JP2007194066A - Discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp with small power consumption emitting blue light by utilizing indium as a light-emitting material. <P>SOLUTION: A bulb is constituted by a light emission tube part 11 and a straight sealing tube part 12 integrally jointed to the light emission tube part 11, and a pair of electrodes 21 are arranged in the light emission tube part 11 so as to face each other. Further, an electrode structure having the electrode 21 on its tip end is inserted into the sealing tube part 12 in a manner of keeping a gap between an inner wall of the sealing tube part 12 and itself, and mercury and indium iodide are sealed inside the light emission tube part of the lamp of which a part between external end side part of the sealing tube part 12 and the electrode structure is formed into an airtightly sealed structure. By using the above structure of the lamp, the discharge lamp emitting a blue color in which indium is sealed by not less than 0.05 mg, consuming power by not less than 20 W and not more than 50 W can be obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a discharge lamp that emits blue light used for aquarium illumination.

An aquarium lamp for emitting blue light using indium as a luminescent material so that beautiful colors of fish, corals, seaweeds, and the like can be vividly reproduced is known (for example, see Patent Document 1).
Recently, tropical fish have been observed in ordinary households. For example, the aquarium lamp shown in Patent Document 1 is used by being placed on the top of the aquarium.
Specifically, the above-mentioned aquarium lamp has a light emitting tube made of quartz glass, and sealing tubes formed at both ends of the light emitting tube have a structure in which quartz glass is melted and crushed. The internal volume of the tube is 2 cc and it lights up at 150W.
In addition, the coldest spot of the arc tube is 700 to 800 ° C. due to the structural relationship between the crushing sealed tube and the arc tube.
FIG. 6 shows a configuration example of the aquarium lamp using quartz glass as the arc tube.
As shown in the figure, a pair of electrodes 21 is provided inside an arc tube 11 made of quartz glass. A crushing structure sealing tube 12 is formed at both ends of the arc tube 11, and the electrode 21 is connected to an external lead wire 24 via a molybdenum foil (Mo foil) 29 sealed in the sealing tube 12. Mercury and indium iodide are enclosed in the arc tube 11.
JP 11-67148 A

As described in Patent Document 1, a lamp that emits light at about 150 W in which mercury and indium iodide are sealed in a quartz glass bulb is conventionally used as a lamp that emits blue light.
Recently, a power-saving lamp has been demanded, and a lamp with a lower power consumption, specifically, a lamp of 50 W or less is demanded.
In order to save power in the lamp of the arc tube made of quartz glass shown in the prior art 1, there is a method of lowering the voltage by lowering the internal pressure of the arc tube. Specifically, it is conceivable to reduce the power consumption by reducing the internal pressure by reducing the amount of mercury enclosed, which governs the internal pressure of the arc tube.
However, when the internal pressure is lowered and the voltage is lowered, the discharge cannot be maintained if the voltage is lowered too much, and there is a limit to lowering the voltage. Electricity cannot be used.

On the other hand, it is possible to reduce the internal pressure of the arc tube by reducing the internal volume of the arc tube without changing the amount of mercury that governs the internal pressure of the arc tube. As the lamp becomes larger, the voltage is too low and the discharge cannot be maintained, so that it is not possible to save power.
Furthermore, in the case of an arc tube lamp made of quartz glass without being limited to the lamp of Patent Document 1, it is possible to manufacture a lamp that is designed to reduce current and voltage to save power.
In this case, the inner volume of the arc tube is also reduced. In such a lamp, since the inner volume of the arc tube is reduced, the amount of the enclosed material is reduced.
However, in the case of an arc tube lamp made of quartz glass, the coldest spot of the arc tube is lower than that of the lamp shown in Patent Document 1 due to the structural relationship between the crushing structure sealing tube and arc tube, but around 700 ° C. It has become.
In other words, although the inner volume of the arc tube is small, the temperature at the coldest spot is around 700 ° C., so that the inclusion in the arc tube evaporates at a high rate.
As a result, the evaporation rate of indium enclosed in the arc tube is high, and a small amount of indium is sufficient to obtain a predetermined indium evaporation amount.

If the amount of indium is excessive with respect to the volume of the arc tube, light at 451 nm, which is the emission peak of indium, will not be emitted by self-absorption, or light near 451 nm will be emitted continuously, resulting in radiated light. The blue color of becomes paler and closer to white.
In the case of the 150 W lamp described in Patent Document 1, the amount of indium iodide to be sealed is, for example, 0.1 mg as described in the same document, and is extremely small. This is done by putting pellets of indium iodide into the arc tube. In the case of a lamp of 150 W or less, the amount of indium to be encapsulated is smaller than this, and the amount is extremely small.

In order to make the lamp of 150 W or less, if it is attempted to reduce the amount of encapsulated indium below the above, for example, the pellets must be crushed and indium iodide must be weighed and encapsulated, but the indium amount is very small. It is extremely difficult to enclose an appropriate amount, and workability also becomes extremely poor when weighed and encapsulated.
As described above, there are various problems in the manufacture of a discharge lamp that emits blue light of 150 W or less. Conventionally, a discharge lamp that emits blue light of 150 W or less has not been manufactured.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a discharge lamp with low power consumption that emits blue light using indium as a luminescent material.

As described above, it is difficult to achieve a lamp that emits blue light by using indium as a luminescent material with low power consumption, using a lamp made of quartz glass. As described above, this is because it is difficult to enclose a very small amount of indium iodide in the arc tube.
Here, as shown in FIG. 6, the lamp with a glass arc tube usually has a crush structure sealing tube at both ends of the arc tube.
On the other hand, a lamp having a straight tubular sealing tube on both sides of an arc tube as shown in FIG. 1 is known. In the case of a discharge lamp using a translucent ceramic, since it cannot be melted and sealed like glass, a lamp having a structure shown in FIG. 1 is usually used.
When the inventor manufactured a discharge lamp that emits blue light with low power consumption using the lamp having the shape shown in FIG. 1, the amount of indium iodide enclosed was increased as compared with the case of using the lamp having the shape shown in FIG. Even found blue light emission.
This is considered to be the following reason. In the case of a lamp having a straight tubular sealing tube on both sides, most of the enclosed indium iodide stays in the low temperature portion of the straight tubular sealing tube on both sides, and the indium iodide present in the arc tube portion. The amount is considered to be less than a fraction of the amount of iodine encapsulated.

Based on the above, the present invention solves the above problems as follows.
(1) A bulb having an arc tube portion and a straight tubular sealing tube portion integrally connected to the arc tube portion, a pair of electrodes arranged in the arc tube portion so as to face each other, and the sealing An electrode structure having the electrode at the tip is inserted into the tube portion so as to have a gap with the inner wall of the sealed tube portion, and an airtight sealing structure is formed between the outer end side portion of the sealed tube portion and the electrode structure. Mercury and indium iodide are enclosed in the arc tube portion of the formed lamp, and blue light is emitted with low power consumption.
(2) 0.1 mg or less of indium is enclosed in the bulb, and the electric power of the discharge lamp is set to 20 W or more and 50 W or less.

In the present invention, the arc tube portion and the straight tube-shaped sealing tube portion integrally connected to the arc tube portion, and the electrode structure having the electrode at the tip in the sealing tube portion, the inner wall of the sealing tube portion And mercury and indium iodide are enclosed in a lamp formed in a hermetically sealed structure between the outer end side portion of the sealing tube portion and the electrode structure. Even if the amount of indium iodide enclosed is larger than that in the case of a lamp having a sealed tube obtained by melting and crushing conventional quartz glass, the lamp can stably emit blue light.
Therefore, an appropriate amount can be enclosed in the arc tube without crushing the pellet of indium iodide, and a discharge lamp emitting blue light with low power consumption, which has been difficult to manufacture in the past, is relatively easy. It can be manufactured.

Hereinafter, embodiments of the discharge lamp according to the present invention will be described. In the following, an embodiment of a discharge lamp using a translucent ceramic as the arc tube will be described, but the object of application of the present invention is not limited to a ceramic lamp.
FIG. 1 is a diagram showing an example of the configuration of a ceramic discharge lamp configured as a metal halide lamp that is turned on by alternating current, which is an embodiment of the present invention. FIG. 1 (a) is a cross-sectional view, and FIG. FIG. 3 is an enlarged explanatory view of a boundary portion between the arc tube and the sealing tube.
In the ceramic discharge lamp shown in FIG. 1, the bulb 10 includes a generally spherical arc tube portion 11 surrounding the discharge space S, and a straight tubular seal continuously connected to extend outward from both ends of the arc tube portion 11. It has the stop pipe part 12, and is formed with translucent ceramics.
As the ceramic constituting the bulb 10, a translucent alumina polycrystal, a translucent yttrium-aluminum-garnet polycrystal, and a translucent yttria polycrystal can be used. Among these, an alumina polycrystal The body is particularly preferred.
In addition, the bulb 10 usually has a maximum outer diameter of the arc tube portion 11 of 5.0 to 8.5 mm, an inner volume of 0.07 to 0.23 cc, and an outer diameter of the sealing tube portion 12 of 1.5 to 2. 0.5 mm, the inner diameter is 0.7 to 0.9 mm, and the length is 6 to 12 mm.

A pair of electrodes 21 are arranged on the bulb 10 so as to face each other in the arc tube portion 11.
The electrode 21 in the illustrated example is formed by winding a metal coil around the distal end portion of an electrode rod 22, and the base end of the electrode rod 22 is connected to the same through a rod-like cermet 23 extending in the same direction. The external lead wires 24 made of molybdenum extending in the direction are integrally connected and electrically connected. Here, as the material of the electrode rod 22 and the metal coil, for example, tungsten or the like is used, and as the material of the external lead wire 24, for example, molybdenum or the like is used.
Further, a sleeve 26 made of ceramic is disposed in an inner portion of the sealing tube portion 12 that is close to the arc tube portion 11 with the electrode rod 22 inserted therethrough.
As a material constituting the sleeve 26, alumina polycrystal, silica glass, or the like can be used, but the same material as the valve 10 is preferable.
The sleeve 26 preferably has a shape in which the outer diameter matches the inner diameter of the sealing tube portion 12 and the inner diameter matches the outer diameter of the electrode rod 22.

Actually, the difference between the outer diameter of the sleeve 26 and the inner diameter of the sealing tube portion 12 is 0.03 to 0.10 mm, and the difference between the inner diameter of the sleeve 26 and the outer diameter of the electrode rod 22 is 0.03 to 0. .07mm.
By using the sleeve 26, the gap between the electrode rod 22 and the inner wall of the sealing tube portion 12 is narrowed, and the amount of inclusions that enter and condense is reduced.
2A, a sleeve 26 may be inserted into the electrode rod 22, and a tungsten coil 27 may be tightly wound around the electrode rod 22 on the electrode side of the sleeve 26. Further, as shown in FIG. 2B, an external lead 28 made of niobium is connected to the end of the electrode rod 22, and a tungsten coil 27 is placed around the electrode rod 22 without using a sleeve member. The structure may be tightly wound and sealed with a frit glass 30 without using a cermet.

Returning to FIG. 1, an electrode structure composed of the electrode rod 22 and the sleeve 26 is inserted into the sealing tube portion 12 of the bulb 10. Specifically, the electrode rod 22 and the sleeve 26 are inserted into the sealing tube portion 12 so that the electrode 21 is positioned in the arc tube portion 11, and between the cermet 23 and the outer end portion of the sealing tube 12. In this state, the frit glass 30 is heated and melted to form an airtight sealing structure on the outer end side portion of the sealing tube portion 12.
As a result, the electrode structure composed of the electrode rod 22 and the sleeve 26 is in a state having the gap k between the inner wall of the sealing tube portion 12.
Here, as shown in FIG. 1B, from the boundary between the arc tube portion 11 and the sealing tube portion 12 to the end of the frit glass 30 that is the internal boundary of the hermetic sealing structure in the sealing tube portion 11. Let the distance of the gap k be L (mm).

As the frit glass 30 for sealing, for example, an alumina-silica-rare earth oxide type or an alumina-calcia type can be preferably used.
Such a ceramic discharge lamp can be lit with low power consumption, for example, 50 W or less, by adjusting current and voltage.
The specifications of the above lamps with power consumption of 20 W and 50 W are as follows.

In such a ceramic discharge lamp, since the material of the bulb is translucent ceramics, the sealing tube portion cannot be melt-deformed in the process of forming the hermetic sealing structure in the sealing tube portion. Therefore, an airtight sealing structure is formed by filling the gap between the sealing tube portion and the electrode structure inserted therethrough with the sealing frit glass 30. As a result, a gap k between the electrode structure and the inner wall of the sealing tube portion 12 is formed.
Further, since the frit glass 30 does not have a sufficiently high heat-resistant temperature, it must be prevented from being overheated when the discharge lamp is turned on.
In view of such a demand, in the sealing tube portion of the ceramic discharge lamp, the arc tube portion is formed in order to separate the central portion of the arc tube portion, which is extremely hot during lighting, from the hermetic sealing region. Subsequently, an appropriate length of the sealing tube portion is required. As a result, the gap k between the electrode structure and the inner wall of the sealing tube portion 12 is elongated.
Since the sealing tube portion following the arc tube portion is formed with an elongated gap k between itself and the electrode structure, the light emission is caused by the structural relationship between the seal tube portion and the arc tube portion. The coldest spot of the tube is a temperature lower than the coldest spot (around 700 ° C.) made of conventional quartz glass, specifically 600 ° C., in the vicinity connected to the sealing tube portion 11.

Since the discharge lamp having the above configuration has a lower temperature than the coldest spot of a quartz glass lamp having a sealed tube with a collapsed structure, mercury and indium enclosed in the arc tube have the coldest spot. Due to the temperature, it is less likely to evaporate than a conventional quartz glass lamp.
That is, since it is difficult to evaporate, it is necessary to increase the amount of indium enclosed.
In a conventional quartz glass lamp, in order to achieve power saving, it is necessary to reduce the pellet form of indium iodide, and the pellet form of indium iodide can be further reduced. However, in the case of the structure of this embodiment, since it is necessary to increase the amount of indium enclosed, pellet-shaped indium iodide having the current size can be used.
As a result, in a ceramic discharge lamp in which an elongated gap is formed between the sealing tube portion and the electrode structure, and the coldest spot of the arc tube portion is 700 ° C. or less, an appropriate discharge tube is provided in the arc tube. A quantity of indium can be encapsulated, and the emission line spectrum is emitted at 451 nm, and the lamp is surely emitted with blue light.
For example, in the lamp shown in Table 1, the amount of indium iodide enclosed is 0.1 mg, which is equivalent to a conventional discharge lamp made of quartz glass of about 150 W.
On the other hand, mercury sealed in the arc tube controls the internal pressure in the arc tube, and the internal pressure is controlled so as to maintain a voltage state in which arc discharge can be maintained, and the current value is set within a predetermined range.

Next, the relationship between the amount of mercury and indium iodide enclosed was examined by experiment. In addition, the length L of the gap between the sealing tube portions (= the distance from the boundary between the arc tube portion and the sealing tube portion to the inner boundary of the hermetic sealing structure in the sealing tube portion: FIG. 1B) The relationship with this was investigated.
This experiment was conducted using the 20/50 W type ceramic metal halide lamp shown in Table 1. The inner diameter of the arc tube and the inclusion in the arc tube are those shown in Table 1. .
In the experiment, a lamp in which the gap length L was changed in the range of 2 to 12 mm was used, and the relationship between mercury and indium iodide was defined as mercury (mg) / indium iodide (mg). (Mg) / indium iodide (mg) was changed in the range of 10 to 150, and in each case the frit glass state, the color of the emitted light, the arc tube state, the lamp power (W), the mercury amount (mg), The amount of indium iodide (mg) was examined. As described above, the smallest indium iodide pellet that can be used at present is about 0.05 mg. Therefore, in this experiment, the amount of indium iodide enclosed was any of 0.15 mg, 0.1 mg, and 0.05 mg. The experiment was conducted by changing the amount of mercury enclosed according to the power.
In this experiment, the color of the emitted light after lighting for 500 hours and the state of the arc tube were examined.
The results are shown in FIGS.
In addition, when the value of mercury (mg) / indium iodide amount (mg) is 150, the amount of mercury enclosed becomes 7.5 mg and the voltage increases to 60 W. This result is also shown in FIG. It shows.

As can be seen from FIGS. 3 to 5, the length (interval length L) from the boundary between the arc tube portion and the sealing tube portion to the inner boundary of the hermetic sealing structure in the sealing tube portion is less than 3 mm. In this case, the frit glass constituting the hermetic sealing structure and the arc tube were too close, the frit glass was melted, and the hermeticity of the arc tube was impaired. For this reason, it was not possible to evaluate.
In the case of the lamps 11 and 12 in which the length (interval length L) from the boundary between the arc tube portion and the sealing tube portion to the inner boundary of the hermetic sealing structure in the sealing tube portion exceeds 10 mm, the sealing tube The volume of the gap in the section increases, the amount of indium iodide entering the gap increases too much, the amount of halogen (iodine) present in the arc tube decreases, the halogen cycle in the arc tube becomes insufficient, and light emission The tube turns black. Further, although the color of the radiated light is blue, the luminous flux from the lamp is lowered due to the blackening of the arc tube, and there is a problem that the illuminance of the illumination area is lowered.
Note that it is considered that this problem can be solved by increasing the amount of indium iodide enclosed in accordance with the volume of the gap in the sealed tube portion. However, a lamp having a long sealed tube length also has a long tube length. It becomes long and is not preferable in practical use.

On the other hand, when the value of mercury (mg) / indium iodide (mg) exceeds 120, when the amount of indium iodide enclosed is 0.05 mg, the amount of indium iodide enclosed is less than the amount of mercury enclosed. .
In this case, in the lamps 2 to 11, the amount of indium iodide is reduced, so that the halogen (iodine) tatami present in the arc tube is also reduced, the halogen cycle in the arc tube is insufficient, and the arc tube is formed. Blacken. In addition, since the amount of indium in the arc tube is reduced, the emitted light also has a strong white color and becomes a blue color close to white, and a desired color cannot be obtained.

On the other hand, when the value of mercury (mg) / indium iodide (mg) is less than 15, when the amount of indium iodide enclosed is 0.15 mg, the amount of mercury enclosed with respect to indium iodide is small.
For this reason, in lamps 2 to 4, since the amount of indium iodide is relatively large, the amount of indium present in the arc tube is large, light in the vicinity of 451 nm is continuously emitted, and the blue color of the emitted light is light. Become.
In the lamps 5 to 9, excess indium enters the gap in the sealed tube portion, and the amount of indium in the arc tube is optimized accordingly, and the emitted light from the lamp becomes blue light.
In the lamps 10 to 11, the gap in the sealed tube portion becomes too large, indium enters the gap in the form of indium iodide, the amount of halogen (iodine) present in the arc tube decreases, and the halogen cycle in the arc tube Becomes insufficient, and the arc tube becomes black. Further, although the color of the emitted light is blue, there is a problem that the luminous flux from the lamp is lowered due to the blackening of the arc tube, and the illuminance in the illumination area is lowered.

From the above experimental results, a lamp having a length L from 3 to 10 mm from the boundary between the arc tube portion and the sealing tube portion to the inner boundary of the hermetic sealing structure in the sealing tube portion, which is mercury (mg) / mg A lamp having an indium iodide (mg) value of 15 to 120, that is, a mercury encapsulation amount of 1.5 mg to 6 mg and an indium iodide encapsulation amount of 0.1 to 0.05 mg, has a low power consumption of 50 W or less. However, it has been found that the frit glass does not melt and the luminous flux does not decrease due to blackening of the arc tube, and the lamp emits blue light reliably.
That is, if the lamp having the structure shown in FIG. 1 is used, a discharge lamp having a power consumption of blue light emission of 20 W or more and less than 50 W can be obtained by sealing 0.05 mg or more and 0.1 mg or less of indium. .

It is a figure which shows the structural example of the discharge lamp of the Example of this invention. It is a figure which shows the other structural example of the discharge lamp of the Example of this invention. It is a figure (1) which shows an experimental result. It is a figure (2) which shows an experimental result. It is a figure (3) which shows an experimental result. It is a figure which shows the structural example of the discharge lamp made from the quartz glass which conventionally emits blue light.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Bulb 11 Light-emitting tube part 12 Sealing tube part 21 Electrode 22 Electrode rod 23 Cermet 24 External lead wire 26 Sleeve 27 Tungsten coil 29 Molybdenum foil 30 Frit glass

Claims (2)

A discharge lamp in which mercury and indium iodide are sealed in an arc tube portion,
The discharge lamp includes a bulb having an arc tube portion and a straight tubular sealing tube portion integrally connected to the arc tube portion,
A pair of electrodes are arranged in the arc tube portion so as to face each other,
An electrode structure having the electrode at the tip is inserted into the sealing tube portion so as to have a gap from the inner wall of the sealing tube portion, and in this state, between the outer end side portion of the sealing tube portion and the electrode structure. Is formed in a hermetic sealing structure. The discharge lamp according to claim 1, wherein 0.1 mg or less of indium is enclosed in the bulb, and the electric power of the discharge lamp is 20 W or more and 50 W or less.

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