JP4294535B2 - High pressure discharge lamp - Google Patents

Description

  The present invention relates to a high pressure discharge lamp. In particular, the present invention relates to a high-pressure discharge lamp that is suitably used for lighting a high ceiling, a store, a street, and the like.

  Conventionally, high-pressure discharge lamps used in high ceilings, stores, streets, etc. are arc tubes made of quartz glass or ceramic materials, outer tubes, and wire frames made of conductive materials that support the arc tubes in the outer tubes. (For example, refer to Patent Document 1). Since the arc tube of this type of high-pressure discharge lamp becomes very hot during lighting, mitigating thermal stress generated in the arc tube is an important point for preventing the arc tube from being damaged. Patent Document 1 discloses a structure in which stress caused by thermal expansion of an arc tube generated during lighting is released to a coil provided at one end of a wire frame.

  Similarly, for the purpose of preventing breakage of the arc tube, there is also a prior art in which compressive stress is made latent in the arc tube material in advance in order to relieve the tensile stress generated on the arc tube surface during lighting (for example, patents). Reference 2 and Patent Document 3). In these techniques, the tensile stress generated during lighting is canceled out by the compressive stress that has been latent in advance, and as a result, the lamp is prevented from being damaged.

  Recently, lighting conditions required for high-pressure discharge lamps have changed. Broadly speaking, there are two conditions. One of these high-pressure discharge lamps, particularly metal halide lamps, is required to have higher efficiency. In order to improve luminous efficiency, the operating pressure in the arc tube is increased from the conventional several atmospheres (about 5 to 9 atmospheres) to several ten. It is necessary to increase to atmospheric pressure (about 10 to 15 atmospheric pressure). There are several ways to increase the operating pressure. For example, a general method is to reduce the shape of the arc tube, increase the tube wall load, raise the arc tube temperature more than before, and promote the evaporation of the encapsulated metal. The other is the lighting posture of the lamp. Conventionally, vertical lighting has been used relatively frequently, but the use from horizontal lighting has also been increasing in order to realize space saving in terms of design of lighting equipment.

  However, all of the conventional techniques alleviate the thermal stress generated in the arc tube during lighting under the condition of several operating pressures and vertical lighting. There is no provision for measures against thermal stresses generated in the arc tube under conditions of high operating pressure of about a few ten atmospheres and horizontal lighting.

US Pat. No. 6,326,721 JP-A-2-301957 JP 60-225159 A

  An object of the present invention is to alleviate thermal stress generated in an arc tube of a high-pressure discharge lamp. In particular, an object of the present invention is to alleviate thermal stress generated in the arc tube under conditions of high operating pressure of about several tens of atmospheres and horizontal lighting, thereby preventing breakage of the high-pressure discharge lamp.

  A first aspect of the present invention includes a light emitting unit, a pair of electrodes disposed so as to face each other in the light emitting unit, and a pair of side tube portions extending in an axial direction connecting the electrodes from both ends of the light emitting unit. And a support structure that supports the arc tube so as to restrict displacement in a direction orthogonal to at least the axis, and a base end side is supported by the support structure, while a distal end side of the arc tube A thermal stress is generated by a temperature change at the time of switching from the lighting state to the extinction state, and the thermal stress is connected to the side tube portion, and the thermal stress is arranged in a posture in which the axis extends in the horizontal direction. There is provided a high-pressure discharge lamp including a pair of thermal stress generating members that act as a downward force in the vertical direction with respect to the arc tube and as an outward force on the arc tube.

  Under the condition of a high operating pressure of about several tens of atmospheres and horizontal lighting, the maximum thermal stress is generated in the upper part in the vertical direction of the light emitting part due to the temperature change when switching from the lighting state to the extinguishing state. The direction of this thermal stress is tensile. The thermal stress generated by the thermal stress generating member acts as a downward force in the vertical direction with respect to the side tube portion of the arc tube and as an outward force with respect to the arc tube, so the vertical stress of the arc tube where the maximum tensile stress acts A compressive stress acts on the upper part of the direction. Therefore, by providing a thermal stress generating member, the thermal stress acting on the arc tube at the time of switching from the lighting state to the extinguishing state can be alleviated, cracking and breakage of the arc tube can be prevented, and the life of the high pressure discharge lamp can be extended. Can do.

  Specifically, the high-pressure discharge lamp includes a pair of connecting members that connect the side tube portion and the distal end side of the thermal stress generating member.

  More specifically, the connecting member extends from the annular portion in a direction away from the side tube portion, and the distal end side of the thermal stress generating member is fixed. And a fixed portion. The connecting member may be fixed to the side tube portion by caulking the annular portion to the side tube portion. In this case, a groove into which the annular portion is fitted may be formed on the outer peripheral surface of the side tube portion.

When the electrode extends in the axial direction and protrudes to the outside of the arc tube through the side tube portion, the support structure includes a wire frame that supports the electrode and is electrically connected to a lighting circuit. The base end of the thermal stress generating member may be fixed to a pair of support shafts extending from the wire frame toward the side tube portion.

  The thermal stress generating member is made of a single metal material having a bimetal or a desired linear expansion coefficient.

  The present invention is preferably applied when the arc tube is made of a ceramic material, but the arc tube may be made of another material such as quartz.

  The present invention is suitably applied when the light-emitting substance enclosed in the light-emitting portion is turned on, that is, when the operating pressure is 10 MPa or more.

  The high pressure discharge lamp may further include an outer tube surrounding the arc tube.

A second aspect of the present invention, have a light emitting portion, the thermal stress generated with the arc tube which is horizontally operated by temperature change when switching from the lighting state to the OFF state, the thermal stress of the light emitting portion Provided is a high-pressure discharge lamp comprising a thermal stress generating member that generates compressive stress in an upper part.

  In the high-pressure discharge lamp of the present invention, by providing a thermal stress generating member, it acts on the arc tube at the time of switching from the lighting state to the extinguishing state under a condition of a high level of operating pressure, particularly about 10 or more atm. It is possible to relieve the thermal stress, prevent cracking and breakage of the arc tube, and extend the life of the high-pressure discharge lamp.

  The present inventor has found that when a high pressure discharge lamp is used under the condition of horizontal lighting at a high operating pressure, the arc tube is easily damaged immediately after switching from the lighting state to the extinguishing state. The thermal stress that causes this failure was analyzed. The present invention is based on new knowledge obtained by such analysis. The rise in pressure and temperature when the lamp is started, that is, when switching from the extinguished state to the lit state follows the evaporation of the encapsulated metal and is sufficiently gradual. However, under the condition of high operating pressure and horizontal lighting, there is a rapid temperature drop immediately after the light is turned off or when switching from the lighted state to the turned off state.

  FIG. 1 shows a temperature distribution during stable lighting of an arc tube 1 of a metal halide lamp which is a kind of high-pressure discharge lamp. The arc tube 1 is made of a ceramic material mainly composed of alumina (Al2O3). Inside the light emitting unit 1a, an enclosed metal containing mercury and a metal halide and a rare gas as a buffer gas are enclosed. The operating pressure is 10-15 Pa. Further, the arc tube 1 has a lighting posture (horizontal lighting) in which a virtual straight line or an axis L connecting a pair of electrodes 2A and 2B disposed therein extends in a substantially horizontal direction. The arc tube 1 can be thermally expanded in the direction of the axis L extending in the horizontal direction, but is supported so as to be restricted in displacement in a direction perpendicular to the axis L (including the vertical direction).

  In FIG. 1, the higher the density of dots attached to each region partitioned by the isotherm T, the higher the region. When a part of the supplied electric power is consumed as thermal energy, the inside of the light emitting unit 1a is heated to a high temperature close to 1,100 ° C. Further, since the lighting posture is horizontal, a temperature difference close to 100 ° C. occurs between the upper part and the lower part of the arc tube 1. Specifically, the temperature at the upper part of the inner wall surface of the arc tube 1 indicated by the point t1 is about 1070 ° C., whereas the temperature at the lower part of the inner wall surface of the light emitting part 1a is about 930 ° C. The temperature difference in the light emitting part 1a is generated as a result of a convection phenomenon in a high temperature and high pressure state due to a large amount of encapsulated metal being filled in the light emitting part 1a. Therefore, the temperature difference increases as the lighting pressure in the light emitting unit 1a increases.

  FIG. 2 shows a calculation result obtained by simulating each part stress generated when the light emitting unit 1a is turned on in such a high temperature and high pressure state by using a finite element method. Specifically, FIG. 2 shows that the temperature distribution shown in FIG. 1 changes according to the conditions simulating the actual measured value of the temperature decrease immediately after the light is turned off, and changes to each part of the arc tube 1 in the state where the temperature returns to room temperature. The distribution of the generated thermal stress is shown. In FIG. 2, it is shown that the higher the density of dots attached to each region partitioned by the isostress line P, the greater the thermal stress. As is clear from FIG. 2, the portion of the arc tube 1 where the strongest tensile stress is generated is the upper portion of the inner wall surface. The tensile stress is maximum (111 MPa) at the point p1 at the uppermost part of the inner wall surface, and the tensile stress value decreases as it moves downward. For example, the tensile stress at the point p2 at the center of the inner wall surface is 30 MPa. In addition, compressive stress is generated on the lower side of the inner wall. For example, a compressive stress of −40 MPa is generated at the point p3 at the bottom of the inner wall surface. As shown by arrows M1 and M2 in FIG. 3, the tensile stress is generated in the side tube portions 1b and 1c (in the direction of the axis L). This corresponds to a portion where the arc tube is broken in an actual lamp intensity test.

  As described above, when a high pressure discharge lamp is used under the conditions of high operating pressure and horizontal lighting, a large thermal stress in the tensile direction is generated at the top of the arc tube when switching from the lighting state to the extinguishing state, and this thermal stress is generated by the arc tube. It was found to cause damage.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 3 shows a metal halide lamp that is a high-pressure discharge lamp according to an embodiment of the present invention. The arc tube 1 includes an elongated hollow tubular light-emitting portion 1a, a pair of side tube portions 1b and 1c extending from both ends of the light-emitting portion 1a, and a pair of electrodes 2A with the tips exposed inside the light-emitting portion 1a. , 2B. The side tube portions 1b and 1c extend along an imaginary straight line or an axis L connecting the electrodes 2A and 2B. In the present embodiment, the light emitting portion 1a and the side tube portions 1b and 1c are made of a ceramic material whose main material is alumina (Al2O3). The base ends of the electrodes 2A and 2B are led out of the arc tube 1 through the narrow tube portions 1d of the side tube portions 1b and 1c. An outer tube 21 is provided so as to surround the arc tube 1.

  The electrical connection structure will be described. In the drawing, the base end of the right electrode 2A is connected to the support member 3, and the base end of the left electrode 2B is connected to the deformable member 4. Further, the support member 3 is connected to the wire frame 5, and the deformable member 4 is connected to the wire frame 6. The wire frames 5 and 6 are connected to an external lighting circuit (not shown) through a base 7.

  A light emitting material such as mercury or a metal halide such as a metal halide, or a rare gas as a buffer gas is sealed inside the light emitting portion 1a. The pressure in the light emitting unit 1a during lighting, that is, the operating pressure is 10 to 15 MPa. The lighting posture is horizontal. Specifically, this metal halide lamp has a lighting posture in which an axis L connecting the pair of electrodes 2A and 2B is substantially horizontal.

  Next, a support structure for the arc tube 1 will be described. One wire frame 5 extends horizontally from the base 7 through the lower side of the arc tube 1, and its tip is fixed to a recessed portion 21 a of the outer tube 21. The other wire frame 6 extends from the base 7 in the horizontal direction, and its tip is located near the side tube portion 1 c of the arc tube 1. The tip of the wire frame 6 is positioned above the arc tube 1. The proximal end side of the right electrode 2 </ b> A is mechanically supported by the wire frame 5, and the proximal end side of the left electrode 2 </ b> B is mechanically supported by the wire frame 6.

  In general, the arc tube 1 is expanded by thermal expansion when the lamp is stably lit compared to when it is cold. The arc tube 1 has the largest thermal expansion in the horizontal direction (the direction of the axis L). The arc tube 1 is supported so as to relieve stress generated in the arc tube 1 due to thermal expansion during lighting. First, a deformable member 4 and a support member 8 that extend in the vertical direction are provided corresponding to the base end side of the left electrode 2B in the drawing. The deformable member 4 is made of a material that is conductive and relatively freely deformed, such as a stranded wire made of a conductive material. The deformable member 4 has an upper end welded to the wire frame 6 at the connection point 21 and a lower end welded to the proximal end side of the electrode 2B at the connection point 22. The upper end of the support shaft member 8 is welded to the wire frame 6 at the connection point 17 and has a ring-shaped portion 8a at the lower end. The base end side of the electrode 2B is inserted through the ring-shaped portion 8a, but is not fixed to the ring-shaped portion 8a. On the other hand, a support member 3 extending in the vertical direction is provided corresponding to the base end side of the right electrode 2A in the drawing. The lower end side of the support member 3 is welded to the wire frame 5 at the connection point 20. The base end side of the electrode 2 </ b> A is welded to the support member 3 at the connection point 10. Since the left electrode 2B is inserted into the ring-shaped portion 8a and the deformable member 4 is deformable, the electrode 2B can be displaced in the direction of the axis L. However, the displacement of the electrode 2B in the direction orthogonal to the horizontal direction (including the vertical direction) is restricted by the ring-shaped portion 8a. On the other hand, since the right electrode 2A is fixed to the support member 3, displacement in the direction of the axis L and the direction orthogonal thereto is restricted. Therefore, the arc tube 1 can expand in the horizontal direction along the axis L, and stress generated by this expansion is relieved, but displacement in a direction orthogonal to the horizontal direction is restricted.

  When the arc tube 1 is regarded as a beam, the right end is a fixed end fixed to the support member 3 as shown in FIG. 6, and the left end is only displaced in the direction perpendicular to the axis by the ring-shaped portion 8a. Is the regulated rotation end.

  Next, a structure for relieving the thermal stress generated in the arc tube 1 when the light is extinguished will be described with reference to FIGS.

  Support shafts 11 and 12 extending upward in the vertical direction are connected to the wire frame 5. The support shaft 11 is arranged on the lower side of the right side pipe portion 1b in the figure, the lower end is welded to the wire frame 5 at the connection point 20, and the upper end faces the side pipe portion 1b with a gap. Yes. On the other hand, the support shaft 12 is disposed on the lower side of the left side pipe portion 1c in the figure, the lower end is welded to the wire frame 5 at the connection point 19, and the upper end faces the side pipe portion 1c with a gap. is doing.

  Stoppers or connecting members 13 and 14 are attached to the side tube portions 1b and 1c, respectively. Referring to FIG. 4, the connecting member 14 is formed by forming a band-shaped metal plate, and an annular portion 14a wound around and attached to the outer peripheral surface of the side tube portion 1c, and a fixing portion 14b extending downward from the annular portion 14a. It has. The annular portion 14a is wound obliquely with respect to the side tube portion 1c, and the contact position 14c of the annular portion 14a with respect to the upper portion of the side tube portion 1c is more than the contact position 14d of the annular portion 14a with respect to the lower portion of the side tube portion 1c. It is located on the inner side, that is, the light emitting unit 1a side. The annular portion 14a is mounted so as not to easily shift with respect to the side tube portion 1c, and the contact positions 14d and 14c do not move. The material, shape, and attachment posture of the connecting member 13 with respect to the side tube portion 1b are the same as those of the connecting portion 14.

  The support shafts 11 and 12 and the connecting members 13 and 14 are connected by bimetals 15 and 16 as thermal stress generating members. Referring to FIG. 5, the base end side of the bimetal 16 is welded to the support shaft 12, and the tip end side is welded to the fixing portion 14 b of the connecting member 14. The bimetal 16 is a laminate of a plate material (high thermal expansion plate material 31) made of an alloy material having a high thermal expansion coefficient and a plate material (low thermal expansion plate material 32) made of an alloy material having a low thermal expansion coefficient, and has a thermal deformation effect. . That is, when the temperature rises, the high thermal expansion plate material 31 is deformed to a greater extent than the low thermal expansion plate material 32, so that it is bent toward the low thermal expansion member 32 side. In the present embodiment, the bimetal 16 is arranged so that the low thermal expansion plate 32 is positioned above the high thermal expansion member 31 in the vertical direction, that is, on the arc tube 1 side. Further, the materials, shapes, and dimensions of the high thermal expansion plate member 31 and the low thermal expansion member 32 are curved toward the low thermal expansion member 32 as shown by the solid line A in FIG. 5 due to the radiant heat from the arc tube 1 that is stably lit. And is fixed to the support shaft 12 and the connecting member 14. The structure and mounting posture of the bimetal 15 that couples the support shaft 11 and the coupling member 13 are the same as those of the bimetal 16.

  Since the lighting pressure of the metal halide lamp of the present embodiment is high (10 to 15 MPa) and the lighting posture is horizontal, as described with reference to FIGS. 1 and 2, the lighting state is switched from the lighting state to the extinguishing state. At the time of switching, a large thermal stress in the tensile direction is generated at the top of the arc tube 1a. This thermal stress acts on the arc tube 1 as a deforming force for deforming the light emitting portion 1a into a bow shape projecting upward in the vertical direction, as schematically indicated by a dotted line in FIG.

  On the other hand, immediately after the metal halide lamp is turned off, the radiant heat from the arc tube 1 rapidly decreases and the temperature decreases, so that the high thermal expansion plate 32 of the bimetals 15 and 16 starts to shrink rapidly. Referring again to FIG. 5, if the bimetal 16 is not welded to the connecting member 14, the bimetal 16 is rapidly deformed into a linear shape indicated by a dotted line B due to a temperature drop. However, since the displacement is restricted by welding both ends of the bimetal 16 to the support shaft 12 and the connecting member 14 in practice, the bimetal 16 hardly changes from the shape shown by the solid line A, and thermal stress is generated. The thermal stress generated in the bimetal 16 acts as a force indicated by an arrow Y on the side tube portion 1 c of the arc tube 1 through the connecting member 14. Referring also to FIG. 3, thermal stress is also generated in the bimetal 15 due to the temperature decrease immediately after the light is turned off, and this thermal stress is indicated by an arrow X with respect to the side tube portion 1 b of the arc tube 1 through the connecting member 13. Acts as a force. The directions of the forces X and Y acting on the side tube portions 1b and 1c due to the thermal stress generated in the bimetals 15 and 16 are obliquely downward, specifically, vertically downward with respect to the side tube portions 1b and 1c, and the side tube portions. It is outward (direction away from the light emission part 1a) with respect to 1b and 1c. Accordingly, as schematically indicated by a one-dot chain line in FIG. 6, these forces X and Y act on the arc tube 1 as a deforming force for deforming the light emitting portion 1 a into a bow shape projecting downward in the vertical direction, A compressive stress is generated in the upper part of the inner wall surface of the arc tube 1. In other words, the forces X and Y cause the arc tube 1 to deform in a direction opposite to the deformation of the arc tube 1 (dotted line in FIG. 6) due to thermal stress generated in the arc tube 1 when switching from the lighting state to the extinguishing state. Let Therefore, due to forces X and Y acting on the arc tube 1 from the bimetals 15 and 16 via the connecting members 13 and 14, thermal stress in the tensile direction generated on the inner wall surface of the light emitting portion 1a immediately after the arc tube 1 is extinguished, particularly The thermal stress at the uppermost inner wall surface (see position t1 in FIG. 2) of the light emitting unit 1a is effectively relieved.

  7A and 7B show another example of the connecting member. The annular portion 13 a of the connecting member 13 is caulked to the side tube portion 1 b, and the entire inner surface of the annular portion 13 a is in close contact with the outer peripheral surface of the connecting member 13. Further, the lower end of the fixed portion 13 b is folded back and the folded portion is welded to the upper surface of the bimetal 15. Since the connecting member 13 is firmly fixed to the side tube portion 1b by caulking the annular portion 13a to the side tube portion 1b, the thermal stress generated in the bimetal 15 when the light is extinguished is reliably transmitted through the connecting member 13. Propagates to the arc tube 1. The other connecting member 14 (see FIG. 3) may have a similar structure.

  8A and 8B show still another example of the connecting member. An annular groove 1d is formed on the outer peripheral surface of the side tube portion 1b, and the annular portion 13a of the connecting member 13 is fitted into the groove 1d. The annular portion 13a is caulked to the side tube portion 1b. By fitting the annular portion 13a into the groove 1d, the position of the annular portion 13a in the axis L direction relative to the side tube portion 1b can be more reliably prevented, so that the thermal stress of the bimetal 15 is more reliably applied to the arc tube 1. Propagate. The other connecting member 14 (see FIG. 3) may have a similar structure.

  The relaxation of the tensile stress at the upper part in the vertical direction of the light emitting unit 1a with the above configuration works more effectively as the pressure in the light emitting unit 1a becomes higher. In particular, it is effective when the internal pressure when the light emitting unit 1a is turned on is 10 MPa (about 10 atm) or more. What is necessary is just to enclose the mixture of PrI3, CsI, and NaI in the light emission part 1a as an enclosure with which the light emission part 1a becomes 10 Mpa or more at the time of lighting.

  In order to sufficiently exhibit the effect of relaxing the tensile stress of the light emitting portion 1a with the above configuration, there are some points to be taken into consideration in design. The first is the strength of the wire frames 5 and 6, the support members 3 and 8, and the support shafts 11 and 12. In order to effectively apply the thermal stress generated by the bimetals 15 and 16 as the forces X and Y for relaxing the thermal stress in the tensile direction of the light emitting portion 1a, the peripheral wire frames 5 and 6, the supporting members 3 and 8, The support shafts 11 and 12 must be made of a material, shape, and dimensions that are not easily deformed. When stainless steel is used as the conductive metal material, the diameter is desirably 0.5 mm or more. Similarly, it is needless to say that the connection points 10 and 17 to 20 need to be firmly welded so that the supporting members are not easily shaken.

  The second is the cooling rate of the bimetals 15 and 16. Alumina and quartz constituting the arc tube 1 have higher specific heat and lower thermal conductivity than the metal materials constituting the support shafts 11 and 12 and the bimetals 15 and 16. Therefore, the cooling rate when the arc tube 1 is switched from the lighting state to the extinguishing state is sufficiently faster for the bimetals 15 and 16 than for the arc tube 1. However, as a measure for ensuring safety, a structure for increasing the surface area such as cooling fins is provided on the support shafts 11 and 12 to promote heat radiation from the support shafts 11 and 12, thereby the bimetal 13 immediately after turning off. The cooling rate of 14 may be increased.

  Moreover, although the said embodiment is provided with the support shafts 11 and 12 only for bimetal mounting | wearing, when the space in a lamp | ramp is not obtained enough, the bimetals 15 and 16 are supported by the support members 3 and 8 of the arc_tube | light_emitting_tube 1, for example. Also good.

  Furthermore, in the above-described embodiment, bimetal is adopted as a thermal stress generating member that generates thermal stress according to temperature change. However, the shape of the arc tube, the size of the compressive stress that needs to be applied to the arc tube, Depending on the direction, the thermal stress generating member may be made of a single metal material having a required expansion coefficient. That is, the thermal stress generating member may be any member that generates a thermal stress according to a temperature change of the light emitting portion 1a, and that the thermal stress acts as a force in a direction to relieve the thermal stress generated in the light emitting portion 1a.

  Furthermore, although the ceramic material is used as the arc tube 1 material in the above-described embodiment, it goes without saying that the present invention can also be applied when other general arc tube 1 materials such as quartz glass are used. . However, in general, when ceramics having a large expansion coefficient are used for the arc tube 1, there is a relatively high possibility that breakage such as cracks will occur. Therefore, the present invention is suitably applied when the material of the arc tube 1 is ceramic. The

Schematic showing the temperature distribution of the arc tube during lighting; Schematic showing the stress distribution of the arc tube immediately after extinction; The figure which shows typically the high pressure discharge lamp which concerns on embodiment of this invention; FIG. 3 is a partially enlarged view showing the connecting member; Partial enlarged view for explaining the structure and function of the bimetal; Figure for conceptually explaining the support of the light tube; A partially enlarged perspective view showing another example of the connecting member; Sectional drawing in the VII-VII line of FIG. 7A; A partially enlarged perspective view showing still another example of the connecting member; It is sectional drawing in the VIII-VIII line of FIG. 8A.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emission tube 1a Light emission part 1b, 1c Side tube part 1c Thin tube part 2A, 2B Electrode 3 Support member 4 Deformable member 5,6 Wire frame 7 Base 8 Support shaft member 8a Ring-shaped part 13, 14 Connection member 13a, 14a Annular Part 15, 16 Bimetal 21 Outer tube 31 High thermal expansion plate 32 Low thermal expansion plate L Axis

Claims (11)

A light-emitting tube having a light-emitting portion, a pair of electrodes arranged to face each other in the light-emitting portion, and a pair of side tube portions extending in an axial direction connecting the electrodes from both ends of the light-emitting portion;
A support structure for supporting the arc tube so as to restrict displacement in a direction perpendicular to at least the axis;
Each base end side is supported by the support structure, while the distal end side is connected to the side tube portion of the arc tube, and a thermal stress is generated by a temperature change at the time of switching from the lighting state to the extinguishing state. A high-pressure discharge comprising: a pair of thermal stress generating members that act as a downward force in the vertical direction with respect to the side tube portion of the arc tube arranged in a posture in which an axis extends in the horizontal direction and acts as an outward force with respect to the arc tube lamp.   The high-pressure discharge lamp according to claim 1, further comprising a pair of connecting members that connect the side tube portion and the distal end side of the thermal stress generating member.   The connecting member includes an annular portion that surrounds the outer peripheral surface of the side tube portion, and a fixed portion that extends in a direction away from the annular portion with respect to the side tube portion, and the distal end side of the thermal stress generating member is fixed. The high-pressure discharge lamp according to claim 2 provided.   The high pressure discharge lamp according to claim 3, wherein the connecting member is fixed to the side tube portion by caulking the annular portion to the side tube portion.   The high pressure discharge lamp according to claim 4, wherein a groove into which the annular portion is fitted is formed on an outer peripheral surface of the side tube portion. The electrode extends in the axial direction and protrudes outside the arc tube through the side tube portion,
The support structure includes a wire frame that supports the electrode and is electrically connected to a lighting circuit;
The high pressure discharge lamp according to claim 1, wherein proximal ends of the pair of thermal stress generating members are fixed to a pair of support shafts extending from the wire frame toward the side tube portion.   The high-pressure discharge lamp according to claim 1, wherein the thermal stress generating member is made of a bimetal.   The high-pressure discharge lamp according to claim 1, wherein the arc tube is made of a ceramic material. The high-pressure discharge lamp according to claim 1, wherein a light-emitting substance is enclosed in the light-emitting portion, and the pressure of the light-emitting substance during lighting is 10 MPa or more.   The high pressure discharge lamp according to claim 1, further comprising an outer tube surrounding the arc tube. A light-emitting tube having a light-emitting portion and horizontally lit ;
A high-pressure discharge lamp comprising: a thermal stress generating member that generates a thermal stress due to a temperature change at the time of switching from a lighting state to a non-lighting state, and this thermal stress generates a compressive stress in the upper portion of the light emitting portion.

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