JP3379438B2 - Lamp with foil seal structure - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lamp having a foil sealing structure. 2. Description of the Related Art For example, in a high-current or ultra-high-pressure mercury lamp for a large current, the amount of mercury, which is a main component of a luminescent gas, is large, the gas pressure at the time of lighting is high, and It is necessary that the pressure resistance is large. Therefore, a so-called foil seal structure using a metal foil for sealing is generally employed in a high-pressure mercury lamp or an ultra-high-pressure mercury lamp. [0003] As a technique relating to a foil seal structure, for example, there is one disclosed in Japanese Utility Model Laid-Open No. 6-60960.
The high-pressure mercury lamp according to the present invention will be described with reference to the drawings. FIG. 5 is a cross-sectional view of the hermetic sealing portion of the high-pressure mercury lamp as viewed from the side. FIG. 6 is a cross-sectional view of the high-pressure mercury lamp cut along a broken line portion A in FIG. The electrode 6 is arranged in the light emitting space surrounding portion 82, and the internal lead rod 3 following the electrode 6 is inserted into the glass cylinder 7 arranged inside the sealing tube 81, and the front end of the columnar glass body 1 is formed. It is welded to a disk-shaped first metal plate 31 arranged along the surface. The glass body 1 has a hole 12 on the rear side, and the external lead rod 4 is inserted into the hole 12. The external lead rod 4 is welded in a state of being inserted through a disk-shaped second metal plate 41 disposed on the rear end face of the glass body 1, and is inserted through the glass cylinder 10 at the rear thereof. On the outer peripheral surface of the glass body 1, a first metal foil 2
The first metal foil 20 is welded to the first metal plate 31 at one end 21 and to the second metal plate 41 at the other end 22 thereof. A second metal foil 25 is provided on the outer peripheral surface.
The first and second metal foils are strip-shaped, and are arranged so as to be separated from each other in the circumferential direction of the glass body 1 and extend in the longitudinal direction as shown in FIG. The inner periphery of the sealing tube 81 and the outer periphery of the glass body 1 are welded through the metal foils 20 and 25, and the inner periphery of the rear end of the sealing tube and the outer periphery of the glass tube 10 are welded. Thereby, the hermetic sealing portion of the high-pressure mercury lamp is formed. However, the high-pressure mercury lamp having the hermetically sealed portion having the above-described structure is made of metal such as the metal foils 20 and 25 or the second metal plate 41, which is disposed inside the sealing tube 81. In some cases, the conductive member was oxidized and a long service life could not be obtained. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has the following objects.
An object of the present invention is to provide a lamp capable of preventing a conductive member in a hermetically sealed portion of a lamp from being oxidized and obtaining a long service life even with a large current. Therefore, a lamp having a foil sealing structure according to the present invention comprises a glass light emitting tube comprising a light emitting space surrounding portion and a sealing tube following the light emitting space surrounding portion, and an inside of the sealing tube. , A first metal plate and a second metal plate respectively disposed on a front end face and a rear end face of the glass body, and a base end electrically connected to the first metal plate. An internal lead bar connected to the light emitting space surrounding portion, the electrode being provided at the distal end of the internal lead bar, and an external lead electrically connected to the second metal plate. A rod and a metal foil extending along the outer periphery of the glass body, one end of which is electrically connected to the first metal plate and the other end of which is electrically connected to the second metal plate, The metal foil is the other part except the one end side Is thicker than the thickness on the one end side. 2 (a) and 2 (b) show a hermetically sealed portion of a high-pressure mercury lamp according to an embodiment, where (a) is a cross-sectional view as viewed from the side, and (b) 3A is a cross-sectional view taken along a broken line portion A in FIG. As shown in FIG. 2A, the sealing tube 81 of the luminous tube 8 made of quartz glass
Inside, a columnar and solid glass body 1 is disposed. A disk-shaped first metal plate 31 is arranged on the front end face of the glass body 1. The first metal plate 31 is made of, for example, molybdenum. In the center of the first metal plate 31,
The inner lead rod 3 extending toward the light emitting space surrounding portion 82 is welded. An electrode 6 is provided at the tip of the internal lead bar 3. A glass cylinder 7 is disposed between the outer periphery of the inner lead bar 3 and the inner periphery of the sealing tube 81, and the inner lead bar 3 is inserted into and held by the glass cylinder 7. . A hole 12 is formed at the rear of the glass body 1,
An external lead rod 4 that fits inside the hole 12 is inserted. The external lead rod 4 is inserted into a hole of the second metal plate 41 arranged on the rear end face of the glass body 1 and connected by welding near the hole. Further behind, it is inserted into and held by the glass cylinder 10. An electrode 6 followed by an internal lead 3,
Alternatively, a material for forming the external lead rod 4 is, for example, tungsten of a high melting point metal.
The metal plate 31 or the second metal plate 41 is, for example, molybdenum. The electrode 6 is provided integrally with the internal lead rod 3 in the case of a cathode of a lamp which is lit by direct current, for example, by shaping the tip of the internal lead rod 3 into a cone shape by shaving. A first metal plate 31 and a second metal plate 41
Is generally a disk-shaped metal plate having a diameter equal to or slightly smaller than the end face of the glass body 1. Note that disk metal foils 32 and 42 having substantially the same dimensions as the first metal plate 31 or the second metal plate 41 are provided on both surfaces of the first metal plate 31 and the second metal plate 41. You. The disk-shaped metal foils 32 and 42 are made of, for example, molybdenum foil. This prevents the first metal plate 31 or the second metal plate 41 from being welded to a glass member arranged in contact with each of the front and rear sides, and distortion occurs between the metal and the glass. Is prevented. In the outer periphery of the glass body 1, FIG.
As shown in FIG.
For example, four strip-shaped metal foils 2 made of molybdenum are arranged so as to extend in the axial direction. One end 21 of each of the metal foils 2 is connected to a first metal plate 31, and the other end 22 is connected to a second metal plate 41. Here, as shown in FIG. 3, the metal foil 2 has a small thickness at a portion at a distance L1 from the front end on one end side, and has a large thickness on the rear end side. FIG. 1 shows a lamp according to the invention. FIG. 1 is a cross-sectional view of the high-pressure mercury lamp according to the present invention when viewed from the side. As shown in the figure, an external lead rod 4 extending outward from both ends of the lamp is connected to a lead wire 5.
1 is connected to the base 52. Then, a gap between the base 52 and the sealing tube 81 is filled with an adhesive 53 and fixed. In the lamp according to the present invention, the thickness of the metal foil is thinner at a distance L1 from the front end on one end side and thicker on the rear end side. It has become possible to prevent the oxidation of the metal foil and the oxidation of the second metal plate inside the sealing tube.
The reason will be described. As a result of intensive studies on the cause of oxidation of the metal foil, the present inventor has found that the problems that have occurred in the prior art are as follows. According to the prior art, the second metal foil is superimposed on the first metal foil to prevent self-heating in the metal foil inside the sealing tube, thereby causing a difference in thermal expansion between the metal and the glass. The heat distortion caused by this was prevented. However, when the sealing tube is hermetically welded, since the first and second metal foils are interposed and welded between the sealing tube and the glass body disposed inside the sealing tube, the two metal foils are bonded together. Air may remain between them. Also, since a large current flows while the lamp is on,
The temperature becomes extremely high due to self-heating of the metal foil portion and arc heat from the electrode tip. Therefore, it was found that the first and second metal foils were exposed to a high-temperature air atmosphere and oxidized. Further, it is essential to completely shut off the outside air inside the sealing tube. In the prior art, since the sealing of two metal foils in a stacked manner lacks sealing reliability, the second metal foil has not been disposed so as to reach the end of the first metal foil. As a result, the electrical resistance increases at both ends of the first metal foil, and the temperature increases. One end of the metal foil (light emitting space side) is preferable from the viewpoint of preventing the non-evaporation of mercury, but the other end of the metal foil is oxidized by a metal member such as the metal foil or the second metal plate. It was undesirable, and it was not avoided. However, according to the present invention, since the metal foil is not used in an overlapping manner, no air remains inside when the sealing tube is airtightly sealed. Accordingly, the metal foil is not oxidized during the operation of the lamp. Since the thickness of the metal foil 2 near the other end is increased to reduce the electric resistance during lighting, self-heating at that portion of the metal foil can be suppressed. Therefore, the temperature of the sealing tube in the vicinity of the second metal plate can be reduced, and the second metal plate that is likely to be exposed to the outside air is not oxidized. Here, the distortion caused by the difference in thermal expansion between the metal foil and the glass in contact with the metal foil is caused by thickening the metal foil, but the pressure outside the sealing pipe is atmospheric pressure, and the pressure at the rear end of the sealing pipe is Since very high gas pressure does not act on the glass as in the glass on the light emitting space surrounding portion side, cracks and the like do not occur in the glass portion. By the way, during the operation of the lamp, a higher pressure resistance is required on the luminous space surrounding portion side of the sealing tube, but according to the present invention, near the one end portion (luminous space side) of the metal foil. Since the thickness of the metal foil at one end is small, distortion can be reduced, and therefore, no glass accident such as cracking or rupture of the sealing tube occurs, and the service life of the lamp can be extended. Further, according to the present invention, since the metal foil is thin at one end, the electric resistance is large, and the metal foil generates heat at that portion. However, in the case of high-pressure mercury lamps and ultra-high-pressure mercury lamps, evaporation of mercury sealed inside the arc tube is essential, and self-heating on the side of the metal foil surrounding the light-emitting space contributes to evaporation of mercury, which is very effective. It is. Even if the temperature of the metal foil becomes high at one end, the metal foil and the first metal plate at that portion are not exposed to the outside air because they are located on the light-emitting space surrounding portion side. The members are not oxidized. EXAMPLE In order to demonstrate the effect of the present invention, a conductive part construct having a hermetically sealed portion of a high-pressure mercury lamp according to the present invention shown in FIG. The temperature was measured. As shown in FIG.
Using the metal foil 2, the first metal plate 31, the second metal plate 41, the internal lead rods 3 and the external lead rods 4, a conductive part construction for temperature measurement was manufactured. The metal foil 2 is made of molybdenum and has a thickness D of 60.
μm, the total length L is 50 mm, and the distance L1 from one end is 1
The thickness d of the 5 mm portion is 40 μm. Three to four metal foils 2 were prepared and arranged on the outer peripheral surface of the glass body 1 so as to be spaced apart from each other at substantially equal intervals. The inner lead rod 3 and the outer lead rod 4 were made of a tungsten rod having a diameter of 6 mm, and an electrode 6 also made of tungsten was attached to the tip of the inner lead rod 3. The outer diameter of the glass body 1 is φ16 mm, and the total length is 50 mm. Then, a first metal plate 31 and a second metal plate 41 having outer diameters substantially equal to the outer diameter of the glass body 1 are arranged on both bottom surfaces of the glass body 1. The inner lead bar 3 was welded to the first metal plate 31 and the outer lead bar 4 was welded to the second metal plate 41, respectively. In order to compare the temperature change of the metal foil 2, a conductive part construction was produced in the same manner as the above construction using a molybdenum foil having a uniform thickness of 40 μm. Then, the assembly is placed in an inert gas and the internal lead rod 3
And the external lead rod 4 were connected to supply a current of 100 A. FIG. 4 is a graph showing the temperature of each part.
In the case where three metal foils 2 are provided and in the case where four metal foils 2 are provided, the L1 portion is 40 μm and the other portions are 60 μm.
It was found that the temperature decreased in each part and that the self-heating of the metal foil could be reduced. And it turned out that the temperature inside the sealing pipe 81 can be reduced by this invention. As described above, according to the present invention, the thickness of the other parts except the one end is made larger than the thickness of the one end, so that the self-heating of the metal foil at the other end is suppressed and the temperature is reduced. Therefore, oxidation of a metal member disposed in the sealing tube, such as a metal foil or a second metal plate, is less likely to occur. In addition, since the metal foil is not overlapped, the possibility that air remains in the sealing portion is low, and oxidation of the foil becomes difficult. As described above, the metal foil disposed in the hermetically sealed portion is made thinner on the light emitting space surrounding portion side, and the other portions except the light emitting space surrounding portion side are made thinner. By increasing the thickness, it is not necessary to seal two pieces of metal foil, so that the inside of the sealing tube can be made airtight and the metal foil is not oxidized, and one end is formed. In addition to the above, the self-heating of the metal foil can be prevented in other portions, and the metal power supply member inside the sealing tube is not oxidized. Therefore, it is possible to provide a lamp having a long service life, in which power supply failure does not occur even with a large current.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a lamp according to an embodiment of the present invention when viewed from the side. FIG. 2A is a cross-sectional view of a hermetic sealing portion of a lamp according to an embodiment of the present invention when viewed from the side. (B) It is a cross-sectional view showing an arrangement state of a metal foil in one example of the present invention. FIG. 3 is an explanatory diagram showing an enlarged view of a conductive portion according to an embodiment of the present invention. FIG. 4 is a graph showing a temperature at a point on a metal foil. FIG. 5 is a cross-sectional view of a hermetically sealed portion of a conventional lamp when viewed from the side. FIG. 6 is a cross-sectional view showing an arrangement state of metal foil of a conventional lamp. DESCRIPTION OF SYMBOLS 1 Glass body 12 Hole 2 Metal foil 20 First metal foil 21 One end 22 Other end 25 Second metal foil 3 Internal lead rod 31 First metal plate 32 Disk-shaped metal foil 4 External lead Rod 41 Second metal plate 42 Disk-shaped metal foil 51 Lead wire 52 Cap 53 Adhesive 6 Electrode 7 Glass cylinder 8 Emitting tube 81 Sealing tube 82 Emitting space surrounding portion 10 Glass cylinder

Claims (1)

(57) [Claim 1] A glass light emitting tube comprising a light emitting space surrounding portion and a sealing tube subsequent thereto, a columnar glass body disposed inside the sealing tube, and the glass A first metal plate and a second metal plate disposed on a front end surface and a rear end surface of the body, respectively;
An inner lead bar electrically connected to the metal plate of the first embodiment, and disposed to extend into the light emitting space; an electrode provided at a tip of the inner lead bar;
An external lead rod electrically connected to the metal plate, and extending along the outer periphery of the glass body, one end of which is electrically connected to the first metal plate, and the other end of which is electrically connected to the second metal plate. A lamp having a foil sealing structure, characterized in that the metal foil has a thickness other than the one end side is greater than the thickness of the one end side. .