X-ray inspection device

Abstract

The invention relates to an X-ray inspection apparatus. An X-ray inspection device (1) is provided with: an X-ray irradiation unit (6) that generates X-rays by applying a first voltage between a cathode (57) and an anode (56) in an X-ray bulb (50), and irradiates a conveyed article (G) with the X-rays; an X-ray detection unit (7) that detects the X-rays irradiated from the X-ray irradiation unit (6); an inspection unit (40) that generates an X-ray transmission image on the basis of the detection result of the X-ray detection unit (7) and inspects the article (G); and a control unit (40) that changes the voltage applied between the cathode (57) and the anode (56). The control unit (40) applies a second voltage between the cathode (57) and the anode (56), the second voltage being higher than the first voltage, before the irradiation of the X-ray generated by the application of the first voltage is started or after the irradiation of the X-ray generated by the application of the first voltage is ended.

Description

Technical Field

[0001] One aspect of the present invention relates to an X-ray inspection apparatus. Background Art

[0002] An X-ray inspection device is known (for example, Patent Document 1: Japanese Patent Application Publication No. 2014-2023), which includes a conveying unit that conveys an article, an X-ray irradiation unit that irradiates the article conveyed by the conveying unit with X-rays, and an X-ray detection unit that detects X-rays that have passed through the article. In such an X-ray inspection device, a voltage value applied to an X-ray tube is adjusted in accordance with the type of the article to be inspected, and an output value of the X-rays is appropriately switched. Summary of the invention

[0003] In such an X-ray inspection device, when inspection is continuously performed under low voltage conditions such as a voltage value in the range of 15 kV to 50 kV, a malfunction may occur due to inappropriate X-ray emission in a part of the acquired X-ray transmission image (abnormal discharge generated in the X-ray tube). In this case, it is necessary to acquire the X-ray transmission image again, and the inspection processing capability of the X-ray inspection device is reduced.

[0004] Therefore, an object of one aspect of the present invention is to provide an X-ray inspection apparatus that can suppress a decrease in inspection throughput even when inspection is continuously performed under low voltage conditions.

[0005] (1) An X-ray inspection apparatus according to one aspect of the present invention comprises: an X-ray irradiation unit that generates X-rays by applying a first voltage between a cathode and an anode in an X-ray tube and irradiates an object being transported with the X-rays; an X-ray detection unit that detects the X-rays irradiated from the X-ray irradiation unit; an inspection unit that generates an X-ray transmission image based on the detection result of the X-ray detection unit and inspects the object; and a control unit that changes the voltage applied between the cathode and the anode, the control unit applying a second voltage higher than the first voltage between the cathode and the anode before starting to irradiate the X-rays generated by applying the first voltage or after ending to irradiate the X-rays generated by applying the first voltage.

[0006] Regarding the problem that when an X-ray inspection device is continuously used under low voltage conditions, a part of the acquired X-ray transmission image is not properly radiated with X-rays, the inventor of the present application believes that the reason may be that if the voltage applied between the cathode and the anode is low, the force pulling electrons from the cathode to the anode is weak, and the remaining electrons that have not hit the target will be retained in the X-ray tube. Therefore, it is believed that if a high voltage is applied between the cathode and the anode, these remaining electrons will hit the target and be driven out of the X-ray tube, and X-rays will be properly radiated from the X-ray tube. Therefore, the control unit applies a second voltage higher than the first voltage between the cathode and the anode before starting to radiate X-rays generated by applying the first voltage or after ending to radiate X-rays generated by applying the first voltage. As a result, abnormal discharge generated in the X-ray tube is suppressed, and even when the inspection is continuously performed under low voltage conditions, the decline in inspection processing capacity can be suppressed.

[0007] (2) In the X-ray inspection device described in (1) above, the first voltage may be in the range of 15 kV to 50 kV, and the second voltage may be in the range of 60 kV to 150 kV. In this configuration, even when the X-ray inspection device is continuously used under the condition of a low voltage in the range of 15 kV to 50 kV, by periodically applying a high voltage in the range of 60 kV to 150 kV, it is possible to suppress the occurrence of an inappropriate situation caused by inappropriate X-ray emission in a part of the acquired X-ray transmission image.

[0008] (3) In the X-ray inspection device described in (1) or (2) above, the second voltage may be at least twice the first voltage. In this configuration, by periodically applying the second voltage at least twice the first voltage, it is possible to suppress the occurrence of an adverse situation caused by inappropriate X-ray emission in a portion of the acquired X-ray transmission image.

[0009] (4) In the X-ray inspection apparatus described in any one of (1) to (3) above, the control unit may determine at least one of the intensity and application time of the second voltage based on at least one of the number of abnormal discharges generated in the X-ray irradiation unit and the irradiation time of X-rays in the X-ray irradiation unit starting from the start of use of the X-ray tube or the last time the second voltage was applied. In this configuration, it is possible to appropriately remove excess electrons in the X-ray tube.

[0010] (5) In the X-ray inspection device described in any one of (1) to (4) above, the control unit may store the number of abnormal discharges generated in the X-ray irradiation unit starting from when the X-ray tube was started or when the second voltage was last applied, and determine whether to apply the second voltage based on the number of abnormal discharges. The time for applying the second voltage that is not related to obtaining the X-ray transmission image will erode the time that can be used for inspection and cause a decrease in inspection processing capacity. In this configuration, since the second voltage is applied as needed, the decrease in inspection processing capacity can be minimized.

[0011] (6) In the X-ray inspection device described in any one of (1) to (5) above, the control unit may store the irradiation time of X-rays in the X-ray irradiation unit starting from the time when the X-ray tube was started or the last time the second voltage was applied, and determine whether to apply the second voltage based on the irradiation time. The time for applying the second voltage that is not related to the acquisition of the X-ray transmission image will erode the time that can be used for the inspection and cause a decrease in the inspection processing capacity. In this configuration, since the second voltage is applied as needed, the decrease in the inspection processing capacity can be minimized.

[0012] (7) In the X-ray inspection apparatus described in any one of (1) to (6) above, the control unit may apply the second voltage when the power is turned on. In this configuration, since the excess electrons in the X-ray tube are appropriately removed periodically, even when the inspection is continuously performed under low voltage conditions, it is possible to suppress a decrease in the inspection processing capability.

[0013] According to an aspect of the present invention, even when inspection is continuously performed under a low voltage condition, a decrease in inspection throughput can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a diagram showing the configuration of an X-ray inspection apparatus according to one embodiment.

[0015] Figure 2 for Figure 1 The diagram shows the internal structure of the shielding box.

[0016] Figure 3 To show Figure 1 A schematic diagram showing a schematic structure of an X-ray irradiation unit is shown.

[0017] Figure 4 This is a graph showing the number of times abnormal discharge occurs per day when the operation is continued with a voltage of 30 kV (8 mA) applied between the anode electrode and the cathode electrode.

[0018] Figure 5This is a graph showing the number of abnormal discharges per day when a voltage of 30 kV (8 mA) is continuously applied after a voltage of 75 kV (4 mA) is applied between the anode electrode and the cathode electrode for ten minutes. DETAILED DESCRIPTION

[0019] Hereinafter, an X-ray inspection apparatus 1 according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0020] like Figure 1 and Figure 2 As shown, the X-ray inspection device 1 includes a device body 2, a support leg 3, a shielding box 4, a conveyor conveyor 5, an X-ray irradiation unit 6, an X-ray detection unit 7, an LCD display 8, and a controller (control unit) 10. The X-ray inspection device 1 acquires an X-ray transmission image of the article G while conveying the article G, and performs inspections on the article G based on the X-ray transmission image (for example, storage quantity inspection, foreign matter mixing inspection, shortage inspection, defect inspection, etc.).

[0021] The X-ray inspection device 1 is connected to an external power supply (not shown) that supplies power to the X-ray inspection device 1. In the X-ray inspection device 1, an X-ray generating device 100 is composed of an X-ray irradiation unit 6, an LCD display 8, and a controller 10. It should be noted that the article G before inspection is transported into the X-ray inspection device 1 by the inward conveyor 9A, and the article G after inspection is transported out of the X-ray inspection device 1 by the outward conveyor 9B. The article G determined as a defective product by the X-ray inspection device 1 is distributed outside the production line by a distribution device (not shown) arranged downstream of the outward conveyor 9B, and the article G determined as a qualified product by the X-ray inspection device 1 directly passes through the distribution device.

[0022] The device body 2 accommodates a controller 10 and the like. The support legs 3 support the device body 2. The shielding box 4 is provided in the device body 2 to prevent X-ray leakage. An inlet 4a and an outlet 4b are formed in the shielding box 4. The article G before inspection is transported into the shielding box 4 through the inlet 4a by the inlet conveyor 9A, and the article G after inspection is transported out of the shielding box 4 through the outlet 4b to the outlet conveyor 9B. X-ray shielding curtains (not shown) are provided in the inlet 4a and the outlet 4b, respectively, to prevent X-ray leakage.

[0023] The transport conveyor 5 is disposed in the shield box 4 and transports the articles G from the carrying inlet 4a to the carrying outlet 4b along the transport direction A. The transport conveyor 5 is, for example, a belt conveyor that is hung between the carrying inlet 4a and the carrying outlet 4b.

[0024] The X-ray irradiation unit 6 is disposed in the shield box 4 and irradiates X-rays to the article G conveyed by the conveyor 5. The X-ray irradiation unit 6 includes at least an X-ray tube 50 (see FIG. 5 ) for irradiating X-rays. Figure 3 ). The details of the X-ray irradiation unit 6 will be described later.

[0025] The X-ray detection unit 7 is arranged in the shield box 4, and detects the X-rays irradiated from the X-ray irradiation unit 6 and transmitted through the article G and the conveyor 5. The X-ray detection unit 7 constitutes an X-ray detection device. The X-ray detection unit 7 is configured as a line sensor, for example. Specifically, the X-ray detection unit 7 has a plurality of photodiodes arranged one-dimensionally along a horizontal direction perpendicular to the conveying direction A and a scintillator arranged on the X-ray incident side relative to each photodiode. In this case, in the X-ray detection unit 7, the X-ray incident on the scintillator is converted into light, and the light incident on each photodiode is converted into an electrical signal.

[0026] The LCD display 8 is provided in the apparatus body 2. The LCD display 8 has a display screen as a touch panel and a speaker. The LCD display 8 functions as an operation input unit for accepting inputs of various conditions through the display screen. The LCD display 8 functions as a display unit for displaying the inspection results of the X-ray inspection apparatus 1 through the display screen.

[0027] The controller 10 is arranged in the device body 2, and controls the operation of each part of the X-ray inspection device 1. The controller 10 has a processor such as a CPU (Central Processing Unit), a memory such as a ROM (Read Only Memory), a RAM (Random Access Memory), and a storage such as an SSD (Solid State Drive). The ROM stores a program for controlling the X-ray inspection device 1. The controller 10 can be configured as software that loads the program stored in the ROM onto the RAM and executes it through the CPU. The controller 10 can also be configured as hardware using an electronic circuit, etc. It should be noted that the characteristic control content of the controller 10 in this embodiment will be described in detail later.

[0028] The storage unit 10A is composed of one or more of a RAM, a HDD (Hard Disk Drive), a flash memory, etc. The storage unit 10A stores the generated X-ray transmission image, the detection time of abnormal discharge, normal driving conditions (the applied voltage for each object G, the application time of the voltage for each object G, the conveying speed), etc.

[0029] The X-ray generating device 100 is a device that generates X-rays, and Figure 1 As shown, it includes an X-ray irradiation unit 6, a controller 10 and an LCD display 8. Figure 3 As shown, the X-ray irradiation unit 6 includes an X-ray tube 50, a tube power supply 51, a filament power supply 52, a tank 53, an abnormal discharge detection circuit 54, and a current monitoring mechanism 71. The X-ray tube 50 includes an X-ray tube body 55 formed of stainless steel and ceramics, an anode electrode 56 (anode) disposed inside the X-ray tube body 55 and including a target material T, and a cathode electrode 57 (cathode) disposed inside the X-ray tube body 55 and including a filament F. An X-ray irradiation window 58 is formed in the X-ray tube body 55 to transmit X-rays.

[0030] The tube power supply 51 is connected to an external power supply, and boosts the input voltage through an inverter or the like (not shown) to generate a predetermined DC voltage. The positive output terminal of the tube power supply 51 is connected to the anode electrode 56, and the negative output terminal is connected to the cathode electrode 57. The tube power supply 51 applies (supplies) a predetermined voltage to the anode electrode 56 and the cathode electrode 57, respectively, and generates a potential difference between the anode electrode 56 and the cathode electrode 57.

[0031] The filament power supply 52 supplies a filament current to the cathode electrode 57. As described above, when a filament current is supplied from the filament power supply 52 to the cathode electrode 57 in a state where a predetermined potential difference is generated between the anode electrode 56 and the cathode electrode 57, the cathode electrode 57 is heated in the X-ray tube 50, and thermal electrons are released from the cathode electrode 57. The thermal electrons released from the cathode electrode 57 collide with the anode electrode 56 (see the dotted arrow). As a result, X-rays are generated and irradiated to the outside of the X-ray tube 50 through the X-ray irradiation window 58 (see the single-dot chain arrow X).

[0032] The tank 53 accommodates the X-ray tube 50, the tube power supply 51, and the filament power supply 52. ​​An electric circuit connecting the tube power supply 51 and the anode electrode 56 (i.e., an electric circuit including the anode electrode 56), i.e., a first electric circuit 59, and an electric circuit connecting the tube power supply 51 and the cathode electrode 57 (i.e., an electric circuit including the cathode electrode 57), i.e., a second electric circuit 60 are arranged in the tank 53.

[0033] Insulating oil 61 is sealed in the tank 53. The insulating oil 61 has electrical insulation properties and ensures electrical insulation between the parts with potential difference in the space inside the tank 53 (for example, between the first electrical circuit 59 and the second electrical circuit 60 or between the first electrical circuit 59 or the second electrical circuit 60 and the tank 53 or the X-ray tube body 55). The insulating oil 61 plays a role in cooling the X-ray tube 50, which generates high heat when generating X-rays. It should be noted that, instead of the insulating oil 61 or in addition to the insulating oil 61, a solid insulator such as epoxy or silicon may be sealed in the tank 53.

[0034] The abnormal discharge detection circuit 54 is a circuit for detecting abnormal discharge generated in the X-ray tube 50. The abnormal discharge caused by the structure of the X-ray tube 50 is generated in the X-ray tube 50 mainly because the electrons released from the cathode electrode 57 do not collide with the anode electrode 56 and stay in the X-ray tube 50. More specifically, the abnormal discharge caused by the structure of the X-ray tube 50 includes discharge caused between the anode electrode 56 and the cathode electrode 57 due to ionization of the gas inside the X-ray tube 50 by the electrons released from the cathode electrode 57, and discharge caused in the X-ray tube 50 due to temporary accumulation of the electrons released from the cathode electrode 57 on the X-ray tube wall that maintains insulation and saturation.

[0035] The abnormal discharge detection circuit 54 is connected to the first electrical circuit 59, the second electrical circuit 60, and the controller 10, respectively. The abnormal discharge detection circuit 54 is configured to include a first detection unit that outputs a pulse according to a change (sudden decrease) in the voltage value in the first electrical circuit 59, a second detection unit that outputs a pulse according to a change (sudden decrease) in the voltage value in the second electrical circuit 60, an XOR circuit, an AND circuit, etc. When a change (sudden decrease) in the voltage value occurs in at least one of the first electrical circuit 59 and the second electrical circuit 60, the abnormal discharge detection circuit 54 detects this and outputs a signal to the controller 10.

[0036] The current monitoring mechanism 71 has a function of monitoring the current flowing in the X-ray tube 50. The current monitoring mechanism 71 can be constituted by, for example, a current detector. The arrangement of the current monitoring mechanism 71 is not particularly limited, but the current monitoring mechanism 71 is arranged between the tube power supply 51 and the anode electrode 56.

[0037] The controller 10 controls the X-ray irradiation unit 6. The controller 10 changes the voltage applied between the anode electrode 56 and the cathode electrode 57. Specifically, when the type of the article G to be inspected is selected (preset) through the LCD display 8, the controller 10 reads the voltage value (tube voltage) stored corresponding to the type of the article G from the storage unit 10A, and applies the read voltage between the anode electrode 56 and the cathode electrode 57 when inspecting the article G. As a result, a current (tube current) corresponding to the applied voltage flows in the X-ray tube 50, and X-rays with an intensity suitable for X-ray inspection (suitable for obtaining a clear X-ray transmission image) are irradiated to the article G. The signal output from the X-ray detection unit 7 and A / D converted is input to the controller 10. The controller 10 functions as an inspection unit that generates an X-ray transmission image of the article G based on the signal and inspects the article G based on the X-ray transmission image.

[0038] In the X-ray inspection device 1 of the present embodiment, in order to improve the inspection performance including thin articles or soft foreign matter, the tube voltage can be set within a low voltage range of 15 kV to 50 kV. That is, when inspecting the article G, the controller 10 can apply a voltage (hereinafter also referred to as "first voltage") within a range of 15 kV to 50 kV between the anode electrode 56 and the cathode electrode 57.

[0039] The controller 10 detects abnormal discharge based on the change in voltage value in both the first electrical circuit 59 and the second electrical circuit 60. When the controller 10 detects the change (sudden decrease) in voltage value in both the first electrical circuit 59 and the second electrical circuit 60, it is determined that abnormal discharge has occurred. The controller 10 stores information related to the time when the abnormal discharge is determined to have occurred in the storage unit 10A.

[0040] The controller 10 periodically applies a voltage in the range of 60 kV to 150 kV (hereinafter also referred to as a "second voltage") higher than the voltage in the range of 15 kV to 50 kV between the anode electrode 56 and the cathode electrode 57. More specifically, the controller 10 applies the second voltage between the anode electrode 56 and the cathode electrode 57 before starting to irradiate X-rays generated by applying the voltage in the range of 15 kV to 50 kV or after ending to irradiate X-rays generated by applying the voltage in the range of 15 kV to 50 kV.

[0041] The controller 10 applies the second voltage stored in the storage unit 10A in association with the first voltage. In addition, the second voltage applied by the controller 10 of the present embodiment is set to be twice or more the first voltage. For example, the controller 10 operates the X-ray irradiation unit 6 at a tube voltage of 75 kV (at which the tube current is 1 mA) for one minute before operating the X-ray irradiation unit 6 at a tube voltage of 30 kV (at which the tube current is 8 mA).

[0042] Examples of timing before starting to irradiate X-rays generated by applying the first voltage include the following timings, namely, the timing for starting the X-ray inspection device 1 every morning (just after the power of the X-ray inspection device 1 is turned on), selecting the type of object G to be inspected (changing the reservation setting) and just before calibration is performed under that condition, just after the inspection start button is pressed and just before starting to irradiate X-rays generated by applying the first voltage, etc.

[0043] In addition, examples of timing after starting to irradiate X-rays generated by applying the first voltage include the following timings, namely, the timing to stop the X-ray inspection device 1 in the evening every day (just before the power of the X-ray inspection device 1 is turned off), before setting the type of object G to be inspected (just after pressing the button for starting to change the reservation setting), and after the object G is discharged from the conveyor 5 (just after the inspection is completed).

[0044] The effects of the X-ray inspection device 1 of the above-mentioned embodiment will be described. When the X-ray inspection device 1 is continuously used under the condition that the voltage applied between the anode electrode 56 and the cathode electrode 57 is a low voltage of 15 kV to 50 kV, a defect (such as multiple stripes) may occur due to the X-rays not being properly radiated in a part of the acquired X-ray transmission image. The inventors of the present application have found that the reason is that if the voltage applied between the anode electrode 56 and the cathode electrode 57 is low, the force pulling the electrons from the cathode electrode 57 to the anode electrode 56 is weak, and the remaining electrons that have not hit the target material T are retained in the X-ray tube 50. Therefore, it is considered that if a voltage (high voltage) in the range of 60 kV to 150 kV is applied between the anode electrode 56 and the cathode electrode 57, these remaining electrons will hit the target material T and be driven out of the X-ray tube 50, and X-rays will be properly radiated from the X-ray tube 50.

[0045] In the X-ray inspection apparatus 1 of the present embodiment, before starting to irradiate X-rays generated by applying the first voltage or after finishing irradiating X-rays generated by applying the first voltage, the controller 10 applies a second voltage higher than the first voltage between the anode electrode 56 and the cathode electrode 57. As a result, abnormal discharge generated in the X-ray tube 50 is suppressed, and even when the inspection is continuously performed under the condition of applying a voltage in the range of 15 kV to 50 kV (low voltage), it is possible to suppress a decrease in the inspection processing capability.

[0046] Here, it was confirmed that abnormal discharge occurred when the first voltage was continuously applied between the anode electrode 56 and the cathode electrode 57. Figure 1 to Figure 3 In the X-ray inspection device 1 shown in FIG. 1 , the number of abnormal discharges per day was obtained when the voltage of 30 kV (8 mA) was continuously applied between the anode electrode 56 and the cathode electrode 57 (after continuous power-on). Figure 4 As shown, the number of abnormal discharges occurring each day increases suddenly after the predetermined energization time has passed. Therefore, when the abnormal discharges begin to increase suddenly, a voltage of 75 kV (4 mA) higher than 30 kV (8 mA) is applied between the anode electrode 56 and the cathode electrode 57 for ten minutes.

[0047] The number of abnormal discharges per day was obtained when a voltage of 30 kV (8 mA) was continuously applied after applying a voltage of 75 kV (4 mA). Figure 5 As shown, the number of abnormal discharges generated per day can be suppressed. It can be confirmed that if a second voltage higher than the first voltage is applied between the anode electrode 56 and the cathode electrode 57, even when the inspection is continuously performed under the condition of a low voltage such as 15kV to 50kV, the abnormal discharge generated in the X-ray tube 50 is suppressed, and the reduction in the inspection processing capacity can be suppressed.

[0048] In the X-ray inspection device 1 of the present embodiment, the first voltage ranges from 15 kV to 50 kV, and the second voltage ranges from 60 kV to 150 kV. In this configuration, even when the X-ray inspection device is continuously used under the condition of a low voltage range of 15 kV to 50 kV, a high voltage range of 60 kV to 150 kV can be periodically applied to suppress the occurrence of an inappropriate situation caused by inappropriate X-ray emission in a part of the acquired X-ray transmission image.

[0049] In the X-ray inspection apparatus 1 of this embodiment, the second voltage is set to be twice or more of the first voltage. In this configuration, by periodically applying the second voltage that is twice or more of the first voltage, it is possible to suppress the occurrence of a problem caused by inappropriate X-ray emission in a part of the acquired X-ray transmission image.

[0050] In the X-ray inspection apparatus 1 of the present embodiment, the controller 10 can apply the second voltage when the power is turned on. With such a configuration, since the excess electrons in the X-ray tube 50 are properly and regularly discharged, even when the inspection is continuously performed under the condition of a low voltage in the range of 15 kV to 50 kV, the number of times abnormal discharge occurs in the X-ray tube 50 is reduced, and thus the inspection processing capability can be suppressed from being reduced.

[0051] Although one embodiment has been described above, one aspect of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention.

[0052] In the X-ray inspection apparatus 1 of the present embodiment, the second voltage applied by the controller 10 is described by taking as an example the second voltage stored in the storage unit 10A, i.e., the set value set relative to the first voltage (in other words, set for each object G), but the present invention is not limited thereto. For example, the controller 10 may also apply a variable value that changes according to various conditions (operating conditions) set in the X-ray irradiation unit 6 as the second voltage. For example, the controller 10 may also determine at least one of the intensity and application time of the second voltage based on at least one of the number of abnormal discharges generated in the X-ray irradiation unit 6 and the irradiation time of X-rays in the X-ray irradiation unit 6 starting from the start of use of the X-ray tube 50 or the last application of the second voltage. It should be noted that the number of abnormal discharges generated in the X-ray irradiation unit 6 and the irradiation time of X-rays in the X-ray irradiation unit 6 are stored in the storage unit 10A.

[0053] In order to apply the second voltage to drive out the excess electrons in the X-ray tube 50 in a shorter time, the shortest application time of the second voltage may be determined based on the maximum voltage (e.g., 75 kV) that can be set in the X-ray inspection device 1. However, in this case, the burden imposed on the X-ray tube 50 or the X-ray detection unit 7 increases. Therefore, when there is enough time for applying the second voltage (e.g., after the end of a day's production), a voltage lower than the above-mentioned maximum voltage (e.g., 60 kV) may be set and applied for a longer application time than the above-mentioned shortest application time, thereby driving out the excess electrons in the X-ray tube 50 from the X-ray tube 50. In this way, the second voltage can be applied while suppressing the deterioration of each component.

[0054] In the X-ray inspection apparatus 1 of the above embodiment and the above modification, the second voltage is applied regularly at the timing described above, but the present invention is not limited thereto. For example, the controller 10 may determine whether to apply the second voltage every time at the timing described above.

[0055] As an example of a determination method, the controller 10 may also determine whether to apply the second voltage based on the number of abnormal discharges generated in the X-ray irradiation unit 6 starting from when the X-ray tube 50 is started to be used or when the second voltage was last applied. It should be noted that the controller 10 can obtain the number of abnormal discharges from the storage unit 10A.

[0056] In addition, as another example of the determination method, the controller 10 may also determine whether to apply the second voltage based on the irradiation time of X-rays in the X-ray irradiation unit 6 starting from when the X-ray tube 50 is started to be used or when the second voltage was last applied. It should be noted that the controller 10 can obtain the above-mentioned irradiation time from the storage unit 10A.

[0057] With the configuration of such a modified example, it is possible to appropriately remove the excess electrons in the X-ray tube 50. In addition, although the time for applying the first voltage to perform inspection is eroded if the second voltage is applied periodically, with the configuration of such a modified example, the number of times the second voltage is applied can be minimized. Furthermore, the reduction in the inspection processing capability of the X-ray inspection device 1 can be minimized.

[0058] In the X-ray inspection apparatus 1 of the above-mentioned embodiment and the above-mentioned modification, an example of applying a voltage more than twice the first voltage when applying the second voltage is given and explained, but if the first voltage is set to 15kV to 50kV and the second voltage is set to 60kV to 150kV, the condition of applying a voltage more than twice the first voltage when applying the second voltage can be removed. In addition, as in the X-ray inspection apparatus 1 of the above-mentioned embodiment and the above-mentioned modification, even if the first voltage is not set within the range of 15kV to 50kV and the second voltage is not set within the range of 60kV to 150kV, it is sufficient as long as the controller 10 is configured to apply a voltage more than twice the first voltage when applying the second voltage.

[0059] In the X-ray inspection apparatus 1 of the above-mentioned embodiment and the above-mentioned modification, an example is given and described in which the X-ray detection unit 7 has a plurality of photodiodes arranged one-dimensionally along the horizontal direction (width direction) perpendicular to the conveying direction A, but it is also possible to have a plurality of photodiodes arranged in a plane (two-dimensionally) in the conveying direction A and the width direction. In addition, the X-ray detection unit 7 may be, for example, a sensor (multi-energy sensor) that detects X-rays in each of a plurality of energy regions that pass through the article G. In addition, in the X-ray inspection apparatus 1 of the above-mentioned embodiment and the above-mentioned modification, an example is given and described in which a scintillator is arranged on the X-ray incident side relative to each photodiode, but this may be eliminated and the X-ray detection unit 7 may be replaced by a direct conversion type detection unit that can detect X-rays by photon counting.

Claims

1. An X-ray inspection device comprising: An X-ray irradiation unit generates X-rays by applying a first voltage between a cathode and an anode in an X-ray tube, and irradiates the conveyed object with X-rays; An X-ray detection unit that detects the X-rays irradiated from the X-ray irradiation unit; an inspection unit that generates an X-ray transmission image based on the detection result of the X-ray detection unit and inspects the object; as well as a control unit that changes a voltage applied between the cathode and the anode, The control unit applies a second voltage higher than the first voltage between the cathode and the anode before starting irradiation of X-rays generated by applying the first voltage or after ending irradiation of X-rays generated by applying the first voltage.

2. The X-ray inspection apparatus according to claim 1, wherein: The first voltage ranges from 15 kV to 50 kV, and the second voltage ranges from 60 kV to 150 kV.

3. The X-ray inspection device according to claim 1 or 2, wherein: The second voltage is more than twice the first voltage.

4. The X-ray inspection apparatus according to claim 1 or 2, wherein: The control unit determines at least one of the intensity and application time of the second voltage based on at least one of the number of abnormal discharges generated in the X-ray irradiation unit and the irradiation time of the X-rays in the X-ray irradiation unit starting from the start of use of the X-ray tube or the last time the second voltage was applied.

5. The X-ray inspection apparatus according to claim 1 or 2, wherein: The control unit stores the number of abnormal discharges generated in the X-ray irradiation unit starting from when the X-ray tube starts to be used or when the second voltage was last applied, and determines whether to apply the second voltage based on the number of abnormal discharges.

6. The X-ray inspection apparatus according to claim 1 or 2, wherein: The control unit stores an irradiation time of the X-rays in the X-ray irradiation unit starting from when the X-ray tube starts to be used or when the second voltage was last applied, and determines whether to apply the second voltage based on the irradiation time.

7. The X-ray inspection apparatus according to claim 1 or 2, wherein: The control unit applies the second voltage when power is turned on.

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