JP2012174585A - Metal halide lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal halide lamp which is manufactured easily and can be repeatedly used for a long period of time.SOLUTION: A metal halide lamp comprises: a luminous tube 11 made of quartz having a translucent light-emitting part 11a which is swollen at a central area containing mercury and metal halide in the inside, and lateral tube parts 11b which are provided on both sides of the light-emitting part, respectively; a cap 12 made of a metal material which is attached around end areas of the lateral tube parts; molybdenum foil 13 which is hermetically sealed in the lateral tube parts on a side closer to the light-emitting part than the cap; an electrode bar 14 which is connected to the light-emitting part side of the molybdenum foil; and an electrode terminal 16 which is connected to the cap side of the molybdenum foil via a power supply member 15 made of a metal material. An opaque film 17 extending at least from an end of the cap 12 to the connection between the power supply member 15 and the molybdenum foil 13 is formed on outer peripheral surfaces of the lateral tube parts 11b in such a manner that at least part of the lateral tube parts around the molybdenum foil 13 is exposed.

Description

  The present invention relates to a metal halide lamp that can be used particularly advantageously as a light source of a lighting device for a stage or a photography studio.

  A metal halide lamp (sometimes called a metal halide discharge lamp) has an emission color close to that of sunlight and has an advantage of higher brightness than a halogen lamp. It is widely used as a light source or as a light source for lighting devices in buildings such as hotels and restaurants.

  The metal halide lamp is a quartz arc tube having a translucent light-emitting portion that swells in a central region containing mercury and metal halide, and side tube portions respectively provided on both sides of the light-emitting portion. A base made of a metal material mounted around the end region of the pipe part, molybdenum foil hermetically sealed in each side pipe part on the side of the light emitting part from the base, connected to the light emitting part side of the molybdenum foil And electrode terminals connected to the base side of the molybdenum foil via a power supply member made of a metal material.

  By supplying electric energy to the electrode terminal of the metal halide lamp, arc discharge is generated between the electrode rods protruding inside the light emitting portion of the arc tube, and the light emission of this discharge is used for illumination.

  The light emitting portion of the arc tube is heated to high temperatures because the arc discharge radiant heat is applied. And the radiant heat of arc discharge is provided to the side tube part of the arc tube, and heat is transferred from the high temperature light emitting part. For this reason, the side tube portion, the molybdenum foil hermetically sealed inside the side tube portion, and the metal base made around the side tube portion are also heated.

  For this reason, if a metal halide lamp is used repeatedly over a long period of time, and the lamp is turned on and off repeatedly, the coefficient of thermal expansion of the quartz side tube part is the thermal expansion of the parts made of metal material (molybdenum foil or base). Since it is extremely small compared to the rate, cracks may occur due to thermal stress repeatedly generated in the side tube portion.

  Patent Document 1 discloses a metal halide lamp having a configuration in which a base portion of an electrode rod (a rod-shaped electrode material) and a metal foil are hermetically sealed in each side tube portion of an arc tube (bulb). Around the electrode rod of this metal halide lamp, a coil made of a high melting point material and a getter material and having a predetermined wire diameter, pitch and inner diameter corresponding to the diameter of the electrode rod is mounted. In the same document, even when a dimensional difference due to a difference in thermal expansion coefficient occurs between the arc tube and the electrode rod due to heat generated when the lamp is turned on, the dimensional difference is absorbed by the coil. There is a description that generation of cracks at a portion in contact with the electrode rod is prevented.

Japanese Patent Laid-Open No. 10-154485 (FIG. 1)

  An object of the present invention is to provide a metal halide lamp that is easy to manufacture and can be used repeatedly for a long period of time.

  The inventor forms an opaque film on the outer peripheral surface of the side tube portion of the arc tube of the metal halide lamp (on the side of the light emitting unit with respect to the base), so that the radiant heat of the arc discharge is blocked by the opaque film and the side tube portion. Since the temperature rise at the portion in contact with the mouthpiece of the side tube portion is suppressed, and the above opaque film is formed so that at least a part of the side tube portion around the molybdenum foil is exposed, molybdenum Since it is difficult to prevent heat dissipation from the foil to the surroundings of the side tube part, the temperature rise of the part in contact with the molybdenum foil of the side tube part is also suppressed, so the occurrence of thermal stress in the side tube part is sufficiently reduced. The inventors have found that the occurrence of cracks in the side tube portion is suppressed, and have reached the present invention.

  The present invention relates to a light emitting tube made of quartz having a translucent light emitting part bulging in a central region containing mercury and metal halide inside, and side tube parts respectively provided on both sides of the light emitting part, A base made of a metal material attached around the end region of each side tube part, a molybdenum foil hermetically sealed in each side tube part on the side of the light emitting part from the base, on the light emitting part side of the molybdenum foil A metal halide lamp including a connected electrode rod and an electrode terminal connected to the base of the molybdenum foil via a power supply member made of a metal material, on the outer peripheral surface of each side tube portion, An opaque film extending from the end portion of the base to at least a connection portion between the power supply member and the molybdenum foil is formed so that at least a part of the side tube portion around the molybdenum foil is exposed. For metal halide lamps .

Preferred embodiments of the metal halide lamp of the present invention are as follows.
(1) A portion having a length of 1/3 or more of the side tube portion around the molybdenum foil is exposed.
(2) The opaque film is a white film.

  In the present specification, “translucency” means that the transmittance of light having a wavelength in the range of 400 to 4000 nm is 70% or more. “Opaque” means that the transmittance of light having a wavelength in the range of 400 to 4000 nm is 40% or less.

  In the metal halide lamp according to the present invention, the opaque film formed in the predetermined area on the outer peripheral surface of each side tube portion suppresses the temperature rise at the portion of the side tube portion that comes into contact with the metal material part (molybdenum foil or base). Therefore, the generation of thermal stress in the side tube portion is sufficiently reduced, thereby suppressing the generation of cracks in the side tube portion. Therefore, the metal halide lamp of the present invention can be used repeatedly for a long period of time, and can be easily manufactured by forming an opaque film in a predetermined region on the outer peripheral surface of the side tube portion.

It is a partially notched front view which shows the structural example of the metal halide lamp of this invention. It is an expanded sectional view of the metal halide lamp 10 of FIG.

  The metal halide lamp of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a partially cutaway front view showing a configuration example of a metal halide lamp of the present invention, and FIG. 2 is an enlarged cross-sectional view of the metal halide lamp 10 of FIG. However, the metal halide lamp 10 of FIG. 2 is shown as a cross section only for parts other than the electrode rod 14, the molybdenum foil 13, the power supply member 15, and the electrode terminal 16.

  The metal halide lamp 10 is made of quartz having a translucent light emitting portion 11a bulging in a central region containing mercury and metal halide inside, and side tube portions 11b respectively provided on both sides of the light emitting portion 11a. The molybdenum tube is hermetically sealed in each side tube portion on the side of the light emitting portion 11a from the base 12 and the base 12 made of a metal material attached around the end region of each side tube portion 11b. 13, an electrode rod 14 connected to the light emitting portion 11a side of the molybdenum foil 13, and an electrode terminal 16 connected to the base 12 side of the molybdenum foil 13 via a power feeding member 15 made of a metal material. Has been.

  The metal halide lamp 10 has at least a part of the side tube portion around the molybdenum foil 13 on the outer peripheral surface of each side tube portion 11b (in the case of the metal halide lamp 10, the side tube portion around the molybdenum foil 13). (A portion having a length of about 1/2 of the length) is exposed so that at least the connection portion 21 between the power supply member 15 and the molybdenum foil 13 from the end of the base 12 (in the case of the metal halide lamp 10, the molybdenum foil). 13 is characterized in that an opaque film 17 is formed to extend to a substantially central position in the length direction of 13.

  The arc tube 11 is made of quartz, and includes a translucent light emitting portion 11a that sticks out in a central region, and side tube portions 11b provided on both sides thereof.

  Mercury and metal halide are accommodated in the light emitting part 11a. Examples of metal halides include compounds of metals such as Na, Tl, Th, In, Sn, Si, Sc, Dy, Ho, and Tm and halogens such as iodine or bromine. The light emitting unit 11a can contain a rare gas such as argon.

  The light emitting part 11a needs to be “translucent”. “Translucent” means that the transmittance of light having a wavelength in the range of 400 to 4000 nm is 70% or more. The light transmittance of the light emitting part 11a is preferably 75% or more, and more preferably 80% or more.

  A base 12 is mounted around the end region of the side tube portion 11b. The base 12 is made of, for example, a metal material typified by brass. In order to suppress oxidation of the surface of the base 12, the surface of the base 12 can be plated (eg, nickel plating).

  Molybdenum foil 13 is hermetically sealed inside each side tube portion 11b on the light emitting portion 11a side of the base 12.

  As the molybdenum foil 13, a molybdenum film is used. The thickness of the molybdenum foil 13 is generally set in the range of 5 to 200 μm, preferably 10 to 150 μm.

  One or two or more molybdenum foils can be further stacked on the molybdenum foil 13. When the molybdenum foil 13 is composed of two or more molybdenum foils in total, a thin plate made of a material (eg, quartz) that exhibits electrical insulation is disposed between the molybdenum foils adjacent to each other. You can also.

  The molybdenum foil 13 has a function of plastically deforming when the side tube portion 11b is thermally expanded, thereby reducing the thermal stress generated at the portion in contact with the molybdenum foil 13 of the side tube portion 11b.

  However, since the molybdenum foil 13 is set to a thin thickness so as to enable the plastic deformation, the electric resistance is large, and a large Joule heat is generated by a current flowing through the molybdenum foil 13. When the molybdenum foil becomes high temperature and deteriorates (eg, oxidative expansion), cracks occur in the side tube portion that contacts the molybdenum foil, resulting in insufficient hermetic sealing, It may become impossible to supply energy.

  On the other hand, the molybdenum film 18a wound around the base of the electrode rod 14 described later and the molybdenum film 18b wound around the end region of the bar 15a of the power supply member 15 are similar to the molybdenum foil 13 described above. Each film is made of molybdenum. However, each of the molybdenum films 18a and 18b exhibits a small electric resistance value when wound around and electrically connected to a conductive part (electrode bar 14 or bar 15a). Joule heat is not generated, and therefore the problem of the deterioration is difficult to occur. For this reason, in the present specification, the molybdenum films (molybdenum films wound around conductive parts) 18a and 18b and the molybdenum foils (molybdenum films not wound around conductive parts). ) And 13 are distinguished from each other.

  An electrode bar 14 is connected to the light emitting part 11a side of the molybdenum foil 13. The tip of the electrode rod 14 protrudes into the light emitting part 11a. The electrode rod 14 is made of tungsten, for example. As described above, the molybdenum film 18 a is wound around the base of the electrode rod 14.

  An electrode terminal 16 is connected to the base 12 side of the molybdenum foil 13 via a power supply member 15 made of a metal material.

  The power supply member 15 includes, for example, a tungsten rod 15a, a copper stranded wire 15b, and a molybdenum rod 15c. As described above, the molybdenum film 18b is wound around the end region of the tungsten rod 15a. The stranded wire 15b is deformed when the power supply member 15 is thermally expanded, and absorbs the extension of the power supply member 15 due to the thermal expansion, thereby reducing the thermal stress generated in the side tube portion 11b.

  One end of the electrode terminal 16 is connected to the bar 15 c of the power supply member 15. The other end of the electrode terminal 16 protrudes outside the arc tube 11. As the electrode terminal 16, for example, a bar made of molybdenum is used.

  Since the configuration of the metal halide lamp 10 is the same as that of a known metal halide lamp except for an opaque film described below, no further description will be given.

  In the metal halide lamp 10 shown in FIGS. 1 and 2, the outer peripheral surface of each side tube portion 11 b is about half the length of the side tube portion around the molybdenum foil 13 (that is, about the entire length of the molybdenum foil 13). An opaque film 17 extending from the end of the base 12 to the substantially central position in the length direction of the molybdenum foil 13 is formed so that a portion (1/2 length) is exposed.

  The opaque film 17 blocks the radiant heat of the arc discharge generated in the light emitting portion 11a, and suppresses the temperature rise at the portion closer to the light emitting portion 11a than the base 12 of the side tube portion 11b. For this reason, the amount of heat transmitted to the portion inside the base 12 of the side tube portion 11b is reduced, and the generation of thermal stress in the side tube portion is sufficiently reduced. Therefore, the occurrence of cracks in the portion that comes into contact with the base 12 (part made of metal material) of the side tube portion is suppressed.

  In the present invention, in order to block the radiant heat of the arc discharge and suppress the temperature rise of the side tube portion 11b, the opaque film 17 is connected to at least the feeding member 15 from the end of the base 12 on the outer peripheral surface of the side tube portion 11b. It forms so that it may extend to the position corresponding to the position of the connection part 21 with the molybdenum foil 13. An opaque film can also be formed on the outer peripheral surface of the die.

  The opaque film 17 may extend to the light emitting part 11a side from the position corresponding to the position of the connecting part 21 of the side tube part 11b. However, as described above, the molybdenum foil 13 generates large Joule heat. The opaque film 17 may hinder heat dissipation to the periphery of the molybdenum foil.

  Accordingly, in the present invention, the opaque film 17 is covered with the opaque film so that at least a part of the side tube portion around the molybdenum foil 13 is exposed (the entire side tube portion around the molybdenum foil 13 is exposed). It is formed on the outer peripheral surface of the side tube portion 11b.

  If the heat release to the periphery of the molybdenum foil 13 is good, the temperature rise of the molybdenum foil 13 and the surrounding side tube portion is suppressed. Therefore, the occurrence of cracks in the portion of the side tube portion 11b that comes into contact with the molybdenum foil 13 (part made of a metal material) is suppressed.

  The side tube portion around the molybdenum foil 13 is preferably exposed at a portion having a length of 1/3 or more, particularly 1/2 or more of the entire length (that is, equal to the entire length of the molybdenum foil 13).

  As described above, in the metal halide lamp 10 of the present invention, the occurrence of cracks in the portion of the side tube portion 11b that comes into contact with the metal material parts (molybdenum foil 13 and base 12) is suppressed, and mercury and metal halide from the cracks Since the occurrence of steam leakage is suppressed, it can be used repeatedly for a long period of time, and can be easily manufactured by forming an opaque film in a predetermined region on the outer peripheral surface of the side tube portion 11b.

  The opaque film 17 is not particularly limited in the color of the film as long as it can block the radiant heat generated by the arc discharge generated in the light emitting portion 11a. As the opaque film 17, for example, a known black film or white film can be used. “Opaque” means that the transmittance of light having a wavelength in the range of 400 to 4000 nm is 40% or less. The light transmittance of the opaque film is preferably 35% or less, and more preferably 30% or less.

  The black film preferably contains black pigment powder and a binder. As the black pigment powder, for example, a powder of triiron tetroxide can be used. It is preferable to use a known inorganic polymer (eg, metal oxide polymer) as the binder.

The white film preferably contains white pigment powder and a binder. As the white pigment powder, for example, titanium oxide (TiO ₂ ) or zirconium oxide (ZrO ₂ ) powder can be used. It is preferable to use a known inorganic polymer (eg, metal oxide polymer) as the binder.

  The opaque film 17 of the metal halide lamp 10 shown in FIGS. 1 and 2 can efficiently reflect the radiant heat generated by the arc discharge generated in the light emitting portion 11a and effectively suppress the temperature rise of the side tube portion 11b. Therefore, a white film is used.

  The opaque film 17 can be formed by applying or spraying the coating liquid containing the pigment powder and the binder to the outer peripheral surface of the side tube portion 11b of the arc tube 11 and then drying.

  The thickness of the opaque film is preferably in the range of 5 to 500 μm.

  In the metal halide lamp of the present invention, it is preferable that each side tube portion 11b is further hermetically sealed on the base 12 side (end portion side of the side tube portion 11b) with respect to the molybdenum foil 13.

  Two quartz cylinders 19a and 19b are fitted and fixed (eg, welded) to the inner side surface of the end portion of the side tube portion 11b of the metal halide lamp 10 shown in FIG. The end of the cylindrical body 19a is fixed (eg, welded) to the molybdenum cylindrical member 20. The side tube portion 11 b is hermetically sealed by brazing the cylindrical member 20 around the bar 15 c of the power feeding member 15. As a result, the side tube portion 11b in which the temperature rise is suppressed by the opaque film 17 can be surely hermetically sealed at a relatively low temperature site away from the high temperature arc discharge.

  The distance (FIG. 2: L) between the position where the hermetic sealing is performed with the addition of the side tube portion 11b and the position corresponding to the tip of the electrode rod 14 is the distance between the pair of electrode rods (FIG. 1: W). It is preferable that they are equal to or more than that (that is, the relationship of L ≧ W is satisfied).

  As the distance L is larger, the side tube portion 11b can be reliably sealed at a lower temperature portion, but the side tube portion becomes longer. Therefore, the distance L is preferably in the range of 1 to 15 times the distance W, and more preferably in the range of 2 to 10 times.

  First, a metal halide lamp having the same configuration as the metal halide lamp 10 shown in FIGS. 1 and 2 was prepared except that a white film (opaque film) was not formed.

  A through hole is formed in the base of the metal halide lamp, a thermocouple is inserted through the through hole, and a position where the cylindrical member 20 and the bar 15c shown in FIG. 2 come into contact with each other on the outer peripheral surface of the side tube portion. And fixed at the corresponding position. Thereby, the temperature of the side tube portion can be stably measured without being affected by the air flow around the lamp.

  Next, 60 minutes after starting the lighting of the metal halide lamp on which the white film was not formed, the temperature of the side tube portion was measured using a thermocouple, and then the lamp was turned off and allowed to cool.

  Subsequently, a white paint coating film containing white pigment powder (zirconium oxide powder) and a binder (organometallic polymer) is formed on the outer peripheral surface of each side tube portion of the metal halide lamp. A white film (opaque film) was formed by drying at room temperature. The white film is formed in a region from the end of the mouthpiece on the outer peripheral surface of the side tube portion to a position corresponding to the substantially central position in the length direction of the molybdenum foil, and thereby, about the side tube portion around the molybdenum foil. A portion having a length of 1/2 (that is, a length of about 1/2 of the entire length of the molybdenum foil) was exposed.

  The configuration of the metal halide lamp thus formed with the white film is the same as that of the metal halide lamp 10 shown in FIGS. 1 and 2 except that the through hole is formed in the base.

  Then, 60 minutes after starting the lighting of the metal halide lamp on which the white film was formed, the temperature of the side tube portion was measured using a thermocouple, and then the lamp was turned off and allowed to cool.

  The difference between the temperature of the side tube portion measured for the metal halide lamp not forming the white film and the temperature of the side tube portion measured for the metal halide lamp forming the white film is about 100 ° C. Has been confirmed to be extremely effective in suppressing the temperature rise in the side tube.

  Further, after repeating the operation of turning on the metal halide lamp on which the white film was formed for 3 hours and then turning it off for 1 hour 85 times, the side tube portion of the arc tube was visually observed. As a result, it was confirmed that no cracks were generated in the portion of the arc tube that contacts the base of the side tube portion and the portion of the side tube portion that contacts the molybdenum foil.

DESCRIPTION OF SYMBOLS 10 Metal halide lamp 11 Light emission tube 11a Light emission part 11b Side tube part 12 Base 13 Molybdenum foil 14 Electrode rod 15 Feed member 15a Bar material 15b Strand 15c Bar material 16 Electrode terminal 17 Opaque film | membrane 18a, 18b Molybdenum film 19a, 19b Tubular body 20 Cylindrical member 21 Connection between power feeding member 15 and molybdenum foil 13

Claims (3)

A quartz arc tube having a translucent light emitting part bulging in a central region containing mercury and metal halide inside, and side tube parts respectively provided on both sides of the light emitting part, and each side tube A base made of a metal material mounted around the end region of the part, a molybdenum foil hermetically sealed in each side tube part on the side of the light emitting part from the base, and connected to the light emitting part side of the molybdenum foil A metal halide lamp including an electrode terminal and an electrode terminal connected to a base side of the molybdenum foil via a power feeding member made of a metal material,
At least a part of the side tube portion around the molybdenum foil is exposed on the outer peripheral surface of each side tube portion, and at least from the end of the base to the connection portion between the power feeding member and the molybdenum foil. A metal halide lamp characterized in that an opaque film extending to   The metal halide lamp according to claim 1, wherein a portion having a length of 1/3 or more of the side tube portion around the molybdenum foil is exposed.   The metal halide lamp according to claim 1 or 2, wherein the opaque film is a white film.

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