JPH0350380B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a high pressure metal vapor discharge lamp incorporating a thermally responsive switch type starting device.

[Technical background of the invention and its problems]

High-pressure metal vapor discharge lamps with arc tubes made of translucent ceramics, such as polycrystalline alumina ceramics or metal oxide single crystals such as ruby and sapphire, etc. For example, high-pressure sodium lamps have xenon, etc. in the alumina ceramic arc tube bulb. It consists of an arc tube filled with a rare starting gas, mercury, and sodium sealed inside an outer tube with a cap attached to one end.It has been attracting more attention in recent years as a power-saving light source because it has extremely high luminous efficiency compared to high-pressure mercury lamps. has been done.

This lamp had a high starting voltage for the arc tube, and could not be started using commercial power supply voltage, requiring an expensive, specialized ballast with a starting device that generated high-voltage pulses. In response to this, in recent years, a proximate conductor has been disposed on the outer surface of the arc tube, and a means has been developed to facilitate starting by utilizing the potential difference generated between the proximal conductor and one electrode having an opposing potential. A comparatively inexpensive ballast for high-pressure mercury lamps that facilitates starting by incorporating a starting device consisting of a resistance heating element in the tube and a normally closed type thermally responsive switch that is activated by being heated by the resistance heating element. Lamps that can be started by

The starting device built into the outer tube heats the thermally responsive switch using a resistance heating element, and superimposes the high voltage pulse generated when the thermally responsive switch opens on the secondary voltage of the ballast, causing the arc tube to open. This makes starting easier by applying a voltage between the electrodes, but when the thermally responsive switch opens, the resistance heating element connected in series with it stops generating heat, so the thermally responsive switch is cooled. It returns to its original closed state, and current flows through the starter again. As a result, the current supplied to the arc tube connected in parallel with the starter device decreases, resulting in problems such as the arc tube dying out or the discharge becoming unstable. Therefore, it is essential to prevent the thermally responsive switch from returning to the closed state after the lamp has started, and for this reason, the thermally responsive switch is designed to maintain the open state by receiving radiant heat from the arc tube. It is installed near the arc tube.

However, for example, at the end of the lamp's life, if the electron radioactive material coated on the electrodes dries up and the arc tube goes into a malfunction state, the thermally responsive switch cannot receive the radiant heat from the arc tube, so it must be cooled down. The switch returns to its original closed state, and current flows through the starting circuit again, causing the thermally responsive switch to operate, causing the switch to repeat its opening and closing operations. In such a situation, high-voltage pulses would be repeatedly applied to the ballast and wiring, which could rarely cause dielectric breakdown.

In particular, this type of lamp is often installed in a high place, so even if it becomes defective, it cannot be easily replaced, and it may be left energized for a long period of time, during which time the ballast and wiring It is quite conceivable that the insulation of the

[Purpose of the invention]

The present invention was made in consideration of the above circumstances, and
The purpose of the present invention is to provide a high-pressure metal vapor discharge lamp with a built-in starting device that can prevent dielectric breakdown in lighting circuits such as ballasts and wiring even if the arc tube goes into a non-lighting state. do.

[Summary of the invention]

The present invention is a high-pressure steam discharge lamp that incorporates a starting device consisting of a translucent ceramic arc tube, a thermally responsive switch, and a resistance heating element, in which a pair of conductors are disposed oppositely on an insulator at a distance of 0.5 to 5 mm. An insulating gap made of
In addition, since they are electrically connected in parallel, in the unlikely event that the thermally responsive switch repeatedly opens and closes, the contact material of the thermally responsive switch will be placed on the insulating gap. It scatters and adheres to the insulation resistance, lowering its insulation resistance, making it appear as if a resistor is connected in parallel with the starter, and lowering the pulse voltage generated when the starter is activated, thereby preventing dielectric breakdown of the lighting circuit. It is possible.

[Embodiments of the invention]

It has been known that connecting a resistor in parallel with the starter changes the value of the pulse voltage generated when the starter is activated. That is, the smaller the value of the resistance, the lower the pulse voltage. For example, when no resistor is connected, a pulse voltage as high as 4 to 6 kV is generated, but when connected in parallel,
If a 10 kΩ resistor is connected, the pulse voltage will drop to 3.5 to 5.5 kV, and if a 1 kΩ resistor is connected, the pulse voltage will drop to 2 to 4 kV.

By the way, as a pair of contacts of a thermally responsive switch in a starter device repeatedly opens and closes, the metal material that makes up the contacts becomes extremely fine particles, scatters, and forms a thin film on nearby components. The film thickness gradually increases. However, the material metal for the above-mentioned contacts is usually composed of high melting point metals such as tungsten, but these metals do not exhibit conductivity in the form of very thin films, but gradually become more conductive when the film thickness exceeds several hundred Å. It exhibits electrical conductivity, and when it exceeds 1000 Å, it exhibits a good conductive state.

The inventors focused on this point and placed 0.5
By installing an insulating gap consisting of a pair of conductors facing each other with a gap of 5 mm in the vicinity of the thermally responsive switch and electrically in parallel, the contact material will not be exposed to scattering to the extent that occurs during the normal life of the lamp. The insulation of the surface of the gap provided in the insulating gap is not impaired by this process, and therefore it does not affect the pulse voltage.
When a thermally responsive switch repeatedly opens and closes continuously, the amount of contact material that adheres to the gap between the insulating gap increases rapidly, and the insulation resistance of the gap decreases, causing the switch to act as a starting device. It has been found that a resistor is connected in parallel with the starter, thereby reducing the pulse voltage generated when the starter is activated.

Next, details of the present invention will be explained with reference to an illustrated embodiment. Figure 2 shows a 360W rated high-pressure sodium lamp with a built-in starter, and Figure 1 shows the starter. 1 is an outer tube with a high vacuum inside and a cap 2 attached to one end, and 3 is an outer tube with a cap 2 attached to one end. A closing body 6 that supports electrodes 5a and 5b at both ends of a light-transmitting ceramic tube, for example, an alumina ceramic tube 4, is an arc tube.
a and 6b, and xenon gas, mercury, and sodium are sealed inside as rare gases for starting. Reference numeral 7 denotes a starting device electrically connected in parallel with the arc tube 3, which consists of a thermally responsive switch 9 assembled on an insulating substrate 8 and a coil filament-shaped resistance heating element 10 electrically connected in series thereto. .

Of the pair of tungsten contacts 11a and 11b of the thermally responsive switch 9, the fixed contact 11a is connected via a support member 12, and the movable contact 11b is connected to bolts 15a and 15b via a bimetal piece 13 and a bimetal piece support member 14, respectively. Insulated board 8
The bolts 15a are attached to the arc tube support 20, which will be described later, and the bolts 15b are attached to the resistance heating element 10.
are connected to one end of each.

Moreover, between both the supporting members 12 and 14, there is provided a contact point 11a, which is electrically parallel to the thermally responsive switch 9.
An insulating gap 23 is attached at a distance l10 mm from the junction part 16 of 11b. The insulating gap 23 consists of a pair of conductors 26, 26 made of conductive carbon coating, for example, placed on an insulator 24 made of a round bar of mullite, with a gap 25 of 1 mm between them.
These conductors 26, 26 are connected to both support members 12, 26 of the thermally responsive switch 9 via metal gaps 27, 27 and lead wires 28, 28, respectively.
14.

Reference numeral 17 denotes a stem sealed to one end of the outer tube 1, and internal lead-in wires 18 and 19 are sealed. They are each connected to a support 20, and this support 20 also serves as a power supply to one electrode 5a. Also, one end of the other internal lead-in wire 19 is connected to the base 2.
The other end is connected to the top portion 2b of the electrode 5b, and the other end is connected to the other electrode 5b. 21 is a nearby conductor, which is connected to the arc tube 3
is disposed along the longitudinal direction on the outer surface of the
It is connected to the arc tube support 20, which also serves as a power supply to the arc tube.

Although a lamp with such a configuration is not shown,
When connected to an AC power source via a single-choke type mercury lamp ballast for a 200V class AC power source, both contacts 11a and 11b of the thermally responsive switch 9 are closed before starting the lamp, so the resistance heating element 10 has approximately A current of 0.77 A is applied to generate heat, which causes the bimetal piece 13 to bend and open both contacts 11a and 11b. This kick voltage at the time of opening generates a high voltage pulse of 4 to 6 kV in the ballast, and the application of this high voltage pulse causes a sudden change between the adjacent conductor 21 and one electrode 5b having an opposing potential. A potential gradient is generated, which promotes the generation of arc discharge within the arc tube 3, leading to lighting.

Note that while the lamp is lit, the thermally responsive switch 9 receives radiant heat from the high temperature arc tube 3 and closes both contacts 11a,
11b remains open and will not be activated again.

For example, at the end of the life of such a lamp, the electrode 5
When the electron radioactive material applied to the terminals a and 5b is depleted and the arc tube 3 falls into a malfunction state, the thermally responsive switch 9 repeats the opening and closing operations as described above, but the contact 11
Since the distance l between the junction 16 of a and 11b and the surface of the gap 25 of the insulating gap 23 is set to an appropriate value of 10 mm, the surface of the gap 25 is covered with the tungsten coating of the contact material deposited by scattering. As a result, its insulation properties are reduced, and as a result, a resistor (the above-mentioned tungsten film) is connected in parallel to the starter 7 in terms of the circuit, which results in a reduction in the pulse voltage generated by the activation of the starter. Therefore, even if a pulse voltage is repeatedly applied to the ballast or wiring, there will be no dielectric breakdown of the ballast or wiring.

In the above embodiment, the junction part 16 of both contacts 11a, 11b of the thermally responsive switch 9 and the insulating gap 2
The distance l from the gap 25 of 3 was set to 10 mm, but it is preferable that this distance l be in the range of 7 mm to 15 mm. If it is less than 7 mm and too close, the amount of contact material deposited on the gap 25 due to scattering will increase. If the rate of increase in the lamp becomes too fast, the pulse voltage will drop before the life of the lamp, making it difficult to start the lamp. On the other hand, if it exceeds 15mm, the distance will be too much, so
Conversely, the rate of increase in the amount of contact material deposited by scattering into the gap 25 of the insulating gap 23 becomes too slow, and the resistance value of the gap 25 does not easily decrease.
Even when the arc tube 3 falls into a malfunction state, the pulse voltage does not drop, making it difficult to completely prevent dielectric breakdown of the ballast and wiring.

Also, a pair of conductors 26, 2 of the insulating gap 23
The gap 25 of 6 was set to 1 mm, but this is 0.5 mm ~
It is preferable to set it within the range of 5 mm. If the gap is too short (less than 0.5 mm), the gap 25 has to maintain a certain level of electrical insulation during the life of the lamp, which is a problem. Since the distance from the junction part 16 is different at both ends of the gap 25, the film thickness of the contact material deposited in the gap 25 also differs at both ends and becomes non-uniform, which causes the arc tube 3 to not light up. Even if a situation arises in which the thermally responsive switch 9 repeatedly opens and closes, the electrical insulation of the gap 25 will not drop rapidly, and therefore the pulse voltage will not be able to drop rapidly. Undesirable.

It should be noted that the present invention is not limited to the above-mentioned embodiments; for example, various modifications can be made to the structure and shape of the thermally responsive switch, and the mounting position of the insulating gap 23 is not limited to between both ends of the thermally responsive switch 9. For example, both ends of the arc tube 3 may be connected via lead wires. moreover,
The lamp types are not limited to high-pressure sodium lamps, but can also be applied to other high-pressure metal vapor discharge lamps with built-in starting devices, such as lamps filled with other alkali metals or lamps filled with metal halides. .

〔Effect of the invention〕

As described in detail above, in the present invention, an insulating gap is provided near the thermally responsive switch of the starter and electrically in parallel with it, so that if a malfunction occurs at the end of the lamp life, only the thermally responsive switch is activated. Even if repeated activation occurs, the pulse voltage generated at this time can be made lower than the initial value, so there is no dielectric breakdown in the ballast or wiring, making it safe to use. A high-pressure metal vapor discharge lamp with a built-in starting device is obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the starting device portion of a high-pressure sodium lamp with a built-in starter device, which is an embodiment of the present invention, and FIG. 2 is a block diagram of the entire lamp. 1... outer tube, 3... arc tube, 7... starting device,
9...Thermal response switch, 10...Resistive heating element, 1
1a, 11b...Contact points of thermally responsive switches, 16...
...Intersection of both contacts, 23...Insulating gap, 24
... Insulator of insulated gap, 25 ... Gap part of insulated gap, 26 ... Conductor of insulated gap, 27
...Insulated gap metal cap, 28...Insulated gap lead wire.

Claims (1)

[Claims] 1. In a high-pressure metal vapor discharge lamp with a built-in arc tube, a thermally responsive switch, and a starting device consisting of a resistance heating element, an insulator consisting of a pair of conductors placed opposite each other on an insulator with a distance of 0.5 to 5 mm. gap,
A high-pressure metal vapor discharge lamp with a built-in starting device, characterized in that it is installed near the thermally responsive switch and electrically connected in parallel.