JPS5859551A - Metal halide lamp - Google Patents

Abstract

PURPOSE:To obtain a metal halide lamp, which has a high luminous-flux maintenance rate and causes no flickerings and no light suppressions, by preparing an outer coil from a double or triple complex-wire, and preparing an inner coil by winding a simple wire in one layer or two layers. CONSTITUTION:A double or triple coil is used in preparing an outer coil 1. The end of the coil 1 dosen't touch an electrode core bar 3, and surrounds an inner coil 2 so that a hollow part is formed between the bar 3 and the end of the coil 1. Since a double or triple complex-wire is used for the coil 1, the thermal capacity of the coil 1 is small, and the shift from a glow discharge to an arc discharge carried out during the starting of a metal halide lamp is facilitated. In addition, since the inner coil 2 is made by winding a simple wire in one layer or two layers, the coil 2 works as a heat reserver which receives heat flowing from the end of the bar 3 which has the highest temperature in the electrode. Therefore, the thermal capacity of the whole electrode can be increased without making the diameter of the bar 3 excessively large relative to the current of the lamp. In such an electrode as above, tungsten containing thorium dioxide (ThO2) is used for at least one of the bar 3 and the coil 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a metal halide lamp containing a rare gas, mercury, and a metal halide, and particularly to an electrode thereof.

Inside the arc tube made of a translucent material such as quartz, sodium
In metal halide lamps filled with halides such as scandium, thallium, indium, tin, and rare earth metals, the electrode structure is essential to achieve excellent characteristics such as good luminous flux maintenance and no fluctuation in light output due to flickering. Improvements are particularly important. As is well known, it is not possible to use barium-based electron emissive materials, which have excellent electron emissivity and adhesion properties, for the electrodes of metal halide lamps, and instead use thorium oxide (Tho2), yttrium oxide (Y2O2), or rare earth materials. Metal oxides are commonly referred to as metal oxides. However, electric f- made of these oxides
All radioactive substances have high melting points and have difficulty adhering to tungsten electrodes, and may fall off or be sputtered from the electrodes due to strong thermal shock or ion bombardment during startup, causing the wall of the arc tube to become black. The dark spots turn gray and reduce the luminous flux maintenance rate. Therefore, in order to prevent the electron radioactive material from falling off and sputtering, it has been widely proposed to use a double or triple wire coil in the coil section that holds the electron radioactive material, but it is not perfect. do not have.

As an electrode structure in which no electron radioactive substance is deposited (, -L,
In Japanese Patent Application Laid-Open No. 52-132570, a secondary coil is loosely wound around the primary coil, and this double coil is tightly wound around the electrode core frame in approximately the same number of turns, unwinding, and inward winding. A structure in which a two-layer coil jfj is wound outwardly is disclosed. Once on this electrode, the transition time (from glow discharge at startup to arc discharge) is relatively short. This requires a large amount of thermionic emission when transitioning from glow discharge to arc discharge.
Because it uses a heat sink, its heat capacity is small and it can be
This is because they are heated by the 1-ton bombardment and emit a large amount of thermionic electrons. However, in order to improve the luminous flux maintenance rate during long-term movement, the heat capacity of the entire electrode must be maintained at an appropriate value, so in order to compensate for the small heat capacity of the coil part, the heat capacity of the electrode core frame must be increased. It is necessary to make it larger, and the electrode core frame is ¥.

Make it thicker → make it thicker. If the diameter of the electrode core becomes too large for the lamp current, the arc spot at the tip of the electrode core moves, which causes fluctuations in the light output, causing flickering in the irradiation area, and in severe cases, flickering occurs every half cycle. The restrike voltage increases, making it easier for the engine to turn off. This tendency is especially noticeable in low-wattage cards.

The present invention provides a metal halide lamp that has a good luminous flux maintenance rate, does not flicker, and does not turn off. The electrode is composed of an electrode core frame, the outer F1111 coil is composed of a double or triple double wire coil, and the inner coil has a structure in which a single wire is wound in one or two layers. At least one of the inner coils of the electrode core rod is made of tungsten containing thorium dioxide, and has an electrode structure in which no electron radioactive material is coated.

Embodiments of the present invention will be described below with reference to the drawings. .

Figures 1(a) and 1(b) show electrodes of an embodiment of a metal halide lamp according to the present invention;
(b) is the case where the inner coil is made of one layer of single wire, and (b) is the case where the inner coil is made of two layers of single wire. In addition, Figures 2 (a) and (b) show enlarged details of the double or triple double wire coil that constitutes the outer coil, and Figure 2 (a) shows the double coil 2oJ).
tH case, 0)) in the same figure is the case of the triple coil 21.

In Figures 1(a) and (b), the outer coil 1 is a 2Φ1 or triple double-wire coil, and the
The tip side of the +111 coil 1 surrounds the inner coil 2, forming a hollow part without being in close contact with the electrode core frame 3. Since a double or triple + wire coil is used for the outer coil 1, the heat capacity is small and the transition from glow discharge to arc discharge at the time of starting is facilitated.

In addition, since the inner coil 2 is composed of one or two layers of single wire, it functions as a heat reservoir that absorbs the heat flow from the tip of the electrode core frame 3, which has the highest temperature among the electrodes. Since there is no inner coil 2, the electrode core diameter does not become excessive with respect to the lamp current, and the heat capacity of the entire electrode can be increased. On the other hand, if the inner coil has three or more layers, heat conduction from the electrode core frame to the inner coil will be poor, resulting in a disadvantage that the effectiveness of the heat server will be reduced.

Therefore, by adopting the configuration of the present invention, the diameter of the electrode core rod is designed to be thinner, in order to maintain the appropriate heat capacity ht value of the entire electrode necessary to maintain the luminous flux maintenance factor at a high value during long-term movement. As a result, flickering and fading caused by movement of the arc spot at the tip of the electrode can be prevented.
4Ja metal paralite lamp with high luminous flux maintenance rate
can be provided.

In addition, since the configuration of the present invention does not coat an electron radioactive substance, it is inferior to electrodes coated with an electron radioactive substance in terms of starting characteristics and starting delay, but the starting voltage can be solved by another starting aid means. This is what Noh is all about.

An example is Figure 3(a).

For (b), a conventional circuit similar to that of a small child may be used. Same figure (
, ), the arc tube 6 is placed outside #4, and the pulsed electric LF
A series body consisting of a glow pipe 6, a current limiting resistor 7j, and a bimetal switch 8, which generates
Starting resistor 1 connected between 1 and bimetal switch 8
2 are provided. If the pulse voltage generated in the glow tube 6 is about 1600 cm, starting is possible. As a result, an inexpensive ballast for high-pressure mercury lamps can be used. A pulsed electric current 1'E is connected to the external starting auxiliary conductor 14 provided close to the arc tube 6.
The configuration that marks IJ11 makes starting possible. .

Can be used.

Regarding the starting delay, the starting delay can be reduced by using tungsten containing thorium dioxide (Th02) for at least one of the electrode core frame and the inner coil. Th02-containing tungsten has a structure in which ThO2 particles are dispersed and interposed in the grain boundaries of tungsten1, and tungsten containing 0.6 to 3% ThO2 is generally used, or the higher the Th02 content, the more brittle it becomes. It becomes difficult to wire draw or mold. However, if the startup is delayed
The more the ho2-containing edge increases, the better.

Next, a physical example of the present invention will be explained.

An electrode core frame with a diameter of 0.8 mm containing approximately 1.6% ThO2, a primary coil with a wire diameter of 0.3 mm, and a wire diameter of 0.8 mm were used.
The present invention has an electrode having an outer coil made of a double coil made of a loosely wound 1+n+n secondary winding coil, and an inner coil made of a lane coil made of a single layer of pure tungsten wire with a wire diameter of 0.4 mm. metal halide lamp A (hereinafter referred to as lamp A) and Th of approximately 1.5 parts.
Electrode core frame, wire (f,
0.06 mm secondary winding coil with a wire diameter of 0.02 mm
2 +Ji, in which the tertiary winding coil is erodedly wound: an outer coil consisting of a triple coil in which the coil is further loosely wound around a primary coil with a wire diameter of 0.3 mm, and an outer coil with a diameter of 0.25 m.
The metal halide lamp B (hereinafter referred to as lamp B) according to the present invention has an electrode with an inner coil made of a double-layered single-wire coil made of a tungsten wire with about 1.5% Th02i of m. Diameter 1. containing ThO2.
A double double wire coil, identical to the one used for the outer coil for the lamp, is wound back onto the tightly packed inner coil on a 0 mm electrode core frame, and from a two-layer coil that is wound inside and outside about the same number of times. Metal halide lamp C with conventional electrodes
(hereinafter referred to as U/P C, !i), and about 1.6% Th
The inner coil is made by tightly winding the same three-layer double-wire coil as that used for the outer coil of lamp B in an electrode core frame containing O2 and having a diameter of 0.8 am. Five prototypes of each of four types of metal halide lamps D (hereinafter referred to as lamps D) each having 41 conventional electrodes each consisting of a two-layer coil wound externally a number of times were fabricated. The entire lamp volume ti=k is not coated with electron radioactive material. The electrode weight of each lamp is 382my for rung A, 393mj for lamp B,
Lung C was 38my1, and rung D was 342my.

The arc tube of each lamp has an inner diameter of 20 mm, a distance between electrodes of 46 mm, an internal volume of approximately 1 cscc, and a power output of 400 W.
3, scandium iodide (Sc Ia), sodium iodide (NaI), and cenium iodide (CsI) are combined as additives at 813.
The arc tube was completed by enclosing 3 m of mercury to obtain a suitable IE lamp, IJE, and 60 Torr of argon as a starting gas.

These lamps were lit using the lighting circuit shown in Fig. 3 (a), and the luminous flux maintenance rate after 6000 hours of lighting, the starting voltage IF when the lamp was turned on at 5-fold intervals, and the presence or absence of flickering based on subjective evaluation. , 'The starting delay time from ton field application to the discharge start trench, and the transition time from glow discharge to arc discharge are defined and the average values are shown in Table F. The same table also shows various compatibility in 0 hour muttering.

(Margin below) As is clear from the table above, Lamp A and Lamp B according to the present invention are superior in luminous flux maintenance factor to conventional Lamp C and Lamp D. -1l: Lamps A and B have lower starting voltages than lamps C and D. Here, the reason why the starting voltage of lamp C is high is that the electrode core frame is thick and it is difficult to transition from arc discharge to arc discharge. -Also, flickering did not occur in Lamp A and Lamp B. On the other hand, flickering was observed in lamp C. This is the electrode core frame or husk.

Furthermore, Lamp A and Lamp B had good results with a short transition time from glow discharge to arc discharge.

Regarding the start delay time, lamp C and lamp D
Similarly, lamps A and B have a starting delay time or an electrode coated with an electron radioactive material.
Although it is long compared to 5 seconds, there is no practical problem as long as it is within 10 seconds.

It can be seen from the above that Lamp A and Lamp B according to the present invention, which are the older brothers, are superior to conventional Lamp C and Lamp D in terms of overall cost.

Furthermore, according to other experiments, it was confirmed that the electrode used in the present invention is also effective with other additives such as Na-Tl-In...
For In-based additives, it was confirmed that the luminous flux maintenance factor was better when pure tungsten was used for the electrode core frame and tungsten with Th02a was used for the inner coil. moreover,
It is recognized that the effects described in L can be obtained regardless of the wattage, not only 400W, but also 'yoow, 1000W, etc.
.

[Brief explanation of the drawing]

FIG. 1(a), Φ) is a sectional view showing an electrode of an embodiment of a metal light lamp according to the present invention; FIG. ) is a double-layered single-wire coil or [), and Figures 2(a) and 2(b) are enlarged views showing the outer coil of the electrode. ) is the case of a triple double-wire coil, as shown in Figure 3(a). (b) is a diagram showing an example of a lighting circuit for a metal ride lamp according to the present invention. 1...Outer 111tl coil, 2...Inner coil, 3. Electrode core. Name of agent: Patent attorney Toshio Nakao and 1 other person ft.
51 figure fR2 figure 0

Claims (1)

[Claims] Starting Jll, f inside the arc tube with electrodes sealed at both ends
Active gas, mercury, and metal halide are enclosed, and the electrode is composed of a coil portion consisting of an outer coil and an inner coil, and an electrode core rod whose tip protrudes from the outer coil, and the outer +1111 coil is The inner coil is composed of a double or triple double wire coil, the inner coil has a structure in which a single wire is wound in one or two layers, and at least one of the electrode core rod and the front inner coil. 1. A metal halide lamp, characterized in that the electrode is made of tungsten containing thorium oxide, and the electrode is not coated with an electron emitting material.