JP3424446B2 - Electrodeless lamp - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention does not have an electrode inside a bulb made of a translucent material in which a discharge gas is sealed, and a high-frequency electromagnetic field is applied to the discharge gas from outside the bulb to discharge gas. The present invention relates to an electrodeless discharge lamp that excites and emits light.

[0002]

2. Description of the Related Art Conventionally, there is known an electrodeless discharge lamp in which a high-frequency electromagnetic field is applied to a discharge gas enclosed in a bulb to excite the discharge gas to emit light. Since this type of electrodeless discharge lamp has features such as small size, high efficiency, and long life, research and development have been conducted in various places.

As an electrodeless discharge lamp of this type, as shown in FIG. 3, one in which a bulb-shaped bulb 1 is formed so as to surround an induction coil 2 is known (Japanese Patent Publication No. 56-5038).
(See Japanese Patent Publication No. 5). A discharge gas containing mercury vapor is enclosed in the bulb 1, and a high-frequency electromagnetic field formed by flowing a high-frequency current in the induction coil 2 acts on the discharge gas to excite the discharge gas and emit ultraviolet light. Let them do it. In addition, a phosphor coating is formed on the inner surface of the bulb 1, and converts the ultraviolet rays emitted from the discharge gas into visible light for illumination.

[0004]

By the way, the high-frequency electromagnetic field formed by the induction coil 2 is formed not only outside the induction coil 2 but also inside (inside the coil) and inside the induction coil 2 (induction coil). The high-frequency electromagnetic field is also applied to the exhaust pipe 3 located at the central axis 2), and discharge plasma is also generated inside the exhaust pipe 3.

Since the exhaust pipe 3 is a thin pipe, the plasma density is high, and the exhaust pipe 3 is blackened by the strong impact of electrons and ions. Further, the blackening does not stop only in the exhaust pipe 3, and sodium knocked out from the glass of the exhaust pipe 3 due to the impact of electrons or ions may diffuse into the valve 1 and cause blackening of the entire valve 1.

The present invention has been made in order to solve the above problems, and an object of the present invention is to provide an electrodeless discharge lamp with less blackening of the exhaust pipe and a good luminous flux maintenance rate. .

[0007]

In order to solve the above-mentioned problems, the present invention has an induction coil to which a high-frequency current is applied, a shape surrounding the induction coil, and an exhaust pipe at the center of the coil axis. In an electrodeless discharge lamp, which is provided with a bulb made of a translucent material in which a discharge gas is enclosed, and which excites and emits the discharge gas by the action of a high-frequency electromagnetic field formed by an induction coil, a conductive material is provided on the outer surface of the exhaust pipe. It is characterized in that it is provided with an electromagnetic wave shield formed by, and by configuring in this way, the high-frequency electromagnetic field formed by the induction coil is blocked by the outer surface of the exhaust pipe, and the high density inside the exhaust pipe Since no plasma is generated,
The blackening of the exhaust pipe can be reduced, and the luminous flux maintenance rate is improved.

If a protective film is formed on the inner surface of the exhaust pipe in place of the electromagnetic wave shield, the exhaust pipe can be protected even if a high-density plasma is generated in the exhaust pipe, and the same effect as described above can be obtained. To be

In addition to the electromagnetic wave shield or the protective film, an electric field shield made of a conductive material is provided along the outer circumference of the induction coil, and the induction coil is inserted through the electric field shield.
It is characterized in that the il is arranged near the center of the bulb .
Furthermore, either one of the electromagnetic wave shielding or field shield, or may be a slit in both.

[0010]

FIG. 1 shows an embodiment of an electrodeless discharge lamp according to the present invention. In this embodiment, a bulb 1 formed so as to surround an induction coil 2 is used.
The bulb 1 has a spherical appearance made of a translucent material such as glass, and a cylindrical cavity 4 is formed at the center of the sphere, and an exhaust pipe 3 is formed along the central axis of the cavity 4. Has been formed. The exhaust pipe 3 communicates with the valve 1 that forms an airtight space. The induction coil 2 is arranged near the bottom of the cavity 4, that is, near the center of the valve 1 via an electric field shield 6 described later.

Here, in the formation of the valve 1 as described above, a spherical body 1a having an opening at a part thereof and a cylindrical body 1b having one end opening having a diameter substantially the same as the opening diameter are provided at respective opening ends. It is done by joining. It goes without saying that the bottom surface of the cylindrical body 1b is provided with a glass tube that constitutes the exhaust pipe 3 in advance.

A phosphor coating 5 is formed on the inner surface of the bulb 1 (including the outer peripheral surface and the bottom surface of the cylindrical body 1b). Inside the bulb 1, a rare gas such as argon is used as a discharge gas. And mercury is enclosed. Also, the tubular body 1b
An electric field shield 6 made of a conductive material such as aluminum is provided along the inner peripheral surface of the electric field shield 6. A slit (not shown) is provided in the electric field shield 6 in the vertical direction, that is, in the cylinder axis direction. At the same time, it is connected to the base 7 and grounded. Furthermore, an electromagnetic wave shield 8 made of a conductive material such as aluminum is provided on the outer surface of the exhaust pipe 3, and is connected to the base 7 and grounded.

In the electrodeless discharge lamp thus constructed, when a high frequency current is passed through the induction coil 2, a high frequency electromagnetic field formed around the induction coil 2 acts on the discharge gas sealed in the bulb 1. , Discharge plasma is formed,
Mercury is excited and emits ultraviolet rays. This ultraviolet ray is converted into visible light by the phosphor coating 5.

By the way, a strong plasma is generated in the vicinity of the induction coil 2, but the electric field shield 6 provided along the inner peripheral surface of the cylindrical body 1b weakens the impact of electrons and ions, and the bulb 1 Blackening of the inner surface can be reduced. Further, since the electric field shield 6 is provided with a slit and is grounded, eddy current loss in the electric field shield 6 is small and luminous efficiency is good. Further, since the exhaust pipe 3 is covered with the electromagnetic wave shield 8, strong plasma is not generated in the exhaust pipe 3 and the exhaust pipe 3 is less blackened. Further, since the amount of sodium knocked out from the glass constituting the exhaust pipe 3 by electron or ion bombardment is small, the luminous flux maintenance factor can be improved.

An electromagnetic wave shield 8 provided on the exhaust pipe 3
By forming a slit in the vertical direction, the same effect can be obtained as an electric field shield, in which case eddy current loss is reduced.

Next, FIG. 2 shows a different embodiment of the present invention. The difference from the above embodiment is that a protective film 9 is formed on the inner surface of the exhaust pipe 3 instead of the electromagnetic wave shield 8. Since other configurations are the same as those of the above-described embodiment, the description will be omitted by giving the same reference numerals to the same configurations.

With this configuration, even if a high density plasma is generated in the exhaust pipe 3 due to the high frequency electromagnetic field formed by the induction coil 2, the glass forming the exhaust pipe 3 is protected from the plasma. You can Therefore, blackening of the exhaust pipe 3 can be reduced, and the amount of sodium knocked out from the glass of the exhaust pipe 3 by electron or ion bombardment is small, so that the luminous flux maintenance factor is improved.

[0018]

As described above, the present invention has an induction coil to which a high-frequency current is applied, a shape surrounding the induction coil, and an exhaust pipe at the center of the coil axis, in which discharge gas is enclosed. With a bulb made of translucent material,
In an electrodeless discharge lamp that excites and emits a discharge gas by the action of a high-frequency electromagnetic field formed by an induction coil, an electromagnetic wave shield made of a conductive material is provided on the outer surface of the exhaust pipe, so that it is formed by the induction coil. Since the high-frequency electromagnetic field is blocked by the outer surface of the exhaust pipe and a high-density plasma is not generated in the exhaust pipe, blackening of the exhaust pipe can be reduced and the luminous flux maintenance rate is improved.

If a protective film is formed on the inner surface of the exhaust pipe instead of the electromagnetic wave shield, the exhaust pipe can be protected even if a high-density plasma is generated in the exhaust pipe, and the same effect as described above can be obtained. To be And along the outer circumference of the induction coil
The electric field shield made of a conductive material.
Place the induction coil near the center of the valve via a shield.
Since it was installed, strong plasma is generated near this induction coil.
However, due to the action of the electric field shield, electrons and ions are generated.
The impact is also weakened and the blackening of the inner surface of the valve can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a different embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

1 valve 2 induction coil 3 exhaust pipe 4 cavities 5 Phosphor coating 6 Electric field shield 7 base 8 electromagnetic shield 9 Protective film

Claims (3)

(57) [Claims] 1. An induction coil to which a high frequency current is applied,
It has a shape surrounding the induction coil, an exhaust pipe in the center of the coil axis, and a valve made of a translucent material in which a discharge gas is enclosed, and by the action of a high-frequency electromagnetic field formed by the induction coil. in an electrodeless discharge lamp in which a discharge gas excitation light-emitting is, Rutotomoni provided an electromagnetic wave shielding made of a conductive material on an outer surface of the exhaust pipe, the induction
An electric field shield made of a conductive material along the outer circumference of the conducting coil.
And the induction coil through this electric field shield.
An electrodeless discharge lamp, which is arranged near the center of a bulb . 2. An induction coil to which a high frequency current is applied,
It has a shape that surrounds the induction coil and
Light-transmitting with an exhaust pipe inside and discharge gas sealed inside
With a valve made of material and formed by an induction coil
The discharge gas is excited by the action of the high-frequency electromagnetic field
That electrodeless discharge lamp odor Te, thereby forming a protective film on the inner surface of the exhaust pipe, conductive along the outer circumference of the induction coil
The electric field shield formed by the material is provided.
An electrodeless discharge lamp you characterized in that it is arranged the induction coil in the vicinity of the center of the valve through. 3. An electrodeless discharge lamp according to the electromagnetic wave either the shield or the field shield, or any of claims 1 or claim 2, characterized in that a slit on both sides.