JPH0697606B2 - Electrodeless discharge lamp - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrodeless discharge lamp that has no electrodes inside the lamp and that excites and emits discharge gas inside the lamp by a high frequency electromagnetic field from the outside.

[Prior Art] Conventionally, electrodeless discharge lamps have been researched and developed in various places because they have characteristics of small size, high output, and long life. There are various uses, but it is considered to be used as a high-power point light source, for example.

Among such electrodeless discharge lamps, for example, Japanese Patent Laid-Open No.
In the lamp disclosed in Japanese Patent Publication No. -78766, as shown in FIG. 4, a bulb 7 that covers the air-core coil 6 is formed,
The mercury vapor in the bulb 7 is discharged by an electromagnetic field generated by passing a high-frequency current through the air-core coil 6, and the magnetic field generated by the cylindrical coil used here is the strongest inside. In the example, there is no discharge space in that portion, and the bulb 7 is formed exclusively by utilizing the magnetic field outside the coil.

Further, the shape of the high-power electrodeless discharge lamp that has recently been developed in various places to emit light by electromagnetic waves is spherical as shown in FIG. 5, and rare gas and luminescent substance are contained in the bulb 8 made of transparent quartz or the like. Is enclosed and an induction coil 9 is wound around the valve 8. When mercury is selected as the luminescent material, initial startup is relatively easy but restarting is difficult, and the mercury vapor pressure changes exponentially with increasing temperature. The alignment condition of is so bad that the lamp cannot be operated stably. If mercury is not added to improve the matching state, initial starting becomes very difficult, and if a high voltage is applied to forcefully start, a large lighting device is required.

[Problems to be Solved by the Invention] The present invention has been made in view of the above problems, and an object thereof is to provide an electrodeless discharge lamp having good startability and good compatibility with a high frequency circuit. is there.

[Means for Solving the Problems] In order to solve the above problems, the present invention encloses mercury in the bulb by applying a high-frequency current to an induction coil wound along the outer peripheral wall of the translucent bulb. In an electrodeless discharge lamp that excites and emits steam, a start auxiliary winding having both ends opened having a number of turns larger than that of the induction coil is arranged so as to be electromagnetically coupled with the induction coil, Both ends thereof are in contact with the outer wall of the valve.

[Embodiment 1] FIG. 1 and FIG. 2 show a first embodiment of the present invention, in which 1 is a spherical bulb, which is airtight and transparent and has a discharge gas inside. As xenon (Xe) gas 100Tor
r is enclosed. Reference numeral 2 denotes an induction coil wound along the outer peripheral wall of the valve 1, which is wound 3 turns in this embodiment, and both ends thereof are connected to a high frequency power source (not shown) for supplying a high frequency current. Reference numeral 3 denotes a starting auxiliary winding wound between the valve 1 and the induction coil 2 substantially in parallel with the induction coil 2, and has a number of turns (10 turns in this embodiment) larger than the number of turns of the induction coil 2. However, both ends thereof are in contact with the outer wall of the valve 1.

In the electrodeless discharge lamp configured as described above, when a high frequency current of, for example, ten and several MHz is applied to the induction coil 2, an alternating magnetic field is generated around the current flowing through the induction coil 2. A voltage corresponding to the voltage across the induction coil × (the number of turns of the auxiliary coil for winding / the number of turns of the induction coil) is applied to both ends of the starting auxiliary winding 3 arranged so as to interlink with the generated alternating magnetic field. Occur. The electric field in the valve due to this voltage causes dielectric breakdown of the Xe gas in the valve 1. As a result, the electron density in the bulb 1 increases, and finally, a strong ring-shaped discharge is generated around the alternating magnetic field along the induced magnetic field, and the discharge is stabilized. The induction magnetic field is formed in the valve 1 along the induction coil 2.

Instead of Xe gas, another type of gas or 2
Of course, a mixed gas of more than one kind may be used. Further, it is of course possible to enclose a metal in addition to the gas.

Example 2 This example is characterized in that a metal halide such as NaI-TaI-InI is enclosed in addition to the enclosed gas in Example 1 above, and other configurations are the same as in Example 1. is there.

With this configuration, the initial start-up and the initial ring-shaped discharge are performed with Xe gas, and thereafter, the vapor pressure of the metal vapor increases, so that the metal vapor emits light. In other words, the white emission of Xe gas is used at the initial stage of lighting, and then the discharge emission of metal vapor is used. Therefore, it is possible to provide a high-intensity discharge lamp with a very good rise.

[Embodiment 3] FIG. 2 shows a third embodiment of the present invention.
2 is different from that of Embodiment 1 in that a magnetic body 4 such as a ferrite core is used for coupling between the induction coil 2 and the starting auxiliary winding 3, and other configurations are the same as those in the first embodiment.

With this configuration, the number of turns of the starting auxiliary winding 3 can be increased regardless of the size of the valve 1.
Therefore, it is effective when the valve 1 is small and the number of turns of the starting auxiliary winding 3 is limited.

[Advantages of the Invention] As described above, in the electrodeless discharge lamp according to the present invention, the start auxiliary winding having the both ends opened having the number of turns larger than that of the induction coil is electromagnetically coupled to the induction coil. By arranging and contacting both ends with the outer wall of the bulb, it is possible to provide a high-luminance electrodeless discharge lamp having good startability and good matching with a high frequency circuit.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a simplified sectional view showing the same as above, FIG. 3 is a schematic configuration view showing a different embodiment of the present invention, and FIG. FIG. 5 is a simplified view showing a different conventional example, and FIG. 1 ... Valve 2 ... Induction coil 3 ... Winding for assisting starting

Claims (1)

[Claims] 1. An electrodeless discharge lamp in which mercury vapor enclosed in the bulb is excited to emit light by passing a high-frequency current through an induction coil wound along the outer peripheral wall of the transparent bulb. A starting auxiliary winding having both ends opened and having a number of turns larger than that of the induction coil is disposed so as to be electromagnetically coupled to the induction coil, and both ends thereof are in contact with the outer wall of the valve. And electrodeless discharge lamp.