JP3489414B2 - Short arc type discharge lamp - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a short arc type discharge lamp. In particular, it relates to a short arc type discharge lamp having a trigger wire.

[0002]

2. Description of the Related Art Metal halide lamps are used for general illumination and spot illumination, and metal halide lamps are also incorporated in projectors such as OHPs, slide projectors, actual projectors, liquid crystal projectors and the like. FIG. 3 shows such a metal halide lamp. The lamp 1 is made of quartz glass and has a pair of electrodes 2 and 3 therein. This electrode has a sealing part 4,
At 5 it is connected to a metal foil and further leads to external leads. Then, a trigger wire 8 is connected to one of the outer leads 6, and the wire 8 is wound around the base of the other electrode 2. Then, the concave reflecting mirror 9 is provided in a state substantially coincident with the axis of the lamp 1, and the tip of the sealing portion 4 of the lamp 1 is inserted and fixed to the neck of the concave reflecting mirror 9. A power supply 10 is connected to the lamp 1 to supply electric power.

As described above, the trigger wire is usually wound so as to have the same electric potential as that of one of the electrodes, and this wire improves the starting characteristics in a cold state of the lamp. This is for the following reason. That is, when there is no trigger wire, the pulsed high voltage applied to the lamp is evenly applied between both electrodes. For example, when a pulsed high voltage of 20 KV is applied to a lamp with an arc length of 5 mm, the potential gradient becomes 4 KV / mm, and this energy accelerates the electrons. On the other hand, when the wire is attached as shown in FIG. 3, in the vicinity of the base of the other electrode 2 around which the wire is wound, a high pulse voltage is generated between the other electrode 3 and the capacitance of quartz glass as a medium. Since the voltage is applied, it can be said that the potential gradient is considerably higher than the above. Therefore, it is understood that by providing the wire, the electrons are given sufficient acceleration energy, and the charged particles generated thereby cause the Townsend avalanche phenomenon, leading to dielectric breakdown.

On the other hand, let us consider a case where the high voltage pulse is applied immediately after the lamp is turned off from the stable lighting state, that is, when the lamp is not sufficiently cooled to start the lamp. In this case, if a trigger wire is provided, the number of charged particles necessary for dielectric breakdown is sufficient, but the internal pressure of the lamp is still high (in a cold state, the inert gas is 1 atm or less). However, the internal pressure of several to several tens of atmosphere remains immediately after the light is turned off.) The pulse high voltage does not become corona discharge on the inner wall of the lamp near the base of the other electrode and does not shift to arc discharge between the electrodes. In many cases, the lamp will not light. Then, when the wire was removed from FIG. 3, the lamp was turned on immediately after the light was turned off. However, when the high pulse voltage is low, the lamp does not light, but corona discharge does not occur on the inner wall of the lamp as when a wire is provided. As described above, the trigger wire does not hinder the lighting performance under normal operating conditions when the lamp is cold, but it does not hinder the lighting performance of the lamp when restarted immediately after the lamp is turned off. I understood.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a short arc type discharge lamp which can be restarted satisfactorily even immediately after extinguished.

[0006]

The short arc type discharge lamp of the present invention comprises a pair of electrodes inside, and a short arc type discharge lamp in which a sealing portion is formed at both ends of an arc tube in which a luminous substance is sealed. The discharge lamp when starting
A short arc type discharge consisting of a power supply that applies high voltage.
In a lamp device, the short arc type discharge lamp
Is a trigger wire that is at the same potential as one of the electrodes, is wrapped around quartz glass that corresponds to the vicinity of the base of the other electrode, and there is conduction in the middle of the trigger wire when the discharge lamp is cold. state, and is connected to a switch becomes non-conductive state in the warm state, the Sui
The discharge lamp is cold when the
Pulse height from power supply to the electrodes and to the trigger wire
Apply pressure and keep the discharge lamp warm.
Applies a pulsed high voltage only between the electrodes from the power source.
It is characterized by

Further, the discharge lamp according to claim 2 is
A reflecting mirror is provided so as to cover the periphery thereof, and the switch is provided on the back surface of the reflecting mirror.

Further, the discharge lamp according to claim 3 is
It is characterized by being a metal halide lamp.

[0009]

In the short arc type discharge lamp of the present invention, the switch makes the trigger wire conductive when the lamp is cold, so that the lamp can be lit under normal conditions. In addition, since the trigger wire is made non-conductive by the switch when the lamp is in a warm state such as immediately after the lamp is turned off, the lighting performance of the lamp is improved without the pulse high voltage being consumed by the corona discharge.

[0010]

1 shows an embodiment of the present invention.
The same numbers as in FIG. 3 represent the same parts. A lead wire 60 is connected to the external lead 6 of the lamp 1 and is connected to the power supply 10. Then, the trigger wire 8 is branched in the middle of the lead wire 60, and the trigger wire 8 penetrates the hole provided in the reflecting mirror 9 via the switch 11 and the electrode 2 in the sealing portion 4 of the lamp 1. Wrapped near the root of.

The switch 11 is attached to the back surface of the reflecting mirror 9 (the surface opposite to the reflecting surface), and for this switch 11, for example, bimetal can be used. Then, the bimetal switch conducts at, for example, less than 100 ° C.
The lamp is set to open at 0 ° C or higher, and the lamp is set to a position at which it becomes 100 ° C or higher in a stable lighting state. As a result, when the lamp is sufficiently cooled, the switch 11
Since a temperature lower than 0 ° C. is detected, it becomes conductive, and a voltage of the same potential is applied to the trigger when it is applied to the electrode 3, so that the lamp can be satisfactorily started by lighting. On the other hand, when the lamp is still warm, that is, immediately after extinguished from the stable lighting state, the switch 11 detects a temperature of 100 ° C. or higher, so that it is in the cutoff state, and no potential is applied to the trigger 8 and the above-mentioned condition occurs. It does not cause any problems. The position where the switch 8 is attached and the setting of the cutoff temperature of the switch can be changed depending on the size of the lamp (rated power etc.) and the size of the reflection mirror, and are not limited to those shown in this embodiment. It goes without saying that the configuration of can be applied.

FIG. 2 shows another embodiment of the present invention. The switch 11 is an electromagnetic switch which is arranged apart from the reflecting mirror 9 and is controlled to open / close by a signal from the control circuit 40. Here, the control by the control circuit 40 is performed, for example, by detecting the lighting state of the lamp, detecting the elapsed time of the extinguished state, and the like. Specifically, the lighting state of the lamp is judged from the voltage or current supplied to the lamp, and the elapsed time after the light is turned off can also be recognized by measuring the time in such a state. In this embodiment, since it is not necessary to detect the temperature of the lamp or the reflector,
The switch 11 need not be provided on the back surface of the reflecting mirror 9.

Next, an experiment showing the effect of the present invention will be described. A short arc type metal halide lamp with an AC length of 250 W and an arc length of 2.5 mm was used, and two types of lamps were used, one with a trigger wire as shown in FIG. 1 and one without a trigger wire. Then, for each lamp, a state in which the lamp is sufficiently cooled, and the lamp is steadily turned on for 10 minutes and then turned off, and 15 seconds after the turning off,
The restart experiment was conducted in each state of 30 seconds, 45 seconds and 60 seconds.
The experiment was performed 100 times for each, and the number of times of lighting (probability) was counted. Here, the pulse high voltage applied at one time is 20 KV, and the number of times of application is only once.
The experimental results are shown in FIG. It can be said that if the lighting property of 95% or more is secured, the high voltage pulse is applied for about 3 seconds in practical use, and thus sufficient lighting is possible. As a result, it can be seen that in the case where the trigger wire is present, the lamp can be successfully restarted in a state where the lamp is cold or a state after 45 seconds from extinction. Further, it can be seen that when the trigger wire is not provided, the lamp can be successfully restarted if it is in a state until 30 seconds after the light is turned off.

The short arc type discharge lamp of the present invention comprises:
Not limited to metal halide lamps, other lamps,
For example, it can be applied to a mercury lamp. Further, the short arc type discharge lamp is not limited to an AC lighting type, but can be applied to a DC lighting type.

[0015]

As described above, in the short arc type discharge lamp of the present invention, since the trigger wire is provided with the switch and the trigger wire is made conductive by the switch when the lamp is cold, the lamp can be lit under normal conditions. it can. In addition, since the trigger wire is made non-conductive by the switch when the lamp is in a warm state such as immediately after the lamp is turned off, the lighting performance of the lamp is improved without the pulse high voltage being consumed by the corona discharge.

[Brief description of drawings]

FIG. 1 shows a short arc type discharge lamp of the present invention.

FIG. 2 shows another embodiment of the short arc type discharge lamp of the present invention.

FIG. 3 shows a conventional short arc type discharge lamp.

FIG. 4 shows the effect of the present invention.

[Explanation of symbols]

1 discharge lamp 2 electrodes 3 electrodes 4 Sealing part 5 Sealing part 6 External lead 8 trigger wire 9 Reflector 10 Ballast 11 switch

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Claims (3)

(57) [Claims] 1. A short arc type discharge lamp having a pair of electrodes inside thereof, wherein a sealing portion is formed at both ends of an arc tube in which a luminescent substance is sealed, and a pulse height at the time of starting the discharge lamp.
Short arc type discharge lamp consisting of a power source for applying pressure
In the device, in the short arc type discharge lamp , a trigger wire having the same electric potential as one of the electrodes is wound around quartz glass corresponding to the vicinity of the base of the other electrode, and the trigger wire is provided in the middle of the trigger wire. , becomes conductive in a state where the discharge lamp is cold, is connected to a switch becomes non-conductive state in the warm state by the switch, in a state where the discharge lamp has cooled, the electrostatic from said power supply
When a high pulse voltage is applied between the electrodes and the trigger wire
In both cases, when the discharge lamp is warm,
A high voltage pulse is applied only between the electrodes.
Electric arc type discharge lamp device. 2. The short arc type discharge according to claim 1, wherein the discharge lamp is provided with a reflection mirror so as to cover the periphery thereof, and the switch is provided on the back surface of the reflection mirror. lamp. 3. The short arc type discharge lamp according to claim 1, wherein the discharge lamp is a metal halide lamp.