JPS6059649A - Metal halide lamp used in horizontal position - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a horizontally lit metal halide lamp, which has a uniform radiation distribution in the circumferential direction of the arc, and emits light in a stable manner. The present invention relates to a metal halide lamp suitable for use as a light source for optical character reading devices that require high resolution.

[Background of the invention]

In metal halide lamps for general lighting that use quartz arc tubes, when the lamp is lit horizontally, excess fill material adheres to the lower side of the arc tube wall, reducing downward light transmission. This phenomenon is not so much of a problem with lamps for general lighting, but it is a major hindrance in lamps for optical character readers, which illuminate the ledger and read the characters written on the ledger. . On the other hand, in a high-pressure sodium lamp with an alumina pipe as an arc tube, the tube diameter is small and the temperature at the center of the arc tube is sufficiently higher than at the tube ends, so excess fill material does not accumulate in the center of the tube even when the lamp is lit horizontally. However, when a halogen compound is enclosed in an arc tube made of alumina pipe, the constituent materials of the arc tube react with the halogen element, so a lamp in which this compound is enclosed has not yet been put to practical use.

Therefore, in order to prevent the above-mentioned excess inclusions from adhering to the wall of the arc tube and to provide a uniform radiation distribution in the circumferential direction of the arc, the present inventors have attempted to reduce the tube current density of the arc tube to at least 2. It is separately proposed to construct a horizontally lit metal halide lamp with an OA/c4 and an electrode enclosure height of at least 6 mm. That is, in such a lamp, the excess fill material is concentrated behind the electrode, that is, near the sealing part of the arc tube.

However, even in such a lamp, there is a problem in that part of the excess fill material that becomes liquid during lighting periodically jumps out into the arc, making the light output unstable.Therefore, some kind of improvement is desired. It is rare.

[Purpose of the invention]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a horizontally lit metal halide lamp that emits light uniformly in the circumferential direction and at the same time provides stable light output.

[Summary of the invention]

In order to achieve the above object, in the present invention, the tube current density of the arc tube is at least 2.0 A104, the height of the electrode is at least 6.0 mm, and the central axis of the electrode and the central axis of the arc tube are 5 (30°) vertically upward
It is characterized by being configured as a horizontally lit metal halide lamp. In other words, the tube current is 2. OA
/d or more, and even if the electrode filling height is 6tan or more, if the electrode axis angle is less than 5 degrees with respect to the arc tube axis or is vertically downward, part of the excess filling material during horizontal lighting will be removed. This is not preferable because the portion periodically protrudes into the arc from the rear portion of the electrode, resulting in periodic dramatic fluctuations in the light output. This sudden fluctuation in light output is extremely inconvenient for devices that read characters at high speed, as it may result in poor reading.

Furthermore, if this angle exceeds 30° in the vertical upward direction, there will be no periodic protrusion of excess inclusions into the arc, and the light output will be stable. As a result, the arc approaches the inner wall of the tube and devitrifies the quartz tube, which is undesirable.

Due to the characteristic configuration of the present invention, during lighting, non-evaporated excess of the filler substance is prevented from adhering to the wall surface of the arc tube between the tips of the electrodes, so that it is uniformly distributed in the circumferential direction of the arc tube. It is an object of the present invention to provide a horizontally lit metal halide lamp which can obtain a stable light output by providing a stable radiation distribution and at the same time suppressing excess fillers accumulated in the arc tube sealing part from periodically jumping into the arc. It has become possible.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained with reference to FIG. FIG. 1 shows a horizontal lighting type according to the present invention.

In these figures, there are electrodes 2.2 at both ends of a quartz arc tube 10 with an inner diameter of 6.5+mn at a distance of 80+o+ between the electrodes.
2' is sealed. At this time, the height of the electrode 2°2' (the height from the sealing part to the tip of the electrode) is 6.5 mm. In addition to iodides such as sodium and thallium, xenon as a starting rare gas and Hg as a buffer gas are sealed in the arc tube 1. As shown in FIG. 2, the electrodes 2 and 2' are electrically connected at the end of the quartz arc tube 1 through the MO foil 3 and are hermetically sealed.
The end of this MO foil 3 is electrically led out to the outside by an MO lead wire 4.4'. In addition, luminescence +! f1
Heat insulating films 7, 7' are provided around the outer circumference of the electrodes 2, 2' to slightly correct electrical characteristics. The arc tube 1 is fixed by a support fixing plate 8° 8' so as to be positioned on the central axis of the outer tube 6 made of quartz, and the MO lead wire 4 mentioned above is fixed.
, 4' are electrically connected to the Mo foil 5.5', and their ends are electrically connected to MO lead wires (not shown), and then pierced with nitrogen at both ends of the outer tube 6. ing.

The lamp produced in this way has a lamp current of 1.2A.
with a lamp power of 200 W (therefore, the tube current density is 3.6 A/tri),
In this embodiment, the electrode 2 (2'1
The angle θ between the central axis BB' of the arc tube 1 and the center +111A-A' of the arc tube 1 is 12°.

When such a metal halide lamp was turned on horizontally, the excess iodide at the time of lighting was stably aggregated at the position of the sealing part 11 shown in FIG. 2, and there was no abnormal fluctuation in the light output.
Further, no excess inclusions were observed to adhere to the wall of the arc tube between the tips of the electrodes 2 and 2', and a stable and uniform light output was obtained.

Next, we conducted experiments and studies on various lamps with different current densities, electrode enclosure heights, crossing angles θ, and lamp powers, and the following results were obtained.

In other words, in horizontally lit metal halide lamps,
During lighting, the non-evaporated surplus of the filled material is prevented from adhering to the tube wall surface of the arc tube l between the tips of the electrodes 2.2', and in addition, the non-evaporated surplus of the filled material accumulated behind the electrode 2. In order to prevent part of the surplus from jumping into the arc, the tube current density should be set to at least 2. OA/c+! b electrode 2.
The enclosure height of 2' is at least 6.0 mm, and the angle between the central axis of the electrode and the central axis of the arc tube is
θ may be in the range of 5° to 30° vertically upward. The reason for this is as follows. The enclosure height of electrodes 2 and 21 is set to 6
, OW, no matter how you choose the crossing angle θ, the tube current density will be 5. Even if the tube current density exceeds OA/crI, it is impossible to prevent excess inclusions from adhering to the tube wall between the tips of electrodes 2 and 2'. If the temperature is exceeded, the temperature of the arc tube 1 will become too high and the life of the lamp will be significantly shortened.

Also, the tube current density was set to 2. If the temperature is less than OA/cd, the temperature of the tube wall will drop and excess inclusions will adhere to the tube wall between the tips of the electrodes 2 and 2', no matter how the crossing angle θ is selected. on the other hand,
When the tube current density is less than 2, OA/cr/1, electrodes 2,2
If the filling height of ' is set to 6.0 mm or more, no matter how the intersection angle θ is chosen, the temperature of the entire arc tube l will drop and sufficient evaporation pressure of the filling material will not be obtained, resulting in a decrease in light output. decreases. Moreover, the tube current density is 2. If the OA/CR is set to 1 or more and the height of the electrode 2.2' is set to 6 or more, if the crossing angle θ is less than 5°, no adhesion to the tube wall between the tips of the electrodes 2.2' will occur at all; A part of the enclosed material periodically pops out from behind the electrode 2.2' into the arc, causing a remarkable fluctuation in the light output, and if the crossing angle θ exceeds 30'', the gap between the tips of the electrodes 2.2' Although no adhesion to the tube wall of the arc tube 1 occurs, and in addition, there is no periodic ejection of excess inclusions into the arc, the tips of the electrodes 2 and 2' are too close to the tube wall surface of the arc tube 1, so the quartz tube 1 devitrification.

FIG. 3 is a graph showing an example of the results obtained from the above-mentioned experiments and studies. This graph shows the tube current density of 2.
OA/ca constant, electrode 2.2' enclosure height 6.
We will show what happens to the remarkable fluctuations in light output (stability of light output) by keeping OB constant and changing the intersection angle θ from vertically downward to vertically upward while setting the lamp power to 200W. . In this figure, the ◯ marks represent lamps in which no remarkable light fluctuations were observed, and the X marks represent lamps in which remarkable light fluctuations were observed.

The intersection angle θ is represented by - in the vertically downward direction and by 10 in the vertically upward direction. Besides, ○.

The vertical number of X indicates the number of lamps tested.

As is clear from this graph, when the intersection angle θ is less than 5°, the prominent light fluctuations tend to decrease somewhat as θ increases, but most of the lamps are not suitable for practical use. . On the other hand, when the intersection angle is 5 degrees or more, there is no noticeable light fluctuation at all, and an extremely good lamp can be obtained. however,
If the crossing angle θ exceeds 30°, this is not desirable because the above-mentioned devitrification of the arc tube 1 will occur.

〔Effect of the invention〕

As described above, according to the present invention, during lighting, non-evaporated residue of the enclosed substance is left on the wall surface of the arc tube between the tips of the electrodes.

Since the adhesion of particles is suppressed, a uniform radiation distribution can be obtained in the circumferential direction of the arc tube, and at the same time, excess inclusions accumulated in the arc tube sealing part periodically jump into the arc. This makes it possible to provide a horizontally lit metal halide lamp that provides stable light output.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of a horizontally lit metal halide lamp according to the present invention, FIG. 2 is a partially enlarged sectional view of the arc tube in FIG. 1, and FIG. 3 is a diagram for explaining the present invention in detail. It is a graph showing an example of experimental results.

Claims (1)

[Claims] 1. In a metal halide lamp in which a quartz arc tube with electrodes at both ends is lit and used horizontally, the tube current density of the arc tube is at least 2. OA/cr/l,
The encapsulation height of the electrode is at least 6.0 groups, and
A horizontally lit metal halide lamp, characterized in that the angle between the central axis of the electrode and the central axis of the arc tube is in the range of 5'-30° vertically upward.