JPH09245729A - Arc tube for discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact arc tube for a discharge lamp with its superior color design and low power consumption, preferable for illumination such as a show window in a shop. SOLUTION: An arc tube for a discharge lamp having electrodes 23, 23 arranged opposite to each other in a sealed glass bulb and sealing Xe gas, mercury, and metal halogen compounds, SnI2 and SnBr2 in the glass bulb 22, in which the sealing quantity of SnI2 is within the range of 40 to 70wt.% against the total weight of SnI2 and SnBr2 to be sealed so as to enable the light flux maintenance rate of roughly 100% and a constant high color design property to be maintained over the long period of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc tube for a discharge lamp, and more particularly to an arc tube for a discharge lamp having a high color rendering and a relatively small power consumption suitable for show windows in stores and lighting for general households. Regarding

[0002]

2. Description of the Related Art Discharge lamps are widely used in outdoor facilities such as street lights and stadiums because they have good luminous efficiency and color rendering properties and have a longer life than filament type bulbs. As its structure, as shown in FIG. 11, a front lens b is engaged and integrated with a front opening of a glass reflector a on which a parabolic reflection surface a ₁ is formed to define a lamp chamber. And in this light room,
The arc tube c, which is the light source main body, has a structure in which its rear end is fixed to the rear top of the reflector a.

[0003] arc tube in the closed glass bulb c ₁ of c, the electrode d, e are oppositely arranged, from both ends of the arc tube c, the electrode d, lead f to conduct e, g is derived It is connected to power supply lines h and i. In the sealed glass bulb of the arc tube, an inert gas such as Ar or Xe,
Mercury and a metal halide are enclosed as a luminescent substance.

[0004]

However, even if the conventional discharge lamp is used as it is as a lamp for show window lighting in a store or for general household use, it is difficult to use because it is large and consumes a large amount of power. . on the other hand,
In the recent automobile headlamp industry, a discharge lamp device having a long life and high efficiency has been proposed as a light source of a headlamp. The inventor has long been engaged in the development of a discharge lamp device that can be used as a light source of a headlamp for an automobile, and has been proposing various discharge lamp devices that are compact and consume less power. By applying this technology, we thought that it would be possible to use discharge lamps for lighting in stores and ordinary homes, which was difficult to use in the past.

As a light source for an automobile headlamp, a Sc--Na system is used as a metal halide to be sealed from the viewpoints of high efficiency, relatively excellent color rendering properties, and a desirable color temperature of about 4200K. Is common. However, since the arc tube of a discharge lamp for general lighting has no limitation on color temperature and efficiency as in an automobile headlamp, the inventor of the present invention exhibits high color rendering properties as a metal halide to be encapsulated.
Attention was paid to n-type, especially SnI ₂ and SnBr ₂ . And
As a result of repeated experiments, it was found that it is effective to make SnI ₂ and SnBr ₂ to be enclosed in a predetermined weight ratio, and the present invention has been proposed.

The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is to provide a compact discharge lamp having excellent color rendering properties, which is suitable for illuminating a show window in a store and consumes less power. To provide an arc tube.

[0007]

In order to achieve the above-mentioned object, the present invention has electrodes facing each other in a hermetically sealed glass sphere, wherein the glass sphere contains Xe gas and mercury. Metal halides SnI ₂ and SnBr ₂
An arc tube for a discharge lamp, in which S
The enclosed amount of nI _2, and such that in the range of 40 to 70% by weight relative to the total weight of the encapsulated SnI ₂ and SnBr _2. The enclosed amount of SnI ₂ and the luminous flux value are inversely proportional to the total weight of metal halides (SnI ₂ and SnBr ₂ ),
If it is excessive (70 wt% or more), the luminous flux value is too low, and if the SnI ₂ encapsulation amount is too small (40 wt% or less) (SnBr ₂ encapsulation amount is large), it is more chemically active than I. The electrode is attacked by strong Br, and the durability is poor. Therefore, the amount of SnI ₂ sealed in the arc tube is such that an appropriate luminous flux value can be obtained as a light source for general illumination,
And as long as it is durable, SnI ₂ and SnB
40 to 70 wt% of the total weight of r ₂ is desirable. Also, the enclosed density of mercury is a parameter that determines the tube voltage. If it is too high, the tube voltage may become too high and the lamp may disappear. Can no longer be controlled. Therefore, the enclosed density of mercury is 1.5 × 10 ^{-2, which} is a tube voltage that does not extinguish and can be controlled by the lighting circuit.
The range of 2.3 × 10 ^-2 mg / μl is desirable. The encapsulation density of the metal halide (SnI ₂ , SnBr ₂ ) is
If the temperature is too high, the liquefied metal halide remains in the glass bulb during lighting and blocks light emission, or the color of the metal halide partially acts as a filter, and an appropriate luminescent color cannot be obtained. On the other hand, if it is too low, the desired luminous flux value and color rendering cannot be obtained. Therefore, metal halides (SnI ₂ ,
The SnBr ₂ ) encapsulation density is preferably in the range of 0.004 to 0.013 mg / μl as a range in which a luminous flux value and a color rendering property equal to or higher than a predetermined value are obtained and an appropriate light emitting property is obtained.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described based on examples. FIG. 1 shows a cross section of a discharge lamp according to a first embodiment of the present invention. In this figure, in the front opening of the glass-made substantially bowl-shaped reflector 10 having a parabolic light-reflecting surface that has been aluminum-deposited on its inner peripheral surface,
The glass front lens 12 is assembled and integrated to define the lamp chamber S of the discharge lamp. A bulb insertion hole 11 is formed in the rear top portion of the reflector 10, and a discharge bulb 20 is inserted and integrated in the bulb insertion hole 11 to form the electrode 2
The structure is such that the arc tube 21 that emits light by the arc discharge between 3 and 23 extends into the lamp chamber S.

The discharge bulb 20 has a structure in which an arc tube 21 extends forward from an insulative base 30 in which a ceramic disk 34 is joined and integrated with the front surface of a synthetic resin base body 32 which constitutes a bulb side connector. Power is supplied to the arc tube 21 through the lighting circuit side connector 40. That is, one of the electrodes 23, 23 in the closed glass bulb 22 of the arc tube 21 has a lead wire 23 a extending from the front end pinch seal portion of the arc tube 21.
Is connected to a lead support 25 penetrating the base body 30 in the front-back direction, and the lead support 25 is connected to a belt-shaped low-voltage side terminal 26 fixed to the base body 30. The other of the electrodes 23 is connected to a high voltage side terminal 27 fixed to the base body 30 via a lead wire 23b derived from a rear end pinch seal portion of the arc tube 21.

The sealed glass sphere 22 has an axial inner diameter of 7.
It is a substantially ellipsoid with 0 mm and an inner diameter of 3.2 mm in the direction orthogonal to the axis.
Its inner volume is 30 μl, and the distance between the electrodes 23 is 3.
8 mm. Xe gas as an inert gas and mercury and metal halides (SnI ₂ and SnBr ₂ ) as light emitting substances are enclosed in the closed glass bulb 22, and the enclosed density of mercury is 2.3 × 10 ⁻² mg / μl. Thus, the total weight of the enclosed metal halides SnI ₂ and SnBr ₂ is about 0.3 mg.

And the enclosed SnI_TwoAnd SnBr_Twoof
The ratio is SnI_Two: SnBr_Two= 31: 69% by weight
Tube A and SnI_Two: SnBr_Two= 45: 55
Weight% arc tube B and SnI_Two: SnBr_Two=
59: 41% by weight of three types of arc tube C prepared
Was. In addition to the arc tubes A, B and C, mercury
Encapsulation density of 2.8 × 10 ^-2SnI at mg / μl_TwoWhen
SnBr_TwoTube with a ratio of 30: 70% by weight
F, 46:54 wt% arc tube G, 63:
37% by weight arc tube H and SnI_Two= 0% (S
nBr_Two= 100%) of 4 types of arc tube I
I thought.

Sn in the arc tubes A to C
The total weight of I ₂ and SnBr ₂ is also about 0.3 mg. The initial characteristics of the tube voltage, luminous flux, color temperature, and average color rendering index Ra of the seven types of arcs A to C and F to I when the lighting power is 35 W. Is shown in FIGS. The characteristic values of the arc tubes A, B, C, and FI in FIGS. 2 to 5 are the characteristic values (tube voltage, luminous flux, luminous flux, etc.) indicated by about 10 arc tubes prepared for each specification. Color temperature and average color rendering index) are averaged values.

In FIG. 2, the enclosed density of mercury is 2.8 ×
10^-2In the arc tubes FI, which are mg / μl,
Encapsulation density of silver is 2.3 × 10^-2arc which is mg / μl
The tube voltage is higher than the tubes A, B, and C. High tube voltage
The tube voltage should be 100V because it may disappear.
It does not significantly exceed, and preferably 100 V or less. one
On the contrary, if the tube voltage is low, control by the lighting circuit
Since there is a possibility that it will be impossible, if possible, 85 V or more
desirable. Therefore, the enclosed density of mercury is 2.8 × 10.^-2m
2.3 × 10 than g / μl^-2mg / μl is preferred
1.5 × 10 ^-2mg / μl to 2.3 × 10^-2mg /
μl is most desirable.

In FIG. 3, the enclosed density of mercury is low (the enclosed amount of mercury is small relative to the inner volume of the arc tube).
The arc tubes A, B, and C have somewhat higher luminous flux values.
It is estimated that this is because the mercury partial pressure during lighting is relatively low and the metal halide partial pressure is relatively high. Further, it can be seen that the lower the mixing ratio of SnI ₂ (the higher the mixing ratio of SnBr ₂ ) is, the higher the luminous flux value is. That is, in FIG.
It is a characteristic diagram showing the relationship between the mixing ratio of nI ₂ and SnBr ₂ and the spectral distribution. From this figure, it can be seen that the mixing ratio of SnI ₂ is low (SnB
As the mixing ratio of r ₂ is higher), the peak value near 500 nm, which indicates the presence of mercury halide, becomes stronger.
Low nI ₂ mixing ratio (high SnBr ₂ mixing ratio)
It is estimated that the more mercury halide is formed, the higher the luminous flux value becomes.

The luminous flux value of the arc tube I is 1500.
It has a low lumen, which is insufficient as a light source for general lighting lamps. This is SnB that acts to increase the luminous flux value.
It is presumed that r ₂ was not encapsulated at all. In FIG. 4, the color temperature is somewhat higher in the lower mercury density (arc tubes A to C) than in the higher mercury density (arc tubes FI), but in each case, the target temperature is close to 5000K. Therefore, there is almost no effect of the mixing ratio of SnI ₂ and SnBr ₂ .

In FIG. 5, the average color rendering index Ra is irrespective of the amount of mercury density, and SnI ₂ and Sn
Irrespective of the mixing ratio of Br ₂ , it is stable at around 90 and there is no problem. 7 to 10 show that, in addition to the arc tubes A to C, the enclosed density of mercury is 2.3 × 10 ^-2 mg / μ.
1 and the ratio of SnI ₂ and SnBr ₂ is SnI ₂ : SnBr.
₂ = 0: 100% by weight of arc tube D and 100:
Working characteristics of a total of 5 types of arc tubes A to D including 0% by weight of arc tube E when a life test is performed in which the lighting power is set to 35 W (blinking once a day) The voltage, the luminous flux maintenance factor, the color temperature, and the average color rendering index Ra) are shown.

The arc tube D (n = 3) is 91,437,624 hours after the start of the lighting test, and the arc tube A (n = 3) is 387,439,584 hours.
Each electrode was damaged and could not be lit after that. It is presumed that this was because the electrode was eroded by Br, which had strong chemical activity. Further, the arc tubes B and C each had a broken electrode at 4000 hours after the start of lighting and could not be lit thereafter, but if it can be lit for 4000 hours continuously,
It is reasonably durable and can be used as a light source for general lighting.

FIG. 7 shows the tube voltage characteristic, and SnI ₂
The tube voltage of each of the arc tubes B, C, and E having a mixing ratio of 45, 59, and 100% is around 100 V, which can be said to be a range that can be used for general lighting lamps such as show windows. In particular, the arc tube C maintains 90 V to 100 V for up to 4000 hours and is particularly excellent. FIG. 8 shows the luminous flux maintenance factor characteristics of the arc tube B,
The luminous flux maintenance factor for both C and E is 90 to 100%
In particular, the luminous flux maintenance ratios of the arc tubes B and C are maintained at about 100% until 4000 hours have passed, which is very good.

However, the luminous flux value at the initial characteristic of the arc tube E is 1500-1600 according to the measurement by the inventors.
Lumen (not shown) and a luminous flux maintenance factor of 20
Before and after 00 hours, the luminous flux value of the arc tube B, C in the initial characteristics was 18% while it decreased to nearly 90%.
With a luminous flux value of 00 lumens (not shown), this luminous flux value is maintained as it is for a long time (until the elapse of 4000 hours), and the arc tubes B and C are optimal as the light source of the lamp for general illumination.

That is, with respect to the arc tube E, only SnI ₂ was used as the enclosed metal halide, and SnBr _{2 was used.}
Since the electrodes are not enclosed at all, it is difficult for the electrodes to erode.
Lighting is continued even after 00 hours have passed, and the durability is the most excellent, but since the luminous flux value is as low as 1500 to 1600 lumens, it becomes a very dark lamp. This is similar to the arc tube E in that the density of enclosed mercury (2.3 × 10 ⁻² mg / μl) is slightly different, but the luminous flux value of the arc tube I in which SnBr ₂ is not encapsulated at all is as shown in FIG.
As can be seen from the above, it is very low as 1500 lumens, which can be understood from the fact that the amount of light is insufficient as a light source of a lamp for general lighting.

FIG. 9 shows the color temperature characteristic, and SnI ₂
The lower the mixing ratio of (the higher the mixing ratio of SnBr ₂ ) is, the higher the color temperature is, but in any of the arc tubes B, C and E, the color temperature is around 5000 K, and the light source for general lighting lamps such as show windows. It becomes the range that can be used as. FIG.
0 indicates an average color rendering index (Ra) characteristic, and all Ras of the arc tubes B, C, and E remain stable at 90 to 95 for 4000 hours, which is very good.

[0022]

As is apparent from the above description, according to the present invention, power consumption is small, compact, and a luminous flux maintenance factor of approximately 100% and a constant high color rendering property can be maintained for a long period of time. It is possible to obtain an optimum arc tube as a light source for a general illumination lamp such as. Particularly, according to claim 2, stable lighting and proper light emission are guaranteed.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a discharge lamp according to an embodiment of the present invention.

FIG. 2 is a diagram showing the initial characteristics of the tube voltage of the arc tube according to the present invention.

FIG. 3 is a diagram showing initial characteristics of luminous flux of an arc tube according to the present invention.

FIG. 4 is a diagram showing initial characteristics of color temperature of the arc tube according to the present invention.

FIG. 5 is a diagram showing the initial characteristics of the average color rendering index of the arc tube according to the present invention.

FIG. 6 SnI ₂ and SnBr enclosed in an arc tube
Diagram showing the relationship between the mixture ratio of ₂ and the spectral distribution

FIG. 7 is a diagram showing the change over time in the tube voltage of the arc tube according to the present invention.

FIG. 8 is a diagram showing changes with time in the luminous flux maintenance factor of the arc tube according to the present invention.

FIG. 9 is a diagram showing changes with time in color temperature of the arc tube according to the present invention.

FIG. 10 is a diagram showing changes over time in the average color rendering index of the arc tube according to the present invention.

FIG. 11 is a vertical sectional view of a conventional discharge lamp.

[Explanation of symbols]

 21 Arc tube 22 Closed glass bulb 23 Electrode rod

Claims (2)

[Claims] 1. An Xe gas and mercury are provided in the glass sphere, the electrodes being oppositely installed in a sealed glass sphere.
An arc tube for a discharge lamp, in which SnI ₂ and SnBr ₂ which are metal halides are encapsulated.
An arc tube for a discharge lamp, wherein the amount of ₂ enclosed is within the range of 40 to 70 wt% with respect to the total weight of the enclosed SnI ₂ and SnBr ₂ . 2. The enclosed density of mercury is 1.5 × 10 ⁻² to
The arc tube for a discharge lamp according to claim 1, wherein the metal halide has an encapsulation density of 0.004 to 0.013 mg / μl at 2.3 × 10 ^-2 mg / μl.