JPH0611254U - Electrodeless discharge lamp - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an electrodeless discharge lamp with good startability. [Structure] A winding of an induction coil 2 is wound around an outer circumference of a bulb 1 made of a translucent material, and a high frequency current is supplied from a high frequency power source 4 to the induction coil 2. A discharge gas is enclosed in the bulb 1, and a high frequency electromagnetic field around the induction coil 2 is applied to the discharge gas to excite the discharge gas to emit light. On the outer wall surface of the valve 1, two starting auxiliary electrodes 3a and 3b are arranged along the winding direction of the induction coil 2 over substantially the entire circumference of the valve 1. A radially outward end piece 6 of the bulb 1 is extended to the ends of the auxiliary starting electrodes 3a and 3b, and the both end pieces 6 are opposed to each other. A high frequency voltage is applied to the auxiliary starting electrodes 3a and 3b to generate a preliminary discharge, and then a high frequency current is applied to the induction coil 2 to easily turn on the light. Further, the presence of the end piece 6 prevents electric field concentration at the ends of the starting auxiliary electrodes 3a and 3b, and prevents dielectric breakdown in the atmosphere between the starting auxiliary electrodes 3a and 3b.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an electrodeless discharge lamp that does not have an electrode inside the bulb and that causes the discharge gas inside the bulb to emit light by exciting a high-frequency electromagnetic field from outside the bulb.

[0002]

[Prior art]

 Conventionally, this type of electrodeless discharge lamp has the characteristics of small size, high output, and long life, so it has been researched and developed in various places, and it is considered to be used for high output point light sources, for example. Has been. As the electrodeless discharge lamp, as shown in FIG. 4, a bulb-shaped bulb 1 that surrounds an induction coil 2 that is an air-core coil is provided, and a high-frequency current is passed through the induction coil 2 to surround the induction coil 2. There is a method in which the high-frequency electromagnetic field formed in (1) is applied to the discharge gas containing mercury vapor sealed in the bulb 1 to excite the discharge gas to emit light (JP-A-57-78766).

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 configuration, the high frequency magnetic field inside the induction coil 2 acts on the discharge gas. There is a problem that the efficiency is low because it is not done. On the other hand, as shown in FIG. 5, a spherical bulb 1 made of transparent quartz glass or the like and an induction coil 2 having a winding wound around the outer circumference of the bulb 1 are provided. An electrodeless discharge lamp in which an inner high-frequency magnetic field acts on the discharge gas has been considered. In this configuration, since the high-frequency magnetic field is generated in the discharge gas inside the induction coil 2, the efficiency is higher than that of the configuration shown in 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 a discharge gas containing mercury is used, the initial starting is relatively easy, but there is a problem that restarting immediately after turning off the light is difficult. In addition, since the vapor pressure of mercury changes exponentially as the temperature rises, it is difficult to match with the high-frequency power source for supplying high-frequency current to the induction coil 2, and it becomes impossible to achieve matching. There is a problem that it cannot be lit stably because it goes out. On the other hand, if the discharge gas does not contain mercury, it will be easier to achieve matching, but the initial start will be 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, and this causes a problem of increasing the size of the high-frequency power source as a lighting circuit. 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. 6, 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. An electrodeless discharge lamp has been proposed in which a pair of starting auxiliary electrodes 3a and 3b facing each other are arranged on both sides of the bulb 1 in the axial direction of the induction coil 2 so that starting is relatively easy. (U.S. Pat. No. 4,489,589). In this electrodeless discharge lamp, a high-frequency voltage is applied between the start-up assistance electrodes 3a and 3b prior to the application of the high-frequency current to the induction coil 2 so that a streamer-like preliminary discharge is generated and the preliminary discharge is performed. This is intended to facilitate starting by passing a high-frequency current through the induction coil 2 in a state where discharge has occurred.

[0006]

[Problems to be solved by the device]

 By the way, when a high-frequency current is passed through the induction coil 2 to light it, a toroidal induction electric field is generated in the bulb 1 by the high-frequency magnetic field, and the discharge gas is ionized by the induction electric field to have a toroidal discharge path. Main discharge (generally ring discharge, or discharge state called high frequency ring discharge) occurs. Since the induction electric field interlinks with the high frequency magnetic field, a discharge path is formed along the winding direction of the winding of the induction coil 2 during lighting. On the other hand, since the preliminary discharge is generated between the auxiliary starting electrodes 3a and 3b in a direction orthogonal to the induction electric field, the high frequency electric field generated between the auxiliary starting electrodes 3a and 3b causes the transition from the preliminary discharge to the main discharge. There is a problem of hindering.

Further, since the distance between the starting auxiliary electrodes 3a and 3b is restricted by the distance between both ends of the valve 1 in the axial direction of the induction coil 2, the distance between the starting auxiliary electrodes 3a and 3b is reduced. If it is not possible to obtain the electric field strength necessary to generate the preliminary discharge, it is necessary to set the high frequency voltage applied to the auxiliary starting electrodes 3a and 3b to a considerably high value. Therefore, there is a problem in that the startability is not sufficiently improved even if the starting auxiliary electrodes 3a and 3b are provided.

The present invention is intended to solve the above-mentioned problems, and it is not necessary to supply a large amount of electric power to the starting auxiliary electrode, and the starting property is good and the electrodeless discharge can be formed in a relatively small size. It is intended to provide electric lights.

[0009]

[Means for Solving the Problems]

 In the invention of claim 1, in order to achieve the above object, a high frequency current is supplied from a high frequency power source 4 to an induction coil 2 in which a winding is wound around an outer circumference of a bulb 1 made of a translucent material. A high-frequency voltage is applied to an electrodeless discharge lamp that excites the discharge gas by causing a high-frequency electromagnetic field formed inside the winding in the radial direction to act on the discharge gas sealed in the bulb 1. A plurality of starting auxiliary electrodes 3a, 3b are arranged over substantially the entire circumference of the outer wall surface of the valve 1, and end pieces 6 facing each other are provided at the ends of a pair of adjacent starting auxiliary electrodes 3a, 3b. Are extended respectively.

According to the second aspect of the present invention, the auxiliary starting electrodes 3 a and 3 b are arranged on the line of intersection between the plane directly intersecting the central axis of the induction coil 2 and the outer wall surface of the valve 1.

[0011]

[Action]

 According to the structure of claim 1, when a high-frequency current is passed through the induction coil 2, the high-frequency magnetic field formed around the induction coil 2 acts on the discharge gas sealed in the valve 1 to cause the valve 1 to move. A toroidal induced electric field is generated therein, and the induced electric field causes a main discharge having a toroidal discharge path to be turned on. Here, when a high frequency voltage is applied to the auxiliary starting electrodes 3a and 3b before the high frequency current is applied to the induction coil 2, a streamer-like preliminary discharge is generated in the valve along the auxiliary auxiliary electrodes 3a and 3b. . Further, since the starting auxiliary electrodes 3a, 3b are arranged over substantially the entire circumference of the outer wall surface of the valve 1, the distance between the adjacent starting auxiliary electrodes 3a, 3b can be reduced, and the starting auxiliary electrodes 3a, 3b can be reduced. It is possible to increase the electric field strength between the electrodes 3 and 3b, which facilitates pre-discharge. In short, preliminary discharge is likely to occur, and the energy required for the transition from the preliminary discharge to the main discharge is small, so that the startability is excellent, and since the supplied energy at the time of starting is small, the power supply can be downsized, The overall size can be reduced. However, since the end pieces 6 facing each other are respectively extended to the ends of the pair of adjacent starting auxiliary electrodes 3a and 3b, the starting auxiliary at the portion where the distance between the auxiliary starting electrodes 3a and 3b is the minimum. The area between the electrodes 3a and 3b can be made large, and as a result, the electric field near the ends of the starting auxiliary electrodes 3a and 3b can be dispersed to suppress the electric field concentration. That is, the breakdown voltage between the starting auxiliary electrodes 3a and 3b can be set high, and the voltage applied to the starting auxiliary electrodes can be set to be relatively high, which facilitates the preliminary discharge and allows the insulation. It is possible to prevent damage to the starting auxiliary electrode due to breakage.

In order to confirm the effect of suppressing the occurrence of dielectric breakdown by providing the end pieces 6 on the auxiliary starting electrodes 3a and 3b, a comparative experiment as shown in FIG. 3 was performed. That is, as shown in FIG. 3A, the end portions of the strip-shaped electrode plates 7a and 7b are bent at a substantially right angle so that the end pieces 6 are provided and the end pieces 6 are opposed to each other. The voltage at which dielectric breakdown occurred was measured in the case where the edges of the strip-shaped electrode plates 7a and 7b face each other as shown in (b). Nickel plates were used as the electrode plates 7a and 7b, and the distance between the electrode plates 7a and 7b was set to 2 mm. Further, regarding the electrode plates 7a and 7b in FIG. 3 (a), the tip portions of the end pieces 6 are folded back in a direction away from each other so that no edge is formed at the tip portions of the end pieces 6 and The protruding length of the piece 6 was set to 2 mm. When a high frequency voltage of 13.56 MHz was applied to both electrode plates 7a and 7b by a high frequency power source 5 and varied between 0 and 3 kV, no dielectric breakdown occurred in the configuration of FIG. 3 (a). In the configuration of 3 (b), dielectric breakdown occurred at 2.3 to 2.5 kV. In other words, it was obtained that the provision of the end piece 6 does not cause the electric field to concentrate and the dielectric breakdown is less likely to occur. Here, the projecting dimension of the end piece 6 is set to be equal to the distance of the end piece 6, but it is desirable that the projecting dimension of the end edge 6 is 1: 2 or more with respect to the distance of the end piece 6.

In the configuration of claim 2, since the starting auxiliary electrodes 3a and 3b are arranged on the plane orthogonal to the central axis of the induction coil 2, the preliminary discharge is formed so as to follow the induction electric field by the induction coil 2. Therefore, it is not necessary to change the direction of the discharge at the time of transition from the preliminary discharge to the main discharge, and it is possible to reduce the energy supplied at the time of starting.

[0014]

【Example】

 (Embodiment 1) As shown in FIG. 1, a bulb 1 is formed of a light-transmitting material such as quartz glass into an airtight cylindrical shape, and a xenon gas of 100 Torr, for example, is enclosed in the bulb 1 as a discharge gas. I am doing it. A winding of the induction coil 2 is wound around the outer periphery of the valve 1 so as to be substantially coaxial with the center axis of 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. On the outer wall surface of the valve 1, two starting auxiliary electrodes 3a and 3b made of nickel plates are formed on a ring which is a line of intersection between the plane orthogonal to the central axis of the induction coil 2 and the outer wall surface of the valve 1. It is arranged in close contact with the valve 1. The starting auxiliary electrodes 3a and 3b are provided within the width of the induction coil 2 in the axial direction of the valve 1. Each of the starting auxiliary electrodes 3a, 3b is formed in an elongated strip shape having a sufficiently large vertical and horizontal dimensional ratio, and each of the starting auxiliary electrodes 3a, 3b has an end portion protruding outward in the radial direction of the valve 1 from each other. The opposing end pieces 6 are extended (see FIG. 1 (b)). The end piece 6 has the same width (for example, 3 mm) as the starting auxiliary electrodes 3a and 3b, and the protrusion dimension is set to, for example, 2 mm. In addition, the end piece 6 is formed in a rounded shape over the entire circumference so that no angular edge is formed on the peripheral edge of the end piece 6. That is, no corner is formed on the peripheral edge of the facing surface of the end piece 6 (for example, an elliptical shape), and the peripheral edge of the end piece 6 is an outwardly convex arc shape even in a cross section orthogonal to the facing surface. Is formed in. With such a shape, the concentration of the electric field can be prevented and the occurrence of dielectric breakdown can be further suppressed.

The induction coil 2 is supplied with a high-frequency current from a high-frequency power source 4 to generate a high-frequency magnetic field, and the high-frequency magnetic field acts on the discharge gas inside the bulb 1 to cause a main discharge having a toroidal discharge path. Is generated, and the discharge gas is excited to emit light. That is, a toroidal induction electric field is generated in the bulb 1 along the winding direction of the induction coil 2 by the high frequency magnetic field, and this induction electric field causes discharge plasma in the bulb 1. Occurs and the main discharge is maintained. The high frequency power supply 4 includes a high frequency generator 4a that generates a high frequency, an amplifier 4b that amplifies the output of the high frequency generator 4a, and a matching circuit 4c that is inserted between the amplifier 4b and the induction coil 2 to match the impedance. It is composed of

A high-frequency voltage is applied by a high-frequency power source 5 between the starting auxiliary electrodes 3a and 3b to generate a streamer-like preliminary discharge in the bulb 1. That is, when a high-frequency voltage is applied between the auxiliary starting electrodes 3a and 3b to form a high-frequency electric field, electrons in the vicinity of the auxiliary auxiliary electrodes 3a and 3b collide with the xenon atoms in the bulb 1 to generate xenon atoms. When enough electrons are supplied to maintain the discharge by ionizing and repeating such a phenomenon, as shown in FIG. 2, a streamer-shaped preliminary electrode is formed along the auxiliary starting electrodes 3a and 3b. Discharge SP occurs. Here, the auxiliary starting electrode 3b is connected to one end of the induction coil 2 and grounded. Further, the high frequency power supply 5 includes a matching circuit and the like like the high frequency power supply 4.

At the time of starting, first, a high frequency voltage is applied to the auxiliary starting electrodes 3a and 3b by the high frequency power source 5. At this time, a high frequency electric field is generated around both of the starting auxiliary electrodes 3a and 3b, and the preliminary discharge SP is generated along the starting auxiliary electrodes 3a and 3b as described above. When the induction coil 2 is supplied with a high-frequency current from the high-frequency power source 4 in the state where the preliminary discharge SP is generated, a high-frequency magnetic field interlinking the induction coil is generated, and an induction electric field interlinking with the high-frequency magnetic field is generated. Further, the high frequency magnetic field generated by the induction coil 2 is linked to the preliminary discharge SP. When the loop of the preliminary discharge SP is closed by the action of the induction electric field on the preliminary discharge SP in this way, the main discharge is started, and strong light emission is generated by the excitation of the discharge gas, and the lighting state is set. Here, since the induction coil 2 generates an induction electric field in the same direction as that of the preliminary discharge SP, the energy for changing the direction of the discharge path is not required when the transition from the preliminary discharge SP to the main discharge is required. When the lighting state is entered, the lighting state is maintained without applying a high frequency voltage to the start assisting electrodes 3a and 3b.

By providing the starting auxiliary electrodes 3a and 3b as described above, the initial input for forming the main discharge can be greatly reduced. This allows the power supply to be smaller and easier to start. Further, in the above configuration, the preliminary discharge SP was generated at 1.5 kV, and at this time, dielectric breakdown in the atmosphere did not occur between the starting auxiliary electrodes 3a and 3b.

Here, as the discharge gas, another single gas or a mixed gas may be used instead of the xenon gas, and the gas pressure is not limited to 100 Torr. In addition, although nickel plates are used as the start assisting electrodes 3a and 3b, the present invention is not limited to this, and the shape of the valve 1 is not limited to a cylindrical shape, and a spherical shape and various other shapes can be used. Can be adopted.

Example 2 In this example, 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-TlI-InI or the like is mixed with the rare gas. When a discharge gas mixed with such a substance is used, excited gas emission of rare gas occurs immediately after the main discharge occurs, and if the rare gas is xenon, white light is generated. After that, the vapor pressure of the mixed substance rises, 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 start-up can be provided. The technical idea of this embodiment can be applied to any of the above embodiments. The substance mixed with the rare gas as a component of the discharge gas is appropriately set according to the efficiency and the light color.

[0021]

[Effect of device]

 According to the invention of claim 1, a plurality of starting auxiliary electrodes are arranged over substantially the entire circumference of the outer wall surface of the valve. Therefore, when a high frequency voltage is applied to the starting auxiliary electrode, the auxiliary starting electrodes are arranged along the starting auxiliary electrode in the valve. Since a preliminary discharge is generated in the auxiliary auxiliary electrodes, the distance between the adjacent auxiliary auxiliary electrodes can be reduced, and as a result, the electric field strength between the auxiliary auxiliary electrodes can be increased. Discharge tends to occur. In other words, the power supply at start-up is small, so that the power supply can be downsized, and the overall size can be reduced. Furthermore, since the end pieces that oppose each other are extended to the ends of the pair of adjacent starting auxiliary electrodes, the area between the starting auxiliary electrodes at the portion where the distance between the starting auxiliary electrodes is minimum is increased. It is possible to disperse the electric field in the vicinity of the end of the starting auxiliary electrode and suppress the electric field concentration, and it is possible to increase the breakdown voltage between the starting auxiliary electrodes. become. As a result, it is possible to set the voltage applied to the starting auxiliary electrode to a relatively high value, which facilitates preliminary discharge and has the advantage that damage to the starting auxiliary electrode due to dielectric breakdown can be prevented. Of.

According to the second aspect of the present invention, since the starting auxiliary electrodes are arranged on the plane orthogonal to the central axis of the induction coil, the preliminary discharge is formed along the induction electric field by the induction coil, There is no need to change the direction of the discharge when shifting to the main discharge, the supplied energy at the time of starting can be reduced, and there is an advantage that the shift from the preliminary discharge to the main discharge becomes easy.

[Brief description of drawings]

1A shows a first embodiment, FIG. 1A is a schematic configuration diagram, and FIG. 1B is a sectional view taken along line XX of FIG.

FIG. 2 is an explanatory diagram of preliminary discharge in Example 1.

FIG. 3 is an explanatory view of the principle of the present invention.

FIG. 4 is a cross-sectional view showing a conventional electrodeless discharge lamp.

FIG. 5 is a side view showing another conventional example of the electrodeless discharge lamp.

FIG. 6 is a side view showing still another conventional example of the electrodeless discharge lamp.

[Explanation of symbols]

 1 Valve 2 Induction Coil 3a Starting Auxiliary Electrode 3b Starting Auxiliary Electrode 4 High Frequency Power Supply 5 High Frequency Power Supply 6 End Piece

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Innovator Shin Ogawa, 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Shingo Higashisaka, 1048, Kadoma, Kadoma City, Osaka Matsushita Electric Co., Ltd.

Claims (2)

[Scope of utility model registration request] 1. A high-frequency electromagnetic wave formed inside a winding in the radial direction of the induction coil by passing a high-frequency current from a high-frequency power source to an induction coil having a winding wound around an outer circumference of a valve made of a translucent material. In an electrodeless discharge lamp that excites and emits discharge gas by causing a field to act on the discharge gas enclosed in the bulb, a plurality of starting auxiliary electrodes to which a high-frequency voltage is applied are provided around substantially the entire outer wall surface of the bulb. An electrodeless discharge lamp in which end pieces facing each other are extended at the ends of a pair of adjacent starting auxiliary electrodes. 2. The electrodeless discharge lamp according to claim 1, wherein the auxiliary starting electrodes are arranged on a line of intersection between a plane orthogonal to the central axis of the induction coil and the outer wall surface of the bulb.