Patent ID: 12230413

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding elements will be denoted by the same reference signs and redundant description will be omitted.

An electron beam emission device1shown inFIG.1is used for, for example, ink curing, sterilizing, or surface reforming on an irradiation target by irradiating the irradiation target with electron beams EB. Hereinafter, an electron beam emitting side (a side of a window9) which is a side from which the electron beams EB are emitted by the electron beam emission device1will be described as a “front side.”

As shown inFIGS.1to3, the electron beam emission device1includes a filament unit (an electron beam generation source)2, a vacuum container (a main body)3, a cathode holding member4, a cathode holding member5, a rail6, a high voltage introduction insulation member7, an insulation support member8, and a window (an electron extraction part)9. The filament unit2is an electron beam generation unit that generates the electron beams EB. Further, the filament unit2is a long unit.

The vacuum container3is formed of a conductive material such as a metal. The vacuum container3has a substantially cylindrical shape. The vacuum container3forms a vacuum space R having a substantially circular column shape inside. The filament unit2is disposed inside the vacuum container3in an axial direction (a major axis direction) of the vacuum space R having a substantially circular column shape. An opening3athrough which the vacuum space R and an external space communicate with each other is provided at a position on the front side in the vacuum container3with respect to the filament unit2. The window9is fixed to the opening3ato be vacuum-sealed.

The window9includes a window material9aand a support9b. The window material9ais formed in a thin film shape. As a material of the window material9a, a material having excellent transparency for the electron beams EB (for example, beryllium, titanium, aluminum, or the like) is used. The support9bis disposed on a side of the vacuum space R of the window material9aand supports the window material9a. The support9bis a mesh-like member and has a plurality of holes through which the electron beams EB pass.

An exhaust port3bfor exhausting air in the vacuum container3is provided at a position on a rear side in the vacuum container3with respect to the filament unit2. A vacuum pump (not shown) is connected to the exhaust port3b, and the air in the vacuum container3is discharged by the vacuum pump. As a result, the inside of the vacuum container3becomes the vacuum space R. In both ends of the vacuum container3having a substantially cylindrical shape, an opening3con the other side and an opening3don one side are closed by a flange7aof the high voltage introduction insulation member7and a lid3e, respectively.

A pair of cathode holding members4and5that have a cathode potential are disposed in the vacuum container3. The rail6which has a cathode potential and also serves as a surrounding electrode that surrounds the filament unit2is provided between the cathode holding member4on the other side and the cathode holding member5on one side. The rail6is a conductive and long member having a substantially C-shaped cross section. The rail6is disposed such that an opening having a substantially C-shaped cross section faces the front side (a side of the window9). The rail6holds the filament unit2in an inside portion (an inside space). For example, the filament unit2is held in the rail6by being inserted into the inside of the rail6through insertion holes provided in the cathode holding member5and the insulation support member8in a state where the lid3eof the vacuum container3is removed.

The high voltage introduction insulation member7is provided at an end of the vacuum container3on a side of the opening3con the other side. The other end of the high voltage introduction insulation member7projects to the outside of the vacuum container3through the opening3c. The high voltage introduction insulation member7has the flange7aprotruding outward in a radial direction thereof and seals the opening3cof the vacuum container3. The high voltage introduction insulation member7is formed of an insulation material (for example, an insulation resin such as an epoxy resin, ceramic, or the like). The cathode holding member4holds one end of the high voltage introduction insulation member7in a state where the cathode holding member4is electrically insulated from the vacuum container3which has a ground potential.

Further, the high voltage introduction insulation member7is a high withstand voltage type connector for receiving supply of a high voltage from a power source device outside the electron beam emission device1. A plug (not shown) for supplying a high voltage from the power source device is inserted into the high voltage introduction insulation member7. An internal wiring for supplying a high voltage supplied from the outside to the filament unit2and the like is provided inside the high voltage introduction insulation member7. This internal wiring is covered with an insulation material constituting the high voltage introduction insulation member7, and insulation with respect to the vacuum container3is ensured.

The insulation support member8is provided at an end of the vacuum container3on a side of the opening3don the one side (an end on a side of the lid3e). The insulation support member8is formed of an insulation material (for example, an insulation resin such as an epoxy resin, ceramic, or the like). The cathode holding member5holds the other end of the insulation support member8in a state where the cathode holding member5is electrically insulated from the vacuum container3.

As shown inFIGS.3to5, the filament unit2is configured as one unit to be attachable to and detachable from the rail6. The filament unit2includes a filament (an electron discharge part)10, a main frame (a frame)11, a grid electrode12, a sub frame13, a power supply line14, a guide member15, a terminal holding member16, a filament fixing member17, and a tension holding unit20.

The main frame11is a long member having a substantially U-shaped (C-shaped) cross section. The main frame11is disposed such that an opening having a substantially U-shaped cross section faces the front side (a side of the window9). The filament fixing member17is provided at the other end of the main frame11in the inside (an inside space) of the main frame11. Further, the tension holding unit20is provided at one end of the main frame11in the inside (the inside space) of the main frame11.

The filament10is an electron discharge part that discharges electrons that become the electron beams EB when heated by energization. The filament10is a linear member and extends on a desired axis L extending from one side to the other side. The filament10is formed of a metal material having a high melting point, for example, a material containing tungsten as a main component. One end of the filament10is connected to the tension holding unit20. The other end of the filament10is connected to the filament fixing member17. As described above, the main frame11supports the tension holding unit20connected to the one end of the filament10and the filament fixing member17connected to the other end of the filament10.

The terminal holding member16is attached to the other end of the main frame11. The terminal holding member16holds a filament terminal T1for supplying a current for the filament10to discharge electrons, a high voltage terminal T2for supplying a cathode potential to the filament unit2, and a grid electrode terminal T3for supplying an applied voltage to the grid electrode12in a state where the terminals T1, T2, and T3are electrically insulated from each other. The filament terminal T1is connected to the other end of the power supply line14. The high voltage terminal T2is electrically connected to the filament fixing member17.

The sub frame13is a long member having a substantially U-shaped cross section. The sub frame13is disposed parallel to the main frame11. The power supply line14is connected to the tension holding unit20from a connection position with the filament terminal T1through the inside (an inside space) of the sub frame13. The sub frame13has a protective function for the power supply line14. The main frame11and the sub frame13are connected to each other by a plurality of guide members15. An outer surface of the guide member15is slidably in contact with an inner surface of the rail6.

The grid electrode12is disposed on the front side with respect to the filament10and is supported by the guide member15via an insulation member18. A plurality of holes are formed in the grid electrode12(seeFIG.4and the like). The grid electrode12is electrically connected to the grid electrode terminal T3via a wiring (not shown).

The tension holding unit20holds tension of the filament10. Here, the tension holding unit20can hold the tension of the filament10by pressing or pulling a movable body connected to the one end of the filament10by a spring. In the present embodiment, the tension holding unit20holds the tension of the filament10by pulling the movable body by the spring. The tension holding unit20is attached to the main frame11in a state where the tension holding unit20is electrically insulated from the main frame11via an insulation member or the like. One end of the power supply line14is connected to the tension holding unit20. The tension holding unit20can supply the electric power supplied via the power supply line14to the filament10while holding the tension of the filament10.

The filament unit2is inserted into the inside (the inside space) of the rail6through the insertion holes provided in the cathode holding member5and the insulation support member8with the other end provided with the filament terminal T1or the like as a head and is fixed thereto. At a position where the filament unit2has been inserted, tip ends of the filament terminal T1, the high voltage terminal T2, and the grid electrode terminal T3are in contact with tip ends of three connection terminals provided in the high voltage introduction insulation member7. As a result, the filament terminal T1and the like are electrically connected to the connection terminals provided in the high voltage introduction insulation member7.

The filament10discharges electrons when a high negative voltage such as minus several tens of kV to minus several hundreds of kV is applied in a state where the filament10is heated by energization. A predetermined voltage is applied to the grid electrode12. For example, a voltage on a positive side of about 100 V to 150 V with respect to the negative voltage applied to the filament10may be applied to the grid electrode12. The grid electrode12forms an electric field for drawing out electrons and curbing diffusion of the electrons. As a result, the electrons discharged from the filament10are emitted to the front side as the electron beams EB from the holes provided in the grid electrode12.

Next, the details of the tension holding unit20for holding the tension of the filament10will be described with reference toFIGS.6and7. In the following description, for convenience of explanation, a side (the other side) on which the filament10is provided with respect to the tension holding unit20is referred to as a “left side,” and a side (one side) on which the tension holding unit20is provided with respect to the filament10is referred to as a “right side.” That is, a left-right direction is a direction along the axis L extending from the one side to the other side.

As shown inFIGS.6and7, the tension holding unit20includes a movable body (a movable part)21, a housing (a support part, a housing part)22, a spring (a tension holding part)23, and a foil material (a power supply path part)24. The movable body21is connected to the one end of the filament10. The movable body21has a circular column21aand a connection part21b. The circular column21ahas a circular column shape extending in the left-right direction. The one end of the filament10is fixed to an end of the circular column21aon the left side. As a method for fixing the circular column21aand the filament10to each other, various methods can be adopted. The connection part21bis connected to an end of the circular column21aon the right side. The other end of the spring23and the other end of the foil material24are connected to the connection part21b. The movable body21is formed of a conductive material. The movable body21is formed of, for example, a material such as stainless steel, copper, or a copper alloy.

The movable body21is provided on the axis L. A state in which the movable body21is provided on the axis L is a disposition state in which the axis L is positioned inside an outer edge of the movable body21when viewed from the direction along the axis L. The same intention applies to a state in which other members are provided on the axis L. Further, the movable body21may be disposed such that a position of a center of gravity of the movable body21is positioned on the axis L.

The housing22is a box body having an accommodation space (an internal space) S inside. The spring23, the foil material24, and the end of the movable body21on the right side are accommodated in the accommodation space S of the housing22. The housing22may be constituted by a box part22ahaving an open surface such that the spring23and the like can be accommodated in the accommodation space S and a lid22bcovering an opening of the box part22a. A guide hole (a movable part holding part)22dis provided in a filament side wall22c(a wall on the left side which constitutes the housing22) which is a wall of the housing22on a side of the filament10(the other side). The guide hole22dextends along the axis L. Further, the guide hole22dis a through hole having a circular column shape extending along the axis L. A diameter of the guide hole22dis larger than a diameter of the circular column21aof the movable body21by a desired value. The guide hole22dguides the circular column21aof the movable body21to be movable along the axis L. That is, the housing22holds the movable body21to be movable along the axis L by the guide hole22d.

A power supply line connection part22fto which the one end of the power supply line14is connected is provided in a power supply side wall22e(a wall on the right side constituting the housing22) which is a wall on a side (the one side) opposite to a side of the filament10in the housing22. For example, the end of the power supply line14is electrically connected to the housing22by a bolt at the power supply line connection part22f. As a result, the housing22is electrically connected to a power source device (a power supply device) that supplies power to the filament10via the power supply line14and the like. The housing22is formed of a conductive material. The housing22is formed of, for example, a material such as stainless steel, copper, or a copper alloy.

The spring23is accommodated in the accommodation space S of the housing22. The spring23is provided on the axis L. The other end of the spring23is connected to an end of the connection part21bon the right side. A connection position between the spring23and the connection part21bis positioned on the axis L. One end of the spring23is connected to the power supply side wall22eof the housing22. The housing22covers the spring23such that the spring23cannot be seen directly from the filament10. A connection position (a connection portion) between the spring23and the movable body21is positioned in the accommodation space S.

The spring23is a tension spring. The spring23applies a tensile force to the movable body21such that the movable body21moves along the axis L. That is, the spring23pulls the movable body21in one side direction along the axis L from the connection position to the movable body21. The movable body21connects the one end of the filament10and the other end of the spring23to each other. As a result, the spring23pulls the filament10via the movable body21by applying a tensile force to the movable body21and holds the tension of the filament10. The spring23is formed of, for example, a material such as stainless steel or Inconel. The spring23may be formed of a material which is different from the filament10. A load of the spring23needs to be in a desired range during an operation (when the filament10is energized), and if the load deviates from that range, problems such as loosening, plastic deformation, and disconnection of the filament10may occur. Therefore, when the load of the spring23is Fa, an allowable tensile load of the filament10is Fx, and the sum of a weight and a frictional force of the movable body21is Fy, a relationship of Fx+Fy>Fa needs to be established. Further, it should be noted that the heating of the filament10by energization causes a relationship of the allowable tensile load of the filament10, that is, the allowable tensile load Fx1at a room temperature>the allowable tensile load Fx2at the time of heating. Therefore, the load of the spring23is preferably in the range of 0.01 N to 1000 N, more preferably 0.01 N to 100 N, and even more preferably 0.1 N to 10 N.

The foil material24is accommodated in the accommodation space S of the housing22. The foil material24serves as a power supply path for supplying the electric power supplied to the housing22via the power supply line14to the movable body21. One end of the foil material24is connected to the power supply side wall22eof the housing22, and the other end of the foil material24is connected to the connection part21bof the movable body21. A connection portion between the foil material24and the movable body21is positioned in the accommodation space S. As a result, the foil material24is electrically connected to the filament10via the movable body21. The foil material24is formed of a material having a better electrical conductivity than the spring23. That is, an electric resistance value of the spring23is larger than an electric resistance value of the foil material24. The foil material24is formed of, for example, copper or the like as a material having a good electrical conductivity and a good flexibility. For example, in a case where the spring23is formed of stainless steel, the electric resistance is about 6Ω. For example, copper is used as the material of the foil material24, and a length thereof is, for example, 50 mm. An electrical resistivity of copper is 1.7×10−8Ω·m. Therefore, if a cross-sectional area of the foil material24is 1.4×10−2mm2or more, the electric resistance value of the foil material24can be sufficiently lowered to 1/100 or less of the electric resistance value of the spring23formed of stainless steel.

The foil material24is a thin film shaped member formed of a metal (a metal thin film part). A thickness of the foil material24is thinner than a width of the foil material24, and the width of the foil material24is smaller than a length of the foil material24. The foil material24extends from the power supply side wall22etoward the movable body21and is fixed to the connection part21bin a state where a tip end is folded back in a U shape. As described above, the foil material24has a folded-back part24awhich is folded back in a U shape and includes regions which are overlapped each other (doubled) in a positional relationship along the axis L at an end on the left side thereof, and the regions are separated from each other in a direction perpendicular to the axis L. Therefore, the length of the foil material24is longer than that of the spring23and longer than a length (a length of a straight line) from a connection position A between the foil material24and the power supply side wall22eto a connection position B between the foil material24and the movable body21. As a result, even in a case where the movable body21moves along the axis L, the position of the folded-back part24amoves in the foil material24(the doubled regions become larger or smaller), and thus the foil material24can maintain a state in which the power supply side wall22eand the movable body21are connected to each other while allowing the movable body21to move.

As shown inFIG.7, the housing22may further include a partitioning part22gin which one end is fixed to the power supply side wall22eand the other end extends toward the movable body21. The partitioning part22gextends from the end of the spring23on the left side to the end of the spring23on the left side to place the foil material24in a state where the partitioning part22gis separated from the spring23and partitions the spring23and the foil material24from each other. As a result, the foil material24is prevented from coining into contact with the spring23.

In this way, the tension holding unit20can maintain the tension of the filament10with the tensile force of the spring23. Further, a length (a free length) of the spring23is such that a tensile force can be applied to the movable body21even in a case where a length of the filament10becomes longer due to thermal expansion. For example, in a case where the material forming the filament10is tungsten, when the filament10having a total length of 500 mm is heated to 2000° C., the filament10becomes longer by about 5 mm due to thermal expansion with a coefficient of linear expansion of tungsten of 5.2×10−6[1/K] (2000° C.). Therefore, in order to absorb the thermal expansion length of the filament10, the movable body21needs to be able to move by at least about 5 mm. In addition, it is more preferable to secure a moving range in consideration of thermal expansion of peripheral members (for example, the main frame11). As a result, the tension holding unit20can maintain the tension of the filament10with the tensile force of the spring23even in a case where the length of the filament10changes due to thermal expansion. In this way, a state where the filament10is stretched in a straight linear shape by the tension holding unit20is maintained.

Further, in the tension holding unit20, the power supply side wall22eto which the power supply line14is connected and the movable body21to which the filament10is connected are connected to each other by the spring23and the foil material24. Here, the foil material24is formed of a material having a better electrical conductivity than the spring23. As a result, the electric power is supplied from the power supply side wall22eto the movable body21mainly through the foil material24rather than the spring23. As a result, heat generation of the spring23due to energization is curbed, and thus fluctuations in the tensile force, deterioration, or the like of the spring23due to the influence of heat is curbed. In this way, the tension holding unit20can hold the tension of the filament10by the spring23while supplying the electric power to the filament10through the foil material24via the movable body21. More specifically, since the electric power supply to the filament10is performed via the movable body21, the movable body21is in charge of rubbing or the like due to the mechanical sliding operation caused by the expansion and contraction of the spring23, and thus it is possible to curb the influence on the holding of the tension of the filament10by the spring23and the electric power supply to the filament10by the foil material24while curbing the mechanical damage to the filament10.

As described above, in the electron beam emission device1(the filament unit2), the tension of the filament10is held by the spring23. Further, in the electron beam emission device1, the electric resistance value of the spring23is larger than the electric resistance value of the foil material24, the energization to the spring23is curbed. As a result, deterioration of the spring23can be curbed. In this way, the electron beam emission device1can curb the energization to the spring23that holds the tension of the filament10to appropriately hold the tension of the filament10.

The electron beam emission device1(the filament unit2) includes the movable body21that connects one end of the filament10, the other end of the foil material24, and the other end of the spring23to each other. In this case, the electron beam emission device1can more reliably perform the holding of the tension of the filament10and the supplying of electric power via the movable body21connected to both the spring23and the foil material24. More specifically, since the supplying of electric power to the filament10is performed via the movable body21, the movable body21is in charge of rubbing or the like due to the mechanical sliding operation caused by the expansion and contraction of the spring23. Therefore, it is possible to curb the influence on the holding of the tension of the filament10by the spring23and the supplying of electric power to the filament10by the foil material24while curbing the mechanical damage to the filament10.

The length of the foil material24is longer than a length (a length of a straight line) from a connection position A between the foil material24and the power supply side wall22eto a connection position B between the foil material24and the movable body21. In this case, since the foil material24can absorb the movement of the movable body21even in a case where the movable body21moves due to thermal expansion of the filament10or the like, the electron beam emission device1can more reliably supply electric power to the filament10.

A thickness of the foil material24is thinner than a width of the foil material24. In this case, the foil material24can easily bend following the movement of the movable body21, and even if the movable body21moves, electric power can be reliably supplied.

The movable body21is formed of a conductive material. In this case, the electron beam emission device1can more reliably electrically connect the filament10and the foil material24to each other.

The connection portion between the spring23and the movable body21and the connection portion between the foil material24and the movable body21are positioned in the accommodation space S of the housing22. In this case, the electron beam emission device1can protect these electrically connected connection portions from external factors by the housing22and can stably perform the supplying of electric power at the connection portions.

The housing22supports the movable body21to be movable along the axis L by the guide hole22d. In this case, the electron beam emission device1can stably move the movable body21and can more reliably hold the tension of the filament10by the spring23.

The spring23is connected to the movable body21on the axis L and applies a tensile force to the movable body21to hold the tension of the filament10via the movable body21. In this case, the electron beam emission device1can easily apply the tensile force of the spring23to the filament10via the movable body21in the direction of the axis L to easily hold the tension of the filament10.

Next, various modification examples of the tension holding unit provided in the electron beam emission device1will be described. Hereinafter, a difference from the tension holding unit20in the above embodiment and a difference between tension holding units in the modification examples will be mainly described.

First Modification Example

As shown inFIG.8, a tension holding unit20A in a first modification example includes a movable body21A, a housing22A, a spring23, and an annular elastic body (a power supply path part)25. The movable body21A has a circular column shape extending in the left-right direction. The one end of the filament10is fixed to an end of the movable body21A on the left side. The other end of the spring23is connected to an end of the movable body21A on the right side. The movable body21A is provided on the axis L. Further, the movable body21A is disposed such that a position of a center of gravity of the movable body21A is positioned on the axis L. The movable body21A is formed of a conductive material. The movable body21A is formed of, for example, a copper alloy, stainless steel, or the like as a material having a good electrical conductivity.

The housing22A is a box body having an accommodation space S inside. The spring23is accommodated in the accommodation space S of the housing22A. The housing22A may be constituted by a box part22ahaving an open surface such that the spring23can be accommodated in the accommodation space S. A guide hole22dis provided in a filament side wall22cof the housing22A. A diameter of the guide hole22dis larger than a diameter of the movable body21A by a desired value. A length of the guide hole22din the direction of the axis L is longer than a length of the movable body21A. The guide hole22dguides the movable body21A to be movable along the axis L. That is, the housing22A holds the movable body21A to be movable along the axis L by the guide hole22d. The housing22A is formed of a conductive material. The housing22A is formed of, for example, a copper alloy, stainless steel, or the like as a material having a good electrical conductivity.

The spring23is provided on the axis L. The other end of the spring23is connected to an end of the movable body21A on the right side. A connection position between the spring23and the movable body21A is positioned on the axis L. One end of the spring23is connected to a power supply side wall22eof the housing22A. The housing22A covers the spring23such that the spring23cannot be seen directly from the filament10.

The spring23applies a tensile force to the movable body21A such that the movable body21A moves along the axis L. That is, the spring23pulls the movable body21A in one side direction along the axis L from the connection position to the movable body21A. As a result, the spring23pulls the filament10via the movable body21A by applying a tensile force to the movable body21A and holds the tension of the filament10.

The annular elastic body25is accommodated in the guide hole22dof the housing22A. The annular elastic body25serves as a power supply path for supplying the electric power supplied to the housing22A via the power supply line14to the movable body21A. The annular elastic body25is formed of an elastic member having an annular shape and conductivity. The annular elastic body25is fitted into a recess21cextending over the entire region in a circumferential direction in an outer peripheral surface of the movable body21A in a cross section in the direction perpendicular to the axis L.

A portion of an outer peripheral edge (one end) of the annular elastic body25in a radial direction (a direction perpendicular to the axis L) is in contact with an inner peripheral surface of the guide hole22dof the housing22A and is electrically connected thereto. A portion of an inner peripheral edge (the other end) of the annular elastic body25in the radial direction is in contact with an outer peripheral surface (an inner wall surface of the recess21c) of the movable body21A and is electrically connected thereto. That is, in the state where the annular elastic body25is fitted into the recess21c, a diameter of an outer periphery of the annular elastic body25is larger than a diameter of an outer periphery of the movable body21A, and a diameter of an inner periphery of the annular elastic body25is smaller than at least a diameter of an outer periphery of the movable body21A. As a result, the annular elastic body25is electrically connected to the housing22A and is also electrically connected to the filament10via the movable body21A. The annular elastic body25is formed of a material having a better electrical conductivity than the spring23. That is, an electric resistance value of the spring23is larger than an electric resistance value of the annular elastic body25. The annular elastic body25is formed of, for example, a copper alloy or the like as a material having a good electrical conductivity.

In this way, the tension holding unit20A can maintain the tension of the filament10with the tensile force of the spring23as in the tension holding unit20in the embodiment. Further, in the tension holding unit20A, the housing22A and the movable body21A are connected to each other by the spring23and the annular elastic body25. Further, the annular elastic body25is formed of a material having a better electrical conductivity than the spring23. As a result, the electric power is supplied from the housing22A to the movable body21A mainly through the annular elastic body25rather than the spring23. As a result, heat generation of the spring23due to energization is curbed, and thus fluctuations in the tensile force, deterioration, or the like of the spring23due to the influence of heat is curbed. In this way, the tension holding unit20A can hold the tension of the filament10by the spring23while supplying the electric power to the filament10through the annular elastic body25via the movable body21A.

As described above, also in a case where the electron beam emission device1is provided with the tension holding unit20A, it is possible to exhibit the same operation and effect as in the case where the electron beam emission device1is provided with the tension holding unit20in the embodiment.

Specifically, in the electron beam emission device1(the filament unit2), the tension of the filament10is held by the spring23. Further, in the tension holding unit20A, the electric resistance value of the spring23is larger than the electric resistance value of the annular elastic body25, the energization to the spring23is curbed. As a result, deterioration of the spring23can be curbed. In this way, the electron beam emission device1provided with the tension holding unit20A can curb the energization to the spring23that holds the tension of the filament10to appropriately hold the tension of the filament10.

The electron beam emission device1(the filament unit2) includes the movable body21A that connects one end of the filament10, one end of the spring23, and the annular elastic body25to each other. In this case, the electron beam emission device1can more reliably perform the holding of the tension of the filament10and the supplying of electric power via the movable body21A connected to both the spring23and the annular elastic body25. More specifically, since supplying of electric power to the filament10is performed via the movable body21A, the movable body21A is in charge of rubbing or the like due to the mechanical sliding operation caused by the expansion and contraction of the spring23. Therefore, it is possible to curb the influence on the holding of the tension of the filament10by the spring23and the supplying of electric power to the filament10by the annular elastic body25while curbing the mechanical damage to the filament10.

The electron beam emission device1(the filament unit2) supplies electric power to the filament10from the housing22A by electrically connecting the movable body21A and the guide hole22dof the housing22A via the annular elastic body25. The annular elastic body25is in contact with the inner peripheral surface of the guide hole22dand the outer peripheral surface of the movable body21A. As a result, the electron beam emission device1provided with the tension holding unit20A can electrically connect the housing22A and the movable body21A to each other and can supply electric power from the housing22A to the filament10via the movable body21A.

The annular elastic body25is fitted into the recess21cof the movable body21A. In this case, the electron beam emission device1provided with the tension holding unit20A can more reliably supply electric power to the filament10by the annular elastic body25while easily holding the annular elastic body25by the recess21cprovided in the outer peripheral surface of the movable body21A.

The spring23is connected to the movable body21A on the axis L and applies a tensile force to the movable body21A to hold the tension of the filament10via the movable body21A. In this case, the electron beam emission device1provided with the tension holding unit20A can easily apply the tensile force of the spring23to the filament10via the movable body21A in the direction of the axis L to easily hold the tension of the filament10.

Second Modification Example

As shown inFIG.9, a tension holding unit20B in a second modification example includes a movable body21B, a housing22B, a spring (a tension holding part)26, and a foil material (a power supply path part)27. The movable body21B is connected to the one end of the filament10. The movable body21B has a circular column21aand a small-diameter circular column21d. The small-diameter circular column21dincludes a main body21d1having a diameter smaller than that of the circular column21aand a tip end21d2having a diameter smaller than that of the main body21d1. The main body21d1is connected to an end of the circular column21aon the left side, and the tip end21d2is connected to an end of the main body21d1on the left side. The one end of the filament10is fixed to an end of the tip end21d2of the small-diameter circular column21don the left side. The movable body21B is provided on the axis L. Further, the movable body21B is disposed such that a position of a center of gravity of the movable body21B is positioned on the axis L. The movable body21B is formed of a conductive material. The movable body21B is formed of, for example, a material such as stainless steel, copper, or a copper alloy.

The housing22B further includes a housing side spring receiving part (a housing side tension receiving part)22hwith respect to the housing22A (seeFIG.8) in the first modification example. The housing side spring receiving part22his provided on a surface of the filament side wall22con a side of the filament10(the other side). The housing side spring receiving part22his provided with a small-diameter hole22jthrough which the tip end21d2of the small-diameter circular column21dof the movable body21B can be inserted. A diameter of the small-diameter hole22jis smaller than a diameter of a guide hole22dand larger than a diameter of the tip end21d2. The housing22B is formed of a conductive material. The housing22B is formed of, for example, a material such as stainless steel, copper, or a copper alloy.

The spring26is accommodated in the guide hole22dof the housing22B. The spring26is provided on the axis L. The main body21d1of the small-diameter circular column21dof the movable body21B passes through the inside of the spring26. That is, an outer diameter of the spring26is smaller than an inner diameter of the guide hole22d, and an inner diameter of the spring26is larger than an outer diameter of the main body21d1of the small-diameter circular column21d. One end of the spring26is in contact with an end face of the circular column21aof the movable body21B on the left side. The other end of the spring26is in contact with a surface of the housing side spring receiving part22hon the right side. That is, the end surface of the circular column21aof the movable body21B on the left side becomes a movable body side spring receiving part (a movable part side tension receiving part)21ewith which the spring26is in contact. The housing side spring receiving part22his positioned on a side of the filament10from the movable body side spring receiving part21e. The spring26is disposed between the movable body side spring receiving part21eand the housing side spring receiving part22h. The housing side spring receiving part22hcovers the spring26such that the spring26cannot be seen directly from the filament10(partitions the filament10the spring26from each other).

The spring26is a compression spring. The spring26applies a pressing force to the movable body21B such that the movable body21B moves along the axis L. That is, the spring26presses the movable body21B in one side direction along the axis L from a contact position with the movable body21B. The movable body21B is connected to the one end of the filament10. As a result, the spring26pulls the filament10in a right direction via the movable body21B by applying a pressing force to the movable body21B and holds the tension of the filament10. The spring26is formed of, for example, a material such as stainless steel or Inconel. The spring26may be formed of a material which is different from the filament10.

The foil material27is accommodated in the accommodation space S of the housing22B. The foil material27serves as a power supply path for supplying the electric power supplied to the housing22B via the power supply line14to the movable body21B. One end of the foil material27is connected to the power supply side wall22eof the housing22B, and the other end of the foil material27is connected to the circular column21aof the movable body21B. As a result, the foil material27is electrically connected to the filament10via the movable body21B. The foil material27is formed of a material having a better electrical conductivity than the spring26. That is, an electric resistance value of the spring26is larger than an electric resistance value of the foil material27. The foil material27is formed of, for example, copper or the like as a material having a good electrical conductivity and a good flexibility.

The foil material27is a thin film shaped member formed of a metal (a metal thin film part). A thickness of the foil material27is thinner than a width of the foil material27, and the width of the foil material27is smaller than a length of the foil material27. The length of the foil material27is longer than a length (a length of a straight line along the axis L) from a connection position A between the foil material27and the power supply side wall22eto a connection position B between the foil material27and the movable body21B. As a result, even in a case where the movable body21B moves along the axis L, the foil material24can maintain a state in which the power supply side wall22eand the movable body21B are connected to each other while allowing the movable body21B to move.

In this way, the tension holding unit20B can maintain the tension of the filament10with the pressing force of the spring26. Further, a length (a free length) of the spring26is such that a pressing force can be applied to the movable body21B even in a case where a length of the filament10becomes longer due to thermal expansion. As a result, the tension holding unit20B can maintain the tension of the filament10with the pressing force of the spring26even in a case where the length of the filament10changes due to thermal expansion. In this way, a state where the filament10is stretched in a straight linear shape by the tension holding unit20B is maintained.

Further, in the tension holding unit20B, the housing22B and the movable body21B are connected to each other by the spring26and the foil material27. Here, the foil material27is formed of a material having a better electrical conductivity than the spring26. As a result, the electric power is supplied from the power supply side wall22eto the movable body21B mainly through the foil material27rather than the spring26. As a result, heat generation of the spring26due to energization is curbed, and thus fluctuations in the pressing force or the like of the spring26due to the influence of heat is curbed. In this way, the tension holding unit20B can hold the tension of the filament10by the spring26while supplying the electric power to the filament10through the foil material27via the movable body21B.

As described above, also in a case where the electron beam emission device1is provided with the tension holding unit20B, it is possible to exhibit the same operation and effect as in the case where the electron beam emission device1is provided with the tension holding unit20in the embodiment.

Here, in the tension holding unit20B, the spring26is disposed between the movable body side spring receiving part21eof the movable body21B and the housing side spring receiving part22h. The spring26applies a pressing force to the movable body21B. In this case, the electron beam emission device1provided with the tension holding unit20B can easily hold the tension of the filament10using the pressing force of the spring26.

Third Modification Example

As shown inFIG.10, a tension holding unit20C in a third modification example is configured to include the annular elastic body25of the tension holding unit20A (seeFIG.8) in the first modification example instead of the foil material27in the configuration of the tension holding unit20B (seeFIG.9) in the second modification example. Specifically, the tension holding unit20C includes a movable body21C, a housing22B, an annular elastic body (a power supply path part)25, and a spring26. A recess21cis provided in an outer peripheral surface of a circular column21aof the movable body21C. The annular elastic body25is fitted into the recess21cof the circular column21a.

The tension holding unit20C can maintain the tension of the filament10with the pressing force of the spring26as in the tension holding unit20B in the second modification example. Further, in the tension holding unit20C, the housing22B and the movable body21C are connected to each other by the annular elastic body25and spring26. Here, the annular elastic body25is formed of a material having a better electrical conductivity than the spring26. As a result, the electric power is supplied from the housing22B to the movable body21C mainly through the annular elastic body25rather than the spring26. As a result, heat generation of the spring26due to energization is curbed, and thus fluctuations in the pressing force or the like of the spring26due to the influence of heat is curbed. In this way, the tension holding unit20C can hold the tension of the filament10by the spring26while supplying the electric power to the filament10through the annular elastic body25via the movable body21C.

As described above, also in a case where the electron beam emission device1is provided with the tension holding unit20C, it is possible to exhibit the same operation and effect as in the case where the electron beam emission device1is provided with the tension holding unit20B in the second modification example.

Here, in the tension holding unit20C, the spring26is disposed between the movable body side spring receiving part21eof the movable body21C and the housing side spring receiving part22h. The spring26applies a pressing force to the movable body21C. In this case, the electron beam emission device1provided with the tension holding unit20C can easily hold the tension of the filament10using the pressing force of the spring26.

Fourth Modification Example

As shown inFIG.11, a tension holding unit20D in a fourth modification example further includes an insulation ring (an insulation member)28and an insulation ring (and insulation member)29with respect to the configuration of the tension holding unit20B (seeFIG.9) in the second modification example. That is, the tension holding unit20D includes a movable body21B, a housing22B, a spring26, a foil material27, an insulation ring28, and an insulation ring29.

The insulation ring28is disposed between the spring26and a housing side spring receiving part22h. The insulation ring28electrically insulates the housing22B and the spring26from each other. The insulation ring28is formed of a material having a less conductivity than the spring26. An outer edge of the insulation ring28projects toward the spring26in a direction along the axis L to surround an outer peripheral portion of the spring26. As a result, the insulation ring28can prevent the outer peripheral portion of the spring26from coining into contact with the inner peripheral surface of the guide hole22d. Further, the spring26is also positioned in the direction perpendicular to the axis L by an inner peripheral portion of the insulation ring28, and thus the contact between the spring26and the small-diameter circular column21dof the movable body21B is also curbed.

Similarly, the insulation ring29is disposed between the movable body side spring receiving part21eof the circular column21aof the movable body21B and the spring26. The insulation ring29electrically insulates the movable body21B and the spring26from each other. The insulation ring29is formed of a material having a less conductivity than the spring26. An outer edge of the insulation ring29projects toward the spring26in a direction along the axis L to surround an outer peripheral portion of the spring26. As a result, the insulation ring29can prevent the outer peripheral portion of the spring26from coining into contact with the inner peripheral surface of the guide hole22d. Further, the spring26is also positioned in the direction perpendicular to the axis L by an inner peripheral portion of the insulation ring29, and thus the contact between the spring26and the small-diameter circular column21dof the movable body21B is also curbed.

The tension holding unit20D may be configured to include only any one of the insulation ring28and the insulation ring29.

As described above, the tension holding unit20D in the fourth modification example can further curb the energization to the spring26by providing the insulation rings28and29and can more reliably supply electric power to the filament10by the foil material27. Further, the tension holding unit20D can further curb heat generation of the spring26due to energization.

Fifth Modification Example

As shown inFIG.12, a tension holding unit20E in a fifth modification example further includes an insulation ring (an insulation member)28and an insulation ring (and insulation member)29with respect to the configuration of the tension holding unit20C (seeFIG.10) in the third modification example. That is, the tension holding unit20E includes a movable body21C, a housing22B, an annular elastic body25, a spring26, an insulation ring28, and an insulation ring29. The insulation rings28and29have the same configuration as the insulation rings28and29in the fourth modification example.

As described above, the tension holding unit20E in the fifth modification example can further curb the flow of electricity to the spring26by providing the insulation rings28and29and can more reliably supply electric power to the filament10by the annular elastic body25. Further, the tension holding unit20E can further curb heat generation of the spring26due to energization.

Here, for example, even in the tension holding unit20in the embodiment described with reference toFIGS.6and7, it is possible to further curb the flow of electricity to the spring23. Specifically, in the connection part21bof the tension holding unit20shown inFIGS.6and7, a portion to which the spring23is connected (a portion to be hooked) may be made of an insulation material (for example, ceramic or the like). Alternatively, the portion of the connection part21bto which the spring23is connected may be subjected to insulation coating. Further, the spring23of the tension holding unit20may be subjected to insulation coating. Similarly, for example, in the movable body21A of the tension holding unit20A of the first modification example described with reference toFIG.8, a portion to which the spring23is connected (a portion to be hooked) may be made of an insulation material (for example, ceramic or the like). Alternatively, the portion of the movable body21A to which the spring23is connected may be subjected to insulation coating. Further, the spring23of the tension holding unit20A may be subjected to insulation coating. Even in these cases, the tension holding units20and20A can further curb the flow of electricity to the spring23and can further curb heat generation of the spring23due to energization.

Sixth Modification Example

As shown inFIG.13, in a tension holding unit20F in a sixth modification example, the housing22of the tension holding unit20in the embodiment is divided into two. Specifically, the tension holding unit20F includes a movable body21, a housing22F, a spring23, and a foil material24. The housing22F includes a first housing22kand a second housing22m.

The first housing22kis provided with the guide hole22dthrough which the circular column21aof the movable body21passes. The second housing22mhas the accommodation space S for accommodating the spring23and a portion of the foil material24on a side of the power supply side wall22e. The first housing22kand the second housing22mare attached to the main frame11of the filament unit2via an insulation material. That is, the first housing22kand the second housing22mare electrically insulated from each other.

As described above, also in a case where the electron beam emission device1is provided with the tension holding unit20F, it is possible to exhibit the same operation and effect as in the case where the electron beam emission device1is provided with the tension holding unit20in the embodiment. Further, the tension holding unit20F can supply the electric power to the movable body21from the power supply side wall22evia the foil material24without directly supplying the electric power to the movable body21from the inner peripheral surface of the guide hole22dprovided in the first housing22k. In this way, the tension holding unit20F is not configured to supply the electric power via the members sliding on each other, and thus it is possible to supply the electric power to the movable body21more reliably.

Seventh Modification Example

As shown inFIG.14, in a tension holding unit20G in a seventh modification example, the housing22A of the tension holding unit20A in the first modification example is divided into two. Specifically, the tension holding unit20G includes a movable body21A, a housing22G, a spring23, and an annular elastic body25. The housing22G includes a first housing22nand a second housing22p.

The first housing22nis provided with the guide hole22dthrough which the movable body21A passes. The one end of the spring23is connected to an end of the movable body21A on the right side. The other end of the spring23is connected to the second housing22p. The first housing22nand the second housing22pare attached to the main frame11of the filament unit2via an insulation material. That is, the first housing22nand the second housing22pare electrically insulated from each other.

The end of the power supply line14is connected to the first housing22n. In the tension holding unit20G, the electric power is supplied from the first housing22nto the filament10via the annular elastic body25and the movable body21A. As a result, heat generation of the spring23due to energization is curbed, and thus fluctuations in the tensile force or the like of the spring23due to the influence of heat is curbed. In this way, the tension holding unit20G can hold the tension of the filament10by the spring23while supplying the electric power to the filament10through the annular elastic body25via the movable body21A.

(Example of Filament Fixing Method)

Next, an example of a method of fixing the filament10to the tip end of the movable body21of the tension holding unit20in the embodiment will be described. The method of fixing the filament10, which will be described below, is also applicable to the various modification examples of the tension holding unit described above. As shown inFIG.15, a bolt hole21fextending along the axis L is provided in the tip end surface (the other end surface) of the circular column21aof the movable body21. A filament fixing member40is attached to the tip end (the one end side) of the filament10. The filament fixing member40includes a tubular part41and a flange42. The tip end of the filament10is inserted into the tubular part41and fixed thereto. Here, the tubular part41may be attached to the filament10by the tip end of the filament10being placed on an inner peripheral surface thereof by caulking. The flange42protrudes outward from the outer peripheral surface of the end of the tubular part41on a side of the movable body21.

The filament fixing member40is fixed to the tip end of the movable body21by a perforated bolt50. The perforated bolt50is provided with a through hole50aextending in an axial direction of the perforated bolt50. The tubular part41of the filament fixing member40and a part of the filament10are inserted into the through hole50asuch that the flange42comes into contact with the tip end of the perforated bolt50. The perforated bolt50is attached to the bolt hole21fof the circular column21ain a state where the tubular part41or the like is inserted into the through hole50a. The filament fixing member40attached to the tip end of the filament10is fixed to the tip end of the circular column21awhen the flange42is sandwiched between the tip end of the perforated bolt50and a bottom portion of the bolt hole21fof the circular column21a.

In this way, in the configuration shown inFIG.15, the filament10can be easily attached to and detached from the movable body21using the perforated bolt50. As a result, in this configuration, it is easy to replace the filament10. Further, according to this configuration, the movable body21can easily pull the filament10in the direction of the axis L while curbing the axial deviation.

Although the embodiment and various modification examples of the present disclosure have been described above, the present disclosure is not limited to the above embodiment and various modification examples. The configurations which will be described below are applicable to all the embodiment and various modification examples as much as possible. For example, the tension holding unit20in the embodiment may not be provided with the movable body21. In this case, the ends of the spring23and the foil material24may be directly connected to the end of the filament10.

In the tension holding unit20of the embodiment, the shape of the movable body21and the guide hole22dis not limited to the circular column shape extending along the axis L. The movable body21and the guide hole22dmay have a shape other than the circular column shape, for example, a polygonal shape.

In the tension holding unit20A of the first modification example, the annular elastic body25is not limited to being fitted into the recess21cof the movable body21A. For example, the annular elastic body25may be fitted into a recess extending over the entire region in a circumferential direction in the inner peripheral surface of the guide hole22d.

The tension holding unit20A of the first modification example includes the annular elastic body25as the power supply path part that connects the movable body21A and the housing22A to each other, but the power supply path part does not have to be annular. Further, the recess21cprovided in the outer peripheral surface of the movable body21A may not be provided over the entire region in the circumferential direction in the outer peripheral surface of the movable body21A. The recess21cmay be provided only in a part of the outer peripheral surface of the movable body21A. In this case, the power supply path part that connects the movable body21A and the housing22A to each other only have to be a shape that is fitted into a recess provided in the outer peripheral surface of the movable body21A. Similarly, in a case where the power supply path part that connects the movable body21A and the housing22A to each other is fitted into the recess provided in the guide hole22d, the recess provided in the guide hole22ddoes not have to be provided over the entire region in the circumferential direction in the inner peripheral surface of the guide hole22d.

Further, the filament unit2may be used as an electron beam generation source provided in an X-ray emission device that emits X-rays. In a case where the filament unit2is used as an electron beam generation source of an X-ray emission device, the X-ray emission device further includes a main body that accommodates the filament unit2, an X-ray target (for example, tungsten, molybdenum, or the like) as an X-ray generation part that generates X-rays when electrons are incident from the filament unit2, and an X-ray extraction part for extracting X-rays to the outside of the main body. In this case, as an example of the X-ray extraction part, the window9shown inFIG.1may be changed to a window for X-ray emission constituted by a window material having a high X-ray permeability (for example, beryllium, diamond, or the like) and the X-ray target provided on a surface of the window material on a side of the vacuum space R. As a result, the electron beams EB emitted from the filament unit2can be incident on the X-ray target, and the X-rays can be emitted from the X-ray target.

At least a part of the above-described embodiment and various modification examples may be arbitrarily combined.

REFERENCE SIGNS LIST

1Electron beam emission device2Filament unit (electron beam generation source)10Filament (electron discharge part)20,20A to20G Tension holding unit21,21A to21C Movable body (movable part)21eMovable body side spring receiving part (movable part side tension receiving part)22,22A,22B,22F,22G housing (support part, housing part)22dGuide hole (movable part holding part)22hHousing side spring receiving part (housing side tension receiving part)23,26Spring (tension holding part)24,27Foil material (power supply path part, metal thin film part)25Annular elastic body (power supply path part)28,29Insulation ring (insulation member)L AxisS Accommodation space (internal space)