JP3175314B2 - Metal halide lamp - Google Patents

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 low wattage and excellent color characteristics.

[0002]

2. Description of the Related Art Conventionally, metal halide lamps have been used in various applications because of their high efficiency, high color rendering, and long life. In recent years, it has come to be widely used for lighting of indoor commercial facilities such as stores. In such applications, a lamp with low wattage and excellent color characteristics is required. In a metal halide lamp, when a combination of DyI ₃ , TlI, CsI, or the like is used as the enclosed iodide, depending on the design, a color temperature of about 3000 to 5000 K and an average color rendering index Ra of 90 or more can be obtained. It is becoming possible.

[0003]

By the way, Dy-Tl-Cs
When higher color rendering properties are desired in metal halide lamps, various conditions such as the inner volume of the arc tube, arc length, heat retention state, amount of additives, and ratio of additives are important. But more than 95 lamps could be obtained. As described above, in the lamp having Ra of 95 or more, the light emission is white light on or near the black body locus in the xy chromaticity coordinates.

However, in most conventional metal halide lamps, the average color rendering index Ra and the color temperature are described as color characteristics in catalogs and the like, and the color characteristics of the lamp are evaluated by the chromaticity point and the special color rendering index. It is not at present. In such a way of expressing color characteristics, for example,
Even if Ra is 90 or more and the color temperature is a desired value, if the chromaticity coordinates are located at points separated from the blackbody locus, the light source color will deviate from white, causing unnatural color tone and discomfort. Which results in In particular, in order to produce a Dy-Tl-Cs-based metal halide lamp having a color temperature of 4000 to 5000 K and Ra of 95 or more, the luminous bulb is exposed to a severe condition thermally during lighting. In addition, the above conditions require even higher precision, especially the additive ratio becomes delicate, its control is difficult, and the metal halide has a color characteristic such that the light source color on the black body locus stably during the lifetime. It is difficult to manufacture a lamp.

Japanese Patent Application Laid-Open No. 2-227956 discloses a method of obtaining a metal halide lamp having a low color temperature and a high color rendering by increasing the wall load of an arc tube to a relatively high value of 25 to 60 W / cm ^2. Is disclosed. But,
When the wall load is increased in this way, there is a problem that the life characteristics are not guaranteed, and further, the average color rendering index Ra is 90,
R ₉ of the special color rendering index is disadvantage that peaked at about 80.

The present invention has been made to solve the above-mentioned problems of the conventional metal halide lamp.
An object of the present invention is to provide a metal halide lamp having a long life and high color rendering properties, in which the average color rendering index Ra is 95 or more at a color temperature of 00K.

[0007]

In order to solve the above problems, the present invention provides an arc tube made of quartz glass, a hollow tube made of quartz glass disposed outside the arc tube, and In a Dy-Tl-Cs-based metal halide lamp composed of an arc tube and a hard glass outer tube arranged so as to surround a hollow tube, the arc length of the arc tube is 16 to 23 mm and the internal volume is 1.6. 22.5 cc, the wall load is 11.7-20 W / cm ^2, and the density of TlI sealed in the arc tube is 0.25-0.51 mg / cc.
And the ratio of the amount of DyI ₃ and TlI encapsulated, TlI / DyI ₃
It should be between 0.30 and 0.50.

In the metal halide lamp having the above-described structure, when the color temperature of 4000 to 5000 K is obtained when the filling density of TlI is set to 0.25 to 0.51 mg / cc, DyI ₃ and Tl
By setting the ratio of the enclosed amount of I to 0.30 to 0.50, the average color rendering index Ra can be 95 or more. By disposing a hollow tube around the arc tube, 11.7 to 20 W / cm ²
Since Ra can be 95 or more with the wall load of, a metal halide lamp with a long life and high color rendering can be realized.

[0009]

Next, an embodiment will be described. FIG. 1 is a view showing one embodiment of a metal halide lamp according to the present invention.
FIG. 2 is an enlarged view showing the arc tube. In the figure,
Reference numeral 1 denotes a 150 W quartz glass luminous tube having electrodes 2a and 2b provided at both ends thereof with an electrode spacing of 19 mm, an internal volume of 2.0 cc, and a wall load of 15 W / cm ^2. I have. And in the light-emitting tube, DyI ₃ 1.5mg, TlI0.6mg, CsI
0.5 mg, Hg 9 mg and argon 50 torr are enclosed. Numeral 3 is a quartz glass hollow tube arranged around the arc tube 1, and outer peripheral portions of upper and lower ends of the quartz hollow tube 3 are C-shaped holding bands 5a, 5b caulked to a stainless steel column 4. Supported by And the arc tube 1 and the hollow tube 3
Is incorporated in a hard glass T-shaped outer bulb 6 to constitute a metal halide lamp. In the drawing, reference numeral 7 denotes a curved portion of the column 4 arranged on the top side of the outer sphere 6, and reference numeral 8 denotes a barium getter.

When the metal halide lamp thus configured is operated at a rated lamp power of 150 W, the xy chromaticity coordinates are (0.365, 0.365), the color temperature is 4500 K, the average color rendering index Ra is 96, and the special color rendering index Ra is 96. Color rendering index Ri, that is, R _{9 to} R ₁₅
Was 90 or more, and a light source color on a black body locus was obtained.

The metal halide lamp according to the present invention is a lamp equipped with an arc tube, a hollow tube and an outer bulb in order to obtain desired excellent color characteristics of a color temperature of 4000 to 5000 K and Ra95 or more. Length 16 ~ 23mm, internal volume 1.6 ~
2.5 cc, sets the wall load 11.7~20W / cm ^2, the charging density of TlI enclosing the arc tube with a 0.25~0.51mg / cc, DyI ₃ and TlI the charging amount of the ratio TlI / DyI ₃ 0.30
Next, an experiment performed to define such a value will be described.

First, in order to solve the above-mentioned conventional problems, the chromaticity coordinates of the light emission of a Dy-Tl-Cs-based metal halide lamp are close to a black body locus and different from each other. About the actual lamp,
When the distance from the black body locus was large, it was found that when the emission of TlI was strong, the light was colored green, and when the emission of TlI was weak, the light was colored purple. Therefore, in order to solve the problem of departure from such a black body locus, it has been found that the color rendering of the lamp can be enhanced by appropriately adding the amount of TlI while securing an appropriate heat retaining state. . In other words, when the heat retention state is poor, there is no Dy-based light emission, and light emission due to TlI having a high vapor pressure becomes conspicuous.
The y coordinate shifts to a higher one. Further, if the TlI amount is unnecessarily large even when the heat retention state is good, the color rendering evaluation number cannot be increased because the y coordinate is largely separated from the blackbody locus even if the x coordinate is within the design range. Conversely,
If the amount of TlI is small, the y-coordinate is lower than the locus of the black body, and purple light is emitted. Then, the present inventor has proposed a DyI ₃ -TlI additive that contributes to light emission,
A trial experiment was conducted focusing on the conditions of wall load, internal volume, and arc length.

In the present invention, by providing a hollow tube made of quartz glass on the outside of the arc tube, the heat insulating effect provided by the heat insulating film provided at the end of the arc tube is supplemented. In the metal halide lamp having such a hollow tube, DyI ₃ and Tl were applied to an arc tube having an internal volume of 2.0 cc, an arc length of 19 mm, and a wall load of 15 W / cm ^2.
Lamps in which the amount of I was varied were prepared, and xy chromaticity coordinates were measured. The results shown in FIG. 3 were obtained. In the chromaticity diagram of FIG. 3, DyI ₃ curve a the enclosed amount i.e. charging density per volume of TlI as 0.5 mg / cc
Curve b shows the same TlI encapsulation density of 0.4 mg / cc, curve c shows the TlI encapsulation density of 0.3 mg / cc, and curve d shows the TlI encapsulation density. 0.2mg / c
c and curve e show the characteristics when the encapsulation density of TlI was 0.1 mg / cc.

From the characteristic curve of FIG. 3, it can be seen that the amount of DyI ₃ has the effect of changing the x value of the chromaticity point and the color temperature.
The amount of I has the effect of changing the y value of the chromaticity point. In FIG. 3, when the chromaticity point of the light source is located on the black body locus BBL, the light source is a high color rendering light source in an ideal state. For example, 4300
When designing a high color rendering metal halide lamp of K, referring to curve b, the amount of TlI to be filled is about 0.8 mg (filling density is about
0.4 mg / cc), when the required amount of DyI ₃ is charged and the required temperature is maintained, a light source located on the blackbody locus can be designed. It can also be seen that in order to obtain a high color rendering lamp having a color temperature of 4000 to 5000 K, the TlI enclosing density must be about 0.25 to 0.51 mg / cc.

[0015] Next, DyI ₃ enclosed amount ratio of the TlI alpha (DyI ₃
/ TlI) and the average color rendering index Ra were examined, and the result shown in FIG. 4 was obtained. This experiment was performed by setting the encapsulation density of DyI ₃ at 0.8 mg / cc and 1.2 mg / cc, and the data at 0.8 mg / cc was indicated by a circle.
The data in the case of 1.2 mg / cc is indicated by a triangle. As can be seen from these data, the change in the amount of DyI ₃
Does not significantly affect the ratio of DyI ₃ and TlI.
It can be seen that setting a value between 0.30 and 0.50 results in a lamp with a Ra of 95 or more.

Next, the relationship between the wall load and Ra was examined using the ratio of the amount of DyI ₃ and TlI as the parameter α, and the results shown in FIG. 5 were obtained. Since the metal halide lamp of the present invention has a hollow tube made of quartz glass around the arc tube, the metal halide lamp has higher heat insulation than a metal halide lamp in which only a normal heat insulation film is provided on the arc tube, and has a vapor pressure of DyI ₃ . Can be increased without increasing the wall load. Therefore, as shown in FIG.
With a wall load of about 0.4, the wall load was 12.5W /
cm ² or more, in the lamps which are about 0.3 to charging amount ratio alpha, when the wall load 11.7W / cm ² or more, it is possible to obtain the Ra95 or metal halide lamp.

By the way, when the wall load becomes 15 W / cm ² or more, the value of Ra becomes constant. And the wall load is 20W / cm
The lamps up to ² can withstand 6000 hours of operation, but when the wall load was increased to 25 W / cm ^2, lamps that could not be lit due to arc tube leakage in 1500 hours continued. Therefore, it was confirmed that the wall load was desirably set to 11.7 to 20 W / cm ² .

By the way, in a lamp having no hollow tube made of quartz glass, a luminescent color is stabilized to green at a wall load of 13 W / cm ² . In order to set the color temperature to 4300K in a lamp without such a hollow tube,
The wall load must be increased to 21 W / cm ² , and if the wall load is increased in this way, the short life of the lamp cannot be avoided as described above. Accordingly, in the metal halide lamp according to the present invention, the provision of the hollow tube made of quartz glass is extremely significant.
It is difficult to produce a DyI ₃ -TlI-CsI based metal halide lamp.

Based on the above experimental results, in the metal halide lamp according to the present invention, the wall load was 11.7 to less.
20 W / cm ² , TlI encapsulation density 0.25-0.51 mg / cc, DyI
The encapsulation ratio between DyI ₃ and TlI is set to 0.30 to 0.50. Next, the encapsulation density of DyI ₃ is set to 0.6 to 1.4 mg / cc,
Of 0.3 to 0.5 mg / cc, and the density of CsI of 0.3.
Create a lamp with 3-0.7 mg / cc and set the color temperature Tc
(K), average color rendering index Ra and special color rendering index Ri
Table 1 shows the measurement results of (R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , and R ₁₅ ). At this time, an arc tube having a wall load of 15 W / cm ² , an arc length of 19 mm, an internal volume of 2.0 cc and a rated lamp power of 150 W was used.

[0020]

[Table 1]

As can be seen from Table 1, all the lamps within the range of the filling density and the filling amount ratio of the additives specified in the present invention have a color temperature in the range of 4000 to 5000 K and an average color rendering index. Ra not only has a 95 or more, it can be seen that particularly in this type of metal halide lamp showing very difficult and is special color rendering index has R ₉ also 90 or more properties. FIG. 6 shows a spectral distribution diagram of a metal halide lamp (third stage in Table 1) showing characteristics of a color temperature of about 4400K.

The above-mentioned regulations regarding the additive encapsulation density, the encapsulation amount ratio and the wall load of the arc tube are as follows.
The metal halide lamp according to the present invention was set based on the results of an experiment conducted on a lamp with a rated lamp power of 150 W and a rated lamp power of 2.0 cc. It is specified in the range as follows. That is, the arc length
If it is less than 16 mm, the color rendering property tends to decrease, while if it exceeds 23 mm, the high temperature part of the electrode becomes closer to the end of the arc tube, a vigorous thermochemical reaction occurs, and the devitrification becomes remarkable. It is set to 16 to 23 mm. Regarding the inner volume of the arc tube, if the volume is less than 1.6 cc, the lamp voltage rises remarkably due to devitrification, and the color change becomes large.
When the ratio exceeds cc, the color rendering property decreases and the color temperature rises from a design value. Therefore, in the present invention, the internal volume is defined to be 1.6 to 2.5 cc.

[0023]

As described above, according to the present invention,
Since the wall load, the inner volume, the arc length of the arc tube, the encapsulation density of TlI added and the encapsulation ratio of DyI ₃ and TlI were set within appropriate ranges, the average color rendering index Ra was reduced.
95 or more, special color rendering index Ri of 90 or more, color temperature 4000 to 50
A long-life metal halide lamp having characteristics of 00K can be easily provided.

[Brief description of the drawings]

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

FIG. 2 is an enlarged view showing an arc tube in the embodiment shown in FIG.

FIG. 3 is a diagram showing a change in chromaticity coordinates when the encapsulation density of TlI and DyI ₃ is changed.

FIG. 4 shows the ratio α of DyI ₃ to TlI and the average color rendering index Ra.
FIG.

FIG. 5 is a diagram showing a relationship between a wall surface load of an arc tube and an average color rendering index Ra.

FIG. 6 is a diagram showing a spectral distribution of a metal halide lamp showing a color temperature of 4400K.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arc tube 2a, 2b Electrode 3 Hollow tube 4 Prop 5a, 5b Retaining band 6 Outer sphere 7 Curved part 8 Barium getter

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-63653 (JP, A) JP-A-61-250958 (JP, A) JP-A-3-171546 (JP, A) JP-A-2- 227956 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01J 61/12 H01J 61/30 H01J 61/34

Claims (1)

(57) [Claims] 1. An arc tube made of quartz glass, a hollow tube made of quartz glass arranged outside the arc tube, and an outer tube made of hard glass arranged so as to surround the arc tube and the hollow tube. In the Dy-Tl-Cs-based metal halide lamp, the arc length of the arc tube is 16 to 23 mm, and the inner volume is 1.6 to 23 mm.
2.5 cc, the wall load and 11.7~20W / cm ^2, the DyI ₃ and enclosed amount ratio TlI / DyI ₃ of TlI with a charging density of TlI sealed in the light emitting tube and 0.25~0.51mg / cc 0.30 ~ 0.
50, average color rendering index Ra of 95 or more, special color rendering index Ri
A metal halide lamp characterized by having a color temperature of at least 80 and a color temperature of 4000 to 5000K.