Inspection apparatus and inspection method

Abstract

Provided are an inspection device and an inspection method that can highly accurately inspect an insulation state between circuit patterns even when a cable has a parasitic capacitance. The inspection device includes a cable that connects a printed board that is an inspection target and the inspection device, a canceling unit that cancels the parasitic capacitance of the cable, and a determination unit that determines whether or not an insulation state between circuit patterns is good or whether or not an electric spark occurs between the circuit patterns, based on a voltage value between the circuit patterns or a current value flowing between the circuit patterns, which are obtained by applying an inspection voltage between the circuit patterns of the printed board via the cable.

Description

Technical Field

[0001] This invention relates to an inspection apparatus and an inspection method. Background Technology

[0002] In the past, in printed circuit boards with multiple wiring patterns, an insulation inspection device was used to determine the insulation status (whether sufficient insulation was guaranteed) of each wiring pattern with other wiring patterns, thereby performing an insulation inspection to check whether the printed circuit board was a good product (for example, Patent Document 1).

[0003] In Patent Document 1, the insulation state between circuit patterns is checked by applying a voltage between them on a printed circuit board. That is, the insulation state between two circuit patterns is checked by applying a voltage to one circuit pattern and checking the current flowing through another. In this insulation inspection device, the circuit patterns on the printed circuit board are connected, for example, via an inspection probe located at the end of a cable. The insulation inspection device applies an inspection voltage to the circuit patterns via the cable and the inspection probe. The insulation inspection device checks whether the insulation is good based on an insulation resistance value calculated according to the voltage value between the circuit patterns and the current flowing through the cable.

[0004] In addition, the insulation inspection device performs spark detection simultaneously with the insulation inspection. A spark is a phenomenon where insulation breakdown occurs due to a potential difference generated between circuit patterns, resulting in a momentary flow of current between the circuit patterns. During the insulation inspection process, the insulation inspection device measures the voltage between the circuit patterns or the current flowing through them within a specified spark detection time. The insulation inspection device determines that a spark has occurred if the voltage between the circuit patterns drops by a specified value or more, i.e., a voltage drop. Alternatively, the insulation inspection device determines that a spark has occurred if the current flowing through the circuit patterns increases by a specified threshold or more, i.e., a spark current.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 5727976 Summary of the Invention

[0008] However, due to the parasitic capacitance of the cable, it is sometimes impossible to accurately measure the current flowing through the circuit pattern or the voltage applied to the circuit pattern. Therefore, it is difficult to check the insulation condition with high precision.

[0009] This invention provides an inspection device and method that can accurately inspect the insulation status between circuit patterns or whether electrical sparks occur between circuit patterns, even when parasitic capacitance exists in the cable.

[0010] To address the aforementioned issues, one aspect of the present invention is an inspection apparatus comprising: a cable connecting a printed circuit board to be inspected and an inspection apparatus; an elimination unit for eliminating parasitic capacitance of the cable; and a determination unit for determining the insulation condition between the circuit patterns or whether electrical sparks occur between the circuit patterns based on voltage values ​​between the circuit patterns obtained by applying an inspection voltage to the circuit patterns of the printed circuit board via the cable, or current values ​​flowing between the circuit patterns.

[0011] Furthermore, one aspect of the present invention is an inspection method, which is an inspection device equipped with an elimination part for eliminating parasitic capacitance of a cable. The cable is connected to a printed circuit board to be inspected and the inspection device. In this method, a determination unit determines the insulation condition between the circuit patterns or whether electrical sparks occur between the circuit patterns based on the voltage value between the circuit patterns obtained by applying an inspection voltage to the circuit patterns of the printed circuit board via the cable, or the current value flowing between the circuit patterns.

[0012] According to the present invention, it is possible to check the insulation status between circuit patterns or whether electrical sparks occur between circuit patterns with high precision. Attached Figure Description

[0013] Figure 1A , Figure 1B This is a block diagram showing a structural example of the insulation inspection system 1 according to the first embodiment.

[0014] Figure 2A , Figure 2B , Figure 2C This is a block diagram illustrating a structural example of the insulation inspection system 1A according to the second embodiment.

[0015] Figure 3A , Figure 3B This is a block diagram illustrating a structural example of the insulation inspection system 2 according to the third embodiment.

[0016] Figure 4A , Figure 4B , Figure 4C This is a block diagram illustrating a structural example of the insulation inspection system 2A according to the fourth embodiment.

[0017] Figure 5 This is a block diagram illustrating a structural example of an existing insulation inspection system 500.

[0018] Figure 6This is a block diagram illustrating a structural example of an existing insulation inspection system 600.

[0019] Label Explanation

[0020] 1…Insulation inspection system, 10…Inspection device, 100, 100-1…Connector, 110…Cable, 111…Center conductor, 112…Shielding conductor, 120…Cable, 121…Center conductor, 122…Shielding conductor, 130…Virtual grounding circuit, 200, 200-1…Connector, 210…Cable, 211…High-potential side center conductor, 212…Low-potential side center conductor, 213…Shielding conductor Detailed Implementation

[0021] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0022] (Existing insulation inspection system 500)

[0023] First, let's describe the existing insulation inspection system 500. Figure 5 This is a block diagram illustrating a structural example of an insulation inspection system 500. The insulation inspection system 500 includes, for example, a conventional inspection device JS1 and a printed circuit board 30. The printed circuit board 30 is a substrate on which a circuit pattern, which is the object of the insulation inspection, is printed.

[0024] The conventional inspection device JS1 is connected to the circuit pattern 300 of the printed circuit board 30 via cable 110. Furthermore, the conventional inspection device JS1 is connected to the circuit pattern 310 of the printed circuit board 30 via cable 120. Here, circuit pattern 300 and circuit pattern 310 are different circuit patterns printed on the same printed circuit board 30.

[0025] The existing testing device JS1 includes, for example, a voltage source VDD, an ammeter A1, a resistor R1, a cable 110, a cable 120, a voltmeter V, an ammeter A2, and a judgment unit 150. The voltage source VDD is a voltage source that applies a predetermined testing voltage to the circuit pattern 300, such as a variable voltage source. Alternatively, a current source may be provided instead of the voltage source VDD. In this case, the current source supplies a predetermined current to the circuit pattern 300.

[0026] Ammeter A1 detects the current flowing through the high-side of the conventional inspection device JS1. Resistor R1 is the resistance between ammeter A1 and circuit pattern 300. Voltmeter V detects the voltage applied between the circuit patterns (circuit pattern 300 and circuit pattern 310). Cable 110 connects circuit pattern 300 and the measuring terminal on the high-side of the conventional inspection device JS1. Figure 5The black dot indicates the location. Cable 120 connects the circuit pattern 310 to the low-side measuring terminal in the existing inspection device JS1. Figure 5 (The black dots indicate the electrical connections.) Ammeter A2 detects the current flowing through the low-potential side of the conventional inspection device JS1. Furthermore, when applying voltage to multiple circuit boards in the printed circuit board 30, voltage is sometimes applied between multiple circuit patterns and other multiple circuit patterns, between one circuit pattern and other multiple circuit patterns, or between multiple circuit patterns and another circuit pattern.

[0027] Cable 110 includes a center conductor 111 and a shield conductor 112. The center conductor 111 connects to the measuring terminal on the high-potential side and the circuit pattern 300. The center conductor 111 is insulated with an insulator such as polyethylene. The shield conductor 112 is cylindrical to cover the insulator covering the center conductor 111. The shield conductor 112 is connected to ground (GND).

[0028] Cable 120 has a center conductor 121 and a shield conductor 122. The center conductor 121 and shield conductor 122 in cable 120 have the same construction as the center conductor 111 and shield conductor 112 in cable 110, so their description is omitted. The center conductor 121 connects circuit pattern 310 and the measuring terminal on the low-potential side. The shield conductor 122 is connected to the ground terminal GND.

[0029] The determination unit 150 is implemented by executing a program stored in the storage unit by a processor such as the CPU (Central Processing Unit) in the conventional inspection device JS1, which is a computer device. The determination unit 150 includes a voltage control circuit connected to and controlling the voltage source VDD. The determination unit 150 is connected to ammeters A1 and A2 respectively to acquire the current values ​​measured by ammeters A1 and A2. The determination unit 150 is connected to a voltmeter V to acquire the voltage value measured by the voltmeter V.

[0030] The determination unit 150 applies a voltage to the circuit patterns (between circuit pattern 300 and circuit pattern 310) on the printed circuit board 30 via cable 110. The determination unit 150 detects the current flowing between the circuit patterns. For example, when the insulation between circuit pattern 300 and circuit pattern 310 is sufficient, almost no current flows through circuit pattern 310 even when a voltage is applied to circuit pattern 300. When the insulation between circuit pattern 300 and circuit pattern 310 is insufficient, if a voltage is applied to circuit pattern 300, a larger current flows through circuit pattern 310 compared to the case of sufficient insulation. In this case, the insulation resistance between the circuit patterns is lower than that of the case of sufficient insulation. The determination unit 150 uses this property to perform an insulation check.

[0031] Here, the determination unit 150 performs spark detection during the insulation inspection process. The determination unit 150 performs spark detection by detecting the voltage drop between circuit patterns or the increase in current flowing through the circuit patterns when a spark occurs. In the following description, the waveform representing the temporal change of the instantaneously increasing current value when a spark occurs is referred to as the "spark waveform." Furthermore, the instantaneously increasing current value when a spark occurs is referred to as the "spark current." Furthermore, the maximum value of the spark current is referred to as the "peak current."

[0032] The determination unit 150 determines, for example, whether the peak current flowing through the circuit patterns during a predetermined detection time is above a predetermined threshold when a voltage is applied between the circuit patterns. The detection time is a predetermined time interval starting from the point when the voltage begins to rise after the voltage is applied. The current value during this time can be detected using either ammeter A1 or A2. Alternatively, the determination unit 150 can also make a determination based on the current values ​​of both ammeters A1 and A2.

[0033] If the current flowing through the circuit patterns exceeds a threshold, the determination unit 150 determines that an electric spark has occurred. On the other hand, if the current flowing through the circuit patterns is less than a predetermined threshold, the determination unit 150 determines that no electric spark has occurred. That is, the determination unit 150 determines whether an electric spark has occurred between the circuit patterns based on the current flowing through the circuit patterns obtained by applying a check voltage between the circuit patterns.

[0034] Furthermore, the above description uses the case where the determination unit 150 determines whether an electric spark has occurred based on the current value flowing between the circuit patterns. However, it is not limited to this. The determination unit 150 may also determine whether an electric spark has occurred between the circuit patterns based on the voltage value applied between the circuit patterns (such as the amount of voltage drop).

[0035] (Existing insulation inspection system 600)

[0036] Next, the existing insulation inspection system 600 will be described. Figure 6 This is a block diagram illustrating a structural example of a conventional insulation inspection system 600. The conventional insulation inspection system 600 differs from the insulation inspection system 500 in that the cable connecting the device and the printed circuit board 30 is a two-core cable (with two center conductors). In the following description, only the differences from the insulation inspection system 500 will be explained, while descriptions of structures identical to those in the insulation inspection system 500 will be omitted.

[0037] The insulation inspection system 600 includes, for example, a conventional inspection device JS2 and a printed circuit board 30. The conventional inspection device JS2 is connected to the circuit patterns 300, 310 of the printed circuit board 30 via a cable 210.

[0038] The existing inspection device JS2 includes, for example, a voltage source VDD, an ammeter A3, a resistor R2, a cable 210, a voltmeter V, an ammeter A4, and a determination unit 250. The elements of the voltage source VDD, ammeter A3, resistor R2, voltmeter V, ammeter A4, and determination unit 250 are the same as those of the voltage source VDD, ammeter A1, resistor R1, voltmeter V, ammeter A2, and determination unit 150 in the existing inspection device JS1. Therefore, their description is omitted.

[0039] Cable 210 is a 2-core cable. That is, cable 210 connects the high-potential side (highside) measuring terminal of the existing testing device JS2. Figure 6 The part indicated by the black dot) and the circuit pattern 300 are electrically connected. Furthermore, cable 210 connects the circuit pattern 310 to the low-side measuring terminal in the existing inspection device JS2. Figure 6 Electrical connections are made to the areas indicated by the black dots.

[0040] Cable 210 includes a high-potential-side center conductor 211, a low-potential-side center conductor 212, and a shielding conductor 213. The high-potential-side center conductor 211 connects the high-potential-side measuring terminal and the circuit pattern 300. The high-potential-side center conductor 211 is insulated with an insulator such as polyethylene. The low-potential-side center conductor 212 connects the circuit pattern 310 and the low-potential-side measuring terminal. The low-potential-side center conductor 212 is also insulated with an insulator such as polyethylene. The shielding conductor 213 is cylindrical, collectively covering both the insulator covering the high-potential-side center conductor 211 and the insulator covering the low-potential-side center conductor 212. The shielding conductor 213 is connected, for example, to ground (GND).

[0041] Generally, in cables, the shield conductor and the center conductor are placed close together. Therefore, sometimes the center conductor and shield conductor function unexpectedly as capacitors. That is, the capacitance of this unexpected capacitor can become the parasitic capacitance of the cable. This parasitic capacitance is the same in both the 1-core cable (with one center conductor) in the existing inspection device JS1 and the 2-core cable in the existing inspection device JS2.

[0042] exist Figure 5In the circuit diagram, when a check voltage is applied between the circuit patterns, it is assumed that current flows in routes RT2 and RT3 in addition to route RT1 due to parasitic capacitance. Route RT1 is the path where current is expected to flow during the check. Route RT2 is assumed to be the path where current flows from the center conductor 111 to the shield conductor 112 via the parasitic capacitance KY1 of cable 110. Route RT3 is assumed to be the path where current flows from the center conductor 121 to the shield conductor 122 via the parasitic capacitance KY2 of cable 120.

[0043] exist Figure 6 In this circuit, when a check voltage is applied between the circuit patterns, it is assumed that current also flows in routes RT11 and RT12, in addition to route RT10. Route RT10 is the path where current is expected to flow during the check. Route RT11 is assumed to be the path where current flows from the high-potential side center conductor 211 to the shield conductor 213 via the parasitic capacitance KY3 between the high-potential side center conductor 211 and the shield conductor 213. Route RT12 is assumed to be the path where current flows from the low-potential side center conductor 212 to the shield conductor 213 via the parasitic capacitance KY4 between the low-potential side center conductor 212 and the shield conductor 213.

[0044] Thus, due to the parasitic capacitance in the cable, it is difficult to accurately detect the current flowing through the circuit patterns during inspection. Furthermore, the parasitic capacitance in the cable can cause a gradual slope in current changes, resulting in a blunted waveform. Therefore, during insulation inspection, it takes a certain amount of time for the current flowing through the circuit patterns to stabilize, which is a major reason for the extended inspection time. Moreover, even in the case of electrical sparks, the spark waveform is sometimes hidden by parasitic capacitance, making it impossible to detect the instantaneous increase in current value and thus the occurrence of electrical sparks.

[0045] As a countermeasure, in this embodiment, the parasitic capacitance of the cable appears to disappear. That is, in this embodiment, the parasitic capacitance of the cable is canceled (eliminated). Hereinafter, this embodiment will be described in the order of the first embodiment to the fourth embodiment.

[0046] (First Embodiment)

[0047] The insulation inspection system 1 according to the first embodiment is described. Figure 1A , Figure 1B This is a block diagram illustrating a structural example of the insulation inspection system 1 according to the first embodiment. In the insulation inspection system 1, the parasitic capacitance of the cable 110 in the conventional inspection device JS1 appears to be eliminated.

[0048] like Figure 1AAs shown, the insulation inspection system 1 includes an inspection device 10 and a printed circuit board 30. The inspection device 10 includes a voltage source VDD, an ammeter A1, a resistor R1, a voltmeter V, a connection 100, a buffer B, cables 110 and 120, an ammeter A2, and a judgment unit 150. The elements of the voltage source VDD, ammeter A1, resistor R1, voltmeter V, cable 120, ammeter A2, and judgment unit 150 are the same as those assigned the same designations in the existing inspection device JS1. Therefore, their description is omitted.

[0049] In this embodiment, the center conductor 111 and the shield conductor 112 of the cable 110 are connected via the buffer B through the connection portion 100. That is, the connection portion 100 connects the center conductor 111 and the shield conductor 112. Here, the connection portion 100 is an example of an "elimination portion".

[0050] Therefore, the potential of the shielding conductor 112 becomes the same as the potential of the center conductor 111. Consequently, no current flows due to the potential difference between the shielding conductor 112 and the center conductor 111. Therefore, the parasitic capacitance (denoted by CM1) generated between the shielding conductor 112 and the center conductor 111 can be ignored, and the parasitic capacitance appears to be eliminated.

[0051] In addition, such as Figure 1B As shown, the center conductor 111 and the shield conductor 112 of the cable 110 can also be connected directly without a buffer.

[0052] If the parasitic capacitance of cable 110 is eliminated, then when a check voltage is applied between the patterns, Figure 5 No current flows through the path RT2 in the diagram. That is, it is the same as... Figure 5 Compared to existing systems, it can detect the current value flowing between circuit patterns during inspection with higher accuracy.

[0053] (Second Implementation)

[0054] The insulation inspection system 1A according to the second embodiment is described. Figure 2A , Figure 2B , Figure 2C This is a block diagram illustrating a structural example of the insulation inspection system 1A according to the second embodiment. In the insulation inspection system 1, the parasitic capacitance of the cable 120 in the conventional inspection device JS1 appears to be eliminated.

[0055] like Figure 2AAs shown, the insulation inspection system 1A includes an inspection device 10A and a printed circuit board 30. The inspection device 10A includes a voltage source VDD, an ammeter A1, a resistor R1, a voltmeter V, a cable 110, a cable 120, a virtual grounding circuit 130, an ammeter A20, and a judgment unit 150. The elements of the voltage source VDD, ammeter A1, resistor R1, voltmeter V, and cable 110 are the same as those assigned the same designations in the existing inspection device JS1. Therefore, their description is omitted. The ammeter A20... Figure 2A China and Figure 5 The ammeter A2 is represented by a different graph, but it has the same function as the ammeter A2, detecting the current flowing through the low potential side of the inspection device 10A.

[0056] In this embodiment, the center conductor 121 of the cable 120 is connected to the virtual grounding circuit 130. The virtual grounding circuit 130 is a negative feedback circuit constructed using an operational amplifier, which functions to make the potential of the input terminals of the operational amplifier equal to that of the ground. In the virtual grounding circuit 130, the positive input terminal (+) of the operational amplifier is connected to the ground terminal GND. Thus, the center conductor 121 is maintained at the same potential as the ground terminal GND. Here, the virtual grounding circuit 130 is an example of an "elimination unit".

[0057] Therefore, the potential of the center conductor 121 and the potential of the shielding conductor 122 become the same. Consequently, no current flows due to the potential difference between the center conductor 121 and the shielding conductor 122. Therefore, the parasitic capacitance (denoted by CM2) generated between the center conductor 121 and the shielding conductor 122 can be ignored, and the parasitic capacitance appears to be eliminated.

[0058] If the parasitic capacitance of cable 120 is eliminated, then when a check voltage is applied between the patterns, Figure 5 No current flows through the path RT3 in the diagram. That is, it is the same as... Figure 5 Compared to existing systems, it can detect the current value flowing between circuit patterns during inspection with higher accuracy.

[0059] Alternatively, the connection portion 100 shown in FIG1 can be provided in the insulation inspection system 1A. That is, the insulation inspection system 1A can also be a structure that includes both the connection portion 100 for eliminating the parasitic capacitance of the cable 110 and the virtual grounding circuit 130 for eliminating the parasitic capacitance of the cable 120.

[0060] In addition, such as Figure 2BAs shown, in order to visually eliminate the parasitic capacitance of cable 120, a virtual grounding circuit 130 can be provided instead of a connection portion 100-1 identical to the connection portion 100 in the first embodiment can be provided on the low-potential side. That is, a connection portion is provided that connects the center conductor 121 and the shield conductor 122 via the buffer B. This connection portion 100-1 is also an example of an "elimination portion".

[0061] In addition, such as Figure 2C As shown, in order to seemingly eliminate the parasitic capacitance of cable 120, the center conductor 121 and the shield conductor 122 can be directly connected without going through a buffer.

[0062] (Third Implementation)

[0063] The insulation inspection system 2 described in the third embodiment is explained. Figure 3A , Figure 3B This is a block diagram illustrating a structural example of the insulation inspection system 2 according to the third embodiment. In the insulation inspection system 2, the parasitic capacitance of the cable 210 in the conventional inspection device JS2 appears to be eliminated.

[0064] like Figure 3A As shown, the insulation inspection system 2 includes an inspection device 20 and a printed circuit board 30. The inspection device 20 includes a voltage source VDD, an ammeter A3, a resistor R2, a voltmeter V, a connection 200, a buffer B, a cable 210, an ammeter A4, and a judgment unit 250. The elements of the voltage source VDD, ammeter A3, resistor R2, voltmeter V, and judgment unit 250 are the same as those assigned the same designations in the existing inspection device JS2. Therefore, their description is omitted.

[0065] In this embodiment, the high-potential side center conductor 211 and shield conductor 213 of the cable 210 are connected via a buffer B through a connection portion 200. That is, the connection portion 200 connects the high-potential side center conductor 211 and shield conductor 213. Here, the connection portion 200 is an example of an "elimination portion".

[0066] Therefore, the potential of the high-potential side center conductor 211 and the potential of the shielding conductor 213 become the same. Consequently, no current flows due to the potential difference between the high-potential side center conductor 211 and the shielding conductor 213. Therefore, the parasitic capacitance (represented by the numeral CM3) generated between the high-potential side center conductor 211 and the shielding conductor 213 can be ignored, and the parasitic capacitance appears to be eliminated.

[0067] In addition, such as Figure 3B As shown, the center conductor 211 and shield conductor 213 of cable 210 can also be directly connected without a buffer.

[0068] If the parasitic capacitance of cable 210 is eliminated, then when a check voltage is applied between patterns, Figure 6 No current flows through the path RT11 in the circuit. That is, with Figure 6 Compared to existing systems, it can detect the current value flowing between circuit patterns during inspection with higher accuracy.

[0069] (Fourth implementation)

[0070] The insulation inspection system 2A according to the fourth embodiment is described. Figure 4A , Figure 4B , Figure 4C This is a block diagram illustrating a structural example of the insulation inspection system 2A according to the fourth embodiment. In the insulation inspection system 2A, the parasitic capacitance of the cable 210 in the conventional inspection device JS2 appears to be eliminated.

[0071] like Figure 4A As shown, the insulation inspection system 2A includes an inspection device 20A and a printed circuit board 30. The inspection device 20A includes a voltage source VDD, an ammeter A3, a resistor R2, a voltmeter V, a cable 210, a virtual grounding circuit 230, and an ammeter A40. The elements of the voltage source VDD, ammeter A3, resistor R2, and voltmeter V are the same as those assigned the same designations in the existing inspection device JS2. Therefore, their description is omitted. The ammeter A40... Figure 4A China and Figure 6 It is represented by a different graph than the ammeter A4, but has the same function as the ammeter A4, detecting the current flowing through the low potential side of the inspection device 20A.

[0072] In this embodiment, the low-potential side center conductor 212 of cable 210 is connected to the virtual grounding circuit 230. The virtual grounding circuit 230 is the same as the virtual grounding circuit 130 of the inspection device 10A. Therefore, its description is omitted. In the virtual grounding circuit 230, the positive input terminal (+) of the operational amplifier is connected to the ground terminal GND. As a result, the low-potential side center conductor 212 is maintained at the same potential as the ground terminal GND. Here, the virtual grounding circuit 230 is an example of an "elimination unit".

[0073] Therefore, the potential of the low-potential side center conductor 212 and the potential of the shielding conductor 213 become the same. Consequently, no current flows due to the potential difference between the low-potential side center conductor 212 and the shielding conductor 213. Therefore, the parasitic capacitance (represented by the numeral CM4) generated between the low-potential side center conductor 212 and the shielding conductor 213 can be ignored, and the parasitic capacitance appears to be eliminated.

[0074] If the parasitic capacitance of cable 210 is eliminated, then when a check voltage is applied between patterns, Figure 6 No current flows through the path RT12 in the circuit. That is, it is the same as... Figure 6 Compared to existing systems, it can detect the current value flowing between circuit patterns during inspection with higher accuracy.

[0075] In addition, such as Figure 4B As shown, in order to visually eliminate the parasitic capacitance of cable 210, a virtual grounding circuit 230 can be provided instead of a connection portion 200-1 identical to the connection portion 200 in the third embodiment can be provided on the low-potential side. That is, a connection portion is provided that connects the low-potential side center conductor 212 and the shielding conductor 213 via buffer B. This connection portion 200-1 is also an example of an "elimination portion".

[0076] In addition, such as Figure 4C As shown, in order to seemingly eliminate the parasitic capacitance of cable 210, the low-potential side center conductor 212 and shield conductor 213 can be directly connected without going through a buffer.

[0077] As mentioned above, Figure 1A The inspection apparatus 10 of the first embodiment shown includes a cable 110, a connector 100, and a determination unit 150. The cable 110 connects the printed circuit board 30 and the inspection apparatus 10. The cable 110 includes a shielded cable equipped with a center conductor 111, an insulator covering the center conductor 111 with an insulating film, and a shielding conductor 112 covering the insulator. In the cable 110, the center conductor 111 is connected to the high-potential side between circuit patterns. The connector 100 connects the center conductor 111 and the shielding conductor 112. The determination unit 150 determines the quality of the insulation between the circuit patterns. The determination unit 150 applies an inspection voltage to the circuit patterns of the printed circuit board 30 via the cable 110. The determination unit 150 determines the quality of the insulation based on the voltage value between the circuit patterns obtained by applying the inspection voltage, or the current value flowing through the circuit patterns.

[0078] Therefore, in the inspection apparatus 10 of the first embodiment, the center conductor 111 and the shielding conductor 112 are connected. Thus, the parasitic capacitance of the cable 110 appears to be eliminated. Therefore, the current value flowing between the circuit patterns can be accurately detected during inspection. Therefore, even when parasitic capacitance exists in the cable 110, the insulation state between the circuit patterns can be inspected with high precision.

[0079] Furthermore, by eliminating the parasitic capacitance of cable 110, the time required for the applied voltage to rise can be shortened. This reduces the inspection time and improves inspection efficiency.

[0080] Furthermore, conventionally, the frequency characteristics of the measurement path have deteriorated due to the parasitic capacitance of cable 110. Here, the measurement path refers to the path through which current flows by applying voltage. This deterioration in frequency characteristics means that high-frequency characteristics decrease and the time constant of the current flowing through the measurement path increases. In contrast, in this embodiment, the parasitic capacitance of cable 110 is eliminated. As a result, the frequency characteristics of the measurement path are improved. This improvement in frequency characteristics means that high-frequency characteristics are enhanced, suppressing the decrease in the rate of change of current flowing through the measurement path, and the rate of change of current is faster compared to existing methods. Consequently, the high-frequency waveform of the spark current measured by ammeter A1 or ammeter A20 becomes sharper, improving the measurement accuracy of peak current.

[0081] Furthermore, by eliminating the parasitic capacitance of cable 110, it is possible to detect the peak value of the spark waveform that was previously hidden by parasitic capacitance during conventional inspections. That is, conventionally, due to parasitic capacitance, the spark waveform is flat, and there are spark waveforms whose peak values ​​are undetectable and thus hidden. In this embodiment, by eliminating the parasitic capacitance of cable 110, the rise in waveform becomes sharper than before, enabling the detection of previously hidden peak values.

[0082] also, Figure 2A The inspection apparatus 10A of the second embodiment shown includes a cable 120, a virtual grounding circuit 130, and a determination unit 150. The cable 120 connects the printed circuit board 30 and the inspection apparatus 10A. The cable 120 includes a shielded cable equipped with a center conductor 121, an insulator with an insulating film covering the center conductor 121, and a shielding conductor 122 covering the insulator. Regarding the cable 120, the center conductor 121 is connected to the low-potential side between circuit patterns. The shielding conductor 122 is grounded. The virtual grounding circuit 130 is connected to the center conductor 121. Therefore, in the inspection apparatus 10A of the second embodiment, the parasitic capacitance of the cable 120 appears to be eliminated. Thus, the same effect as described above is achieved.

[0083] also, Figure 3AThe inspection device 20 of the third embodiment shown includes a cable 210, a connector 200, and a determination unit 250. The cable 210 connects the printed circuit board 30 and the inspection device 20. The cable 210 includes a shielded cable equipped with a high-potential side center conductor 211, a low-potential side center conductor 212, an insulator, and a shielding conductor 213. The insulator provides an insulating coating for both the high-potential side center conductor 211 and the low-potential side center conductor 212. The shielding conductor 213 covers the insulator. The high-potential side center conductor 211 is connected to the high-potential side between circuit patterns. The low-potential side center conductor 212 is connected to the low-potential side between circuit patterns. The connector 200 connects the high-potential side center conductor 211 and the shielding conductor 213. Therefore, in the inspection device 20 of the third embodiment, the parasitic capacitance of the cable 210 appears to be eliminated. Thus, the same effect as described above is achieved.

[0084] also, Figure 4A The inspection device 20A of the fourth embodiment shown includes a cable 210, a virtual grounding circuit 230, and a determination unit 250. The high-potential side center conductor 211 is connected to the high-potential side between circuit patterns. The low-potential side center conductor 212 is connected to the low-potential side between circuit patterns. The shielding conductor 213 is grounded. The virtual grounding circuit 230 is connected to the low-potential side center conductor 212. Therefore, in the inspection device 20A of the fourth embodiment, the parasitic capacitance of the cable 210 appears to be eliminated. Thus, the same effect as described above is achieved.

[0085] Furthermore, in the above embodiment, the expression "connected to ground (GND)" is used. The potential of ground (GND) in this case is not limited to the case of representing an absolute potential of 0 (V). That is, the ground potential includes the potential at the middle of the power supply of the circuit in the inspection device (intermediate potential). The intermediate potential is the potential between the high-potential side and the low-potential side of the power supply. For example, the intermediate potential is 7.5 (V) when the high-potential side of the power supply is 15 (V) and the low-potential side is 0 (V). Ground (GND) can be such an intermediate potential of 7.5 (V), or it can be any potential between the high-potential side of 15 (V) and the low-potential side of 0 (V).

[0086] While some embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention as well as within the scope of the invention as described in the claims and its equivalents.

Claims

1. An inspection device, characterized in that, include: Cables connect the printed circuit board to be inspected and the inspection device. Elimination section, which eliminates the parasitic capacitance of the cable; as well as The determination unit determines the insulation condition between the circuit patterns or whether electrical sparks have occurred between the circuit patterns based on the voltage value between the circuit patterns obtained by applying a test voltage between the circuit patterns on the printed circuit board via the cable, or the current value flowing between the circuit patterns. The cable is a two-core cable, comprising a shielded cable equipped with a high-potential side center conductor, a low-potential side center conductor, an insulator that respectively insulates the high-potential side center conductor and the low-potential side center conductor, and a shielded conductor that together covers the insulator that insulates the high-potential side center conductor and the insulator that insulates the low-potential side center conductor. The high-potential side center conductor is connected to the high-potential side between the circuit patterns, and the low-potential side center conductor is connected to the low-potential side between the circuit patterns.

2. The inspection device as described in claim 1, characterized in that, The elimination section is a connection section that makes the high-potential side center conductor and the shielding conductor at the same potential.

3. The inspection device as described in claim 2, characterized in that, The elimination section is a connection section that connects the high-potential side center conductor and the shielding conductor.

4. The inspection device as claimed in claim 1, characterized in that, The shielding conductor is set to ground potential. The elimination section is a virtual grounding circuit that virtually grounds the center conductor on the low-potential side.

5. The inspection device as claimed in claim 1, characterized in that, The elimination section is a connection that makes the center conductor and the shielding conductor on the low-potential side at the same potential.

6. The inspection device as described in claim 5, characterized in that, The elimination section is a connection section that connects the low-potential side center conductor and the shielding conductor.

7. An inspection method, characterized in that, This inspection method includes an inspection device for a cable, wherein the cable is used to connect the printed circuit board to be inspected and the inspection device. In this inspection method... The elimination section eliminates the parasitic capacitance of the cables connecting the printed circuit board to the inspection device, which are the objects of inspection. The determination unit determines the insulation condition between the circuit patterns or whether electrical sparks have occurred between the circuit patterns based on the voltage value between the circuit patterns obtained by applying a test voltage between the circuit patterns on the printed circuit board via the cable, or the current value flowing between the circuit patterns. The cable is a two-core cable, comprising a shielded cable equipped with a high-potential side center conductor, a low-potential side center conductor, an insulator that respectively insulates the high-potential side center conductor and the low-potential side center conductor, and a shielded conductor that together covers the insulator that insulates the high-potential side center conductor and the insulator that insulates the low-potential side center conductor. The high-potential side center conductor is connected to the high-potential side between the circuit patterns, and the low-potential side center conductor is connected to the low-potential side between the circuit patterns.

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