JPS6213792B1 - - Google Patents

Description

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an example of the configuration of the discharge lamp of the present invention, and FIG. 2 is a longitudinal cross-sectional view showing an example of the detailed configuration of the airtight sealing portion between the container and the power supply member.
FIG. 3 is a longitudinal sectional view showing another example of the structure of the airtight sealing part, and FIG. 4 is a longitudinal sectional view showing an example of the assembly of the power supply member and the lid body used in the assembly of the discharge lamp of the present invention. FIG. 5 is a longitudinal cross-sectional view showing an example of a manufacturing apparatus for manufacturing the hermetic sealing portion, and FIG. 6 is a partially cutaway front view showing another example of the configuration of the discharge lamp of the present invention.

[Detailed description of the invention]

The present invention relates to a gas discharge lamp in which a discharge space is constituted by a container made of densely sintered translucent alumina. In general, the tube wall of a gas discharge lamp must be constructed of a material that can withstand the chemical action of the discharge medium gas at its operating temperature until the end of the lamp's lifetime, e.g. 700～
Materials such as ordinary glass or quartz glass cannot be used when the operating temperature is high and the discharge medium gas has an aggressive composition, such as in high-pressure sodium discharge lamps at 1500°C. . In fact, these materials are severely eroded and discolored during operation, which not only obstructs the transmission of discharge luminescence, but also reduces the mechanical durability of the discharge lamp vessel due to the erosion, making it difficult to use discharge lamps. Increased risk of rupture. In order to eliminate these drawbacks as much as possible, it is known to use densely sintered translucent alumina in the discharge lamp vessel, but this alumina is made of at least 95% by weight alumina oxide. , is understood to be a mixture of the main component aluminum oxide and a temporary binder, shaped by means customary in ceramic technology, and sintered at extremely high temperatures. This alumina is advantageous for use not only in high-pressure sodium vapor discharge lamps, but also in high-pressure mercury vapor discharge lamps, especially those containing iodine or iodide in the discharge space; in fact, this material It has stronger resistance to the corrosive action of the gas atmosphere than quartz glass, which has conventionally been widely used in this type of discharge lamp. Only a few metal materials, such as tungsten, molybdenum, or niobium, can be used as the electrodes and power supply members to be hermetically sealed in the discharge lamp vessel as described above. Since the coefficient of expansion closely matches that of , it is extremely suitable for use as a power supply member that penetrates the discharge lamp container. However, even when a suitable metal material is selected for the power supply member, the fabrication of the hermetic seal remains an extremely difficult task, especially when using niobium. The main reason for this is that the melting point of alumina is extremely high, over 1925℃, and
This is because alumina does not have the same softening temperature range as ordinary glass or quartz glass. Therefore, various structures have been considered for airtight sealing parts having this problem. One of the conventional methods of improving the hermetic seal is
Although there is use of hollow tubular feed members, and in fact hollow tubular feed members are flexible enough to easily compensate for slight differences in expansion coefficients, such tubular bodies can be used in discharge lamp vessels. Because it is difficult to directly seal this type of tubular body, in the conventional structure, a translucent dense sintered alumina plug is prepared in advance and the plug is hermetically sealed with this type of tubular body. Indirect sealing was used to airtightly seal the lamp to a discharge lamp container made of the same material. In other conventional structures, a lid made of dense sintered alumina is used in place of the above-mentioned plug, and the lid is hermetically sealed to the outside of the open end of the discharge lamp container. . Furthermore, in another conventional structure, a large diameter collar with a relatively thin wall thickness is similarly provided integrally with a tubular power supply member, and the thin collar is directly sealed inside the opening of the discharge lamp container. Of course, the hermetic seal of such a structure has extremely high flexibility. In some cases, this hermetic sealing part was modified so that the above-mentioned flange was sealed on the outside of the container opening instead of on the inside. However, in most of the conventional structures described above, adhesive glass is used between the components of the hermetic sealing part, and the reason is that if the adhesive glass is not used, the hermetic sealing part cannot be constructed. This is because it is essentially impossible. The sealing material, that is, the adhesive glass that should be used between the components of the hermetic sealing part is basically made of aluminum oxide or calcium oxide, as described in British Patent No. 1019821, which will be mentioned later. A glass-like material or glass-forming material consisting of a combination of bonding glass and magnesium oxide, and without the use of such an adhesive glass, it is impossible to obtain an airtight seal between the components, e.g. due to differences in expansion coefficients. Gas leakage occurs at the sealing portion between the wall surfaces of the power supply member and the sealing component, and furthermore, gas leakage occurs between the metal of the power supply member and the alumina of the sealing member due to sintering of alumina as described below. It will also be impossible to achieve this goal. However, in the hermetic sealing part of the conventional structure described above, the adhesive glass is exposed to extremely high temperatures and corrosive gas atmosphere both during manufacturing and operation of the discharge lamp. Of course, strict conditions were imposed on the composition. In addition, although gas discharge lamps with the above-mentioned conventional hermetic sealing structure can achieve sufficiently satisfactory performance in practical use, it is difficult to manufacture the hermetic sealing part, so it is difficult to manufacture the gas discharge lamp immediately after the product is completed. The problem was that the defective rate due to gas leakage was extremely high for both structures. That is, in the conventional structure described above, since the power supply member was sealed to the discharge lamp container using only one of the plug body and the lid body, it was difficult to connect these sealing components and the discharge lamp vessel. In addition, in such a structure, the expansion coefficient of the adhesive glass used cannot be adjusted to the same extent in any product or in any individual product. Sufficient reliability is not achieved mainly due to the fact that it is difficult to ensure that the parts are always the same, and as a result, the hermetic seal is susceptible to distortions that can cause cracks. There was a problem. An object of the present invention is to solve the above-mentioned problems with the conventional structure of the airtight sealing part, to prevent gas leakage not only during use but also during manufacturing, and to provide an airtight sealing part with an easy-to-manufacture structure. An object of the present invention is to provide a sintered alumina container discharge lamp in which a power supply member is sealed to a discharge lamp container. That is, the present invention provides a discharge lamp in which at least one power supply member is hermetically sealed in a discharge lamp container made of translucent dense sintered alumina, which has at least a cylindrical power supply member sealed portion and constitutes a discharge space. A plug body made of translucent dense sintered alumina is placed in the cylindrical portion and sintered to the discharge lamp vessel in an airtight manner, and an opening is provided in the plug body and the temperature inside the opening is heated to a temperature higher than 800°C. , and the power supply member is hermetically sealed with translucent dense sintered alumina and adhesive glass having a melting point lower than the melting point of the metal constituting the power supply member, and further has an opening that penetrates the power connection member. A cylindrical portion of the discharge lamp container and a lid made of translucent dense sintered alumina that supports the plug disposed in the cylindrical portion;
The discharge lamp vessel is made of adhesive glass having a melting point higher than 800°C and lower than the melting point of the translucent dense sintered alumina and the metal constituting the power supply member.
The present invention is characterized in that the plug body and the power supply member are hermetically sealed. As mentioned above, a structure in which a plug is sealed in a discharge lamp tube body made of translucent dense sintered alumina is known, and in this conventional structure, a discharge lamp made of translucent dense sintered alumina It is also known to seal the plug to the tube with adhesive glass or a low melting point porcelain material. However, such conventional structure
This is mainly due to the fact that the coefficient of expansion of the adhesive materials used is not always the same, resulting in insufficient reliability and, as a result, distortions that can lead to cracking in hermetic seals. tend to occur in the
There was a drawback. Furthermore, in the conventional structure described above, an annular pool of adhesive material is formed inside the discharge lamp container at the corner where the container and the stopper come into contact, and the adhesive material in the pool is highly active during operation of the gas discharge lamp. Exposure to an aggressive gas atmosphere at high temperatures results in not only frequent discoloration of the discharge lamp vessel, but also cracks in the adhesive material at the pool, which cracks between the stopper and the vessel. The disadvantage is that this often extends to certain adhesive materials. On the other hand, in the structure according to the present invention, the plug body is sealed to the discharge lamp container by sintering, so the above-mentioned drawbacks do not occur. Generally, when agglomerated and bonded metal materials are heated and sintered, metal powder is formed without melting. That is, sintering means heating a collection of fine particles of metal or metal oxide at a temperature below the melting temperature to weld the fine particles together and form a lump. Therefore, as mentioned above, when an adhesive material made of densely sintered translucent polycrystalline aluminum oxide, that is, alumina, is sintered in a discharge lamp container made of the same material, the adhesion is weak before sintering. The density of particles in the material was slightly higher than the density of particles in the wall of the discharge lamp vessel, but during sintering, the wall of the discharge lamp vessel shrinks more rapidly than the adhesive material. By such sintering, a hermetic seal will be achieved. In the structure according to the present invention, the discharge lamp container and the plug fitted to the open end of the discharge lamp container are reliably hermetically sealed by sintering homogeneous alumina without using adhesive glass, as described above. In this state, a power supply member is fitted into the center opening of a lid made of homogeneous alumina in the opening of the stopper at the end of the container as described in detail later in the drawings, and adhesive glass is attached to both sides of the lid. The ring bodies of the forming material are overlapped and the power feeding member is fitted, and the stopper and the lid are crimped together and heated to melt the adhesive glass forming material, so that the stopper and the power feeding member are bonded together. The molten adhesive glass is infiltrated into the gap from the outside of the stopper, and at the same time, the molten adhesive glass is also infiltrated into the gap between the cover and the power supply member, as well as the gap between the cover and the stopper and the end surface of the container. Therefore, first, a thin layer of long cylindrical adhesive glass is formed on the surface of the fitted portion of the power supply member, and is in continuous contact with the stopper and the lid. Since the adhesive glass was formed by penetrating from the outside of the plug, there was no risk that the end of the thin layer would be exposed to the discharge space inside the container and exposed to the corrosive gas atmosphere at high temperatures. Thus, a long thin layer of adhesive glass along the power supply member provides a safe and reliable hermetic seal, and the risk of gas leakage due to cracking of the adhesive glass due to operation of the discharge lamp is reliably eliminated. Moreover, because of the long thin layer of adhesive glass that stretches along the power supply member, the thin layer of adhesive glass that fills the gaps between the lid, the plug, and the end of the container is also far away from the corrosive gas atmosphere in the discharge space. Therefore, an extremely safe and reliable airtight seal is achieved between the lid, the stopper, and the end surface of the container, and as a result, in the discharge lamp of the present invention, not only during manufacturing but also during operation of the discharge lamp. The risk of gas leakage due to cracks in the bonded glass is greatly reduced compared to conventional methods.
An extremely reliable hermetic seal is obtained. In addition,
If necessary, an annular pool of adhesive glass can be provided on the outside of the discharge lamp vessel at the corner portion where the power supply member and the lid come into contact, and such a pool of adhesive glass is provided on the outside of the overall structure according to the present invention. Therefore, the adhesive glass in the pool is not actually attacked by the corrosive gas atmosphere in the discharge space. Since the discharge lamp of the present invention is often subjected to operating temperatures exceeding 700°C, the adhesive glass that seals each part must have a melting point of 800°C or higher, and in particular, at least Such a high temperature occurs when high-pressure gas discharge is performed in a discharge space in a gas atmosphere containing one type of alkali metal, mercury, and at least one type of rare gas. Therefore,
The present invention, which uses such adhesive glass, is particularly suitable when applied to so-called high-pressure sodium vapor discharge lamps that contain sodium as an alkali metal and xenon as a rare gas. In the discharge lamp of the present invention, it is preferable that at least the portion of the power supply member that is hermetically sealed to the stopper and the lid be made of metal niobium, as in the conventional discharge lamp. In a particularly preferred configuration example of the discharge lamp of the present invention,
The lid protrudes from the end face of the cylindrical part of the discharge lamp vessel, and an annular pool of adhesive glass is provided at the corner where the cylindrical part and the lid meet, resulting in a more reliable air conditioner. It is designed to provide a hermetic seal. In the discharge lamp of the present invention, as in the low-pressure sodium vapor discharge lamp, an outer tube is evacuated or filled with an inert gas such as argon, and the discharge space in which gas discharge is actually performed is used. A discharge lamp vessel constituting the lamp can be placed inside the outer bulb. Note that this outer bulb serves as a thermal insulator, similar to that in low-pressure sodium vapor discharge lamps. In a particularly preferred example of this kind of configuration of the discharge lamp of the present invention, the power supply member is constituted by a tubular body having an opening at the end opposite to the discharge space.
A rod-shaped support body loosely inserted into the open end of the power supply member is fixed to the outer tube, and a rod-shaped support body fixed to the outer tube is loosely inserted into the open end of the power supply member fixed to the discharge lamp container. Therefore, the discharge lamp container can be easily expanded in response to the high temperature during operation of the discharge lamp without applying a force to the power supply end that would damage the hermetic seal or the power supply member. Note that with such a structure, as a result of loosely inserting the power supply member and the rod-shaped support into each other, it may not be possible to obtain the necessary electrical connection between them. One end of the flexible conducting wire is connected to the power supply member, and the other end is connected to an electrode conducting wire provided at, for example, a knob portion of the outer tube. The invention will be explained in detail below by way of example embodiments with reference to the drawings. In the configuration example of the discharge lamp of the present invention shown in FIG.
Reference numeral 1 denotes a discharge lamp container constituting a discharge space 2, in which gas discharge is performed in an atmosphere containing, for example, sodium vapor, mercury vapor, and rare gas such as xenon. The discharge lamp vessel 1 is made of densely sintered translucent alumina, and discharge electrodes 3 and 4, which are equipped with tungsten coils and configured in a well-known manner, are arranged at both ends of the discharge space 2. 3 and 4 are respectively attached to power supply members 5 and 6 made of niobium tubes. Reference numerals 7 and 8 denote two plugs made of transparent alumina which are similarly densely sintered, and these plugs 7 and 8 are sealed to the discharge lamp container 1 by sintering. Reference numerals 9 and 10 denote two lids made of densely sintered translucent alumina, and these lids 9 and 10 are sealed to both the discharge lamp container 1 and the plugs 7 and 8, respectively. do. The discharge tube 1 having such a structure is made of, for example, an outer tube 11 made of hard glass.
The outer tube 11 is provided with a knob 12, and two support conductors 13 and 1 are housed in the inner tube, and the outer tube 11 is provided with a knob 12.
4 to the knob 12. 15 and 16
The supporting conductors 14 and 1 support the discharge electrodes 3 and 4.
These are two strip-shaped connecting members that are connected to 3, respectively. Note that the support conductor 14 is covered with a quartz glass tube 17 for protection. 18 and 19 are the outer tube 11
There are two getter rings to maintain the vacuum inside. Next, in an example of the detailed configuration of the hermetic sealing portion between the discharge lamp container 1 and the power supply member 6 shown in FIG.
The structure of the upper end of the gas discharge lamp 1 shown in FIG. 1 is shown in an enlarged scale, and the same parts as shown in FIG. 1 are given the same symbols. The thick black line 20 is
This shows that the plug body 7 made of translucent dense sintered alumina is sintered to the discharge lamp vessel 1 made of the same material. Reference numeral 21 denotes adhesive glass, and as shown in the figure, the power supply member 6 is sealed to both the lid 9 and the stopper 7. It is also arranged between the end surface of the discharge lamp container 1 and the plug body 7. In this way, since the long adhesive glass layer is provided at a location suitable for sealing, extremely excellent hermetic sealing can be achieved. There is essentially no adhesive glass in the corner portion where the power supply member 6 and the stopper 7 contact each other in the discharge space, which could be corroded by the corrosive gas atmosphere in the discharge space, and there is no adhesive glass outside the discharge space. Although an annular pool of adhesive glass is formed at the corner portion where the adhesive glass contacts, there is no risk of it being attacked by the corrosive gas atmosphere outside the discharge space. Among the discharge electrodes 3,
The part that is actually attached to the power supply member 6 is a part 22 made of, for example, molybdenum, and this part 22 is made of, for example, molybdenum.
It is mounted in a known manner using, for example, titanium, within the tubular opening of the power supply member 6, which is mostly made of niobium, and is connected to a tungsten rod 23 in the form of a rod at its end. Reference numeral 24 denotes a tungsten coil, which is wound around the rod-shaped end of the above-mentioned component 22 and the tungsten rod, and is coated with a substance that easily emits electrons, if necessary. The other configuration example of the airtight sealing part shown in FIG. 3 is composed of the same components as in the example shown in the second diagram described above, and these configurations are denoted by the same symbols as in FIG. 2. There is. In the configuration example shown in the third figure, the lid 9 has a larger diameter than the discharge lamp container 1, and as a result, a ring of adhesive glass is formed at the outer corner where the lid 9 and the container 1 touch. Since the reservoir 28 is formed, a more reliable and easy airtight seal is ensured. In manufacturing the discharge lamp of the present invention, first,
The plugs 7 and 8 are attached to the container 1, and openings to which the power supply member is to be attached are provided in the plugs 7 and 8. The above manufacturing process is preferably carried out as follows. That is, as shown in FIG. 4, an assembly is prepared in advance in which a tubular power supply member 6 to which a discharge electrode is attached, which is made up of parts 22, 23, and 24, is inserted into an opening of a lid 9, and the assembly is inserted into the opening of the lid 9. Ring bodies 25 and 26 made of glass-like material, that is, glass-forming material are disposed on the upper and lower surfaces of 9, respectively. Note that this glass-forming material is a mixture having a composition as described, for example, in the aforementioned British Patent No. 1019821. 27 is a thin strip or linear body made of, for example, molybdenum, and this strip or linear body 27 is attached to the power supply member 6 to prevent the power supply member 6 from falling out from the opening of the lid body 9. It also serves to reliably guide the discharge electrode to the correct position within the container 1. After manufacturing such an assembly as shown in the figure, the assembly is mounted on the plug body 7 by inserting the tubular power supply member 6 into the opening of the plug body 7, and heated in this state to melt the glass-forming material. When 25 and 26 are melted, the melted glass-forming material penetrates into the gap between the power supply member 6 and both the lid body 9 and the stopper body 7 and airtightly seals them together, as shown in FIG. As shown,
It also penetrates between the lid 9, the stopper 7, and the end surface of the container 1, forming an adhesive glass layer therebetween. Next, FIG. 5 shows an example of an apparatus for hermetically sealing the discharge lamp of the present invention in manufacturing it. This sealing device consists of a bell-shaped glass 30 attached to a base via a packing 31.
0 houses a tubular core 32 having an opening at its upper end. A metal base 36 which can be cooled with water is arranged inside the tubular core 32, and the cooling water can be supplied through a conduit 37 and discharged through a conduit 38. 4 at the periphery of the quartz glass sleeve 39 attached to the metal base 36 so as to surround the metal base 36.
A book of tungsten rods 40 is supported, and a cylindrical body 41 made of graphite is supported at the upper end of the tungsten rods 40. Further, a high-frequency heating coil 42 is arranged outside the bell-shaped glass 30 so as to surround the graphite cylinder 41. The hermetic sealing portion of the light-transmitting dense sintered alumina discharge lamp vessel 43 is manufactured using the above-described sealing device as follows. That is, first, the plugs 44 and 45 are sealed in advance by sintering to both the upper and lower ends of the container 43, and the assembly shown in FIG. Place it on 36. Next, the tubular core 32 is installed, followed by the pin 35, intermediate member 33, and spring 34. Next, bell-shaped glass 3
0, the pin 35 presses the fourth illustrated assembly against the upper end of the container 43, ie, the stopper 44. After installing everything in this way, conduit 3
In addition to supplying cooling water from 7, bell-shaped glass 30
Then, the entire interior of the discharge lamp vessel 43 is filled with an inert gas such as argon. Next, the graphite cylindrical body 41 is heated by the high-frequency heating coil 42 to melt the ring body 48 of the glass-forming material, and the lid body 4 is heated.
9 and the power supply member 50 into the container 43 and the stopper 44
Seal airtightly. After cooling, the bell-shaped glass 30 and the tubular core 32 are removed, and the discharge lamp container 43 whose upper end is hermetically sealed is taken out. The hermetic sealing portion at the lower end of the discharge lamp vessel 43 is also manufactured in the same manner as described above, but before the final hermetic sealing, a required amount of mercury is accommodated in the discharge lamp vessel. Although it is not necessary to introduce mercury in an inert gas, it is necessary to introduce an alkali metal in an inert gas, and the operation is carried out as follows. That is, a discharge lamp container whose lower end is hermetically sealed is mounted on a metal base 36, and then, after the tubular core 32 is mounted, an inert gas such as argon is introduced through a conduit 46.
Note that, at this time, the exhaust port 47 is kept closed. When the inert gas fills the tubular core 32, it is ensured that the discharge lamp vessel 43 is also filled with the inert gas, and excess inert gas flows out from the upper end of the tubular core 32. Next, a required amount of alkali metal, such as sodium, is inserted into the discharge lamp container 43 through the upper opening thereof, and then the assembly shown in the fourth figure is inserted into the container 4.
Attach to the top opening of 3. In this case, the inert gas is continuously introduced. Next, after the crimping members 33, 34, 35 and the bell-shaped glass 30 are sequentially attached, the conduit 46 is closed and the entire inside of the bell-shaped glass 30 is evacuated through the exhaust pipe 47. Thereafter, a rare gas such as xenon, which is necessary when the discharge lamp is completed, is supplied from the conduit 46, and then high-frequency heating is performed to seal the upper end opening of the container 43 hermetically in exactly the same manner as described above. Next, another configuration example of the discharge lamp of the present invention shown in FIG. 6 is almost the same as the configuration example shown in FIG. The projection 62 inside the apex of the outer tube
It is coaxially supported by Since the support rod 61 is loosely inserted into the tubular power supply member 60, even if the discharge lamp container 63 is heated to a high temperature during operation of the discharge lamp, the container 63 will not slide between the support rod 61 and the tubular power supply member 60. This allows it to expand freely upwards. In addition, the current supply to the upper power supply member is as follows:
This is done via a flexible conductive wire 64 which has one end connected to the power supply member 60 and the other end connected to a support conductive wire 66 sealed to the knob 65 . In a discharge lamp in which at least one power supply member is hermetically sealed in a discharge lamp container made of translucent dense sintered alumina which forms a discharge space with at least the sealed part of the power supply member being cylindrical, A plug made of consolidated alumina is arranged in the cylindrical portion and sintered to the discharge lamp container in an airtight manner, and an opening is provided in the plug, and a temperature higher than 800° C. and a light transmitting temperature are provided in the opening. the power supply member is hermetically sealed with adhesive glass having a melting point lower than the melting point of the metal constituting the power supply member and dense sintered alumina;
Furthermore, a lid body made of translucent dense sintered alumina having an opening that penetrates the power supply member and supporting a cylindrical portion of the discharge lamp container and the plug body disposed in the cylindrical portion is heated to 800°C. The discharge lamp container, the plug body, and the power supply member are hermetically sealed with an adhesive glass having a melting point higher than that of the translucent dense sintered alumina and a melting point lower than that of the metal constituting the power supply member. Characteristic sintered alumina container discharge lamp.

[Claims]

1. In a discharge lamp in which at least one power supply member is hermetically sealed in a discharge lamp container made of translucent dense sintered alumina with at least the sealed part of the power supply member being cylindrical and constituting a discharge space, A plug made of sintered alumina is arranged in the cylindrical part and sintered to the discharge lamp vessel in an airtight manner, and an opening is provided in the plug, and a temperature higher than 800°C and transparent is provided in the plug. the power supply member is hermetically sealed with optical dense sintered alumina and adhesive glass having a melting point lower than the melting point of the metal constituting the power supply member;
Furthermore, a cover made of translucent dense sintered alumina having an opening that penetrates the power supply member and supporting the cylindrical portion of the discharge lamp container and the plug disposed in the cylindrical portion is heated to 800°C. The discharge lamp container, the plug body, and the power supply member are hermetically sealed with an adhesive glass having a melting point higher than that of transparent dense sintered alumina and a melting point lower than that of the metal constituting the power supply member. Characteristic sintered alumina container discharge lamp.