JPH06290742A - Metal halide lamp - Google Patents

Abstract

PURPOSE:To provide a metal halide lamp with excellent illuminating color and low color temperature and life shortening of which is preventable. CONSTITUTION:Regarding a metal halide lamp having a light emitting tube 12, the insides of terminal tubular parts 132, 134 in which electrodes 136, 138 are arranged are formed in an approximate cylindrical shape. The input electric power P (W) of the metal halide lamp, the inner length (l) (mm) of the terminal tubular parts 132, 134, the maximum inner diameter S (mm), and the distance D (mm) from the upper ends of the electrodes 136, 138 to the closed ends of the sealed parts of the terminal tubular parts 132, 134 are set to have the following relations: 1.5XD>=1>=0.5XD and P/(lXS)>=5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of color rendering properties and reduction of color temperature of metal halide lamps.

[0002]

2. Description of the Related Art Metal halide lamps are known as highly efficient and economical lamps. In recent years, since this metal halide lamp is used for indoor lighting in stores,
Compactness and high color rendering are required. Also, for indoor use, it is preferable to use one that creates a calm atmosphere, so one with a low color temperature (5000K or less).
Is required.

In order to achieve high color rendering and low color temperature, it is necessary to increase the vapor pressure of the metal halide enclosed inside the arc tube. In conventional metal halide lamps, the central part of the arc tube is spherical, spheroidal, or narrow with both ends narrowed down to activate vapor convection in the arc tube and thereby cool the arc tube. By increasing the temperature of the part to increase the vapor pressure of the metal halide, and by decreasing the internal capacity of the arc tube and increasing the load (W / cm ² ) per unit area (1 cm ² ) of the internal wall surface, the arc tube A method of increasing the vapor pressure of the metal halide by increasing the temperature of the coldest portion, or a method of increasing the vapor pressure of the metal halide by increasing the amount of the metal halide enclosed has been adopted.

[0004]

However, even if the central part of the arc tube is formed in a spherical shape, a spheroidal shape, or a narrow shape, it is the coldest part of the arc tube and is hardly affected by the arc during lighting. It is not effective in raising the temperature around the electrodes. Also, the unit area of the inner wall surface (1 cm ² )
In the method of increasing the load (W / cm ² ) per hit to raise the temperature of the coldest part of the arc tube, an excessively heated portion was generated inside the arc tube, and this portion was encapsulated with quartz forming the arc tube. The reaction with the metal halide causes white turbidity on the inner wall surface, and the enclosed amount of the metal halide is reduced to change the light output characteristics of the metal halide lamp, which may shorten the life of the metal halide lamp. . Further, there is a limit to increasing the vapor pressure of the metal halide only by increasing the amount of the metal halide enclosed without increasing the temperature of the coldest part of the arc tube.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a metal halide lamp which has a high color rendering property, a low color temperature, and can prevent shortening of life.

[0006]

In order to achieve the above object, a metal halide lamp according to the invention of claim 1 is a metal halide lamp having an arc tube in which a metal halide is enclosed together with mercury and an inert gas. The inside of the end tubular portion where the electrode of the arc tube is arranged is formed into a substantially cylindrical shape, and the input power of the metal halide lamp is set to P
(W), the inner length of the end tubular portion is 1 (mm), the maximum inner diameter of the end tubular portion is S (mm), the upper end of the electrode is the closed end of the sealing portion of the end tubular portion. The distance to D (m
m), 1.5 × D ≧ l ≧ 0.5 × D,
Further, it is characterized in that P / (l × S) ≧ 5.

According to a second aspect of the invention, in the metal halide lamp according to the first aspect of the invention, the central portion of the arc tube is formed in a spherical shape, a spheroidal shape, or a narrow shape in which both ends are tapered. It is characterized by.

A metal halide lamp according to a third aspect of the present invention is the metal halide lamp according to the first or second aspect, wherein the metal halide is at least one iodide of Dy, Tl, In, Cs and an alkali metal. It is characterized by that.

[0009]

As described above, in order to achieve high color rendering and low color temperature, the vapor pressure of the metal halide enclosed inside the arc tube is raised by raising the temperature of the electrode peripheral part, which is the coldest part of the arc tube. It is effective to increase. On the other hand, in order to prevent the change of the light output characteristics of the metal halide lamp and prevent the shortening of the life, it is necessary to prevent the excessive heating of the inside of the arc tube.

The present inventor has made a metal halide lamp having a light emitting tube in which a metal halide is enclosed together with mercury and an inert gas, and the inside of the end tubular portion where the electrode of the light emitting tube is arranged has a substantially cylindrical shape. And the input power of the metal halide lamp is P (W), the inner length of the end tubular portion is 1 (mm), the maximum inner diameter of the end tubular portion is S (mm), and the upper end of the electrode is When the distance to the closed end of the sealing portion of the end tubular portion is D (mm), 1.5
By configuring such that xD ≧ l ≧ 0.5 × D and P / (l × S) ≧ 5, the arc tube maximum can be formed without causing an excessively heated portion inside the arc tube. It was found that the temperature around the electrode, which is the cold part, can be increased. As a result, it has been possible to realize a metal halide lamp that has a high color rendering, a low color temperature, and can prevent the life from being shortened.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic structural diagram of a metal halide lamp which is an embodiment of the present invention. Figure 2
It is a schematic sectional drawing of the arc tube of the metal halide lamp shown in FIG. FIG. 3 is a schematic enlarged view of part A of the arc tube shown in FIG. FIG. 4 is a diagram showing the relationship between the internal length l (mm) of the end tubular portion of the arc tube of the metal halide lamp shown in FIG. 1, the color temperature, and the color rendering index.

The metal halide lamp 1 shown in FIG. 1 has an arc tube 12 having heat insulating films 126 and 128 applied to the outer walls of both ends, a quartz tube 14 surrounding the arc tube 12, and an arc tube column supporting the arc tube 12. 162, 164 and arc tube support 16
2 is provided with annular support members 166 and 168 for supporting the quartz tube 14, getters 182 and 184, an outer bulb 20 for accommodating the arc tube 12, the quartz tube 14 and the like, and a base 22. To be done.

The arc tube 12 and the quartz tube 14 are made of quartz glass which is a light-transmitting heat-resistant glass. The arc tube columns 162 and 164 are made of a conductor and support the arc tube 12 and the arc tube lead 1 is attached to the arc tube 12.
It serves to supply electric power via 22, 124.

Further, the arc tube 12 is, as shown in FIG.
A central portion 142 in which DyI ₃ , TlI, and CsI are enclosed together with mercury and argon, end tubular portions 132 and 134 having a substantially cylindrical inside, and end tubular portions 132,
It has a pair of electrodes 136 and 138 arranged in 134. Both ends of the central portion 142 are tapered and formed. The electrodes 136 and 138 are connected to the arc tube leads 122 and 124, respectively. Incidentally, FIG.
[Fig. 3] is a schematic enlarged view of a portion A shown in Fig. 2.

In the metal halide lamp 1 having the above structure, the input power P is 150 (W), the maximum inner diameter M of the central portion 142 is 12 (mm), and the tubular portions 132 and 134 are sealed from the upper ends of the electrodes 136 and 138. The distance D to the closed end of the part is 4 (mm), and the distance t between the electrodes 136 and 138 is 20 (m).
m) and the internal length l of the end tubular portions 132 and 134
The color temperature Tc and the average color rendering index Ra of the metal halide lamp 1 when (mm) was changed were examined.

The results are shown in FIG. When l becomes large, R
Since a is high and Tc is low, the characteristics required for indoor lighting (Tc ≦ 5000K, Ra ≧
It was found that l must be 2 (mm) or more to satisfy 87). Incidentally, l must be 1.5 × D (mm) or less due to manufacturing problems.

When the relationship between l and D was examined based on the above results, it was found that 1.5 × D ≧ l ≧ 0.5 × D (mm).

In the present embodiment, the so-called narrow arc tube 12 formed by narrowing both ends of the central portion 142 into a tapered shape was used, but the central portion is formed into a spherical or spheroidal shape. The same result was obtained even if it was a thing.

Another embodiment of the present invention is shown in FIGS.
Will be described with reference to. FIG. 5 is a schematic structural diagram of a metal halide lamp which is another embodiment of the present invention. Figure 6
It is a figure which shows the relationship between the input electric power per unit area of the end tubular part of the arc tube of the metal halide lamp shown in FIG. 5, and color temperature and a color rendering index. In the metal halide lamp 3 shown in FIG. 5, those having the same functions as those shown in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

The metal halide lamp 3 shown in FIG. 5 is shown in FIG.
The difference from the metal halide lamp 1 shown in is the arc tube 3
The second central portion 322 is formed in a spherical shape.

In the metal halide lamp 3 having the above structure, the input power P is 100 (W), the maximum inner diameter M of the central portion 322 is 12 (mm), and the tubular portions 132 and 134 from the upper ends of the electrodes 136 and 138 are sealed. The distance D to the closed end is 3 (mm), and the distance t between the electrodes 136 and 138 is 20 (m).
m), the internal length l of the end tubular portions 132 and 134 is set to 3
(Mm) and the maximum inner diameter S of the tubular end portions 132, 134
The relationship between P / (l × S), the color temperature Tc of the metal halide lamp 3, and the average color rendering index Ra was examined when the value was changed.

The results are shown in FIG. When S is small, that is, P / (l × S) is large, Ra is high and Tc is low, which satisfies the characteristics (Tc ≦ 5000K, Ra ≧ 87) required for indoor lighting. It has been found that P / (l × S) must be 5 (W / mm ² ) or more in order to be satisfied. Incidentally, S is the end tubular portion 13
Since the electrodes 136 and 138 are arranged inside the electrodes 2,134, they must be larger than the maximum outer diameters of the electrodes 136 and 138.

In this embodiment, the arc tube 32 having the central portion 322 formed in a spherical shape is used, but the central portion is formed in a spheroidal shape or a so-called narrow shape in which both end portions are tapered. The same result was obtained.

From the results of the above embodiments, 1.5 × D ≧
By setting l ≧ 0.5 × D and P / (l × S) ≧ 5, the electrode peripheral portion, which is the coldest portion of the arc tube, does not generate an excessively heated portion inside the arc tube. It is possible to raise the temperature, which results in high color rendering, low color temperature,
Moreover, they have found that it is possible to realize a metal halide lamp that can prevent shortening of life. This is because the electrode, which is the coldest part of the arc tube, is placed inside the end tubular portion, and the inner dimensions of the end tubular portion are controlled as described above, so that only the inner wall surface around the electrode has a unit area (1c).
m ²⁾ because it was possible to increase the load per (W / cm ^2).

In each of the above embodiments, mercury is
Although an arc tube in which DyI ₃ , TlI, and CsI are enclosed together with argon is used, the present invention is not limited to this, and mercury, argon, InI, TlI, and TmI metal iodides or DyI ₃ , TlI, and NaI are used in the central portion. Similar effects can be obtained as long as a metal halide of an alkali metal such as

[0026]

As described above, according to the first aspect of the invention, in the metal halide lamp having the arc tube in which the metal halide is enclosed together with mercury and the inert gas, the electrodes of the arc tube are arranged. The inside of the end tubular portion is formed in a substantially cylindrical shape, the input power of the metal halide lamp is P (W), and the inside length of the end tubular portion is l.
(Mm), the maximum inner diameter of the end tubular portion is S (mm), and the distance from the upper end of the electrode to the closed end of the sealing portion of the end tubular portion is D (mm), 1.5 × D ≧ l ≧ 0.
By configuring 5 × D and P / (l × S) ≧ 5, the electrode peripheral portion, which is the coldest portion of the arc tube, does not generate an excessively heated portion inside the arc tube. It is possible to provide a metal halide lamp having a high color rendering property, a low color temperature, and preventing the life from being shortened.

According to a second aspect of the present invention, in the first aspect of the invention, the central portion of the arc tube is formed in a spherical shape, a spheroidal shape, or a narrow shape in which both ends are tapered. The present invention can provide a metal halide lamp having the same effect as that of the invention described in claim 1.

According to the invention of claim 3, in the invention of claim 1 or 2, the metal halide is D
It is characterized in that it is at least one kind of iodide among y, Tl, In, Cs and alkali metals, and it is possible to provide a metal halide lamp having the same effect as that of the invention according to claim 1.

[Brief description of drawings]

FIG. 1 is a schematic structural diagram of a metal halide lamp that is an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of an arc tube of the metal halide lamp shown in FIG.

FIG. 3 is a schematic enlarged view of a portion A of the arc tube shown in FIG.

4 is a diagram showing the relationship between the internal length l (mm) of the end tubular portion of the arc tube of the metal halide lamp shown in FIG. 1, the color temperature, and the color rendering index.

FIG. 5 is a schematic structural diagram of a metal halide lamp which is another embodiment of the present invention.

6 is a diagram showing the relationship between the internal length l (mm) of the end tubular portion of the arc tube of the metal halide lamp shown in FIG. 5, and the color temperature and color rendering index.

[Explanation of symbols]

 1,3 Metal halide lamp 12,32 Arc tube 14 Quartz tube 20 Outer bulb 22 Base 122,124 Arc tube lead 126,128 Thermal insulation film 132,134 End tubular part 136,138 Electrode 142,322 Central part 162,164 Arc tube Support 166,168 Support member 182,184 Getter

Claims (3)

[Claims] 1. In a metal halide lamp having an arc tube in which a metal halide is enclosed together with mercury and an inert gas, an end tubular portion in which an electrode of the arc tube is arranged is formed into a substantially cylindrical shape, The input power of the metal halide lamp is P (W), the inner length of the end tubular portion is 1 (mm), and the maximum inner diameter of the end tubular portion is S (m).
m), where the distance from the upper end of the electrode to the closed end of the sealing portion of the end tubular portion is D (mm), 1.5 × D ≧
A metal halide lamp characterized in that l ≧ 0.5 × D and P / (l × S) ≧ 5. 2. The metal halide lamp according to claim 1, wherein a central portion of the arc tube is formed in a spherical shape, a spheroidal shape, or a narrow shape in which both end portions are tapered. 3. The metal halide is Dy, Tl,
The metal halide lamp according to claim 1 or 2, wherein the metal halide lamp is at least one iodide of In, Cs and alkali metals.