JPS6014465B2 - Arc discharge lamp and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to metal vapor arc lamps operating with excess unevaporated metal, and more particularly to cold spot (
ColdSpot) relates to a high-pressure sodium lamp using an alumina ceramic outer envelope in which the temperature determines the vapor pressure within the lamp as well as its voltage drop.

BACKGROUND OF THE INVENTION The high-intensity sodium vapor lamps for which the present invention is most useful include a narrow, tubular ceramic arc tube, which is typically housed within a glassy outer tube or jacket.

The arc tube is made of a transparent, high temperature resistant oxide material that becomes sodium resistant at elevated temperatures, and is preferably made of dense polycrystalline alumina or synthetic sapphire. The arc tube includes a sustaining fill that includes sodium along with mercury to improve efficiency and a noble gas to facilitate starting. The arc tube contains a thermionic electrode,
The ends of the arc tube are sealed by sealing members, and the ends are connected to the electrodes via these seals. The outer envelope containing the ceramic arc tube typically has a base at one end to which the arc tube's electrodes are connected. High pressure sodium lamps contain excess sodium mercury amalgam.

That is, it contains more amalgam than will evaporate when the lamp reaches stable operating conditions. By having an excess of bases, the amount supplied becomes non-critical,
Also, some of the excess amalgam is utilized to replenish the lead lost over the age of the lamp, for example by electrolysis through the alumina wall. The lamp voltage, ie, the voltage drop across the arc tube during normal operation, depends on the vapor pressure, which is determined by the lowest temperature of the arc tube, which depends on thermal balance.

A preferred lamp design uses an externally projecting metal exhaust tube that is sealed and provides a reservoir for excess sodium mercury amalgam outside of the arc tube position. Such a configuration has the advantage of retaining excess amalgam in a location not affected by the direct heat of the arc tube as well as the electrodes, so that as the lamp ages, the arc tube darkens due to sodium vapor pressure. and has only a slight effect on the lamp voltage. The use of an external reservoir also facilitates fine adjustment of the thermal balance of the lamp. Another lamp design, without an exhaust tube, is accomplished by inserting a fill of sodium mercury amalgam into the arc tube, which is closed at one end. Then, while the closed end cools, the other end is sealed in a chamber containing an inert gas for starting the lamp. In such lamps, thermal equilibrium results in a cold spot at one end or the other, and excess amalgam accumulates primarily in the shank where the end cap or plug is bonded to the ceramic body. In both designs, the lamp voltage increases with lamp life and reaches the end of life when the ballast can no longer maintain the arc against large voltage drops. In the manufacture of high pressure sodium lamps, the dimensions, materials and processing methods of the parts are carefully selected to maintain the lamp voltage within specification limits.

That said, more than 10% of these lamps made in Ishun's transferor's factories are modified. This is because the final lamp voltage will be above or below the specification limits. Attempting to refurbish a lamp is expensive and time consuming.
Correcting the thermal balance involves breaking the outer tube or jacket, cutting the ceramic arc tube from the old stem structure, welding it to the new stem structure, and adding an exhaust pipe radiation shield. Or it means to remove it. Alternatively, thermal equilibration may be achieved by spraying the exhaust pipe with particulates or by painting it with chrome green paint. The refurbished arc tube must be sealed in a new outer bulb, which must then be evacuated and the lamp re-capped and reconditioned. SUMMARY OF THE INVENTION The purpose of the invention is to eliminate the above-mentioned reconditioning procedure, thereby making it possible to change the characteristic voltage of the lamp without opening (i.e. without destroying) the outer bulb.

The lamp according to the invention comprises a thermal link coupled to a metal part forming part of or attached to the arc tube, the metal part forming part of or being attached to the arc tube. Village heat loss significantly affects cold spot temperature. In lamps which have an external metal exhaust pipe acting as a reservoir, the link is conveniently connected to the exhaust pipe.
The invention provides a thermal link whose heat transfer is reduced in the finished lamp without destroying the lamp jacket. Preferably, heat conduction through the links reduces the average of the lamp voltage distribution sufficiently so that the proportion of high voltage lamps produced is very small. Although most of the lamps produced are lamps with lamp voltages within the specification limits, there is also a proportion of lamps with lamp voltages below the lower specification limits. Low voltage lamps are regulated with increased voltage by reducing the heat transfer of the thermal link. In a preferred embodiment, the thermal link is provided in the form of a wire extending from the exhaust pipe to the metal frame of the support structure, comprising a main part and a severable auxiliary part.

The wires in the auxiliary part are thinner or longer than the wires in the main part. This is because it has lower thermal conductivity. In low voltage lamps, the auxiliary wire is easily cut without breaking the outer bulb. That is, by cutting the wire with a laser beam aimed through the glass of the outer tube. Another method of cutting the auxiliary wire is to include a low temperature melting part in the auxiliary wire and heat the part by passing a high frequency current through the part. DETAILED DESCRIPTION A high-pressure sodium lamp 1 embodying the invention corresponds to a magnitude of 400 watts and is shown in FIG.

It comprises a vitreous outer tube 2 which has a standard cap 3 which is attached to the stem shown at the top. The press section 4 of the re-entrant stem has a pair of relatively thick leads 5, 6 which extend through the stem and whose outer ends meet the shell 7 and eyelet 8 of the base. Connected. The inner tube or arc tube 9 is centrally located within the outer tube and consists of a length of translucent ceramic tube, preferably a translucent polycrystalline alumina ceramic or a transparent monocrystalline ceramic tube. made of alumina.

The upper end of the arc tube has an alumina ceramic plug 10.
The niobium introducer wire 11 extends in a sealed manner, which supports the upper electrode. The lower end closure is also provided with a ceramic plug 12 through which a niobium exhaust pipe 1 made of sheet metal is inserted.
3 grows. During the manufacture of the lamp, it is used as an evacuation and filling tube, as well as a support for the lower electrode and as a current lead-in line. In the final product lamp, the exhaust pipe 13 forms a reservoir for excess mercury amalgam. A ceramic plug is sealed at the end of the arc tube, and the niobium inlet wire 11 and exhaust tube 13 are sealed through the plug. These seals are provided by a glassy composition, which consists primarily of alumina as well as calcia which is fused. The conventionally constructed electrode (not shown) is a moderately densely wound coil of tungsten wire, which is composed of a tungstate of calcium tungstate (di sulfate) held in the interstices between the windings. rimcalcimmtsahokotate
) is activated by

These electrodes are respectively disposed at opposite ends of the arc tube and are supported by an introduction wire 11 and an exhaust pipe 13.
For reference, U.S. Patent Nos. 3 and 7 of Sm$er et al.
No. 1 is available, and details of suitable electrodes are described therein. According to this example, the illustrated lamp has a size of 400 watts, the arc tube is 112 millimeters long, and the aperture is 7 millimeters. The filling has a weight ratio of 2
It consists of a 25 milligram amalgam filling of 5 cents sodium and 75 cents mercury, and xenon at a pressure of 20 torr used as a starter. The illustrated exhaust tube 13 is flattened and sealed at the end 14 and has a flat end portion 15 of sufficient volume to accommodate excess amalgam.
Such flat end portions are useful for general purpose lamps that are subject to shock or vibration. The arc tube is disposed within the outer tube in a manner that takes into account different thermal expansions.

A cancer-like support rod 1 extending approximately in the longitudinal direction of the outer tube.
6 is supported by a spring clamp 17 which is welded to the lead line 5 on the stem end on the one hand and engages a nipple 18 on the other hand at the dome end of the outer tube. The arc tube is held primarily by a wire (main part) 19 which is welded from the niobium exhaust tube 13 to the support rod 16. At the upper end, the dorsal lead-in wire 11 extends through an insulating bushing 21, which is held on the rod 16 by a metal strap 22. The opening through the bushing allows free movement of the introducer wire 11 in all axes, and the introducer wire is electrically connected to the lead wire 6 by the sacrificial introducer 23 . The differential thermal expansion of the alumina arc tube relative to the mount (support rod) is adjusted by the axial movement of the lead-in wire 11 through the bushing 21 and the flexibility of the bent conductor 23.
Here, consider the thermal link extending from the exhaust pipe 13 to the support rod 16.

It consists of a main part and a cuttable auxiliary part. If the thermal conductivity of the auxiliary part is small compared to that of the main part, a reasonable first approximation of the effect of cutting the auxiliary part is as follows. That is, the change in the operating voltage of the lamp is proportional to the thermal conductivity of the cut section.

The effective thermal conductivity C of the auxiliary part is given by ・C=K-sha.

here, K = effective thermal conductivity of the part, A = cross-sectional area of the part, and L = length of section, It is.

In tests performed on lamps, the thermal link
It had a main section of 35 mil niobium wire and had auxiliary sections.

FIG. 3 shows the effect of lamp voltage when using auxiliary sections of 20 mil, 30 mil, or 35 mil niobium wire. What is observed is that the voltage rise is approximately linear with the square of the wire diameter.
The diameter or length of the wire may be varied to control the voltage rise that occurs when the auxiliary portion is cut. 1st
The thermal link between the exhaust pipe 13 and the support rod 16 shown in the figure determines the embodiment of the invention, which is also desirable from the point of view of easy automation of manufacturing.

The niobium main section 19 is suitably 35 mils in diameter and is spot welded to the support rod 16 and extends to the niobium exhaust pipe 13, whereas the main section 19
are spot welded onto the flattened end portion 15. At a point beyond the spot weld, the niopium wire is bent to give a slightly longer section 19a, which connects the support rod 16 to the spot weld at a suitable distance from the first spot weld. be done. This configuration allows the use of a single wire size and provides a thermal link. In this case, the main part 19 is relatively short and the auxiliary part 19a is longer than the main part and therefore has a lower electrical conductivity. In a manufacturing process utilizing the present invention, a device is produced as shown in FIG.

The completed lamp is briefly dried and tested for voltage.

Those lamps whose voltage drops below the lower specification limit are isolated and a laser pulse is focused on the auxiliary wire 19a to cut it. The cut portion is shown as 19b in FIG. 1a. 20 joules of pulsed neodymium at an output wavelength of 1.06 microns (Mmi
mm) laser is sufficient to cut the wire.

In this case, the laser is focused onto the wire through the outer tube.
It is desirable to use niobium or other high temperature resistant metal with a low vapor pressure at the cutting temperature as the auxiliary wire. This is to prevent a heat and light reflective thin film from being formed on the inner surface of the outer tube 2. Niobium melts at 2468 degrees Celsius, and when it is cut by a laser, small pieces scatter,
Or it may stick to the cut end. However, no obstructive thin film is formed anywhere. There are other ways to open (cut) the auxiliary portion of the thermal link besides using a laser.

Referring to FIG. 2, the thermal link between the exhaust pipe 13 and the support rod 16 includes a main portion 31 of 35 mil niobium wire and a secondary portion forming a square loop. The auxiliary sections are made of 15 mil wire and are spot welded to the exhaust pipe, with a section 32 constructed of niobium, which has a lower melting point, and another section 32 that is welded to the support rod, which has a lower vapor pressure at its melting point. 33 of metal, preferably aluminum. These two parts are joined together by ultrasonic welding. In this embodiment, after the lamp is completed, a high frequency current is passed through the square loop formed by the two parts of the thermal link, the exhaust pipe and the support rod, in order to open the auxiliary part of the thermal link. It will be done. The current generates heat and since the aluminum wire section 33 has the smallest cross section and the lowest melting temperature of 660° C., it melts and opens the auxiliary section of the link. A variation of the method to achieve the same objective is to apply a heat lamp to the low melting temperature portion 33 of the link. In a variant of the invention shown in FIG. 4, the lower end of the arc tube 9 is closed by a ceramic plug 40 through which a niobium lead 41 extends in a sealed manner.
It supports an electrode 42 shown in dotted lines.

The wire seal may be similar to that at the upper end of the arc tube shown in FIG. In such lamps that do not have an exhaust pipe and are symmetrical, an amalgam filling is sealed within the arc tube prior to sealing the end a second time. The lower end of the arc tube is cooled and sealed within a chamber containing a lamp starting gas, such as an inert gas such as xenon. A suitable process for making lamps in this manner is described in US Pat. No. 3,609,437. However, the details of the wire seal itself are disclosed in U.S. Pat.
2,64〆It is desirable to follow the instructions. Here, the roof between the electrode and the sealing area. The lead wire seal is thermally insulated from the electrode via a shaped conductor. In such lamps, the excess sodium mercury amalgam collects mostly in the corner 43, where the plug is bonded to the ceramic body at the lower end of the arc tube. The thermal link from the lead wire 41 to the frame support rod 16 comprises a thick niobium wire 44 and a thin cuttable niobium auxiliary wire 45. Auxiliary wires 45 are laser cut if required for the completed lamp. A variation of the invention shown in FIG. 5 has wire seals at both ends of the arc tube as shown in FIG.

The illustrated design is particularly suitable for small sizes, e.g.
Suitable for lamps below Watt. In this case, a heat shield is provided at each end of the arc tube to obtain a sufficiently high cold spot temperature with the required thermal balance. heat shield at the lower end,
is provided with a metallic reflective band 46, preferably made of niobium, as shown in the drawings.
It is wrapped around a ceramic arc tube 9 with both ends spot welded and forms a radial tube 47 on the side of the arc tube adjacent the support rod 16. The shield is a wire crossing piece 4 welded to a lead wire 41.
8, and is held in place by a folded tab 49, which together prevent any movement. Reference is made to US Pat. No. 4,034,252, which describes such structures in further detail. According to the invention, a severable thermal link is provided to the heat shield 46 in the form of a wire 50 which is attached at one end to the support rod 16 and at the other end to the tab 49. It is attached. For these completed lamps, they are tested at low voltage, thermal links are cut, and
Voltage increases. Instead of a thermal link with a cuttable auxiliary part, a thermal link can also be used which reduces the cross-sectional area.

For example, a flat band of niobium may be used as a thermal link between the exhaust pipe and the support rod. In any lamp requiring a thermal link, the voltage can be increased by drilling one or more holes in the band using a laser, if necessary to reduce the thermal conductivity. can.

[Brief explanation of drawings]

FIG. 1 shows a high pressure sodium lamp embodying the invention, including a thermal auxiliary link. Figure la shows a cutout of the lamp with the auxiliary link cut. FIG. 2 shows a similar lamp section where the thermal link forms a square loop to facilitate electromagnetic coupling of energy. FIG. 3 is a plot of experimental data showing the proportionality of the lamp voltage rise to the square of the wire diameter of the severable thermal auxiliary link. FIG. 4 shows a portion of a dual wire arc tube embodying the invention. Figure 5 shows the heating,
2 shows a portion of another double wire arc tube embodying the invention in a link with FIG. 1: Lamp, 2: Outer tube, 5, 6
: Lead wire, 9: Arc tube, 11: Introducing wire, 13:
Exhaust pipe, 16: Frame section (support rod), 19,3
1, 44: Main part (main wire), 19a, 32, 3
3, 45, 50: Auxiliary portion (auxiliary wire) 19b: Cut portion, 42: Electrode. Chikarasugi/haiku. Must-resist 〇2 Enemy Q3 Material 4〆Uchisugi. nine

Claims (1)

[Scope of Claims] 1. A glass outer tube having a pair of lead wires sealed therein; an arc tube held within the outer tube and connected to the lead wires; and an arc tube sealed within the arc tube and configured to operate as a lamp. The thermal balance of the lamp determines a cold spot in the arc tube at which excess metal accumulates, and the temperature of the cold spot determines the metal vapor pressure in the arc tube. and an ionizable medium, the voltage drop of which is determined, a metallic member having a heat loss that significantly influences the temperature of the cold spot, and coupled to the metallic member. death,
Thermal links arranged so as to influence the heat loss and increase the voltage drop by effectively reducing the cross-sectional area by the energy delivered through the wall of the front suborbital tube in the completed lamp. An arc discharge lamp characterized by comprising: 2. The thermal link comprises a main part and an auxiliary part, the auxiliary part being severed by suitably applying energy to the wall of the outer tube. arc discharge lamp. 3. The arc discharge lamp of claim 1, wherein the metal member is a sealed exhaust pipe, and the thermal link is coupled to the exhaust pipe. 4. Claim characterized in that the thermal link comprises primary and auxiliary metal conductors extending from the exhaust pipe to a metal frame member holding the arc tube within the outer tube. The arc discharge lamp according to item 1. 5. The arc discharge lamp of claim 1, wherein the metal member is an inlet sealed at the cold end of the arc tube. 6. The arc discharge lamp of claim 1, wherein the metal member acts as a heat shield around the cold end of the arc tube. 7. A glass outer tube having a pair of lead wires sealed therein; and an exhaust pipe and an inlet wire disposed within the outer tube and each having an exhaust pipe and an inlet wire sealed at opposite ends thereof, the exhaust pipe and the inlet wire being sealed. a ceramic arc tube which carries the electrodes therein and is followed by said lead; and a mercury-sodium amalgam sealed within said arc tube in an amount in excess of that which evaporates during operation of the lamp, and which, by thermal equilibrium of the lamp, an ionizable medium such that a cold spot where excess amalgam accumulates in the arc tube is determined, and the temperature of the exhaust tube determines the metal vapor pressure in the arc tube and the voltage drop thereon; A lamp,
a metal member having a heat loss that significantly influences the temperature of the cold spot; a metal frame member holding the arc tube within the outer bulb; and a bond between the metal member and the metal frame member. a thermal link consisting of a metallic conductor and arranged in such a way that in the finished lamp the energy supplied through the walls of the outer bulb can effectively reduce the cross-sectional area and thereby increase the voltage drop; An arc discharge lamp characterized by comprising: 8. the metal member is a sealed exhaust pipe, the thermal link comprises a metal conductor extending from the frame member to the exhaust pipe and returning to the frame member via a long path; 8. An arc discharge lamp as claimed in claim 7, characterized in that the long path conductor can be cut by aiming a laser beam at it through the vitreous outer envelope. 9. The thermal link is comprised of two metal conductors extending from the metal member to the metal frame member and forming an electrically conductive loop such that a high frequency current is passed through the glass of the outer envelope to the metal frame member. 8. The arc discharge lamp according to claim 7, wherein one of said conductors is melted by being supplied to a loop. 10. said thermal link is comprised of two metal conductors extending from said metal member to said metal frame member, at least a portion of one of said metal conductors comprising a metal having a lower melting point than the other portion; The arc discharge lamp according to claim 7, characterized in that: 11 A vitreous outer tube having a pair of lead wires sealed therein, an arc tube held within the outer tube and connected to the lead wires, and an ionizable medium sealed within the arc tube; the medium contains an amount of vaporizable metal in excess of that which evaporates during lamp operation, the thermal balance of the lamp determines a cold spot in the arc tube at which excess metal accumulates, and the temperature of the cold spot determines the A method for manufacturing an arc discharge lamp of a type in which the metal vapor pressure in the arc tube and the voltage drop thereon is determined, comprising providing a metal member with a heat loss that significantly influences the temperature of the cold spot;
A thermal link is coupled to the metal member of each lamp, and the lamps are manufactured to the extent described above, and most of the manufactured lamps have lamp voltage drops within the specification limits and are substantially Generally speaking, only a few lamps have a voltage drop below the low specification limit, and the voltage drop of all completed lamps should be measured and lamps with a voltage drop below the low specification limit should be isolated. , and reducing the thermal conductivity of the thermal link of the isolated lamp to make the cross-sectional area of the thermal link more efficient with energy delivered through the wall of the outer tube without breaking open the outer tube. A method for manufacturing an arc discharge lamp, characterized in that the voltage drop is sufficiently increased above a lower limit by reducing the voltage drop. 12. The thermal link is comprised of a main part and an auxiliary part, and the auxiliary part is cut by supplying sufficient energy to the auxiliary part through the wall of the vitreous outer tube in the separated lamp. A method for manufacturing an arc discharge lamp according to claim 11, characterized in that: 13. A method of manufacturing an arc discharge lamp according to claim 11, characterized in that the auxiliary portion is cut by aiming a laser beam through the wall of the vitreous outer envelope.