Automatic window foil replacement device

Abstract

To provide an automatic window foil replacement device capable of automatically replacing a window foil of a vacuum chamber to be irradiated with electron beams at an electron beam irradiation device.SOLUTION: An automatic window foil replacement device 1 includes a window foil replacement mechanism 2 configured to wind up a window foil 3 of an electron beam irradiation device 10 and also unwind the window foil to replace the window foil. The window foil replacement mechanism includes a winding roll 21 for a window foil, an unwinding roll 22 for a window foil, a leveling roll 23 and a window foil replacement control part 24. The window foil replacement control part controls a winding length of the window foil at the winding roll and an unwinding length of the window foil at the unwinding roll, according to a cumulative exposure dose of electron beams penetrating through the window foil and irradiating an irradiation target object.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION An embodiment of the present invention relates to an automatic window foil changer. [Background technology]

[0002] Electron beam irradiation devices accelerate electrons using high voltage in a high vacuum, then extract the accelerated electrons into the atmosphere, transferring their energy to materials and inducing various reactions (see Patent Documents 1 and 2). This type of electron beam irradiation process is characterized by a higher energy utilization rate than the thermal energy used in conventional chemical reactions, the absence of additives such as reaction accelerators, and the fact that it is effective at low temperatures. Furthermore, while electron beams are a type of radiation, they are easy to handle and highly safe, as their radiation generation can be controlled by turning the power on and off. Furthermore, the energy delivered to materials per unit time is orders of magnitude greater than that of gamma rays, which can cause similar phenomena. Therefore, electron beam irradiation allows for high continuous productivity, and is actively used industrially, particularly in the fields of sterilization and printing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-8386 [Patent Document 2] Patent No. 7153783 Summary of the Invention [Problem to be solved by the invention]

[0004] Although electron beam irradiation equipment has high continuous productivity and is actively used industrially, the window foil of the vacuum chamber is damaged by electron beam irradiation and must be replaced with a new one after a certain irradiation dose. The window foil is a component that transmits irradiated electrons while maintaining the high vacuum of the vacuum chamber. When replacing the window foil, the vacuum chamber must be returned from a high vacuum state to atmospheric pressure. This requires the production line to be stopped when replacing the window foil, which causes a problem of reduced productivity.

[0005] In order to solve the above problems, the present invention provides an automatic window foil exchange device that can automatically exchange window foils in a vacuum chamber that is irradiated with electron beams in an electron beam irradiation device. [Means for solving the problem]

[0006] An automatic window foil changer according to one embodiment changes the window foil in an electron beam irradiation device including a vacuum chamber through which an electron beam passes to be irradiated onto an object to be irradiated, and a window foil that closes an opening of the chamber to allow the electron beam to pass from the inside of the chamber to the outside. The automatic window foil changer includes a window foil change mechanism that winds and unwinds the window foil to change the window foil. The window foil change mechanism includes a take-up roll, an unwinding roll, a leveling roll, and a window foil change controller. The take-up roll winds the window foil. The unwinding roll unwinds the window foil. The leveling roll keeps the position of the window foil constant in the transmission direction of the electron beam between the take-up roll and the unwinding roll. The window foil change controller controls the winding length of the window foil on the take-up roll and the unwinding length of the window foil on the unwinding roll according to the cumulative dose of the electron beam that passes through the window foil and is irradiated onto the object to be irradiated.

[0007] The automatic window foil changer further includes a vacuum maintenance mechanism for maintaining a vacuum state in the chamber when the window foil changer changes the window foil. The vacuum maintenance mechanism includes at least one permanent magnet, a first magnetic member, a non-magnetic member, a magnetic fluid server, and a second magnetic member. At least one of the permanent magnets is arranged in series. The first magnetic member is magnetically attracted to each pole face of the at least one permanent magnet. The non-magnetic member is interposed between adjacent first magnetic members. The magnetic fluid server supplies magnetic fluid to one end of the first magnetic member in the transmission direction of the electron beam. The second magnetic member is arranged on the opposite side of the window foil from the magnetic fluid and contacts the window foil.

[0008] The vacuum maintenance mechanism has a window foil cooling unit that cools the window foil when the window foil is replaced, and a window foil replacement control unit controls the winding of the window foil onto the winding roll and the unwinding of the window foil onto the unwinding roll so that the window foil can be cooled to a predetermined temperature by the window foil cooling unit when the window foil is replaced. The vacuum maintaining mechanism includes an electromagnet that is disposed on the opposite side of the second magnetic member from the side that contacts the window foil, and that attracts the magnetic fluid by magnetic force via the window foil and the second magnetic member. The vacuum maintaining mechanism has a filter disposed in an exhaust path when the chamber is evacuated and in a purge gas filling path when the chamber is released from the vacuum state to the atmosphere.

[0009] The window foil is made of a β-titanium alloy. The β-titanium alloy is an alloy containing titanium (Ti) and a molybdenum (Mo) equivalent of 10 wt% or more. The Mo equivalent is expressed by the following relational expression: Mo + 0.67 × V + 0.44 × W + 0.28 × Nb + 0.22 × Ta + 2.9 × Fe + 1.6 × Cr - 1.0 × Al [wt%].

[0010] The window foil replacement control unit has a main control unit, a roll monitoring unit, and an alarm unit. When the cumulative irradiation amount of the electron beam exceeds a predetermined threshold, the window foil replacement control unit controls the winding of the window foil from the winding roll and the unwinding of the window foil from the unwinding roll. The roll monitoring unit detects the cumulative unwinding amount of the window foil from the unwinding roll. The alarm unit reports information about the unwinding roll based on the cumulative unwinding amount of the window foil detected by the roll monitoring unit. [Effects of the Invention]

[0011] According to the automatic window foil exchange device of the present invention, it is possible to automatically exchange window foils in a vacuum chamber that is irradiated with electron beams in an electron beam irradiation device. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of an electron beam irradiation device equipped with an automatic window foil exchange device according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing a schematic configuration of an automatic window foil replacement device according to an embodiment of the present invention. [Figure 3] 3 is a plan view schematically showing the configuration of the automatic window foil exchange device shown in FIG. 2, viewed from the direction of arrow A3. FIG. [Figure 4] 3 is a block diagram showing a schematic configuration of a window foil replacement control unit corresponding to the window foil replacement process in this embodiment. FIG. [Figure 5] 10 is a flowchart showing an example of the flow of a window foil replacement process executed by a main control unit of the window foil automatic replacement device according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The automatic window foil changer according to the present invention is a device for changing window foil in an electron beam irradiation device. The electron beam irradiation device is a device that irradiates an object with an electron beam to modify or sterilize the object, and is used, for example, for gravure printing and sterilization of PET bottles. However, its uses are not limited to these. The window foil is used to close a window (opening) in a vacuum chamber through which the electron beam passes, maintaining a vacuum state and allowing the electron beam to pass from the inside to the outside of the vacuum chamber (details will be described later).

[0014] 1 to 3 schematically show the configuration of an automatic window foil changer according to this embodiment. FIG. 1 is a cross-sectional view showing an example of a state in which the automatic window foil changer according to this embodiment is fixed to an electron beam irradiation device. FIG. 2 is a cross-sectional view showing an example of the configuration of an automatic window foil changer according to this embodiment. FIG. 3 is a plan view showing the configuration of the automatic window foil changer shown in FIG. 2 from the direction of arrow A3. For convenience, FIG. 3 omits a housing, which will be described later. As shown in FIGS. 1 to 3 , a first direction D1, a second direction D2, and a third direction D3 are defined. These directions D1, D2, and D3 are mutually orthogonal. In this embodiment, as an example, the first direction D1 and the second direction D2 define a horizontal plane. The third direction D3 is a direction along a vertical line (vertical direction). In the illustrated example, the arrow points downward (downward), and the opposite direction points upward (upward). However, the directions and planes defined by D1, D2, and D3 are not limited to the above example.

[0015] 1 and 2, the automatic window foil changer 1 is provided in an electron beam irradiation apparatus 10 and is a device for changing a used window foil 31 for an unused window foil 32 in the electron beam irradiation apparatus 10. For example, the automatic window foil changer 1 may be provided in the electron beam irradiation apparatus 10 from the beginning as one of the functions of the electron beam irradiation apparatus 10, or may be added later as an additional function (option) of the electron beam irradiation apparatus 10.

[0016] Therefore, the electron beam irradiation device 10 will be first described before describing the automatic window foil changer 1. As described above, the automatic window foil changer 1 is configured so that it can be retrofitted to the electron beam irradiation device 10. Therefore, the basic configuration of the electron beam irradiation device 10 may be the same as that of a general electron beam irradiation device that has been used conventionally.

[0017] As shown in FIGS. 1 and 2, the electron beam irradiation device 10 includes, as main components, an electron beam generating unit 12, a chamber unit 14, and an electron beam irradiation window unit 16. The electron beam generating unit 12 includes, for example, a filament 121 that generates an electron beam, and a power supply 122 that supplies power to the filament 121. The filament 121 is heated by the power supplied from the power supply 122 and emits electrons.

[0018] The chamber unit 14 includes, for example, an acceleration tube 141 that accelerates the electron beam generated by the filament 121 of the electron beam generating unit 12 in a vacuum space, and a scan tube 142 that scans the electron beam accelerated by the acceleration tube 141. The acceleration structure 141 has a filament 121 of the electron beam generating unit 12 provided at one end in the tube axis direction (hereinafter referred to as the axial direction), and has a plurality of electrodes arranged toward the other end. One axial end of the acceleration structure 141 where the filament 121 is provided is airtightly closed. In the illustrated example, the axial direction is a direction along the third direction D3. When these electrodes are energized, the acceleration structure 141 generates an electric field that accelerates electrons emitted from the filament 121 toward the other axial end.

[0019] The scan tube 142 is continuous with the other axial end of the acceleration tube 141, and has a scan coil 143 at the continuous location. When the scan coil 143 is energized, the electron beam accelerated by the acceleration tube 141 is deflected. The internal space where the acceleration tube 141 and the scan tube 142 communicate constitutes a vacuum chamber 140 through which electrons emitted from the filament 121 pass as an electron beam. The electron beam passes through the vacuum chamber 140 in the direction indicated by the arrow A10 in FIGS. 1 and 2, for example, downward in the up-down direction (third direction D3), and is irradiated onto an object to be irradiated.

[0020] The electron beam irradiation window 16 is an opening at the axial end of the chamber 14, for example, at the end opposite the connection point between the scan tube 142 and the accelerating tube 141. That is, the electron beam irradiation window 16 is an opening in the chamber 14. The shape of the opening of the electron beam irradiation window 16 is not particularly limited and can be any shape, such as circular, oval, elliptical, or square. In the illustrated example, it is approximately rectangular, specifically, approximately rectangular with its longitudinal axis extending in the direction of movement of the window foil 3 (described later). The electron beam irradiation window 16, or more specifically, the chamber 14, can be closed with the window foil 3. The window foil 3 closes the chamber 14 while allowing electron beams to pass from the inside to the outside of the chamber 14. When the electron beam generated by the electron beam generator 12 is irradiated onto an object to be irradiated, the electron beam irradiation window 16 is closed with the window foil 3, and the inside of the chamber 14 is placed in a vacuum state. The chamber 14 is evacuated, for example, by a vacuum pump or the like.

[0021] Next, the automatic window foil replacement device 1 according to this embodiment will be described. 2 and 3, the automatic window foil changer 1 mainly comprises a window foil change mechanism 2 and a vacuum maintenance mechanism 4. The window foil change mechanism and vacuum maintenance mechanism 4 are attached to a housing 6 and fixed to the electron beam irradiation device 10 via the housing 6. The housing 6 has an opening 61 that communicates with the chamber 14 of the electron beam irradiation device 10, and is fixed to the electron beam irradiation device 10 with a sealing member, in the illustrated example, an O-ring 51, sandwiched between a flange 61a of the opening 61 and the periphery of the electron beam irradiation window 16. In this way, the housing 6 and the electron beam irradiation window 16, or more specifically, the automatic window foil changer 1 and the electron beam irradiation device 10, are airtightly integrated so as to maintain the vacuum in the chamber 14.

[0022] The window foil replacement mechanism 2 is a mechanism for winding up and unwinding the window foil 3 to replace the window foil 3. In this embodiment, the window foil 3 is an extremely thin metal foil whose total length is sufficiently larger than its width and whose thickness is on the order of a few microns. In the illustrated example, the total length is the dimension in the first direction D1, the width is the dimension in the second direction D2, and the thickness is the dimension in the third direction D3.

[0023] The window foil 3 can be made of any material as long as it can close the chamber 14 while allowing the electron beam to pass from the inside to the outside of the chamber 14. In this embodiment, as an example, a β-titanium alloy is used as the material for the window foil 3. Therefore, the window foil 3 is non-magnetic and cannot be attracted by magnetic force. The β-titanium alloy is, for example, an alloy containing titanium (Ti) and a molybdenum (Mo) equivalent of 10 wt% or more. The Mo equivalent is expressed by the following relational expression (1): Mo equivalent = Mo + 0.67 × V + 0.44 × W + 0.28 × Nb + 0.22 × Ta + 2.9 × Fe + 1.6 × Cr - 1.0 × Al [wt%] … (1) In the relational formula (1), V represents vanadium, W represents tungsten, Nb represents niobium, Ta represents tantalum, Fe represents iron, Cr represents chromium, and Al represents aluminum.

[0024] The window foil replacement mechanism 2 includes, as main elements, a take-up roll 21, an unwinding roll 22, a leveling roll 23, and a window foil replacement control unit 24. The winding roll 21 has a winding shaft 211 that winds up the used window foil 31, and the used window foil 31 that has been wound around the winding shaft 211 into a roll. For convenience in the following description, the used window foil 31 wound into a roll will also be referred to as the winding roll 21. The used window foil 31 is a window foil 3 that has been exposed to an electron beam of a predetermined intensity for a predetermined period of time. In this embodiment, the window foil 3 is used in units of an area that blocks the electron beam irradiation window 16. The winding shaft 211 is driven by a predetermined drive device and rotates synchronously with the unwinding shaft 221, which will be described later. For example, the winding shaft 211 rotates in the same direction as the unwinding shaft 221 at approximately the same speed. In the illustrated example, the winding shaft 211 extends in the second direction D2.

[0025] As described above, the window foil 3 is a long, continuous piece of metal foil. Therefore, the portion of the window foil 3 that has moved further back than the electron beam irradiation window 16 in the direction of movement during replacement is the used portion. The portion of the window foil 3 that blocks the electron beam irradiation window 16, i.e., the portion of the window foil 3 through which the irradiated electron beam passes, corresponds to the portion in use. In the following explanation, this used portion will also be referred to as the used window foil 31. The remaining portion of the window foil 3, i.e., the portion located further forward than the electron beam irradiation window 16 in the direction of movement during replacement, is the portion through which the electron beam has not yet passed, and in the following explanation, this portion will be referred to as the unused window foil 32.

[0026] When a predetermined length of the used window foil 31 has been wound onto the winding spindle 211, the used window foil 31 is removed from the winding spindle 211. As a result, the used window foil 31 is wound onto the winding spindle 211 again. The winding roll 21 may have a cylindrical winding core that is inserted into the winding spindle 211 and rotates together with the winding spindle 211. In this case, the used window foil 31 is wound onto the winding core. When a predetermined length of the used window foil 31 has been wound onto the winding core, the used window foil 31 is removed from the winding spindle 211 together with the winding core.

[0027] The unwinding roll 22 has an unwinding shaft 221 that unwinds an unused window foil 32, and the unused window foil 32 is wound around the unwinding shaft 221 to form a roll. In the following description, for convenience, the unused window foil 32 wound in a roll will also be referred to as the unwinding roll 22. The unused window foil 32 is the window foil 3 in a state (initial state) that does not transmit the electron beam. In this embodiment, unused window foil 32 that is unwound from the unwinding roll 22 in area units that block the electron beam irradiation window portion 16 is used. The unwinding shaft 221 is driven by a predetermined drive device and rotates synchronously with the winding shaft 211. For example, the unwinding shaft 221 rotates in the same direction as the winding shaft 211 at approximately the same speed. In the illustrated example, the unwinding shaft 221 extends in the second direction D2 parallel to the winding shaft 211. Of these rotating shafts, for example, the winding shaft 211 may be a main driving shaft (drive shaft) for the unwinding shaft 221, and the unwinding shaft 221 may be a driven shaft.

[0028] When a predetermined length of unused window foil 32 is unwound from the unwinding shaft 221, a new unwinding roll 22 is set. For example, the unused window foil 32 is wound in a roll around the unwinding shaft 221. The unwinding roll 22 may have a cylindrical unwinding core that is inserted into the unwinding shaft 221 and rotates together with the unwinding shaft 221. In this case, the unused window foil 32 is wound around the unwinding core. When a predetermined length of unused window foil 32 is unwound from the unwinding core, the unwinding core is removed from the unwinding shaft 221, and a new unused window foil 32 wound around another unwinding core is set on the unwinding shaft 221.

[0029] The leveling rolls 23 adjust the winding start position of the window foil 3 wound by the winding roll 21 and the unwinding start position of the window foil 3 unwound from the unwinding roll 22 so that their vertical distances from a predetermined reference plane are the same. In other words, the leveling rolls 23 keep the position of the window foil 3 constant in the transmission direction of the electron beam (third direction D3 in the illustrated example) between the winding roll 21 and the unwinding roll 22. The electron beam passes through the window foil 3 in the direction indicated by arrow A1 in FIG. 2 (downward in the vertical direction (third direction D3)) and is irradiated onto the object to be irradiated. In this embodiment, as an example, the reference plane is the installation surface of the electron beam irradiation device 10, specifically, a horizontal plane defined by the first direction D1 and the second direction D2. In other words, the leveling rolls 23 match the winding start position and unwinding start position of the window foil 3 in the vertical direction, which is the third direction D3. As a result, the window foil 3 moves between the take-up roll 21 and the unwinding roll 22 while maintaining a constant height in the vertical direction, that is, while maintaining a horizontal state.

[0030] The leveling rolls 23 rotate in accordance with the window foil 3 moving between the take-up roll 21 and the unwinding roll 22. In the illustrated example, the leveling rolls 23 have a rotating shaft 231 and a cover 232 that covers the periphery of the rotating shaft 231. The rotating shaft 231 extends in the second direction D2 parallel to the take-up shaft 211 and the unwinding shaft 221. The cover 232 is formed, for example, from a resin material, and rotates together with the rotating shaft 231 while contacting the window foil 3. In this embodiment, as an example, the rotating shaft 231 is not a driving shaft (main driving shaft), but a driven shaft that rotates in conjunction with the rotation of the take-up shaft 211 or the unwinding shaft 221. However, the rotating shaft 231 may also be a driving shaft. The leveling rolls 23 may also be composed of a stationary shaft that does not rotate and a rotating cover that rotates around the stationary shaft.

[0031] The leveling rolls 23 form a pair, and the pair of leveling rolls 23a, 23b are arranged between the take-up roll 21 and the unwinding roll 22 in the movement direction of the window foil 3. Of these leveling rolls 23a, 23b, the leveling roll 23a is arranged near the take-up roll 21, and the other leveling roll 23b is arranged near the unwinding roll 22. The leveling roll 23a mainly adjusts the vertical height of the winding start position of the used window foil 31 wound by the winding roll 21. The leveling roll 23b mainly adjusts the vertical height of the unwinding start position of the unused window foil 32 unwound from the unwinding roll 22.

[0032] The window foil replacement control unit 24 executes a process (hereinafter referred to as window foil replacement process) for replacing a used window foil 31 with an unused window foil 32, depending on the cumulative dose of electron beams that pass through the window foil 3 and are irradiated onto the object to be irradiated. In the window foil replacement process, the winding shaft 211 of the winding roll 21 and the unwinding shaft 221 of the unwinding roll 22 are rotated at a predetermined rotation speed to wind up the used window foil 31 and unwind the unused window foil 32, thereby replacing them. In other words, in the window foil replacement process, the window foil replacement control unit 24 controls the winding length of the window foil 3 on the winding roll 21 and the unwinding length of the window foil 3 on the unwinding roll 22, depending on the cumulative dose of electron beams that pass through the window foil 3 and are irradiated onto the object to be irradiated.

[0033] As shown in Fig. 4, the window foil replacement control unit 24, in order to execute the window foil replacement process, includes, for example, a main control unit 241, a roll monitoring unit 242, and an alarm unit 243. Fig. 4 is a block diagram showing a schematic configuration of the window foil replacement control unit 24 corresponding to the window foil replacement process.

[0034] The main control unit 241 includes a CPU, memory, a storage device (non-volatile memory), an input / output circuit, a timer, a display, etc., and executes predetermined arithmetic processing. For example, the main control unit 241 reads various data via the input / output circuit, performs arithmetic processing in the CPU using a program read from the storage device to the memory, and controls the operation of the winding shaft 211 of the winding roll 21 and the unwinding shaft 221 of the unwinding roll 22, etc., based on the processing results.

[0035] The window foil replacement process is coded as a program (window foil replacement process program). This program is stored in, for example, a storage device of the main control unit 241, and is read into the memory and executed by the CPU when the electron beam irradiation device 10 is started up.

[0036] In the window foil replacement process, the main control unit 241 controls the amount of movement of the window foil 3 between the take-up roll 21 and the unwinding roll 22 in accordance with the cumulative dose of electron beams that pass through the window foil 3 and are irradiated onto the object to be irradiated. Specifically, the main control unit 241 controls the winding length of the used window foil 31 on the take-up roll 21 and the unwinding length of the unused window foil 32 on the unwinding roll 22 in accordance with the cumulative dose of electron beams. In this case, the main control unit 241 rotates the take-up shaft 211 to wind a predetermined length of used window foil 31 onto the take-up shaft 211, and rotates the unwinding shaft 221 to unwind a predetermined length of unused window foil 32 from the unwinding shaft 221.

[0037] The predetermined length is, for example, the distance of the electron beam irradiation window 16 in the movement direction of the window foil 3, in other words, the opening length of the electron beam irradiation window 16. In the illustrated example, the first direction D1 corresponds to the movement direction of the window foil 3. The cumulative dose of electron beams is a value calculated, for example, from the intensity of the electron beams irradiated after passing through the window foil 3 and the irradiation time. Therefore, for example, the cumulative dose of electron beams is compared with a predetermined threshold (hereinafter referred to as the replacement reference value), and if the cumulative dose exceeds the replacement reference value, the used window foil 31 is moved a predetermined length between the winding roll 21 and the unwinding roll 22 and replaced with an unused window foil 32. The replacement reference value is set, for example, to about 80% to 90% of the maximum cumulative dose of irradiation allowed for the window foil 3 so that the window foil 3 can be replaced before the end of its life. The replacement reference value is written, for example, to a storage device (non-volatile memory) of the main control unit 241 and is read as a parameter when determining the cumulative electron beam irradiation amount in the window foil replacement process described later, that is, when determining whether the window foil 3 needs to be replaced.

[0038] The roll monitoring unit 242 has an accumulated unwinding amount detection unit 242 a that monitors the unwinding roll 22 . The cumulative unwinding amount detection unit 242a detects the cumulative unwinding amount of unused window foil 32 on the unwinding roll 22. The cumulative unwinding amount is the amount of window foil 32 that has been unwound by the unwinding shaft 221 from a state in which the unused window foil 32 is not unwound. The cumulative unwinding amount detection unit 242a is, for example, a sensor that detects the number of rotations of the unwinding shaft 221 of the unwinding roll 22, a sensor that detects the length of the unused window foil 32 unwound from the unwinding shaft 221, a sensor that detects the remaining thickness (radial dimension) of the unused window foil 32 wound around the unwinding shaft 221, a sensor that detects the weight of the unwinding roll 22, or the like. The operation of the cumulative unwinding amount detection unit 242a is controlled by, for example, the main control unit 241, and information on the detection results is appropriately provided to the main control unit 241 via wire or wirelessly.

[0039] The roll monitoring unit 242 may have an accumulated winding amount detection unit that monitors the winding roll 21 in addition to or instead of the accumulated unwinding amount detection unit 242a. The cumulative winding amount detection unit detects the cumulative winding amount of used window foil 31 on the winding roll 21. The cumulative winding amount is the amount of window foil 31 that has been wound around the winding shaft 211 since the state when no used window foil 31 was wound around it. The cumulative winding amount detection unit is, for example, a sensor that detects the number of rotations of the winding shaft 211 of the winding roll 21, a sensor that detects the winding length and winding thickness (radial dimension) of the used window foil 31 wound around the winding shaft 211, a sensor that detects the weight of the winding roll 21, etc.

[0040] The notification unit 243 notifies predetermined information based on the monitoring results of the unwinding roll 22 by the roll monitoring unit 242. The predetermined information is information related to the unwinding roll 22, such as information urging the replacement of the unwinding roll 22. The notification unit 243 is, for example, a display that displays a message, a speaker that sounds a warning sound, a warning light that emits a predetermined signal, or an alarm device that is any combination of these. The operation of the notification unit 243 is controlled by, for example, the main control unit 241, and notifies predetermined information as appropriate. Note that if the roll monitoring unit 242 has a cumulative winding amount detection unit, the notification unit 243 may notify information related to the winding roll 21, such as information urging the replacement of the winding roll 21, in addition to or instead of the information related to the unwinding roll 22.

[0041] The roll monitoring unit 242 and the notification unit 243 will be described later in the window foil replacement process executed by the main control unit 241. Figure 5 is a flowchart showing an example of the flow of the window foil replacement process executed by the main control unit 241.

[0042] As shown in FIG. 5, in the window foil replacement process, the main control unit 241 acquires the cumulative dose of electron beams on the irradiated object, in other words, the cumulative dose of electron beams passing through the currently used window foil 3 (used window foil 31) (S101). For example, the main control unit 241 detects the dose of electron beams on the irradiated object, calculates the dose of electron beams based on, for example, the intensity and irradiation time of the electron beams, accumulates the values, and stores them in the memory of the main control unit 241. The dose of electron beams on the irradiated object is provided to the main control unit 241 by, for example, the electron beam generator 12 of the electron beam irradiation device 10, and the main control unit 241 calculates the cumulative dose of electron beams based on the provided dose of electron beams. The main control unit 241 transmits and receives predetermined control signals and data signals to and from the electron beam generator 12 via wire or wirelessly.

[0043] When the accumulated dose of the electron beam is acquired, the main control unit 241 compares the accumulated dose of the electron beam stored in the memory with the replacement reference value. The main control unit 241 determines, for example, whether or not the accumulated dose of the electron beam exceeds the replacement reference value (S102). If the accumulated dose of the electron beam does not exceed the replacement reference value (No in S102), that is, if it is less than the replacement reference value, the main control unit 241 repeats this determination. The waiting time (interval) for repeating this determination can be set arbitrarily. For example, the main control unit 241 may constantly repeat the determination of the accumulated dose with the waiting time set to substantially 0 (zero), or may re-determine the accumulated dose after a predetermined waiting time (interval) has elapsed.

[0044] On the other hand, if the cumulative irradiation amount of the electron beam exceeds the replacement reference value (Yes in S102), the main control unit 241 determines whether or not it is necessary to replace the unwinding roll 22. That is, the main control unit 241 determines whether or not it is possible for the unwinding roll 22 to unwind unused window foil 32. If the roll monitoring unit 242 has a cumulative winding amount detection unit, the main control unit 241 may determine whether or not it is necessary to replace the winding roll 21 instead of or in addition to determining whether or not it is necessary to replace the unwinding roll 22. The determination of whether or not it is necessary to replace the winding roll 21 is a determination of whether or not it is possible for the winding roll 21 to wind up used window foil 31.

[0045] The main control unit 241 acquires the cumulative unwinding amount of the unused window foil 32 from the unwinding shaft 221 (S103). The cumulative unwinding amount of the unused window foil 32 is detected by the cumulative unwinding amount detection unit 242a of the roll monitoring unit 242 as described above.

[0046] The main control unit 241 determines whether or not the unwinding roll 22 needs to be replaced based on the acquired cumulative unwinding amount. In determining whether or not the unwinding roll 22 needs to be replaced, the main control unit 241 compares the cumulative unwinding amount of the unused window foil 32 with a predetermined threshold value (hereinafter referred to as the unwinding upper limit value). The main control unit 241 determines, for example, whether or not the cumulative unwinding amount of the unused window foil 32 exceeds the unwinding upper limit value (S104). The unwinding upper limit value is written, for example, in a storage device (non-volatile memory) of the main control unit 241, and is read out as a parameter when determining the cumulative unwinding amount, that is, when determining whether or not the unwinding roll 22 needs to be replaced.

[0047] If the cumulative unwinding amount does not exceed the unwinding upper limit value, that is, if the cumulative unwinding amount is equal to or less than the unwinding upper limit value (No in S104), the main control unit 241 replaces the window foil 3 (S105). In this case, since it is possible to both wind up the used window foil 31 onto the winding roll 21 and unwind an unused window foil 32 onto the unwinding roll 22, replacement of the window foil 3 is performed automatically. At that time, the main control unit 241 rotates the winding shaft 211 of the winding roll 21 to wind up the used window foil 31 by a predetermined length, and rotates the unwinding shaft 221 of the unwinding roll 22 to unwind an unused window foil 32 by a predetermined length. In this way, the used window foil 31 is replaced with an unused window foil 32. When a predetermined length of used window foil 31 is wound up and a predetermined length of unused window foil 32 is unwound and the window foil 3 is replaced, the main control section 241 stops the winding shaft 211 and the unwinding shaft 221.

[0048] When the window foil 3 is replaced, the main control unit 241 resets the cumulative irradiation amount of the electron beam to an initial value (e.g., 0 (zero)) (S106). For example, the main control unit 241 overwrites the cumulative irradiation amount of the electron beam stored in a memory or the like with 0.

[0049] Then, the main control unit 241 starts acquiring the cumulative irradiation amount of the electron beam that passes through the window foil 3 (unused window foil 32) to be used after the replacement in S105 and is irradiated onto the irradiation target (S101). That is, the window foil replacement process for the window foil 3 to be used after the replacement in S105 is newly started.

[0050] On the other hand, if the cumulative unwinding amount exceeds the unwinding upper limit value (Yes in S104), the main control unit 241 issues information urging replacement of the unwinding roll 22 (S107). In this case, the main control unit 241 operates the notification unit 243 to prompt replacement of the unwinding roll 22, for example, by displaying a message on a display, outputting a sound from a speaker, or turning on a warning light. This enables prompt replacement of the unwinding roll 22. Note that a reminder or warning about replacement of the unwinding roll 22 may be issued any number of times before the cumulative unwinding amount exceeds the unwinding upper limit value. This makes it possible to take measures such as preparing a supplementary or replacement unwinding roll 22 before replacement of the unwinding roll 22 becomes necessary.

[0051] When the unwinding roll 22 is replaced, the take-up roll 21 is also replaced. The simultaneous replacement of these rolls is due to the need for certain adjustments in addition to the replacement of each roll. For example, it is necessary to guide the leading end of the unused window foil 32 of the replaced unwinding roll 22 from directly below the seal area with the magnetic fluid 40 (described later) to the replaced take-up roll 21, bite and fix it, and apply an appropriate tension to the window foil 3 to perform leveling adjustments. These operations are performed by returning the vacuum chamber 14 to atmospheric pressure (normal pressure) (opening the chamber to the atmosphere). By always having spare take-up rolls 21 and unwinding rolls 22 on hand, roll replacement and adjustments can be performed quickly.

[0052] When issuing information prompting replacement of the unwinding roll 22, the main control unit 241 determines the operation stop conditions of the automatic window foil changer 1 (S108). The operation stop conditions are conditions for determining whether or not to stop operation of the automatic window foil changer 1. The automatic window foil changer 1 starts operation when the electron beam irradiation device 10 starts operation (starts up), and stops operation when the electron beam irradiation device 10 stops operation (ends). Therefore, the operation stop conditions are determined, for example, based on whether or not the main control unit 241 has received a signal indicating that operation of the electron beam irradiation device 10 is stopped. The signal indicating operation stop is transmitted when a user or the like selects operation stop from the operation panel or remote control of the electron beam irradiation device 10, for example.

[0053] If the operation stop condition is not met (No in S108), the main control unit 241 issues information (hereinafter referred to as operation stop preparation information) urging the user to stop operation (S109). In this case, the winding roll 21 and the unwinding roll 22 need to be replaced and certain adjustment work needs to be performed, so the operation of the automatic window foil exchanger 1 and the electron beam irradiation device 10 needs to be stopped. Therefore, the main control unit 241 notifies the user of the operation stop preparation information until the operation stop condition is met. The operation stop preparation information is information for prompting a user to select operation stop from, for example, an operation panel or a remote control of the automatic window foil exchanger 1 or the electron beam irradiation device 10. When notifying the user of the operation stop preparation information, the main control unit 241 activates the notification unit 243 to, for example, display a message on a display, output a sound from a speaker, or turn on a warning light to prompt the user to stop operation of the automatic window foil exchanger 1 and the electron beam irradiation device 10. Such notification may be repeated, for example, after a predetermined waiting time (interval) has elapsed.

[0054] When the operation shutdown preparation information is notified, the main control unit 241 again determines whether the operation shutdown condition of the automatic window foil exchange device 1 is met (S108). That is, the main control unit 241 repeatedly determines whether the operation shutdown condition is met until the condition is met. The waiting time (interval) for repeating such determinations can be set arbitrarily. For example, the main control unit 241 may constantly repeat the determination of the operation shutdown condition with the waiting time set to substantially 0 (zero), or may re-determine whether the operation shutdown condition is met after a predetermined waiting time (interval) has elapsed.

[0055] When the operation stop condition is met (Yes in S108), the main control unit 241 resets the accumulated unwinding amount of the unwinding roll 22 (S110). For example, the main control unit 241 causes the accumulated unwinding amount detection unit 242a to overwrite the accumulated unwinding amount of unused window foil 32 detected by the accumulated unwinding amount detection unit 242a with 0. If the roll monitoring unit 242 has an accumulated winding amount detection unit, the main control unit 241 resets the accumulated winding amount of the winding roll 21 instead of or in addition to resetting the accumulated unwinding amount of the unwinding roll 22. For example, the main control unit 241 causes the accumulated winding amount detection unit to overwrite the accumulated winding amount of used window foil 31 detected by the accumulated winding amount detection unit with 0.

[0056] Then, the main control unit 241 stops the operation of the automatic window foil changer 1 (S111). At this time, for example, the electron beam generation unit 12 of the electron beam irradiation device 10 stops irradiating the object with an electron beam, and the production line for the object also stops. In other words, the main control unit 241 repeats a series of window foil replacement processes while the electron beam irradiation device 10 and the automatic window foil changer 1 are operating, and ends the series of window foil replacement processes when the operation of the electron beam irradiation device 10 and the automatic window foil changer 1 is stopped. This makes it possible to replace the winding roll 21 and the unwinding roll 22. The winding roll 21 and the unwinding roll 22 may be replaced manually or automatically.

[0057] Such a window foil replacement process is carried out while the vacuum state of the chamber section 14 is maintained. The vacuum maintenance mechanism 4 is a mechanism for maintaining a vacuum state in the chamber 14 of the electron beam irradiation device 10 when the window foil replacement mechanism 2 replaces the window foil 3. In other words, the vacuum state in the chamber 14 is maintained by the vacuum maintenance mechanism 4 while the window foil replacement process described above is being performed. Any mechanism can be used as the vacuum maintenance mechanism 4, but in this embodiment, as an example, a sealing mechanism using a magnetic fluid (magnetic fluid sealing mechanism) is used. As described above, in this embodiment, when the used window foil 31 is replaced with an unused window foil 32, the window foil 3 moves continuously in one direction, i.e., linearly, between the take-up roll 21 and the unwinding roll 22. In other words, in this embodiment, in the chamber 14 where the linearly moving window foil 3 forms the boundary with the atmosphere, a magnetic fluid sealing mechanism is used as a mechanism for maintaining a vacuum state in the chamber 14.

[0058] As shown in FIGS. 2 and 3 , the vacuum maintenance mechanism 4 includes, as its main elements, a permanent magnet 41, a first magnetic member (hereinafter referred to as a pole piece) 42, a non-magnetic member 43, a filter 44, a magnetic fluid server 45, a second magnetic member (hereinafter referred to as a base) 46, an electromagnet 47, and a window foil cooling unit 48. In this embodiment, as an example, the permanent magnet 41, the pole piece 42, the non-magnetic member 43, the filter 44, and the magnetic fluid server 45 of the vacuum maintenance mechanism 4 are modularized, and the module is fixed to a mounting plate 49 by welding or the like. The mounting plate 49 is fixed to the housing 6 with a sealing member, an O-ring 52 in the illustrated example, sandwiched between the mounting plate 49 and the housing 6. As a result, the mounting plate 49 and the housing 6 are integrated together in an airtight manner, or more specifically, capable of maintaining the vacuum of the chamber 14 of the electron beam irradiation device 10.

[0059] The permanent magnets 41 are composed of, for example, iron (Fe), cobalt (Co), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), and samarium (Sm) as part or all of their raw materials. The permanent magnets 41 are annular and surround the outer periphery of the electron beam irradiation window 16 of the electron beam irradiation device 10. In the illustrated example, five permanent magnets 41 are arranged concentrically with the center of the opening of the electron beam irradiation window 16, spaced apart, and in series in the direction of radiation. The center of the opening of the electron beam irradiation window 16 is the intersection of the diagonals of a substantially rectangular shape. For example, if the opening shape is circular or elliptical, it is the center of the circle; if the opening shape is elliptical, it is the intersection of the major and minor axes; and if the opening shape is square, it is the intersection of the diagonals as with a rectangle.

[0060] By arranging the five permanent magnets 41 concentrically with the opening center of the electron beam irradiation window 16 in this manner, the five permanent magnets 41 are arranged on both sides of the electron beam irradiation window 16 of the electron beam irradiation device 10 in the direction of movement of the window foil 3 (first direction D1 in the illustrated example), with the pole piece 42, non-magnetic member 43, and pole piece 42 sandwiched between them. That is, these permanent magnets 41 are arranged so that their magnetic pole faces are aligned in the direction of movement of the window foil 3. One side of the electron beam irradiation window 16 is the side where used window foil 31 is wound up, and the other side is the side where unused window foil 32 is unwound. Hereinafter, one side of the electron beam irradiation window 16 in the direction of movement of the window foil 3 is referred to as the winding side, and the other side is referred to as the unwinding side. The number of permanent magnets 41 to be arranged is not limited to five as in the illustrated example, but can be arbitrarily set depending on the required number of sealing locations with the magnetic fluid 40 (described later), i.e., the desired sealing performance.

[0061] The pole pieces 42 are made of any magnetic material and, like the permanent magnets 41, are annular in shape surrounding the outer periphery of the electron beam irradiation window 16 of the electron beam irradiation device 10. The pole pieces 42 are attracted to the magnetic pole faces of the permanent magnets 41 by magnetic force. In other words, the pole pieces 42 are arranged in pairs with the permanent magnets 41. In this embodiment, the pole pieces 42 protrude forward in the transmission direction of the electron beam in the window foil 3 (downward in the up-down direction (third direction D3)) beyond the permanent magnets 41.

[0062] In the illustrated example, a pole piece 42 is attached to the magnetic pole face of each of the five permanent magnets 41. That is, ten pole pieces 42 in total, each consisting of two pole pieces, are arranged to surround the outer periphery of the electron beam irradiation window 16. In the movement direction of the window foil 3 (first direction D1 in the illustrated example), ten pole pieces 42 are arranged attached to the magnetic pole faces of the five permanent magnets 41 on the winding side, and ten pole pieces 42 are arranged attached to the magnetic pole faces of the five permanent magnets 41 on the unwinding side.

[0063] The non-magnetic member 43 is made of any non-magnetic material and is interposed between adjacent pole pieces 42. As a result, the magnetic forces of different permanent magnets 41 are applied to each of the adjacent pole pieces 42 sandwiching the non-magnetic member 43. The non-magnetic member 43 forms a ring shape concentric with the adjacent pole pieces 42 and is located between the adjacent pole pieces 42. In the illustrated example, one non-magnetic member 43 is disposed between each of the five adjacent pairs of pole pieces 42, for a total of four non-magnetic members 43. One pair of pole pieces 42 is made up of two pole pieces 42 attracted to the magnetic pole faces of one permanent magnet 41.

[0064] The filter 44 is made of, for example, an air-permeable ceramic and prevents a decrease in the sealing performance of the magnetic fluid 40 (described later) when the chamber 14 of the electron beam irradiation device 10 is evacuated. For example, if viscous convection of air occurs when the chamber 14 begins to be evacuated, the magnetic fluid 40 may be destroyed depending on the extent of the convection, thereby decreasing the sealing performance of the magnetic fluid 40. For this reason, in this embodiment, when the chamber 14 is evacuated, exhaust (evacuation) is performed only through the filter 44. Furthermore, when the vacuum chamber 14 is returned to atmospheric pressure (normal pressure) (opened to the atmosphere), purge gas is filled only through the filter 44. Therefore, the filter 44 is disposed in the exhaust path when the chamber 14 is evacuated and in the purge gas filling path when the chamber 14 is opened to the atmosphere from the vacuum state.

[0065] The filter 44 has an annular shape surrounding the outer periphery of the electron beam irradiation window 16 of the electron beam irradiation device 10 and is disposed inside the electron beam irradiation window 16 relative to the sealing area of the magnetic fluid 40, which will be described later. In the illustrated example, the filter 44 is disposed in one of the five pole pieces 42 (hereinafter referred to as the innermost pole piece pair) 42a, which is disposed inside the electron beam irradiation window 16. For example, each of the innermost pole piece pairs 42a is provided with a through hole 421, into which the filter 44 is inserted. An airtight seal member is interposed between the filter 44 and the through hole 421 to maintain the vacuum state of the chamber 14. The through hole 421 serves as an exhaust path when the chamber 14 is evacuated and as a filling path for a purge gas when the chamber 14 is opened to the atmosphere from the vacuum state.

[0066] The magnetic fluid server 45 stores the refill magnetic fluid 40 and automatically replenishes the magnetic fluid 40 when the magnetic fluid 40 adsorbed to one end of the pole piece 42 is consumed. In other words, the magnetic fluid server 45 supplies the magnetic fluid 40 to one end of the pole piece 42.

[0067] The magnetic fluid 40 is a liquid or sol sealing material that is attracted by magnetic force to prevent gas leakage, and is a magnetic liquid or sol with a base liquid such as water or oil. The magnetic fluid 40 is attracted to one end of the pole piece 42 by the magnetic force of the permanent magnet 41. The one end of the pole piece 42 is the front end of the window foil 3 in the direction of transmission of the electron beam (the lower end in the up-down direction (third direction D3)). Therefore, the magnetic fluid 40 is continuous in a ring shape so as to surround the outer periphery of the electron beam irradiation window 16 of the electron beam irradiation device 10.

[0068] In the illustrated example, the magnetic fluid 40 adsorbed to one end of each of the ten pole pieces 42 is arranged so as to surround the outer periphery of the electron beam irradiation window portion 16. In the movement direction of the window foil 3 (first direction D1 in the illustrated example), the magnetic fluid 40 adsorbed to one end of each of the ten pole pieces 42 on the winding side is arranged, and the magnetic fluid 40 adsorbed to one end of each of the ten pole pieces 42 on the unwinding side is arranged.

[0069] These magnetic fluids 40 are in airtight contact with the window foil 3 around the outer periphery of the electron beam irradiation window 16. That is, the locations where these magnetic fluids 40 come into contact with the window foil 3 are the sealed locations of each magnetic fluid 40. In the illustrated example, the magnetic fluids 40 come into contact with the window foil 3 at ten locations on the winding side and at ten locations on the unwinding side. Therefore, the chamber 14 of the electron beam irradiation device 10 is sealed at ten locations on the winding side and at ten locations on the unwinding side. In FIG. 2, these ten sealed locations are collectively shown as a sealed region 40a. The number of sealed locations, i.e., the number of contact points between the magnetic fluids 40 and the window foil 3, is set arbitrarily depending on the degree of vacuum required in the chamber 14. That is, it is sufficient that the number of permanent magnets 41 and pole pieces 42 corresponding to the desired degree of vacuum are arranged, and the magnetic fluid 40 is attracted to one end of the pole pieces 42.

[0070] There is no particular limitation on the method of replenishing the magnetic fluid 40 from the magnetic fluid server 45. In the present embodiment, as an example, the magnetic fluid server 45 replenishing the magnetic fluid 40 by capillary action. However, the magnetic fluid server 45 may also replenishing the magnetic fluid 40 using a pump device, a spraying device, or the like.

[0071] In the illustrated example, the magnetic fluid 40 is supplied from the magnetic fluid server 45 to the magnetic fluid 40 adsorbed to one end of each of ten pole pieces 42 arranged to surround the outer periphery of the electron beam irradiation window 16. Specifically, the magnetic fluid server 45 appropriately supplies magnetic fluid 40 to one end of the pole piece 42 from which the magnetic fluid 40 has been consumed. Therefore, the sealing performance of the sealing points formed by the magnetic fluid 40 surrounding the outer periphery of the electron beam irradiation window 16 is always maintained appropriately. This makes it possible to maintain the chamber 14 of the electron beam irradiation device 10 in a desired vacuum state.

[0072] The underlay 46 is made of any magnetic material and has a ring shape that surrounds the outer periphery of the electron beam irradiation window 16 of the electron beam irradiation device 10, with the window foil 3 interposed between the underlay 46 and the magnetic fluid 40. The underlay 46 is arranged on the opposite side of the window foil 3 from the magnetic fluid 40. As a result, the magnetic fluid 40 and the underlay 46 are attracted to each other with the window foil 3 in between. The magnetic fluid 40 and the underlay 46 attract each other, causing them to come into close contact with the window foil 3 at the sealing locations. The magnetic fluid 40 side of the window foil 3 is the vacuum side that communicates with the chamber 14 of the electron beam irradiation device 10, and the underlay 46 is located on the atmosphere side of the window foil 3.

[0073] At this time, the magnetic fluid 40 comes into close contact with the rear surface 3a of the window foil 3 in the direction of transmission of the electron beam. On the other hand, the underlay 46 comes into close contact with the front surface 3b of the window foil 3 in the direction of transmission of the electron beam. In the illustrated example, the surface 3a of the window foil 3 is the upper surface in the vertical direction (third direction D3), and the surface 3b is the lower surface. The upper surface 46a of the underlay 46 (the rear surface of the window foil 3 in the direction of transmission of the electron beam) comes into close contact with the surface 3b, which is the lower surface of the window foil 3.

[0074] The electromagnet 47 is arranged on the side of the underlay 46 opposite to the side that comes into contact with the window foil 3, and attracts the magnetic fluid 40 by magnetic force via the window foil 3 and the underlay 46, which is made of magnetic material. In the illustrated example, the electromagnet 47 is arranged on the underside 46b of the underlay 46 (the surface of the window foil 3 that faces forward in the direction of transmission of the electron beam). The electromagnet 47 is annular, with a magnetic pole face (magnetic field) that extends over substantially the entire underside 46b of the underlay 46. As a result, the electromagnet 47 applies a magnetic force to substantially the entire underside 46b of the underlay 46.

[0075] Here, depending on the material and surface properties of the window foil 3, for example, friction between the window foil 3 and the magnetic fluid 40 may become so great that when the window foil 3 moves between the take-up roll 21 and the unwinding roll 22, the magnetic fluid 40 may be dragged by the window foil 3 and move along with the window foil 3. As described above, when the window foil 3 moves, the magnetic fluid 40 and the underlay 46 are attracted to each other via the window foil 3 by the magnetic force of the permanent magnet 41, and the magnetic fluid 40 is attracted to the magnetic fluid 40 by the magnetic force of the electromagnet 47. Therefore, the magnetic fluid 40 can be fixed to the underlay 46, and the magnetic fluid 40 can be prevented from being dragged by the moving window foil 3.

[0076] When a used window foil 31 is replaced with an unused window foil 32, the window foil cooling unit 48 cools the used window foil 31 and the unused window foil 32 that is continuous with the used window foil 31. When an electron beam is irradiated onto an object to be irradiated, the electron beam passes through the window foil 3, but not all of the electron beam passes through; some of the electron beam remains on the window foil 3. This causes the temperature of the used window foil 31 to rise. For example, when the electron beam is irradiated under conditions of high acceleration voltage, the temperature of the used window foil 31 becomes very high. If the window foil 3 is wound around the winding shaft 211 while still in this high-temperature state, the high-temperature window foil 3 heats the magnetic fluid 40. If the magnetic fluid 40 is excessively heated, the base liquid of the magnetic fluid 40 may heat up, increase in temperature, and evaporate, which may reduce the sealing ability of the magnetic fluid 40.

[0077] The window foil cooling section 48 cools the window foil 3 when the window foil 3 is replaced, thereby preventing a decrease in the sealing performance of the magnetic fluid 40. Therefore, the movement speed of the window foil 3 from the unwinding side to the winding side when the window foil 3 is replaced is adjusted to a speed that can ensure a cooling time sufficient for the window foil 3 to be properly cooled by the window foil cooling section 48. In other words, the rotation speeds of the winding shaft 211 of the winding roll 21 and the unwinding shaft 221 of the unwinding roll 22 are adjusted to a speed that can properly cool the window foil 3.

[0078] The cooling mechanism of the window foil cooling unit 48 is not particularly limited as long as it can cool the window foil 3 to a temperature that does not reduce the sealing ability of the magnetic fluid 40. For example, a water-cooled cooling mechanism having a heat absorption panel made of copper, aluminum, or the like that absorbs heat by coming into contact with the window foil 3, or an air-cooled cooling mechanism having a nozzle that sprays cooling gas or the like toward the window foil 3, can be used as the window foil cooling unit 48. In the present embodiment, an example in which a water-cooled cooling mechanism is used is illustrated as an example. In the illustrated example, the window foil cooling unit 48 cools the window foil 3 by bringing a heat absorption panel into contact with the surface 3b, which is the underside of the window foil 3.

[0079] The window foil cooling unit 48 is annular and surrounds the outer periphery of the electron beam irradiation window 16 of the electron beam irradiation device 10, with the window foil 3 interposed between the window foil cooling unit 48 and the electron beam irradiation window 16. The window foil cooling unit 48 is disposed further inward with respect to the electron beam irradiation window 16 than the module consisting of the permanent magnet 41, pole piece 42, non-magnetic member 43, and magnetic fluid server 45. As a result, the window foil cooling unit 48 cools, from the atmosphere side, the vicinity of the portion of the window foil 3 through which the electron beam irradiated onto the irradiation object passes.

[0080] That is, the area where the window foil 3 is cooled by the window foil cooling unit 48 (hereinafter referred to as the window foil cooling area) is located inside the sealing area by the magnetic fluid 40, and is outside the sealing area. Therefore, in the window foil cooling area, a pressing force is applied to the window foil 3 by a predetermined pressing member 50. The application of a pressing force from the pressing member 50 to the window foil 3 prevents the window foil cooling area of the window foil 3 from rippling or wrinkling when the window foil 3 moves. Any pressing member 50 can be used as long as it can prevent such waviness and wrinkling. In this embodiment, an example in which a spring (coil spring) is used is illustrated as an example.

[0081] In the illustrated example, the pressing member 50 presses the window foil cooling portion 48 toward the window foil 3, thereby pressing the window foil cooling portion 48 against the window foil 3, thereby applying a pressing force to the window foil 3 via the window foil cooling portion 48. Therefore, the pressing member 50 applies an upward pressing force to the surface 3b, which is the lower surface of the window foil 3.

[0082] In this embodiment, the window foil 3 moves between the take-up roll 21 and the unwinding roll 22 while being kept horizontal by the leveling rolls 23. At this time, the leveling rolls 23 apply a downward pressing force to the surface 3a, which is the upper surface of the window foil 3. For this reason, the pressing member 50 applies an upward pressing force to the window foil 3 in accordance with the downward pressing force applied by the leveling rolls 23, i.e., a force in the opposite direction to the pressing force applied by the pressing member 50 to the window foil 3. In this way, an appropriate tension is applied to the window foil 3 so that its posture during movement is kept horizontal.

[0083] The automatic window foil changer 1 according to this embodiment provides the following advantageous effects. The automatic window foil changer 1 includes a window foil changer mechanism 2, in which a used window foil 31 is wound around a winding shaft 211 to form the winding roll 21, and an unused window foil 32 is wound around a winding shaft 221 to form the unwinding roll 22. Therefore, by appropriately setting the winding roll 21 and the unwinding roll 22, the window foil 3 in use can be automatically replaced with an unused window foil 32 when the cumulative dose of electron beams irradiated through and passing through the window foil 3 exceeds the replacement reference value. The replacement reference value can be set to, for example, approximately 80% to 90% of the maximum cumulative dose of irradiation permitted for the window foil 3, so that the window foil 3 can be automatically replaced before the end of its life. This allows the window foil 3 to continue to be used appropriately. This allows the electron beam irradiation of the irradiated object to be appropriately repeated.

[0084] Additionally, the automatic window foil changer 1 includes a vacuum maintenance mechanism 4 that maintains a vacuum state in the chamber 14 of the electron beam irradiation device 10. In the vacuum maintenance mechanism 4, a magnetic fluid 40 is in airtight contact with the window foil 3 around the outer periphery of the electron beam irradiation window 16, sealing the chamber 14. This allows the magnetic fluid 40 to maintain airtight contact with the window foil 3 even when the window foil 3 moves between the take-up roll 21 and the unwinding roll 22 during replacement of the used window foil 31 with an unused window foil 32. Therefore, the vacuum state in the chamber 14 can be appropriately maintained during replacement of the window foil 3. In other words, the window foil 3 can be replaced while maintaining the vacuum state in the chamber 14. This allows the electron beam irradiation device 10 to operate continuously, except when it is stopped for, for example, periodic inspection or repair. As a result, the electron beam irradiation of the irradiated object can be continued.

[0085] Therefore, for example, when replacing the window foil 3 as in the conventional method, there is no need to temporarily stop the electron beam irradiation device 10 and return the chamber 14 from a high vacuum state to atmospheric pressure. Therefore, it is not necessary to stop the production line to replace the window foil 3.

[0086] As described above, according to the automatic window foil exchange device 1 of this embodiment, the electron beam irradiation device 10 can be operated continuously with almost no interruption, thereby improving productivity.

[0087] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. Such novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims. [Explanation of symbols]

[0088] 1... window foil automatic exchange device, 2... window foil exchange mechanism, 3... window foil, 3a... window foil surface (upper surface), 3b... window foil surface (lower surface), 4... vacuum maintenance mechanism, 6... housing, 10... electron beam irradiation device, 12... electron beam generation unit, 14... chamber unit, 16... electron beam irradiation window unit, 21... take-up roll, 22... unwinding roll, 23, 23a, 23b... leveling roll, 24... window foil exchange control unit, 25... window foil cooling unit, 31... used window foil, 32... unused window foil, 40... magnetic fluid, 40a... sealing area, 41... permanent magnet, 42... first magnetic member (pole piece), 43... non-magnetic member, 44... filter, 45... magnetic fluid server, 46... second Magnetic member (underlay), 46a...upper surface of second magnetic member (underlay), 46b...lower surface of second magnetic member (underlay), 47...electromagnet, 48...window foil cooling section, 49...mounting plate, 50...pressure member, 51, 52...O-rings, 61...opening, 61a...flange, 121...filament, 122...power supply, 140...vacuum chamber, 141...acceleration tube, 142...scan tube, 143...scanning coil, 211...winding shaft, 221...unwinding shaft, 231...rotating shaft, 232...cover, 241...main control section, 242...roll monitoring section, 242a...cumulative unwinding amount detection section, 243...alarm section, D1...first direction, D2...second direction, D3...third direction.

Claims

1. 1. An apparatus for replacing a window foil in an electron beam irradiation apparatus including a vacuum chamber through which an electron beam passes to be irradiated onto an irradiation target, and a window foil that closes an opening of the chamber to allow the electron beam to pass from the inside to the outside of the chamber, a window foil replacement mechanism that winds and unwinds the window foil to replace the window foil; The window foil replacement mechanism includes: a winding roll for winding the window foil; an unwinding roll that unwinds the window foil; a leveling roll that keeps the position of the window foil constant in the transmission direction of the electron beam between the winding roll and the unwinding roll; a window foil replacement control unit that controls the winding length of the window foil on the winding roll and the unwinding length of the window foil on the unwinding roll in accordance with the cumulative irradiation amount of the electron beam that passes through the window foil and is irradiated onto the object to be irradiated. Automatic window foil replacement device.

2. a vacuum maintaining mechanism for maintaining a vacuum state of the chamber when the window foil replacement mechanism replaces the window foil; The vacuum maintenance mechanism includes: at least one permanent magnet arranged in series; a first magnetic member magnetically attracted to each pole face of the at least one permanent magnet; a non-magnetic member interposed between adjacent first magnetic members; a magnetic fluid server that supplies a magnetic fluid to one end of the first magnetic member in a transmission direction of the electron beam; a second magnetic member that is disposed on the opposite side of the window foil from the magnetic fluid and that is in contact with the window foil; 2. The automatic window foil changing device according to claim 1.

3. the vacuum maintenance mechanism has a window foil cooling unit that cools the window foil when the window foil is replaced, The window foil replacement control unit controls the winding of the window foil by the winding roll and the unwinding of the window foil by the unwinding roll so that the window foil can be cooled to a predetermined temperature by the window foil cooling unit when the window foil is replaced.

3. The automatic window foil changing device according to claim 2.

4. The vacuum maintaining mechanism has an electromagnet that is disposed on the opposite side of the second magnetic member from the side that contacts the window foil, and that attracts the magnetic fluid by magnetic force via the window foil and the second magnetic member.

3. The automatic window foil changing device according to claim 2.

5. The vacuum maintaining mechanism has a filter disposed in an exhaust path when the chamber is placed in a vacuum state and in a filling path of a purge gas when the chamber is released from the vacuum state to the atmosphere.

3. The automatic window foil changing device according to claim 2.

6. the window foil is made of a β-type titanium alloy; The β-type titanium alloy is an alloy containing titanium (Ti) and a molybdenum (Mo) equivalent of 10 wt% or more, The Mo equivalent is expressed by the following relational expression: Mo+0.67×V+0.44×W+0.28×Nb+0.22×Ta+2.9×Fe+1.6×Cr−1.0×Al [wt %] 6. An automatic window foil changing device according to claim 1.

7. The window foil replacement control unit a main control unit that controls the winding of the window foil onto the winding roll and the unwinding of the window foil onto the unwinding roll when the cumulative irradiation amount of the electron beam exceeds a predetermined threshold; a roll monitoring unit that detects an accumulated amount of the window foil unwound from the unwinding roll; a notification unit that notifies information about the unwinding roll based on the cumulative unwinding amount of the window foil detected by the roll monitoring unit.

7. An automatic window foil changing device according to claim 6.

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