JPH05325891A - High pressure discharge lamp - Google Patents

Abstract

PURPOSE:To maintain a stable discharge for a long period by composing a discharge side electrode and a sealing part side electrode with different materials, and sealing an electrode in which the above electrodes are engaged and connected in a bulb. CONSTITUTION:In an electrode 1 used for a high pressure xenon lamp (a), for example, a discharge side electrode 2 is composed of a tangsten including sodium, it is composed of a cylindrical electrode whose tip is cut in a conical form, and a screw hole 21 is provided on the lower surface. And a sealing side electrode rod 3 is made of tangsten, and a screw 32 threaded at the tip is engaged to the screw hole 21 of the above electrode 2. In an electrode 1 used in a metal haloid lamp (b), a discharge side electrode 2 is composed of tangsten or a tangsten including sodium, and a screw 22 is formed at the lower end. And a sealing part side electrode 3 is composed of rhenium or a tangsten containing rhenium, and the above screw 22 is engaged to a screw hole 31 set at the end face, and a coil 4 which consists of a tangsten wire is wound around the electrodes 2 and 3. By composing in such a way, the contact resistance is not increased even though a flashing is repeated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode of a high-pressure discharge lamp used for lighting in parks, sports facilities, etc., and for photochemistry.

[0002]

2. Description of the Related Art There are various types of electrodes 1 for a high pressure discharge lamp. Among these, there is one in which an electrode rod is welded as an internal conductor to a metal foil such as molybdenum sealed in the sealing portion, and the discharge side electrode is connected to the tip side of this electrode rod.

The connection is as follows: (1) As shown in FIG. 4 (a), a refractory metal such as tungsten or tungsten containing thorium, or powder of tungsten, tungsten containing thorium, tantalum, etc. and thorium oxide, zirconium oxide, aluminum oxide, oxidation. A metal oxide powder such as yttrium is mixed, pressure-molded and then sintered to form a porous columnar discharge-side electrode 2 for impregnating an electron emitting substance.
Then, the electrode rod 3 also made of tungsten or tungsten containing thorium is inserted into the hole 22 provided at the center of the discharge side electrode 2.

(2) Further, in a metal halide lamp containing a metal halide, the tip of the discharge side electrode has a high temperature, but the temperature of the electrode rod near the sealing portion is lower than that of the tip. It is known that a portion is etched by halogen to become thin and the electrode rod is broken. As a countermeasure against this, as shown in FIG. 4 (b), the electrode rod 3 near the sealing portion is made of a material such as rhenium or tungsten containing rhenium, which is hard to be etched by halogen, and the electrode 2 on the discharge side is made of tungsten or tungsten containing thorium. These materials are inserted into a coil 4 around which a tungsten wire carrying an emitter is wound and integrated, and mechanically and electrically bonded.

(3) Further, as a coil similar to the above-mentioned coil, a sleeve is used in place of the coil to integrate them, and mechanical and electrical joining is performed.

However, in the electrodes having these structures, in the case of the former sintered electrode (1), there is a difference in the coefficient of thermal expansion due to the materials of the discharge side electrode and the electrode rod being different, and the latter (2) ) And (3) in the case of the coil or sleeve connection electrode, in addition to the difference in the coefficient of thermal expansion due to the material difference between the discharge side electrode and the electrode rod and the coil or sleeve, the coil may be wound in the winding or axial direction. Expansion and contraction occurs.

For this reason, the connecting portion of the electrode that rises in temperature when the discharge lamp is lit loosens, the contact resistance in this portion increases, heat is generated, and the electrode becomes abnormally hot, which not only promotes loosening. However, there are problems such as a significant deterioration in the lamp characteristics, and the brightness of the discharge lamp is reduced early due to the occurrence of bulb blackening due to electrode spattering, especially in the case of a high output discharge lamp with a lamp current of 10A or more. The occurrence was remarkable.

[0008]

The problem to be solved by the present invention is that in the electrode in which the discharge side and the sealing part side are integrally connected, the connection part of the electrode whose temperature is raised by lighting the discharge lamp is In some cases, loosening occurred, contact resistance increased, and the desired lamp characteristics were not obtained, or in extreme cases, the electrode on the discharge side fell off.

It is an object of the present invention to provide a high pressure discharge lamp which can maintain stable discharge for a long period of time by using an electrode in which the discharge side electrode and the sealing part side electrode are mechanically and firmly connected.

[0010]

In the high pressure discharge lamp according to claim 1 of the present invention, the discharge side and the sealing part side are made of different materials, and electrodes which are engaged and connected to each other are sealed in a bulb. It is characterized by In the high pressure discharge lamp according to claim 2 of the present invention, mercury, a metal halide and a starting gas are enclosed in a quartz glass bulb, and the discharge side is tungsten or thorium-containing tungsten, and the sealing side is rhenium or rhenium-containing tungsten. It is characterized in that the electrodes made of the above material and having both engaged and connected are sealed. A high pressure discharge lamp according to a third aspect of the present invention is characterized in that the engaging means is a screw connection.

A high pressure discharge lamp according to a third aspect of the present invention is characterized in that the engaging means is a fitting connection.

[0012]

[Function] Since the connection between the discharge side electrode and the sealing side electrode is screwed or fitted, it does not come out and separate due to a mere temperature change, and it is mechanically and electrically long-term. It is possible to provide a high-pressure discharge lamp that can maintain a stable connection throughout.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an electrode for a high-pressure discharge lamp according to the present invention, and FIG. 2 shows a high-pressure discharge lamp in which this electrode is sealed. In the figure, the same parts as those in FIG.

FIG. 1 (a) shows an electrode 1 used in, for example, a high-pressure xenon lamp. The discharge-side electrode 2 is formed of thorium-containing tungsten and has a conical shape with its tip cut into a conical shape. It is provided. Further, the sealing portion side electrode rod 3 is made of tungsten, and the screw portion 32 engraved at the tip is screwed into the screw hole 21 of the discharge side electrode 2 to form the electrode 1.

FIG. 1 (b) shows an electrode 1 used for a metal halide lamp, for example. The discharge side electrode 2 is made of tungsten or tungsten containing thorium, and a screw portion 22 is formed at the lower end. In addition, the sealing portion side electrode 3
Is made of rhenium, tungsten containing rhenium, or the like having a diameter substantially the same as that of the discharge-side electrode 2, and the screw portion 22 is screwed into a screw hole 31 formed in the end face thereof to form the electrode 1. A coil 4 made of a tungsten wire or the like is wound around the discharge side electrode 2 and the sealing part side electrode 3 including the screwed part, and the coil 4 and the discharge side electrode 2 and the sealing part side. An electron emitting substance is filled in a gap around the electrode 3 and a pitch between the coils 4. 1 (a),
The electrode 1 configured as shown in (b) is loosened between the discharge side electrode 2 and the sealing part side electrode 3 even if a thermal shock is given by repeatedly blinking the lamp after sealing the discharge lamp. No obstacles occurred.

Next, a specific example in which the electrode 1 shown in FIG. 1 (b) is applied to a metal halide lamp will be described with reference to FIG. The discharge side electrode 2 made of thorium-containing tungsten has a length of about 10 mm, a wire diameter of about 2.5 mm, a screw portion length of about 4 mm, a screw portion wire diameter of about 1.5 mm, and a sealing portion side made of rhenium. The electrode 3 has a length of about 15 mm, a wire diameter of about 2.5 mm, a screw hole depth of about 4 mm, and a screw hole diameter of about 1.5 mm. Is fixed by screwing, and a tungsten wire having a wire diameter of about 1 mm is wound around each of the electrodes 2 and 3 for about 5 turns to form the electrode 1.

Then, after a molybdenum foil 5 is connected to the sealing portion side electrode 3 of the electrode 1 by a usual method, the electrode 1 is formed into a substantially elliptical shape having a maximum tube diameter of about 36 mm and a maximum tube length of about 52 mm. The quartz glass bulb 6 is sealed at both end sealing portions 7.

Then, after exhausting the inside of the glass bulb 6,
DyBr3 3mg, TmBr3 3mg, HoBr3 3m
A lamp L having a rated output of 2 kW was manufactured by sealing the exhaust pipe 8 with g, HgBr2 8 mg, Hg 70 mg and starting argon gas 200 torr.

The 10 metal halide lamps thus manufactured were blinked (5.5 hours for turning on and 0.5 hours for turning off) at 2.4 kW, which is 20% higher than the rating, and tested for 0 hours, 100 hours and 300 hours. The electrode temperature, the electric characteristics of the lamp, and the brightness of the lamp after 500 hours and 1000 hours were measured.

As a result, in each lamp, not only the temperature of the electrode but also the change of the lamp electric characteristic and the brightness are compared with that of the lamp voltage after 1000 hours when the lamp voltage is 3 V on average.
The rise and the brightness of the lamp decreased by 5% on average, which was within the range of increase and decrease during normal lighting, and no abnormalities were observed. In addition, the discharge side electrode did not fall off, and the sealed part side electrode was not etched and narrowed by the enclosed bromide.

The results were the same even when the output of the lamp, the shape of the bulb, the composition and amount of the filling material, the lighting direction, the lighting conditions and the like were changed.

FIG. 3 shows another embodiment, which is an electrode 1 in which the connecting means between the discharge side electrode 2 and the sealing part side electrode 3 is fitted and connected. In FIG. 3 (a), the tip of the sealing part side electrode 3 is formed as a tapered fitting protrusion 33 having a larger diameter than the other part, and the corresponding lower surface side of the discharge side electrode 2 goes inward. A fitting hole 23 having a large diameter is formed. The connection between the two is made by press-fitting a large-diameter fitting projection 33 into the fitting hole 23, and once inserted, the large-diameter portion is locked in the fitting hole 23 and does not come off.

In FIG. 3B, a fitting projection 33 having a smaller diameter than the other portion is provided at the tip of the sealing portion side electrode 3, and the above fitting is provided on the lower surface side of the discharge side electrode 2 corresponding thereto. A fitting hole 23 having a diameter smaller than that of the abutment portion 33 is formed. The connection of both is a fitting hole 23.
It is made by press-fitting a large-diameter fitting protrusion 33 into the coil. Further, a tungsten wire is wound around the coil 4 at this connection.
Since both are wound, both electrodes 2 and 3 will not come out.

In the case of the embodiment of FIG. 3, both electrodes could be firmly connected as in the case of FIG.

The present invention is not limited to the above embodiment. For example, the types of high-pressure discharge lamps are not limited to metal halide lamps and high-pressure xenon lamps, but can be widely applied to other types of discharge lamps such as ultra-high-pressure discharge lamps and high-pressure mercury lamps.

Further, the formation of the engaging portion such as the screw portion and the screw hole to be screwed is not limited to one of the discharge side electrode and the sealing portion side electrode. Further, the electrode material is not limited to the one described in the embodiment, and a material having a good electron emission property on the discharge side and a material inexpensive on the sealing part side that is not easily attacked by the substance enclosed in the valve or an inexpensive material may be appropriately selected. ..

[0027]

As described above in detail, according to the present invention, 2
When the individual members are connected to form the electrode member, the connection means is an engagement connection such as screwing or fitting, so that the fixation is firm and reliable, and even if thermal stress is applied to the electrode when the discharge lamp blinks. It is possible to provide a high-pressure discharge lamp with stable characteristics, in which the connection between the two does not loosen, overheating due to poor contact at the connection part does not occur, and the electrode members do not fall off.

[Brief description of drawings]

FIG. 1 is a partially sectional front view showing an embodiment of a discharge lamp electrode of the present invention.

FIG. 2 is a sectional front view showing an embodiment of the high pressure discharge lamp of the present invention.

FIG. 3 is a partial sectional front view showing another embodiment of the discharge lamp electrode of the present invention.

FIG. 4 is a partial sectional front view showing an example of a conventional discharge lamp electrode.

[Explanation of symbols]

 L lamp 1 electrode 2 discharge side electrode 21 screw hole 22 screw part 23 fitting hole 3 sealing part side electrode 31 screw hole 32 screw part 33 fitting protrusion 4 coil 6 glass bulb 7 sealing part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Ito 1-4-2 Mita, Minato-ku, Tokyo Toshiba Lighting & Technology Corporation

Claims (4)

[Claims] 1. A high-pressure discharge lamp, characterized in that the discharge side and the sealing part side are made of different materials, and electrodes in which the two are engaged and connected are sealed in a bulb. 2. A quartz glass bulb is filled with mercury, a metal halide and a starting gas, and the discharge side is made of tungsten or tungsten containing thorium, and the sealing side is made of rhenium or tungsten containing rhenium, and both are engaged. A high-pressure discharge lamp characterized in that the connected electrodes are sealed. 3. The high pressure discharge lamp according to claim 1, wherein the engaging means is a threaded connection. 4. The high pressure discharge lamp according to claim 1, wherein the engaging means is a fitting connection.