JPH03741B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a metal vapor discharge lamp in which a starting means including a lighting tube and a current limiting resistor is housed in an outer bulb along with an arc tube.

Metal halide lamps and high-pressure sodium lamps are more efficient than high-pressure mercury lamps, so they can be used in place of high-pressure mercury lamps, and in lighting circuits for high-pressure mercury lamps.
In other words, various attempts have been made to use ballasts for high-pressure mercury lamps to light metal halide lamps and high-pressure sodium lamps.

That is, metal halide lamps and high-pressure sodium lamps have a higher starting voltage than high-pressure mercury lamps, and therefore it is difficult to start them simply when combined with a mercury lamp ballast.

Therefore, proposals have been made to lower the starting voltage by filling the arc tube with so-called Penning gas, which is a mixture of neon and argon, so that it can be lit even with a mercury lamp ballast.
Since this type uses a mixed gas mainly composed of neon, which has a light mass, it has a light efficiency of 5 to 8
There is a drawback that it decreases by about %.

In order to eliminate such problems, a starting means is built into the outer bulb together with the arc tube, and by using a glow lighting tube as the starting means, the pulse voltage generated by the glow lighting tube is reduced when starting the lamp. It has been proposed that the arc tube is started by applying it to the arc tube.

However, those using a glow lamp tube as a starting means have a property that the pulse generated by the lamp tube becomes higher as the lamp life progresses. In other words, as the life of the lighting tube progresses, the inert gas (argon, etc.) inside the lighting tube deteriorates due to sputtering of the contacts, and impurity gas is released from the glass bulb, etc. The peak value of the generated pulse increases. In addition to this, the starting voltage of the arc tube also increases as its life progresses. Therefore, as the life progresses, the pulse generated by the lighting tube increases, and if the lighting tube does not start despite this,
A so-called discharge within the outer tube is caused in a portion of the outer tube that is prone to discharge, that is, between conductive members having different polar potentials. Once such outer tube discharge occurs, the discharge continues because the inside of the outer tube is maintained in a nitrogen gas or inert gas atmosphere, which has the drawback of causing melting of the conductive member and damage to the outer tube. Ta.

The present invention was developed based on the above circumstances, and its purpose is to instantly stop the outer tube discharge even if it occurs, thereby preventing melting of the conductive member and damage to the outer tube, thereby increasing safety. The present invention aims to provide a metal vapor discharge lamp with improved performance.

An embodiment of the present invention will be described below based on the drawings.

The drawing shows a metal halide lamp, and 1 is an outer bulb. An arc tube 2 is housed within the outer tube 1. Inside the arc tube 2, main electrodes 3a, 3b and an auxiliary starting electrode 4 are housed in proximity to one of the main electrodes 3a. Note that this starting auxiliary electrode 4 may not be used in some cases.

The arc tube 2 is filled with a predetermined amount of mercury, a metal halide, and an inert gas such as argon gas.

The arc tube 2 has both ends attached to holders 5a and 5b.
are held by supports 6a and 6b, respectively, with one support 6a being welded to an inner conductor 8a sealed to the stem 7, and the other support 6b being attached to the top of the outer tube 1. There is. One main electrode 3a of the arc tube 2 is electrically connected to one support 6a, and the other main electrode 3b is connected to a connecting wire 10 via a lead wire 9, and this connecting wire 10 is connected to the stem. 7 and is connected to another inner conductor 8b which is sealed. The one inner conductor 8a is connected to the cap 11, and
The other inner conductor 8b is connected to the eyelet terminal 1 of the base 11.
Connected to 2.

On the other hand, the starting auxiliary electrode 4 is connected to the connecting line 10 via a starting auxiliary resistor 13 and a normally closed bimetal switch 14.

And on one support 6a there is a glow lighting tube 1.
5 is attached via a lighting tube holder 16. One of the pair of lead wires 17a, 17b led from this glow lighting tube 15, 17a
is connected to the support 6a, and the other lead wire 17b is connected to one end of the current limiting resistor 18. The other end of this current-limiting resistor 18 is connected to a connection portion between the bimetal switch 14 and the starting auxiliary resistor 13.

Therefore, the lighting tube 15, the current limiting resistor 18, and the bimetal switch 14 form a series circuit as shown in FIG. It is something that exists.

In such a configuration, when starting the lamp, the bimetal switch 14, the current limiting resistor 18, and the connecting wire 1
0, the other lead wire 17b of the lighting tube 15 is kept at the same potential, whereas the support 6a and the lighting tube 1
5 one lead wire 17a, lighting tube holder 16
etc. have different polarity potentials.

Therefore, the lead wire 17b led from the lighting tube 15 and connected to the current limiting resistor 18 has a distance between the lead wire 17b and another conductive member having a different polarity in the outer tube 1. Among conductive members having different polarity potentials, the spacing is maintained at the minimum. For example, the distance between point A on the lead wire 17b and point B on the lead wire 17a is set to a minimum dimension of 3 to 5 mm within the outer tube 1. Another example is between point A of the lead wire 17b and point C of the lighting tube holder 16, or between point A of the lead wire 17b and the support 6.
It may be between point D and point a. In any case, the polarities between A and B, between A and C, between A and D, etc. are different, and the distance between any one of these pairs has different polarity within the outer tube 1. The distance between the conductive members is set to be smaller than the distance between the conductive members. In this embodiment, between the lead wires 17a and 17b, that is, A-B
The distance between the lead wires 17a and 17b is set to a minimum dimension of about 3 to 5 mm, and the reason why the distance between the lead wires 17a and 17b is set to the minimum dimension is that molding is easy and the minimum dimension can be easily set.

Note that nitrogen gas or a mixed gas of nitrogen gas and other inert gas is contained in the outer tube 1, for example.
Approximately 400 torr is enclosed. Also, current limiting resistor 18
is set to a resistance value of approximately 300Ω.

The operation of the embodiment having such a configuration will be explained.

As shown in FIG. 2, the lamp is connected to a power source 20 via a mercury lamp ballast 19, but since the normally closed bimetal switch 14 is closed at the time of starting, this switch 14 is current limited. A current flows through the resistor 18 and the glow lamp tube 15.
In the glow lighting tube 15 described above, the glow current heats the bimetal inside the lighting tube 15 and opens and closes the lighting tube contacts, thereby disconnecting the ballast 19 via the current limiting resistor 18. . The ballast 19 generates a pulse voltage due to the fluctuation of this blockage current, and this pulse voltage is applied between the starting auxiliary electrode 4 and one of the main electrodes 3a adjacent thereto, and between the two main electrodes 3a, 3.
Administered between b. Therefore, the arc tube 2 will start.

When the arc tube 2 starts, the bimetal switch 14 is heated and opened by the heat from the arc tube 2, thereby opening the series circuit and preventing current from flowing through the lighting tube 15 and the current limiting resistor 18. and auxiliary electrode 4
and the main electrode 3a are kept at the same potential.

The lamp is lit in this manner, but as the life of the lamp progresses, the pulse voltage increases as the inert gas in the lighting tube 15 deteriorates. For example, a lighting tube that generates a pulse voltage of about 1500V at the beginning of its life may generate a pulse voltage of 3000V or more as its life progresses. On the other hand, the arc tube 2 also requires a higher starting voltage as its life progresses, so
Even with a pulse voltage of 3000V, it may not start. For this reason, outer bulb discharge may occur between conductive members of different polarities within the outer bulb 1 to which a pulse voltage of 3000V is applied.

However, in the above embodiment, the outer bulb discharge is always generated using the other lead wire 17b of the lighting tube 15 as a cathode bright spot. That is, in the outer tube 1, between this lead wire 17b and a conductive member of a different polarity, for example, between A and B,
Or, because the distance between A and C or between A and D is set to be the shortest distance, outer tube discharge is not necessarily between A and B, or between A and C, or between A and D due to the nature of the discharge phenomenon. occurs in For example, lighting tube 15
When the minimum interval is between both lead wires 17a, 17b (between A and B), these lead wires 17a,
Since discharge occurs between 17b, the cap 11 → inner conductor 8a → support 6a → one lead wire 17a of the lighting tube 15 (point B) → the other lead wire 17b of the lighting tube 15 (point A) → current limiting Current flows from the resistor 18 to the bimetal switch 14 to the inner conductor 8b to the eyelet terminal 12.

Since such a discharge always makes the connection line between the lighting tube 15 and the current limiting resistor 18, that is, the other lead wire 17b, a bright spot, this discharge current always flows through the current limiting resistor 1.
It will flow through 8. Since the current limiting resistor 18 has a relatively large resistance, it causes a voltage drop, and therefore, the outer bulb discharge caused by the pulse of the lighting tube 15 is stopped instantaneously by this voltage drop effect. In other words, the discharge remains only at the time of pulse generation, and this discharge is no longer connected. This eliminates continuous arc discharge between different conductive members, and prevents melting of the conductive members and destruction of the outer tube.

Experiments have shown that if the resistance value of the current limiting resistor 18 is such that the current value when the contact in the lighting tube 15 is closed is 2 amperes or less, then the discharge between A and B can be sustained. It was found that this can be prevented. In other words, the resistance value of the current limiting resistor 18 is to drop the secondary voltage of the ballast 19, but if the resistance value is such that the current of the lighting tube 15 is regulated to 2 amperes or less, A-B Although it depends on the dimensions between the tubes and the gas conditions inside the outer tube, it serves as a guide to prevent the discharge from continuing.

Note that the present invention is not limited to metal halide lamps, and can be implemented even with high-pressure sodium lamps, for example.

As detailed above, according to the present invention, different polar potentials are applied in the outer tube between the lead wire connecting the lighting tube and the current limiting resistor and the other conductive member having a potential opposite to this lead wire. Since the spacing is the shortest among the conductive members included, the lead wire will definitely become a bright spot when a pulse voltage from the lighting tube is applied and the arc tube does not light up and an outer tube discharge occurs.
Since the discharge current of the discharge that uses this lead wire as a bright spot always flows through the current limiting resistor, the voltage is dropped by this current limiting resistor, and therefore the discharge that uses the lead wire as a bright spot is immediately stopped. . Therefore, the continuation of the outer tube discharge is eliminated, and melting of the conductive member and damage to the outer tube are prevented, resulting in an advantage of extremely high safety.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a front view showing a cross section of the outer tube of a metal halide lamp;
FIG. 2 is a circuit diagram showing the lighting circuit. DESCRIPTION OF SYMBOLS 1... Outer tube, 2... Arc tube, 3a, 3b... Main electrode, 15... Lighting tube, 17a, 17b... Lead wire of lighting tube, 18... Current limiting resistor.

Claims (1)

[Scope of Claims] 1. An arc tube and a starting means for the arc tube are housed in an outer tube, and an inert gas is sealed in the outer tube,
In a metal vapor discharge lamp in which a series circuit consisting of at least a lighting tube and a current limiting resistor is connected in parallel to the lighting tube, the starting means includes a lead wire connecting the lighting tube and the current limiting resistor, and a lead wire connecting the lighting tube and the current limiting resistor. A metal vapor discharger characterized in that a distance between the lead wire and another conductive member in the outer tube having a facing potential is set smaller than a distance between other conductive members in the outer tube having different polarity potentials. electric light. 2. The other conductive member in the outer bulb having the opposing potential is the other lead wire of the lighting tube, and the distance between the pair of lead wires of the lighting tube has different polarity potentials in the outer bulb. The metal vapor discharge lamp according to claim 1, wherein the distance between the conductive members is set smaller than the distance between the conductive members. 3. The metal vapor discharge lamp according to claim 1 or 2, wherein the current limiting resistor has a resistance value such that the lighting tube current is 2 amperes or less.