JP2004022498A - Arc tube for lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the manufacturing cost of an arc tube for a lamp by reducing the quantity of a luminescent substance to be enclosed. <P>SOLUTION: In this arc tube for a lamp, an envelope 1 having translucency and a pair of electrodes 2 each arranged in a form penetrating the envelope 1 are installed; the envelope 1 is formed by comprising a thick tube part 1b filled with the luminescent substance for forming a discharge space, and a pair of thin tube parts 1a for respectively inserting the pair of electrodes 2; and coils 11 wound around the electrodes 2 in the tube parts 1a are installed. A nearly cylindrical metal member ME is disposed around each coil 11. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
According to the present invention, an envelope having a light-transmitting property and a pair of electrodes arranged so as to penetrate the envelope are provided, and the envelope forms a discharge space by being filled with a luminescent substance. The present invention relates to a light emitting tube for a lamp, which is formed to include a thick tube portion and a pair of thin tube portions through which the pair of electrodes are inserted, respectively, and includes a coil wound around the electrode in the thin tube portion.
[0002]
[Prior art]
Such an arc tube for a lamp is used as an arc tube of a lamp such as a ceramic metal halide lamp or a high-pressure sodium lamp.
In the envelope of the arc tube for a lamp, a pair of electrodes are arranged so as to penetrate the envelope in order to cause a discharge in the space inside the envelope. Is provided, and a thick tube portion that forms a discharge space in a state of being connected to the thin tube portion is provided.
The tips of the pair of electrodes protrude from the thin tube into the thick tube, and a coil is wound around the electrode at a portion of the electrode present in the thin tube. As shown in FIG. 4A showing a conventional arrangement, the coil 101 narrows the space between the inner wall of the thin tube portion 102 and the electrode 103 so that the vaporized luminescent material in the thick tube portion 104 has a low temperature. By preventing heat from entering the inner portion of the thin tube portion 102 and radiating the heat of the electrode 103, the heat in the discharge space (the space in the thick tube portion 104) in a high temperature state is transmitted through the electrode 103 having good heat conduction. It is transmitted to the sealing portion 105 of the electrode 103 in the thin tube portion 102 and functions to prevent the brazing material 106 of the sealing portion 105 from exceeding the heat-resistant temperature.
[0003]
[Problems to be solved by the invention]
However, in the above-described conventional configuration, as shown in FIG. 4B, the luminescent material 107 that has invaded as vapor solidifies or liquefies and accumulates in the gap between the coil 101 and the envelope (small tube portion 102), and emits light. There is a considerable amount of luminescent material that does not contribute, and it was necessary to initially set a relatively large amount of luminescent material to be sealed in the arc tube.
This luminescent material is generally extremely expensive, and as described above, the need for a large amount of the luminescent material has led to an increase in the manufacturing cost of the arc tube for a lamp.
The present invention has been made in view of such circumstances, and an object of the present invention is to reduce the amount of a luminescent substance to be enclosed and reduce the manufacturing cost of a luminous tube for a lamp.
[0004]
[Means for Solving the Problems]
With the configuration according to claim 1, an envelope having a light-transmitting property and a pair of electrodes arranged so as to penetrate the envelope are provided, and the envelope is formed of a luminescent material. Is formed to include a thick tube portion that forms a discharge space by being enclosed, and a pair of thin tube portions that respectively penetrate the pair of electrodes, and includes a coil that is wound around the electrode in the thin tube portion. In the lamp arc tube, a substantially cylindrical metal member is disposed around the coil.
[0005]
That is, by disposing a substantially cylindrical metal member around the coil wound around the electrode, the metal member fills the space around the coil to reduce the gap, and the presence of the metal member allows the coil to be formed. The volume of the space to be occupied is reduced, and accordingly, the diameter of the coil is reduced, and the gap formed in the coil is also reduced.
If only the space between the electrode and the inner wall of the thin tube is simply eliminated, a configuration in which, for example, a metal pipe that fills the space between the electrode and the inner wall of the thin tube may be arranged without providing the coil, such a configuration is also conceivable. In the configuration, the heat dissipating effect of the heat transmitted from the discharge space to the electrode is not sufficient, and the brazing material for fixing the electrode to the thin tube may exceed the heat resistant temperature.
[0006]
Furthermore, as a substantially cylindrical member arranged around the coil, it is conceivable that a ceramic member is arranged instead of a metal member, but by disposing a metal member having good heat conduction around the coil, The temperature of the portion is maintained at a relatively high temperature, whereby the solidification or liquefaction of the vapor of the light emitting substance can be suppressed.
In other words, by disposing a substantially cylindrical metal member around the coil, the gap where the solidified or liquefied luminescent material stays is reduced, and the vapor of the luminescent material is maintained by maintaining the inside of the thin tube at a certain high temperature. By suppressing the solidification or liquefaction of the particles and radiating the heat from the electrodes, the amount of the luminescent substance staying in the thin tube can be reduced.
Accordingly, the manufacturing cost of the arc tube for a lamp can be reduced by reducing the amount of the luminescent substance to be enclosed.
The substantially cylindrical metal member may be configured by a single component, or may be configured so that a plurality of components are gathered to form a substantially cylindrical shape as a whole.
[0007]
In addition, with the configuration described in the second aspect, the substantially cylindrical metal member is formed of a molybdenum pipe.
That is, the metal member disposed around the coil also has a function of maintaining the inside of the thin tube at a high temperature to some extent. However, if the heat conduction is too good, the inside of the thin tube becomes unnecessarily hot and the electrode is fixed. This has an adverse effect on the brazing material to be used.
In that regard, molybdenum has a lower thermal conductivity than metals such as tungsten, and can maintain the inside of the thin tube at a moderately high temperature.
Furthermore, the shape is also a simple pipe shape and processing is easy.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a light emitting tube for a lamp according to the present invention will be described with reference to the drawings.
[Schematic configuration of arc tube LT]
As shown in FIG. 2, a lamp arc tube LT for a lamp according to the present embodiment (hereinafter simply abbreviated as “arc tube LT”) is a light-transmitting envelope 1 formed of a light-transmitting ceramic. A pair of electrodes 2 is hermetically sealed with a brazing material 3, and a metal halide such as mercury or sodium iodide is sealed in the envelope 1 as a luminescent material.
The arc tube LT, together with a circuit such as a starter of the arc tube LT (not shown), is sealed in a glass bulb 4 with, for example, nitrogen gas as shown in FIG. 3 to constitute a so-called HID lamp. FIG. 3 exemplifies a lamp shape provided with the base 5.
The envelope 1 of the present embodiment includes a thick tube portion 1b for forming a discharge space, and a pair of thin tube portions 1a arranged on both sides of the thick tube portion 1b and through which the electrodes 2 are inserted. In this embodiment, the material used is translucent alumina among the translucent ceramics.
The electrode 2 is inserted into a cylindrical spacer 7 made of the same material as the envelope 1 at an outer opening of the thin tube portion 1a as shown in FIG. 1 showing an enlarged cross section of the thin tube portion 1a. Hermetically sealed.
[0009]
[Detailed configuration of electrode 2]
As shown in FIG. 1 and the like, the electrode 2 has an external lead-in wire 2a formed of a niobium wire, an electrode pole 2b formed of tungsten, and a relay formed of a small-diameter molybdenum wire connecting the two. The wire 2c is integrally formed.
A metal (tungsten) coil 10 (hereinafter, this coil 10 is referred to as a “pole head coil 10”) is wound around the electrode pole core 2b at a tip protruding into the thick tube portion 1b, and the thin tube portion 1a is wound. A coil 11 made of metal (molybdenum) (hereinafter, this coil 11 is referred to as a “second coil 11”) is wound around a portion located inside.
A pipe 12 made of molybdenum is fitted around the second coil 11 as a substantially cylindrical metal member ME.
[0010]
The pole head coil 10 has a function of radiating heat of the electrode pole core 2b, and stabilizes a discharge state by this heat radiation effect.
On the other hand, the second coil 11 and the pipe 12 narrow the space between the inner wall of the thin tube portion 1a and the electrode pole core 2b and suppress the evaporated luminescent material from moving to the deep side (sealing side) of the thin tube portion 1a. At the same time, the temperature of the thin tube portion 1a is maintained at a relatively high level to prevent the solidified (or liquefied) luminescent substance from staying in the thin tube portion 1a. It has a function of radiating heat conducted from the portion 1b side to the back side of the thin tube portion 1a to suppress a rise in temperature of the sealed portion.
[0011]
Next, the effect of the second coil 11 and the pipe 12 for preventing the luminous substance from staying will be described with reference to specific experimental examples.
The dimensions of each part of the arc tube LT manufactured for the experiment are listed below.
First, regarding the dimensions of the envelope 1, the inner diameter of the central portion of the thick tube portion 1b is φ18mm, the outer diameter is φ21mm, the inner diameter of the thin tube portion 1a is φ2mm, the outer diameter is 4mm, the length is 20mm, and the dimensions of the electrode 2 The diameter of the electrode core 2b is φ1.0 mm, the wire diameter of the second coil 11 is φ0.2 mm, the inner diameter of the molybdenum pipe 12 is φ1.42 mm, and the outer diameter is φ1.98 mm.
23 mg of mercury, 8 mg of dysprosium iodide, 2 mg of thallium iodide, and 4 mg of sodium iodide were enclosed in the envelope 1 as a luminescent substance.
[0012]
When the arc tube LT manufactured in this manner was lit under a lighting condition of a lamp power of 400 W and a vertical lighting, it was found that the initial characteristics were a lamp luminous flux of 35,800 lm (lumen) and an average color rendering index (Ra) of 92. Was done.
Incidentally, in the conventional case in which the molybdenum pipe 12 is not provided and the luminous substance is prevented from staying in the thin tube portion 1a only by the second coil 11, if the other conditions are the same as the above, the luminous substance Of these, the amount of metal iodide used is twice as much as the above, the lamp luminous flux is 34000 lm (lumen), the average color rendering index (Ra) is 90, and the use of metal iodide is achieved by applying the present invention. The amount can be reduced to half of the conventional amount, and further, both the lamp luminous flux and the average color rendering index (Ra) are improved.
Further, when an experiment was conducted with the conditions optimized, it was confirmed that the amount of metal iodide used could be reduced to about one third of the conventional amount.
[0013]
[Another embodiment]
Hereinafter, other embodiments of the present invention will be listed.
(1) In the above-described embodiment, the pipe 12 made of molybdenum is exemplified as the substantially cylindrical metal member ME disposed around the second coil 11, but the configuration of the metal member ME is a single pipe member. In addition to the above configuration, a configuration in which short pipes are arranged in the axial direction to form a cylindrical shape as a whole, or a configuration in which semi-cylindrical members are combined to form a cylindrical shape as a whole, The metal pipes may be concentrically stacked so as to be substantially cylindrical as a whole, and the specific shape of the metal member ME can be variously changed. Also, the material of the metal member ME may be a metal material other than molybdenum.
(2) In the above embodiment, the shape of the envelope 1 is such that the thin tube portions 1a supporting the electrodes 2 are arranged on both sides of the thick tube portion 1b, but the thin tube portions 1a are arranged side by side on the thick tube portion 1b. The specific shape of the envelope 1 can be variously changed, for example, in a state arrangement.
[0014]
【The invention's effect】
According to the configuration of the first aspect, by disposing a substantially cylindrical metal member around the coil wound around the electrode, the metal member fills the space around the coil to reduce the gap and Due to the presence of the metal member, the volume of the space to be occupied by the coil is reduced, and accordingly, the diameter of the coil is reduced and the gap formed in the coil is also reduced.
In addition, by disposing a metal member having good heat conduction around the coil, the temperature of the portion is maintained at a relatively high level, whereby the solidification or liquefaction of the vapor of the luminescent material can be suppressed. .
Thus, by reducing the amount of the luminescent material staying in the thin tube, the amount of the luminescent material sealed in the envelope can be reduced and the manufacturing cost of the arc tube for the lamp can be reduced.
[0015]
According to the configuration of the second aspect, the metal member disposed around the coil also has a function of maintaining the inside of the thin tube at a high temperature to some extent, but if the heat conduction is too good, the inside of the thin tube is required. Since the temperature becomes higher as described above, since it will adversely affect the brazing material for fixing the electrodes, by disposing molybdenum having a lower thermal conductivity than a metal such as tungsten around the coil, The inside of the thin tube can be maintained at a moderately high temperature.
Moreover, the shape is also a simple pipe shape, and processing is easy.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of an arc tube for a lamp according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view of an arc tube for a lamp according to an embodiment of the present invention. FIG. 4A is a cross-sectional view of a main part of a conventional arc tube for a lamp, and FIG. 4B is an enlarged view of a part around a coil.
Reference Signs List 1 envelope 1a thin tube portion 1b thick tube portion 2 electrode 11 coil 12 pipe ME metal member

Claims (2)

An envelope having a light-transmitting property and a pair of electrodes arranged so as to penetrate the envelope are provided,
The envelope is formed to include a thick tube portion that forms a discharge space in which a luminescent substance is sealed, and a pair of thin tube portions that respectively insert the pair of electrodes,
An arc tube for a lamp provided with a coil wound around the electrode in the thin tube portion,
An arc tube for a lamp, wherein a substantially cylindrical metal member is arranged around the coil. The arc tube for a lamp according to claim 1, wherein the metal member is constituted by a pipe made of molybdenum.

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