JPH0855612A - Inductively coupled electrodeless discharge lamp and lighting system using the same - Google Patents

Abstract

PURPOSE:To obtain an inductively coupled electrodeless discharge lamp of such structure that an arc tube can be prevented from coming in contact with an excitation coil and a minute space can be kept between both the tube and the coil and a lighting system using the lamp. CONSTITUTION:An inductively coupled electrodeless discharge lamp has an arc tube 10 wherein a discharging space 13 is formed and a luminous medium is filled, an excitation coil 20 for generating magnetic field coupled discharge in the tube 10, and an abutting member 25 arranged on the inner surface of the coil 20 and for preventing the tube 10 from coming in contact with the inner surface of the coil 20. The tube 10 can be consequently prevented from abutting on the member 25 to come in contact with the coil 20 even if the tube 10 and the coil 20 are combined with each other in an off-center condition. Moreover, magnetic coupling can be heightened because the tube 10 and the coil 20 are spaced from each other with a minute space kept therebetween.

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 a plasma discharge is generated in an arc tube by an excitation coil provided around the arc tube, and the discharge causes a luminous medium enclosed in the arc tube to emit light. The present invention relates to an electrodeless discharge lamp and a lighting device using the same.

[0002]

2. Description of the Related Art In a normal high pressure metal vapor discharge lamp, electrodes are sealed at both ends of an arc tube bulb, an arc discharge is generated between these electrodes, and this discharge ionizes and excites a luminous medium enclosed in the bulb. It is designed to emit light. However, such a lamp requires an electrode component because the electrode has to be arranged inside the bulb, and the sealing structure of the electrode is complicated, which is a special measure for preventing leakage from the electrode sealing part. However, since the electrodes are exposed to the discharge space, the electrodes are eroded, blackening occurs due to the adhesion of the electrode material to the wall of the tube, and the electrode life is shortened due to electrode damage.

As a lamp that eliminates such drawbacks,
For example, JP-A-2-12753 proposes an inductively coupled electrodeless discharge lamp. The inductively coupled electrodeless discharge lamp encloses a light emitting medium, for example, a metal halide, which emits light by generating a magnetic field coupling in a transparent arc tube having a single-tube or double-tube structure, and surrounds the arc tube. A high-frequency excitation coil is provided to generate a plasma by magnetic field coupling in the arc tube by the excitation coil, and the metal halide serving as the emission medium is discharged and emitted by the plasma. Since there is no such problem, there is an advantage that the drawbacks in the case of the electrode type lamp described above can be eliminated.

An inductively coupled electrodeless discharge lamp of this type has, for example, a high-frequency excitation coil surrounding the arc tube at the time of starting.
When a high frequency current of about 3.56 MHz is passed, a strong electromagnetic field is generated in the exciting coil along the coil axis direction, and this electromagnetic field causes a donut-shaped plasma discharge in the arc tube. This plasma discharge ionizes and excites the luminescent medium to emit light, which is transmitted through the tube wall of the arc tube and radiated to the outside.

In the inductively coupled electrodeless discharge lamp that operates as described above, a high magnetic field supplied to the excitation coil generates a strong magnetic field in the arc tube, which causes plasma discharge. Higher magnetic coupling from the coil to the arc tube improves efficiency.
Then, in order to enhance the magnetic coupling between the excitation coil and the arc tube, it is desirable that the interval between the excitation coil and the arc tube is made small, and in extreme cases, they are in contact with each other.

[0006]

However, when the excitation coil and the arc tube are in contact with each other, the arc tube which becomes high in temperature during lighting comes into contact with the low temperature excitation coil, and therefore, due to the temperature difference, the double tube is generated. In the case of a structured arc tube, the outer tube may be heat-shocked, and in the case of a single tube, the arc tube may be directly heat-shocked to cause cracks. Therefore, the excitation coil and the arc tube must be spaced apart so that they do not contact each other. On the other hand, in order to increase the magnetic coupling, it is required to make the mutual intervals minute.

In order to achieve such a structure, the arc tube and the excitation coil may be manufactured with high precision, and the centers of both may be correctly aligned. In the case of a single tube, the arc tube is made of quartz or ceramic. In the case of a double tube, the outer tube is made of hard glass, quartz, or the like, so that the outer shape is likely to have variations in manufacturing, which makes it difficult to perform highly accurate dimensional control.

For this reason, the arc tube and the excitation coil may be assembled in an off-center state, so that the tube wall of the arc tube may partially contact the excitation coil. Such contact may cause damage to the arc tube due to the temperature difference as described above, and since the temperature of the arc tube locally drops at the contact part, this part becomes the coldest part, and this coldest part. The encapsulation substance aggregates on the surface, which causes problems such as normal lighting cannot be maintained.

The present invention has been made in view of the above circumstances. An object of the present invention is to prevent the arc tube from coming into contact with the excitation coil to prevent the arc tube from being broken or the undesired aggregation of the encapsulating substance. It is an object of the present invention to provide an inductively coupled electrodeless discharge lamp and a lighting device using the same, which prevent the above-mentioned phenomenon and enhance the magnetic coupling while maintaining a minute gap therebetween.

[0010]

According to a first aspect of the present invention, a discharge space is formed inside, and a discharge tube in which a medium that emits light by discharge is sealed, and the discharge tube is surrounded by the discharge tube. An excitation coil that is provided to generate a magnetic field coupled discharge in the arc tube, and an abutment member that is provided on the inner surface of the excitation coil and that prevents the arc tube from contacting the inner surface of the excitation coil, are provided. Characterize.

Here, the arc tube includes a single tube structure and a double tube structure composed of an inner tube and an outer tube. The invention of claim 2 is characterized in that the contact member is formed of an insulator having a lower thermal conductivity than that of the excitation coil.

According to a third aspect of the present invention, the exciting coil has a plurality of turns, and the abutment member connects the coil portions having the plurality of turns. According to a fourth aspect of the present invention, there is provided the inductively coupled electrodeless discharge lamp according to any one of the first to third aspects, a luminaire in which the inductively coupled electrodeless discharge lamp is housed, and the inductively coupled type. Fixing means for fixing the excitation coil of the electrodeless discharge lamp to the lighting fixture and the arc tube inserted through the excitation coil are attached to the lighting fixture, and the arc tube shakes with respect to the lighting fixture in this mounting state. And a light emitting tube swinging support means that is movably supported.

[0013]

According to the invention of claim 1, since the contact member for preventing the arc tube from coming into contact with the inner surface of the excitation coil is provided on the inner surface of the excitation coil, the arc tube and the excitation coil are assembled in an off-center state. Even if the arc tube is touched, the contact of the arc tube with the contact member prevents the contact with the excitation coil. Therefore, breakage of the arc tube and undesired aggregation of the enclosed substance are prevented. Moreover, since the arc tube and the excitation coil are spaced apart from each other with a minute gap, the magnetic coupling can be enhanced and the efficiency becomes excellent.

According to the second aspect of the present invention, since the contact member is formed of an insulator having a lower thermal conductivity than the excitation coil, even if the arc tube contacts the contact member, the contact portion is locally formed. It is possible to prevent the damage due to the temperature difference of the arc tube and the aggregation of the encapsulating substance without causing the temperature to decrease.

According to the third aspect of the present invention, since the contact member connects the coil portions having a plurality of turns to each other, the distance between the coil portions does not change due to thermal deformation, vibration, etc. The magnetic coupling function can be maintained.

According to the fourth aspect of the present invention, the light emitting tube inserted into the excitation coil is supported by the lighting apparatus, and the light emitting tube is swingably supported by the lighting apparatus in this supporting state. Since the arc tube supporting means is provided, the arc tube is off-centered to the excitation coil and the arc tube rocking supporting means allows displacement of the arc tube. Therefore, the arc tube is in contact with the contact member. Can be mechanically supported. Therefore, no unreasonable stress is generated in the arc tube, the excitation coil, or the lighting fixture, and damage to these can be prevented.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings. FIG. 1 shows an inductively coupled electrodeless discharge lamp and its lighting circuit. FIG. 2 is a cross-sectional view thereof, FIG. 3 is an enlarged view of a contact member, and FIG. 4 is the above electrodeless discharge lamp as a light source. It is a sectional view of the entire illumination device.

In FIG. 1, reference numeral 1 is an inductively coupled electrodeless discharge lamp, and 10 is its arc tube. Arc tube 10
Has a double pipe structure including an inner pipe 11 and an outer pipe 12.
The inner tube 11 is made of quartz or translucent alumina, or a single crystal or polycrystalline translucent ceramic material such as sapphire or garnet.
1 has, for example, an outer diameter in the major axis direction of about 32.5 mm (an inner diameter of about 3
0. mm), the outer diameter in the minor axis direction is approximately 25.0 mm (inner diameter approximately 2
2.5 mm) and has a discharge space 1 inside.
3 are formed. In the discharge space 13, a luminescent substance that emits light by the plasma discharge 14 generated in a donut shape, for example, a metal halide such as scandium iodide ScI ₃ and sodium iodide NaI, and argon, xenon, krypton, neon, etc. The rare gas for starting which consists of at least 1 sort (s) of the said gas is enclosed.

A starting probe 15 is connected to one end of the inner pipe 11 and is located on the center line. The starting probe 15 has an outer diameter of, for example, 5.0 mm (inner diameter of about 2.
5mm) and the length is about 20mm, and it has a cylindrical shape.
It is partitioned by a partition wall 16 so as not to communicate with the discharge space 13 in the inside 1. The probe 15 is filled with a rare gas that promotes a starting discharge, such as krypton. And
A starting electrode 17 is attached to the tip of the probe 15.

The outer tube 12 is made of hard glass or quartz and surrounds the inner tube 11. One end of the outer tube 12 is sealed, and the probe 15 is hermetically penetrated through the sealed portion 18. From the sealed portion 18, the probe 15 is inserted.
A high frequency excitation coil 20 is arranged around the arc tube 10 having the double tube structure as described above. This excitation coil 2
In the case of the present embodiment, 0 is configured to be wound around the arc tube 10 for two turns, and is formed by two conductors 21 and 21 substantially corresponding to coil wire. Each of these conductors 21 and 21 has, for example, a thickness of 2 mm and an inner diameter of 3
6mm, 62mm outer diameter of high-purity aluminum, or copper, silver, or the like, which is formed of a ring-shaped metal disk having excellent conductivity, or copper, silver, or the like on the surface of a metal plate made of iron, stainless steel, or the like. Copper, silver, or the like is formed on the surface of a metal plate made of a so-called clad material, or made of iron, stainless steel, etc. by sticking together a good conductor such as gold.
The ring-shaped conductors 21 and 21 are formed by plate-shaped circular discs plated with gold or the like, and these ring-shaped conductors 21 are arranged at a predetermined interval in the coil axial direction. , 21 are welded to each other to be connected to each other to form a spiral energization path as a whole.

The high frequency excitation coil 20 composed of such a pair of conductors 21, 21 is connected to the lighting circuit 30. The lighting circuit 30 includes a high frequency oscillation circuit 31 and a starting circuit 3.
The high frequency oscillation circuit 31 is composed of a circuit (not shown) for converting an alternating current into a direct current, which is connected to a commercial power source, a high frequency generating amplifier, a matching circuit, and the like. The high frequency oscillation circuit 31 converts the frequency of the commercial power supply into a high frequency of 13.56 MHz, for example, and supplies this high frequency to the high frequency excitation coil 20.

The starting circuit 32 boosts the high frequency generated by the high frequency oscillating circuit 31 to increase the frequency of the probe 15.
It is adapted to be supplied to the starting electrode 17 attached to the tip of the.

The high-frequency excitation coil 20 as described above has a plurality of abutting members 2 which are spaced apart from each other in the circumferential direction on the inner surface thereof.
5 is attached. These abutting members 25 ... Are made of an insulator and have a thermal conductivity lower than that of the conductors 21, 21 constituting the excitation coil 20, for example, quartz or ceramic, or a heat resistant resin. It is formed of an insulator such as. As shown in FIG. 3, the abutting members 25 have an E-shaped cross section, for example, and the inner edges of the conductors 21 and 21 constituting the excitation coil 20 are fitted in the recesses 26 and 26 that are vertically separated from each other. The convex portions 27 formed between the concave portions 26, 26 are joined to each other by the conductors 21, 2 of the excitation coil 20.
The vertical dimension of 1 is maintained.

The contact members 25 ...
No. 0 is joined by mechanical fitting or glass adhesive, etc., and in this joined state, the inner surface of the abutting members 25 ... Is directed toward the inner side (center direction) of the inner surface of the excitation coil 20 as shown in FIG. As shown in the figure, it is designed so as to project by a minute dimension s. As a result, even if the arc tube 10 inserted into the excitation coil 20 tries to contact the inner surface of the excitation coil 20, it is prevented that the arc tube 10 contacts the contact members 25 ... And contacts the inner surface of the excitation coil 20. It has become.

The inductively coupled electrodeless discharge lamp 1 having such a structure is attached to a lighting fixture 40 as shown in FIG. 4, for example, to form a lighting device. The lighting fixture 40 includes a fixture main body 41 forming a housing, a frame 42 attached to the fixture main body 41, and a reflector 43.

The arc tube 10, the excitation coil 20 and the lighting circuit 30 which compose the inductively coupled electrodeless discharge lamp 1.
Are attached to the frame 42, respectively. In this case, in the excitation coil 20, the base end portions 21a, 21a extending from the ring-shaped conductors 21, 21 are fixed to the frame 42 using, for example, screws 44. Then, in contrast to such an excitation coil 20, the arc tube 10 has the excitation coil 20.
Separately from the above, it is attached to the frame 42 via the arc tube swinging support means 45 of the present invention.

The arc tube swing supporting means 45 has the following structure, for example. That is, the base 46 is fixed to the outer tube 12 of the arc tube 10, and the base 46 is detachably attached to the socket 47. Base 46
When attaching to the socket 47, a well-known screw type or bayonet method is adopted, and in this example, the pins 48 provided on the base 46 are locked to the socket 47 by pushing and rotating the base 46 into the socket 47. The bayonet method is applied.

The socket 47 is attached to the frame 42 via mounting screws 49. In this case, springs 50 ... Are fitted into the mounting screws 49. It is supported so as to be swingable. Therefore, the arc tube 10 is swingably supported by the frame 42.

A lighting circuit 30 including a high frequency oscillating circuit 31 and a starting circuit 32 is attached to the frame 42. The operation of the inductively coupled electrodeless discharge lamp 1 and the lighting device having such a configuration will be described. When starting the lamp, for example, 13.5 from the high frequency oscillation circuit 31.
At the same time as sending a high frequency current of 6 MHz to the excitation coil 20, a high frequency voltage is applied to the starting electrode 17 through the starting circuit 32. As a result, a starting glow discharge is generated in the probe 15, and the glow discharge in the probe 15 generates a high frequency plasma discharge 14 in the discharge space 13 of the inner tube 11 in which a strong high frequency electric field is generated by the high frequency excitation coil 20. Induce. This plasma discharge 14 causes the discharge space 13
A light emitting medium such as a metal halide contained in is ionized and excited to emit visible light, and this light is transmitted to the outside through the tube walls of the inner tube 11 and the outer tube 12.

When the discharge becomes stable after such a start,
The impedance of the arc tube 10 is lowered, the voltage generated on the secondary side of the matching circuit is automatically lowered, a high frequency magnetic field is generated by the high frequency excitation coil 20 in the arc tube 10, and the plasma discharge 14 is generated by this magnetic field coupling. Will be maintained.

The light emitted from such a discharge lamp 1 is
The light is reflected by the reflector 43 of the lighting fixture 40 and emitted downward. In the inductively coupled electrodeless discharge lamp 1 that operates as described above, a high-frequency current supplied to the excitation coil 20 generates a strong magnetic field in the arc tube 10, thereby generating the plasma discharge 14. , Excitation coil 2
High magnetic coupling from 0 to arc tube 10 leads to improved efficiency. Therefore, it is desirable to reduce the distance between the excitation coil 20 and the outer tube 12 of the arc tube 10.

However, the excitation coil 20 and the outer tube 12
, The outer tube 10 having a high temperature during lighting comes into contact with the low-temperature excitation coil 20, so that the outer tube 12 may be cracked due to the temperature difference. Therefore,
The excitation coil 20 and the outer tube 12 must be spaced apart from each other so that they do not come into contact with each other.

In order to satisfy such requirements, the outer tube 12
It suffices to manufacture the excitation coil 20 and the excitation coil 20 with high accuracy and to align the centers of both accurately. However, since the outer tube 12 is made of hard glass, quartz, or the like, the outer tube 12 is likely to have dimensional variations in manufacturing, Therefore, it is difficult to control dimensions with high accuracy.

For this reason, the outer tube 12 and the excitation coil 20 may be assembled in an off-center state, and there is a concern that the outer tube 12 may partially contact the excitation coil 20. On the other hand, in the present invention, since the contact member 25 is provided on the inner surface of the excitation coil 20, even if the outer tube 12 of the arc tube 10 tries to contact the excitation coil 20, the outer tube 12 contacts the contact member 25. This prevents contact with the excitation coil 20.

Therefore, a local temperature difference caused by the contact of the outer tube 12 with the excitation coil 20 does not occur,
The outer tube 12 is prevented from cracking. Further, when the temperature of the outer tube 12 locally drops at the contact portion, the side wall of the inner tube 11 facing this portion becomes the coldest portion, and the enclosed substance aggregates in this coldest portion, so that normal lighting can be maintained. However, since the contact member 25 prevents the outer tube 12 from coming into contact with the excitation coil 20, aggregation of the encapsulated substance is also prevented.

When the outer tube 12 comes into contact with the contact member 25, the outer tube 12 and the excitation coil 20 are separated from each other with a minute gap s, so that the magnetic coupling between them can be enhanced. High efficiency can be obtained.

Since the contact member 25 is made of an insulator having a lower thermal conductivity than that of the excitation coil 20,
Even if the outer tube 12 comes into contact with the abutting member 25, the temperature of the contact portion does not locally drop, and damage to the arc tube 10 due to a temperature difference and aggregation of the enclosed substance are prevented.

Further, the abutting member 25 includes the concave portions 26, 26.
And the convex portion 27, and the excitation coil 2 is provided in the concave portions 26, 26.
Since the inner surface side end portions of the conductors 21, 21 constituting each turn of 0 are fitted, the conductors 21,
The distance between 21 will be maintained. Therefore, the mutual spacing between these conductors 21, 21 does not change due to thermal deformation or vibration, the shape of the excitation coil 20 is maintained, and a high magnetic coupling function for the arc tube 10 can be maintained.

Further, the abutting member 25 allows the conductors 21, 21
Since the space between them is maintained, the inductance change of the coil can be kept small, and the matching deviation of the circuit can be reduced. Therefore, it is possible to prevent a change in the lamp input and an overload of the high frequency oscillation circuit 31.

By the way, when the outer tube 12 comes into contact with the abutting member 25 as described above, the outer tube 12 comes into contact with the abutting member 2.
It will be displaced compared to before it was hit and restrained. At this time, the arc tube 10 is attached to the base 46 and the socket 4.
If the outer tube 12 is immovably fixed to the frame 42 of the luminaire 40 via 7, it becomes impossible to allow the outer tube 12 to move when the outer tube 12 abuts on the abutting member 25.
A stress is generated at the abutting position of and the mounting position on the frame 42.

However, in the case of this embodiment, the socket 47
Since the springs 50 are supported by the springs 50, the socket 47 can be swung, and the arc tube 10 can be displaced.
Therefore, even if the outer tube 12 contacts the contact member 25, it is possible to prevent the generation of stress.

The present invention is not limited to the above embodiment. That is, the arc tube 10 of the above-mentioned embodiment has a double tube structure with the inner tube 11 and the outer tube 12, but it can be implemented even if the inner tube 11 only has a single tube structure.

The means for swingably supporting the arc tube 10 with respect to the luminaire 40 includes the socket 47 and the frame 4.
Not only is it swingably attached to 2, but the arc tube 10 is swingably attached to the base 46, or the base 46 is swingably attached to the socket 47, and various other modifications are possible. Is.

[0044]

As described above, according to the invention of claim 1, even when the arc tube and the excitation coil are assembled in the off-center state, the arc tube contacts the contact member and contacts the excitation coil. To be prevented. Therefore, breakage of the arc tube and undesired aggregation of the enclosed substance are prevented. Moreover, since the arc tube and the excitation coil are spaced apart from each other with a minute gap, the magnetic coupling can be enhanced and the efficiency becomes excellent.

According to the second aspect of the present invention, since the contact member is formed of an insulator having a lower thermal conductivity than the excitation coil, even if the arc tube contacts the contact member, the contact portion is locally formed. Therefore, the temperature of the arc tube is not lowered, and the damage due to the temperature difference of the arc tube and the aggregation of the enclosed substance are prevented.

According to the third aspect of the invention, since the abutting member connects the coil portions having a plurality of turns to each other, the distance between the coil portions does not change due to thermal deformation, vibration, etc. The binding function can be kept high.

According to the invention of claim 4, since the arc tube swinging support means for swingably supporting the arc tube with respect to the lighting fixture is provided, the above-mentioned light emission occurs when the arc tube abuts on the abutting member. Since the tube swing support means allows the arc tube to be displaced, the arc tube, the excitation coil, and the luminaire are prevented from being unduly stressed and their damage can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram showing an inductively coupled electrodeless discharge lamp and a lighting circuit therefor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the same embodiment.

FIG. 3 is an enlarged sectional view showing an abutting member of the embodiment.

FIG. 4 is a configuration diagram showing an example of a lighting device using the electrode discharge lamp.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Inductively coupled electrodeless discharge lamp 10 ... Arc tube 11 ... Inner tube 12 ... Outer tube 13 ... Discharge space 14 ... Plasma discharge 15 ... Probe 20 ... Excitation coil 21 ... Ring conductor 25 ... Abutment member 26 ... Recess 27 ... Projection portion 30 ... Lighting circuit 31 ... High-frequency oscillation circuit 32 ... Starting circuit 40 ... Lighting equipment 41 ... Instrument body 42 ... Frame 43 ... Reflector

Claims (4)

[Claims] 1. A discharge space is formed inside, and
An arc tube in which a medium that emits light by discharge is enclosed in the discharge space, an excitation coil that surrounds the arc tube and generates a magnetic field coupling discharge in the arc tube, and an arc coil that is provided on the inner surface of the excitation coil. An inductively coupled electrodeless discharge lamp, comprising: a contact member that prevents the arc tube from coming into contact with the inner surface of the excitation coil. 2. The inductively coupled electrodeless discharge lamp, wherein the contact member is formed of an insulator having a lower thermal conductivity than that of the excitation coil. 3. The excitation coil has a plurality of turns, and the abutment member connects the coil portions of the plurality of turns to each other.
The inductively coupled electrodeless discharge lamp as described in 1. 4. The inductively coupled electrodeless discharge lamp according to any one of claims 1 to 3, a lighting fixture containing the inductively coupled electrodeless discharge lamp, and the inductively coupled electrodeless discharge lamp. Fixing means for fixing the excitation coil of the electric lamp to the lighting fixture, and the arc tube inserted through the excitation coil is attached to the lighting fixture, and the arc tube is swingable with respect to the lighting fixture in this mounting state. An illuminating device comprising: an arc tube swinging and supporting means that is supported.