JP2007273373A - Metal halide lamp and lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal halide lamp of high efficiency suppressing variation of lighting color. <P>SOLUTION: The metal halide lamp has an arc tube 8 formed of a light transmitting ceramic material comprising a main tube part 12 forming a discharge space and fine tube parts 14, 16 provided on both sides of the main tube part 12 and filled with rare gas and a halide inside, and a pair of electrodes 22, 24 having shaft parts 26, 28 supported to the fine tube parts 14, 16 and provided so that the tips face each other with a clearance in the discharge space. The main tube part 12 is provided with a swelling part 20 locally swelling in the middle in a direction of a tube axis 8X. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a metal halide lamp, and more particularly to a metal halide lamp using a translucent ceramic material for an arc tube.

  Conventionally, quartz glass has been the mainstream material used for arc tubes of metal halide lamps, but in recent years, materials using translucent ceramics have been put into practical use. Since the translucent ceramic has higher heat resistance than quartz glass, the metal halide lamp can be lit at a higher temperature, and the lamp characteristics such as color rendering properties are improved. In addition, the translucent ceramic can increase the load on the tube wall because it has less reaction with the metal halide, unlike quartz glass, so that higher efficiency can be obtained than when quartz glass is used.

In order to achieve further efficiency, Patent Document 1 discloses that a light emitting tube having a relatively elongated shape in which sodium halide (for example, NaI) and cerium halide (for example, CeI ₃ ) are sealed in a light emitting tube. There is disclosed a metal halide lamp that employs a tube (a shape such that (EL / D)> 5 where D is the inner diameter of a portion forming a discharge space in the arc tube and EL is the distance between electrodes).

In Patent Document 2, sodium halide (for example, NaI) and praseodymium halide (for example, PrI ₃ ) are enclosed in an arc tube, and a relatively elongated arc tube ((EL / D)> 4), a metal halide lamp adopting a shape such as 4 is disclosed.
According to the metal halide lamps of Patent Documents 1 and 2, since the portion constituting the discharge space in the arc tube is relatively elongated, sodium self-absorption is reduced, thereby realizing high efficiency.
JP 2000-501563 A JP 2003-229089 A

However, when the inventor of the present application actually manufactured and turned on the metal halide lamp described in Patent Document 1, it was recognized that the light color (color temperature) fluctuated drastically.
Accordingly, an object of the present invention is to provide a metal halide lamp that is highly efficient and suppresses fluctuations in light color. Moreover, an object of this invention is to provide the illuminating device provided with such a metal halide lamp.

  In order to achieve the above object, the metal halide lamp according to the present invention includes a main tube portion that forms a discharge space and narrow tube portions provided on both sides of the main tube portion, and contains a rare gas and a halide inside. A light emitting tube made of a translucent ceramic material, and a pair of electrodes that have a shaft portion supported by the narrow tube portion and are provided so that the tip portions face each other with a gap in the discharge space; The main pipe part has a bulging part that bulges locally in the middle of the pipe axis direction.

Further, the main portion other than the bulging portion has a substantially cylindrical shape as a whole. When the inner diameter of the cylindrical portion is DE and the distance between the pair of electrodes is EL, the main portion is It has a shape that satisfies the relationship of 3.5 ≦ (EL / DE).
Further, the bulging portion has a substantially circular cross section, and when the maximum inner diameter of the bulging portion is DC, the main pipe portion is 1.2 ≦ (DC / DE) ≦ 2. It is characterized by having a shape that satisfies the relationship of 0.

Further, when the length of the bulging portion in the tube axis direction is WC, the main tube portion has a shape satisfying a relationship of WC ≦ {(2/5) × EL}. To do.
Further, the halide is characterized in that at least one of cerium halide, praseodymium halide, and neodymium halide and sodium halide are encapsulated.

  In order to achieve the above object, a lighting device according to the present invention lights a lighting fixture, the metal halide lamp according to any one of claims 1 to 5 incorporated in the lighting fixture, and the metal halide lamp. And a ballast for making it happen.

  According to the metal halide lamp having the above structure, even when the main pipe is elongated for high efficiency, the coldest spot appears in the bulging portion. It becomes easy to aggregate to a part, and it becomes difficult to aggregate to a thin tube part. As a result, it is possible to suppress rapid evaporation of the liquefied halide in the narrow tube portion, which is presumed to be a cause of light color variation.

In the following, embodiments of the present invention will be described. Prior to the specific description thereof, the cause of light color fluctuations occurring in the metal halide lamp according to the prior art will be described.
FIG. 11 is a longitudinal sectional view showing a light emitting part 102 of a metal halide lamp according to the prior art.
As shown in FIG. 11, the light emitting unit 102 includes an arc tube 110 including a main tube portion 104 and thin tube portions 106 and 108 extending from both sides of the main tube portion 104.

The arc tube 110 is made of a light-transmitting polycrystalline alumina ceramic material having a heat resistance of about 1200 ° C.
The main tube portion 104 forms a discharge space, and the thin tube portions 106 and 108 support the shaft portions (tungsten electrode rods 116 and 118) of the tungsten electrodes 112 and 114 via lead wires 130 and 132 described later. The inner diameter D of the main pipe portion 104 is 5.2 [mm]. The arc tube 110 is filled with a predetermined amount of CeI ₃ , a luminescent material 120 made of a metal halide of NaI, mercury as a buffer gas, and argon as a starting assisting rare gas.

The tungsten electrodes 112 and 114 are composed of tungsten electrode rods 116 and 118 and tungsten coils 122 and 124 wound around one end side of the tungsten electrode rods 116 and 118. The distance (interelectrode distance) EL between the tip portions of the tungsten electrode 112 and the tungsten electrode 114 facing each other is 41.6 [mm].
In addition, in the portion of the tungsten electrode rods 116 and 118 that overlaps the thin tube portions 106 and 108, a space that is inevitably formed in the thin tube portions 106 and 108 (the tungsten electrode rods 116 and 118 and the inner peripheral surfaces of the thin tube portions 106 and 108). Molybdenum coils 126 and 128 are wound around as much as possible.

  One end portions of lead wires 130 and 132 thicker than the tungsten electrode rods 116 and 118 are joined to the other end portions of the tungsten electrode rods 116 and 118. The lead wires 130 and 132 are sealed and fixed to the narrow tube portions 106 and 108 with frit (ceramic cement) 134 and 136, and the arc tube 110 is hermetically sealed with the frit 134 and 136. The lead wires 130 and 132 are made of conductive cermet.

The light emitting unit 102 shown in FIG. 11 is housed in a vacuum outer tube bulb and is a completed metal halide lamp with a base attached to the outer tube bulb, but the illustration of the outer tube bulb and the base is omitted. To do. Here, the metal halide lamp having the light emitting unit 102 is referred to as a “comparative lamp”.
The inventor of the present application turns on the comparison lamp having the above configuration, measures the color temperature at intervals of 2 minutes for 10 hours (600 minutes) from the point when 100 hours have elapsed from the start of lighting, and changes the color temperature over time. investigated. At this time, the comparison lamp was held in a posture in which the tube axis 110X of the arc tube 110 was in the horizontal direction.

The survey results are shown in FIG. FIG. 12 is a graph in which the horizontal axis represents the elapsed time from the start of color temperature measurement (that is, 100 hours from the start of lighting), and the vertical axis represents the color temperature.
As is apparent from FIG. 12, it can be seen that the color temperature changes drastically in a short time.
The following values are obtained from the color temperature data on which the graph of FIG. 12 is based.
Average color temperature: 3851K, maximum color temperature: 4450K, minimum color temperature: 3342K, standard deviation σ: 238K
The inventor of the present application inferred the cause of the violent change in the color temperature through observation of a comparative lamp and the like as follows.

When the EL / D value is 8 (= 41.6 / 5.2) and has a relatively long main tube portion as in the test lamp, the coldest spot during lighting exists in the thin tube portion. Therefore, the metal iodide (CeI _{3 in} this example) encapsulated with sodium halide (in this case NaI) aggregates in the narrow tube part, and in some cases liquefies and adheres to the inner peripheral surface of the narrow tube part It seems to do.
Since the outer periphery of the molybdenum coil disposed in the narrow tube portion and the inner periphery of the thin tube portion are very close to each other, the liquefied metal iodide may come into contact with the molybdenum coil. The temperature of the molybdenum coil is very high compared to the temperature of the inner peripheral surface of the narrow tube (that is, the temperature of the liquefied metal iodide), and the end portion closer to the discharge space exceeds the boiling point of the metal iodide. It is at temperature. Therefore, the metal iodide contacting the end portion of the molybdenum coil rapidly evaporates (bumps) and spreads into the discharge space (in the main tube). As a result, it is considered that a drastic change in vapor pressure occurs and the color temperature changes suddenly.

Since the above-described aggregation of metal iodide in the narrow tube portion, adhesion to the inner peripheral surface of the thin tube portion, contact with the molybdenum coil, and evaporation are repeated in a short cycle, the color temperature as shown in FIG. We assumed that severe fluctuations would occur.
Therefore, the inventor of the present application makes the main pipe part relatively thick and short so that the coldest point exists in the lower part of the central part in the pipe axis direction of the main pipe part, and aggregates metal iodide in this part. As a result, it was confirmed that the color temperature was relatively stable as the above-mentioned comparative lamp did not show a drastic change in color temperature.

  Further, it was confirmed that even when the tube axis 110X of the arc tube 110 was held and lit in a vertical position, the color temperature was relatively stable, and the color temperature was relatively stable. This is presumably due to the following reasons. In the case of vertical lighting, the coldest spot appears in the lower narrow tube section. For this reason, it seems that metal iodide is liquefied and adheres to the inner periphery of the thin tube portion, but moves downward through the inner peripheral surface of the thin tube portion, so the liquefied metal iodide is close to the discharge space of the molybdenum coil. This is probably due to the low probability of contact with the end portion. In addition, it is conceivable that the liquefied metal iodide comes into contact with the end portion (that is, the lower end portion) far from the discharge space of the molybdenum coil, but the temperature of the lower end portion is the boiling point of the metal iodide. This is probably because the bumping as described above does not occur.

The inventor of the present application produced various metal halide lamps having different ratios (EL / D) of the interelectrode distance EL and the main pipe inner diameter D, and conducted the experiment by horizontally lighting them. (EL / D) <3 In the range of .5, the color temperature variation that seemed to be a problem was not recognized, but in the range of (EL / D) ≧ 3.5, the problematic color temperature variation was recognized.
In addition, when one, all, or any two of cerium halide, praseodymium halide, neodymium halide, or any two of them can be encapsulated as a halide, high luminous efficiency can be realized, but other halides are encapsulated In particular, it has been confirmed that the color temperature fluctuates significantly.

As described above, in order to suppress the variation in color temperature that occurs during horizontal lighting, the main section may be made thicker and shorter. However, if the thickness is shortened, the luminous efficiency will be reduced this time. This is because when sodium halide is encapsulated, sodium self-absorption increases.
Therefore, the inventor of the present application may make the main part elongated as a whole for high efficiency (the shape of the main part is set in the range of (EL / D) ≧ 3.5), We have created a metal halide lamp that is less likely to cause color temperature fluctuations.

Hereinafter, such a metal halide lamp will be described based on an embodiment with reference to the drawings.
(Embodiment 1)
FIG. 1 is a partially cutaway view of a metal halide lamp 2 according to Embodiment 1. FIG.
The metal halide lamp 2 has a rated lamp power of 250 [W] and a tube wall load of 32 [W / cm ² ].

As shown in FIG. 1, the metal halide lamp 2 has a structure in which a light emitting unit 10 having a light emitting tube 8 is housed in an outer tube bulb 6 provided with a base 4 (for example, E type). The outer tube valve 6 is made of hard glass, and the inside of the outer tube valve 6 is evacuated.
FIG. 2 is a longitudinal sectional view of the light emitting unit 10.
As shown in FIG. 2, the light emitting unit 10 includes a light emitting tube 8 including a main tube portion 12 and thin tube portions 14 and 16 extending from both sides of the main tube portion 12. Further, the main pipe portion 12 has a bulging portion 20 that bulges locally in the middle of the tube axis 8X direction. In addition, although it is the bulging part 20 when viewed from the outer peripheral side of the main pipe part 12, when viewed from the inner peripheral side of the main pipe part 20, it can also be regarded as a recessed part 20A that is locally recessed.

  The bulging portion 20 has a substantially spherical shape. Therefore, the cross section cut by a plane orthogonal to the tube axis 8X has a substantially circular shape, and the inner diameter DC (maximum inner diameter in the cross section) of the bulging portion 20 is 8.4 [mm]. . Moreover, the length (longest part length) WC in the tube axis 8X direction of the bulging part 20 is 8.8 [mm]. The purpose (effect) of providing the bulging portion 20 will be described later.

Parts other than the bulging part 20 in the main pipe part 12 have a substantially cylindrical shape as a whole. The inner diameter DE of the cylindrical part is 5.0 [mm], and the outer diameter is 6. 4 [mm].
The inner diameters of the thin tube portions 14 and 16 are 1.0 [mm], and the outer diameter is 3.2 [mm].
The arc tube 8 is formed of a light-transmitting polycrystalline alumina ceramic material (total transmittance of 96%) having a heat resistance of about 1200 ° C. The arc tube 8 can be manufactured by a known gel casting molding method or a casting molding method.

The main tube portion 12 forms a discharge space, and the thin tube portions 14 and 18 support the shaft portions (tungsten electrode rods 26 and 28) of the tungsten electrodes 22 and 24 via lead wires 40 and 42 described later.
The arc tube 8 is filled with a luminescent material 30 made of CeI ₃ , a metal halide of NaI, mercury as a buffer gas, and xenon as a start-up rare gas. In addition, CeI ₃ is enclosed in 5.0 mg, NaI is 10.0 mg, and mercury is 1.4 mg. Xenon is enclosed in an amount of 200 mbar.

  The tungsten electrodes 22, 24 are composed of tungsten electrode rods 26, 28 and tungsten coils 32, 34 wound around one end side of the tungsten electrode rods 26, 28. The diameters of the tungsten electrode rods 26 and 28 are 0.60 [mm], and the total length is 17.5 [mm]. The distance EL between the tip portions of the tungsten electrode 22 and the tungsten electrode 24 facing each other (interelectrode distance) EL is 40.0 [mm].

Further, the portion of the tungsten electrode rods 26, 28 that overlaps the thin tube portions 14, 26 has a space that is inevitably formed in the thin tube portions 14, 16 (the tungsten electrode rods 26, 28 and the inner peripheral surfaces of the thin tube portions 14, 16 Molybdenum coils 36 and 38 are wound around as much as possible.
One end portions of lead wires 40 and 42 that are thicker than the tungsten electrode rods 26 and 28 are joined to the other end portions of the tungsten electrode rods 26 and 28. The lead wires 40 and 42 are made of conductive cermet, have a diameter of 0.95 [mm], and a total length of 6.0 [mm]. The lead wires 40 and 42 are sealed and fixed to the narrow tube portions 14 and 16 with Dy ₂ O ₃ —Al ₂ O ₃ —SiO ₂ type frits 44 and 46, and the arc tube 8 is connected to the frit 44 and 46. Is hermetically sealed. The frits 44 and 46 penetrate from the end portions of the thin tube portions 14 and 16 to a depth of 5.0 [mm] (frit sealing length).

With respect to the metal halide lamp 2 (hereinafter referred to as “first embodiment lamp 2” with respect to the comparison lamp) having the above-described configuration, an experiment similar to the case of the comparison lamp is performed to investigate the variation in the color temperature. did.
The experimental results are shown in FIG.
Further, the following values are obtained from the color temperature data on which the graph of FIG. 3 is based.

Average color temperature: 3950K, maximum color temperature: 4274K, minimum color temperature: 3515K, standard deviation σ: 130K
From the experimental results, it can be seen that the standard deviation σ of the color temperature was 238 K in the comparative lamp, whereas the first example lamp 2 was 130 K, and the variation in the color temperature was suppressed.
This is because the coldest point appears in the bulging portion 20 by providing the bulging portion 20 that bulges locally in the middle of the tube axis 8X. As a result, it is considered that the metal iodide tends to aggregate on the inner periphery of the bulging portion 20 and is less likely to aggregate on the thin tube portions 14 and 16.

For the comparison lamp and the first embodiment lamp 2, the voltage [V], current [A], power [W], and total luminous flux [lm] measured after lighting for 15 minutes after aging for 100 hours from the start of lighting. FIG. 4 shows average values of luminous efficiency [lm / W], color temperature [Tc], Duv (deviation from black body locus × 1000), and average color rendering index [CRI]. As shown in FIG. 4, it can be seen that the first example lamp 2 is superior to the comparative lamp in terms of luminous efficiency.
(Embodiment 2)
FIG. 5 shows a longitudinal sectional view of the light emitting unit 50 in the metal halide lamp according to the second embodiment. The metal halide lamp according to the second embodiment has basically the same configuration as that of the metal halide lamp 2 according to the first embodiment except that the shape of the main tube portion in the arc tube is different. Therefore, in the figure of the metal halide lamp according to the second embodiment, the same components as those of the metal halide lamp 2 of the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The main tube portion 54 of the arc tube 52 has a bulging portion 56 that bulges locally in the middle of the tube axis 52X direction. The bulging portion 56 bulges in a trapezoidal shape in the longitudinal section. That is, the bulging portion 56 includes a cylindrical portion 56B having an inner diameter (DC) larger than a cylindrical portion (inner diameter DE portion) other than the bulging portion 56, and a tapered portion extending from the cylindrical portion 56B ( A frustoconical portion) 56C.

Here, the distance EL between the electrodes in the light emitting portion 50 is 40.0 [mm], the inner diameter DE of the main pipe portion 54 other than the bulging portion 56 is 5.0 [mm], and the outer diameter is 6.4 [mm]. mm], the maximum inner diameter DC of the bulging portion 56 is 8.4 [mm], and the length of the cylindrical portion 56B in the tube axis 52X direction is 4.0 [mm].
The metal halide lamp according to the second embodiment has a rated power of 250 [W] and a tube wall load of 31 [W / cm ² ].

With respect to the metal halide lamp according to the second embodiment having the above-described configuration (hereinafter also referred to as “second example lamp”), an experiment was conducted in the same manner as in the case of the comparative lamp, and the variation in the color temperature was investigated.
The experimental results are shown in FIG.
Further, the following values are obtained from the color temperature data that is the basis of the graph of FIG.

Average color temperature: 4287K, maximum color temperature: 4331K, minimum color temperature: 4225K, standard deviation σ: 23K
From the experimental results, it can be seen that the standard deviation σ of the color temperature was 238K for the comparative lamp, whereas it was 23K for the first example lamp 2, and the variation in the color temperature was suppressed.
For the comparative lamp and the second embodiment lamp, the voltage [V], the current [A], the power [W], the total luminous flux [lm], which were measured after lighting for 15 minutes after aging for 100 hours from the start of lighting, FIG. 7 shows average values of luminous efficiency [lm / W], color temperature [Tc], Duv (deviation from black body locus × 1000), and average color rendering index [CRI]. As shown in FIG. 7, it can be seen that the first example lamp 2 can achieve high luminous efficiency substantially equal to that of the comparative lamp which is excellent in luminous efficiency.

Although detailed data is omitted, the inventor of the present application has found a preferable relationship among the dimensions DC, DE, and WC of the arc tube in the metal halide lamp according to Embodiments 1 and 2 through experiments. The relationship will be described below.
(i) Relationship between the maximum inner diameter DC [mm] of the bulging portion and the inner diameter DE [mm] of the main pipe portion other than the bulging portion The main pipe portion is 1.2 ≦ (DC / DE) ≦ 2.0. It is preferable to have a shape that satisfies this relationship.

In the range of 1.2> (DC / DE), the coldest point does not appear in the bulging portion. In the range of (DC / DE)> 2.0, the coldest point appears in the bulging portion. This is because the temperature is excessively decreased, and as a result, the vapor pressure of the halide is greatly decreased, and the luminous efficiency is significantly decreased.
Therefore, in order to realize high luminous efficiency while suppressing variation in color temperature, the value of (DC / DE) is preferably in the above range.

(ii) Relationship between the length WC [mm] of the bulging portion in the tube axis direction and the interelectrode distance EL [mm] The main tube portion satisfies the relationship of WC ≦ {(2/5) × EL}. It is preferable to have a shape.
In the range of WC> {(2/5) × EL}, the arc is greatly curved upward and the temperature difference between the upper part and the lower part in the bulging part becomes large, and the arc tube may crack. It is.

  In the case of a conventional arc tube without a bulging portion, when the arc tube is lit horizontally, when the arc tube is viewed in a cross section, first, a temperature difference occurs between the upper and lower sides of the discharge space, which causes convection of the sealed gas. When viewed in the cross section, the convection occurs clockwise in the right half and counterclockwise in the left half. That is, since convection from the lower side to the upper side is generated in the middle portion in the left-right direction, the arc is pushed upward by the convection and curved upwards. Since the arc is a heat source, a considerable temperature difference occurs between the upper part of the arc tube approached by the arc and the lower part from which the arc moves away, and cracks occur. The degree of bending depends on the inner diameter of the arc tube. That is, when the inner diameter of the arc tube is small, the temperature difference between the upper and lower sides in the discharge space is small, and even if the arc is bent, it is suppressed by being suppressed by the tube wall. When is large, the reverse result is obtained, and cracks are likely to occur.

The above is the case of a conventional arc tube, but the inventors of the present application have found through experiments that the degree of arc curvature changes depending on the length of the WC when a bulging portion is provided. Thus, an appropriate range of WC and EL that can prevent the occurrence of cracks due to arc curvature was obtained.
That is, in order to prevent the occurrence of cracks, it is preferable that WC and EL have the above relationship. If the WC is too short, it becomes difficult to manufacture the arc tube, so it is practically preferable that the range is {(1/10) × EL} ≦ WC.

The arc tube may have a shape other than those described above, for example, as in the following modification.
The metal halide lamps according to the following modifications 1 and 2 have basically the same configuration as the metal halide lamp 2 according to the first embodiment except that the shape of the arc tube is different. Therefore, in the drawings of the metal halide lamps according to the first and second modifications, the same components as those of the metal halide lamp 2 of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
(Modification 1)
FIG. 8 is a longitudinal sectional view showing the light emitting unit 60 of the metal halide lamp according to the first modification.

The main tube portion 64 of the arc tube 62 has a bulging portion 66 that bulges locally in the middle of the tube axis 62X direction. The bulging portion 66 bulges in a cylindrical shape. That is, the bulging portion 66 has a shape protruding in a cylindrical shape having an inner diameter (DC) larger than a cylindrical portion (inner diameter DE portion) other than the bulging portion 66.
(Modification 2)
FIG. 9 is a longitudinal sectional view showing a light emitting unit 70 of the metal halide lamp according to the second modification.

The main tube portion 74 of the arc tube 72 has a bulging portion 76 that bulges locally in the middle of the tube axis 72X. The bulging portion 76 bulges in a cylindrical shape. That is, the bulging portion 76 has a shape protruding in a cylindrical shape having an inner diameter (DC) larger than a cylindrical portion (inner diameter DE portion) other than the bulging portion 76. However, the difference from Modification 1 is that, in Modification 1, the connecting portion between the bulging portion and the other main pipe portion, and the connecting portion between the main pipe portion and the thin tube portion are rounded smoothly. On the other hand, in the modified example 2, the connecting portion between the bulging portion 76 and the other main pipe portion 74 and the connecting portion between the main pipe portion 74 and the thin tube portions 77 and 78 are angular. is there.
(Embodiment 3)
FIG. 10 is a diagram showing a schematic configuration of the illumination device 80 according to the third embodiment.

  As shown in FIG. 10, the lighting device 80 includes a lighting fixture 84 attached to the vertical wall 82, a metal halide lamp 2 incorporated in the lighting fixture 84, and a ballast 86 for lighting the metal halide lamp 2. It should be noted that any of the metal halide lamps according to the first and second embodiments and the first and second modifications may be incorporated into the lighting fixture 84, but in this example, the first embodiment relates to the first embodiment.

  The lighting fixture 84 has a socket 88 for attaching the base 4 (FIG. 1) of the metal halide lamp 2, and the metal halide lamp 2 in the attached state has a longitudinal direction (a tube axis direction of the arc tube 8). It is held in a horizontal orientation. The lighting fixture 84 has a reflecting mirror 90 that reflects and collects light from the metal halide lamp 2 attached to the socket 88 in the horizontal direction. The reflecting mirror 90 has a trumpet-shaped inner surface, and the inner surface is mirror-finished or coated with white paint, and efficiently reflects light from the metal halide lamp 2.

As described above, the present invention has been described based on the embodiment. However, the present invention is not limited to the above-described form, and for example, the following form is also possible.
(1) In the above embodiment, the bulging portion is bulged over the entire circumference of the main pipe portion. However, the bulging portion is not limited to this and may be partially bulged. . For example, it can be a bulging portion bulged downwardly in a hemispherical shape. That is, in a horizontally lit metal halide lamp, if the main portion has a bulging portion that bulges at least downward locally in the middle of the tube axis direction, the coldest spot is located at the bulging portion. Thus, the object of the present invention can be achieved. Needless to say, the shape bulging downward is not limited to a hemispherical shape.
(2) In the above embodiment, the main pipe portion other than the bulging portion is formed in a substantially cylindrical shape, but is not limited to this, for example, a taper shape that gently expands from both ends toward the bulging portion. It may be formed in a taper shape that is gradually reduced from the bulging portion toward both ends. Or when it sees in a longitudinal cross section, you may form so that the shape which match | combined the main pipe part part of both sides of a bulging part may become a long ellipse shape as a whole (part).
(3) In the above embodiment, the main tube portion and the thin tube portion are integrally formed to constitute the arc tube. However, the present invention is not limited to this, and the main tube portion and the thin tube portion are separately formed. The arc tube may be formed by assembling. In other words, the arc tube may be formed by forming the outer diameter of the end portion of the narrow tube portion to be larger than the inner diameter of the end portion of the main tube portion and joining the end portions in a tight-fitting state by shrink fitting. .
(4) In the above embodiment, the present invention is applied to a metal halide lamp having a rated power of 250 [W]. However, the present invention is not limited to this, and 200 [W], 150 [W], Applicable to metal halide lamps with rated power of 100 [W] and 70 [W].
(5) In the above embodiment, the arc tube is filled with cerium halide together with sodium halide. However, the halide sealed together with sodium halide is not limited to this, and for example, the following configuration may be used. . It may be praseodymium halide or neodymium halide, or all of cerium halide, praseodymium halide, and neodymium halide, or any two of them.

  In other words, the arc tube only needs to contain sodium halide and at least one of cerium halide, praseodymium halide, and neodymium halide as a halide.

  In particular, the metal halide lamp according to the present invention can be suitably used as a light source of a lighting device that is required to have high efficiency and little light color fluctuation.

It is a figure which shows the metal halide lamp which concerns on Embodiment 1. FIG. It is a figure which shows the light emission part of the metal halide lamp which concerns on Embodiment 1. FIG. It is a figure which shows the experimental result of the light color (color temperature) fluctuation | variation in the metal halide lamp which concerns on Embodiment 1. FIG. It is the figure which compared the various characteristics of the metal halide lamp which concerns on Embodiment 1, and the metal halide lamp which concerns on a prior art. It is a figure which shows the light emission part of the metal halide lamp which concerns on Embodiment 2. FIG. It is a figure which shows the experimental result of the light color (color temperature) fluctuation | variation in the metal halide lamp which concerns on Embodiment 2. FIG. It is the figure which compared the various characteristics of the metal halide lamp which concerns on Embodiment 2, and the metal halide lamp which concerns on a prior art. It is a figure which shows the light emission part of the metal halide lamp which concerns on the modification 1. It is a figure which shows the light emission part of the metal halide lamp which concerns on the modification 2. It is a figure which shows the illuminating device which concerns on Embodiment 3. FIG. It is a figure which shows the light emission part of the metal halide lamp which concerns on a prior art. It is a figure which shows the experimental result of the light color (color temperature) fluctuation | variation in the metal halide lamp which concerns on a prior art.

Explanation of symbols

2 Metal halide lamp 8, 52, 62, 72 Arc tube 12, 54, 64, 74 Main tube portion 14, 16, 77, 78 Narrow tube portion 20, 56, 66, 76 Swelled portion 22, 24 Tungsten electrode 26, 28 Tungsten Electrode rod 80 Lighting device 84 Lighting fixture 86 Ballast

Claims (6)

An arc tube made of a translucent ceramic material, comprising a main tube portion that forms a discharge space and thin tube portions provided on both sides of the main tube portion, in which a rare gas and a halide are enclosed,
Having a shaft portion supported by the narrow tube portion, and having a pair of electrodes provided so that the tip portions face each other at an interval in the discharge space;
The metal halide lamp characterized in that the main pipe part has a bulging part that bulges locally in the middle in the axial direction of the pipe.   The main portion other than the bulging portion is generally cylindrical, and when the inner diameter of the cylindrical portion is DE and the distance between the pair of electrodes is EL, the main portion is 3 2. The metal halide lamp according to claim 1, wherein the metal halide lamp has a shape satisfying a relationship of 0.5 ≦ (EL / DE).   The bulging portion has a substantially circular cross section, and when the maximum inner diameter of the bulging portion is DC, the main pipe portion satisfies 1.2 ≦ (DC / DE) ≦ 2.0. The metal halide lamp according to claim 2, wherein the metal halide lamp has a shape that satisfies the relationship.   The main pipe part has a shape satisfying a relationship of WC ≦ {(2/5) × EL}, where WC is a length in the pipe axis direction of the bulging part. Item 4. A metal halide lamp according to item 2 or 3.   The halide according to any one of claims 1 to 4, wherein at least one of cerium halide, praseodymium halide, and neodymium halide and sodium halide are encapsulated as the halide. Metal halide lamp. Lighting equipment,
A metal halide lamp according to any one of claims 1 to 5, incorporated in the lighting fixture,
A ballast for lighting the metal halide lamp;
A lighting device comprising:

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