JP3376818B2 - Electrodeless fluorescent lamp - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeless fluorescent lamp, and more particularly to a long-life electrodeless fluorescent lamp that prevents external emission of electromagnetic waves.

[0002]

2. Description of the Related Art As an illumination light source, a fluorescent lamp which is turned on at a commercial frequency or a frequency of about several tens of kHz is widely used. These fluorescent lamps are usually tubular or bent tubular, and have electrodes at both ends. Apply a voltage between these electrodes to obtain a commercial frequency or several tens of kHz
A discharge having a certain frequency is generated, and ultraviolet rays generated by the discharge are converted into visible light by a phosphor coated on the inner surface of the glass container and taken out to the outside. The electrodes are coated with an electron emitting substance that easily emits electrons into the discharge space. This electron emitting substance is evaporated and scattered by the sputtering caused by the ions and the temperature rises to be reduced. If the electron emission material is exhausted, it becomes difficult for electrons to be emitted from the electrodes, and discharge cannot be maintained. Therefore, the life of a lamp having such an electrode is determined by the consumption of the electron emitting material applied to the electrode.

Recently, a long-life electrodeless fluorescent lamp has been studied. For example, it is described in JP-A-63-310550. In an electrodeless fluorescent lamp, a high-frequency current is passed through an excitation coil placed in the vicinity of a discharge vessel filled with a discharge gas, or a high-frequency voltage is applied to a pair of counter electrodes placed in the vicinity of the discharge vessel to generate a high-frequency wave. An induction electromagnetic field is generated to discharge and emit the discharge gas in the discharge vessel. The frequency of this high frequency is about several MHz to several tens of MHz. Since the electrodeless fluorescent lamp has no electrode inside the discharge vessel, it has a long life regardless of the consumption of the electron emitting material. However, since the electrodeless fluorescent lamp is lit at a high frequency, electromagnetic radiation noise is easily generated and some kind of shield means is required. In the conventional electrodeless fluorescent lamp, as a shield means, a transparent conductive film such as a nesa film is integrally formed on the inner surface of the discharge vessel, or the bulb is covered with a wire mesh for shielding.

[0004]

The above-mentioned conventional techniques have the following problems as countermeasures against electromagnetic radiation noise. The method of covering the valve with a wire mesh has a problem in that the size is increased and the use is limited. Further, in the method of integrally forming the transparent conductive film on the inner surface of the discharge container and embedding the lead wire for returning the high frequency energy which becomes the electromagnetic radiation noise to the lighting circuit in the discharge container, a complicated conduction method is required. There is a problem with the point. Also, in the method of attaching a copper foil or the like to the outer surface of the discharge vessel that faces a part of the transparent conductive film on the inner surface of the discharge vessel and conducting with capacitive coupling through the wall of the discharge vessel, the copper foil blocks light, so that a large area of copper foil is used. However, there is a problem in that the shield effect is weakened because it cannot be used.

An object of the present invention is to provide an electrodeless fluorescent lamp that prevents electromagnetic radiation noise from being emitted from the discharge container to the outside and that does not pose a risk of electric shock.

[0006]

In order to achieve the above object, the present invention coats the outer wall of a discharge vessel with a transparent conductive metal oxide in order to prevent electromagnetic waves from being emitted to the outside.
It has a portion for directly connecting the transparent conductive metal oxide and the lighting circuit, and is characterized in that the outside of the transparent conductive metal oxide is coated with the transparent insulating metal oxide. Further, by coating the inner wall of the discharge vessel with a transparent conductive metal oxide, the shielding effect can be further enhanced.

Since the outer wall of the discharge vessel is coated with the transparent conductive metal oxide and is directly connected to the lighting circuit,
It is possible to realize an electrodeless fluorescent lamp which can prevent emission of electromagnetic noise, have no adverse effect on external peripheral devices, and have no risk of electric shock due to the transparent insulating metal oxide.

[0008]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing a cross section of a part of the electrodeless fluorescent lamp of the present invention. A phosphor 4 is applied to the inner surface of the discharge container 1. The appearance is almost spherical,
It is a cylindrical depression from the bottom to the inside. The discharge vessel 1 is filled with a rare gas such as argon and mercury. The outer wall of the discharge vessel 1 is coated with a transparent conductive metal oxide 2. A transparent insulating metal oxide 3 is coated on the outside of the transparent conductive metal oxide 2. A metal plate 5 that is in direct contact with the transparent conductive metal oxide 2 is provided below the discharge vessel 1 and the transparent conductive metal oxide 2. Metal plate 5 is lighting circuit 6
The electromagnetic radiation noise can be efficiently dropped to the power supply. There is a power supply port 8 for connecting the lighting circuit 6 to a commercial power source. The lighting circuit 6 is several M from the commercial power source.
It is generating a high frequency of Hz. The high frequency output of the lighting circuit 6 is connected to the excitation coil 7.

The operation during lighting is as follows. High frequency power is supplied to the excitation coil 7 from the lighting circuit 6 connected to the commercial power source, and a high frequency electromagnetic field is generated around the coil.
A ring-shaped high frequency plasma concentric with the coil is generated around the coil by the high frequency electromagnetic field. Ultraviolet rays generated from the high frequency plasma are applied to the phosphor 4 and converted into visible light. The converted visible light passes through the discharge container 1, the transparent conductive metal oxide 2 and the transparent insulating metal oxide 3 and is extracted to the outside. On the other hand, electromagnetic radiation noise due to the high frequency current is directly transmitted from the transparent conductive metal oxide 2 to the metal plate 5 and returned to the lighting circuit 6. Therefore, the emission of electromagnetic noise can be prevented, the external peripheral devices are not adversely affected, and the risk of electric shock can be eliminated by the transparent insulating metal oxide 3.

The transparent conductive metal oxide 2 is made of a tin oxide film or an ITO film. The transparent insulating metal oxide 3 is made of a strontium oxide film or a zirconium oxide film having high light transmittance. The transparent conductive metal oxide 2 is
It may be an oxide of any element of Zn, Cd, Sb, Ga, In, or Pb, or may contain a plurality of oxides of these elements and oxides of Sn. The transparent insulating metal oxide 3 may be an oxide of any element of Ca, Y, Ti, Si, or Al. Among the oxides of these elements, the oxide of Sr, and the oxide of Zr, It may contain more than one.

In the above embodiment, mercury and argon gas were used as the substances to be enclosed in the discharge vessel 1. However, the present invention is not limited to these. For example, various amalgams can be used. By selecting the amalgam with the highest luminous efficiency according to the temperature of the lamp when it is operating, it becomes possible to meet various operating conditions of the lamp. Instead of argon gas, krypton, xenon gas or neon gas can be used. Alternatively, no mercury may be used and only a rare gas such as xenon may be used.
In this case, the temperature characteristics are stable regardless of the ambient temperature,
It is possible to realize a lamp that rises quickly at the time of starting.

FIG. 2 is a side view showing a cross section of a part of an electrodeless fluorescent lamp according to another embodiment. In this example, in order to make the electrodeless fluorescent lamp of the first example more efficient and suppress electromagnetic radiation noise, the inside of the discharge vessel 1 was coated with a transparent conductive metal oxide 9. Similar to FIG. 1, the structure includes a light emitting tube 1, a transparent conductive metal oxide 2, a transparent insulating metal oxide 3, a phosphor 4, a metal plate 5, and a lighting circuit 6, and has a structure with high light transmittance. Further, by covering the entire surface of the arc tube 1 with the transparent conductive metal oxide 2 and the transparent conductive metal oxide 9 that are capacitively coupled, it becomes possible to further prevent electromagnetic radiation noise from leaking to the outside.

The outer transparent conductive metal oxide 2 and the transparent conductive metal oxide 9 do not have to cover the entire surface of the discharge vessel 1, and the transparent conductive metal oxide 2 or the transparent conductive metal oxide 9 is not necessary. Either one of them may cover a part of the discharge vessel 1, for example, only the lower half. In this case, the capacity between the transparent conductive metal oxide 9 on the inner side and the transparent conductive metal oxide 2 on the outer side is the capacity required for reducing electromagnetic radiation noise. With this structure, it is possible to eliminate the light blocking by the copper foil which has been conventionally used for capacitive coupling, and to provide a lamp with good light transmittance. When the transparent conductive metal oxide 2 covers almost half of the lower side of the discharge vessel 1, compared with the prior art electrodeless fluorescent lamp in which only the entire inner surface of the discharge vessel is covered with the transparent conductive metal oxide, The electromagnetic radiation noise can be reduced by half.

The transparent conductive metal oxides 2 and 9 are made of tin oxide film or ITO film. The transparent insulating metal oxide 3 is made of a strontium oxide film or a zirconium oxide film having high light transmittance. The transparent conductive metal oxides 2 and 9 may be oxides of any element of Zn, Cd, Sb, Ga, In, or Pb, and include a plurality of oxides of these elements and oxides of Sn. It can be The transparent insulating metal oxide 3 is made of Ca, Y, T
It may be an oxide of any element of i, Si, or Al, or may include a plurality of oxides of these elements, oxides of Sr, and oxides of Zr.

[0015]

According to the present invention, by directly connecting the transparent conductive metal oxide to the lighting circuit, it is possible to efficiently reduce electromagnetic radiation noise and prevent external peripheral devices from being adversely affected. Further, since the light emitting portion of the discharge vessel is covered with the transparent insulating metal oxide, there is no risk of electric shock when the lamp comes into contact with the human body.

[Brief description of drawings]

FIG. 1 is a side view showing a cross section of a part of an electrodeless fluorescent lamp of the present invention.

FIG. 2 is a side view showing a cross section of a part of an electrodeless fluorescent lamp according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Discharge container, 2 ... Transparent conductive metal oxide, 3 ... Transparent insulating metal oxide, 4 ... Phosphor, 5 ... Metal plate, 6 ... Lighting circuit, 7 ... Excitation coil, 8 ... Power supply port, 9 ... Transparent conductive metal oxide.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Yasuda 888 Fujihashi, Ome-shi, Tokyo Inside the Heater Lighting Division, Nitate Manufacturing Co., Ltd. (56) Reference JP-A-7-282784 (JP, A) JP-A 7-211298 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01J 65/04 H01J 61/35

Claims (3)

(57) [Claims] 1. An excitation coil (7) for generating a high frequency electromagnetic field
A discharge vessel (1) having a recess containing the excitation coil (7), a phosphor (4) provided on the entire inner surface of the discharge vessel (1), and high-frequency power to the excitation coil (7) And a lighting circuit (6) for supplying electric power, wherein the entire outer wall of the discharge vessel (1) is a first
Coated with a transparent conductive metal oxide of
The transparent conductive metal oxide of has a portion that is directly connected to the lighting circuit (6), and the outside of the first transparent conductive metal oxide covers the entire outer wall of the discharge vessel (1). The discharge vessel coated with a transparent insulating metal oxide (1)
An electrodeless fluorescent lamp characterized by being coated with a second transparent conductive metal oxide so as to cover the entire inner wall of the. 2. The transparent conductive layer comprises Zn, Cd, Sb, G
The electrodeless fluorescent lamp according to claim 1, further comprising at least one oxide of elements a, In, and Pb. 3. The transparent insulating layer is made of Ca, Sr, Y, Z.
The electrodeless fluorescent lamp according to claim 1, comprising at least one oxide of elements of r, Ti, Si, and Al.