JP2004335461A - High pressure discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To alleviate thermal stress generated in an arc tube under a condition of a high operation pressure of about several tens of atmospheric pressure and horizontal lighting. <P>SOLUTION: This high pressure discharge lamp has a supporting structure for supporting an arc tube 1 so as to restrain displacement toward the direction crossing the axial line at right angle. By a temperature change at the time of switching a lighting state to a light-out state, thermal stress is generated by a pair of thermal stress generating members 15, 16. This thermal stress acts as a force oriented downward in a perpendicular direction relative to side tubes 1b, 1c of the arc tube 1 of which the axial line L is arranged in a posture extending in a horizontal direction and as a force oriented outward relative to the arc tube 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The invention relates to a high-pressure discharge lamp. In particular, the present invention relates to a high-pressure discharge lamp suitably used for lighting high ceilings, stores, streets, and the like.

  Conventionally, high-pressure discharge lamps used for high ceilings, shops, streets, etc. are made of quartz glass or a ceramic tube, an outer tube, and a wire frame made of a conductive material that supports the arc tube in the outer tube. (For example, see Patent Document 1). Since the luminous tube of this type of high-pressure discharge lamp becomes extremely hot during operation, it is important to alleviate the thermal stress generated in the luminous tube to prevent damage to the luminous tube. 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 the arc tube from being damaged, there is a prior art in which a compressive stress is previously made latent in the arc tube material in order to alleviate the tensile stress generated on the arc tube surface during lighting (for example, Patent Reference 2 and Patent Document 3). In these techniques, a tensile stress generated during operation is canceled by a compressive stress that is latent in advance, and as a result, damage to the lamp is prevented.

  Recently, lighting conditions required for high-pressure discharge lamps have changed. Broadly, there are two conditions. One is that while these high-pressure discharge lamps, particularly metal halide lamps, are required to have higher efficiency, the operating pressure in the arc tube is increased from several atmospheric pressures (about 5 to 9 atmospheric pressures) to 10 or more in order to improve luminous efficiency. It is necessary to increase the pressure to the atmospheric pressure (about 10 to 15 atm). There are several ways to increase the operating pressure. For example, it is common 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, use in vertical lighting has been relatively large, but use in horizontal lighting has also been increasing in order to realize a design viewpoint of lighting fixtures, particularly, space saving.

  However, all of the above-mentioned conventional techniques reduce the thermal stress generated in the arc tube during lighting under the condition of operating pressure of several atmospheres and vertical lighting. No measures are provided for the thermal stress generated in the arc tube under the condition of high operating pressure of about 10 atm and horizontal lighting.

U.S. Patent No. 6,326,721 JP-A-2-301957 JP-A-60-225159

  SUMMARY OF THE INVENTION It is an object of the present invention to alleviate thermal stress generated in an arc tube of a high-pressure discharge lamp. In particular, it is an object of the present invention to reduce thermal stress generated in an arc tube under conditions of high operating pressure of about several tens of atmospheres and horizontal lighting, thereby preventing damage to a high pressure discharge lamp.

  According to a first aspect of the present invention, there is provided a light emitting unit, a pair of electrodes arranged 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 regulate at least displacement in a direction orthogonal to the axis, and a base end side of the arc tube is supported by the support structure, while a tip end of the arc tube is A thermal stress is generated by a temperature change at the time of switching from the on state to the off state, and the thermal stress is connected to the side tube part, and the thermal stress is generated by the side tube part of the arc tube arranged in a posture in which the axis extends in the horizontal direction. A high-pressure discharge lamp comprising a pair of thermal stress generating members that act vertically as a force on the arc tube and that acts outward on the arc tube.

  Under a high operating pressure of about 10 atm and a condition of horizontal lighting, a maximum thermal stress is generated in a vertically upper part of the light emitting unit due to a temperature change at the time of switching from a lighting state to a lighting state. The direction of this thermal stress is tensile. The thermal stress generated by the thermal stress generating member acts as a downward force on the side tube portion of the arc tube and an outward force on the arc tube, so that the vertical stress of the arc tube on which the maximum tensile stress acts is applied. A compressive stress acts on the upper part in 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 is alleviated, cracking and breakage of the arc tube are prevented, and the life of the high pressure discharge lamp is extended. Can be.

  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 has an annular portion surrounding the outer peripheral surface of the side tube portion, extends in a direction away from the annular portion with respect to the side tube portion, and a distal end side of the thermal stress generating member is fixed. Fixed part. The connecting member may be fixed to the side tube by caulking the annular portion to the side tube. 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.

  In a case where the electrode extends in the axial direction and projects outside the arc tube through the side tube portion, and 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 bimetal or a single metal material having a desired coefficient of linear expansion.

  The present invention is suitably 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 preferably applied when the pressure at the time of lighting of the light emitting substance sealed in the light emitting portion, that is, the operating pressure is 10 MPa or more.

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

  According to a second aspect of the present invention, a thermal stress is generated by an arc tube having a light emitting portion and a temperature change at the time of switching from a lighting state to a light-off state, and the thermal stress generates a compressive stress at an upper portion of the light emitting portion. A high-pressure discharge lamp comprising:

  In the high-pressure discharge lamp of the present invention, the provision of the thermal stress generating member allows the high-pressure discharge lamp to operate on the arc tube when switching from the on state to the off state under the condition of a high operating pressure, especially about 10 atm, and horizontal lighting. This can reduce thermal stress, prevent cracking or 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 conditions of high operating pressure and horizontal lighting, cracks and the like are likely to occur in the arc tube immediately after switching from the lighting state to the off state, and further described in detail below. The thermal stress causing this failure was analyzed as follows. The present invention is based on new findings obtained by such analysis. The pressure and temperature rise at the time of starting the lamp, that is, at the time of switching from the extinguished state to the lit state, is sufficiently slow because it follows evaporation of the encapsulated metal. However, under the conditions of high operating pressure and horizontal lighting, there is a rapid temperature drop immediately after turning off or when switching from the lighting state to the lighting 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 whose main material is alumina (Al2O3). A sealed metal containing mercury and a metal halide and a rare gas as a buffer gas are sealed inside the light emitting portion 1a. 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 axis L connecting the pair of electrodes 2A and 2B disposed inside extends substantially in the horizontal direction. The arc tube 1 can thermally expand in the direction of the axis L extending in the horizontal direction, but is supported such that displacement in the direction perpendicular to the axis L (including the vertical direction) is restricted.

  In FIG. 1, the higher the density of dots assigned to each area partitioned by the isotherm T, the higher the area is. As a part of the supplied electric power is consumed as heat energy, the inside of the light emitting unit 1a is heated to a high temperature of about 1,100 ° C. Further, since the lighting posture is horizontal, a temperature difference of about 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., while 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 portion 1a is generated as a result of a convection phenomenon in a high-temperature and high-pressure state due to a large amount of metal being filled in the light emitting portion 1a. Therefore, the higher the pressure at the time of lighting in the light emitting section 1a, the greater the temperature difference.

  FIG. 2 shows a calculation result obtained by simulating, using the finite element method, various stresses generated in the light emitting section 1a which is turned on in such a high temperature and high pressure state when the light is turned off. Specifically, FIG. 2 shows that the temperature distribution shown in FIG. 1 changes according to the condition simulating the actual measured value of the temperature decrease immediately after the light is actually turned off, and the respective parts of the arc tube 1 return to room temperature. The distribution of the generated thermal stress is shown. In FIG. 2, it is shown that the higher the density of the dots assigned to each area partitioned by the equal stress line P, the higher the thermal stress. As is clear from FIG. 2, the part where the strongest tensile stress occurs in each part of the arc tube 1 is the upper part of the inner wall surface. At the point p1 at the uppermost portion of the inner wall surface, the tensile stress is the maximum (111 MPa), and the value of the tensile stress decreases as moving to the lower portion. For example, the tensile stress at point p2 at the center of the inner wall surface is 30 MPa. Also, a compressive stress is generated on the lower side of the inner wall. For example, a compressive stress of −40 MPa is generated at a point p3 at the lowermost portion of the inner wall surface. As shown by arrows M1 and M2 in FIG. 3, tensile stress is generated in the direction of the side pipes 1b and 1c (the direction of the axis L). This corresponds to a part where the arc tube is broken in an actual lamp strength 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 occurs at the upper part of the arc tube when switching from the lighting state to the extinguishing state, and this thermal stress is Was found to cause damage.

  Next, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 3 shows a metal halide lamp which is a high-pressure discharge lamp according to an embodiment of the present invention. The light emitting tube 1 has 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 whose tips are exposed inside the light emitting portion 1a. , 2B. The side tubes 1b and 1c extend along a virtual straight line or 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 raw material is alumina (Al2O3). The base ends of the electrodes 2A, 2B pass through the thin tube portion 1d of the side tube portions 1b, 1c and are led out of the arc tube 1. An outer tube 21 is provided so as to surround the arc tube 1.

  Describing the electrical connection structure, the base of the right electrode 2A is connected to the support member 3 and the base of the left electrode 2B is connected to the deformable member 4 in the figure. Further, the support member 3 is connected to a wire frame 5, and the deformable member 4 is connected to a wire frame 6. The wire frames 5 and 6 are connected via a base 7 to an external lighting circuit (not shown).

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

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

  In general, when the lamp is stably turned on, the arc tube 1 expands due to thermal expansion compared to when the lamp is cold. The thermal expansion of the arc tube 1 is greatest 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 extending in the vertical direction are provided corresponding to the base end side of the left electrode 2B in the figure. The deformable member 4 is made of a material having conductivity and deforming relatively freely, such as a stranded wire made of a conductive material. The upper end of the deformable member 4 is welded to the wire frame 6 at the connection point 21, and the lower end is welded to the base end side of the electrode 2 </ b> B at the connection point 22. The support member 8 has an upper end welded to the wire frame 6 at a connection point 17 and has a ring-shaped portion 8a at a lower end. The base end of the electrode 2B is inserted into 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 figure. The lower end of the support member 3 is welded to the wire frame 5 at the connection point 20. The base end of the electrode 2A is welded to the support member 3 at a 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, the 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 the stress generated by the expansion is reduced, but the displacement in the direction orthogonal to the horizontal direction is restricted.

  Assuming that the arc tube 1 is 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 a regulated rotating end.

  Next, a structure for alleviating the thermal stress generated in the arc tube 1 at the time of turning off the light will be described with reference to FIGS.

  Support shafts 11 and 12 extending vertically upward are connected to the wire frame 5. The support shaft 11 is arranged below the right side tube portion 1b in the drawing, and the lower end is welded to the wire frame 5 at the connection point 20 and the upper end faces the side tube portion 1b with a space therebetween. I have. On the other hand, the support shaft 12 is disposed below the left side tube 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 tube portion 1c with a space therebetween. are 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 molding a band-shaped metal plate, and has an annular portion 14 a wound around the outer peripheral surface of the side tube portion 1 c and mounted, and a fixed portion 14 b extending downward from the annular portion 14 a. It has. The annular portion 14a is obliquely wound around the side tube portion 1c, and the contact position 14c of the annular portion 14a with the upper portion of the side tube portion 1c is larger than the contact position 14d of the annular portion 14a with the lower portion of the side tube portion 1c. It is located inside, that is, on the light emitting unit 1a side. The annular portion 14a is mounted so as not to be easily shifted with respect to the side tube portion 1c, and the contact positions 14d and 14c do not move. The material and shape of the connecting member 13 and the mounting posture 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 bimetal 16 has a base end welded to the support shaft 12 and a distal end welded to the fixing portion 14 b of the connecting member 14. The bimetal 16 is obtained by laminating a plate made of an alloy material having a high coefficient of thermal expansion (high thermal expansion plate 31) and a plate made of an alloy material having a low coefficient of thermal expansion (low thermal expansion plate 32), and has a thermal deformation effect. . That is, when the temperature rises, the high thermal expansion plate 31 deforms more than the low thermal expansion plate 32, so that the high thermal expansion plate 31 bends 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 vertically above the high thermal expansion member 31, that is, on the arc tube 1 side. The material, shape, and dimensions of the high thermal expansion plate member 31 and the low thermal expansion member 32 are such that the radiant heat from the arc tube 1 during stable lighting curves toward the low thermal expansion member 32 as shown by a solid line A in FIG. And fixed to the support shaft 12 and the connecting member 14. The structure and mounting posture of the bimetal 15 that connects the support shaft 11 and the connecting member 13 are the same as those of the bimetal 16.

  Since the lighting operation 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 FIG. 1 and FIG. At the time of switching, a large thermal stress occurs in the upper part of the arc tube 1a in the tensile direction. This thermal stress acts on the arc tube 1 as a deforming force for deforming the light emitting portion 1a into a bow shape protruding vertically upward, 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 rapidly deforms to a linear shape indicated by a dotted line B due to a decrease in temperature. However, in practice, both ends of the bimetal 16 are welded to the support shaft 12 and the connecting member 14 so that the displacement is restrained. Therefore, the bimetal 16 hardly changes from the shape indicated by the solid line A, and a thermal stress is generated. The thermal stress generated in the bimetal 16 acts on the side tube portion 1c of the arc tube 1 via the connecting member 14 as a force indicated by an arrow Y. Referring also to FIG. 3, thermal stress also occurs in the bimetal 15 due to the above-described temperature drop 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 via 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, more specifically, vertically downward with respect to the side tube portions 1b and 1c, and the side tube portions. 1b, 1c is outward (direction away from the light emitting unit 1a). Therefore, as schematically shown by a dashed line in FIG. 6, these forces X and Y act on the arc tube 1 as a deformation force for deforming the light emitting portion 1a into a bow shape protruding vertically downward, A compressive stress is generated on 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 the opposite direction to the deformation (dotted line in FIG. 6) of the arc tube 1 due to the thermal stress generated in the arc tube 1 when switching from the on state to the off state. Let it. Therefore, due to the 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 turned off, especially Thermal stress at the uppermost portion of the inner wall surface of the light emitting portion 1a (see position t1 in FIG. 2) is effectively reduced.

  7A and 7B show another example of the connecting member. The annular portion 13a of the connecting member 13 is caulked to the side tube portion 1b, and the entire inner surface of the annular portion 13a is in close contact with the outer peripheral surface of the connecting member 13. The lower end of the fixing portion 13b 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 at the time of turning off the light is reliably transmitted through the connecting member 13. The light 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 direction of the axis L with respect to the side tube portion 1b can be more reliably prevented from shifting, so that the thermal stress of the bimetal 15 can be 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 in the vertically upper part of the light emitting unit 1a by the above-described structure works more effectively as the pressure inside the light emitting unit 1a becomes higher. In particular, it is effective when the internal pressure at the time of lighting of the light emitting section 1a is 10 MPa (about 10 atm) or more. As a filling material in which the light emitting portion 1a becomes 10 MPa or more during lighting, a mixture of PrI3, CsI, and NaI may be sealed in the light emitting portion 1a.

  In order to sufficiently exhibit the effect of relaxing the tensile stress of the light emitting portion 1a by the above configuration, there are some points to be considered 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 use 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 surrounding wire frames 5, 6 and the supporting members 3, 8, In addition, the support shafts 11 and 12 need to be made of a material, a shape, and a dimension that do not easily deform. 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, 17 to 20 also need to be firmly welded so that the supporting member group is not easily displaced.

  The second is a 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 metal materials constituting the support shafts 11 and 12 and the bimetals 15 and 16. Therefore, the bimetals 15 and 16 have a sufficiently higher cooling rate when the arc tube 1 is switched from the on state to the off state. However, as a measure for more thoroughness, 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, and thereby the bimetals 13 and 12 immediately after the lights are turned off. The cooling rate of 14 may be increased.

  In the above-described embodiment, the supporting shafts 11 and 12 are provided exclusively for mounting the bimetal. However, when sufficient space in the lamp cannot be obtained, the bimetals 15 and 16 are supported by the supporting members 3 and 8 of the arc tube 1. Is also good.

  Furthermore, in the above-described embodiment, a bimetal is employed as a thermal stress generating member that generates thermal stress in accordance with a change in temperature, but the shape of the arc tube, the magnitude of the compressive stress that needs to be applied to the arc tube, and the like. 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 in accordance with the temperature change of the light emitting portion 1a and acts as a force in a direction in which the thermal stress reduces the thermal stress generated in the light emitting portion 1a.

  Furthermore, in the above-described embodiment, a ceramic material is used as the material of the arc tube 1. However, it is needless to say that the present invention can be applied to a case where another general material of the arc tube 1 such as quartz glass is used. . However, in general, when a ceramic having a large expansion coefficient is 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. You.

Schematic diagram showing the temperature distribution of the arc tube during lighting; Schematic diagram showing the stress distribution of the arc tube immediately after turning off the light; The figure which shows typically the high pressure discharge lamp which concerns on embodiment of this invention; FIG. 3 is a partially enlarged view of FIG. 3 showing a connecting member; A partially enlarged view for explaining the structure and function of the bimetal; Diagram for conceptually explaining light tube support; A partially enlarged perspective view showing another example of the connecting member; FIG. 7A is a sectional view taken along line VII-VII 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 reference numerals

REFERENCE SIGNS LIST 1 arc tube 1a light emitting portion 1b, 1c side tube portion 1c thin tube portion 2A, 2B electrode 3 support member 4 deformable member 5, 6 wire frame 7 base 8 support shaft member 8a ring-shaped portion 13, 14 connecting 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 within the light-emitting portion, and a pair of side tube portions extending in the axial direction connecting the electrodes from both ends of the light-emitting portion,
A support structure that supports the arc tube so as to regulate at least displacement in a direction perpendicular to the axis,
The base end side is supported by the support structure, while the tip end side is connected to the side tube portion of the arc tube, and generates a thermal stress due to a temperature change at the time of switching from an on state to an off state. A pair of thermal stress-generating members that act vertically as downward force on the side tube portion of the arc tube and that act as an outward force on the arc tube, the axis of the arc tube being arranged in a posture extending in the horizontal direction. lamp.   The high-pressure discharge lamp according to claim 1, further comprising a pair of connecting members that connect the side tube portion and a distal end side of the thermal stress generating member.   The connecting member includes an annular portion surrounding the outer peripheral surface of the side tube portion, and a fixed portion extending in a direction away from the annular portion with respect to the side tube portion, and a distal end side of the thermal stress generating member being fixed. The high-pressure discharge lamp according to claim 2, further comprising:   The high-pressure discharge lamp according to claim 3, wherein the connecting member is fixed to the side tube by caulking the annular portion to the side tube.   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 projects outside the arc tube through the side tube portion,
The support structure includes a wire frame that supports the electrodes and electrically connects to a lighting circuit,
The high-pressure discharge lamp according to claim 1, wherein base 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 sealed in the light-emitting portion, and a pressure of the light-emitting substance at the time of lighting is 10 MPa or more.   The high-pressure discharge lamp according to claim 1, further comprising an outer tube surrounding the arc tube. An arc tube having a light emitting section;
A high-pressure discharge lamp comprising: a thermal stress generating member that generates thermal stress due to a temperature change at the time of switching from the on state to the off state, and the thermal stress generates a compressive stress on the upper part of the light emitting unit.

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