JP3246463B2 - Metal vapor discharge lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal vapor discharge lamp using an arc tube made of translucent ceramic.

[0002]

2. Description of the Related Art Conventionally, this kind of metal vapor discharge lamp has
For example, JP-A-6-196131 (conventional example 1),
JP-A-7-240184 (conventional example 2);
This is disclosed in Japanese Patent Application Laid-Open No. 1-245457 (Conventional Example 3).

That is, the prior art 1 has an arc tube made of a translucent ceramic, and a hydrogen permeable substance connected to an electrode in a narrow tube provided on both sides of a central main portion of the arc tube and a halide resistance. A feeder made of a substance is inserted, and a gap between the thin tube and the feeder is sealed with a glass frit.

As the hydrogen permeable substance, niobium, tantalum, or the like is used, whereby the thermal expansion coefficient can be made close to that of alumina, which is a material of the thin tube, and the occurrence of cracks during sealing can be prevented. However, since niobium and the like react violently with the halide as an enclosure, tungsten, molybdenum, or a halide-resistant substance such as a conductive cermet is used in portions where the enclosure exists during lighting, and niobium is used. The hydrogen permeable portion is completely sealed by a glass frit, and has a configuration for suppressing a reaction with a power supply.

[0005] In the prior art example 2, in the center, a bulge portion having a spherical or elliptical sphere is formed at the center and a thin tube portion having a smaller diameter than the bulge portion is formed integrally at both ends of the bulge portion. The light-emitting device includes a light-emitting ceramic light-emitting tube, and a pair of electrodes supported by one end of a closed body having a conducting means for conducting inside and outside of the light-emitting tube inserted into the thin tube portion.

In this configuration, the inside and outside of the arc tube are electrically connected by an external lead wire penetrating the inside of the closing body. The thin tube portion is joined to the thin tube portion by a glass adhesive made of, for example, frit glass poured into a gap between the inner surface of the end portion on the side opposite to the electrode and the outer surface of the closing body.

Further, mercury as a buffer metal, metal halide as a luminescent metal, and a rare gas such as argon gas are sealed in the arc tube. However, the metal halide is sealed in excess of the amount that evaporates during lighting.

Normally, when the temperature of the glass adhesive becomes high during lighting, a chemical reaction occurs with the metal halide and the glass adhesive deteriorates. This deterioration causes a leak in the arc tube. Therefore, in this conventional example, during lighting, excess metal halide is aggregated in the gap between the inner surface of the narrow tube portion and the outer surface of the closing member except for the joint portion made of the glass adhesive, and the glass halide is adhered by the aggregated metal halide. The agent and the hot gas in the discharge space are thermally isolated. This can prevent the glass adhesive from deteriorating due to a chemical reaction with the metal halide, thereby preventing the arc tube from leaking.

In Conventional Example 3, dysprosium halide is sealed in an arc tube in which the end of a translucent alumina tube is closed with a conductive cermet via a sealing material, and a main component of the sealing material is formed. Is formed using a rare earth metal oxide. The conductive cermet is prepared by mixing tungsten powder and the like with alumina and the like used for the arc tube material,
Sintered, the difference in thermal expansion coefficient from alumina is very small, and cracks in the sealed portion can be reduced.
In addition, since a rare earth metal oxide is used as a main component as a sealing material, a reaction between the filling material and the sealing material during lighting can be suppressed.

[0010]

In the conventional structure as described above, when a metal such as tungsten or molybdenum having a coefficient of thermal expansion that is significantly different from that of alumina is used for the halide-resistant portion of the power supply, cracks are formed in the sealing portion. Thus, there is a problem that the arc tube easily leaks during the sealing step and during lighting. In order to prevent this, it is preferable to use a conductive cermet having an expansion coefficient close to that of alumina in the halide-resistant portion, but it is difficult to bond the conductive cermet with niobium, which is a hydrogen-permeable substance, and the reliability of this portion is low. However, there is a problem that the utilization rate of the power feeder is reduced due to the nature of the power supply.

Further, when a metal such as niobium is used as the power supply, the interface between the niobium and the glass frit is coupled with
It is weaker than the bonding at the interface between the glass frit and alumina, which are oxides, and there is a problem that the lamp gradually drops from the interface between niobium and the glass frit during lighting for a long time, and the lamp voltage decreases. .

Further, a considerable amount of thermal stress is generated between niobium having a thermal expansion coefficient of 7.2 × 10 ^-6 and alumina having a thermal expansion coefficient of 8.0 × 10 ^-6 during sealing and lighting. At high watts where the diameter of the electrode rod is large, there is a problem that this thermal stress cannot be ignored and causes cracks in the sealing portion. In addition, niobium or the like reacts with nitrogen at a high temperature to cause embrittlement, and a high wattage element whose end portion temperature tends to increase is not suitable for lighting in a nitrogen atmosphere.

Further, in the configuration in which the end portion of the arc tube is sealed by a closing member having an external lead wire penetrated therein, the external lead wire and the closing member are not sufficiently joined to each other and sealed along the lead wire. There is a problem that the object leaks out of the arc tube and the lamp voltage is significantly reduced during lighting.

Further, in the above-described structure in which the end of the arc tube is sealed by the conductive cermet, the front surface of the sealing material is close to the discharge space and the temperature is high, so that the sealing material is softened or sealed. There is a problem that a reaction occurs with the substance and the optical characteristics are significantly reduced in a short time.

Further, the luminous efficiency of each conventional example is examined.
For example, the color rendering performance was as low as about 80 lm / W.
As described above, although higher luminous efficiency is desired, there has been a problem that means for improving luminous efficiency has not been considered.

Also, when the luminous flux rising time (time until a luminous flux of 90% of a stable state is obtained) in the initial lighting period was examined, it was as long as about 13 to 15 minutes. As described above, although a shorter luminous flux rise time is desired, the conventional metal vapor discharge lamp has a problem that no means for improving it is considered.

The present invention has been made in order to solve such a problem, and has a highly reliable sealing portion capable of obtaining stable optical characteristics over a long life, improves luminous efficiency, and improves lighting efficiency. An object of the present invention is to provide a metal vapor discharge lamp capable of improving the luminous flux rising characteristics in the initial stage.

[0018]

According to the present invention, there is provided a metal vapor discharge lamp comprising: a light emitting portion in which a light emitting metal is sealed and having a pair of electrodes; and thin tube portions provided at both ends of the light emitting portion. A light-transmitting ceramic light-emitting element having a power supply body made of a conductive cermet inserted into the thin tube portion and having an end portion opposite to the light emitting portion sealed in the thin tube portion with a sealing material. A tube, wherein the electrode is provided at a light emitting portion side end of the conductive cermet, and an end of the conductive cermet opposite to the electrode connection side extends at least to the thin tube end. The temperature of the end face on the discharge space side of the sealing material is 800 ° C. at the maximum.
The specific resistance of the conductive cermet at 20 ° C.
Is not less than 10.0 × 10 ⁻⁸ Ωm and not more than 25.0 × 10 ⁻⁸ Ωm
It has a configuration Ru under der.

As a result, the bonding force at the interface between the sealing material and the thin tube and the conductive cermet at the sealing portion is strengthened, airtightness is maintained for a long time, and cracks are generated even in a high wattage lamp of 150 watts or more. A metal vapor discharge lamp having a highly reliable sealing portion that can be prevented can be provided.

Further, by limiting the temperature of the end face of the sealing material (glass frit) on the side of the discharge space, the reaction between the glass frit and the enclosure can be suppressed, and the metal vapor discharge lamp having stable optical characteristics throughout its life. Can be provided.
As a means for lowering the temperature of the sealing portion, since Nb or the like which reacts with nitrogen at a high temperature is not used, nitrogen can be sealed in the outer tube. Thereby, the heat of the sealing portion is lost by the nitrogen, the temperature of the glass frit can be lowered, and the reaction can be suppressed. further,
By attaching a heat retaining tube, the temperature of the sealed
Thus, the reaction between the enclosure and the glass frit can be suppressed, and a desired light color can be obtained. Further
In the early stage of lighting of the metal vapor discharge lamp,
The temperature can be raised quickly.

As described above, in the configuration of the present invention, stable optical characteristics can be obtained in long-term lighting.
In recent years, this type of lamp has been required to have a long life and to have high luminous efficiency and excellent startup characteristics. As a result of examining the cause of the decrease in luminous efficiency in the conventional metal vapor discharge lamp, the inventor has found that the cause is heat loss from the discharge space. Further, it has been found that a factor for improving the luminous flux rising characteristic is related to the temperature of the sealed object.

The present invention has been made based on such findings, and has the following means.

The metal vapor discharge lamp according to the present invention is characterized in that
In the invention described in the above, the thermal conductivity of the conductive cermet at 20 ° C. is 0.28 (cal / cm · sec ·
deg) or less.

[0024] This makes it possible to reduce the heat loss that is lost by conducting the conductive cermet from the discharge space.

[0025] The metal vapor discharge lamp of the present invention is defined in claim 1.
Alternatively, in the invention according to claim 2, the outer diameter r (mm) of the conductive cermet is 4.9 × 10 ⁻³ P + 0.53 (mm) or less, where P (W) is the lamp power. It has a configuration.

As a result, higher luminous efficiency can be obtained than before .

[0027]

[0028] The metal vapor discharge lamp of the present invention is characterized in claim 1.
The distance L (m) between the discharge space side end surface of the sealing material and the discharge space in the invention according to any one of claims 1 to 3 ,
m) is P (W), and (3/11)
5) P + 355/115 (mm) or more.

Thus, the temperature of the end face of the sealing material on the side of the discharge space can be made 800 ° C. or less, and a metal vapor discharge lamp with little change in optical characteristics during long-time operation can be obtained.

The metal vapor discharge lamp according to the present invention is described in claim 1.
The invention according to any one of the first to fourth aspects, wherein a structure is provided in which a heat retaining cylinder that surrounds the thin tube portion is provided.

As a result, the temperature of the enclosure can be adjusted, the life is stabilized, and a desired light color can be obtained.

The metal vapor discharge lamp according to the present invention is described in claim 1.
In the invention according to any one of the first to fifth aspects, the arc tube is provided in an outer tube, and nitrogen is sealed in the outer tube.

As a result, the temperature of the sealing portion can be lowered, and stable optical characteristics can be obtained throughout the life.

[0034]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a metal vapor discharge lamp with a lamp power of 150 W according to a first embodiment of the present invention has a light-emitting tube 1 made of a translucent ceramic made of, for example, polycrystalline alumina, and a light-emitting tube. An outer tube 2 surrounding the tube 1 and metal wires 3a and 3b for fixing the arc tube 1 in the outer tube 2 are provided. A predetermined pressure of nitrogen is sealed in the outer tube 2.
In addition, 4 in a figure shows a base.

As shown in FIG. 2, the arc tube 1 includes a main tube portion 5 having a maximum outer diameter of, for example, 10 mm, and a thin tube portion 6 having an inner diameter of 1.0 mm provided at both ends of the main tube portion 5, as shown in FIG. Having. Also, a predetermined amount of mercury, a rare gas for starting, for example, argon gas, and dysprosium iodide, thallium iodide, sodium iodide and the like as metal halides are sealed in the arc tube 1.

A conductive cermet 7, which is a power supply having an outer diameter of 0.9 mm, is inserted into each thin tube portion 6, and is sealed by a glass frit 8.

The conductive cermet 7 is obtained by mixing and sintering a powder of molybdenum or a powder of tungsten and a powder of alumina. In addition, conductive cermet 7
Has a thermal expansion coefficient substantially equal to that of the arc tube 1. The conductive cermet 7 used here is obtained by mixing and sintering molybdenum and alumina at a weight ratio of 50:50, and has a thermal expansion coefficient of about 7.0 × 10 ^−6. Is higher, for example, 250 watts or 400 watts, it is preferable to further increase the mixing ratio of alumina to make it closer to the thermal expansion coefficient of alumina.

The conductive cermet 7 protrudes out of the arc tube by a length of 10 mm from the end of the thin tube portion 6, and is directly welded to the metal wires 3a and 3b, respectively.

Here, the conductive cermet 7 is connected to the thin tube portion 6.
Is protruded from the end by a length of 10 mm, but may be flush with the end face of the thin tube portion 6. In this case, it is necessary to join an external lead wire or the like to the end of the conductive cermet 7 on the side opposite to the joint side with the electrode. Since the bonding force at the interface with the glass frit 8 is low, there is a risk that arc tube leakage will occur. Therefore, it is preferable that the conductive cermet 7 protrudes from the end of the thin tube portion 6.

The glass frit 8 is made of dysprosium oxide, alumina, silica, or the like, and has a gap between the inner surface of the thin tube portion 6 and the outer surface of the conductive cermet 7 as shown in FIG.
The glass frit 8 is poured to a position where the distance L between the end face on the discharge space side and the end face on the discharge space becomes 7 mm. The discharge space is defined as a space formed by a surface including the inner surface of the main tube portion 5 and the end surface of the thin tube portion 6 on the main tube portion 5 side.

The electrodes 9 are connected to the conductive cermet 7 and provided so as to face each other in the main pipe portion 5. The distance between each electrode 9 is 10 mm.

In the metal vapor discharge lamp of the present embodiment, the temperature of the end face of the glass frit 8 on the discharge space side is set to 75.
0, 800, 850, 900, 950 ° C.
The luminous flux maintenance rate during the life of 100 pieces was examined, and the results as shown in FIG. 4 were obtained. The temperature is measured by attaching a platinum-platinum rhodium thermocouple to the outer surface of the thin tube portion 6 at the discharge space side end of the glass frit 8 and calculating from the thickness of the thin tube portion 6 and the thermal conductivity of alumina. I asked. Symbol in FIG. 4 *
Indicates that the temperature of the glass frit 8 is 750 ° C.
° C, symbol △ is 850 ° C, symbol × is 900 ° C, symbol □ is 9
50 ° C. is indicated.

As is apparent from FIG. 4, when the temperature of the glass frit 8 is 850 ° C. or higher, the luminous flux maintenance factor is lower than 60% at the rated life of 6000 hours after the lamp is turned on. Observation of the cross section of the sealing portion at this time confirmed that the end face of the frit was severely eroded by the inclusion. Due to this, the luminescent metal was lost, causing a decrease in the luminous flux maintenance factor.

When the arc tube leakage at the lighting time at each temperature was examined, the results shown in Table 1 were obtained. When the temperature is 950 ° C., 50% or more of the lamps leak at 6000 hours, and when the temperature is 850 ° C., the lamp voltage gradually decreases after 7000 hours, and at 9000 hours, 30% or more of the lamps leak. Then, it turned off.
It was confirmed that the lamps at 800 ° C. or lower ensured a luminous flux maintenance ratio of 70% or more even after 6000 hours, 70% of the lamps were lit for 9000 hours, and 50% were lit for 12,000 hours or more without leaking.

[0046]

[Table 1]

In the above embodiment, the description has been given of the 150 W metal vapor discharge lamp.
Similar results were obtained with metal vapor discharge lamps such as W, 100 W, 250 W, and 400 W. Further, in the case of using Nb instead of the conductive cermet 7 as a power supply, the interface between the glass frit 8 and Nb is not as strong as the interface between the conductive cermet 7 and the glass frit 8, and in the long-term life, Lack of trust in airtightness. For a lamp of 150 W or more, for example, 250 W,
The diameter of the rod of the power feeder is increased, and the expansion coefficient is 7.2 × 10 ^-6
A small crack is generated between Nb, which is the above, and alumina, which is 8.0 × 10 ^-6 , and this crack grows during lighting,
An arc tube leak will result. The inventors assumed that the lamp power was 250 W, the frit temperature was 800 ° C., and the power supply was N
b, the life test of the lamp was performed.
Three out of 100 cracks occurred in 0 hours, 6
By 000 hours, 30 bottles leaked. When observing the cross section of the sealed portion of the lamp where the leak occurred, a very large number of very small cracks were found in the glass frit filling the gap between Nb and alumina, and several cracks grew to the end of the sealed portion. Iodine was detected between the two. On the other hand, the lamp of the present invention was turned on without leaking 70% or more in 9000 hours. This is because the cermet used has an expansion coefficient of 7.5 × 10 ⁻⁶ , can be closer to translucent alumina than Nb, and the adhesion of the sealing portion is N
It is considered that the reason is that cermet is stronger than b. In addition, nitrogen is sealed in the outer tube 2 of the lamp in order to lower the temperature of the sealing portion. However, in the case of using Nb as the power supply, the deterioration of Nb after 3000 hours is severe. This deterioration is also considered to be one of the causes of arc tube leakage.

Further, as shown in Table 2, the luminous efficiency of the metal vapor discharge lamp of this embodiment when the conductive cermets 7 having different thermal conductivities of Examples 1 to 3 were used was examined. As a result, the results shown in Table 2 were obtained. However, Example 1 to Example 3
And conductive cermet 7 having thermal conductivity of Comparative Example 1
Is obtained by sintering mixed powders in which the mixing ratio between the molybdenum powder and the alumina powder is variously changed. In particular, the conductive cermet 7 having the thermal conductivity of Comparative Example 1 has the largest thermal conductivity that can be produced practically when these materials are used. The conductive cermet 7 having the thermal conductivity of Comparative Example 2 is obtained by sintering a mixed powder of a powder of tungsten and a powder of alumina, and can be manufactured practically when these materials are used. It has the highest thermal conductivity.

The thermal conductivity described below is a value at 20 ° C. unless otherwise specified.

[0050]

[Table 2]

The luminous efficiency of a conventional metal vapor discharge lamp having a high color rendering, for example, is usually about 80 lm / W. On the other hand, as shown in Table 2, 0.28 (cal / cm
When the conductive cermet 7 having a thermal conductivity of not more than (.sec.deg) was used, the luminous efficiency was 95 lm / W or more. A luminous efficiency of 90 lm / W or more is practically sufficient. On the other hand, 0.28 (cal / cm · sec ·
deg) and 0.33 (cal / cm · sec)
· Deg) conductive cermet 7 having the following thermal conductivity:
When was used, the luminous efficiency was of a level that would not hinder practical use, but cracks easily occurred in the glass frit 8. 0.33 (cal / cm · sec · deg)
When a conductive cermet having a thermal conductivity exceeding the above range was used, the luminous efficiency was not sufficient for practical use, and cracks were easily generated in the glass frit 8.

The reason why cracks are easily generated in the glass frit 8 is that the ratio of alumina contained in the conductive cermet 7 decreases as the thermal conductivity increases, and the heat of the conductive cermet 7 decreases. Expansion coefficient and arc tube 1
This is because the difference from that of becomes larger. Further, the occurrence of cracks in the glass frit 8 causes a leak to occur in a sealing portion between the thin tube portion 6 and the conductive cermet 7.

From this, the thermal conductivity was set to 0.28 (ca)
By setting the ratio to 1 / cm · sec · deg or less, the luminous efficiency can be improved by about 10% or more as compared with the conventional one, and the generation of cracks in the glass frit 8 can be prevented. This is conductive cermet 7
This is because, since the thermal conductivity of the conductive cermet 7 is small due to the low thermal conductivity of the conductive cermet 7 from the discharge space, the heat loss can be reduced. In addition, since the ratio of alumina contained in the conductive cermet 7 is increased, the coefficient of thermal expansion can be made substantially equal to that of the arc tube 1. The smaller the thermal conductivity, the better.

However, even if the thermal conductivity is small, if the outer diameter r (mm) of the conductive cermet 7 is large, the heat loss increases. Then, in order to solve such a problem, the thermal conductivity is 0.28 (cal / cm · sec · de).
g) Lamp power 150 W using conductive cermet 7
As shown in Table 3, the luminous efficiencies of the metal vapor discharge lamps of Example 3 or Example 4 and Comparative Examples 3 to 6 when the conductive cermets 7 having different outer diameters r were used were examined. As a result, the results shown in Table 3 were obtained.

[0055]

[Table 3]

As shown in Table 3, the outer diameter r was 1.265 m.
m, the luminous efficiency is 9
0 lm / W or more. On the other hand, the outer diameter r is 1.265 m
When the conductive cermet 7 exceeding m was used, practically sufficient luminous efficiency could not be obtained.

From the above, by setting the outer diameter r of the conductive cermet 7 to 1.265 mm or less, the outer diameter r is improved by 10% or more as compared with the normal luminous efficiency of the conventional high color rendering metal vapor discharge lamp. It can be seen that it can be done.
This is because it is possible to reduce heat loss that is lost by conducting the conductive cermet 7 from the discharge space. In addition, since a metal vapor discharge lamp having a higher luminous efficiency is desired in practical use, the outer diameter r is such that the luminous efficiency is 95 lm.
/ W or more and preferably 0.9 mm or less.

It should be noted that the inner diameter of the thin tube portion 6 is changed with the change of the outer diameter r. If the outer diameter r is too small, the conductive cermet 7 cannot withstand the current flowing therethrough or the generated voltage, and is damaged. Therefore, the conductive cermet 7 must have an outer diameter that can withstand these. .

As described above, the glass frit 8
It was confirmed that the reaction with the encapsulated metal halide was promoted when the temperature of the mixture became 800 ° C. or higher. As a result, the glass frit 8 is deteriorated, and a leak is generated at a sealing portion between the thin tube portion 6 and the conductive cermet 7. Therefore, in order to solve such a problem, a metal vapor having the above-described configuration of a lamp power of 150 W using a conductive cermet 7 having an outer diameter of 0.9 mm and a thermal conductivity of 0.28 (cal / cm · sec · deg) is used. In the discharge lamp, as shown in Table 4, the distance L between the discharge space side end face of the glass frit 8 and the discharge space was determined.
When the temperature of the end face of the glass frit 8 on the discharge space side and the presence or absence of leakage after lighting for 3000 hours were examined using metal vapor discharge lamps having various (mm) values, the results shown in Table 4 were obtained. Was.

[0060]

[Table 4]

As shown in Table 4, the leak can be prevented by setting the distance L to 7 mm or more. On the other hand, when the distance L is 6 mm or less, a leak occurs. This is because the end face of the glass frit 8 on the side of the discharge space and the discharge space that becomes hot during lighting are maintained at a predetermined distance as described above, so that the temperature is maintained at 800 ° C. or less. This is because the chemical reaction between the metal and the metal halide is suppressed.

As shown in FIG. 5, a 150 W metal vapor discharge lamp according to the second embodiment of the present invention is the same as the metal vapor discharge lamp according to the above embodiment, but with an inner diameter of 3.1 mm and a length of 5 mm.
The heat insulation tube 10 made of, for example, molybdenum made of metal having a thickness of 1 mm is attached to the outer periphery of the thin tube portion 6. Here, the distance L between the discharge space side end surface of the glass frit 8 and the discharge space was 8 mm, and the temperature was 700 ° C. As a result, stable optical characteristics could be obtained even during a long lighting time.

Further, the heat retaining cylinder 10 is connected to the glass frit 8
Attached to the narrow tube portion closer to the discharge space than the discharge space side end face and kept warm, the temperature of the sealed material is kept warm, and the temperature of the discharge space side end face of the glass frit 8 is 800 ° C. with the same filling amount. As a result, the same color characteristics could be obtained.

If the heat retaining cylinder 10 is extended to the end face of the glass frit 8 on the discharge space side, the temperature of the glass frit 8 rises, causing an arc tube leak.

In addition, according to such a configuration, unlike the conventional metal vapor discharge lamp, it is not necessary to fill the metal halide more than the amount that evaporates during operation. The amount of sealing can be reduced, and the cost can be reduced.

In the above embodiment, the case of a 150 W metal vapor discharge lamp has been described. However, the present invention is not limited to this. For example, a 35 W metal vapor discharge lamp, a 70 W metal vapor discharge lamp, a 100 W metal vapor discharge lamp , 2
A 50 W metal vapor discharge lamp, a 400 W metal vapor discharge lamp, or the like may be used. At this time, the outer diameter r (mm) of each metal vapor discharge lamp is such that the lamp power P (W) is 3
4.9 × 10 ⁻³ P + in the range of 5 W to 400 W
When the value is equal to or less than the value defined by 0.53, the luminous efficiency can be improved. Similarly, the distance L (mm) is
If the value is equal to or more than the value defined by (3/115) P + 355/115, the occurrence of a leak can be prevented.

Next, the specific resistance value was variously changed by changing the ratio of molybdenum in the conductive cermet 7, and as shown in Table 5, the conductive cermets 7 having different specific resistance values of Examples 5 to 7 and Comparative Example 7 were used. Rise time of the luminous flux in the initial lighting of the cermet (time required to obtain 90% of the luminous flux of the stable state)
And the luminous flux maintenance factor after lighting for 6000 hours was examined.

Incidentally, the specific resistance values described later are values at 20 ° C. unless otherwise specified.

[0069]

[Table 5]

The luminous flux rise time of the conventional metal vapor discharge lamp is usually about 13 to 15 minutes. On the other hand, as shown in Table 5, when the conductive cermet 7 having a specific resistance value of 10.0 × 10 ⁻⁸ Ωm or more was used, the luminous flux rising time was 10 minutes or less. Luminous flux rise time is 1
A time of 0 minutes or less is practically sufficient. On the other hand, 10.0
When the conductive cermet 7 having a specific resistance value of less than × 10 ⁻⁸ Ωm was used, the luminous flux rising time was not practically sufficient.

This is because the heat generation of the conductive cermet 7 increases as the specific resistance increases, so that the vicinity of the coolest portion of the arc tube 1 (the gap between the inner surface of the thin tube portion 6 and the outer surface of the conductive cermet 7) is filled. This is because the temperature of the object can be quickly increased.

However, as shown in Table 5, the specific resistance value was 3
In Comparative Example 7 using a conductive cermet exceeding 0.0 × 10 ⁻⁸ Ωm or more, the luminous flux maintenance factor after lighting for 6000 hours was reduced to 60%. If the specific resistance value is too large, the temperature of the sealing portion between the thin tube portion 6 and the conductive cermet 7 becomes too high, so that the metal halide adheres to the end face of the glass frit 8 on the discharge space side. This is because the amount of metal halide contributing to light emission decreases. Usually, if the luminous flux maintenance factor is 70% or more, there is no problem in practical use. Therefore, the specific resistance is preferably 25.0 × 10 ⁻⁸ Ωm or less.

In the above embodiment, the case where molybdenum is used as the constituent material of the conductive cermet 7 has been described, but tungsten may be used instead of molybdenum.

Although the case where nitrogen is sealed in the outer tube 2 has been described, the inside of the outer tube 2 may be evacuated to a vacuum. In this case, since the temperature of the sealing portion of the thin tube portion 6 increases, it is preferable to further increase the distance L between the glass frit 8 and the discharge space.

[0075]

As described above, the present invention has a highly reliable sealing portion capable of obtaining stable optical characteristics over a long life, improves the luminous efficiency, and improves the luminous flux rising characteristics at the beginning of lighting. An improved metal vapor discharge lamp can be provided.

[Brief description of the drawings]

FIG. 1 is a front view of a metal vapor discharge lamp according to a first embodiment of the present invention.

FIG. 2 is a partially cutaway front view of the arc tube.

FIG. 3 is an enlarged sectional view of a main part of the arc tube.

FIG. 4 is a diagram showing the relationship between the end face temperature of the frit on the discharge space side and the luminous flux maintenance factor.

FIG. 5 is a front view of a metal vapor discharge lamp according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arc tube 2 Outer tube 3a, 3b Metal wire 4 Base 5 Main tube part 6 Thin tube part 7 Conductive cermet 8 Glass frit 9 Electrode 10 Heat insulation tube

Continuation of the front page (72) Inventor Shunsuke Kakisaka 1-1, Kochi-cho, Takatsuki-shi, Osaka Prefecture Inside Matsushita Electronics Corporation (72) Inventor Kazuo Takeda 1-1, Kochi-cho, Takatsuki-shi, Osaka Matsushita Electronics Inside (72) Inventor Kenji Akiyoshi 1-1, Yukicho, Takatsuki-shi, Osaka Prefecture Inside Matsushita Electronics Corporation (72) Inventor Fumiki Nakayama 1-1-1, Yukicho, Takatsuki-shi, Osaka Matsushita Electronics Corporation (72) Inventor Takashi Yamamoto 1-1, Yukicho, Takatsuki-shi, Osaka Matsushita Electronics Corporation (56) References JP-A-6-89699 (JP, A) JP-A-57-196469 (JP) JP-A-9-213273 (JP, A) JP-A-63-21739 (JP, A) JP-A-61-220265 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB (Name) H01J 61/36

Claims (6)

(57) [Claims] 1. A light-emitting part in which a light-emitting metal is sealed and having a pair of electrodes, a thin tube provided at both ends of the light-emitting unit, and the light-emitting unit inserted into the thin tube and A light-transmitting ceramic light-emitting tube having a power supply body made of a conductive cermet sealed in the thin tube portion with an end portion opposite to the light-emitting portion side end of the conductive cermet. The part is provided with the electrode, the end of the conductive cermet opposite to the electrode connection side extends to at least the capillary end,
The temperature of the end face on the discharge space side of the sealing material is 800 ° C. or less.
Der is, the resistivity at 20 ° C. of the electrically conductive cermet
The value is 10.0 × 10 ⁻⁸ Ωm or more and 25.0 × 10 ⁻⁸ Ωm
Metal vapor discharge lamp, characterized in der Rukoto below. 2. The thermal conductivity of the conductive cermet at 20 ° C. is 0.28 (cal / cm · sec · de).
g) The metal vapor discharge lamp according to claim 1, wherein: 3. An outer diameter r (mm) of the conductive cermet.
Is 4.9 × 10 ⁻³ where P (W) is the lamp power.
The metal vapor discharge lamp according to claim 1 or 2, wherein P + 0.53 (mm) or less. 4. The distance L (mm) between the discharge space side end surface of the sealing material and the discharge space is determined by the lamp power P (W).
, (3/115) P + 355/115 (m
m) or more, the metal vapor discharge lamp according to any one of claims 1 to 3 . 5. A metal vapor discharge lamp according to any one of claims 1 to 4, characterized in that the heat insulating tube is provided encasing said capillary portion. 6. The arc tube is provided in an outer tube,
The metal vapor discharge lamp according to any one of claims 1 to 5 , wherein nitrogen is sealed in the outer tube.