JPH01209652A - metal vapor discharge lamp - Google Patents

Abstract

PURPOSE:To prevent flicker by thermally separating a luminous tube and a resistor from a diode with a thermal insulation board. CONSTITUTION:A luminous tube 1 and a resistor 10 are thermally separated from a diode 11 by disposed a thermal insulation board 9 such as aluminum board between luminous tube 1 resistor 10 and the diode 11. The thermal insulation board 9 used in this manner insulates heat generated in the luminous tube 1 and the resistor 10, so that the surface temperature of the diode 11 falls down. Normal operation of the diode 11 is thereby ensured during its lamp life and flicker can be prevented as well.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a high-pressure metal vapor discharge lamp such as a metal halide lamp, which is designed to prevent flickering phenomena.

[Conventional technology]

A so-called metal halide lamp, in which a metal halide is sealed together with mercury and a rare gas inside an arc tube equipped with a pair of electrodes, has good color rendering properties and high luminous efficiency, so it is used as a light source in various fields. There is.

However, because this type of lamp is lit vertically and contains metal halide, metal halide vapor is released inside the arc tube while the lamp is lit. Since balance occurs, various problems arise.

The flickering phenomenon of the light emitted when the lamp is turned on also poses a problem in that it tends to cause discomfort, especially when the lamp is used as a light source for indoor lighting and is installed in a relatively low place.

This flickering phenomenon occurs because the lamp current waveform differs every half cycle during lighting of the metal halide lamp, and is asymmetrical as shown in Figure 4.The light output waveform based on this asymmetric lamp current is also shown in Figure 5. A major cause of this is that the peak values f1°r2 for each half cycle are different and asymmetrical.

Conventionally, as a means to prevent such flickering phenomenon, a method has been used in which a lamp is lit using a DC power source or a high frequency lighting device is used.

In addition, Japanese Utility Model Application Publication No. 196496/1983 discloses a method of reducing flicker caused by asymmetry in the lamp current by connecting a current control circuit consisting of a resistor and a diode in series or parallel with the arc tube and placing it inside the lamp. Disclosed.

[Problem to be solved by the invention]

However, when lighting a lamp using a DC power source as described above, electrolytic phenomena occur in the electrodes of the arc tube, resulting in a short lamp life, and when lighting a lamp using a high-frequency lighting device, acoustic resonance phenomenon occurs. This has the disadvantage that the arc becomes unstable and extinction occurs. Furthermore, if a current control circuit consisting of a resistor and a diode is connected in series with the arc tube, the flickering phenomenon can be effectively prevented, but the diode may receive heat due to radiant heat and convection from the arc tube and the resistor. There is a problem in that a chemical reaction occurs and the lamp life is shortened, and therefore it is difficult to prevent flickering and to perform normal and reliable lighting operation over the lamp life period.

Furthermore, when this current control circuit is connected in parallel to the arc tube, the effect of reducing the flicker phenomenon is small, and in the case of a lamp that is started by applying a pulse, the pulse voltage decreases, worsening the startability. It has the disadvantage of being stored away.

The present invention has been made to solve the above-mentioned problems in conventional metal vapor discharge lamps, and provides a metal vapor discharge lamp that can effectively prevent flickering during lighting over the life of the lamp. The purpose is to

[Means and effects for solving the problem] In order to solve the above problems, the present invention connects a current control circuit consisting of a parallel circuit of a resistor and a diode in series with the arc tube, and houses them in the outer tube. In this metal vapor discharge lamp, a heat shield plate is disposed between the arc tube, the resistor, and the diode to thermally isolate the arc tube, the resistor, and the diode.

With this configuration, it is possible to prevent flickering while the metal vapor discharge lamp is lit, and also to use the flickering prevention diode at a relatively low temperature, so that it can be used normally and reliably during the lamp life. It becomes possible to operate it.

〔Example〕

Examples will be described below. FIG. 1 is a front view showing the main parts of a scandium-sodium type 250 W metal halide lamp to which the present invention is applied, and FIG. 2 is a circuit configuration diagram thereof. In the figure, reference numeral 1 denotes an arc tube in which scandium and sodium iodide are sealed together with mercury and argon, and electrodes 2 and a commutative electrode 3 are sealed at both ends.

4 is a heat insulating film provided at both ends of the arc tube 1.
The arc tube 1 is attached to support plates 7.8 attached to the ends of the upper and lower struts 5.6, with both ends thereof supported. A heat shield plate 9 made of an alumina plate with a diameter of 35 m5 and a thickness of 11 m is disposed in the middle of the upper support column 5, and below the heat shield plate 9, the external terminal 2a of the electrode 2 of the arc tube 1 and the upper support column 5 are connected. 5Ω resistor 10 between
are connected and arranged.

On the other hand, above the heat shield plate 9, a diode 11 is connected between the external terminal 2a of the electrode 2 projecting through the heat shield plate 9 and the upper support column 5. In the figure, 12 is a getter formed on the support plate 8, and 13 is a lead wire made of molybdenum for electrically connecting the upper support 5 to the base of a lamp (not shown). These constituent members are enclosed in an outer tube (not shown) to constitute a metal halide lamp. In Fig. 2, 21 is a metal halide lamp, 22 is a choke coil type ballast,
23 indicates a power source.

The lifespan of a diode on a ship is determined by the sum of the temperature rise of Junxilon due to energization and the ambient temperature, which is 175℃.
is the normal limit value. Therefore, its rated life is determined by the current value and ambient temperature. For example, rated 3A
When using this diode at an ambient temperature of 120℃,
It is known that it can withstand 9000 hours of lamp life. By the way, when the diode is simply placed inside the outer bulb of the lamp as in the past, each part inside the outer bulb is It has been difficult to operate normally over the life of the lamp because the temperature is considerably high and the diode is therefore exposed to high temperatures of, for example, 178° C., resulting in a short life span.

On the other hand, by adopting a configuration using the heat shield plate 9 as in the above embodiment, the heat generated from the arc tube 1 and the resistor 10 is blocked by the heat shield plate 9, so that the surface temperature of the diode 11 decreases. temperature was reduced to below 105°C. Thereby, the diode 11 can be operated normally over the lamp life period, and the lighting operation can be performed while preventing the flickering phenomenon.

In the above embodiment, the diameter of the heat shield plate 9 is 35 fl, which is five times the diameter 7H of the diode 11.
Although heat radiation from the resistor 10 can be avoided, the effect of avoiding heat due to convection is small. Therefore, for safety reasons, the diameter of the heat shield plate 9 is set to 2.0 mm of the diameter of the diode 11.
It turned out that about 5 times as much is necessary. In addition, if the maximum diameter of the heat shield plate 9 is about the same as the distance between the two upper supports,
Its installation is convenient and easy to install. The distance between the upper struts 5.5 is 6 of the diameter of the diode 11.
Since the diameter is about twice that of the diode 11Φ, it is desirable that the diameter of the heat shield plate 9 is 2.5 to 6 times the diameter of the diode 11Φ.

Further, the material of the heat shield plate 9 is not limited to alumina, but any other ceramic material, glass, or metal material that can withstand the heat of the arc tube 1 can be used. Further, in the above embodiment, the heat shield plate 9 is a disc-shaped one as shown in FIG. A dish-shaped or conical shape as shown in Figure fB) and C+, or even a polygonal shape can also be used.

Furthermore, in the above embodiment, a 250W scandium-sodium type metal halide lamp was used, but the present invention can also be applied to metal halide lamps of other wattages and other types of metal vapor discharge lamps. In this case, the relationship between the diameter of the heat shield plate and the diameter of the diode was set to approximately the same value as in the above embodiment, and the same effects were obtained.

〔Effect of the invention〕

As described above based on the embodiments, according to the present invention, the heat shield plate is provided to thermally isolate the arc tube and the resistor from the diode. It is possible to protect the lamp from heat caused by radiation and convection, thereby preventing damage, and to ensure normal and reliable anti-flicker operation over the life of the lamp.

[Brief explanation of the drawing]

Fig. 1 is a front view showing the main parts of an embodiment of the metal vapor discharge lamp according to the present invention, Fig. 2 is its circuit configuration diagram, and Fig. 3
, +81. (C1 is a diagram showing the shape of the heat shield plate, the fourth
Figure 5 shows the current waveform of a metal halide lamp.
The figure is a diagram showing a light output waveform of a metal halide lamp. In the figure, 1 is an arc tube, 5 and 6 are pillars, 7.8 is a support plate, 9 is a heat shield plate, 1O is a resistor, and 11 is a diode.

Claims (1)

[Claims] 1. In a metal vapor discharge lamp in which a current control circuit consisting of a parallel circuit of a resistor and a diode is connected in series with the arc tube and these are housed in an outer bulb, the arc tube, the resistor, and the diode are connected in series. A metal vapor discharge lamp characterized in that a heat shield plate is disposed between the arc tube and the resistor to thermally isolate the diode. 2. The heat shield plate is made of a heat-resistant material such as ceramic, glass, or metal, and its maximum diameter R and the diameter r of the diode are set to satisfy the following relationship: 2.5r≦R≦6r. The metal vapor discharge lamp according to claim 1, characterized in that: