JPH03116687A - High-pressure metallic vapour discharge lamp - Google Patents

Abstract

PURPOSE:To prevent damage and danger to a lighting circuit by separating a nonlinear capacitor FEC circuit from a power supply through two thermoreactive switches during lighting a discharge lamp and preventing voltage from being applied to the FEC through a starting auxiliary electrode circuit. CONSTITUTION:A series circuit which is composed of two thermoreactive switches 4a, 4b with room-temperature closed contacts and a nonlinear capacitor (FEC) 5 is connected in parallel to a luminous tube 1, and a starting auxiliary electrode 3 is electrically connected to a main electrode 2a via a resistor 6 and the thermoreactive switch 4a, one of two thermoreactive switches. There is therefore no danger resulting from lowered high-voltage pulse generative function and lowered electric resistance of the FEC. When the discharge lamp is restarted, if either one of two thermoreactive switches 4a, 4b is closed in priority and the other one is not closed, no voltage is applied to the FEC 5 and so no high-voltage pulse occurs.

Description

[Detailed description of the invention] (Industrial application field) The invention includes a starter consisting of a nonlinear capacitor.

Concerning improvements in high pressure metal vapor discharge lamps such as metal halide lamps.

(Prior Art) FIG. 5 is an example of a high-pressure metal vapor discharge lamp equipped with a starter consisting of a nonlinear capacitor (hereinafter referred to as FEC) having hysteretic voltage-charge characteristics. In the figure, 1 has a pair of main electrodes 2a + 2b and a starting auxiliary electrode 3 provided close to one of the main cough electrodes, and contains metal halides such as added sodium and scandium along with mercury and rare gas. It is an arc tube made by enclosing a chemical compound. An FEC 5 is connected in parallel to the arc tube 1 via a thermally responsive switch 4 having normal-temperature closed contacts. Further, the starting auxiliary electrode 3 of the arc tube 1 is electrically connected to the main electrode 2a adjacent thereto via the resistor 6 and the thermally responsive switch 4. And these arc tubes 1. Thermal response switch4. The FEC 5 and the resistor 6 are housed inside the lamp outer bulb 7.

8 is a ballast such as a choke coil, and 9 is an AC power source.

When an AC power supply voltage is applied to the discharge lamp as described above, the FE
C5 oscillates and a high voltage pulse is generated in the winding of the ballast 8, which is applied together with the power supply voltage to the electrodes of the arc tube 1, thereby starting and lighting the discharge lamp. After the discharge lamp starts, discharge tube 1
Thermal response switch 4 opens due to radiant heat from the FEC 5, disconnects the FEC 5 from the power supply, and at the same time connects the starting auxiliary electrode 3 to the main electrode 2.
electrically disconnected from a.

However, in the discharge lamp as described above, when the discharge lamp is started and the thermally responsive switch 4 is opened, the power source 9 consisting of the main electrode 2a, the arc discharge, the starting auxiliary electrode 3, the resistor 6, the FEC 5, and the power source 9 is activated. A voltage is applied to the FEC 5 through the circuit.

On the other hand, the FEC 5 incorporated in the outer bulb of the discharge lamp is exposed to extremely high temperatures while the discharge lamp is lit. For example, if the FEC is installed near the base attachment part of the outer sphere, approximately 3
00°C, which is much higher than the transformation point (Curie point) of the ferroelectric material that makes up the FEC. FE
When C is placed in such a high temperature, it changes from a ferroelectric material to a paraelectric material, and the dielectric constant and capacitance decrease.

Since the impedance increases accordingly, a voltage with a high waveform as shown in FIG. 7 is applied between the terminals of the FEC 5.

In this way, when a high voltage is continuously applied to the FEC 5 at high temperatures, the silver in the silver film electrode provided on the surface of the ferroelectric crystal constituting the FEC diffuses into the ferroelectric material along the grain boundaries. ), as a result, F
The hysteresis characteristics of the EC will be impaired, and the high voltage pulse generation function will be degraded. Furthermore, since silver diffuses into the ferroelectric material, the insulation resistance of the FEC also decreases, making dielectric breakdown more likely to occur.

In order to solve this problem, as shown in FIG. 6, an FEC 5 and a resistor 6 are connected to the arc tube 1 in parallel via separate thermally responsive switches 4a and 4b each having a normal temperature closed contact. It has also been proposed to connect the FEC 5 so that no voltage is applied to the FEC 5 through the circuit of the starting auxiliary electrode 3 after the discharge lamp is lit.

However, in such a structure, when a discharge lamp that has been in a lit state is once turned off and then restarted within a short time, the thermally responsive switch 4b on the side of the starting auxiliary electrode 3 does not return to the closed state after the discharge lamp is turned off. If the thermally responsive switch 4a on the FEC 5 side returns to the closed state before too long, a high voltage pulse is generated but the discharge lamp does not start, which not only damages the discharge lamp lighting circuit but is also dangerous. Therefore, in such a structure, the contact pressure must be adjusted so that the switching contact of the thermally responsive switch 4b on the side of the starting auxiliary electrode 3 returns earlier than the switching contact of the thermally responsive switch 4a on the FEC 5 side. This was an inconvenience.

(Problems to be Solved by the Invention) Therefore, the present invention provides a high-pressure metal vapor discharge lamp equipped with an arc tube having an auxiliary starting electrode and a starter consisting of an FEC, which There is no reduction in the FECO high voltage pulse generation function or insulation resistance due to voltage being applied to the FEC, and there is no need to adjust the opening/closing contacts of the starting auxiliary electrode or the thermally responsive switch that opens and closes the FEC circuit. The purpose is to provide discharge lamps.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a high-pressure metal vapor discharge lamp equipped with a starter made of FEC, which includes a pair of main electrodes and A series circuit consisting of two thermally responsive switches each having a normal temperature closed contact and an FEC is connected in parallel to an arc tube which has a starting auxiliary electrode provided therein and is filled with a metal halide along with mercury and a rare gas. At the same time, the starting auxiliary electrode is electrically connected to a main electrode that is not adjacent thereto via a resistor and one of the two thermally responsive switches. The structure is as follows.

(Function) In the present invention, since the two thermally responsive switches are connected in series to the FEC as described above, any one of the thermally responsive switches opens after the discharge lamp is started. , the FEC circuit is disconnected from the power supply, so generation of high voltage pulses stops. Also, one of the thermally responsive switches opens the circuit that electrically connects the starting auxiliary electrode to the main electrode that is not adjacent to it, and the other one opens the FEC circuit through the circuit of the starting auxiliary electrode. Since the circuit to which the voltage is applied is opened, it is possible to prevent the high voltage pulse generation function of the FEC from deteriorating and the insulation resistance from decreasing. Furthermore, when restarting a discharge lamp, no matter which of the two thermally responsive switches closes first, no voltage will be applied to the FEC unless the other closes, so high voltage pulses will not occur. do not have.

(Example 1) FIG. 1 shows a basic example of the present invention. In the same figure, ■ has a pair of main electrodes 2a and 2b and an auxiliary starting electrode 3 provided close to one of the main electrodes, and inside contains concentrated sodium, concentrated scandium, etc. along with mercury and rare gas. It is an arc tube made by enclosing a metal halide. The arc tube 1 includes two thermally responsive switches 4a having normal temperature close contacts;
FEC5 is connected in parallel via 4b. In FEC, silver film electrodes with a diameter of 14.5 mm are formed on both sides of a disc-shaped sintered body with a diameter of 15.5 mm and a thickness of 1.0 mm, which is mainly composed of barium titanate (BaTi03), and electrode terminals are attached to these. In addition to being connected, the outer periphery is overcoated with inorganic glass. The Curie point of this FEC5 is 90
°C, and can withstand temperatures of 400 °C continuously - 550 °C temporarily so that it can be installed inside the lamp's outer bulb. Further, the starting auxiliary electrode 3 of the arc tube 1 includes a resistor 6 of Ω at 30 and one of the two thermally responsive switches 4a and 4b.
It is electrically connected to the main electrode 2a via the electrode 4b. Each of these components is housed inside the lamp outer bulb 7.

8 is a ballast, and 9 is an AC power source.

When an AC power supply voltage is applied to such a discharge lamp, the power supply voltage is applied to the FEC 5, and the FEC 5 oscillates, so that the ballast 8
A high voltage pulse as shown in FIG. 8 is generated in the winding of the light emitting tube 1, and this is applied together with the power supply voltage between the main electrode 2b of the light emitting tube 1 and the auxiliary starting electrode 3 adjacent thereto. A discharge occurs between the two. Subsequently, this discharge occurs at the amphibious electrode 2a.
, 2b, and the discharge lamp starts. When the discharge lamp starts, the heat-responsive switch 4a first opens due to the radiant heat of the arc tube 1, disconnecting the FEC 5 from the power supply, and thus stopping the generation of high voltage pulses. Next, another thermally responsive switch 4
Since b is also open, the FEC5 is passed through the circuit of the starting auxiliary electrode 3.
Since no voltage is applied to the FEC, it is possible to prevent a decrease in the high voltage pulse generation function of the FEC and a decrease in insulation resistance.

Furthermore, when restarting the discharge lamp, first the thermally responsive switch 4b closes, and then the other thermally responsive switch 4a closes, but the high Since no voltage pulses are generated, generation of unnecessary high voltage pulses can be prevented.

In this embodiment, a case has been described in which the thermally responsive switch 5 is designed to open first, but in the present invention, there is no need to specify the opening/closing order of the two thermally responsive switches, so the switching contact pressure is There is no need to compare or adjust.

Further, the connection point of the thermally responsive switch 4b may be a point A (marked with an x).

(Example 2) FIG. 2 shows a second example of the present invention. Note that the first
Portions corresponding to those in the embodiment are given the same reference numerals and explanations will be omitted. This embodiment is suitable for medium to high wattage discharge lamps, and a semiconductor switch 10 is connected in series with the FEC 5. In a 400W metal halide lamp, the breakover voltage of the semiconductor switch 10 is ■. is 100-22
0■ is appropriate, and the peak value of the high voltage pulse is 1000
~2000V. Note that generally the semiconductor switch 10
is held inside the base and can withstand high temperatures during lighting.

(Embodiment 3) FIG. 3 shows a third embodiment of the present invention. Note that parts corresponding to those in the first and second embodiments are designated by the same reference numerals and their explanations will be omitted.

In this embodiment, a resistor 11 of 10 to 200 Ω is provided in parallel with the semiconductor switch 10 of the second embodiment, thereby making it possible to stabilize the ON phase of the semiconductor switch 10.

(Embodiment 4) FIG. 4 shows a fourth embodiment of the present invention. Note that the first to
Portions corresponding to those in the third embodiment are designated by the same reference numerals, and description thereof will be omitted.

This embodiment uses a phase advance type ballast in the third embodiment, and further adds a resistor 12 of 10 to 300 Ω in parallel to the series circuit of the FEC 5 and the semiconductor switch 10. This resistor 12 serves as a discharge resistance for the series capacitor 13 of the phase advance type ballast 8, and prevents the starting circuit from being blocked by charging the phase advance capacitor in one direction due to an unbalanced current when starting the discharge lamp. This is to prevent

(Effects of the Invention) As is clear from the above description, according to the present invention, while the discharge lamp is lit, the FEC circuit is disconnected from the power supply by the two thermally responsive switches, and the FEC circuit is connected to the starting auxiliary electrode circuit. Since voltage is also prevented from being applied to the FEC,
There is no reduction in the FECO high voltage generation function or insulation resistance. Also, when restarting the discharge lamp, 2
The high voltage
Since no pulses are generated, damage to the lighting circuit or danger due to the generation of unnecessary pulses can be prevented.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the invention, FIG. 2 is a circuit diagram showing a second embodiment of the invention, and FIG. 3 is a circuit diagram showing a third embodiment of the invention.
FIG. 4 is a circuit diagram showing a fourth embodiment of the present invention; FIGS. 5 and 6 are circuit diagrams of a conventional discharge lamp; FIG.
The figure is a voltage waveform diagram applied to FEC of a conventional discharge lamp, and FIG. 8 is a waveform diagram of high voltage pulses generated by FEC. l... Arc tube, 2a, 2b... Main electrode, 3... Starting auxiliary electrode, 4.4a, 4b... Thermal response switch, 5.
...FEC16...resistor, 7...outer bulb, 8...ballast, 9...AC power supply, 10...semiconductor switch,
11.12...Resistor, 13...Capacitor. Figure Figure Figure Figure 7

Claims (1)

[Claims] (1) It has a pair of main electrodes (2a) and (2b) and a starting auxiliary electrode (3) provided close to one of the main electrodes, and a metal halide is sealed therein along with mercury and a rare gas. In parallel with the arc tube (1) consisting of a
5), and connect the starting auxiliary electrode (3) to the main electrode (2a) which is not close to the resistor (6) and one of the two thermally responsive switches. A high-pressure metal vapor discharge lamp characterized in that it is electrically connected via a thermally responsive switch (4a).