Inspection apparatus and inspection method

Abstract

To provide an inspection device and an inspection method capable of improving detection accuracy.SOLUTION: According to an embodiment, an inspection apparatus includes a detection unit and a conveyance unit. The detection unit includes a transmission unit that transmits a first ultrasonic wave of a first wavelength, a reception unit on which the first ultrasonic wave is incident, a first waveguide including a first end portion, and a second waveguide including a second end portion facing the first end portion. The conveyor conveys the inspection object between the first end and the second end along a second direction intersecting the first direction from the transmitter to the receiver. A gap length along the first direction between the first end portion and the second end portion is not less than 0.7 times N / 4 of the first wavelength and less than N / 4 times the first wavelength. N is an odd number greater than or equal to 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to an inspection apparatus and an inspection method. [Background technology]

[0002] For example, there are inspection devices that use ultrasound, etc. Improvement of inspection accuracy is desired. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-42612 Summary of the Invention [Problem to be solved by the invention]

[0004] The embodiments of the present invention provide an inspection device and an inspection method that can improve inspection accuracy. [Means for solving the problem]

[0005] According to an embodiment of the present invention, an inspection device includes a detection unit and a transport unit. The detection unit includes a transmission unit configured to transmit a first ultrasonic wave of a first wavelength; a reception unit configured to receive the first ultrasonic wave and output a signal corresponding to the incident first ultrasonic wave; a first waveguide provided between the reception unit and the transmission unit, including a first end, and configured to pass the first ultrasonic wave; and a second waveguide provided between the first waveguide and the reception unit, including a second end spaced from the first waveguide and facing the first end, and configured to pass the first ultrasonic wave. The transport unit is configured to transport the inspection object between the first end and the second end along a second direction intersecting a first direction from the transmission unit to the reception unit. A gap length along the first direction between the first end and the second end is equal to or greater than 0.7 times N / 4 of the first wavelength and less than N / 4 times the first wavelength, where N is an odd number equal to or greater than 1. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic side view illustrating the inspection device according to the first embodiment. [Figure 2] FIG. 2 is a graph illustrating the characteristics of the inspection device. [Figure 3] FIG. 3 is a graph illustrating the characteristics of the inspection device. [Figure 4] FIG. 4 is a schematic perspective view illustrating the inspection device according to the first embodiment. [Figure 5] FIG. 5 is a flowchart illustrating the inspection method according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In this specification and in each drawing, elements similar to those previously described with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions thereof will be omitted where appropriate.

[0008] (First embodiment) FIG. 1 is a schematic side view illustrating the inspection device according to the first embodiment. As shown in FIG. 1, an inspection device 110 according to the embodiment includes a detection unit 10 and a transport unit 60.

[0009] The detection unit 10 includes a transmitter 11, a receiver 12, a first waveguide 21, and a second waveguide 22. The transmitter 11 is configured to transmit a first ultrasonic wave 11w. The first ultrasonic wave 11w has a first wavelength λ. In the embodiment, the first wavelength λ may be, for example, not less than 2 mm and not more than 11 mm. The frequency of the first ultrasonic wave 11w may be, for example, not less than 30 kHz and not more than 150 kHz.

[0010] The first ultrasonic wave 11w is incident on the receiving unit 12. The receiving unit 12 is configured to output a signal (received signal Sd) corresponding to the incident first ultrasonic wave 11w.

[0011] The first waveguide 21 is provided between the receiving unit 12 and the transmitting unit 11. The first waveguide 21 includes a first end 21e. The first waveguide 21 is configured to pass a first ultrasonic wave 11w.

[0012] The second waveguide 22 is provided between the first waveguide 21 and the receiving unit 12. The second waveguide 22 is spaced apart from the first waveguide 21. The second waveguide 22 includes a second end 22e. The second end 22e faces the first end 21e. The second waveguide 22 is configured to pass the first ultrasonic wave 11w.

[0013] A control unit 70 may be provided in the inspection device 110. The control unit 70 may be included in the inspection device 110. The control unit 70 may be provided separately from the inspection device 110. The control unit 70 may include a transmitting circuit 11D and a receiving circuit 12D.

[0014] The transmission circuit 11D is configured to cause the transmission unit 11 to emit a first ultrasonic wave 11w. For example, a control signal Sc is supplied from the control unit 70 to the transmission circuit 11D. The transmission circuit 11D supplies a drive signal Sv to the transmission unit 11 based on the control signal Sc. The first layer 11f included in the transmission unit 11 vibrates based on the drive signal Sv, thereby generating the first ultrasonic wave 11w. The first ultrasonic wave 11w may be, for example, a burst wave.

[0015] The receiving circuit 12D is configured to detect a receiving signal Sd obtained from the receiving unit 12. The second layer 12f included in the receiving unit 12 vibrates due to the incident first ultrasonic wave 11w. The receiving unit 12 generates a receiving signal Sd (electrical signal) corresponding to the vibration. The generated receiving signal Sd (electrical signal) is detected by the receiving circuit 12D. The transmitting unit 11 and the receiving unit 12 may include a piezoelectric element or the like.

[0016] The transport unit 60 is configured to transport the inspection object 80 between the first end 21e and the second end 22e along a second direction D2 that intersects with the first direction D1 from the transmitter 11 to the receiver 12. The inspection object 80 moves in the space SP between the first end 21e and the second end 22e.

[0017] For example, the inspection object 80 is placed on the conveying unit 60. For example, the conveying unit 60 is moved by a first conveying mechanism 61 (for example, a roller) and a second conveying mechanism 62 (for example, a roller), and the inspection object 80 is conveyed as the conveying unit 60 moves.

[0018] The second direction D2 (e.g., the conveying direction) is defined as the X-axis direction. A direction perpendicular to the X-axis direction is defined as the Y-axis direction. A direction perpendicular to the X-axis direction and the Y-axis direction is defined as the Z-axis direction. The inspection object 80 is conveyed along the XY plane. The first direction D1 may be, for example, along the Z-axis direction. The first direction D1 may be inclined with respect to the Z-axis direction.

[0019] The inspection object 80 is, for example, a paper sheet. The inspection object 80 is, for example, a banknote. The inspection object 80 may also be a document such as a security. The inspection object 80 may also be, for example, mail. The material of the inspection object 80 is arbitrary. The inspection object 80 may be paper, a plastic film, or the like.

[0020] For example, at least a portion of the first ultrasonic wave 11w emitted from the transmitter 11 and passing through the first waveguide 21 passes through the inspection object 80. The first ultrasonic wave 11w that has passed through the inspection object 80 is incident on the receiver 12 via the second waveguide 22. The first ultrasonic wave 11w that is incident on the receiver 12 changes depending on the state of the inspection object 80. The changing first ultrasonic wave 11w is received by the receiver 12. The reception signal Sd output from the receiver 12 reflects the state of the inspection object 80. For example, the control unit 70 can process the reception signal Sd and output an inspection signal S1. The inspection signal S1 includes information regarding the inspection result of the inspection object 80. The state of the inspection object 80 may include, for example, the presence or absence of a foreign object. The inspection device 110 can inspect, for example, banknotes.

[0021] In the embodiment, a portion (direct wave) of the first ultrasonic wave 11w emitted from the first waveguide 21 passes through the test object 80 and can be incident on the receiving unit 12. Another portion (first reflected wave) of the first ultrasonic wave 11w emitted from the first waveguide 21 is reflected by the test object 80, and the reflected first ultrasonic wave 11w is reflected at the first end 21e of the first waveguide 21 and may be incident on the receiving unit 12 after passing through the test object 80. Furthermore, another portion (second reflected wave) of the first ultrasonic wave 11w emitted from the first waveguide 21 is reflected at the second end 22e after passing through the test object 80 and may be reflected at the test object 80 and may be incident on the receiving unit 12.

[0022] The first reflected wave and the second reflected wave described above become noise components relative to the direct wave for inspection. When the gap length Lg (see FIG. 1) along the first direction D1 between the first end 21e and the second end 22e satisfies a specific condition, the first reflected wave and the second reflected wave are considered to substantially cancel each other out, reducing noise. For example, the specific condition described above is considered to be satisfied when the gap length Lg is an odd multiple of ¼ of the first wavelength λ.

[0023] FIG. 2 is a graph illustrating the characteristics of the inspection device. 2, the horizontal axis represents the normalized gap length Lg1, and the vertical axis represents the normalized noise parameter NP1. In FIG. 2, the moving speed of the inspection object 80 is changed.

[0024] In FIG. 2, the gap length Lg varies within a range of approximately 5 times ¼ of the first wavelength λ. The horizontal axis of FIG. 2 is the normalized gap length Lg1. The normalized gap length Lg1 is the ratio of the set gap length Lg to 5×λ / 4. The vertical axis of FIG. 2 is the normalized noise parameter NP1. The ratio of the fluctuation component contained in the received signal Sd to the average value of the received signal Sd is defined as the noise parameter NP0. The normalized noise parameter NP1 is normalized by the noise parameter NP0 when the gap length Lg is 5×λ / 4. It is preferable that the normalized noise parameter NP1 is small.

[0025] When the moving speed vs is 0 and the normalized gap length Lg1 is 1, the normalized noise parameter NP1 is minimized. This is because the first reflected wave and the second reflected wave cancel each other out when the gap length Lg is 5×λ / 4.

[0026] 2, when the moving speed vs is 4.8 m / s, 6.1 m / s, or 8.2 m / s, the normalized noise parameter NP1 becomes minimal when the normalized gap length Lg1 is smaller than 1. Under practical conditions where the inspection object 80 moves, it is believed that the movement of the inspection object 80 affects the noise.

[0027] For example, it is believed that the movement of the inspection object 80 will cause variations in the density of the air in the space SP through which the inspection object 80 moves and its surroundings. For example, non-uniformity in the air pressure will occur. For example, it is believed that changes will occur in the propagation characteristics of the ultrasonic waves near at least one of the first end 21e of the first waveguide 21 and the second end 22e of the second waveguide 22. It is believed that these changes are related to the characteristics shown in FIG. 2.

[0028] As described above, it was found that when the inspection object 80 is moving, noise is not necessarily reduced when the gap length Lg is an odd multiple of 1 / 4 of the first wavelength λ. It was also found that when the inspection object 80 is moving, noise is reduced when the gap length Lg is shorter than an odd multiple of 1 / 4 of the first wavelength λ.

[0029] In the embodiment, it is preferable that the gap length Lg along the first direction D1 between the first end 21e and the second end 22e satisfies the first formula. 0.7×λ×N / 4 ≦ Lg < λ×N / 4 (1) In the first formula, "N" is an odd number greater than or equal to 1. In the example of the experimental results in FIG. 2, "N" is 5.

[0030] It is preferable that the gap length Lg is equal to or greater than 0.7 times N / 4 times the first wavelength λ and less than N / 4 times the first wavelength λ. This allows a small noise parameter NP0 to be obtained. The influence of noise is suppressed. This allows highly accurate detection results to be obtained. According to the embodiment, an inspection device capable of improving inspection accuracy can be provided.

[0031] For example, when the inspection target 80 passes through the space SP between the first end 21e and the second end 22e, the position in the first direction D1 may fluctuate. For example, when multiple inspection targets 80 pass through the space SP between the first end 21e and the second end 22e, the position in the first direction D1 may fluctuate. According to the embodiment, the influence of such position fluctuations is suppressed.

[0032] In an embodiment, the gap length Lg may be equal to or less than 0.98 times N / 4 times the first wavelength λ, which results in a smaller noise parameter NP0. The gap length Lg may be equal to or less than 0.95 times N / 4 times the first wavelength λ.

[0033] 2, the normalized gap length Lg1 at which the normalized noise parameter NP1 is minimized decreases as the moving speed vs increases, and the shift amount ΔLg from 1 of the normalized gap length Lg1 at which the normalized noise parameter NP1 is minimized increases as the moving speed vs increases.

[0034] FIG. 3 is a graph illustrating the characteristics of the inspection device. 3, the horizontal axis represents the moving speed vs. The vertical axis represents the normalized gap length Lg1(min) at which the normalized noise parameter NP1 is minimized. The difference between the normalized gap length Lg1(min) and 1 corresponds to the shift amount ΔLg from N / 4 times the first wavelength λ.

[0035] As shown in Figure 3, as the moving speed vs increases, the normalized gap length Lg1(min) decreases. When the moving speed vs is 3 m / s or higher, noise can be suppressed by making the gap length Lg shorter than λ / 4 × N (N is an odd number greater than or equal to 1). For example, when the moving speed vs is 3 m / s or higher, the effects of air density as described above are thought to occur.

[0036] When the moving speed vs is high, the range of gap length Lg in which a small noise parameter NP0 is obtained widens. In the embodiment, the moving speed vs (transport speed) of the inspection object 80 may be 3 m / s or more. The moving speed vs may be 5 m / s or more. The moving speed vs may be, for example, 7 m / s or more and 12 m / s or less. The moving speed vs may be, for example, 7 m / s or more and 10 m / s or less.

[0037] In the embodiment, "N" may be 3 or more and 9 or less. When "N" is 3 or more, the gap length Lg is prevented from becoming excessively short. This prevents damage to the waveguide or the test object 80 when the position of the test object 80 in the first direction D1 changes excessively during transportation. When "N" is 9 or less, the gap length Lg is prevented from becoming excessively long. For example, the effects of noise can be suppressed.

[0038] "N" may be 5 or 7. "N" may be 5. Practically, the gap length Lg may be 3 mm or more and 8 mm or less.

[0039] In this embodiment, the value (m / s) of the moving speed vs of the inspection object 80 may be equal to or greater than 0.75 (m / s) times the value (mm) of the gap length Lg, and equal to or less than 2.5 (m / s) times the gap length Lg (mm).

[0040] As shown in FIG. 1, the first end 21e has a first inner diameter d1. The first inner diameter d1 is the inner diameter of the first end 21e along a transverse direction that intersects with the first direction D1. For example, the transverse direction is perpendicular to the first direction D1. The second end 22e has a second inner diameter d2. The second inner diameter d2 is the inner diameter of the second end 22e along the transverse direction.

[0041] In this embodiment, the first inner diameter d1 may be 0.5 to 4 times the gap length Lg. For example, the second inner diameter d2 may be 0.5 to 4 times the gap length Lg. With such inner diameters, when the normalized gap length Lg1 is smaller than 1, the normalized noise parameter NP1 is likely to become minimal.

[0042] The first length L1 of the first waveguide 21 along the first direction D1 may be four times or more the first inner diameter d1. The second length L2 of the second waveguide 22 along the first direction D1 may be four times or more the second inner diameter d2. This makes it easier to obtain highly directional first ultrasonic waves 11w.

[0043] In the embodiment, the test object 80 may pass through a substantial center in the first direction D1 between the first end 21e and the second end 22e. For example, the test object 80 passes through a first position P1 between the first end 21e and the second end 22e (see FIG. 1 ). The distance between the first position P1 and the first end 21e along the first direction D1 is defined as a first distance. The distance between the first position P1 and the second end 22e along the first direction D1 is defined as a second distance. The first difference between the first distance and the second distance may be substantially 0. For example, the ratio of the first absolute value of the first difference to the first distance may be greater than or equal to 0 and less than or equal to 0.5. Noise is suppressed. This ratio may be less than or equal to 0.25.

[0044] FIG. 4 is a schematic perspective view illustrating the inspection device according to the first embodiment. 4 , the inspection device 111 according to the embodiment includes a plurality of detection units 10 and a transport unit 60. The inspection device 111 may include a control unit 70. In the inspection device 111, the configuration of each of the plurality of detection units 10 may have the configuration described for the inspection device 110.

[0045] In the inspection device 111, a direction from a first waveguide 21 included in one of the plurality of detecting units 10 to a first waveguide 21 included in another of the plurality of detecting units 10 (e.g., third direction D3) intersects with a plane including the first direction D1 and the second direction D2. For example, the plurality of detecting units 10 may be arranged along a direction (third direction D3) intersecting with a plane including the first direction D1 and the second direction D2. The plurality of detecting units 10 can detect the in-plane distribution of a characteristic (e.g., thickness) of the inspection object 80.

[0046] In the inspection device 111, the above formula 1 is applied to at least one of the multiple detection units 10. The influence of noise is suppressed. For example, the tolerance range of the gap length Lg is relaxed in the multiple detection units 10. By relaxing the tolerance range, for example, it is possible to reduce manufacturing costs. A more practical, high-precision inspection device is provided.

[0047] (Second embodiment) The second embodiment relates to an inspection method. The inspection method according to the embodiment may include inspecting an inspection object 80 using the inspection device according to the first embodiment.

[0048] FIG. 5 is a flowchart illustrating the inspection method according to the second embodiment. For example, the inspection method according to the embodiment includes transporting the inspection object 80 between the first end 21e of the first waveguide 21 and the second end 22e of the second waveguide 22 along a second direction D2 that intersects with a first direction D1 from the transmitter 11 to the receiver 12 (step S110). The inspection method also includes inspecting the inspection object 80 (step S120).

[0049] The transmitting unit 11 is configured to transmit a first ultrasonic wave 11w of a first wavelength λ. The first ultrasonic wave 11w is incident on the receiving unit 12. The receiving unit 12 is configured to output a signal (received signal Sd) corresponding to the incident first ultrasonic wave 11w. The first waveguide 21 is provided between the receiving unit 12 and the transmitting unit 11. The first waveguide 21 is configured to pass the first ultrasonic wave 11w. The second waveguide 22 is provided between the first waveguide 21 and the receiving unit 12. The second waveguide 22 is spaced apart from the first waveguide 21. The second waveguide 22 is configured to pass the first ultrasonic wave 11w. The second end 22e faces the first end 21e. A gap length Lg along the first direction D1 between the first end 21e and the second end 22e is not less than 0.7 times N / 4 times the first wavelength λ and less than N / 4 times the first wavelength λ. "N" is an odd number equal to or greater than 1. The influence of noise is suppressed. An inspection method that can improve inspection accuracy is provided.

[0050] In the inspection method according to the embodiment, the gap length Lg may be equal to or less than 0.98 times N / 4 times the first wavelength λ. In the inspection method according to the embodiment, the configuration described in relation to the first embodiment may be applied.

[0051] The embodiments may include the following technical solutions. (Technical proposal 1) A detection unit; A conveying unit; Equipped with The detection unit a transmitter configured to transmit a first ultrasonic wave at a first wavelength; a receiving unit configured to receive the first ultrasonic wave and to output a signal corresponding to the first ultrasonic wave; a first waveguide disposed between the receiving unit and the transmitting unit, the first waveguide including a first end and configured to pass the first ultrasonic wave; a second waveguide provided between the first waveguide and the receiving unit, the second waveguide including a second end spaced apart from the first waveguide and facing the first end, and configured to pass the first ultrasonic wave; Including, the transport unit is configured to transport the test object between the first end and the second end along a second direction intersecting a first direction from the transmitter to the receiver; a gap length along the first direction between the first end and the second end is equal to or greater than 0.7 times N / 4 times the first wavelength and less than N / 4 times the first wavelength; The inspection apparatus, wherein N is an odd number greater than or equal to 1.

[0052] (Technical proposal 2) The inspection device described in Technical Solution 1, wherein the gap length is less than or equal to 0.98 times N / 4 times the first wavelength.

[0053] (Technical proposal 3) The inspection device described in Technical Solution 1, wherein the gap length is less than or equal to 0.95 times N / 4 times the first wavelength.

[0054] (Technical proposal 4) The inspection device according to any one of Technical Schemes 1 to 3, wherein N is 3 or more and 9 or less.

[0055] (Technical proposal 5) The inspection device according to any one of technical proposals 1 to 3, wherein N is 5 or 7.

[0056] (Technical proposal 6) The first end has a first inner diameter along a transverse direction that intersects with the first direction, The inspection device according to any one of Technical Schemes 1 to 5, wherein the first inner diameter is 0.5 to 4 times the gap length.

[0057] (Technical proposal 7) The second end has a second inner diameter along the intersecting direction, The inspection device described in Technical Proposal 6, wherein the second inner diameter is 0.5 times or more and 4 times or less the gap length.

[0058] (Technical proposal 8) The inspection device described in Technical Proposal 7, wherein a second length of the second waveguide along the first direction is four times or more the second inner diameter.

[0059] (Technical proposal 9) The inspection device according to any one of Technical Schemes 6 to 8, wherein a first length of the first waveguide along the first direction is four times or more the first inner diameter.

[0060] (Technical proposal 10) The inspection device according to any one of Technical Schemes 1 to 9, wherein the moving speed of the inspection object is 3 m / s or more.

[0061] (Technical proposal 11) The inspection device described in Technical Proposal 10, wherein the moving speed is 7 m / s or more and 10 m / s or less.

[0062] (Technical proposal 12) An inspection device according to any one of technical proposals 1 to 9, wherein the value of the movement speed (m / s) of the object to be inspected is 0.75 times or more and 2.5 times or less the value of the gap length (mm).

[0063] (Technical proposal 13) The inspection device according to any one of Technical Schemes 1 to 12, wherein the gap length is 3 mm or more and 8 mm or less.

[0064] (Technical proposal 14) the test object passes through a first position between the first end and the second end, An inspection device described in any one of Technical Proposals 1 to 13, wherein a ratio of a first absolute value of a first difference between a first distance along the first direction between the first position and the first end and a second distance along the first direction between the first position and the second end to the first distance is greater than or equal to 0 and less than 0.5.

[0065] (Technical proposal 15) The inspection device according to any one of Technical Schemes 1 to 14, comprising a plurality of the detection units.

[0066] (Technical proposal 16) The inspection device described in Technical Proposal 15, wherein a direction from the first waveguide included in one of the plurality of detection units to the first waveguide included in another of the plurality of detection units intersects with a plane including the first direction and the second direction.

[0067] (Technical proposal 17) The inspection device described in Technical Proposal 15, wherein the multiple detection units are arranged along a direction intersecting a plane including the first direction and the second direction.

[0068] (Technical proposal 18) a control unit including a transmitting circuit and a receiving circuit; the transmission circuit is configured to cause the transmission unit to emit the first ultrasonic wave; The inspection device according to any one of Technical Schemes 1 to 17, wherein the receiving circuit is configured to detect a received signal obtained from the receiving unit.

[0069] (Technical proposal 19) conveying the test object between a first end of the first waveguide and a second end of the second waveguide along a second direction intersecting the first direction from the transmitter to the receiver; Inspecting the inspection object, the transmitting unit is configured to transmit a first ultrasonic wave of a first wavelength; the receiving unit is configured to receive the first ultrasonic wave and to output a signal corresponding to the first ultrasonic wave that has been received; the first waveguide is provided between the receiving unit and the transmitting unit and is configured to pass the first ultrasonic wave; the second waveguide is provided between the first waveguide and the receiving unit, is separated from the first waveguide, and is configured to pass the first ultrasonic wave; the second end faces the first end, a gap length along the first direction between the first end and the second end is equal to or greater than 0.7 times N / 4 times the first wavelength and less than N / 4 times the first wavelength; An inspection method, wherein N is an odd number greater than or equal to 1.

[0070] (Technical proposal 20) The inspection method described in Technical Solution 19, wherein the gap length is less than or equal to 0.98 times N / 4 times the first wavelength.

[0071] According to the embodiment, it is possible to provide an inspection device and an inspection method that can improve detection accuracy.

[0072] The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, the specific configurations of the elements included in the inspection device, such as the detection unit, transmission unit, reception unit, transport unit, and control unit, are within the scope of the present invention as long as a person skilled in the art can implement the present invention in a similar manner and obtain similar effects by appropriately selecting them from known ranges.

[0073] Furthermore, any combination of two or more elements of each specific example within the scope of technical feasibility is also included within the scope of the present invention as long as it includes the gist of the present invention.

[0074] In addition, all inspection devices and inspection methods that can be implemented by a person skilled in the art by appropriately modifying the design based on the inspection device and inspection method described above as embodiments of the present invention also fall within the scope of the present invention, as long as they include the gist of the present invention.

[0075] In addition, within the scope of the concept of the present invention, a person skilled in the art may come up with various modifications and alterations, and it will be understood that these modifications and alterations also fall within the scope of the present invention.

[0076] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0077] 10: detection unit, 11: transmission unit, 11D: transmission circuit, 11f: first layer, 11w: first ultrasonic wave, 12: reception unit, 12D: reception circuit, 12f: second layer, 21, 22: first and second waveguides, 21e, 22e: first and second ends, 60: transport unit, 61, 62: first and second transport mechanisms, 70: control unit, 80: inspection object, 110, 111: inspection device, D1 to D3: first to third directions, L1, L2: first and second lengths, Lg: gap length, Lg1: normalized gap length, NP0: noise parameter, NP1: normalized noise parameter, P1: first position, S1: inspection signal, SP: space, Sc: control signal, Sd: received signal, Sv: drive signal, d1, d2: 1st, 2nd inner diameter

Claims

1. A detection unit; A conveying unit; Equipped with The detection unit a transmitter configured to transmit a first ultrasonic wave at a first wavelength; a receiving unit configured to receive the first ultrasonic wave and to output a signal corresponding to the first ultrasonic wave; a first waveguide disposed between the receiver and the transmitter, the first waveguide including a first end and configured to pass the first ultrasonic wave; a second waveguide provided between the first waveguide and the receiving unit, the second waveguide including a second end spaced from the first waveguide and opposite the first end, and configured to pass the first ultrasonic wave; Including, the transport unit is configured to transport the test object between the first end and the second end along a second direction intersecting a first direction from the transmitter to the receiver; a gap length along the first direction between the first end and the second end is equal to or greater than 0.7 times N / 4 times the first wavelength and less than N / 4 times the first wavelength, An inspection apparatus, wherein N is an odd number equal to or greater than 1.

2. The inspection device according to claim 1 , wherein the gap length is equal to or less than 0.95 times the N / 4 times the first wavelength.

3. 3. The inspection device according to claim 2, wherein N is 5 or 7.

4. The first end has a first inner diameter along a transverse direction that intersects with the first direction, The inspection device according to claim 3 , wherein the first inner diameter is equal to or greater than 0.5 times and equal to or less than 4 times the gap length.

5. The second end has a second inner diameter along the transverse direction, The inspection device according to claim 4 , wherein the second inner diameter is equal to or greater than 0.5 times and equal to or less than 4 times the gap length.

6. The inspection device according to claim 1 , wherein the moving speed of the inspection object is 3 m / s or more.

7. the test object passes through a first position between the first end and the second end, 2. The inspection device of claim 1, wherein a ratio of a first absolute value of a first difference between a first distance along the first direction between the first position and the first end and a second distance along the first direction between the first position and the second end to the first distance is greater than or equal to 0 and less than 0.

5.

8. The inspection device according to claim 1 , comprising a plurality of the detection units.

9. 9. The inspection device according to claim 8, wherein a direction from the first waveguide included in one of the plurality of detection units to the first waveguide included in another of the plurality of detection units intersects a plane including the first direction and the second direction.

10. conveying the test object between the first end of the first waveguide and the second end of the second waveguide along a second direction intersecting the first direction from the transmitter to the receiver; Inspecting the inspection object, the transmitter is configured to transmit a first ultrasonic wave having a first wavelength; the receiving unit is configured to receive the first ultrasonic wave and to output a signal corresponding to the incident first ultrasonic wave; the first waveguide is provided between the receiving unit and the transmitting unit and is configured to pass the first ultrasonic wave; the second waveguide is provided between the first waveguide and the receiving unit, is separated from the first waveguide, and is configured to pass the first ultrasonic wave; the second end faces the first end, a gap length along the first direction between the first end and the second end is equal to or greater than 0.7 times N / 4 times the first wavelength and less than N / 4 times the first wavelength, An inspection method, wherein N is an odd number greater than or equal to 1.

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