JPS62200645A - Small-sized metal halide lamp - Google Patents

Abstract

PURPOSE:To prevent the generation of cataphoresis and reduce the color temperature without losing the quality of the color rendering property, by specifying the sealing amount of a metal halide including sodium halide sealed in a luminous tube. CONSTITUTION:The sealing amount of a metal halide including sodium halide sealed in a luminous tube 2 is made 20 to 90mg/cc. The vapor of the metal halide is distributed broadly in the bulb thereby, and, even at the anode 3 side which is not the coolest position, the metal halide exists to increase the vapor pressure of the itself. Therefore, the generation of cataphoresis is restricted, and the color temperature can be reduced less than 4,000K without losing the quality of the color rendering property.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention 1 (Industrial Application Field) The present invention relates to a small metal halide lamp for horizontal lighting that is operated by a power source such as direct current that does not have a four-dimensional reversal.

(Prior art) In recent years, from the perspective of energy conservation, the development of small metal vapor discharge lamps with excellent luminous efficiency, such as metal halide lamps, which can be used in place of incandescent bulbs with low luminous efficiency, has been actively promoted. ing.

These small metal vapor discharge lamps are usually operated via a ballast using a 100V or 200V general power supply with a commercial frequency of 50)-12 or 60H7, and the ballast is separate from the discharge lamp. The method used is to install it at a certain location.

However, when considering it as a replacement for incandescent light bulbs, which are often used indoors in general households and stores, it is essential that the lamp and ballast be integrated, and that the ballast be compact, lightweight, and inexpensive. be.

However, with ballasts using choke coils, which are currently common, it is difficult to meet the above conditions. In recent years, with the development of transistors, ICs, etc., it has become possible to construct an electronic circuit as a ballast that can satisfy the above conditions.

Possible methods for such electronic circuits include DC lighting and high-frequency lighting, but high-frequency lighting causes a phenomenon called acoustic resonance in a specific frequency band, which causes the arc to fluctuate and cause the lamp to go out. In particular, in the case of metal halide lamps, the frequency band in which acoustic resonance occurs is extremely wide due to the shape of the arc tube and the inclusions, making high-frequency lighting methods inappropriate. Therefore, especially for electronic ballasts for metal halide lamps, it is desirable to use a lighting system that uses a power source such as direct current that does not have polarity reversal.

On the other hand, when considering application to automobile headlights, portable floodlights, etc., the power source itself is DC, and for the same reason as above), as a ballast, lighting without reversing polarity such as DC is used. It is desirable to adopt this method.

Also, considering the lighting direction of the lamp, the height of the fixture can be made compact (especially effective for car headlights and floodlights).
It looks better when lit horizontally than at the mouth. If the lamp is mounted horizontally and installed in a floodlight, moving it up, down, left, or right will not actually change the lighting direction of the lamp unless it is tilted, so for metal halide lamps, the lamp's character changes depending on the lighting direction. It's a huge advantage.

For these reasons, in order to popularize metal halide lamps as a replacement for incandescent light bulbs, it is advantageous to use direct current and horizontal lighting.

(Problem to be Solved by the Invention) However, when a metal halide lamp is lit horizontally with direct current, the metal sealed as a metal halide (especially a light metal such as sodium Na) near the cathode emits strong light due to the cataphoresis phenomenon, while the anode A phenomenon occurs in which mercury luminescence becomes stronger in the vicinity. The reason why mercury emits light near the anode is because the pressure of mercury during lighting is high and mercury is less susceptible to the cataphoresis effect.

In general, in metal halide lamps, when the luminescence of the metal sealed as metal halide becomes stronger, the luminescence of mercury becomes weaker, but in the case of DC/horizontal lighting, even if the luminescence of the metal sealed as metal halide becomes strong, the luminescence of mercury still remains. must remain strong. Even if the vapor pressure of the metal halide is the same as in this case, the mercury emits more strongly under direct current/horizontal lighting, resulting in a higher color temperature.

Figure 3 shows the relationship between the color temperature and back color evaluation number Ra of a 35W class metal halide lamp in which scandium iodide and sodium iodide are filled as metal halides in arc tubes of approximately the same size, and the relationship between DC/horizontal lighting and AC. - This is a diagram comparing vertical lighting. It can be seen that for the same color temperature, DC/horizontal lighting has better Ra. This is because, as mentioned above, in DC/horizontal lighting, not only the metal sealed as metal halide but also mercury emits strong light.

Direct current/horizontal lighting has a great advantage in this way, but on the other hand, as mentioned above, it has the disadvantage that the color temperature becomes high at the same vapor pressure of the metal light as in alternating current/vertical lighting.

When considering a replacement for incandescent light bulbs, a high color temperature creates a strange feeling, so it is desirable to lower the color temperature.

The present invention has been made in consideration of the above circumstances, and has a color temperature that reduces the occurrence of cataphoresis when lit horizontally using a power source such as direct current that does not reverse polarity, and allows the color temperature to be replaced by an incandescent light bulb. The purpose of the present invention is to provide a small-sized metal halide lamp.

[Structure of the Invention] (Means for Solving the Problems) The present invention reduces the amount of metal halide containing sodium halide sealed in the arc tube to 20 m per unit volume.
'j/c, c ~90m! It is characterized by being J/c, c.

(Function) Conventionally, the metal halide was enclosed in less than 20m3/C,C, and the color temperature reached 4000 or more. 9
0m'J/c, metal halide vapor is now widely distributed in the valve, metal halide also exists on the anode side, which is not the coldest part, and the vapor pressure of the metal halide increases. Since the color temperature increases, the occurrence of cataphoresis phenomenon can be suppressed and the color temperature can be lowered to 4000 or less without impairing the color rendering quality.

(Embodiment of the Invention) The present invention will be described below based on an embodiment shown in FIGS. 1 and 2.

Figure 1 shows a small metal halide lamp of 35 watts (W> class), in which 1 is an outer tube and 2 is an arc tube.

The arc tube 2 has a bulb formed into an approximately elliptical sphere with a maximum inner diameter of 6 rnrn and a maximum varus of 8 #, and a positive electrode 3 and a cathode 4 with an inter-electrode distance of 5M are placed inside the bulb, facing each other. It is installed as follows.

The anode 3 and the cathode 4 are connected to lead wires 7a and 7 via molybdenum i5a and 6b that are hermetically sealed to the sealing parts 5a and 5b.
These lead wires 7a and 7b are connected to outer conductor wires 8a and 8b which also serve as navoto wires and which are passed through a part of the outer tube 1 in an airtight manner.

Inside the arc tube 2, argon gas is sealed at a predetermined pressure as a starting rare gas, and a predetermined amount of mercury is also sealed. In addition, as the metal halide, scandium iodide and sodium iodide were used at a ratio of 1:5, totaling 8
mg is included.

Since this arc tube 1 has an internal volume of 0.14 C.C, the metal halide is 57.1 my/unit volume.
c, c are enclosed.

A small metal halide lamp having such a configuration is connected to a power source such as a DC power source that does not have polarity reversal, and is used in a horizontal position with the lamp axis running in the horizontal direction.

When I turned on a lamp like this, the color temperature was about 330.
0K, and the average color rendering index Ra was about 74. The reason why we were able to lower the color temperature in this way is because we reduced the amount of scandium iodide and sodium iodide to 8 mg (57,1
This is because m'j/c, c).

The present inventors investigated the color temperature of the lamp having the above structure by varying the amount of iodide enclosed.

The results are shown in FIG.

As can be seen from FIG. 2, the color temperature decreases as the amount of iodide encapsulated increases. This is because when the amount of iodide is increased, the molten iodide is distributed over a wide range of the arc tube, meaning that iodide vapor also exists on the anode side, which is not the coldest part, and the vapor pressure of iodide as a whole increases. I'm there to increase. If the inclusion of iodide is increased, 13my, (90#l!?/c,
If it exceeds c), it will be too much for the volume of the arc tube, and the arc will tend to become unstable, and problems such as sudden changes due to vibrations and fading will occur, so it is desirable to set it to 13 #ICJ or less. Furthermore, if the amount of the lamp is reduced, the color temperature will rise, making it difficult to replace a light bulb, and furthermore, the characteristics of a metal halide lamp will not be utilized.

Therefore, the color temperature is below 4000 at 2.8 mg (20
/Jiff/c, c) That's all good.

From these experimental results, iodide has a concentration of 20m per unit volume.
It can be understood that it is sufficient to encapsulate it in the range of g/c, c to 90 mg/c, c.

In order to roughly check the validity of this matter, I conducted an experiment on a 100W class metal halide lamp and found that it is a good lamp if the iodide content is 2qm/C to 90m1/C,C. I was able to get 1q of characteristics.

In addition, since the power taphoresis phenomenon is easily affected by light metals, sufficient lamp characteristics as a metal halide lamp can be obtained by satisfying the above conditions when a metal halide lamp containing at least sodium iodide is operated with direct current and horizontally. I can do it.

In the above example, an example was shown in which sodium was used in the form of iodide as the sodium halide, but sodium may also be used in the form of at least one of chloride, bromide, or fluoride.

[Effects of the Invention] As explained above, according to the present invention, the metal halide is sealed in the 20//19. /c, c ~ g 0m3/C,
C, the vapor pressure of the metal halide, especially sodium halide, increases in the arc tube, causing it to split throughout the arc tube.
In addition to preventing the occurrence of cataphoresis, the color temperature can be lowered without impairing color rendering properties. Therefore, even if it is replaced with an incandescent light bulb, a light source that does not give any strange feeling can be obtained.

[Brief explanation of drawings]

Figures 1 and 2 show an embodiment of the present invention, Figure 1 is a cross-sectional view of a small metal halide lamp, Figure 2 is a characteristic diagram showing the relationship between the amount of iodide filled and color temperature, and Figure 3 is a characteristic diagram showing the relationship between color temperature and average light color evaluation number. 1... Outer tube, 2... Arc tube, 3... Anode, 4...
・Cathode applicant patent attorney Takehiko Suzue ml Figure

Claims (1)

[Claims] An anode and a cathode are sealed opposite to each other at both ends of an arc tube bulb,
A small metal halide lamp of 100 watts (W) or less, which has an arc tube filled with a starting rare gas, mercury, and a filler containing at least sodium halide, and is lit in a horizontal position by a power source that does not reverse polarity. In,
The amount of metal halide sealed in the arc tube was 20 mg/c. per unit volume. c~90mg/c. A small metal halide lamp characterized by c.