JPH05182640A - Solenoid field type discharge lamp - Google Patents

Abstract

PURPOSE:To provide a solenoid field type discharge lamp wherein a starting discharge is quickly and surely generated. CONSTITUTION:A high frequency excitation coil 20 is arranged in the periphery of a bulb 10 sealed with a luminous substance, to generate a plasma discharge in the bulb by flowing a high frequency current in the excitation coil, and the luminous substance emits light by this plasma discharge. Here, porous ceramics 30 is sealed in the bulb. Since the porous ceramics emits a discharge electron, a starting discharge and a main discharge from this starting discharge are easily generated, to smoothly generate a ring(doughnut)-shaped discharge, and the porous ceramics adsorbs surplus halogen vapor in discharge space to stabilize an electric field in the bulb.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid magnetic field type discharge lamp in which a plasma discharge is generated in a bulb by a high frequency excitation coil, and a luminescent material in the bulb is caused to emit light by this discharge.

[0002]

2. Description of the Related Art In a well-known high pressure metal vapor discharge lamp, that is, an HID discharge lamp, electrodes made of a refractory metal structure are sealed at both ends of an arc tube, and a voltage is applied between these electrodes. Then, arc discharge is generated, and the arc discharge causes the luminescent metal enclosed in the bulb to be ionized and excited to emit light. However, in the lamp having such a structure, since the electrodes are sealed at the end portions of the bulb, the sealing structure of the electrodes becomes complicated, and special measures are required to prevent leakage from the electrode sealing parts. Moreover, since the electrodes are exposed to the discharge space, various problems such as erosion of the electrodes occur.

A solenoid magnetic field type discharge lamp has been attracting attention as a lamp for solving such a problem of the electrode type discharge lamp. A solenoid magnetic field type discharge lamp is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-60048, in which a luminescent substance is enclosed in a transparent bulb, a high-frequency excitation coil is arranged around the bulb, and the excitation coil is radiated by a high-frequency wave. It is configured to be connected to an oscillation circuit.When a high-frequency current is passed from the high-frequency oscillation circuit to the excitation coil, a high-frequency magnetic field is generated, which causes plasma discharge in the bulb, and this discharge ionizes and excites the luminescent material. To emit light. Such a lamp is also referred to as an electrodeless discharge lamp because there is no electrode inside the bulb, and it is possible to eliminate the problem in the case of the above-mentioned electrode type lamp.

By the way, in this type of solenoid magnetic field type discharge lamp, a ring (donut) type electric field is generated in the bulb by the excitation coil surrounding the bulb. To efficiently inject electric energy into the discharge gas during plasma discharge,
It is important that the shape of the electric field is similar to that of the plasma discharge. In other words, plasma discharge is a ring (donut)
It is desirable to have a ring (doughnut) shape along the electric field of the shape. In order to generate such a ring-shaped discharge, it is important to induce a ring discharge at the beginning of the start of discharge. For this reason, in this type of solenoid magnetic field type discharge lamp, a starting means is provided. Japanese Unexamined Patent Publication No. 2-6
In Japanese Patent Laid-Open No. 0048, a starting electrode is provided at both ends on the center line of the valve, and a starting voltage is applied between the starting electrodes to cause discharge breakdown in the valve, thereby starting the starting. Means are shown. In such a case, a spark-like discharge is generated between the pair of starting electrodes, which expands in the radial direction to induce a ring-shaped plasma discharge.

However, since such a structure in which the starting electrode is provided is originally developed as an electrodeless discharge lamp of this type of solenoid magnetic field type discharge lamp, the purpose is to provide no electrode. Although the electrode is installed for starting, it is against the purpose, and the sealing of the electrode and the arrangement structure are complicated, which causes problems such as erosion of the electrode.

From the above, the starting means shown in FIG.
As shown in Fig. 4, a starting thin tube (also called a gas probe)
The structure which provides is proposed. In this device, a luminescent substance is enclosed in a transparent bulb 10, a high frequency excitation coil 20 is arranged around the bulb 10, and the excitation coil 20 is connected to a high frequency oscillation circuit 26 via a matching box 25. .. On one side of the valve 10, for example, a thin tube 15 which is preferably located on the coil central axis OO and is preferably made of the same material as the valve is connected, and the thin tube 15 is a partition wall with respect to the inside of the valve 10. Is isolated by 16,
At least one kind of argon or krypton, for example, is enclosed in the thin tube 15 as a starting rare gas.

A starting electrode 17 is attached to the thin tube 15, and the starting electrode 17 is connected to the capacitors 18a, 18a.
′ And an inductance 18b, and the starting circuit 18 is connected to a high frequency oscillation circuit 26 via a matching box 25.

In such a structure, when a high frequency voltage is applied to the starting electrode 17, a potential difference is generated between the starting electrode 17 and the high frequency electric field generated in the valve 10 by the high frequency magnetic field of the excitation coil 20. It is generated, which causes glow discharge in the thin tube 15 due to the starting rare gas. This glow discharge creates an electric field gradient with the interior of the bulb 10 and thus a radial discharge channel within the bulb 10, which induces a ring-shaped plasma discharge and a ring-shaped main discharge 12. It is a thing.

[0009]

However, there are some lamps in which the transition to the ring discharge does not occur smoothly even when the above-mentioned starting means is used. In particular, the luminescent metal is a metal halide such as NaI, CeI ₃ ,
It has been found that in the case of a highly efficient and long-life lamp using SnI ₂ , TlI, InI, etc., the occurrence of ring discharge is not good. There are various possible reasons for this, and one of them is considered to be that the excess halogen vapor floating in the bulb makes the electric field and arc unstable, making starting difficult and hindering the transition to ring discharge.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a solenoid magnetic field type discharge lamp in which a ring-shaped discharge is quickly and reliably generated in a bulb.

[0011]

The first aspect of the present invention is to enclose a luminescent material in a translucent bulb, and to arrange a high frequency excitation coil so as to surround the bulb, and to arrange a high frequency current in the excitation coil. In a solenoid magnetic field type discharge lamp in which a plasma discharge is caused to flow in the bulb to cause the light emitting substance to emit light by the plasma discharge, porous ceramics is enclosed in the bulb. A second aspect of the present invention is to enclose a luminescent material in a translucent bulb, and to arrange a high frequency excitation coil so as to surround the bulb, and to apply a high frequency current to the excitation coil to cause plasma discharge in the bulb. In addition, a starting thin tube isolated from the inside of the valve is connected to the valve, a rare gas for starting is enclosed in the starting thin tube, and a starting discharge is generated by the starting gas in the thin tube, In the solenoid magnetic field type discharge lamp in which the plasma discharge in the bulb is induced by the starting discharge, and the luminescent material is caused to emit light by the plasma discharge in the bulb, porous ceramics is enclosed in the starting thin tube. It is characterized by

[0012]

The porous ceramic has a property of emitting electrons when the defect lattice inside the ceramic is stimulated by a high frequency magnetic field and an electric field, and a property of adsorbing an excessive halide. Therefore, if the porous ceramic particles are stored in the bulb, the excess halide is adsorbed, so that the excess halogen vapor does not exist in the discharge space, the electric field in the bulb is stable, and the porous ceramic is stable. Since the initial discharge electrons are emitted, the main discharge is easily generated by being stimulated by the high frequency magnetic field and the electric field, and the ring (donut) type discharge is considered to be smoothly generated.

Further, when the porous ceramics is enclosed in the starting thin tube, the porous ceramics generate initial electrons in the thin tube upon being stimulated by a high frequency magnetic field and an electric field. Can be smoothly promoted, glow discharge is easily generated in the thin tube, and the starting characteristic is improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in FIGS.

In the figure, reference numeral 10 denotes an arc tube bulb, which is made of a high melting point glass such as synthetic quartz or a transparent ceramic material such as alumina.
In the bulb 10, an arc discharge 12 due to plasma is generated.
A light-emitting substance that emits light, for example, halogen metal, Na
I-CeI ₃ is enclosed. In addition to the light emitting substance, at least one rare gas such as argon, xenon, krypton, or neon is enclosed in the bulb 10.

An excitation coil 20 is arranged around the valve 10. Both ends of the excitation coil 20 are connected to a high frequency oscillation circuit 26 via a matching box 25, and a high frequency current is supplied by a high frequency voltage supplied from the high frequency oscillation circuit 26.

Due to such a high-frequency current, a magnetic field is generated in the exciting coil 20 along the coil axis direction O-O of the exciting coil 20, whereby the valve 10 housed in the central space of the coil 20 is generated. , A doughnut-shaped arc discharge 12 is generated by the plasma around the coil axis OO. This discharge 12 ionizes and excites the luminescent metal to emit light, which passes through the bulb 10 and is emitted to the outside. The excitation coil 20 is made of a highly conductive metal such as high-purity aluminum or copper or silver, and the coil wire has a non-circular cross section, for example, a flat shape.

A starting thin tube 15 is connected to one end of the valve 10, for example, located on the center line. Thin tube 1
5 is preferably the same material as the valve, valve 1
It is isolated from the inside of 0 through a partition wall 16. At least one kind of argon or krypton, for example, is enclosed in the thin tube 15 as a rare gas for starting. A starting electrode 17 is attached to the thin tube 15. The starting electrode 17 includes capacitors 18a and 18a '.
And a starting circuit 18 including an inductance 18b, and the starting circuit 18 is connected to a high frequency oscillation circuit 26 via the matching box 25.
In the case of the present embodiment, the valve 10 contains a porous ceramic, for example, porous alumina 30, in a size of about 10 mg.

The operation of the solenoid magnetic field type discharge lamp having such a structure, that is, the electrodeless discharge lamp will be described. When starting the lamp, from the high-frequency oscillator circuit 26, the starting electrode 1
At the same time as supplying the starting voltage to 7, a high frequency current is passed through the excitation coil 20 to generate an electric field in the valve 10 by the high frequency magnetic field. Then, a potential difference occurs between the starting electrode 17 and the electric field of the bulb 10, and the rare gas in the thin tube 15 causes glow discharge. An electric field gradient is generated between this glow discharge and the electric field in the bulb 10, so that plasma discharge is induced in the bulb 10 and a ring-shaped discharge 12 is generated around the coil axis OO.

In this case, since the valve 10 contains the porous ceramics 30, the ceramics 30
Is stimulated by the high-frequency magnetic field and electric field to emit initial electrons, which facilitates the initiation of discharge. Further, since the porous ceramics 30 adsorbs the excess halogen vapor in the bulb 10, the arc during starting and during lighting is stable. Therefore, when an electric field gradient is generated between the glow discharge generated in the thin tube 15 and the bulb 10,
A smooth discharge channel in the radial direction is generated inside the ring-shaped main discharge to induce a ring-shaped plasma discharge 1
2 can be generated. Therefore, the ring-shaped (doughnut) discharge 12 can be generated smoothly and surely. Such a ring (donut) type discharge 12 ionizes and excites the halogen metal to emit light.

Since the excitation coil 20 of this embodiment has a flat cross section, it has a large surface area, and since the high frequency current has the property of flowing on the surface of the conductor, the skin resistance is small and the surface area is large. The heat dissipation effect increases,
Along with the reduction in the resistance, self-heating is reduced, and the coil efficiency is improved. FIG. 2 shows the rate of ring discharge occurrence. 6.3 mg of NaI and 28 mg of CeI ₃ were enclosed in a bulb 10 having an outer diameter of 20 mm and a height of 17 mm, and 250 Torr of krypton was enclosed. 20 Torr krypton is enclosed in the starting thin tube 15, and this thin tube 1
A starting current of about 0.3 amperes was made to flow in the No. 5. With such a lamp, when the ring discharge occurrence rate was examined with and without containing the porous alumina 30 having a size of about 10 mg in the bulb 10, the results as shown in FIG. 2 were obtained. In the conventional case, the ring discharge occurrence probability cannot be increased unless the applied power is increased to increase the electric field strength, but in the case of the present invention, the ring discharge occurrence probability can be improved without increasing the applied power. ..

In the above-described embodiment, the porous ceramics 30 is housed in the valve 10. However, according to the present invention, the porous ceramics 40 is replaced with the starting thin tube 15 as in the other embodiments shown in FIGS. It may be housed inside. Even in the case of such a configuration, at the same time as supplying the starting voltage from the high-frequency oscillation circuit 26 to the starting electrode 17, the excitation coil 2
A high-frequency current is passed through 0 to generate an electric field in the bulb 10 by the high-frequency magnetic field. Then, a potential difference occurs between the starting electrode 17 and the electric field of the bulb 10, and the rare gas in the thin tube 15 causes glow discharge. In this case, since the porous ceramics 40 is housed in the thin tube 10, the ceramics 40 is stimulated by the high frequency magnetic field and the electric field to emit initial electrons, so that the glow discharge is surely discharged even at a low voltage. Easy to get started. An electric field gradient is generated between the glow discharge and the electric field in the bulb 10, so that plasma discharge is induced in the bulb 10 and thus a ring-shaped discharge around the coil axis OO in the bulb 10. 12 occurs. FIG. 4 shows the result of an experiment conducted on the probability of starting glow discharge in this case. This experiment has an inner diameter of 7
1 krypton in a starting tube 15 mm, 60 mm long
It was filled with 0 Torr so that a starting current of about 0.3 amperes could flow through the thin tube 15, and the case where the porous alumina 40 having a size of about 3 mg was housed in the thin tube 15 and the case where it was not housed were investigated. is there. It can be seen from FIG. 4 that the power required to generate the starting glow can be reduced when the porous alumina 40 is housed. When the engine is started in a dark room where the number of initial electrons is insufficient, the effect of this embodiment becomes more remarkable.

Reducing the electric power required to generate the starting glow in this way has the following effects. That is, before the start glow does not occur, the high frequency oscillation circuit 26
The load of the excitation coil 20 and the capacitor 18
a, 18a ′ and a starting circuit 18 including an inductance 18b, a matching box 25, and the like, which are normal when a proper resistance component is generated on the load side such as when glow occurs or when the lamp starts. Matching becomes possible, and the tuning is largely deviated before the start glow occurs, so that the electric power supplied to the starting thin tube 15 at the time of starting becomes significantly low, and the starting glow is small with a small electric power. It is necessary to take measures that can occur. On the other hand, as described above, the valve 10
Alternatively, in the case where the porous alumina 30 or 40 is housed in the thin tube 15, the electric power required for generating the starting glow can be reduced, so that the above worry can be avoided and a reliable starting can be performed.

Immediately after the occurrence of glow, the circuit 2 is rapidly changed.
Although the matching of 6 is in a normal state, in the case of the conventional circuit in which the starting glow is generated with high power, there is a concern that the rush current may flow from the power supply to the high frequency oscillation circuit 26 and damage the circuit. On the other hand, in the case of each of the above-described embodiments, the electric power required to generate the starting glow can be reduced, so that the damage to the circuit due to the inrush current can be prevented. The luminescent material of the present invention is not limited to metal halides, but it exhibits remarkable effects in the case of metal halides.

[0025]

As described above, according to the first aspect of the present invention, since the porous ceramic particles are contained in the bulb, excess halogen vapor does not exist in the discharge space, and the electric field in the bulb is stabilized. Moreover, since the porous ceramics emit the initial discharge electrons, the main discharge is easily generated by being stimulated by the high frequency magnetic field and the electric field, and the ring (donut) type discharge is smoothly generated. In addition, 2 of the present invention
According to the second, since the porous ceramics is enclosed in the starting thin tube, initial electrons are emitted from the porous ceramics in this thin tube by being stimulated by the high-frequency magnetic field and electric field, and the discharge breakdown at the start of discharge is smoothed. It can be promoted, glow discharge is easily generated, and starting characteristics are improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a solenoid magnetic field type discharge lamp and a lighting circuit thereof showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a ring discharge occurrence rate.

FIG. 3 is a configuration diagram showing a solenoid magnetic field type discharge lamp and a lighting circuit thereof according to another embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a starting glow discharge occurrence rate.

FIG. 5 is a configuration diagram showing a solenoid magnetic field type discharge lamp and a lighting circuit thereof as background art of the present invention.

[Explanation of symbols]

10 ... Bulb, 12 ... Arc discharge, 15 ... Capillary for starting,
16 ... Partition wall, 17 ... Starting electrode, 20 ... Excitation coil, 2
6 ... High-frequency oscillator circuit, 30, 40 ... Porous ceramics.

Claims (3)

[Claims] 1. A light-emitting substance is enclosed in a translucent bulb, and a high-frequency excitation coil is arranged so as to surround the bulb, and a high-frequency current is passed through the excitation coil to generate plasma discharge in the bulb. A solenoid magnetic field type discharge lamp in which the luminescent material is caused to emit light by this plasma discharge, wherein a porous ceramic is enclosed in the bulb. 2. A light-emitting substance is enclosed in a translucent bulb, and a high-frequency excitation coil is arranged so as to surround the bulb, and a high-frequency current is passed through the excitation coil to generate plasma discharge in the bulb. And connect the starting thin tube isolated from the inside of this valve to the above valve,
A starting rare gas is sealed in the starting thin tube, a starting discharge is generated by the starting gas in the thin tube, the plasma discharge is induced in the valve by the starting discharge, and the plasma discharge in the valve is generated. A solenoid magnetic field type discharge lamp in which the luminescent material is made to emit light, wherein porous ceramics is enclosed in the starting thin tube. 3. The solenoid magnetic field type discharge lamp according to claim 1, wherein the luminescent substance is a metal halide.