JP3653708B2 - Electrodeless fluorescent discharge lamp - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrodeless fluorescent discharge lamp that is driven to be lit by a single electric power supply wire through which a high-frequency constant current flows.
[0002]
[Prior art]
[Patent Document 1]
US Pat. No. 3,500,118 Conventionally, an electrodeless fluorescent discharge lamp as shown in the above document is known. The principle is briefly explained. An annular iron core, in which a coil for power supply is wound around the outer periphery of a glass tube formed in an annular shape and sealed with mercury vapor, is fitted and arranged, and a high-frequency current is supplied to the coil. A high-frequency discharge current is generated inside the glass tube by electromagnetic induction through an iron core, and the phosphor inside the glass tube is caused to emit light by ultraviolet rays generated thereby. However, in such a case, the discharge current flows along the longitudinal direction of the glass tube, so that the discharge path length cannot be shortened and the cross-sectional area of the discharge path is limited. There is a drawback that the impedance cannot be lowered, and therefore the discharge start voltage and the discharge sustain voltage cannot be lowered.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide an electrodeless fluorescent discharge lamp capable of minimizing the discharge impedance by minimizing the discharge path length and maximizing the cross-sectional area of the discharge path. It is to be.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned object, an electrodeless fluorescent discharge lamp according to the present invention has an annular iron core arranged at a predetermined distance from an inner wall inside a glass tube formed in an annular shape, and applies a fluorescent paint to the inner wall of the glass tube. At the same time, the inside of the glass tube has a discharge atmosphere, and an electric wire having a high-frequency constant current passed through the center hole of the ring of the glass tube is featured.
[0005]
[Action]
A high-frequency magnetic flux is induced in the annular iron core by the electric wire that has passed a high-frequency constant current, and this magnetic flux causes a discharge current to flow around the annular iron core in the direction indicated by arrow A in FIG. Then, the electrodeless fluorescent discharge lamp is turned on.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of an electrodeless fluorescent discharge lamp according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of the whole, and FIG. 2 is a sectional perspective view thereof. In the electrodeless fluorescent discharge lamp 1, a glass tube 2 having a substantially uniform diameter is formed in an annular shape, and an annular core 3 made of a ferrite core is disposed therein. The position where the annular iron core 3 is arranged is substantially the center of the cross section of the glass tube 2, and a predetermined distance necessary for forming a discharge path between the annular iron core 3 and the inner wall of the glass tube 2 is provided. .
[0007]
A fluorescent paint is applied to the inner wall of the glass tube 2, and the inside of the glass tube 2 is in a high vacuum, and a discharge gas such as mercury and a small amount of argon (other rare gas) is sealed to form a discharge atmosphere. Argon contributes to the start of glow discharge, and when the discharge potential reaches the transition point, it shifts to steady arc discharge, and mercury vapor generates ultraviolet rays to cause the fluorescent paint to emit light.
[0008]
One electric power supply wire 4 is loosely passed through the center hole of the electrodeless fluorescent discharge lamp 1, and both ends of the electric wire 4 are connected to a high-frequency constant current source 5 made of, for example, an inverter. The electric wire 4 acts as a one-turn winding of the annular core 3 and induces a high frequency magnetic flux in the annular core 3.
[0009]
A high frequency electric field is generated around the annular core 3 in the direction indicated by the arrow A in FIG. 2 by the high frequency magnetic flux induced in the annular core 3, thereby generating a glow discharge, and when the discharge potential reaches the transition point, the next moment A transition is made to arc discharge, and a stable discharge current determined by the value of the current flowing through the electric wire 4 flows, whereby the fluorescent paint applied to the inner wall of the glass tube 2 emits light and the electrodeless fluorescent discharge lamp 1 is lit.
[0010]
As indicated by an arrow A in FIG. 2, glow discharge and arc discharge are generated around the annular core 3 in a direction perpendicular to the ring direction, so that the discharge path length is the shortest with respect to the thickness restriction of the annular core 3. It becomes. Further, since the cross-sectional area of the discharge path is determined by the distance between the annular iron core 3 and the inner wall of the glass tube 2, it can be set to an appropriate size as required. For this reason, the discharge impedance is minimized, and the discharge start voltage (transition voltage) and the discharge sustain voltage can be minimized.
[0011]
In the above embodiment, the shape of the ring of the glass tube 2 and the annular iron core 3 is circular. be able to. Moreover, although the cross-sectional shape of the glass tube 2 and the cyclic | annular iron core 3 is each made circular and square, it can be made into another shape suitably (for example, easy to shape | mold).
[0012]
【The invention's effect】
As described above, the electrodeless fluorescent discharge lamp of the present invention can minimize the discharge impedance because the discharge path length can be minimized and the discharge path cross-sectional area can be maximized. The discharge sustaining voltage can be made the lowest, the frequency of the high-frequency constant current source can be kept low, and the annular core can be reduced in size, thereby minimizing the iron loss generated in the annular core. Therefore, heat generation due to iron loss can be minimized, and furthermore, an electrodeless fluorescent discharge lamp can be moved to any position along the electric wire by allowing one electric power supply wire to pass through. In addition, an excellent effect is provided that a plurality of them can be provided in series.
[Brief description of the drawings]
FIG. 1 is a perspective view of an electrodeless fluorescent discharge lamp according to the present invention. FIG. 2 is a sectional perspective view of the electrodeless fluorescent discharge lamp.
DESCRIPTION OF SYMBOLS 1 Electrodeless fluorescent discharge lamp 2 Glass tube 3 Annular iron core 4 Electric wire 5 High frequency constant current source

Claims (1)

An annular iron core is placed inside the annular glass tube at a predetermined distance from the inner wall, and a fluorescent paint is applied to the inner wall of the glass tube, and the inside of the glass tube is made to have a discharge atmosphere, and the center hole of the glass tube ring An electrodeless fluorescent discharge lamp characterized by loosely passing an electric wire through which a high-frequency constant current is passed.

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