JPS6213327Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to the improvement of lighting devices for high-pressure metal vapor discharge lamps, particularly metal halide lamps. An object of the present invention is to improve the reliability of the starting performance of a lighting device in which a series circuit is connected in parallel to an arc tube and connected to a power source via an inductive ballast.

In order to achieve this purpose, in this invention,
The above lighting device is characterized in that the contact rod constituting the thermally responsive switch is made of thoriated tungsten material, and that at least the contact surface of the contact rod is roughened to have a surface roughness of 10 μm or more. .

Due to the characteristic configuration of the present invention, the duration of the chatter between the contact rods of the thermally responsive switch can be reliably made longer than before, and the high-frequency pulse generated at that time can reliably start the discharge lamp. I can do it.

The present invention will be described in detail below using figures.

FIG. 1 shows the overall configuration of a discharge lamp lighting device according to the present invention. Reference numeral 1 designates an arc tube, main electrodes 2 and 2' are sealed at both ends thereof, and mercury, rare gas, and various metal halides are sealed inside the arc tube. Reference numeral 3 denotes an auxiliary electrode provided on the main electrode 2' side, and is connected to one end of a power source 5 via a thermally responsive switch 4. Further, the main electrode 2 and the auxiliary electrode 3 are connected via a resistor 6. The auxiliary electrode 3, the thermally responsive switch 4, and the resistor 6 constitute a first starting auxiliary circuit for the arc tube 1. On the other hand, a series circuit consisting of a thermally responsive switch 7, a heating element 8, and a resistor 9 is connected in parallel to the arc tube 1, and constitutes a second starting auxiliary circuit for the arc tube 1. These starting auxiliary circuits are installed inside the outer tube 10 and constitute a metal halide lamp. This metal halide lamp is connected to a commercial power source 5 via an inductive ballast 11.

The metal halide lamp lighting device configured as described above operates as follows. When the power source 5 is turned on, the above-mentioned first starting auxiliary circuit operates, and the arc tube 1 is brought into a state where it is easy to discharge. Next, the heating element 8 is heated by the current controlled by the resistor 9 flowing through the second starting auxiliary circuit, and the thermally responsive switch 7, which had been closed, is opened by the heat.
When the thermally responsive switch 7 opens, the current flowing in the circuit is cut off, so the inductive ballast 1
A single high voltage pulse is generated across the arc tube 1, but this pulse does not discharge the arc tube 1. Furthermore, when the cooled thermally responsive switch 7 attempts to close, a chattering phenomenon occurs, resulting in repeated opening and closing operations at very short time intervals. Due to this chattering phenomenon, the current flowing in the circuit is interrupted, so a high frequency, high voltage pulse is generated between both ends of the inductive ballast 11, and this high voltage pulse is transmitted to the main electrodes 2, 2' of the arc tube 1. applied in between. As a result, the arc tube 1 starts discharging, and the metal halide lamp is turned on.

The detailed configuration of the thermally responsive switch 7 is shown in Figure 2 a and b.
Shown below. FIG. 2b shows a side view of FIG. 2a. The thermally responsive switch 7 is composed of contact rods 12, 12' made of hardly soluble metal rods, a bimetal plate 13, support fittings 14, 14', and an insulator 15 for fixing the support fittings 14, 14'. Support metal fittings 1
4, 14' and the insulator 15 are made of, for example, a combination of Mo wire and Mo glass, or a combination of Kovar and Kovar glass.

From various experimental results regarding the thermally responsive switch 7 having such a configuration, it has been found that constructing the contact rods 12, 12' with thoriated tungsten material can sustain the high voltage pulse for the longest time due to the above-mentioned chattering phenomenon. There was found. Furthermore, it has been found that the surfaces of the contact rods 12, 12' may be roughened in order to easily generate high voltage pulses and to increase their duration. By roughening the contact surfaces of the contact rods 12, 12' from the beginning, the initial discharge between the contact rods 12, 12' is facilitated, so that the duration of the high voltage pulse can be reliably extended. , it is possible to improve the reliability of the starting performance of the discharge lamp lighting device.

Figure 3a shows the surface roughness μ of the contact rods 12, 12'.
This figure shows the relationship between m and the number of high-voltage pulses generated. The definition of surface roughness is the average value of unevenness Io (μ
m). Further, the number of high-voltage pulse occurrences is the number of times a pulse with a pulse duration of 0.3 seconds or more occurs in 5 minutes. As is clear from Figure 3a, as the surface roughness of the thoriated tungsten contact rod increases, the number of pulse generation gradually increases, and when the surface roughness reaches 10 μm or more, the number of pulses is saturated. I'll come. Therefore, it can be seen from this graph that if the surface roughness is set to 10 μm or more, the number of pulse generation can be stably maintained and a highly reliable lighting device can be obtained.

Next, a specific example of roughening the surface of a contact rod and its characteristics will be described.

Example 1 Grinding wheel #80 made of silica powder, silica sand, etc. was applied to the surface of a 1 mm diameter thoriated tungsten rod under pressure 2.
Figure 4a shows a schematic diagram of the surface condition when so-called liquid honing, which roughens the surface by 10 μm or more by spraying at Kg/cm ² for 60 seconds, is performed. It is sufficient to roughen the contact rod surface only on the contact surface, but in reality, such local roughening is difficult and the entire surface of the contact rod must be roughened. However, even when applied to the entire surface, there was no problem with mechanical strength or the like.

The operating characteristics of a thermally responsive switch having a contact rod with a roughened surface in this manner are shown by curve A in FIG.

In FIG. 5, the horizontal axis shows the sample number (10 samples), and the vertical axis shows the pulse generation circuit (times), and the definition of the number of pulse generation is as described above. Curve C in the figure shows the operating characteristics of a conventional contact rod whose surface is made extremely smooth (surface roughness of 1 μm or less) by chemically treating the surface of the contact rod. This was used for comparison in terms of characteristics. When comparing curve A according to the present invention and conventional curve C, there are variations in the number of pulses generated depending on the sample number, but when looking at the average number of pulses generated, curve A is =
7.0, whereas curve C is =2.9, which shows that the lighting device according to the present invention is much superior to the conventional one.

Example 2 When a thoriated tungsten rod having a diameter of 1 mm is diced from a raw material, by providing irregularities on the inner surface of the die, the surface can be made to have a desired surface roughness, that is, a surface roughness of 10 μm or more. FIG. 4b is a schematic diagram of the surface condition when the surface is roughened in this manner. Curve B in FIG. 5 is its operating characteristic. As with curve A, the number of pulses generated varies depending on the sample, but the average number of pulses is 6.2, which is much improved over the conventional curve C.

Example 3 FIG. 4c shows a schematic diagram of the surface of a contact rod, which was made by machining a thoriated tungsten rod with a diameter of 1 mm to have a surface roughness of 10 μm or more. This was different from the case of die drawing shown in FIG. 4b, in which scratches were provided in the circumferential direction of the contact rod, and the operating characteristics were almost the same as in FIG. 4b.

In addition to the methods described above, chemical polishing and electrolytic polishing methods can be considered as surface roughening methods, and surface roughness of 10 μm or more can be easily achieved using these methods as well.

As described above, the present invention makes it possible to reliably increase the duration of the high-frequency pulse required to start a discharge lamp, and as a result, it is possible to provide a discharge lamp lighting device with extremely excellent starting performance. It is something.

[Brief explanation of the drawing]

Figure 1 is a circuit configuration diagram of a discharge lamp lighting device according to the present invention, Figures 2a and b are detailed configuration diagrams of the thermally responsive switch in Figure 1, and Figures 3a and b are graphs showing the effects of the present invention. Explanatory diagrams of surface roughness, Figures 4a, b, and c are examples according to the present invention, and Figure 5 is a schematic diagram of the surface condition of the contact rod, and Figure 5 is a characteristic of the embodiment shown in Figures 4a and b. This is a graph showing. 1... Arc tube, 2, 2... Main electrode, 3... Auxiliary electrode, 4, 7... Thermal response switch, 8... Heat generating element, 6, 9... Resistor, 10... Outer tube, 11 ……
Inductive ballast, 5... Commercial power supply, 12, 12'...
...Contact rod, 13...Bimetal plate, 14, 14'
...Supporting metal fitting, 15...Insulator.

Claims (1)

[Scope of utility model registration request] closes at room temperature and opens at high temperature, and
A starting auxiliary circuit in which a thermally responsive switch having a contact rod, a heating element for controlling the opening and closing of the thermally responsive switch, and a resistor for controlling the current flowing through the heating element are connected in series is connected to the arc tube. In a discharge lamp lighting device in which discharge lamps connected in parallel are connected to a power source via an inductive ballast, the contact rod of the thermally responsive switch is made of thoriated tungsten, and at least the contact point of the contact rod is made of thoriated tungsten. A discharge lamp lighting device characterized in that a surface has a surface roughness of at least 10 μm.