JPH0589852A - Solenoid magnetic field type discharge lamp - Google Patents

Abstract

PURPOSE:To provide a solenoid magnetic field type discharge lamp, in which the excitor coil has an enlarged surface area. CONSTITUTION:A high frequency excitor coil 20 is arranged as surrounding a bulb 10 in which a light emissive substance is encapsulated, and a high frequency current is allowed to flow in this excitor coil to generate plasma discharge within the bulb, and thereby the light emissive substance is permitted to make light emission. In this solenoid magnetic field type discharge lamp, the conductor to constitute the excitor coil 20 is formed by bundling a plurality of electroconductive thin wires 21, 22 electrically insulated from one another. This enlarges the surface area to admit passage of current and lessens the resistance, which enables a large current flowing.

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. A solenoid magnetic field type discharge lamp is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-60048, in which a luminescent substance is enclosed in a transparent bulb, a high-frequency excitation coil is arranged around the bulb, and the excitation coil is radiated by a high-frequency wave. It is configured to be connected to an oscillation circuit.When a high-frequency current is passed from the high-frequency oscillation circuit to the excitation coil, a high-frequency magnetic field is generated, which causes plasma discharge in the bulb, and this discharge ionizes and excites the luminescent material. To emit light. Such a lamp 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 above-mentioned electrode type lamp.

[0005]

In this type of solenoid magnetic field type discharge lamp, a ring (donut) type electric field is generated in the bulb by an excitation coil surrounding the bulb, and plasma discharge is generated by this electric field. Therefore, the excitation coil is not in direct contact with the electric field, and thus the coupling coefficient between the excitation coil and the discharge is small. Therefore, in order to maintain stable plasma discharge in the bulb, it is necessary to generate a strong high-frequency magnetic field and induce a strong electric field. For this reason, it is necessary to flow a large current through the excitation coil.

By the way, when a high-frequency current is passed through a conductor, it has a property of flowing on the surface of the conductor. If the surface area is large, the current path becomes large and the resistance becomes small (skin effect). However, the conventional excitation coil is composed of a wire having a circular cross section, and when the cross section is circular, the surface area is smaller than that of a non-circular shape having the same cross sectional area. For this reason, the conventional excitation coil has a small skin area and a large resistance, and thus has a limit in flowing a large current.

If the resistance is high, Joule heat is generated and the temperature of the coil rises. In order to prevent the temperature rise of the coil, measures such as thickening the coil and using an air cooling device can be considered, but such a structure has drawbacks of increasing weight and complicating the device.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a solenoid magnetic field type discharge lamp capable of increasing the skin effect of the excitation coil and flowing a large current.

[0009]

In order to achieve the above-mentioned object, the present invention encloses a luminescent material in a translucent bulb, and arranges a high frequency excitation coil so as to surround the bulb. In a solenoid magnetic field type discharge lamp in which a high-frequency current is applied to generate a plasma discharge in the bulb, and the luminescent material is caused to emit light by the plasma discharge, the conductor forming the excitation coil includes a plurality of conductive thin wires. It is characterized in that they are bundled in a mutually insulated state.

[0010]

According to the present invention, since the conductor forming the excitation coil is formed by bundling a plurality of conductive thin wires in an insulated state, current flows on the surface of each thin wire and the total surface area is large. Becomes larger, the resistance loss becomes smaller,
The heat loss is also reduced and a large current can be passed.

[0011]

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

In FIG. 1A, 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 that emits light by arc discharge 12 caused by plasma, for example, a metal halide. 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 connected to a high frequency oscillation circuit 30, and a high frequency current is supplied by a high frequency voltage supplied from the high frequency oscillation circuit 30.

Due to such a high frequency current, a magnetic field is generated in the excitation coil 20 along the coil axis direction O-O of the excitation coil 20, whereby the valve 10 housed in the central space of the coil 20 is generated. A donut-shaped arc discharge 12 is generated by the plasma around the coil axis OO. The discharge 12 ionizes and excites the luminescent material to emit light, and this light passes through the bulb 10 and is emitted to the outside.

The excitation coil 20 is composed of a plurality of conductive thin wires bundled in a mutually insulated state, each of which serves as a coil wire. That is, the conductor of the excitation coil 20 is as shown in FIG.
As shown in FIG. 3B, a plurality of conductive thin wires 21, 22
These thin wires 21, 22 ...
Are electrically connected in parallel.

In the case of the present embodiment, a thin wire 21 having a large wire diameter is arranged in the central portion, and a large number of ultrafine wires 22 having a small wire diameter are arranged around the core wire 21. These fine wires 21 and extra fine wires 22 are made of high-purity aluminum,
The thin wires 21, 22 ... Are made of the same material such as copper, silver and nickel, and are insulated from each other by an insulating coating 23. The coil conductor having such a configuration has a substantially circular overall cross-sectional shape, and has the same overall cross-sectional area as that of a conventional coil made of a single wire. For example, the fine wire 21 at the center has a wire diameter of about 1.2 mm, and the extra fine wires 22 ...
50 are used.

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 to both ends of the excitation coil 20 from the high frequency oscillation circuit 30, a high frequency current flows 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, and as a result, a donut-shaped arc discharge 12 due to plasma is generated in the bulb 10.
Occurs. The light-emitting substance is ionized and excited by this discharge 12 to emit light, and this light passes through the bulb 10 and is emitted to the outside.

In such a lamp, the conductor of the coil 20 is composed of a large number of thin wires 21, 22, ...
When the whole has the same cross-sectional area, the surface area is larger than that when one wire is used. Therefore, the flow path becomes large, the skin effect is improved, and the loss of high frequency current is reduced. That is, since the resistance of the current is reduced, a large current can flow. Therefore, a large amount of energy can be supplied to the plasma discharge 12 in the bulb 10, so that the discharge can be reliably maintained. Further, as the resistance becomes smaller, the generation of Joule heat is reduced and the surface area is large, so that the heat radiation area is increased, the cooling property is improved, and the coil temperature is lowered.

Further, in the case of this embodiment, since the relatively thick thin wire 21 is arranged at the center of the conductor, the rigidity is increased. Therefore, it is possible to maintain a predetermined coil shape and prevent deformation of the coil.

In addition, in the structure shown in FIG. 1B, it is more preferable if the core wire 21 is made of a wire having a high magnetic permeability. That is, the center line 21 is made of nickel or an alloy of nickel and iron to have a wire diameter of, for example, about 0.5 mm, and the ultrafine wires 22 ... Surrounding are copper wires having a wire diameter of about 0.08 mm.
200 to 250 are used.

In such a structure, since the core wire 21 has a high rigidity, a predetermined coil shape can be maintained, and since the core wire 21 has a high magnetic permeability, the current flow to the core wire 21 is reduced. Most of the electric current is the surrounding fine wires 22 ...
Flow through the skin, and in this case, since the surface area is large, the skin effect is improved. FIG. 2 shows a second embodiment of the present invention.

In this embodiment, the excitation coil 40 has a flat cross section. That is, the excitation coil 4
The conductor of No. 0 is configured by bundling a large number of thin wires 41 ... In the present embodiment, the thin wires 41 ... There is. In addition, each thin wire 41 ... Insulation coating 4
Although it may be insulated by 2, the bare wire may be kept insulated by the resin 43.

For example, the thin wires 41 are made of copper wire having a wire diameter of 0.1 mm, and a total of 1,000 wires are impregnated with the silicon resin 43 and formed into a flat shape having a flatness of 0.05. is there.

Also in the case of such a structure, since the electric current flows on the surface of each thin wire 41, the skin effect is improved.
In addition, since the entire conductor shape is flat, the surface area is increased and the cooling performance is improved as compared with the case where the conductor is circular.

Further, since the flatness can be made thin, as can be understood from FIG. 2A, the valve 1
The ratio of blocking the light emitted from 0 is small, and the light blocking effect is reduced. Moreover, since the resin 43 maintains the overall shape, the coil shape is maintained in a good condition. It should be noted that the present invention is not limited to making the core wire 21 a large diameter or increasing the magnetic permeability, and for example, a litz wire may be used.
Further, the luminescent substance is not particularly limited, and all luminescent substances used in conventionally known electrode-type discharge lamps are applicable.

[0026]

As described above, according to the present invention, since the conductor forming the excitation coil is formed by bundling a plurality of conductive thin wires insulated from each other, the surface area through which the electric current passes becomes large and the skin area is reduced. Since the resistance becomes large and the resistance becomes small, a large current can flow. Therefore, good discharge is maintained. Further, since the resistance becomes small, Joule heat is less generated, and the temperature rise of the coil is prevented.

[Brief description of drawings]

1A and 1B show a first embodiment of the present invention, wherein FIG. 1A is a sectional view of a solenoid magnetic field type discharge lamp, and FIG. 1B is an enlarged sectional view of an excitation coil.

2A and 2B show a second embodiment of the present invention, wherein FIG. 2A is a sectional view of a solenoid magnetic field type discharge lamp, and FIG. 2B is an enlarged sectional view of an excitation coil.

[Explanation of symbols]

10 ... Bulb, 12 ... Arc discharge, 20, 40 ... Excitation coil, 21, 22, 41 ... Thin wire.

Claims (4)

[Claims] 1. A light-emitting substance is enclosed in a translucent bulb, and a high-frequency excitation coil is arranged so as to surround the bulb, and a high-frequency current is passed through the excitation coil to generate plasma discharge in the bulb. In the solenoid magnetic field type discharge lamp in which the light emitting substance is caused to emit light by the plasma discharge, the conductor forming the excitation coil is formed by bundling a plurality of conductive thin wires insulated from each other. Solenoid magnetic field type discharge lamp. 2. The conductor of the excitation coil formed by bundling a plurality of conductive thin wires, has a wire having high rigidity arranged in the central portion, and a thin wire arranged around this wire.
The solenoid magnetic field type discharge lamp described in. 3. The conductor of the excitation coil, which is configured by bundling a plurality of conductive thin wires, has a wire having a high magnetic permeability arranged in the central portion, and a wire having excellent conductivity is arranged around the wire. The solenoid magnetic field type discharge lamp according to claim 1 or 2. 4. The solenoid magnetic field type discharge device according to claim 1, wherein the conductors of the excitation coil formed by bundling a plurality of conductive thin wires are bound so that the cross-sectional shape is non-circular. Electric light.