JP2002093368A - Non-mercury metal halide lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-mercury metal halide lamp having an electrode that has a narrow arc. SOLUTION: This is a non-mercury metal halide lamp which is equipped with an arc tube (1) having a pair of electrodes (3, 3) opposed to each other within, and which contains a rare gas and a halide (7) of cerium and does not contain mercury in the arc tube (1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mercury-free metal halide lamp. In particular, the present invention relates to a lamp for a point light source used in combination with a reflector or the like.

[0002]

2. Description of the Related Art Metal halide lamps in which a metal halide is sealed in an arc tube are becoming widespread as lamps for general lighting and headlights of automobiles. Conventional metal halide lamps include a lamp having an electrode in an arc tube (hereinafter, referred to as an "electrode type lamp") and a lamp without an electrode in an arc tube (hereinafter, referred to as an "electrodeless lamp").

A specific example of a conventional electrode type metal halide lamp is disclosed, for example, in Japanese Patent Application Laid-Open No. 57-92747. The electroded lamp disclosed in the publication has a rare gas, mercury, sodium halide, and, for example, cerium halide in an arc tube. It is stated in the publication that high luminous efficiency and white light characteristics can thereby be realized.

A specific example of a conventional electrodeless metal halide lamp is disclosed in, for example, Japanese Patent Laid-Open No. 1-1320.
There is one disclosed in Japanese Patent Publication No. 39. The electrodeless lamp disclosed in this publication has a sodium halide, a cerium halide, and xenon in an arc tube. The publication discloses that white lamp light emission can thereby be realized.

[0005]

However, it has been found that the conventional lamp has a problem that the width of the arc becomes large. If the arc width is large, a metal halide lamp that does not conform to the standard may be produced. For example, in a metal halide lamp for a vehicle headlight, a standard is defined for an arc width. Therefore, it is necessary to set the arc width in a range defined by the standard.

[0006] The Japan Light Bulb Manufacturers Association, HID light source for automobile headlights (JEL215)
When the relative luminance distribution in the central cross section of the arc (the center position between the electrodes) is measured, the width of the 20% luminance value of the maximum value is defined as the width of the arc, and the width of the arc is 1.10 mm. It must be within ± 0.40 mm. This standard specifies that when a lamp is incorporated into a lamp,
This is for performing light distribution control.

According to Japanese Patent Application Laid-Open No. 57-92747,
It is stated that an electroded lamp having a rare gas, mercury, a halide of sodium (Na), and a halide of cerium (Ce) can realize a widened and stable discharge arc. Then, the inventor of the present application produced a lamp according to the publication. The manufactured lamp has an arc tube with an inner volume of 0.025 cc, 0.65 mg of mercury, 0.16 mg of Na halide, and 0.2 of Ce halide.
mg encapsulated. When this lamp was turned on with power consumption of 35 W, the width of the arc was 1.8 mm. This greatly deviates from the standard. That is, C
The electrode type metal halide lamp containing the halide e and mercury has a problem that the width of the arc becomes large.

The electrodeless lamp disclosed in Japanese Patent Application Laid-Open No. 1-132039 has a problem that an arc spreads over the entire arc tube. This is a feature of the electrodeless lamp, and the size of the arc tube becomes the size of the arc as it is. Although attempts to reduce the size of the arc tube are active, it is difficult to reduce the size of the arc tube due to problems such as breakage of the lamp, and the fact is that the attempt is not yet sufficient. For example, when the same energy as disclosed in the publication is applied to a smaller arc tube than the one disclosed in the publication, the temperature of the arc tube rises excessively, and as a result, It was confirmed by the experiment of the present inventor that the rupture occurred in several hours. Therefore, in the electrodeless metal halide lamp, there is a problem that it becomes difficult to use a light source that is very close to a point light source in order to combine it with a reflector or the like.

In recent years, environmental issues have been emphasized, and a metal halide lamp containing no mercury has been desired in consideration of the global environment at the time of disposal. Japanese Unexamined Patent Application Publication No. 1-132039
The electrodeless lamp disclosed in the above publication is a mercury-free metal halide lamp. However, as described above, it is very difficult to realize a point light source because of the electrodeless lamp.

The present invention has been made in view of the above points, and a main object thereof is to provide a mercury-free metal halide lamp having a narrow arc width.

[0011]

A mercury-free metal halide lamp according to the present invention includes an arc tube having a pair of opposed electrodes in the tube, and the arc tube contains a rare gas and a cerium halide. And does not contain mercury.

In one embodiment, the arc tube further contains at least one of a scandium halide and a sodium halide.

In one embodiment, the total amount of halide enclosed in the arc tube is 30 mg / cc or less as a value per 1 cc volume in the arc tube.

In one embodiment, the rated power of the mercury-free metal halide lamp is set to 25 W or more and 55 W or less.

In one embodiment, the rare gas contains at least Xe (xenon), and the pressure of the rare gas charged at room temperature is 0.1 MPa or more and 2.5 MPa or less.

In one embodiment, a means for applying a magnetic field to the arc tube is further provided.

The mercury-free metal halide lamp is preferably a lamp for a point light source.

Another mercury-free metal halide lamp according to the present invention includes an arc tube having a pair of opposing electrodes in the tube, and the arc tube contains a rare gas, a cerium halide, a zinc halide, and aluminum. At least one selected from the group consisting of halides, antimony halides, and indium bromide, and does not contain mercury.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The inventor of the present application has conducted intensive studies to develop an electrode-type mercury-free metal halide lamp having a narrow arc width, and as a result, has succeeded in completing such a mercury-free metal halide lamp. did.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, components having substantially the same function are denoted by the same reference numeral for simplification of description. Note that the present invention is not limited to the following embodiments.

The mercury-free metal halide lamp according to the embodiment of the present invention will be described. FIG. 1 schematically shows a cross-sectional configuration of a mercury-free metal halide lamp of the present embodiment.

The lamp of the present embodiment includes an arc tube 1 having a pair of opposed electrodes (3, 3) in the tube. A pair of sealing portions 2 for hermetically sealing the arc tube 1 extend from the arc tube 1, and the electrodes 3 are connected to a lead wire 5 made of molybdenum via a metal foil 4 in the sealing portion 2. It is connected. In other words, the electrode 3 is electrically connected to one end of the molybdenum foil 4 sealed by the sealing portion 2,
It is electrically connected to a lead wire 5 connected to the other end of the molybdenum foil 4.

The electrode 3 is a tungsten electrode made of tungsten (the diameter of the electrode rod is about 0.25 mm). The tip of the electrode 3 has a distance between the tips (that is, a distance between the electrodes) of about 3. It is arranged in the arc tube 1 so as to be 7 mm. The arc tube 1 is made of quartz glass, and the inner volume of the arc tube 1 is about 0.025 cc. Inside the arc tube 1, about 0.2 mg of cerium iodide (CeI ₃ ), about 0.19 mg of scandium iodide (ScI ₃ ), and about 0.16 mg of sodium iodide (N
aI), and xenon gas (Xe) of about 1.4 MPa at room temperature (not shown). However, mercury is not sealed in the arc tube 1.

This lamp is lit so that the straight line connecting the electrodes is substantially horizontal. That is, it is lit horizontally.
Note that the lighting may be performed vertically or may be performed diagonally. In the present embodiment, the lighting power is 35 W. The major difference between the conventional electrode-type metal halide lamp and the metal halide lamp of the present embodiment is that the metal halide lamp of the present embodiment does not contain mercury.

The electrode type mercury-free metal halide lamp of the present embodiment is surprisingly surprising.
Despite being a lamp in which is enclosed, the arc width is narrow and high brightness is exhibited. Here, a method of measuring the arc width and the arc luminance will be described with reference to FIG.

FIG. 2 schematically shows a configuration of a measuring device for measuring an arc width and an arc brightness. The measuring lamp 20 is electrically connected to a ballast for lighting the lamp and a power supply (21). Lamp 20
Through the filter 22 provided near the arc tube of
The D camera 23 captures an image of the arc of the lamp 20, and the image captured by the CCD camera 23 is displayed on a monitor 24.

The width of the arc was measured in accordance with the Japan Light Bulb Manufacturers Association standard (JEL215) for HID light sources for automotive headlamps. The arc width defined by the Japan Light Bulb Manufacturers Association standard (JEL215) is the width of 20% of the maximum brightness value when the relative brightness distribution of the arc at the center cross section of the arc (center position between electrodes) is measured.

FIG. 3 shows an example of an arc luminance distribution. The vertical axis in FIG. 3 represents the ratio of the arc to the maximum brightness, and the horizontal axis represents the arc position. Generally, the brightness of the arc is the highest at the position of the center section of the arc (the center position between the electrodes), and is substantially symmetric about the position of the center section of the arc (the center position between the electrodes).

The maximum luminance value and the arc width of the lamp of this embodiment were measured by the method described above.

Table 1 below shows a list of the lamp enclosures measured by the present inventors.

[0031]

[Table 1]

The lamp 1 is a mercury-free metal halide lamp in this embodiment, and the lamp 2 is a conventional lamp (comparative example) in which 0.65 mg of mercury is added to this lamp. The lamps 3 to 7 are also mercury-free metal halide lamps of this embodiment in which mercury is not sealed.

The lamps 3 to 5 have ScI ₃ of 0.03 m
g, 0.02 mg of NaI and 0.1 mg of zinc iodide (ZnI ₂ ) added thereto (lamp ₃ ) and 0.1 ml of aluminum iodide (AlI ₃ ), respectively.
mg (lamp 4), and 0.1 mg of antimony iodide (SbI ₃ ) (lamp 5). Lamp 6 has 0.2 mg of indium bromide (InBr) sealed therein instead of CeI ₃ of lamp 1. Then, the lamp 7 has In
0.2 mg of Br was added.

The present inventor conducted experiments on lamps 1 to 7 and examined the arc width and luminance characteristics. FIG. 4 shows the results. The vertical axis in FIG. 4 represents the maximum luminance of the lamp, and is shown as a relative value when the maximum luminance value of the lamp 2 (Comparative Example) is set to 1. The horizontal axis in FIG. 4 represents the arc width (mm). A lamp having a high luminance value and a narrow arc width is a lamp having characteristics that are closer to a point light source and have improved characteristics of condensing efficiency when used in combination with a reflector or the like.

As can be seen from FIG. 4, the lamp 1 and the lamps 3 to 7 have a smaller arc width than the lamp 2 (comparative example). In other words, by sealing a halide of Ce, a halide of Zn, a halide of Al, a halide of Sb, and indium bromide in a lamp containing no mercury, there is an effect of reducing the arc width. The present inventor has found. As shown in FIG. 4, the arc width of lamps 5, 4, 7 is 1.2 mm, the arc width of lamps 3, 6 is 1.1 mm, and the arc width of lamp 1 is 1 mm. 0.0 mm.

The lamps 1 and 7 also have improved luminance compared to the lamp 2 (comparative example). That is, lamp 2
As compared with the comparative example, the lamp 1 had 1.5 times the luminance and the lamp 7 had 1.2 times the luminance. Lamp 1 and Lamp 7
Have a common feature that they both contain a cerium halide. Therefore, by encapsulating a Ce halide in an electrode type lamp that does not contain mercury, a lamp with a narrow arc width and high brightness can be realized.

Further, lamp 1, lamps 3 to 7, and
And ScI_Three0.19 mg and NaI 0.16 mg
Lamp voltage and radiation
The light efficiency was measured. The lamp is easy to understand
8 is the lamp 1 from the CeI _ThreeIt is a lamp that only
You.

FIG. 5 shows the measurement results. As can be seen from FIG. 5, lamp 1 shows the highest efficiency. That is, the lamp 1 in which the halogenated Ce is sealed has 116 lm / W,
It has been found to have very high efficiency. Therefore, when realizing a high-efficiency lamp, it is preferable to adopt the configuration of the lamp 1. In terms of lamp voltage, lamp 8
Has a lamp voltage of 28 V, whereas lamps 1, 3 to
7, it can be seen that the lamp voltage is higher than that. That is, enclosing a halide of Ce, a halide of Zn, a halide of Al, a halide of Sb, and indium bromide has an effect of increasing a lamp voltage. If the lamp voltage can be increased, the current of the lamp can be reduced, so that the consumption of the electrodes can be suppressed. In addition, if the lamp voltage can be increased, it is possible to perform lighting with a small amount of current, and the effect that the lighting circuit (ballast) can be reduced in size can be obtained.

The effects of the present inventors that the arc width is reduced and the brightness is increased by enclosing the halide of Ce in the mercury-free electrode-type lamp are as follows.
Irrespective of other components, such as the lamp power, the distance between the electrodes, the internal volume of the arc tube 1, the amount of Sc iodide or Na iodide, or the type or amount of halide as an inclusion other than Ce. Therefore, the present invention is not limited to those conditions. Further, if it is desired to obtain the effect of narrowing the arc width, not only a mercury-free metal halide lamp in which a halide of Ce is sealed, but also a halide of Zn, a halide of Al, a halide of Sb, and indium bromide. An enclosed mercury-free metal halide lamp is also applicable. However, in order to realize a high-luminance, high-efficiency lamp with a narrow arc width, which is not included in a conventional lamp, it is preferable to adopt a configuration like the lamp 1 of the present embodiment.

The effect of increasing the lamp voltage can be obtained by increasing the total enclosed amount of the halide.
Increasing the total halide loading tends to provide good properties for the lamp. However, when the halide is enclosed in an amount exceeding 30 mg / cc in terms of the value per unit arc tube internal volume, the enclosure that has not evaporated during lamp operation rises up to the center of the arc tube along the arc tube wall. A phenomenon can occur. When this phenomenon occurs, the arc is hidden by the shadow of the inclusion that has risen, and good characteristics cannot be exhibited. Therefore, it is preferable that the amount of halide to be enclosed is 30 mg / cc or less per unit arc tube volume.

In the lamp 1 of this embodiment, in addition to Ce halide, Sc iodide and Na iodide are sealed. The main reason for encapsulating these halides is to improve the luminous flux of the lamp.

The total amount of Sc iodide and Na iodide encapsulated is preferably 2 mg / cc or more and 15 mg / cc or less. When the lamp is lit for a long time, the iodide of Sc or the iodide of Na reacts with the glass or sinks into the base of the electrode, and as a result, the amount of iodide capable of emitting light decreases. For this reason, it is preferable to encapsulate at least 2 mg / cc.

FIG. 6 shows the relationship between the total amount of Sc and Na iodides and the lamp luminous flux. The horizontal axis in FIG. 6 indicates the total amount of Sc and Na iodides (Sc + Na total).
The vertical axis represents the luminous flux (lm) of the lamp. As shown in FIG. 6, when the total amount of the iodide of Sc and the iodide of Na is too large, absorption of light emission occurs and the like.
The luminous flux falls. Therefore, the total amount of the iodide of Sc and the iodide of Na is preferably set to a predetermined amount or less. For example, if the dose is set to about 15 mg / cc or less, a light flux of about 2700 lm can be secured. According to the Japan Light Bulb Manufacturer's Association standard for HID light sources for automotive headlights, the luminous flux of the lamp must be 2700 lm or more.
/ Cc or less.

When the luminous flux is 2800 lm or more,
It is preferred to be 13 mg / cc or less. When the luminous flux is 2600 lm or more, it is preferable to set it to 16 mg / cc or less. When the luminous flux is 2400 lm or more, 1
It is preferable that the content be 9 mg / cc or less.

In addition, the amount of Ce halide to be enclosed is 0.
It is preferably from 8 mg / cc to 15 mg / cc. The reason will be described with reference to FIG. FIG.
The horizontal axis indicates the amount (mg / cc) of Ce halide per unit volume inside the arc tube, and the vertical axis indicates the lamp voltage (V).

As shown in FIG. 7, the lamp voltage rises as the Ce halide is sealed. Lamp voltage is 3
If the voltage is lower than 0 V, the lamp current increases, that is, the load on the electrodes increases, so that it is not practical. Therefore,
In order to obtain a lamp voltage of 30 V or more, the amount of Ce halide per unit volume of the arc tube is 0.8 mg.
/ Cc or more.

When the amount of Ce halide is increased, the luminous flux is increased, and the lamp characteristics tend to be good. Therefore, it is preferable that the amount of Ce halide is relatively large. However, 1 per unit arc tube volume
When a Ce halide of 5 mg / cc or more is sealed, a phenomenon may occur in which the sealed material that has not evaporated during lamp operation rises to the center of the arc tube along the arc tube wall. If that phenomenon occurs, the arc will be hidden by the shadow of the enclosure, and the desired characteristics may not be exhibited. Therefore, it is preferable that the amount of Ce halide to be enclosed is 15 mg / cc or less per unit arc tube volume.

Next, the amount of other halogenated substances sealed in the lamps 3 to 6 in this embodiment will be described.

First, the lamp 3 will be described. Regarding the lamp 3, the amount of the enclosed halide of Zn was 0.2 mg.
/ Cc or more and 15 mg / cc or less.
The reason will be described with reference to FIG. The abscissa in FIG. 8 represents the amount (mg / cc) of Zn halide per unit volume in the arc tube, and the ordinate represents the lamp voltage (V).

As shown in FIG. 8, in order to increase the lamp voltage to 30 V or more, the amount of the halide of Zn must be set to 0.1.
It is preferable that the concentration be 2 mg / cc or more. Also, if the enclosure is filled at 15 mg / cc or more per unit arc tube internal volume, a phenomenon may occur in which the enclosure that has not evaporated on the arc tube wall even while the lamp is on rises to the arc tube center. If that phenomenon occurs, the arc will be hidden by the shadow of the enclosure, and the desired characteristics may not be exhibited. Therefore, Z
The amount of the halide of n is preferably 15 mg / cc or less per unit arc tube volume.

Next, the lamp 4 will be described. Regarding the lamp 4, the amount of Al halide enclosed was 0.5 mg.
/ Cc or more and 15 mg / cc or less.
The reason will be described with reference to FIG. The abscissa of FIG. 9 represents the amount of encapsulated Al halide per unit volume in the arc tube (mg / cc), and the ordinate represents the lamp voltage (V).

As shown in FIG. 9, in order to increase the lamp voltage to 30 V or more, the amount of the halide of Al is set to 0.1.
It is preferable that the concentration be 5 mg / cc or more. Also, if the enclosure is filled at 15 mg / cc or more per unit arc tube internal volume, a phenomenon may occur in which the enclosure that has not evaporated on the arc tube wall even while the lamp is on rises to the arc tube center. If that phenomenon occurs, the arc will be hidden by the shadow of the enclosure, and the desired characteristics may not be exhibited. Therefore, A
It is preferable that the enclosed amount of the halide 1 is 15 mg / cc or less per unit arc tube internal volume.

Next, the lamp 5 will be described. Regarding the lamp 5, the amount of Sb halide enclosed was 1.1 mg.
/ Cc or more and 15 mg / cc or less.
The reason will be described with reference to FIG. The horizontal axis in FIG. 10 represents the amount of Sb halide enclosed per unit volume in the arc tube (mg / cc), and the vertical axis represents the lamp voltage (V).

As shown in FIG. 10, the lamp voltage was set to 30V.
In order to achieve the above, the amount of halide of Sb should be
It is preferable that the concentration be 1.1 mg / cc or more. In addition, if 15 mg / cc or more is enclosed per unit arc tube volume,
A phenomenon may occur in which the filling material that has not evaporated on the arc tube wall even during the operation of the lamp rises to the center of the arc tube. When that phenomenon occurs, the arc will be hidden behind the enclosure,
There is a possibility that desired characteristics cannot be exhibited. Therefore, it is preferable that the enclosed amount of the Sb halide be 15 mg / cc or less per unit arc tube volume.

Next, the lamp 6 will be described. In the lamp 6, the amount of InBr sealed is preferably 0.1 mg / cc or more and 15 mg / cc or less. The reason will be described with reference to FIG. The horizontal axis in FIG.
The amount of InBr halide enclosed per unit volume in the arc tube (mg / cc) is shown, and the vertical axis shows the lamp voltage (V).

As shown in FIG. 11, the lamp voltage was set to 30V.
In order to achieve the above, the amount of InBr encapsulated is 0.1 mg.
/ Cc or more. Also, if the enclosure is filled at 15 mg / cc or more per unit arc tube internal volume, a phenomenon may occur in which the enclosure that has not evaporated on the arc tube wall even while the lamp is on rises to the arc tube center. If that phenomenon occurs, the arc will be hidden by the shadow of the enclosure, and the desired characteristics may not be exhibited. Therefore, InB
r is 15 mg / cc per unit arc tube volume.
It is preferable to set the following.

In the above-described configuration of the present embodiment, when the lighting operation is performed with a lamp power of about 25 W or more, a stable arc that can sufficiently maintain the lighting can be obtained. In addition, the more the lamp is turned on with a larger lamp power, the more luminous flux is obtained. However, in the use range of the vehicle headlight, the upper limit of the power consumption of the lamp of the present embodiment may be approximately 55 W in practice. Because the power consumption of halogen lamps for automobile headlights currently used is 5
This is because lighting in the range of 5 W and exceeding 55 W is uneconomical and not very desirable. If the use is desired even if it is uneconomical, the upper limit may be over 55W.

Here, the sealing pressure of the Xe gas will be described. In order to make the lamp suitable for practical use, in the electrode type metal halide lamp containing no mercury according to the present embodiment, it is preferable that the upper limit of the sealing pressure of the Xe gas is set to about 2.5 MPa (converted to room temperature). . About 2.5MPa
If the lamp is sealed as described above, the configuration of the lamp according to the present embodiment is not preferable because the possibility that airtightness inside the arc tube 1 leaks from the vicinity of the connection between the electrode 3 and the molybdenum foil 4 during the lighting operation is increased. . A more preferable upper limit of the sealing pressure of the Xe gas is about 2.0 MPa. However, when the lamp of the present embodiment is used as a light source for an automobile headlight that requires a short rise in light, the lower limit is more preferably about 0.1 MPa.

Further, since the lamp of this embodiment has a narrow arc width, it is easily affected by the convection force of gas generated by the arc tube temperature distribution. Therefore, a phenomenon in which the arc is curved is observed. Therefore, as shown in FIG. 12, means (for example, a permanent magnet) 8 for applying a magnetic field 9 having a component perpendicular to a straight line connecting the electrodes 3 of the lamp is provided near the lamp of the present embodiment. It may be. When such a magnetic field 9 is applied, arc bending can be suppressed. Although the principle of suppressing the arc curvature of a mercury-free metal halide lamp by applying the magnetic field 9 is not always clear at present, the parameters capable of suppressing the arc curvature are described in Japanese Patent Application No. 2000-38.
No. 8000 (corresponding US patent application Ser. No. 09/7399)
No. 74, Applicant; Matsushita Electric Industrial Co., Ltd.). It has also been found that if the parameter satisfies the relationship of the following formulas (1) and (2), the curvature of the arc can be suppressed and the swing of the arc can be suppressed.
It is described in detail in Japanese Patent Application No. 2001-155385 (applicant; Matsushita Electric Industrial Co., Ltd.). These specifications are incorporated herein by reference.

Equations 1 and 2 showing the relationship between arc curvature suppression and arc fluctuation suppression for a mercury-free metal halide lamp are as follows.

0 <(100 BW / f) −P ₀ d <100 (Formula 1) 0 <(10 BW / f) −Pd <10 (Formula 2) Here, B (mT) is a pair of electrodes (3, The magnetic field (9) applied to the center between the electrode tips when the horizontal lighting is performed so that the straight line connecting the tips of 3) is substantially horizontal, and d (mm)
Is the distance between the tips of the pair of electrodes (3, 3), and P ₀
(MPa) is the pressure inside the arc tube 1 during steady lighting, W (W) is the power consumed during steady lighting,
F (Hz) is a stable frequency at the time of steady lighting. Note that P (MPa) in Equation 2 is a rare gas sealing pressure at 20 ° C.

The meaning of each term in the equations (1) and (2) will be briefly described. The term (100 BW / f) in the equation (1) and the equation (2)
The term (10 BW / f) in the equation is the term for the force that causes the arc generated by the magnetic field 9 to move downward, while the term P ₀ d in Equation 1 and Pd in Equation 2 are the values in the arc tube. Is the term for the force (buoyancy) that moves the arc upward due to the convection of the gas.

[0063] The operation than the pressure P _0, and that easily measured towards the filling pressure P of the rare gas, not an operational pressure P _0,
Since there is no particular problem even if the pressure is specified by the noble gas filling pressure P, the use of Equation 2 has a greater advantage in lamp design. In Equation 2, more preferable conditions are as follows. P is 0.1 (MPa) <P <2.5 (MP
a) is preferred. Also, P · d is P · d <
8 (more preferably, Pd ≦ 4.6). Further, f is preferably 40 (Hz) <f. B is preferably B <500 (mT). And d is preferably 2 <d (mm).

In a lamp having a small inner diameter of the arc tube 1 of, for example, 5 mm or less, the arc curvature greatly affects the life characteristics of the lamp. That is, the arc curvature causes an increase in the temperature of the upper portion of the arc tube 1, causing problems such as white turbidity of the quartz glass as the arc tube material, and as a result, the lamp life may be shortened. Therefore, the magnetic field 9
It is considered that suppressing the arc bending with the force is an effective means for improving the quality such as the life characteristics of the lamp. In addition, since the fluctuation of the arc causes flickering and is not preferable, suppressing the fluctuation of the arc leads to the improvement of the lamp characteristics.

Since the magnetic field 9 required to suppress the arc bending varies depending on the lamp design, it is preferable to apply a magnetic field 9 suitable for each lamp. However, if each parameter is defined so as to satisfy the relationship of the above equations 1 and 2, there is a great advantage since a lamp in which the arc bending and the arc swing can be easily designed without trial and error. As the magnetic field applying means 8, a permanent magnet (for example, a ferrite permanent magnet) is preferable because a magnetic field can be easily applied. Note that the magnetic field applying means 8 may be an electromagnet.

The magnetic field applying means 8 is used to suppress arc bending and arc fluctuation. By enclosing a halide of Ce in a mercury-free electrode type lamp, the arc width is reduced and the arc width is reduced. The effect of the present embodiment that high luminance is obtained can be obtained without using the magnetic field applying means 8. In addition, the effect that the arc width can be reduced by encapsulating a halide of Ce, a halide of Zn, a halide of Al, a halide of Sb, and indium bromide is also obtained by the magnetic field applying means 8. It can be obtained at least.

[0067]

According to the present invention, a mercury-free metal halide lamp having a narrow arc width is provided because a rare gas and a cerium halide are contained in an arc tube having a pair of opposed electrodes in the tube. be able to.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a configuration of an electrode-type metal halide lamp not containing mercury according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a configuration of an arc width / luminance measuring device.

FIG. 3 is a graph showing a brightness distribution of an arc.

FIG. 4 is a graph showing a relationship between an arc width of a lamp and a maximum luminance value.

FIG. 5 is a graph showing the relationship between lamp efficiency and voltage.

FIG. 6 is a graph showing the relationship between the total amount of scandium halide and sodium halide encapsulated and the luminous flux.

FIG. 7 is a graph showing the relationship between the amount of cerium halide sealed and the lamp voltage.

FIG. 8 is a graph showing the relationship between the amount of zinc halide enclosed and the lamp voltage.

FIG. 9 is a graph showing the relationship between the amount of halide of aluminum and the lamp voltage.

FIG. 10 is a graph showing the relationship between the amount of antimony halide enclosed and the lamp voltage.

FIG. 11 is a graph showing the relationship between the amount of indium bromide sealed and the lamp voltage.

FIG. 12 is a cross-sectional view schematically showing a configuration in which a magnetic field applying means 8 is provided in the mercury-free metal halide lamp of the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arc tube 2 Sealing part 3 Electrode 4 Molybdenum foil 5 Lead wire 7 Halide 8 Magnetic field applying means (permanent magnet) 9 Magnetic field 20 Lamp 21 Stabilizer and power supply 22 Filter 23 CCD camera 24 Monitor

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hideaki Kiryu 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor ▲ Yoshi ▼ Masato Ta 1006 Okadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Company F-term (reference) 5C015 QQ03 QQ14 QQ18 QQ52 QQ56 QQ58 QQ65 RR05 SS04

Claims (8)

[Claims] 1. An arc tube having a pair of electrodes facing each other in a tube, wherein the arc tube contains a rare gas and a cerium halide and does not contain mercury. Mercury metal halide lamp. 2. The mercury-free metal halide lamp according to claim 1, wherein the arc tube further contains at least one of a halide of scandium and a halide of sodium. 3. The total enclosed amount of the halide enclosed in the arc tube is a value per 1 cc volume of the arc tube,
3. The amount is not more than 30 mg / cc.
2. A mercury-free metal halide lamp according to item 1. 4. The mercury-free metal halide lamp according to claim 1, wherein the rated power of the mercury-free metal halide lamp is set to 25 W or more and 55 W or less. 5. The rare gas according to claim 1, wherein the rare gas contains at least Xe (xenon), and a sealing pressure of the rare gas is 0.1 MPa or more and 2.5 MPa or less at room temperature. A mercury-free metal halide lamp according to one of the above. 6. The mercury-free metal halide lamp according to claim 1, further comprising means for applying a magnetic field to said arc tube. 7. The mercury-free metal halide lamp according to claim 1, wherein the mercury-free metal halide lamp is a lamp for a point light source. 8. An arc tube having a pair of electrodes facing each other in a tube, wherein the arc tube contains a rare gas, a cerium halide, a zinc halide, an aluminum halide, an antimony halide, and A mercury-free metal halide lamp containing at least one selected from the group consisting of indium bromide and containing no mercury.