JP2003051283A - Mercury-free metal halide lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a white and bright lamp, which makes user's economical burden light, because the lamp life is long. SOLUTION: The lamp consists of a rare gas, a halide of Sc(scandium), a halide of Na(sodium), and adding a 3rd additive in luminescence valve. The 3rd additive is a metal or halide of a metal. The 3rd additive is selected from the thing that has the ionization voltage in the metal simple substance is 5 to 10(eV), and the steam pressure of the 3rd additive determined at a lamp temperature at operation is 1*10<-5> (atm) or higher.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to general lighting and
The present invention relates to a metal halide lamp used in a vehicle headlight or the like in combination with a reflector or the like.

[0002]

2. Description of the Related Art For example, as a light source used as a vehicle headlight, there is a metal halide lamp. In a conventional general metal halide lamp, three kinds of rare gas (gas), mercury (liquid), and metal halide (solid) are enclosed in an arc tube. The role of each of the lamp enclosures will be described. The rare gas is enclosed mainly for the purpose of starting, the metal halide for emitting light, and the mercury for enclosing the lamp voltage.

By encapsulating mercury, in particular, by increasing the lamp voltage and reducing the lamp current,
It is enclosed to reduce the heat load on the electrodes and extend the lamp life. With a typical lamp, the lamp voltage is 70-
The amount of mercury is adjusted to operate at 100 (V).

However, a lamp in which mercury is sealed has a lower production efficiency as compared with a lamp not containing mercury, and the number of steps of injecting liquid mercury into the steps of production increases, resulting in an increase in production cost. There is a problem such as. In particular, recently, a mercury-free metal halide lamp has been desired in consideration of the global environment.

However, when mercury is removed, the lamp voltage greatly decreases, so that when operating with the same power, the current increases and the heat load on the electrodes increases. As a result, the scattering of the electrodes is promoted, which causes a problem that the luminous flux maintenance factor of the lamp is shortened.

This will be described in detail below. The voltage of the lamp containing mercury: Vla (V) is, for example,
As disclosed in Japanese Patent Laid-Open No. 6-13047, it is represented by a known formula. This is shown in Equation 1. NHg in Formula 1
Is the mercury density (mg / cc) per unit internal volume of the arc tube
And L is a distance (mm) between electrodes. According to this known formula, the lamp voltage is proportional to the product of the distance between the electrodes and the mercury atom atomic density to the power of about 1/2. In addition, the constant 20 of Expression 1
Is the sum of the electrode drop voltage and the voltage increase due to the rare gas and metal halide.

Vla = 20 + k (proportional constant) * nHg0.56 * L Equation 1 According to Equation 1, when mercury is removed from the lamp, nHg = 0, so the lamp voltage is 20 It descends to about (V). Therefore, when operating with the same lamp power, it is necessary to compensate for the drop in the lamp voltage by increasing the lamp current. As a result, the heat load on the electrodes increases, blackening due to electrode scattering becomes noticeable, and the luminous flux maintenance factor of the lamp deteriorates.

Therefore, various attempts have been made to increase the lamp voltage when Hg is removed. 1 of this means
One example is the method disclosed in Japanese Patent Laid-Open No. 6-84496. This is to increase the lamp voltage by defining the Xe pressure to be enclosed above a certain condition. The details will be described below. The structure of JP-A-6-84496 is a metal halide lamp containing only a rare gas and a metal iodide such as scandium iodide (hereinafter referred to as ScI ₃ ) and sodium iodide (hereinafter referred to as NaI) in an arc tube and containing no mercury. , The distance between the electrodes of the lamp is L (m
m), when the rare gas to be filled is xenon (hereinafter referred to as Xe), when the filling pressure of Xe at room temperature is P (atmospheric pressure),
The configuration is such that PL ≧ 40 or more. That is, Xe
By defining the product of the pressure and the distance between the electrodes, the number of atoms in the arc is defined, the mobility of electrons is reduced, and the lamp voltage is increased. Also, with this configuration,
It is described that the effect of increasing the lamp voltage to 50 (V) or more can be obtained.

[0009]

[Patent Document 1] Japanese Patent Laid-Open No. 6-8
According to 4496, a metal halide lamp not containing mercury was prepared, lit and evaluated. Below, JP-A-6-84
The conventional metal halide lamp shown in FIG. 496 will be described with reference to FIG. In FIG. 5, reference numeral 51 is an arc tube made of quartz, and 52 at both ends of the arc tube 51 are sealing parts. 53 is a pair of electrodes made of tungsten, 54 is a molybdenum foil, 55 is a lead wire also made of molybdenum, and 56 is a metal halide. The electrodes 53 are electrically connected to molybdenum foils 54 sealed in the sealing portions 52, and the molybdenum foils 54 are electrically connected to lead wires 55, respectively. The distance between the tips of the electrodes 53, that is, the distance between the electrodes is arranged to be about 4 mm.

The inner volume of the arc tube 51 is about 0.025 cc.
In the inside, Xe is 10 (atmospheric pressure) at room temperature, and as the metal halide 56, ScI ₃ and NaI are 0.
25 mg is enclosed. The conventional metal halide lamp shown in FIG. 5 is PL = 4 according to the formula of Japanese Patent Laid-Open No. 6-84496.
0, which satisfies the condition of Japanese Patent Laid-Open No. 6-84496. Therefore, according to the contents described in Japanese Patent Laid-Open No. 6-84496, the lamp voltage should be 50V or more.

Therefore, the above metal halide lamp is
When the lamp was turned on with an input power of 35 (W) and the lamp voltage was measured, the voltage was 35 (V), which did not reach the stated lamp voltage of 50 (V).

From the above experimental results, the conventional known techniques,
According to Japanese Unexamined Patent Publication (Kokai) No. 6-84496, in order to obtain a lamp voltage of 50 V or more in a lamp not containing Hg, PL ≧ 4
The minimum Xe pressure of 10 (atm) that satisfies the condition of 0 is insufficient, and therefore Xe needs to be sealed at a higher pressure. The expected Xe pressure is 10 (a
It is 20 (atm) or more, which is much higher than tm).

However, if Xe is enclosed at a high pressure in this way, the following problems will occur in practice. The ionization voltage of Xe is as high as about 12 (eV), and therefore 20 (at
It is necessary to apply a high voltage in order to generate a discharge under a pressure of m) or higher. Generally, 7-10 (atm)
In the case of a lamp filled with about Xe, an applied voltage of 30 (KV) or more is required to surely cause discharge. Therefore, in the case of a lamp containing 20 (atm) or more of Xe, the voltage required for starting far exceeds 30 (KV), which causes problems such as a complicated lighting circuit and large size and uneconomical. To do.

In view of the breaking strength of the lamp, a lamp having a high filling pressure is not preferable because it may break.

Further, Xe has a high excitation voltage as compared with other enclosed materials, and there is a problem that the high-pressure encapsulation of Xe causes a decrease in luminous efficiency.

[0016]

In order to solve the above problems, the metal halide lamp of the present invention has the following features.

That is, the mercury-free metal halide lamp of the present invention has a structure in which a third additive is added to the arc tube in addition to the rare gas, the halide of Sc (scandium) and the halide of Na (sodium), The third additive is a metal or a metal halide, has an ionization voltage of 5 to 10 (eV) in a metal simple substance, and has a vapor pressure of the metal halide of 1 determined by the lamp temperature during operation.
It is characterized in that the rare gas is selected from those of 0 ⁻⁵ (atm) or more, the rare gas contains at least Xe (xenon), and the filling pressure of the rare gas is 1 to 10 atm at room temperature.

The third additive of the mercury-free metal halide lamp of the present invention is characterized in that it is a halide of Y (yttrium).

The third additive of the mercury-free metal halide lamp of the present invention is characterized in that it is a halide of In (indium).

The chromaticity point of the emitted light of the mercury-free metal halide lamp of the present invention is characterized in that it operates so as to satisfy the following formula on the CIE1931xy chromaticity diagram.

X ≧ 0.310 x ≦ 0.500 y ≦ 0.150 + 0.640x y ≦ 0.440 y ≧ 0.050 + 0.750x y ≧ 0.382 (where x ≧ 0.44) The third of mercury-free metal halide lamps
The additive is YI ₃ , the amount of YI ₃ enclosed is 0.8 to 12 (mg / cc) per unit inner volume of the arc tube, and the lamp power is turned on at 30 to 55 W.

Further, the metal halide lamp of the present invention is characterized in that it operates at a luminous flux of 2000 (lm) or more.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) Embodiment 1 of the present invention will be described below. 1 is a diagram showing a metal halide lamp according to a first embodiment of the present invention. The lamp of the present embodiment has exactly the same structure as the conventional lamp shown in FIG. In FIG.
Reference numeral 11 is an arc tube made of quartz, and 12 at both ends of the arc tube 11 are sealing portions. 13 is a pair of electrodes made of tungsten, 14 is a molybdenum foil, 15 is a lead wire also made of molybdenum, and 16 is a metal halide. The electrodes 13 are electrically connected to the molybdenum foils 14 sealed in the sealing portions 12, and the molybdenum foils 14 are electrically connected to the lead wires 15, respectively. The distance between the tips of the electrodes 13, that is, the distance between the electrodes is arranged to be about 4 (mm). Arc tube 11
The internal volume of is about 0.025 (cc),
In addition to the metal halide 16, 7 (atm) of Xe is sealed as a starting gas at room temperature. Metal halide 1
In the configuration of No. 6, ScI ₃ and NaI total 0.25 (m
g) and 0.3 (mg) of YI ₃ as a _third additive.

That is, in the lamp of this embodiment, the enclosed Xe pressure is 7 (at) as compared with the conventional lamp shown in FIG.
m) and the same configuration except that 0.1 (mg) of YI ₃ was added.

Here, the lamp of the first embodiment is set to 200
The temperature of the coldest spot when the lamp is horizontally lit at a power of 45 (W) with a rectangular wave current of (Hz) is about 700 at the lower surface of the arc tube.
(° C). From this, the temperature of the inner surface of the quartz tube where YI ₃ exists is about 800 (° C) considering the heat conduction of quartz.
It is estimated to be. The vapor pressure of YI ₃ at 800 (° C.) is about 10 ⁻⁵ (atm), and the ionization voltage of Y alone is 6.
It is 4 (eV), which satisfies claim 1. The voltage of this lamp is 35 (V). Also, for comparison, Y
The voltage of the conventional lamp without I ₃ is 28 (V)
Is. Therefore, by adding YI ₃ ,
(V) A voltage rise is obtained. Therefore, in the lamp of the present embodiment, as compared with the conventional metal halide lamp shown in FIG. 5, because the lamp voltage is higher, the lamp current can be suppressed, and the thermal load on the electrodes is reduced. As a result, blackening is suppressed. The lamp has a good luminous flux maintenance factor.

FIG. 2 shows a plot of the chromaticity points of the emitted light of the lamp of this embodiment on the CIE1931xy chromaticity diagram. The frame shown by the solid line in FIG. 2 is a HID light source for automobile headlights (JEL 21
It is the chromaticity range of the white light source specified in 5). This is represented by the formula shown in claim 3. Therefore, the lamp of the present embodiment satisfies the chromaticity of the white light source for automobile headlights.

The luminous flux of the lamp of this embodiment is 4
It is 700 (lm). Here, the luminous flux of a halogen lamp which is generally used for a vehicle headlight at present is about 2000 (lm). Therefore, the lamp of the present embodiment has a luminous flux that can be used for a vehicle headlight.

The chromaticity point of the emitted light of the lamp is YI ₃
It largely depends on the addition amount per unit inner volume of the arc tube and the lamp power. The amount of YI ₃ added is such that the enclosed weight per unit internal volume of the arc tube is 0.8 (mg / cc) to 12 (mg / c).
c) is desirable, and the lamp power is 3
It is preferably 5 to 55 (W). FIG. 3 shows that the amount of YI ₃ added to the lamp of the present embodiment was changed to 200
It is a diagram in which the chromaticity point of the emitted light is plotted on the CIE1931xy chromaticity diagram by lighting with a rectangular wave current of (Hz) and a lamp power of 45 (W). The frame shown by the solid line in FIG. 3 is, like FIG. 2, the HI for automobile headlights of the Japan Light Bulb Industry Association standard.
It is the chromaticity range of the white light source described in D light source (JEL 215). The numbers beside the plots in the figure indicate the amount of YI ₃ added. As shown in FIG.
All lamps are in the white chromaticity range. Further, when the amount of YI ₃ added increases, the emission of Y, which has abundant emission in the blue region, becomes remarkable, and the x value and the y value of chromaticity become small. Therefore, the amount of YI ₃ added is 12 (mg /
If it is cc) or more, it is out of the chromaticity range of white.

Similarly, the amount of YI ₃ added is 0.8 (m
Even if it is set to g / cc) or less, it is out of the chromaticity range of white. Therefore, the amount of YI ₃ added is 0.8 to 12 (mg /
cc) is desirable, and by defining it within this range, the chromaticity of the lamp can be kept within the chromaticity range of white. Further, although the case of the lamp power of 45 W is shown, similar results were obtained in the range of the lamp power of 35 to 55 (W).

(Second Embodiment) A second embodiment of the present invention will be described below. Several types of lamps having exactly the same structure as the lamp of the first embodiment shown in FIG. The prototyped lamp uses indium iodide (hereinafter referred to as InI) as the third metal halide. That is, the metal iodide 16 is composed of conventional ScI ₃ , NaI and InI.

When this lamp was horizontally lit with a rectangular wave current of 200 Hz and an electric power of 45 (W), the coldest spot temperature was a surface temperature of about 700 (degrees) below the arc tube. Than this,
The temperature of the inner wall of the arc tube where InI exists is about 800 (degrees).
It is estimated to be. The vapor pressure of InI at 800 degrees is about 2
(Atm), and the ionization voltage of In alone is 5.8 (e
V), which satisfies claim 1. The voltage of this lamp was 45 (V). Since the voltage of the conventional lamp to which InI was not added was 28 (V), the voltage was increased by 17 (V) by adding InI.

As described above, ScI is used as the metal halide 16.
In addition to ₃ and NaI, the metal halide lamp of the present invention configured as added InI, as compared to a metal halide lamp that is constituted only by the conventional ScI ₃ and NaI, having a higher lamp voltage. Therefore, the lamp current can be suppressed, the heat loss at the electrode is smaller, and the excessive temperature rise of the electrode can be prevented, so that a long-life lamp with less blackening can be realized.

FIG. 4 shows the chromaticity points of the emitted light of the lamp of this embodiment plotted on the CIE1931xy chromaticity diagram. The frame shown by the solid line in FIG. 4 is shown in FIGS.
Same as above, HID for automobile headlights of the Japan Light Bulb Industry Association standard
It is within the chromaticity range of the white light source described in Light Source (JEL 215). Therefore, the lamp of the present embodiment satisfies the chromaticity of the white light source for automobile headlights.

The luminous flux of the lamp of this embodiment is 3
It is 600 (lm). Here, the luminous flux of a halogen lamp which is generally used for a vehicle headlight at present is about 2000 (lm). Therefore, the lamp of the present embodiment has a luminous flux that can be used for a vehicle headlight.

In the first and second embodiments, the third
The case where YI ₃ and InI are added as the additive of the above is explained. The third additive is a metal or a metal halide, and the ionization voltage of the metal simple substance is 5 to 10 (eV),
The vapor pressure determined by the lamp temperature during operation is 10 ^-5 (at
Other than YI ₃ and InI may be used as long as they are at least m). For example, YBr ₃ (yttrium bromide), InI
₃ (indium iodide), InBr (indium bromide), TlI (thallium iodide), or the like may be used.

On the other hand, in the case of adding a substance having an ionization voltage of 5 (eV) or less for the third additive metal alone, for example, CsI (cesium iodide: ionization voltage 3.9 (eV)), the lamp is used. The voltage drops. This is because a large amount of electrons are supplied into the arc due to the low ionization voltage, so that the lamp current increases and the lamp voltage decreases correspondingly.

The ionization voltage of the third additive is 10 (e
When a substance of V) or higher, such as Hg (mercury), was added, the efficiency of the lamp decreased.

When a substance having a vapor pressure determined by the lamp temperature during operation of 10 ⁻⁵ or less, for example, BaI ₂ (barium iodide) is enclosed, the lamp voltage does not rise.

It should be noted that the effect of increasing the voltage can be obtained by adding YI ₃ and InI, in addition to the encapsulation amount and the encapsulation ratio described in the first and second embodiments.

In the first and second embodiments, the case where I (iodine) is used as the halogen of the halide has been described, but the same effect can be obtained by using other halogen such as Br (bromine) or a combination thereof. can get.

In the first and second embodiments, the electric power of 45
Although the case of W has been described, the effect of increasing the lamp voltage can be obtained regardless of the power.

In the first and second embodiments, the case has been described in which Xe is sealed at 7 atmospheres at room temperature, but the effect of the present invention can be obtained regardless of the type and pressure of the rare gas. Further, considering the light rising characteristics at the time of starting and the breaking strength of the lamp, the Xe pressure is preferably 1 to 10 atm at room temperature.

In the first and second embodiments, the metal halide lamp having a pair of electrodes has been described.
The same effect can be obtained in the electrodeless metal halide lamp.

[0044]

As described above, according to the present invention, the third additive is added to the arc tube in addition to the rare gas, the halide of Sc (scandium) and the halide of Na (sodium). The third additive is a metal or a metal halide, and the third additive has an ionization voltage of a simple metal of 5 to 10 (eV), and the third additive is a lamp during operation. Vapor pressure determined by temperature is 10
^The lamp voltage can be increased without excessively increasing the internal pressure of the arc tube and without lowering the efficiency of the lamp by selecting from those which are equal to or higher than ^-5 (atm). This allows the lamp current to be kept relatively low and the thermal load on the electrodes to be reduced. Therefore, it is possible to suppress the blackening of the arc tube due to the scattering of the electrodes,
The luminous flux maintenance factor of the lamp can be improved. Moreover, since the internal pressure of the arc tube can be kept relatively low, the life of the arc tube can be improved.

That is, since the metal halide lamp of the present invention has a long lamp life, it is possible to obtain a white and bright lamp with a light economical burden on the user.

[Brief description of drawings]

FIG. 1 is a diagram showing a metal halide lamp according to a first embodiment of the present invention.

FIG. 2 is a diagram showing chromaticity points of emitted light of the metal halide lamp according to the first embodiment of the present invention.

FIG. 3 is a diagram showing chromaticity points of emitted light when changing the amount of YI ₃ added to the metal halide lamp according to the first embodiment of the present invention.

FIG. 4 is a diagram showing chromaticity points of emitted light of the metal halide lamp according to the second embodiment of the present invention.

FIG. 5 is a diagram showing a conventional metal halide lamp.

[Explanation of symbols]

11 arc tube 12 Sealing part 13 electrodes 14 Molybdenum foil 15 lead wire

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mamoru Takeda             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Takeshi Saito             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Hideaki Kiryu             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 5C015 PP05 PP07 QQ03 QQ14 QQ15                       QQ58 RR05 SS04

Claims (6)

[Claims] 1. A structure in which a third additive is added to the arc tube in addition to a rare gas, a halide of Sc (scandium) and a halide of Na (sodium), and the third additive is a metal. Alternatively, it is a metal halide, and the third additive has an ionization voltage of a simple metal of 5 to 10
(EV), the third additive is selected from those having a vapor pressure determined by the lamp temperature during operation of 10 ⁻⁵ (atm) or more, and the rare gas is at least Xe (xenon). A mercury-free metal halide lamp, characterized in that the rare gas is enclosed at a pressure of 1 to 10 atm at room temperature. 2. The mercury-free metal halide lamp according to claim 1, wherein the third additive is a Y (yttrium) halide. 3. The mercury-free metal halide lamp according to claim 1, wherein the third additive is a halide of In (indium). 4. The chromaticity point of the emitted light of the lamp is CIE193.
The mercury-free metal halide lamp according to any one of claims 1 to 3, which operates so as to satisfy the following formula on a 1xy chromaticity diagram. x ≧ 0.310 x ≦ 0.500 y ≦ 0.150 + 0.640x y ≦ 0.440 y ≧ 0.050 + 0.750x y ≧ 0.382 (where x ≧ 0.44) 5. The third additive is YI ₃ , wherein Y
The enclosed amount of I ₃ is 0.8 to 12 per unit inner volume of the arc tube.
(Mg / cc) and the lamp power is 35 to 55 (W)
The mercury-free metal halide lamp according to claim 4, wherein the mercury-free metal halide lamp is lit with. 6. The mercury-free metal halide lamp according to claim 1, wherein the luminous flux of the lamp operates at 2000 (lm) or more.