CN213337870U

CN213337870U - Inspection apparatus

Info

Publication number: CN213337870U
Application number: CN202021009118.8U
Authority: CN
Inventors: 三宅康志
Original assignee: Yamaha Fine Technologies Co Ltd
Current assignee: Yamaha Fine Technologies Co Ltd
Priority date: 2020-04-15
Filing date: 2020-06-04
Publication date: 2021-06-01
Anticipated expiration: 2030-06-04
Also published as: KR20210127874A; KR102648218B1; JP2021169951A; CN113533908A

Abstract

Provided is an inspection device capable of inspecting the insulation state between circuit patterns with high accuracy even when a cable has a parasitic capacitance. The inspection apparatus includes: a cable for connecting the printed circuit board to be inspected and the inspection device; a cancellation section that cancels a parasitic capacitance of the cable; and a determination unit that determines whether or not the insulation state between the circuit patterns is good or not, or whether or not a spark occurs between the circuit patterns, based on a voltage value between the circuit patterns obtained by applying an inspection voltage between the circuit patterns of the printed circuit board via the cable, or a current value flowing between the circuit patterns.

Description

Inspection apparatus

Technical Field

The utility model relates to an inspection device.

Background

Conventionally, in a printed circuit board having a plurality of wiring patterns, an insulation inspection apparatus determines whether or not the insulation state of each wiring pattern from the other wiring patterns is good (whether or not sufficient insulation is ensured), and thereby performs an insulation inspection for inspecting whether or not the printed circuit board is good (for example, patent document 1).

In patent document 1, the insulation state between circuit patterns is inspected by applying a voltage between the circuit patterns on a printed board. That is, the insulation state of one circuit pattern from another circuit pattern is checked by applying a voltage to the one circuit pattern and checking a current flowing through the other circuit pattern. In such an insulation inspection apparatus, a circuit pattern of a printed circuit board is connected, for example, via an inspection probe provided at the tip of a cable. The insulation inspection apparatus applies an inspection voltage to the circuit pattern via the cable and the inspection probe. The insulation inspection device inspects whether the insulation device is good or not based on the insulation resistance value calculated from the voltage value between the circuit patterns and the current value flowing through the cable.

Further, the insulation inspection apparatus performs spark detection simultaneously with the insulation inspection. The spark is a phenomenon in which insulation breakdown occurs due to a potential difference generated between circuit patterns, and current instantaneously flows between the circuit patterns. The insulation inspection apparatus measures a voltage between the circuit patterns or a current flowing between the circuit patterns during a predetermined spark detection time during the insulation inspection. The insulation inspection apparatus determines that an electric spark has occurred when a voltage drop between circuit patterns is greater than or equal to a predetermined value, that is, a so-called drop voltage. Alternatively, the insulation inspection apparatus determines that a spark has occurred when a so-called spark current, which is an increase in current flowing between circuit patterns by a predetermined threshold value or more, occurs.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5727976

SUMMERY OF THE UTILITY MODEL

However, due to the parasitic capacitance of the cable, the value of the current flowing through the circuit pattern or the value of the voltage applied to the circuit pattern may not be measured accurately. Therefore, there is a problem that it is difficult to accurately check whether the insulation state is good.

The utility model provides an even there is parasitic capacitance's condition in the cable, also can check the insulating state between the circuit pattern or have between the circuit pattern with high accuracy inspection device that does not have the electric spark to take place.

In order to solve the above problem, an aspect of the present invention is an inspection apparatus including: a cable for connecting the printed circuit board to be inspected and the inspection device; a cancellation section that cancels a parasitic capacitance of the cable; and a determination unit that determines whether or not the insulation state between the circuit patterns is good or not, or whether or not a spark occurs between the circuit patterns, based on a voltage value between the circuit patterns obtained by applying an inspection voltage between the circuit patterns of the printed circuit board via the cable, or a current value flowing between the circuit patterns.

According to the utility model discloses, can check insulating state or circuit pattern between circuit pattern with high accuracy and have or not the electric spark to take place between.

Drawings

Fig. 1A and 1B are block diagrams showing a configuration example of an insulation inspection system 1 according to embodiment 1.

Fig. 2A, 2B, and 2C are block diagrams showing a configuration example of the insulation inspection system 1A according to embodiment 2.

Fig. 3A and 3B are block diagrams showing a configuration example of the insulation inspection system 2 according to embodiment 3.

Fig. 4A, 4B, and 4C are block diagrams showing a configuration example of the insulation inspection system 2A according to embodiment 4.

Fig. 5 is a block diagram showing a configuration example of a conventional insulation inspection system 500.

Fig. 6 is a block diagram showing a configuration example of a conventional insulation inspection system 600.

Description of the reference symbols

1 … insulation inspection system, 10 … inspection apparatus, 100, 100-1 … connection section, 110 … cable, 111 … center conductor, 112 … shield conductor, 120 … cable, 121 … center conductor, 122 … shield conductor, 130 … virtual ground circuit, 200, 200-1 … connection section, 210 … cable, 211 … high potential side center conductor, 212 … low potential side center conductor, 213 … shield conductor

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(existing insulation inspection System 500)

First, the conventional insulation inspection system 500 is explained. Fig. 5 is a block diagram showing a configuration example of the insulation inspection system 500. The insulation inspection system 500 includes, for example, a conventional inspection device JS1 and the printed substrate 30. The printed board 30 is a board on which a circuit pattern to be inspected for insulation inspection is printed.

The conventional inspection device JS1 is connected to the circuit pattern 300 of the printed circuit board 30 via the cable 110. The conventional inspection device JS1 is connected to the circuit pattern 310 of the printed circuit board 30 via the cable 120. Here, the

circuit patterns

300 and 310 are different circuit patterns printed on the same printed substrate 30.

The conventional inspection 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 determination unit 150. The voltage source VDD is a voltage source for applying a predetermined inspection voltage to the circuit pattern 300, and is, for example, a variable voltage source. Instead of the voltage source VDD, a current source may be provided. At this time, the current source supplies a predetermined current to the circuit pattern 300.

Current meter a1 detects a current flowing through the high potential side (Highside) of conventional inspection device JS 1. Resistance R1 is the resistance between ammeter a1 and circuit pattern 300. The voltmeter V detects a voltage applied between the circuit patterns (between the circuit pattern 300 and the circuit pattern 310). The cable 110 electrically connects the circuit pattern 300 and a measurement end on the high potential side (a portion shown by a black dot in fig. 5) in the conventional inspection device JS 1. The cable 120 electrically connects the circuit pattern 310 and a measurement end (a portion indicated by a black dot in fig. 5) on the low potential side (Lowside) in the conventional inspection device JS 1. The ammeter a2 detects a current flowing through the low potential side in the conventional type inspection device JS 1. When a voltage is applied to a plurality of circuit boards on the printed board 30, a voltage may be applied between a plurality of circuit patterns and another plurality of circuit patterns, between 1 circuit pattern and another plurality of circuit patterns, or between a plurality of circuit patterns and another circuit pattern.

The cable 110 includes a center conductor 111 and a shield conductor 112. The central conductor 111 connects the measurement terminal on the high potential side and the circuit pattern 300. The central conductor 111 is coated with an insulating film of polyethylene or the like. The shield conductor 112 is provided in a cylindrical shape so as to cover the insulator insulating and coating the central conductor 111. The shield conductor 112 is connected to a ground terminal GND (ground).

The cable 120 includes a center conductor 121 and a shield conductor 122. The central conductor 121 and the shield conductor 122 in the cable 120 are of the same configuration as the central conductor 111 and the shield conductor 112 in the cable 110, and therefore, the description thereof is omitted. The central conductor 121 connects the circuit pattern 310 and the measurement terminal on the low potential side. The shield conductor 122 is connected to the ground terminal GND (ground).

The determination unit 150 is realized by executing a program stored in a storage unit by a processor such as a cpu (central Processing unit) in the conventional inspection device JS1 as a computer device. The determination unit 150 includes a voltage control circuit connected to the voltage source VDD to control the voltage source VDD. The determination unit 150 is connected to ammeters a1 and a2, respectively, and acquires current values measured by ammeters a1 and a 2. The determination unit 150 is connected to the voltmeter V, and acquires a voltage value measured by the voltmeter V.

The determination unit 150 applies a voltage between the circuit patterns (between the circuit patterns 300 and 310) of the printed circuit board 30 via the cable 110. The determination unit 150 detects a current value flowing between the circuit patterns. For example, when the circuit pattern 300 and the circuit pattern 310 are sufficiently insulated from each other, a current hardly flows through the circuit pattern 310 even if a voltage is applied to the circuit pattern 300. When the insulating state between the circuit pattern 300 and the circuit pattern 310 is insufficient, a larger current flows through the circuit pattern 310 when a voltage is applied to the circuit pattern 300 than when the insulating state is sufficient. In this case, the insulation resistance value between the circuit patterns becomes lower than that in the case where the insulation state is sufficient. The determination unit 150 performs insulation inspection using such a property.

Here, the determination unit 150 detects the spark during the insulation inspection. The determination unit 150 detects an electric spark by detecting a voltage drop between circuit patterns or an increase in a current value flowing between circuit patterns, which occurs when an electric spark occurs. In the following description, a waveform indicating a time-series change in a current value that instantaneously increases when an electric spark occurs is referred to as an "electric spark waveform". Further, a current value that is instantaneously increased at the time of occurrence of an electric spark is referred to as "electric spark current". The maximum value of the spark current is referred to as "peak current".

The determination unit 150 determines whether or not a current value of a peak current flowing between the circuit patterns is equal to or greater than a predetermined threshold value for a predetermined detection time when a voltage is applied between the circuit patterns, for example. The detection time is a predetermined time interval starting from the time when the voltage starts to rise after the voltage is applied. The current value at this time can be detected by using any one of the ammeter a1, a 2. Determination unit 150 may perform the determination based on the current values of both ammeters a1 and a 2.

When a current equal to or greater than a threshold value flows, the determination unit 150 determines that a spark has occurred. On the other hand, when the current value flowing between the circuit patterns is smaller than the predetermined threshold value, the determination unit 150 determines that no spark has occurred. That is, the determination unit 150 determines whether or not the spark is generated between the circuit patterns based on the value of the current flowing between the circuit patterns obtained by applying the inspection voltage between the circuit patterns.

In the above description, the case where the determination unit 150 determines whether or not the spark is generated based on the current value flowing between the circuit patterns has been described as an example. But is not limited thereto. The determination unit 150 may determine whether or not the spark occurs between the circuit patterns based on a voltage value (a drop amount of the voltage value, etc.) applied between the circuit patterns.

(existing insulation inspection System 600)

Next, the conventional insulation inspection system 600 will be explained. Fig. 6 is a block diagram showing a configuration example of a conventional insulation inspection system 600. The conventional insulation inspection system 600 is different from the insulation inspection system 500 in that the cable connecting the device and the printed circuit board 30 is a 2-core (2 central conductors) cable. In the following description, only points different from the insulation inspection system 500 will be described, and the description of the same configuration as the insulation inspection system 500 will be omitted.

The insulation inspection system 600 includes, for example, a conventional inspection device JS2 and the printed substrate 30. The conventional inspection device JS2 is connected to the

circuit patterns

300 and 310 of the printed circuit board 30 via the cable 210.

The conventional 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. Elements of voltage source VDD, ammeter A3, resistor R2, voltmeter V, ammeter a4, and determination unit 250 are the same as elements of voltage source VDD, ammeter a1, resistor R1, voltmeter V, ammeter a2, and determination unit 150 in conventional inspection device JS 1. Therefore, the description thereof is omitted.

Cable 210 is a 2-core cable. That is, the cable 210 electrically connects the measurement end (the portion indicated by the black dot in fig. 6) on the high potential side (Highside) in the conventional inspection device JS2 and the circuit pattern 300. Further, the cable 210 electrically connects the circuit pattern 310 and a measurement end (a portion indicated by a black dot in fig. 6) on the low potential side (Lowside) in the conventional inspection device JS 2.

The cable 210 includes a high-potential side center conductor 211, a low-potential side center conductor 212, and a shield conductor 213. The high potential side center conductor 211 connects the measurement terminal on the high potential side and the circuit pattern 300. The high-potential side center conductor 211 is coated with an insulating film made of an insulator such as polyethylene. The low-potential-side center conductor 212 connects the circuit pattern 310 and the measurement terminal on the low potential side. The low-potential side center conductor 212 is insulated and coated with an insulator such as polyethylene. The shield conductor 213 is provided in a tubular shape so as to cover an insulator for insulating the high-potential side center conductor 211 and an insulator for insulating the low-potential side center conductor 212 in common. The shield conductor 213 is connected to the ground GND, for example.

Generally, in a cable, a shield conductor and a center conductor are disposed close to each other. Therefore, the center conductor and the shield conductor may function as an unexpected capacitor. That is, the capacitance of the unexpected capacitor may become a parasitic capacitance of the cable. The same applies to the 1-core (1 central conductor) cable in the conventional inspection device JS1 and the 2-core cable in the conventional inspection device JS2, in which a parasitic capacitance is generated in the cable.

In fig. 5, when the inspection voltage is applied between the circuit patterns, it is considered that a current flows through the routes RT2 and RT3 in addition to the route RT1 due to the parasitic capacitance. Route RT1 is a path through which a current is supposed to flow at the time of inspection. Route RT2 is a path through which a current is supposed to flow from center conductor 111 to shield conductor 112 via parasitic capacitance KY1 of cable 110. Route RT3 is a path through which a current is supposed to flow from center conductor 121 to shield conductor 122 via parasitic capacitance KY2 of cable 120.

In fig. 6, when the inspection voltage is applied between the circuit patterns, it is considered that a current flows through the route RT11 and the route RT12 in addition to the route RT 10. Route RT10 is a path through which a current is supposed to flow at the time of inspection. Route RT11 is a path through which a current is supposed to flow from high-potential-side center conductor 211 to shield conductor 213 via parasitic capacitance KY3 between high-potential-side center conductor 211 and shield conductor 213. The route RT12 is a path through which a current is considered to flow 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.

In this way, since the parasitic capacitance exists in the cable, it is difficult to accurately detect the value of the current flowing between the circuit patterns at the time of inspection. Further, since the cable has a parasitic capacitance, a change slope of the current value may be gentle, and the waveform may be blunted. Therefore, in the insulation inspection, a certain time is required until the current flowing between the circuit patterns is stabilized, which becomes a factor of increasing the inspection time. Even when a spark occurs, the spark waveform may be hidden by the parasitic capacitance, and the instantaneous increase in current value may not be recognized, so that the spark occurrence may not be detected.

As a countermeasure, in the present embodiment, the parasitic capacitance of the cable is visually eliminated. That is, in the present embodiment, the parasitic capacitance of the cable is eliminated (canceled). The present embodiment will be described below in the order of embodiment 1 to embodiment 4.

(embodiment 1)

An insulation inspection system 1 according to embodiment 1 will be described. Fig. 1A and 1B are block diagrams showing a configuration example of an insulation inspection system 1 according to embodiment 1. In insulation inspection system 1, the parasitic capacitance of cable 110 in existing type inspection device JS1 is made to appear to be eliminated.

As shown in fig. 1A, the insulation inspection system 1 includes an inspection device 10 and a printed substrate 30. The inspection apparatus 10 includes a voltage source VDD, an ammeter a1, a resistor R1, a voltmeter V, a connection unit 100, a buffer B, a cable 110, a cable 120, an ammeter a2, and a determination unit 150. The elements of the voltage source VDD, the ammeter a1, the resistor R1, the voltmeter V, the cable 120, the ammeter a2, and the judgment unit 150 are the same as those given the same reference numerals in the conventional inspection device JS 1. Therefore, the description thereof is omitted.

In the present embodiment, the center conductor 111 and the shield conductor 112 of the cable 110 are connected to each other via the buffer B by 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 the "cancellation portion".

Thereby, the potential of the shield conductor 112 becomes the same potential as the potential of the center conductor 111. Therefore, a current caused by a potential difference between the potential of the shield conductor 112 and the potential of the center conductor 111 does not flow. Therefore, the parasitic capacitance (capacitance indicated by reference numeral CM 1) generated between the shield conductor 112 and the center conductor 111 can be ignored, and the parasitic capacitance appears to be eliminated.

As shown in fig. 1B, the center conductor 111 and the shield conductor 112 of the cable 110 may be directly connected without a buffer.

When the parasitic capacitance of the cable 110 is eliminated, no current flows through the path of the route RT2 in fig. 5 when the test voltage is applied between the patterns. That is, compared with the conventional system of fig. 5, the current value flowing between the circuit patterns during inspection can be detected with higher accuracy.

(embodiment 2)

An insulation inspection system 1A according to embodiment 2 will be described. Fig. 2A, 2B, and 2C are block diagrams showing a configuration example of the insulation inspection system 1A according to embodiment 2. In the insulation inspection system 1, the parasitic capacitance of the cable 120 in the existing type inspection device JS1 is made to appear to be eliminated.

As shown in fig. 2A, the insulation inspection system 1A includes an inspection device 10A and a printed substrate 30. The inspection apparatus 10A includes a voltage source VDD, an ammeter a1, a resistor R1, a voltmeter V, a cable 110, a cable 120, a virtual ground circuit 130, an ammeter a20, and a determination unit 150. The elements of the voltage source VDD, the ammeter a1, the resistor R1, the voltmeter V, and the cable 110 are the same as those given the same reference numerals in the conventional inspection device JS 1. Therefore, the description thereof is omitted. The ammeter a20 is shown in fig. 2A as a graph different from the ammeter a2 of fig. 5, but has the same function as the ammeter a2, and detects a current flowing on the low potential side in the inspection apparatus 10A.

In the present embodiment, the center conductor 121 of the cable 120 is connected to the virtual ground circuit 130. The virtual ground circuit 130 is a negative feedback circuit configured using an operational amplifier, and functions to equalize the potential of the input terminal of the operational amplifier. In the virtual ground circuit 130, the non-inverting input terminal (+) of the operational amplifier is connected to the ground terminal GND. Thereby, the center conductor 121 is maintained at the same potential as the ground GND. Here, the virtual ground circuit 130 is an example of the "eliminating section".

Thereby, the potential of the central conductor 121 and the potential of the shield conductor 122 become the same potential. Therefore, a current due to a potential difference between the potential of the center conductor 121 and the potential of the shield conductor 122 does not flow. Therefore, the parasitic capacitance (capacitance indicated by reference numeral CM 2) generated between the center conductor 121 and the shield conductor 122 can be ignored, and the parasitic capacitance appears to be eliminated.

When the parasitic capacitance of the cable 120 is eliminated, no current flows through the path of the route RT3 in fig. 5 when the inspection voltage is applied between the patterns. That is, compared with the conventional system of fig. 5, the current value flowing between the circuit patterns during inspection can be detected with higher accuracy.

In addition, the connection unit 100 shown in fig. 1 may be provided in the insulation inspection system 1A. That is, insulation inspection system 1A may have a configuration including both connection unit 100 for eliminating the parasitic capacitance of cable 110 and virtual ground circuit 130 for eliminating the parasitic capacitance of cable 120.

As shown in fig. 2B, a connection unit 100-1 similar to the connection unit 100 of embodiment 1 may be provided on the low potential side instead of the virtual ground circuit 130 in order to visually eliminate the parasitic capacitance of the cable 120. That is, a connection portion is provided to connect the center conductor 121 and the shield conductor 122 via the buffer B. This connecting portion 100-1 is also an example of the "eliminating portion".

As shown in fig. 2C, the center conductor 121 and the shield conductor 122 may be directly connected without a buffer in order to visually eliminate the parasitic capacitance of the cable 120.

(embodiment 3)

The insulation inspection system 2 according to embodiment 3 will be described. Fig. 3A and 3B are block diagrams showing a configuration example of the insulation inspection system 2 according to embodiment 3. In insulation inspection system 2, the parasitic capacitance of cable 210 in existing type inspection device JS2 was made to appear to be eliminated.

As shown in fig. 3A, the insulation inspection system 2 includes an inspection device 20 and a printed substrate 30. The inspection apparatus 20 includes a voltage source VDD, an ammeter A3, a resistor R2, a voltmeter V, a connection unit 200, a buffer B, a cable 210, an ammeter a4, and a determination unit 250. The elements of the voltage source VDD, the ammeter a3, the resistor R2, the voltmeter V, and the judgment unit 250 are the same as those given the same reference numerals in the conventional inspection device JS 2. Therefore, the description thereof is omitted.

In the present embodiment, the high-potential-side center conductor 211 and the shield conductor 213 of the cable 210 are connected to each other through the connection unit 200 via the buffer B. That is, the connection portion 200 connects the high potential side center conductor 211 and the shield conductor 213. Here, the connection portion 200 is an example of the "cancellation portion".

Thereby, the potential of the high potential side center conductor 211 and the potential of the shield conductor 213 become the same potential. Therefore, a current caused by a potential difference between the potential of the high potential side center conductor 211 and the potential of the shield conductor 213 does not flow. Therefore, the parasitic capacitance (capacitance indicated by the reference numeral CM 3) generated between the high potential side center conductor 211 and the shield conductor 213 can be ignored, and the parasitic capacitance appears to be eliminated.

As shown in fig. 3B, the center conductor 211 and the shield conductor 213 of the cable 210 may be directly connected without a buffer.

When the parasitic capacitance of cable 210 is eliminated, no current flows through the path of route RT11 in fig. 6 when the inspection voltage is applied between the patterns. That is, compared with the conventional system of fig. 6, the current value flowing between the circuit patterns during inspection can be detected with higher accuracy.

(embodiment 4)

An insulation inspection system 2A according to embodiment 4 will be described. Fig. 4A, 4B, and 4C are block diagrams showing a configuration example of the insulation inspection system 2A according to embodiment 4. In insulation inspection system 2A, the parasitic capacitance of cable 210 in existing type inspection device JS2 is made to appear to be eliminated.

As shown in fig. 4A, the insulation inspection system 2A includes an inspection device 20A and a printed substrate 30. Inspection apparatus 20A includes voltage source VDD, ammeter A3, resistor R2, voltmeter V, cable 210, virtual ground circuit 230, and ammeter A40. The elements of the voltage source VDD, the ammeter a3, the resistor R2, and the voltmeter V are the same as those given the same reference numerals in the conventional inspection device JS 2. Therefore, the description thereof is omitted. The ammeter a40 is shown in fig. 4A by a graph different from the ammeter a4 of fig. 6, but has the same function as the ammeter a4, and detects a current flowing on the low potential side in the inspection apparatus 20A.

In the present embodiment, the low-potential-side center conductor 212 of the cable 210 is connected to the virtual ground circuit 230. The virtual ground circuit 230 is the same as the virtual ground circuit 130 of the inspection apparatus 10A. Therefore, the description thereof is omitted. In the virtual ground circuit 230, the non-inverting input terminal (+) of the operational amplifier is connected to the ground terminal GND. Thereby, the low-potential center conductor 212 is maintained at the same potential as the ground GND. Here, the virtual ground circuit 230 is an example of the "eliminating section".

Thereby, the potential of the low-potential center conductor 212 becomes the same potential as the potential of the shield conductor 213. Therefore, a current due to a potential difference between the potential of the low-potential center conductor 212 and the potential of the shield conductor 213 does not flow. Therefore, a parasitic capacitance (capacitance indicated by reference numeral CM 4) generated between the low potential side center conductor 212 and the shield conductor 213 can be ignored, and the parasitic capacitance appears to be eliminated.

When the parasitic capacitance of cable 210 is eliminated, no current flows through the path of route RT12 in fig. 6 when the inspection voltage is applied between the patterns. That is, compared with the conventional system of fig. 6, the current value flowing between the circuit patterns during inspection can be detected with higher accuracy.

As shown in fig. 4B, a connection unit 200-1 similar to the connection unit 200 of embodiment 3 may be provided on the low potential side instead of the virtual ground circuit 230 in order to visually eliminate the parasitic capacitance of the cable 210. That is, a connection portion is provided to connect the low-potential side center conductor 212 and the shield conductor 213 via the buffer B. This connecting portion 200-1 is also an example of the "eliminating portion".

As shown in fig. 4C, the low-potential-side center conductor 212 and the shield conductor 213 may be directly connected without a buffer in order to visually eliminate the parasitic capacitance of the cable 210.

As described above, the inspection apparatus 10 according to embodiment 1 shown in fig. 1A includes the cable 110, the connection unit 100, and the determination unit 150. The cable 110 connects the printed circuit board 30 and the inspection apparatus 10. The cable 110 includes a shielded cable provided with a central conductor 111, an insulator insulating the central conductor 111 and a shield conductor 112 covering the insulator. In the case of the cable 110, the central conductor 111 is connected to the high potential side between the circuit patterns. The connection portion 100 connects the center conductor 111 and the shield conductor 112. The determination unit 150 determines whether or not the insulation state between the circuit patterns is good. The determination unit 150 applies an inspection voltage between the circuit patterns of the printed circuit board 30 via the cable 110. The determination unit 150 determines whether the insulation state is good or bad based on a voltage value between the circuit patterns obtained by applying the inspection voltage or a current value flowing between the circuit patterns.

Thus, in the inspection apparatus 10 according to embodiment 1, the central conductor 111 and the shield conductor 112 are connected. Thus, the parasitic capacitance of the cable 110 appears to be eliminated. This enables accurate detection of the current value flowing between the circuit patterns during inspection. Therefore, even when the parasitic capacitance exists in the cable 110, the insulation state between the circuit patterns can be checked with high accuracy.

Further, by eliminating the parasitic capacitance of the cable 110, the time until the applied voltage rises can be shortened. This can shorten the time required for the inspection, and can improve the efficiency of the inspection.

In addition, in the past, the frequency characteristics of the measurement path were deteriorated due to the parasitic capacitance of the cable 110. The measurement path here refers to a path through which a current flows by applying a voltage. The deterioration of the frequency characteristic here means that the high frequency characteristic is lowered and the time constant of the current flowing through the measurement path is increased. In contrast, in the present embodiment, the parasitic capacitance of the cable 110 is eliminated. Thereby, the frequency characteristic of the measurement path is improved. Here, the improvement of the frequency characteristic means that the high frequency characteristic is improved, the decrease of the change rate of the current flowing through the measurement path is suppressed, and the change rate of the current is faster than that in the conventional case. As a result, the high-frequency waveform of the spark current measured by the ammeter a1 or a ammeter a20 becomes sharp, and the accuracy of measuring the peak current can be improved.

Further, by eliminating the parasitic capacitance of the cable 110, it is possible to detect the peak of the spark waveform hidden by the parasitic capacitance in the conventional inspection. That is, conventionally, there is a spark waveform that is gentle due to parasitic capacitance and hidden because a peak value is not detected. In the present embodiment, by eliminating the parasitic capacitance of the cable 110, the rise of the waveform becomes sharper than before, and the peak value which has been hidden in the past can be detected.

The inspection apparatus 10A according to embodiment 2 shown in fig. 2A includes a cable 120, a virtual ground 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 provided with a center conductor 121, an insulator covering the center conductor 121 with an insulating film, and a shield conductor 122 covering the insulator. In the case of the cable 120, the central conductor 121 is connected to the low potential side between the circuit patterns. The shield conductor 122 is grounded. The virtual ground circuit 130 is connected to the center conductor 121. Thus, in the inspection apparatus 10A of embodiment 2, the parasitic capacitance of the cable 120 seems to be eliminated. Therefore, the same effects as those described above are achieved.

The inspection apparatus 20 according to embodiment 3 shown in fig. 3A includes a cable 210, a connection unit 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 provided with a high-potential side center conductor 211, a low-potential side center conductor 212, an insulator, and a shield conductor 213. The insulator is an insulating coating for each of the high-potential side central conductor 211 and the low-potential side central conductor 212. The shield conductor 213 covers the insulator. The high potential side center conductor 211 is connected to the high potential side between the circuit patterns. The low-potential-side center conductor 212 is connected to the low potential side between the circuit patterns. The connection portion 200 connects the high potential side center conductor 211 and the shield conductor 213. Thus, in inspection apparatus 20 according to embodiment 3, the parasitic capacitance of cable 210 is apparently eliminated. Therefore, the same effects as those described above are achieved.

The inspection apparatus 20A according to embodiment 4 shown in fig. 4A includes a cable 210, a virtual ground circuit 230, and a determination unit 250. The high potential side center conductor 211 is connected to the high potential side between the circuit patterns. The low-potential-side center conductor 212 is connected to the low potential side between the circuit patterns. The shield conductor 213 is grounded. The virtual ground circuit 230 is connected to the low potential side center conductor 212. Thus, in inspection apparatus 20A of embodiment 4, the parasitic capacitance of cable 210 appears to be eliminated. Therefore, the same effects as those described above are achieved.

In addition, in the above-described embodiment, the expression "connected to the ground terminal GND (ground)" is used. The potential of the ground terminal GND (ground potential) at this time is not limited to the case where the potential represents the absolute potential 0 (V). That is, the ground potential includes a potential (intermediate potential) in the middle of the power supply of the circuit in the inspection apparatus. The intermediate potential is a potential between a potential on the high potential side and a potential on the low potential side in 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). The ground GND may have such an intermediate potential of 7.5(V), or may have an arbitrary potential between 15(V) on the high potential side and 0(V) on the low potential side.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments may be implemented in other various manners, and various omissions, substitutions, and changes may be made without departing from the spirit of the present invention. These embodiments and modifications are included in the scope and spirit of the invention, and are included in the scope of the invention described in the claims and the equivalents thereof.

Claims

1. An inspection apparatus, comprising:

a cable for connecting the printed circuit board to be inspected and the inspection device;

a cancellation section that cancels a parasitic capacitance of the cable; and

and a determination unit that determines whether or not the insulation state between the circuit patterns is good or not, or whether or not a spark occurs between the circuit patterns, based on a voltage value between the circuit patterns obtained by applying an inspection voltage between the circuit patterns of the printed circuit board via the cable, or a current value flowing between the circuit patterns.

2. The inspection device of claim 1,

the cable includes a shielded cable provided with a first central conductor, an insulator covering the first central conductor with an insulating film, and a first shield conductor covering the insulator, the first central conductor being connected to a high potential side between the circuit patterns,

the eliminating portion includes a first connecting portion that makes the first center conductor and the first shield conductor equipotential.

3. The inspection apparatus of claim 2,

the first connecting portion connects the first center conductor and the first shield conductor.

4. The inspection apparatus according to any one of claims 1 to 3,

the cable includes a shielded cable provided with a second central conductor, an insulator covering the second central conductor in an insulating manner, and a second shield conductor covering the insulator, the second central conductor being connected to a low potential side between the circuit patterns, the second shield conductor being set to a ground potential,

the eliminating section includes a virtual ground circuit that virtually grounds the second center conductor.

5. The inspection apparatus according to any one of claims 1 to 3,

the cable includes a shielded cable provided with a second central conductor, an insulator covering the second central conductor with insulation, and a second shield conductor covering the insulator, the second central conductor being connected to a low potential side between the circuit patterns,

the eliminating portion includes a second connecting portion that makes the second center conductor and the second shield conductor equipotential.

6. The inspection device of claim 5,

the second connecting portion connects the second center conductor and the second shield conductor.

7. The inspection device of claim 1,

the cable includes a shielded cable provided with a high-potential side center conductor connected to a high-potential side between the circuit patterns, a low-potential side center conductor connected to a low-potential side between the circuit patterns, an insulator insulating-coated the high-potential side center conductor and the low-potential side center conductor, respectively, and a shield conductor covering the insulator,

the eliminating section is a connecting section for equalizing the potential of the high-potential-side center conductor and the shield conductor.

8. The inspection device of claim 7,

the eliminating section is a connecting section connecting the high potential side center conductor and the shield conductor.

9. The inspection device of claim 1,

the cable includes a shielded cable provided with a high-potential side center conductor connected to a high-potential side between the circuit patterns, a low-potential side center conductor connected to a low-potential side between the circuit patterns, an insulator insulating-coated the high-potential side center conductor and the low-potential side center conductor, respectively, and a shield conductor covering the insulator, the shield conductor being set to a ground potential,

the eliminating unit is a virtual ground circuit that virtually grounds the low potential side center conductor.

10. The inspection device of claim 1,

the eliminating section is a connecting section for equalizing the potential of the low potential side center conductor and the shield conductor.

11. The inspection device of claim 10,

the eliminating section is a connecting section that connects the low potential side center conductor and the shield conductor.