JP2001338615A - Discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of cracks at a sealing part or deterioration of lamp characteristics with a discharge lamp with a ceramic tube used as a light-emitting tube, without giving rise to an increase of a size of the tube or a hike of cost of materials for the tube. SOLUTION: A heat dissipation member is provided at both ends of a light- emitting tube. Further, the heat dissipation member is arranged at a sealing part, and connected with a support frame to fix the light-emitting tube with the heat dissipation member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp using a ceramic tube.

[0002]

2. Description of the Related Art In recent years, a metal halide lamp using a translucent alumina tube, which is one of ceramic tubes, as an arc tube in which a metal halide is sealed has been used.
It is commercialized with the following.

[0003] The advantage of using an alumina tube as the arc tube of a metal halide lamp is that it is scientifically and thermally stable with respect to a metal halide as an enclosure, as compared with a quartz glass tube generally used in a conventional metal halide lamp. Because of this, it is possible to suppress a decrease in lamp life, which has been caused by a chemical reaction between the enclosure and quartz glass, and to expect an improvement in life characteristics. This means that it is possible to design a lamp with high efficiency and to use an arc tube made of quartz glass, which has a high reactivity and can be filled with an alkali metal, which could not be filled practically.

When a ceramic tube is used as an arc tube, its sealing is connected to an electrode core 4 as shown in FIG.
A structure in which an end disk in which the molybdenum wire 3 and the niobium wire 1 are connected by welding or the like is used as an electric introducing body, and this is sealed and fixed to an arc tube 5 by a glass frit 2, FIG.
As shown in FIG. 1, the structure using an electrode core 4 connected to a conductive cermet end disk 6 as an electric conductor is employed. In addition, as the glass frit used here, for example, those containing alumina, silicon oxide, dysprosium oxide as a main component,
A material containing alumina and calcium oxide as main components is used.

[0005] Such a metal halide lamp is shown in FIG.
The wires 10 and the plate 7 made of a material such as nickel are connected to the electric guides at both ends of the arc tube 8 as shown in FIG. 1, and these are connected to the outer ball frame 13 and the like, and the arc tube 8 is fixed in the outer ball 9. It has the structure which was done.

[0006]

When a medium-to-high wattage lamp larger than 150 W is manufactured with the above-mentioned conventional structure, a low-wattage lamp of 150 W or less does not produce a lamp at the arc tube sealing portion. It was found that problems such as generation of cracks and deterioration of lamp characteristics occurred. This is considered to be due to the fact that the heat generated during the operation of the lamp is larger than that of the low wattage lamp, so that the temperature of the sealing portion becomes higher. The frit reacts chemically with the enclosure,
It is considered that this causes deterioration of lamp characteristics.

Therefore, as means for lowering the temperature of the sealing portion so as not to cause such a problem, a method of moving the sealing portion away from the arc discharge region and a method of increasing the heat capacity by increasing the thickness of the arc tube. And so on.

However, when such a method is used, new problems such as an increase in the size of the arc tube and an increase in the material cost of the arc tube occur.

In view of the above, the present invention provides a discharge lamp using a ceramic tube as an arc tube, without increasing the size of the arc tube and the cost of the arc tube material even when the output of the discharge lamp is increased. It is another object of the present invention to provide a discharge lamp structure that does not cause cracks in the sealing portion and deterioration of lamp characteristics as described above.

[0010]

In the discharge lamp of the present invention, at least a metal halide, mercury and an inert gas are sealed in a ceramic tube, and both ends of the ceramic tube are sealed in a gap between the ceramic tube and a conductive wire. A discharge lamp in which an arc tube having a sealing portion filled with a material is incorporated in an outer sphere by a support frame, wherein heat radiation members are provided at both ends of the arc tube. .

By providing the heat radiating members at both ends of the arc tube, the heat at both ends of the arc tube is radiated through the heat radiating members, and the temperature rise of the sealing portion is suppressed. The heat radiation from the heat radiation member may be conducted by heat conduction or heat radiation, and the material of the heat radiation member is appropriately selected according to the heat radiation method.

In particular, when heat from both ends of the arc tube is transmitted to the heat radiating member by heat conduction and the heat is radiated from the heat radiating member, a heat radiating member made of a metal plate or a metal wire is attached to the end of the arc tube. It is preferable that the ceramic tube be brought into close contact by a method such as tight contact and winding. In this case, it is preferable to use a material having a coefficient of thermal expansion as close as possible to the coefficient of thermal expansion of the ceramic tube.

When the heat radiating member is mounted, the mounting position is set at the position for suppressing the temperature rise of the sealing portion.
It is preferable that the end of the arc tube is located at or near the sealing portion, and it is particularly preferable that the end portion be attached to the sealing portion. Thus, in order to effectively radiate the heat of the sealing portion, it is preferable that the heat radiating member is provided on the sealing portion filled with the sealing material.

In the case where heat is radiated from the heat radiating member by heat conduction, it is preferable to connect the heat radiating member to a support frame of the light emitting tube which also serves to supply power to the light emitting tube. The heat is dissipated outside the discharge lamp.

Further, a heat radiation member is attached to the end of the arc tube,
It is preferable to connect the heat radiating member to the support frame so that the arc tube is fixed to the support frame by the heat radiating member. By doing so, it is possible to increase the vibration resistance of the arc tube end. In particular, such a fixing structure is suitable as a fixing structure for an arc tube having a structure in which the arc tube has a small diameter portion at both ends and a sealing portion is provided in the small diameter portion. With respect to the vibration, the damage at the small diameter portion, particularly at the root of the small diameter portion is suppressed. In this case, the heat dissipating member is attached to the small-diameter portion which is the end of the arc tube, and it is necessary to fix the heat dissipating member. To increase.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. FIG. 1 is a schematic diagram of a discharge lamp according to a first embodiment of the present invention. The main body of the arc tube 8 is made of a translucent alumina tube, the maximum outer diameter of the central portion is 18 mm, and the outer diameter of the narrow tube portion at both ends is 4 mm. The length of the central portion is 30 mm and the length of the thin tube is 15 mm. In the arc tube 8, dysprosium iodide, holmium iodide, and thulium iodide are contained in a total of 1 as an enclosure.
2 mg, thallium iodide 2 mg, sodium iodide 2 mg,
14 mg of mercury and 13.3 kPa of argon gas are sealed. A niobium wire having a wire diameter of 0.75 mm for supplying power to two electrodes is connected to both ends of the arc tube 8. A gap between the small diameter portion of the alumina tube and the niobium wire is melt-filled with a sealing material made of a glass frit containing alumina, silicon oxide, and dysprosium oxide as main components. A niobium plate 11 having a width of 2 mm and a thickness of 0.2 mm is tightly wound around the sealing portions at both ends of the arc tube 8, and the niobium plate 11 is fixed to a support frame 13 of an outer sphere. The atmosphere in the outer sphere 9 can be replaced with a rare gas such as nitrogen, but in this embodiment, the atmosphere is evacuated.

During the operation of the lamp, the heat generated by the arc discharge is conducted from the electrode core and at the same time, is conducted from the tube wall of the arc tube to increase the temperature of the sealing portion. In the case of the assembling method according to the present invention, the heat conducted to the sealing portion is conducted to the outer bulb frame through the metal plate wound around the sealing portion. Therefore, an increase in the temperature of the sealing portion is suppressed, and cracks in the sealing portion due to thermal stress can be prevented. The temperature of the sealing portion can be controlled by the material, width, and thickness of the metal plate, so that the optimum temperature of the sealing portion can be obtained by arbitrarily adjusting the metal plate by the power of the lamp. FIG. 2 is a schematic diagram of a discharge lamp according to a second embodiment of the present invention. In this embodiment, the length of the thin tube portion of the arc tube 8 is different, and one of them is 10 m.
m and the other is 15 mm. A niobium plate 11 'having a width of 3 mm and a thickness of 0.2 mm is provided on a sealing portion having a thin tube portion length of 10 mm.
However, the sealing portion having a capillary portion length of 15 mm has a width of 2 mm and a thickness of 0.3 mm.
The 2 mm niobium plates 11 are wound closely together and fixed to the outer spherical frame 13. The rest is the same as the first embodiment. In this way, when the capillary section length is different on the left and right,
By changing the size of the metal plate wound around the sealing portion, the left and right sealing portion temperatures can be made substantially equal. This method is effective for reducing the size of the lamp.

A lighting test was performed on the lamp thus manufactured at a rated power of 400 W. As a result, it was possible to stably light even after 6000 hours had elapsed, and no abnormality such as crack was observed in the sealing portion. Further, the lamp luminous flux was 80% or more of the initial value, and it was determined from this that no chemical reaction between the filler and the brazing material had occurred.

In the first and second embodiments,
By connecting the heat radiating member to the support frame, the luminous tube is fixed to the support frame by the heat radiating member,
The vibration intensity at the end of the arc tube was increased, and the damage at the root of the small-diameter portion was smaller than that of the conventional one due to the vibration of the discharge lamp.

FIG. 3 is a schematic diagram of a discharge lamp according to a third embodiment of the present invention. The lamp of the present embodiment differs from the lamp of the first embodiment in that the niobium plate 12, which is a heat radiation member, is not fixed to the support frame. In the case of this embodiment, the niobium plate 12
Dissipation of heat from is mainly done by radiation. In the above embodiment, a niobium plate is used as a heat radiating member provided at both ends of the arc tube, but as a material thereof, niobium or tantalum having a thermal expansion coefficient similar to that of a ceramic arc tube such as an alumina tube is most preferable. However, other materials can be used. For example, nickel, molybdenum, tungsten, and stainless steel are suitable as other materials. In addition, various shapes and forms can be used for the shape and form.

In the above-described embodiment, the ceramic tube is made of alumina. However, other materials such as aluminum nitride and yttrium oxide can be used. Also, as the sealing material, various materials such as ceramic frit can be used in addition to the glass frit.

[0022]

According to the present invention, the provision of the heat radiating member can lower the temperature of the sealing portion, thereby suppressing the occurrence of cracks in the sealing portion and the chemical reaction between the filling and the glass frit. As a result, deterioration of the lamp characteristics does not occur, and the output of the discharge lamp is increased to increase the output power.
Even in the case of a high wattage discharge lamp, it is possible to manufacture the discharge lamp at low cost without increasing the size of the arc tube or the cost of the arc tube material.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a discharge lamp according to a first embodiment.

FIG. 2 is a schematic diagram of a discharge lamp according to a second embodiment.

FIG. 3 is a schematic diagram of a discharge lamp according to a third embodiment.

FIG. 4 is a diagram showing a sealing structure of an arc tube.

FIG. 5 is a diagram showing a sealing structure of an arc tube.

FIG. 6 is a schematic diagram of a conventional discharge lamp.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 niobium wire 2 glass frit 3 molybdenum wire 4 electrode core 5 arc tube 6 cermet end disk 8 arc tube 9 outer sphere 11, 11 ', 12 niobium plate

Claims (3)

[Claims] 1. A light emitting device having at least a metal halide, mercury and an inert gas sealed inside a ceramic tube, and a sealing portion at both ends of the ceramic tube filled with a sealing material in a gap between the ceramic tube and a conductive line. What is claimed is: 1. A discharge lamp comprising a tube incorporated in an outer sphere by a support frame, wherein a discharge member is provided at both ends of the arc tube. 2. The discharge lamp according to claim 1, wherein the heat radiating member is provided in the sealing portion. 3. The discharge lamp according to claim 1, wherein the heat radiation member is connected to the support frame, and the arc tube is fixed to the support frame by the heat radiation member.