JPS61250960A - High pressure metal vapor discharge lamp - Google Patents

Abstract

PURPOSE:To surely prevent burning of a ballast by connecting in parallel a safety device comprising a series circuit of a usually-open type thermal action switch and a heating filament to a luminescent tube. CONSTITUTION:A safety device comprising a series circuit of a usually-open type thermal action switch 20 and a heating filament 21 is connected in parallel to a luminescent tube 3 which is accommodated in an outer tube 1 whose inside is evacuated, and the filament 21 is brought into contact with a stem 15 of the outer tube or closely arranged near the stem 15. If the luminescent tube leaked during lighting, the same voltage as lamp voltage is applied to the switch 20 and glow discharge is taken place and the switch is closed. Current flows to the filament to heat it and a hole is produced on the wall of the outer tube or the stem by this heat, and a large amount of air is introduced inside the outer tube. Thereby, the luminescent tube is turned off and burning of a ballast is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a high-pressure metal vapor discharge lamp having an arc tube made of a translucent ceramic tube.

[Technical background of the invention and its problems]

A high-pressure metal vapor discharge lamp using a translucent ceramic tube as an arc tube, for example, an arc tube in which a rare gas for starting, such as xenon gas, sodium as a luminescent metal, and mercury as a buffer metal, are sealed in the translucent ceramic tube. A high-pressure sodium lamp is made of a sealed outer tube with an evacuated interior.

Due to its high luminous efficiency, it has become rapidly popular in recent years. This lamp is normally lit by connecting a choke coil type ballast in series, which consists of multiple layers of insulated metal wire wound around an iron core.

By the way, in the above-mentioned lamp, a leak may occur in the hermetically sealed portion of one arc tube at the end of its life. In particular, if a leak occurs during lamp lighting, not only the enclosed rare gas but also mercury and sodium vaporized within the arc tube will leak into the outer bulb. As a result, the buffer metal mercury in the arc tube decreases, and the parallel free paths of ions and electrons between the electrodes become longer.

The potential gradient or lamp voltage is significantly reduced.

For example, 1 normal lamp rated voltage is 100~130VK
The voltage decreases to about 20V to 40V compared to the set value. From the perspective of the ballast, this is equivalent to a state in which the secondary side is almost short-circuited. Normally, in a choke coil type ballast, the secondary short circuit current is approximately 180% of the lamp rated current.
Corresponds to %. Therefore, if the lamp voltage continues to be lit for a long time with an abnormally low voltage, the windings and iron core of the ballast will heat up and the insulation between the two windings will deteriorate, and as early as 3 hours after a short circuit. At a certain level, the above-mentioned insulation is broken, the current limiting function is lost, and an excessive current flows through the lamp, which may damage the arc tube or outer tube, or cause burnout of the ballast.

As a countermeasure against leakage in the arc tube, for example, Japanese Patent Application Laid-Open No. 55-124941 discloses a high-voltage starter equipped with a heat-responsive switch-type starter consisting of a series circuit of a resistor and a bimetal switch in parallel with the arc tube. In a sodium lamp, if an arc tube leaks by attaching an electron radioactive substance to the resistor, the thermoelectrons emitted from the electron radioactive substance will ionize the xenon gas leaking into the lamp outer bulb, A method is disclosed in which a discharge is caused using the xenon ions thus generated as a medium, thereby causing the resistor to melt and interrupting the starting circuit, thereby stopping the starting of the leaking lamp.

However, this method prevents burnout of the ballast by interrupting the circuit of the thermal switch-type starting device built into the lamp with a leaky arc tube and preventing the lamp from starting. The arc tube leaks,
This was completely useless in preventing ballast burnout that would occur if the lamp was left on for a long period of time. [Object of the Invention] The present invention was made in response to the above-mentioned circumstances.

To provide a high-pressure metal vapor discharge lamp capable of surely extinguishing the lamp and preventing burnout of a ballast when the lamp continues to be lit even if the arc tube leaks while the lamp is lit.

[Summary of the invention]

A safety device consisting of a series circuit of a normally open type response switch and a heat generating filament is connected electrically in parallel with the arc tube housed in the outer tube whose interior is evacuated, and the heat generating filament is brought into contact with the stem portion of the outer tube. Or, by placing them close together, if the arc tube leaks and the enclosed material leaks into the outer tube while the lamp is on, the normally open type response switch has a voltage equal to the lamp voltage applied to it, so it will not glow. An electric discharge is generated and the filament closes, and electricity is applied to the filament 1 to generate heat.The heat causes holes or cracks in the wall or stem of the outer tube to introduce a large amount of air into the outer tube, thereby causing the arc tube to close. This is to prevent the ballast from burning out by turning off the light.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.
“ Figure 1 is an explanatory diagram of the configuration of a high-pressure sodium lamp with a built-in starting device compatible with a 400W mercury lamp ballast, and Figure 2 is an enlarged view of the main parts. The outer tube is evacuated to a relatively high vacuum and has a cap (2) attached to one end, and (3) is a luminous tube. Both ends of the tube (4) made of translucent ceramics, such as alumina ceramics, are connected to electrodes (5a),
Closed bodies (6a) and (6b) supporting (5b) are hermetically sealed via K-type glass solder, and a rare gas for starting, such as xenon gas, and buffer metal fittings, such as mercury and sodium, are sealed inside. ing. (7) is a starter device that is electrically connected in parallel with the arc tube (3), and is a normally closed type responsive switch (9) assembled on an insulating substrate (8).
) and a coiled filament-shaped resistance heating element a connected electrically in series, one end of this starting device (7) is connected to one electrode of the arc tube (5b) via a conductor (11).
) to the electrical inlet (connect to I).

The other end is connected to an arc tube support (14) K which also serves as an electricity introducing body to the other electrode (5a) via a conductor 0.

In addition, the above-mentioned electricity introducing body (I and arc tube support (14)
Stem α51fC that seals the opening of the t-i outer tube (1)
Connected to one end of each of the implanted outer tube introduction wires (16) and (17), these outer tube introduction wires as,
? ) is connected to the cap (2) K.

The rice cake is a proximal conductor arranged along the longitudinal direction on the outer surface of the arc tube (3).

Incidentally, aS is a safety device which is an important part of the present invention, and is composed of a series circuit of a normally open type responsive switch handle and a heat generating filament (21). The normally open type responsive switch (A) has a thickness of 0.
A pair of 15mm bimetal pieces (22A), (22
B), and the opposing surfaces thereof include contacts (23A) and (23B) made of a fusible material such as nickel, and barium Ba (23B), an electron-emissive substance obtained by thermally decomposing barium azide BaN6, for example. 24A),
(24B) is deposited. Further, the heating filament (21) has a diameter of 0. It is made of β inkstone tungsten wire, one end (21a) of which is one bimetal piece (22A) K,
The other end (21b) is connected to one outer tube introduction line (L6) by winding the stem haze. Additionally, add the other bimetal piece (
22B) is connected to the other outer tube lead-in line αη via the conductor a3 and the arc tube support (14). (25) are the above-mentioned bimetal pieces that also serve as heat shields (22A), (22
B) For installation, use the appropriate insulated board.

It serves to cut off radiant heat so that the normally open thermally responsive switch (a) will not be activated by the radiant heat from the arc tube (3) while it is lit.

Although a lamp with such a configuration is not shown, when it is connected to an AC power source via a single-choke type mercury lamp ballast for a 200V class AC power source, the normally closed thermal response switch of the starting device (7) is activated before starting the lamp. Since (9) is closed, the resistance heating element (l) generates heat when energized, and this heat causes the normally closed thermally responsive switch (9) to open, and the kick voltage when this opens generates a high voltage pulse in the ballast. However, by applying this high voltage pulse, a steep potential gradient is created between the adjacent conductor 08 and one electrode (5b) having an opposing potential, promoting the generation of arc discharge in the second arc tube (3), and lighting it. It comes to that.

In such a lamp, if the luminous tube (3) leaks during zero lighting and the sealed xenon gas leaks into the outer tube (1) and fills it, the pair of normally open thermally responsive switches of the above-mentioned safety device will shut off. A glow discharge occurs between the bimetal pieces (22A) and (22B), and the generated heat causes the bimetal pieces (22A) and (22B) to
(22B) is deformed and both contacts (23A), (23
B) comes into contact and the first heating filament (21) is energized and generates heat. Due to this heat, the above bimetal piece (22A)
, Based on the deformation of (22B) (both contacts (23A)
, (23B) is kept in contact with the 9 heating filament (2
1) continues to generate heat, and this heat causes the heating filament (
The stem α9 glass around which the stem 21) is wound becomes instantly softened and dented by the outside air, and the K eventually breaks, allowing air to enter the outer tube (1). This air also enters the leaking arc tube (3), so the lamp goes out immediately.

Moreover, since it will never turn on again after that, burnout of the ballast is completely prevented.

In addition, since the heat generating filament (21) also oxidizes when exposed to air and becomes Wlr#I early, there is no need to provide it with a current limiting function, and if a tungsten wire with a wire diameter that does not melt at the short circuit current of the ballast is used. Since the length may be short, it is preferable from the viewpoint of assembly work and vibration resistance.

Next, safety devices were tested for each of the above example lamps and 20 conventional lamps (excluding 19 lamps) from this example lamp.
Comparative test results are shown. The test method was to make the strength of the hermetic sealing part of each lamp weak in advance so that the arc tube would leak within a short time after being lit, and then a lighting test was conducted. When the arc tube of each lamp leaks, the pressure inside the outer tube of the xenon gas leaked into the outer tube is approximately 1. It becomes O Thor. The test results show that in the case of the example lamp, when the 9 arc tube leaks, the safety device (19) is activated and air enters the outer bulb and the arc tube, causing all the lamps to go out. On the other hand, in the case of the conventional lamp, even if one arc tube leaked, the lighting continued, and as a result, the ballast burned out in half of the 10 bulbs.

Note that the present invention is not limited to the above-mentioned embodiments; for example, the heat-generating filament (21) may be placed close to the stem (15) without being wound, or the heat-generating filament (21) may be placed close to the stem (15) without being wound. It may be placed in contact with or close to the wall of the outer tube (1), and in case of an emergency, the outer tube wall may be damaged and leakage may occur.Also, do not incorporate other lamps or starting devices with different inputs. Not to mention various high-pressure sodium lamps such as lamps and lamps that do not apply pulses at startup.

n) It can also be applied to other high-pressure metal vapor discharge lamps in which metals other than IJum, metal halides, etc. are sealed in translucent ceramic arc tubes.

〔Effect of the invention〕

As detailed above, according to the present invention, nine arc tubes leak,
If the inner pressure of the outer tube leaks due to the enclosed material, a safety device consisting of a normally open heat-responsive switch and a heat-generating filament is activated to introduce busy air into the lamp and turn off the lamp, thereby reliably preventing burnout of the ballast. I can do it.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of a high-pressure sodium lamp which is an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the configuration of the main parts thereof. (1)... Outer tube, (3)... Arc tube. (7)...Starting device, exhaust...stem. αI・・・Safety device.翰... Always open form response switch.

Claims (1)

[Claims] A light-transmitting ceramic tube is provided with a pair of electrodes, and a luminescent tube in which a starting rare gas and at least a luminescent metal are sealed inside is housed in an outer tube whose opening is sealed with a stem and whose interior is evacuated.
A safety device consisting of a series circuit of a normally open heat-responsive switch and a heat-generating filament is connected electrically in parallel with the arc tube, and the heat-generating filament is connected to or in close proximity to the wall or stem of the outer bulb. A high-pressure metal vapor discharge lamp characterized by the following: