Patent ID: 12230493

MODE FOR CARRYING OUT INVENTION

Embodiment 1

FIG.1andFIG.2are diagrams for describing a configuration of a microwave-excited light source device according to Embodiment 1,FIG.1is a cross-sectional view taken along an axis of the microwave-excited light source device, andFIG.2is a partially enlarged cross-sectional view obtained by enlarging a region R inFIG.1.

As shown inFIG.1, a microwave-excited light source device1according to Embodiment 1 includes a center electrode2disposed at the center in the radial direction, an annular electrode3disposed concentrically with the center electrode2, and an arc tube4arranged in an annular space between the center electrode2and the annular electrode3. In addition, a connection end plate6that is disc-shaped and serves as a connection end for electrical connection to a microwave generation source100, and a connector5in annular shape that is for electrical connection between the connection end plate6and the annular electrode3and is for mechanical fixation of the arc tube4to the connection end plate6are provided.

The arc tube4is, for example, a double tube formed by joining an inner tube4iand an outer tube4xmade of quartz glass having a higher ultraviolet transmissivity than other glasses, and mercury (Hg) or the like, which is a luminescent material is sealed in the inside (light-emitting space4s). The double tube has an outer diameter D4=15 mm and an axial length L4=150 mm, and has an elongated shape in which the axial length L4is 10 times the outer diameter D4.

In addition, for example, the annular electrode3, which is in net-shaped, referred to as a mesh conductor, and can transmit light, are in close contact with an outer circumferential surface4fxof the outer tube4x. At the center in the radial direction (inner side of the inner tube4i), the center electrode2concentric with the annular electrode3is inserted. The central electrode2and the annular electrode3function to form an electromagnetic field in the annular space when a microwave is input from the microwave generation source100. Then, the device is configured such that the luminescent material in the light-emitting space4sis excited to emit light by the formed electromagnetic field, and thus the light is emitted through the annular electrode3.

The connection end plate6includes a conductor portion61that is disposed on the outer peripheral side and is for electrical connection to the annular electrode3, and an insulator portion62that is disposed on the inner peripheral side of the conductor portion61and has a through hole, which is not denoted by a reference numeral, through which the center electrode2passes in the center portion. The connector5is formed in an annular shape with a conductive material, and is fitted to the arc tube4so that the annular electrode3is interposed between the inner circumferential surface of the connector5and the outer circumferential surface4fxof the arc tube4to be electrically connected to the annular electrode3.

A coupling member7that mechanically couples the connector5and the connection end plate6, electrically connects the connector5and the conductor portion61, and functions as a buffer mechanism is further provided.

As the coupling member7, a case is drawn in which eight helical springs as elastic bodies are arranged to disperse them at eight positions in the circumferential direction with their directions of the axes parallel to the axial direction. As shown inFIG.2, when no mechanical shock is applied, the coupling member7mechanically supports the connector5with respect to the connection end plate6such that an opposing surface6ffof the connection end plate6and an opposing surface5ffof the connector5face each other in parallel with a clearance G7ain the axial direction. In addition, since the coupling member7is formed of a conductor, the conductor portion61and the connector5are electrically connected to each other.

Further, the connector5is formed of a conductive material and has an annular portion5rwhose inner diameter is equal to the outer diameter D4of the arc tube4(strictly speaking, the diameter added with the thickness of the annular electrode3) and an edge portion5pextending radially inward at one end (right end in the figure) of the annular portion5rin the axial direction. The connector5restrains and mechanically fixes the outer circumferential surface4fxof the arc tube4by fitting the annular portion5rinto the outer circumferential surface4fxof the arc tube4from above the annular electrode3. Thus, an electrical connection path from one pole of the microwave generation source100to the annular electrode3via the connection end plate6and the connector5is completed.

As for the fitting, so-called shrink fitting may be used, in which the inner diameter of the annular portion5rof the connector5is made smaller than the sum of the outer diameter D4of the arc tube4and the thickness of the annular electrode3, and the connector is fitted in a heated and expanded state. Alternatively, an inner circumferential surface5fimay be formed in a tapered shape, and the annular portion5rmay be pushed into the arc tube4in the axial direction to generate a pressing force in the radial direction.

At this time, when the annular portion5ris fitted until the edge portion5pabuts against one end (the end portion on the right side in the figure) of the arc tube4, the movement of the arc tube4in the axial direction is also restrained, and the mechanical fixation between the connector5and the arc tube4is further strengthened. On the other hand, since the arc tube4and the connector5are supported by the connection end plate6via the coupling member7, which is an elastic body, the arc tube4and the connector5are allowed to move in the axial direction or in a direction inclined with respect to the axis.

The center electrode2is mechanically fixed to and supported by the insulator portion62of the connection end plate6, but is electrically connected to the other pole of the microwave generation source100directly or via a coaxial cable or the like. At this time, an outer diameter D2of the center electrode2is set to be smaller than an inner diameter D4iof the inner tube4isuch that there should be a clearance G24between the outer diameter and an inner circumferential surface4fiof the inner tube4iof the arc tube4, and the center electrode2is in a floating state with respect to the inner circumferential surface4fi. That is, mechanical connection of the center electrode2is cut with respect to the arc tube4, and the movement of the center electrode2is allowed in the axial direction of the arc tube4or in a direction inclined with respect to the axis. The clearance G24is set in a range from 1 mm to 5 mm, for example, on the basis of an assumed mechanical shock (external force) and the movement of the center electrode2(the spring coefficient of the elastic member constituting the coupling member7, etc.) allowed in response to the mechanical shock.

When a microwave is input from the microwave generation source100to the microwave-excited light source device1configured as described above, an electromagnetic field is formed by the microwave input in the annular space between the center electrode2and the annular electrode3. By the electromagnetic field formed by the microwave, the luminescent material in the light-emitting space4sof the arc tube4, which is disposed in the annular space, is excited to emit light, and the emitted light can be output through the annular electrode3. For example, when the electromagnetic field is generated in the annular space by a microwave of 2.45 GHz, ultraviolet rays are emitted by an excited light emission of the mercury as the luminescent material, and highly efficient sterilization can be achieved.

Here, for example, a case where a mechanical shock is applied to the arc tube4will be examined. In the configuration disclosed in Patent Document 1, since the elongated arc tube is fixedly supported with respect to the microwave generation source100or the transmission path by using a screw, a force is applied to the screw portion, which may cause irreversible deformation. Then, the contact state at the screw portion also serving as the electrical connection also changes, the impedance in the transmission path of the microwave changes from an initially set value, and the desired light emission characteristics cannot be obtained. On the other hand, this phenomenon has been overlooked so far because even in that state, the conduction is maintained and it is not in a state where the light does not emit, but the inventor of the present application found that this phenomenon should not be overlooked as a microwave-excited light source device1.

Therefore, the microwave-excited light source device1of the present application is configured to form a buffer mechanism that suppresses the stress to be applied to the contact surface between the arc tube4and the connector5by, for example, elastic deformation of the coupling member7when the arc tube4is subjected to an external force. In Embodiment 1, the arc tube4is supported by interposing the coupling member7between the connector5into which the arc tube4is fitted and the connection end plate6serving as a support mechanism, the coupling member7being formed of a plurality of elastic bodies dispersed in the circumferential direction and functioning as a buffer mechanism.

Here, it is assumed that a force is applied to the arc tube4in a direction in which the axis thereof is to be inclined. Then, while the force is applied, the shape of the area with the clearance G7ais changed by the deformation of the coupling member7, and the arc tube4is displaced with respect to the connection end plate6without being accompanied by displacement with respect to the connector5, so that the stress applied to the interface between the arc tube and the connector5is relieved. As a result, displacement does not occur between the annular electrode3in close contact with the outer circumferential surface4fxand the connectors5, and even if an external force such as a mechanical shock is applied, the electrical connection state, that is, the impedance, can be maintained at the initially set value, and desired light emission characteristics can be maintained.

On the other hand, although the center electrode2is mechanically fixed to the connection end plate6, the center electrode2does not hit against the inner circumferential surface4fiof the arc tube4when the center electrode2is displaced, because there is the clearance G24between the center electrode2and the inner circumferential surface4fi, which is set in consideration of the displacement. Further, since the displacement is caused by the deformation of the elastic member7, that is, the displacement caused by the elastic deformation, when the external force is removed, the elastic member7returns to the original position, that is, the regular position along the axis in the center. That is, in the deformation of the elastic body, the displacement when the external force is applied is reversible, and when the external force is removed, the annular space between the center electrode2and the annular electrode3also returns to its original state. Therefore, the state of the electromagnetic field is also recovered, and the characteristics can be maintained.

As for the arrangement of the elastic bodies constituting the coupling member7, the number of elastic bodies to be arranged and the arrangement positions of the elastic bodies can be changed as appropriate as long as the elastic bodies are arranged at positions interposing or surrounding the axis. Further, the helical spring is not a limitation, and other forms such as a plate spring and a volute spring may be used as long as they have conductivity. Further, in the present application including the following embodiments, the arc tube4of a double-tube type in which the shape of the outer circumferential surface4fxperpendicular to the axial direction is circular and the annular electrode3can be supported by the entire circumference will be described as an example, but this is not a limitation. For example, like a spiral tube, a tube in any form can be applied as long as it maintains the outer diameter to support the annular electrode3, and the clearance G24with the center electrode2, even when pressed from the outer circumferential surface side.

Embodiment 2

In Embodiment 1 described above, an example has been described in which the clearance in the axial direction is provided between the connector and the connection end plate, and the connector and the connection end plate are coupled by an elastically deformable coupling member. In Embodiment 2, an example in which a coupling member that presses and supports a connector in the radial direction is provided will be described.FIG.3andFIG.4are for describing a configuration of a microwave-excited light source device according to Embodiment 2,FIG.3is a partially enlarged cross-sectional view along the axis of the microwave-excited light source device corresponding toFIG.2of Embodiment 1, andFIG.4is a cross-sectional view perpendicular to the axis, corresponding to a line A-A ofFIG.3. Note that, for each of the entire images in the arc tube, the annular electrode, and the center electrode,FIG.1in Embodiment 1 is referred to.

As shown inFIG.3andFIG.4, the microwave-excited light source device1according to Embodiment 2 is provided with a coupling member7that couples a connector5and a connection end plate6so that the connector5presses the outer circumferential surface4fxfrom above the annular electrode3in the radial direction. The connector5has an arc shape, which is obtained by dividing an annular ring along the outer circumferential surface4fxof the arc tube4in the circumferential direction, and is provided at two positions in the circumferential direction.

Basically, as in Embodiment 1, the connection end plate6includes the conductor portion61for electrical connection to the annular electrode3, and the insulator portion62disposed on the inner circumferential side of the conductor portion61and having a through hole formed in the center thereof for allowing the center electrode2to pass therethrough. In Embodiment 2, a male thread to be screwed into a female thread7sformed on an inner circumferential surface of a cylindrical portion72of the coupling member7to be described later is cut on an outer circumferential surface of the conductor portion61.

The coupling member7includes the cylindrical portion72having a cylindrical shape and provided with the female thread7son one end side in the axial direction for screwing the connection end plate6and an elastic member71extending from an inner circumferential surface7fion the other end side of the cylindrical portion72toward the center in the radial direction. The connection end plate6is mechanically fixed to the cylindrical portion72by screwing the connection end plate6into the female thread7suntil the connection end plate6abuts against a ridge portion (not denoted by a reference numeral) protruding toward the axial center at an intermediate portion in the axial direction.

On the other hand, a plurality of helical springs as the elastic member71whose axes are oriented in the radial direction are distributed and arranged at different positions in the axial direction and the circumferential direction so as to press the outer circumferential surface4fxof the arc tube4covered with the annular electrode3via the connectors5from positions distributed in the circumferential direction on the inner circumferential surface7fiof the cylindrical portion72. Although a clearance G7rin the radial direction is provided between the cylindrical portion72and the arc tube4and a clearance G7ain the axial direction is provided between the arc tube4and the connection end plate6, the arc tube4is mechanically supported by the pressing force of the elastic member71such that the cylindrical portion72and the arc tube4are kept concentric.

At this time, since both the cylindrical portion72and the elastic member71are formed of a conductive material, a stable electrical connection path from the connection end plate6(the conductor portion61thereof) to the elastic member71is completed in accordance with the mechanical fixation of the coupling member7and the connection end plate6by screwing the connection end plate6into the female thread7s. The elastic member71causes the annular electrode3to be sandwiched between the connectors5and the outer circumferential surface4fxof the arc tube4, and brings the connectors5into close contact with the annular electrode3by the urging force, so that the electrical connection path from the connection end plate6to the annular electrode3is completed.

As in Embodiment 1, the center electrode2is mechanically fixed to and supported by the insulator portion62of the connection end plate6, and is electrically connected to the other pole of the microwave generation source100directly or via a coaxial cable or the like. With respect to the relationship with the inner circumferential surface4fiof the inner tube4iof the arc tube4, mechanical connection of the center electrode2is cut with respect to the arc tube4, and the center electrode2is allowed to move in the axial direction of the arc tube4or in a direction inclined with respect to the axis.

On the premise of the configuration described above, it is assumed that a force is applied to the arc tube4in a direction in which the axis is to be inclined. Then, while the force is applied, the elastic member71of the coupling member7is deformed to change the shapes in the areas of the clearance G7rand the clearance G7a, and the arc tube4is displaced with respect to the connection end plate6without displacement with respect to the connectors5, so that the stress applied to the interfaces between the arc tube4and the connectors5is relaxed. As a result, no displacement occurs between the annular electrode3in close contact with the outer circumferential surface4fxand the connectors5, so that the electrical connection state, i.e., the impedance, can be maintained at the initially set value and desired light emission characteristics can be maintained.

On the other hand, although the center electrode2is mechanically fixed to the connection end plate6, the center electrode2does not hit against the inner circumferential surface4fiof the arc tube4when the center electrode2is displaced, because there is the clearance G24between the center electrode2and the inner circumferential surface4fi. Further, since the displacement is caused by the deformation of the elastic member71, that is, the displacement caused by the elastic deformation, when the external force is removed, the elastic member71returns to the original position, that is, the regular position along the axis in the center. In other words, the displacement due to the mechanical shock is reversible, and when the external force is removed, the annular space between the center electrode2and the annular electrode3also returns to its original state, so that the state of the electromagnetic field is recovered and the characteristics can be maintained.

The length and the number of the connectors5in the circumferential direction and the axial direction, and the type, the arrangement position, and the number of the elastic members71that urge each of the connectors5are not limited to the embodiment exemplified above. For example,FIG.3andFIG.4show an example in which two connectors5each having a length of about ¼ of the circumferential length in the circumferential direction are arranged so as to face each other, but this is not a limitation, and the circumferential length and the number of connectors5may be changed (two or more). In addition, in a case where the elastic members71are arranged to be distributed in the circumferential direction, a material that deforms along the outer circumferential surface4fxmay be used for the connector, and for example, the connector5may be formed of an arc-shaped plate spring.

FIG.3andFIG.4show an example in which the elastic members71are separately arranged at two positions in the axial direction and at three positions in the circumferential direction in each of the connectors5. Needless to say that this is not a limitation, and including the type of the spring, this can be changed as appropriate.

Embodiment 3

In Embodiment 1 and Embodiment 2 described above, examples have been described in which a clearance is provided between the connector and the connection end plate, and the connector and the connection end plate are coupled by an elastically deformable coupling member. In Embodiment 3, a configuration example will be described in which a connector formed of a conductive rubber is used to couple the connector and a connection end plate in a close contact state.FIG.5andFIG.6are diagrams for describing a configuration of a microwave-excited light source device according to Embodiment 3,FIG.5is a partially enlarged cross-sectional view along the axis of the microwave-excited light source device corresponding toFIG.2of Embodiment 1, andFIG.6is a cross-sectional view perpendicular to the axis, corresponding to a line B-B ofFIG.5. Note that as in Embodiment 2, for each of the entire images in the arc tube, the annular electrode, and the center electrode,FIG.1in Embodiment 1 is referred to.

In the microwave-excited light source device1according to Embodiment 3, as shown inFIG.5andFIG.6, the connection end plate6and the annular electrode3are connected to each other via a connector5E formed of a conductive rubber. The connector5E is integrally molded using a conductive rubber (elastic body) so as to have an annular portion5rwhose inside diameter matches the outer diameter D4of the arc tube4, and a disc portion5bthat has a larger diameter than the annular portion and is provided at one end (right side in the figure) of the annular portion5r, with a through hole for passing the center electrode2in the center.

An inner diameter and a thickness of the annular portion5rin the radial direction are large enough to provide a clamping force (pressing force) that is required to maintain stable electrical connection between the annular portion5rand the annular electrode3when the annular portion5ris fitted into the arc tube4. Further, the thickness in the radial direction is set so that a resistance value in the axial direction as the electrical connection path should not be excessive.

As in the coupling member7of Embodiment 1, the thickness of the disc portion5bin the axal direction is determined on the basis of the property of the conductive rubber as an elastic body so as to secure the amount of deformation necessary for achieving the buffering function when a mechanical shock is applied to the arc tube4.

The connection end plate6basically has the same structure as that of Embodiment 2, and is constituted with the conductor portion61for electrical connection to the annular electrode3and the insulator portion62having a through hole formed in the center thereof for passing the center electrode2therethrough, and a male thread is formed on the outer circumferential surface of the conductor portion61.

The coupling member7is formed in a cylindrical shape, the female thread7sfor screwing the connection end plate6is provided on one end side in the axial direction, and an inner edge portion for allowing the annular portion5rto pass and receiving an outer edge portion of the disc portion5bis formed on the other end side. Then, the annular portion5ris to cover the arc tube4together with the annular electrode3such that the annular portion5rprotrudes from the inner edge portion of the coupling member7with the connector5E fitted into the coupling member7. Since the inner diameter of the annular portion5ris smaller than the diameter of the arc tube4, the arc tube4is compressed by the annular portion5rdue to the elasticity as the conductive rubber, and the mechanical support between the arc tube4and the connector5E is established.

In this state, the connection end plate6is screwed into the female thread7suntil the connection end plate6abuts against the disc portion5b, whereby the connection end plate6and the connector5E being an elastic body, and the connector5E and the end surface of the arc tube4are brought into close contact with each other. That is, the relation is established such that the connection end plate6, the connector5E, and the arc tube4are mechanically supported by each other via the coupling member7.

Then, since the connector5E is formed of a conductive material, a stable electrical connection path from the connection end plate6(the conductor portion61thereof) to the annular electrode3via the connector5E is completed with the mechanical fixation of the coupling member7and the connection end plate6by the screwing into the female screw7s. Note that, in Embodiment 3, since the connector5E is in direct contact with the conductor portion61, the coupling member7does not need to be formed of a conductive member, and may be configured to have only a function of mechanically supporting the connector5E and the connection end plate6.

As in Embodiment 1 and Embodiment 2, the center electrode2is mechanically fixed to and supported by the insulator portion62of the connection end plate6, and is electrically connected to the other pole of the microwave generation source100directly or via a coaxial cable or the like. With respect to the relationship with the inner circumferential surface4fiof the inner tube4iof the arc tube4, mechanical connection of the center electrode2is cut with respect to the arc tube4, and the center electrode2is allowed to move in the axial direction of the arc tube4or in a direction inclined with respect to the axis.

On the premise of the configuration described above, it is assumed that a force is applied to the arc tube4in a direction in which the axis is to be inclined. Then, while the forces are applied, the connector5E is deformed, so that the connector5E itself changes in shape similarly to the clearance G7rand the clearance G7adescribed in Embodiment 2. At this time, the arc tube4is displaced with respect to the connection end plate6(and the coupling member7) without accompanying displacement between the connector5E and the annular electrode3, and the stress to be applied to the contact surface between the annular electrode3and the connector5E is suppressed, so that change in the state can be prevented. As a result, no displacement occurs between the annular electrode3in close contact with the outer circumferential surface4fxand the connector5E, and the electrical connection state, i.e., the impedance, can be maintained at the initially set value and desired light emission characteristics can be maintained.

On the other hand, although the center electrode2is mechanically fixed to the connection end plate6, the center electrode2does not hit against the inner circumferential surface4fiof the arc tube4when the center electrode2is displaced, because there is the clearance G24between the center electrode2and the inner circumferential surface4fi. Further, since the displacement is caused by the deformation of the connector5E formed of the conductive rubber, i.e., the displacement caused by the elastic deformation, when the external force is removed, the connector5E returns to the original position, i.e., the regular position along the axis in the center. In other words, the displacement due to the mechanical shock is reversible, and when the external force is removed, the annular space between the center electrode2and the annular electrode3also returns to its original state, so that the state of the electromagnetic field is recovered and the characteristics can be maintained.

Embodiment 4

In the above-described Embodiment 1 to Embodiment 3, examples have been described in which the buffer mechanism that relaxes the stress due to a mechanical shock is formed between the connection end plate constituting the support mechanism, which supports the arc tube, and the annular electrode, with respect to the connection end plate to be electrically connected to the microwave generation source100. On the other hand, in Embodiment 4, unlike Embodiment 1 to Embodiment 3, it is assumed that the microwave generation source100is not fixed to an installation target such as equipment that performs an irradiation process, and is in a mechanically floating state. In addition, an example will be described in which a support mechanism for supporting the connection end plate with respect to the installation target is provided, a second coupling member of an elastic body is interposed between the support mechanism and the connection end plate to form a buffer mechanism.

FIG.7andFIG.8are for describing a configuration of a microwave-excited light source device according to Embodiment 4,FIG.7is a partially enlarged cross-sectional view along the axis of the microwave-excited light source device corresponding toFIG.2of Embodiment 1, andFIG.8is a cross-sectional view perpendicular to the axis, corresponding to a line C-C ofFIG.7. Note that as in Embodiment 2 and Embodiment 3, for each of the entire images in the arc tube, the annular electrode, and the center electrode,FIG.1in Embodiment 1 is referred to.

In the microwave-excited light source device1according to Embodiment 4, as shown inFIG.7andFIG.8, the arc tube4and the connection end plate6are mechanically and fixedly supported by a connector5that electrically connects the annular electrode3and the conductor portion61. The connection end plate6is configured to be supported by a supporting member9for fixing and supporting the device main body through a second connecting member8constituted with an elastic body.

The connector5has a structure like a different diameter joint in which a first annular portion5rlfor covering the outer circumferential surface4fxof the arc tube4, a second annular portion5r2having a thread5scut in the inner circumferential surface for screwing the connection end plate6, and an edge portion5pare integrated. Therefore, as shown inFIG.7, the connection end plate6and the connector5are to be connected. The arc tube4is mechanically fixed by covering the first annular portion5rlin the same manner as described in Embodiment 1 to be electrically connected to the annular electrode3.

Further, the connector5is mechanically fixed to the connection end plate6and electrically connected to the conductor61by screwing the connection end plate6until it abuts against the edge portion5p, similar to the relationship between the coupling member7and the connection end plate6in Embodiment 2. At this time, the connection end plate6and the arc tube4are brought into close contact with each other in the axial direction, so that the arc tube4, the connector5, and the connection end plate6are mechanically and firmly fixed in both the axial direction and the radial direction. However, in an outer circumferential surface of the connection end plate6, the thread5sis not cut in a region to be connected to the second connection member8, and the thread extends from a side close to the arc tube4to a range not reaching the center in the axial direction.

That is, in Embodiment 4, the connector5does not have a buffering function depending on the elastic deformation, but functions as a coupling member for mechanically fixing the arc tube4and the connection end plate6, and also functions as an electrical connection path between the annular electrode3and the conductor portion61. In addition, in Embodiment 4, unlike Embodiment 1 to Embodiment 3, no clearance is provided between the center electrode2and the inner circumferential surface4fiof the arc tube4, and the center electrode2and the arc tube4are also mechanically fixed to each other. That is, the center electrode2, the arc tube4, the annular electrode3, the connector5, and the connection end plate6are mechanically fixed and integrated.

On the other hand, the microwave generation source100is not fixed to the equipment and is in a mechanically floating state, and when a mechanical shock is applied to the arc tube4, the microwave generation source100is also displaced together with the connection end plate6. Therefore, in order to fix the main body of the microwave-excited light source device1to the equipment, the microwave-excited light source device1includes the supporting member9having a fixing base9mfor fixing to the equipment, an annular portion9rsurrounding the outer circumferential surface of the connection end plate6with a clearance G8therebetween, and a second coupling member8for coupling the supporting member9and the connection end plate6.

In the second coupling member8, for example, a plurality of helical springs whose axes are oriented in the radial direction are arranged in a distributed manner in the circumferential direction (at eight positions at intervals of 45 degrees in the figure), and each of the helical springs presses a portion of the outer circumferential surface of the connection end plate6exposed from the connector5(second annular portion5r2). Thus, the supporting member9is configured to mechanically support the connection end plate6, that is, the main body of the microwave-excited light source device1via the elastic body.

On the premise of the configuration described above, it is assumed that a force is applied to the arc tube4in a direction in which the axis is to be inclined. Then, while the force is applied, the helical spring (elastic body) constituting the second coupling member8is deformed, so that the displacement between the connector5and the annular electrode3and the displacement between the connector5and the connection end plate6are not accompanied. Therefore, even if a mechanical shock is applied, the stresses to be applied to the contact surface between the annular electrode3and the connector5and to the contact surface between the connector5and the connection end plate6(the conductor portion61) are suppressed, and the state change can be prevented. As a result, there is no portion where displacement occurs between the annular electrode3in close contact with the outer circumferential surface4fxand the conductor portion61, and the electrical connection state, i.e., the impedance, can be maintained at the initially set value and desired light emission characteristics can be maintained.

Note that, in Embodiment 4, it is assumed that the microwave generation source100is directly fixed to the connection end plate6and is mechanically integrated with the arc tube4, but this is not a limitation. For example, even when the microwave generation source100is electrically connected to the conductor portion61of the connection end plate6and the center electrode2via a flexible coaxial cable, the support mechanism having a mechanical buffering function by the supporting member9and the second coupling member8functions effectively.

Alternatively, even when the annular portion9rof the supporting member9and the second coupling member8may be formed of a conductor to form an electrical connection path to the annular electrode3via the supporting member9, the support mechanism having the mechanical buffering function by the supporting member9and the second coupling member8functions effectively.

Although various exemplary embodiments and examples are described in the present application, various features, aspects, and functions described in one or more embodiments are not inherent in an application of the contents disclosed in a particular embodiment, and can be applicable alone or in their various combinations to each embodiment. Accordingly, countless variations that are not illustrated are envisaged within the scope of the art disclosed herein. For example, the case where at least one component is modified, added or omitted, and the case where at least one component is extracted and combined with a component disclosed in another embodiment are included.

For example, an example in which the annular electrode3is formed of the mesh conductor has been described, but this is not a limitation, and indium-tin oxide (ITO) referred to as a transparent electrode may be used. In addition, although mercury is used as the luminescent material on the premise of sterilization, this is not a limitation, and in a use in which uniform emission (irradiation to a processing target) in the axial direction is desired, sulfur(S), argon (Ar), xenon (Xe), or the like may be used as the luminescent material and the frequency of the microwave may be determined as appropriate in accordance with the material. Further, although the arc tube4is made of quartz glass having a high ultraviolet transmittance, it is needless to say that the material of the arc tube4may be selected as appropriate in accordance with light to be emitted.

As described above, according to the microwave-excited light source device1of the present application, the microwave-excited light source device1that is electrically connected to the microwave generation source100and generates microwave-excited light includes the center electrode2electrically connected to one pole of the microwave generation source100and extending in an axial direction, the annular electrode3concentrically disposed with respect to the center electrode2, the arc tube4that is disposed in an annular space formed between the center electrode2and the annular electrode3and emits the microwave-excited light, the connection end plate6to which the other pole of the microwave generation source100is electrically connected, the connector5that electrically connects the annular electrode3and the connection end plate6, and the buffer mechanism (for example, coupling member7, connector5E, second coupling member8) that is elastically deformed when the arc tube4is subjected to an external force and suppresses stress applied to a contact surface between the annular electrode3and the connector5. Therefore, even if the arc tube4is subjected to an external force such as a mechanical shock, the stress to be applied to the electrical connection portion is relaxed, so that the electrical connection state can be appropriately maintained, and the microwave-excited light source device1capable of performing desired irradiation while suppressing a change in the light emission characteristics can be obtained.

At this time, the microwave-excited light source device is configured such that the connector5has an annular shape, one end side thereof (annular portion5r) in the axial direction fitted to the outer circumferential surface4fxof the arc tube4interposes the annular electrode3between the one end side and the outer circumferential surface4fx, and the clearance G7ain the axial direction is provided between the other end side thereof (edge portion5p) and the connection end plate6. The microwave-excited light source device includes the coupling member7formed of an elastic body that expands and contracts in an axial direction, is disposed in the clearance G7ain the axial direction to couple the connector5and the conductor portion61and functions as the buffer mechanism. As a result, even if the arc tube4is subjected to an external force in any direction, the coupling member7is deformed to relax the stress in the contact surface between the connector5and the annular electrode3, so that the electrical connection state can be appropriately maintained, and the microwave-excited light source device1capable of performing desired irradiation while suppressing a change in the light emission characteristics can be obtained.

Alternatively, the microwave-excited light source device is configured such that the connector5is constituted with a plurality of arc-shaped plates that are divided and arranged in a circumferential direction, and the coupling member7functioning as the buffer mechanism is constituted with the cylindrical portion72that has the inner circumferential surface7fiat one end side in an axial direction facing the outer circumferential surface4fxof the arc tube4with the clearance G7rtherebetween in a radial direction and has the other end side thereof fixed to the connection end plate6(conductor portion61), and the elastic body (elastic member71) that expands and contracts in the radial direction to press the connector5toward the arc tube4. Thus, the stress in the contact surface between the connector5and the annular electrode3is relaxed owing to the deformation of the elastic member71so that the electrical connection state can be appropriately maintained, and the microwave-excited light source device1capable of performing desired irradiation while suppressing a change in the light emission characteristics can be obtained.

In this case, when the arc tube4and the connection end plate6are disposed with the clearance G7atherebetween in the axial direction, even if the arc tube4is subjected to an external force in any direction, the stress in the contact surface between the connector5and the annular electrode3can be relaxed.

The microwave-excited light source device is configured such that the connector5E is formed of a conductive rubber and has the annular shape, one end side thereof (annular portion5r) fitted to the outer circumferential surface4fxof the arc tube4interposes the annular electrode3between the one end side and the outer circumferential surface4fx, and the other end side thereof (disc portion5b) has the disc shape and is interposed between the arc tube4and the connection end plate6in the axial direction, thereby functioning as the buffer mechanism. Thus, the stress in the contact surface between the connector5E and the annular electrode3is relaxed owing particular to the deformation of the disc portion5bof the connector5E, so that the electrical connection state can be appropriately maintained, and the microwave-excited light source device1capable of performing desired irradiation while suppressing a change in the light emission characteristics can be obtained.

In the case described above, if the clearance G24in the radial direction is provided between the inner circumferential surface4fiof the arc tube4and the center electrode2, the center electrode2does not hit against the inner circumferential surface4fiof the arc tube4when the buffer mechanism is deformed, so that the microwave-excited light source device1with higher reliability can be obtained.

Furthermore, the microwave-excited light source device is configured such that the supporting member9fixed to an installation target such as a sterilization treatment tank is provided and the second coupling member8couples the supporting member9and the connection end plate6, is elastically deformed when the arc tube4is subjected to an external force, suppresses stress to be applied to the contact surface between the annular electrode3and the connector5, and functions as the buffer mechanism. Thus, even if the installation target is subjected to an external force that cause the arc tube4to displace, the stress applied to the electrical connection portion is relaxed, so that the electrical connection state can be appropriately maintained, and the microwave-excited light source device1capable of performing desired irradiation while suppressing a change in the light emission characteristics can be obtained.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

1: microwave-excited light source device,100: microwave generation source,2: center electrode,3: annular electrode,4: arc tube,4s: light-emitting space,4fi: inner circumferential surface,4fx: outer circumferential surface,5: connector,5E: connector (buffer mechanism),6: connection end plate,61: conductor portion,62: insulator portion,7: coupling member (buffer mechanism),8: second coupling member (buffer mechanism),9: supporting member, D2: outer diameter (of center electrode), D4i: inner diameter (of inner tube of arc tube), G24: clearance, G7a: clearance (in axial direction), G7r: clearance (in radial direction), G8: clearance.