JP2831675B2 - Metal vapor discharge lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a metal vapor discharge lamp using an outer tube made of a translucent ceramic.

(Prior art) A metal vapor discharge lamp such as a high-pressure sodium lamp has been widely used for a long time. Particularly, a metal vapor discharge lamp having a configuration in which a discharge tube is housed in an outer tube made of a transparent ceramic is particularly used. Demand has been growing in recent years. The reason is that translucent ceramics have a higher infrared light transmittance than quartz glass which has been used for the outer tube for a long time, and can be used in various fields. FIG. 2 shows a conventional example of a metal vapor discharge lamp using an outer tube made of such a translucent ceramic.

In the discharge tube (1) in the figure, a metal such as mercury or sodium amalgam or a metal compound such as a metal halide and a starting gas such as Xe are sealed. When a metal vapor discharge lamp is used, first, a voltage is applied between a pair of opposed internal electrodes (2) fixed to both ends in the discharge tube (1) to cause a discharge by the starting gas. Due to the heat generated at this time, a metal vapor is generated from the metal or the metal compound, and a discharge mainly composed of the generated metal vapor occurs to emit light. To operate as described above, the metal vapor discharge lamp is configured as follows.

In the discharge tube (1), both ends of the inner tube (3) are sealed with a pair of internal closing members (4) made of metal. The internal closing member (4) is penetrated by an internal exhaust pipe (5) for the purpose of exhausting the discharge tube (1) and filling a starting gas, etc., and the internal exhaust pipe (5) is connected to the discharge tube (1). ) The outer end is crushed and cut to maintain the airtightness in the discharge tube (1). Further, a pair of opposed internal electrodes (2) are fixed to both ends in the discharge tube (1) as described above. The discharge tube (1) thus configured is housed in an outer tube (6) made of translucent ceramics, and the outer tube (6) is hermetically sealed using the same means as the inner tube (3). Is done. That is, the outer pipe (6) is sealed at both ends with a pair of metal external closing bodies (7) penetrated by the outer exhaust pipe (8), and the outer exhaust pipe (8) is sealed with the outer pipe (6). Crushed at the outer end. The internal exhaust pipe (5) and the external exhaust pipe (8) are both made of metal, and the internal exhaust pipe (5) and the external exhaust pipe (8) are connected by a conductor (9).
The internal electrode (2) and the external electrode (10) are electrically connected. When the translucent ceramic is used for the outer tube as described above, the transmittance of infrared light in the outer tube is good, and because of the excellent heat resistance of the translucent ceramic, the discharge tube and the outer tube that generate high heat can be used. Adhesion becomes possible. Another advantage is that the metal vapor discharge lamp can be miniaturized.

However, in a conventional metal vapor discharge lamp using an outer tube made of a translucent ceramic, the outer tube is sealed with a metal external closing member, and thus has the following problems.
That is, at the time of manufacturing a metal vapor discharge lamp, the joint between the outer tube and the outer blockage body is heated to a high temperature of 800 ° C. or more, joined with a brazing material, and then cooled to room temperature. It is desired that the closure has an approximate value of the coefficient of thermal expansion. If the difference in the thermal expansion coefficient between the outer tube and the external blocker is large, the degree of contraction between the outer tube and the external blocker differs when heated to a temperature of 800 ° C or higher and then cooled to room temperature. This is because a thermal stress is generated in the joint portion and the joint portion is distorted, which causes a decrease in strength against external force such as breakage due to an impact applied during transportation. However, in the conventional example, the translucent ceramics and metal used for the outer tube and the outer closing body are 800
There is a large difference in the coefficient of thermal expansion at a high temperature of not less than ℃. Therefore, for the reasons described above, conventional metal vapor discharge lamps are not sufficiently strong against external force.

Further, in a conventional metal vapor discharge lamp, in a configuration in which an external electrode is provided at an end of the external exhaust pipe outside the outer tube, the pair of external electrodes is located further outside the pair of external closing bodies, so that the length is large in the longitudinal direction. Inevitably, it has been desired to make the longitudinal direction shorter to reduce the size of metal vapor discharge or the like.

(Problems to be Solved by the Invention) As described above, in the conventional metal vapor discharge lamp, there is a problem that the joint between the outer tube and the external closing body is distorted, so that it is weak against external force. Was.

It is an object of the present invention to realize a metal vapor discharge lamp having less distortion as described above and excellent in strength against external force, and at the same time, to make the longitudinal direction shorter than conventional metal vapor discharge lamps and to reduce the size.

[Structure of the Invention] (Means and Action for Solving the Problems) In the metal vapor discharge lamp according to the present invention, an airtightly sealed discharge tube and an outer tube made of a translucent ceramic for housing the discharge tube are provided. A tube, a pair of metal plates electrically connected to a pair of internal electrodes in the discharge tube, respectively, and sealing both ends of the outer tube, and opposite to the outer tube sealing portion of the pair of metal plates And a pair of ceramic materials joined to the pair of metal plates on the side, respectively, and the difference in the coefficient of thermal expansion between the ceramic material and the light-transmitting ceramic is different from that of the metal plate and the light-transmitting ceramic. Is smaller than the difference between the coefficients. That is, when the outer tube and the metal plate are joined, the difference in thermal shrinkage between the two when the temperature drops from the joining temperature to room temperature is reduced by joining the ceramic material to the metal plate, This is to reduce the distortion generated in the image.

As described above, when the ceramic material has a thermal expansion coefficient closer to that of the translucent ceramic used for the outer tube as compared with the metal plate, it is possible to reduce distortion generated at a joint during manufacturing. However, it is also possible to extend the life of the metal vapor discharge lamp. This is because, when a metal vapor discharge lamp is used, distortion generated at the joint between the outer tube and the metal plate due to a rise in temperature at the joint can be reduced, and durability can be improved. Furthermore, the value of the coefficient of thermal expansion of the ceramic material is 0.7 to 1.2 times the value of the coefficient of thermal expansion of the translucent ceramic used for the outer tube, preferably 0.8 to 1.2.
Desirably 1.1 times. That is, when the ceramic material has such a thermal expansion coefficient, the metal vapor discharge lamp according to the present invention exhibits a more remarkable effect.

As the translucent ceramics used for the outer tube, alumina, yttria, aluminum nitride, aluminum oxynitride, and the like can be used. As the ceramic material, a material usable for the outer tube and the metal plate can be used. Are different, but among alumina, magnesia, zirconia, yttria, silicon nitride, silicon carbide, etc.
A material having an appropriate coefficient of thermal expansion may be used as appropriate. Needless to say, a material similar to the translucent ceramic used for the outer tube may be used. Although any metal can be used for the metal plate, a metal having excellent oxidation resistance and nitridation resistance, for example, stainless steel or Kovar (KOVA) can be used.
It is desirable to use an alloy such as R). Further, different materials may be used for the ceramic material and the metal plate on both sides of the outer tube.

The shape of the ceramic material is preferably a disk shape or a ring shape. For joining the outer tube and the metal plate and the metal plate and the ceramic material, a brazing material containing an active metal such as Ti, Zr, or Hf, a fusible frit containing calcium aluminate as a main component, or the like can be used. . In particular, when the joining is performed using a brazing material consisting of a three-component system of Ag-Cu-Ti, among the metal vapor discharge lamps according to the present invention, it is found by the present inventor that outstanding strength is obtained. Has been confirmed.

The metal vapor discharge lamp according to the present invention is desirably applied to, for example, a high-pressure sodium lamp or the like in which a light-transmitting ceramic is usually used in a discharge tube. For example, a mercury lamp or a metal halide lamp in which quartz glass is usually used in a discharge tube It can also be applied to Also, if necessary, it can be applied to mercury lamps and metal halide lamps using translucent ceramics for the discharge tube,
The present invention can be applied to all metal vapor discharge lamps having a double structure accommodated in a discharge tube or an outer tube.

In the metal vapor discharge lamp according to the present invention, the degree of heat shrinkage of the metal plate during manufacturing is adjusted by joining a ceramic material having the above-described characteristics to the outside of the metal plate sealing the outer tube. In addition, since the distortion generated at the joint between the outer tube and the metal plate, which has been a problem in the conventional metal vapor discharge lamp, can be reduced, a metal vapor discharge lamp having excellent strength against external force can be obtained. Further, in the present invention, since the outer peripheral portion of the metal plate sealing the outer tube can be used as an external electrode as it is, the external electrode is located further outside the external closing member sealing the outer tube. Compared to a metal vapor discharge lamp, a metal vapor discharge or the like that has a shorter longitudinal direction and is downsized can be realized.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a side view of a metal vapor discharge or the like according to the present invention. The inner tube (3) is made of translucent alumina and has an inner diameter of 25m.
m, tube length 200 mm. Niobium having a thickness of 0.2 mm is used for the blockage body (4), and a fusible frit mainly composed of Al ₂ O ₃ , CaO, and MgO is used for joining the inner tube (3) and the blockage body (4). Using. Weight% of sodium in inner tube (1)
20 mg of sodium amalgam containing 20% and Xe of starting gas are sealed at 20 Torr. Furthermore, the internal closing body (4) is an internal exhaust pipe (5) made of niobium and having an inner diameter of 6 mm.
Penetrates and an internal electrode (2) made of tungsten is provided at an end of the internal exhaust pipe (5) in the inner pipe (3).
A discharge tube (1) is formed.

The outer tube (6) for accommodating the discharge tube (1) having the above-mentioned structure was formed of high-density polycrystalline alumina having a purity of 99.9% and having a tube inner diameter of 36 mm and a tube length of 300 mm. Both ends of the outer tube (6) are connected to the inner electrode (2) through the conductor (9).
A pair of 1 mm thick metal plates (1
Sealed by 1). The conductor (9) is made of iron plated with nickel, and the metal plate (11) is expressed in weight%.
A Kovar (KOVAR) alloy having a composition of 54Fe-29Ni-17Co was used. As the ceramic material (12) to be bonded to the outside of the metal plate (11), a disk-shaped ceramic plate having a thickness of 5 mm made of 96% pure polycrystalline alumina is used, and the outer tube (6) and the metal plate (11) are used. 70% by weight in the joint between the metal plate (11) and the ceramic material (12).
A foil brazing material having a composition of Ag-27Cu-3Ti was used.

Next, a description will be given of a manufacturing method of the first embodiment configured as described above. First, both ends of the inner pipe (3) are closed with a pair of inner closing bodies (4) through which an inner exhaust pipe (5) is welded through. The mixture was heated and melted at 1550 ° C. for 10 minutes, and both ends of the inner tube (3) were sealed. Further, after sodium amalgam and Xe are sealed from the internal exhaust pipe (5), the end of the internal exhaust pipe (5) outside the inner pipe (3) is air-tightly pressed with a hydraulic cutter at a pressure of 400 kg / cm ^2. Cut. An internal electrode (2) is provided in advance at an end of the internal exhaust pipe (5) in the inner pipe (3). Subsequently, after the discharge tube (1) obtained by the above-described manufacturing method is accommodated in the outer tube (6), the internal electrode (2) and the metal plate (10) are electrically connected using the conductor (9). did. Thereafter, the axial positions of the discharge tube (1) and the outer tube (6) are aligned, and the outer tube (6) is joined to the metal plate (10) at the end of the outer tube (6). Joining with the material (11) was performed simultaneously. For the above-mentioned joining, the above-mentioned brazing material is used, and 5
Heating was performed at 850 ° C. for 10 minutes in a high-frequency furnace in a vacuum of × 10 ⁻⁵ Torr, and then cooled in the furnace.

The metal vapor discharge lamp as shown in FIG. 1 was obtained by the manufacturing method described above.

A durability test was performed on the first embodiment configured as described above according to the following procedure. Ie output 3kw
Producing a plurality of metal vapor discharge lamps according to the first embodiment of,
After lighting for 500 hours, 1000 hours, 3000 hours, and 5000 hours for 3 hours and 30 minutes in the atmosphere at an ambient temperature of 300 ° C for 3 hours,
Amplitude of 2 mm, vibration frequency of 200, equivalent to impact during transportation of vehicles
Vibration was performed at 0 rpm for 60 minutes, and the presence or absence of crack generation in the sealed portion of the outer tube was examined. As a result, it was confirmed that the metal vapor discharge lamp that was lit for each lighting time had no cracks due to vibration, had sufficient strength against external force, and had good durability.

Next, a second embodiment of the present invention was configured as follows. The inner tube, the inner closed body, the inner exhaust tube, the inner electrode, and their joints in the discharge tube and their joints are the same as those in the first embodiment. The metal plate is made of SUS304 having a composition of 74Fe-18Cr-8Ni by weight and ceramics. As the material, a ring-shaped ceramic member having an inner diameter of 36 mm made of 96% pure yttria polycrystal was used. The same high density polycrystalline alumina as in the first embodiment was used for the outer tube, and the same brazing material as in the first embodiment was used for joining the outer tube to the metal plate and the metal plate to the ceramic material. The metal vapor discharge lamp having such a configuration was manufactured by the same manufacturing method as that of the first embodiment, and was used as a second embodiment. When the second example was subjected to the same strength test as the first example, no cracks were generated, and it was confirmed that the second example had sufficient strength against external force and had good durability.

Further, a third embodiment of the present invention was configured as follows. The inner tube, the inner closed body, the inner exhaust tube, the inner electrode, and their joints in the discharge tube and their joints are the same as those in the first embodiment. For the tube, a high-density polycrystalline alumina similar to that of the first embodiment was used, and for the ceramic material, a disc-shaped ceramic plate also made of the same polycrystalline alumina as that of the first embodiment was used. For joining the outer tube to the metal plate and the metal plate to the ceramic material, a fusible frit made of Al ₂ O ₃ , CaO, MgO is used.As a manufacturing method, the fusible frit is used for joining and the joining temperature is set to 1550. A method similar to that of the first example was used except that the temperature was changed to ° C. When a strength test similar to that of the first embodiment was performed on the third embodiment as described above, it was confirmed that no crack was generated, and that the third embodiment had sufficient strength against external force and had good durability. .

Further, in the embodiment according to the present invention described above, the metal plate used for sealing the outer tube can be used as the external electrode as it is, so that the conventional metal vapor as shown in FIG. Compared with the discharge lamp, the longitudinal direction can be made shorter, and a more compact metal vapor discharge lamp has been realized.

[Effects of the Invention] As described in detail above, according to the present invention, in a metal vapor discharge lamp using a translucent ceramic for an outer tube, a metal vapor discharge lamp having sufficient strength against external force is provided. In addition, it is also possible to shorten the longitudinal direction of the metal vapor discharge lamp to make it more compact.

[Brief description of the drawings]

FIG. 1 is a side view of a metal vapor discharge lamp according to the present invention, and FIG. 2 is a side view of a conventional metal vapor discharge lamp. DESCRIPTION OF SYMBOLS 1 ... Discharge tube, 2 ... Internal electrode, 3 ... Inner tube, 4 ... Inner block, 5 ... Inner exhaust tube, 6 ... Outer tube, 7 ... External blocker, 8 ... External exhaust Tube, 9 Conductor, 10 External electrode, 11 Metal plate, 12 Ceramic material

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Atsushi Saita 1-12-1 Funakoshi-cho, Yokosuka City, Kanagawa Prefecture Inside Yokosuka Plant, Toshiba Corporation (56) References JP-A-53-85978 (JP, A) Sho Akai Kai 52-19180 (JP, U) JP 42-27221 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01J 61/30, 61/34, 61/36

Claims (1)

(57) [Claims] 1. An airtightly sealed discharge tube in which discharge by metal vapor is performed, an outer tube made of a translucent ceramic for accommodating the discharge tube, and a pair of internal electrodes in the discharge tube. A pair of metal plates connected to the outer tube and sealing both ends of the outer tube, and a pair of ceramic materials respectively joined to the pair of metal plates on the opposite side of the pair of metal plates from the outer tube sealing portion. Wherein the difference in thermal expansion coefficient between the ceramic material and the translucent ceramic is smaller than the difference in thermal expansion coefficient between the metal plate and the translucent ceramic.