JPH0447897Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is a compact high-pressure metal vapor discharger such as a metal halide lamp or a high-pressure sodium lamp, which houses an arc tube and a preheater for preheating the arc tube in the outer envelope. Regarding electric lights.

[Conventional technology]

Vehicle headlights have conventionally used incandescent light bulbs as their light source, but incandescent light bulbs have drawbacks such as low luminous efficiency and short lifespan, and the lamps must be replaced frequently.

For this reason, research has recently been underway to use compact high-pressure metal vapor discharge lamps, such as metal halide lamps and high-pressure sodium lamps, which have high efficiency, long life, and are easy to downsize, as light sources for headlights.

When using the above-mentioned small high-pressure metal vapor discharge lamp as a light source for a headlamp, the amount of consumption of the discharge lamp is 100W
(W) It is desirable that the size be as follows.

By the way, when the above-mentioned small high-pressure metal vapor discharge lamp, such as a small metal halide lamp, is used as a light source for a vehicle headlamp, instantaneous lighting and instantaneous luminous flux rise characteristics become a problem. As a countermeasure for instantaneous lighting, the application of high-voltage pulses has become more likely to be realized, but there is a need for further improvement regarding the rise of the luminous flux.

Conventionally, a method has been considered in which the arc tube is heated with a heater. For example, Japanese Patent Laid-Open No. 51-4881 discloses a technique in which a heat-retaining heater is placed near the coldest part of the arc tube. However, the purpose of the invention disclosed in the above publication is to adjust the color temperature of the lamp by changing the amount of heat generated by the heater by changing the current flowing through the heater, and by arbitrarily changing the temperature of the coldest part of the arc tube from the outside. However, it is also thought to be related to the improvement of the luminous flux rise of the lamp, which is the problem mentioned above.

In other words, if a heater is installed near the arc tube and the heater is used to heat the arc tube in advance, the evaporation of the metal sealed inside the arc tube will be promoted, so the luminous flux will rise immediately when starting with a high-pressure pulse. It is something.

If a coil heater made of tungsten is used as the preheating heater as described above, when a high-voltage pulse is applied between the heater and the arc tube lead wire at the time of starting, internal discharge may occur inside the outer tube, or the tungsten coil heater may It evaporates due to heat generation, leading to early blackening. Therefore, it is desirable to use a so-called ceramic heater, in which a tungsten coil is covered with ceramic, as the preheating heater.

For example, a small metal halide lamp with such a configuration is attached to the top of the reflector of the headlamp, so the outer bulb has a sealed structure at one end, and the arc tube is attached to this sealed part. A structure is employed in which a pair of support wires that mechanically support the power supply and serve as power supply lines are sealed together, and a pair of preheating heater lead wires connected to the preheating heater are sealed. Therefore, the preheating heater has a so-called cantilever support structure in which it is supported by a pair of preheating heater lead wires within the outer tube.

[The problem that the idea aims to solve]

However, vehicle headlights are extremely frequently subjected to shocks and vibrations while driving, and for this reason,
Shocks and vibrations are also transmitted to the preheating heater. If the preheater has a cantilever structure supported by a pair of preheater lead wires, the preheater will vibrate when subjected to impact or vibration, and may hit the arc tubes placed close to each other or cause damage to the outside. There are concerns that it may hit the inner surface of the tube, peel off the ceramic coating, or even generate ceramics at the sealing part of the outer tube.

In addition, in the case of the above-mentioned compact high-pressure metal vapor discharge lamp, the outer bulb is also small, so the arc tube and the support wire, which also serves as a power supply line and mechanically supports the arc tube, tend to come close to each other. Become stronger. In this way, support wires that also serve as power supply lines are routed to the side of the arc tube, and when these wires approach each other, the luminescent metals sealed inside the arc tube are attracted to the support wires during lighting, and atoms such as sodium, for example, Substances with a small radius pass through the quartz that makes up the arc tube bulb and disappear, and even substances whose atoms are too large to pass through the quartz are attracted to the walls of the quartz bulb and cause early blackening. Become.

Therefore, the purpose of the present invention is to strengthen the mechanical support of the preheater, improve the heating efficiency of the arc tube by the preheater, and also cause the luminous metal sealed inside the arc tube to be attracted to the support wire. The present invention aims to provide a small-sized high-pressure metal vapor discharge lamp in which the amount of energy used is reduced.

[Means to solve the problem]

In the present invention, an arc tube and a preheating heater disposed near the arc tube to preheat the arc tube are housed in the outer tube, and the arc tube is connected to a support wire that is routed on the side of the arc tube. In the compact high-pressure metal vapor discharge lamp supported by the support wire, the preheating heater includes a heating element covered with an insulator, and the preheating heater is arranged at a position where the heating element faces the arc tube and emits less light than the support wire. At least a portion of the insulator is located closer to the arc tube than the support wire and is attached to the support wire.

[Effect]

According to the present invention, the preheating heater is not only supported by a pair of preheating heater lead wires, but also supported by a relatively strong support wire, so the supporting strength is improved and the preheating heater is not subjected to shock or vibration. Also, there is less vibration in the preheater. Moreover,
This preheating heater has its heating element facing the arc tube,
In addition, since it is located closer to the arc tube than the support wire, it is relatively close to the arc tube, making it easier to effectively transfer heat generated as radiant heat to the arc tube. Although it is a member, it is insulated by an insulator, so the effect of attracting the luminescent metal inside the arc tube is reduced.

[Example of idea]

The present invention will be explained below based on an embodiment shown in FIGS. 1 and 2.

FIG. 1 is a diagram showing a schematic configuration of a metal halide lamp with a rating of 35 W that is lit by a DC power source, and 1 is an outer bulb. The outer tube 1 has a sealing part 1a at one end.
The sealing portion 1a side is attached to the top of the reflector of the headlamp through a cap (not shown), and the tube axis is used with the tube axis facing in a substantially horizontal direction.

Inside the outer tube 1, an arc tube 2 and a preheater 3 are housed.

The arc tube 2 has an anode 4a and a cathode 4b disposed opposite to each other at both ends inside a bulb made of quartz glass.
molybdenum foil 6a, hermetically sealed to a, 5b;
It is connected to arc tube lead wires 7a and 7b via 6b. The arc tube lead wires 7a, 7b are welded to support wires 8a, 8b made of tungsten or the like.
is passed through the sealing portion 1a of the outer tube 1 in an airtight manner. Therefore, the arc tube 2 is connected to the support wire 8.
It is mechanically supported by support wires 8a and 8b, and connected to a power source by these support wires 8a and 8b.

Inside the arc tube 2, a starting rare gas, mercury, scandium metal, and metal halides such as scandium iodide and sodium iodide are sealed.

Such an arc tube 2 has an outer tube 1 placed in such a position that the anode 4a and the cathode 4b are along the tube axis, that is, the anode 4a and the cathode 4b are positioned horizontally.
is housed within.

The preheater 3 is a ceramic heater formed by covering a heating element 9 made of tungsten with a ceramic 10, and has a flat plate shape, for example. Such a preheater 3 is located below the arc tube 2.
It is installed at a distance of 0.1 mm to 1.2 mm from the arc tube 2, and its flat upper surface faces the lower surface of the arc tube 2.

The tungsten heating element 9 of the preheater 3 is connected to preheater lead wires 11a and 11b, and these preheater lead wires 11a and 11b are passed through the sealing portion 1a of the outer tube 1 in an airtight manner.

As shown in FIG. 2, the preheater 3 has an insertion hole 1 extending in the tube axis direction in the coating layer of the ceramic 10.
2 is formed, and the inner diameter of this insertion hole 12 is formed larger than the outer diameter of the support wire 8a. One of the support wires 8a is loosely inserted into the insertion hole 12. The base of the support wire 8a leading out from the insertion hole 12 is filled with heat-resistant insulators 13, 13 such as alumina, silica, or magnesia, thereby joining the preheater 3 to the support wire 8a.

In this case, the support wire 8a is inserted through the tungsten heating element 9 on the side other than the arc tube, that is, on the side opposite to the arc tube 2 with the tungsten heating element 9 in between.

Therefore, as shown in FIG.
The heating element 9 is closer to the arc tube 2 than the support wire 8a.
located on the side and this support wire 8a
On the arc tube 2 side, a coating layer of ceramic 10, a heating element 9, and a ceramic 10 are placed toward the arc tube 2.
The support wire 8a is insulated from the arc tube 2 by the ceramic coating layer 10.

Note that at least one of the support wires 8a and 8b is covered with an insulator such as a glass tube 14 to prevent discharge inside the outer tube, and the preheating heater lead wires 11a and 11b are also covered with an insulator to prevent discharge inside the outer tube. , covered with an insulator such as a glass tube 15.

The operation of such a configuration will be explained.

By applying a high voltage pulse powered by a DC power source to the support wires 8a and 8b, the anode 4a
DC discharge begins between the cathode 4b and the cathode 4b.

At this time, if the preheater 3 is energized in advance to generate heat, the arc tube 2 is heated by the preheater 3, and the mercury, scandium metal, and metal halide sealed in the arc tube 2 are converted into Since scandium oxide and sodium iodide have been evaporated, a predetermined luminous flux can be obtained almost at the same time as starting. That is, since the lamp luminous flux is determined by the vapor pressure of the enclosed metal, by the time the lamp is started due to the steam accelerating action of the steam heater 3, the vapor pressure is already sufficient, and the instantaneous luminous flux can rise.

Therefore, the preheater 3 of this embodiment is not only mechanically supported by the pair of preheater lead wires 11a and 11b, but also supported by the support wire 8.
Since it is also supported by a, the support strength of the preheater 3 is improved. Normally the support wires 8a, 8b are
Since wires having a larger diameter than the arc tube lead wires 7a, 7b and the preheater lead wires 11a, 11b are used, the preheater 3 is firmly supported. Therefore, when used as a light source for a vehicle headlamp, even if shock or vibration is transmitted, the support wire 8a will share the support, preventing the installation position of the preheater 3 from shifting or tilting. At the same time, the vibration of the preheater 3 is reduced, and problems such as hitting the arc tube 2 disposed close to it, hitting the inner surface of the outer tube 1, and peeling off the ceramic coating 10 are prevented. . In addition, since the vibration of the preheating heater 3 is reduced, the preheating heater lead wire 11
Unreasonable stress is not generated in the outer tube sealing portion 1a of the tubes a and 11b, and cracks are not generated in the sealing portion 1a.

Note that since the support wire 8a is provided on the opposite side of the arc tube 2 with the tungsten heating element 9 in between, the infrared rays are not blocked when the preheater 3 heats the arc tube 2, and the arc tube 2 does not impede heating efficiency. Further, the support wire 8a connects the ceramic 10 of the preheater 3 to the arc tube 2.
Since it is electrically insulated by the coating layer, the proportion of the luminescent metal housed in the arc tube 2 drawn to the bulb wall by the energized support wire 8a is reduced, and sodium with a small base paper radius escapes from the quartz bulb and other luminescent metals Problems such as metal adhesion to the valve wall and blackening are prevented. Also,
Since the heating element 9 of the preheater 3 is also electrically insulated by the ceramic coating layer, the heating element 9 that is energized
The effect of attracting the luminescent metal inside the arc tube 2 toward the bulb wall is reduced.

In other words, the ceramic coating layer 10 functions as a mounting base for the heating element 9, as an insulating coating for the heating element 9, and as an insulating function for the support wire 8a, thereby simplifying the structure. In addition, the support wire 8a is loosely inserted into the insertion hole 12 formed in the preheater 3, and is connected at the root portion leading out from the insertion hole 12 with heat-resistant insulators 13, 13 such as alumina, silica, or magnesia. Therefore, the contact area between the preheater 3 and the support wire 8a is smaller than when the two are in close contact with each other, and therefore, the heat of the preheater 3 is difficult to be transmitted to the support wire 8a, and the heat loss of the preheater 3 is small. At the same time, there is no fear that the support wire 8a will be excessively heated.

In this embodiment, since the outer tube 1 is turned on horizontally and the preheater 3 is placed below the arc tube 2, the arc tube 2 receives convection heat as well as radiant heat from the preheater 3. Heating efficiency is improved.

Note that the present invention is not limited only to the steam embodiment.

FIG. 3 shows another embodiment of the present invention,
The preheater 3 is attached to the support wire 8a by metal bands 20, 20. In this case, the preheater 3 and the support wire 8a are
It is desirable to interpose heat-resistant insulators at several points in the contact portion of a.

In the above embodiment, a case has been described in which the preheater 3 is formed into a flat plate shape, but the present invention is not limited to this, and may be formed into a V-shape or a U-shape.

Furthermore, the present invention is applicable not only to metal halide lamps, but also to other small high-pressure metal vapor discharge lamps, such as high-pressure sodium lamps, which are lit horizontally by applying a high-pressure pulse at startup, and can also be applied to lamps that are lit with direct current. It's not limited either.

Furthermore, the preheating heater may be de-energized to stop heating after the arc tube is lit.

Furthermore, the compact high-pressure metal vapor discharge lamp of the present invention is
It is not limited to use as a vehicle headlight light source,
It may also be used as a light source for general lighting.

[Effect of idea]

As explained above, according to the present invention, since the preheating heater is supported by the support wire, the support strength of the preheating heater is improved, and the installation position of the preheating heater is prevented from being displaced or tilted even if shock or vibration is transmitted. At the same time, the vibration of the preheater is reduced,
This prevents problems such as hitting the arc tubes disposed close to each other, hitting the inner surface of the outer tube, and peeling off the ceramic coating. In addition, since the vibration of the preheating heater is reduced, undue stress is not generated on the outer tube sealing part through the preheating heater lead wire connected to the preheating heater, and cracks are not generated in the sealing part. It will have a long life. Moreover, the preheating heater is located so that its heating element faces the arc tube and is located closer to the arc tube than the support wire, so it is relatively close to the arc tube, and therefore effectively converts the heat generated into radiant heat to the arc tube. can be transmitted and has good heating efficiency. Furthermore, although the heating element and the support wire are current-carrying members, they are insulated by the insulator of the preheater, so the effect of attracting the luminescent metal inside the arc tube is reduced.
It is possible to prevent devitrification of the luminescent metal and blackening due to adhesion to the tube wall. In this case, the insulator of the preheater insulates the heating element of the preheater and also insulates the support wire, which simplifies the structure.

[Brief explanation of the drawing]

Figures 1 and 2 show one embodiment of the present invention, with Figure 1 being a schematic diagram of the overall configuration, Figure 2 being a sectional view of the arc tube and preheater, and Figure 3 being another embodiment of the present invention. It is a perspective view showing an example. DESCRIPTION OF SYMBOLS 1... Outer tube, 1a... Sealing part of outer tube, 2... Arc tube, 3... Preheating heater, 4a... Anode, 4b...
...Cathode, 7a, 7b...Earth tube lead wire, 8a,
8b...Support wire, 9...Tungsten heating element, 10...Ceramic, 11a, 11b...
Preheating heater lead wire, 12...Insertion hole, 13...
Heat-resistant insulator, 20... band.

Claims (1)

[Claims for Utility Model Registration] An arc tube and a preheating heater disposed near the arc tube to preheat the arc tube are housed in the outer bulb, and the arc tube is routed to the side of the arc tube. In a small high-pressure metal vapor discharge lamp supported by a support wire, the preheating heater has a heating element covered with an insulator, and the preheating heater is provided at a position where the heating element faces the arc tube and is supported by a support wire. A small high-pressure metal vapor release device characterized in that the insulator is located closer to the arc tube than the support wire and at least a part of the insulator is attached to the support wire. electric light.