X-ray inspection equipment

Abstract

The present invention provides an X-ray inspection device that can easily detect a decrease in the vacuum level of an X-ray tube. [Solution] The system comprises a transport unit that continuously transports an object to be inspected, which is placed on a mounting surface having a width perpendicular to the transport direction, in the transport direction; an X-ray generating unit that irradiates the object to be inspected with X-rays while it is being transported by the transport unit, and includes an X-ray detection unit that detects the X-rays that have passed through the object to be inspected; an inspection unit that performs inspection based on the detection data of the X-rays detected by the X-ray detection unit; a measurement unit that measures and controls the amount of electricity of the filament power supply of the X-ray tube; and a detection unit that detects when a predetermined deterioration has occurred in the vacuum level of the X-ray tube based on the measured amount of electricity.

Description

【Technical Field】 , 【0007】 【0001】 The present invention relates to an X-ray inspection apparatus having a function of predicting deterioration of an X-ray generator in advance. 【Background Art】 【0002】 An X-ray inspection apparatus is known that irradiates an inspection object such as food or a package with X-rays and analyzes the X-rays that have passed through the inspection object to inspect the internal and external states of the inspection object (see, for example, Patent Document 1). 【0003】 An X-ray tube used as a radiation source for irradiating an inspection object with X-rays includes a filament (cathode) and a target (anode) in a vacuum tube, and generates X-rays by colliding thermoelectrons emitted by applying a high voltage to the filament against the target. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2018-096796 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 By repeatedly using the X-ray tube, the degree of vacuum decreases, and the risk of fluctuations and decreases in the X-ray generation intensity, and even the risk of generation stop increases. However, there has been no X-ray inspection apparatus having a function that enables easy grasping of the decrease in the degree of vacuum. 【0006】 An object of the present invention is to provide an X-ray inspection apparatus capable of easily grasping a decrease in the degree of vacuum of an X-ray tube. 【Means for Solving the Problems】 【0007】 The X-ray inspection apparatus of the present invention comprises: a transport unit that continuously transports an object to be inspected, which is placed on a mounting surface having a width in a direction perpendicular to the transport direction, in the transport direction; an X-ray generating unit equipped with an X-ray tube that generates X-rays by causing thermionic electrons emitted from a filament, which is the cathode, to collide with a target, which is the anode, and irradiates the object to be inspected with X-rays while it is being transported by the transport unit; an X-ray detection unit that detects the X-rays that have passed through the object to be inspected; an inspection unit that performs inspection based on the detection data of the X-rays detected by the X-ray detection unit; a control unit that measures and controls the amount of electricity of the filament power supply of the X-ray tube; and a detection unit that detects when a predetermined deterioration has occurred in the vacuum level of the X-ray tube based on the amount of electricity. 【0008】 The amount of electricity may also be the filament current value. 【0009】 The detection unit may detect that a predetermined deterioration has occurred in the vacuum level of the X-ray tube based solely on the filament current value. 【0010】 The control unit may control the filament power supply so that the amount of X-rays generated from the X-ray tube remains constant. 【0011】 The control unit may perform the measurement of electrical quantities when aging the X-ray tube. 【0012】 The detection unit may detect a slight deterioration in the vacuum level of the X-ray tube when the amount of electricity exceeds a first threshold. 【0013】 The first threshold may be determined by taking into account the time-dependent increase in the amount of electricity over a predetermined period prior to the detection of mild degradation of the X-ray tube. 【0014】 The detection unit may detect that severe deterioration has occurred in the vacuum level of the X-ray tube when the amount of electricity exceeds a second threshold that is greater than the first threshold. 【0015】 The second threshold may be a value based on the specifications of the X-ray tube. 【0016】 The detection unit may further detect that a predetermined deterioration has occurred in the filament of the X-ray tube based on the electrical quantity. 【0017】 The electrical quantity may be the filament current value. 【0018】 The detection unit may detect that a predetermined deterioration has occurred in the filament of the X-ray tube based only on the filament current value. 【0019】 The detection unit may detect that a predetermined deterioration has occurred in the filament when the filament current value falls below a third threshold value. 【0020】 The third threshold value may be determined based on the filament current value in a predetermined period prior to the detection of the predetermined deterioration of the filament. 【0021】 When the detection unit detects a predetermined deterioration, it may perform a predetermined display on the display unit. 【Advantages of the Invention】 【0022】 According to the X-ray inspection apparatus of the present invention, it is possible to easily grasp the deterioration of the vacuum degree of the X-ray tube based on the change over time of the filament current. As a result, the timing of replacing the X-ray tube becomes clear and planned replacement is possible. Therefore, compared with the case where a failure occurs unexpectedly and replacement is performed, the production stop time of the user can be shortened. 【Brief Description of the Drawings】 【0023】 [Figure 1] It is a diagram showing the configuration of the X-ray inspection apparatus 100 of the present invention. [Figure 2] It is a diagram showing an example of the specific configuration of the X-ray generation unit 120. [Figure 3] It is a graph showing the relationship between the usage time of the X-ray tube 121 and the filament current value If, and a diagram showing an example of threshold setting. [Figure 4] It is a graph showing the relationship between the usage time of the X-ray tube 121 and the filament current value If, and a diagram showing another example of threshold setting. 【Best Mode for Carrying Out the Invention】 【0024】 Hereinafter, embodiments of the present invention will be described based on the drawings. In the following description, the same reference numerals are assigned to the same functional parts, and the description of the functional parts that have been described once will be omitted as appropriate. Also, the pixel value of each pixel constituting the image is such that the smaller the value, the brighter, and the larger the value, the darker. 【0025】 A functional block diagram of the X-ray inspection apparatus 100 of the present invention is shown in FIG. 1. 【0026】 The X-ray inspection apparatus 100 includes a conveyance unit 110, an X-ray generation unit 120, an X-ray detection unit 130, an inspection unit 140, a sorting unit 150, a control unit 160, a storage unit 170, a detection unit 180, and a display unit 190. 【0027】 The conveyance unit 110 is a conveyor of an arbitrary type that continuously conveys the inspection object W placed sequentially in a predetermined one direction (in the example of FIG. 1, the positive Y-axis direction in a three-dimensional orthogonal coordinate system in which the Z-axis direction is the gravity direction) at a predetermined speed. The inspection object W is an arbitrary object, and examples thereof include foods and food packages. The inspection object W placed on the conveyance unit 110 is carried into the housing of the X-ray inspection apparatus 100 (not shown) from the carry-in port (the left side of the X-ray inspection apparatus 100 in FIG. 1) of the X-ray inspection apparatus 100, undergoes X-ray inspection, and is carried out from the carry-out port (the right side of the X-ray inspection apparatus 100 in FIG. 1). 【0028】 The transport unit 110 has a width in the direction perpendicular to the transport direction (X-axis direction), and moves the placed inspection object W in the positive Y-axis direction by moving the mounting surface, which is an XY plane. The mounting surface may be a physical surface that moves along with the placed inspection object W by moving itself as a surface, like a belt conveyor, or it may be a virtual surface in the sense that the inspection object W is moved as a surface by being powered, like a driven roller conveyor. The transport speed depends on the detection period of the detection element, etc., but in foreign object inspection of articles, it is generally around a few m / min to over a hundred m / min. 【0029】 The X-ray generator 120 generates X-rays and irradiates the object to be inspected W, which is being transported by the transport unit 110, with the X-rays. An example of the specific configuration of the X-ray generator 120 is shown in Figure 2. The X-ray generator 120 comprises an X-ray tube 121, a filament power supply Vf, and a tube power supply Vt. The X-ray tube 121 generates X-rays according to the following principle. The inside of the X-ray tube 121 is a vacuum and contains a filament 121f, which is the cathode, and a target 121t, which is a metal plate that is the anode. The filament 121f generates heat and produces thermionic electrons when a filament current, which is supplied by the filament power supply Vf, flows through it. By applying a high voltage between the target 121t and the filament 121f using the tube power supply Vt, the thermionic electrons generated from the filament 121f are accelerated. Then, when these accelerated thermionic electrons collide with the target 121t, X-rays are generated. 【0030】 The X-ray detection unit 130 is positioned to detect X-rays that have passed through the object to be inspected W irradiated by the X-ray generation unit 120. X-rays that have passed through the object to be inspected W are X-rays that have been transmitted through or reflected from the object to be inspected W. Figure 1 shows an example in which the X-ray detection unit 130 is positioned opposite the X-ray generation unit 120, with the mounting surface of the transport unit 110 in between, in order to detect X-rays that have passed through the object to be inspected W. When detecting X-rays that have passed through the object to be inspected W, the X-ray detection unit 130 may be positioned inside the transport unit 110 as shown in Figure 1 to detect X-rays that have passed through the conveyor belt, etc., or the transport unit 110 may be divided into two parts and the X-rays may be detected from the gap between the two parts. When the X-ray detection unit 130 is positioned inside the transport unit 110, it is preferable to use a conveyor belt, etc. made of a material that has high transparency to the X-rays irradiated by the X-ray generation unit 120. Furthermore, when detecting X-rays reflected from the object W to be inspected, the transport unit 110 may be positioned above the mounting surface, that is, on the same side as the X-ray generating unit 120. 【0031】 The X-ray detection unit 130 is a line sensor in which multiple detection elements are arranged in the width direction (X-axis direction) of the transport unit 110 to detect X-rays irradiated by the X-ray generation unit 120. Each detection element of the X-ray detection unit 130 detects electromagnetic waves that have arrived after passing through the object to be inspected W transported by the transport unit 110 and outputs detection data at predetermined intervals. The number of detection elements arranged in the line sensor is set to at least cover the width direction range in which the object to be inspected W is placed on the transport unit 110. Furthermore, the period in which each detection element detects electromagnetic waves, accumulates detection data, and outputs it is set to, for example, the time required for the width in the transport direction of the detection elements to pass through at the transport speed of the object to be inspected W by the transport unit 110. By setting the number of elements and the detection period in this way, the objects to be inspected W passing through the X-ray detection unit 130 one after another can be inspected without omission. 【0032】 Since the position of the X-ray detection unit 130 is fixed, as the object to be inspected W is transported in the positive Y-axis direction, the X-ray detection unit 130 moves relative to the object to be inspected W in the negative Y-axis direction, and the object to be inspected W is scanned by the strip-shaped detection area. During this scanning, each detection element of the X-ray detection unit 130 repeatedly detects the electromagnetic waves that have passed through the object to be inspected W at a detection cycle corresponding to the transport speed of the object to be inspected W. For example, a group of detection data arranged in two dimensions by the number of detection elements × the number of detection cycles can be obtained. The number of cycles in which the group of detection data is obtained can be arbitrarily determined according to the size of the object to be inspected W, the size of the image to be generated, etc. 【0033】 The inspection unit 140 performs inspection based on the X-ray detection data detected by the X-ray detection unit 130. Specifically, first, based on the group of detection data obtained from the output of the X-ray detection unit 130, it generates an image in which the position of each detection data in a two-dimensional array is used as the pixel position, and the value of the detection data for each pixel is expressed as a pixel value. Then, by comparing the pixel value of each pixel with a predetermined threshold, the pixel region corresponding to the part in which the object to be inspected W is located is identified. 【0034】 In images generated based on X-ray detection data, areas where no object exists are bright, while areas where an object exists are dark. Furthermore, if there are abnormalities, such as foreign objects within an object, the abnormal areas are imaged darker than the areas without abnormalities. Therefore, by appropriately setting thresholds for pixel values, each area can be distinguished. 【0035】 For example, an object detection threshold is set to distinguish between areas where the object W is not present and areas where it is present, and an anomaly detection threshold is set to distinguish between areas without anomalies and areas with anomalies. Then, for example, by applying the object detection threshold to each pixel of the generated image, the pixel region corresponding to the area where the object W is present is identified, and further by applying the anomaly detection threshold to each pixel in the pixel region corresponding to the area where the object W is present, it is possible to identify which object W has an anomaly. As a result, the pixel region corresponding to the area where the anomaly-affected object W, which is the target for sorting, is present can be identified. 【0036】 The sorting unit 150 is equipped with one or more sorting mechanisms downstream of the transport of the X-ray detection unit 130. The sorting mechanism can be implemented in any form as long as it can sort the objects to be inspected W according to the inspection results in the inspection unit 140. 【0037】 One example of a sorting mechanism is a nozzle that injects gas. In this case, the number of nozzles is such that it covers the area in which the detection elements of the X-ray detection unit 130 are arranged in the width direction (X-axis direction) of the transport unit 110. Specifically, the nozzles are arranged so that gas is injected at a predetermined position as the object to be inspected W, which has been placed on the transport unit 110 and transported, passes through the transport unit as it falls after being released from the transport end of the transport unit 110. 【0038】 The inspection results of the detection data detected by the detection elements of the X-ray detection unit 130, performed by the inspection unit 140, are reflected in the gas ejection operation from a nozzle provided downstream of the transport unit 110 at the widthwise position of the transport unit 110 where the detection elements are located. The number of detection elements in the X-ray detection unit 130 and the number of nozzles in the sorting unit 150 do not have to be the same, as long as there is a corresponding relationship. For example, the operation of one nozzle provided downstream of the transport of two or more detection elements may be determined based on the inspection results of the detection data detected by two or more detection elements. 【0039】 The control unit 160 measures the electrical quantities necessary for controlling the X-ray tube 121 and detecting its degradation, such as the current, voltage, and power consumption of the filament power supply Vf and tube power supply Vt in the X-ray tube 121. It also controls the filament power supply Vf and tube power supply Vt so that the X-ray generation intensity from the X-ray generation unit 120 remains constant, i.e., so that the tube current value It remains constant. The measurement results may be stored in a storage unit 170, which is a storage means of any type. 【0040】 The timing of the measurement of electrical quantities in the control unit 160 is arbitrary, but it is preferable to measure them periodically or whenever necessary and store them in the memory unit 170 so that changes in electrical quantities over time can be grasped. Electrical quantities may be measured, for example, each time the aging of the X-ray tube 121 is performed. In particular, by measuring immediately after aging, measurement results under the same conditions can be accumulated without difficulty. Measurements may also be taken each time an X-ray inspection is performed, but it becomes necessary to evaluate changes over time considering the differences in inspection conditions for each inspection. 【0041】 The detection unit 180 detects that a predetermined deterioration has occurred in the X-ray tube 121 based on the measurement results of the electrical quantity in the control unit 160. 【0042】 The vacuum level of the X-ray tube 121 deteriorates with repeated use. As the vacuum level deteriorates, thermionic electrons moving at high speed collide with the increased number of gas molecules inside the X-ray tube 121, hindering their movement and reducing the tube current, which in turn reduces the amount of X-rays generated. When the control unit 160 detects a decrease in the tube current value It, it controls the filament power supply Vf to increase the filament current, thereby increasing electron emission from the filament 121f. This increases the tube current and maintains a constant amount of X-rays generated. In other words, a predetermined deterioration of the vacuum level of the X-ray tube 121 can be detected from the increasing trend of the filament current value If over time. The predetermined deterioration of the vacuum level that can be detected includes mild deterioration, which is desirable to replace as soon as possible, and severe deterioration, which requires urgent replacement. Whether a predetermined deterioration has occurred can be detected based on the filament current value If as described above, or based on electrical quantities other than the filament current value If measured by the control unit 160. It can also be detected based on multiple electrical quantities. 【0043】 For example, when detecting a predetermined deterioration of the vacuum level based solely on the filament current value If, ​​a threshold for detecting mild deterioration (first threshold T1) and a threshold for detecting severe deterioration (second threshold T2) that is greater than the first threshold T1 are determined in advance of detection. The detection unit 180 then performs detection by determining whether or not the filament current value If exceeds these thresholds. The first threshold T1 and the second threshold T2 may be determined appropriately based on, for example, the specifications and type of the X-ray tube 121 actually applied to the X-ray generation unit 120, the actual trend of the filament current value If over time, etc. 【0044】 Figure 3 shows graph G1, an example of the relationship between the operating time of the X-ray tube 121 and the filament current value If. As can be seen from this graph, the filament current value If increases over time and then increases sharply from a certain point. In other words, even when the X-ray tube 121 is operating normally, the filament current value If increases over time. This is because, even when the X-ray tube 121 is operating normally, it deteriorates little by little, but the filament current value If is controlled by the control function of the X-ray generation unit 120 so that the X-ray generation intensity does not decrease due to deterioration. 【0045】 The first threshold T1 is preferably determined by taking into account the time-dependent increase in the filament current value If within the range in which the X-ray tube 121 operates normally. Specifically, for example, an approximate straight line A of graph G1 may be drawn for a predetermined period prior to the detection of mild degradation, and the current value obtained by adding the amount obtained by multiplying the increase in the filament current value If between the starting point and the ending point of the approximate straight line A during the predetermined period by a certain multiplier (e.g., 1.5) to the filament current value If at the starting point of the approximate straight line A may be used as the first threshold T1. 【0046】 On the other hand, when the filament current value If increases sharply, it indicates that there is a limit to how much the X-ray intensity can be stabilized by increasing the filament current value If, ​​and the X-ray tube is on the verge of failure. Therefore, it is desirable to set the second threshold T2 as low as possible, taking into account the specifications and type of the X-ray tube 121. 【0047】 The above describes an example of detecting the deterioration of the vacuum level of the X-ray tube 121 based on changes in the filament current value If. However, it is also possible to similarly detect the deterioration based on changes in electrical quantities other than the filament current value If measured by the control unit 160. 【0048】 The detection unit 180 can also detect when a predetermined degradation has occurred in the filament 121f of the X-ray tube 121, based on the measurement results of the amount of electricity of the filament power supply Vf in the control unit 160. Figure 4 shows graph G2, an example of the relationship between the usage time of the X-ray tube 121 and the filament current value If. In this example, the filament current value If continues to increase gradually until around 3500 hours after the start of use, in accordance with the degradation of the vacuum state, but thereafter it begins to decrease. This decrease is based on the fact that the cross-sectional area decreases and the resistance value increases due to the degradation of the filament 121f. 【0049】 The control unit 160 controls the power of the filament power supply Vf to maintain a constant power level in order to keep the amount of X-rays generated constant. Specifically, as the resistance of the filament 121f increases, the power of the filament power supply Vf tends to increase. When the control unit 160 detects this increasing trend, it reduces the filament current value If to keep the power of the filament power supply Vf constant. Therefore, the decreasing trend of the filament current value If caused by this control makes it possible to detect that a certain degree of deterioration has occurred in the filament 121f. The certain degree of deterioration of the filament 121f that can be detected includes mild deterioration, which is desirable to replace as soon as possible, similar to deterioration of the vacuum level, and severe deterioration, which requires urgent replacement. The certain degree of deterioration may be detected by taking into account requirements other than the filament current value If, ​​or it may be detected based solely on the filament current value If. 【0050】 When detecting a predetermined degradation of the filament 121f based solely on the filament current value If, ​​a threshold for detecting mild degradation (third threshold T3) and a threshold for detecting severe degradation (fourth threshold T4) smaller than the third threshold T3 are determined in advance of the determination. The detection unit 180 then performs detection by determining whether the filament current value If falls below these thresholds. The third threshold T3 and the fourth threshold T4 may be determined appropriately based on, for example, the specifications and type of the X-ray tube 121 actually applied to the X-ray generator 120, and the actual trend of the filament current value If over time. For example, the third threshold T3 may be determined based on the average of the filament current value If over a predetermined period prior to the detection of mild degradation of the X-ray tube 121 (for example, one week from the start of use). The fourth threshold T4 may be determined, for example, by multiplying the third threshold T3 by a certain multiplier. 【0051】 When the detection unit 180 detects a predetermined level of deterioration, it may display the detection result on the display unit 190, which is a display means of any type. 【0052】 For example, the system may be configured to display a message prompting the user to check the filament current value If when the first or third threshold is exceeded, or it may be configured to display a button along with the message, and clicking the button may display a graph showing the change in the filament current value If over time. Alternatively, the system may be configured to display a message warning the user to replace the filament immediately when the second or fourth threshold is exceeded. 【0053】 According to the X-ray inspection apparatus of the present invention, deterioration of the vacuum level of the X-ray tube and deterioration of the filament can be easily determined based on changes in the filament current over time. This clarifies the timing for replacing the X-ray tube and enables planned replacement, thereby reducing the user's production downtime compared to when replacement is required due to an unexpected failure. 【0054】 It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that has substantially the same technical idea as described in the claims of the present invention and produces similar effects is included within the technical scope of the present invention. In other words, modifications can be made as appropriate within the scope of the technical idea expressed in the present invention, and such modified or improved forms are also included within the technical scope of the present invention. [Explanation of symbols] 【0055】 100 X-ray inspection equipment 110 Conveying section 120 X-ray generator 121 X-ray tube 121f filament 121t target 130 X-ray detection unit 140 Inspection Department 150 sorting section 160 Control Unit 170 Storage section 180 Detection unit 190 Display section A Approximate straight line d Increase G1, G2 graphs If filament current value It tube current value T1 First threshold T2 Second threshold T3 Third threshold T4: The fourth threshold Vf Filament Power Supply Vt tube power supply W: Items to be inspected

Claims

[Claim 1] A transport unit that continuously transports an object to be inspected, which is placed on a mounting surface having a width in a direction perpendicular to the transport direction, in the transport direction, The X-ray tube is equipped with an X-ray tube that generates X-rays by colliding thermionic electrons emitted from a filament, which is the cathode, with a target, which is the anode, and the X-ray generating unit irradiates the object to be inspected with X-rays while it is being transported by the transport unit, An X-ray detection unit for detecting the X-rays that have passed through the object to be inspected, An inspection unit that performs an inspection based on the X-ray detection data detected by the X-ray detection unit, A control unit for measuring and controlling the amount of electricity in the filament power supply of the X-ray tube, A detection unit that detects a predetermined deterioration in the vacuum level of the X-ray tube based on the aforementioned electrical quantity, Equipped with, The detection unit is an X-ray inspection device that detects a predetermined deterioration in the vacuum level of the X-ray tube based solely on the filament current value from the measured electrical quantity. [Claim 2] The X-ray inspection apparatus according to claim 1, wherein the control unit controls the filament power supply so that the amount of X-rays generated from the X-ray tube remains constant. [Claim 3] The X-ray inspection apparatus according to claim 1, wherein the measurement of the electrical quantity by the control unit is performed when the aging of the X-ray tube is performed. [Claim 4] The X-ray inspection apparatus according to claim 1, wherein the detection unit detects that a slight deterioration has occurred in the vacuum of the X-ray tube when the amount of electricity exceeds a first threshold. [Claim 5] The X-ray inspection apparatus according to claim 4, wherein the first threshold is determined taking into account the time-dependent increase in the amount of electricity during a predetermined period prior to the detection of mild deterioration of the X-ray tube. [Claim 6] The X-ray inspection apparatus according to claim 4, wherein the detection unit detects that severe deterioration has occurred in the vacuum of the X-ray tube when the amount of electricity exceeds a second threshold which is greater than the first threshold. [Claim 7] The X-ray inspection apparatus according to claim 6, wherein the second threshold value is a value based on the specifications of the X-ray tube. [Claim 8] The X-ray inspection apparatus according to claim 1, wherein the detection unit further detects, based on the amount of electricity, that a predetermined deterioration has occurred in the filament of the X-ray tube. [Claim 9] The X-ray inspection apparatus according to claim 8, wherein the detection unit detects that a predetermined deterioration has occurred in the filament of the X-ray tube based solely on the filament current value from the measured amount of electricity. [Claim 10] The X-ray inspection apparatus according to claim 9, wherein the detection unit detects that a predetermined deterioration has occurred in the filament when the filament current value falls below a third threshold. [Claim 11] The X-ray inspection apparatus according to claim 10, wherein the third threshold is determined based on the filament current value during a predetermined period prior to the detection of a predetermined deterioration of the filament. [Claim 12] The X-ray inspection apparatus according to claim 1, wherein the detection unit displays a predetermined message on the display unit when it detects the predetermined deterioration.

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