JPH0589853A - Solenoid magnetic field type discharge lamp - Google Patents

Abstract

PURPOSE:To enhance the total efficiency of a lamp by enhancing the efficiency of an excitor coil. CONSTITUTION:A light emissive substance is encapsulated in a photo- transmissive bulb 10, and therein plasma discharge is generated by a high frequency excitor coil 20 arranged as surrounding the bulb, and thereby the light emissive substance is allowed to make light emission. In this solenoid magnetic field discharge lamp, conductors 21, 22 constituting the excitor coil shall assume a flat plate having a section which is flat in the direction across the coil axis. This increases the surface area to lessen the surface resistance, which lessens the current resistance to lead to enlargement of the heat radiating effect, and thereby the coil efficiency is enhanced. Because the flat surface of each conductor is arranged in the direction across the coil axis the rate of shutting the light emitted by the bulb is lessened.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A generally well-known high pressure metal vapor discharge lamp, that is, an HID discharge lamp, has electrodes made of a refractory metal structure sealed at both ends of an arc tube, and an arc discharge is generated between these electrodes. The luminescent metal generated and sealed in the bulb is ionized and excited to emit light.

However, in the lamp having such a structure, since the electrodes are arranged in the bulb, the structure for sealing the electrodes is complicated, and special measures are required to prevent leakage from the electrode sealing portion. In addition, since the electrodes are exposed to the discharge space, various problems such as erosion of the electrodes occur.

A solenoid magnetic field type discharge lamp has been attracting attention as a lamp for solving such a problem of the electrode type discharge lamp. In a solenoid magnetic field type discharge lamp, a light emitting substance is enclosed in a transparent bulb, and a high frequency excitation coil is arranged so as to surround the bulb. The excitation coil causes arc discharge by plasma in the bulb to emit the light. Since the substance is made to emit light, it is also referred to as an electrodeless discharge lamp because there is no electrode inside the bulb, and it is possible to solve the problem of the electrode type lamp.

By the way, in this type of solenoid magnetic field type discharge lamp, since discharge is performed with a low impedance, it is necessary to pass a high frequency of a large current of about 20 amperes in the excitation coil, and the resistance loss in the coil causes a lamp loss. This will have a major impact on overall efficiency. That is, in this type of solenoid magnetic field type discharge lamp, the efficiency of the excitation coil is the main factor that influences the lamp efficiency. Therefore, it is desired to improve the efficiency of the excitation coil.

Conventionally, for example, Japanese Patent Laid-Open No. 12275/1990
No. 3 discloses a solenoid magnetic field type discharge lamp, which proposes a device for improving coil efficiency. That is, in this publication, in order to improve the efficiency of the excitation coil, it is important to reduce the loss of high-frequency current due to the excitation coil surrounding the valve and to prevent the light emitted from the valve from being blocked by this coil. Has been done. Therefore, in this publication, the conductivity of the surface of the excitation coil is increased and the reflectance is increased.

[0007]

However, the means for reducing the high frequency loss of the excitation coil does not depend solely on the conductivity of the surface of the excitation coil or the reflection characteristics.

That is, the inventors of the present invention have studied and studied, and in order to reduce the high frequency loss of the excitation coil and improve the efficiency, the surface area is increased to reduce the skin resistance to reduce the heat loss, and the coil is reduced. It was found that it is necessary to reduce the light-shielding effect due to.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a solenoid magnetic field type discharge lamp capable of improving the efficiency of the excitation coil and the overall efficiency of the lamp.

[0010]

In order to achieve the above-mentioned object, the present invention encloses a luminescent substance in a translucent bulb, and arranges a high frequency excitation coil so as to surround at least a part of the bulb, In a solenoid magnetic field type discharge lamp in which a plasma discharge is generated in the bulb by the excitation coil to cause the luminescent substance to emit light, the conductor forming the excitation coil has a cross-sectional shape in a direction intersecting the coil axial direction. It is characterized by having a flat plate shape having a flat shape along.

[0011]

As described above, the present inventors, as a factor for improving the efficiency of the excitation coil, reduce the skin resistance to reduce the high frequency resistance loss, reduce the heat loss, and reduce the light shielding effect. Noticed that it needs to be small.

Now, considering the enhancement of the skin effect of the excitation coil to reduce the resistance loss, the conventional coil uses a wire having a circular cross section as shown in FIG. Compared with, the surface area is small. As is well known, a high-frequency current in a conductor flows on the surface of the conductor. Therefore, if the surface area is large, the current path becomes large and the resistance becomes small. From this,
If the cross-sectional shape is made non-circular instead of circular, the surface area becomes large and the resistance can be made small.

Further, if the resistance is small, heat generation is reduced, the temperature rise of the coil is prevented, and if the cross-sectional shape is non-circular, the surface area is increased and the heat radiation effect is increased, so that the temperature of the coil is increased. This lowers the coil efficiency and prevents obstacles such as surface oxidation and creep deformation.

From the above, attention was paid to making the cross-sectional shape of the coil non-circular. In this case, if the adjacent coils are close to each other, an induced current is generated between them, and they have a thermal effect on each other, and the light emitted from the bulb is blocked.

Therefore, the cross-sectional shape of the conductor of the excitation coil is a flat plate shape having a flat shape along the direction intersecting the coil axis direction, thereby increasing the surface area, reducing the high frequency resistance, and increasing the temperature. Since the number of conductors can be reduced and the thickness of the conductors can be reduced, the distance between adjacent conductors can be increased, so that the light blocking effect can be reduced.

[0016]

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

In the figure, reference numeral 10 denotes a bulb which is an outer cover, and is made of, for example, a high melting point glass such as synthetic quartz or a transparent ceramic material such as alumina. The bulb 10 is filled with a light-emitting substance which emits light by an arc discharge 11 by plasma, for example, an iron halide such as iron iodide when used as a light source for ultraviolet irradiation. In addition to the light emitting substance, at least one rare gas for starting such as argon, xenon, krypton, neon, etc. is enclosed in the bulb 10.

An excitation coil 20 is arranged around the valve 10. Both ends of the excitation coil 20 are high frequency power sources 3
It is connected to 0, and a high frequency current is supplied by the high frequency voltage supplied from the high frequency power supply 30.

Due to such a high-frequency current, a magnetic field A is generated in the excitation coil 20 along the coil axis direction O-O of the excitation coil 20, whereby the inside of the valve 10 accommodated in the central space of the coil 20. A donut-shaped arc discharge 11 caused by plasma surrounding the coil axis OO
Occurs. The discharge metal 11 ionizes and excites the luminescent metal to emit ultraviolet rays, which pass through the bulb 10 and are emitted to the outside.

The excitation coil 20 is made of a highly conductive metal such as high-purity aluminum, copper, or silver, and the cross-sectional shape of the conductor corresponding to the coil wire is flat. That is, the excitation coil 20 has a shape in which a metal band is formed in a spiral shape, and the flat surface has a coil axis O-.
It extends in the direction intersecting with O.

In this embodiment, the number of turns of the coil is set to about 2 turns, and the upper winding portion 21 and the lower winding portion 2 shown in the figure are used.
2 intersects with the coil axis O-O while being inclined in opposite directions. The inclination angle θ formed by the flat surface portion with respect to the coil axis OO is preferably 45 to 90 °.

As a concrete example of dimensions, the plate thickness t of the coil conductor is 2 mm, the coil inner diameter d ₁ is 36 mm, and the coil outer diameter d.
₂ is 62 mm, the minimum distance g between the adjacent conductors 21 and 22 is 2 mm, and the inclination angle θ is 80 °.

In the solenoid magnetic field type discharge lamp having such a structure, that is, the electrodeless discharge lamp, when a high frequency voltage is supplied from the high frequency power source 30 to both ends of the excitation coil 20, a high frequency current is passed through the coil 20. Due to this high-frequency current, a magnetic field A is generated in the excitation coil 20 along the coil axis direction O-O of the excitation coil 20, whereby the valve 1
A doughnut-shaped arc discharge 11 due to plasma is generated in zero. The discharge metal 11 ionizes and excites the luminescent metal to emit ultraviolet rays, which pass through the bulb 10 and are emitted to the outside. In such a lamp, since the conductor of the coil 20 is formed into a strip shape having a flat cross section, the surface area is increased in the case of the same cross sectional area as compared with the case of the circular cross section.

Therefore, the skin effect is expanded and the loss of high frequency current is reduced. That is, as the surface area increases, the flow path becomes larger and the resistance of the current is reduced, so that the coil efficiency is improved. Further, when the surface area is large, the heat dissipation area is increased, so that the cooling property is improved and the surface temperature of the coil is lowered in combination with the decrease in the resistance. This means that less energy is wastedly released as heat, so the coil efficiency is improved, and obstacles such as surface oxidation and creep deformation of the coil are prevented.

Since the conductor having a flat cross section as described above is arranged by extending its flat surface in the circumferential direction so as to intersect the coil axis OO, the ratio of generating an eddy current is small. Moreover, the ratio of blocking the light emitted from the bulb 10 in the radial direction is reduced. That is, as shown in FIG. 3, in the case of the coil 40 made of a wire having a circular cross section, the surface area is small relative to the cross sectional area and the skin effect is small, so that the resistance to high frequency current is large.

Further, the coil 40 made of a wire having a circular cross section has a relatively large dimension s along the coil axis OO, so that the coil spacing is small. Therefore, as shown in FIG. 3, the line of magnetic force A collides with the coil at a high rate. When the lines of magnetic force collide with the conductor, eddy current is generated in the conductor as shown in FIG. On the other hand, when the lines of magnetic force are parallel to the conductor, no eddy current is generated as shown in FIG. Such an eddy current becomes a resistance of the current flowing through the coil.

Therefore, it is preferable that the conductors do not block the magnetic lines of force as much as possible, and the flat conductors 21 and 22 as shown in FIG.
Is intersected with the coil axis OO at an inclination angle θ, the plate thickness t of the conductors 21 and 22 is thin, and the extending direction of the plane is substantially parallel to the direction of the magnetic line of force that is a hyperbola. , 22 block the line of magnetic force A less.

Therefore, when the flat plate-shaped conductors 21 and 22 cross the coil axis O--O at an inclination angle .theta. So as to face each other in opposite directions, the resistance due to eddy current is reduced, Also in this respect, the coil efficiency can be improved.

When the flat conductors 21 and 22 are installed such that their planes intersect the coil axis OO, the plate thickness t
When is circular, it is thinner than s, so that the ratio of blocking the light emitted in the radial direction is small.

In particular, when the flat plate-shaped conductors 21 and 22 cross each other in the opposite directions with respect to the coil axis OO at an inclination angle θ, the adjacent conductors 21 and 22 have the same diameter. Since the outer sides of the directions oppose each other so as to be separated from each other, the direction of the ultraviolet rays extending from the bulb 10 in the radial direction and the direction extending in the outer diameter direction of these conductors 21, 21 are close to each other, and the ratio of blocking light is further reduced.

If the number of turns of the coil is set to about 2 turns, the adjacent conductors 21 and 22 are inclined in the opposite directions to each other so that they can easily face each other as described above, and the number of turns is small, so that it is not provided in the valve 10. It is difficult to generate a desired electric field, the arc is easily stabilized, and the resistance can be reduced, so that a large current can be easily passed through the coil. Therefore, according to the structure of the above embodiment, the overall efficiency of the lamp is improved.
For example, if the arc tube bulb 10 has a diameter of 22 mm, 300
With W input, the efficiency reached 89%.

Further, it was confirmed from a numerical calculation simulation that the light-shielding rate was only 4%, and that the surface temperature of the coil conductor was about 250 ° C., and that it could withstand lighting for 10,000 hours. The present invention is not limited to the above embodiment.

That is, the luminescent metal of the present invention is not particularly limited, and is applicable not only to all the luminescent metals used in conventionally known electrode-type discharge lamps, but also to electrodes. Due to the above reaction, it is possible to use a luminescent substance, which has hitherto been limited in application to a discharge lamp.

[0034]

As described above, according to the present invention, since the conductor forming the exciting coil has a flat cross-sectional shape, the surface area increases, the skin resistance decreases, and the resistance to current decreases. Since the surface area is large, the heat dissipation effect is increased, and in combination with the decrease in the resistance, self-heating is reduced and the coil efficiency is improved. And
Since such a conductor with a flat cross section is arranged such that its flat surface intersects with the coil axis, the amount of eddy current generated is small and the light emitted from the valve is associated with the reduction in thickness. The ratio of shading is reduced. Therefore, the overall efficiency of the lamp is improved.

[Brief description of drawings]

FIG. 1 is a front view of a solenoid magnetic field type discharge lamp showing an embodiment of the present invention.

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

FIG. 3 is a sectional view of a conventional solenoid magnetic field type discharge lamp using a circular wire.

FIG. 4 is an explanatory diagram showing an eddy current generation phenomenon.

[Explanation of symbols]

10 ... Bulb, 11 ... Arc discharge, 20 ... Excitation coil,
21, 22 ... Conductor, 30 ... Power supply.

Claims (5)

[Claims] 1. A luminescent material is enclosed in a translucent bulb,
A high-frequency excitation coil is arranged so as to surround the bulb, and the excitation coil constitutes the excitation coil in a solenoid magnetic field type discharge lamp in which a plasma discharge is generated in the bulb by the excitation coil to cause the luminescent substance to emit light. The solenoid magnetic field discharge lamp is characterized in that the conductor has a flat plate shape having a flat cross section along a direction intersecting the coil axis direction. 2. The solenoid magnetic field type discharge lamp according to claim 1, wherein the number of turns of the excitation coil is about 2 turns. 3. The conductor having a flat cross section, wherein the flat surfaces intersect with each other at a predetermined inclination angle with respect to the coil axial direction.
The solenoid magnetic field type discharge lamp described in. 4. The solenoid magnetic field type discharge lamp according to claim 3, wherein an inclination angle θ between the flat surface of the conductor having a flat cross section and the coil axis is in the range of 45 to 90 °. 5. The excitation coil is made of aluminum, copper,
The solenoid magnetic field type discharge lamp according to claim 4, wherein the discharge lamp is made of silver or an alloy thereof.