Detection device and detection method for testing the airtightness of sealed products

Abstract

A detection device (1) for testing the airtightness of a sealed product (2) comprises a sealed container (3) configured to contain at least one product (2) sealed in a nitrogen-containing atmosphere, a turbomolecular vacuum pump (7), an ionization gas gauge (5), a buffer volume (8) fluidly connected to the chamber (12) of the ionization gas gauge (5), a main shut-off valve (9) positioned between the sealed container (3) and the buffer volume (8) and configured to communicate with or shut off the buffer volume (8) from the sealed container (3), a conductance variable limiter (10) positioned between the inlet of the turbomolecular vacuum pump (7) and the buffer volume (8) having a variable opening, and a gas injection device (11) configured to inject a displacement gas other than nitrogen into the sealed container (3) containing the sealed product (2) at a variable flow rate.

Description

[Technical Field]

[0001] This invention relates to a detection device for testing the airtightness of sealed products such as pharmaceuticals and food products, or sealed products from the biotechnology industry, automotive industry, watchmaking industry, and cosmetics industry. Furthermore, the present invention also relates to a detection method implemented in the said detection device. [Background technology]

[0002] Certain products, such as sealed blister packs, sachets, vials, pouches, pharmaceutical or medical bags, and syringes, are sealed within their packaging under atmospheric pressure or vacuum to maintain their integrity. To ensure the complete airtightness of a seal, the airtightness of the sealed product is tested. The test must be highly sensitive to ensure that the seal provides good airtightness for various types of products, including those in dry or liquid states, flexible or rigid, opaque or transparent, etc. For the pharmaceutical and agrofood industries, this testing is essential to ensure the stability of drugs and food products by protecting them from moisture, air, and bacteria. There are several methods for testing the airtightness of a sealed product.

[0003] Patent Document 1 discloses an invention for a detection method for testing the airtightness of a sealed product. In this method, at least one product that has been pre-sealed in an air, nitrogen, or argon atmosphere is placed in a sealing container, the pressure inside the sealing container is reduced to a high vacuum using a turbomolecular vacuum pump, and while continuing to evacuate the sealing container to a high vacuum, the gas contained inside the sealing container is ionized, and the change in the concentration of at least one ionized gas species among nitrogen, oxygen, or argon in the gas volume contained in the sealed product is monitored inside the sealing container by analysis using emission spectroscopy or mass spectrometry. This detection method utilizes the fact that a gas atmosphere is trapped between the protected element and its packaging in a sealed product. Therefore, by inspecting the type of gas contained within this gas volume in the sealed container, it becomes possible to determine whether or not there is a leak from the sealed product. This eliminates the need to puncture and reseal the packaging to fill it with tracer gas. No special procedures are required between sealing products during manufacturing, leak testing, and selling leak-free sealed products. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] EP2875328B1 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, in certain industries, a very high level of sensitivity is required, especially to detect small leaks, and in the pharmaceutical industry in particular, to ensure a sterility threshold of less than 0.5 μm, i.e., 4.10 -5 mbar.l / s, or 4.10 -6 Pa.m 3 / s, or less than 0.2 μm, i.e., 6.10 -6 mbar.l / s, or 6.10 -7 Pa.m 3 The sensitivity to leakage in / s is required. Therefore, reducing the background noise of the test method is essential to obtain sufficient sensitivity. When the gas species being monitored for changes within a sealed container is nitrogen, the measured nitrogen signal may originate from leaks from the sealed product to be detected, but it may also originate from gas leaks through walls, particularly the walls of the sealed container, the walls of the sealed product, and even the walls of the detector chamber and vacuum line (due to intermittent communication with the sealed container at intermediate pressure). This background noise can be reduced by waiting for an extended period at the maximum exhaust volume, known as the ultimate vacuum. However, at the ultimate vacuum, the backflow of gas through the turbomolecular vacuum pump creates another source of parasitic nitrogen background noise.

[0006] Therefore, in order to achieve high-sensitivity detection, it is desirable to reduce nitrogen background noise that may be generated by degassing of the wall surface or backflow through the vacuum pump. However, below very low pressures, it is no longer possible to maintain an ignition plasma in the detector chamber for a sufficiently long time to perform a leak test. [Means for solving the problem]

[0007] The object of the present invention is to overcome, at least partially, this drawback by proposing an apparatus and method for highly sensitively detecting leaks from products sealed under a nitrogen-containing atmosphere, particularly in order to meet pharmaceutical standards.

[0008] For this purpose, the subject of the present invention is a detection device for checking the leak-proof properties of a sealed product, and this detection device is A sealed container configured to contain at least one product sealed under a nitrogen-containing atmosphere, a turbomolecular vacuum pump, and an ionization gas gauge, This detection device further, The buffer volume fluidly connected to the chamber of the ionized gas gauge, A main shut-off valve is interposed between the sealed container and the buffer volume and configured to either connect the buffer volume to the sealed container or to shut it off from the sealed container. A conductance variable limiting unit is disposed between the inlet of the turbomolecular vacuum pump and the buffer volume section, wherein the conductance variable limiting unit has a variable opening. The sealed container containing the sealed product is equipped with a gas injection device that injects a displacement gas different from nitrogen at a variable flow rate.

[0009] According to the present invention, by injecting a substitution gas into an enclosure by combining a turbo molecular vacuum pump and a variable conductance restricting part at its intake port, it becomes possible to adjust the pressure inside the enclosure, and thus the pressure inside the chamber of an ionization gauge, and to achieve a test pressure compatible with the generation and maintenance of plasma. The resulting pressure is the lowest pressure possible for ignition and maintenance of the plasma, enabling highly sensitive testing. Furthermore, by continuously injecting the substitution gas into the enclosure and directing the flow towards the discharge port of the turbo molecular vacuum pump, it is possible to prevent nitrogen from flowing back into the enclosure through the turbo molecular vacuum pump. The variable conductance restricting part makes it possible to increase the pressure by reducing the pumping flow rate while maintaining the high compression ratio of the turbo molecular vacuum pump, and also to prevent the backflow of gas species passing through the turbo molecular vacuum pump. Also, this makes it possible to reduce the amount of substitution gas injected during the test and avoid the nitrogen signal being overwritten by the substitution gas signal. Furthermore, by making the conductance of the restricting part variable, it becomes possible to increase the conductance and rapidly evacuate the enclosure from atmospheric pressure.

[0010] The detection device can also have one or more of the features described below, either alone or in combination. The detection device may include a control unit. The control unit can be configured to control the variable aperture of the variable conductance restricting part according to the control parameters of the ionization gauge in order to ignite or maintain the plasma in the chamber. The control unit can be configured to control the flow rate of the gas injection device according to the control parameters of the ionization gauge in order to ignite or maintain the plasma in the chamber. The variable conductance restricting part includes, for example, a diaphragm. The control parameter of the ionization gauge is, for example, the voltage of the generator of the plasma generator of the ionization gauge.

[0011] In an exemplary embodiment of the present invention, the ionization gauge a chamber, a plasma generator configured to generate plasma in the chamber, a emission spectrometer, and an optical window that enables the light emitted from the plasma to be analyzed by the emission spectrometer. In an exemplary embodiment of the present invention, the ionization gauge a cathode having a cylindrical wall connected to at least one disk having a central hole and at least two peripheral holes, a linear anode disposed at the center of the cathode and passing through the disk of the cathode, at least one toroidal magnet surrounding the chamber, and [[ID=2I]] a plasma generator having a generator connected to the cathode and the anode. This detection device includes a calibrated leak connected to the enclosure, a capillary and a main shut-off valve, and the capillary and the main shut-off valve are interposed between the nitrogen dispenser and the enclosure.

[0012] A further subject of the present invention is a detection method for checking the leak prevention of a product sealed in the detection device as described above, including the following steps. In the first step, at least one product pre-sealed under a nitrogen-containing atmosphere is placed in the enclosure, In the second step, the main shut-off valve is opened to communicate the enclosure with a buffer space under vacuum, In the third step, a substitution gas different from nitrogen is continuously injected into the enclosure, and while the high vacuum pump in the enclosure continues, the gas contained in the enclosure is ionized by the ionization gauge, and the change in the nitrogen concentration in the enclosure is monitored through emission spectroscopic analysis to identify the presence of a leak from the sealed product. The opening of the variable conductance limiter and the flow rate of the gas injection device are controlled to generate and maintain an ignition plasma within the chamber of the ionization gas gauge.

[0013] According to one exemplary embodiment of the present invention, in the second step, the opening of the variable conductance limiter is maximized and the flow rate of the gas injection device is minimized. According to one exemplary embodiment of the present invention, in the third step, as the pressure in the sealed container gradually decreases, the opening of the variable conductance limiter is first reduced before increasing the flow rate of the gas injector in order to maintain the ignition plasma. This detection method may include a fourth step of closing the main shut-off valve until atmospheric pressure is restored inside the sealed container while the displacement gas continues to be injected. Alternatively, during the first step, a displacement gas can be injected into the sealed container to sweep the walls of the sealed container with the displacement gas. The substitution gas is selected from, for example, argon, xenon, helium, carbon dioxide, krypton, and neon.

[0014] According to one exemplary embodiment of the present invention, a calibration test is performed using an intact, sealed product contained within a sealed container, into which a known flow rate of nitrogen is injected via a calibrated leak of a detection device.

[0015] Further features and advantages of the present invention will become apparent from the following description, provided with reference to the accompanying drawings and as examples not to limit. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram of one embodiment of the detection device of the present invention for testing the airtightness of sealed products. [Figure 2A] Figure 1 is a schematic front view of the detection device with the variable opening of the conductance variable limiting section in its maximum opening state. [Figure 2B] This is a schematic front view similar to Figure 2A, with the variable opening partially closed. [Figure 3] This is a schematic cross-sectional view of a component of one exemplary embodiment of an ionization gas gauge for a detection device. [Figure 4] This figure shows the steps of the detection method implemented in the detection device. [Figure 5A] This figure shows an example of a spectrum obtained from a leak test of a sealed product without substitution gas. [Figure 5B] This figure shows an example of a spectrum obtained from a leak test of a product sealed using argon as the displacement gas. [Modes for carrying out the invention]

[0017] The following embodiments of the present invention are illustrative. While this specification refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment or that the features apply only to one embodiment. Other embodiments can also be provided by combining or substituting individual features of different embodiments. In each drawing, identical elements are given the same reference numerals.

[0018] Figure 1 is a schematic diagram of a detection device 1 for testing the leak-proof properties of a sealed product 2. Sealed product 2 is, for example, a sealed blister pack, sachet, vial, pouch, pharmaceutical or medical bag, syringe, etc., which may be a pharmaceutical or food product. The sealed product 2 may be a product of the biotechnology industry, the watchmaking industry, or the automotive industry. These products contain at least one element that needs to be protected from, for example, moisture, air, bacteria, etc., such as pharmaceuticals or food products. The element to be protected is in liquid or solid form. The product is sealed in packaging. Because the packaging remains sealed, access to the inside is impossible, and gas cannot enter or leave the packaging.

[0019] In the sealed product 2, a mixed gas containing nitrogen, such as nitrogen or air, is sealed between the protected element and its packaging. Therefore, the pressure within the gas volume contained in the sealed product 2 is constant. Depending on the form of the packaging, this is the atmospheric pressure, or in the case of a "vacuum" pack, a pressure below the atmospheric pressure. This may also serve as a reservoir in the event of overpressure in an airbag or other types. The detection device 1 includes an encapsulation container 3 configured to accommodate at least one product 2 sealed under a nitrogen-containing atmosphere, a pump unit 4, and an ionization gas gauge 5.

[0020] The encapsulation container 3 has a volume capable of accommodating one or more sealed products 2. This encapsulation container 3 has dimensions slightly larger than the volume of the sealed product 2 being tested, and in order to limit gas absorption by the surface of the encapsulation container 3 when the encapsulation container 3 is at atmospheric pressure for loading / unloading the sealed product 2 as much as possible. Thereby, gas leakage from the wall of the encapsulation container 3 under low pressure is suppressed, reducing the possibility of leading to an increase in background noise. Furthermore, by making the volume of the encapsulation container 3 slightly larger than the volume of the sealed product 2, the pressure inside the encapsulation container 3 can be reduced more quickly, improving the response time and measurement sensitivity. The measurement volume is equal to the volume of the encapsulation container 3 minus the volume of the sealed product 2. Thereby, gas leakage from the wall of the encapsulation container 3 under low pressure is suppressed, reducing the possibility of leading to an increase in background noise.

[0021] The pump unit 4 includes a roughing vacuum pump 6 and a turbo molecular vacuum pump 7 fluidly connected in series, and the inlet of the roughing vacuum pump 6 is fluidly connected to the outlet of the turbo molecular vacuum pump 7. The turbo molecular vacuum pump 7 has an ultimate vacuum, that is, without gas injection, of 10 -5 mbar (10 -3 Pa) or less, for example, 10 -5 mbar (10 -3Pa)~10 -7 millibar (10 -5 It is configured to provide a high vacuum of Pa) inside the sealed container 3.

[0022] The detection device 1 further includes a buffer volume 8, a main shut-off valve 9 positioned between the buffer volume 8 and the sealed container 3, a conductance variable limiter 10 positioned between the inlet of the turbomolecular vacuum pump 7 and the buffer volume 8, and a gas injection device 11 configured to inject a displacement gas different from nitrogen at a variable flow rate into the sealed container 3 containing the sealed product 2. The conductance variable limiting unit 10 has a variable opening that can reduce the conductance between the buffer volume 8 and the turbomolecular vacuum pump 7, i.e., the size of the gas passage between the turbomolecular vacuum pump 7 and the buffer volume 8, while simultaneously allowing the buffer volume 8 to be continuously pumped by the turbomolecular vacuum pump 7. The conductance variable limiting unit 10 is composed of, for example, a diaphragm. This diaphragm can have multiple degrees of closure, such as a fully open state (Figure 2A) or a partially closed state (Figure 2B). The size of its opening changes continuously, for example.

[0023] The main shut-off valve 9 is opened to connect the buffer volume 8 to the sealed container 3 and place the sealed container 3 under vacuum by the buffer volume 8. The main shut-off valve 9 is also closed to isolate the buffer volume 8 from the sealed container 3. In particular, with the main shut-off valve 9 closed, the sealed container 3 can be opened to atmospheric pressure for unloading / loading of the sealed product 2 to be tested, and at the same time, the pressure in the buffer volume 8 can be reduced by the turbomolecular vacuum pump 7. The buffer volume 8 is constantly kept under vacuum by the turbomolecular vacuum pump 7. Since the pressure within the buffer volume 8 does not rise to atmospheric pressure, gas absorption by its surface can be avoided. The buffer volume 8 is, for example, 0.5 dm³. 3 ~2dm 3 For example, 1dm 3 That is the case.

[0024] The displacement gas injection device 11 is configured to inject a displacement gas at a variable flow rate different from nitrogen into a sealed container 3 containing a sealed product 2, and for this purpose, it is equipped with, for example, a flow controller 25.

[0025] The displacement gas is injected into the sealed container 3 for the following purposes: to check for leaks from the sealed product 2 during the test, to return the sealed container 3 to atmospheric pressure if necessary, and to sweep the sealed container 3 to atmospheric pressure during the loading / unloading of the sealed product 2 being tested, as will be described later. Alternatively, a specific additional gas injection line is used for returning the sealed container 3 to atmospheric pressure and / or sweeping it at atmospheric pressure.

[0026] The displacement gas is a gas different from nitrogen to avoid confusion with the nitrogen contained in the sealed product 2. Examples of substitution gases include bargon. Argon has the advantage of facilitating spectral interpretation, particularly because its spectral lines are divergent from those of nitrogen. Furthermore, argon is a neutral gas, readily available, inexpensive, and facilitates plasma initiation. Other examples of substitution gases include xenon, helium, carbon dioxide, krypton, or neon. The substitution gas may also be a mixture of gases other than nitrogen.

[0027] As clearly shown in Figures 1 and 3, according to one exemplary embodiment of the present invention, the ionization gas gauge 5 comprises a chamber 12 fluidly connected to a buffer volume 8, a plasma generator 13 configured to generate plasma within the chamber 12, an emission spectrometer 14 configured to provide a spectrum from the light emitted by the plasma, and an optical window 15, such as a transparent observation window, that allows the light emitted by the plasma to be analyzed by the emission spectrometer 14. The chamber 12, connected to the buffer volume 8 by its open end, can be continuously placed under vacuum by this buffer volume 8.

[0028] According to one exemplary embodiment, the plasma generator 13 of the ionization gas gauge 5 comprises an anode 16 (+ electrode) and a cathode 17 (- electrode) connected to the positive and negative electrodes of the generator 21, respectively (see Figure 3). The cathode 17 comprises a cylindrical wall 17a connected to at least one disk 17b. This cylindrical wall 17a is connected, for example, to three disks along the axis of the cylindrical wall 17a, each disk having a central hole through which the anode 16 passes, and at least two peripheral holes, for example six peripheral holes, regularly distributed around this central hole. The linear anode 16 is positioned at the center of the cathode 17, is separated from the cathode 17, and penetrates the disk 17b of the cathode 17.

[0029] The generator 21 of the plasma generator 13 is configured to apply a high potential difference of, for example, 3000 volts or more between the anode 16 (positively charged) and the cathode 17 (negatively charged), thereby generating a radial electric field E. In practice, the generator 21 is supplied with a fixed current, for example, while the voltage is a variable control parameter, and in particular depends on the pressure in the chamber 12 of the ionization gas gauge 5.

[0030] This electric field E generates and accelerates an electron flow from the cathode 17 to the anode 16, thereby generating a plasma and enabling the excitation and ionization of gas molecules generated from the sealed container 3. To obtain a usable plasma, a magnetic field B with a constant intensity of approximately 100 mT is applied in a predetermined direction, and its magnetic field lines are perpendicular to the electric field E and parallel to the anode 16. The magnetic field B is generated by at least one permanent toric magnet 18 surrounding the chamber 12. The presence of the magnetic field B coupled with the electric field E can significantly enhance the excitation of plasma gas molecules.

[0031] In this way, by generating plasma in the chamber 12 using the plasma generator 13, the types of gas present in the sealed container 3 can be analyzed. The plasma generated above the gas species emits light generated from the de-excitation of characteristic molecules of the present gas. This light, after passing through the optical window 15, is collected by, for example, an optical collector system and spectroscopically analyzed by an emission spectrometer 14. The optical collector system and the emission spectrometer 14 are optically connected, for example, via an optical fiber 19, which transmits this light from the optical collector to the spectrometer 14 (see Figure 1).

[0032] In emission spectroscopy, charged molecules (ions) are separated according to the wavelength they emit. The amplitude of the peaks in the spectrum (or spectral lines) corresponds to the relative abundance of the molecular elements. The spectrometer 14 establishes the characteristic spectra of the gas species present in the chamber 12. The wavelengths of the optical spectral lines thus obtained indicate the characteristics of the gas species present in the sealed container 3 (see Figures 5A and 5B).

[0033] This detection method utilizes the fact that the sealed product 2 contains a nitrogen-containing gas atmosphere trapped between the protected element and its packaging. Therefore, by monitoring the emission of nitrogen, it is possible to identify the presence of leakage from the sealed product 2. Leaks are detected, for example, by comparing at least one nitrogen line in the obtained spectrum with the nitrogen line in the spectrum of a leak-free reference sealed product 2, or by observing the presence of nitrogen lines, specifically, for example, by comparing the amplitude of the nitrogen line in the obtained spectrum with a maximum amplitude threshold that must not be exceeded in order for the sealed product to be considered intact.

[0034] The detection device 1 may include a calibration leak 22 connected to the sealed container 3 (see Figure 1). “Calibration leak” is understood to mean a leak with known characteristics. This calibration leak can be used to obtain the spectrum of a reference sealed product 2. To this end, a calibration test is performed using an intact product 2 sealed in a sealed container 3 into which nitrogen of a known flow rate is injected via a calibration leak 22.

[0035] According to one embodiment, the calibration leak 22 comprises a capillary 23 and a calibration leak shutoff valve 24 interposed between the nitrogen dispenser and the sealed container 3. The capillary 23 is capable of supplying a known and constant flow rate of nitrogen. The intact, sealed product 2 contained within the sealed container 3 during measurement allows a degassing source from the walls of the sealed product 2 to be added to the reference signal. The detection device 1 includes a control unit 20, such as a computer, automaton, and controller, connected to an emission spectrometer 14. The device receives signals from the emission spectrometer 14 representing changes in the ionized gas species in the chamber 12 and identifies whether characteristic wavelengths of nitrogen are present in the spectrum to identify leaks.

[0036] According to one exemplary embodiment, the control unit 20 is configured to control the variable opening of the conductance variable limiter 10 and / or the flow rate of the gas injection device 11, depending on the control parameters of the ionization gas gauge 5, in order to ignite or maintain the plasma in the chamber 12. Examples of control parameters for the ionization gas gauge 5 include the voltage of the generator of the plasma generator 13. The control unit 20 can also be configured to control the shut-off valve 24 for the calibration leak 22, if necessary.

[0037] During operation, the detection method 100 for testing the airtightness of a sealed product 2 inside the detection device 1 includes the following steps (see Figure 4). Initially, the main shut-off valve 9 is closed, and the sealed container 3 is isolated from the buffer volume 8. The buffer volume 8 is placed under vacuum by the turbomolecular vacuum pump 7, and its discharge port is maintained under rough vacuum by the rough vacuum pump 6.

[0038] In the first step 101, at least one product 2, which has been previously sealed in a nitrogen-containing atmosphere, for example, in an air atmosphere or a nitrogen atmosphere, is placed inside the sealing container 3. This first step 101 is performed at the pressure of the atmosphere outside the sealing container 3, for example, atmospheric pressure.

[0039] According to one embodiment, in the first step 101, a displacement gas is injected into the sealed container 3 in order to sweep the walls of the sealed container 3 with the displacement gas. By sweeping the walls of the sealed container 3 with the displacement gas while the sealed container 3 is open for unloading / loading the sealed product 2, it is possible to prevent the walls of the sealed container 3 from being filled with gas species generated from the surrounding air, thereby preventing an increase in background noise when the sealed container 3 is placed under vacuum. The sealed container 3 is then closed.

[0040] In the second step 102, the main shut-off valve 9 is opened, and the sealed container 3 communicates with the vacuum-state buffer volume 8, thereby reducing the pressure inside the sealed container 3 and the chamber 12 of the ionization gas gauge 5. The opening of the conductance variable limiter 10 is, for example, at its maximum, and the flow rate of the gas injection device 11 is, for example, at its minimum. The resulting high vacuum (or test pressure) is, for example, 10 -2 mbar (1 Pa) to 10 -7 mbar(10 -5 It is between Pa).

[0041] The conductance variable limiter 10 allows for increasing the pumping flow rate for various degassing rates of the sealed product in order to quickly obtain the test pressure inside the sealed container 3 during the first step 101. Specifically, the variable conductance limiter 10 positioned before the turbomolecular vacuum pump 7 can increase the passage cross-sectional area and, consequently, the conductance. This allows the pressure to be reduced from atmospheric pressure as quickly as possible after loading the sealed product 2, and this maximum pumping can be maintained until degassing is complete. The degassing time can be adjusted according to the degassing rate of the sealed product 2. For example, in the case of sealed containers with a large amount of degassing volume, such as containers made of plastic material, this prevents degassing from taking several hours.

[0042] In the third step 103, a replacement gas different from nitrogen is injected by the replacement gas injection device 11, for example, at an initial flow rate of 10 -3 mbar·l / s, i.e., 10 -4 Pa·m 3 The gas is continuously injected into the sealed container 3 at a rate of / s. While maintaining high vacuum pumping within the sealed container 3, the gas contained within the sealed container 3 is ionized by the ionization gas gauge 5, and changes in nitrogen concentration within the sealed container 3 are monitored via emission spectroscopy analysis to identify any leaks from the sealed product 2.

[0043] The opening of the conductance variable limiter 10 and the flow rate of the gas injection device 11 are controlled to generate and maintain ignition plasma within the chamber 12 of the ionization gas gauge 5. By continuously injecting displacement gas into the sealed container 3 using the turbomolecular vacuum pump 7 and the conductance variable limiting unit 10 at its intake port, it becomes possible to adjust the gas pressure inside the sealed container 3, and consequently, inside the chamber 12 of the ionization gas gauge 5, thereby achieving a test pressure that is compatible with plasma generation and maintenance inside the chamber 12.

[0044] By continuously injecting the displacement gas into the sealed container 3, the flow can be directed towards the discharge port of the turbomolecular vacuum pump 7, thereby preventing nitrogen from flowing back into the sealed container 3 through the turbomolecular vacuum pump 7.

[0045] The variable conductance limiter 10 makes it possible to reduce the pumping flow rate while maintaining the high compressibility of the turbomolecular vacuum pump 7, and consequently, it also makes it possible to prevent backflow of the gas species passing through the turbomolecular vacuum pump 7. Furthermore, by reducing the pumping flow rate relative to the maximum pumping required to place it under vacuum, the amount of replacement gas injected to achieve the desired test pressure can be reduced. By reducing the amount of replacement gas injected, the nitrogen signal is no longer overwritten by the replacement gas signal. Specifically, the power required for the generator 21 of the plasma generator 13 is reduced, making it possible to visualize the nitrogen partial pressure signal. The pressure obtained in this way is the minimum pressure possible to maintain the plasma, and therefore high measurement sensitivity can be obtained.

[0046] In practice, for example, to maintain the ignition plasma, it is desirable to maintain a constant current. To achieve this, for example, as the pressure inside the sealed container 3 gradually decreases, the voltage of the generator 21 of the plasma generator 13 is first increased. When this voltage reaches its maximum value, for example 5000 volts, the opening of the conductance variable limiter 10 is first reduced, and then the flow rate of the gas injection device 11 is increased. This flow rate is, for example, 101 mbar.l / s, or 1 Pa.m. 3 It can be increased up to / s.

[0047] After performing the leak test, in step 4 104, for example, the main shut-off valve 9 is closed to return the inside of the sealed container 3 to atmospheric pressure while continuing to inject the replacement gas. The injected displacement gas can saturate the inner walls of the sealed container 3 and the inner walls of the chamber 12 of the ionization gas gauge 5, thereby reducing the adsorption rate of ambient air, particularly nitrogen, onto the walls. As a result, the time required for degassing between two measurements can be shortened, and consequently, the cycle time can be reduced.

[0048] The graphs shown in Figures 5A and 5B illustrate two examples of spectra obtained by emission spectroscopy measurements to check the leak-proofness of the packaging of sealed product 2 by monitoring the amplitude of the nitrogen line peaks contained in the sealing container 3 present within the sealed product 2.

[0049] In the spectrum of Figure 5B, argon is used as the substitution gas, and the amplitude of the monitored nitrogen spectral line (around 389 nm) is lower than that of the spectrum of Figure 5A, which does not contain the substitution gas. Therefore, nitrogen background noise can be reduced by using a displacement gas. Furthermore, in the spectrum of Figure 5B, the amplitude of the argon spectral line increases because the substitution gas is argon. However, since the argon line is far from the monitored nitrogen line, it does not interfere with the monitoring of the nitrogen line. Therefore, it will be understood that the detection device 1 enables highly sensitive detection of leaks, particularly from sealed products 2 that meet pharmaceutical standards. [Explanation of symbols]

[0050] 1. Detection device 2. Sealed products 3. Encapsulation container 4 Pump Unit 5. Ionization gas gauge 6. Roughing vacuum pump 7. Turbomolecular vacuum pump 8 Buffer volume 9 Main shut-off valve 10 Variable conductance limiting unit 11. Gas injection device 12 Chambers 13 Plasma Generator 14. Emission Spectrometer 15 Optical windows 16 Anodes 17 Cathode 18 Toric Magnets 19 Optical Fiber 20 Control Units 21 Generators 22. Calibration Leak 23 Capillaries 24 Calibration Leak Shut-off Valve 25 Flow Controller

Claims

1. A detection device (1) for testing the airtightness of a sealed product (2), A sealed container (3) configured to contain the product (2) sealed under at least one nitrogen-containing atmosphere, Turbomolecular vacuum pump (7), It is equipped with an ionization gas gauge (5), and further, The buffer volume (8) is fluidly connected to the chamber (12) of the ionized gas gauge (5), A main shut-off valve (9) is interposed between the sealing container (3) and the buffer volume (8), and is configured to either connect the buffer volume (8) to the sealing container (3) or to shut it off from the sealing container (3), A conductance variable limiting unit (10) having a variable opening is positioned between the inlet of the turbomolecular vacuum pump (7) and the buffer volume (8), A gas injection device (11) is provided for injecting a displacement gas at a variable flow rate different from nitrogen into the sealed container (3) containing the sealed product (2), A detection device characterized by comprising a control unit (20) configured to control the flow rate of the variable opening of the conductance variable limiting unit (10) and / or the gas injection device (11) in accordance with the control parameters of the ionization gas gauge (5) to ignite or maintain plasma in the chamber (12).

2. The detection device according to claim 1, characterized in that the control parameter of the ionization gas gauge (5) is the voltage of the generator of the plasma generator (13).

3. The detection device according to claim 1, characterized in that the conductance variable limiting unit (10) includes a diaphragm.

4. The ionization gas gauge (5) is Chamber (12) and A plasma generator (13) configured to generate plasma within the chamber (12), Emission spectrometer (14), The detection device according to claim 1, further comprising an optical window (15) that allows light emitted from the plasma to be analyzed by the emission spectrometer (14).

5. The plasma generator (13) A cathode (17) having a cylindrical wall (17a), the cylindrical wall (17a) being connected to at least one disk (17b) having a central hole and at least two peripheral holes, A linear anode (16) is positioned at the center of the cathode (17) and penetrates the disk (17b) of the cathode (17), At least one toric magnet (18) surrounds the chamber (12), The detection device according to claim 4, further comprising a generator (21) connected to the cathode (17) and the anode (16).

6. The detection device according to claim 1, wherein the detection device (1) comprises a calibration leak (22) connected to the sealed container (3), the sealed container (3) comprises a capillary (23) and a calibration leak shutoff valve (24), and the capillary (23) and the calibration leak shutoff valve (24) are interposed between a nitrogen dispenser and the sealed container (3).

7. A detection method (100) for testing the airtightness of a sealed product using a detection device (1) according to any one of claims 1 to 6, In the first step (101), at least one product (2) that has been pre-sealed in a nitrogen-containing atmosphere is placed inside the sealing container (3). In the second step (102), the main shut-off valve (9) is opened to connect the sealed container (3) to the buffer volume (8) under vacuum (102). A detection method characterized in that, in the third step (103), a substitution gas different from nitrogen is continuously injected into the sealed container (3), and while continuing high vacuum pumping in the sealed container (3), the gas contained in the sealed container (3) is ionized by the ionization gas gauge (5), changes in the nitrogen concentration in the sealed container (3) are monitored by emission spectroscopy analysis to identify the presence of leakage from the sealed product (2), and the opening of the conductance variable limiter (10) and the flow rate of the gas injection device (11) are controlled to generate and maintain an ignition plasma in the chamber (12) of the ionization gas gauge (5).

8. The detection method according to claim 7, characterized in that in the second step (102), the opening of the conductance variable limiting unit (10) is at its maximum and the flow rate of the gas injection device (11) is at its minimum.

9. The detection method according to claim 7, characterized in that, in the third step (103), as the pressure inside the sealed container (3) gradually decreases, the opening of the variable conductance limiter (10) is first reduced before increasing the flow rate of the gas injection device (11) in order to maintain the ignition plasma.

10. The detection method (100) according to claim 7, characterized in that in the fourth step (104), the displacement gas is continued to be injected and the main shut-off valve (9) is closed so that the pressure inside the sealed container (3) returns to atmospheric pressure.

11. The detection method according to claim 7, characterized in that, during the first step (101), the displacement gas is injected into the sealed container (3) and the wall surface of the sealed container (3) is swept with the displacement gas.

12. The detection method according to claim 7, characterized in that the substitution gas is selected from argon, xenon, helium, carbon dioxide, krypton, and neon.

13. The detection method according to claim 7, characterized in that the substitution gas is selected from argon, xenon, helium, carbon dioxide, krypton, and neon.

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