JPH0715094Y2 - Electrodeless discharge lamp - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeless discharge lamp which has no electrode inside the lamp and which excites and discharges discharge gas inside the lamp by a high frequency electromagnetic field from the outside.

[0002]

2. Description of the Related 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, in the lamp disclosed in Japanese Patent Laid-Open No. 57-78766, a bulb 22 is formed so as to cover an air-core coil 21, as shown in FIG. However, the mercury vapor in the bulb 22 is discharged by an electromagnetic field generated by passing a high-frequency current through the air-core coil 21, and the magnetic field generated by the cylindrical coil used here is the strongest inside. In this example, there is no discharge space in that portion, and the valve 22 is formed exclusively by utilizing the magnetic field outside the coil.

Further, the shape of the high-power electrodeless discharge lamp which has recently been developed in various places and emits light by electromagnetic waves is spherical as shown in FIG. 6, and rare gas is contained in the bulb 23 formed of transparent quartz or the like. Bulb 2 with luminescent material enclosed
An induction coil 24 is wound around 3. 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 condition, the initial starting becomes very difficult, and if a high voltage is applied to forcefully start, a large lighting device is required. become.

In view of the above problems, the applicant of the present application previously applied for an electrodeless discharge lamp which has good startability and good compatibility with a high frequency circuit. The outline will be described below with reference to FIGS. 7 and 8.

In the figure, reference numeral 1 is a spherical valve having a narrow tube portion 2, which is airtight and transparent, and contains 100 torr of xenon gas and Na as a metal halide substance.
The total amount of I-TaI-InI is 24 mg, and the weight% ratio is 80: 1.
It is enclosed at 5: 5. Reference numeral 3 denotes an induction coil wound along the outer peripheral wall of the valve 1, which is wound 3 turns in this example, and both ends thereof are connected to the high frequency generating means 4.

Numerals 5 and 6 are a pair of auxiliary electrodes made of a foil-shaped conductive material, which are wound around the thin tube portion 2 with a small interval (so far as insulation breakdown does not occur in the air, in this example, 0.5 mm apart). The auxiliary electrodes 5 and 6 are shown in FIG.
In the example shown in FIG. 8, both ends of the induction coil 3 are connected via connecting wires 7, respectively, and in the example shown in FIG.

In the electrodeless discharge lamp thus constructed, when a high frequency current is passed through the induction coil 3, a voltage is generated between the coil terminals. This generated voltage is also applied between the electrodes 5 and 6 of the thin tube portion 2. However, since the distance between the electrodes is smaller than the distance between the coil terminals, the electrodes 5,
The electric field strength between 6 is larger than the electric field strength between the coils 3.
Therefore, first, dielectric breakdown of Xe gas occurs in the thin tube portion 2. The discharge plasma generated in the thin tube portion 2 extends to the main discharge space of the bulb 1 as the input increases.

When the electron density is sufficiently increased in the main discharge space, a discharge accompanied by strong ring-shaped light emission is generated along the induction coil 3 in the bulb 1 which is the main discharge space. The temperature rise due to this ring-shaped discharge raises the vapor pressure of the metal halide material, and the metal-based light emission is the main discharge. Therefore, it is possible to obtain an electrodeless discharge lamp that can be easily started at the beginning without enclosing mercury and has good compatibility with a high frequency circuit.

[0011]

However, when a so-called metal halide substance such as a metal iodide or a metal bromide is enclosed as described above, the metal halide substance is contained in the thin tube portion 2 which is the coldest portion during lamp operation. gathering,
It has the drawback that the desired vapor pressure cannot be obtained and therefore the desired light output cannot be obtained.

The present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide good starting performance, good matching with a high-frequency circuit, and a desired light output during stable operation. An object is to provide an electrode discharge lamp.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a discharge enclosed in a bulb by applying a high frequency current to an induction coil wound along the outer peripheral wall of the bulb. In an electrodeless discharge lamp that excites and emits gas, a thin tube portion that forms the same airtight space as the bulb is integrally provided with the bulb, and a pair of auxiliary electrodes made of a foil-shaped conductive material is provided in the thin tube portion in the air. It is characterized in that it is arranged with an interval such that dielectric breakdown does not occur, a heating means or a heat retaining means is arranged in the thin tube portion, and a high frequency voltage is applied between the both electrodes only at the time of starting. .
Note that, instead of the auxiliary electrode, a starting auxiliary coil may be wound around the thin tube portion.

[0014]

Embodiment 1 FIG. 1 shows a first embodiment of the present invention, which is different from the prior art shown in FIGS. 7 and 8 in that the inner wall of the thin tube portion 2 has an infrared reflection film 9 as a heating means. Since the other configurations are the same as those of the above-described prior art by applying, the description thereof will be omitted by assigning the same reference numerals to the same configurations. Of course, the infrared reflection film 9 may be applied to the outer wall of the thin tube portion 2.

With such a structure, as described in the above-mentioned "Problems to be solved by the invention", in the prior art, the metal halide substance is accumulated in the thin tube portion 2 which is the coldest portion during the lamp operation. Many gather, the metal vapor pressure in the main discharge space becomes lower than the desired vapor pressure, and the desired light output cannot be obtained, but in the present embodiment, the temperature of the thin tube portion 2 rises due to the infrared reflection film 9. Therefore, the metal vapor pressure in the main discharge space becomes a desired vapor pressure.

[0016]

Second Embodiment FIG. 2 shows a second embodiment of the present invention. The difference from the first embodiment is that a heat insulating material 10 as a heat insulating means is provided on the outer wall of the thin tube portion 2. Even with this structure, the same effect as that of the first embodiment can be obtained.

[0017]

[Third Embodiment] FIG. 3 shows a third embodiment of the present invention. The difference from the first embodiment is that a heater 11 is used as a heating means.
Is provided. With this configuration,
Even if the desired coldest part temperature cannot be obtained only by the heat generation of the lamp itself, the thin tube part 2 is heated by the heater 11, so that the desired coldest part temperature can be obtained, and therefore, the desired light output can be obtained. become.

[0018]

[Fourth Embodiment] FIG. 4 shows a fourth embodiment of the present invention. The difference from the first, second and third embodiments is that a starting auxiliary coil 12 is provided instead of the auxiliary electrodes 5, 6. , And inductive coupling. Of course, the thin tube portion 2 is provided with the above heating means or heat retaining means. Even with this structure, the same effect as that of each of the above-described embodiments can be obtained.

[0019]

As described above, the present invention excites and discharges the discharge gas enclosed in the bulb by energizing the induction coil wound along the outer peripheral wall of the translucent bulb with a high frequency current. In the electrodeless discharge lamp, the thin tube portion that forms the same airtight space as the bulb is provided integrally with the bulb, and the thin tube portion is provided with an inductive or electrostatic coupling portion that supplies high-frequency power only at the time of starting. By providing the heating means or the heat retaining means in the part, it is possible to provide an electrodeless discharge lamp which has good startability, good matching with a high frequency circuit, and can obtain a desired light output during stable operation.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a sectional view showing a third embodiment of the present invention.

FIG. 4 is a perspective view showing a fourth embodiment of the present invention.

FIG. 5 is a partial cross-sectional front view showing a conventional example.

FIG. 6 is a perspective view showing a conventional example.

FIG. 7 is a simplified diagram showing the prior art.

FIG. 8 is a simplified diagram showing the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 valve 2 thin tube part 3 induction coil 4 high frequency generating means 5 auxiliary electrode 6 auxiliary electrode 7 connecting wire 8 high frequency generating means 9 heating means (infrared reflecting film) 10 heat retaining means (heat retaining material) 11 heating means (heater) 12 auxiliary for starting coil

Claims (3)

[Scope of utility model registration request] 1. An electrodeless discharge lamp in which a discharge gas 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 thin tube portion that forms the same airtight space as the valve is provided integrally with the valve, and a pair of auxiliary electrodes made of a foil-shaped conductive material are arranged in the thin tube portion at intervals such that dielectric breakdown does not occur in the air. In addition, the electrodeless discharge lamp is characterized in that a heating means is provided in the thin tube portion and a high frequency voltage is applied between the both electrodes only at the time of starting. 2. An electrodeless discharge lamp in which a discharge gas 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 thin tube portion that forms the same airtight space as the valve is provided integrally with the valve, a starting auxiliary coil is wound around the thin tube portion, and heating means is provided in the thin tube portion, and the starting auxiliary coil is used only when starting. An electrodeless discharge lamp characterized in that a high frequency voltage is applied. 3. The electrodeless discharge lamp according to claim 1, wherein the electrodeless discharge lamp is provided with a heat retaining means instead of the heating means.