JP4498940B2 - Metal halide lamp - Google Patents

Description

  The present invention relates to a metal halide lamp that essentially does not enclose mercury as a discharge medium used in automobile headlamps and the like.

  As a prior art, in the foil seal lamp comprising a light emitting mechanism portion at one end of a metal foil made of molybdenum embedded in a sealing portion of a lamp vessel made of a translucent member and a lead rod extending outwardly at the other end, the lead A glass mainly composed of boron oxide and bismuth oxide is filled in the gap formed on the outer periphery of the rod with a sealing agent made of rubidium oxide or cesium oxide, and the outer end surface of the sealing portion closes the gap. There is an invention of a foil seal lamp in which is sealed.

  In the above invention, it is described that the lead wire and the foil exposed to the oxidizing environment can be shielded from the outside air by blocking the air entrance at the outer end of the sealing portion, so that the oxidation can be prevented. . If the lead wire or the like is oxidized, it may cause the foil to melt.

JP 2004-319177 A

  However, if the oxide is used to close the gap between the sealing portion and the lead wire, the manufacturing process is increased and complicated, and the cost is increased.

  Therefore, as a result of various experiments conducted by the present inventors, a crack is formed on the contact surface of the sealing portion that seals the external lead wire, thereby preventing intrusion of the atmosphere without using other materials. I found out that I could suppress it and came to propose.

  The objective of this invention is suppressing generation | occurrence | production of the fusion | melting of the welding part of an external lead wire and metal foil.

In order to achieve the above object, a metal halide lamp according to the present invention includes a light-transmitting hermetic container having an arc tube portion that forms a discharge space, sealing portions formed at both ends of the arc tube portion, and the discharge. A discharge medium in which a metal halide and a rare gas are sealed in a space and essentially free of mercury, a metal foil sealed inside the sealing portion, one end connected to the metal foil, and the other end a pair of electrodes arranged opposite at the discharge space, one end of which is connected to the metal foil and the other end provided with an external lead wire led out of the airtight container, of the front Kifu stop portion A plurality of cracks are formed in the portion sealing the external lead wire, and the formation range of the crack in the axial direction is 2.0 mm or more.

  According to the present invention, it is possible to suppress the occurrence of fusing of the welded portion between the external lead wire and the metal foil.

(First embodiment)
Hereinafter, a metal halide lamp according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall view of a metal halide lamp according to a first embodiment of the present invention.

  The hermetic container 1 is made of, for example, a fire-resistant and light-transmitting quartz glass, and has a luminous tube portion 11 having a substantially elliptical shape in the axial direction and a plate-like sealing that is crushed at both ends in the longitudinal direction. Parts 131 and 132. Inside the arc tube portion 11, there is formed a discharge space 12 having a substantially cylindrical shape in the axial direction and an internal volume of 0.1 cc or less. The discharge space 12 is made of metal halide as a discharge medium. Some sodium iodide, scandium iodide, zinc iodide, and a rare gas, xenon, are enclosed.

  Metal sodium contained in sodium iodide and metal scandium contained in scandium iodide mainly act as luminescent metals, and the metal zinc contained in zinc iodide is mainly a lamp voltage instead of mercury. Acts as a forming medium. Iodine, which is less reactive than other halides, is most suitable as the halide bonded to these luminescent metals, but other halogens such as bromine and chlorine are used, or combinations thereof are used. Or you may. Also, xenon, which is a rare gas, mainly acts as a starting gas because of its high luminous efficiency immediately after starting.

  Here, the discharge medium sealed in the arc tube portion 11 essentially does not contain mercury. This “essentially free of mercury” means that it does not contain any mercury, or accepts an amount of mercury of less than 2 mg per cc, preferably 1 mg or less. In other words, when the voltage of a metal halide lamp is increased to a required level by mercury vapor as in a conventional short arc lamp containing mercury, 20 to 40 mg per cc, or 50 mg or more in some cases is sealed. Then, it can be said that the amount of mercury of less than 2 mg is overwhelmingly small and essentially contains no mercury.

  The metal foils 21 and 22 made of, for example, molybdenum are sealed inside the sealing portions 131 and 132 so that the planes thereof are parallel to the planes of the sealing portions 131 and 132. At one end of the metal foils 21 and 22, stepped electrodes 31 and 32 made of, for example, tungsten and having a distal end formed larger in diameter than the proximal end, and coils 41 and 42 are wound around the proximal end. In this state, they are connected by resistance welding. The tips of the electrodes 31 and 32 are arranged so that the tips of the electrodes 31 and 32 face each other while maintaining a predetermined distance between the electrodes in the discharge space 12. Here, the “predetermined” is about 4.2 mm when used for an automobile headlamp, about 2 mm when used for a projection, and 5 mm or less is preferable for a short arc lamp.

  One end of the external lead wires 51 and 52 is connected to the other end of the metal foils 21 and 22 by resistance welding or the like, and the other end extends to the outside of the sealing portions 131 and 132. Here, the crack 14 in the axial direction is formed on the glass in the contact portion with the external lead wire 52 in the sealing portion 132 on the front end side of the metal halide lamp where the welded portion between the metal foil and the external lead wire is likely to become high temperature during lighting. The formation range is formed by dmm. In addition, one end of a power supply terminal 53 formed in an L shape is connected to the external lead wire 52 extending in the outward direction of the sealing portion 132 so as to be substantially perpendicular. A part of the power supply terminal 53 is covered with, for example, an insulating tube 6 made of ceramic so that the potential of the external lead wire 52 does not affect the part.

  On the outside of the hermetic container 1 equipped with these, for example, a cylindrical outer tube 7 formed by attaching alumina oxide to quartz glass and blocking ultraviolet rays is hermetically sealed along its longitudinal direction. It is provided so as to cover most of the container 1. At both ends of the outer tube 7 in the longitudinal direction, weld portions 71 connected to the sealing portion 132 by glass welding are formed. (The welded portion on the other end side is not shown.) Here, the space formed by the outer tube 7 and the airtight container 1 is in an atmospheric atmosphere, but if desired, argon can be enclosed, Or a vacuum atmosphere.

  The outer tube 7 with the airtight container 1 covered inside is connected to the socket 9 by a fixed metal tool 8 formed so as to sandwich the outer peripheral surface thereof. Near the end of the socket 9, a metal terminal 91 for supplying power from the lighting circuit is formed along the outer peripheral surface, and the metal terminal 91 is connected via the external lead wire 52 and the power supply terminal 53. Electrically connected. Although not shown, the other terminal for supplying power is formed at the bottom portion of the socket 9, and this terminal is electrically connected to the external lead wire 51.

  The metal halide lamp composed of these is lit with about 75 W at start-up and about 35 W at stable.

  FIG. 2 is an enlarged view for explaining a sealing portion in the vicinity of a crack forming portion. Here, the outer tube 7 is removed so that the crack 14 can be easily confirmed.

  In the figure, a sealing portion 132 in the vicinity includes a flat rectangular pinch portion 132a, a columnar shrink portion 132b mainly serving as a welding location with the outer tube 7, and a cone serving as a boundary between the pinch portion 132a and the shrink portion 132b. It is comprised from the trapezoid taper part 132c. A plurality of cracks 141 to 148 are formed on the glass surface of the sealing portion 132 that is in contact with the external lead wire 52, and these cracks 141 to 148 are formed on the axis of the external lead wire 52. When the forming range in the direction is d, it is 2.0 mm or more. Here, the above-mentioned “formation range in the axial direction of a plurality of cracks” refers to the distance between cracks located at both extremes among the cracks formed in the axial direction of the sealing portion 132 in contact with the external lead wire 52. This corresponds to the distance d between the cracks 141 and 148 in FIG.

  Next, the formation process of the crack 14 will be described. Here, in the formation of the crack 14, the process after the pinch sealing process of the sealing portion 132 is important, and the other processes are omitted because they are not significantly different from the known metal halide lamp manufacturing process.

  After the pinch sealing process in which the quartz glass is heated to about 1800 ° C., which is the processable temperature of the quartz glass, and is pressed with a planar pincher to form the pinch portion 132a, the sealing portion 132 and the external lead wire 52 are at a high temperature. Therefore, they are in a state of being expanded more than at normal temperature, and in particular, the external lead wire 52 is expanded in the axial direction.

  Thereafter, the sealing portion 132 is completed by cooling and solidifying those portions, but the presence or absence of the crack 14 in the sealing portion 132 or the formation range when the crack 14 is formed changes depending on the cooling and solidifying conditions. More specifically, the shape of the external lead wire 52 that is a metal is likely to change between quartz glass, which is the material of the sealing portion 132, and molybdenum, which is the material of the external lead wire 52. After the pinch sealing step, the expanded external lead wire 52 precedes and contracts in the axial direction (compression). Since the compression of the external lead wire 52 contracts while drawing the surface of the sealing portion 132 that is in contact with the external lead wire 52, if the strength of drawing the glass is strong, the durability of the quartz glass The force 14 is exceeded and a crack 14 is formed. Therefore, for example, when the temperature of the sealing part 132 immediately after the pinch seal is lowered at a rate of about 30 ° C. by lowering the ambient temperature or blowing the cooling gas to the sealing part 132, the final It was confirmed that cracks 14 having a forming range of about 2.0 mm were formed in the axial direction in the metal halide lamp assembled in 1). On the other hand, if the temperature of the sealing portion 132 was lowered relatively slowly immediately after the pinch seal, the crack 14 did not occur.

  FIG. 3 is an enlarged view for explaining an example of the specification of the metal halide lamp of FIG. The volume of the discharge space 12 is 29 cc, the inner diameter A of the arc tube portion 11 is 2.6 mm, the outer diameter B is 6.2 mm, the maximum length C in the longitudinal direction is 7.8 mm, the interelectrode distance D is 4.4 mm, and the electrode 31 32, the diameter of the distal end portion is 0.38 mm, the diameter of the proximal end portion is 0.30 mm, and the diameters of the external lead wires 51 and 52 are 0.40 mm. The arc tube 11 is filled with 0.6 mg of scandium iodide-sodium iodide-zinc iodide as a discharge medium and 11 atm of xenon as a rare gas, and contains no mercury as a discharge medium. Absent.

  FIG. 4 is a diagram for explaining the occurrence of fusing of the metal foil when the axial formation range d of the crack is changed in the lamp specification of FIG. Here, the test performed this time is a 2000 hour flashing test in the EU 120 minute mode, which is a life test condition of a metal halide lamp for automobile headlamps, which is determined by the Japan Light Bulb Industry Association. Further, in the test, 20 lamps having different crack formation ranges d in the axial direction were manufactured, and the evaluation of the occurrence of fusing of the metal foil in the figure was 10-20 out of 20 fusing occurrences. 3 to 9 out of 20, ○ is 1 to 2 out of 20, and ◎ is 0 out of 20.

  FIG. 4 shows that the number of occurrences of fusing of the metal foil 22 decreases as the formation range d of the crack 14 increases. Here, when the formation range d of the crack 14 was changed from 0 mm to 0.5 mm, a great reduction effect of the number of occurrences of fusing of the metal foil 22 was observed. However, many lamps were turned off after 2000 hours. It is not suitable. Therefore, it is good that it is 2.0 mm or less which can keep the fusing rate of the metal foil 22 to 10% or less even after 2000 hours. Furthermore, it is preferable that the thickness is 2.5 mm or more so that non-lighting due to the melting of the metal foil 22 does not occur even after 2000 hours. Here, in FIG. 2, there is a portion in which no crack is formed in the middle of the range, but it is confirmed that the formation distance of the crack 14 from the beginning to the end in the axial direction is most related, which is a problem. There is no.

  Next, the fusing relationship between the crack 14 and the metal foil 22 is estimated as follows. First, the cause of the fusing of the metal foil 22 is a temperature increase due to lighting and volume expansion due to oxidation of the external lead wire 52 due to the entry of outside air from the outside. Therefore, when the crack 14 is formed in the sealing portion 132, first, although the contact surface between the external lead wire 52 in which the crack 14 is formed and the sealing portion 132 cannot be visually confirmed, the compression of the external lead wire 52 is performed. The compressive strain formed by the pulling of the glass at the time is formed, and it is expected that the adhesiveness is improved by the compressive strain and it is difficult to generate a gap for intrusion of outside air. Secondly, it is expected that the formed crack itself becomes a second outside air entry path and reduces the amount of outside air toward the metal foil 22. That is, it is considered that the cracks 14 formed in the lamp of the present invention acted to suppress the entry of outside air and suppressed the occurrence of fusing of the metal foil 22.

  In the present embodiment, in the metal halide lamp that essentially does not contain mercury in the discharge space 12, a plurality of cracks 14 are formed in the sealing portion 132 that seals the external lead wire 52, and the axial direction of the crack 14 is By setting the formation range to 2.0 mm or more, it is possible to suppress the entry of outside air, which is one of the causes of the oxidation of the external lead wire 52, and thus it is possible to prevent the metal foil 22 from being blown out.

  In addition, embodiment is not necessarily restricted above, For example, you may change as follows.

  In the present invention, no upper limit is set for the formation range d of the crack 14. This is because the effect of reducing the number of occurrences of fusing of the metal foil 22 is improved as the cracks 14 are formed larger. That is, the formation range d of the crack 14 may be formed as large as possible. Further, as the crack 14 is formed, the change of other characteristics, for example, the deterioration of the lamp life characteristics and the change of the lamp characteristics due to the intentional formation of the cracks have not been confirmed.

  Further, the crack 14 may be formed not only on the sealing portion 132 side on the front end side of the lamp where the metal foil is likely to be melted but also on the sealing end portion 131 on the base end side of the lamp, that is, on the socket 9 side.

The whole figure for demonstrating 1st Embodiment of the metal halide lamp of this invention. The enlarged view for demonstrating the sealing part of the crack formation part vicinity. The enlarged view for demonstrating the example of the specification of the metal halide lamp of FIG. FIG. 4 is a diagram for explaining the occurrence of fusing of a metal foil when the formation range d of the crack in the axial direction is changed in the lamp specification of FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Airtight container 11 Light emission tube part 12 Discharge space 131, 132 Sealing part 14 Crack 21, 22 Metal foil 31, 32 Electrode 41, 42 Coil 51, 52 External lead wire 53 Feed terminal 6 Insulation tube 7 Outer tube 8 Fixed metal tool 9 Socket

Claims (1)

A translucent airtight container having an arc tube portion forming a discharge space, sealing portions formed at both ends of the arc tube portion;
A discharge medium in which a metal halide and a rare gas are enclosed in the discharge space, and essentially free of mercury;
A metal foil sealed inside the sealing portion;
One end is connected to the metal foil, and the other end is a pair of electrodes opposed to each other in the discharge space,
One end is connected to the metal foil, and the other end includes an external lead wire leading out of the hermetic container,
Before Of Kifu stop portion, said the portion which seals the external leads are cracks plurality formation, a metal halide, wherein the axial formation range of the cracking is 2.0mm or more lamp.

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