JPH03274651A - Metal halide lamp for horizontal lighting - Google Patents

Abstract

PURPOSE:To suppress an arc from floating and prevent an arc from swaying by applying electric current to one electricity supplying lead wire toward the reverse direction to the arc current and placing the lead wire in a specific position. CONSTITUTION:Electric current is applied to one electricity supplying lead wire 6 of a light emitting tube 1 to the reverse direction to that of electric current of an arc 10 in the light emitting tube 10. The distance RL between the lead wire 6 and the axial center 8 of the light emitting tube 1 and lamp current Il(A) are defined to have a relation; 7Il<=RL<=25Il, and the lead wire 6 is set to position within a 15-75 deg. right and left range when the right above point in the vertical plane of the axial center 8 is set to be 0 deg.. Consequently, the floating of the arc 10 in the light emitting tube 1 is suppressed and the swaying of the arc 10 is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a metal halide lamp, and in particular to a horizontal lighting lamp equipped with a reflecting mirror and used as a relatively small light source for images that distributes light in an optically limited area. Regarding metal halide lamps.

[Prior Art] Halogen lamps have been widely used in projectors, overhead projectors, etc. due to their characteristics as high-efficiency compact light sources, but in recent years halogen lamps have become more efficient, have high color rendering properties, and are compact. Metal halide lamps have been developed and are now being used in overhead type projection televisions using liquid crystals, in addition to the above devices.

[Problem to be solved by the invention] By the way, among metal halide lamps having the above characteristics,
Those with an arc length of 20 or less are placed horizontally and lit.
If the lighting continues for a while, the metal halide sealed in the quartz arc tube will react with the quartz, resulting in the generation of impurity gas and excess halogen, which will cause the arc to deteriorate. The object may float upward, become curved, or shake. As a result, when used in an overhead type projection television, for example, problems arise such as uneven illumination on the screen and flickering of the image.

The present invention was made to solve the above-mentioned problems in horizontally lit metal halide lamps, and is a metal halide lamp for horizontally lit that suppresses upward floating of the arc and further prevents the occurrence of swinging of the arc. The purpose is to provide

[Means and effects for solving the problem] In order to solve the above-mentioned problems, the present invention provides a metal halide lamp in which at least a metal halide-filled arc tube is lit horizontally, in which one side of the power supply to the arc tube is The lead wire is arranged so that the current flows in the opposite direction to the current direction of the arc in the arc tube, and the distance between the lead wire and the center of the arc tube axis is 11tRL, and the lamp current is Il (A). When the range is 7・I4≦RL≦25・Il, and when Oo is directly above the vertical plane of the arc tube axis, the left and right 1
It is arranged and constructed so that it is located in the range of 5'' to 75 degrees.

By arranging one of the power supply lead wires to the arc tube in this manner, a repulsive force is exerted on the arc by the current that crushes the lead wire, thereby preventing the arc from floating. Also, place the lead wire so as to avoid directly above the arc tube.
7, the occurrence of 1゛◆ fluctuation of the arc can be effectively prevented.

〔Example〕

Next, an example will be described. FIG. 1 is a perspective view showing an embodiment of a horizontally lit metal halide lamp according to the present invention. The metal halide lamp shown in this example is
The lamp voltage is 75 V and the lamp current is 2 A. 1 is a quartz arc tube with an internal volume of 0.4 cc, a maximum outer diameter of 11 m at the center, and a maximum inner diameter of 8.8 mm at the center. In addition to metal halide, mercury and argon are sealed inside. Inside the arc tube 1, there are electrodes 2 at both ends.
2' are arranged as shown in A with a distance between the electrodes of 5.5 cm. Electrodes 2 and 2' are made of a tungsten core rod of φ0.5cm containing 1.7% ThO□, and a tungsten core rod of φ0.3mm containing 1.7% ThO
It is formed by winding a single coil of ThO-containing tungsten wire. And these electrodes 2゜2' have a thickness of 0
．． It is connected to a wire 4.4' made of a molybdenum wire with a diameter of 0.6 m through a molybdenum foil 3.3' with a diameter of 0.2 mm, a width of 1.5++a, and a length of 18 mm. It is connected to the lead wire 6.

Then, a reflector m7 with a cold collar is attached to surround the arc tube l constructed in this way, and the nickel lead wire 6 is folded back so as to be almost parallel to the axial center 8 of the arc tube l, and the reflector It is connected to a terminal 9 which is drawn out from the outside of the reflector 7 and fixed to the outer wall surface of the reflector.

In the present invention, the arrangement position of the lead wire 6 is set as described in the claims.Next, an experiment conducted in setting the arrangement position of the lead wire 6 will be explained. .

First, the metal halide lamp configured as described above is lit using an electronic ballast capable of lighting a rectangular wave of about 250 Hz with a lamp power of 150 W, and the arc 10 of the arc tube 1 is lit.
As a result of observing the situation, it was found that the floating of the arc 10 and the manner of separation of the arcs differed depending on the arrangement position of the lead wire 6. For example, as shown in the vertical cross-sectional view of the arc tube 1 in FIG. is 1.0 m after 500 hours of lighting, which is not very large, but because the arc tube is filled with metal halide, the lead wire 6 placed directly above the arc tube causes cyclic arc swings. It has been found.

On the other hand, if the point directly above is O in the plane perpendicular to the arc tube axis,
o, and as shown by the dotted line in Fig. 2, the lead wire 6 is placed at a position of 20° to the left or right of the arc tube at a distance of 7 cm from the arc tube axis center 8, and similarly after 500 hours of lighting. When the state of the arc was observed, it was found that the arc had a floating height of 1.05 m, and no swinging of the arc occurred.

The reason why the arc levitation is reduced by arranging the lead 16 directly above or diagonally above the arc tube 1 is that the current direction of the arc IO of the arc tube 1 is opposite to the current direction of the lead wire 6. and therefore arc 10 and lead [6
It turns out that this is because a repulsive force acts between them, and since the lead 116 is fixed, a force acts on the arc 10 in the opposite direction to the floating direction. This means that if the lead wire 6 is placed directly below the arc tube 1 at a distance of 10 mm from the axial center 8, the arc will be 5 mm compared to when the lead wire is led out in the tube axis direction.
This was also confirmed by the fact that after the light was on for 00 hours, it rose an additional 0.3 meters above the ground.

It has also been found that the levitation of the arc IO in the arc tube 1 varies depending on the distance between the lead wire 6 and the arc tube axis center 8 and the current value. Therefore, we investigated the placement position of the lead wire 6 with respect to the arc tube 1, that is, the direction and distance, as well as the current value, the degree of floating of the arc, and the occurrence of arc shaking. It has been found that the distance and direction of the lead wire 6 may be set within the following range as a condition for preventing shaking. In other words, regarding the distance, if the lamp current is lz (A) and the distance between the lead lt6 and the arc tube axis center 8 is RL, then if 7.17≦R1≦25.14, then the arc levitation can be reduced by two degrees. It can be kept below.

Regarding the lower limit of the above-mentioned distance RL, if the lead wire is brought too close to the arc tube, heat reflection will increase and a part of the arc tube will bulge, so take this into account and set it as above. It was done.

As for the direction in which the lead wires are arranged, as shown in Figure 2, it is necessary to set the direction directly above the arc tube at 0''', and the direction should be at least 15 degrees left and right to ensure that arc swings hardly occur.
In addition, as a condition to effectively prevent the arc from floating,
It is necessary to set the angle θ to 15°≦θ≦75”.

By setting the lead wire placement position in this way,
This suppresses the levitation of the arc in the arc tube, which in turn reduces the reaction between the metal halide and the quartz that makes up the arc tube.
Furthermore, arc fluctuation can be effectively prevented.

C Effects of the Invention] As described above based on the embodiments, according to the present invention, by arranging the lead wire within a predetermined range with respect to the arc tube, arc floating of the arc tube can be suppressed and arc It is possible to provide a metal halide lamp for horizontal lighting that prevents shaking.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a horizontally lit metal halide lamp according to the present invention, and FIG. 2 is a vertical sectional view of the arc tube portion. In the figure, 1 is an arc tube, 2.2' is an electrode, 33' is a molybdenum foil, 4.4' is a wire, 5 is a cap, 6 is a lead wire, 7 is a reflector, and 9 is a terminal. Figure 1

Claims (1)

[Claims] 1. In a metal halide lamp in which an arc tube filled with at least metal halide is lit horizontally,
One power supply lead wire to the arc tube is arranged so that the current flows in the opposite direction to the current direction of the arc in the arc tube, and the distance R_L (mm) between the lead wire and the center of the arc tube axis is When the current is I_l (A), 7・I_l≦
A metal halide lamp for horizontal lighting, characterized in that the range is R_L≦25・I_l, and the lamp is arranged in a range of 15° to 75° left and right when the vertical plane of the arc tube axis is set to 0° directly above. .