WO2000016360A1

WO2000016360A1 - Anhydrous silver halide lamp

Info

Publication number: WO2000016360A1
Application number: PCT/JP1999/004969
Authority: WO
Inventors: Mamoru Takeda; Makoto Horiuchi; Kiyoshi Takahashi; Makoto Kai; Takeshi Saito; Hideaki Kiryu
Original assignee: Matsushita Electric Industrial Co.,Ltd
Priority date: 1998-09-16
Filing date: 1999-09-10
Publication date: 2000-03-23
Also published as: CN1277732A; EP1032010A4; TW429390B; KR20010024584A; EP1032010A1

Abstract

A light bulb (1) includes a pair of electrodes (3), and I/S is less than 20 A/mm2, where S is the cross section of the point of the electrodes (3) and I is the current that flows between electrodes (3) at rated power for the bulb. Since this condition prevents the light bulb (1) from blackening or the increase in the lamp voltage, which can occur due to the evaporation of the electrodes with time, a long service life can be achieved.

Description

Mercury-free metal halide lamp

TECHNICAL FIELD The present invention relates to a mercury-free metal halide lamp that is used as various light sources such as general lighting and a headlight of an automobile combined with a reflector, etc., and particularly contains no mercury. Things.

Background technology Conventionally, halogen lamps with tungsten filament have been the mainstream lamps used for automobile headlamps. Recently, however, metal halide lamps, which are high-pressure discharge lamps of metal halides, are being used for the purpose of improving efficiency and discriminating white lines. The above-mentioned conventional metal halide lamps are rarely used in arc tubes. Gas, metal halide (solid), and mercury are enclosed. In each of these enclosures, the noble gases are mainly used to make the lamp easy to start or to obtain a strong light output immediately after the start, and the metal halides to obtain the proper light output during stable operation. In addition, mercury is encapsulated to obtain the high enough inter-electrode voltage (lamp voltage) required for the lamp to operate properly.

Especially when the lamp is lit, a high inter-electrode voltage is obtained due to the inclusion of mercury. This allows the lamp to light with less lamp current. As a result, the heat load (Joule loss) of the electrode is reduced, and lighting can be performed for a long time of several thousand hours.

As a specific example of a conventional metal-halide lamp, for example, a lamp suitable for a vehicle headlight disclosed in Japanese Patent Application Laid-Open No. 59-111124 is known. . Hereinafter, a conventional metal halide lamp based on this publication is shown in FIG. 16 and described.

In FIG. 16, reference numeral 101 denotes an arc tube made of quartz, and numerals 102 at both ends of the arc tube 101 are sealing portions. 103 is a pair of electrodes made of tungsten, 104 is a molybdenum foil, and 105 is a lead wire made of the same molybdenum. The electrode 103 is electrically connected to one end of the molybdenum foil 104 sealed in the sealing portion 102, and is further connected to the other end of the molybdenum foil 104. Lead wire 105 is electrically connected.

The tip of the electrode 103 in the arc tube 101 is arranged so that the distance between the tips, that is, the distance between the electrodes is about 4.2 (mm). The inner volume of the arc tube 101 is about 0.03 (cc), and about 0.7 mg (about 1.1 mg / cc) of mercury is contained in the arc tube. 106, and a total of about 0.3 mg (about 12.2 mg / cc per unit arc tube volume) of sodium iodide, scandium iodide, and sodium iodide. And 0.7 MPa of Xe gas at room temperature (not shown).

The metal halide lamp as described above has a lamp voltage of about 70 to 80 V. For example, when the lamp is lit with a lamp power of about 35 W, the lamp current is about 0.4 to 0.5 A.

As described above, as a result of obtaining a high lamp voltage by mercury, Conventional metal halide lamps can be lit with low current, and thus this conventional metal halide lamp has a long life of about 200 hours. As mentioned above, the inclusion of mercury results in an increase in lamp voltage, thus providing us with a long lamp life of thousands of hours.

However, on the other hand, it has a drawback such as requiring a process of injecting liquid mercury during production, which tends to increase the production cost. In recent years, a metal halide lamp that does not contain mercury has been desired in consideration of the global environment.

However, when mercury is removed from the conventional metal halide lamp, the lamp voltage drops to about 25V. In this case, the lamp current during lighting is about 1.5 A, which is about three times that of the conventional metal halide lamp containing mercury. As a result, the heat load (Joule loss) of the electrode increases, and the evaporation of the electrode becomes active. Therefore, a mercury-free lamp with a configuration in which mercury is simply removed from a conventional metal halide lamp, the arc tube turns black in only a few tens of hours, and reaches its life in a very short time. There is a problem. In addition, since the distance between the electrodes increases due to the evaporation of the electrodes, the operating state of the lamp changes with the elapse of the lighting time, and an excessive load is applied to the drive circuit.

At the current technology level, efforts are being made to reduce the efficiency of fluorescent lamps, since complete removal of mercury would greatly reduce the efficiency, but mercury-free has not been achieved . Efforts have also been made to eliminate mercury from metal halide lamps, and electrodeless discharge lamps are being commercialized, but electrodeed discharge lamps are still under study. DISCLOSURE OF THE INVENTION In view of the above points, the present invention does not fill in mercury and prevents an increase in lamp voltage and blackening of the arc tube 1 due to evaporation of the electrodes and the like over the lighting time. The purpose is to provide a mercury-free metal halide lamp that can achieve a long lamp life without producing it.

In other words, it has been empirically determined that a low lamp current is necessary to extend the life. However, the same life cannot always be obtained with the same current, depending on the lamp specifications and lighting conditions. The present inventor has made various studies and found that the life of the lamp is not simply the magnitude of the current, but the current density is important. It has been reached.

Therefore, the invention of claim 1 is:

A mercury-free metal halide lamp that has a pair of discharge electrodes in the arc tube and contains at least a rare gas and a metal halide. S (mm ²⁾ the cross-sectional area of the Kinora lamp current and is lit at the rated power can and was I (a), and this I / S is ² 0 (a / mm 2) or less It is characterized by

The invention of claim 2 is

A mercury-free metal halide lamp according to claim 1, wherein

It is characterized in that the above I / S is 15 (A / mm ² ) or less.

Also, the invention of claim 3 is:

A mercury-free metal halide lamp according to claim 1, wherein 00/163 P

It is characterized in that the temperature of the tip of the discharge electrode at the time of lighting at the rated power is 320 K or less. As a result, the lamp voltage increases significantly due to the synergistic effect of an increase in the vapor pressure of the metal halide and an increase in the distance between the electrodes due to evaporation of the electrodes with the passage of the lighting time, etc. Since blackening is suppressed, a long lamp life can be obtained. Also, the invention of claim 4 is:

A mercury-free metal halide lamp according to claim 3, wherein

The temperature characteristic at the tip of the discharge electrode when lit at the rated power is 250 K or more. This makes it easy to start a stable discharge. The invention of claim 5 is:

The mercury-free metal halide lamp according to claim 1 or claim 3, wherein at least one of a halide of scandium and a halide of sodium is contained in the arc tube. It is characterized by including one of them.

The invention of claim 6 is

A mercury-free metal halide lamp according to claim 5, wherein

It is characterized in that the arc tube contains at least one of halide of indium and halogen of indium.

The invention of claim 7 is: 4. The mercury-free metal halide lamp according to claim 1 or 3, characterized in that the arc tube contains at least a halide of +3 valent indium. ing.

The invention of claim 8 is:

A mercury-free metal halide lamp according to claim 7, wherein

Further, it is characterized in that the arc tube contains a halide of thallium.

The invention of claim 9 is

A mercury-free metal halide lamp according to claim 7, wherein

Further, the invention is characterized in that the arc tube contains at least one of a halide of scandium and a halide of sodium.

The invention of claim 10 is

A mercury-free metal halide lamp according to claim 8, wherein

In addition, the invention of claim 11

A mercury-free metal halide lamp according to claim 7, wherein

The above-mentioned halide of trivalent indium is characterized in that it is at least one of iodide and bromide. As a result, a high lamp voltage can be obtained, so that the current density can be easily suppressed to be small, and therefore, the lamp life can be surely improved. Also, the invention of claim 12 is

The mercury-free metal halide lamp according to claim 1 or 3, further comprising an outer tube for holding the arc tube, wherein the outer tube is provided with an infrared reflection layer. I have. As a result, the heat retention of the lamp is increased, so that the vapor pressure of the metal halide is easily increased, so that the lamp voltage can be increased. Therefore, the lamp life can be easily reduced, and therefore, the lamp life can be reliably improved.

FIG. 1 is a cross-sectional view showing a mercury-free metal halide lamp according to the first embodiment.

FIG. 2 is a graph showing the relationship between the current density of the mercury-free metal halide lamp of Embodiment 1 and the ramp voltage increase rate after lighting for 100 hours.

FIG. 3 is a graph showing the relationship between the lighting time, the rate of change of the distance between the electrodes, and the rate of change of the lamp voltage in the mercury-free metal halide lamp of the first embodiment.

FIG. 4 is a graph showing the correlation between the rate of change of the electrode distance and the rate of change of the lamp voltage in the mercury-free metal halide lamp of the first embodiment.

FIG. 5 is a graph showing the relationship between the current density and the electrode tip temperature in the mercury-free metal halide lamp of the first embodiment.

FIG. 6 shows the mercury-free metal halide lamps of Embodiments 3 and 4. Sectional view

Figure 7 is a graph showing the relationship between the mercury-free main Taruhara Lee de ramp of + 3-valent fin di © charging amount of beam of Yo U compound I n I ₃ and lamp voltage of the third embodiment

FIG. 8 is a graph showing the relationship between the sealing pressure of Xe and the total luminous flux of the mercury-free metal halide lamp of the third embodiment.

Figure 9 shows the amount of +3 valent indium iodide I n I ₃ and the total luminous flux when the mercury-free metal halide lamp of the third embodiment is turned on with 45 W power. Graph showing the relationship

Fig. 10 shows the amount of +3 valent indium iodide I n I;, when the mercury-free metal halide lamp of the third embodiment is turned on with 35 W power. Graph showing the relationship between

FIG. 11 is a graph showing the relationship between the amount of thallium iodide and the lamp voltage of the mercury-free metal halide lamp of the fourth embodiment.

FIG. 12 is a graph showing the relationship between the amount of the iodide and the total luminous flux of the mercury-free metal halide lamp of the fourth embodiment.

FIG. 13 is a graph showing the relationship between the filling pressure of Xe and the lamp voltage of the mercury-free metal halide lamp of the fourth embodiment.

FIG. 14 is a graph showing the relationship between the sealing pressure of Xe and the total luminous flux of the mercury-free metal halide lamp of the fourth embodiment.

FIG. 15 is a cross-sectional view showing a mercury-free metal halide lamp with the infrared reflecting film of Embodiment 5 coated thereon.

Fig. 16 is a cross-sectional view showing a conventional metal halide lamp.

BEST MODE FOR CARRYING OUT THE INVENTION (Summary of each embodiment)

First, an outline of each of the following embodiments will be described.

The basic principle of the present invention is to extend the lamp life by reducing the current density and the temperature of the electrode tip. In the following first embodiment, a description will be given of a current density capable of extending the life of a lamp and a temperature of an electrode tip.

Here, as a first method for reducing the current density, there is a method of increasing the thickness of the electrode rod.

As a second method of reducing the current density, there is a method of increasing the lamp voltage. Methods of increasing the lamp voltage include a method of setting a large distance between the electrodes and a method of increasing the vapor pressure of the filling material (luminescent substance) to be filled in the arc tube. Methods for increasing the vapor pressure of the above-mentioned inclusions also include the use of additional high-vapor-pressure enclosures (e.g., halides of scandium and halogenates of lithium). There are a method of using the method and a method of increasing the temperature of the arc tube.

Therefore, in a second embodiment, a method for increasing the thickness of the electrode rod and a method for setting the distance between the electrodes to increase the lamp voltage will be described.

Further, in Embodiments 3 and 4, a description will be given of an enclosure capable of increasing the vapor pressure in order to increase the lamp voltage.

In the fifth embodiment, a method for increasing the lamp wall temperature of the arc tube in order to increase the lamp voltage will be described. (Embodiment 1)

Hereinafter, Embodiment 1 of the present invention will be described. FIG. FIG. 1 is a sectional view showing a mercury-free metal halide lamp according to the first embodiment of the present invention. <In FIG. 1, reference numeral 1 denotes an arc tube made of quartz, and reference numerals 2 at both ends of the arc tube 1 denote sealing portions. 3 is a pair of electrodes made of tungsten, 4 is a molybdenum foil, and 5 is a lead wire also made of a molybdenum material. The electrode 3 is electrically connected to one end of the molybdenum foil 4 sealed in the sealing portion 2, and a lead wire 5 is electrically connected to the other end of the molybdenum foil 4. Have been. The arc tube 1 is filled with a later-described halide 7 and a rare gas (not shown). In the figure, the area of the tip surface of the electrode 3 (the cross-sectional area of the tip portion when the tip portion is spherical, etc .; hereinafter, collectively referred to as the electrode cross-sectional area) is denoted by S and the electrode.

The distance between 3.3 is represented by L, the voltage between the electrodes 3 and 3 (ramp voltage) is represented by V, the current flowing between the electrodes 3.3 and 3 (lamp current) is represented by I, and the discharge arc is represented by A. .

In Structure Do you Yo above, for example, the inter-electrode distance L 3. 5~ 4. 3 mm , the electrode cross-sectional area S 1. 1 6 9 ~ 1 . 3 tip of 2 7 mm ² (electrode 3 is a plane Various lamps with the diameter ø of 0.25 to 0.46 mm) and encapsulation of the following compounds (Table 1) as the nitrogenated compounds 7 were prepared.

With a lamp power of 45 W, the lamp was lit continuously for 100 hours with a stable discharge arc A, and the lamp voltage was measured.

table 1

At this time, the lamp voltage VI after lighting for 100 hours with respect to the lamp voltage VQ immediately after starting lighting. Q rise rate Rv, ie

Rv = (V _{1 0 0} -V ₀ ) / V ₀ (Equation 1)

I asked. Figure 2 shows the relationship between the ramp voltage rise rate and the current density (lamp current 1 / electrode cross-sectional area S). In the figure, the measurement error of about 3% is represented by an error bar. As can be seen from the figure, the ramp voltage increase rate increases extremely when the current density exceeds about 2 OA / mm ² . In this case (for example, in the case of 3 OA / mm ² ), part of the electrode 3 evaporates, and the remaining part is deformed into a fold. The evaporation causes blackening of the arc tube 1, and the luminous flux maintenance rate is greatly reduced. Also, when the current density is large, the arc tends to be unstable. On the other hand, if the current density is about 2 OA / mm ² or less, the ramp voltage rise rate R v becomes about 0.1 or less, which satisfies the condition generally regarded as a non-defective product limit. If the current density is about 1 OA / mm ² or less, the ramp voltage rise rate can be significantly reduced. In these cases (for example, in the case of 8 A / mm ² ), the electrode 3 was hardly deformed, and the luminous flux was not reduced by blackening.

The reason why the ramp voltage rise rate sharply increases as the current density rises as described above is explained below.

The ramp voltage Via is generally

V laoc N ^{^1/2} XL (Equation 2)

It is represented by

Here, N is the particle density in the lamp, and L is the distance between the electrodes.

Therefore, for the above mercury-free lamp and a conventional organic mercury lamp, a mercury-free run-flop about ² 5 A / mm 2, chromatic mercury lamp is about 8 A / mm ² The lamp was lit at the current density, the lamp voltage V1a and the distance L between the electrodes were measured over the lighting time, and the rate of change from the value immediately after the start of lighting was determined. The result is shown in Fig. 3. That is, in the case of a mercury-containing lamp, the rate of change of the lamp voltage V1a and the rate of change of the distance L between the electrodes increase only slightly with the elapse of the lighting time. However, in the case of mercury-free lamps, both increase significantly. Looking at the relationship between the rate of change of the lamp voltage V ia and the rate of change of the distance L between the electrodes, as shown in Fig. 4, in the case of a mercury-containing lamp, the slope is about 0.9, That is, the rate of change of the lamp voltage V 1 a and the rate of change of the inter-electrode distance L increase almost to the same extent. On the other hand, in the mercury-free lamp, the gradient is about 2, and the rate of change of the lamp voltage V1a is larger than that of the distance L between the electrodes.

As described above, in the mercury lamp, the rate of change of the distance L between the lamp electrodes increases only slightly because the electrode 3 hardly evaporates, and the change in the lamp voltage V 1 a The reason why the rate of change and the rate of change of the distance L between the electrodes are almost the same is that almost all changes in N in the above (Equation 2) occur because the enclosed mercury is all mercury vapor. (That is, only L of the above (Equation 2) mainly changes). On the other hand, in the mercury-free lamp, the rate of change of the distance L between the lamp electrodes increases significantly because the electrode 3 evaporates vigorously, and the rate of change of the lamp voltage VIa increases. The reason why the rate of change of the interelectrode distance L increases more greatly is that the vapor pressure of the metal halide increases as the interelectrode distance L increases as the electrode 3 evaporates. (That is, L and N in the above (Equation 2) both change.) (That is, when the distance L between the electrodes increases, the tube wall temperature of the arc tube 1 increases, It is considered that the vapor pressure of the metal halide has increased. When the spectral spectrum was observed, it was observed that the metallic spectrum was changing.

Therefore, as described above, as the current density increases, the lamp voltage increases sharply, and the life of the arc tube 1 decreases significantly due to blackening, while the current density decreases to 2 OA / mm ² or less. More preferably, by setting it to 1 OA / mm ² , the ramp voltage increase rate can be greatly suppressed, and a long lamp life can be obtained.

Next, an example in which the tip temperature of the electrode is used as an index corresponding to the current density will be described. In other words, the higher the temperature of the electrode tip, the more the evaporation of the electrode is promoted. By keeping this temperature low, the ramp voltage rise rate is reduced and the lamp life is prolonged. Can be. Here, in general, it is very difficult to directly measure the electrode temperature of a metal-halide lamp. However, by using the method disclosed by the present inventors in Japanese Patent Application Laid-Open No. Hei 4-99, noise due to the spectrum unique to the metal can be removed, and the accuracy is extremely high. Measurement with high sensitivity can be simplified.

Specifically, first, the luminances LI and L2 of light of two wavelengths λ ΐ and λ 2 (for example, 1 = 613 nm, A 2 = 807 nm) are measured, and the luminance ratio R is calculated. Ask.

R = L 1 (A l) / L 2 (λ 2) (3)

Next, the electrode temperature T is calculated using the luminance ratio R.

T = C (1 / λ 1-1 / λ 2) / In (R x λ ¹⁵ / λ 2

⁵ ) (4)

Here, C = 0.001 4 3 8 8 [m'K].

Figure 5 shows the relationship between the electrode tip temperature obtained in this way and the current density. As can be seen from the figure, it corresponds to a current density of 2 OA / mm ² The temperature at the tip of the electrode used is 320 K, and by keeping the temperature at or below this temperature, the lamp life can be extended. In order to start a stable discharge, it is preferable that the temperature be 250 K or more.

(Embodiment 2)

A specific method for reducing the current density will be described.

First, the current density can be reduced by making the electrode rod thicker. Specifically, for example, when the rated power is 35 W and the lamp voltage is 70 V, the lamp current is 0.5 A, so the electrode cross-sectional area is 0.025 mm ² (circular shape). In the case of a cross section, the current density can be suppressed to 2 OA / mm ² or less by making the diameter approximately ◦ .18 mm) or more. However, if the thickness is too large, the withstand pressure of the arc tube decreases in inverse proportion to the electrode rod diameter. That is, the stress generated in the vicinity of the gap between the arc tube and the electrode rod becomes large. Therefore, in the case where the inside of the arc tube is at a high pressure (for example, 100 atm at the time of lighting), as in a lamp for an automobile, for example, the electrode rod may be damaged due to its mechanical strength. It is preferable to make it smaller. In order to shorten the rise time of the light beam at the start of lighting, it is preferable to reduce the diameter of the electrode rod.

Also, the current density can be reduced by increasing the distance between the electrodes and increasing the lamp voltage. For example, increasing the pump voltage from about 4 mm to about 5 mm as in a conventional normal lamp can increase the pump voltage by about 25%. Therefore, it is easy to reduce the current density. However, when used together with a reflector such as a headlight of an automobile, the size of the light source is limited. It is preferable not to make the distance between the electrodes too large.

(Embodiment 3)

The following describes an enclosure that can increase the lamp voltage by increasing the vapor pressure.

Hereinafter, Embodiment 3 of the present invention will be described. FIG. 6 is a cross-sectional view showing a mercury-free metal halide lamp according to Embodiment 3 of the present invention. In FIG. 6, reference numeral 1 denotes an arc tube made of quartz, and 2 at both ends of the arc tube 1. It is a stop. 3 is a pair of electrodes made of tungsten, 4 is a molybdenum foil, and 5 is a lead wire made of the same molybdenum. The electrode 3 is electrically connected to one end of the molybdenum foil 4 sealed in the sealing portion 2, and a lead wire 5 is electrically connected to the other end of the molybdenum foil 4. Have been.

The tip of the electrode 3 in the arc tube 1 is arranged so that the distance between the tips, that is, the distance between the electrodes is about 4.2 (mm).

The inner volume of the arc tube 1 is about 0.025 (cc), and about 0.2 mg of + trivalent indium iodide Inl ₃ (unit in the arc tube) About 8.0 mg / cc per volume) and about 0.19 mg of scandium iodide (about 8, O mg / cc per unit arc tube volume) and about 0.16 mg Of sodium iodide (about 6.4 mg / cc per unit arc tube volume), and about 0.7 MPa at room temperature, not shown in the figure. Xenon gas is sealed.

Compared to the structure of the conventional metal halide lamp, the feature of the large structure of the metal halide lamp according to the present embodiment is that it does not contain mercury, and that the indium that is further enclosed is indium. Is a trivalent indium It is the iodide I n I ₃ of the jam.

+ The surprising thing about the mercury-free metal halide lamp of this embodiment, which contains the trivalent zinc iodide I n I _3, is that it is very mercury-free. The lighting operation is performed at a very high lamp voltage. For example, when the lamp is operated with a lamp power of 45 W, the lamp voltage of the lamp of this embodiment is about 55 V, and when the lamp is operated with a lamp power of 35 W, The lamp voltage is about 50 V. The lamp shown in this embodiment in which +3 valent indium iodide Inl ₃ is removed from the lamp described in this embodiment operates with a lamp power of 25 W to 50 W. Even so, a lamp voltage of only about 27 V can be obtained. In addition, in the mercury-free metal halide lamp of the present embodiment, + trivalent zinc iodide I n I ₃ and + monovalent zinc iodide I Even in the case where the lamp is replaced with nl, for example, the lamp voltage during the lighting operation with a lamp power of 35 W is about 45 V, and the lamp voltage of the lamp of the present embodiment is Not reachable.

For this and the result high run-up voltage to encapsulate I n I ₃ to the good cormorants is obtained, lamp of this embodiment, Ri cotton to more than several hundred hours, it also blackening of the arc tube It can be turned on with virtually no change.

In addition, since a high lamp voltage can be obtained as described above, the current density can be easily reduced to 2 OA / mm ² or less, and the lamp life can be reliably improved. Can be. Specifically, for example, when the diameter of the electrode 3 is 0.25 mm and the lamp power is 35 W, the I n I _{3 and the} like are set so that the lamp voltage becomes about 35.7 y or more. May be set. In the above example, about 0.2 mg of + trivalent indium iodide In I 3 (about 8.0 mg / cc per unit arc tube volume) is enclosed. As an example, the mercury-free metal halide lamp was used as an example, as shown in Fig. 7, with a configuration in which the encapsulation amount of the iodide I n I ₃ of the +3 valent indium was increased. By doing so, it was found that a higher lamp voltage was obtained, and therefore, the working life was also advantageously improved. Figure 7 is the mercury-free main Taruharai Dora pump of this embodiment, + trivalent increase the amount of enclosed Yo U compound I n I ₃ Lee indium, 3 5 W or is 4 5 W of run- when is lit operating at up power is a graph showing the relationship between the amount of enclosed ® © product I nl ₃ of the lamp voltage and + 3-valent I Njiumu. The more + trivalent enclosed amount of I Nji ©-time of Yo c monster I n I ₃ is larger, run-up voltage is high Ku becomes Ri good.

Incidentally, increasing effect of the lamp voltage due增pressurized encapsulation of Yo U compound I nl ₃ of + 3-valent Lee Nji um This, lamp power and distance between the electrodes, the internal volume of the arc tube 1, X e Gas filling pressure, amount of scandium iodide / aluminium iodide, or other halogens that are enclosed with the +3 valent indium iodide I n I ₃ Obtained irrespective of other components such as the type and amount of the compound.

In addition, an example was shown in which xenon gas of about 0.7 MPa 70 kPa was sealed at room temperature, but as shown in Fig. 8, xenon gas at a higher pressure was sealed. Then, the total luminous flux increases almost linearly. Figure 8 shows the relationship between the xenon gas charging pressure (converted to room temperature) and the total luminous flux of the mercury-free metal halide lamp of this embodiment, which was turned on with a lamp power of 45 W. This is a graph showing the amount of encapsulated indium iodide Inl ₃ of the indium over a night. Moreover on the surprising rather should this, in the +3 valent I Nji © beam Yo U compound I n I ₃ mercury-free main Taruharai Dora pump in the form status of this embodiment of the encapsulated structure and the xenon Roh Ngasu sealed entrance The hot spot of the arc tube 1 with increasing pressure (highest temperature part: When the arc tube is held horizontally and lit, the temperature rise in the upper outer surface of the arc tube 1 is so small that it can be neglected. Therefore, there is a possibility that the arc tube 1 may expand due to an increase in the xenon gas filling pressure. Low.

As described above, the mercury-free metal halide lamp according to the present embodiment in which at least xenon gas and the iodide I n I _{3 of the} +3 valence alloy are sealed in the arc tube 1 is a xenon gas. Increasing the gas filling pressure increases the total luminous flux almost without increasing the temperature of the hot spot, and increases the lamp voltage by increasing the iodide I n I ₃ of the +3 valence alloy. Has the characteristic of increasing. These effects depend on the lamp power, the distance between the electrodes, the inner volume of the arc tube 1, the amount of scandium iodide and the amount of sodium iodide, or + 3valent ions. Obtained irrespective of other components such as the type and amount of other halides encapsulated with the iodide I n I _{3 of} sodium.

Here, the sealing pressure of xenon gas will be described. In order to obtain a lamp suitable for practical use, in the mercury-free metal halide lamp described in the present embodiment, the upper limit of the sealing pressure of xenon gas is about 2.5 MPa (converted to room temperature). It is preferable to set to. When sealed at a pressure of about 2.5 MPa or more, the mercury-free metal halide lamp of the present embodiment has a configuration in which the arc tube 1 is connected from the vicinity of the connection between the electrode 3 and the molybdenum foil 4 during the lighting operation. This is because the possibility of leakage of the internal airtightness increases, which is not preferable. The upper limit of the more preferable xenon gas filling pressure is about 2.0MPa. On the other hand, the lower limit is about 5 to 20 KPa, which makes it easy to start the lamp. However, when the mercury-free metal halide lamp of the present invention is used as a light source for a vehicle headlight that requires a short rise of light, the lower limit is about 0.1 IMPa. Is more preferred. Then, the charging amount and the light flux of Yo U compound I n I ₃ +3 valent Lee down di ium explain about. In the mercury-free main Taruhara Lee de lamp of the present invention, +3 valent amount of enclosed Lee down di ium Yo U compound I n I ₃ is better to be larger structure Ri good, high lamp voltage Ri yo is However, when the mercury-free lamp described in the present embodiment is used for a light source for a vehicle headlight, + trivalent indium iodide I enclosed amount of nl ₃ is about 9 0 Ri per unit arc tube volume. O mg / cc or is less than configured to this and is arbitrarily favored in the following points.

In other words, a halogen lamp, which is currently widely used for automobile headlights, can obtain a total luminous flux of about 110 (lm) at a power consumption of 55 W. Ramp pairs to the invention which is about 9 Ri units arc tube volume equivalent other inclusion of Yo U compound I n I ₃ of Let's Ni + trivalent I Nji © beam shown in FIG. 9 0. O If the configuration is less than mg / cc, only 45 W of power will provide more luminous flux than conventional halogen bulbs, which is more economical. Figure 9 shows the total luminous flux and the amount of +3 valent indium iodide I n I _{3 in} the mercury-free metal halide lamp of this embodiment, which was turned on with a lamp power of 45 W. Is a graph showing the xenon gas sealing pressure (converted to room temperature) over time. From FIG. 9, it can be seen that, when the xenon gas charging pressure is the maximum allowable pressure of 2.5 MPa (converted to room temperature) of the mercury-free lamp of this embodiment, + trivalent indium iodine is used. compound I nl to about 9 0 Ri filling amount is per arc tube volume of _3. about 1 1 0 0 (lm) or more filling pressure of the light beam is obtained (xenon Ngasu also low Ri by less at O mg / cc In the case of a configuration, for example, in the case of a more preferable xenon gas φ maximum pressure of 2.0 MPa (converted to room temperature), which is allowable in the configuration of the mercury-free lamp of the present embodiment, the present invention is not applicable. In order to obtain a luminous flux of about 110 (1 m) or more at the mercury metal halide lamp, the trivalent indium iodide (I n I ₃ ) The upper limit of the filling amount is about 70 mg / cc per arc tube volume. That is, if the xenon gas filling pressure is 2.0MPa, about 70 mg / cc per arc tube volume With a filling amount of less than / cc, a luminous flux of about 110 (lm) or more can be obtained, which is more economical than a halogen bulb.

Similarly, FIG. 1 0 In 3 5 W of lamp mercury-free main Taruharai de lamp of this embodiment is lit at a power, the total flux and + 3-valent Lee Nji © untwisted U compound I n I ₃ The graph shows the relationship between the amount of filled gas and the filled pressure (converted to room temperature) of xenon gas over time. + With less than about 50 mg / cc per unit volume of the arc tube, the amount of trivalent zinc iodide I n I ₃ can be reduced to only 35 W. Power is more economical than conventional halogen bulbs, providing more luminous flux. Xenon Bruno filling pressure of Ngasu is 2. 5 MP a case of (room temperature-converted value) + trivalent inclusion of Yo Wihi product I nl ₃ Lee emissions indium, about 5 0 Ri per arc tube internal volume. A light flux of about 110 (lm) or more can be obtained at O mg / cc or less. If the filling pressure of the xenon Roh Ngasu is low, for example when the 2 OMP a (room temperature-converted value), the upper limit of the preferred arbitrariness + trivalent Lee enclosed amount of Yo U compound I n I ₃ of indium is per arc tube volume Approximately 40.0 mg / cc, a luminous flux of about 110 (lm) or more can be obtained with a smaller filling amount, and it is more economical than a halogen bulb.

As described above, in the configuration of the mercury-free metal halide lamp of the present invention, xenon gas of an appropriate pressure is sealed up to 2.5 MPa and the volume of the arc tube is reduced. Ri about 9 0. if O mg / cc and an upper limit and to encapsulating Lee down di ium Yo U compound I nl ₃ +3 valent appropriate amount constituting approximately 2 5 W or more lamp power When the lamp is turned on, the airtightness in the arc tube 1 is not broken, and a high lamp voltage is applied. As a result, it is a mercury-free metal halide lamp that has a long service life and generates more luminous flux than a halogen bulb, and is most suitable as a so-called automotive headlight light source.

Regarding the lamp power, the mercury-free lamp of the present embodiment can obtain more luminous flux as the lamp is turned on with a larger lamp power. However, practically, the upper limit of the power consumption of the mercury-free lamp of the present embodiment is approximately 55 W in the usage range of a vehicle headlight. Lighting beyond the power consumption of conventional halogen bulbs is uneconomical and not preferred.

Next, the light color of the mercury-free metal halide lamp of the present embodiment will be described.

In the mercury-free metal halide lamp of the present embodiment, xenon gas of an appropriate pressure is sealed up to 2.5 MPa, and about 90 mg / cc per volume of the arc tube is filled. As an upper limit, an appropriate amount of +3 valent indium iodide I n I ₃ is enclosed, and the lamp is lit with power between approximately 25 W and 55 W. The light color of the mercury-free lamp of this embodiment is within the chromaticity range of the white light source specified by the HID light source for automobile headlights (JEL2115) of the Japan Light Bulb Manufacturers Association. It was confirmed. In other words, by setting the type and amount of the enclosure containing +3 valent indium iodide I n I ₃ and the rated power as described above, for example, the emission of the lamp can be reduced. The chromaticity point is in the CIE 1 9 3 1 X y chromaticity diagram

X≥ 0.31 0 and

≤ 0.5 .5 and

y≤0.1.50 + 0.6.640 and

y <0 .4 4 0 and y≥ 0 .0 5 0 + 0.75 0 and

y≥0.32 (except x≥0.44)

In the chromaticity range of Therefore, the mercury of the present embodiment is limited by the above-described limited range of the sealing pressure of xenon gas, the amount of iodide I n I ₃ of +3 valence indium, and the lamp power, as described above. The metal halide lamp is fully usable as a vehicle headlight light source.

(Embodiment 4)

Hereinafter, Embodiment 4 of the present invention will be described. The structural configuration of this lamp is the same as that of the lamp of the third embodiment shown in FIG. 6 described above, except that the encapsulated nitrogen compound 7 and the enclosed xenon gas are not included. The difference is that the pressure is about 1.4 MPa at room temperature. That is, the halogenated compound 7 contains about ◦.lmg of + trivalent indium iodide In I I 3 (about 4.0 mg / cc per unit arc tube volume) and about 0.1 mg. lmg of thallium iodide T 1 I (approximately 4.0 mg / cc per unit arc tube volume) and approximately 0.19 mg of scandium iodide (approximate unit volume per arc tube) 8. O mg / cc) and about 0.16 mg of sodium iodide (about 6.4 mg / cc per unit arc tube volume).

Compared to the configuration of the conventional metal halide lamp, the feature of the large configuration of the metal halide lamp of the present embodiment is that it does not contain mercury as in Embodiment 3 and is sealed. In addition to the fact that the iodide of the enzyme is +3 valent indium iodide I n I ₃ , it also contains thallium iodide. Is a point.

What is surprising about the mercury-free metal halide lamp of this embodiment is that It operates at a very high lamp voltage, even though it does not contain silver. FIG. 11 shows the change in lamp voltage when the lamp is turned on at 35 W as in the third embodiment with the amount of thallium iodide (T1I) changed. The addition of thallium iodide (T1I) dramatically increases the lamp voltage, and the higher the amount added, the higher the ramp voltage. For example, the lamp voltage is about 70 V when the lighting operation is performed with a lamp power of 35 W. In order to obtain such a high lamp voltage, the lamp of the present embodiment can cause a substantial change over several hundred hours without blackening of the arc tube. It can be lit immediately.

In addition, since a high lamp voltage can be obtained as described above, it is easy to reduce the current density to 2 OA / mm ² or less as in the case of the above-described third embodiment. As a result, the lamp life can be reliably improved.

Even more surprisingly, when the lamp of the present embodiment is lit at 35 W, for example, a very large light flux of 3250 (1 m) can be obtained. FIG. 12 shows a change in the luminous flux when the lamp is lit at 35 W as in the third embodiment by changing the amount of thallium iodide (TII) sealed in the lamp. As shown in the figure, a large luminous flux can be obtained by adding thallium iodide T1I, and the amount of thallium iodide encapsulated must be increased. Further, the luminous flux increases.

The increase in lamp voltage and the increase in luminous flux due to the increase in the amount of filled thallium iodide (T1I) are due to lamp power, distance between electrodes, internal volume of arc tube 1, Xe gas Other factors, such as the fill pressure, the amount of scandium iodide, the amount of sodium iodide in the sodium, or the type and amount of other halides that are enclosed with the iodide. Obtained irrespective of the components. Further, it was found that when the pressure of the xenon (Xe) gas to be enclosed was increased, the lamp voltage and the luminous flux were further increased. Figures 13 and 14 show the relationship between the sealed pressure of Xe and the lamp voltage or luminous flux when lit at 35 W. As shown in these figures, the lamp voltage and the luminous flux increase as the Xe pressure increases. However, as described in the third embodiment, the filling pressure of xenon gas is not more than 2.5 MPa, more preferably not more than 2. OMPa, and not less than about 5 to 20 KPa. More preferably, it is more than 0 .IMPa, which is desirable in terms of maintaining airtightness and easy starting. As described above, at least xenon gas and +3 valence As described above, the mercury-free metal halide lamp of this embodiment in which the indium iodide InI3 of indium and titanium iodide are sealed in the arc tube 1 has the above-described properties. The lamp voltage and the total luminous flux increase when the evening beam is increased, and the lamp voltage and the total luminous flux also increase when the xenon gas filling pressure is increased. This effect also depends on the lamp power, the distance between the electrodes, the inner volume of the arc tube 1, the amount of scandium iodide, the amount of sodium iodide, or the amount of iodide. Obtained irrespective of other components such as the type and amount of other halides enclosed with the evening room.

Therefore, in the configuration of the mercury-free metal halide lamp of the present embodiment, xenon gas of an appropriate pressure is sealed up to 2.5 MPa, and + trivalent indium iodide is used. A configuration in which a certain indium iodide and thorium iodide are encapsulated provides a high lamp voltage, has a long life, and generates more luminous flux than a halogen bulb. It is a mercury-free metal halide lamp that is optimal as a so-called light source for vehicle headlights. Regarding the lamp power, as in the third embodiment, the more the lamp is turned on with a large lamp power, the more luminous flux is obtained. However, practically, the upper limit of the power consumption of the mercury-free lamp of the present embodiment is approximately 55 W in the usage range of the vehicle headlight. Lighting beyond the power consumption of conventional halogen bulbs is uneconomical and not preferred.

As for the light color, as in the third embodiment, the mercury-free metal halide lamp of the present embodiment is filled with xenon gas at an appropriate pressure up to 2.5 MPa. and construction encapsulating arc tube volume per Ri about 9 0. ® © product I n I ₃ and Yo Ukata re um of O mg / cc limit and to appropriate amount of + 3-valent Lee indium However, when the lamp is illuminated with an electric power of about 25 W to 55 W, the light color of the mercury-free lamp of the present embodiment is an automobile headlight conforming to the Japan Light Bulb Manufacturers Association standard. It was confirmed that it was within the chromaticity range of the white light source specified by the HID light source (JEL215) for the camera. That is, the + trivalent Lee indium type and amount of Yo U compound I n fill containing I _3, and Ri by the rated power and this is set to cormorants good example of the above, the run-up of the emitted light The chromaticity point is in the CIE 1 9 3 1 X y chromaticity diagram

X≥ 0.31 0 and

≤ 0. 5 0 0 and

y≤0.1.50 + 0.6.640 and

y≤ 0. 4 4 0 and

y≥ 0 .0 5 0 + 0.75 0 x and

y≥0.32 (except x≥0.44)

In the chromaticity range of Therefore, the charging pressure of xenon gas in a limited range as described above and the The mercury-free metal halide lamp according to the present embodiment can be completely used as a light source for a vehicle headlamp in terms of the amount of iodide I n I ₃ charged and the lamp power. In the fourth embodiment, a mercury-free lamp in which thallium iodide is encapsulated has been described as an example. However, thallium bromide (T1Br) may be used. It may be Li (T 1 C 1). Further, the T1 metal and the halogen may be separately sealed.

Further, in the third, fourth respective embodiments have been described mercury-free run-flop encapsulating Yo U compound I n I ₃ +3 valent Lee indium example, +3 valent Lee emissions Jiumu Yo U compound I n I ₃ is + trivalent Lee may be a Nji um bromide I n B r ₃ of + 3-valent Lee down Ji beam Yo U compound I nl ₃ and +3 Lee indium it may be a bromide I n B r _3.

Further, +3 Lee down di ium Yo U compound I nl ₃ is + monovalent Lee emissions Jiu divided into arm Yo U compound I n I and iodine I ₂ is enclosed in the arc tube 1 It doesn't matter. + If trivalent Lee emissions Woo you encapsulate bromide I n B r ₃ of arm likewise, the arc tube is divided into + 1 valent and bromide I n B r Lee emissions di ium bromine B r ₂ It may be sealed in 1. + Monovalent fin Yo U compound I nl bromine B r ₂ of Jiumu enclosed in the arc tube 1, + trivalent Lee Njiu beam Yo U compound I nl ₃ and + 3-valent Lee down di ium Both of the bromide I nBr of this type may be generated in the arc tube 1. In addition, it is also possible to encapsulate InI (or InBr) and a halide such as AgI (or AgBr), which is easily separated at high temperatures, such as AgI (or AgBr). I n X _y (X is iodine or bromine, y> 1) may be vMedia.Creating contained in enclosure in manner.

In addition, Kise Roh Ngasu and + trivalent Lee down indium Yo c monster _I n I. Ί of In addition, a lamp composed of scandium iodide and sodium iodide was described as an example, but scandium iodide and sodium iodide were It may be composed of other metal halides. For example, the scandium iodide may be scandium bromide, and the sodium iodide may be sodium bromide. Furthermore, scandium and sodium may be other metals, such as, for example, thallium iodide or bromide. The encapsulation amount is not limited to the amount shown in the lamp of the present embodiment.

In addition, the distance between the electrodes shown in the mercury-free lamp of each embodiment, the internal volume of the arc tube 1, the amount of scandium iodide and the amount of sodium iodide, etc. The constituent elements other than the halogenated compound and xenon gas of the high-valent alloy are merely examples, and for example, the distance between the electrodes may be other than 4.2 mm, and the inner volume of the arc tube 1 may be different. Is not limited to 0.025 cc.

In the above example, xenon gas of about 0.7 MPa or 1.4 MPa at room temperature was sealed in the arc tube 1 to assist starting, but it was used for automobile headlights. In consideration of this, the rare gas is preferably xenon gas only, and the rare gas may be a rare gas other than xenon gas, for example, argon gas, and its filling pressure is about 0.7 at room temperature. It is not limited to MPa.

(Embodiment 5)

A method of raising the lamp wall voltage by raising the tube wall temperature of the arc tube in advance and increasing the vapor pressure of the metal halide will be described.

As shown in FIG. 15, the mercury-free metal halide lamp of FIG. 1 is held in an outer tube 8. The outer surface of the outer tube 8 has an infrared reflective film 9 are coated. As a result, the heat retention becomes higher.-The vapor pressure of the metal halide is easily increased, and the lamp voltage can be easily increased. Therefore, the current density can be kept low, and the lamp life can be easily extended.

As the infrared reflection film 9, for example, a film obtained by multilayer coating of a TaO x film and a Si x film by a thermal CVD method and a sputtering method can be used. The number of coating layers may be determined based on the tact time in manufacturing, the balance between manufacturing cost and lamp performance, and the like. On the other hand, the effect of increasing the vapor pressure of the metal halide is remarkably obtained. Further, the infrared reflecting film 9 may be coated not only on the outer surface of the outer tube 8 but also on the inner surface. As described above, the particularly preferred examples of the present invention have been described in the above embodiments. However, it is needless to say that the description is not limited and can be variously modified. The metal halide lamp of the present invention described in the present embodiment is an exemplification, and the scope of the present invention is determined by the appended claims. INDUSTRIAL APPLICABILITY As described above, according to the present invention, by setting the current density or the electrode tip temperature to a predetermined value or less, the evaporation of the electrode with the elapse of the lighting time is achieved. Thus, the lamp voltage can be increased and the arc tube 1 can be prevented from being blackened, and a long lamp life can be obtained. Therefore, the present invention is useful in fields such as general lighting and automobile headlights.

Claims

The scope of the claims

(1)

A mercury-free metal halide lamp that has a pair of discharge electrodes in the arc tube and contains at least a rare gas and a metal halide. S (mm ²⁾ the cross-sectional area of the Kinora lamp current and is lit at the rated power can and was I (a), and this I / S is ² 0 (a / mm 2) or less Mercury-free metal halide lamps.

(2)

A mercury-free metal halide lamp according to claim 1, wherein

A mercury-free metal lamp or ride lamp characterized in that the I / S is 15 (A / mm ² ) or less.

(3)

A mercury-free metal halide lamp according to claim 1, wherein

A mercury-free metal halide lamp, characterized in that the tip temperature of the discharge electrode at the time of lighting at a rated power is 320 K or less.

( Four )

The mercury-free metal halide lamp according to claim 3, wherein

A mercury-free metal halide lamp characterized in that the tip temperature of the discharge electrode when lit at rated power is 250 K or more.

( Five )

4. The mercury-free metal halide lamp according to claim 1 or 3, wherein at least one of a halide of scandium and a halide of sodium is contained in the arc tube. A mercury-free metal halide lamp characterized by containing:

(6)

A mercury-free metal halide lamp according to claim 5, wherein

A mercury-free metal halide lamp characterized in that the arc tube contains at least one of a halide of indium and a halide of yttrium.

(7)

A mercury-free metal halide lamp according to claim 1 or claim 3, characterized in that the arc tube contains at least a halide of +3 valent indium. Mercury-free metal halide lamp.

(8)

A mercury-free metal halide lamp according to claim 7, wherein

Furthermore, a mercury-free metal halide lamp characterized in that the arc tube contains a halide of thallium.

(9)

A mercury-free metal halide lamp according to claim 7, wherein

Further, the mercury-free metal halide is characterized in that the arc tube contains at least one of a halide of scandium and a halide of sodium. Drum.

( Ten )

A mercury-free metal halide lamp according to claim 8, wherein

Further, the mercury-free metal halide lamp characterized in that the arc tube contains at least one of a halide of scandium and a halide of sodium. Pump.

(1 1)

A mercury-free metal halide lamp according to claim 7, wherein

The halides of the above-mentioned trivalent indium are iodide or bromide A mercury-free metal halide lamp characterized in that it is at least one of objects.

(1 2)

4. The mercury-free metal halide lamp according to claim 1 or 3, further comprising an outer tube for holding the arc tube, wherein the outer tube is provided with an infrared reflection layer. Mercury metal halide lamp.