JPH03740B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to ultra-high pressure discharge lamps such as short-arc xenon lamps, ultra-high pressure mercury lamps, and ultra-high pressure metal halide lamps.

It replaces the conventional short-arc xenon lamp, which is equipped with a transparent quartz glass bulb with pinch seals on both sides of the spherical part where the tips of the anode and cathode are housed, and is compact and has excellent impact resistance. A high-intensity discharge lamp that is easy to manufacture and can also achieve higher brightness characteristics when necessary.
The present applicant has developed and already filed a patent application as Japanese Patent Application No. 180621/1983. This high-intensity discharge lamp has a bulb in which the gas is sealed, formed into a straight tube shape using translucent alumina such as single-crystal sapphire, and a base that supports electrodes at both ends of the bulb, which are sealed via joint tubes. However, it is characterized by having an exhaust pipe attached to one of the caps. This feature eliminates electrode-to-bulb contact, eliminating the effects of these differential thermal expansions, and the physical characteristics of the valve and the exhaust structure allow the bulb to be removed from the valve.

This high-intensity discharge lamp is characterized by its miniaturization, which means that the brazed part between the bulb and the joint tube is brought closer to the high-temperature electrode, and the gas pressure inside the bulb is extremely high. In addition, it is preferable to further improve the reliability of the brazed portion, both to extend the life of the brazed portion and to reduce the capacity of the cooling equipment for the brazed portion.

The present invention was proposed under the above circumstances, and its purpose is to improve the reliability of the brazed portion between the valve and the joint pipe, and to make the setting of the electrode interval dependent on the valve length. Do it without worrying,
It is an object of the present invention to provide an ultra-high pressure discharge lamp which can also achieve low cost.

That is, in the present invention, joint pipes are brazed to both ends of a straight-tube-shaped bulb made of translucent alumina, and caps are brazed or welded to each of these joint pipes, and one of the caps is supports an anode disposed within the bulb along the axial direction of the bulb, the other base supports a cathode disposed within the bulb along the axial direction of the bulb and faces the anode, and In a device in which an exhaust pipe communicating with the inside of the valve is attached to one of the caps, and a sealed gas is sealed in the valve, at least the cap supporting the anode and the valve end opposite thereto, the valve and the joint pipe This is an ultra-high-pressure discharge lamp characterized by a ceramic ring having a heat shielding part that covers the brazed part from the inside.

The present invention will be described below with reference to an embodiment shown in FIGS. 1 and 2.

In the figure, 1 is a straight pipe type valve with both ends open. The bulb 1 is made of a translucent alumina such as alumina, single crystal sapphire, or polycrystalline sapphire. This example has an outer diameter of 8 mmφ, a length of 30.5 mm,
This is the case of single crystal sapphire with a wall thickness of 0.85 mm. The characteristics of single crystal sapphire are superior to those of conventional transparent quartz glass as follows. Note that the values in parentheses are for transparent quartz glass. Density at room temperature 3.98gr/
cm ³ (2.20gr/cm ³ ), Mohs hardness at room temperature 9(6), compressive strength at room temperature 2100Kg/cm ² (11500Kg/cm ² ), Young's modulus at room temperature (35-42) x 10 ⁵ Kg / ^cm2 (7.4× ¹⁰⁵
Kg/ ^cm2 ), tensile strength at 20℃, 500℃ and 1000℃
4060Kg/ ^cm2 (1130Kg/ ^cm2 ), 2800Kg/ ^cm2 (1160
Kg/cm ² ) and 3640Kg/cm ² (1310Kg/cm ² ), rigidity modulus at room temperature 21×10 ⁵ Kg/cm ² (3.4×10 ⁵ Kg/cm ² ), Poisson's ratio at room temperature 0.254 (0.14) etc. Cylindrical joint pipes 2 are brazed to both metallized ends of the valve 1, respectively. The joint pipes 2, 2 are made of a metal material such as titanium or an iron-based alloy such as Kovar (trade name). A cap 3 or 4 is brazed or welded to the joint tubes 2, 2, respectively. The caps 3 and 4 are both made of a metal material such as pure iron or an iron-based alloy, and the cap 4 is provided with an electrode support portion 4a on the bulb 1 side so as not to come into contact with the inner peripheral surface of the bulb 1. have. One of the caps 3 supports an anode 5 which is press-fitted and brazed, and which is disposed within the bulb 1 along the axial direction of the bulb 1 . The other cap 4 has its electrode support portion 4
A cathode 6 is supported within the bulb 1 by being press-fitted and brazed to the anode 5 and disposed along the axial direction of the bulb 1 and facing the anode 5. The anode 5 and the cathode 6 are each made of a heat-resistant metal such as tungsten or tritated tungsten. The electrode gap g between the anode 5 and the cathode 6 is appropriately determined, and in this embodiment, the electrode gap g for short arcs is, for example, 2 cm or less. A getter 7 is attached to the tip of the anode 5. In addition, 3
b and 4b are air vent passages during brazing, respectively. Further, one of the caps, for example, the cap 4, is formed with a communication passage 8 that communicates the inside and outside of the valve 1, and connected to this passage 8, an exhaust pipe 9 made of nickel, copper, etc. is attached to the cap 4 by brazing. It is being Furthermore, the sealed gas is sealed at a predetermined pressure within the valve 1 whose both ends are sealed with the above structure. The sealed gas used is an inert gas such as xenon, argon, or krypton, or a selected inert gas containing metal vapor such as mercury, cesium, sodium, potassium, lithium, or rubidium. In this example, xenon gas is sealed at a pressure of 10 to 20 atmospheres. Further, ring bodies 10 and 11 are respectively provided between both ends of the valve 1 and the caps 3 and 4 facing these, and are inserted between these ends. The ring bodies 10 and 11 are made of ceramic and have a cylindrical heat shielding part 13 that covers the brazed part between the valve 1 and the joint pipe 2 from the inside. And, in this example,
As a more preferable example, the inner peripheral surfaces of the ring bodies 10 and 11 are spaced apart from the anode 5 or the cathode 6, and the heat shield part 13
are spaced apart from the end of the valve 1 to form a gap 14 therebetween. Note that 15 is an annular groove that accommodates a brazing material. Further, reference numeral 16 in FIG. 2 indicates a brazing material storage groove carved in the caps 3 and 4.

According to the high-intensity discharge lamp having the above structure, since the exhaust pipe 9 is attached to one of the caps 4, the bulb 1 does not require a spherical part for providing the exhaust pipe 9, unlike the conventional short-arc xenon lamp. . In addition, since the bulb 1 is made of single-crystal sapphire, its physical properties, particularly its strength, are superior to those of quartz glass. ) and will not be destroyed. That is, for these reasons, the valve 1 can be constructed as a straight pipe without requiring a spherical part. Further, since the electrodes (anode 5 and cathode 6) are supported by the bases 3 and 4, the electrodes and the bulb 1 do not come into contact with each other. Therefore, the influence of the difference in thermal expansion between the electrode and the bulb 1 on the sealing portion is almost eliminated, and the pinch sealing portion that is conventionally required is not required. Therefore, as described above, since the discharge lamp does not require a spherical part or a pinch seal part, its size is significantly reduced compared to the conventional one, and residual stress is not generated in the bulb 1. Therefore, manufacturing is significantly easier.

Since the exhaust pipe 9 is attached to the cap 4 as described above, the bulb 1 does not have an exhaust tip like a conventional short arc xenon lamp, and it does not have a pinch seal, so it is more effective than before. Impact resistance is significantly improved.

Furthermore, since the valve 1 is made of single-crystal sapphire, which has high strength and does not generate residual stress, the pressure of the sealed gas can be increased, and the sealed gas can be pumped at high pressure as in this embodiment. When sealed, the brightness can be improved in proportion to the pressure.

Further, since the ceramic ring bodies 10 and 11 are respectively inserted between the valve 1 and the caps 3 and 4, the following excellent effects can be obtained. First, the length of the valve 1 can be shortened and costs can be reduced. Second, the electrode gap g can be set without depending on the length of the valve 1, and for this purpose, by preparing ring bodies 10 and 11 of various lengths, the valve 1
It is possible to adjust the electrode gap g to any size, such as when the length of is constant. Third
In addition, due to the heat resistance and low thermal conductivity of the ceramic rings 10 and 11, it is possible to thermally insulate the valve 1 and the caps 3 and 4 that support the electrodes, which become hot, and also to provide heat shielding parts 13 of the rings 10 and 11. As a result, radiant heat radiated from the high-temperature electrode toward the brazed portion between the bulb 1 and the joint pipes 2, 2 can be blocked, so that the reliability of the brazed portion can be further improved. Incidentally, during lighting of the ultra-high pressure discharge lamp of this embodiment, the temperature of the anode 5, which reaches the highest temperature at its tip, is about 3000°C, and the temperature decreases toward the base 3 due to heat conduction, heat convection, and heat radiation. It becomes a slope. However, since the conductive heat and radiant heat from the anode 5 are blocked by the ceramic ring 10 to the brazed part between the valve 1 and the joint pipe 2, the temperature of the brazed part is lowered to the melting point of the brazing material (normally approx. 800℃)
It can be reliably reduced to below. By ensuring high reliability of such a brazed portion, it is also possible to reduce the capacity of the cooling equipment for air cooling the ultra-high pressure discharge lamp, if necessary. In the case of this embodiment, since the gap 14 is formed between the heat shielding part 13 and the brazed part, it is more preferable to ensure high reliability of the brazed part, and the valve 1 during assembly is more preferable. This does not make the fitting work between the pipe 2 and the joint pipe 2 difficult. Fourthly, the valve 1 and the joint pipe 2 can be brazed reliably. In other words, although the annular brazing material storage groove 15 is formed on the outer periphery of the valve 1 side of the annular bodies 10 and 11, the metal-to-metal (i.e., inside the joint pipe) The joint surface between the circumferential surface and the metallized outer peripheral surface of the end of the valve 1 has better wettability, so the wax stored in the groove 15 is applied to the joint between the valve 1 and the joint pipe 2. This is because it flows smoothly.

Note that the present invention may be implemented as shown in FIG. This embodiment has the same structure as the above embodiment except that the ceramic ring 10 is divided into a plurality of parts, for example, a first ring 10a and a second ring 10b, and a heat shield part 13 is provided on one of them. be. According to this embodiment, since the ring body 10 is formed by stacking a plurality of ring bodies 10a and 10b, heat conduction from the cap to the bulb 1 can be blocked more effectively. Therefore, the reliability of the brazed portion between the valve 1 and the joint pipe 2 can be further improved. In this embodiment, the second ring body 10b may be formed of a heat-resistant and heat-insulating material other than ceramic material, and a heat shield portion may be provided on the second ring body 10b.

Further, in the present invention, the heat shield portion 13 may be formed so as to be in contact with the inner circumference of the end portion of the bulb 1. Further, since the brazed portion on the cathode 6 side does not reach a high temperature as high as that on the anode 5 side, the heat shield portion 13 of the ring body 11 may be omitted.

In addition, when carrying out the present invention, the specific structure, shape, position, material, etc. of the valve, joint pipe, mouthpiece, anode, cathode, exhaust pipe, ring body, etc., and the composition of the sealed gas, etc. shall be as described above. It goes without saying that the invention is not limited to one embodiment, and can be implemented in various configurations as long as it does not go against the gist of the invention.

The gist of the present invention described above is the structure described in the claims. Therefore, according to the present invention, both ends of a light-transmitting alumina bulb and a pair of caps each supporting an anode and a cathode and respectively attached to both ends of the bulb via a joint tube, The structure with the ceramic rings sandwiched between them makes it possible to shorten expensive bulbs and reduce costs, and also allows the electrode spacing between the anode and cathode to be set without depending on the bulb length. can. Further, according to the present invention, at least the annular body sandwiched between the anode-supporting base and the valve end opposite thereto includes a heat shielding portion that covers the brazed portion between the valve and the joint pipe from the inside. By providing a configuration in which the annular body is provided, conductive heat to the brazed portion by the ring body and radiant heat from the electrode can be blocked, and the reliability of the brazed portion can be further improved.

[Brief explanation of drawings]

Fig. 1 is a side view of a short arc xenon lamp according to an embodiment of the present invention, Fig. 2 is an enlarged vertical sectional view of the same example, and Fig. 3 shows a part of another embodiment of the present invention. FIG. 1... Valve, 2... Joint pipe, 3, 4... Base, 5... Anode, 6... Cathode, 9... Exhaust pipe, 1
0,11...ring body, 10a...first ring body, 10b
...Second ring body, 13...Heat shielding part.

Claims (1)

[Claims] 1. Connecting pipes are brazed to both ends of a straight-tube shaped bulb made of translucent alumina, and caps are brazed or welded to each of these coupling pipes, and one of the caps has a socket inside the bulb. one of the bases supports an anode disposed along the axial direction of the bulb; the other base supports a cathode that is disposed within the bulb in the axial direction of the valve and faces the anode; is equipped with an exhaust pipe that communicates with the inside of the valve, and is made of ceramic and has a heat shielding part that covers the brazed part between the valve and the joint pipe from the inside, at least at the mouthpiece supporting the anode and the valve end opposite to this. An ultra-high-pressure discharge lamp characterized by a ring-shaped body with a sealed gas inside the bulb.