JPH0131662B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a metal vapor discharge lamp in which a starter device is built into an outer bulb together with an arc tube.

[Technical background of the invention and its problems]

In recent years, high-efficiency metal halide lamps and high-pressure sodium lamps have been lit using single-yoke coil ballasts for high-pressure mercury lamps. As shown in FIG. 1, this type of discharge lamp has a starter device 3 housed in an outer bulb 1 along with a luminous tube 2. These series circuits are connected in series, and such a series circuit is connected in parallel to the arc tube 2. Such a discharge lamp is connected to a power source 7 via a single-yoke coil ballast 6 for high-pressure mercury lamps, but since the thermally responsive switch 4 is closed at startup, current flows through the current limiting resistor 5, and this limit The thermally responsive switch 4 is opened by the heat generated by the flow resistance 5, and the high voltage pulse voltage generated at this time is applied between the electrodes 8a and 8b of the arc tube 2 to start the arc tube.

The specific structure of a high-pressure sodium lamp is shown in Figure 2. The arc tube 2 is held within the outer tube 1 by a support 10, and the unitized starting device 3 is held on this support 10. As shown in FIG. 3, the starting device 3 unit covers the surface of a current limiting resistor 5 made of a ceramic resistance heating element or a metal heating element with a ceramic insulation coating 11 made of alumina, silica, etc. Metal brazing filler metal 12a, 12 on the surface of
metal lead rods 13 and 14 via b and 12c, respectively.
and 15 are connected. metal lead rod 13,
14 are electrically connected to both ends of the current limiting resistor 5, and one metal lead rod 13 is mechanically and electrically connected to the support 10. A bimetal piece 16 is welded to the other metal lead rod 14, and a movable contact 1 is attached to the tip of this bimetal piece 16.
7 is connected. Remaining metal lead rod 1
5 is electrically insulated from the current limiting resistor 5 and stands upright on the ceramic cover 11, and this metal lead rod 15 forms a fixed contact with which the movable contact 17 is connected and separated, and is connected to the electrode 8a. electrically connected. The support 10 is connected to one stem lead 18, and the electrode 8a is connected to the other stem lead 1.
Connected to 9. The other electrode 8b is connected to the support 10. 20 indicates a cap.

At the time of starting, the bimetal piece 16 is returned to its original position and the movable contact 17 is in contact with the metal lead rod 15 as a fixed contact, so when the voltage from the power source 7 is applied, current flows through the current limiting resistor 5, that is, as shown in FIG. In the starting device 3, current flows through the metal lead rod 13, the current limiting resistor 5, the metal lead rod 14, the bimetal piece 16, the movable contact 17, and the metal lead rod 15.
6 is heated and the movable contact 17 is separated from the metal lead rod 15 due to the bending of the bimetal piece 16, so that a pulse voltage based on the kick voltage is generated.

By the way, in the starting device 3 having such a configuration, the metal lead rods 13, 14, and 15 each touch the metal brazing material 1 to the ceramic coating 11.
They are joined via 2a, 12b and 12c. Therefore, on the outside of the ceramic covering 11, the metal brazing materials 12a, 12b and 12c
The distance between them is relatively close.
However, at the moment when the bimetal switch 4 is opened, mutually opposite potentials are applied between the metal lead rods 13 and 15, and the pulse voltage accompanying the opening of the bimetal switch 4 is applied to these metal lead rods. It is applied between 13 and 15. For this reason,
A creeping discharge may occur on the surface of the ceramic coating 11 between the metal brazing materials 12a and 12c located at the shortest distance. In particular, the metal brazing filler metals 12a, 12
If c is formed into a rectangular shape, creeping discharge is likely to occur because the corners become edges between opposing corners and become bright spots of discharge. Such creeping discharge grows between the surface of the ceramic covering 11 and other parts of the outer bulb 1 at different potentials, and tends to cause outer bulb discharge and gas release.

[Object of the Invention] The present invention was made based on the above circumstances, and its object is to provide a metal vapor discharge lamp that prevents creeping discharge from occurring on the surface of a ceramic coating and prevents outer bulb discharge. This is what we are trying to provide.

[Summary of the invention]

The present invention prevents electrical discharge between conductive members with different potentials by setting the shortest distance between the conductive members with different potentials to be 3 mm or more, and further forming opposing parts of the brazing metal with a radius of at least 0.5 mm. This is what I did.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings. The overall structure of the high-pressure sodium lamp according to the present invention is shown in FIG. 2, in which the arc tube 2 is held by a support 10 within the outer tube 1.
As shown in FIG. 3, this support 10 holds a unitized starting device 3 in which a thermally responsive switch and a current limiting resistor are connected in series. Here, the current limiting resistor is made of, for example, a ceramic resistance heating element or a metal heating element, the surface of which is covered with a ceramic insulation coating 11 made of alumina, silica, or the like. Further, as shown in the same figure and FIG.
It is electrically connected to the current limiting resistor 5 via a, 12b, and 12c. These metal lead rods 14, 15
A thermally responsive switch 4 made of, for example, a bimetal is provided between them, and when the arc tube is started, the movable contact 17 of the thermally responsive switch 4 contacts the metal lead rod 15, and the current limiting resistor 5 generates heat. In this case, the movable contact 17 is separated from the metal lead rod 15 so that a pulse voltage based on the kick voltage is generated.

In the starting device 3 shown in FIG. 4, the metal lead rods 13 and 15 are at different potentials, and in this case, the shortest distance l is between the metal brazing fillers 12a and 12c. In this embodiment, the distance between the metal brazing materials 12a and 12c, which is the shortest distance 1, is set to 3.
mm or more, and furthermore, the metal brazing filler metals 12a, 12
Corners 12aa, 12ab, 12 facing each other between c
ca and 12cb are formed into curved surfaces having a radius of at least 0.5 mm.

The reason for restricting the shortest distance l to 3 mm or more is based on the experience of the inventors. In other words, for high-pressure sodium lamps or metal halide lamps, the voltage is 1000 to 3000V at startup.
Starting is possible by applying a pulse voltage peak value of about 1000~
For a pulse voltage of 3000V, the above shortest distance l is 3
It has been confirmed that creeping discharge does not occur if the thickness is larger than mm.

Also, the corner portions 12aa of the metal brazing materials 12a and 12c,
When 12ab, 12ca, and 12cb are made into curved surfaces with a radius r of 0.5 mm or more, there are no edge portions, thereby preventing concentration of the electric field, and thus preventing these portions from becoming a source of creeping discharge.

In the above embodiment, the corner portions 12aa, 12ab,
12ca and 12cb were formed into curved surfaces with a radius of 0.5 mm or more, but for example, if the entire metal brazing material
Even if it is formed into a circular shape with a radius of 0.5 mm or more, creeping discharge can be prevented.

In addition, the present invention can be carried out with a high-pressure mercury lamp in addition to a high-pressure sodium lamp or a metal halide lamp, and the starting device uses a glow lighting tube, a current-limiting resistor, and a normally closed thermal response switch. is also possible. Furthermore, the inside of the outer tube may be a vacuum or may be filled with gas.

〔Effect of the invention〕

In the present invention, the shortest distance between conductive members with different potentials is set to 3 mm or more, and the opposing portions of the brazing metal are formed to have a radius of at least 0.5 mm, so that high voltage pulses are not applied during startup. Even if the conductive members have different potentials, creeping discharge and the like will not occur between the conductive members, and therefore, outer tube discharge, gas release, etc. can be prevented, and safety will be improved.

[Brief explanation of drawings]

Figures 1 to 3 are for explaining the prior art, in which Figure 1 is a circuit diagram, Figure 2 is a schematic diagram, Figure 3 is a perspective view of the starting device, and Figure 4 is a diagram of the present invention. FIG. 2 is a plan view of a starting device showing one embodiment. 1... outer tube, 2... arc tube, 3... starting device,
4...Thermal response switch, 5...Current limiting resistor, 11...
...Ceramic covering, 12a, 12b, 12c...
...Metal brazing filler metal, 13, 14, 15...Metal lead rod.

Claims (1)

[Claims] 1. In a metal vapor discharge lamp in which a starting device comprising at least a thermally responsive switch and a current limiting resistor connected in series is connected in parallel to the arc tube, and the starting device and the arc tube are housed in an outer bulb, the above-mentioned The current limiting resistor is covered with a heat-resistant insulator, and a conductive member is led out from the heat-resistant insulator through a metal brazing material provided on the surface of the heat-resistant insulator, and the shortest distance between the conductive members of different potentials is A metal vapor discharge lamp characterized in that the metal brazing material is formed to have a radius of 3 mm or more, and the opposing metal brazing material has a radius of at least 0.5 mm.