JPH10116594A - Electrodeless fluorescent lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress unnecessary electromagnetic radiation to the outside of an electrodeless discharge lamp without damaging appearance by providing a conductive spiral or a conductive material at the inside of a discharge container. SOLUTION: At the inside of a discharge constainer 1, a conductive spiral ring 9 is installed near the inner wall of the container around an exciting coil 6 and he ring 9 is fixed to a cylindrical sinking part. When high frequency power is supplied to the exciting coil 6 from a lighting circuit 7 and a lamp is lighted, electromagnetic radiation noise due to high frequency current is feedbacked to the lighting circuit 7 via a copper foil 5 provided on the part of the outer wall of the container 1, further, magnetic field is made by current flowing in the spiral ring 9, magnetic field is canceled with magnetic field generated from the exciting coils 6 each other and electromagnetic radiation to the outside of the discharge container is suppressed. Thus, unnecessary electromagnetic radiation to the outside of the lamp is suppressed, radiation noise is reduced, current is prevented from generating in a metal instrument when the lamp is inserted into the metal instrument and consequently damage of the lighting circuit can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrodeless fluorescent lamp which emits light by high frequency power.

[0002]

2. Description of the Related Art As a light source for illumination, a fluorescent lamp which is lit at a commercial frequency or a frequency of about several tens of kHz is widely used. These fluorescent lamps are usually straight or curved, and have electrodes inside both ends. The electrodes are coated with an electron emitting material that easily emits electrons into the discharge space. This electron-emitting substance is reduced in scattering due to sputtering by ions and evaporation due to an increase in temperature. When the electron emitting material is exhausted, electrons are less likely to be emitted from the electrodes, and the discharge cannot be maintained. Therefore, the life of the lamp having such an electrode is determined by the consumption of the electron emitting material applied to the electrode.

In recent years, long life electrodeless fluorescent lamps have been studied. However, since an electrodeless fluorescent lamp is one in which a high-frequency current flows through an excitation coil and a discharge gas in a discharge vessel is discharged and emitted by a generated high-frequency induction electromagnetic field, electromagnetic radiation noise is easily generated and some sort of shielding means is required. . As a conventional shield means, for example, JP-A-61-2143
As described in Japanese Patent Publication No. 48, there is a method of integrally forming a transparent conductive film such as a tin oxide film on the inner surface of a discharge vessel arc tube.

As another shield means, there is an example in which a copper ring as disclosed in Japanese Patent Publication No. 5-46661 is provided on a part of the outer wall of the discharge vessel arc tube to reduce electromagnetic radiation noise.

[0005]

As a countermeasure against electromagnetic radiation noise of the conventional electrodeless fluorescent lamp, there are the following methods and problems.

As a method for returning high-frequency energy to a lighting circuit, which is one of the conventional measures against electromagnetic radiation noise, a copper foil or the like is provided on the outer wall of the discharge vessel arc tube facing a part of the transparent conductive film on the inner surface of the discharge vessel arc tube. In the method of pasting, conducting by capacitive coupling through the discharge vessel arc tube wall, and dropping it to the lighting circuit,
Since the copper foil blocks light, the copper foil cannot be formed up to the horizontal position of the excitation coil.For example, when an electrodeless fluorescent lamp is turned on in a metal appliance, the influence of the magnetic field accompanying the electrodeless discharge is reduced. As a result, there is a phenomenon that current flows in the metal appliance, which leads to damage to the lighting circuit.

Further, as a countermeasure for preventing a current from flowing in the above-mentioned metal appliance, a method of reducing a radiated electromagnetic field by attaching a copper ring or the like to an outer wall of a discharge vessel arc tube as disclosed in Japanese Patent Publication No. 5-46661. Then, there was a problem that appearance was spoiled as a household lamp.

[0008]

In order to solve the above-mentioned problems, in the present invention, as a method for preventing an electromagnetic field from being emitted to the outside, a spiral or one or more ring-shaped conductive material is built in a discharge vessel, The conductive material is placed at a position horizontal to the position of the excitation coil.

[0009] In the above solution, by incorporating a spiral-shaped or one or more ring-shaped conductive material in the discharge vessel to reduce the electric and magnetic field radiation, when the lamp is inserted into a metal appliance, The lighting circuit can be prevented from being damaged by current generation due to a magnetic field. In addition, since the conductive material is incorporated in the discharge vessel and the appearance is not impaired, the spiral shape or one or more ring-shaped conductive materials are attached to the lower part of the discharge vessel so that the phosphor is not damaged. Can also be prevented.

[0010]

FIG. 1 shows an embodiment of an electrodeless fluorescent lamp according to the present invention. A transparent conductive film 2 is formed on the inner surface of the discharge vessel 1.
Is further coated, and a phosphor 3 is applied on the inner surface. The external shape is substantially spherical, and a discharge vessel submerged portion 4 is formed in a cylindrical shape from the periphery toward the inside. A rare gas such as argon and mercury are sealed in the discharge vessel 1.

A conductive spiral ring 9 is built in, and several turns are installed in a spiral shape around the excitation coil 6 and near the inner wall of the discharge vessel. The conductive spiral ring 9 is attached and fixed to the lower part of the cylindrical discharge vessel submerged portion 4. A copper foil 5 is provided on a part of the outer wall of the discharge vessel 1, and the copper foil 5 is covered with an outer case 10. The copper foil 5 is electrically connected to a lighting circuit 7 and has a power supply port 8 for connecting the lighting circuit 7 to a commercial power supply. The lighting circuit 7 generates a high frequency of several MHz from a commercial power supply. The high-frequency output of the lighting circuit 7 is connected to the excitation coil 6.

The operation at the time of lighting is as follows. High frequency power is supplied to the excitation coil 6 from the lighting circuit 7 by being connected to a commercial power supply. High frequency plasma is generated around the coil by a high frequency electromagnetic field generated around the coil. Ultraviolet light generated from the high-frequency plasma is applied to the phosphor 3 to be converted into visible light, and is taken out of the transparent conductive film 2 and the discharge vessel 1. On the other hand, the electromagnetic radiation noise due to the high-frequency current is transmitted from the transparent conductive film 2 to the copper foil 5 through the discharge vessel 1 and returned to the lighting circuit 7. Further, the electromagnetic radiation noise generates a magnetic field by the current flowing through several turns of the conductive spiral-shaped ring 9 built in the discharge vessel, and the magnetic field generated from the excitation coil 6 is directed outward from the conductive spiral-shaped ring 9. Thus, the electromagnetic radiation to the outside of the discharge vessel can be prevented.

FIG. 2 shows another embodiment of the present invention. In this embodiment as well, several conductive rings 11 are arranged in parallel inside the discharge vessel 1 in the same manner as the measures for preventing electromagnetic radiation described with reference to FIG. At this time, the discharge vessel 1 had a substantially cylindrical shape to facilitate insertion of the conductive ring 11.

In the embodiment shown in FIG. 1, the transparent conductive film 2 is formed of a tin oxide film or an ITO film, and mercury and argon are used as an enclosure in the discharge vessel. In the present invention, for example, various amalgams can be used in place of the mercury.
In this case, amalgam having the highest luminous efficiency is selected according to the temperature of the lamp during the operation of the lamp. This makes it possible to cope with various operating conditions of the lamp.
Also, krypton, xenon gas or neon gas can be used instead of argon gas. Alternatively, only a rare gas such as xenon may be used without using mercury at all. In this case, it is possible to realize a lamp that has a stable temperature characteristic and has a fast start-up time at the start without being influenced by the ambient temperature.

[0015]

According to the present invention, by providing a conductive spiral shape or a conductive material inside the discharge vessel and fixing it at the lower part of the columnar recess, the appearance of the lamp is impaired by controlling the electromagnetic radiation. In addition, unnecessary electromagnetic radiation to the outside of the electrodeless discharge lamp can be suppressed.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of an electrodeless fluorescent lamp of the present invention.

FIG. 2 is an explanatory view showing another embodiment of the electrodeless fluorescent lamp of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Discharge container, 2 ... Transparent conductive film, 3 ... Phosphor, 4 ... Submerged portion of cylindrical discharge container, 5 ... Copper foil, 6 ... Excitation coil,
7: lighting circuit, 8: power supply port, 9: conductive spiral shaped ring, 10: outer case, 11: conductive ring.

Continued on the front page (72) Inventor Kenji Miyata 888 Fujibashi, Ome-shi, Tokyo Heating Lighting Division, Hitachi, Ltd.

Claims (4)

[Claims] 1. A discharge vessel having a submerged part in a part thereof, an excitation coil connected to a power supply unit built therein, and a high-frequency electromagnetic field is generated in the discharge vessel by the excitation coil. An electrodeless fluorescent lamp that excites a gas and emits light through a transparent conductive film and a phosphor or the like on the inner surface of the discharge vessel, characterized in that the discharge vessel has a spiral-shaped or one or more ring-shaped conductive material inside. Electrodeless fluorescent lamp. 2. The electrodeless fluorescent lamp according to claim 1, wherein a spiral or ring-shaped conductive material is provided outside the excitation coil connected to the power supply unit. 3. An electrodeless fluorescent lamp according to claim 1, wherein said spiral conductive material has end-to-end conduction. 4. An electrodeless fluorescent lamp according to claim 1, wherein the spiral or ring-shaped conductive material is fixed to a wall of the discharge vessel or a submerged portion of the discharge vessel.