JPH0316208Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a small high-pressure metal vapor discharge lamp such as a metal halide lamp or a high-pressure sodium lamp of 100W or less.

[Conventional technology]

For example, incandescent bulbs have traditionally been used as the light source for vehicle headlights, but incandescent bulbs have drawbacks such as low luminous efficiency and short lifespan, and the lamps must be replaced frequently. There is a problem with this.

On the other hand, discharge lamps are known as light sources with high luminous efficiency and long life. For example, fluorescent lamps, which are low-pressure discharge lamps, are used as interior lights in buses and trains. However, even if it is attempted to use a fluorescent lamp as a headlamp light source, it is too large to be applied.

For this reason, research is underway to use high-pressure metal vapor discharge lamps, such as metal halide lamps and high-pressure sodium lamps, as light sources for headlights, which have higher luminous efficiency than fluorescent lamps and are easier to miniaturize. .

When using such high-pressure metal vapor discharge lamps, the power consumption of the discharge lamp should be 100W or less, taking into account the size of the headlight, the required luminous intensity, and the vehicle's battery consumption. is preferred.

However, when such a small high-pressure metal vapor discharge lamp, such as a metal halide lamp, is used as a light source for a headlamp, there are the following problems.

That is, since the headlights are turned on just before the vehicle departs or when the vehicle enters a tunnel, they must be turned on instantly, and the rise time of the luminous flux must be short to reach a predetermined brightness quickly.

As a countermeasure for instantaneous lighting of small high-pressure metal vapor discharge lamps, a technique is known in which the lamp is started by applying a high-pressure pulse, and if a high-pressure pulse application method is adopted, it can be put to practical use as a headlamp.

However, even when the lamp starts, the mercury and metal halides sealed in the arc tube hardly evaporate, so the lamp brightness is only about 10% of the stable lighting condition. It takes 3 to 10 minutes to reach sufficient brightness, and it takes time for the so-called luminous flux to rise, making it difficult to put it into practical use.

As a means of solving the luminous flux rise problem, a method of heating the arc tube with a heater has been considered. 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.

Therefore, a heater is installed near the arc tube,
If the arc tube is heated in advance by this heater before starting, the evaporation of the metal sealed inside the arc tube is promoted, so that the luminous flux quickly rises at the same time as starting.

However, in lamps manufactured by such means, the outer tube is constructed in a small size, and the arc tube and preheater are housed in the outer bulb in such a small space. There is a concern that the preheating heaters and the arc tube lead wire and the preheating heater lead wire are close to each other, and that an electric discharge inside the outer tube may occur when a high voltage pulse is applied for starting. In order to prevent such discharge inside the outer tube, it is conceivable to configure the preheater with a ceramic heater, or to cover the arc tube lead wire and the preheater lead wire with an insulator such as a glass tube.

[Problem that the invention attempts to solve]

However, when a high-voltage pulse is applied during startup, defective discharge may occur not only inside the outer bulb, but also between the arc tube lead wire and preheater lead wire led outside the outer bulb. be.

In other words, the arc tube lead wire and preheating heater lead wire are led out by passing through the crushed seal formed at the end of the outer tube in an airtight manner. A total of four lead wires are lined up in a straight line from the end surface of the tube sealing part, and are linearly led out in parallel to the tube axis direction. And when a high voltage pulse is applied,
Since defective discharge is likely to occur between a pair of arc tube lead wires, these arc tube lead wires are placed on both outer sides of the end face of the outer bulb sealing part so that these arc tube lead wires are furthest away from each other. A pair of preheating heater lead wires are arranged at a distance from each other near the center between them.

Even with this arrangement, if the height of the applied pulse becomes high, discharge outside the outer tube may occur between one of the arc tube lead wires and the preheater lead wire that are adjacent to each other.

In such a defective discharge, since energy is consumed by the discharge, no arc discharge is generated within the arc tube, and the state of corona discharge continues, and the starting circuit continues to generate a pulse voltage. If this condition continues, discharge will occur even between the arc tube lead wires that are spaced apart from each other, leading to damage to the lamp.

Further, since the pair of preheating heater lead wires are arranged relatively close to each other, they tend to come into contact with each other, and there is a risk of a short circuit.

Therefore, the present invention aims to provide a compact high-pressure metal vapor discharge lamp that prevents discharge outside the outer bulb and reduces the amount of contact between the preheater lead wires.

[Means for solving problems]

In the present invention, the arc tube lead wire is arranged at an outer position on the end surface of the outer tube sealing part, and the preheating heater lead wire is arranged at a center side position on the end face of the outer tube sealing part. The preheating heater lead wires are bent in a direction perpendicular to the line connecting the arc tube lead wires.

[Effect]

According to such a configuration, since the preheating heater lead wire is bent in a direction perpendicular to the line connecting the arc tube lead wires, the distance between the arc tube lead wire and the preheating heater lead wire increases, and
The distance between the preheating heater lead wires also increases, making it difficult for electric discharge to occur between the arc tube lead wire and the preheating heater lead wire, and reducing the amount of contact between the preheating heater lead wires.

[Example of idea]

The present invention will be described below based on an embodiment shown in the drawings.

FIG. 1 is a diagram showing the schematic configuration of a 35W metal halide lamp that is lit by a DC power source.
1 is an outer tube. The outer tube 1 is provided with a sealing portion 1a at one end, and is used with the sealing portion 1a facing sideways, that is, 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. These arc tube lead wires 7a and 7b pass through the sealing portion 1a of the outer tube 1 in an airtight manner.

The arc tube 2 is filled with a starting rare gas, mercury, and scandium iodide and sodium iodide as metal halides.

The preheater 3 is a ceramic heater in which a heating element is covered with ceramic, and is, for example, shaped like a flat plate and has a power of 40W. Such a preheater 3 is installed below the arc tube 2 at a distance of 0.1 mm to 1.2 mm from the arc tube 2.

The preheating heater 3 has preheating heater lead wires 8a, 8.
These preheating heater lead wires 8a, 8b pass through the sealing portion 1a of the outer tube 1 in an airtight manner.

Note that at least one of the arc tube lead wires 7a and 7b is covered with an insulator such as a glass tube 9 in order to prevent discharge inside the outer bulb, and
The preheating heater lead wires 8a and 8b are also covered with an insulator such as a glass tube 10 to prevent discharge inside the outer tube.

Further, 11 indicates a getter.

Therefore, the arc tube lead wires 7a, 7b and the preheating heater lead wires 8a, 8b are connected to the outer tube 1.
It is derived from the end surface 1aa of the sealing portion 1a formed in the following manner. That is, FIG. 2 shows the arrangement of each of the lead wires on the end surface 1aa of the sealing portion 1a of the outer tube 1. As shown in FIG. Since the sealing portion 1a of the outer tube 1 is crushed and sealed, its end surface 1
aa is approximately rectangular. On this end face 1aa,
The arc tube lead wires 7a and 7b are led out from both outer portions in the longitudinal direction, respectively. The lead-out portions of these arc tube lead wires 7a and 7b extend linearly parallel to the tube axis direction. The lead-out portions of these arc tube lead wires 7a and 7b are covered with an insulator made of, for example, a glass tube 12.

On the end face 1aa of the sealing part 1a, the preheating heater lead wires 8a and 8b are led out from each other at a distance from each other in the longitudinal direction, and are located on the center side in the longitudinal direction. Therefore, these preheating heater lead wires 8a, 8b are the same as the arc tube lead wires 7a, 7b.
It is derived from a position between the two.

The preheating heater lead wires 8a and 8b are made of an insulator made of the glass tube 12, and are connected to the arc tube lead wire 7.
It is bent within the height range covering a and 7b, for example at its base. This bending direction is approximately perpendicular to the line connecting the arc tube lead wires 7a and 7b. In this embodiment, as shown in FIG. 3, the line connecting the arc tube lead wires 7a and 7b is bent toward a perpendicular line H-H passing through the tube axis O. At the position where the line is reached, it is bent again so as to be parallel to the tube axis direction.

The operation of such a configuration will be explained.

When the preheating heater 3 is energized in advance to generate heat, the arc tube 2 is heated by the preheater 3, and the mercury and metal halides sealed in the arc tube 2 are heated, such as scandium iodide and iodide. Accelerates sodium evaporation.

In this state, by applying a high voltage pulse using a DC power source to the arc tube lead wires 7a and 7b, a DC discharge is started between the anode 4a and the cathode 4b.

At this time, the arc tube 2 has already been heated by the preheater 3 to promote the evaporation of mercury and metal halides such as scandium iodide and sodium iodide sealed in the arc tube 2, and the lamp luminous flux is , the rise of the luminous flux is rapid due to the evaporation promoting action of the heater 3, and a predetermined luminous flux can be obtained in an extremely short period of time.

In this type of small lamp, the outer bulb 1 is small and the arc tube 2 and preheater 3 are housed within the outer bulb 1 in a small space. Arc tube lead wires 7a, 7b
and the preheater 3 and the arc tube lead wire 7a,
7b and the preheating heater lead wires 8a, 8b are close to each other. With such a configuration, when a high voltage pulse is applied for startup, there is a risk that an outer-tube discharge may occur. However, since the preheater 3 is composed of a ceramic heater, and the arc tube lead wire 7a and the preheater lead wires 8a and 8b are covered with insulators 9 and 10 such as glass tubes, discharge inside the outer tube is prevented. be done.

In addition, when a high voltage pulse is applied, the arc tube lead wires 7a, 7b and the preheating heater lead wires 8a,
There is also a risk of electrical discharge in the portion of the tube 8b that is led out from the sealing portion 1a, that is, the outside of the outer bulb 1. However, in this embodiment, the preheating heater lead wires 8a, 8 are arranged on the central side of the sealing part end surface 1aa.
b, and the arc tube lead wires 7a, 7 at their bases.
Since the arc tube lead wire 7 is bent in a direction substantially perpendicular to the line connecting b, the arc tube lead wire 7
a, 7b and the preheating heater lead wires 8a, 8b are increased, and the preheating heater lead wires 8
The distance between a and 8b also increases.

Therefore, as the distance between the arc tube lead wires 7a, 7b and the preheating heater lead wires 8a, 8b becomes larger, electric discharge occurs between the adjacent arc tube lead wires 7a, 7b and the preheating heater lead wires 8a, 8b. It becomes difficult. Particularly in the case of this embodiment, the lead-out portions of the arc tube lead wires 7a and 7b are connected to the glass tubes 12 and 1.
Since it is covered with an insulator such as 2, discharge outside the outer tube 1 is reliably prevented.

Furthermore, since the distance between the preheating heater lead wires 8a and 8b is increased, the amount of contact between the preheating heater lead wires 8a and 8b is reduced, and the degree of freedom in connection to external power supply side terminals is increased.

For this reason, undesired discharge is prevented both inside and outside the outer bulb, ensuring arc discharge can be generated within the arc tube, and damage to the lamp can also be prevented.

The present invention is not limited to metal halide lamps, but can be applied to other high-pressure metal vapor discharge lamps, such as high-pressure sodium lamps, which are lit 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.

[Effect of idea]

As explained above, according to the present invention, the preheating heater lead wire placed between the arc tube lead wires is bent in a direction perpendicular to the line connecting the arc tube lead wires, so that the preheating As the distance between the heater lead wires increases, the distance between the preheating heater lead wires also increases, making it difficult for electric discharge to occur between the arc tube lead wire and the preheating heater lead wire, and reducing contact between the preheating heater lead wires. Become. As a result, arc discharge in the arc tube is reliably generated, instantaneous lighting is possible, and lamp damage and short circuits are prevented.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a schematic diagram of the overall configuration, Fig. 2 is a perspective view of the end of the outer tube, and Fig. 3 is a view taken in the direction of the arrow in Fig. 2. . 1... Outer tube, 2... Arc tube, 3... Preheater, 4a... Anode, 4b... Cathode, 5a, 5b...
...Sealing part, 7a, 7b...Earth tube lead wire, 8
a, 8b... Preheating heater lead wire, 9, 10, 1
2...Insulating coating.

Claims (1)

[Claims for Utility Model Registration] (1) An arc tube in which at least one arc tube lead wire is covered with an insulator in the outer bulb, and an arc tube disposed near the arc tube to heat and preheat the arc tube. In a small high-pressure metal vapor discharge lamp, the heater lead wire accommodates a preheater covered with an insulator, and the arc tube lead wire and the preheater lead wire are led out from an end face of a sealing part formed at one end of the outer tube. , the arc tube lead wire is arranged at an outer position on the end surface of the outer tube sealing section, and the preheating heater lead wire is arranged at a center side position on the end surface of the outer tube sealing section, and the preheating heater lead wire is arranged at an inner position of the arc tube lead wire on the end surface of the outer tube sealing section. A compact high-pressure metal vapor discharge lamp characterized in that the preheating heater lead wires are bent in a direction perpendicular to a line connecting the arc tube lead wires. (2) A small high-pressure metal vapor discharge lamp according to claim 1 of the utility model registration claim, characterized in that the arc tube lead wire led out from the end face of the outer bulb sealing part is coated with an insulator. .