JP2010066012A - Method for inspecting leakage of sealed vessel and apparatus for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To apply a high voltage to an insulative sealed vessel having a conductive content, and to rapidly and accurately determine whether a leakage exists. <P>SOLUTION: In a method for inspecting the leakage of the sealed vessel, the high voltage is applied to a to-be-inspected object 12 for sealing the conductive content. A received signal as a current flowing in the to-be-inspected object 12 is A/D converted. It determines whether the leakage exists or not. After the A/D conversion, a minimum value filtering process is implemented so as to remove a discharge noise. It determines whether the leakage exists, based on the received signal after the minimum value filtering process and a preset threshold value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In particular, the present invention relates to a sealed container leak inspection method and apparatus using a high voltage.

In general, liquid pharmaceuticals, foods, and the like are stored or distributed in a state of being enclosed in a container such as a synthetic resin pack, a plastic bottle, or a glass ampoule.
When such pharmaceuticals and foods are manufactured, they are manufactured on a manufacturing line maintained at a predetermined cleanliness so that foreign substances are not mixed into the container and contaminated. And the container with which the pharmaceutical and the food were sealed is subjected to a leak inspection on the production line after being sealed. The leak (pinhole) inspection is for inspecting whether there is a defect such as a pinhole or a crack that causes a leak in a container sealed with a pack or a glass ampule.

  As an example, a glass ampoule or the like is sealed by being heated with a burner after being filled with internal liquid. At this time, distortion may occur in the glass during the cooling process, cracks, pinholes, etc. may occur, causing leakage. In addition, cracks may occur even during conveyance on the production line.

  FIG. 10 is a diagram showing a schematic configuration of a conventional leak inspection apparatus. FIG. 10A shows a leak inspection apparatus using an analog amplifier, and FIG. 10B is a schematic configuration diagram of the leak inspection apparatus including an integration amplifier and an A / D converter.

  First, as shown in (1), the leak inspection apparatus 1 applies a high voltage to the inspection object 4 by the power supply means 2 and the transformer 3. Then, the current flowing through the inspection object 4 is measured by the current detection resistor 5, and the detected signal is passed through the analog amplifier 6 at the subsequent stage. The analog amplifier 6 removes high frequency discharge noise. A determination unit 7 such as a comparator compares a predetermined reference voltage value with the received signal to determine whether the product is a leaked product.

In addition, the leak inspection apparatus 1A including the integration amplifier and the A / D converter as shown in (2) applies a high voltage to the inspection object 4 as shown in (1), and then the current detection resistor 5 Measure the current flowing through the object under test. Then, the detected signal is passed through an integration amplifier 8 at the subsequent stage to perform integration processing. Then, after A / D conversion is performed by the A / D converter 9, the determination unit 7 determines the result by comparing with the comparison value. An apparatus disclosed in Patent Document 1 is disclosed as a leak inspection apparatus including such an A / D converter.
JP 2002-372509 A

  FIG. 11 is a diagram showing signal waveforms of an inspection apparatus using an analog amplifier. FIG. 2A shows a signal waveform of a non-defective sample, and FIG. 2B shows a signal waveform of a sample having a pinhole (defective product). The vertical axis indicates voltage (V), and the horizontal axis indicates time (s) (the same applies to the following signal waveform graphs). As shown in (1), in the case of a non-defective sample, there is usually a gap between the high-voltage electrode and the object to be inspected, and a signal (discharge noise) in which the discharge current flowing through this gap is detected is detected. Is done. In addition, as shown in (2), in the case of a defective product, a received signal derived from a pinhole, that is, a pinhole signal (discharge signal) is adjacent to a good product discharge noise and has a voltage value higher than that of a good product discharge noise. The signal is small and wide. Thus, since the discharge current flowing through the ampoule has unnecessary discharge noise, it is difficult to distinguish between a good product and a defective product. Further, when the processing is performed by the analog amplifier and the determination unit, the level of the non-defective product and the defective product is small, so that it may be erroneously detected as a non-defective product depending on the threshold setting condition, and the determination unit cannot correctly determine.

  On the other hand, FIG. 12 is an explanatory view of a leak inspection apparatus using a conventional A / D converter. As shown in the figure, the object to be inspected moves in the direction of arrow A on a transport line having an electrode plate attached to the upper surface. The signal waveform at this time is that when a non-defective product passes through the entrance, center, and exit of the electrode plate, the center is the maximum. The signal is lower than the good product. For this reason, when integration processing is performed on the entire received signal, there is a problem in that a small discharge signal is erased near the entrance or exit that is smaller than the center of the signal waveform and cannot be determined correctly.

  In order to improve the above-described problems of the prior art, an object of the present invention is to provide a sealed container leak inspection method and apparatus capable of quickly and accurately determining the presence or absence of a leak when a high voltage is applied to the sealed container.

  According to the sealed container leak inspection method of the present invention, a high voltage is applied to an object to be inspected in which conductive contents are sealed, and a received signal of a current flowing through the object to be inspected is A / D converted to determine whether there is a leak. In the leak check method for the sealed container for performing the determination, after the A / D conversion, the minimum value filtering process for removing the discharge noise and extracting the minimum reception signal is performed, and the reception signal after the minimum value filtering process is performed. It is characterized in that the presence or absence of a leak is determined based on a predetermined threshold value. As a result, non-defective discharge noise can be removed by the minimum value filter, and a leak signal can be easily extracted and emphasized. Therefore, the leak signal can be detected quickly and accurately.

  Further, in the sealed container leakage inspection method of the present invention, after the minimum value filtering process, the difference between the current reception signal and the reception signal before a predetermined period is taken, and the reception signal obtained by the difference is determined in advance. It is characterized in that the presence or absence of a leak is determined based on the threshold value. As a result, non-defective discharge noise can be removed by the minimum value filtering, and a leak signal can be extracted. Then, by taking the difference from the reception signal before the predetermined period, it is possible to remove the non-defective reception signal and display only the leak signal. Therefore, the leak signal can be detected quickly and accurately. Further, the S / N ratio can be improved, the difference between a good product and a defective product becomes clear, and the determination becomes more reliable.

  A leak inspection apparatus for a sealed container according to the present invention is an A / D converter that applies A / D conversion to a received signal of a current flowing through the inspection object by applying a high voltage to the inspection object sealed with conductive contents. And, based on a minimum value filter that extracts discharge noise of the signal subjected to A / D conversion processing and extracts the minimum received signal, a received signal after processing of the minimum value filter, and a predetermined threshold value, And a determination unit that determines whether or not there is a leak. As a result, non-defective discharge noise can be removed by the minimum value filter, and the leak signal can be easily enhanced. Therefore, the leak signal can be detected quickly and accurately.

  A leak inspection apparatus for a sealed container according to the present invention is an A / D converter that applies A / D conversion to a received signal of a current flowing through the inspection object by applying a high voltage to the inspection object sealed with conductive contents. A minimum value filter that extracts discharge noise of the signal subjected to the A / D conversion processing and extracts the minimum reception signal, a current reception signal processed by the minimum value filter, and reception before a predetermined period A difference processing unit that takes a difference from the signal; and a determination unit that determines whether or not there is a leak based on a received signal after processing by the difference processing unit and a predetermined threshold value. . As a result, non-defective discharge noise can be removed by the minimum value filtering, and a leak signal can be extracted. Then, by taking the difference from the reception signal before the predetermined period, it is possible to remove the non-defective reception signal and display only the leak signal. Therefore, the leak signal can be detected quickly and accurately. Further, the S / N ratio can be improved, the difference between a good product and a defective product becomes clear, and the determination becomes more reliable.

  According to the sealed container leak inspection method and apparatus of the present invention having the above-described configuration, the discharge noise of the sealed container in which the conductive contents are sealed can be easily removed to quickly and accurately determine the presence or absence of the leak. Can do.

Embodiments of a leak inspection method and apparatus for a sealed container according to the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram of a first embodiment of a leak inspection apparatus for a sealed container according to the present invention. As shown in the drawing, the sealed container leak inspection apparatus 10 (hereinafter simply referred to as a leak inspection apparatus) according to the first embodiment includes a measurement unit 20, a signal processing unit 40, and a determination unit 60.

The measurement unit 20 includes an AC power source 22, a transformer 24, a high voltage electrode 26, a low voltage electrode 28, and a current detection resistor 30.
The AC power source 22 is a high voltage power source applied to the inspection object 12. The transformer 24 is a transformer that converts low voltage to high voltage. Specifically, the transformer 24 of this embodiment boosts the voltage of the AC power supply 22.

  The inspected object 12 is an insulating sealed container filled with a conductive solution as a content, for example, an ampoule container made of glass or plastic. In the ampoule container, the ampoule is filled with a conductive solution, and then the tip opening at one end is sealed.

The high-voltage electrode 26 and the low-voltage electrode 28 are electrically connected to the above-described transformer 24, and are mounted on a production line on which the inspection object 12 is conveyed with a predetermined interval. The high voltage electrode 26 is an electrode attached so as to face the one end side where the tip opening of the object 12 to be sealed is sealed. On the other hand, the low-voltage electrode 28 is an electrode attached at a position facing the other end side (bottom portion) of the inspection object 12. In such a high voltage electrode 26 and a low voltage electrode 28, a current flows from the high voltage electrode 26 to the low voltage electrode 28, and a high voltage is applied to the inspection object 12 between the electrodes.
The current detection resistor 30 is attached between the low-voltage electrode 28 and the transformer 24, and the current flowing through the inspection object 12 is measured as a voltage via the resistor (R).

Next, the signal processing unit 40 includes a low-pass filter 42, an A / D converter 44, a storage unit 46, and a minimum value filter 48.
The low-pass filter (anti-aliasing filter) 42 is a filter that cuts a high-frequency signal from the received signal measured by the current detection resistor 30 and passes only a low-frequency signal. The low-pass filter 42 according to the present embodiment removes noise that does not affect the A / D converter 44 at the subsequent stage.

The A / D converter 44 converts the received signal from which noise has been removed by the low-pass filter 42 into a digital signal so that arithmetic processing described later can be performed easily and quickly.
The storage means (memory) 46 is a memory that temporarily stores the digitally converted signal.

  The minimum value filter 48 is a filter that performs minimum value processing. The minimum value process is an arithmetic process for calculating a minimum value from an arbitrarily selected continuous signal sequence. Specifically, the minimum value process is performed according to the following equation.

That is, the minimum value filter 48 has a received signal sequence that has been A / D converted as a (i) and a minimum filter output as s (i).
s (i) = min [a (i−j), a (i−1), a (i), a (i + 1), a (i + j)]
Meet the relationship. Note that j can be an arbitrarily determined integer between 1 and 10.

  The determination unit 60 receives a signal from the minimum value filter 48. The determination unit 60 arbitrarily sets a non-defective threshold value based on a non-defective received signal of the object to be inspected 12 and performs a pass / fail determination based on the threshold value and the received signal after the minimum value filter processing. .

  The leak inspection method (hereinafter simply referred to as “leak inspection method”) for the sealed container according to the first embodiment having the above-described configuration will be described below. FIG. 2 is a flowchart of the leak inspection method according to the first embodiment.

  The voltage of the AC power supply 22 is boosted by the transformer 24, and a high voltage is applied from the high voltage electrode 26 and the low voltage electrode 28 connected to the transformer 24 to the inspection object 12 conveyed on the conveyance line (step 100).

  At this time, a current flows from the high-voltage electrode 26 to the inspection object 12, and the current flows through the container of the inspection object 12 and the conductive contents to the low-voltage electrode 28. Then, a current reception signal having a magnitude proportional to the flowing AC current, that is, a voltage signal is measured in the current detection resistor 30 (step 102).

  The extracted voltage is sent to the low-pass filter 42 to perform a process of removing high-frequency noise and passing a low-frequency (filtering that does not affect the subsequent digital processing) (step 104).

  Next, the received signal is digitized by the A / D converter 44 (step 106). The digitally converted signal is temporarily stored in the storage means 46 (step 108).

The signal stored in the storage means 46 is subjected to minimum value processing by a minimum value filter 48. The reception signal in a continuous predetermined range stored in the storage means 46 is read out. Of these, when the A / D converted received signal sequence is a (i), and j = 2 as an example, the minimum filter output s (i) is:
s (i) = min [a (i-2), a (i-1), a (i), a (i + 1), a (i + 2)].

  Here, the leakage discharge signal has a signal width of 40 μs or more. On the other hand, the discharge noise is a pulse within 5 μs to 10 μs. Therefore, one sampling width of this embodiment may be at least 5 μs. Then, if j = 2 and 5 points, minimum value filter processing is performed with a signal width of 5 μs × 5 points = 25 μs.

  That is, the minimum value of a total of five received signals including two signals before and after the continuous received signal centering on the received signal a (i) is obtained (step 110). Next, the same processing is performed for the received signal sequence a (i + 1), and such processing is continuously performed.

  FIG. 3 is an explanatory diagram of signal waveforms of the leak inspection method according to the first embodiment. In the drawing, (A) and (B) respectively show a non-defective signal waveform and a leaked signal waveform of the inspection object 12. Further, (C) and (D) in the figure respectively show a non-defective product signal waveform and a leaked product signal waveform after the minimum value filter processing. As shown to (A), in the case of a good product, it discharges evenly at a low frequency. On the other hand, as shown in (B), in the case of a defective product, if there is a leak, the dielectric breakdown of the air accelerates, and a rapid increase in the low frequency part as shown by the arrow b is observed in the latter half of the peak of the low frequency waveform. It is done.

  In the present invention, when the minimum value processing is performed on the continuous received signal sequence, the discharge noise appearing in (A) and (B) is removed in (C) and (D), and in particular, in (D), the discharge signal is not generated. It is emphasized. This is detected as a continuous signal in which the discharge noise and the discharge signal are close to each other in the received signal, but the discharge noise with a high voltage value is eliminated by the minimum value filter, and the discharge signal with a small voltage value remains, and the portion is This is because it was extracted and emphasized.

  Finally, the determination unit 60 performs pass / fail determination based on the received signal after the minimum value filter processing and the good product threshold value determined in advance by the good product received signal. For example, the threshold value on the positive side of the non-defective waveform shown in (C) is set to 0.15 (V). Then, when this threshold is applied to the voltage waveform shown in (D), since there is a voltage value exceeding 0.15 (V), it is determined that the product has a leak. Thus, when the received signal is larger than the threshold value, it is determined that the inspection object is a defective product having a leak, and when the received signal is smaller than the threshold value, it is determined as a non-defective product (step 112).

Next, a second embodiment of the leak inspection apparatus of the present invention will be described. FIG. 4 is a schematic configuration diagram of a second embodiment of the leak inspection apparatus of the present invention.
The difference between the leak inspection apparatus 10A of the second embodiment and the leak inspection apparatus 10 of the first embodiment described above is that the period measuring means 50 is provided after the storage means 46, and the minimum value filter of the signal processing unit 40A. The difference processing means 52 and the second filter 56 are provided between 48 and the determination unit 60. Other configurations are the same as those of the leak inspection apparatus of the first embodiment, and the same reference numerals are given and detailed description is omitted.

  The period measuring means 50 of the signal processing unit 40A is attached to the subsequent stage of the storage means 46, and a signal from the storage means 46 is input. The period measuring unit 50 reads a continuous predetermined range of received signals stored in the storage unit 46 and measures the period from the signal waveform. Then, m sampling numbers in one cycle are obtained. Therefore, the number of samplings in the n period can be expressed as n × m.

Further, the difference processing means 52 of the signal processing unit 40A receives the signals of the minimum value filter 48 and the period measuring means 50. The difference processing means 52 includes a signal delay memory 53 in the previous stage and an adder 54 in the subsequent stage. The signal delay memory 53 is a memory that obtains and stores a received signal s ′ n cycles before from the sampling number n × m of n cycles, which is the cycle data of the cycle measuring means 50. Here, the received signal s ′ before n cycles can be expressed as s ′ (nm + i), where s (i) is the current received signal among the continuous predetermined range of received signals read from the storage means 46. The adder 54 takes the difference between the current reception signal s (i) and the reception signal s ′ (nm + i) before the arbitrarily set period. That is, the difference e (i) between the current received signal and the received signal n cycles before is e (i) = s (i) −s ′ (nm + i)
It becomes the relationship.

For example, a low-pass filter is used as the second filter 56. The second filter 56 receives a signal from the difference processing means 52 and removes high frequency noise.
A leak inspection method according to the second embodiment having the above configuration will be described below. FIG. 5 is a flowchart of the leak inspection method according to the second embodiment.

  The process from the measurement part 20 to the memory | storage means 46 in 2nd embodiment performs the process similar to 1st embodiment. That is, the voltage of the AC power supply 22 is boosted by the transformer 24, and a high voltage is applied from the high-voltage electrode 26 and the low-voltage electrode 28 connected to the transformer 24 to the inspection object 12 conveyed on the conveyance line (step 100).

  At this time, a current flows from the high voltage electrode 26 to the inspection object 12, and the current flows through the container of the inspection object 12 and the conductive contents to the low voltage current 28. Then, a current reception signal having a magnitude proportional to the flowing AC current, that is, a voltage signal is measured in the current detection resistor 30 (step 102).

  The extracted voltage is sent to the low-pass filter 42 to perform a process of removing high-frequency noise and passing a low-frequency (filtering that does not affect the subsequent digital processing) (step 104).

  Next, the received signal is digitized by the A / D converter 44 (step 106). The digitally converted signal is temporarily stored in the storage means 46 (step 108).

  Next, the period measurement means 50 measures the read cycle of the received signals in the continuous predetermined range stored in the storage means 46 (step 200). The period measuring means 50 measures the period from the signal waveform of the received signal in a continuous predetermined range and obtains m sampling numbers in one period. The number of samplings in the n period is n × m. Note that n can be any integer.

On the other hand, the signal stored in the storage means 46 is subjected to minimum value processing by a minimum value filter 48. The reception signal in a continuous predetermined range stored in the storage means 46 is read out. Among these, when the A / D converted received signal sequence is a (i), and j = 2 as an example, the minimum filter output s (i) is
min [a (i-2), a (i-1), a (i), a (i + 1), a (i + 2)],
The minimum value of a total of five received signals including two signals before and after the continuous received signal centering on the received signal a (i) is obtained (step 110). Next, the same processing is performed for the received signal sequence a (i + 1), and such processing is continuously performed.

The difference processing means 52 receives the signal after the minimum value filter processing of the minimum value filter 48 and the period data of the period measurement means 50. As an example, when obtaining the received signal s ′ three cycles before from the sampling number m obtained by the cycle measuring means 50 in one cycle, the current received signal among the received signals in the continuous predetermined range after the minimum value filter processing. Is s (i), the received signal s ′ three cycles before can be expressed as s ′ = (3m + i). In the signal delay memory 53, the reception signal s ′ three cycles before is temporarily recorded. Next, the adder 54 takes the difference between the current received signal s (i) and the received signal s ′ three cycles before stored in the signal delay memory 53. When the signal obtained from the difference is the signal e (i),
e (i) = s (i) -s ′ (3m + i)
(Step 202).

  FIG. 6 is an explanatory diagram of signal waveforms of the leak inspection method according to the second embodiment. In the figure, (A) shows the continuous signal of the non-defective product and the leaked product of the storage means 46, (B) shows the continuous signal of the good product and the leaked product after the minimum value filter processing, and (C) shows the non-defective product after the differential processing and The continuous signal of the leaked product is shown. As shown to (A), although the leak signal shown by the arrow c in the figure is detected, it is a signal smaller than the discharge noise of a good product. As shown in (B), when this continuous signal is subjected to minimum value processing, non-defective discharge noise is removed and only the leak signal is extracted and emphasized. Further, as shown in (C), when the difference process between the current continuous signal and the continuous signal n cycles before is performed, the non-defective signal is removed and only the discharge signal remains.

Further, the error noise of the signal after the difference processing is removed by the second filter 56 (step 204).
Finally, the determination unit 60 determines pass / fail based on the received signal after the difference process and a predetermined good product threshold. For example, when the received signal is larger than the threshold value, it is determined that the inspection object is a defective product having a leak, and when the received signal is smaller than the threshold value, it is determined as a non-defective product (step 206).

  Next, a leak inspection apparatus related to the present invention will be described. FIG. 7 is a diagram showing a schematic configuration of a leak inspection apparatus related to the present invention. As shown in the figure, a leak inspection apparatus 10B related to the present invention includes a measurement unit 20, a signal processing unit 40B, and a determination unit 60.

The measurement unit 20 includes an AC power source 22, a transformer 24, a high voltage electrode 26, a low voltage electrode 28, and a current detection resistor 30.
The AC power source 22 is a high voltage power source applied to the inspection object 12. The transformer 24 is a transformer that converts low voltage to high voltage. Specifically, the transformer 24 of this embodiment boosts the voltage of the AC power supply 22.

  The inspected object 12 is a glass or plastic ampoule container filled with a conductive solution as a content. In the ampoule container, the ampoule is filled with a conductive solution, and then the tip opening at one end is sealed.

  The high-voltage electrode 26 and the low-voltage electrode 28 are electrically connected to the above-described transformer 24, and are mounted on a production line on which the inspection object 12 is conveyed with a predetermined interval. The high voltage electrode 26 is an electrode attached so as to face the one end side where the tip opening of the object 12 to be sealed is sealed. On the other hand, the low-voltage electrode 28 is an electrode attached at a position facing the other end side (bottom portion) of the inspection object 12. In such a high voltage electrode 26 and low voltage electrode 28, a current flows from the high voltage electrode 26 to the low voltage electrode 28, and a high voltage is applied to the inspection object 12 between the electrodes.

The current detection resistor 30 is attached between the low-voltage electrode 28 and the transformer 24, and the current flowing through the inspection object 12 is measured as a voltage via the resistor (R).
Next, the signal processing unit 40B includes a low-pass filter 42, an A / D converter 44, a storage unit 46, a period measurement unit 50, a difference processing unit 52, and a second filter 56.

  The low-pass filter (anti-aliasing filter) 42 is a filter that cuts a high-frequency signal from the received signal measured by the current detection resistor 30 and passes only a low-frequency signal. The low-pass filter 42 according to the present embodiment removes noise that does not affect the A / D converter 44 at the subsequent stage.

The A / D converter 44 converts the received signal from which noise has been removed by the low-pass filter 42 into a digital signal so that arithmetic processing described later can be performed easily and quickly.
The storage means (memory) 46 is a memory that temporarily stores the digitally converted signal.

  The period measuring unit 50 is attached to the subsequent stage of the storage unit 46 and receives a signal from the storage unit 46. The period measuring unit 50 reads a continuous predetermined range of received signals stored in the storage unit 46 and measures the period from the signal waveform. Then, m sampling numbers in one cycle are obtained. Therefore, the number of samplings in the n period can be expressed as n × m.

Further, the difference processing means 52 receives the signals of the storage means 46 and the period measuring means 50. The difference processing means 52 includes a signal delay memory 53 in the previous stage and an adder 54 in the subsequent stage. The signal delay memory 53 is a memory that obtains and stores a received signal s ′ n cycles before from the sampling number n × m of n cycles, which is the cycle data of the cycle measuring means 50. Here, the received signal s ′ before n cycles can be expressed as s ′ (nm + i), where s (i) is the current received signal among the continuous predetermined range of received signals read from the storage means 46. The adder 54 takes the difference between the current reception signal s (i) and the reception signal s ′ (nm + i) before the arbitrarily set period. That is, the difference e (i) between the current received signal and the received signal n cycles before is e (i) = s (i) −s ′ (nm + i)
It becomes the relationship.

For example, a low-pass filter is used as the second filter 56. The second filter 56 receives a signal from the difference processing means 52 and removes high frequency noise.
The determination unit 60 receives the signal from the second filter 56. The determination unit 60 arbitrarily sets a threshold value for a non-defective product of the inspected object 12 in advance, and performs a pass / fail determination based on the threshold value and the received signal after difference processing.

  Thus, the leak inspection apparatus 10B related to the present invention is different from the leak inspection apparatus 10A according to the second embodiment in that the minimum value filter 48 is not provided.

The leak inspection method related to the present invention having the above configuration will be described below. FIG. 8 is a flowchart showing a leak inspection method related to the present invention.
The voltage of the AC power supply 22 is boosted by the transformer 24, and a high voltage is applied from the high voltage electrode 26 and the low voltage electrode 28 connected to the transformer 24 to the inspection object 12 conveyed on the conveyance line (step 100).

  At this time, a current flows from the high voltage electrode 26 to the inspection object 12, and the current flows through the container of the inspection object 12 and the conductive contents to the low voltage current 28. Then, a current reception signal having a magnitude proportional to the flowing AC current, that is, a voltage signal is measured in the current detection resistor 30 (step 102).

  The extracted voltage is sent to the low-pass filter 42 to perform a process of removing high-frequency noise and passing a low-frequency (filtering that does not affect the subsequent digital processing) (step 104).

  Next, the received signal is digitized by the A / D converter 44 (step 106). The digitally converted signal is temporarily stored in the storage means 46 (step 108).

  Next, the period measurement means 50 measures the read cycle of the received signals in the continuous predetermined range stored in the storage means 46 (step 200). The period measuring means 50 measures the period from the signal waveform of the received signal in a continuous predetermined range and obtains m sampling numbers in one period. The number of samplings in the n period is n × m. Note that n can be any integer.

The difference processing means 52 receives the received signal of the storage means 46 and the period data of the period measurement means 50. As an example, when obtaining the received signal s ′ three cycles before from the sampling number m obtained by the cycle measuring means 50 in one cycle, the current received signal among the received signals in the continuous predetermined range after the minimum value filter processing. Is s (i), the received signal s ′ three cycles before can be expressed as s ′ = (3m + i). In the signal delay memory 53, the reception signal s ′ three cycles before is temporarily recorded. Next, the adder 54 takes the difference between the current received signal s (i) and the received signal s ′ three cycles before stored in the signal delay memory 53. When the signal obtained from the difference is the signal e (i),
e (i) = s (i) -s ′ (3m + i)
(Step 300).

  FIG. 9 is an explanatory diagram of signal waveforms of the leak inspection method related to the present invention. In the figure, (A) shows the continuous signal of the non-defective product and the leaked product in the storage means 46, and (B) shows the continuous signal of the good product and the leaked product after the differential processing. As shown in FIG. 5A, in the figure, the first stage of the first part is a non-defective signal waveform, and the second stage of the broken line 1 is a leaky signal waveform. As shown in (B), when differential processing is performed between the current continuous signal and the continuous signal before n cycles, the front signal is removed and only the discharge signal is highlighted and displayed.

Further, the second filter 56 removes error noise of the signal after the difference processing (step 302).
Finally, the determination unit 60 determines pass / fail based on the received signal after the difference process and a predetermined good product threshold. For example, when the received signal is larger than the threshold value, it is determined that the inspection object is a defective product having a leak, and when the received signal is smaller than the threshold value, it is determined as a non-defective product (step 304).

  According to such a leak inspection method and apparatus for a sealed container, it is possible to quickly and accurately determine whether or not there is a leak in the container in which the conductive contents are sealed using a high voltage.

BRIEF DESCRIPTION OF THE DRAWINGS It is the structure schematic of 1st embodiment of the leak test | inspection apparatus of the sealed container of this invention. It is a figure which shows the flowchart of the leak test | inspection method of 1st embodiment. It is explanatory drawing of the leak test | inspection method of 1st embodiment. It is the structure schematic of 2nd embodiment of the leak test | inspection apparatus of this invention. It is a figure which shows the flowchart of the leak inspection method of 2nd embodiment. It is explanatory drawing of the leak test | inspection method of 2nd embodiment. 1 is a schematic configuration diagram of a leak inspection apparatus related to the present invention. It is a figure which shows the flowchart of the leak inspection method relevant to this invention. It is explanatory drawing of the leak test | inspection method relevant to this invention. It is a figure which shows the structure outline of the conventional leak test | inspection apparatus. It is a figure which shows the signal waveform of the leak test | inspection apparatus using the conventional analog amplifier. It is explanatory drawing of the leak inspection apparatus using the conventional A / D converter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ......... Leakage inspection apparatus, 2 ......... Power supply means, 3 ......... Transformer, 4 ......... Inspection object, 5 ...... Current detection resistor, 6 ......... Analog amplifier, 7 ......... Determination Means 8 ... Integration amplifier 9 ... A / D converter 10, 10A, 10B ... Leak inspection device 12 ... Inspected object 20 ... Measurement unit 22 ... AC power supply, 24 ......... Transformer, 26 ......... High voltage electrode, 28 ......... Low voltage electrode, 30 ......... Current detection resistor, 40, 40A, 40B ......... Signal processing unit, 42 ......... Low pass filter 44 ......... A / D converter 46 ......... Storage means 48 ......... Minimum value filter 50 ......... Period measurement means 52 ......... Difference processing means 53 ......... Signal delay memory, 54... Adder, 56... Second filter, 60.

Claims (4)

In a leak inspection method for a sealed container that applies a high voltage to an object to be inspected in which conductive contents are sealed and performs A / D conversion on a received signal of a current flowing through the object to be inspected to determine whether there is a leak,
After the A / D conversion, a minimum value filtering process for removing discharge noise and extracting the minimum received signal is performed.
A leak inspection method for a sealed container, wherein the presence or absence of a leak is determined based on a reception signal after the minimum value filter processing and a predetermined threshold value. After the minimum value filtering process,
Take the difference between the current received signal and the received signal before the predetermined period,
The method for inspecting a leak of a sealed container according to claim 1, wherein the presence or absence of a leak is determined based on a reception signal obtained from the difference and a predetermined threshold value. An A / D converter for applying a high voltage to the object to be inspected, in which the conductive contents are sealed, and A / D converting a received signal of a current flowing through the object;
A minimum value filter that removes discharge noise of the A / D converted signal and extracts the minimum received signal;
A determination unit configured to determine whether or not there is a leak based on a reception signal after processing of the minimum value filter and a predetermined threshold;
A leak inspection apparatus for a sealed container, comprising: An A / D converter for applying a high voltage to the object to be inspected, in which the conductive contents are sealed, and A / D converting a received signal of a current flowing through the object;
A minimum value filter that removes discharge noise of the A / D converted signal and extracts the minimum received signal;
Differential processing means for taking a difference between a current reception signal processed by the minimum value filter and a reception signal before a predetermined period;
A determination unit configured to determine whether or not there is a leak based on a reception signal after processing by the difference processing unit and a predetermined threshold;
A leak inspection apparatus for a sealed container, comprising:

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