JPS5932864B2 - high pressure discharge lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high pressure discharge lamp that reduces the applied voltage for restarting and shortens the restart time.

In general, in high-pressure discharge lamps such as high-pressure mercury lamps, metal halide lamps, and high-pressure sodium lamps, the pressure of mercury vapor in the arc tube reaches the diffuse pressure while the lamp is on, so there is a temporary drop in the power supply voltage. According to
Once the lamp goes out, even if the power supply voltage returns to normal,
The lamp cannot start immediately, and the temperature of the arc tube drops, causing
It was impossible to light the lamp until the mercury vapor pressure inside the arc tube decreased to a state where discharge could start.

The time from when the lamp goes out until it can start discharging again is called the restart time, which is 3 to 5 minutes for high-pressure mercury lamps and 8 to 8 minutes for metal halide lamps.
15 minutes, and in high pressure sodium lamps 2-1
A 5 minute restart time is required.

High-pressure discharge lamps that require such a long restart time are extremely inconvenient to use.

In order to shorten this long restart time and restart the engine instantly, a method was conventionally used in which a high voltage of 10 to 35 [KV] was applied between the electrodes to force the restart. In this case, since the applied voltage is extremely high, special dedicated lamps and lighting devices are required, which are expensive and large, and due to the high voltage, when installing the lighting device, There were major restrictions on its handling.

The conventional device will be explained in more detail with reference to FIG.

The inside of the quartz arc tube 1 of a 400 (W) high-pressure mercury lamp, which has main electrodes 2 and 3 at both ends and an auxiliary electrode 4 adjacent to the main electrode 2, is filled with the required amount of mercury and starting auxiliary gas. A certain amount of argon is sealed.

The main electrodes 2 and 3 are connected to the lighting device 12 via leads 8 and 9, respectively.
It is connected to the.

The auxiliary electrode 4 is connected to a lead 9 via a lead 7 and a starting resistor 6 of several tens of kilohms.

Reference numeral 11 indicates a light-transmitting outer tube incorporating the light-transmitting tube 1, and reference numeral 13 indicates a power source.

When the high-pressure mercury lamp configured in this manner is connected to the power source 13 via the lighting device 12 and voltage is applied, a glow discharge occurs between the main electrode 2 and the auxiliary electrode 4 and is controlled by the starting resistor 6. A current flows, and due to the auxiliary effect of this discharge, the discharge between the main electrodes 2 and 3 starts quickly.

The current between the main electrodes 2 and 3 (lamp current) is controlled by a lighting device 12.

Then, about 5 minutes after the start of discharge, a stable lighting state is achieved.

The pressure of mercury vapor inside the arc tube 1 during lighting reaches several atmospheres,
The high-pressure mercury discharge between the main electrodes 2 and 3 is maintained stably.

In this way, the high-pressure mercury lamp reaches a stable lighting state, but if the lamp goes out due to, for example, a temporary drop in the power supply voltage while in this stable lighting state, the power supply voltage will return to normal. However, since the pressure of mercury vapor in the arc tube 1 has reached several atmospheres, this high-pressure mercury lamp cannot immediately start discharging.

In general, high-pressure mercury lamps require 3 to 5 minutes to restart after turning off until discharge starts again.
During this time, the temperature of the arc tube decreases, the mercury vapor pressure decreases accordingly, and the temperature of the arc tube decreases to about 600 ('C1:
] to approximately 150 [°C] before restarting is possible.

The mercury vapor pressure inside the arc tube at this time is approximately 3 (Torr)
It is.

When the relationship between the elapsed time after turning off the high-pressure mercury lamp during stable operation and the discharge starting voltage is measured, the characteristics shown in FIG. 2 are obtained.

Immediately after the lights go out, the discharge starting voltage increases as time passes, and reaches the maximum value after about 1 minute, and the discharge starting voltage is 8 (KV).
The voltage will exceed.

In other words, in order to start discharging in this state, 8 (
It is necessary to apply a high voltage exceeding KV).

As more time passes, the discharge starting voltage gradually decreases, and after about 4 minutes, it returns to normal voltage (for example, 20
At 0 (V), it becomes possible to start discharging, and the rung restarts.

Therefore, in order to restart the lamp at any time that has elapsed since the lamp went out, the lighting device must be equipped with a device that generates a voltage exceeding 8 (KV).

The required voltage to be applied varies depending on the type and size of the lamp (wattage), and a high voltage of 10 to 35 (KV) is practically required.

The inventors investigated in detail the relationship between the mercury vapor pressure in the arc tube, which is the cause of this high restart voltage, and the discharge starting voltage of the lamp, and as a result, the relationship shown in FIG. 3 was obtained.

When the pressure of mercury vapor is about 10' (Torr) or less, that is, when the temperature of the arc tube is about 180 [°C] or less, the firing voltage gradually increases as the mercury vapor pressure increases.
When it exceeds 1 (Torr), the increase becomes large, and furthermore, about 1 Torr.
02 (Torr) or more, that is, the arc tube temperature is about 260 (
℃), the voltage rises rapidly and it becomes impossible to start a discharge with normal voltage.

The pressure of mercury vapor in the arc tube when starting the lamp at room temperature is about 10'' (Torr), and at this mercury vapor pressure, the discharge starting voltage of the lamp is low, so the lamp starts discharging at a normal voltage.

However, when restarting, the mercury vapor pressure within the arc tube during stable lighting has reached several atmospheres to several atmospheres, and the discharge starting voltage is extremely high, so discharge will not start at normal voltage.

Therefore, after the light is turned off, the temperature of the arc tube gradually decreases to about 15
It is necessary to wait until the temperature is below 0 [° C.], that is, until the mercury vapor pressure falls below several Torr, and the discharge can begin.

In order to start discharging under the high vapor pressure of mercury in order to shorten the restart time without waiting for the mercury vapor pressure in the arc tube to drop below several Torr, a significantly high voltage must be applied to the lamp. must be applied.

In particular, when the vapor pressure of mercury is 100 [Torr:] or more, the discharge starting voltage rises rapidly, making it impossible to start discharge at a normal voltage.

The inventors investigated various methods for starting discharge under a high mercury vapor pressure of 100 Torr or more with a relatively low voltage. 10-60 at the tip
° Bend and wind a filament around this bent electrode core wire, extend this filament from the electrode tip side toward the end of the arc tube, ′- With this filament heated by electric current, apply a voltage between the electrodes. It has been found that the method of energizing and starting is extremely effective.

This invention was made based on the above knowledge, and 10
When restarting under a high mercury vapor pressure of 0 (Torr) or higher, at least one of the electrode core wires provided at both ends of the arc tube is bent at an angle of ~60°, and the bent electrode core wire is By winding a filament and extending the filament from the tip of the electrode toward the end of the arc tube, and applying the required voltage between the electrodes while heating the filament with an electric current, the initiation of the discharge is significantly facilitated. The present invention provides a new high-pressure discharge lamp that shortens the restart time and significantly reduces the voltage required for restart.

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

FIG. 4 shows a schematic circuit diagram of the high pressure discharge lamp of the present invention, and FIG. 5 shows an enlarged view of the electrode portion.

In these figures, the main electrodes 2 and 3 are arranged at both ends, the tip of the core wire 14 of one of the main electrodes 2 is bent by 10 to 60 degrees, and the filament 5 is wound around the bent main electrode core wire 14. Inside the quartz arc tube 1 of the 400 (W) high pressure mercury lamp, the filament 5 is extended from the main electrode tip side toward the arc tube end, and the tip of the filament 5 is wound around the auxiliary pole core wire 15. It is filled with the required amount of mercury and an appropriate amount of argon, which is a starting aid gas.

Assuming that the angle between the central axis of the main electrode core wire 14 and the central axis of the bent tip is θ, this θ needs to be in the range of 10 to 60'.

The main electrodes 2 and 3 are connected to the lighting device 12 via leads 8 and 9, respectively.
It is connected to the.

The filament 5 connected to the main electrode 2 is connected to a lighting device 12 via a lead 10.

Reference numeral 11 indicates a translucent outer tube containing the arc tube 1, and 13 indicates a power source.

When a voltage is applied to the high-pressure mercury lamp configured in this way from the power source 13 via the lighting device 12, the main electrodes 2 and 3 are immediately turned on.
A discharge between the main electrodes 2 and 3 starts, and a current controlled by the lighting device 12 flows between the main electrodes 2 and 3.

Then, about 5 minutes after the start of discharge, a stable lighting state is achieved.

The pressure of mercury vapor inside the arc tube 1 during lighting reaches several atmospheres,
The high-pressure mercury discharge between the main electrodes 2 and 3 is maintained stably.

When restarting the high-pressure mercury lamp having the above configuration after it has been turned off, first, a current is applied to the filament 5 from the preheating circuit built into the lighting device 12 through the leads 10 and 8 to heat the filament 5. Then, a voltage from the lighting device 12 is applied between the main electrodes 2 and 3 through the bridges 8 and 9 to start discharge.

The temperature of the filament 5 at this time has a large effect on the discharge starting voltage.

FIG. 6 shows the relationship between the discharge starting voltage and the filament temperature one minute after the lamp is turned off in this high-pressure mercury lamp. The discharge starting voltage for restart under mercury vapor pressure was measured one minute after the lights were turned off.

As is clear from this figure, the temperature of filament 5 is 5
When the temperature exceeds 00[:'C, 1, the discharge starting voltage decreases rapidly, and when the temperature exceeds 600 (°C), the discharge starting voltage gradually decreases as the filament temperature increases.

Conventionally, a high voltage of 10 [Kv] or more was applied to shorten the restart time or to restart the lamp immediately after turning off the light, but in the method of the present invention, the tip of the electrode core wire is Electron emission from the filament can be easily performed by bending the filament by ~60", winding the filament around the bent electrode core wire, extending the filament from the tip of the electrode toward the end of the arc tube, and heating it. Since a voltage is applied between both electrodes to restart the discharge, it is extremely easy to start the discharge, and even under mercury vapor of 100 Torr': The starting voltage becomes approximately 3.000 (V) or less, which is a significant decrease.

Therefore, the high voltage generator required for restarting is not large and expensive as in the past, but rather a relatively inexpensive one, and because the generated voltage is low, it is necessary to install a lighting device. The wiring restrictions associated with this do not need to be as severe as in the past, and can be used with the same restrictions as in the case of ordinary high-pressure discharge lamps.

In addition, by adopting an electrode with this configuration, it is possible to easily install the filament in the limited space at the end of the arc tube, and since the tip of the core wire is bent, it is easy to start the filament. Since the arc spot that is sometimes formed on the filament quickly moves to the tip of the core wire, it is possible to easily restart the lamp without sacrificing various characteristics of the lamp during stable lighting.

Furthermore, the bending angle θ of the tip of the electrode core wire is 10
If the angle is outside the range of ~60°, a sufficient effect will not be obtained, and the arc spot will remain on the filament for a long time, making it difficult to move to the tip of the core wire.

The high-pressure discharge lamp of this invention is designed with the reduction of the restart voltage in mind first, so that during normal starting from room temperature, where the discharge starting voltage is low, discharge can be started without heating the filament. However, at this time as well, the filament may be heated and started in the same way as when restarting.

In the above embodiment, a double coil made of double-wound tungsten wire was used as the filament, but the filament is not limited to a double coil; a triple coil or a strand of wire may be used as it is without being made into a coil.

Further, instead of providing the filament only on one electrode, a filament made of a heat-resistant metal may be provided on both electrodes disposed at both ends of the arc tube, and both filaments may be heated simultaneously.

In this way, the discharge starting voltage can be further lowered than in the case where only the filament provided on one side is heated.

The upper limit of filament temperature during heating is 2300 ('C)23
If the temperature exceeds 0.00°C, evaporation of the electrode material and accompanying breakage of the filament are likely to occur.

In order to achieve the object of the present invention more effectively, the voltage drop between both ends of the filament may be set to 11 (V) or more when the filament is heated by electric current.

The voltage drop across the filament during heating is 11 (V)
At this point, a discharge occurs between both ends of the filament (a discharge that occurs only at the ends of the arc tube), and not only is the electrode heated to the required temperature, but this discharge also releases abundant ions and electrons into the discharge space inside the arc tube. This makes it easier to initiate the discharge between the main electrodes and restart it under high vapor pressure of mercury.

Although the above embodiment describes a 400 (W) high pressure mercury lamp, this invention is applicable not only to high pressure mercury lamps of various sizes and lamp powers, but also because of the high mercury vapor pressure in the arc tube, which reduces the restart time. Similar effects can be obtained when applied to high-pressure discharge lamps such as long metal halide lamps and high-pressure sodium lamps.

As described above, this invention provides that when restarting under a mercury vapor pressure of 100 (Torr) or more (that is, the arc tube temperature is about 260 [°C] or more), the electrodes provided at both ends of the arc tube , the tip of at least one electrode core wire is 1
A filament is wound around the bent electrode core wire by 0 to 60 degrees, and the filament is extended from the tip of the electrode toward the end of the arc tube. While the filament is heated with an electric current, the required distance between the electrodes is By applying a suitable voltage, the start of discharge is significantly facilitated and restart time is shortened even under high mercury vapor pressure, and
By significantly lowering the voltage required for restarting the lamp after it has been turned off, it is possible to operate high-pressure discharge lamps with a comparatively large, low-cost lighting device, without the need for the conventional large and expensive lighting device. This provides a high-pressure discharge lamp that can be restarted, has high practical value, and is highly effective.

[Brief explanation of the drawing]

Figure 1 is a schematic circuit diagram of a conventional high-pressure discharge lamp, Figure 2 is a characteristic diagram showing the relationship between the elapsed time after the high-pressure discharge lamp goes out and the discharge starting voltage, and Figure 3 is a diagram showing the relationship between the mercury vapor pressure in the arc tube and the discharge. FIG. 4 is a schematic circuit diagram showing an embodiment of the high pressure discharge lamp of the present invention, FIG. 5 is an enlarged view of the electrode portion of FIG. 4, and FIG. 6 is a diagram showing the relationship between the starting voltages. FIG. 2 is a characteristic diagram showing the relationship between the temperature of a heating filament and the discharge starting voltage of a high-pressure discharge lamp. In the figure, 1 is an arc tube, 2 and 3 are main electrodes, 4 is an auxiliary electrode, 5 is a filament, θ is a bending angle, 11 is an outer tube, and 12 is a lighting device. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. In a high-pressure discharge lamp equipped with an arc tube having electrodes at both ends and mercury sealed inside, the tip of at least one electrode core wire of the electrodes provided in the arc tube. 10
Bend ~60° and wind a filament around the bent electrode core wire, extend this filament from the electrode tip side toward the end of the arc tube, and start when the mercury vapor pressure in the arc tube is 100 (Torr) or higher. The high-pressure discharge lamp is started by applying a voltage between the two electrodes while the filament is heated by an electric current. 2 The temperature of the above filament during heating is 500℃
A high-pressure discharge lamp according to claim 1, characterized by the above-mentioned features. 3. The high-pressure discharge lamp according to claim 1 or 2, characterized in that the filament is heated and at the same time discharge occurs between both ends of the filament.