JPS62172659A - Electrodeless discharge lamp - Google Patents

Abstract

PURPOSE:To make it easy to get a high output, by forming an airtight container of a highly heatproof material, and covering the container by a light-transmitting material allowing no ultraviolet ray transmission. CONSTITUTION:In an airtight space 22, a discharge is taken place by a high frequency wave electromagnetic field generated by an induction coil 25. Since an airtight space 21 is well permeable for a visible light and ultraviolet rays, the beams of the both wavelength areas are radiated from a luminous bulb 24. When the both beams reach to the outside container 27, the ultraviolet rays are cut off and only the visible light permeates to output to the outside. In this case, since the luminous bulb 24 is formed of a highly heatproof material, the high output light can be radiated outward easily.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to an electrodeless discharge lamp in which a discharge material such as a rare gas or metal vapor sealed in a light-transmitting airtight container is discharged and emitted by a high-frequency electromagnetic field. .

(Background Art) Conventional discharge lamps can be roughly classified into two types of lamp structures from the viewpoint of lighting methods.

One type is an electrode type, typified by general fluorescent lamps that are currently widely used along with incandescent light bulbs, and the other is an electrodeless type.

First, an example of the electrode type is shown in FIG. 4. In the figure, 1 is a glass bulb, and a phosphor coating 2 is formed on the inner surface of the bulb. Further, the airtight space 3 formed by the glass bulb 1 is filled with a predetermined amount of mercury and rare gas. Further, at both ends of the glass bulb 1, electrodes 4a and 4b filled with a thermionic emitting substance are arranged. These electrodes 4a, 4b are connected to tjlit6 via a current limiting impedance 5. In such a lamp, a voltage is applied between the electrodes 4a and 4b to generate an electric discharge in the tube between the electrodes, the ultraviolet light generated thereby excites the phosphor 2, and the visible light generated there is utilized. It is something.

Next, an example of the electrodeless type is shown in FIG. In the figure, 7 is a glass bulb, a fluorescent coating 8 is formed on its inner surface, and an airtight space 9 formed by the glass bulb 7 is
A predetermined amount of mercury vapor and rare gas are sealed. Reference numeral 10 denotes an induction coil wound around the outer periphery of the valve 7, and both ends of the induction coil are connected to a power source 11. In this type, the lamp part does not have an electrode like the above-mentioned electrode type, and when a high frequency current is passed through the induction coil 10, a high frequency electromagnetic field is generated around it, and a discharge occurs within the bulb 7. The ultraviolet light generated by this further excites the phosphor 8 to generate visible light, and this light emission is utilized.

By the way, when comparing the above two types of discharge lamps,
The non-electrode type has the following advantages over the electrode type.

(al instantaneous lighting is possible.

M) It is easy to downsize and increase output.

(C) It has a long life.

In particular, when aiming to increase the output of a lamp, it is very difficult to achieve high output because the current that can be passed through the electrodes is severely limited in the case of an electrode type. The electrode type can input more power and is easier to increase output. However, as a matter of course, the electrodeless type also has a limit to its ability to achieve high output. In other words, the question is whether the bulb can withstand the heat generated by the lamp when lit. From this point of view, the bulb should be made of transparent quartz (SiO2), which has higher heat resistance than ordinary glass (e.g. soda glass), or translucent alumina (A1203).
If formed with
These materials usually have strong transmittance in the ultraviolet region with wavelengths longer than 200 nI11, so they are not suitable for general illumination light sources.

(Object of the Invention) The present invention has been made in view of the above points, and its purpose is to provide an electrodeless discharge lamp that can easily achieve high output and has the advantages of an electrodeless type. be.

(Disclosure of the Invention) The present invention is an electrodeless discharge lamp in which a discharge body enclosed in a light-transmitting airtight container is discharged and emitted by a high-frequency electromagnetic field, and the airtight container is formed of a highly heat-resistant material. , the airtight container is covered with an outer container made of a translucent material that does not transmit ultraviolet rays.

Hereinafter, the present invention will be explained in detail based on examples.

Embodiment 1 FIG. 1 shows a first embodiment of the present invention. In the figure, 21 is an airtight container forming an airtight space 22, and the airtight container 2 is made of transparent quartz (S i 02 ) or It is made of translucent and highly heat-resistant material such as translucent alumina (Affi203), and a discharge body consisting of a predetermined amount of water 11 vapor and rare gas is sealed inside, making it translucent and airtight. container 2
A fluorescent coating 23 is formed on the inner surface of 1. An induction coil 2 is installed outside the light bulb 24 configured in this way.
5 are placed close to each other, and both ends of the induction coil 25 are connected to a power source 26.
It is connected to the. Further, the light-emitting bulb 24 is connected to the outer container 2.
Covered by 7. This outer container 27 has good transparency for visible light and ultraviolet light (for example, wavelength 254
It is made of a material (for example, soda lime glass) that has almost no transparency to ultraviolet light of 185 nm or 185 nm. That is, the outer container 27 functions as a filter that cuts out the ultraviolet light among the visible light and ultraviolet light generated from the light-emitting bulb 24 and selectively transmits only the visible light.

Note that a space 28 between the light-emitting bulb 24 and the outer container 27 communicates with the atmosphere.

Next, the operation of the above embodiment will be explained. As described above, discharge occurs in the airtight space 22 due to the high frequency electromagnetic field generated from the induction coil 25.

Since the airtight container 21 has good transparency for visible light and ultraviolet light, light in both wavelength ranges is emitted from the light-emitting bulb 24. When these lights reach the external container 27, the ultraviolet light is cut off, only the visible light is transmitted, and is output to the outside. Here, the light-emitting bulb 24 is as described above.
Since it is made of a highly heat-resistant material, it is easy to increase the output of light that is output to the outside.

Embodiment 2 FIG. 2 shows a second embodiment of the present invention, in which the configurations of the light bulb 24 and the induction coil 25 are the same as in the previous embodiment, and the different structure is that the light bulb 24 is covered with a light bulb 24. The provided external container 29 forms an airtight space 30 between the light-emitting bulb 24 and the outer container 29, and this airtight space 30 is filled with gas for cooling the light-emitting bulb 24. Note that it is preferable that the gas to be filled has higher thermal conductivity than air, such as helium or neon.

The effects of this embodiment are similar to those of the previous embodiment, but since the periphery of the light-emitting bulb 24 is in contact with the cooling atmosphere, it becomes easier to increase the output.

Embodiment 3 FIG. 3 shows a third embodiment of the present invention, which has the same structure as the second embodiment, with an airtight space 30 between the light bulb 24 and the outer container 29. A cooling gas is sealed, and the difference is that a phosphor coating is not formed on the inner surface of the light-emitting bulb 24, but a phosphor coating 31 is formed on the inner surface of the outer container 29.

As described above, in this embodiment, since there is no fluorescent coating on the inner surface of the light-emitting bulb 24, the radiation from the light-emitting bulb 24 is only the ultraviolet rays generated by the discharge (strictly speaking, the emission in the visible range due to the discharge is also included). ), this ultraviolet light is transmitted to the outer container 2
The phosphor coated on the inner surface of 9 is excited to emit visible light.

Similarly to the first and second embodiments, this embodiment also has the effect that it is easy to increase the output.

Incidentally, in any of the three embodiments described above, blackening may occur on the inner surface of the light-emitting bulb 24 to which the induction coil 25 is placed in close proximity as the lighting time elapses, and especially in the first and second embodiments. As in, the light bulb 24
If there is a phosphor coating on the inner surface of the phosphor, blackening occurs on the surface of the phosphor coating, which causes luminous flux deterioration. However, in the third embodiment, there is no phosphor coating on the inner surface of the light bulb 24 where blackening occurs, but there is a phosphor coating on the inner surface of the outer container 29, so the luminous flux deterioration as described above is significantly reduced. It also has the effect of reducing it.

(Effects of the Invention) As described above, the present invention provides an electrodeless discharge lamp in which a discharge body sealed in a light-transmitting airtight container is discharged and emitted by a high-frequency electromagnetic field, and the airtight container is made of a highly heat-resistant material. In addition, by covering the airtight container with an outer container made of a translucent material that does not transmit ultraviolet rays, it is easy to increase output, prevent ultraviolet rays from being emitted to the outside, and have the advantages of an electrodeless type. It was possible to provide an electrodeless discharge lamp with the following features.

[Brief explanation of drawings]

1 to 3 are simplified partial cross-sectional views showing embodiments of the present invention, and FIGS. 4 and 5 are simplified partial cross-sectional views showing conventional examples, respectively. 21... Translucent airtight container, 23.31... Fluorescent coating, 27.29... Outer container.

Claims (4)

[Claims] (1) An electrodeless discharge lamp in which a discharge body enclosed in a light-transmitting airtight container is discharged and emitted by a high-frequency electromagnetic field, and the airtight container is formed of a highly heat-resistant material, and the airtight container is exposed to ultraviolet light. An electrodeless discharge lamp characterized in that the lamp is covered with an outer container made of a translucent material that does not transmit light. (2) The electrodeless discharge lamp according to claim 1, wherein a space surrounded by the airtight container and the outer container is an airtight space, and a cooling gas is sealed in the airtight space. (3) The electrodeless discharge lamp according to claim 1 or 2, wherein a phosphor coating is formed on the inner surface of the airtight container. (4) The electrodeless discharge lamp according to claim 1 or 2, wherein a phosphor coating is formed on the inner surface of the outer container.