HU195029B - Method for sealing ceramic cap of a high-pressure discharge lamp, preferably sodium discharge lamp and the lamp made by said method - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to a method of sealing a ceramic envelope (discharge vessel) closed from its own material at one end of a high pressure discharge lamp, in particular a sodium lamp, by combining an open end of the envelope with a ceramic disk carrying the current conductors.

The invention further relates to a high-pressure discharge lamp produced by the process, in particular to a sodium lamp having a ceramic envelope sealed at one end with an additive and noble gas charge and having a ceramic disk containing the conductors, fixed thereto.

In the presently known embodiments of high-pressure discharge lamps, and in the course of their manufacture, the problem of performing the pumping and soldering operation of the burner body is generally known in parallel with the reduction of dimensions or power: it is necessary to maintain a temperature of 1200-1500 ° C and at the same time to keep the temperature of the additive below 80 ° C at the other end of the smaller size burner. The required temperature gradient is now 35 W rated power, approx. Even with a 35 mm burner, it is hardly safe and the ceramic material has a temperature gradient tolerance. In the suction tube embodiment, the above problem is eliminated, but the relatively large suction tube has a high heat loss and the external cold point requires overheating of the ceramic parts.

For example, known solutions require the use of very wide heat-reflecting clamps to achieve the required cold-point temperature, which significantly reduces the luminous efficiency of the lamps.

60-127634 has become known to reduce the size of the burner body while leaving the suction pipe. JP Publication No. 3,1992, a discharge lamp comprising a ceramic envelope soldered together at one end, similarly to a metal halide lamp, and a ceramic body bonded to the open end of the bulb by means of an annular enamel bond.

However, the construction is not economical for the production of high pressure lamps. Namely, the annular enamel must be melted during the fusion of the bulb and the sealing body. As a result of the heat applied, the pressure in the bulb in the bulb increases and the bulb in the molten enamel is blown, meaning that during production a portion of the bulb material is lost and the effluent gas also displaces the enamel.

It is an object of the present invention to provide a method for sealing the envelope of a ceramic bulb soldered on one end that is free of the above disadvantage, i.e., that the total amount of charge in the bulb remains in the bulb during the enamel bonding between the ceramic bulb and the ceramic closure body.

It has now been found that by forming the sealing body from a ceramic disc having a cross-sectional area larger than the inner cross-section of the bulb and preferably identical to the outer cross-section of the bulb, the disc may be mounted on the bulb during assembly. Further, it has been discovered that placing a sealing ring made of a plastic, high-melting metal between the face of the disc and the open end of the bulb will seal it using an appropriate clamping force between the bulb and the disc until an enamel bond is formed between the bulb and the disc. . Due to the sealing effect of the metal ring, the charge in the bulb, which increases in pressure as the enamel bond is formed, remains in the bulb. It cannot inflate the molten enamel or move the enamel. For the metal ring to be properly sealed, it must be ductile so that it can rest securely on both the front face and the disc. This is the plastic property of the enamel melting! temperature. In addition, its coefficient of thermal expansion must be consistent with the coefficient of thermal expansion of the bulb and disc materials. It must also be resistant to the corrosive effects of the charge in the bulb. Most preferably, these requirements are met by a continuous metal ring of niobium. If the materials in the discharge chamber are corrosive to the metal, the sealing ring is provided with a corrosion-resistant layer on the surface facing the discharge chamber.

It has now been discovered that a method of sealing a closed ceramic bulb of its own material, preferably aluminum oxide, has been developed at one end of a high pressure discharge lamp, particularly a sodium lamp. In the process, a ceramic disk, preferably an alumina disk, is welded to the open end of the envelope by means of a heat-melted and then solidified enamel ring. it carries the vacuum conductors passing through it in a vacuum-tight manner. In accordance with the present invention, the method is further developed by providing an inner, continuous, plastic metal sealing ring to the front surface of the open end of the bulb, in the sense that it is not in contact with the inner space of the bulb. a disk having an enamel ring and conductors, and having a diameter larger than the inner cross-section of the envelope, preferably of the same diameter as the outer envelope of the envelope; clamping and maintaining the compression force, using the enamel ring between the bulb and the disc, the enamel bond is formed and the compression force is removed. At this point, the shroud and disc are tightly connected to each other. The finished discharge lamp can be used without an outer bulb, but it can also be equipped with a vacuum sealed outer bulb. There is either vacuum or noble gas propellant in the space between the discharge lamp and the outer bulb.

The magnitude of the compression force is given in relation to one cm of the edge of the sealing ring along which the sealing ring contacts the face of the bulb.

For producing the high-pressure discharge lamp, it is preferably circular or flattened, e.g. called. a ceramic envelope having a cross-section of a racetrack is closed to the cross-section of its envelope by means of a circular or flattened circular cross-section, e.g. horse racing track with ceramic disc with cross section, with sealing ring and enamel ring of same shape. The advantage of a circular cross-section is that it is easy to manufacture, while a flattened circular section is, for example, a so-called "cross-section". electrodes are preferably placed in the cross-section of the racetrack, resulting in a more uniform heat distribution and wall stabilizing effect.

Preferably, a continuous niobium ring of substantially rectangular cross-section may be used as a sealing ring. This ring is positioned with its diagonal edges resting on the front surface of the ceramic disk or ceramic envelope. Thus, the vacuum seal can be achieved with less compressive force.

It is also advantageous to use a continuous niobium ring made of sheet as a sealing ring. This ring is placed between concentric ribs protruding from the face of the bulb and the disc so that these ribs enclose the sealing ring. This is advantageous mainly because the niobium ring can be formed relatively cheaply from a sheet and its continuity is already solved.

When an envelope containing a filler containing a metal halide as an additive is to be sealed, a niobium ring with a known halogen-resistant layer, such as a mixture of rare-earth oxides, is used as a sealing ring on the surfaces of the envelope. This layer can be formed at the same time as the enamel bond, if the enamel ring is also made of halogen-resistant enamel material. In order to avoid loosening the current conductors fixed to the disc during the heating necessary to form the enamel bond and thus maintaining the seal of the disc, it is advisable to fix the conductors to the disc with a higher melting point,.

as the melting point of the enamel ring used to solder the bulb and the dial.

It is also possible to prevent the melting of the enamel fastening of the lead-in conductors by heat dissipation through the soldered current lead-in, and thus, for example, the lead-in conductors may be fastened with the same material as the enamel ring.

It is also advantageous according to the invention to use a disc bearing material which can withstand the effect of free air at operating temperature without damage. These include, for example, current feeders made of stainless steel.

The sealed discharge lamp may, if desired, also be enclosed in a bulb made of an opaque light-transmitting material, preferably glass. · In the space between the discharge lamp and the outer bulb, a vacuum or a noble gas charge is applied and the outer bulb is sealed tightly.

Advantageously, tantalum conductors can be used for the outer bulb high pressure discharge lamp. In this case, the material of the electrodes is expediently tantalum, thus eliminating the otherwise necessary welding joint between the electrode and the current feeder. For tantalum electrodes, a tantalum-based cathode activator is preferably used.

The present invention also relates to a high-pressure discharge lamp, in particular a sodium lamp, produced by the above-described process. The high-pressure discharge lamp, in particular the sodium lamp, has a closed ceramic bulb on its own material, preferably an aluminum oxide bulb, and a ceramic disk, preferably an alumina seal, sealed by an annular enamel ring fixed to the open end of the bulb. This lamp has been further developed in accordance with the present invention by having an inner, continuous, plastic metal sealing ring disposed concentric to the enamel ring between the face of the open end of the bulb and the disc having a larger cross section than the inner diameter of the bulb.

The bulb of the high-pressure discharge lamp according to the invention is preferably of circular or flattened circular cross-section, e.g. the racetrack may have a cross-section. Of course, the shape of the sealing ring, the enamel ring and the disc is adapted to the cross-section of the envelope.

Preferred is a discharge lamp of the invention having a sealing ring having a continuous niobium ring having a substantially rectangular cross-section. This niobium ring rests along the diagonal edges of the front face and the dial. At the edges, the ring is slightly flattened at the edges, so one of the preferred shape sealing rings is substantially rectangular.

-3195029

In one embodiment of the discharge lamp of the present invention, the sealing ring is a niobium ring formed by a plate which is surrounded on both sides by concentric ribs protruding from the front face and the disc.

Also preferred is a discharge lamp according to the invention in which the current conductors are soldered with enamel having a higher melting point than the melting point of the enamel ring material. The enamel material is calcium aluminate modified with 2-10% by weight of rare earth oxide and strontium and / or barium oxide. Depending on the modification, the melting point of the enamel changes.

In one embodiment of the exterior bulb high pressure discharge lamp, both the leads and the electrodes are made of tantalum. Tantalum is an advantageous current feeder because its coefficient of thermal expansion coincides with that of the material of the disc.

A preferred embodiment of the present invention is a discharge lamp according to the invention, wherein the current-extending conductors extending from the disc to the outside can withstand the effect of air at operating temperature without damage.

In this case, the discharge lamp can be manufactured and marketed without an outer bulb. However, in this case, the soldering material soldered to the ceramic disk may not be the same as the soldering material protruding from the disk, but the two metals must be joined together by a welded joint close to the disk. The coefficient of thermal expansion of the metal, which can withstand the effects of air, does not match the coefficient of expansion of the material of the disc, so that, for example, the stainless steel conductor cannot be soldered into the disc.

BRIEF DESCRIPTION OF THE DRAWINGS Illustrations are provided.

Figure 1 shows a schematic sectional view of an exemplary embodiment of a high pressure discharge lamp.

2a. a side view of a high-pressure discharge lamp of flattened circular cross-section, and

2b. Fig. 3A is a plan view of a high pressure discharge lamp.

Figure 3 is a schematic sectional view of a sealing ring embodiment of a high pressure discharge lamp plate.

Figure 4 is a schematic sectional view of an exemplary embodiment of a high pressure metal halide discharge lamp.

In the figures, the same numbers denote the same details.

The invention will now be described in more detail with reference to the accompanying drawings.

The current leads 6, 7 forming a unit with the electrodes 9, 10 are inserted into the holes of the prefabricated disc 5 and soldered with the enamel 8, thereby making the ceramic disk gas-tight. The additive 4 is placed in a downward facing envelope 1, which is primarily a sodium mercury alloy (sodium amalgam), but may or may not be any other metal halide suitable for discharge physics or light source application technology. In this case, there is a halogen-resistant layer 11 on the surface contacting the discharge area of the sealing ring, and the enamel used for soldering should also preferably be halogen-resistant.

The sealing ring 3 and the enamel ring 4 are placed on the front surface 2 of the bulb 1, and a disk carrying the current inlets 6, 7 is applied thereto and a noble gas is introduced into the bulb. Then, the cover 1 and the disc 5 are clamped in the direction indicated by the arrows in the figure so that the sealing ring 3 is deformed and sealed. Typically, the clamping force is 0.5 to 1000 N per 1 cm of the edge of the sealing ring that contacts the front surface of the bulb. While maintaining the clamping force, the enamel ring 4 is melted by heating, and the discharge lamp thus assembled is cooled to the desired crystal structure and voltage state of the enamel ring. With this, the cover 1 is soldered to the disk 5 and bonded under vacuum, in other words, the enamel bond is formed. At the end of the operation, the clamping force is eliminated. The sealing ring 3 ensures that during the soldering, i.e. during the formation of the enamel bond, the high pressure prevailing in the envelope 1 cannot blow out the molten material of the enamel ring 4 and that the additive or noble gas cannot escape from the envelope 1.

In the sealing process shown, the melting point of the enamel 8 is greater than the melting point of the enamel ring 4, so that the disk 5 remains sealed.

If the material of the enamel 8 is the same as that of the enamel ring 4, during the formation of the enamel bond, heat must be drawn through the lead-in leads 6, 7 so that the enamel 8 does not melt.

The discharge lamp produced according to the invention may be provided with an external, preferably glass bulb, conventional for high-pressure lamps. There is either a vacuum or a noble gas charge in the space between the discharge lamp and the outer bulb.

The bulb sealing method of the present invention is advantageous for producing low-power, high-pressure discharge lamps in particular, but can also be used to produce high-power light sources of up to kilowatt power. The process of the present invention eliminates the practice of fully exploiting the temperature gradient tolerance of a ceramic material during manufacture because one end of the bulb can be sealed with a reliable seal in a single operation.

The high-pressure discharge lamp produced by the process according to the invention has at its one end a cover 1 of alumina material covered with its own material. The bulb shape-4195029 ja may be similar to the glass bulb shape of a known cylindrical bulb but may also have a flattened cross-section (Figure 2).

Aluminum discs 5 are connected to the flat end face 2 of the open end of the bulb 1 through an inner sealing ring 3 and an outer enamel ring 4. 1 and 4, the sealing ring 3 is a continuous niobium ring having a substantially rectangular cross-section. The diagonal deformed edges of the sealing ring rest on the sheath 1 and on the disc 5. Concentric to the sealing ring 3, there is also an enamel ring 4 between the front surface 2 of the bulb 1 and the disc 5, which provides the actual connection between the bulb 1 and the disc 5 of the discharge lamp.

The current conductors 6, 7 pass through the disc 5. Their material (Fig. 1) at the ends opposite to the inner space of the disc, is a metal which is able to withstand the operating temperature of the discharge lamp in the open air without damage, namely stainless steel. The conductors 6, 7 are soldered to the disc 5 with enamel 8 having a melting point higher than the melting point of the enamel ring 4.

The lamp of Figure 4 also requires that the enamel be as halogen-resistant as possible. The current leads 6, 7 passing through the disc 5 are parallel to each other, but the tips of the electrodes 9, 10 are facing each other due to the 90 ° bend. The electrodes 9, 10 do not contain radiators. There is, of course, no obstacle to the use of radiators, where warranted. The conductors 6, 7 and electrodes 9, 10 are not always of the same material and must be welded together in a known manner.

If the bulb 1 has a flat circular cross section, e.g. of course, the sealing ring 3, the enamel ring and the disc 5 are also of circular or flattened circular cross-section with the sheath 1. At defined dimensions and power levels, the electrodes 9, 10 may be positioned within the bulb such that a wall stabilizing effect is exerted on the discharge lamp.

The discharge lamp of the present invention is advantageously used in all locations where low-power or small-sized lamps are required. For example, a suitable electronic ballast can replace conventional incandescent lamps. It is known that the filler in the bulb is most easily attacked by the enamel and thus cannot perform its function after a while, but the lifetime of our discharge lamp is prolonged compared to traditional enamel-only lamps, since the materials in the discharge space cannot come into contact with because of the inner metal sealing ring with the enamel.

Claims (15)

PATENT CLAIMS A method for sealing a ceramic envelope of a high pressure discharge lamp, in particular a sodium lamp, closed at its own end, preferably an alumina envelope, by heat-melting and then solidifying a ceramic disk, preferably aluminum, with an annealed ring carrying the current conductors passing therethrough, characterized in that an inner, continuous metal sealing ring (3) is applied to the open surface (2) of the envelope (1), and externally the enamel ring (6, 7). a bearing plate (5) of the same size as the outer cross-section of the bulb, preferably of the same diameter as the outer part of the bulb, and then the bulb (1) filled with additive and noble gas is required to deform the sealing ring (3). , clamping the disk (5) to the disk (5) by compressive force and maintaining the compressive force by means of an enamel ring (4) between the jacket (1) and the disk (5) in a known manner and then releasing the compressive force. Method according to claim 1, characterized in that a circular or flattened annular sealing ring (3), an enamel ring (4) and a disc are placed on the open face (2) of the open end of the circular or flattened circular envelope (1). (5). Method according to Claim 1 or 2, characterized in that a continuous niobium ring of rectangular cross-section is applied as a sealing ring (3) on the front face (2) of the open end of the bulb (1) with its diagonal edges on the bulb (1) and disk (1). 5) lie down. Method according to claim 1 or 2, characterized in that the sealing ring (3) is a continuous niobium ring made of sheet metal and is inserted between concentric ribs protruding from the front surface of the bulb (1) and the disk (5). 5. A method according to any one of claims 1 to 3, characterized in that the sealing ring (3) is a metal ring bearing a known halogen-resistant layer on the surface facing the inner space of the bulb (1). 6. Method according to any one of claims 1 to 3, characterized in that a disc (5) is inserted between the enamel ring (4) and the sealing ring (3) on the front surface (2) into which the conductors (6, 7) are secured by enamel material with a higher melting point than the enamel ring (4). 7. A method according to any one of the preceding claims, characterized in that heat is drawn through the conductors during the formation of the enamel bond. 8. A method according to any one of claims 1 to 3, characterized in that at its operating temperature, a disc (5) for carrying current-carrying metal conductors (6, 7) made of metal that is exposed to open air is sealed with a -5195029 by inserting a ring (4) on the front surface (2). 9. A method according to any one of claims 1 to 3, characterized in that the sealed discharge lamp is placed in an outer envelope and the air between the discharge lamp and the outer envelope is deaerated and the outer envelope is sealed in a vacuum housing. Method according to Claim 9, characterized in that a disk (5) carrying tantalum current conductors (6, 7) is placed on the front surface (2) by a sealing ring (3) and an enamel ring (4). 11. A high-pressure discharge lamp, in particular a sodium lamp, produced by a method according to any one of claims 1 to 4, having at one end a ceramic envelope sealed with its own material and containing an additive and a noble gas filler, and having a ceramic disk with current conductors passing therethrough, characterized in that the end face (2) of the open end of the bulb (1) is larger than the inner cross-section of the bulb (0), preferably with an inner enamel ring between the disc (5) (4) also has a concentric continuous plastic sealing ring (3). 5 Discharge lamp according to Claim 11, characterized in that the bulb (1) has a flattened circular cross-section and that the sealing ring (3), the enamel ring (4) and the disc (5) are circularly flattened with the bulb (1). 10 Discharge lamp according to claim 11 or 12, characterized in that the metal sealing ring (3) is a continuous niobium ring of rectangular cross-section with its diagonal edges resting on the disk (5). Discharge lamp according to Claim 11 or 12, characterized in that the sealing ring (3) is a continuous niobium ring made of a plate, which is provided bilaterally with the bulb (1). Its 20 end faces (2) and the disc (5) are surrounded by prominent concentric ribs. 15. A 11-14. Discharge lamp according to any one of claims 1 to 4, characterized in that the melting point of the enamel material (8) which solderes the current conductors (6, 7) to the disc (5) exceeds the melting point of the material of the enamel ring (4).