JPH0896765A - Inductively coupled electrodeless discharge lamp, its lighting device, and lighting device using the same - Google Patents

Abstract

(57) [Abstract] [Purpose] In an arc tube having a protruding tube portion extended from a bulging portion forming a light emitting space, it is possible to prevent the temperature of the protruding tube portion from excessively lowering and to improve luminous efficiency. An inductively coupled electrodeless discharge lamp that can be used is provided. [Arrangement] An arc tube 10 having a bulging portion 11 and a protruding cylindrical portion 12 protruding from the bulging portion, a luminous tube 10 in which a luminescent medium and a rare gas are filled, and a bulging portion surrounding the bulging portion. An exciting coil 30 for generating a magnetic field coupled discharge in the arc tube and a heat insulating member 20 for covering the protruding cylindrical portion are provided. Since the heat-retaining film is formed on the surface of the projecting tubular portion, the heat release from the projecting tubular portion is suppressed and the temperature of the coldest portion can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductively coupled type in which plasma is generated in an arc tube by an excitation coil provided around the arc tube and the discharge causes the luminous medium enclosed in the arc tube to emit light. The present invention relates to an electrode discharge lamp, a lighting device for the same, and a lighting device using the same.

[0002]

Conventional high pressure metal vapor discharge lamps, or HIs
In a D discharge lamp, electrodes made of a high melting point metal are sealed at both ends of an arc tube bulb, an arc discharge is generated between these electrodes, and the luminescence medium enclosed in the bulb is ionized and excited by this discharge to emit light. It is designed to let you.
However, a lamp having such an electrode requires an electrode component because the electrode has to be arranged inside the bulb, and the sealing structure of the electrode is complicated to prevent leakage from the electrode sealing part. Therefore, there is a drawback that the electrode is eroded because the electrode is exposed to the discharge space, blackening occurs due to the electrode material adhering to the tube wall, and the life is shortened due to electrode damage.

As a lamp that eliminates such drawbacks,
For example, Japanese Patent Application Laid-Open No. 2-12753 proposes an inductively coupled electrodeless discharge lamp. The inductively coupled electrodeless discharge lamp is
A luminescent medium that emits light by generating a magnetic field coupling, such as a metal halide, is enclosed in a transparent arc tube bulb.
A high-frequency excitation coil is arranged so as to surround the arc tube, and the excitation coil generates plasma by magnetic field coupling in the arc tube, and the plasma causes the metal halide as the light emitting medium to discharge and emit light. Since there is no electrode in the arc tube, there is an advantage that the above-mentioned drawbacks in the case of the electrode type lamp can be eliminated.

By the way, in this type of inductively coupled electrodeless discharge lamp, since the maximum temperature of the arc tube during lighting rises to about 1000 ° C., the arc tube is closed after the light emitting medium and the rare gas are filled. If the sealing location is provided near the above-mentioned maximum temperature, there is a concern that the glass adhesive and the enclosed material react due to the high temperature to cause sealing failure and leak. In addition, when the glass adhesive and the enclosure material react due to high temperature, there is a risk that the enclosure material may run out and may disappear or go out of light.

For this reason, the arc tube has a bulging portion which forms a discharge space which is a main light emitting region, and is projected from the bulging portion.
A structure is used in which a thin tube-shaped protruding cylinder portion used as an exhaust pipe is formed, and a luminescent medium or a rare gas is sealed from an opening portion of the protruding cylinder portion and then the opening end portion is closed. After the evacuation step, such a protruding tube portion is sealed with a closing member using a glass adhesive.

If such a protruding tube portion is formed, the tip of the protruding tube portion will be far away from the maximum temperature portion of the arc tube, so that the temperature rise of the sealing portion is suppressed and the glass adhesive As a result, there is no concern that the enclosure will react, and a reliable seal can be maintained.

[0007]

By the way, when the above-mentioned protruding cylinder is provided, the tip of the protruding cylinder becomes the coldest part during lighting, and the excess light emitting medium aggregates in this coldest part. . Therefore, the coldest part controls the vapor pressure of the light emitting medium during lighting.

However, in the case of a lamp having a small input, for example, the temperature of the coldest part may be too low, and in this case, the vapor pressure of the light emitting medium may be low and the light emission amount may be low.

Although it is possible to change the temperature of the coldest part by changing the length of the protruding tube portion, it is necessary to manufacture a light emitting tube in which the protruding length of the protruding tube portion is different for each rating. A pipe is required, which increases the cost.

Therefore, it is desirable to use a common arc tube, but as described above, in a lamp with a small rated input, the temperature of the coldest part may become too low. The present invention has been made based on such a situation, and an object of the present invention is to provide an arc tube having a protruding tube portion extended from a bulging portion forming a light emitting space, in which the temperature of the protruding tube portion is excessive. It is an object of the present invention to provide an inductively-coupled electrodeless discharge lamp, a lighting device for the same, and a lighting device using the same, which can prevent light emission from increasing and increase luminous efficiency.

[0011]

According to a first aspect of the present invention, there is provided a bulging portion in which a main discharge space is formed, and a protruding cylindrical portion protruding from the bulging portion and communicating with the main discharge space. ,
An arc tube in which a luminous medium and a rare gas are enclosed, an excitation coil which surrounds the bulging portion and generates a magnetic field coupling discharge in the arc tube, and an extruding tube which is provided in the projecting tube section. And a heat insulating member that covers the portion.

According to a second aspect of the present invention, there is provided a bulging portion in which a main discharge space is formed, and a protruding cylindrical portion protruding from the bulging portion and communicating with the main discharge space. An arc tube filled with a rare gas, an excitation coil that surrounds the bulging portion and generates a magnetic field coupling discharge in the arc tube, and a conductive member that is provided on the protruding tube section and covers the protruding tube section And are provided.

According to a third aspect of the present invention, the conductive member also serves as a starting electrode connected to the starting circuit. The invention of claim 4 is characterized in that the conductive member is a conductive coating.

According to a fifth aspect of the present invention, the conductive member is covered with a film for preventing oxidation. The invention of claim 6 is characterized in that the arc tube is formed of a translucent ceramic.

According to a seventh aspect of the present invention, there is provided an inductively coupled electrodeless discharge lamp according to any one of the first to sixth aspects, and a high frequency oscillation circuit for supplying high frequency power to an excitation coil of the discharge lamp. A lighting device for an inductively coupled electrodeless discharge lamp, comprising:

According to an eighth aspect of the present invention, there is provided an inductively coupled electrodeless discharge lamp according to any one of the first to sixth aspects, and a high frequency oscillation circuit for supplying high frequency power to an excitation coil of the discharge lamp. An illuminating device comprising: an inductively coupled electrodeless discharge lamp and a luminaire containing a high-frequency oscillation circuit.

[0017]

According to the first aspect of the present invention, since the heat insulating coating is formed on the surface of the projecting tubular portion, heat is prevented from being released from the projecting tubular portion, so that the heat is generated at the end of the projecting tubular portion. It is possible to raise the temperature of the coldest part. Therefore, a predetermined vapor pressure can be obtained and a predetermined luminous efficiency can be obtained.

Further, in this way, the protruding cylindrical portion can be made long and the reaction between the sealing adhesive and the enclosed material can be prevented. According to the invention as set forth in claim 2, the conductive coating film formed on the surface of the protruding tube portion serves to keep the protruding tube portion warm, and to raise the temperature of the coldest portion generated at the end of the protruding tube portion. Therefore, a predetermined vapor pressure can be obtained, and a predetermined luminous efficiency can be obtained.

Also in this case, the protruding cylindrical portion can be made long and the reaction between the sealing adhesive and the enclosed material can be prevented.
According to the third aspect of the invention, since the conductive member also serves as the starting electrode, it is possible to configure the starting means with a simple structure, which facilitates starting.

According to the fourth aspect of the invention, since the conductive member is formed of a conductive coating, the structure is simple and the formation is easy. According to the invention described in claim 5, since the conductive member is covered with the film for preventing oxidation, oxidation is prevented and the life is extended.

According to the sixth aspect of the invention, since the arc tube is made of translucent ceramic, heat resistance,
It has excellent chemical resistance and is effective for high-voltage, high-power inductively coupled electrodeless discharge lamps. According to the invention of claim 7 and claim 8, the temperature of the coldest part is maintained at a predetermined temperature,
A lighting device and a lighting device with high luminous efficiency can be provided.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the first embodiment shown in FIG. FIG. 1 shows the whole of an inductively coupled electrodeless discharge lamp. In the figure, reference numeral 1 is an inductively coupled electrodeless discharge lamp, and 10 is an arc tube thereof. The arc tube 10 is made of a translucent alumina, sapphire, garnet, or other single crystal or polycrystal translucent ceramic material, and has a bulge portion 11 and a protruding cylinder portion extended from the bulge portion 11. 12 and. Bulge 11
Has a substantially flat outer shape with an outer diameter in the major axis direction of about 32.5 mm (inner diameter of about 30.mm) and an outer diameter in the minor axis direction of about 25.0 mm (inner diameter of about 27.5 mm). And the main discharge space 13 is formed inside. The main discharge space 13 is filled with a luminescent substance which emits light by the plasma discharge 14 generated in a donut shape, for example, a metal halide and a rare gas for starting. As the metal halide, a rare earth metal halide or an alkali metal iodide or bromide is encapsulated. For example, scandium iodide ScI ₃ and sodium iodide N
aI, or neodymium iodide NdI ₃ and sodium iodide NaI, or praseodymium iodide PrI ₃ , cesium iodide CsI, and sodium iodide NaI are each sealed in a predetermined amount. Further, as the starting rare gas, at least one kind of gas such as argon, xenon, krypton and neon is enclosed.

The protruding cylindrical portion 12 is located on the center line of the bulging portion 11 and integrally projects from the bulging portion 11. The protruding cylinder portion 12 has a cylindrical shape with an outer diameter of 5.0 to 6.0 mm and a length of about 45 mm, and one end thereof communicates with the main discharge space 13.

The tip of the protruding cylindrical portion 12 is closed by a closing body 15. The closing body 15 is made of a ceramic disk or the like, and is joined to the open end of the protruding cylindrical portion 12 by a glass adhesive 16. As a result, the protruding tube portion 12 is hermetically sealed. The glass adhesive 16 is A
l ₂ O ₃ -SiO ₂ system or Al ₂ O ₃ -CaO-Ba
O-based glass solder, refractory metal such as platinum, etc. are used.

In the case of this embodiment, the closing body 15 is
A starting electrode 17 formed of a tube made of a conductive metal such as niobium Nb, stainless steel or copper Cu is penetrated through, and the starting electrode 17 is attached to the closing body 15 by a glass adhesive 18. It is airtightly joined. The inner end of the starting electrode 17 faces the protruding cylindrical portion 12, and the outer end thereof is connected to a starting circuit 26 described later.

A heat insulating member, for example, a heat insulating film 20 is attached to the outer surfaces of the protruding cylindrical portion 12 and the starting electrode 17. The heat-retaining coating 20 is made of, for example, a heat-resistant oxide such as silica, alumina, or zirconia, or a heat-resistant resin, and is applied over the entire surfaces of the protruding cylindrical portion 12 and the starting electrode 17 that are exposed to the outside air.

A high frequency excitation coil 3 is provided around the arc tube 10.
0 is arranged. In the excitation coil 30, the conductor corresponding to the coil wire is high-purity aluminum or copper,
Alternatively, a pair of ring-shaped metal discs 3 having excellent conductivity such as silver
It is composed of 1 and 31. The pair of annular discs 31, 31 are arranged so as to face each other along the coil axial direction, and by forming a spiral energization path as a whole by welding and connecting some of the inner peripheral portions to each other. ing. That is, the pair of annular discs 31 and 31 are not continuous in the circumferential direction, but are separated from each other in the circumferential direction, and the inner circumferential portion of one annular disc 31 and the other annular disc 31 are separated.
And the inner peripheral part of each of them are partially connected to each other to form a spiral energization path as a whole.

Specifically, the pair of annular discs 31, 3
1 is formed of a high-purity aluminum plate having a plate thickness of 2 mm, an inner diameter of 35 mm, and an outer diameter of 62 mm. The high frequency excitation coil 30 composed of such a pair of annular discs 31, 31 is arranged corresponding to the maximum outer diameter portion of the arc tube 10 on the inner surface of the coil wire, and from the high frequency oscillation circuit 25,
For example, a high frequency current of about 13.56 MHz is made to flow. Such a high-frequency current generates a magnetic field in the excitation coil 30 along the coil axis direction of the excitation coil 30, and the magnetic field surrounds the coil axis in the arc tube 10 housed in the central space of the coil 30. In this way, a donut-shaped plasma is generated, which causes a magnetic field-coupled plasma discharge 14. The plasma discharge 14 ionizes and excites the luminescent medium to emit light, which is transmitted through the tube wall of the arc tube 10 and radiated to the outside.

The high frequency exciting coil 30 is connected to the high frequency oscillating circuit 25.
5, the high frequency power of, for example, 13.56 MHz is supplied. In addition, 27 shows a commercial power supply.

The operation of the first embodiment having such a structure will be described. When starting the lamp, a starting voltage is supplied from the high-frequency oscillation circuit 25 to the starting electrode 17 through the starting circuit 26, and at the same time a high-frequency current is passed through the excitation coil 30 to generate a high-frequency magnetic field in the main discharge space 13 inside the arc tube 10. Generate an electric field. Then, a potential difference is generated between the starting electrode 17 and the electric field in the arc tube 10, a glow discharge is generated between them, and this glow discharge induces a plasma discharge in the main discharge space 13, and thus a bulging portion. A donut-shaped discharge 14 is generated in 11.

When the doughnut-shaped plasma discharge 14 is generated in the main discharge space 13 in this manner, the luminescent substance in the main discharge space 13 is ionized and excited to emit light. This light emission is emitted to the outside from the tube wall of the arc tube 10.

In the inductively coupled electrodeless discharge lamp that operates as described above, since the heat insulating coating 20 is formed on the outer surfaces of the protruding tube portion 14 and the starting electrode 17, the tip portion of the protruding tube portion 14 or the electrode 17 is formed. The temperature of the coldest part generated at the outer end of the is increased.

That is, since the tip end of the protruding tube portion 14 and the outer end portion of the auxiliary electrode 17 are separated from the donut-shaped plasma discharge 14 generated in the main discharge space 13 during lighting,
The temperature becomes lower, and either one becomes the coldest part, and the excess light emitting metal, that is, the halide of the rare earth metal, agglomerates in this coldest part. The vapor pressure in the arc tube 10 depends on the temperature of the coldest part, and the luminous efficiency depends on the vapor pressure. Therefore, the temperature of the coldest part ultimately controls the luminous efficiency.

However, if the length of the protruding cylinder portion 14 is shortened, the coldest portion can be brought closer to the plasma discharge 14, and therefore the temperature can be raised, but in this case, the tip of the protruding cylinder portion 12 is airtight. There is a concern that the glass adhesive 16 to be sealed in the above may react with the inclusions by being heated, resulting in poor airtightness. Therefore, the length of the projecting tubular portion 14 needs to be some length, which may lower the temperature of the coldest portion.

Further, in order to prevent the reaction between the glass adhesive 16 and the enclosed material, the protruding tube portion 14 is formed to be long in advance, so that it is possible to use the arc tube in common even for discharge lamps having different ratings. In this case, depending on the rating, the temperature of the coldest part may drop too much.

On the other hand, in the case of the above embodiment, the protruding cylindrical portion 1
4 and the heat insulating coating 20 is formed on the outer surface of the starting electrode 17, heat is prevented from being radiated from the tip portion of the protruding tubular portion 14 and the surface of the auxiliary electrode 17, and thus the tip portion of the protruding tubular portion 14 is prevented. Alternatively, the temperature of the coldest portion generated at the end of the auxiliary electrode 17 can be raised. Therefore, a predetermined vapor pressure can be obtained and a predetermined luminous efficiency can be obtained.

Therefore, according to the configuration of the above embodiment,
It is possible to prevent melting of the glass adhesive 16 and raise the temperature of the coldest portion to a predetermined temperature. In the above embodiment, the starting electrode 17 is attached to the closing body 15, and the electrode 17 is passed through the starting circuit 26 and the high frequency oscillation circuit 25.
However, the present invention is not limited to the inductively coupled electrodeless discharge lamp using such starting means.

That is, FIG. 2 shows a second embodiment of the present invention, which is an example of an inductively coupled electrodeless discharge lamp of the type in which the starting electrode 17 and the starting circuit 26 are not used. In this example, the same members as those in FIG.

In the case of such a configuration, the high frequency oscillation circuit 2
By causing a predetermined high-frequency current to flow from 5 to the high-frequency excitation coil 30, the plasma discharge 14 can be generated in the main discharge space 13 without using a special starting means.

Also in this case, since the heat insulating coating 20 is formed on the outer surface of the protruding tube portion 14, the heat release from the tip of the protruding tube portion 14 is suppressed, and the heat is generated at the tip of the protruding tube portion 14. It is possible to raise the temperature of the coldest part.
Therefore, the reaction between the glass adhesive 16 and the enclosed material can be prevented, and moreover, a predetermined vapor pressure can be obtained, and thus a predetermined luminous efficiency can be obtained.

FIG. 3 shows a third embodiment of the present invention. In this embodiment, a conductive coating 22 made of a conductive material, for example, silver, copper, aluminum, etc., is formed on the outer surface of the protruding cylinder portion 14.
Is formed. Further, a coating 23 is formed on the outer surface of the conductive coating 22 in order to prevent oxidation of the conductive coating 22 and to insulate the conductive coating 22. The coating 23 is made of, for example, a heat resistant insulating coating such as silica, alumina or zirconia, or a heat resistant insulating resin.

In the case of this embodiment, the conductive film 22 is also used as the starting electrode, and the conductive film 22 is connected to the high frequency oscillation circuit 25 through the starting circuit 26. Since other structures may be the same as those in FIG. 1, the same reference numerals are used and the description thereof is omitted.

The operation of the third embodiment having such a structure will be described. When starting the lamp, a starting voltage is supplied from the high frequency oscillating circuit 25 through the starting circuit 26 to the conductive coating film 22 formed on the outer surface of the protruding tubular portion 14,
At the same time, a high-frequency current is passed through the excitation coil 30 and the arc tube 10
An electric field is generated in the main discharge space 13 by a high frequency magnetic field. Then, a potential difference is generated between the conductive coating film 22 and the electric field in the arc tube 10, a glow discharge is generated between them, and this glow discharge induces a plasma discharge in the main discharge space 13, and thus a bulging portion. A donut-shaped discharge 14 is generated in 11.

For this reason, the conductive film 22 acts as a starting electrode. With such a conductive coating 22, the configuration becomes simpler than in the case where the starting electrode 17 is provided as in the first embodiment shown in FIG.

While the lamp is on, the conductive coating film 22 and the anti-oxidation / insulating coating film 23 formed on the outer surface of the projecting cylinder portion 14 have a heat retaining function so as not to release the heat of the projecting cylinder portion 14. It is possible to raise the temperature of the coldest portion generated at the tip of the tubular portion 14. Therefore, the reaction between the glass adhesive 16 and the enclosed material is prevented, and the bulging portion 1
A predetermined vapor pressure can be obtained within 1, and thus a predetermined luminous efficiency can be obtained.

Further, in the case of such a conductive film 22,
Not only does the heat of the projecting tube portion 14 not escape to the outside, but a dielectric current flows through the conductive coating film 22 due to the magnetic flux (indicated by the arrow in FIG. 3) generated in the excitation coil 30 during lighting, and this dielectric current Thereby, the conductive film 22 self-heats. Therefore, in addition to the passive heat-retaining effect of not releasing the heat of the projecting tubular portion 14 to the outside, an effect of positively heating the projecting tubular portion 14 can be expected, which can raise the temperature of the coldest portion. it can.

In this case, the protruding cylinder portion 14 is connected to the excitation coil 30.
If it is arranged along the coil axis O-O direction, the direction in which the interlinkage between the coated surface of the conductive coating film 22 and the excitation magnetic flux (indicated by the arrow in FIG. 3) generated by the excitation coil 30 is minimized. As a result, the magnetic flux passing through the conductive coating film 22 applied in a cylindrical shape increases, and a large dielectric current flows, so that the heat generation performance can be improved.

Further, the conductive coating film 22 can increase the amount of heat generation if it is a material having a high magnetic permeability, and conversely, can reduce the heat generation amount if it is a material having a low magnetic permeability. As described above, the idea that the conductive coating film 22 is positively heated during lighting to raise the temperature of the coldest part is not limited to the above-described dielectric heating, but the conductive coating film 22 is connected to a heating circuit, not shown. Alternatively, the heating circuit may be directly supplied with an electric current to generate heat.

Since the outer surface of the conductive coating film 22 is covered with the oxidation preventing and insulating coating film 23, the heat retaining action is further enhanced, the conductive coating film 22 is prevented from being oxidized, and the insulating action is achieved. Is prevented and is safe.

FIG. 4 shows a fourth embodiment of the present invention. This embodiment shows an example in which the conductive member formed on the outer surface of the protruding cylinder portion 14, for example, the conductive coating film 22 is not used as the starting electrode. That is, FIG. 4 is an example of an inductively coupled electrodeless discharge lamp that does not use the starting electrode 17 and the starting circuit 26, as in FIG. 2. Also in this example, the same members as those in FIG.

Also in the case of this structure, as in FIG. 2, by flowing a predetermined high frequency current from the high frequency oscillating circuit 25 to the high frequency exciting coil 30, the main discharge space 13 can be provided without using any special starting means. Plasma discharge 14 can be generated.

Also in this case, the conductive coating film 22 and the oxidation preventing / insulating coating film 23 formed on the outer surface of the projecting tubular portion 14 have the effect of keeping the temperature of the projecting tubular portion 14, so that the most likely occurrence occurs in the projecting tubular portion 14. The temperature of the cold section can be raised. Therefore, the reaction between the glass adhesive 16 and the enclosed material can be prevented, and a predetermined vapor pressure can be obtained in the bulging portion 11, and thus a predetermined luminous efficiency can be obtained.

Also in the case of such a conductive coating film 22, it is possible to positively heat the projecting tubular portion 14 by flowing a dielectric current or a heating current, thereby increasing the temperature of the coldest portion. You can

Further, since the outer surface of the conductive coating film 22 is covered with the oxidation preventing and insulating coating film 23, the heat retaining function is further enhanced, and the conductive coating film 22 is prevented from being oxidized and has a good insulating function. , Safe.

FIG. 5 shows a fifth embodiment of the present invention. In this embodiment, the heat insulating coating 2 similar to that shown in FIG.
In the bulged portion 11 of the arc tube 10, the wall thickness t of the equator portion to which the excitation coil 30 is closest is shown.
₁ is made larger than the wall thickness t ₂ of other places (t ₁ > t ₂ ). That is, in the arc tube 10, the excitation coil 30 is closest to the equator, so that the temperature of the equator is locally highest, and in some cases, thermal shock may cause cracking. If the wall thickness t ₁ of the portion is made larger than the wall thickness t ₂ of the other portion, the heat capacity of the equator increases, the mechanical strength and the thermal strength improve, and the temperature gradient becomes gentle. Can be prevented.

As described above, the wall thickness t ₁ of the equator portion is
The technique for increasing the thickness t ₂ to be larger than the wall thickness t ₂ at other locations can be implemented regardless of the technique for forming the heat insulating coating 20 or the conductive coating 22 on the protruding cylindrical portion 12.

FIG. 6 shows a sixth embodiment of the present invention. In this embodiment, the heat insulating coating 2 similar to that shown in FIG.
In the example in which 0 is formed, in the bulging portion 11 of the arc tube 10, the surface opposite to the protruding tube portion 12, that is, the outer surface of the lower half of the equator portion is polished.

When such a surface polishing portion 28 is provided, the lower half surface of the arc tube 10 made of ceramic has a low surface roughness and is a clean surface, so that the diffusion and absorption of light is reduced and the downward light is directed. The transparency is improved, and the brightness can be improved.

As will be described later, since the inductively coupled electrodeless discharge lamp of this type often uses the lower half of the arc tube 10 as the light emitting surface, the surface polishing section 28 as described above is provided. It is valid.

The technique of forming the surface polishing portion 28 in the lower half of the equator can be carried out independently of the technique of forming the heat insulating coating 20 or the conductive coating 22 on the protruding cylindrical portion 12. Is.

In the first to sixth embodiments, the inside of the protruding cylindrical portion 12 extended from the bulging portion 11 is
Although the case where it is hollow has been described, if the inner space of the projecting tubular portion 12 is hollow, a large useless space exists because this inner space does not contribute to light emission, and this inner space is set to a predetermined pressure. Therefore, extra luminescent metal and rare gas are needed. Therefore, measures to eliminate or reduce this internal space have been considered.

In this case, it is conceivable to reduce the diameter of the protruding tube portion 12 to form a thin tube, but since the protruding tube portion 12 serves as a stay for mechanically supporting the arc tube 10,
When the tube is made thin, the strength becomes weak, and there is a limitation in making the tube.

Therefore, the structure as in the seventh embodiment shown in FIG. 7 is adopted. That is, in the seventh embodiment, the plug body 40 is fitted in the internal space of the protruding tubular portion 12. The plug 40 is made of ceramic or the like, and may be separate from or integral with the closing body 15 that seals the open end of the protruding cylindrical portion 12. By doing so, the inner surface of the protruding tubular portion 12 and the plug 4
Since a minute gap 41 is formed between the outer surface of the hollow cylinder 0 and the outer surface of the hollow cylinder 12, most of the internal space of the protruding cylindrical portion 12 is filled with the plug body 40, so that the volume of the internal space can be reduced. Since it is not necessary to fill the luminescent metal or the rare gas, it is possible to reduce the filling amount.

In this arc tube 10, as in the third embodiment shown in FIG. 3, a conductive member, for example, a conductive coating film 22 is formed on the outer surface of the projecting tubular portion 14, and this conductive material is used. On the outer surface of the coating film 22, an oxidation preventing / insulating coating film 23 is laminated and formed.

In the case of this embodiment, the conductive film 22 is also used as the starting electrode, and the conductive film 22 is connected to the high frequency oscillation circuit 25 via the starting circuit 26. Since other structures may be the same as those in FIG. 3, the same reference numerals are used and the description thereof is omitted.

The operation of the seventh embodiment having such a configuration will be described. When starting the lamp, a starting voltage is supplied from the high frequency oscillating circuit 25 through the starting circuit 26 to the conductive coating film 22 formed on the outer surface of the protruding tubular portion 14,
At the same time, a high-frequency current is passed through the excitation coil 30 and the arc tube 10
An electric field is generated in the main discharge space 13 by a high frequency magnetic field. Then, a potential difference is generated between the conductive film 22 and the electric field in the arc tube 10, and glow discharge is generated between them.

In this case, the plug 40 is fitted in the inner space of the protruding cylinder 12, but a minute gap 41 is formed between the inner surface of the protruding cylinder 12 and the outer surface of the plug 40. The glow discharge extends to the main discharge space 13 through the minute gap 41.

Such a glow discharge induces a plasma discharge in the main discharge space 13, so that a donut-shaped discharge 14 is generated in the expanded diameter portion 11. Therefore, also in this case, the conductive coating film 22 acts as a starting electrode.

While the lamp is lit, the conductive film 22 and the oxidation preventing / insulating film 23 formed on the outer surface of the protruding tube portion 14 have a heat retaining function so as to prevent the heat of the protruding tube portion 14 from escaping. It is possible to raise the temperature of the coldest portion generated at the end portion of the tubular portion 12, that is, at the tip portion of the minute void 41. The minute gap 41 formed between the inner surface of the protruding cylindrical portion 12 and the outer surface of the plug 40 communicates with the main discharge space 13, so that the coldest portion is generated at the tip of the minute gap 41. Since the temperature of the coldest portion rises, it is possible to prevent the glass adhesive 16 from melting and to obtain a predetermined vapor pressure in the bulging portion 11, and thus a predetermined luminous efficiency. .

Further, in the case of such a conductive film 22,
Not only does the heat of the projecting tube portion 14 not escape to the outside, but a dielectric current flows through the conductive coating film 22 due to the magnetic flux (indicated by the arrow in FIG. 3) generated in the excitation coil 30 during lighting, and this dielectric current Thereby, the conductive film 22 self-heats. Therefore, in addition to the passive heat-retaining effect of not releasing the heat of the projecting tubular portion 14 to the outside, an effect of positively heating the projecting tubular portion 14 can be expected, which can raise the temperature of the coldest portion. it can.

In this case, the protruding cylinder portion 14 is connected to the excitation coil 30.
If it is arranged along the coil axis O-O direction, the direction in which the interlinkage between the coated surface of the conductive coating film 22 and the excitation magnetic flux (indicated by the arrow in FIG. 3) generated by the excitation coil 30 is minimized. As a result, the magnetic flux passing through the conductive coating film 22 applied in a cylindrical shape increases, and a large dielectric current flows, so that the heat generation performance can be improved.

Since the outer surface of the conductive coating film 22 is covered with the oxidation preventing and insulating coating film 23, the heat retaining function is further enhanced, the conductive coating film 22 is prevented from being oxidized, and the insulating function is exerted. Is prevented and is safe.

FIG. 8 shows an eighth embodiment of the present invention. This embodiment shows an example in which the conductive member formed on the outer surface of the protruding cylinder portion 14, for example, the conductive coating film 22 is not used as the starting electrode. That is, FIG. 8 is an example of an inductively coupled electrodeless discharge lamp of the type that does not use the starting electrode 17 and the starting circuit 26, as in FIG. 4. Also in this example, the same members as those in FIG.

Also in the case of this structure, as in the case of FIG. 4, by flowing a predetermined high frequency current from the high frequency oscillation circuit 25 to the high frequency excitation coil 30, the main discharge space 13 can be provided without using any special starting means. Plasma discharge 14 can be generated.

Since the conductive coating film 22 and the anti-oxidation / insulating coating film 23 formed on the outer surface of the projecting tubular portion 14 have the effect of keeping the temperature of the projecting tubular portion 14, the temperature of the coldest portion generated in the projecting tubular portion 14 is increased. Can be raised. For this reason,
It is possible to prevent the reaction between the glass adhesive 16 and the enclosed material, and to obtain a predetermined vapor pressure in the bulging portion 11, and thus a predetermined luminous efficiency.

Further, also in the case of such a conductive coating film 22, it is possible to positively heat the projecting tubular portion 14 by flowing a dielectric current or a heating current, thereby increasing the temperature of the coldest portion. You can

Further, since the outer surface of the conductive coating film 22 is covered with the oxidation preventing and insulating coating film 23, the heat retaining action is further enhanced, the conductive coating film 22 is prevented from being oxidized, and a good insulating action is exhibited. , Safe.

In the case of the embodiment shown in FIG. 8, instead of the conductive film 22 and the anti-oxidation / insulating film 23, the structure shown in FIG.
You may form the heat insulation coating 20 shown in. Furthermore, FIG. 9 shows a ninth embodiment of the present invention.

The ninth embodiment is an example in which the probe 50 is used as the starting means. That is, a ceramic probe 50 is formed integrally with the closing cylinder 15 in the protruding tube portion 12, and the probe 50 is fitted into the protruding tube portion 12. The end portion of the probe 50 is a closed wall 51, and thus the inside of the probe 50 constitutes an auxiliary discharge space 52 isolated from the main discharge space 13. The probe 50 is filled with a rare gas made of one or more of argon, xenon, krypton, neon and the like.

The probe 50 as described above is fixed to the protruding tube portion 12 by hermetically bonding the end closing member 15 to the protruding tube portion 12 via the glass adhesive 16.
In this case, a gap portion 53 is formed between the inner surface of the protruding cylindrical portion 12 and the outer surface of the probe 50. Also, the closing body 15
1 is sealed with a starting electrode 17 similar to that shown in FIG. 1, and the starting electrode 17 is connected to a starting circuit 26.

On the outer surface of the protruding cylinder portion 12, a heat insulating film 20 similar to that shown in FIG. 1 is formed. Other structures may be the same as in the case of FIG. 1, so the same reference numerals are given and the description thereof is omitted.

The operation of the ninth embodiment having such a configuration will be described. When starting the lamp, a starting voltage is supplied from the high-frequency oscillating circuit 25 to the starting electrode 17 through the starting circuit 26, a high-frequency current is caused to flow through the excitation coil 30 at the same time, and a high-frequency magnetic field is generated in the main discharge space 11 inside the arc tube 10. Generate an electric field. Then, a potential difference is generated between the starting electrode 17 and the electric field in the arc tube 10, so that the rare gas enclosed in the starting discharge space 52 in the probe 50 emits glow discharge. In this case, by making the gas pressure of the rare gas sealed in the starting discharge space 52 relatively low, starting discharge is likely to occur.

The glow discharge generated in the starting discharge space 52 creates an electric field gradient with the electric field in the arc tube 10. Therefore, this starting discharge induces a plasma discharge in the main discharge space 13, Therefore, a donut-shaped discharge 14 is generated.

When the donut-shaped plasma discharge 14 is generated in the main discharge space 13 in this manner, the main discharge space 13 is formed.
The luminescent substance therein is ionized and excited to emit light. This light emission is emitted to the outside from the tube wall of the arc tube 10.

In such an inductively coupled electrodeless discharge lamp 1, since the heat insulating coating 20 is formed on the protruding tube portion 12,
As in the case of FIG. 1, the temperature of the coldest portion generated at the tip of the gap 53 formed between the inner surface of the protruding tube portion 12 and the outer surface of the probe 50 is suppressed because the heat release of the protruding tube portion 12 is suppressed. Can be higher. Therefore, the luminous efficiency can be increased.

FIG. 10 shows the inductively coupled electrodeless discharge lamp 1 described above.
The illuminating device which used as a light source is shown. In FIG. 10, reference numeral 8
Reference numeral 0 denotes a main body of the lighting fixture, which has a reflector 81 on the upper portion and a front glass 82 on the front surface.

A high frequency oscillation circuit 25 and a starting circuit 26 are attached to the instrument body 80, and FIG.
The inductively coupled electrodeless discharge lamp 1 described in any of FIGS.

The inductively coupled electrodeless discharge lamp 1 has a protruding tube portion 1
2 is attached downward, and the bulging portion 11 is attached upward to the instrument body 80. Therefore, when the inductively coupled electrodeless discharge lamp 1 is turned on, the light mainly emitted from the upper surface side of the bulging portion 11 is reflected by the reflector 81 and then illuminates the front through the front glass 82.

In this case, since the projecting tubular portion 12 faces downward, the coldest portion is formed at the lower end of the projecting tubular portion 12, and if the heat insulating coating 20 or the conductive coating 22 is formed, it will be described in detail. By the operation described, the temperature of the coldest part can be raised to a predetermined temperature. Therefore, a lighting device with high luminous efficiency can be obtained.

The luminous substance sealed in the arc tube 10 is a halide of a rare earth metal or an alkali metal.
Although it is advantageous in terms of light emission efficiency and color rendering, it is not limited to metal halides, and other light emitting substances such as sulfur and gallium may be used alone or in a combination thereof. Furthermore, the shape of the bulging portion 11 of the arc tube 10 is spherical,
It may be an ellipsoidal sphere, a ring shape, or the like. Further, the arc tube 10 is not limited to be made of ceramic, but may be made of quartz.

[0091]

As described above, according to the first aspect of the present invention, since the heat insulating coating is formed on the surface of the projecting tubular portion, it is possible to prevent the heat from being released from the projecting tubular portion, and thus the projecting tubular portion. It is possible to raise the temperature of the coldest part generated at the end of the. Therefore, a predetermined vapor pressure can be obtained and a predetermined luminous efficiency can be obtained. Moreover, in this way, the protruding cylindrical portion can be made long, and there is no concern that the sealing adhesive reacts with the enclosed material to cause adhesion failure.

According to the second aspect of the present invention, the conductive coating film formed on the surface of the protruding tube portion serves to keep the protruding tube portion warm, and raises the temperature of the coldest portion generated at the end of the protruding tube portion. Therefore, a predetermined vapor pressure can be obtained, and a predetermined luminous efficiency can be obtained.

Also in this case, the protruding cylindrical portion can be made long, and there is no fear that the sealing adhesive reacts with the enclosed material to cause defective adhesion. According to the invention of claim 3, since the conductive member also serves as the starting electrode, the starting means can be constructed with a simple structure, and the starting is facilitated.

According to the invention of claim 4, since the conductive member is formed of a conductive coating, the structure is simple and the formation is easy. According to the invention of claim 5, since the conductive member is covered with the film for preventing oxidation, the oxidation is prevented and the life is extended.

According to the sixth aspect of the invention, since the arc tube is formed of a translucent ceramic, it is excellent in heat resistance and chemical resistance, and is used in a high pressure, high output inductively coupled electrodeless discharge lamp. It is valid. According to the inventions of claims 7 and 8, it is possible to provide a lighting device and a lighting device in which the temperature of the coldest part is maintained at a predetermined temperature and which has high luminous efficiency.

[Brief description of drawings]

FIG. 1 is a sectional view of an inductively coupled electrodeless discharge lamp showing a first embodiment of the present invention.

FIG. 2 is a sectional view of an inductively coupled electrodeless discharge lamp showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of an inductively coupled electrodeless discharge lamp showing a third embodiment of the present invention.

FIG. 4 is a sectional view of an inductively coupled electrodeless discharge lamp showing a fourth embodiment of the present invention.

FIG. 5 is a sectional view of an inductively coupled electrodeless discharge lamp showing a fifth embodiment of the present invention.

FIG. 6 is a sectional view of an inductively coupled electrodeless discharge lamp showing a sixth embodiment of the present invention.

FIG. 7 is a sectional view of an inductively coupled electrodeless discharge lamp showing a seventh embodiment of the present invention.

FIG. 8 is a sectional view of an inductively coupled electrodeless discharge lamp showing an eighth embodiment of the present invention.

FIG. 9 is a sectional view of an inductive coupling type electrodeless discharge lamp showing a ninth embodiment of the present invention.

FIG. 10 shows a tenth embodiment of the present invention and is a cross-sectional view of an illumination device using an inductively coupled electrodeless discharge lamp as a light source.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Inductively coupled electrodeless discharge lamp 10 ... Arc tube 11 ... Expansion part 12 ... Projection cylinder part 13 ... Main discharge space 14 ... Plasma discharge 15 ... Closure body 16 ... Glass adhesive 17 ... Starting electrode 20 ... Insulating film 22 ... Conductive film 23 ... Antioxidant and insulating film 25 ... High-frequency oscillation circuit 26 ... Starting circuit 30 ... Excitation coil 31 ... Coil conductor 40 ... Plug body 50 ... Probe 80 ... Lighting equipment body 81 ... Reflector 82 ... Front glass

Claims (8)

[Claims] 1. A bulging portion having a main discharge space formed therein, and a protruding cylinder portion protruding from the bulging portion and communicating with the main discharge space, wherein a luminescent medium and a rare gas are enclosed. And an excitation coil that surrounds the bulging portion to generate a magnetic field coupling discharge in the arc tube, and a heat insulating member that is provided on the protruding cylinder portion and covers the protruding cylinder portion. An inductively coupled electrodeless discharge lamp characterized by the above. 2. A bulging portion having a main discharge space formed therein, and a protruding cylinder portion protruding from the bulging portion and communicating with the main discharge space, wherein a luminescent medium and a rare gas are enclosed. A light emitting tube, an excitation coil that surrounds the bulging portion and that generates a magnetic field coupled discharge in the light emitting tube, and a conductive member that is provided on the protruding tube portion and covers the protruding tube portion. An inductively coupled electrodeless discharge lamp characterized by the above. 3. The inductively coupled electrodeless discharge lamp according to claim 2, wherein the conductive member also serves as a starting electrode connected to a starting circuit. 4. The inductively coupled electrodeless discharge lamp according to claim 2, wherein the conductive member is a conductive coating. 5. The inductively coupled electrodeless discharge lamp according to claim 2, wherein the conductive member is covered with a film for preventing oxidation. 6. The inductively coupled electrodeless discharge lamp according to claim 1, wherein the arc tube is made of translucent ceramic. 7. An inductively coupled electrodeless discharge lamp according to any one of claims 1 to 6, and a high frequency oscillation circuit for supplying high frequency power to an excitation coil of the discharge lamp. A characteristic lighting device for an inductively coupled electrodeless discharge lamp. 8. An inductively coupled electrodeless discharge lamp according to any one of claims 1 to 6, a high frequency oscillating circuit for supplying high frequency power to an excitation coil of the discharge lamp, and these inductively coupled electrodeless discharge lamps. An illuminating device comprising: an electrode discharge lamp and a luminaire containing a high-frequency oscillation circuit.