JPH05109390A - Electrode-less discharge lamp - Google Patents

Abstract

PURPOSE:To make the starting of an electrode-less discharge light lamp easy. CONSTITUTION:An induction coil 2 is coiled on the external circumference of a bulb 1 which is made of a light transmissive material and in which a discharge gas is sealed. High frequency electric current from a first high frequency electric power source 4a is applied to the induction coil 2 and a high frequency wave magnetic field is applied to the discharge gas sealed in the bulb 1 to radiate light by excitation of the discharge gas. A unipolar auxiliary electrode 3 is put in the bottom face of the bulb 1 and high frequency voltage from a second high frequency electric power source 4b is applied between the earth and the auxiliary electrode. Also, in the bulb 1, the external wall face at the site corresponding to the auxiliary electrode 3 is recessed and a projected part 5 projected toward inside of the bulb 1 is formed in the auxiliary electrode 3. Due to the high frequency wave electric field in the surroundings of the auxiliary electrode 3, string-like predischarge having free end at one end occurs in the bulb 1 and transferring to an arc discharge by high frequency wave magnetic field in the surroundings of the induction coil 2 becomes easy. In that case, the high frequency wave electric field is converged in the projected part 5, so that predischarge occurs easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention does not have an electrode inside a bulb made of a translucent material in which a discharge gas is sealed, and a high frequency magnetic field is applied to the discharge gas from outside the bulb to discharge gas. The present invention relates to an electrodeless discharge lamp adapted to excite and emit light.

[0002]

2. Description of the Related Art Conventionally, an electrodeless discharge lamp is known in which a high-frequency magnetic field is applied to a discharge gas sealed in a bulb to excite the discharge gas to emit light. This kind of electrodeless discharge lamp is small, high power,
Since it has features such as long life, it has been researched and developed in various places, and various uses are considered as a high-power point light source.

As an electrodeless discharge lamp, as shown in FIG. 2, a bulb-shaped bulb 1 surrounding an induction coil 2 is provided, and a high-frequency current is supplied to the induction coil 2 and enclosed in the bulb 1. There is a method in which a high-frequency magnetic field is applied to the generated discharge gas to excite the discharge gas to cause it to emit light (Japanese Patent Laid-Open No. 57-78766). A discharge gas containing mercury vapor is used, and the discharge gas emits light when excited by the mercury vapor.

By the way, the magnetic field formed around the air-core coil used as the induction coil 2 is the strongest inside the induction coil 2, but in the above-mentioned configuration, the high frequency magnetic field inside the induction coil 2 is discharged gas. Therefore, there is a problem that the efficiency is low. On the other hand, as shown in FIG. 3, a spherical valve 1 is provided,
The induction coil 2 having a winding wound around the outer circumference of the valve 1 is provided,
An electrodeless discharge lamp in which a high-frequency current is passed from the high-frequency power source 4 to the induction coil 2 has been considered. In this configuration, since the high-frequency magnetic field is applied to the discharge gas inside the induction coil 2, the efficiency is higher than that of the configuration of FIG.

As the discharge gas of these electrodeless discharge lamps, a mixed gas of a light emitting substance such as mercury vapor and a rare gas is generally used. When the discharge gas containing mercury is used, the initial starting becomes relatively easy, but there is a problem that the restarting is difficult. In addition, since the vapor pressure of mercury changes exponentially when the temperature rises (especially during lighting), it is difficult to match with the high-frequency power source for supplying the high-frequency current to the induction coil 2, and if the match is lost. The problem of disappearing arises. On the other hand, if mercury is not contained in the discharge gas, matching can be easily achieved, but initial starting becomes difficult. If a high voltage is applied to the induction coil, it can be forcibly started, but a high-frequency power source that can output a high voltage is required, which causes a problem that the high-frequency power source as a lighting circuit becomes large. That is, the size of the electrodeless discharge lamp including the electrodeless discharge lamp and the high frequency power source is increased.

In order to solve the above-mentioned problem, as shown in FIG. 4, a winding of the induction coil 2 is wound around the outer periphery of the valve 1 so that a high frequency magnetic field can be efficiently applied to the discharge gas, and An electrodeless discharge lamp has been proposed in which a pair of auxiliary electrodes 3 facing each other are arranged on both sides of the bulb 1 in the axial direction of the induction coil 2 so as to make starting relatively easy (US Pat. 4,894,
589, U.S. Pat. No. 4,902,937). In this electrodeless discharge lamp, a high-frequency voltage is applied between both auxiliary electrodes 3 prior to energization of a high-frequency current to the induction coil 2 so that preliminary discharge is performed, and induction is performed in the state where the preliminary discharge has occurred. It is intended to facilitate the starting by energizing the coil 2 with a high frequency current.

[0007]

By the way, when a high frequency current is passed through the induction coil 2 to light it, a rotating electric field is generated in the bulb 1 by the high frequency magnetic field, and the discharge plasma is generated along this rotating electric field. Is what runs. Since the rotating electric field is generated in the plane orthogonal to the magnetic flux, the discharge plasma runs along the winding direction of the winding of the induction coil 2 during lighting. On the other hand, the preliminary discharge generated between the auxiliary electrodes 3 is generated in the direction orthogonal to the rotating electric field, and both ends are restrained by the auxiliary electrodes 3, so that the rotating electric field is changed from the state of the preliminary discharge. There is a problem that a relatively large amount of energy is required to shift the discharge plasma to a state in which the discharge plasma runs. That is, even if the pair of auxiliary electrodes 3 are provided, there is a problem in that starting is not so easy.

An object of the present invention is to solve the above problems, and an object thereof is to provide an electrodeless discharge lamp which is easy to start and does not require a large high frequency power source and which can be formed relatively compactly. Is.

[0009]

In order to achieve the above-mentioned object, the present invention provides an induction coil in which one or more turns are wound around the outer circumference of a bulb made of a translucent material in which a discharge gas is enclosed. In the electrodeless discharge lamp in which a high-frequency current is applied from the high-frequency power source, and a high-frequency magnetic field is applied to the discharge gas sealed in the bulb to excite and discharge the discharge gas, a high-frequency voltage is applied from the second high-frequency power source. A single-pole auxiliary electrode that can generate a string-shaped preliminary discharge is provided in the bulb in close contact with the outer wall surface of the bulb so as to be electrostatically coupled to the space inside the bulb. The outer wall surface of the portion is recessed toward the inside of the bulb to form a protrusion on the auxiliary electrode that protrudes inside the bulb.

[0010]

According to the above construction, the unipolar auxiliary electrode capable of generating a string-shaped preliminary discharge in the bulb when a high frequency voltage is applied is electrostatically coupled to the space inside the bulb. Since it is provided in close contact with the wall surface, prior to energizing the induction coil with a high-frequency current to excite the discharge gas to emit light, preliminary discharge can be generated by the auxiliary electrode, and the discharge gas contains a luminescent substance. If not, it will be easy to start. Further, since the auxiliary electrode has a single pole, one end of the auxiliary discharge is restrained by the auxiliary electrode but the other end is a free end, and discharge plasma generated by the high frequency magnetic field generated around the induction coil runs. Even if the direction and the direction in which the preliminary discharge occurs are different, it is easy to shift the preliminary discharge to the direction in which the discharge plasma runs at the time of lighting, and compared with the case where a pair of auxiliary electrodes are arranged facing each other. , The energy required for starting is reduced. Further, since the outer wall surface of the portion of the bulb to which the auxiliary electrode is closely attached is depressed toward the inside of the bulb to form a protrusion on the auxiliary electrode that protrudes to the inside of the bulb, the electric field is concentrated at the tip of the protrusion. As a result, the preliminary discharge is likely to occur, and the starting is further facilitated.

[0011]

【Example】

(Embodiment 1) As shown in FIG. 1, a bulb 1 is made of a translucent material into a spherical shape, and xenon gas as a discharge gas is sealed at 100 Torr. The outer wall surface of one portion of the valve 1 is recessed and protrudes inward. Further, the induction coil 2 is formed by winding a winding around the outer circumference of a cylinder that is virtually set so as to enclose the valve 1. Here, the induction coil 2 is wound three turns, but the number of turns is not particularly limited and may be one or more turns. The induction coil 2 is arranged such that the recessed portion of the outer wall surface of the valve 1 is located at one end side in the axial direction. A monopolar auxiliary electrode 3 is arranged in close contact with the concave portion of the outer wall surface of the bulb 1. The auxiliary electrode 3 has a radius of 5 due to a metal foil, for example.
By forming a fan shape of mm and forming a conical shape in which straight portions are joined together, it is in close contact with the recessed portion of the valve 1. Therefore, the auxiliary electrode 3 is formed with the protrusion 5 protruding inward of the bulb 1.

The induction coil 2 is supplied with a high-frequency current from the first high-frequency power source 4a to generate a high-frequency magnetic field, and the high-frequency magnetic field acts on the discharge gas inside the bulb 1 to excite the discharge gas and emit light. It is supposed to do. A rotating electric field is generated in the bulb 1 by the high frequency magnetic field, and the discharge plasma generated in the bulb 1 by the rotating electric field rotates in the bulb 1. A high-frequency voltage is applied to the auxiliary electrode 3 from the second high-frequency power source 4b via a connection line, and a high-frequency electric field generated around the auxiliary electrode 3 causes a string-shaped preliminary discharge to occur in the bulb 1. It has become. That is, the electrons accelerated by the high-frequency electric field generated around the auxiliary electrode 3 collide with the atoms of the discharge gas and are ionized, so that the preliminary discharge occurs. Since the auxiliary electrode 3 is unipolar, one end of the preliminary discharge is restrained by the auxiliary electrode 3, but the other end is a free end, so that the preliminary discharge can move relatively freely. Here, the first high frequency power source 4
The a and the second high frequency power source 4b include a high frequency oscillating section for obtaining a high frequency output, an amplifying section for power amplifying the high frequency output, a matching section for matching impedance with the induction coil 2 and the auxiliary electrode 3. In addition, the second high frequency power source 4b
Applies a high frequency voltage between the auxiliary electrode 3 and the ground.

In order to light the electrodeless discharge lamp configured as described above, first, a high frequency voltage is applied to the auxiliary electrode 3 to cause preliminary discharge. The preliminary discharge gradually extends from the auxiliary electrode 3 and reaches almost the opposite side of the bulb 1. Here, when a high-frequency current is passed through the induction coil 2, the free end of the preliminary discharge is induced along the rotating electric field generated by the high-frequency magnetic field generated around the induction coil 2 to form a loop-shaped discharge path. At the moment when this loop is connected to form a ring shape, strong light emission occurs due to excitation of the discharge gas, and the light is turned on. After shifting to the lighting state, the light emitting state is maintained without applying a high frequency voltage to the auxiliary electrode 3.

As described above, by applying the high frequency voltage to the auxiliary electrode 3, the preliminary discharge can be generated, the transition to the arc discharge is facilitated, and the ignition is facilitated. That is, as compared with the case where there is no preliminary discharge, the initial input to the induction coil 2 is greatly reduced, and the startability is improved. Also,
The preliminary discharge is generated by electrons that are accelerated by a high-frequency electric field and collide and ionize xenon atoms. As described above, the outer wall surface of the bulb 1 is recessed so that the auxiliary electrode 3 protrudes inside the bulb 1. Since the protruding portions 5 are formed, the high-frequency electric field is concentrated on the protruding portions 5, so that impact ionization of xenon atoms is facilitated and pre-discharge is facilitated. That is, as a result of easy occurrence of preliminary discharge, it is possible to provide an electrodeless discharge lamp that can be easily started.

As the discharge gas, other single gas or mixed gas may be used instead of the xenon gas. Further, the position, size and shape of the auxiliary electrode are not particularly limited. Furthermore, the bulb 1 is not limited to a spherical shape, and may have any shape as long as it can form the protrusion 5 that projects into the inner space of the bulb 1 on the auxiliary electrode 3.

(Embodiment 2) In this embodiment, instead of forming the auxiliary electrode 3 with a metal foil, the auxiliary electrode 3 is formed by applying water platinum to the recess formed on the outer wall surface of the bulb 1. Is. If the auxiliary electrode 3 is formed by applying and drying such a liquid conductor, the degree of adhesion between the valve 1 and the auxiliary electrode 3 becomes high, and the degree of coupling between the internal space of the valve 1 and the auxiliary electrode 3 becomes high. Therefore, preliminary discharge is more likely to occur. Other configurations and operations are similar to those of the first embodiment.

(Embodiment 3) In this embodiment, as the discharge gas, a rare gas mixed with a metal or a metal halide is used. The metal and the metal halide may be a single substance or a mixture. For example, NaI-TaI-InI or the like is mixed with a rare gas. When a discharge gas mixed with such a substance is used, excited light emission of the rare gas occurs immediately after the transition to the arc discharge, and if the rare gas is xenon, white light is generated. After that, the vapor pressure of the mixed substance increases, and the emission color due to the mixed substance occurs. As described above, a high emission brightness can be obtained from the initial state, and a high-luminance electrodeless discharge lamp having a good rise can be provided. The configuration is the same as in Example 1 except for the components of the discharge gas.

[0018]

As described above, according to the present invention, a single-pole auxiliary electrode capable of generating a string-shaped pre-discharge in a bulb by applying a high frequency voltage is electrostatically coupled to the space in the bulb. Since it is installed in close contact with the outer wall surface of the valve,
Prior to energizing the induction coil with a high-frequency current to excite the discharge gas to cause it to emit light, a preliminary discharge can be generated by the auxiliary electrode, and even if the discharge gas does not contain a luminescent substance, it is easy to do so. It has the advantage that it can be started. Further, since the auxiliary electrode has a single pole, one end of the auxiliary discharge is restrained by the auxiliary electrode but the other end is a free end, and discharge plasma generated by the high frequency magnetic field generated around the induction coil runs. Even if the direction and the direction in which the preliminary discharge occurs are different, it is easy to shift the preliminary discharge to the direction in which the discharge plasma runs at the time of lighting, and compared with the case where a pair of auxiliary electrodes are arranged facing each other. That is, the effect that the energy required for starting is reduced. Further, since the outer wall surface of the portion of the bulb to which the auxiliary electrode is in close contact is recessed inside the bulb to form the protrusion protruding toward the inside of the bulb on the auxiliary electrode, the electric field is concentrated on the tip of the protrusion. As a result, the preliminary discharge is likely to occur, and the starting is further facilitated.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment.

FIG. 2 is a sectional view showing a conventional electrodeless discharge lamp.

FIG. 3 is a configuration diagram using another conventional electrodeless discharge lamp.

FIG. 4 is a sectional view showing still another conventional electrodeless discharge lamp.

[Explanation of symbols]

 1 Valve 2 Induction Coil 3 Auxiliary Electrode 4a First High Frequency Power Supply 4b Second High Frequency Power Supply 5 Projection

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[Procedure amendment]

[Submission date] February 3, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010]

According to the above construction, the unipolar auxiliary electrode capable of generating a string-shaped preliminary discharge in the bulb when a high frequency voltage is applied is electrostatically coupled to the space inside the bulb. since is provided in close contact with the wall, prior to discharge gas to cause excitation emission is by applying a high frequency current to the induction coil, it is possible to generate priming discharge by the auxiliary electrode, so that you can start to easily. Further, since the auxiliary electrode has a single pole, one end of the auxiliary discharge is restrained by the auxiliary electrode but the other end is a free end, and discharge plasma generated by the high frequency magnetic field generated around the induction coil runs. Even if the direction and the direction in which the preliminary discharge occurs are different, it is easy to shift the preliminary discharge to the direction in which the discharge plasma runs at the time of lighting, and compared with the case where a pair of auxiliary electrodes are arranged facing each other. , The energy required for starting is reduced. Further, since the outer wall surface of the portion of the bulb to which the auxiliary electrode is closely attached is depressed toward the inside of the bulb to form a protrusion on the auxiliary electrode that protrudes to the inside of the bulb, the electric field is concentrated at the tip of the protrusion. As a result, the preliminary discharge is likely to occur, and the starting is further facilitated.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

(Embodiment 3) In this embodiment, as the discharge gas, a rare gas mixed with a metal or a metal halide is used. The metal and the metal halide may be a single substance or a mixture. For example, mixing the like to the noble gas NaI- TlI -InI. When a discharge gas mixed with such a substance is used, excited light emission of the rare gas occurs immediately after the transition to the arc discharge, and if the rare gas is xenon, white light is generated. After that, the vapor pressure of the mixed substance increases, and the emission color due to the mixed substance occurs. As described above, a high emission brightness can be obtained from the initial state, and a high-luminance electrodeless discharge lamp having a good rise can be provided. The configuration is the same as in Example 1 except for the components of the discharge gas.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

[0018]

As described above, according to the present invention, a single-pole auxiliary electrode capable of generating a string-shaped pre-discharge in a bulb by applying a high frequency voltage is electrostatically coupled to the space in the bulb. Since it is installed in close contact with the outer wall surface of the valve,
Prior to discharge gas to cause excitation emission is by applying a high frequency current to the induction coil, it is possible to generate priming discharge by the auxiliary electrode, it has the advantage of starting to easily. Further, since the auxiliary electrode has a single pole, one end of the auxiliary discharge is restrained by the auxiliary electrode but the other end is a free end, and discharge plasma generated by the high frequency magnetic field generated around the induction coil runs. Even if the direction and the direction in which the preliminary discharge occurs are different, it is easy to shift the preliminary discharge to the direction in which the discharge plasma runs at the time of lighting, and compared with the case where a pair of auxiliary electrodes are arranged facing each other. That is, the effect that the energy required for starting is reduced. Further, since the outer wall surface of the portion of the bulb to which the auxiliary electrode is in close contact is recessed inside the bulb to form the protrusion protruding toward the inside of the bulb on the auxiliary electrode, the electric field is concentrated on the tip of the protrusion. As a result, the preliminary discharge is likely to occur, and the starting is further facilitated.

Claims (1)

[Claims] 1. A high-frequency current is supplied from a first high-frequency power source to an induction coil in which a winding is wound one or more turns around a bulb made of a translucent material in which a discharge gas is sealed, and then sealed in the bulb. In an electrodeless discharge lamp that excites the discharge gas to emit light by applying a high-frequency magnetic field to the discharge gas, a high-frequency voltage is applied from a second high-frequency power source to generate a string-shaped preliminary discharge in the bulb. The auxiliary electrode of the is closely attached to the outer wall surface of the valve so as to be electrostatically coupled to the space inside the valve. An electrodeless discharge lamp, characterized in that it is formed by forming a protrusion projecting inward of the bulb.