JPH07245084A - Metal halide lamp - Google Patents

Abstract

PURPOSE:To stabilize lighting and color temperature regardless of a lamp lighting direction by regulating an inner diameter, arc length between electrodes, mercury quantity, and lamp voltage of a metal halide lamp light emission tube of 1000W or more by a specific relational expression. CONSTITUTION:In a light emission tube 1 of quartz, main electrodes 2, 3 and an auxiliary electrode are sealed at both ends, and at least rare earth metal iodide is enclosed-inside with mercury and rare gas to be held in an outer bulb 6 through a pair of light emission tube support poles 7, 8. An inner diameter D of this tube l is set at 28-32mm, an arc length L between the electrodes is set at 74-95mm, a mercury concentration during lighting is set at 0.85-1.6mg/cc, and where mercury quantity is Mug, with a lamp voltage of V1V, their relation is regulated by an expression. Oscillation or color separation of arc, or bend of arc in the tube 1 can thus be restricted. Devitrification by temperature rise of quartz can be prevented, and a high rendering color of an average color rendering index of 90 or more can be maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal halide lamp having a high wattage of 1000 watts or more and a high color rendering property.

[0002]

2. Description of the Related Art High color rendering metal halide lamps are used for indoor lighting as lighting for stores such as department stores and restaurants, and their optical characteristics are highly evaluated. Further, a lamp having a higher color rendering property is required as a light source for illumination of an outdoor stadium or an indoor stadium. The average color rendering index (Ra) of the Sc-Na-based lamp as an arc tube additive is 65.
The color rendering property is not so high. So Dy-T
m-Ho and Dy-Tl lamps have been proposed. Similar to general lighting lamps, there are two types of lamps, a double-tube lamp in which the arc tube is housed in a T-shaped outer bulb, and a single-tube lamp in which only the arc tube is used without the outer bulb. It is used as a light source for stadiums and soccer fields.

However, the single-tube lamp is compact, and excellent optical characteristics such as high color rendering can be obtained by increasing the wall load of the arc tube, but the temperature of the arc tube rises and the working range of the lamp increases. It has the disadvantage of poor characteristics. That is, the luminous flux maintenance factor decreases due to devitrification of the arc tube, or a defect occurs due to leakage of the sealed portions at both ends of the arc tube, and the lamp life is reached in a short time. In addition, there is a problem that a burst due to a leak of the arc tube is likely to occur. Therefore, the maintenance cost is higher than that of the Sc-Na type lamp having the same lamp input.

Although the double-tube lamp loses its compactness, it has the advantage of being low in initial cost and maintenance cost because it can use existing lighting equipment and has a long life and high color rendering properties. . However, in this type of lamp, the lighting direction of the lamp (the mounting direction of the outer cap to the appliance) is often specified, and it is regulated, for example, horizontally ± 60 ° and cannot be lit in the vertical direction. This is because the arc in the arc tube is likely to undergo color separation up and down, and it becomes difficult to obtain uniform light and high color rendering. Further, when the lamp is lit vertically, the vibration of the arc becomes severe and it becomes difficult to realize a lamp that can be lit horizontally and vertically. This causes a problem in that an indoor stadium or the like is often illuminated from various directions, and thus it is not possible to use a lamp of this type having a high color rendering property.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and can be stably lit in any lamp lighting direction without arc fluctuation or arc bending of the arc tube over the life of the lamp. Another object of the present invention is to provide a metal halide lamp having a high tube input and a high color rendering type, which does not cause a change in color temperature due to color separation of arcs and the like. The inventor believes that the desired lamp can be obtained by suppressing the arc fluctuation and color separation of the arc tube during the vertical lighting and reducing the arc bending during the horizontal lighting, and the arc tube of the lamp is considered to be obtained. Among the specifications, paying attention to the five parameters of the inner diameter of the arc tube, the inner volume, the additive, the distance between the electrodes, and the mercury density, a comparative experiment was conducted to solve the above-mentioned problems.

[0006]

A metal halide lamp according to the present invention comprises at least a main electrode sealed at both ends of an arc tube and mercury and a rare gas, and at least an iodide of a rare earth metal enclosed therein. In a lamp having a tube input of 1000 W or more in which the tube is held in the outer bulb, the inner diameter (D) of the arc tube is 28 to 32 mm, the arc length (L) between the electrodes is 74 to 95 mm, and the mercury density during lighting. 0.85
When the amount of mercury is (M) mg and the lamp voltage is (Vl) V, 22 ≦ Vl (D ³ / ML).
It is characterized by defining ^1/2 ≤ 28.

[0007]

With the above structure, it is possible to suppress the arcing of the arc tube, the color separation in the arc tube, the arc bending, and the like. Further, due to the arc bending, the distance between the arc and quartz is shortened, and the devitrification phenomenon due to the temperature rise of quartz is not caused. And the average color rendering index (R
A high color rendering type lamp having a) of 90 or more is obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A metal halide lamp according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view of a metal halide lamp, in which reference numeral 1 is a quartz arc tube in which main electrodes 2, 3 and auxiliary electrode 4 are sealed at both ends, and dysprosium iodide (DyI ₃ ) and thallium iodide ( TlI), cesium iodide (CsI), mercury and argon gas are enclosed. A heat insulating film 5 made of fine particles such as zirconium oxide (ZrO ₂ ) is formed on the outer surface of the end of the arc tube 1. And, such an arc tube 1 has an outer bulb 6
It is held in the outer bulb 6 via a pair of arc tube columns 7 and 8 connected to the inner stem. Reference numeral 9 is a lead wire for electrically connecting the main electrode 2 and the auxiliary electrode 4, and 10 is an outer cap.

Next, the above five parameters will be described based on experimental results. Generally, when designing a metal halide lamp, the following empirical formula is accepted. Vl = K (ML / D ³ ) ^1/2 , where Vl: lamp voltage (V), M: mercury amount (mg),
L: arc length (mm), D: arc tube inner diameter (mm). At this time, K is a coefficient peculiar to the lamp.

Further, according to an experiment, a Dy-T of 150 W, which is a low wattage lamp with high color rendering property, manufactured by the applicant of the present invention.
Average color rendering index of 1-Cs type metal halide lamp (R
When the lamp constant (K) such that a) was 90 was calculated, the following arc tube design values were obtained. When the lamp voltage is 90 V and the amount of mercury is 10 mg, the inner diameter of the arc tube is 1.2.
cm, the arc length was 1.9 cm, and K = 24. Based on the above results, Vl = 120V, arc tube wall load is 1
Lamps of various designs regulated to 8 W / cm ² were prototyped. The design values are shown in Table 1. Each additive in the arc tube had DyI ₃ of 15 mg, TlI 5 mg, and CsI 5 mg, and the arc length was calculated from the wall surface load and the arc tube inner diameter.

[0011]

[Table 1]

Table 2 shows the characteristics when a metal halide lamp is constructed with such an arc tube specification and the tube input is 1500 W and the tube lighting is constant. According to Table 1 and Table 2, K ≧ 24
In order to satisfy the above condition, if the inner diameter of the arc tube is less than 28 mm, it cannot be realized by a general heat-retaining means such as forming a heat-retaining film at the end of the arc tube, and the heat must be kept excessively. If the temperature is excessively maintained, the arc becomes unstable and the arc tube is deformed due to the temperature rise.
In addition, when the inner diameter is 40 mm, the arc becomes unstable during lighting. This is because the amount of enclosed mercury was large and the influence of the convection phenomenon occurred.

Next, the influence of the mercury density was investigated. When the mercury density was 0.85 to 1.6 mg / cc, all of the mercury was evaporated during lighting, and the higher the density of the enclosed mercury, the more active the convection in the arc tube and the arc. This is because it causes instability such as bending and causes a change in color temperature depending on the lighting direction. That is, when the mercury density is 0.85 mg / cc or less, the convection during vertical lighting is inactive, the supply of the luminescent material to the arc discharge becomes insufficient, and the color temperature becomes high. Conversely, the mercury density is 1.6
If it is more than mg / cc, the color temperature during vertical lighting will drop.

As described above, the inner diameter of the arc tube is 28 to 32 mm and the mercury density is 0.8 according to the lamp characteristics when the lamp is vertically lit.
5-1.6 mg / cc can be selected. 2 and 3 show changes in the luminous flux value and the color temperature depending on the lighting posture at that time. According to FIGS. 2 and 3, the characteristic changes depending on the lighting posture characteristically depending on the specifications of the lamp. Therefore, the technical problem to be solved by the present invention is to reduce the change due to the lighting posture of the lamp, and the range is within ± 5% of the luminous flux,
The color temperature is defined to be within ± 10%. And
It can be seen from Tables 1 and 2 that the range corresponding to this may be 32 mm or less in arc tube inner diameter.

[0015]

[Table 2]

Although the Dy-Tl-Cs type lamp has been described in the above embodiment, a Dy-Tm-Ho type lamp filled with an iodide of another rare earth metal may be used. Also, a lamp with a tube input of 1500 W has been described, but 1000 W, 2000 W, 3000 W, etc.
Similar results were obtained with lamps of W or higher.

[0017]

As described above, in the metal halide lamp according to the present invention, regardless of the lighting posture such as vertical or horizontal lighting, arc sway of arc tube of arc tube of high watt and high color rendering lamp and arc instability such as arc bending. Not only can this be prevented, but also changes in the lamp characteristics due to changes in color temperature due to arc color separation, etc. can be prevented. or,
High color rendering can be maintained throughout the lifetime, which is a great advantage in applications such as sports lighting.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a metal halide lamp according to the present invention.

FIG. 2 is a characteristic diagram showing changes in luminous flux due to differences in lighting postures of lamps having different arc tube inner diameters.

FIG. 3 is a characteristic diagram showing changes in color temperature due to differences in lighting postures of lamps having different inner diameters of arc tubes.

[Explanation of symbols] 1 arc tube 2,3 main electrode 4 auxiliary electrode 5 heat insulating film 6 outer bulb 7,8 arc tube strut 9 lead wire 10 outer bulb cap

Claims (1)

[Claims] 1. A tube in which at least a main electrode is sealed at both ends of an arc tube, and at least a rare earth metal iodide is enclosed together with mercury and a rare gas, and the arc tube is held in an outer bulb. In a metal halide lamp with an input of 1000 W or more, the inner diameter (D) of the arc tube is 28 to 32 mm, the arc length (L) between the electrodes is 74 to 95 mm, and the mercury density during lighting is 0.85 to 1.6 mg / cc. And the amount of mercury (M)
The metal halide lamp is defined as 22 ≦ Vl (D ³ / ML) ^1/2 ≦ 28, where mg and the lamp voltage are (Vl) V.