JPH0151853B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention shortens the restart time of a high pressure discharge lamp by lowering the starting voltage under high pressure mercury vapor pressure.

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 inside the arc tube reaches several atmospheres while the lamp is on, so the power supply voltage may temporarily drop. As a result, 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 the pressure of mercury vapor inside the arc tube to drop to a state where it can start discharging. Until then, it was impossible to turn on the light. The time from when the lamp goes out until it can start discharging again is called the restart time, and it takes 3 to 5 minutes for high-pressure mercury lamps, 8 to 15 minutes for metal halide lamps, and 8 to 15 minutes for high-pressure sodium lamps. , a restart time of 2 to 15 minutes 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 has conventionally been used in which a high voltage of 10KV to 35KV is applied between the electrodes to force the restart. However, since the applied voltage is extremely high, this method requires special dedicated lamps and lighting devices, which are expensive and large, and due to the high voltage, it is difficult to install the lighting device. , there were major restrictions on its handling.

This invention has been made in view of the above points, and when restarting immediately after turning off the light, at least a portion of at least one of the electrodes provided at both ends of the arc tube is heated, and the electrode portion during heating is heated. By applying the required voltage between the above electrodes at a temperature of 500 to 2300 [℃], it is possible to significantly facilitate the initiation of discharge, shorten the restart time, and reduce the voltage necessary for restart. The object of the present invention is to provide a new high-pressure discharge lamp that significantly reduces the

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

FIG. 1 shows a schematic circuit diagram of a conventional high pressure discharge lamp, and FIG. 2 shows a schematic circuit diagram of a high pressure discharge lamp of the present invention.

In FIG. 1, main electrodes 2 and 3 are provided at both ends,
400 [W] with auxiliary electrode 4 adjacent to main electrode 2
The quartz arc tube 1 of the high-pressure mercury lamp is filled with a required amount of mercury and an appropriate amount of argon as a starting aid gas. Main electrodes 2 and 3 are lead 8,
It is connected to the lighting device 12 via 9. The auxiliary electrode 4 is connected to a lead 9 via a connecting tube 7 and a starting resistor 6 of several tens of kilohms.

Reference numeral 11 indicates a translucent outer tube in which the arc tube 1 is incorporated.

As shown in FIG. 1, when the high-pressure mercury lamp configured in this way is connected to the power source 13 via the lighting device 12 and voltage is applied, glow discharge occurs between the main electrode 2 and the auxiliary electrode 4. However, a current controlled by the starting resistor 6 flows, and due to the effect of assisting the discharge, the discharge between the main electrodes 2 and 3 starts promptly. The current between the main electrodes 2 and 3 (lamp current) is controlled by the lighting device 12. Then, about 5 minutes after the start of discharge, a stable lighting state is achieved. The pressure of mercury vapor within the arc tube 1 during lighting reaches approximately 5 atmospheres, and the high-pressure mercury discharge between the main electrodes 2 and 3 is maintained stably.

In this way, the high-pressure mercury lamp becomes in 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 reaches several atmospheres, the high-pressure mercury lamp cannot immediately start discharging.

Generally, in the case of a high-pressure mercury lamp, it takes 3 to 5 minutes to restart the lamp after it goes out until discharge starts again, and during this time the temperature of the arc tube decreases.
Accordingly, the mercury vapor pressure decreases, and restart is only possible when the arc tube temperature drops from about 600°C during lighting to about 150°C.

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

When we measure the relationship between the elapsed time after turning off a high-pressure mercury lamp that is stably lit and the discharge starting voltage, the third
It exhibits the characteristics shown in the figure. Immediately after the light is turned off, the discharge starting voltage increases as time passes, and reaches the maximum value after about 1 minute, and the discharge starting voltage becomes a high voltage exceeding 8 [KV].

That is, in order to start discharge in this state, it is necessary to apply a high voltage exceeding 8 [KV].

As more time passes, the discharge starting voltage gradually decreases, and after about 4 minutes or more, it becomes possible to start discharging at a normal voltage (for example, 200 V), and the lamp restarts.

Therefore, in order to restart the lamp at any time that has elapsed since it went out, the lighting device must be
A device that generates a voltage exceeding [KV] must be provided. The required voltage to be applied varies depending on the type and size (wattage) of the lamp, and in practice, a high voltage of 10 [KV] to 35 [KV] is required.

The inventors studied 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. 4 was obtained.
If the pressure of mercury vapor is less than about 10 ¹ [Torr], that is,
When the temperature of the arc tube is about 180 [℃] or less, the discharge starting voltage increases gradually as the mercury vapor pressure rises, and when it exceeds 10 ¹ [Torr], the increase becomes large, and further increases to about 10 ² [Torr]. In other words, the arc tube temperature is approximately
When the temperature exceeds 260 [℃], the temperature rises rapidly and it becomes impossible to start discharge at normal voltage.

The pressure of mercury vapor in the arc tube when starting a lamp at room temperature is approximately 10 ^-3 [Torr], and the lamp's discharge starting voltage is low within this mercury vapor pressure range, so the lamp will not discharge at normal voltage. Start. However, when restarting, the mercury vapor pressure within the arc tube during stable lighting reaches several to ten-odd atmospheres, and the discharge starting voltage is extremely high, so discharge will not start at normal voltage. Therefore, after the light is turned off, it is necessary to wait until the temperature of the arc tube gradually decreases to below about 150°C, that is, the mercury vapor pressure drops to below several Torr, and then the discharge can begin.

In order to shorten the restart time without waiting for the mercury vapor pressure in the arc tube to drop below a few Torr, the discharge can be started at a high vapor pressure of mercury.
Significantly higher voltages must be applied to the lamp.

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

The inventors used 100 lights as an example of relighting immediately after lights out.
As a result of various studies on how to start a discharge under a high mercury vapor pressure of [Torr] or more at a relatively low voltage, we found that at least a portion of at least one of the electrodes provided at both ends of the arc tube is heated. However, they discovered that the method of starting the engine by applying a voltage between the electrodes was extremely effective.

In FIG. 2 showing an embodiment of the present invention, main electrodes 2 and 3 are arranged at both ends, and a filament 5 made of tungsten is connected to the main electrode 2.
Inside the quartz arc tube 1 of the 400 [W] high-pressure mercury lamp, a required amount of mercury and an appropriate amount of argon, which is a starting aid gas, are sealed. The main electrodes 2 and 3 are connected to a lighting device 12 via leads 8 and 9, respectively.

The lighting device 12 includes a high voltage power supply 15 for applying high voltage to the main electrodes 2 and 3, a heating body power supply 14 for heating the filament 5, and a lamp current control circuit 16.

The filament 5 connected to the main electrode 2 is
It is connected via a lead 10 to a heating body power source 14 as a preheating circuit built into the lighting device 12 .

Reference numeral 11 indicates a translucent outer tube in which the arc tube 1 is incorporated.

As shown in FIG. 2, the high-pressure mercury lamp of the present invention constructed in this manner is connected to a power source 13 via a ballast 12 and voltage is applied, and a discharge between the main electrodes 2 and 3 immediately starts. A current controlled by a current control circuit 16 built into 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 within the arc tube 1 during lighting reaches approximately 5 atmospheres, and the high-pressure mercury discharge between the main electrodes 2 and 3 is maintained stably.

When restarting the high-pressure mercury lamp of the present invention having the above-mentioned configuration after it has been turned off, first, the lighting device 1 is connected to the filament 5 by the leads 10 and 8.
A current is passed from the heating element power source 14 as a preheating circuit in the lighting device 12 to keep the filament 5 in a heated state. A voltage from the voltage power source 15 is applied to start the discharge. The temperature of the filament at this time has a large effect on the discharge starting voltage.

As shown in Figure 3, when restarting, the discharge starting voltage is highest after approximately 1 minute has passed after the lamp has been turned off. Requires a lighting device with a device that generates a top pressure higher than the starting voltage.

FIG. 5 shows the relationship between the discharge starting voltage and the filament temperature one minute after the lamp is turned off in the high-pressure mercury lamp of the present invention shown in FIG. When the temperature of the filament 5 provided on the main electrode 2 is arbitrarily changed by electric current and the discharge starting voltage for restarting under high mercury vapor pressure is measured, the temperature of the filament 5 is 500% as shown in Fig. 5. [℃]
Above that, the discharge starting voltage drops rapidly,
Above 600℃, as the filament temperature increases,
The discharge starting voltage gradually decreases.

Conventionally, restart time is shortened. Alternatively, a high voltage of 10 [KV] or more was applied to restart the lamp immediately after turning it off, but in the method of this invention, by providing a filament and heating it, the voltage from the electrode (including the filament) is In order to create a condition where electron emission can easily occur, and then apply a voltage between both electrodes to restart the process,
The start of discharge becomes extremely easy, and the discharge starting voltage drops significantly to about 2000 [V] or less even when restarting, especially under mercury vapor of 100 [Torr] or more. For this reason, the high voltage generator necessary for restarting, that is, the high voltage power supply 15, is not large and expensive as in the past, but can be relatively small and inexpensive, and because the generating electrode is low, Wiring restrictions associated with installation of the lighting device do not need to be as severe as conventional ones, and can be used with the same restrictions as in the case of ordinary high-pressure discharge lamps.

Here, the circuit configuration shown in FIG. 2 will be further specifically explained using FIG. 6.

In FIG. 6, 15 is a high-voltage pulse generation circuit used in ballasts for high-pressure sodium lamps, that is, a high-voltage power supply.

This circuit is connected to an AC power source 13, and the arc tube 1
Since a pulse of about 2.5 KV is always generated when no current is flowing in the engine, this pulse is applied between the main electrodes 2 and 3 even when restarting. Reference numeral 16 denotes a current control circuit consisting of a chiyoke. This chain yoke is used as a primary winding, and 29 secondary windings constitute a transformer 30, which is connected to the coil 26 of the relay. 27 is a contact point of this relay.

Further, the contact point 27 of this relay and a transformer 28 whose energization is controlled by this relay constitute a power source 14 for the heating body. This lighting device operates as follows. Immediately after the light is turned off, when the power source 13 is connected, a high voltage (approximately 2.5 KV) pulse is generated from the high voltage power source 15, but since the height is not sufficient, discharge does not start between the main electrodes 2 and 3. Therefore, no current flows through the current control circuit 16, that is, the primary winding of the transformer 30, and no current flows through the relay 26 either.
Therefore, the relay contacts remain closed and transformer 2
A current flows through filament 5 as a heating element via 8 . The temperature of the electrode 2 rises due to the heat of the heating element, that is, the filament 5, and the discharge starting voltage decreases to below the pulse voltage (approximately 2.5 KV), and discharge starts.

When the discharge starts, current flows through the current control circuit 16, and the relay coil 26 passes through the transformer 30.
A current flows through the heater, opens the contact 27, stops the current to the heating element 5, and completes the restart.
It should be noted that there is a method for passing current through the filament 5, which is a heating element, at the time of restarting, and a method for passing current through the filament 5, which is a heating element, and
Various examples other than the configuration shown in FIG. 6 are possible as a configuration for applying a high voltage between them.

That is, in order to restart the lamp any time after the lamp has been turned off, it is necessary to apply at least a voltage higher than the maximum discharge starting voltage. As shown in FIG. 5, in order to lower the maximum value of this discharge starting voltage, the maximum temperature of the electrode 2 including the filament 5 must be lowered.
The effect was seen at temperatures above 500℃. Also in the above example, when the filament 5 was heated, the maximum temperature of the electrode 2 including the filament was about 850°C. Furthermore, the power of filament 5 is reduced to approximately
When the temperature was set to 500°C, approximately 5500V was required to enable restarting at any time after the lights were turned off. This voltage is sufficiently low compared to the case where the electrode 2 is not heated by the filament 5, and as long as the temperature of the electrode 2 including the filament 5 is at least 500°C or higher, the voltage is applied to enable restart. It turns out that it is effective in lowering the voltage. On the other hand, the applied voltage necessary to further lower the temperature of the electrode 2 including the filament 5 from 500° C. increases, and the effect becomes less and less apparent.

In FIG. 3, the discharge starting voltage decreases within one minute after the light is turned off, but one of the reasons for this is thought to be that the temperature of the electrode 2 is still high due to preheating when the light is turned on. For about 3 seconds after the lights are turned off, the temperature of the electrode is
The temperature is over 500°C, and it restarts with the same low applied voltage as when the temperature is raised by heating with a filament. After that, the temperature of the electrode rapidly decreases, and the discharge starting voltage also rapidly increases. That is, in the embodiment, heating by at least the filament is necessary from the time when the discharge starting voltage sharply increases about 3 seconds after the lights are turned off until about 2 minutes after when it sufficiently decreases again. Immediately after lights out refers to the period during that time. Furthermore, it is necessary to be able to turn on the lamp at any time after the lamp has been turned off, and at the very least, it is necessary to have a structure in which heating is always performed by the filament when restarting the lamp immediately after the lamp has been turned off.

In the above embodiment, a tungsten filament that is directly heated by an electric current is connected to the main electrode as a means for heating the electrode, but the electrode may also be heated indirectly or heated from outside the arc tube. It is a good thing.

The electrodes may be heated not only on one side, but also on both electrodes disposed at both ends of the arc tube.
In this way, the discharge starting voltage can be further lowered than in the case where only one side of the electrode is heated.

The upper limit of the electrode (including filament) temperature during heating is 2300°C; if it exceeds 2300°C, evaporation of the electrode material and associated filament breakage are likely to occur.

In this invention, the filament material that can be used is most preferably tungsten, but any heat-resistant metal material such as molybdenum or tantalum may be used.

In order to more effectively achieve the object of the present invention, when a filament is provided as the heating means for the electrode, the voltage drop across the filament when heated by electric current is 11 [V] or more. Just set it.

The voltage drop across the filament when heated is 11
When the voltage exceeds [V], a discharge occurs between both ends of the filament (a discharge that occurs only at the ends of the arc tube).
In addition to the electrodes being heated to the required temperature, this discharge also diffuses abundant ions and electrons into the discharge space within the arc tube, making it easier to initiate the discharge between the main electrodes and reducing the high vapor pressure of mercury. It will be easier to restart below.

In the above embodiment, a configuration in which a heating filament was connected to the main electrode was used, but the method of arranging the filament is not limited to this method.Although it is not in direct physical contact with the main electrode, it is electrically Any method described above may be used.

Furthermore, in a small high-pressure discharge lamp with a relatively small lamp current, the main electrode and the filament may not be formed individually, but the filament may also function as the main electrode. It is fully achievable.

In the above embodiment, a 400W high-pressure mercury lamp was described, but this invention is applicable not only to high-pressure mercury lamps of various sizes (lamp power), but also to metal halide lamps, which have a long restart time due to the high mercury vapor pressure inside the arc tube. Similar effects can be obtained when applied to high pressure discharge lamps such as high pressure sodium lamps.

Note that high-pressure discharge lamps have been known that have a preheating filament on the main electrode to improve normal starting, but in this case, even if you try to restart the lamp immediately after the lamp goes out, the bimetal does not return and the preheating filament does not work. Since it did not work, it was not possible to shorten the restart time.

As described above, when restarting immediately after turning off the light, the temperature of the electrode portions provided at both ends of the arc tube during heating is set to 500 to 2300 [°C], and the required distance between the electrodes is maintained. By applying a suitable voltage, even under high-pressure mercury vapor, the start of discharge is significantly facilitated, the restart time is shortened, and the voltage required for restart at any elapsed time after the light is turned off is significantly reduced. Large size like conventional
This makes it possible to restart a high-pressure discharge lamp with a relatively small and inexpensive lighting device without using an expensive lighting device, and provides a high-pressure discharge lamp that has high practical value and is highly effective. It is something to do.

[Brief explanation of drawings]

Figure 1 is a schematic circuit diagram of a conventional high-pressure discharge lamp, Figure 2
The figure is a schematic circuit diagram showing one embodiment of the present invention.
The figure is a characteristic diagram showing the relationship between the elapsed time after the high pressure discharge lamp is turned off and the discharge starting voltage, Figure 4 is a characteristic diagram showing the relationship between the mercury vapor pressure in the arc tube and the discharge starting voltage, and Figure 5 is a characteristic diagram showing the relationship between the discharge firing voltage and the elapsed time after the high pressure discharge lamp is turned off. FIG. 6 is a characteristic diagram showing the relationship between the temperature of the heating filament of a high-pressure discharge lamp and the discharge starting voltage, and FIG. 6 is a diagram showing a specific circuit configuration of the one shown in FIG. 2. In the figure, 1 is an arc tube, 2 and 3 are main electrodes, and 4
is an auxiliary electrode, 5 is a filament, 11 is an outer tube, 1
2 is a lighting device, and 13 is a power source. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A high-pressure discharge lamp having an arc tube in which at least mercury is sealed and provided with a pair of electrodes, including a heating element that heats at least one of the electrodes, and a heating element that heats at least one of the electrodes during normal startup. When restarting immediately after turning off the heating element without heating the heating element, the electrode is heated by the heating element, and a voltage is applied between the electrodes with the temperature of the electrode part at the time of heating being 500 to 2300 [℃]. A high-pressure discharge lamp characterized in that it is equipped with a lighting device that restarts the lamp by applying 2. Claim 1, characterized in that the lighting device is equipped with a heating element power source that causes the heating element to generate heat when restarting immediately after turning off the light, and a high voltage power source that applies a high voltage between the electrodes. High pressure discharge lamp as described.