Surface detection sensor and sensor system including same

Abstract

The purpose of the present disclosure is to shorten the time required for visually inspecting a subject. This surface detection sensor (1) comprises a plurality of electrode blocks (10). Each of the plurality of electrode blocks (10) has: an electrode (11) which is disposed on a base material (20); and a contactor (12) which can be brought into contact with a surface of a subject (200). At least a portion of an elastic member (30) is interposed between the electrode (11) and the contactor (12). The plurality of electrode blocks (10) are arranged side-by-side along a second direction. The second direction intersects a first direction (DR1) in which the contactor (12) is moved relative to the subject (200).

Description

Surface detection sensor and sensor system including same

[0001] The present disclosure relates to a surface detection sensor and a sensor system including the same. More particularly, the present disclosure relates to a surface detection sensor for performing visual inspection of an object and a sensor system including the same.

[0002] Patent Document 1 discloses a method for inspecting the appearance of a glossy surface of a component. In this method, tactile sensors are placed on both the front and rear sides of a battery, which is the component to be inspected, and an equal load is applied to both the front and rear sides of the battery via the front and rear tactile sensors. The surface pressure distribution on both the front and rear sides is then obtained based on the output values ​​of the front and rear tactile sensors, and areas of the surface pressure distribution with relatively low surface pressure are determined to be defective.

[0003] When applying the visual inspection method of Patent Document 1 to the visual inspection of a large object such as an automobile body, it is difficult to prepare a tactile sensor that can cover the entire surface of the object. Therefore, the inspection work of covering the surface of the object with the tactile sensor while gradually shifting the position of the tactile sensor must be repeated multiple times, which may increase the inspection time.

[0004] JP 2014-70921 A

[0005] An object of the present disclosure is to provide a surface detection sensor that can reduce the time required for visual inspection of an object to be inspected, and a sensor system including the same.

[0006] A surface detection sensor according to one aspect of the present disclosure includes a plurality of electrode blocks, a substrate supporting the plurality of electrode blocks, and an elastic member. Each of the plurality of electrode blocks has an electrode disposed on the substrate and a contactor capable of contacting the surface of a subject. At least a portion of the elastic member is interposed between the electrode of each of the plurality of electrode blocks and the contactor. The plurality of electrode blocks are arranged side by side along a second direction. The second direction intersects with a first direction in which the contactor moves relative to the subject.

[0007] A sensor system according to an aspect of the present disclosure includes the surface detection sensor and a pressing mechanism, to which the base material is attached via an elastic buffer member, and which presses the contacts of the electrode blocks against the surface of the subject.

[0008] FIG. 1 is a schematic cross-sectional view of a surface detection sensor according to an embodiment of the present disclosure, as viewed from below. FIG. 2 is a schematic plan view of the surface detection sensor as viewed from the front. FIG. 3 is a schematic cross-sectional view of the surface detection sensor as viewed from the right. FIG. 4 is a schematic cross-sectional view of another aspect of the surface detection sensor as viewed from above. FIG. 5 is a schematic cross-sectional view of another aspect of the surface detection sensor as viewed from above. FIG. 6 is a schematic cross-sectional view of the surface detection sensor as viewed from above. FIG. 7 is a schematic cross-sectional view of the surface detection sensor as viewed from the right. FIG. 8 is a schematic circuit diagram of the surface detection sensor as viewed from above. FIG. 9 is a graph showing an example of an oscillation signal of an oscillation circuit and a demodulation signal of a detection circuit included in the surface detection sensor as viewed from above. FIG. 10 is a schematic cross-sectional view of a sensor system including the surface detection sensor as viewed from above. FIG. 11 is a schematic circuit diagram of a surface detection sensor according to a first modification. FIG. 12 is a diagram showing a transformation result of a Fourier transform unit included in the surface detection sensor as viewed from above. FIG. 13 is a schematic circuit diagram of a surface detection sensor according to a second modification. Fig. 14 is a diagram showing measurement results of an impedance measurement unit provided in the surface detection sensor of the same. Fig. 15 is a schematic plan view seen from the front of the surface detection sensor according to Modification 3. Fig. 16 is a schematic cross-sectional view seen from above the surface detection sensor of the same.

[0009] Hereinafter, a surface detection sensor according to an embodiment and a sensor system including the same will be described in detail with reference to the drawings. However, each diagram described in the following embodiments is a schematic diagram, and the dimensional ratios of the sizes of the components do not necessarily reflect the actual dimensional ratios. Furthermore, the configurations described in the following embodiments are merely examples of the present disclosure. The present disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved.

[0010] (Embodiment) (1) Overview As shown in FIGS. 1 and 2 , a surface detection sensor 1 according to this embodiment includes a plurality of electrode blocks 10, a substrate 20, and an elastic member 30.

[0011] The substrate 20 supports a plurality of electrode blocks 10 .

[0012] Each of the plurality of electrode blocks 10 has an electrode 11 arranged on a substrate 20 and a contact 12 that can come into contact with a surface 201 of a subject 200 .

[0013] At least a part of the elastic member 30 is interposed between the electrode 11 and the contact 12 of each of the plurality of electrode blocks 10 .

[0014] The plurality of electrode blocks 10 are arranged side by side along a second direction DR2, which intersects with the first direction DR1 in which the contacts 12 are moved relative to the subject 200.

[0015] Here, the second direction DR2 is, for example, a direction that intersects the first direction DR1 at a right angle, but the angle at which the first direction DR1 and the second direction DR2 intersect is not limited to 90 degrees. The angle at which the first direction DR1 and the second direction DR2 intersect may be, for example, an angle between 80 degrees and 100 degrees, and can be changed appropriately depending on the shape of the surface 201 of the subject 200, etc.

[0016] The surface detection sensor 1 is used, for example, to detect defective portions on the surface 201 of the test object 200. More specifically, the surface detection sensor 1 is used to perform an appearance inspection of the surface 201 of the test object 200. When the test object 200 is, for example, an automobile body 210 and an appearance inspection is performed on a coating film 220 formed on the surface of the car body 210, the surface detection sensor 1 inspects whether or not defective portions such as peeling, flaking, drips, dust (bumps), or repellencies have occurred on the surface of the coating film 220. Note that "peeling" refers to a state in which the coating film 220 has peeled off due to impurities or the like. "Flags" refers to a state in which small bubble-like blisters or holes have occurred during the curing or drying of the coating film 220. "Drips" refers to a state in which paint flows downward when forming the coating film 220 on a vertical or inclined surface, causing the coating film 220 to become thicker in parts, resulting in an uneven thickness of the coating film 220. "Dust (bumps)" refers to a state in which foreign matter adheres to the surface (finished surface) of the paint film 220, forming protrusions. "Repelling" refers to a state in which, after painting the surface of the vehicle body 210, the paint does not adhere evenly, causing partial depressions in the paint film 220.

[0017] When detecting a defect on the surface 201 of the subject 200 using the surface detection sensor 1, the contactors 12 of the electrode blocks 10 are pressed against the surface 201 of the subject 200 and the contactors 12 are moved relative to the subject 200. When the contactors 12 of at least one electrode block 10 move over the surface 201 of the subject 200 and come into contact with a defect occurring on the surface 201 of the subject 200, the elastic member 30 interposed between the contactor 12 of at least one electrode block 10 and the electrode 11 expands and contracts according to the shape of the defect. For example, when the contactor 12 of at least one electrode block 10 comes into contact with a protruding defect occurring on the surface 201 of the subject 200, the elastic member 30 is compressed, thereby reducing the volume of the elastic member 30 present between the subject 200 and the electrode 11 and reducing the parasitic capacitance occurring between the subject 200 and the electrode 11. On the other hand, when the contact 12 of at least one electrode block 10 hits a concave defect that occurs on the surface 201 of the subject 200, the elastic member 30 stretches, increasing the volume of the elastic member 30 that exists between the subject 200 and the electrode 11, and increasing the parasitic capacitance that occurs between the subject 200 and the electrode 11.

[0018] Therefore, according to the surface detection sensor 1 of this embodiment, the presence or absence of a defect on the surface 201 of the subject 200 can be detected based on a change (increase or decrease) in parasitic capacitance occurring between the subject 200 and the electrodes 11. Furthermore, by moving multiple electrode blocks 10 arranged along the second direction DR2 along the first direction DR1, defective portions on the surface 201 of the subject 200 can be detected. This increases the area that can be inspected with a single scanning operation compared to when only one electrode block 10 is used, thereby reducing the time required for inspection. Furthermore, because it is sufficient to simply rub the multiple contacts 12 provided on the surface detection sensor 1 along the surface of the subject 200, the time required for inspection can be reduced compared to when the inspection task is repeated multiple times while gradually shifting the position where the tactile sensor covers the surface of the subject. Furthermore, because the multiple electrode blocks 10 are arranged along the second direction DR2, the location of a defective portion occurring on the surface 201 of the subject 200 can be identified based on the position of the electrode block 10 where the parasitic capacitance has changed. Therefore, there is an advantage that the position of a defective portion occurring on the surface 201 of the object 200 can be identified with a positional accuracy according to the size and arrangement interval of the electrodes 11.

[0019] (2) Details The surface detection sensor 1 according to this embodiment and the sensor system 100 including the same will be described below with reference to the drawings. In the following description, the X-axis direction in FIG. 1 and other figures will be defined as the left-right direction, the Y-axis direction as the up-down direction, and the Z-axis direction as the front-rear direction. Furthermore, the positive direction in the X-axis direction will be defined as the left, the positive direction in the Y-axis direction as the up, and the positive direction in the Z-axis direction as the front. However, these directions are merely examples and are not intended to limit the directions in which the surface detection sensor 1 and the sensor system 100 are used. Furthermore, the arrows indicating the various directions in the drawings are merely shown for explanatory purposes and do not have any substance.

[0020] (2.1) Surface Detection Sensor The surface detection sensor 1 includes a sensor module 2 and a circuit module 3 .

[0021] The sensor module 2 includes a plurality of electrode blocks 10 , a substrate 20 , and an elastic member 30 .

[0022] The circuit module 3 detects the presence or absence of a defect on the surface 201 of the object to be inspected 200 based on a plurality of parasitic capacitances formed between the plurality of electrodes 11 provided on the plurality of electrode blocks 10 and the object to be inspected 200 .

[0023] (2.1.1) Sensor Module First, the configuration of the sensor module 2 will be described with reference to FIGS.

[0024] The substrate 20 is formed, for example, from a synthetic resin material, into a rectangular plate shape whose dimension in the Y-axis direction is longer than its dimension in the X-axis direction. On a first surface (the surface facing the subject 200) of the substrate 20, multiple electrodes 11 are arranged along the Y-axis direction at predetermined intervals. Furthermore, on a second surface of the substrate 20, for example, a back electrode 13 is provided so as to cover the entire second surface. The back electrode 13 faces the multiple electrodes 11 of the multiple electrode blocks 10 via the substrate 20. The back electrode 13 is arranged, for example, over the entire back surface of the substrate 20. The electrodes 11 and the back electrode 13 are formed of a metal with good conductivity, such as platinum, gold, or aluminum. Since the back electrode 13 covers the entire back surface of the substrate 20, it is possible to electromagnetically shield the back surface of the substrate 20 and suppress the occurrence of parasitic capacitance between the electrode 11 and an object located behind the substrate 20.

[0025] A plurality of electrode blocks 10 are provided on the substrate 20 .

[0026] The multiple electrode blocks 10 are lined up along the Y-axis direction on the first surface of the substrate 20. The multiple electrode blocks 10 lined up along the Y-axis direction have the same configuration. Each of the multiple electrode blocks 10 includes an electrode 11 and a contact 12. The multiple electrode blocks 10 lined up in the Y-axis direction are formed to be the same shape and size. Here, the position of a defective portion occurring on the surface 201 of the subject 200 is detected based on the position of the electrode block 10 where the parasitic capacitance has changed, so it is preferable that the size W1 (see FIG. 2 ) of each electrode block 10 in the second direction DR2 be set to the same degree as the positional accuracy when detecting the position of the defective portion.

[0027] The electrode 11 is formed in a thin plate shape from a metal material with good conductivity, such as platinum, gold, or aluminum. The electrode 11 is provided on a first surface of the substrate 20. The electrode 11 has a rectangular shape in a plan view formed by two sides along the X-axis direction and two sides along the Y-axis direction. The electrode 11 is electrically connected to the circuit module 3 via, for example, a conductive member provided on the substrate 20. In the following description, when describing individual electrodes 11, they may be referred to as electrodes 11A, 11B, 11C, etc.

[0028] The electrodes 11 provided on the first surface of the substrate 20 are covered with an elastic member 30. The elastic member 30 is formed in a thin plate shape from an elastic synthetic resin material. The elastic member 30 is arranged so as to overlap the first surface of the substrate 20. The elastic member 30 is provided across the plurality of electrodes 11 so as to cover the plurality of electrodes 11 provided on the first surface of the substrate 20. In other words, the elastic member 30 is provided across the entire plurality of electrodes 11 of the plurality of electrode blocks 10. In other words, the elastic member 30 covering the plurality of electrodes 11 is provided integrally.

[0029] The contactors 12 included in each of the multiple electrode blocks 10 are provided on the surface of the elastic member 30 opposite the substrate 20. The contactors 12 are formed, for example, from a synthetic resin material. The contactors 12 have a hardness sufficient to prevent deformation when they come into contact with a protruding defect 231 or the like on the surface 201 of the test object 200. The hardness of the contactors 12 is softer than the hardness of the coating 220 formed on the surface of the vehicle body 210 of the test object 200, and harder than the hardness of the elastic member 30. Therefore, even if the contactors 12 are moved relative to the test object 200 while in contact with the surface 201 of the test object 200, the surface 201 of the test object 200 is unlikely to be scratched by rubbing against the contactors 12. The elastic modulus of the elastic member 30 is smaller than that of the contactors 12. Therefore, when the contactor 12 comes into contact with a protruding defective portion 231 (see Figure 1) formed on the surface 201 of the test object 200, the deformation amount of the elastic member 30 can be made larger than the deformation amount of the contactor 12, and the change in the parasitic capacitance C1 can be made larger.

[0030] Here, there are multiple types of contactors 12, and the multiple types of contactors 12 differ from one another in the shape of the contact portion with the test object 200. It is preferable that the shape of the contact portion between the contactor 12 and the test object 200 be changed appropriately in accordance with the size, shape, etc. of a defective portion occurring on the surface 201 of the test object 200.

[0031] In the surface detection sensor 1 of this embodiment, three types of contactors 12 are provided as the contactors 12. The three types of contactors 12 include at least a first contactor 12A (see FIGS. 1 to 4), a second contactor 12B (see FIGS. 5 and 6), and a third contactor 12C (see FIG. 7).

[0032] The first contactor 12A is formed in a shape suitable for detecting, for example, a protruding defective portion 231 (see FIG. 1) or 233 (see FIG. 3). As shown in FIGS. 1 to 3, the first contactor 12A is a plate-shaped contactor formed in a plate shape extending along the Y-axis direction (second direction DR2). That is, the multiple types of contactors 12 include the first contactor 12A. The first contactor 12A is formed in a plate shape and is arranged so that its thickness direction is along the first direction DR1 and its long side direction is along the second direction DR2. Here, the first contactor 12A is provided from a position overlapping a first end of the electrode 11 in the Y-axis direction in the Z-axis direction to a position overlapping a second end of the electrode 11 in the Y-axis direction in the Z-axis direction. The first contactor 12A is provided near the center of the electrode 11 in the X-axis direction, and the multiple first contactors 12A provided on the surface of the elastic member 30 are provided at approximately the same position in the X-axis direction. In addition, two components being located at approximately the same position is not limited to a state in which the two components are located at exactly the same position, but can also include a state in which the positional deviation between the two components is within a manufacturing error.

[0033] When the first contactor 12A abuts against the protruding defective portion 231 or 233, the first contactor 12A is pressed by the defective portion 231 or 233, compressing the installation portion of the first contactor 12A in the elastic member 30. In the electrode block 10 including the first contactor 12A abutting against the protruding defective portion 231 or 233, the volume of the elastic member 30 present between the electrode 11 and the test object 200 decreases, thereby reducing the parasitic capacitance C1 between the electrode 11 and the test object 200. Therefore, the surface detection sensor 1 including the first contactor 12A can detect the presence of the protruding defective portion 231, 233 based on the change in the parasitic capacitance C1 occurring between the electrode 11 and the test object 200. Since the first contactor 12A is formed in a plate shape extending along the Y-axis direction, the width dimension of the sensor module 2 in the X-axis direction only needs to be equal to or greater than the width dimension required to form the first contactor 12A, as shown in Figure 4, and the shape and size of the sensor module 2 can be changed as appropriate.

[0034] The second contactor 12B is formed in a shape suitable for detecting a defective portion 232 (see FIGS. 5 and 6), such as a slit-shaped scratch. As shown in FIGS. 5 and 6, the second contactor 12B is a needle-like contactor provided at a position that overlaps in the Z-axis direction with the center position of the electrode 11 in the first direction DR1 and the second direction DR2. In other words, the multiple types of contactors 12 include a needle-like second contactor 12B provided corresponding to one electrode 11. The multiple second contactors 12B provided on the multiple electrode blocks 10 are provided at approximately the same position in the first direction DR1 (X-axis direction).

[0035] Because the sensor module 2 of the surface detection sensor 1 is pressed against the test object 200, when the second contactor 12B enters a defective portion 232 such as a slit-shaped scratch, the installation portion of the second contactor 12B in the elastic member 30 stretches. In the electrode block 10 including the second contactor 12B that has entered the defective portion 232 such as a scratch, the volume of the elastic member 30 existing between the electrode 11 and the test object 200 increases and the volume of the gap portion (hollow portion) decreases, thereby increasing the parasitic capacitance C1 between the electrode 11 and the test object 200. Therefore, the surface detection sensor 1 including the second contactor 12B can detect the presence of a defective portion 232 such as a slit-shaped scratch based on the change in the parasitic capacitance C1 occurring between the electrode 11 and the test object 200.

[0036] The third contactors 12C are formed in a shape suitable for detecting, for example, a depression-shaped defective portion 234 (see FIG. 7 ). As shown in FIG. 7 , the third contactors 12C are multiple needle-shaped contactors provided on the surface of the elastic member 30 in an area overlapping with the electrodes 11 in the Z-axis direction. The third contactors 12C include multiple needle-shaped contactors arranged at predetermined intervals in the second direction DR2. In other words, the multiple types of contactors 12 include multiple needle-shaped third contactors 12C provided corresponding to one electrode 11. The size of each needle-shaped contactor is smaller than the size of the depression-shaped defective portion 234 to be detected, and is set to a size that allows multiple needle-shaped contactors to fit into the depression-shaped defective portion 234.

[0037] Because the sensor module 2 of the surface detection sensor 1 is pressed against the object under test 200, when the multiple needle-like contactors of the third contactor 12C move to a position overlapping the recessed defective portion 234, one or more needle-like contactors enter the recessed defective portion 234. At this time, the installation portion of the one or more needle-like contactors that have entered the recessed defective portion 234 in the elastic member 30 expands, increasing the volume of the elastic member 30 present between the electrode 11 and the object under test 200 and reducing the volume of the gap portion (hollow portion). This increases the parasitic capacitance C1 between the electrode 11 and the object under test 200, so the surface detection sensor 1 equipped with the third contactor 12C can detect the presence of the recessed defective portion 234 based on the change in parasitic capacitance C1.

[0038] The plurality of electrode blocks 10 arranged in the second direction DR2 are provided with the same type of contactor 12 selected from, for example, the first to third contactors 12A to 12C according to the size and shape of the defective portion to be detected. In the following, an example will be described in which the plurality of electrode blocks 10 arranged in the second direction DR2 are provided with the first contactor 12A as the contactor 12.

[0039] When inspecting the surface 201 of the object 200 using the surface detection sensor 1, the contactor 12 is moved relative to the object 200 along the first direction DR1 (X-axis direction) while being pressed against the surface 201 of the object 200. Note that since the inspection is performed with the contactor 12 pressed against the surface 201 of the object 200, the elastic member 30 is in a compressed state compared to a state in which the contactor 12 is not in contact with the surface 201 of the object 200. In this embodiment, for example, the position of the surface detection sensor 1 is not changed, and the object 200 is moved, thereby moving the contactor 12 relative to the object 200. Note that the position of the object 200 may be kept unchanged, and the surface detection sensor 1 may be moved, thereby moving the contactor 12 relative to the object 200. Alternatively, the contactor 12 may be moved relative to the object 200 by moving both the object 200 and the surface detection sensor 1.

[0040] The contactor 12 has a hardness such that the contactor 12 does not deform when it comes into contact with a protruding defect 231 or the like formed on the surface 201 of the test object 200. The hardness of the contactor 12 is softer than the hardness of the coating 220 formed on the surface of the vehicle body 210 of the test object 200 and harder than the hardness of the elastic member 30. Therefore, even if the contactor 12 is moved relative to the test object 200 while in contact with the surface 201 of the test object 200, there is little possibility that the surface 201 of the test object 200 will be scratched by rubbing of the contactor 12. Furthermore, when the contactor 12 comes into contact with a protruding defect 231 or the like formed on the surface 201 of the test object 200, the contactor 12 does not deform but the elastic member 30 does.

[0041] When a defective portion such as a protruding defective portion 231 or a recessed defective portion 232 occurs on the surface 201 of the test object 200, when the contactor 12 hits the protruding defective portion 231, the contactor 12 is pushed backward by the protruding defective portion 231. Here, since the elastic member 30 is softer than the contactor 12, when the contactor 12 is pushed backward by the protruding defective portion 231, the elastic member 30 interposed between the contactor 12 that hits the protruding defective portion 231 and the electrode 11 becomes further compressed. When the elastic member 30 is further compressed, the volume of the elastic member 30 present between the test object 200 and the electrode 11 decreases, and the parasitic capacitance C1 generated between the test object 200 and the electrode 11 decreases.

[0042] On the other hand, when the contactor 12 enters a recessed defective portion 232 formed on the surface 201 of the test object 200, the elastic member 30 expands to a position where the contactor 12 abuts on the bottom of the recessed defective portion 232. This increases the volume of the elastic member 30 present between the test object 200 and the electrode 11, and increases the parasitic capacitance C1 generated between the test object 200 and the electrode 11.

[0043] (2.1.2) Circuit Module Next, a description will be given of the circuit configuration of the circuit module 3. FIG.

[0044] The circuit module 3 includes a detection unit 60. The detection unit 60 detects a defective portion on the surface 201 of the test object 200 based on a change in parasitic capacitance C1 generated between the electrode 11 and the test object 200 when the contactor 12 is moved relative to the test object 200 in a first direction DR1 while the contactor 12 is in contact with the surface 201 of the test object 200.

[0045] More specifically, the circuit module 3 includes a switching circuit 51 , an oscillation circuit 52 , a detection circuit 53 , and a signal processing unit 54 having the function of a detection unit 60 .

[0046] The switching circuit 51 selectively connects any one of the plurality of electrodes 11 included in the plurality of electrode blocks 10 to one end of the inductor L1. Specifically, the switching circuit 51 includes a plurality of switches 51A, 51B, 51C... connected between the plurality of electrodes 11A, 11B, 11C... and the inductor L1, respectively. The plurality of switches 51A, 51B, 51C... are controlled to be turned on or off in response to a switching signal input from a switching control unit 541, which will be described later. The switching control unit 541 selectively controls one of the plurality of switches 51A, 51B, 51C... to be turned on, so that any one of the plurality of electrodes 11 is connected to the inductor L1.

[0047] The oscillation circuit 52 includes an inductor L1, one end of which is connected to the electrode 11 via a switching circuit 51. The oscillation circuit 52 also includes an inductor L2, the first end of which is connected to the second end of the inductor L1, and an inverter IC1. The second end of the inductor L2 is connected to the input end of the inverter IC1, and the first end of the inductor L1 is connected to the output end of the inverter IC1. Here, the inductors L1 and L2, the parasitic capacitance C1 between the electrode 11 and the subject 200, and the inverter IC1 form a Hartley oscillator. The oscillation frequency of the oscillation circuit 52 is determined by the parasitic capacitance C1 between the electrode 11, which is connected to the first end of the inductor L1 via the switching circuit 51, and the subject 200, and the inductances of the inductors L1 and L2. The switching circuit 51 sequentially switches the electrode 11 connected to the first end of the inductor L1 every time a predetermined switching time elapses, and the oscillation circuit 52 oscillates at an oscillation frequency corresponding to a parasitic capacitance C1 between the electrode 11 connected to the first end of the inductor L1 and the test object 200. When the contactor 12 comes into contact with a defective portion occurring on the surface 201 of the test object 200, causing a change in the parasitic capacitance C1, the oscillation frequency of the oscillation circuit 52 changes in accordance with the change in the parasitic capacitance C1. Note that, although the oscillation circuit 52 is a Hartley oscillator in this embodiment, the oscillation circuit 52 may also be a Colbitz oscillator, and the circuit configuration of the oscillation circuit 52 can be changed as appropriate.

[0048] The detection circuit 53 performs FM detection on the oscillation signal S10 of the oscillation circuit 52 to generate a demodulated signal S11. The oscillation signal S10 of the oscillation circuit 52 is input to the detection circuit 53. The detection circuit 53 performs FM detection on the oscillation signal S10 and outputs a demodulated signal S11 having a voltage value corresponding to the frequency of the oscillation signal S10, for example. Figure 9 is a graph showing an example of the oscillation signal S10 and the demodulated signal S11. Here, the voltage value of the demodulated signal S11 in a normal state where the contact 12 is in contact with the surface 201 of the test object 200 where no defect exists is set to V1.

[0049] 9 is a period during which the contactor 12 contacts a protruding defect 231 on the surface 201 of the test object 200, and during this period T1, the parasitic capacitance C1 is reduced compared to the normal state. Therefore, the oscillation frequency of the oscillation signal S10 is higher than the oscillation frequency in the normal state, and the voltage value of the demodulation signal S11 is higher than V1. Also, during the period T2 in FIG. 9, the contactor 12 is inserted into a recessed defect 232 on the surface 201 of the test object 200, and during this period T2, the parasitic capacitance C1 is increased compared to the normal state. Therefore, the oscillation frequency of the oscillation signal S10 is lower than the oscillation frequency in the normal state, and the voltage value of the demodulation signal S11 is lower than V1.

[0050] The signal processing unit 54 is mainly composed of, for example, a computer system having one or more processors and a memory. The functions of the signal processing unit 54 are realized by the processor of the computer system executing a program recorded in the memory of the computer system. The program may be recorded in the memory, or may be provided via a telecommunications line such as the Internet, or may be recorded on a non-transitory recording medium such as a memory card and provided.

[0051] The signal processing unit 54 has, for example, the functions of a switching control unit 541 and a detection unit 60. Note that the switching control unit 541 and the detection unit 60 merely indicate the functions realized by the signal processing unit 54, and do not necessarily indicate actual configurations.

[0052] The switching control unit 541 selectively connects one of the multiple electrodes 11 to the first end of the inductor L1 by switching on / off the multiple switches 51A, 51B, 51C, etc. The switching control unit 541 sequentially switches the electrode 11 connected to the first end of the inductor L1 every time a predetermined switching time elapses. The switching time is set to the time required for the oscillation state of the oscillation circuit 52 to stabilize after the parasitic capacitance C1 is connected to the first end of the inductor L1. Here, if the number of electrodes 11 is n and the switching time is TA, the time required to detect the presence or absence of a defective portion based on the parasitic capacitance C1 between the n electrodes 11 and the test object 200 is (n × TA). Since a fast speed at which the contactor 12 is moved relative to the test object 200 is likely to result in missed detections, it is preferable to move the contactor 12 as slowly as possible.

[0053] The detection unit 60 detects a change in the parasitic capacitance C1 based on the demodulation signal S11 and detects a defective portion on the surface 201 of the object to be inspected 200 from the change in the parasitic capacitance C1. The detection unit 60 detects a defective portion on the surface 201 of the object to be inspected 200 by comparing the value of the demodulation signal S11 input from the detection circuit 53 with the value V1 of the demodulation signal S11 in a normal state. The detection unit 60 detects the presence of a defective portion when, for example, the absolute value of the difference (V2-V1) between the value V2 of the demodulation signal S11 input from the detection circuit 53 and the value V1 of the demodulation signal S11 in a normal state exceeds a predetermined threshold. The detection unit 60 may also determine that a protruding defective portion exists on the surface 201 of the object to be inspected 200 when the difference (V2-V1) between the value V2 and the value V1 of the demodulation signal S11 input from the detection circuit 53 exceeds a positive threshold. In addition, the detection unit 60 may determine that a recess-shaped defective portion exists on the surface 201 of the subject 200 when the difference (V2-V1) between the value V2 and the value V1 of the demodulation signal S11 input from the detection circuit 53 falls below a negative threshold.

[0054] In this embodiment, the circuit module 3 only needs to have one oscillator circuit 52, which allows the circuit scale to be reduced.

[0055] (2.2) Sensor System Next, a sensor system 100 including the surface detection sensor 1 will be described with reference to FIG.

[0056] The sensor system 100 includes the surface detection sensor 1 and a pressing mechanism 70 (see FIG. 6).

[0057] The base material 20 is attached to the pressing mechanism 70 via an elastic buffer member 71. The pressing mechanism 70 presses the contacts 12 of the electrode blocks 10 against the surface 201 of the subject 200.

[0058] The sensor system 100 may further include, for example, a driving mechanism 600 that moves the multiple contacts 12 along the first direction DR1 while the pressing mechanism 70 presses the multiple contacts 12 against the surface 201 of the subject 200.

[0059] The driving mechanism 600 includes, for example, a robot arm 61 to which the surface detection sensor 1 is attached via a pressing mechanism 70, and a driving circuit 62 that drives the robot arm 61. The driving circuit 62 drives the robot arm 61 to move the plurality of contacts 12 along a first direction DR1 while pressing the plurality of contacts 12 against the surface 201 of the subject 200.

[0060] The surface detection sensor 1 is attached to the robot arm 61 of the drive mechanism 600 via a pressing mechanism 70 including a buffer member 71 .

[0061] The pressing mechanism 70 comprises a plate-shaped buffer member 71 to which the substrate 20 of the surface detection sensor 1 is attached, a metal support member 72 to which the buffer member 71 is attached, and a plate spring portion 73 that connects between a rod-shaped member 611 provided at the tip of the robot arm 61 and the support member 72.

[0062] The buffer member 71 is formed in a plate shape from an elastic synthetic resin. A back electrode 13 provided on a second surface of the substrate 20 is connected to a first surface of the buffer member 71 in the Z-axis direction. The buffer member 71 is sponge-like and is more easily deformed than the substrate 20. Therefore, when the surface of the subject 200 is formed into a curved surface, the buffer member 71 deforms, allowing the multiple contacts 12 of the surface detection sensor 1 to contact the surface 201 of the subject 200.

[0063] The support member 72 is formed in a plate shape from, for example, a metal material. A first surface of the support member 72 in the Z-axis direction is connected to a second surface of the buffer member 71. A leaf spring portion 73 is attached to the second surface of the support member 72, and the support member 72 is attached to the rod-shaped member 611 of the robot arm 61 via the leaf spring portion 73.

[0064] (2.3) Description of Operation When inspecting the surface 201 of the specimen 200 using the surface detection sensor 1, the drive circuit 62 controls the robot arm 61 to bring the multiple contactors 12 of the surface detection sensor 1, which are attached to the rod-shaped member 611 via the pressing mechanism 70, into contact with the surface 201 of the specimen 200. At this time, the spring force of the leaf spring portion 73 presses the multiple contactors 12 of the surface detection sensor 1 against the surface 201 of the specimen 200. Then, when the drive circuit 62 drives the robot arm 61 to move the multiple contactors 12 of the surface detection sensor 1 along the first direction DR1, the multiple contactors 12 move while rubbing against the surface 201 of the specimen 200.

[0065] When one or more of the contactors 12 of the surface detection sensor 1 come into contact with a defective portion present on the surface 201 while the contactors 12 of the surface detection sensor 1 are moving while rubbing against the surface 201 of the subject 200, a parasitic capacitance C1 changes between the subject 200 and one or more electrodes 11 corresponding to the one or more contactors 12 that have come into contact with the defective portion. At this time, the detection unit 60 of the surface detection sensor 1 can detect the presence of a defective portion on the surface 201 of the subject 200 based on the change in parasitic capacitance C1. Furthermore, the detection unit 60 can detect the position of the defective portion on the surface 201 of the subject 200 based on the position of the electrode block 10 where the parasitic capacitance C1 has changed and the position of the rod-shaped member 611 attached to the robot arm 61.

[0066] In addition, when moving the subject 200 relative to the multiple contactors 12 of the surface detection sensor 1, the driving mechanism 600 is not required; the subject 200 can simply be moved relative to the multiple contactors 12 while the multiple contactors 12 are pressed against the surface 201 of the subject 200.

[0067] (3) Modifications The above embodiment is merely one of various embodiments of the present disclosure. The above embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved.

[0068] Modifications of the above embodiment are listed below. The modifications described below can be applied in appropriate combinations. Note that the above embodiment may also be referred to as a basic example below.

[0069] (3.1) Modification 1 The surface detection sensor 1 of Modification 1 will be described with reference to Figures 11 and 12. The surface detection sensor 1 of Modification 1 differs from the basic example in the circuit configuration of the circuit module 3. Note that, since the surface detection sensor 1 of Modification 1 is the same as the basic example except for the circuit configuration of the circuit module 3, the same components as those of the basic example will be denoted by the same reference numerals and descriptions thereof will be omitted as appropriate.

[0070] In the surface detection sensor 1 of the first modified example, the circuit module 3 includes a plurality of oscillator circuits 52A, 52B, 52C, and the like, and a signal processing unit 54 having the function of a Fourier transform unit 542. The circuit module 3 also includes a plurality of resistors R1, R2, R3, and the like.

[0071] The multiple oscillator circuits 52A, 52B, 52C... correspond one-to-one to the multiple electrode blocks 10. Each of the multiple oscillator circuits 52A, 52B, 52C... includes inductors L12, L22, L32..., one end (first end) of which is connected to an electrode 11 of a corresponding one of the multiple electrode blocks 10. The inductors L12, L22, L32... included in the multiple oscillator circuits 52A, 52B, 52C... have different inductances. Each of the multiple oscillator circuits 52A, 52B, 52C... further includes inverters IC11, IC12, IC13... and inductors L11, L21, L31....

[0072] Each of the multiple oscillator circuits 52A, 52B, 52C... has, for example, a circuit configuration of a Hartley oscillator. Because the multiple oscillator circuits 52A, 52B, 52C... have similar circuit configurations, the circuit configuration of the oscillator circuit 52A will be described as an example, and descriptions of the other oscillator circuits 52B, 52C... will be omitted. The oscillator circuit 52A includes an inductor L12 having a first end connected to the electrode 11A, an inverter IC11 having the first end of the inductor L12 connected to its input end, and an inductor L11 connected between the output end of the inverter IC11 and the second end of the inductor L12. A parasitic capacitance C1 between the electrode 11A and the subject 200, the inductors L11 and L12, and the inverter IC11 form a Hartley oscillator. The output end of the oscillator circuit 52A (specifically, the output end of the inverter IC11) is connected to a junction P1 via a high-resistance resistor R1.

[0073] Here, the oscillation frequency of the oscillator circuit 52A is determined by the parasitic capacitance C1 between the electrode 11A and the subject 200 and the inductances of the inductors L11 and L12. When no defective portions occur on the surface 201 of the subject 200 with which the multiple contacts 12 of the multiple electrode blocks 10 are in contact, the parasitic capacitances C1 between the electrodes 11A, 11B, 11C... of the multiple electrode blocks 10 and the surface 201 of the subject 200 will have approximately the same value. On the other hand, the inductances of the multiple inductors L12, L22, L32... included in the multiple oscillator circuits 52A, 52B, 52C... are different from one another, and therefore the oscillation frequencies of the multiple oscillator circuits 52A, 52B, 52C... will be different from one another.

[0074] The output terminals of the plurality of oscillator circuits 52A, 52B, 52C, etc. are connected to the junction P1 via high-resistance resistors R1, R2, R3, etc. The junction P1 is also connected to the signal processing unit 54. Therefore, a composite signal SA1 obtained by combining (adding) the output signals S1, S2, S3, etc. of the plurality of oscillator circuits 52A, 52B, 52C, etc. is input to the signal processing unit 54.

[0075] As in the basic example, the signal processing unit 54 mainly comprises a computer system having one or more processors and memories. The signal processing unit 54 has the functions of a Fourier transform unit 542 and a detection unit 60. Note that the Fourier transform unit 542 and the detection unit 60 merely represent functions realized by the signal processing unit 54, and do not necessarily represent actual configurations.

[0076] The Fourier transform unit 542 performs a Fourier transform on a composite signal SA1 obtained by combining the output signals S1, S2, S3, etc. of the multiple oscillation circuits 52A, 52B, 52C, etc. The Fourier transform unit 542 outputs the result of the Fourier transform of the composite signal SA1 to the detection unit 60. FIG. 12 is a graph showing the result of the transform performed by the Fourier transform unit 542. The Fourier transform performed by the Fourier transform unit 542 results in a frequency spectrum having three peaks corresponding to the oscillation frequencies of the oscillation circuits 52A, 52B, and 52C, respectively. In the frequency spectrum shown in FIG. 12, the frequencies f11, f12, and f13 corresponding to the three peaks correspond to the oscillation frequencies of the oscillation circuits 52A, 52B, and 52C, respectively. The frequencies of the peaks appearing in the frequency spectrum are referred to as peak frequencies.

[0077] The detection unit 60 detects a defective portion on the surface of the test object 200 based on a change in the peak frequency of the transformation result by the Fourier transform unit 542. Here, when one or more of the contactors 12 included in the surface detection sensor 1 come into contact with a defective portion (a protrusion-shaped or recess-shaped defective portion) on the surface of the test object 200, a parasitic capacitance C1 between the test object 200 and the electrode 11 of the electrode block 10 including the contactor 12 in contact with the defective portion changes. When the parasitic capacitance C1 changes, the oscillation frequency of the oscillation circuit including this parasitic capacitance C1 changes. For example, when the contactor 12 corresponding to the electrode 11A comes into contact with the defective portion, the parasitic capacitance C1 between the electrode 11A and the test object 200 changes, and the peak frequency (peak frequency) corresponding to the oscillation frequency of the oscillation circuit 52A changes from f11.

[0078] When the peak frequencies of the multiple peaks corresponding to the oscillation frequencies of the oscillator circuits 52A, 52B, 52C, etc. vary by a predetermined value or more from the peak frequency in a normal state, the detector 60 determines that the contactor 12 of the electrode block 10 corresponding to the oscillator circuit whose peak frequency has varied by the predetermined value or more is in contact with a defective portion. This allows the detector 60 to detect the presence or absence of a defective portion on the surface 201 of the subject 200, and, if a defective portion exists, the position of the defective portion. Furthermore, in the first modification, the detector 60 can simultaneously detect whether or not multiple contactors 12 are in contact with a defective portion.

[0079] (3.2) Modification 2 The surface detection sensor 1 of Modification 2 will be described with reference to Figures 13 and 14. The surface detection sensor 1 of Modification 2 differs from the basic example in the circuit configuration of the circuit module 3. Note that, since the surface detection sensor 1 of Modification 2 is the same as the basic example except for the circuit configuration of the circuit module 3, the same components as those of the basic example will be denoted by the same reference numerals and descriptions thereof will be omitted as appropriate.

[0080] In the surface detection sensor 1 of the second modification, the circuit module 3 includes a plurality of oscillation circuits 52A, 52B, 52C . . . and an impedance measuring unit 55.

[0081] The multiple oscillator circuits 52A, 52B, 52C... correspond one-to-one to the multiple electrode blocks 10. Each of the multiple oscillator circuits 52A, 52B, 52C... has inductors L41, L42, L43... whose first ends are connected to the electrodes 11 of the corresponding electrode blocks 10. Second ends of the multiple inductors L41, L42, L43... of the multiple oscillator circuits 52A, 52B, 52C... are connected to a common connection point P2. The inductors L41, L42, L43... of the multiple oscillator circuits 52A, 52B, 52C... and the parasitic capacitances generated between the electrodes 11A, 11B, 11C... and the subject 200 respectively form LC series resonant circuits. Here, the inductances of the multiple inductors L41, L42, L43... are different from one another.

[0082] Since the multiple oscillator circuits 52A, 52B, 52C... have similar circuit configurations, the circuit configuration will be described using the oscillator circuit 52A as an example, and descriptions of the other oscillator circuits 52B, 52C... will be omitted. The oscillator circuit 52A is configured as an LC series resonant circuit including a parasitic capacitance C1 generated between the electrode 11A and the subject 200, and an inductor L41 having a first end connected to the electrode 11A and a second end connected to a common connection point P2. The resonant frequency of this LC series resonant circuit is determined by the parasitic capacitance C1 generated between the electrode 11A and the subject 200 and the inductance of the inductor L41. Note that the inductances of the multiple inductors L41, L42, L43... included in the multiple oscillator circuits 52A, 52B, 52C... are different from one another, and therefore the oscillation frequencies of the multiple oscillator circuits 52A, 52B, 52C... are different from one another.

[0083] The second ends of the plurality of inductors L41, L42, L43 . . . are connected to a common connection point P2, which is connected to the input terminal of the impedance measuring section 55.

[0084] The impedance measuring unit 55 measures the impedance of the circuit connected to the common connection point P2. Here, the circuit connected to the common connection point P2 is a parallel circuit in which a plurality of oscillator circuits 52A, 52B, 52C... are connected in parallel. Therefore, the impedance measuring unit 55 measures the impedance of the parallel circuit in which a plurality of oscillator circuits 52A, 52B, 52C... are connected in parallel.

[0085] Fig. 14 shows the results of measurement, by the impedance measuring unit 55, of the impedance Z of the circuit connected to the common connection point P2. The frequency characteristics of the impedance Z shown in Fig. 14 show three peaks where the impedance value suddenly decreases at the oscillation frequencies f11, f12, and f13 of the oscillator circuits 52A, 52B, and 52C. The frequencies of the multiple peaks (hereinafter referred to as peak frequencies) that appear in the frequency characteristics of the impedance Z respectively match the oscillation frequencies f11, f12, f13, and so on of the multiple oscillator circuits 52A, 52B, 52C, and so on.

[0086] As in the basic example, the signal processing unit 54 mainly comprises a computer system having one or more processors and memories. The signal processing unit 54 has the functions of the detection unit 60. Note that the detection unit 60 merely represents the functions realized by the signal processing unit 54, and does not necessarily represent a substantial configuration.

[0087] The detection unit 60 detects a defective portion on the surface 201 of the test object 200 based on a change in the peak frequency of the impedance Z. Here, when one or more of the contactors 12 included in the surface detection sensor 1 come into contact with a defective portion (a protrusion-shaped or recess-shaped defective portion) on the surface of the test object 200, a parasitic capacitance C1 between the test object 200 and the electrode 11 of the electrode block 10 including the contactor 12 that has come into contact with the defective portion changes. When the parasitic capacitance C1 changes, the oscillation frequency of the oscillation circuit including this parasitic capacitance C1 changes. For example, when the contactor 12 corresponding to the electrode 11A comes into contact with the defective portion, the parasitic capacitance C1 between the electrode 11A and the test object 200 changes, and the oscillation frequency f11 of the oscillation circuit 52A changes. As a result, the peak frequency corresponding to the oscillation frequency f11 of the oscillation circuit 52A changes in the frequency characteristics of the impedance Z.

[0088] When the peak frequencies of the multiple peaks corresponding to the oscillation frequencies of the oscillator circuits 52A, 52B, 52C, etc. vary by a predetermined value or more from the peak frequency in the normal state, the detector 60 determines that the contactor 12 of the electrode block 10 corresponding to the oscillator circuit whose peak frequency has varied by the predetermined value or more is in contact with a defective portion. This allows the detector 60 to detect the presence or absence of a defective portion on the surface 201 of the test object 200, and, if a defective portion exists, the position of the defective portion. Furthermore, in the second modification, the detector 60 can simultaneously detect whether or not multiple contactors 12 are in contact with a defective portion.

[0089] (3.3) Modification 3 A surface detection sensor 1 according to Modification 3 will be described with reference to Fig. 15 and Fig. 16. Note that the same components as those in the basic example will be denoted by the same reference numerals and the description thereof will be omitted as appropriate.

[0090] In the surface detection sensor 1 of the third modification, as shown in FIGS. 15 and 16 , multiple electrode groups G1 and G2 are arranged along a first direction DR1 (the X-axis direction in FIG. 15 ). Each of the multiple electrode groups G1 and G2 includes multiple electrode blocks 10 arranged side by side along a second direction DR2. One of the multiple electrode groups G1 and G2 (e.g., electrode group G1) is referred to as a first electrode group, and one or more electrode groups other than the first electrode group (e.g., electrode group G2) among the multiple electrode groups G1 and G2 are referred to as one or more second electrode groups. In this case, the multiple contacts 12 included in the multiple electrode blocks 10 included in the first electrode group (e.g., electrode group G1) are of the same type. Furthermore, the multiple contacts 12 included in the multiple electrode blocks 10 included in the first electrode group (e.g., electrode group G1) are of different types from the multiple contacts 12 included in the multiple electrode blocks 10 included in one or more second electrode groups (e.g., electrode group G2).

[0091] In each of the electrode groups G1, G2, the electrode blocks 10 arranged side by side along the second direction DR2 have the same type of contactors 12, making it possible to detect the presence or absence of defective portions of the same type. In the examples of Figures 15 and 16, the electrode blocks 10 included in the first electrode group (e.g., electrode group G1) have, for example, first contactors 12A, and the electrode blocks 10 included in the second electrode group (e.g., electrode group G2) have, for example, third contactors 12C.

[0092] Here, the first contactor 12A is formed in a shape suitable for detecting a protrusion-shaped defective portion 231 (see FIG. 1) or 233 (see FIG. 3), and the third contactor 12C is formed in a shape suitable for detecting a depression-shaped defective portion 232 (see FIG. 14). Therefore, by providing the surface detection sensor 1 with an electrode group G1 (first electrode group) including a plurality of electrode blocks 10 each having the first contactor 12A and an electrode group G2 (second electrode group) including a plurality of electrode blocks 10 each having the third contactor 12C, it is possible to realize a surface detection sensor 1 that can detect a plurality of types of defective portions.

[0093] The surface detection sensor 1 may include three or more electrode groups having different types of contacts 12, thereby realizing a surface detection sensor 1 that can detect three or more types of defective portions.

[0094] (Summary) The above-described embodiments and the like disclose the following aspects.

[0095] A surface detection sensor (1) of a first aspect includes a plurality of electrode blocks (10), a substrate (20) supporting the plurality of electrode blocks (10), and an elastic member (30). Each of the plurality of electrode blocks (10) has an electrode (11, 11A-11C) disposed on the substrate (20) and a contactor (12) capable of contacting the surface of a test object (200). At least a portion of the elastic member (30) is interposed between the electrode (11, 11A-11C) of each of the plurality of electrode blocks (10) and the contactor (12). The plurality of electrode blocks (10) are arranged side by side along a second direction (DR2). The second direction (DR2) intersects with a first direction (DR1) that moves the contactor (12) relative to the test object (200).

[0096] According to this aspect, the presence or absence of a defect on the surface (201) of the test object (200) and the position of the defect can be detected based on a change (increase or decrease) in the parasitic capacitance generated between the test object (200) and the electrode (11). In addition, by moving a plurality of electrode blocks (10) arranged along the second direction (DR2) along the first direction (DR1), the defect on the surface (201) of the test object (200) can be detected, thereby shortening the time required for inspection.

[0097] The surface detection sensor (1) of the second aspect is the same as the first aspect and includes a detection unit (60). The detection unit (60) detects a defective portion on the surface of the test object (200) based on a change in parasitic capacitance (C1) generated between the electrodes (11, 11A to 11C) and the test object (200) when the contactor (12) is moved relative to the test object (200) along a first direction (DR1) with the contactor (12) in contact with the surface of the test object (200).

[0098] According to this aspect, by moving a plurality of electrode blocks (10) arranged along the second direction (DR2) along the first direction (DR1), defective areas on the surface (201) of the specimen (200) can be detected, thereby shortening the time required for inspection.

[0099] In the surface detection sensor (1) of the third aspect, in the first or second aspect, the elastic member (30) is provided over the entire plurality of electrodes (11, 11A to 11C) of the plurality of electrode blocks (10).

[0100] According to this aspect, when any of the plurality of contacts (12) comes into contact with a defective portion, the elastic member (30) can be easily deformed.

[0101] The surface detection sensor (1) of the fourth aspect is any one of the first to third aspects, and further includes a back electrode (13) that faces the plurality of electrodes (11, 11A to 11C) of the plurality of electrode blocks (10) via the substrate (20).

[0102] According to this aspect, it is possible to reduce the possibility that a parasitic capacitance will occur between the object on the opposite side of the subject (200) due to the back electrode (13).

[0103] In the surface detection sensor (1) of the fifth aspect, in any one of the first to fourth aspects, there are a plurality of types of contacts (12). The plurality of types of contacts (12) have different shapes of the contact portions that come into contact with the specimen (200).

[0104] According to this aspect, defective portions of a plurality of different shapes can be detected.

[0105] In the surface detection sensor (1) of the sixth aspect, a plurality of electrode groups (G1, G2) including a plurality of electrode blocks (10) arranged side by side along the second direction (DR2) are arranged along the first direction (DR1) in the fifth aspect. One of the plurality of electrode groups (G1, G2) is referred to as a first electrode group, and one or more electrode groups (G1, G2) other than the first electrode group are referred to as one or more second electrode groups. The plurality of contacts (12) included in the plurality of electrode blocks (10) included in the first electrode group are of the same type. The plurality of contacts (12) included in the plurality of electrode blocks (10) included in the first electrode group and the plurality of contacts (12) included in the plurality of electrode blocks (10) included in the one or more second electrode groups are of different types.

[0106] According to this aspect, defective portions of a plurality of different shapes can be detected.

[0107] In a seventh aspect of the surface detection sensor (1) of the fifth or sixth aspect, the plurality of types of contactors (12) include a first contactor (12A). The first contactor (12A) is formed in a plate shape and is arranged so that its thickness direction is aligned with the first direction (DR1) and its long side direction is aligned with the second direction (DR2).

[0108] This embodiment has the advantage that protruding defective portions can be easily detected.

[0109] In the surface detection sensor (1) of the eighth aspect, in any of the fifth to seventh aspects, the multiple types of contactors (12) include a needle-shaped second contactor (12B) provided in correspondence with one electrode (11, 11A to 11C).

[0110] This embodiment has the advantage that protruding defective portions can be easily detected.

[0111] In the surface detection sensor (1) of the ninth aspect, in any of the fifth to eighth aspects, the multiple types of contactors (12) include needle-shaped third contactors (12C) provided in multiple numbers corresponding to one electrode (11, 11A to 11C).

[0112] This embodiment has the advantage that it is easy to detect a defective portion in the form of a depression.

[0113] In the surface detection sensor (1) of the tenth aspect, in any one of the first to ninth aspects, the elastic modulus of the elastic member (30) is smaller than the elastic modulus of the contact (12).

[0114] According to this aspect, the amount of deformation of the elastic member (30) can be made larger than the amount of deformation of the contact (12).

[0115] The surface detection sensor (1) of the eleventh aspect is the second aspect and includes a switching circuit (51), an oscillation circuit (52), and a detection circuit (53). The switching circuit (51) selectively connects one of a plurality of electrodes (11, 11A-11C) of a plurality of electrode blocks (10) to one end of an inductor (L1). The oscillation circuit (52) has an inductor (L1) whose one end is connected to the electrode (11, 11A-11C) via the switching circuit (51). The detection circuit (53) performs FM detection on an oscillation signal (S10) of the oscillation circuit (52) to generate a demodulated signal (S11). The detection unit (60) detects a change in parasitic capacitance (C1) based on the demodulated signal (S11) and detects a defective portion on the surface of the specimen (200) from the change in parasitic capacitance (C1).

[0116] According to this embodiment, only one oscillator circuit (52) is required, thereby reducing the circuit size.

[0117] A surface detection sensor (1) according to a twelfth aspect of the present invention is the second aspect, and includes a plurality of oscillator circuits (52) and a Fourier transform unit (542). The plurality of oscillator circuits (52) correspond one-to-one to the plurality of electrode blocks (10). The Fourier transform unit (542) performs a Fourier transform on a composite signal (SA1) obtained by combining output signals (S1 to S3) from the plurality of oscillator circuits (52). Each of the plurality of oscillator circuits (52) includes an inductor (L12, L22, L32) having one end connected to an electrode (11, 11A to 11C) of a corresponding electrode block (10) among the plurality of electrode blocks (10). The inductances of the plurality of inductors (L12, L22, L32) included in the plurality of oscillator circuits (52) are different from one another. The detection unit (60) detects a defect on the surface of the subject (200) based on a change in peak frequency of the conversion result obtained by the Fourier transform unit (542).

[0118] According to this aspect, it is possible to detect at once whether or not a plurality of contacts (12) are in contact with a defective portion, thereby reducing the time required to detect the defective portion.

[0119] A surface detection sensor (1) according to a thirteenth aspect of the present invention is the second aspect, and includes a plurality of oscillator circuits (52) and an impedance measurement unit (55). The plurality of oscillator circuits (52) correspond one-to-one to the plurality of electrode blocks (10). Each of the plurality of oscillator circuits (52) has an inductor (L41-L43) whose first end is connected to an electrode (11, 11A-11C) of a corresponding one of the plurality of electrode blocks (10). Second ends of the plurality of inductors (L41-L43) of the plurality of oscillator circuits (52) are connected to a common connection point (P2). The inductances of the plurality of inductors (L41-L43) are different from one another. The impedance measurement unit (55) measures the impedance of the circuit connected to the common connection point (P2). The detection unit (60) detects a defect on the surface of the subject (200) based on a change in the peak frequency of the impedance.

[0120] According to this aspect, it is possible to detect at once whether or not a plurality of contacts (12) are in contact with a defective portion, thereby reducing the time required to detect the defective portion.

[0121] A sensor system (100) of a fourteenth aspect includes the surface detection sensor (1) of any one of the first to thirteenth aspects and a pressing mechanism (70). The pressing mechanism (70) has a substrate (20) attached via an elastic buffer member (71), and presses a plurality of contacts (12) of a plurality of electrode blocks (10) against the surface of the subject (200).

[0122] According to this aspect, the presence or absence of a defect on the surface (201) of the test object (200) and the position of the defect can be detected based on a change (increase or decrease) in the parasitic capacitance occurring between the test object (200) and the electrode (11).

[0123] The configurations according to the second to thirteenth aspects are not essential for the surface detection sensor (1) and can be omitted as appropriate.

[0124] 1 Surface detection sensor 10 Electrode block 11, 11A to 11C Electrode 12 Contactor 12A First contactor 12B Second contactor 12C Third contactor 13 Back surface electrode 20 Substrate 30 Elastic member 51 Switching circuit 52 Oscillator circuit 53 Detector circuit 55 Impedance measurement unit 60 Detector 70 Pressing mechanism 71 Buffer member 100 Sensor system 200 Subject 542 Fourier transform unit C1 Parasitic capacitance DR1 First direction DR2 Second direction G1, G2 Electrode group L1, L12, L22, L32, L41 to L43 Inductor P2 Common connection point S1 to S3 Output signal S10 Oscillator signal S11 Demodulated signal SA1 Composite signal

Claims

1. A surface detection sensor comprising: a plurality of electrode blocks; a base material that supports the plurality of electrode blocks; and an elastic member, wherein each of the plurality of electrode blocks has an electrode disposed on the base material and a contact that can contact the surface of a subject, at least a part of the elastic member is interposed between the electrode and the contact of each of the plurality of electrode blocks, and the plurality of electrode blocks are arranged side by side along a second direction intersecting a first direction in which the contact is relatively moved with respect to the subject.

2. The surface detection sensor according to claim 1, further comprising a detection unit that detects a defective portion on the surface of the subject based on a change in parasitic capacitance generated between the electrode and the subject when the contact is relatively moved along the first direction with respect to the subject in a state where the contact is in contact with the surface of the subject.

3. The surface detection sensor according to claim 1, wherein the elastic member is provided over the entire plurality of electrodes of the plurality of electrode blocks.

4. The surface detection sensor according to claim 1, further comprising a back electrode facing the plurality of electrodes of the plurality of electrode blocks through the base material.

5. The surface detection sensor according to claim 1, wherein there are a plurality of types of the contacts, and the plurality of types of contacts have different shapes of contact portions with the subject.

6. When a plurality of electrode groups each including the plurality of electrode blocks arranged side by side along the second direction are arranged in a plurality along the first direction, and one of the plurality of electrode groups is a first electrode group and one or more of the electrode groups other than the first electrode group among the plurality of electrode groups are one or more second electrode groups, the plurality of contacts of the plurality of electrode blocks included in the first electrode group are of the same type, and the plurality of contacts of the plurality of electrode blocks included in the first electrode group and the plurality of contacts of the plurality of electrode blocks included in the one or more second electrode groups are of different types from each other. The surface detection sensor according to claim 5.

7. The surface detection sensor according to claim 5, wherein the plurality of types of contacts include a first contact formed in a plate shape and arranged such that the thickness direction is along the first direction and the long side direction is along the second direction.

8. The surface detection sensor according to claim 5, wherein the plurality of types of the contacts include needle-shaped second contacts provided one by one corresponding to one of the electrodes.

9. The surface detection sensor according to claim 5, wherein the plurality of types of the contacts include needle-shaped third contacts provided in plurality corresponding to one of the electrodes.

10. The surface detection sensor according to claim 1, wherein the elastic modulus of the elastic member is smaller than the elastic modulus of the contact.

11. A switching circuit that selectively connects any one of the plurality of electrodes included in the plurality of electrode blocks to one end of an inductor; an oscillation circuit having the inductor whose one end is connected to the electrode via the switching circuit; and a detection circuit that FM-detects an oscillation signal of the oscillation circuit to generate a demodulated signal. The detection unit detects a change in the parasitic capacitance based on the demodulated signal, and detects a defective portion on the surface of the object to be inspected from the change in the parasitic capacitance. The surface detection sensor according to claim 2.

12. A plurality of oscillation circuits corresponding one-to-one to the plurality of electrode blocks; and a Fourier transform unit that Fourier-transforms a combined signal obtained by combining output signals of the plurality of oscillation circuits. Each of the plurality of oscillation circuits includes an inductor whose one end is connected to the electrode included in the corresponding electrode block among the plurality of electrode blocks. Inductances of the plurality of inductors included in the plurality of oscillation circuits are different from each other. The detection unit detects a defective portion on the surface of the object to be inspected based on a change in a peak frequency of a conversion result by the Fourier transform unit. The surface detection sensor according to claim 2.

13. A plurality of oscillation circuits corresponding one-to-one to the plurality of electrode blocks; and an impedance measurement unit. Each of the plurality of oscillation circuits has an inductor whose first end is connected to the electrode included in the corresponding electrode block among the plurality of electrode blocks. Second ends of the plurality of inductors included in the plurality of oscillation circuits are connected to a common connection point. Inductances of the plurality of inductors are different from each other. The impedance measurement unit measures an impedance of a circuit connected to the common connection point. The detection unit detects a defective portion on the surface of the object to be inspected based on a change in a peak frequency of the impedance. The surface detection sensor according to claim 2.

14. A surface detection sensor according to any one of claims 1 to 13, and a pressing mechanism in which the base material is attached via a buffer member having elasticity, and a plurality of the contacts included in the plurality of electrode blocks are pressed against the surface of the object to be inspected, the sensor system comprising the pressing mechanism.

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