JP3228073B2 - Discharge lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp, and more particularly to a discharge lamp having a hermetically sealed structure particularly suitable for a large current.

[0002]

2. Description of the Related Art Discharge lamps, for example, mercury lamps, are widely used in fields utilizing ultraviolet rays emitted therefrom, for example, in the photochemical industry, in the manufacture of semiconductor devices, and in other fields.

For example, in a high-current mercury lamp or an ultra-high-pressure mercury lamp for a large current, the amount of mercury, which is the main component of the luminous gas, is large, and the gas pressure in the luminous tube at the time of lighting is extremely high.
In addition, the calorific value is large, and therefore, the glass of the hermetically sealed portion needs to have high heat resistance and pressure resistance. Then, it is necessary that the mercury in the arc tube is completely evaporated during lighting, and therefore, there must be no low temperature portion in the arc tube during lighting in which mercury condensation occurs.

In view of the above, in a conventional high-pressure mercury lamp or ultra-high-pressure mercury lamp, a so-called rod which achieves hermetic sealing of the arc tube by directly welding glass forming the arc tube to a power supply lead rod. Instead of a seal structure, a so-called foil seal structure using a metal foil for sealing is employed.

FIG. 7 is an explanatory view showing an example of a high-pressure mercury lamp having a foil seal structure. 8 is a light emitting space surrounding portion 82
And a sealing tube 81 following the sealing tube. An electrode 9 is arranged in the light emitting space surrounding portion 82 of the sealing body 8, and the electrode 9 is supported by the internal lead rod 4. The internal lead rod 4 is held in the sealing tube portion 81 by the internal lead rod holding cylinder 6. And internal lead rod 4
A metal plate 3 made of a high-melting-point metal such as molybdenum is welded to the base end portion, and a power supply metal foil 2 is welded to a surface of the metal plate 3 on the light emitting space surrounding portion 82 side. For example, five metal foils for power supply 2 are arranged on the outer periphery of the columnar glass member 1 in a strip shape in the axial direction of the glass member 1 so as to be spaced apart in the circumferential direction. And the metal foil 2 for power supply
Is welded to a dish-shaped metal member 51 at the other end opposite to the direction of welding to the metal plate 3, and is electrically connected to the external lead rod 5 via the metal member 51. . Since the other sealing tube has the same structure, the description is omitted.

The electrode 9 is inserted and arranged in the light emitting space surrounding portion 82 of the sealing body 8 configured as described above.
Then, the sealing body 8 is, for example,
00r. p. While rotating in the circumferential direction at a speed of about m
A heat treatment is performed from the outside of the sealing tube portion 81 using a burner or the like, and the inner periphery of the sealing tube portion 81 and the outer periphery of the glass member 1 are hermetically welded via the metal foil 2 for power supply. On the base end side of the internal lead rod 4, the glass in the portion of the sealing tube portion 81 facing the internal lead rod holding cylinder 6 is heated and pressed or a negative pressure is applied to the inside of the sealing tube portion 81. hand,
The constriction K is formed by welding the inner lead rod holding cylinder 6 with the negative pressure. Note that the other sealing tube has the same structure, and the description is omitted.

[0007]

However, in the discharge lamp configured as described above, the following problem occurs in the heat treatment step of the sealing tube portion 81.

One end face of the glass member 1 in contact with the metal plate 3 or its vicinity (region a in FIG. 7), or one end face of the internal lead rod holding cylinder 6 in contact with the metal plate 3 or its vicinity. (A region b in FIG. 7)
Fine cracks may be generated during the heat treatment step. The cause of the cracks is that the metal plate 3 is made of a high melting point metal such as molybdenum, whereas the glass member 1 and the internal lead rod holding cylinder 6 are made of glass, and have different expansion coefficients. Moreover, the metal plate 3 is composed of the internal lead rod 4 and the electrode 9.
It must be hard to support steel, and a certain large thickness is required. As a result, when the glass member 1 and the internal lead rod holding cylinder 6 are melted and come into contact with the metal plate 3, a large force is exerted on the glass member 1 and the internal lead rod holding cylinder 6 to extend the metal plate 3. When the glass member 1 is further cooled in this state, the glass member 1 and the internal lead rod holding cylinder 6 receive a large force to shrink the metal plate 3. Alternatively, minute cracks are formed on one end face of the inner lead rod holding cylinder 6 which is in contact with the metal plate 3 or in the vicinity thereof. Further, when the discharge lamp in which such fine cracks are generated is turned on, the gas pressure in the arc tube surrounding portion 82 becomes extremely high, so that the cracks grow (the cracks become large) and, consequently, the gas leaks or This means that the sealing tube 81 is broken.

The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent the occurrence of cracks in a glass member or an internal lead rod holding cylinder disposed in a sealing tube. Accordingly, a discharge lamp can be provided which can prevent gas leakage and breakage of the sealing tube portion, and can obtain a long service life.

[0010]

According to a first aspect of the present invention, there is provided a discharge lamp including a columnar glass member disposed inside a sealing tube portion of a glass envelope, and a light emitting space of the glass member. A metal plate arranged on one side facing the surrounding portion side, an internal lead rod having a base end fixed to the metal plate, a tip extending into the light emitting space surrounding portion, and an electrode provided at the tip thereof,
A glass inner lead rod holding cylinder disposed between the outer circumference of the inner lead rod and the inner circumference of the sealing tube portion of the sealing body; and one end portion extending along the outer circumference of the glass member, Is a metal foil for power supply connected to the metal plate and the other end is electrically connected to an external lead rod, and a metal foil having a thickness smaller than that of the metal plate between the glass member and the metal plate. was placed, characterized in that a metal foil thickness than the metal plate is small between the connection has been feed metal foil to the metal plate and the internal lead rod cylindrical retaining body made of said glass .

[0011]

A discharge lamp according to a second aspect of the present invention is the discharge lamp according to the first aspect, in particular, the metal foil has a protrusion formed by being pressed from one side to the other side. It is characterized by having.

[0013]

A high melting point metal, for example, a molybdenum metal, is provided between the glass member and the metal plate and between the glass internal lead rod holding cylinder and the metal plate in the sealing tube portion of the sealing body. By arranging the foil, during the heat treatment process of the sealing tube,
It is possible to prevent the glass member and the metal plate and the glass-made internal lead rod holding cylinder from being welded to the metal plate. Furthermore, since this metal foil is extremely thin compared to a metal plate having a large thickness for supporting the internal lead rods and electrodes,
During the heating step and the cooling step of the sealing tube part of the envelope, even when the glass member and the inner lead rod holding cylinder are melted and come into contact with the metal foil, the metal foil is used for holding the glass member and the inner lead rod. The expansion and contraction forces of the metal foil itself applied to the cylinder are extremely small, and cracks do not occur in the glass member or the internal lead rod holding cylinder.

Furthermore, since the metal foil has a projection formed by pressing from one side to the other side, the glass member and the inner lead rod holding cylinder are melted and come into contact with the metal foil. In the state and the cooling state thereafter, the expansion force and the contraction force of the metal foil can be absorbed by the metal foil itself by the protruding portion, so that the glass member or the inner lead rod holding cylinder is further cracked. Nothing.
The operation and effect are the same whether the protrusion of the metal foil is directed toward the glass member and the inner lead rod holding cylinder or toward the metal plate.

【Example】

FIG. 5 is an explanatory view showing an example of a high-pressure mercury lamp having a foil seal structure. 1 is a cylindrical glass member,
2 is a band-shaped metal foil for power supply, 3 is a disk-shaped metal plate, 4
Is an internal lead rod, 5 is an external lead rod, 51 is a dish-shaped metal member, 6 is an internal lead rod holding cylinder, 7 is an external lead rod holding cylinder, M and M1 are metal foils, and a metal plate. 3, a glass member 1 and a glass internal lead rod holding cylinder 6
The metal M1 is disposed between the power supply metal foil 2 welded on the metal plate 3 and , as shown in FIG. 6, the metal M1 has a hole at its center through which the internal lead rod 4 passes. It is ring-shaped. These form a sealing conductive portion S. Reference numeral 9 denotes an electrode, and reference numeral 8 denotes a sealing body including a light emitting space surrounding portion 82 and a sealing tube portion 81 following the light emitting space surrounding portion 82.

The columnar glass member 1 has a tapered outer peripheral surface on a portion of the peripheral wall 16 following the one end surface 11 on the light emitting space surrounding portion 82 side, and the portion on one end surface 11 side has a truncated cone shape. It is configured. In addition, a hole 13 for installing the external lead bar 5 is formed in the other side surface 12 on the outer end side of the sealing tube portion 81.

The connection method between the metal plate 3 and the internal lead rod 4 is not particularly limited.
Or a method in which a hole is formed in the center of the metal plate 3 and the base end of the internal lead rod 4 is inserted into this hole to weld them together. Examples of a material for forming the metal plate 3 include high melting point metals such as tantalum, niobium, tungsten, and molybdenum. In order to support the electrode 9 and the internal lead bar 4, it is necessary to have hardness, and its thickness is about 0.5 mm.

Between the outer periphery of the inner lead rod 4 and the inner periphery of the sealing tube 81 of the sealing body 8, a glass-made inner lead rod holding cylinder 6 is disposed.

Between the glass member 1 and the metal plate 3, there is disposed a metal foil M in which one to three molybdenum foils each having a thickness of about 15 μm are stacked. In the present example, two molybdenum foils were stacked, and the thickness of the metal foil M was set to 30 μm. This metal foil is shown in FIG. This metal foil is made of molybdenum, but may be any metal having a high melting point, and is not particularly limited. FIG. 3 shows a metal foil having a projection formed thereon. This protrusion has a diameter of 3 by pressing, for example.
It can be formed by embossing about mm. Further, the metal foil M1 has no protrusion.
However, a projection may be provided as shown in FIG. The diameters of the metal foil M and the metal foil M1 are almost the same as those of the metal plate 3.

FIG. 4 is an explanatory view showing an example of the internal lead rod holding cylinder 6. This internal lead rod holding cylinder 6
The end portion 65 following the one end surface 61 on the side of the metal plate 3 is formed in a tapered shape having a gradually increasing diameter, and a cylindrical body 62 formed subsequently is formed into a cylindrical body 6 for holding the internal lead rod. Extends to the end on the light emitting space surrounding portion 82 side. The outer diameter D of the body 62 is adapted to the inner diameter of the sealing tube 81 of the sealing body 8, and is preferably 0.5 mm to 1. The diameter is smaller by 0 mm. Further, one end surface 6 of the inner lead rod holding cylinder 6 on the metal plate 3 side.
1 is substantially the same as the diameter of the metal plate 3 or approximately 90% of the diameter of the metal plate 3.

The inner lead rod holding cylinder 6 has a slash-shaped recess 64 in the other end surface 63 on the light emitting space surrounding portion 82 side. In particular, the outer peripheral edge 66 of the other end surface 63 has a knife edge shape. Is preferably formed.

A stopper 41 made of a molybdenum wire wound around the outer periphery of the inner lead rod 4 is provided at the end of the cylindrical hole of the inner lead rod holding cylinder 6 on the light emitting space surrounding portion 82 side. The inner lead rod holding cylinder 6
Can be prevented from being displaced.

An external lead rod 5 having an outer diameter suitable for this is inserted into the hole 13 of the glass member 1, and the other end surface 12 of the glass member 1 has a bottom portion connected to the external lead rod 5. A dish-shaped metal member 51 having a hole formed therein is arranged,
An external lead rod holding cylinder 7 made of glass is arranged via the metal member 51. As a material for forming the metal member 51, molybdenum or the like can be given.

In the outer periphery of the glass member 1, for example, five strip-shaped molybdenum power supply metal foils 2 extending in the axial direction of the glass member 1 are arranged apart from each other in the circumferential direction. One end 21 of each of the metal foils 2
Extends along the tapered portion of the peripheral wall 16 of the glass member 1 and is further connected to the metal plate 3 arranged at the base end of the internal lead rod 4 by means such as spot welding. The other end 22 of each of the power supply metal foils 2 is connected to the metal member 51.

[0025]

As shown in FIG . 5, the outer periphery of the glass member 1 is heat-treated from outside the sealing tube portion 81 while rotating the sealing body 8 on which the conductive portion S for sealing is disposed, for example, with a glass lathe. And the inner periphery of the sealing tube 81 are hermetically welded via the metal foil 2 for power supply, and the outer periphery of the inner lead rod holding cylinder 6 and the inner periphery of the sealing tube 81 are further welded. A constriction K is formed. On the other hand, also in the sealing tube portion, although not shown, a sealing conductive portion configured similarly to the sealing conductive portion S is connected in the same manner as described above.

According to the above embodiment, the glass member 1 and the metal plate 3 having different expansion coefficients are separated by the metal foil M in the step of heating the sealing tube portion 81 of the sealing body 8. The glass member 1 and the metal plate 3 are not welded. Further, the metal foil M has a thickness of 30 μm, the metal plate 3 has a thickness of 0.5 mm to support the internal lead rods 4 and the electrodes 9, and the metal foil M has a thickness compared to the metal plate 3. Is extremely small, so that even when the glass member 1 is melted and comes into contact with the metal foil M during the heating step and the cooling step of the sealing tube portion of the sealed body, the expansion force exerted on the glass member 1 by the metal foil M and The shrinkage force is extremely small, and it is possible to prevent the glass member 1 from cracking.

In the step of heat-treating the sealing tube portion 81 of the sealing body 8, since the internal lead rod holding cylinder 6 and the metal plate 3 having different expansion coefficients are separated by the metal foil M1, the internal There is no welding between the lead rod holding cylinder 6 and the metal plate 3. Further, this metal foil M1 has a thickness of 3
0 μm, the metal plate 3 has a thickness of 0.5 mm to support the internal lead rods 4 and the electrodes 9, and the metal foil M 1 has an extremely small thickness as compared with the metal plate 3. Even when the internal lead rod holding cylinder 6 is melted and comes into contact with the metal foil M1 during the heating and cooling steps of the pipe portion, the metal foil M1 exerts an expanding force on the internal lead rod holding cylinder 6. In addition, the contraction force is extremely small, and it is possible to prevent the occurrence of cracks in the inner lead rod holding cylinder 6.

Further, in the case where the metal foils M and M1 are formed with protrusions, the protrusions are formed in a state where the glass member and the inner lead rod holding cylinder are melted and come into contact with the metal foil and a cooling state thereafter. Since the expansion force and the contraction force of the metal foil can be absorbed by the metal foil itself by the portion, the occurrence of cracks in the glass member or the inner lead rod holding cylinder can be further prevented.

The outer diameter of the glass member 1 is not limited to a columnar shape, but may be selected as appropriate according to the number of metal foils 2 for power supply to be used, and may be, for example, an octagonal column, a hexagonal column, or the like. Further, the metal foil 51 for power supply can be used without using the metal member 51.
May be directly connected to the outer periphery of the external lead rod 5.

The hermetically sealed structure described above can be used for other lamps requiring a large current.

[0032]

According to the present invention, a high melting point metal such as molybdenum is provided between the glass member and the metal plate and between the glass internal lead rod holding cylinder and the metal plate in the sealing tube portion of the sealing body. By disposing the metal foil, it is possible to prevent the glass member from being welded to the metal plate and the glass internal lead rod holding cylinder and the metal plate during the heat treatment step of the sealing tube portion. Further, since this metal foil is extremely small in thickness as compared with a metal plate having a large thickness for supporting the internal lead rod and the electrode, during the heating step and the cooling step of the sealing tube portion of the envelope,
Even when the glass member and the inner lead rod holding cylinder melt and come into contact with the metal foil, the expansion and contraction forces of the metal foil itself applied to the glass member and the inner lead rod holding cylinder by the metal foil are extremely small. No cracks occur in the glass member or the internal lead rod holding cylinder.

Furthermore, since the metal foil has a protrusion, the glass member and the inner lead rod holding cylinder are melted and contacted with the metal foil, and in the subsequent cooling state, the metal foil has a protrusion. Since the expansion force and the contraction force of the metal foil can be absorbed by the metal foil itself, cracks do not occur in the glass member or the inner lead rod holding cylinder. The operation and effect are the same whether the protrusion of the metal foil is directed toward the glass member and the inner lead rod holding cylinder or toward the metal plate.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view showing a main part of a discharge lamp.

FIG. 2 is an explanatory diagram of a metal foil used for a discharge lamp of the present invention.

FIG. 3 is an explanatory diagram of a metal foil used for the discharge lamp of the present invention.

FIG. 4 is an explanatory view showing an example of an internal lead rod holding cylinder.

FIG. 5 is an explanatory vertical sectional front view showing a main part of one embodiment of the discharge lamp of the present invention.

FIG. 6 is an explanatory diagram of a metal foil used for the discharge lamp of the present invention.

FIG. 7 is an explanatory vertical sectional front view showing a configuration of a conventional discharge lamp having a foil seal structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass member 2 Power supply metal foil 3 Metal plate 4 Internal lead rod 5 External lead rod 6 Internal lead rod holding cylinder 7 External lead rod holding cylinder 8 Enclosure 81 Sealing tube part 82 Light emitting space surrounding part 9 Electrode M metal foil M1 metal foil S conductive part for sealing K constricted part

Claims (2)

(57) [Claims] 1. A column-shaped glass member disposed inside a sealing tube portion of a glass envelope, a metal plate disposed on one side of the glass member facing the light emitting space surrounding portion side, and An inner lead rod having an end fixed to the metal plate, a distal end extending into the light emitting space surrounding portion, and an electrode provided at the distal end; an inner periphery of the inner lead rod and a sealing tube portion of the sealing body; A glass inner lead rod holding cylinder disposed between the outer periphery and the outer periphery of the glass member, one end of which is connected to the metal plate, and the other end of which is electrically connected to the external lead rod. In a discharge lamp comprising a metal foil for power supply, which is electrically connected, a metal foil having a thickness smaller than that of the metal plate is disposed between the glass member and the metal plate, and the internal lead rod holding tube made of glass is provided. A power supply metal foil connected to the body and the metal plate ;
A discharge lamp, wherein a metal foil having a thickness smaller than that of the metal plate is arranged between the discharge lamps. 2. The discharge lamp according to claim 1, wherein the metal foil has a protrusion pressed from one side to the other side.