JPH07118303B2 - Metal halide lamp - Google Patents

Description

TECHNICAL FIELD The present invention relates to a metal halide lamp having a built-in lighting tube.

2. Description of the Related Art Metal halide lamps are used in place of high-pressure mercury lamps because they have higher efficiency and higher color rendering than high-pressure mercury lamps. Various attempts have been made to turn it on.

As an example, by incorporating a starting means together with an arc tube in the outer tube and using a glow lighting tube as the starting means, a pulse voltage generated by the glow lighting tube is applied to the arc tube when the lamp is started. A starter has been proposed (JP-A-55-130064 and JP-A-57172).
694 publication).

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in general, those using a glow ignition tube as a starting means have an initial ignition tube generation pulse voltage of 1000 V or more from the viewpoint of startability, and the ignition tube generation The pulse voltage has the property of becoming higher as the lamp life advances. In other words, the ignition tube itself, as the lamp life progresses,
The peak value of the generated pulse voltage gradually increases due to the reason that the purity of the enclosed gas in the lighting tube is lowered by the sputtering of the contacts and the impure gas is released from the glass bulb or the like. In addition to this, the starting voltage of the arc tube increases as the life of the arc tube increases.

Therefore, the pulse voltage generated in the ignition tube increases with the lapse of life, and if the arc tube does not light immediately due to a restart or the like without this, discharge in the outer tube is likely to occur. A so-called outer tube discharge is caused between portions, that is, between the conductive members having different polar potentials. Such discharge in the outer tube is likely to occur especially when a sealed gas containing neon having a low dielectric breakdown voltage is used in the outer tube, and once generated, the discharge is sustained, the conductive member is melted, and the outer tube is further discharged. There was a problem of causing damage.

The present invention has been made in order to solve such problems, and provides a metal halide lamp having good startability, prevention of discharge in an outer bulb, and improved life and safety.

Means for Solving the Problems In order to solve this problem, the metal halide lamp of the present invention has an arc tube having electrodes at both ends in an outer tube, a lighting tube in parallel with the arc tube, and a current limiting resistor. And a circuit in which a normally closed thermal response switch is connected in series, and at least neon gas is sealed in the outer tube and the arc tube.
The initial starting pulse voltage generated by the lighting tube and the current limiting resistance is 700 V or more and less than 1000 V.

Effect According to the present invention, since at least neon gas is enclosed in the arc tube, the startability is improved. However, when neon gas is enclosed in the arc tube, neon penetrates through the arc tube wall made of, for example, quartz, which is in a high temperature state during lighting, so it is necessary to also enclose at least neon simple substance or a mixed gas containing neon in the outer tube. There is. However, the present invention solves the above problems caused by enclosing a neon-based gas in the outer tube by setting the initial starting pulse voltage generated by the lighting tube and the current limiting resistance to 700 V or more and less than 1000 V. can do.

Embodiment FIG. 1 is a front view of a metal halide lamp which is an embodiment of the present invention. In the figure, a quartz arc tube 2 is provided inside an outer tube 1.
Is provided. At both ends of the arc tube 2, main electrodes 3a, 3b and a starting auxiliary electrode 4 are provided close to one main electrode 3a. The auxiliary auxiliary electrode 4 may not be used in some cases. In addition, in the arc tube 2, mercury,
A predetermined amount of Penning gas mainly containing metal halide and neon is enclosed. One main electrode 3a in the arc tube 2 is electrically connected to the stem introduction line 7 via the connection line 5, and the other main electrode 3b is electrically connected to the stem introduction line 8 via the connection line 6. Has been done. One stem introduction line 7 is connected to the top terminal of the base 9, and the other stem introduction line 8 is connected to the side portion of the base 9.

On the other hand, the auxiliary starting electrode 4 is connected to the stem lead-in wire 8 via the auxiliary auxiliary resistor 10 and the normally closed bimetal switch 11. The lighting tube 12 is held by the stem lead-in wire 7. Of the pair of lead wires 13a and 13b led out of the lighting tube 12, one lead wire 13a is a current limiting resistor 14a.
Is connected to one end of. The other end of the current limiting resistor 14 is connected to the connection portion between the bimetal switch 11 and the starting auxiliary resistor 10.

Therefore, the lighting tube 12, the current limiting resistor 14 and the bimetal switch 11 form a series circuit, and the series circuit is connected in parallel to the arc tube 2 and provided inside the outer tube 1.

Hereinafter, specific examples of the present invention will be described.

An arc tube with a main electrode distance of 80 mm, an appropriate amount of mercury of about 100 mg, scandium iodide and sodium iodide, and a rare gas of neon (99.5%)-argon (0.5%) of about 60 mb was used. In the configuration shown in the figure in which the outer tube is filled with 60% of neon and 40% of nitrogen, the resistance value of the current limiting resistance is changed to variously change the starting pulse voltage generated by the lighting tube and the impedance element. It was 10 lamps were made for each. 1000 made in this way
W metal halide lamp blinks on (5.5 hours on, 0.5 hours off), starting characteristics up to 4000 hours cumulative lighting time,
The occurrence of discharge in the outer tube and the change in pulse voltage at restart were investigated. The results are shown in the table below.

As is clear from the above table, in the initial pulse voltage range of 700 V or higher and less than 1000 V, the lamp startability, rise in pulse voltage, discharge rate in the outer tube, fault rate, and outer tube damage rate are all It is good. However, when the initial pulse voltage is lower than 700 V, the rise rate of the pulse voltage and the occurrence rate of the discharge in the outer tube are good, but the startability is poor and the start failure occurs during the life. Also, when the initial pulse voltage is 1000 V or higher, the startability is improved by enclosing neon-argon Penning gas in the arc tube, but the pulse voltage rises sharply during the life and the occurrence rate of discharge in the outer tube and , The outer tube damage rate becomes high.

It is considered that the reason why the metal halide lamp having the initial pulse voltage in the range of 700 V or more and less than 1000 V has excellent characteristics is as follows.

That is, if the initial pulse voltage is less than 700 V, even if the arc tube is filled with a Penning gas consisting mainly of neon, it is easy to start at 0 hours of lighting, but impure gas or the like remains in the arc tube during its life. Occurs, raises the starting voltage, and finally causes a starting failure. The initial pulse voltage is 10
If it is more than 00V, a high kick voltage will be applied between the contacts of the bimetal switch. Under such conditions, sputtering of the lighting tube becomes intense, impure gas is released from the contact material, glass bulb, etc., and the pulse voltage rises. As the pulse voltage increases, discharge in the outer tube occurs during the life test, especially when the ignition tube is operated when the metal vapor pressure in the arc tube is high and it is difficult to start, such as restart. When the pulse voltage further increases, the rate of occurrence of discharge in the outer tube also increases, which eventually leads to defects and damage to the outer tube.

On the other hand, in the range where the initial pulse voltage is 700 V or more and less than 1000 V, such a problem does not occur at all, and it is possible to improve the pulse voltage, discharge in the outer tube, non-lighting, and damage to the outer tube. It is a thing.

The above embodiment is an example of a metal halide lamp with a lamp power of 1000 W, but by further experiments, the present invention is:
It was confirmed that similar effects can be obtained in low wattage metal halide lamps such as 100W, 250W, 300W, 400W, 700W.

Effect of the Invention As described above, the present invention can provide a metal halide lamp having a long life by suppressing the rise of the pulse voltage throughout the life, preventing the discharge in the outer bulb, the starting failure and the outer bulb being damaged. It is a thing.

[Brief description of drawings]

FIG. 1 is a front view of a metal halide lamp which is an embodiment of the present invention. 1 ... Outer tube, 2 ... Arc tube, 3a, 3b ... Main electrode, 11 ...
Normally closed type bimetal switch, 12 …… lighting tube, 14 …… current limiting resistance.

Claims (1)

[Claims] 1. An arc tube having electrodes on both ends in an outer tube,
A lighting tube, a circuit in which a current limiting resistor and a normally-closed heat-actuated switch are connected in series are provided in parallel with the arc tube, and at least neon gas is sealed in the outer tube and the arc tube. A metal halide lamp characterized in that an initial starting pulse voltage generated by the current limiting resistance is 700 V or more and less than 1000 V.