JPH03742B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a metal vapor discharge lamp in which a starter device and a thermally responsive switch are incorporated together with an arc tube in an outer bulb.

(Description of the Prior Art) Metal vapor discharge lamps generally require a starting device for starting, but lamps in which a starting device is built into the outer bulb along with the arc tube have recently been known.

A conventional metal vapor discharge lamp with a built-in starting device is shown in FIGS. 1 and 2. The arc tube 2 housed in the outer tube 1 has main electrodes 3, 4 and an auxiliary starting electrode 5, and is held within the outer tube 1 by supports 6, 7. Inside the outer tube 1, on the base 8 side, a normally closed bimetal switch 9 as a thermally responsive switch, a glow lighting tube 10 as a starter, and a current limiting resistor 11 are housed. Although not shown, the current limiting resistor 11 is formed into a plate shape by covering the outer surface of a resistor with a heat-resistant insulator such as ceramic. The bimetal switch 9 is mechanically supported by the ceramic-coated plate-like current limiting resistor 11.

As shown in FIG. 2, the auxiliary electrode 5 is connected to the bimetal switch 9 and the contact 12 of the glow lamp 10, and is connected to the opposing main electrode 3 via the bimetal switch 9 and the current limiting resistor 11. There is.
The lighting tube 10 is connected to the main electrode 4 via the support 6. and main electrodes 3 and 4 are stem 1
3 through the lead wires 14 and 15 sealed to the base 8.
and a terminal 16, and is connected to a power source 18 via a ballast 17 shown in FIG.

In such a discharge lamp, when voltage is applied via the ballast 17, the normally closed bimetal switch 9 is closed, so the lighting tube 10 and the bimetal switch 9 are closed.
A current flows through the current limiting resistor 11, and the glow lighting tube 10 is activated. A pulse voltage generated from the ballast 17 by the switching current of the glow lighting tube 10 is applied between the main electrodes 3 and 4 and to the main electrode 4 and the auxiliary electrode 5. As a result, the arc tube 2 is started. When the arc tube 4 is started, the temperature inside the outer bulb 1 rises due to the heat generated by the arc tube 4, and this heat opens the normally closed bimetal switch 9 to prevent current from flowing to the lighting tube 10. Therefore, while the arc tube 2 is lit, the operation of the lighting tube 10 is stopped, and the operation of the lighting tube 1 is stopped.
0 and prevent unnecessary pulse voltage from being applied to the arc tube 2.

However, as mentioned above, the normally closed bimetal switch 9 is opened by the heat generated from the arc tube 2, so when the arc tube 2 is lit, it is irradiated with infrared rays emitted from the arc tube and is constantly heated. It turns out. The bimetallic switch 9 may become fatigued and softened due to the heating during the life of the lamp, which lasts several thousand hours, and the bimetallic contacts may not be able to completely return and close.

For lamps with a rated output of 700 watts or more than 1 kilowatt, the neck part of the outer bulb 1 is long, so the normally closed bimetal switch 9 is housed in the neck part and kept at a distance of 50 cm or more from the arc tube 2. Although it is not impossible to avoid excessive heating during lighting, especially at 200 watts or 400 watts,
For lamps larger than medium-sized lamps such as Watts, use the arc tube 2.
Since the distance between and the bimetal switch 9 is small,
The drawback was that the bimetal deteriorated significantly due to heat.

(Object of the Invention) The present invention was made based on the above circumstances, and its purpose is to prevent deterioration of a thermally responsive switch due to heat radiation from the arc tube, and to ensure reliable operation over the entire life of the switch. The purpose of this invention is to provide a metal vapor discharge lamp that can be used.

(Summary of the Invention) That is, the present invention interposes a heat insulator between the arc tube and the thermally responsive switch to prevent the radiant heat from the arc tube from directly hitting the thermally responsive switch, and also It is constructed of a current limiting resistor whose outer surface is coated with a heat-resistant insulator to prevent early thermal deterioration of the thermally responsive switch.

(Embodiment of the Invention) An embodiment of the present invention will be described below with reference to FIGS. 3 and 4.

This embodiment is the same as the conventional FIG. 2 in terms of circuit configuration, and most of the mechanical configuration is also the same as that in FIG. 1, so it is the same as FIG. 1 and FIG. The parts will be given the same numbers and their descriptions will be omitted.

This embodiment differs from FIG. 1 in that a normally closed bimetallic switch 9 is used as a thermally responsive switch.
and the ceramic-coated current-limiting resistor 11 are arranged upside down. That is, the normally closed bimetallic switch 9 is mechanically attached to the ceramic coated current limiting resistor 11, as described above.
By reversing the upper limit and attaching it to the support 6 by the support wires 31 and 32, the normally closed bimetal switch 9 is not only moved away from the arc tube 2, but also moved away from the normally closed bimetal switch 9. Bimetal switch 9 and arc tube 2
In other words, a heat insulator is interposed between the ceramic-coated current-limiting resistor 11 and the ceramic-coated current-limiting resistor 11.

The unit structure of the normally closed bimetallic switch 9 and its heat insulator (ceramic-coated current limiting resistor 11) is shown in FIG. In other words, 11a is a resistor arranged in a meandering pattern, and 11b is a resistor 1
It is a plate-shaped ceramic body covered with 1a.
9a is a fixed contact implanted in the ceramic body 11b, 9b is a conductive support wire also implanted in the ceramic body 11b and electrically connected to the resistor 11a, 9c is a bimetal piece, and 9d is a movable contact. .

In such an embodiment, the radiant heat from the arc tube 2 during lighting is absorbed by the ceramic coated current limiting resistor 1.
1 prevents the bimetal switch 9 from being excessively heated, and reduces the rate at which the bimetal piece 9c softens due to heating fatigue caused by irradiation with infrared rays emitted from the arc tube. Ru. Therefore, the movable contact 9d is the fixed contact 9a.
The bimetal switch 9 operates reliably in contact and separation, and the function of the bimetal switch 9 is not impaired during the entire life of the lamp.
Particularly in the case of 200 watt and 400 watt class lamps, the distance between the arc tube 2 and the bimetal switch 9 is shortened, but the effect is significant due to the heat insulating effect of the above embodiment.

In addition, the arc tube 2 and the normally closed bimetal switch 9
If a heat insulator is interposed between the lamp and the lamp, the radiant heat from the arc tube 2 will be insulated, but convection heat exists within the outer tube 1, so the lighting tube 2 will be stable after starting. When the light is turned on, the normally closed bimetal switch 9 is heated by the convection heat and opens. For this reason, the lighting tube 10 is protected by keeping the current away from the lighting tube 10. In this case, the opening timing of the normally-closed bimetal switch 9 may be slightly delayed compared to the conventional switch shown in FIG. 1, but this delay in opening timing does not pose a major problem in practice.

Although the materials, structure, etc. are clearly defined in the above embodiments, the present invention is not limited thereto, and the current limiting resistor 11 may be coated with mica or the like and formed into a plate shape.

The present invention also provides a glow lighting tube 10 as a starting device.
However, the switch is not limited to a bimetal switch.

(Effects of the Invention) As detailed above, in the present invention, a heat insulating body consisting of a current limiting resistor whose outer surface is coated with a heat-resistant insulator is interposed between the arc tube and the thermally responsive switch. Since the radiant heat from the arc tube is blocked by the heat insulator, the thermally responsive switch will not be overheated. This has the advantage that thermal deterioration of the thermally responsive switch is prevented and reliable opening/closing operation can be maintained over the entire life of the lamp.

[Brief explanation of the drawing]

1 and 2 show a conventional example, FIG. 1 is a block diagram, FIG. 2 is a circuit diagram, and FIGS. 3 and 4 show an embodiment of the present invention, and FIG. 3 is a block diagram. , 4th
The figure is a unit configuration diagram of a normally closed bimetallic switch and a ceramic-coated plate-like current-limiting resistor. 1... Outer tube, 2... Arc tube, 3, 4... Main electrode, 5... Auxiliary electrode for starting, 9... Normally closed bimetal switch (thermal response switch), 10... Glow lighting tube (starting) device), 11... Ceramic coated plate current limiting resistor.

Claims (1)

[Claims] 1. An arc tube having at least one pair of main electrodes;
A metal vapor discharge lamp having a starter device for starting the arc tube, a current limiting resistor connected to the starter device, and a thermally responsive switch that stops energizing the starter device after starting the arc tube, built in the outer bulb. A metal vapor discharge lamp characterized in that a heat insulating body made of a current limiting resistor whose outer surface is coated with a heat-resistant insulator is interposed between the arc tube and the thermally responsive switch. 2. The metal vapor discharge lamp according to claim 1, wherein the thermally responsive switch is supported by the heat insulator.