JP2001006624A - Electrodeless fluorescent lamp device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a long lifetime fluorescent lamp by forming an electrodeless fluorescent lamp in a double cylindrical shape composed of an outer tube and an inner tube and by drawing an excitation induction coil winding a ferrite inside the inner tube out of both ends of the electrodeless fluorescent lamp to electrically connect with caps disposed. SOLUTION: This electrodeless fluorescent lamp 1 has bases 7 and 7' and is electrically connected to a coil 5 wound on a ferrite 4. An excitation induction coil 6 composed of the ferrite 4 and the coil 5 is disposed on the center of concentric circles constituted of an outer tube 2 and an inner tube 3, each of them composed of glass, and extends over approximately the entire length of the electrodeless fluorescent lamp 1. The outer tube 2 and the inner tube 3 are concentrically disposed and form an airtight discharge space. Both inner ends of the inner tube 3 are opened to the outside air. A protective film of an alumina is coated on both sides facing to the discharge space sandwiched by a double tube constituted of the glass outer tube 2 and the glass inner tube 3. A phosphor is coated on the protective film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrodeless fluorescent lamp for general lighting.

[0002]

2. Description of the Related Art A conventional fluorescent lamp as a light source for illumination is usually a straight tube or a curved tube, and has electrodes at both ends. A voltage having a commercial frequency or a frequency of about several tens of kHz is applied between the electrodes to generate a discharge, and ultraviolet light generated by the discharge is converted into visible light by a phosphor applied on the inner surface of the glass container and is extracted to the outside. Electrodes are applied to the electrodes. This electron-emitting substance is scattered and reduced by sputtering by ions and evaporation by temperature rise. When the electron emitting material is exhausted, electrons are hardly emitted from the electrode, 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 substance applied to the electrode.

In recent years, long life electrodeless fluorescent lamps have been studied. For example, there are JP-A-63-310550 and JP-A-11-3686. An electrodeless fluorescent lamp is a high-frequency current of several hundred kHz to several tens of MHz flowing through an excitation induction coil arranged close to a discharge vessel filled with a discharge gas, or a pair of opposed electrodes arranged close to the discharge vessel. A high-frequency voltage is applied to the discharge vessel to discharge and emit a discharge gas in a discharge vessel by a generated high-frequency electromagnetic field. Since the electrodeless fluorescent lamp has no electrodes in the discharge vessel, it is characterized by having a long life regardless of the consumption of the electron-emitting substance.

At the same time, since this electrodeless fluorescent lamp has no electrodes in the discharge vessel, there is no power loss associated with the electrodes, and an improvement in efficiency is expected. However, electrodeless fluorescent lamps are subject to high tube wall loads (input power per lamp surface area).
Lighting with causes the efficiency to decrease and the phosphor to deteriorate. In particular, when an excitation induction coil longer than the diameter is provided in the inner tube, the discharge tends to be non-uniform, and when the discharge is locally concentrated, the portion becomes a high tube wall load, and the brightness becomes uneven. As well as the efficiency tends to decrease. This is because a high-frequency magnetic field generated around the coil generates a ring-shaped induction electric field concentric with the coil in the discharge vessel to excite the discharge gas and maintain the discharge. Because it is done.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to increase the lamp input power per unit length of an electrodeless fluorescent lamp and to suppress the increase in tube wall load, to achieve uniform and high efficiency.
An object of the present invention is to provide a long-life electrodeless fluorescent lamp and an electrodeless fluorescent lamp device.

[0006]

In order to solve the above-mentioned problems, in a fluorescent lamp according to the present invention, a double cylindrical outer cylindrical portion is used as a discharge space, and an inner cylindrical portion is excited by winding a coil on a ferrite. An induction coil was provided. By making both surfaces of the double cylinder facing the discharge path phosphor layers,
The surface area of the phosphor layer that converts ultraviolet light generated in the discharge path into visible light can be increased, and the load on the tube wall can be reduced even if the input power is large. At the same time, the distance between the center of the discharge path and the phosphor layer can be reduced,
Since the ultraviolet rays generated in the discharge path are effectively absorbed by the phosphor layer, the lamp input power per unit length can be increased without reducing the efficiency of the lamp.

One of the factors that disturb the discharge is a high-frequency electric field generated in the axial direction of the coil. At this time, pulling out the excitation induction coil from both ends of the inner tube that forms the discharge space is a factor that disturbs uniform discharge because the high-frequency electric field generated in the axial direction of the coil is evenly applied to the discharge space. One of them.

When the excitation induction coil is longer than its diameter, the induced electric field at the end of the discharge space is weakened, so that the end tends to be dark. When the ferrite around the excitation induction coil is magnetically coupled by multiple lamps, the leakage of the magnetic flux created by the excitation induction coil is suppressed, and the induction electric field at the end of the discharge space does not weaken, and the discharge is bright over the entire surface of the lamp. Can be done. Furthermore, the brightness of the electrodeless fluorescent lamp can be arbitrarily adjusted by dividing the excitation induction coil into a plurality of parts and individually driving each excitation induction coil. At this time, since the excitation induction coils are magnetically coupled by ferrite, it is necessary to align the phases of the power supplies applied to the respective excitation induction coils. If the phases are not aligned, the discharge is likely to fluctuate irregularly.

Another factor that disturbs the discharge is the effect of the discharge on the exciting induction coil. That is, when the discharge is locally concentrated, the magnetic field generated by the discharge cancels the magnetic field generated by the induction coil for excitation, so that the electric field in the discharge path is weakened and the discharge is more easily concentrated. However, such concentration of discharge can be prevented by dividing the excitation induction coil. At this time, each of the divided excitation induction coils generates a magnetic flux through the ferrite which is magnetically coupled.However, the magnetic flux is generated by making the directions of the magnetic fluxes continuous. Can be enhanced.

[0010] However, if the winding directions of the divided coils are the same, the electric field strength is abnormally increased in adjacent portions, and
The impact of the mercury ions accelerated by the high electric field deteriorates the phosphor and lowers the luminous flux maintenance rate. On the other hand, if the winding directions of the divided coils are opposite to each other, it is possible to eliminate the electric field strength in the adjacent portions and not to impair the luminous flux maintenance ratio. At the same time, the intensity of the electric field generated in the electrodeless fluorescent lamp can be reduced as a whole, and unnecessary electromagnetic radiation can be reduced.

By the way, in order to excite the discharge gas in the discharge vessel by using the excitation induction coil and to generate and maintain the discharge, if the power density of the discharge is increased, the power supplied to the excitation induction coil is increased. Is efficiently transmitted to the discharge space, but the efficiency is reduced for the above reason.

Therefore, the outer tube has a tube diameter of 30 to 50 mm, the difference between the outer tube and the inner tube is 10 to 20 mm, and the discharge space between the outer tube and the inner tube has a pressure of 0.3 to 2 Torr. Noble gas and mercury are sealed, and the difference between the outer diameter of the ferrite in the inner tube and the inner diameter of the inner tube is set to 1 mm or less, so that the tube wall load is reduced to 0 mm.
Supply power can be efficiently transmitted to the discharge space in a high range from a low power density of 02 to 0.08 watt / square centimeter and can be uniformly discharged. If the diameter of the outer tube is smaller than 30 mm, the cross-sectional area of the ferrite is limited, and a sufficient magnetic flux cannot be secured, and the input power is limited to a small value. On the other hand, if the diameter of the outer tube is larger than 50 mm, the discharge tends to be locally concentrated. When the difference between the outer tube and the inner tube is smaller than 10 mm, the discharge tends to be locally concentrated, and when the difference is larger than 20 mm, the distance between the center of the discharge and the tube wall becomes large, and the efficiency is reduced. I do. If the pressure of the sealed rare gas is lower than 0.3 Torr, the phosphor is greatly deteriorated. If the pressure is higher than 2 Torr, the discharge becomes unstable and the efficiency is reduced.

When the difference between the outer diameter of the ferrite and the inner diameter of the inner tube is within 2 mm and the tube wall load is 0.02 watt / cm 2 or more, the electric power supplied to the excitation induction coil efficiently discharges the discharge space. Was communicated to. However, when the tube wall load is less than 0.02 watts / square centimeter, although a discharge in the tube axis direction occurs, a ring-shaped discharge hardly occurs, and the power supplied to the excitation induction coil is reflected without being transmitted to the discharge. And the efficiency decreased.
When the tube wall load exceeded 0.08 watts / square centimeter, the power density became excessive, and conversely, the efficiency decreased.

The electrodeless fluorescent lamp of the present invention has bases at both ends thereof, and can be stably held by holding the bases at both ends. However, on the other hand, the base serves as a light-shielding object for the light emitted from the lamp, so that the efficiency is reduced. Therefore, if the lamp length is increased and the outer tube length is set to three times or more the outer tube diameter, this effect can be ignored and the above-mentioned adverse effects can be eliminated.

The cross section of the electrodeless fluorescent lamp of the present invention is not limited to a circle. The outer tube is flattened,
By using the flat surface as the lower surface, the lower light flux ratio can be increased, and the light emitted from the lamp can be used effectively.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a front view showing a straight tube type electrodeless fluorescent lamp according to an embodiment of the present invention, in which a part of a tube wall is cut away. FIG. 2 shows a cross section taken along line AA ′ of FIG. The electrodeless fluorescent lamp 1 has bases 7 and 7 ′ at both ends, and is electrically connected to a coil 5 wound on a ferrite 4. The excitation induction coil 6 composed of the ferrite 4 and the coil 5 is made of glass and has a length of 6 mm.
It is arranged at the center of a concentric circle composed of a 00 mm outer tube 2 and an inner tube 3 and extends over substantially the entire length of the electrodeless fluorescent lamp 1. As shown in FIG. 2, the outer tube 2 and the inner tube 3 are arranged concentrically to form an airtight discharge space 9, and both inner ends of the inner tube 3 are open to the outside air.

It faces the discharge space 9 sandwiched between a double tube consisting of an outer tube 2 made of glass having a tube outer diameter of 40 mm and a thickness of 1 mm and an inner tube 3 made of glass having a tube outer diameter of 22 mm and a thickness of 1 mm. Protective films 12, 12 'made of alumina are applied to both surfaces, respectively, and phosphors 11, 11' are applied thereon.

The discharge space 9 is filled with a rare gas of about 1 Torr and mercury. The inner diameter of the inner tube 3 is 1
An excitation induction coil 6 composed of an 8 mm ferrite 4 and a coil 5 wound thereon is inserted. The surface of the excitation induction coil 6 is coated with white paint as a visible light reflector. In this embodiment, a case is shown in which the light-transmitting conductive film provided between the inner surface of the outer tube 2 and the protective film 8 is omitted, but there is a difference in performance except that electromagnetic noise increases. Absent.

When a high frequency of 13.56 Mhz was applied to the electrodeless fluorescent lamp 1 having the above configuration, a uniform and stable ring-shaped discharge (input power of 40 W) was applied to the discharge space 9.
And bright and highly efficient lighting without flicker was obtained.

FIG. 3 shows another embodiment of the present invention, which is an electrodeless fluorescent lamp device 21 in which two electrodeless fluorescent lamps are installed in parallel. In the figure, the power supply part and the housing part are omitted. Each of the electrodeless fluorescent lamps is the same as FIG. 1 except that the coils 5 and 5 'are wound in opposite directions. The respective ferrites 4, 4 'are magnetically coupled via ferrules 7, 7b, 7', 7b 'with ferrites 8, 8' coated with an electrical insulator. The two electrodeless fluorescent lamps are lit in parallel by a single high-frequency power supply. At this time, the ferrites 4, 4 'and 8, 8' constitute a closed magnetic circuit, and minimize the leakage of magnetic flux to the outside.

FIG. 4 is a view showing another embodiment of the present invention, in which three high-frequency power supplies 10a, 10b and 10c are respectively provided.
3 coils 5 wound on ferrite 4
It is a figure showing composition of excitation induction coil 6 of the electrodeless fluorescent lamp device which has a, 5b, and 5c. The frequencies and phases of the respective high-frequency power supplies match, and their outputs are arbitrarily adjusted. In the configuration shown in this figure, it is possible to arbitrarily adjust the light at the left and right tube ends and at the center.

FIGS. 3 and 4 respectively show the case where two electrodeless fluorescent lamps are magnetically coupled and the case where the coil is divided into three. However, these couplings or divisions are two. , And the number is not limited to three, but may be plural.

FIG. 5 is a schematic view showing a main part of another embodiment of the excitation induction coil 6 used in the electrodeless fluorescent lamp of the present invention. Coil 5 wound on cylindrical, hollow ferrite 4
d and 5e are respectively symmetrical and wound in opposite directions. One end of each coil is returned in the same direction as the other end through a through hole provided in the ferrite, and is connected in parallel to the high frequency power supply 10 via a base not shown in the figure. The ferrite 4 is shown as a single hollow cylinder in the figure. However, a plurality of ferrites each formed of a short hollow cylinder may be magnetically coupled, or a half-split ferrite may be superposed. May be. In short, it is only necessary that the magnetic coupling be made. In this embodiment, since the coil 5 is symmetrical and the applied high-frequency electric field is also symmetrical, uniform and stable discharge occurs.

FIG. 6 is a sectional view showing another embodiment of the present invention. It is roughly the same as the embodiment shown in FIGS.
The difference is that the outer tube 2 is flat. The outer tube may be flat over its entire length, but may be partially flat. As described above, by making the outer tube flat and the flat surface as the lower surface, the lower luminous flux ratio could be increased by about 10%.

[0025]

As described above, according to the present invention, it is possible to realize an electrodeless fluorescent lamp and an electrodeless fluorescent lamp device which are bright, uniform, high in efficiency and long in life.

[Brief description of the drawings]

FIG. 1 is a front view of an electrodeless fluorescent lamp according to an embodiment of the present invention, in which main parts are cut away.

FIG. 2 is a cross-sectional view taken along line AA ′ of the electrodeless fluorescent lamp of FIG.

FIG. 3 is a front view of an electrodeless fluorescent lamp device according to another embodiment of the present invention, in which main parts are cut away.

FIG. 4 is a front view of an excitation induction coil used in an electrodeless fluorescent lamp according to another embodiment of the present invention.

FIG. 5 is a front view of an excitation induction coil used in an electrodeless fluorescent lamp according to another embodiment of the present invention.

FIG. 6 is a cross-sectional view of an electrodeless fluorescent lamp according to another embodiment of the present invention.

[Explanation of symbols]

1: electrodeless fluorescent lamp, 2, 2 ': outer tube, 3, 3': inner tube, 4, 4 ': ferrite, 5, 5', 5a, 5b, 5
c, 5d, 5e: coil, 6: induction coil for excitation, 7,
7 ', 7b, 7b' ... base, 8, 8 '... ferrite, 9
... discharge space, 10, 10a, 10b, 10c ... power supply.

Claims (7)

[Claims] 1. An electrodeless fluorescent lamp having a double cylindrical shape comprising an outer tube and an inner tube, an airtight discharge space between the outer tube and the inner tube, and both ends of the inner tube being open air. An excitation induction coil wound on ferrite is provided in the inner tube, the coil is drawn out from both ends of the electrodeless fluorescent lamp, and electrically connected to the bases provided at both ends of the electrodeless fluorescent lamp. A fluorescent lamp device, wherein the fluorescent lamp device is connected. 2. The electrodeless fluorescent lamp device according to claim 1, wherein the electrodeless fluorescent lamps are arranged in parallel, and winding directions of excitation induction coils of the adjacent electrodeless fluorescent lamps are set in opposite directions. An electrodeless fluorescent lamp device wherein the ferrites are magnetically coupled to each other and driven by the same power supply. 3. The electrodeless fluorescent lamp device according to claim 1, wherein the excitation induction coil of the electrodeless fluorescent lamp is divided into a plurality of parts, and each excitation induction coil is individually separated by a power source having the same phase. And an electrodeless fluorescent lamp device. 4. The electrodeless fluorescent lamp device according to claim 1, wherein the excitation induction coil of the electrodeless fluorescent lamp is divided into a plurality of parts, and the winding directions of the adjacent excitation induction coils are opposite to each other. Wherein each of the excitation induction coils is driven in parallel. 5. The electrodeless fluorescent lamp device according to claim 1, wherein said outer tube has a diameter of 30 to 50 mm.
And the difference between the outer tube and the inner tube is 10 to 20 mm,
The length of the outer tube is at least three times the diameter of the outer tube, and a rare gas and mercury at a pressure of 0.3 to 2 Torr are sealed in a discharge space between the outer tube and the inner tube. Wherein the difference between the outer diameter of the inner tube and the inner diameter of the inner tube is within 2 mm. 6. The electrodeless fluorescent lamp device according to claim 1, wherein said electrodeless fluorescent lamp is lit at a tube wall load of 0.02 to 0.08 watt / cm 2. Electrode fluorescent lamp device. 7. The electrodeless fluorescent lamp device according to claim 1, wherein an outer tube of said electrodeless fluorescent lamp is flat.