Inspection device and inspection method

Abstract

The present invention provides an inspection device that can accurately inspect the airtightness of a sealed container even when the gas concentration of the target gas is not uniform in the headspace of the sealed container. [Solution] The system comprises a laser light generating unit 2 that generates laser light containing wavelengths absorbed by the target gas and irradiates the sealed container 10 with it; a laser light detection unit 3 that detects the laser light that has passed through the headspace 12 of the sealed container at each vertical height; and a signal processing unit 4 that calculates the gas concentration of the target gas at each vertical height from the detection signals output from the laser light detection unit at each vertical height, and determines the airtightness of the sealed container based on the average value of the gas concentration in the vertical direction.

Description

Technical Field

[0001] The present invention relates to an inspection apparatus and an inspection method.

Background Art

[0002] As an inspection apparatus for inspecting the airtightness of a sealed container such as a vial, the apparatus described in Patent Document 1 has been proposed. Patent Document 1 discloses a headspace analyzer, in which a laser light source and a beam detector are arranged to face each other with a sealed container conveyed by a conveyor sandwiched therebetween. The laser light source emits a laser beam adjusted to a wavelength absorbed by the target gas, and the beam detector detects the laser beam transmitted through the sealed container. The gas concentration of the target gas is calculated from the detection signal, and the airtightness of the sealed container is determined from the calculated gas concentration.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since gases have different densities depending on their types, the gas concentration inside the container varies depending on the height in the vertical direction (see FIG. 3). FIG. 3 shows a state in which a substance 11 such as a drug is stored in a sealed container 10, and a gas 13 with a high density and a gas 14 with a low density are enclosed in a headspace 12 above the substance 11. The gas 13 with a high density is mostly concentrated below the headspace 12, and the gas 14 with a low density is mostly concentrated above the headspace 12.

[0005] In other words, depending on the difference in density, the denser gas 13 is concentrated in the lower part of the headspace 12, and its concentration decreases as you move upwards. The less dense gas 14 is concentrated in the lower part of the headspace 12, and its concentration increases as you move upwards. When two types of gases, for example, nitrogen as the less dense gas 14 and carbon dioxide as the denser gas 13, are sealed in a sealed container 10, the concentration of carbon dioxide is not uniform in the vertical direction, being higher in the lower part of the headspace 12 than in the upper part, and the concentration of nitrogen is higher in the upper part of the headspace 12 than in the lower part. Therefore, even if the gas concentration of the target gas is measured with a small beam diameter as in the conventional method, only a portion of the headspace 12 of the sealed container 10 can be measured, resulting in low accuracy in measuring the gas concentration of the target gas and making it impossible to properly inspect the airtightness of the sealed container 10.

[0006] When measuring with a small beam diameter, qualitative testing (determining the presence or absence of leaks) is possible by changing the measurement position (vertical direction) of the sealed container to a position suitable for the density of the target gas, but quantitative testing (determining the amount of leakage) is not possible. Therefore, the airtightness of the sealed container cannot be accurately inspected. This is because only a portion of the headspace can be measured, making it impossible to know the total gas concentration inside the sealed container. Furthermore, even when measuring the entire headspace with a large beam diameter, only an average value across the entire headspace can be detected, resulting in low measurement accuracy when the gas concentration is unevenly distributed (e.g., high concentration in one area).

[0007] The present invention has been made in view of the above problems, and aims to provide an inspection device and inspection method that can accurately inspect the airtightness of a sealed container even when the gas concentration of the target gas in the headspace of the sealed container is not uniform in the vertical direction. [Means for solving the problem]

[0008] To achieve the above objective, the inspection apparatus according to the present invention is characterized by comprising: a laser light generating unit (2) that generates laser light containing a wavelength absorbed by the target gas and irradiates the sealed container (10); a laser light detection unit (3) that detects the laser light transmitted through the headspace (12) of the sealed container at each vertical height; and a signal processing unit (4) that calculates a state quantity indicating the state of the target gas at each vertical height from the detection signals output from the laser light detection unit at each vertical height, and determines the airtightness of the sealed container based on the vertical statistical values ​​of the state quantity.

[0009] As described above, the inspection device of the present invention uses a laser light detector to detect laser light transmitted through the headspace of a sealed container at each vertical height, and a signal processing unit calculates a state quantity (e.g., gas concentration) indicating the state of the target gas at each vertical height from the laser light detection signal. Based on the vertical statistical values ​​(e.g., average values) of the state quantities, the airtightness of the sealed container is determined. With this configuration, even if the state quantities indicating the state of the target gas in the headspace of the sealed container are not uniform in the vertical direction, the airtightness of the sealed container can be accurately inspected based on the vertical statistical values ​​of the state quantities.

[0010] Furthermore, in the inspection apparatus according to the present invention, the laser light generation unit further comprises a modulation signal generator (21) that generates a modulation signal, and generates the laser light that is frequency modulated based on the modulation signal, and the signal processing unit detects a signal component synchronized with a frequency n times the frequency of the modulation signal (n is an integer of 1 or more) from the detection signal for each vertical height, calculates the gas concentration of the target gas for each vertical height in the headspace based on each signal component, determines the average gas concentration in the vertical direction from the gas concentration of the target gas for each vertical height, and determines the airtightness of the sealed container based on the average gas concentration.

[0011] As described above, the laser light generation unit generates frequency-modulated laser light based on the modulation signal, and the signal processing unit locks in and detects signal components synchronized to a frequency n times the frequency of the modulation signal from the laser light detection signal for each vertical height. With this configuration, the inspection device of the present invention can accurately calculate the gas concentration of the target gas for each vertical height, and thus accurately determine the average gas concentration in the vertical direction. As a result, even if the gas concentration of the target gas in the headspace of the sealed container is not uniform in the vertical direction, the airtightness of the sealed container can be accurately determined.

[0012] Furthermore, in the inspection apparatus according to the present invention, the laser light generation unit further comprises a modulation signal generator (21) that generates a modulation signal, and generates the laser light that is frequency modulated based on the modulation signal, and the signal processing unit detects a signal component synchronized to twice the frequency of the modulation signal from the detection signal for each vertical height, calculates the gas concentration of the target gas for each vertical height in the headspace based on each signal component, determines the average gas concentration in the vertical direction from the gas concentration of the target gas for each vertical height, and determines the airtightness of the sealed container based on the average gas concentration.

[0013] With this configuration, the inspection device of the present invention can accurately calculate the gas concentration of the target gas for each vertical height, and thus accurately determine the average gas concentration in the vertical direction. As a result, even if the gas concentration of the target gas is not uniform in the vertical direction in the headspace of the sealed container, the airtightness of the sealed container can be accurately determined.

[0014] Furthermore, in the inspection apparatus according to the present invention, the laser light generation unit may include a laser light shaping unit (24) that shapes the laser light into a line beam-shaped laser light extending in the vertical direction and irradiates it toward the sealed container, and the laser light detection unit may include a line sensor (31) in which a plurality of sensor elements (32-1, 32-2, ..., 32-N) are arranged in the vertical direction and which receives the line beam-shaped laser light after it has passed through the headspace of the sealed container, and the detection signal may be obtained for each height in the vertical direction by the plurality of sensor elements.

[0015] With this configuration, the inspection device of the present invention can obtain detection signals for laser light at each vertical height using the sensor elements of the line sensor, with a simple configuration.

[0016] Furthermore, in the inspection apparatus according to the present invention, the laser light generating unit may include a laser light scanning unit (26) that scans the laser light in the vertical direction when irradiating the sealed container with the laser light, and the laser light detection unit may include a line sensor (31) in which a plurality of sensor elements (32-1, 32-2, ..., 32-N) are arranged in the vertical direction and which receives the laser light after it has passed through the headspace of the sealed container, and the detection signal may be obtained for each height in the vertical direction by the plurality of sensor elements.

[0017] With this configuration, the inspection device of the present invention can obtain detection signals for laser light at each vertical height using the sensor elements of the line sensor without shaping the laser light into a line beam.

[0018] Furthermore, the inspection apparatus according to the present invention may further include a base (50) on which the sealed container is placed and which is movable up and down in the vertical direction, and the vertical movement of the base changes the vertical height at which the laser light is irradiated onto the sealed container, thereby enabling the laser light detection unit to obtain the detection signal for each vertical height.

[0019] With this configuration, the inspection apparatus of the present invention can obtain detection signals for the laser beam at each vertical height without shaping the laser beam into a line beam, and while keeping the laser beam used for inspection fixed.

[0020] Furthermore, in the inspection apparatus according to the present invention, the laser light generation unit has a first reflector (262) whose vertical height of the reflective surface that reflects the laser light is variable, and the laser light is scanned in the vertical direction by changing the vertical height of the first reflector, and the laser light detection unit has a second reflector (263) which is positioned opposite the first reflector with the sealed container in between, and whose vertical height of the reflective surface that reflects the laser light is variable, and the laser light generated by the laser light generation unit is reflected by the first reflector at each vertical height and irradiated onto the sealed container, and the laser light that has passed through the headspace of the sealed container is reflected by the second reflector and directed towards the laser light detection unit and detected by the laser light detection unit.

[0021] With this configuration, the inspection apparatus of the present invention can obtain detection signals for laser light at predetermined vertical height intervals using a photodetector without using a line sensor, by changing the vertical heights of the first and second reflectors.

[0022] Furthermore, in order to achieve the above objective, the inspection method according to the present invention is characterized by comprising: a laser light generation step of generating laser light containing a wavelength absorbed by the target gas and irradiating a sealed container (10); a laser light detection step of detecting the laser light that has passed through the headspace (12) of the sealed container at each vertical height; and a signal processing step of calculating a state quantity indicating the state of the target gas at each vertical height from the detection signals obtained in the laser light detection step, and determining the airtightness of the sealed container based on the vertical statistical values ​​of the state quantity.

[0023] As described above, in the inspection method of the present invention, in the laser light detection step, the laser light transmitted through the headspace of the sealed container is detected for each height in the vertical direction, and in the signal processing step, a state quantity (for example, gas concentration) indicating the state of the target gas is calculated for each height in the vertical direction from the detection signal of the laser light, and the airtightness of the sealed container is determined based on the statistical value (for example, average value) in the vertical direction of the state quantity. With this configuration, even when the state quantity indicating the state of the target gas in the headspace of the sealed container is not uniform in the vertical direction, the airtightness of the sealed container can be accurately inspected based on the statistical value in the vertical direction of the state quantity.

Effect of the Invention

[0024] According to the present invention, it is possible to provide an inspection device and an inspection method capable of accurately inspecting the airtightness of a sealed container even when the gas concentration of the target gas in the headspace of the sealed container is not uniform in the vertical direction.

Brief Description of the Drawings

[0025] [Figure 1] It is a diagram showing the configuration of an inspection device according to the first embodiment of the present invention. [Figure 2] It is a diagram showing the configuration of the signal processing unit in FIG. 1. [Figure 3] It is a diagram showing a sealed container. [Figure 4] (a) is a side view showing a state in which a sealed container is irradiated with laser light and transmitted light is detected, and (b) is a plan view thereof. [Figure 5] It is a flowchart showing an inspection method according to the first embodiment of the present invention. [Figure 6] It is a diagram showing the configuration of a main part of an inspection device according to the second embodiment of the present invention. [Figure 7] It is a diagram showing the configuration of a main part of an inspection device according to the third embodiment of the present invention. [Figure 8] It is a diagram showing the configuration of a main part of an inspection device according to the fourth embodiment of the present invention. [Figure 9] It is a diagram showing the configuration of a main part of an inspection device according to the fifth embodiment of the present invention. [Figure 10] This diagram illustrates the principle of the 2f detection method. [Figure 11] (a) is a graph showing the 1f signal detected by lock-in from the laser light detection signal, and (b) is a graph showing the 2f signal. [Modes for carrying out the invention]

[0026] Embodiments of the present invention will be described below with reference to the drawings. Note that, for ease of understanding, the scale of each part in the drawings may differ from the actual scale. In the xyz Cartesian coordinate system set in the drawings, the x-axis and y-axis directions are horizontal, and the z-axis direction is vertical, i.e., the direction of gravity.

[0027] (First embodiment) Figure 1 shows the configuration of the inspection device 1 according to the first embodiment of the present invention. As shown in Figure 1, the inspection device 1 according to the first embodiment is an inspection device for inspecting the airtightness of a sealed container 10, such as a sealed vial. The sealed container 10 is not limited to a vial, as long as it is a container that requires airtightness.

[0028] The inspection device 1 of this embodiment uses headspace gas laser analysis as a method for inspecting the airtightness of a sealed container 10. As shown in Figure 1, the inspection device 1 transmits laser light LL of a predetermined wavelength into the headspace 12, which is the space inside the sealed container 10 other than the substance 11 (liquid, solid, or powder, etc.) sealed inside the sealed container 10. The inspection device 1 inspects the airtightness of the sealed container 10 based on the detection signal (also called the laser light detection signal or received signal) of the transmitted laser light absorbed by the target gas (e.g., oxygen, carbon dioxide, etc.). In the following description, oxygen will be used as the target gas as an example.

[0029] As shown in Figure 1, the inspection device 1 comprises a laser light generation unit 2, a laser light detection unit 3, a signal processing unit 4, and a display unit 5.

[0030] (Laser light generation unit) The laser light generation unit 2 generates laser light containing a wavelength absorbed by the target gas (absorption wavelength λc) and irradiates the sealed container 10 with it. Specifically, the laser light generation unit 2 includes a modulation signal generator 21, a laser driver 22, a laser diode 23, and a laser light shaping unit 24.

[0031] The modulation signal generator 21 generates a modulation signal and inputs it to the laser driver 22 and the signal processing unit 4. The modulation signal is, for example, a sine wave of a predetermined frequency. The laser light generation unit 2 generates frequency-modulated laser light based on the modulation signal.

[0032] The laser driver 22 provides a drive current I corresponding to the signal obtained by adding the modulated signal to a reference signal corresponding to the absorption wavelength λc. f The current is input to the laser diode 23. The absorption wavelength λc is the central wavelength of one absorption spectrum in the target gas. The laser driver 22 also controls the temperature of the laser diode 23 with a control current I. TEC This is input to the laser diode 23.

[0033] The laser diode 23 is driven by a reference signal corresponding to the absorption wavelength λc, which is obtained by modulating the modulated signal frequency f. f This generates laser light. Specifically, the laser diode 23 generates laser light that oscillates at the frequency f of the modulation signal with a predetermined wavelength width centered around the absorption wavelength λc.

[0034] The laser beam shaping unit 24 shapes the laser beam into a line beam extending vertically (in the z-axis direction) and irradiates it toward the sealed container 10.

[0035] Figure 4(a) is a side view showing the detection of transmitted light when laser light is shone onto a sealed container 10, and Figure 4(b) is a plan view thereof. As shown in Figure 4, the laser beam shaping unit 24 includes, for example, an optical element 241 that collimates the laser light and an optical element 242 that focuses the light onto the line sensor 31 in the horizontal plane (xy plane). The laser beam shaping unit 24 is not limited to this, and any configuration is acceptable as long as it can shape the laser light into a line beam extending in the vertical direction.

[0036] (Laser light detection unit) The laser light detection unit 3 is configured to detect laser light that has passed through the headspace 12 of the sealed container 10 at each vertical height. The laser light detection unit 3 outputs a laser light detection signal (received signal), which is an electrical signal corresponding to the intensity of the received laser light at each vertical height.

[0037] Specifically, as shown in Figure 4(a), the laser light detection unit 3 has a line sensor 31 in which a plurality of sensor elements 32-1, 32-2, ..., 32-N (where N is an integer of 2 or more) are arranged in the vertical direction, and the line beam-shaped laser light that has passed through the headspace 12 of the sealed container 10 is received. These N sensor elements provide a laser light detection signal for each vertical height.

[0038] (Signal processing unit) The signal processing unit 4 calculates a state quantity indicating the state of the target gas for each vertical height from the laser light detection signal output from the laser light detection unit 3 for each vertical height, and calculates a vertical statistical value of the state quantity from the state quantity for each vertical height. Then, the signal processing unit 4 determines the airtightness of the sealed container 10 based on the vertical statistical value of the state quantity. State quantities include, for example, gas concentration, pressure, and temperature. Statistical values ​​include, for example, mean, median, variance, and standard deviation. In the following explanation, we will use gas concentration as the state quantity and mean as the statistical value.

[0039] As shown in Figure 1, the signal processing unit 4 comprises signal processing units 4-1, 4-2, ..., 4-N (where N is an integer greater than or equal to 2) connected to the sensor elements 32-1, 32-2, ..., 32-N of the line sensor 31, respectively.

[0040] Figure 2 shows the detailed configuration of the signal processing unit 4. As shown in Figure 2, the signal processing unit 4 comprises a lock-in amplifier 41-1, ..., 41-N, a feature extraction unit 43-1, ..., 43-N, a gas concentration calculation unit 44-1, ..., 44-N, an average gas concentration calculation unit 45, and a determination unit 46. Here, N is an integer of 2 or more. The signal processing unit 4-n (1 ≤ n ≤ N) comprises at least a lock-in amplifier 41-n, a feature extraction unit 43-n, and a gas concentration calculation unit 44-n. The average gas concentration calculation unit 45 and the determination unit 46 may be provided in any or all of the signal processing units 4-n (1 ≤ n ≤ N).

[0041] The lock-in amplifier 41-n (1≦n≦N) is connected to the sensor element 32-n (1≦n≦N) of the line sensor 31 and receives the laser light detection signal detected by the sensor element 32-n. The lock-in amplifier 41-n is also connected to the modulation signal generator 21 and receives the modulation signal. The lock-in amplifier 41-n acquires the 2f signal by lock-in detection.

[0042] The feature extraction unit 43-n (1 ≤ n ≤ N) extracts the peak signal level B (see Figure 11(b)), which is a feature of the 2f signal.

[0043] The gas concentration calculation unit 44-n (1≦n≦N) calculates the gas concentration of the target gas based on the peak signal level B, which is a characteristic quantity of the 2f signal. The gas concentration may be calculated from, for example, the correspondence between known gas concentrations and signal levels B, which may be obtained in advance through testing or other means. Furthermore, since the vertical heights of the sensor elements 32-n (1≦n≦N) in the headspace 12 are discretely different from each other, the gas concentration of the target gas can be calculated for each vertical height in the headspace 12.

[0044] The average gas concentration calculation unit 45 calculates the average gas concentration in the vertical direction from the gas concentration of the target gas at each vertical height.

[0045] The determination unit 46 determines the airtightness of the sealed container 10 by, for example, comparing the average gas concentration with a threshold value that serves as a predetermined airtightness determination criterion based on tests, theoretical calculations, or required specifications.

[0046] In this manner, the signal processing unit 4 detects a signal component synchronized with twice the frequency of the modulated signal from the laser light detection signal at each vertical height, calculates the gas concentration of the target gas at each vertical height in the headspace 12 based on each signal component, determines the average gas concentration in the vertical direction from the gas concentrations of the target gas at each vertical height, and determines the airtightness of the sealed container 10 based on the average gas concentration.

[0047] The signal processing unit 4 is comprised, in part or in whole, of a computer that operates according to a program, for example.

[0048] (Display) The display unit 5, for example, is equipped with a liquid crystal screen and displays the results of the airtightness inspection of the sealed container 10.

[0049] (Transportation) Multiple sealed containers 10 are sequentially transported in an upright position in the inspection area where the inspection device 1 is located. The laser light generating unit 2 and the laser light detection unit 3 of the inspection device 1 are positioned opposite each other on either side of the transport path through which the sealed containers 10 are transported. The inspection device 1 inspects the airtightness of the sealed containers 10 during transport or when they are temporarily stopped, and the quality of the airtightness of the sealed containers 10 is determined based on the inspection results. For example, the subsequent transport route is then determined according to whether the containers are airtight or not.

[0050] In this embodiment, the sealed container 10 transported to the inspection area is sealed with the headspace 12 replaced by gas. That is, the sealed container 10 supplied to the inspection area is sealed with the gas in the headspace 12 replaced by an inert gas. In this embodiment, nitrogen gas is used as the inert gas for gas replacement.

[0051] As a gas replacement method, for example, a gas replacement method using a gas replacement device configured to fill the sealed container 10 with an inert gas from a nozzle different from the nozzle used for filling the substance 11 into the sealed container 10 may be used. The gas replacement method using a gas replacement device is not limited to the method described above, but various methods can be employed, such as a method of performing gas replacement by directly blowing an inert gas into the opening of the sealed container 10 after the substance has been filled.

[0052] For example, if nitrogen gas is sealed in a sealed container 10, and there is a defect in the seal of the sealed container 10, oxygen gas from the atmosphere will enter, and the airtightness of the sealed container 10 can be inspected by measuring the concentration of oxygen gas. Alternatively, if dry ice is placed around the sealed container 10, carbon dioxide gas will enter the sealed container 10 through the defect in the seal, and the airtightness of the sealed container 10 can be inspected by measuring the concentration of carbon dioxide gas. In this case, two types of gases, nitrogen and oxygen, or nitrogen and carbon dioxide, will exist in the headspace 12 of the sealed container 10, and due to the difference in density, an uneven distribution or concentration difference of the target gas, oxygen or carbon dioxide, will occur in the vertical direction.

[0053] (Testing method) Next, the method for inspecting the airtightness of the sealed container 10, performed by the inspection device 1, will be described with reference to Figure 5. Figure 5 is a flowchart showing the procedure of the inspection method.

[0054] First, the laser beam emitted from the laser diode 23 is shaped into a vertically extending line beam by the laser beam shaping unit 24 and irradiated onto the sealed container 10 (step S1). The sealed container 10 is positioned upright in the vertical direction.

[0055] Next, the laser light that has passed through the headspace 12 of the sealed container 10 is detected by the line sensor 31 (step S2). The line sensor 31 is positioned so that its longitudinal direction coincides with the vertical direction. The line sensor 31 has sensor elements 32-1, 32-2, ..., 32-N arranged at equal intervals along its longitudinal direction (N is an integer of 2 or more).

[0056] Next, the lock-in amplifiers 41-1, 41-2, ..., 41-N of the signal processing unit 4 acquire laser light detection signals from the sensor elements 32-1, 32-2, ..., 32-N, respectively, and acquire a 2f signal synchronized to twice the frequency f of the modulated signal from the laser light detection signal (step S3).

[0057] Specifically, the signal processing unit 4, lock-in amplifier 41-n (1≦n≦N), passes a signal obtained by multiplying the laser light detection signal and the second harmonic of the modulated wave through a low-pass filter to detect the 2f signal.

[0058] Next, the feature extraction unit 43-n (1≦n≦N) of the signal processing unit 4 calculates the gas concentration of the target gas for each vertical height from the 2f signal (step S4). The gas concentration may be calculated, for example, by first obtaining the correspondence between known gas concentrations and the feature quantities of the 2f signal (for example, the signal level B of the peak of the 2f signal) through testing, and then using this correspondence as the basis for calculating the gas concentration from the feature quantities of the 2f signal obtained by the feature quantity extraction unit 43 of the signal processing unit 4.

[0059] Next, the gas concentration calculation unit 44-n (1≦n≦N) of the signal processing unit 4 calculates the gas concentrations of the target gas GC1, GC2, ..., GC for each vertical height. N From this, calculate the vertical average gas concentration MGC (Step S5). That is, MGC = (GC1 + GC2 + ... + GCN ) / N.

[0060] Next, the signal processing unit 4 determines the airtightness of the sealed container 10 from the average gas concentration (step S6). Specifically, for example, the quality of the airtightness is determined by comparing the average gas concentration with a preset threshold. For example, if the average gas concentration is higher than the threshold, the airtightness test is judged as a failure (NG), and if it is lower than the threshold, it is judged as a pass (OK).

[0061] Then, if necessary, the sealing test results are displayed on the display unit 5 and the process is terminated. And / or, the subsequent transport route of the sealed container 10 is switched based on the sealing test results.

[0062] <Measuring gas concentration principle> This explains the principle of measuring gas concentration.

[0063] When a target gas is irradiated with laser light of absorption wavelength λc, the absorbance of the target gas is proportional to the gas concentration and the optical path length (Lambert-Beer law). This can be used to calculate the gas concentration from the attenuation of the laser light. Specifically, the laser light detection signals output from each sensor element 31-n (1≦n≦N) of the line sensor 31 have a waveform in which the signal level is attenuated according to the gas concentration of the target gas at the absorption wavelength λc of the target gas.

[0064] Figure 10 illustrates the principle of the 2f detection method. In Figure 10, code W1 represents the absorption spectrum of oxygen, the target gas. The absorption wavelength λc is, for example, 760.9 nm. Code W2 represents the time evolution of the wavelength of laser light frequency-modulated by the modulation signal frequency f (e.g., f=5 kHz). The laser light is wavelength-swept around λc in the range of λmin and λmax. This laser light is irradiated onto the sealed container 10. Code W3 represents the 2f signal obtained by lock-in detection of a signal component synchronized with frequency 2f (e.g., 2f=10 kHz) from the laser light detection signal output from the laser light detection unit 3 (each sensor element 31-n of the line sensor 31 in this embodiment) that receives the laser light transmitted through the headspace 12 of the sealed container 10. Noise can be suppressed by the 2f detection method.

[0065] Figure 11(a) is a graph showing the 1f signal detected by lock-in from the laser light detection signal, and Figure 11(b) is a graph showing the 2f signal. The horizontal axis represents wavelength, and the vertical axis represents signal level. The 1f signal in Figure 11(a) is a signal obtained by lock-in detection of a signal component synchronized with frequency 1f (e.g., f=5kHz) from the laser light detection signal. As shown in Figure 11(a), the 1f signal is the waveform obtained by differentiating the waveform of the laser light detection signal. More specifically, the waveform of the 1f signal is constant at signal level A at the absorption wavelength λc and wavelengths far from the absorption wavelength λc, and rises or falls from signal level A at wavelengths before and after the absorption wavelength λc. This signal level A is not affected by the gas concentration of the target gas and depends only on the light-receiving power.

[0066] As shown in Figure 11(b), the 2f signal is the waveform obtained by differentiating the waveform of the 1f signal shown in Figure 11(a). More specifically, the signal level of the 2f signal is 0 at wavelengths sufficiently far from the absorption wavelength λc, and peaks at the absorption wavelength λc. The signal level B of the 2f signal at the absorption wavelength λc is a value that depends on the gas concentration of the target gas and the light receiving power. The gas concentration calculation unit 44-n (1≦n≦N) of the signal processing unit 4 calculates the gas concentration, for example, from the signal level B of the 2f waveform.

[0067] In the embodiment described above, the gas concentration was determined from the signal level B of the 2f signal at the absorption wavelength λc, but this is not limited to this. The signal processing unit 4 may also determine the gas concentration from the peak height of the laser light detection signal at the absorption wavelength λc.

[0068] Alternatively, the signal processing unit 4 may determine the gas concentration from the peak heights D and E that appear before and after the absorption wavelength λc of the 1f signal.

[0069] Furthermore, the 3f signal (the signal component of the modulation signal at the third harmonic frequency in the laser light detection signal) has a waveform that is like the 1f signal waveform shown in Figure 11(a) inverted vertically. Therefore, the signal processing unit 4 may determine the gas concentration from the peak height that appears before and after the absorption wavelength λc in the 3f signal.

[0070] Furthermore, the 4f signal (the signal component of the modulation signal at the fourth harmonic frequency in the laser light detection signal) has a waveform that is like the 2f signal waveform shown in Figure 11(b) inverted vertically. Therefore, the signal processing unit 4 may determine the gas concentration from the peak height of the 4f signal at the absorption wavelength λc. In other words, the signal processing unit 4 can determine the gas concentration based on the nf signal (= the nth harmonic signal component (where n is an integer greater than or equal to 2)).

[0071] Furthermore, although the above-described embodiment uses the signal level B at the absorption wavelength λc of the 2f signal to calculate the gas concentration, it is not limited to this. For example, the gas concentration may be determined based on the shape of the 2f signal. By determining the gas concentration based on the shape of the 2f signal, the influence of gas pressure and other factors can be reduced, and the airtightness of the sealed container 10 can be inspected.

[0072] As described above, the laser light generation unit 2 generates frequency-modulated laser light based on the modulation signal, and the signal processing unit 4 locks in and detects a signal component synchronized to twice the frequency of the modulation signal from the laser light detection signal for each vertical height. With this configuration, the inspection device 1 of this embodiment can accurately calculate the gas concentration of the target gas for each vertical height, and thus can accurately determine the average gas concentration in the vertical direction. This allows for accurate determination of the airtightness of the sealed container 10. Therefore, even if the gas concentration of the target gas is not uniform in the vertical direction in the headspace 12 of the sealed container 10, the airtightness of the sealed container 10 can be accurately inspected.

[0073] (Second embodiment) Next, the inspection apparatus 1 according to the second embodiment will be described.

[0074] Figure 6 shows the configuration of the main parts of the inspection apparatus 1 according to the second embodiment of the present invention. As shown in Figure 6, the laser light generation unit 2 includes a laser light scanning unit 26 that scans the laser light in the vertical direction when irradiating the sealed container 10 with laser light. The laser light detection unit 3 includes a line sensor 31, similar to the first embodiment. The line sensor 31 has a plurality of sensor elements 32-1, 32-2, ..., 32-N arranged in the vertical direction, and receives the laser light after it has passed through the headspace 12 of the sealed container 10, and a laser light detection signal is obtained for each height in the vertical direction by each sensor element.

[0075] Specifically, the laser beam scanning unit 26 has a reflector 261 with a variable tilt angle of the reflective surface that reflects the laser beam, and the laser beam is scanned vertically by changing the tilt angle of the reflector 261. The laser beam emitted from the laser diode 23 is converted into a parallel laser beam LL by the collimator 25 and sent to the reflector 261. The reflector 261 is capable of rotating in the RM direction about a horizontal (perpendicular to the plane of the paper) y-axis axis. Figure 5(a) shows the state in which the laser beam LL is irradiated to the lower part of the headspace 12 of the sealed container 10 by adjusting the tilt angle of the reflector 261. Figure 5(b) shows the state in which the laser beam LL is irradiated to the upper part of the headspace 12 of the sealed container 10 by adjusting the tilt angle of the reflector 261.

[0076] The other components are the same as in the first embodiment, and their description is omitted.

[0077] In the second embodiment of the inspection apparatus 1, by changing the tilt angle of the reflector 261, a laser beam detection signal can be obtained by each sensor element of the line sensor 31 at each vertical height without shaping the laser beam into a line beam.

[0078] (Third embodiment) Next, the inspection apparatus 1 according to the third embodiment will be described.

[0079] Figure 7 shows the configuration of the main part of the inspection apparatus 1 according to the third embodiment of the present invention. As shown in Figure 7, the laser light scanning unit 26 has a reflector 262 whose vertical height of the reflective surface that reflects the laser light is variable, and the laser light is scanned vertically by changing the vertical height of the reflector 262. The laser light detection unit 3 is equipped with a line sensor 31, similar to the first embodiment. The line sensor 31 has a plurality of sensor elements 32-1, 32-2, ..., 32-N arranged in the vertical direction, and receives the laser light after it has passed through the headspace 12 of the sealed container 10, and a laser light detection signal is obtained for each vertical height by each sensor element.

[0080] Specifically, the laser beam emitted from the laser diode 23 is converted into a parallel laser beam LL by the collimator 25 and sent to the reflector 262. The reflector 262 is designed to move up and down in the LM direction, that is, in the vertical direction (z-axis direction). Figure 7(a) shows the state in which the laser beam LL is irradiated to the lower part of the headspace 12 of the sealed container 10 by adjusting the position of the reflector 262 in the LM direction. Figure 7(b) shows the state in which the laser beam LL is irradiated to the upper part of the headspace 12 of the sealed container 10 by adjusting the position of the reflector 262 in the LM direction.

[0081] The other components are the same as in the first embodiment, and their description is omitted.

[0082] In the third embodiment of the inspection apparatus 1, by changing the vertical height of the reflector 262, a laser beam detection signal can be obtained by each sensor element of the line sensor 31 at predetermined vertical height intervals without shaping the laser beam into a line beam.

[0083] (Fourth embodiment) Next, the inspection apparatus 1 according to the fourth embodiment will be described.

[0084] Figure 8 shows the configuration of the main parts of an inspection apparatus 1 according to the fourth embodiment of the present invention. As shown in Figure 8, the laser light generation unit 2 has a first reflector 262 whose vertical height of the reflective surface that reflects the laser light is variable, and the laser light is scanned vertically by changing the vertical height of the first reflector 262. The laser light detection unit 3 is positioned opposite the first reflector 262 with a sealed container 10 in between, and has a second reflector 263 whose vertical height of the reflective surface that reflects the laser light is variable.

[0085] The laser light generated by the laser light generation unit 2 is reflected by the first reflector 262 at each vertical height and irradiated onto the sealed container 10. The laser light that passes through the sealed container 10 is reflected by the second reflector 263 and directed towards the photodetector 32, where it is detected.

[0086] Unlike the first embodiment, which has N sensor elements, the laser light detection unit 3 includes a photodetector 32 having a single sensor element. Therefore, unlike the first embodiment, which has N signal processing units, the signal processing unit 4 has a single signal processing unit.

[0087] Specifically, the laser beam emitted from the laser diode 23 is converted into a parallel laser beam LL by the collimator 25 and sent to the reflector 262. The laser beam reflected by the reflector 262 is then directed onto the sealed container 10. The laser beam that has passed through the sealed container 10 is reflected by the second reflector 263 and directed towards the photodetector 32, where it is detected. The reflector 262 is designed to move up and down in the LM direction, i.e., the vertical direction (z-axis direction). Similarly, the reflector 263 is also designed to move up and down in the LM direction, i.e., the vertical direction (z-axis direction).

[0088] Figure 8(a) shows the state in which the laser beam LL is irradiated to the lower part of the headspace 12 of the sealed container 10 by adjusting the positions of the reflectors 262 and 263 in the LM direction. Figure 8(b) shows the state in which the laser beam LL is irradiated to the upper part of the headspace 12 of the sealed container 10 by adjusting the positions of the reflectors 262 and 263 in the LM direction.

[0089] The other components are the same as in the first embodiment, and their description is omitted.

[0090] In the fourth embodiment of the inspection apparatus 1, by changing the vertical height of the first reflector 262 and the second reflector 263, a laser beam detection signal can be obtained by the photodetector 32 for each vertical height without using a line sensor.

[0091] (Fifth embodiment) Next, the inspection apparatus 1 according to the fifth embodiment will be described.

[0092] Figure 9 shows the configuration of the main parts of an inspection device 1 according to a fifth embodiment of the present invention. As shown in Figure 9, the inspection device 1 further includes a base 50 on which a sealed container 10 is placed and which can move up and down in the vertical direction. By changing the vertical height at which the laser beam is irradiated onto the sealed container 10 by the vertical movement of the base 50, a detection signal is obtained by the laser beam detection unit 3 for each vertical height.

[0093] Unlike the first embodiment, which has N sensor elements, the laser light detection unit 3 includes a photodetector 32 having a single sensor element. Therefore, unlike the first embodiment, which has N signal processing units, the signal processing unit 4 has a single signal processing unit.

[0094] Specifically, the laser light emitted from the laser diode 23 is made into a parallel laser beam LL by the collimator 25 and irradiated onto the sealed container 10 placed on the base 50. The laser light that passes through the sealed container 10 is detected by the photodetector 32. The base 50 is designed to move up and down in the LM direction, that is, in the vertical direction (z-axis direction).

[0095] Figure 9(a) shows the state in which the laser beam LL is irradiated to the lower part of the headspace 12 of the sealed container 10 by adjusting the position of the base 50 in the LM direction. Figure 9(b) shows the state in which the laser beam LL is irradiated to the upper part of the headspace 12 of the sealed container 10 by adjusting the position of the base 50 in the LM direction.

[0096] As described above, moving the sealed container 10 up and down changes the measurement position inside the sealed container 10. In this case, the measurement area inside the sealed container 10 corresponds to the light reception time of the photodetector 32. The base 50 may also be equipped with a rotation mechanism that rotates in the RM direction or the opposite direction with the vertical direction (z-axis direction) as the axis of rotation. This makes it possible to increase the measurement area in the sealed container 10.

[0097] The other components are the same as in the first embodiment, and their description is omitted.

[0098] In the fifth embodiment of the inspection apparatus 1, by changing the vertical height of the base 50, a detection signal for the laser beam can be obtained by the photodetector 32 at each vertical height without shaping the laser beam into a line beam, and while the laser beam itself remains fixed.

[0099] The present invention is not limited to the embodiments described above, and various modifications and changes are possible within the scope of the gist of the invention as described in the claims.

[0100] As described above, the present invention has the effect of being able to accurately inspect the airtightness of a sealed container even when the gas concentration of the target gas is not uniform in the headspace of the sealed container, and is useful for inspection devices and inspection methods in general. [Explanation of Symbols]

[0101] 1. Inspection device 2. Laser light generation unit 3. Light detection unit 4. Signal Processing Unit 5 Display section 10 Sealed container 11 Substance 12 headspace 13. High-density gases 14. Low-density gases 21 Modulated signal generator 22 Laser Drivers 23 Laser Diode 24 Laser Shaping Section 25 Collimator 26 Laser beam scanning unit 31 Line Sensor 32 Photo Detectors 41 Lock-in detection unit 43 Feature Extraction Unit 44 Gas concentration calculation unit 45. Average gas concentration calculation unit 46 Judgment section 50 bases 241, 242 Optical elements 261, 262, 263 Reflector LL laser light

Claims

1. A laser light generating unit (2) generates laser light containing wavelengths absorbed by the target gas and irradiates the sealed container (10), A laser beam detection unit (3) detects the laser beam that has passed through the headspace (12) of the sealed container at each vertical height, A signal processing unit (4) calculates a state quantity indicating the state of the target gas for each vertical height from the detection signal output from the laser light detection unit, and determines the airtightness of the sealed container based on the vertical statistical value of the state quantity, An inspection device equipped with the following features.

2. The laser light generating unit further comprises a modulation signal generator (21) that generates a modulation signal, and generates the laser light that is frequency modulated based on the modulation signal. The inspection apparatus according to claim 1, wherein the signal processing unit detects a signal component synchronized with a frequency n times the frequency of the modulated signal (where n is an integer of 1 or more) from the detection signal for each vertical height, calculates the gas concentration of the target gas for each vertical height in the headspace based on each signal component, determines the average gas concentration in the vertical direction from the gas concentration of the target gas for each vertical height, and determines the airtightness of the sealed container based on the average gas concentration.

3. The laser light generating unit further comprises a modulation signal generator (21) that generates a modulation signal, and generates the laser light that is frequency modulated based on the modulation signal. The inspection apparatus according to claim 1, wherein the signal processing unit detects a signal component synchronized with twice the frequency of the modulated signal from the detection signal for each vertical height, calculates the gas concentration of the target gas for each vertical height in the headspace based on each signal component, determines the average gas concentration in the vertical direction from the gas concentration of the target gas for each vertical height, and determines the airtightness of the sealed container based on the average gas concentration.

4. The laser light generating unit includes a laser light shaping unit (24) that shapes the laser light into a line beam-shaped laser light extending in the vertical direction and irradiates it toward the sealed container. The laser light detection unit includes a line sensor (31) in which a plurality of sensor elements (32-1, 32-2, ..., 32-N) are arranged in the vertical direction, and which receives the line beam-shaped laser light after it has passed through the headspace of the sealed container, and the plurality of sensor elements provide the detection signal for each height in the vertical direction. The inspection apparatus according to claim 2.

5. The laser light generating unit includes a laser light scanning unit (26) that scans the laser light in the vertical direction when irradiating the sealed container with the laser light. The laser light detection unit includes a line sensor (31) in which a plurality of sensor elements (32-1, 32-2, ..., 32-N) are arranged in the vertical direction and which receives the laser light after it has passed through the headspace of the sealed container, and the plurality of sensor elements provide the detection signal for each height in the vertical direction. The inspection apparatus according to claim 2.

6. The aforementioned sealed container is placed on a base (50) which is further movable up and down in the vertical direction, The vertical movement of the base changes the vertical height at which the laser beam is irradiated onto the sealed container, thereby allowing the laser beam detection unit to obtain the detection signal for each vertical height. The inspection apparatus according to claim 2.

7. The laser light generating unit has a first reflecting mirror (262) whose vertical height of the reflective surface that reflects the laser light is variable, and the laser light is scanned in the vertical direction by changing the vertical height of the first reflecting mirror. The laser light detection unit has a second reflector (263) positioned opposite the first reflector with the sealed container in between, the second reflector having a variable vertical height of the reflective surface that reflects the laser light, The laser light generated by the laser light generating unit is reflected by the first reflector at each vertical height and irradiated onto the sealed container, and the laser light that has passed through the headspace of the sealed container is reflected by the second reflector and directed towards the laser light detection unit, where it is detected. The inspection apparatus according to claim 2.

8. A laser light generation step involves generating laser light containing wavelengths absorbed by the target gas and irradiating it onto a sealed container (10), A laser beam detection step in which the laser beam that has passed through the headspace (12) of the sealed container is detected at each vertical height, A signal processing step which involves calculating a state quantity indicating the state of the target gas for each vertical height from the detection signals obtained in the laser beam detection step, and determining the airtightness of the sealed container based on the vertical statistical values ​​of the state quantity, A testing method that includes [a specific feature / feature].

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