JP2000223069A - Metal halide lamp and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting system having a more enhanced luminous flux maintenance factor. SOLUTION: Blackening is prevented by growing a crystal grain by secondarily recrystallizing electrodes 21, 22, reducing proportion of sputtering even if it is heated by occurrence of an arc spot and reducing its adhesion to a tube wall. Since the crystal grain is big, thermal conductivity of the electrode axes 23, 24 is improved, and even if the electrode axes 23, 24 are heated by the arc spot, a temperature of the coolest part produced in the vicinity of the lower end of the electrode 22 gets high by raising the temperature of electrode coils 25, 26. The vapor pressure of mercury and a metal halide is raised and luminous efficiency is enhanced. If the scandium metal is filled, the scandium metal regresses to the electrodes 21, 22 during lighting, and thereby emission is improved and a light flux is 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 and a lighting device having an improved luminous flux maintenance ratio.

[0002]

2. Description of the Related Art Generally, metal halide lamps are characterized by high efficiency and high color rendering.

However, metal halide lamps have a lower luminous flux maintenance rate than other high pressure sodium lamps and mercury lamps. In particular, a metal halide lamp that can be turned on by a ballast for a mercury lamp has a luminous flux maintenance factor of about 50% at the end of its life, and improvement of the luminous flux maintenance factor is desired.

To improve the luminous flux maintenance factor, for example, a configuration described in Japanese Patent Application Laid-Open No. 5-283939 is known. JP-A-5-283039 describes a metal halide lamp in which a part of an electrode is secondarily recrystallized.

[0005]

However, in the case of the metal halide lamp described in JP-A-5-283039, the luminous flux maintenance factor can be sufficiently improved as compared with the conventional metal halide lamp, but it is equal to that of other high pressure discharge lamps. Further improvements are needed to reach 12,000 hours.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a metal halide lamp and a lighting device having a higher luminous flux maintenance ratio.

[0007]

According to a first aspect of the present invention, there is provided a metal halide lamp, comprising: an arc tube; a pair of electrodes of a secondary recrystallized refractory metal containing tungsten as a main component and disposed in the arc tube; With a rare gas, a metal halide, and one of scandium and a rare earth metal sealed in the tube, by not only secondary recrystallizing the electrode, but also sealing one of scandium and the rare earth metal, During the lighting, it is possible to prevent the electrode from being sputtered to lower the transmittance of the arc tube, and to improve the emission by returning either the scandium or the rare earth metal to the electrode, thereby further improving the luminous flux maintenance factor.

[0008] The metal halide lamp according to claim 2 is
2. The metal halide lamp according to claim 1, wherein when the inner volume of the arc tube is L [cc] and the amount of any of scandium and rare earth is M [mg], 0.004 ≦ 0.004 ≦
By satisfying M / L ≦ 0.1 and setting any of the amounts of scandium and rare earth to be within this range, the amount of scandium or rare earth returning to the electrode becomes an appropriate amount, and the luminous flux retention rate is increased. Is improved.

The metal halide lamp according to claim 3 is
In the metal halide lamp according to claim 1 or 2, the electrode is made of doped tungsten, so that the sputtering can be further prevented and the luminous flux maintenance rate is further improved.

A lighting device according to a fourth aspect of the present invention includes the metal halide lamp according to any one of the first to third aspects and a fixture main body to which the metal halide lamp is mounted, and has respective functions.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An illumination device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially cutaway side view showing a metal halide lamp, FIG. 2 is a perspective view showing the appearance of a lighting device, and FIG. 3 is a graph showing the relationship between the amount of scandium metal sealed and the luminous flux maintenance factor. is there.

As shown in FIG. 2, the illuminating device 1 is attached to, for example, a ceiling of a gymnasium or the like, and has a fixture main body 2, and the fixture main body 2 has a reflector 3 which is expanded downward. A lamp socket (not shown) is mounted on an upper portion of the reflector 3, and a metal halide lamp 11 having a power consumption of about 400 W as a metal halide lamp is detachably mounted on the lamp socket.

As shown in FIG. 1, the metal halide lamp 11 has a bulb-shaped outer tube 12 made of hard glass, and a base 13 is attached to a base end of the outer tube 12. Reference numeral 13 denotes an Edison type screw-type base having a shell 14 and an eyelet terminal 15.

A bulb as an arc tube is provided in the outer tube 12.
A bulb 16 is housed therein, and the bulb 16 is formed of transparent quartz glass. Sealing portions 17 and 18 are formed at both ends of the valve 16, respectively.
Is formed by crushing the end of the valve 16. At both ends of the bulb 16, secondary recrystallized doped tungsten electrodes 21 and 22 are provided. These electrodes 21 and 22 are configured by attaching electrode coils 25 and 26 to the tips of electrode shafts 23 and 24, respectively. Furthermore, the roots of the electrode shafts 23 and 24 are sealed with sealing portions 17 and 18, and are joined to metal foil conductors 27 and 28 made of a high melting point metal such as molybdenum in the sealing portions 17 and 18. The foil conductors 27, 28 are connected to external lead wires 31, 32.

A starting auxiliary electrode 33 is provided near the electrode 21.
The base of the starting auxiliary electrode 33 is also sealed to the sealing portion 17, and a metal foil conductor 34 such as molybdenum is sealed in the sealing portion 17.
The metal foil conductor 34 is connected to an external lead wire 35. A lighting start circuit 36 is connected to the external lead wire 35, and the lighting start circuit 36 is connected to the external lead wire 35 with a current limiting resistor R37, a normally closed bimetal switch 38, and a lighting tube 39.
Are connected in series and connected in parallel to the valve 16.

Incidentally, the secondary recrystallization of the electrodes 21 and 22 is performed by 10
^In a vacuum atmosphere of about ^-4 to 10 ^-5 Torr,
Crystal grains are grown and enlarged using a high-temperature vacuum processing method of heating at a temperature of about ° C. In addition, as the secondary recrystallization treatment, an argon plasma method,
A bombard method and a CO ₂ laser method may be used.

The bulb 16 has a longitudinal distance of 42 mm, an inner diameter of 20 mm, an internal volume of 14 cc, a metal halide of ScI ₃ + NaI of 30 mg, a scandium (Sc) metal of 0.1 to 0.5 mg, and,
Mercury and argon gas are sealed. That is, the amount of ScI ₃ + NaI enclosed by the metal halide is
0.004 ≦ 0.1 [mg /
cc].

Further, heat-resistant metal valve holders 41 and 42 are attached to the sealing portions 17 and 18 of the valve 16, respectively.
These bulb holders 41 and 42 are mechanically connected to conductive support wires 43 and 44 which are bent into a frame shape as an arc tube support, and the support wire 43 is formed on the base end side of the outer tube 12. It is fixed to the stem 45.

The external lead wire 31 of the bulb 16 is directly
The external lead wire 32 is connected to one of the shell 14 of the base 13 and the eyelet terminal 15 via a lead wire 46.

At the time of starting, the bimetal switch 38
Is closed, the voltage from the power supply is applied to the bulb 16, and the lighting tube 39 is opened and closed. A pulse voltage is generated by the operation of the lighting tube 39, and the pulse voltage is applied to the electrode 21.
An arc discharge is generated between the starting auxiliary electrode 33 and the
An arc discharge is generated between 21 and 22 to light up.

Further, according to the above embodiment, the electrodes 21 and
Since 22 is recrystallized secondarily and crystal grains are grown and enlarged, the rate of sputtering is reduced even when heated due to the generation of an arc spot during lighting, and tungsten adheres to the tube wall of the bulb 16. Is reduced, blackening is prevented, the luminous flux is prevented from being reduced early, and the luminous flux maintenance rate is improved. Note that doped tungsten has a greater effect than thoriated tungsten. Also,
The growth of the crystal grains by the secondary recrystallization improves the thermal conductivity of the electrode shafts 23 and 24. Therefore, even if the electrode shafts 23 and 24 are heated by the arc spot, the heat is quickly transferred to the electrode coils 25 and 24.
26, and raise the temperature of the electrode coils 25 and 26,
Due to the radiant heat from the electrode coils 25 and 26, the temperature of the coldest part generated near the lower end of the electrode 22 increases. As a result, the vapor pressure of the metal halide or mercury increases, and the luminous efficiency improves. Furthermore, by enclosing scandium metal,
It is considered that the scandium metal returns to the electrodes 21 and 22 during lighting to improve the emission and maintain the luminous flux.

Here, the experimental results of the relationship between the amount of scandium metal sealed and the luminous flux maintenance ratio will be described with reference to FIG.

As shown in FIG. 3, when the scandium metal is encapsulated, the luminous flux maintenance factor is higher than that of the conventional non-encapsulated one, and is reduced to 50% in about 8000 hours in the past. After the elapse of time, a luminous flux maintenance ratio of 80% or more could be obtained.

The content of scandium metal is as follows:
When the amount is less than 0.004 mg / cc, the amount of scandium metal returning to the electrodes 21 and 22 is small, and the improvement of the luminous flux maintenance ratio is small.
The deformation of 1, 22 becomes large, and similarly, the improvement of the luminous flux maintenance ratio is small.

[0026]

According to the metal halide lamp of the first aspect, not only is the electrode recrystallized, but also one of scandium and a rare earth metal is sealed, so that the electrode is sputtered during lighting and the arc tube is spun. In addition, it is possible to prevent the transmittance from lowering, and to improve the emission by returning either the scandium or the rare earth metal to the electrode, thereby further improving the luminous flux maintenance factor.

According to the metal halide lamp of the second aspect, in addition to the metal halide lamp of the first aspect, the inner volume of the arc tube is L [cc], and the enclosed amount of any of scandium and rare earth is M [mg]. When you do
Since 4 ≦ M / L ≦ 0.1, by setting the encapsulation amount of either scandium or rare earth within this range,
The return amount of either scandium or rare earth to the electrode becomes an appropriate amount, and the luminous flux maintenance factor can be improved.

According to the metal halide lamp of the third aspect, in addition to the metal halide lamp of the first or second aspect, since the electrode is made of doped tungsten, sputtering can be further prevented, and the luminous flux maintenance factor can be further improved.

According to the illuminating device of the fourth aspect, since the fixture body for mounting the metal halide lamp of any one of the first to third aspects is provided, each effect can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing the lighting device.

FIG. 3 is a graph showing the relationship between the amount of scandium metal enclosed and the luminous flux maintenance factor.

[Explanation of symbols]

2 Instrument body 11 Metal halide lamp as metal halide lamp 16 Bulb as arc tube 21, 22 electrode

Continued on the front page (72) Inventor Kazuo Takita 4-3-1 Higashishinagawa, Shinagawa-ku, Tokyo Toshiba Lighting & Technology Corporation (72) Inventor Hideki Ito 4-3-1 Higashishinagawa, Shinagawa-ku, Tokyo Toshiba Lighting & Technology Corporation In-house (72) Inventor Naoya Matsumoto 4-3-1 Higashi-Shinagawa, Shinagawa-ku, Tokyo Toshiba Lighting & Technology Corporation (72) Inventor Shinji Atago 4-3-1 Higashi-Shinagawa, Shinagawa-ku, Tokyo Toshiba Lighting Corporation (72) Inventor Hisanori Sano 4-3-1 Higashishinagawa, Shinagawa-ku, Tokyo F-term in Toshiba Lighting & Technology Corporation (reference) 5C015 JJ03 PP03

Claims (4)

[Claims] An arc tube; a pair of electrodes made of a secondary recrystallized refractory metal containing tungsten as a main component and disposed in the arc tube; a rare gas, a metal halide and a rare gas sealed in the arc tube; , A scandium or a rare earth metal. 2. The inner volume of the arc tube is L [cc], and the amount of any of scandium and rare earth is M [m
g], wherein 0.004 ≦ M / L ≦ 0.1. 3. The metal halide lamp according to claim 1, wherein the electrode is made of doped tungsten. 4. A lighting device comprising: the metal halide lamp according to claim 1; and a fixture main body to which the metal halide lamp is mounted.