JP2004111373A - Metallic vapor discharge lamp and illumination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metallic vapor discharge lamp and an illumination device wherein a color temperature is not changed and a characteristic is stablized for a long period of continuous lighting by suppressing sinking of a light-emitting metal. <P>SOLUTION: An arc tube 1 made of translucent ceramic has fine tube sections 12a and 12b at both ends of a main tube section 11. Power supply bodies 20a and 20b include an electrode section made of coils 22a and 22b of tungsten wound around one ends of electrode pins 21a and 21b of tungsten , and electrode support bodies 23a and 23b of conductive cermet connected to the other ends of the electrode pins 21a and 21b. When a lamp power is P(W), a length L1 of the electrode for use in the arc tube 1 ranges from (0.041P + 0.5) to (0.041P + 8.0) mm. Alternatively, a length L2 of the fine tube section of the arc tube 1 ranges from (0.032P + 3.5) to (0.032P + 8.0) mm. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a metal vapor discharge lamp and a lighting device equipped with the metal vapor discharge lamp, and more particularly to a metal vapor discharge lamp using an arc tube made of a translucent ceramic such as alumina ceramic.

The luminous tube in the metal halide lamp is such that a luminescent metal is sealed as a metal halide in a transparent container, and a pair of electrodes are provided in the container so as to face each other. It emits light at high temperatures.
As the container of the arc tube, a container made of quartz glass has been used in many cases, but in recent years, a container using alumina ceramic which is more excellent in heat resistance than quartz glass is becoming mainstream.

As a method for sealing the electrodes in the arc tube, in the case of quartz glass, a method of heating and crushing the side tube portion of the arc tube to seal it is used, but in the case of an alumina ceramic arc tube, the main tube portion is sealed. A container is formed in a shape in which a pair of thin tube portions extend from both ends of the container, and a feeder comprising an electrode and an electrode support is inserted into each of the thin tube portions, and a gap between an inner wall of the thin tube portion and the feeder is provided. A method of melting and pouring a sealing material such as frit glass for sealing is often used (Patent Document 1).

By the way, the arc tube made of alumina ceramic has various advantages and is expected to realize a high-performance lamp.
For example, an alumina ceramic arc tube can be lit at a higher temperature than a quartz glass arc tube, so that the vapor pressure of the enclosure can be increased, which is advantageous for achieving both high color rendering and high efficiency. It is.

Alumina ceramic is also advantageous in extending the life of a metal halide lamp in that it has lower reactivity with a metal halide sealed in an arc tube than quartz glass.
JP-A-57-77863

On the other hand, a metal halide lamp using such an alumina ceramic arc tube has a problem that the color temperature changes during life. That is, even if sufficient color temperature characteristics are obtained immediately after the start of use of a new lamp, the color temperature characteristics often change greatly in the course of, for example, 100 hours and 1000 hours after lighting.
The reason is considered as follows.

Since the alumina ceramic arc tube is sealed as described above, a gap is formed between the power supply and the thin tube portion in a portion not sealed by the sealing material.
During lighting, the liquid light emitting metal gradually sinks into the gap. In particular, when the lamp is turned on such that the electrodes of the lamp are oriented vertically, the luminescent metal sealed in the arc tube easily sinks into the gap located below.

Due to this sinking, the amount of metal contributing to light emission in the discharge space decreases, so that a sufficient vapor pressure of the metal cannot be obtained, and as a result, the color temperature changes.
In order to prevent such a color temperature change, it is conceivable to increase the amount of the luminescent metal sealed in the arc tube. However, if too much luminescent metal is encapsulated, the reaction between the luminescent metal and the electrode, alumina or sealing material is promoted, and the life characteristics are deteriorated.

Further, when the gap is filled by pouring the sealing material deep into the gap between the thin tube portion and the power supply body at the time of sealing, the sinking of the luminescent metal into the gap is suppressed.
However, in this case, since the end face of the sealing material is close to the discharge space, the temperature is considerably increased. Then, the reaction between the sealing material and the light emitting metal is promoted, which causes deterioration of the life characteristics. In addition, since cracks are easily generated in the sealing portion, this also causes the lamp life to be shortened.

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal vapor discharge lamp and an illuminating device capable of maintaining a stable characteristic with a small change in color temperature even when operated continuously for a long time by suppressing sinking of a luminescent metal.
Further, as another problem in the metal halide lamp using the alumina ceramic arc tube, when cerium is contained in the luminous metal, the lamp may go out at the time of initial aging immediately after the lamp is manufactured. The purpose is also to suppress.

In order to achieve the above object, the present invention has a light-emitting container made of a translucent ceramic, an electrode portion and an electrode support are inserted into each capillary portion, and the electrode support is sealed by a sealing material in the capillary portion. In a metal vapor discharge lamp provided with an arc tube formed as described above, the electrode length L1 of the electrode portion used for the arc tube is (0.041P + 0.5) mm or more and (0. 041P + 8.0) mm or less.

Here, the electrode length L1 indicates the distance from the tip of the electrode portion to the connection end of the electrode portion (the end connected to the electrode support). The lamp power indicates the lamp power at the time of stable lighting.
In the metal vapor discharge lamp described above, it is preferable that the length l1 of the electrode portion protruding from the thin tube portion into the discharge space is not less than 3.0 mm and not more than 6.5 mm.
Further, it is preferable that the electrode portion has a thermal conductivity of 130 (W / m · K) or more, and the electrode support has a thermal conductivity of 100 (W / m · K) or less. preferable.

Preferred materials used for the electrode portion include tungsten and molybdenum, and preferred materials used for the electrode support include cermet.
Also, in order to more reliably obtain the effect of suppressing the sinking amount of the luminescent metal, the length L2 of the thin tube portion of the arc tube is set to a value within a range of (0.032P + 3.5) mm or more and (0.032P + 8.0) mm or less. It is preferable to set.

In addition, setting the pouring length l2 of the sealing material into the narrow tube portion to be 3.7 mm or more and 5.5 mm or less, in order to further enhance the reliability of the sealed portion during life and maintain stable characteristics. preferable.
In a metal vapor discharge lamp having a lamp power in the range of 70 W to 400 W, it is sufficient to set the electrode length L1 to (0.041P + 0.5) mm or more and (0.041P + 8.0) mm or less. It has been confirmed that the effect can be obtained.

In addition, the above object is to provide a light emitting vessel having a light emitting container made of a translucent ceramic, an electrode portion and an electrode support being inserted into each of the thin tube portions, and the electrode support being sealed in the thin tube portion by a sealing material. In the metal vapor discharge lamp provided, when the lamp power is P (W), the length L2 of the thin tube portion of the arc tube is not less than (0.032P + 3.5) mm and not more than (0.032P + 8.0) mm. It can be achieved even if it is set within the range.

In a metal vapor discharge lamp having a lamp power in the range of 70 W to 360 W, the length L2 of the thin tube portion is set to a range of (0.032P + 3.5) mm or more and (0.032P + 8.0) mm or less. It has been confirmed that a sufficient effect can be obtained by setting.
Here, if the length L2 of the thin tube portion is set in the range of (0.032P + 3.5) mm or more and (0.032P + 6.0) mm or less, the effect of reducing the sinking of the luminescent metal and the effect of reducing the disappearance of the luminescent metal can be further improved. it can.

In the above metal vapor discharge lamp, it is preferable that the length l2 of the flow of the sealing material into the narrow tube portion is set to 3.7 mm or more and 5.5 mm or less, so that the reliability of the sealed portion during life is further improved and stable characteristics are obtained. Is preferable for maintaining the above.
In addition, the thickness of the thin tube portion of the light emitting container constituting the arc tube is 1.15 times or more the thickness of the main tube portion, or the main tube portion and the thin tube portion of the light emitting container are shrink-fitted. In the case where the luminous tube is formed integrally and does not have the luminous tube or the luminous tube is provided in the outer tube filled with nitrogen, the luminous metal easily sinks into the thin tube portion of the luminous tube. The invention is therefore particularly effective for this type of metal vapor discharge lamp.

By setting the electrode length L1 to (0.041P + 8.0) mm or less as described above, the sinking amount of the luminescent metal can be suppressed low. As a result, a vapor pressure in the discharge space can be sufficiently maintained during lighting, and a metal vapor discharge lamp that has a small change in color temperature even when the lighting is continuously performed for a long time and maintains stable characteristics can be realized.

On the other hand, by setting the electrode length L1 to (0.041P + 0.5) mm or more, the reaction between the sealing material and the luminescent metal is promoted, and the occurrence of cracks in the sealing portion is suppressed.
Further, as described above, by setting the thin tube portion length L2 to (0.032P + 8.0) mm or less, the sinking amount of the luminescent metal can be suppressed low. As a result, it is possible to realize a metal vapor discharge lamp that can maintain a sufficient vapor pressure in the discharge space during operation, has a small change in color temperature even when operated continuously for a long time, and maintains stable characteristics.

On the other hand, by setting the length L2 of the thin tube portion to (0.032P + 3.5) mm or more, the reaction between the sealing material and the luminescent metal is promoted, and the occurrence of cracks in the sealing portion is suppressed.
Further, by setting the length L2 of the thin tube portion to be in the range of (0.032P + 3.5) mm or more and (0.032P + 8.0) mm or less, the problem of extinction can be reduced. It is effective when is included.

An embodiment of the present invention will be described with reference to the drawings.
(Overall configuration of metal vapor discharge lamp and configuration of arc tube)
FIG. 1 is a front view (partial cross section) showing the configuration of the metal vapor discharge lamp according to the present embodiment.
As shown in FIG. 1, in this metal vapor discharge lamp, an arc tube 1 made of translucent ceramic is placed in a predetermined position by power supply lines 2a and 2b in an outer tube 3 in which nitrogen is sealed at a predetermined pressure. The outer tube 3 is provided with a base 4 near the sealing portion.

FIG. 2 is a sectional view showing the configuration of the arc tube 1.
As shown in FIG. 2, the arc tube 1 is configured by inserting power feeders 20a and 20b into a container 10 having narrow tubes 12a and 12b at both ends of a main tube (light emitting portion) 11 forming a discharge space. ing. Alumina ceramic is typical as a translucent ceramic forming the container 10.

The power supply bodies 20a and 20b are formed by winding coils 22a and 22b made of tungsten around the tips of electrode pins 21a and 21b made of tungsten to form electrodes. The electrode supports 23a and 23b made of cermet are joined together. The conductive cermet is obtained by mixing and sintering a metal powder and a ceramic powder, and has a thermal expansion coefficient substantially equal to that of the ceramic.

The electrode pins 21a and 21 and the electrode supports 23a and 23b are joined by laser welding.
If this joining is carried out by resistance welding by butt (butt welding), it is difficult to obtain the joining strength due to the large specific resistance value of the cermet, but sufficient joining strength is obtained by joining by laser welding, and during the life, In welding at, slippage is unlikely to occur.

The electrode pins 21a and 21 and the electrode supports 23a and 23b are connected in the thin tube portions 12a and 12b.
The tips of the electrode pins 21a and 21b protrude into the discharge space from the narrow tube portions 12a and 12b, and the coils 22a and 22b attached to the tips are arranged to face each other in the discharge space of the container 10. .

The other ends of the electrode supports 23a and 23b protrude outward from the thin tubes 12a and 12b, and the gaps between the electrode supports 23a and 23b and the thin tubes 12a and 12b are formed by seals 24a and 24b. Sealed.
The seal portions 24a and 24b are formed by pouring a glass frit made of metal oxide, alumina, silica, or the like inward from the ends of the thin tube portions 12a and 12b.

Mercury, a rare gas, and a luminescent metal are sealed in a discharge space in the main pipe portion 11.
In the metal vapor discharge lamp having the above configuration, a sine wave voltage having a frequency of, for example, 60 Hz and a peak voltage of 283 V is applied to the power supply bodies 20a and 20b from the external drive circuit via the base 4 and the power supply lines 2a and 2b. Keep lighting by.
(Configuration of lighting device)
FIG. 3 is a schematic sectional view showing an example of a lighting device equipped with the metal vapor discharge lamp.

The lighting device 30 is configured by mounting the discharge lamp 34 on a lighting device main body including a base 31 for mounting on a ceiling surface or the like, a socket 32 and a reflection shade 33 mounted on the base 31. The discharge lamp 34 is mounted on the socket 32 with its base facing upward. The reflection shade 33 is conical and has a reflection surface formed on the inner surface side. The reflection shade 34 is attached so as to surround the discharge lamp 34 with its opening directed downward. The lighting circuit device (not shown) is provided in a place different from the lighting device main body.

In the lighting device 30, the discharge lamp 34 is energized from the lighting circuit device via the socket 32 to turn on the lamp 34, and the visible light from the lamp 34 is reflected by the reflecting surface of the reflecting shade 33 or the reflecting shade 33 Is radiated downward through the opening of.
(Relationship between electrode length L1 and lamp characteristics)
In the present embodiment, the electrode lengths L1 (mm) of the electrode pins 21a and 21b are set within the range of the following equation (1).

0.041P + 0.5 ≦ L1 ≦ 0.041P + 8.0 (Equation 1)
Here, P is lamp power (W).
By setting the electrode length L1 in the range of Equation 1 as described above, as can be seen from the results of the following experiment 1, the sinking of the luminescent metal is suppressed, cracks are generated in the sealing portion, and the sealing portion and the luminescent metal are separated from each other. Reaction can be suppressed. Therefore, it is possible to suppress a change in color temperature over a long period of time and to ensure a long life.

This will be described in detail below.
First, whether or not the sinking of the luminescent metal easily occurs depends largely on the temperature in the vicinity of the gap G. Here, the gap G indicates the entire area of the gap formed between the electrode pins 21a and 21b and the narrow tube portions 12a and 12b, and particularly important is the temperature of the gap near the end surfaces of the seal portions 24a and 24b.

That is, if the temperature of the electrode pins 21a and 21b in the thin tube portions 12a and 12b and the temperature of the inner wall facing the electrode pins 21a and 21b in the thin tube portions 12a and 12b are low, the encapsulated luminescent metal will Because it becomes liquid, it sinks.
On the other hand, if the electrode length L1 is set to (0.041P + 8.0) mm or less as described above, the temperature in the vicinity of the gap G is high enough to vaporize the liquid luminescent metal during lamp operation. Will be kept.

The mechanism is considered as follows.
Since the electrode pins 21a and 21b have high thermal conductivity, heat from the positive column is easily transmitted. On the other hand, since the electrode supports 23a and 23b have low thermal conductivity, heat from the electrode pins 21a and 21b is hardly transmitted. Therefore, the temperature near the gap G, particularly near the end faces of the seal portions 24a and 24b is greatly affected by the length (heat capacity) of the electrode pins 21a and 21b. If the length of the electrode pins 21a and 21b is long, the distance from the positive column is long and the heat capacity is large, so that the temperature near the gap G, particularly near the end faces of the seal portions 24a and 24b decreases (conversely, the electrode pin 21a -If the length of 21b is short, the temperature near the gap G will increase).

As described above, the temperature near the gap G, particularly near the end surfaces of the seal portions 24a and 24b is kept high, so that the sinking amount of the luminescent metal can be suppressed low.
On the other hand, if the electrode length L1 is too short, the end faces of the seal portions 24a and 24b facing the gap G become hot, so that the reaction between the seal material and the luminescent metal is promoted.
When the electrode pins 21a and 21b and the electrode supports 23a and 23b are laser-welded, the alumina layer becomes rich on the surface of the welded portion. The reaction between the weld and the luminescent metal is promoted. Then, when the luminescent metal reacts, the tube voltage rises, causing the lamp to go out early and cause a short life.

If the end faces of the seal portions 24a and 24b are too hot, cracks are likely to occur in the seal portions 24a and 24b.
On the other hand, if the electrode length L1 is set to (0.041P + 0.5) mm or more, the temperature of the end faces of the seal portions 24a and 24b does not become too high. And the reaction with the luminescent metal is suppressed.

(About electrode protrusion length 11)
It is preferable that the length of the electrode pins 21a and 21b protruding inward into the discharge space from the thin tube portions 12a and 12b, that is, the electrode protrusion length l1 is not less than 3.0 mm and not more than 6.5 mm. The reason is as follows.
If it is smaller than 3.0 mm, the wall of the tube at the boundary between the main tube 11 and the narrow tubes 12a and 12b approaches the positive column too much, and the temperature of the tube becomes too high. The reaction between the wall and the encapsulating metal (luminescent metal) is promoted. On the other hand, if it exceeds 6.5 mm, the distance between the positive column and the thin tube portions 12a and 12b is too large, and the temperature of the thin tube portions 12a and 12b, and furthermore, the temperature of the gap G becomes too low. Metal) easily sinks into the thin tube portions 12a and 12b. Here, the boundary between the thin tube portions 12a and 12b and the discharge space is a portion where the inner diameter of the thin tube portions 12a and 12b starts to substantially expand.

(Example in which coils 25a and 25b are wound)
In the example of FIG. 2 described above, a gap G corresponding to the diameter difference between the inner peripheral surfaces of the thin tube portions 12a and 12b and the outer peripheral surfaces of the electrode pins 21a and 21b exists.
FIG. 4 is an example in which coils 25a and 25b made of molybdenum are wound around outer peripheral portions in the thin tube portions 12a and 12b of the electrode pins 21a and 21b.

The contents described above can be similarly applied to such a type, and achieve the same effects.
That is, as described above, since the gaps G are considerably filled by the coils 25a and 25b being wound around the electrode pins 21a and 21b, sinking is reduced, and the reaction between the sealing material and the luminescent metal is less likely to occur. However, since the gap G is not completely filled with only the coils 25a and 25b, similar sinking and reaction between the sealing material and the luminescent metal may occur.

Here, when the electrode length L1 (mm) is adjusted within the range of the above formula 1, the effect of similarly suppressing the sinking and the reaction between the sealing material and the luminescent metal can be obtained.
(About form of electrode part and electrode length L1)
FIG. 5 is a sectional view illustrating the electrode length L1. Usually, the length of the electrode portion (electrode length L1) is the length of the electrode pins 21a and 21b, or the length from the tips of the coils 22a and 22b to the connection ends of the electrode pins 21a and 21b with the electrode support. . For example, as shown in FIG. 5A, the same applies to the case where the connection ends of the electrode pins 21a and 21b are embedded in the electrode supports 23a and 23b. -The length of 21b corresponds to the electrode length L1.

On the other hand, exceptionally, as shown in FIG. 5B, the coils 25a and 25b extend over the outer peripheral surfaces of the electrode pins 21a and 21b and the outer peripheral surfaces of the electrode supports 23a and 23b in the thin tube portions 12a and 12b. Is wound, the distance from the tip of the electrode pin 21a / 21b or the tip of the coil 22a / 22b to the end of the coil 25a / 25b (the end opposite to the discharge space) corresponds to the electrode length L1. I do.

(Thermal conductivity of electrode part and electrode support)
As a material for the electrode pins 21a and 21b and the coils 22a and 22b, tungsten, which is a high melting point metal, is used as described above, and its thermal conductivity is 130 (W / m · K) or more. Further, as shown in FIG. 4, the coils 25a and 25b made of molybdenum may be wound around the electrode pins 21a and 21b, but the thermal conductivity of molybdenum is also 130 (W / mK) or more.

Therefore, the electrode portion including the electrode pins 21a and 21b and the coils 22a and 22b, or the electrode portion including the electrode pins 21a and 21b, the coils 22a and 22b, and the coils 25a and 25b has a thermal conductivity of 130 (W). / M · K) or more.
On the other hand, as a material of the electrode supports 23a and 23b, a conductive cermet is used, and it is preferable to use a material having a thermal conductivity of 100 (W / m · K) or less which is lower than that of the electrode portion.

This is because, as can be seen from the results of Experiment 2 below, when the thermal conductivity of the electrode supports 23a and 23b is as high as that of the electrode portion, heat is easily released from the electrode pins to the electrode support. This is because the temperature is lowered and sinking easily occurs.
(Relationship between capillary length L2 and lamp characteristics)
In the present embodiment, the length L2 (mm) of the thin tube portion of the arc tube is set within the range of the following mathematical expression 2. In the following, P is lamp power (W).

0.032P + 3.5 ≦ L2 ≦ 0.032P + 8.0 (Equation 2)
Further, the thin tube portion length L2 indicates the length of a portion from the end of the thin tube portions 12a and 12b to a portion where the tube diameter starts to widen. Usually, the diameter of this portion is substantially constant.
By setting the length L2 of the thin tube portion in the range of the expression 2 as described above, as can be seen from the results of the following experiment 3, the sinking of the luminescent metal is suppressed, and the generation of cracks in the seal portion and the emission of the luminescent metal from the seal portion The reaction with the metal seal can be suppressed. Therefore, the color temperature can be maintained over a long period of time and the life can be extended.

In order to more reliably obtain the effect of suppressing the sinking amount of the luminescent metal, it is preferable that the electrode length L1 is set within the range of Expression 1 and the thin tube portion length L2 is set within the range of Expression 2.
This will be described in detail below.
First, whether or not the sinking of the luminescent metal easily occurs depends largely on the temperature in the vicinity of the gap G.

That is, if the temperature of the electrode pins 21a and 21b in the thin tube portions 12a and 12b and the temperature of the inner wall facing the electrode pins 21a and 21b in the thin tube portions 12a and 12b are low, the light-emitting metal sealed in the gap G Because it does not evaporate and becomes liquid, it sinks.
On the other hand, if the length L2 of the thin tube portion is set to (0.032P + 8.0) mm or less as described above, the temperature in the vicinity of the gap G is high enough to vaporize the liquid luminescent metal during lamp operation. Will be kept.

The mechanism is considered as follows.
The temperature near the gap G, especially near the end faces of the seal portions 24a and 24b is greatly affected by the length L2 of the thin tube portion. When the length of the thin tube portion L2 is long, the distance from the positive column becomes long and the heat capacity is large. Therefore, the temperature near the gap G, particularly near the end faces of the seal portions 24a and 24b becomes low. The temperature near G increases).

On the other hand, if the length L2 of the thin tube portion is too short, the end surfaces of the seal portions 24a and 24b facing the gap G are at a high temperature, so that the reaction between the seal material and the luminescent metal is promoted.
When the electrode pins 21a and 21b and the electrode supports 23a and 23b are laser-welded, the alumina layer becomes rich on the surface of the welded portion. The reaction between the weld and the luminescent metal is promoted. When the luminescent metal reacts, problems such as an increase in the tube voltage occur.

If the end faces of the seal portions 24a and 24b are too hot, cracks are likely to occur in the seal portions 24a and 24b.
On the other hand, if the thin tube portion length L2 is set to (0.032P + 3.5) mm or more, the temperature of the end faces of the seal portions 24a and 24b will not be too high. And the reaction with the luminescent metal is suppressed.

(Relationship between capillary length L2 and lamp extinguishing)
In a metal vapor discharge lamp, when luminous metal contains cerium, a extinction may occur immediately after lighting. In particular, at the time of the initial aging lighting immediately after the lamp is manufactured, the extinction easily occurs immediately after the lighting. On the other hand, if the length L2 of the thin tube portion is set within the range of the above expression 2, in addition to the above-described effects, the problem of the disappearance immediately after the start of lighting can be reduced.

Further, it is more effective to set the thin tube portion length L2 (mm) in the range of the following equation (3).
0.032P + 3.5 ≦ L2 ≦ 0.032P + 6.0 (Equation 3)
Here, P is lamp power (W).
In the following, the mechanism of the occurrence of the extinction and the effect of suppressing the extinction by setting the length of the thin tube portion L2 short will be described.

FIG. 6 is a diagram for explaining the occurrence of the disappearance at the time of lighting.
In this figure, Vm is the power supply voltage input to the drive circuit, and Vla is the lamp voltage applied to the lamp.
In FIG. 6, the voltage at the top of the ramp voltage Vla waveform corresponds to the restriking voltage.

(4) When lighting starts, the lamp voltage Vla gradually increases. However, when cerium Ce is contained in the luminescent metal, the re-ignition voltage tends to sharply increase for a while (several tens of seconds) from the start of lighting. In FIG. 6 as well, at the fifth peak, the re-ignition voltage sharply increases. This is because if the tube wall temperature of the arc tube rises to some extent after the start of lighting, cerium Ce evaporates rapidly, and at this time, arc discharge fluctuation (arc fluctuation) occurs.

Here, if the speed at which the tube wall temperature of the arc tube rises after the start of lighting is low, it takes a long time until cerium evaporates, so that the re-ignition voltage sharply rises when the lamp voltage Vla rises considerably. I do. Then, since the value of the re-ignition voltage at this point becomes considerably high, the difference VA between the power supply voltage Vm and the re-ignition voltage may become zero.
Also in the waveform shown in FIG. 6, the re-ignition voltage sharply increases at the fifth peak, and the difference voltage VA between the power supply voltage Vm and the re-ignition voltage becomes zero.

As described above, when the difference voltage VA between the power supply voltage Vm and the re-ignition voltage becomes 0, the extinction occurs at that time.
On the other hand, if the length L2 of the thin tube portion is shortened, the speed at which the tube wall temperature of the arc tube increases increases, and the time until cerium evaporates becomes shorter. Therefore, when the cerium evaporates, the lamp voltage Vla itself is not so high, so that even if the restrike voltage increases, the difference voltage VA between the power supply voltage Vm and the restrike voltage is unlikely to become zero.

The amount of the luminescent metal sealed in the discharge space was 13.5 mg, and its composition was CeI ₃ (cerium 5.4 mg), NaI (sodium 7.1 mg), TlI (thallium 0.6 mg), and InI (indium 0.1 mg). It has been experimentally confirmed that, for a metal vapor discharge lamp of 4 mg), the extinction is suppressed by setting the thin tube portion length L2 to (0.032P + 8.0) mm or less.

(About the casting length l2 of the sealing material and the thickness of the light emitting container)
In the metal vapor discharge lamp, the length l2 (mm) of pouring the sealing material into the narrow tube portion is preferably set within the range of Expression 4.
3.7 ≦ l2 ≦ 5.5 (Equation 4)
As a result, as can be seen from the results of Experiment 4 below, it is possible to further enhance the reliability of the sealing portion during life and maintain stable characteristics.

In the ceramic light emitting container, the thickness t2 of the thin tube portion is usually 1.15 times or more the thickness t1 of the main tube portion 11.
As described above, when the thickness t2 of the thin tube portion is larger than the thickness t1 of the main tube portion 11, the temperature near the gap G, particularly near the end faces of the seal portions 24a and 24b tends to be low. In this way, it is effective to suppress the sinking by setting the capillary portion length L2 as in the above equation (2) or (3).

(Modifications, etc.)
By the way, since the problem of sinking mainly occurs in the thin tube portion located vertically below, when it is determined that one of the thin tube portion 12a and the thin tube portion 12b of the arc tube 1 is located vertically below, Similar effects can be expected if the thin tube portion length L2 and the like are defined as described above for the lower portion.

However, when the mounting posture of the lamp is not determined, since both the thin tube portion 12a and the thin tube portion 12b of the arc tube 1 may be located vertically below, the thin tube portions 12a and 12b have been described above. It is preferable that the contents be applied to both the pair of thin tube portions 12a and 12b.

The metal vapor discharge lamp according to the present embodiment has a lamp power P = 300 W, and the types and sizes of the respective members are as follows.
The thin tube portion length L2 was 15.8 mm.
The electrode pins 21a and 21b had an outer diameter of 0.71 mm and a length of 17.8 mm.
As the conductive cermets of the electrode supports 23a and 23b, those obtained by mixing and sintering molybdenum and alumina are used. The thermal expansion coefficient is 7.0 × 10 ⁻⁶ , and the thermal conductivity is 70 (W / m). K). The sizes of the electrode supports 23a and 23b are 1.3 mm in outer diameter and 30 mm in length.

The amount of the luminescent metal sealed in the discharge space was 13.5 mg, and the composition was 2.6 mg of DyI3, 2.6 mg of HoI3, 2.6 mg of TmI3, 3.3 mg of NaI, and 2.4 mg of TlI. did. In addition, 20 kPa of argon was sealed as a rare gas in the discharge space.
The inner diameter of the thin tube portions 12a and 12b was 1.3 mm, the thickness t1 of the main tube portion 11 was 1.1 mm, and the thickness t2 of the thin tube portions 12a and 12b was 1.35 mm.

Various experiments described below were performed on the metal vapor discharge lamps of the examples. In these experiments, coils obtained by winding coils 25a and 25b made of molybdenum around the electrode pins 21a and 21b were used.
(Experiment 1)
In the metal vapor discharge lamp of the example, when the electrode length L1 was changed to 11.8 mm, 12.8 mm, 16.3 mm, 19.8 mm, and 20.8 mm, a life test was performed for 3000 hours, and the tube voltage rise during that time (V) and color temperature change (K) were measured.

The length of the gap G (the distance from the discharge space side ends of the narrow tube portions 12a and 12b to the end surfaces of the seal portions 24a and 24b) was kept constant at 4.5 mm.
Table 1 shows the results.
In the column of evaluation in Table 1, “」 ”indicates“ good ”and“ x ”indicates“ poor ”(Tables 2 to 6 also apply).

From Table 1, it can be seen that the tube voltage rise is very small in the range of 12.8 mm or more as compared with the case where the electrode length L1 is 11.8 mm.
This is presumably because when the electrode length L1 is less than 12.8 mm, the end faces of the seal portions 24a and 24b become hot and react with the luminescent metal, but when the electrode length L1 is 12.8 mm or more, the reaction was suppressed.

On the other hand, Table 1 shows that when the electrode length L1 is 19.8 mm or less, the color temperature change during life is extremely small.
This is considered to be because the temperature of the inner wall of the thin tube portion was kept moderately high and the sinking was suppressed by setting the electrode length L1 to 19.8 mm or less.
As described above, when P = 300 W, it can be seen that when the electrode length L1 is in the range of 12.8 mm to 19.8 mm (that is, in the range of the above equation (1)), it is possible to suppress a rise in tube voltage and a change in color temperature during lighting.

Also, in a metal vapor discharge lamp having a lamp output P = 70 W using the electrode pins 21a and 21b having an outer diameter of 0.35 mm, the electrode length L1 is set to 3.0 mm, 3.5 mm, 7.0 mm, 10.8 mm, 11 In the case where the diameter was changed to 0.3 mm, a 3000-hour life test was performed in the same manner, and during that time, the tube voltage rise (V) and the color temperature change (K) were measured.
The results are as shown in Table 2. From the results, it can be seen that when the electrode length L1 is in the range of 3.5 mm to 10.8 mm (the range of the above formula 1), the tube voltage rise and the color temperature change during lighting are reduced. It can be seen that it can be suppressed.

Although specific measurement results are shown here only for the 300 W and 70 W metal vapor discharge lamps, a similar experiment was performed within the range of P = 70 W to 400 W. It was confirmed that the increase in the tube voltage and the change in the color temperature can be reduced.
In addition, when the composition ratio of the luminescent metal was changed, it was found that the increase in the tube voltage and the change in the color temperature during lighting could be reduced when the above equation 1 was satisfied, regardless of the composition ratio.

(Experiment 2)
In the metal vapor discharge lamp of the example, the electrode length was fixed at 17.8 mm, and the material of the electrode support was 100 W / m · K and 110 W in addition to the cermet having a heat conductivity of 70 W / m · K. / M · K, and those replaced with molybdenum (thermal conductivity 138 W / m · K), the color temperature change during life was measured. Table 3 shows the results.

From Table 3, it can be seen that when a material having a thermal conductivity of more than 100 W / m · K is used as the material of the electrode supports 23a and 23b, the color temperature change is large. This is because when the thermal conductivity of the electrode support is high, heat can easily escape from the electrode pins to the electrode support, so that the temperature near the gap G, particularly near the end faces of the seal portions 24a and 24b decreases, and sinking occurs. it is conceivable that.
(Experiment 3)
In the metal vapor discharge lamp of the example, when the length L2 of the thin tube portion was set to 10.0 mm, 11.6 mm, 13.1 mm, 15.0 mm, 17.6 mm, and 19.1 mm, a life test was performed for 3000 hours, and cracks were removed. The occurrence probability and color temperature change were measured.

The electrode length L1 was constant at 17.6 mm, and the length l2 of the flow of the sealing material into the narrow tube was also constant at 4.5 mm.
Table 4 shows the results. In the column of evaluation in Table 4, “◎” indicates “especially good” (Table 5 is based on this).

よ り From Table 4, it can be seen that cracks occur when the thin tube portion length L2 is 11.6 mm or less, but the crack occurrence probability becomes very small when the thin tube portion length L2 is 13.1 mm or more. This is because by setting the length L2 of the thin tube portion to 13.1 mm or more, the temperature of the electrode support and the seal portion in the thin tube portion does not become excessively high during lighting, so that the stress due to the reaction with the luminescent metal and the thermal expansion is suppressed. It is thought that it is.

On the other hand, from Table 4, it can be seen that the color temperature change is large when the capillary portion length L2 is 19.1 mm, but the color temperature change is very small when the capillary portion length L2 is 17.6 mm or less. This is presumably because the temperature of the inner wall of the thin tube portion is kept appropriately high by setting the length L2 of the thin tube portion to 17.6 mm or less, and the sinking is suppressed.
As described above, at P = 300 W, it can be seen that crack generation and color temperature change can be suppressed when the capillary portion length L2 is in the range of 13.1 mm to 17.6 mm (the range of the above formula 2).

Also, in the case of the metal vapor discharge lamp of P = 70 W, when the length L2 of the thin tube portion was changed to 4.0 mm, 5.0 mm, 5.8 mm, 8.0 mm, 10.0 mm, and 11.0 mm, similarly, 3000 hours. A life test was performed to measure the crack occurrence probability and color temperature change (K).
The results are as shown in Table 5. From the results, it can be seen that even when P = 70 W, cracking and color development were observed in the case where the capillary length L2 was in the range of 5.8 mm to 10.0 mm (the range of the above formula 2). It can be seen that the temperature change can be suppressed.

(Experiment 4)
In the metal vapor discharge lamp of the embodiment, the electrode length L1 is 17.6 mm, the thin tube portion length L2 is constant at 15.8 mm, and the glass frit pouring length l2 is 3.2 mm, 3.7 mm, 5.5 mm, and 6.5. A life test of 3000 hours was performed for the case of 0 mm, and the crack occurrence probability and color temperature change in the seal portion were measured. Table 6 shows the results.

From Table 6, it can be seen that when the pouring length l2 is 5.5 mm or less, the crack occurrence probability at the sealing portion is very small. This is presumably because in this range, the electrode support and the sealing portion in the narrow tube portion do not become excessively hot during lighting, so that stress due to reaction with the luminescent metal and thermal expansion is suppressed.
On the other hand, from Table 6, it can be seen that when the pouring length L2 is in the range of 3.7 mm or more, the change in color temperature is extremely small. This is presumably because in this range, the temperature of the end face of the sealing portion is kept at a moderately high temperature, so that sinking is suppressed.

The present invention can provide a metal vapor discharge lamp and an illuminating device that have a small change in color temperature even when lit continuously for a long time and that can maintain stable characteristics or that hardly extinguish.

It is a front view showing the composition of the metal vapor discharge lamp concerning an embodiment of the invention. FIG. 2 is a cross-sectional view illustrating an example of the configuration of the arc tube 1. FIG. 2 is a diagram illustrating a configuration of a lighting device according to the embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating an example of the configuration of the arc tube 1. FIGS. 5A and 5B are cross-sectional views illustrating the electrode length L1. FIG. 7 is a diagram for explaining the occurrence of extinction when a lamp is turned on.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Arc tube 3 Outer tube 10 Container 11 Main tube part 12a ・ 12b Thin tube part 20a ・ 20b Feeder 21a ・ 21b Electrode pin 22a ・ 22b Coil 23a ・ 23b Electrode support 24a ・ 24b Seal part 25a ・ 25b coil

Claims (17)

A light-transmitting ceramic light-emitting container in which a thin tube portion extending from both ends of the main tube portion is formed in a main tube portion in which a discharge space is formed by enclosing a luminescent metal therein,
In each of the thin tube portions, an electrode portion having one end facing the discharge space and a coil provided at the one end, and an electrode support connected to the other end of the electrode portion are inserted,
A metal vapor discharge lamp including an arc tube in which the electrode support is sealed by a sealing material in the thin tube portion,
The length of the electrode part is
A metal vapor discharge lamp characterized in that when the power of the lamp is P (W), it is not less than (0.041P + 0.5) mm and not more than (0.041P + 8.0) mm. The metal vapor discharge lamp according to claim 1, wherein the length of the electrode portion protruding from the thin tube portion toward the inside of the discharge space is not less than 3.0 mm and not more than 6.5 mm. The heat conductivity of the said electrode part is 130 (W / m * K) or more, and the heat conductivity of the said electrode support body is 100 (W / m * K) or less, The characterized by the above-mentioned. Metal vapor discharge lamp. The electrode unit includes at least one of tungsten and molybdenum,
The metal vapor discharge lamp according to claim 1, wherein the electrode support includes a cermet. The length of the thin tube portion is
The metal vapor discharge lamp according to claim 1, wherein when the electric power of the lamp is P (W), it is not less than (0.032P + 3.5) mm and not more than (0.032P + 8.0) mm. The sealing material,
It is poured into the thin tube portion from the end of the thin tube portion,
2. The metal vapor discharge lamp according to claim 1, wherein said pouring length is not less than 3.7 mm and not more than 5.5 mm.  The metal vapor discharge lamp according to claim 1, wherein the main tube portion and the thin tube portion of the luminous container are integrally formed. A light-transmitting ceramic light-emitting container in which a thin tube portion extending from both ends of the main tube portion is formed in a main tube portion in which a discharge space is formed by enclosing a luminescent metal therein,
In each of the thin tube portions, an electrode portion having one end facing the discharge space and a coil provided at the one end, and an electrode support connected to the other end of the electrode portion are inserted,
A metal vapor discharge lamp including an arc tube in which the electrode support is sealed by a sealing material in the thin tube portion,
The length of the electrode part is
When the power of the lamp is P (W), it is not less than (0.041P + 0.5) mm and not more than (0.041P + 8.0) mm;
A metal vapor discharge lamp having a lamp power of 70 W or more and 400 W or less. A light-transmitting ceramic light-emitting container in which a thin tube portion extending from both ends of the main tube portion is formed in a main tube portion in which a discharge space is formed by enclosing a luminescent metal therein,
In each of the thin tube portions, an electrode portion having one end facing the discharge space and a coil provided at the one end, and an electrode support connected to the other end of the electrode portion are inserted,
A metal vapor discharge lamp including an arc tube in which the electrode support is sealed by a sealing material in the thin tube portion,
The length of the thin tube portion is
A metal vapor discharge lamp characterized in that when the power of the lamp is P (W), it is not less than (0.032P + 3.5) mm and not more than (0.032P + 8.0) mm. A light-transmitting ceramic light-emitting container in which a thin tube portion extending from both ends of the main tube portion is formed in a main tube portion in which a discharge space is formed by enclosing a luminescent metal therein,
In each of the thin tube portions, an electrode portion having one end facing the discharge space and a coil provided at the one end, and an electrode support connected to the other end of the electrode portion are inserted,
A metal vapor discharge lamp including an arc tube in which the electrode support is sealed by a sealing material in the thin tube portion,
The length of the thin tube portion is
A metal vapor discharge lamp having a power of (0.032P + 3.5) mm or more and (0.032P + 6.0) mm or less, where P (W) represents the power of the lamp. The luminescent metal sealed in the main pipe part includes:
11. The metal vapor discharge lamp according to claim 10, comprising cerium. The sealing material,
It is poured into the thin tube portion from the end of the thin tube portion,
10. The metal vapor discharge lamp according to claim 9, wherein the pouring length is not less than 3.7 mm and not more than 5.5 mm. 10. The metal vapor discharge lamp according to claim 9, wherein the thickness of the thin tube portion is at least 1.15 times the thickness of the main tube portion. 10. The metal vapor discharge lamp according to claim 9, wherein the electrode support is made of cermet. The metal vapor discharge lamp according to claim 9, wherein the main tube portion and the thin tube portion of the luminous container are integrally formed. 10. The metal vapor discharge lamp according to claim 9, wherein the lamp power is 70 W or more and 360 W or less. A lighting device comprising: a device main body; a metal vapor discharge lamp according to any one of claims 1 to 16 provided in the device main body; and a lighting circuit device connected to the metal vapor discharge lamp.

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