JPS6230283Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a discharge lamp having a double structure in which an arc tube is housed within an outer bulb.

(Prior Art) Generally, in this type of discharge lamp, for example, a high-pressure mercury lamp, a molybdenum foil is attached to the crushing sealing part of the arc tube housed in the outer bulb, and a main electrode and an auxiliary electrode are bonded to the molybdenum foil. It is constructed by sealing the electrode and external conductor, and the tip of each external conductor is
It is led out from the end face of the sealing part. Since the main electrode and the auxiliary electrode are sealed adjacent to each other in at least one of the sealed portions, the external conductive wires connected thereto are also led out adjacent to the end surface of the sealed portion.

(Problem to be solved by the invention) By the way, when forming such a sealing part, the end part of the arc tube bulb is heated and softened, and the main electrode, auxiliary electrode, molybdenum foil, and each other are placed inside the end part in advance. The structure connected to the external conductor is positioned to crush the softened portion, but during such sealing, the end of the bulb is heated to 1,400 to 1,600 degrees Celsius, and when crushed, it is exposed to the heat. Therefore, the external conducting wire itself is also heated to a high temperature, and a conductive metal oxide such as MoO ₃ may be formed on the peripheral surface of the lead-out portion of the external conducting wire. When such an arc tube is placed inside the outer bulb and lit, the temperature of the wall of the arc tube reaches several hundred degrees Celsius, so the external conductor is similarly heated to a high temperature, and this heat causes the outer conductor to form. The metal oxide that has been removed is scattered, and the scattered metal oxide mainly adheres to the end face of the crush sealing portion. In this case, if two external conductors connected to the main electrode and the auxiliary electrode are led out from the sealing part, the metal oxide will adhere to the end face of the sealing part located between these two external conductors. The external conductors are short-circuited, and therefore, even if voltage is applied to both external conductors when starting the lamp, glow discharge is difficult to occur between the main electrode and the auxiliary electrode, resulting in problems such as poor starting performance of the lamp. It was hot.

Therefore, in the past, grooves were formed on the end face of the crush sealing part so as to cross between the external conductors to prevent the metal oxide from continuously adhering between the external conductors, or to complete the sealing. Means such as sandblasting or the like is applied to the lead-out portion of the external conductor wire to remove metal oxides has been adopted. However, these conventional means do not ensure short circuit prevention between both external conductors, and it is difficult to remove metal oxides.
The lamp does not start properly, requires special machining, and the work process is complicated, resulting in poor manufacturing efficiency.
There were drawbacks such as increased costs.

The present invention was developed based on the above circumstances, and its purpose is to reliably prevent the scattering of the metal oxide formed on the circumferential surface of the external conductor, thereby further improving the starting performance of the lamp. It is an object of the present invention to provide a discharge lamp that can improve manufacturing efficiency with a simple configuration.

(Means for Solving the Problems) In the present invention, at least one of the plurality of adjacent external conductors led out from the crushing sealing part is connected so that one end thereof is brought into close contact with the end face of the crushing sealing part. It is characterized by being covered with a covering material.

(Function) According to the present invention, even if metal oxide is formed on the external conductor during the crush sealing process, since it is covered with the covering material, the metal oxide is prevented from scattering during lighting. Since it becomes difficult to adhere to the end face of the crush sealing part, short circuits are prevented.

(Example) The present invention will be described below based on an example shown in the drawings. FIG. 1 shows a high-pressure mercury lamp, and 1 is an outer bulb made of hard glass. The neck portion of the outer bulb 1 is covered with a cap 2, and the inside is filled with vacuum or inert gas. A support 4 which also serves as a power supply line is attached to the stem 3 of the outer bulb 1 along the tube axis direction, and an arc tube 5 is supported on this support 4. That is, the arc tube 5 includes an arc tube bulb 6 molded from quartz glass, and both ends of the arc tube bulb 6 are crushed and sealed. Supported by. Molybdenum foils 9a, 9b and 10 are sealed in the sealing parts 7a and 7b. The molybdenum foils 9a, 9b have main electrodes 11a,
11b is connected, and the remaining molybdenum foil 10 is connected to an auxiliary starting electrode 12, and each of these molybdenum foils 9a, 9b and 10 is connected to external conductors 12a, 12b and 13. And the external conductor 13 is the auxiliary resistor 1
4, and the external conductor 12a is connected to the base 2 through a conductive wire 15.
is connected to the eyelet terminal 2a. Also,
The external conductor 12b is connected to the support 4 via the conductive wire 16.
is connected to the top of the diagram. Such a support 4 is connected to the base 2 via a support line 17 that also serves as a power supply line.
is connected to.

Therefore, the two external conductive wires 12a, 13 which are led out adjacently to one of the sealing portions 7a are connected to the lead-out portions 18, 19 of the luminous bulb bulb 6. Covering materials 21, 21 are provided to cover the metal oxide 20 made of MoO ₃ formed when sealing the portion 7a. This covering material 2
1 and 21 are made of a cylindrical metal material such as nickel, nickel-copper alloy, or stainless steel, and are fitted into the lead-out portions 18 and 19. And covering material 2
1 and 21 are in close contact with the end surface of the sealing part 7a, and the other end surface is in contact with the external conductor 12.
It is welded to a and 13 and fixed so that it cannot be removed. This fixation prevents the metal oxide 20 formed on the lead-out portions 18 and 19 from being exposed on the sealing portion 7a side.

Note that a predetermined amount of mercury and an inert gas are sealed in the arc tube bulb 6.

According to one embodiment of the present invention configured as described above, the lead-out portions 1 of the external conductors 12a, 13
8 and 19 are covered with covering materials 21 and 21,
In particular, the insertion side end surfaces of the covering materials 21, 21 are sealed at the sealing portion 7a.
Since it is in close contact with the end surface of the lead-out portion 18,1
The metal oxide 20 on the surface of the lamp 9 is not exposed, and therefore the oxide 20 can be reliably prevented from scattering due to heat generated by lighting the lamp. Therefore, the external conductors 12a and 13 are prevented from being short-circuited by the metal oxide 20, and a glow discharge reliably occurs between the main electrode 11a and the auxiliary electrode 12, which improves the starting performance of the lamp. improves.

Moreover, the external conductor 1 led out from the sealing part 7a
2a, 13, and then welding the sheathing materials 21, 21 to the external conductors 12a, 13. Installation is completed by simply inserting the sheathing materials 21, 21 into the external conductors 12a, 13. External conductor 12a, 1
It is possible to eliminate the need for special machining such as forming grooves across the three spaces. Therefore,
Manufacturing efficiency is improved, making it suitable for mass production, and manufacturing costs can be reduced.

Further, the covering materials 21, 21 are arranged such that the end surfaces of the outer conductors 12a, 1 are in contact with the end surfaces of the sealing portion 7a.
3, the strength of this portion is increased, and cracks and leaks between the sealing portion 7a and the external conductive wires 12a, 13 can be suppressed.

Characteristic curve A showing how the starting voltage changes with respect to the lighting time of the lamp, which is shown by the lamp according to the present invention.
FIG. 5 shows the results of a comparison between the curve B and the characteristic curve B shown by a conventional lamp with the metal oxide film left exposed. As is clear from Fig. 5, the starting voltage shown by curve A increases by only about 10% even if the lighting time increases and is almost the same as the initial value, but the starting voltage shown by curve B increases by about 2000. The starting voltage increases rapidly after the lighting time, and requires approximately twice the starting voltage shown by curve A above. That is, this indicates that the metal oxide film adhering to the lead-out portion is scattered due to heat generated by lighting the lamp, causing a short circuit between the external conductors.

In the above embodiment, the covering material is formed of a cylindrical metal material, but the present invention is not limited to this, and the outer conductor is coated with an insulating metal oxide such as alumina on the peripheral surface of the lead-out part. The covering material may be integrally formed by applying an object. Further, the covering material is not limited to a metal material, but may be formed from an insulating material such as a heat-resistant glass material, and in this case, it may be fitted into the lead-out portion of at least one of the external conductors. In other words, the creepage distance between the lead-out parts of the external conductor becomes longer due to the insertion of this covering material.
The rate of mutual short-circuiting is reduced. Furthermore, although the above embodiments have been explained using a high-pressure mercury lamp as an example, it goes without saying that the present invention can be similarly implemented using other discharge lamps such as metal halide lamps.

(Effects of the Invention) As explained above, in the present invention, at least one of the lead-out parts of a plurality of adjacent external conductors led out from the crushing sealing part of the arc tube bulb is covered with a covering material. Therefore, when the external conductor is sealed in the sealing part, the proportion of the metal oxide formed on the peripheral surface of the external conductor is coated and exposed is reduced, and this oxide is prevented from being exposed due to heat generated by lighting the lamp, etc. In addition, since the creepage distance between the external conductors becomes longer, the rate of short-circuiting between the external conductors is reduced. Therefore, the adjacent external conductive wires are not electrically connected to each other outside the sealing portion, and glow discharge occurs reliably, thereby improving the startability of the lamp. Moreover, since the above-mentioned covering material can be attached by a simple operation, there is no need for special machining such as forming a groove on the end face of the sealing part so as to cross between the external lead-in wires as in the conventional case. Therefore, manufacturing efficiency is improved, which is convenient for mass production, and has excellent practical effects such as being able to reduce manufacturing costs.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a partially cutaway front view of a high-pressure mercury lamp, Fig. 2 is a front view showing one crushed sealing part of the arc tube, and Fig. 3 is the same part. FIG. 4 is an enlarged sectional view of the middle part of FIG. 2, and FIG. 5 is a characteristic diagram showing changes in the starting voltage of the lamp. 5...Bulb (luminous tube), 7a, 7b...Crushing sealing part, 12a, 13...External conductor, 18, 19
. . . Derivation portion, 21 . . . Covering material.

Claims (1)

[Scope of utility model registration request] In a discharge lamp that has a double-tube structure in which an arc tube is housed within an outer bulb, and the outer bulb is filled with vacuum or inert gas, the adjacent light emitted from the crushed sealing part of the arc tube bulb is A discharge lamp characterized in that a lead-out portion of at least one of a plurality of external conductive wires is covered with a covering material whose one end side is brought into close contact with the end face of the crush sealing portion.