JP4575123B2 - Dielectric barrier discharge lamp - Google Patents

Description

  The present invention relates to a dielectric barrier discharge lamp that forms excimer molecules by dielectric barrier discharge and emits light emitted from the excimer molecules.

  The dielectric barrier discharge lamp is a discharge lamp using excimer molecules formed by dielectric barrier discharge and utilizing light emitted from the excimer molecules. This type of conventional dielectric barrier discharge lamp has an elongated tubular discharge vessel. An external electrode is provided on the outer peripheral surface of the discharge vessel, and an internal electrode extending along the central axis is provided inside the discharge vessel. In addition, the discharge vessel in which the internal electrode is accommodated is filled with a discharge gas that forms excimer molecules by dielectric barrier discharge.

In such a discharge lamp, there is a problem in that the internal electrode hangs down due to thermal expansion of the internal electrode during discharge, and as a result, the emission intensity of the entire discharge lamp is uneven. As a configuration for reducing the sagging of the internal electrode, a dielectric barrier discharge lamp described in Patent Document 1 is known. In this dielectric barrier discharge lamp, a heat-resistant insert made of a heat-resistant material is inserted in an intermediate portion in the axial direction of the coiled internal electrode in order to reduce the sag of the internal electrode.
JP 2001-84966 A

  However, since the dielectric barrier discharge lamp described in Patent Document 1 has a structure in which the internal electrode supports the heat-resistant insert and the internal electrode itself at both ends, the internal electrode still remains at both ends due to thermal expansion or its own weight. It tends to hang down in the part.

  In order to prevent such drooping, it is possible to increase the tension of the internal electrode by increasing the coil pitch of the internal electrode or by reducing the ratio of the length of the coil portion to the total length of the internal electrode. Conceivable. However, in this case, since the discharge area in the internal electrode cannot be taken sufficiently, the discharge between the external electrodes is concentrated and arc-like discharge is likely to occur. For this reason, the internal electrode is easily sputtered, the internal electrode is consumed more intensively, the light transmittance in the discharge vessel is reduced due to the increased adhesion of the sputtered material to the inner wall of the discharge vessel, and the arc discharge As a result, the load on the discharge vessel increases, leading to a shortened life of the discharge lamp.

  Accordingly, the present invention has been made in view of such problems, and an object thereof is to provide a dielectric barrier discharge lamp capable of realizing uniform and stable light output and long life.

In order to solve the above problems, a dielectric barrier discharge lamp according to the present invention is formed of a light-transmitting material, and has a tubular airtight container in which a rare gas for excimer discharge is enclosed, and an outer periphery of the airtight container. An external electrode, and an internal electrode disposed inside the hermetic container, the internal electrode extending along the axial direction of the hermetic container, both ends being held at both ends of the hermetic container, and the external electrode being A first internal electrode in which a predetermined portion corresponding to the outer peripheral surface of the provided airtight container is linear, and at least one coil-shaped second internal electrode provided for the predetermined portion of the first internal electrode If, it has a main component of the metallic member constituting the second internal electrodes are those that vary from the main component of the metallic member constituting the first internal electrode, and constitutes the first internal electrode The density is lower than the main component of the metal member It is characterized in.

In such a dielectric barrier discharge lamp, the position of the whole internal electrode in the short direction of the hermetic container is held by the first inner electrode held at both ends of the hermetic container. Therefore, since the discharge is generated between the coiled second internal electrode and the external electrode provided at a predetermined portion corresponding to the external electrode of the first internal electrode, the position of the internal electrode Can be sufficiently stabilized. Therefore, even when the discharge area of the second internal electrode is increased, it is possible to avoid sagging due to thermal expansion or its own weight. In this way, by configuring the first internal electrode and the second internal electrode with different components, for example, a material having a small thermal expansion is used as the first internal electrode, or a discharge is performed as the second internal electrode. By adopting a material suitable for the above, it is possible to further stabilize the light output and to prolong the life of the lamp. Further, by making the specific gravity of the second internal electrode smaller than the specific gravity of the first internal electrode in this way, the sag of the internal electrode can be reduced.

  Moreover, it is preferable that the 1st internal electrode is penetrated by the 2nd internal electrode in the predetermined part. By inserting the first internal electrode through the second internal electrode, the second internal electrode is stably supported at a position along the first internal electrode.

  In addition, the second internal electrode is preferably a closely wound coil shape. If this configuration is adopted, the discharge area of the second internal electrode can be expanded in a well-balanced manner.

  The first internal electrode preferably includes a coiled portion. With such a coil-shaped part, even when the internal electrode is thermally expanded, the coil-shaped part acts as a tension holding part and tension is generated in the longitudinal direction of the first internal electrode. The sagging of the internal electrode can be further avoided.

  Furthermore, it is also preferable that the coiled portion is provided between the predetermined portion and the end portion of the first internal electrode. By providing such a coil-shaped portion, it is possible to suppress the sagging of the second internal electrode. Further, since the coiled portion is out of the discharge region between the internal electrode and the external electrode, it is possible to avoid the influence of the discharge on the tension holding action of the coiled portion.

  Moreover, it is also preferable that the coil-shaped part is formed from a predetermined part to between the predetermined part and the end portion of the first internal electrode. By adopting such a configuration, it is possible to maintain a uniform tension over a wide range, and thus it is possible to effectively suppress the position variation of the internal electrode due to thermal expansion over the entire internal electrode with a simple configuration.

  Moreover, it is also preferable that a coil-shaped part has a closely wound area | region. By doing so, the length can be shortened while maintaining the tension holding action, so that the tension of the entire first internal electrode is sufficiently exerted while avoiding the influence of discharge on the tension holding action.

  It is also preferable to further include an internal electrode support portion that is fixed inside the airtight container and supports the internal electrode in the short direction of the airtight container. When such an internal electrode support portion is provided, the movement of the internal electrode in the short direction is restricted, so that the sag of the internal electrode can be further suppressed.

  Furthermore, it is preferable that the internal electrode is close to the inner wall corresponding to the outer peripheral surface provided with the external electrode in the hermetic container. In this case, the discharge that occurs between the internal electrode and the external electrode is mainly creeping discharge along the inner wall of the hermetic container. For this reason, the non-uniformity of the emitted light resulting from the arc-like discharge can be prevented, and the influence on the internal electrode and the airtight container can be reduced.

  Moreover, it is preferable that the diameter of the metal member which comprises a 1st internal electrode is larger than the diameter of the metal member which comprises a 2nd internal electrode. With such a configuration, it is possible to further reduce the sagging of the internal electrode by reducing the relative weight of the second internal electrode, and it is possible to improve the manufacturing efficiency of the second internal electrode.

  Furthermore, it is also preferable that the main component of the metal member constituting the second internal electrode has a lower work function than the main component of the metal member constituting the first internal electrode. In this way, the magnitude of the voltage required for starting and maintaining the discharge can be reduced, so that the load on the electrode and the hermetic vessel can be reduced and the life of the discharge lamp can be extended.

  According to the dielectric barrier discharge lamp of the present invention, uniform and stable light output and long life can be realized.

  Hereinafter, preferred embodiments of a dielectric barrier discharge lamp according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

[First Embodiment]
FIG. 1 is a side view of a dielectric barrier discharge lamp according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG. As shown in FIG. 1, the dielectric barrier discharge lamp 1 includes an elongated tubular hermetic container 2. Both ends of the hermetic container 2 are sealed by sealing with a pinch seal, and a rare gas for excimer discharge is sealed inside. The hermetic container 2 constitutes a dielectric in the dielectric barrier discharge, and is made of a light-transmitting material so that light emitted from the inside of the hermetic container 2 can be emitted to the outside. Consists of. Moreover, although the dimension of the airtight container 2 is determined suitably, it is set as the outer diameter of 10 mm, the inner diameter of 8 mm, and length 400mm, for example.

  An internal electrode 4 is disposed inside the hermetic container 2. The internal electrode 4 includes a core electrode (first internal electrode) 6 extending linearly along the central axis in the longitudinal direction of the hermetic container 2 and a coil shape provided for a predetermined portion of the core electrode 6. And a cover electrode (second internal electrode) 8. In the following description, the central axis of the hermetic container refers to the central axis in the longitudinal direction of the hermetic container.

  The core electrode 6 is made of a tungsten wire having an outer diameter of 0.23 mm, and is formed in a straight line over almost the entire length of the central axis in the airtight container 2. The core electrode 6 is electrically connected to the molybdenum foil 12 by welding or the like with end portions 6 a and 6 b sandwiching a platinum foil (not shown) to one end portion of the rectangular molybdenum foil 12. Yes. Furthermore, one end of a lead wire 14 is connected to the other end of the molybdenum foil 12, and the other end of the lead wire 14 is connected to a lighting power source (not shown).

  Both ends 6a and 6b of the core electrode 6, the molybdenum foil 12 connected thereto, and one end of the lead wire 14 are sealed by the pinch seal portions 10 at both ends of the hermetic container 2, whereby the core electrode 6 is sealed in the hermetic container. 2 is held in a stretched state between both ends.

  Further, a closely wound coil-like portion 16 is formed on the end portion 6b side of the core electrode 6 (right side in FIG. 1). The coil-shaped portion 16 is provided to apply tension to the entire core electrode 6 in a state where the internal electrode 4 is stretched in the hermetic container 2 and to prevent loosening due to the weight of the internal electrode 4. The dimensions of the coil-shaped part 16 are formed with an outer diameter of 1.3 mm, a length of 10 mm, and a coil pitch of about 0.3 mm when wound in a coil shape.

  The core electrode 6 holds the cover electrode 8 by being inserted through the cover electrode 8 along the longitudinal direction of the core electrode 6. The cover electrode 8 is made of a tungsten wire having an outer diameter of 0.15 mm smaller than the core electrode 6, and is formed in a coil shape over the entire length. The cover electrode 8 is formed in a coil shape tightly wound so as to have an inner diameter of 0.25 mm, a length of 310 mm, and a coil pitch of about 0.2 mm while being held by the core electrode 6. The cover electrode 8 is in direct contact with the core electrode 6 in a state where the core electrode 6 is inserted. As a result, the cover electrode 8 is electrically connected to the core electrode 6, and a voltage for discharging is supplied through the core electrode 6. The cover electrode 8 is fixed to the core electrode 6 by welding or caulking at one end 8b thereof. On the other hand, the other end 8 a is not fixed to the core electrode 6. When the cover 8 is fixed at both ends 8a and 8b, there is no escape in the longitudinal direction of the hermetic container 2 even if the cover electrode 8 undergoes thermal expansion during discharge. Impact is likely to occur. For this reason, the discharge distance becomes non-uniform in the longitudinal direction of the hermetic container 2, and uniform discharge may not be obtained as a whole. On the other hand, in the present embodiment, the influence of thermal expansion can be dispersed throughout by letting it escape in the direction from the end portion 8a toward the end portion 6a of the core electrode 6, so that the discharge state is uniform as a whole. Can be maintained. In addition, it is preferable that the end portion to be fixed is an end portion on the side having the coil-shaped portion 16 because the coil-shaped portion 16 is not affected when the cover electrode 8 is thermally expanded.

  Here, when the airtight container 2 is exhausted during manufacturing, both ends of the airtight container 2 are sealed with pinch seals, and then the end side in the central axial direction on the side surface of the airtight container 2 (left side in FIG. 1). Exhaust is performed through the exhaust pipe 18 formed in the above, and then a rare gas for excimer discharge is sealed. The exhaust pipe 18 is sealed with a burner or the like after the rare gas is sealed. The exhaust pipe 18 shown in FIGS. 1 and 2 shows a sealed state.

  An external electrode 20 is disposed on the outer peripheral surface of the hermetic container 2. The outer electrode 20 has a rectangular outer diameter in the unfolded state, and as is understood from FIG. 2, the surface of the external electrode 20 is based on a plane P including the central axis of the airtight container 2 and the central axis of the exhaust pipe 18. It is provided symmetrically. The external electrode 20 is formed in a range of about 120 ° in a clockwise direction and a counterclockwise direction about the exhaust pipe 18 in a total of 240 °, and in a range of about 120 ° to about 240 ° in the clockwise direction. Is opened to form a light emitting portion 22 (see FIG. 2). The external electrode 20 is a metal film, for example, aluminum is vapor-deposited on the hermetic container 2, and has a function as an electrode and a function as a reflecting mirror. As shown in FIG. 1, the external electrode 20 is formed with a length of 310 mm in a region A in the center of the outer peripheral surface of the airtight container 2 in the central axis direction. In FIG. 1, only the vertical cross-sectional portion of the external electrode 20 is shown, and the other portions are not shown.

  Here, the external electrode 20 is not limited to the above-described configuration in which the light emitting portion 22 is formed in a range of about 120 ° to about 240 ° clockwise with respect to the plane P, and a range of a desired light emission angle. The range and angle of the light emitting unit 22 may be changed as appropriate according to the conditions.

  Hereinafter, the positional relationship among the core electrode 6, the cover electrode 8, and the external electrode 20 will be described. As described above, the external electrode 20 has a range of about 120 ° in the clockwise and counterclockwise directions with respect to the plane P (see FIG. 2) in the region A along the central axis direction on the outer peripheral surface of the hermetic container 2. Is formed. On the other hand, the cover electrode 8 is provided at a predetermined portion of the core electrode 6 corresponding to the outer peripheral surface of the airtight container 2 where the external electrode 20 is formed. That is, the cover electrode 8 has one end 8b fixed to the core electrode 6 in a state where the core electrode 6 is inserted in a range in the central axis direction corresponding to the range of the region A of the outer wall of the hermetic container 2. Yes. Moreover, the coil-shaped part 16 of the core electrode 6 is a part except the site | part in which the cover electrode 8 was provided, Comprising: It forms between the site | part and the edge part 6b.

  In the dielectric barrier discharge lamp 1 configured as described above, when an AC voltage is applied between the external electrode 20 and the lead wire 14, the rare gas in the hermetic container 2 is caused between the cover electrode 8 and the external electrode 20. Dielectric barrier discharge occurs, and ultraviolet rays are emitted. A part of the ultraviolet rays are radiated through the light emitting part 22 (see FIG. 2) of the airtight container 2 where the external electrode 20 is not formed, and the remaining ultraviolet rays are reflected by the inner surface of the external electrode 20 and then light is emitted. Radiated from the radiation part 22 to the outside.

  Here, the effects of the dielectric barrier discharge lamp 1 will be described in more detail while comparing with other configuration examples of the dielectric barrier discharge lamp. FIGS. 9 and 11 to 13 are side views showing other configuration examples of the dielectric barrier discharge lamp, in which the external electrode is shown only in the longitudinal section and the other parts are not shown.

  In the dielectric barrier discharge lamp 901 shown in FIG. 9, an external electrode 920 is provided on the outer peripheral surface of the hermetic container 902, and a linear internal electrode 904 is stretched along the central axis inside the hermetic container 902. A coiled portion 916 for applying tension to the entire internal electrode 904 is formed on one end side of the internal electrode 904. The internal electrode 904 is made of a tungsten wire having an outer diameter of 0.18 mm, and the coiled portion 916 is formed with an outer diameter of 0.8 mm and a length of 10 mm while being wound in a coil shape.

  In such a dielectric barrier discharge lamp 901, ultraviolet light is radiated to the outside by dielectric barrier discharge between the linear internal electrode 904 and the external electrode 920 formed on the outer peripheral surface of the hermetic container 902. FIG. 10 is a diagram showing a discharge state as viewed from the central axis direction of the dielectric barrier discharge lamp 901 of FIG. 9, wherein (a) is a diagram showing a normal discharge state, and (b) is an arc-shaped discharge. It is a figure which shows a state. As shown in FIG. 10A, in a normal discharge state, discharge is uniformly generated radially from the internal electrode 904 toward the external electrode 920.

  On the other hand, as shown in FIG. 10B, in the dielectric barrier discharge lamp 901, an arc-like discharge is easily generated such that the discharge path is concentrated on a specific path between the internal electrode 904 and the external electrode 920. This is because the discharge area of the internal electrode 904 is not sufficient because the internal electrode 904 has a linear shape. Due to the arc-like discharge, sputtering is easily generated in the internal electrode 904, so that the internal electrode 904 is consumed intensively, the adhesion of the sputtered material to the inner wall of the hermetic container 902 increases, or the arc-like discharge itself. Or the load on the airtight container 902 increases. As a result, in addition to non-uniformity of the emitted light, the life of the discharge lamp is shortened due to the consumption of the internal electrode 904, the damage of the airtight container 902, and the reduction of the light transmittance.

  A dielectric barrier discharge lamp 921 in FIG. 11 shows an example in which the discharge area of the internal electrode is increased with respect to the above problem. As shown in the drawing, a coiled internal electrode 924 is held along the central axis of the hermetic container 922 of the dielectric barrier discharge lamp 921. A coil-like portion 936 having a relatively dense coil pitch is formed on one end portion side of the internal electrode 924 in order to apply a stronger tension to the entire internal electrode 924. The internal electrode 924 is made of a tungsten wire having an outer diameter of 0.18 mm, and is formed in a coiled state with an outer diameter of 0.8 mm and a coil pitch of 1 mm. The coiled portion 936 has an outer diameter of 0.8 mm, The length is 10 mm and the coil pitch is smaller than 1 mm (for example, the coil pitch is 0.5 mm).

  In such a dielectric barrier discharge lamp 921, since it is easy to increase the discharge area as compared with the linear internal electrode, arc discharge can be prevented to some extent. However, in order to increase the discharge area of the internal electrode 924, it is preferable to increase the proportion of the coil portion in the entire internal electrode 924 and to decrease the coil pitch. The tension at will decrease. Such a decrease in the tension of the internal electrode 924 tends to cause the internal electrode to sag due to its own weight or thermal expansion. As a result, the light emission intensity of the entire discharge lamp becomes uneven. Therefore, it is difficult to achieve both the securing of the discharge area of the internal electrode 924 and the stabilization of the position.

  The dielectric barrier discharge lamp 941 in FIG. 12 shows an example in which the position fluctuation of the internal electrode is reduced with respect to the above problem. As shown in the figure, a coiled internal electrode 944 is held along the central axis of the hermetic container 942 of the dielectric barrier discharge lamp 941. An elongated shaft-shaped heat-resistant insert 946 is inserted in the central portion of the internal electrode 944 in the longitudinal direction. The internal electrode 944 is made of, for example, a tungsten wire having an outer diameter of 0.3 mm, and the heat-resistant insert 946 is made of, for example, a tungsten wire having an outer diameter of 0.7 mm that is thicker than the internal electrode 944. The internal electrode 944 is supported between the both end portions thereof by a disk-shaped or ring-shaped position restrictor 948, thereby preventing the position variation of the airtight container 942 in the short direction.

  In such a dielectric barrier discharge lamp 941, since the internal electrode 944 has a structure that supports its own weight including the heat-resistant insert 946, the dielectric barrier discharge lamp 941 still hangs down at the center between both ends of the heat-resistant insert 946. It tends to occur (see FIG. 13). Although it is possible to reduce the sag of the internal electrode 944 by the position restrictor 948, it is desirable to provide it near the discharge site of the internal electrode 944 because the distribution of the emitted light is biased by the presence of the position restrictor 948. Absent.

  On the other hand, the dielectric barrier discharge lamp 1 shown in FIG. 1 has an airtight container for the entire internal electrode 4 by the core electrode 6 having the end portions 6a and 6b held at the pinch seal portions 10 at both ends of the airtight container 2. The position in the short direction of 2 is maintained. Therefore, since the discharge is generated between the coiled cover electrode 8 provided on the core electrode 6 and the external electrode 20, the position of the internal electrode 4 can be sufficiently stabilized. In this case, even when the ratio of the coil portion is increased or the coil pitch is decreased in order to increase the discharge area of the cover electrode 8, it is held by the core electrode 6. The position of the electrode 4 is not affected. Therefore, it is possible to achieve both securing the discharge area of the internal electrode 4 and avoiding the sagging of the internal electrode 4 due to thermal expansion or its own weight. As a result, it is possible to provide a dielectric barrier discharge lamp that achieves uniform and stable light output and long life.

  Further, since the core electrode 6 is inserted through the cover electrode 8 at a predetermined portion corresponding to the external electrode 20, the cover electrode 8 is stably supported at a predetermined portion along the core electrode 6.

  In addition, since the cover electrode 8 is formed in a closely wound coil shape, the discharge area of the cover electrode 8 can be expanded with a good balance.

  In addition, since the core electrode 6 includes the coil-shaped portion 16, even when the core electrode 6 is thermally expanded, the coil-shaped portion 16 acts as a tension holding portion and tension in the longitudinal direction of the core electrode 6. As a result, the sagging of the internal electrode 4 can be further avoided.

  Further, since the coil-shaped portion 16 is provided between the predetermined portion where the cover electrode 8 is provided and the end portion 6b of the core electrode 6, the sag of the cover electrode 8 can be suppressed. Further, since the coiled portion 16 is out of the discharge region between the internal electrode 4 and the external electrode 20 (region corresponding to the region A in FIG. 1), the influence of the discharge on the tension holding action of the coiled portion 16 is reduced. Can be avoided.

  Further, since the wire diameter of the metal member constituting the core electrode 6 is larger than the wire diameter of the metal member constituting the cover electrode 8, the sagging of the internal electrode 4 is further reduced by the relative weight reduction of the cover electrode 8. In addition, the manufacturing efficiency of the cover electrode 8 can be improved.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 3 is a side view of a dielectric barrier discharge lamp 51 according to the second embodiment of the present invention, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. In the dielectric barrier discharge lamp 51 according to the present embodiment, the cover electrode is composed of two members, and the internal electrode support member is provided between the two cover electrodes in the airtight container of the first embodiment. Different from the one.

  As shown in FIG. 3, an internal electrode support member 58 is attached to the central portion of the airtight container 2 in the central axis direction. The internal electrode support member 58 is a disk-shaped member made of fused silica and having an outer diameter of 7.5 mm and a thickness of 1.5 mm, and a through hole 60 having a diameter of 0.3 mm is formed at the center (FIG. 4). reference). The internal electrode support member 58 having such a shape is arranged on the inner wall of the hermetic container 2 so as to substantially close the hermetic container 2 by having an outer diameter that is substantially equal to and slightly smaller than the inner diameter of the hermetic container 2. The core electrode 6 is inserted into the through hole 60 of the internal electrode support member 58, and the core electrode 6 is supported in the short direction of the airtight container 2 by contacting the inner wall of the through hole 60.

  The core electrode 6 is provided by being inserted through the two cover electrodes 52 and 54 at a predetermined portion corresponding to the range of the region A on the outer peripheral surface of the hermetic container 2. Each of these cover electrodes 52 and 54 is provided over a range in which a predetermined portion of the core electrode 6 is divided into two at the position of the internal electrode support member 58. The cover electrodes 52 and 54 are fixed to the core electrode 6 by welding or caulking at one end portions 52c and 54c on the internal electrode support member 58 side, respectively, and the other end portion is not fixed.

  Also in the dielectric barrier discharge lamp 51 having the above-described configuration, the inner electrode 56 as a whole in the short direction of the hermetic container 2 is held by the core electrode 6 held at both ends 6a and 6b in the pinch seal portion 10 of the hermetic container 2. Thus, the position of the internal electrode 56 can be sufficiently stabilized. Therefore, it is possible to achieve both securing the discharge area of the internal electrode 56 and avoiding the sagging of the internal electrode 56 due to thermal expansion and its own weight. As a result, it is possible to provide a dielectric barrier discharge lamp that achieves uniform and stable light output and long life.

  Further, since the position of the intermediate portion of the core electrode 6 is supported by the internal electrode support member 58, the internal electrode 56 in the short direction of the hermetic container 2 can be dispersed by dispersing the influence of the thermal expansion and the own weight of the internal electrode 56. Can be further stabilized.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. FIG. 5 is a side view of a dielectric barrier discharge lamp 71 according to a third embodiment of the present invention, and FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. The dielectric barrier discharge lamp 71 according to this embodiment is different from that of the first embodiment in that the internal electrode includes a coiled core electrode.

  As shown in FIG. 5, the internal electrode 74 includes a core electrode 76 extending in a coil shape along the central axis of the hermetic container 2, and a coil provided at a predetermined portion of the core electrode 76 with the core electrode 76 inserted therethrough. And a cover electrode 78 having a shape.

  The core electrode 76 is made of a tungsten wire having an outer diameter of 0.23 mm, and is formed in a coil shape over the entire length of the central axis in the airtight container 2. The core electrode 76 is electrically connected to the molybdenum foil 12 by welding or the like with ends 76 a and 76 b sandwiching a platinum foil (not shown) to one end of the rectangular molybdenum foil 12. Yes. Furthermore, one end of a lead wire 14 is connected to the other end of the molybdenum foil 12, and the other end of the lead wire 14 is connected to a lighting power source (not shown). Both ends 76a and 76b of the core electrode 76, the molybdenum foil 12 connected thereto, and one end of the lead wire 14 are sealed in the pinch seal portion 10 of the hermetic container 2, whereby the core electrode 76 is sealed in the hermetic container 2. It is held in a stretched state between both ends.

  At this time, the core electrode 76 is formed in a coil shape so as to have an outer diameter of 0.8 mm and a coil pitch of 1 mm in a state where the core electrode 76 is stretched in the airtight container 2, and a coil shape that applies tension to the entire core electrode 76. Parts. Further, the coil pitch is relatively outside the predetermined portion of the core electrode 76 corresponding to the range of the region A of the outer wall of the hermetic container 2 in the central axial direction and between the predetermined portion and the end portion 76b. A small closely wound coil portion (closely wound region) 86 is formed. The densely wound coil portion 86 has, for example, an outer diameter of 0.8 mm, a coil pitch of about 0.3 mm, and a length of 10 mm.

  A cover electrode 78 is provided along a longitudinal direction of the core electrode 76 at a predetermined portion corresponding to the region A of the core electrode 76 (see FIG. 6). The cover electrode 78 is made of a tungsten wire having an outer diameter of 0.15 mm smaller than the core electrode 76, and is formed in a coil shape over the entire length. The cover electrode 78 is formed by being tightly wound in a coil shape so that the inner diameter is 0.85 mm, the length is 310 mm, and the coil pitch is about 0.2 mm in a state where the core electrode 76 is inserted. It is electrically connected by contacting 76. The cover electrode 78 is fixed to the core electrode 76 by welding or caulking at one end 78b, and the other end 78a is not fixed.

  In the dielectric barrier discharge lamp 71 configured as described above, the entire core electrode 76 is formed as a tension holding portion from a predetermined portion corresponding to the region A to between the predetermined portion and the end portions 76a and 76b. Therefore, uniform tension can be maintained over a wide range, and position variation due to thermal expansion over the entire internal electrode 74 can be effectively suppressed with a simple configuration. It should be noted that both ends of the core electrode 76 may be formed in a straight line so as to facilitate the bonding with the molybdenum foil 12.

  Further, the core electrode 76 is formed with a closely wound coil portion 86, and the coil pitch of the closely wound coil portion 86 is relatively small and the tension holding action is strengthened. The tension of the entire core electrode 76 is sufficiently exerted compared with the case where it is made. In addition, since the close-wound coil portion 86 is provided on the outer side in the central axis direction with respect to the predetermined portion where the cover electrode 78 is provided, it is possible to avoid the influence on the discharge tension holding action.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. FIG. 7 is a side view of a dielectric barrier discharge lamp 91 according to a fourth embodiment of the present invention, and FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. In the dielectric barrier discharge lamp 91 according to the present embodiment, the internal electrode is provided close to the inner wall of the airtight container, and the cover electrode is composed of two members, and the internal electrode is interposed between the two cover electrodes. The point from which the support member is provided differs from the thing of 1st Embodiment.

  As shown in FIG. 7, an internal electrode 94 is provided in the hermetic container 2 of the dielectric barrier discharge lamp 91. The internal electrode 94 includes a core electrode 96 that extends linearly in parallel with the central axis of the hermetic container 2, and two coil-shaped cover electrodes 98 and 100 that are divided into predetermined portions of the core electrode 96. It is comprised including.

  Both ends 96a and 96b of the core electrode 96, the molybdenum foil 12 connected thereto, and one end of the lead wire 14 are in the direction in which the external electrode 20 of the hermetic container 2 is provided in the pinch seal part 10 of the hermetic container 2. The core electrode 96 is held in a state where it is stretched between both end portions of the hermetic container 2. That is, as shown in FIG. 8, the core electrode 96 is disposed close to the inner wall on the opposite side across the tube wall of the hermetic container 2 with respect to the outer peripheral surface on which the outer electrode 20 of the hermetic container 2 is provided. Has been.

  An internal electrode support member 102 is attached to the central portion of the core electrode 96 in the longitudinal direction. The internal electrode support member 102 is made of, for example, a metal wire such as tungsten or nickel having an outer diameter of 0.5 mm, and has a circular portion having a diameter substantially equal to the inner diameter of the hermetic container 2 (see FIG. 8). Due to the presence of the circular portion, the internal electrode support member 102 has a biasing force in the direction in which the circular portion is widened. The position of the internal electrode support member 102 is maintained by bringing the outer edge of the circular portion into contact with the inner wall of the airtight container 2. Furthermore, the central portion of the core electrode 96 is sandwiched between the internal electrode support member 102 and the inner wall of the airtight container 2 on the side where the external electrode 20 is provided. Thus, the core electrode 96 is pressed against and contacts the inner wall of the airtight container 2 on the side where the external electrode 20 is provided by the biasing force of the internal electrode support member 102.

  Further, the core electrode 96 is inserted into the two cover electrodes 98 and 100 at a predetermined portion corresponding to the range of the region A (see FIG. 7) on the outer peripheral surface of the hermetic container 2. Each of these cover electrodes 98 and 100 is provided over a range in which a predetermined portion of the core electrode 96 is divided into two at the position of the internal electrode support member 102. The cover electrodes 98 and 100 are fixed to the core electrode 96 by welding or caulking at one end portions 98c and 100c on the internal electrode support member 102 side, and the other end portions are not fixed.

  In the dielectric barrier discharge lamp 91 configured as described above, the internal electrode 94 provided inside the hermetic container 2 is disposed in contact with the inner wall of the hermetic container 2 on the side where the external electrode 20 is provided. Yes. In such a state, the discharge generated between the cover electrodes 98 and 100 and the external electrode 20 is mainly creeping discharge along the inner wall of the airtight container 2 on the side where the external electrode 20 is provided. During such creeping discharge, arc-like discharge is maintained in an extremely small state. Therefore, the influence of the discharge load on the hermetic container 2 and the internal electrode 94 and the occurrence of sputtering of the internal electrode 94 can be reduced. Furthermore, the non-uniformity of the emitted light caused by the arc discharge can be prevented.

  In addition, this invention is not limited to embodiment mentioned above. For example, the metal wires of the core electrodes 6, 76, 96 and the cover electrodes 8, 52, 54, 78, 98, 100 constituting the internal electrode are not limited to specific ones, and the main metal wires of each metal wire Different components may be used. If it does in this way, the material suitable for maintaining tension | tensile_strength as a core electrode can be used, and the material excellent in the discharge characteristic can be used as a cover electrode. Here, as a material of the core electrode, it is preferable to use tungsten, molybdenum, or the like, which is a material having a relatively large elastic modulus and a low coefficient of thermal expansion, from the viewpoint of maintaining the tension.

  In this case, it is also preferable that the main component of the metal wire constituting the cover electrode has a work function lower than that of the metal wire constituting the core electrode. As a metal wire for such a cover electrode, when a tungsten wire is used as the core electrode, a tritated tungsten wire having a work function lower than that of pure tungsten, or an electron emission property such as oxide on the surface of the tungsten wire. What applied the material etc. can be used. Thereby, the magnitude of the voltage required for starting and maintaining the discharge can be reduced, so that the load on the electrode and the hermetic vessel can be reduced and the life of the discharge lamp can be extended.

  It is also preferable that the main component of the metal wire constituting the cover electrode has a lower density than the main component of the metal wire constituting the core electrode. As a metal wire for such a cover electrode, when a tungsten wire is used as the core electrode, a nickel wire having a lower density than tungsten, a molybdenum wire, or the like can be used. Thus, by making the specific gravity of the cover electrode smaller than the specific gravity of the core electrode, the sag of the internal electrode can be reduced.

  In addition, the external electrode 20 may be provided on the outer peripheral surface of the hermetic container 2 as a metal film on the outer peripheral surface of the hermetic container 2 or as a wire formed in a net shape or a loop shape.

  Further, the cover electrode is not limited to being provided at a predetermined position of the core electrode in a state where the core electrode is inserted, and may be formed in a coil shape by being wound around the core electrode. The formed cover electrode itself may be wound around the core electrode.

1 is a side view of a dielectric barrier discharge lamp according to a first embodiment of the present invention. It is sectional drawing along the II-II line of FIG. It is a side view of the dielectric barrier discharge lamp which is 2nd Embodiment of this invention. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. It is a side view of the dielectric barrier discharge lamp which is 3rd Embodiment of this invention. It is sectional drawing along the VI-VI line of FIG. It is a side view of the dielectric barrier discharge lamp which is 4th Embodiment of this invention. It is sectional drawing along the VIII-VIII line of FIG. It is a side view which shows the other structural example of a dielectric barrier discharge lamp. It is a front view which shows the discharge state of the dielectric barrier discharge lamp of FIG. 9, (a) is a figure which shows a normal discharge state, (b) is a figure which shows an arc-shaped discharge state. It is a side view which shows the other structural example of a dielectric barrier discharge lamp. It is a side view which shows the other structural example of a dielectric barrier discharge lamp. It is a principal part expanded side view of the dielectric barrier discharge lamp of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,51,71,91 ... Dielectric barrier discharge lamp, 2 ... Airtight container, 4, 56, 74, 94 ... Internal electrode, 58, 102 ... Internal electrode support member, 6, 76, 96 ... Core electrode (1st , 8, 52, 54, 78, 98, 100 ... cover electrode (second internal electrode), 16, 106 ... coiled portion, 86 ... coil portion (closely wound region), 20 ... external electrode.

Claims (11)

A tubular airtight container made of a light transmissive material and filled with a rare gas for excimer discharge;
An external electrode disposed on the outer periphery of the hermetic container;
An internal electrode disposed inside the hermetic container;
With
The internal electrode is
The airtight container extends along the axial direction of the airtight container, both end portions are held at both end portions of the airtight container, and a predetermined portion corresponding to the outer peripheral surface of the airtight container provided with the external electrode is linear. 1 internal electrode;
At least one coiled second internal electrode provided for the predetermined portion of the first internal electrode;
I have a,
The main component of the metal member that constitutes the second internal electrode is different from the main component of the metal member that constitutes the first internal electrode, and the metal member that constitutes the first internal electrode. The density is smaller than the main component,
A dielectric barrier discharge lamp.   The dielectric barrier discharge lamp according to claim 1, wherein the first internal electrode is inserted into the second internal electrode at the predetermined portion.   3. The dielectric barrier discharge lamp according to claim 1, wherein the second internal electrode has a closely wound coil shape. 4.   The dielectric barrier discharge lamp according to claim 1, wherein the first internal electrode includes a coiled portion.   5. The dielectric barrier discharge lamp according to claim 4, wherein the coil-shaped portion is provided between the predetermined portion and an end portion of the first internal electrode.   5. The dielectric barrier discharge lamp according to claim 4, wherein the coil-shaped portion is formed from the predetermined portion to between the predetermined portion and an end portion of the first internal electrode.   The dielectric barrier discharge lamp according to claim 4, wherein the coil-shaped portion has a densely wound region.   The dielectric according to any one of claims 1 to 7, further comprising an internal electrode support portion that is fixed inside the hermetic container and supports the internal electrode in a short direction of the hermetic container. Barrier discharge lamp.   The dielectric barrier according to any one of claims 1 to 8, wherein the internal electrode is close to an inner wall corresponding to an outer peripheral surface of the hermetic container where the external electrode is provided. Discharge lamp.   10. The dielectric according to claim 1, wherein a diameter of a metal member constituting the first internal electrode is larger than a diameter of a metal member constituting the second internal electrode. Body barrier discharge lamp. 11. The main component of the metal member constituting the second internal electrode has a work function lower than that of the metal member constituting the first internal electrode . The dielectric barrier discharge lamp according to any one of claims.

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