waves will be lower. For example, as mentioned above, the first waveguide 20, the second waveguide The cross-sectional areas of the tube 40 and the cavity resonator 30 are dimensions a = 3.0 mm and b = 1.5 mm, respectively. When using electromagnetic waves with a vibration frequency of 79 GHz, the inlet 31 and outlet 33 Figure 8 shows a comparison of electromagnetic wave levels when the area is changed. The vertical axis in Figure 8 represents the oscillator. This is the ratio of the intensity of the electromagnetic waves generated by 10 to the intensity of the electromagnetic waves received by receiver 50. Therefore, the transmittance of electromagnetic waves passing through the inlet 31 and outlet 33 is shown, as shown in the upper right. For each size of the inlet 31 and outlet 33 (the diameter of the openings of the inlet 31 and outlet 33), This shows the transmittance of electromagnetic waves. As shown in Figure 8, the smaller the area of ​​the inlet 31 and outlet 33, the less air will pass through them. The intensity of electromagnetic waves afterwards is small. Here, the measurement equipment with high measurement accuracy that is commonly used The dynamic range is approximately -110 dB (the -110 dB line in Figure 8). (See reference). In light of this, if the diameters of the inlet 31 and outlet 33 are less than 0.3 mm As a result, the intensity of the electromagnetic waves received by receiver 50 becomes weak, creating a region outside the measurement range. From above, the diameters of the inlet 31 and outlet 33 are preferably φ0.3 mm or larger. i. According to this, the cross-sectional area of ​​the first waveguide 20, the cavity 32, and the second waveguide 40 is The area of ​​the inlet 31 and outlet 33 is preferably 1.6% or more.

[0057] The inlet 31 and outlet of the cavity 32 of the cavity resonator 30 as described above. The upper limit of the diameter is determined by the ratio of the areas of 33, and the first waveguide 20, the cavity 32, and the second This is determined by the ratio of the area of ​​the inlet 31 and outlet 33 to the cross-sectional area of ​​the waveguide 40. The lower limit of the aperture refers to the shape of the first waveguide 20, the cavity resonator 30, and the second waveguide 40, and It can be applied even if the dimensions change.

[0058] (Receiver) The receiver 50 receives electromagnetic waves that have been emanated from the cavity resonator 30 and passed through the second waveguide 40. Believe (see Figure 1).

[0059] (calculation section) The calculation unit 60 evaluates the state of the filamentous material F based on the fluctuations of electromagnetic waves within the cavity resonator 30. It is composed of a calculation device. The calculation unit 60 is composed of parts of the electromagnetic waves received by the receiver 50. The state of the filamentous material F can be evaluated based on the fluctuations in the intensity of a constant resonant frequency, or The state of the filamentous material F can be evaluated based on fluctuations in the frequency of electromagnetic wave generation. In this embodiment, the inspection device 1 generates standing waves of electromagnetic waves having a predetermined resonant frequency in the air. The electromagnetic waves generated within the cavity 32 of the cavity resonator 30 and the electromagnetic waves emanating from the cavity 32 are transmitted to the receiver 50. The receiver 50 receives the signal, and the calculation unit calculates the degree of variation of the electromagnetic wave received by the receiver 50, for example, the resonant frequency. Based on the degree of variation of at least one of the frequencies and amplitudes of the number of parameters being examined, Evaluate the presence or absence of foreign matter in the filamentous body F.

[0060] (Use of chirp waves) Here, the inspection device 1 employs a chirp wave as the electromagnetic wave generated from the oscillator 10. This is also good. This allows for signal processing when using high-frequency electromagnetic waves such as millimeter waves. This allows for down-converting of the frequency, reducing losses within the arithmetic circuits responsible for signal processing. It is possible to reduce the amount of information, or compress it to a level where AD conversion can be easily performed. In the inspection device 1 with the above configuration, chirps with different time change rates are used. An example of a spectral measurement technique that utilizes the difference in wave magnitude is described below (see Figures 10-12). A chirp wave is a waveform based on a signal (chirp signal) whose frequency changes over time. This refers to (see Figure 10). In this embodiment, two frequencies increase with time. This uses chirp wave 1 and chirp wave 2.

[0061] In this embodiment, in addition to oscillator 10, another oscillator 12 is provided, and oscillator 10 or Chirp wave 1 is emitted from one oscillator, and chirp wave 2 is emitted from another oscillator 12 (see Figure 11). Wave 2 employs a chirp wave with a different frequency variation than chirp wave 1. Wave 1 is introduced into the cavity resonator 30, is affected by the resonator, and if there is a foreign object M, that object After the intensity changes, it is derived from outlet 33. On the other hand, chirp wave 2 is affected by cavity resonance. The cavity resonator is not introduced into the interior of the device 30, that is, it is not affected by the object being detected. It is added to chirp wave 1, derived from 30, and used for multiplication.

[0062] These chirp wave 1 and chirp wave 2 are configured to have different frequencies at a given point in time. (However, in the graph showing the relationship between time and frequency, chirp wave 1 and char (Excluding the intersection with chirp wave 2). In this embodiment, chirp wave 1 and chirp wave 2 are The initial frequency and the rate of increase in frequency at the start of oscillation (as shown in the graph in Figure 10(B)) The configuration is such that the slope (expressed as the inclination) is different. More specifically, in this embodiment In this case, chirp wave 1 has a higher initial frequency at the start of oscillation compared to chirp wave 2. It is set up to do so. Also, chirp wave 1 has a frequency increase rate that depends on the time of chirp. It is configured to be smaller compared to wave 2.

[0063] Furthermore, chirp wave 1 and chirp wave 2 emit signals of a certain strength within the range of their radiated frequencies. It may be emitted as a signal. In other words, the intensity information of chirp wave 2 does not need to be used. In this embodiment, the frequency information of chirp wave 2 is downcoded by the frequency of chirp wave 1. It is used to convert. According to this method, immediately after deriving from the cavity resonator 30 This makes it possible to measure the intensity (power) of chirp wave 1 with greater accuracy. .

[0064] Let me explain further with an example. The chirp wave 1 passing through the cavity resonator 30 is at t=0 or Then, between t=100, the frequency was changed from 77.005GHz to 91.001GHz. Let's assume it has been changed. Also, the chirp wave 2 that does not pass through the cavity resonator 30 will be from t=0 to t= Let's assume that the frequency was changed from 77 GHz to 91 GHz between the time points up to 100 (Figure 1). See 2(A). In this case, the change in the frequency difference between the two chirp waves is as shown in the figure. (See Figure 12(B)), the difference at t=0 was 0.005 GHz (5 MHz). This means that when t=100, the difference was 0.001 GHz (1 MHz). It will become.

[0065] Here, the horizontal axis represents the difference in frequency (IF frequency), and the horizontal axis represents the intensity of the chirp wave emitted from oscillator 1 (ma Alternatively, the intensity of chirp wave 1 emitted from oscillator 1 and the intensity of chirp wave 2 emitted from oscillator 2 are compared. For a graph with the difference (not shown) on the vertical axis, the difference in frequency is Fourier transformed to obtain the intensity. The spectrum is acquired, and the relationship between the frequency difference (IF frequency) and the intensity of chirp wave 1 is calculated. (See Figure 13(A)) and the frequency varies with elapsed time, that is, the frequency corresponding to the elapsed time. The horizontal axis represents the difference in the number, and the horizontal axis represents the chirp wave passing through the cavity resonator 30 (i.e., chirp wave 1). This will result in a graph with the intensity of the signal on the vertical axis. Next, based on the above, we will use the chirp wave. When we take the relationship between the original frequency of 1 and the intensity of chirp wave 1 (see Figure 13(B)), this transformation In this case, the frequency can be lower than the original frequency. This allows the receiver 50 to receive The transmitted electromagnetic waves can be down-converted to a frequency band that is easily converted via AD. In this disclosure, which uses millimeter waves, which are electromagnetic waves in the high frequency band compared to conventional methods, the receiver 50 When performing signal processing on electromagnetic waves received, transmission loss in the electrical circuit responsible for calculation processing In particular, transmission loss due to dielectric loss, which is proportional to frequency, becomes large. To solve this, It will be necessary to change the materials of the electrical circuit, especially the circuit board, but currently, the electromagnetic waves in the millimeter wave band... There are no materials that significantly reduce dielectric loss when used in practical applications. On the other hand, as mentioned above, by performing calculations on the down-converted electromagnetic waves, Calculations can be performed with reduced transmission loss. As described above, chirp waves can be used. When performing a spectral measurement method using these chirp waves 1 and chirp waves, the calculation unit 60 performs the calculation using these chirp waves 1 and chirp waves. The presence or absence of abnormalities in filamentous tissue F is evaluated based on the difference in frequency or signal intensity compared to sharp wave 2. Worthy.

[0066] According to the inspection device 1 of this embodiment as described above, the frequency is 30 GHz or higher. By generating electromagnetic waves such as millimeter waves and directing them into the cavity resonator 30, the conventional inspection device can be used It detects foreign matter M that is even smaller than the detectable limit of several hundred μm. This can be done by injecting electromagnetic waves into the filamentous material F being inspected inside the cavity resonator 30. When applying electromagnetic waves (millimeter waves) with a frequency of 30 GHz or higher in device 1, this embodiment The inspection device 1 does not merely employ an oscillator 10 suitable for it, but rather... This is clear from the explanations up to this point, and also from the descriptions of the examples that will be discussed later.

[0067] The embodiments described above are examples of preferred implementations of the present invention, but are not limited thereto. There are no exceptions, and various modifications can be implemented without departing from the spirit of the present invention. For example, the above In this embodiment, an inspection device 1 comprising a single cavity resonator 30 was described, but The device comprises multiple cavity resonators 30, and the filamentous body F comprises two or more of these cavity resonators 30. An inspection system may be configured such that the passage 35 of the cavity resonator 30 is used for the inspection. [Examples]

[0068] We attempted to verify the principle of anomaly detection using actual samples from inspection device 1. The shape and dimensions of inspection device 1 were also examined. The specifications, including the method and resonant frequency, are summarized and shown in Table 1. Here, glass fiber is used as the filamentous material F. Iba was used. Glass fiber was passed through the communication passage 35 of the cavity resonator 30, at 5.0 m / min. The electromagnetic waves measured by receiver 50 were measured when the signal passed through the glass fiber at a certain speed. Figure 14 shows what happens when a normal portion of the filamentous glass fiber F, free of foreign matter, passes through. The waveforms shown are the normal waveform and the waveform when the abnormal portion of the glass fiber containing foreign matter passes through. As shown in Figure 14, when the normal portion passes through, the frequency is around 79 GHz as described above. A peak at the resonant frequency is observed. On the other hand, the abnormal part containing foreign matter is connected to the cavity resonator 30. When passing through passage 35, the peak frequency of the resonant frequency and its intensity fluctuate. According to the inspection device 1 of this embodiment as described above, the normal portion (normal part) of the filamentous body F is inspected. (Regular part), abnormal part containing foreign matter (metal part) 1) In both cases, the peak frequency and intensity change significantly, and the change exceeds the measurement error. This was acknowledged. [Table 1] Furthermore, the inspection device 1 in this disclosure (however, the diameter of the communication port Φ: 1.0 mm, eye (In the case of a squirrel diameter of φ0.7 mm), a foreign object (metal sphere φ2) with a diameter α: 0.2 μm and a length of 100 μm. It was confirmed that detection of a volume equivalent to 0.6 μm is possible (see Figure 15). [Examples]

[0069] We attempted to verify the principle of anomaly detection using an electromagnetic field simulator. Here, the resonant frequency... The cavity resonator 30 was designed so that the frequency was between 76 and 81 GHz (where the diameter of the communication port was Φ (1.5mm, iris diameter φ0.6mm), thread-like material F containing foreign matter (metal part) M is connected. It was passed through passage 35 (see Figure 16). Calculations show that if foreign object M enters the cavity resonator 30... It was observed that the peak shape, peak intensity, and resonant frequency all changed significantly. (See Figure 17). Note that the conditions in Figure 17 are the same as those in Figure 14. The reason the peak position was slightly different was, in reality, due to thermal expansion of the metal part of the cavity resonator 30 and The way the screws are tightened at the connection between the cavity resonator 30 and the waveguides 20 and 40 is highly sensitive to the effects of this method. It was thought that this was because it would happen. [Industrial applicability]

[0070] The present invention is particularly suitable for application to inspection devices and inspection systems for filamentous materials. [Explanation of symbols]

[0071] 1…Inspection device 10…Oscillator 12... Another oscillator 20...First waveguide 30...Cavity resonator 31... Inlet 32...Cavity part 33... Outlet 34... Connecting port 35…Communication path 36...Protection tube 39... Cabinet 39a…Top surface 40...Second waveguide 50... Receiver 60...Arithmetic section F... filamentous body M...Foreign object

Claims

Claim 1 A method of manufacturing a filamentous object inspection apparatus, comprising: an oscillator that emits electromagnetic waves with a frequency of 30 GHz or higher, a first waveguide having one end connected to the oscillator and forming a waveguide path for the electromagnetic waves, a cavity resonator having an introduction port to which the other end of the first waveguide is connected and through which the electromagnetic waves are introduced, a cavity part in which the electromagnetic waves resonate in a specific oscillation mode, an outlet port through which the electromagnetic waves are led out from the cavity part, and a communication port forming a communication path for passing the filamentous object, a second waveguide having one end connected to the outlet port and leading out the electromagnetic waves from the cavity resonator, a receiver that receives the electromagnetic waves led out from the cavity resonator, an arithmetic unit that evaluates the state of the filamentous object based on fluctuations of the electromagnetic waves inside the cavity resonator, the inspection apparatus is configured to include the above components, the cross-sectional area of each of the first waveguide, the cavity resonator, and the second waveguide is set to be substantially constant along the traveling direction of the electromagnetic waves, the cavity resonator is configured to generate a standing wave of the electromagnetic waves within the cavity part, the resonance frequency of the electromagnetic waves satisfies the following formula (1), and the dimension c of the cavity part along the traveling direction of the electromagnetic waves is an integral multiple of the antinode of the standing wave generated inside the cavity part, Equation 1 (Formula (1)) the pore diameter of the communication port is a pore diameter that satisfies the following formula (2), where r is the radius of the waveguide, Equation 2 (Formula (2)) The radius r of the waveguide of the inspection apparatus is determined from the resonance frequency through the following steps 1 to 6 1. Determine the resonant frequency of the standing wave of the electromagnetic wave generated within the cavity resonator.

2. The communication port of the filamentous body is positioned directly above the antinode of the standing wave of the electromagnetic wave having the resonant frequency.

3. Assume that the aforementioned communication port is similar to that of a circular waveguide.

4. The propagation mode inside the waveguide is determined from the resonant frequency and the length of the circular waveguide.

5. Based on the identified propagation mode, the k value included in the formula 2 for determining the cutoff frequency fc is determined.

6. The cutoff frequency fc is set as the upper limit of the frequency included in the electromagnetic waves generated in the cavity resonator, and the diameter r of the communication opening is determined by formula 2. A method for manufacturing an inspection device, wherein the size is determined by the method described above.

2. A method for manufacturing the inspection apparatus according to claim 1, wherein one or more antinodes of standing waves are generated inside the cavity resonator from the inlet to the outlet of the cavity.

3. The method for manufacturing the inspection apparatus according to claim 2, wherein the cavity resonator has an odd number of antinodes n for the standing waves generated inside the cavity.

4. The method for manufacturing the inspection apparatus according to claim 3, wherein the cavity resonator has a number of antinodes n of standing waves generated inside the cavity portion that is 3 or more.

5. The method for manufacturing the inspection apparatus according to claim 1, wherein the connecting passage is formed so that the filamentous body passes through a predetermined range from the antinodes of the standing waves generated inside the cavity in the vibration mode.

6. The method for manufacturing the inspection apparatus according to any one of claims 1 to 5, wherein the cavity resonator has a rectangular parallelepiped cavity.

7. The method for manufacturing an inspection apparatus according to any one of claims 1 to 6, wherein the inlet and outlet are formed by an iris.

8. A method for manufacturing an inspection apparatus according to any one of claims 1 to 7, wherein the inner surface of the cavity is made of metal.

9. The method for manufacturing an inspection apparatus according to any one of claims 1 to 8, wherein the cavity resonator is provided with a plurality of connecting passages for passing a plurality of filamentous bodies.

10. The method for manufacturing an inspection apparatus according to claim 9, wherein each of the plurality of connecting passages is provided at a predetermined interval such that the filamentous body passes through a predetermined range from the antinodes of standing waves generated inside the cavity.

11. The method for manufacturing an inspection apparatus according to any one of claims 1 to 10, wherein the calculation unit evaluates the state of the filamentous body based on at least one of the fluctuation in the intensity of a predetermined resonant frequency contained in the electromagnetic wave and the fluctuation in the generation frequency of the electromagnetic wave.

12. The method for manufacturing an inspection apparatus according to any one of claims 1 to 11, wherein the oscillator generates a continuous wave including a first range of frequencies centered on a predetermined resonant frequency.

13. The method for manufacturing an inspection apparatus according to any one of claims 1 to 11, wherein the oscillator generates a chirp wave that includes a resonant frequency in a continuous manner.

14. A method for manufacturing an inspection apparatus according to any one of claims 1 to 11 and 13, wherein the calculation unit evaluates whether or not there is an abnormality in the filamentous material based on at least one of the difference in frequency between a first chirp wave emitted by the oscillator and received by the receiver via the cavity resonator and a second chirp wave having a different degree of frequency variation over time from the chirp wave emitted by the oscillator, and the difference in signal intensity.

15. A method for manufacturing an inspection apparatus according to any one of claims 1 to 14, comprising a protective tube disposed inside the cavity resonator and separating the communication passage from the cavity inside the cavity resonator.

16. The method for manufacturing an inspection apparatus according to any one of claims 1 to 15, wherein the communication port is set to a size such that electromagnetic waves having a frequency within a predetermined measurement range defined by the cutoff frequency of the waveguide do not leak out of the cavity.

17. A method for manufacturing an inspection apparatus according to any one of claims 1 to 16, wherein the inner diameter of the inlet and the inner diameter of the outlet are smaller than 15% of the cross-sectional area of ​​the cavity provided in the cavity resonator in a direction perpendicular to the line segment connecting the inlet and the outlet.

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