JPH10312777A - Electrodeless fluorescent lamp apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress blackening in a dent cavity bottom part of a bulb and provide an electrodeless fluorescent lamp apparatus with a long life. SOLUTION: This apparatus comprises an in candescent bulb-shape bulb having a dent cavity 2, an induction coil 6 inserted into the dent cavity 2, and a shield 7 installed between the induction coil 6 and the inner circumference wall of the dent cavity 2 and converts electric energy into visible light rays by a phosphor layer 4 formed on the bulb wall face. In this case, a cylindrical projected tube 3 which is projected toward the induction coil side from the bottom face of the dent cavity 2 and of which the tip end is closed is formed, the upper end of the induction coil 6 is positioned lower than the upper end rim of the shield 7, and the lower end of the induction coil 6 is positioned higher than the tip end of the projected tube 3, so that blackening of the bottom part of the dent cavity can be suppressed without elevating the starting voltage of the lamp and shortening of the life of the lamp can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method in which a high-frequency electromagnetic field formed by applying a high-frequency current to an induction coil has no electrode in a discharge gas-filled bulb and acts on the discharge gas in the bulb. The present invention relates to an electrodeless fluorescent lamp device that discharges a discharge gas to emit ultraviolet rays, and converts the ultraviolet rays into visible light by a phosphor layer formed on a bulb wall.

[0002]

2. Description of the Related Art Conventionally, an electrodeless fluorescent lamp has been known which excites a discharge gas to emit light by applying a high-frequency electromagnetic field to a discharge gas sealed in a bulb. This type of electrodeless fluorescent lamp has features such as small size, high output, and long life, and is being researched and developed in various places.

As this type of electrodeless fluorescent lamp, for example, as shown in FIG.
Is known to be formed in a shape enclosing a circle. Such an electrodeless fluorescent lamp includes a bulb-shaped bulb 1 having a bottomed hollow cylinder 2 at the center and an induction coil 6 disposed in the hollow cavity 2. Is discharged, and a high-frequency electromagnetic field formed by flowing a high-frequency current through the induction coil 6 is applied to the discharge gas to excite the discharge gas to emit ultraviolet rays. The light is converted into visible light by the phosphor layer 4 formed on the inner wall surface and used for illumination.

In the electrodeless discharge lamp, a magnetic field line B is generated by a high-frequency current flowing through an induction coil used for lighting, as shown in FIG. Ions and the like in the plasma collide with the wall surface of the bulb 1 along the lines of electric force E, blackening the lamp and shortening the life of the lamp.

Further, the induction coil 6 is heated to a high temperature due to self-heating and radiation of heat from the lamp, and the wire of the induction coil 6 is deteriorated.

Therefore, in order to shield the lines of electric force E and to radiate the heat of the induction coil 6, a cylindrical shape is provided between the induction coil 6 and the inner peripheral wall of the cavity 2 as shown in FIG. A shielding metal (shield) 7 is provided.

However, this shield 7 causes a line of electric force generated by the induction coil 6 to go outside the shield 7 and does not cross the discharge space, so that there is a problem that the starting voltage of the lamp increases.

In order to prevent the starting voltage from rising, several notches (slits) 8 are formed in the shield 7 in the axial direction as shown in FIG. This slit 8
Prevents the eddy current caused by the magnetic field of the induction coil 6 from flowing in the circumferential direction of the shield 7, and thus has an effect of reducing the loss generated by the eddy current.

[0009]

However, when the shield 7 is used, blackening of the side surface of the hollow cavity of the bulb 1 can be prevented and the induction coil 6 can be radiated.
The electric field concentrates on the upper end of the induction coil 6 that is not covered with the shield 7, causing a problem that blackening of the bottom of the hollow 2 increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a long-life electrodeless fluorescent lamp device which reduces blackening of the bottom of a hollow cavity of a bulb. It is in.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a bulb-shaped bulb having a bottomed cylindrical hollow at the center, an induction coil inserted into the hollow, and an induction coil. With a shield disposed between the inner peripheral wall of the hollow cavity and grounded, ultraviolet rays radiated by applying a high-frequency electromagnetic field formed by the induction coil to the discharge gas sealed in the bulb, In the electrodeless fluorescent lamp device, which is converted into visible light by a phosphor layer formed on the bulb wall surface, a cylindrical protruding tube is formed which protrudes from the bottom surface of the hollow cavity toward the induction coil side and has a closed end. By arranging the upper end of the induction coil below the upper edge of the shield and the lower end of the induction coil above the tip of the protruding tube,
The blackening of the bottom of the hollow can be reduced without increasing the starting voltage of the lamp, and the life of the lamp can be prevented from being shortened.

If the upper edge of the shield is bent inward so as to cover the upper end of the induction coil, blackening of the bottom of the hollow can be further reduced, and the life of the lamp can be prevented from being shortened. it can.

[0013]

FIG. 1 shows an embodiment of an electrodeless fluorescent lamp according to the present invention. In the figure, reference numeral 1 denotes a bulb formed of a light-transmitting material such as glass, and its appearance. Has a hollow cylindrical cavity 2 with a bottom in the center in the shape of a light bulb, and has a cylindrical projecting tube 3 projecting from the bottom surface of the hollow cavity 2 to the opening side and having a closed end, and the inside thereof is airtight discharge. Form a space. A phosphor layer 4 is formed on the inner surface of the bulb 1. In the present embodiment, the phosphor layer 4 is formed on the inner surface of the peripheral wall of the bulb 1 and the outer surface of the hollow 2, but may be formed on the inner surface of the protruding tube 3 as necessary. Further, a discharge gas is sealed in the bulb 1 via an exhaust pipe 5. As the discharge gas, for example, a rare gas such as argon or krypton and at least mercury are sealed.

Numeral 6 denotes an induction coil inserted into the hollow 2 of the hollow. The induction coil 6 is disposed at a position where the protruding tube 3 is wound.
The lower end of the induction coil 6 is located below the upper end of the protruding tube 3.

Reference numeral 7 denotes a cylindrical shield disposed between the induction coil 6 and the inner peripheral wall of the hollow cavity 2. The shield 7 shields a high-voltage electric field generated from the induction coil 6, and The valve 1 is prevented from being deteriorated and blackened. The shield 7 is arranged to be grounded, and is provided with several cuts (slits) 8 in the axial direction so that eddy current does not flow in the circumferential direction of the shield 7 to cause power loss (see FIG. 5). ).

By the way, in the conventional electrodeless fluorescent lamp without the protruding tube 3, if the shield 7 is provided between the induction coil 6 and the inner peripheral wall of the hollow 2, as described above, the starting voltage increases. In order to prevent this, as shown in FIG. 4, the starting voltage is increased by placing the induction coil 6 at the same level as or slightly above the upper edge of the shield 7 so as to be in contact with the bottom of the cavity 2. I am holding it down. However, if the induction coil 6 is put out at or slightly above the upper edge of the shield 7,
The electric field concentrates there, causing blackening at the bottom of the cavity 2 and shortening the lamp life.

However, according to this embodiment, the hollow cavity 2
The starting voltage of the lamp is increased by arranging the protruding tube 3 in such a manner that the upper end of the induction coil 6 is located below the upper end edge of the shield 7 and the lower end of the induction coil 6 is located above the tip of the protruding tube 3. Without this, the blackening of the bottom of the hollow 2 can be reduced, and the life of the lamp can be prevented from being shortened.

Next, FIG. 2 shows a different embodiment of the present invention.
Is bent inward to cover the upper end of the induction coil 6 disposed inside the shield 7, and the other configuration is the same as that of the above-described embodiment. The description is omitted by appending a symbol.

With this configuration, the blackening of the bottom of the hollow 2 can be further reduced, and the life of the lamp can be prevented from being shortened.

[0020]

As described above, according to the present invention, a cylindrical projecting tube is formed which protrudes from the bottom surface of the hollow cavity toward the induction coil and has a closed end, and the upper end of the induction coil is located below the upper edge of the shield. Positioning so that the lower end of the induction coil is located above the tip of the protruding tube, it is possible to reduce the blackening of the bottom of the hollow cavity without increasing the starting voltage of the lamp and to prevent the life of the lamp from being shortened be able to. Further, if the upper end edge of the shield is bent inward to cover the upper end of the induction coil, blackening of the bottom of the hollow cavity can be further reduced, and the life of the lamp can be prevented from being shortened.

[Brief description of the drawings]

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

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

FIG. 3 is a cross-sectional view showing a main part of a conventional example, showing magnetic lines of force and electric lines of force generated by an induction coil.

FIG. 4 is a sectional view showing a conventional example.

FIG. 5 is a perspective view showing an example of a shield.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bulb 2 Depression cavity 3 Projection tube 4 Phosphor layer 5 Exhaust tube 6 Induction coil 7 Shield 8 Slit

Claims (2)

[Claims] 1. A bulb-shaped bulb having a cylindrical hollow with a bottom at the center, an induction coil inserted into the hollow, and an inner coil between the induction coil and the inner peripheral wall of the hollow. A shield that is grounded, and converts ultraviolet light emitted by applying a high-frequency electromagnetic field formed by the induction coil to the discharge gas sealed in the bulb to visible light by a phosphor layer formed on the bulb wall surface. An electrodeless fluorescent lamp device comprising: a cylindrical protruding tube that protrudes from the bottom surface of the recessed cavity toward the induction coil and has a closed end, and an upper end of the induction coil is located below an upper end edge of the shield; And
An electrodeless fluorescent lamp device, wherein a lower end of an induction coil is disposed above a tip of the protruding tube. 2. An upper edge of the shield is bent inward,
The electrodeless fluorescent lamp device according to claim 1, wherein an upper end of the induction coil is covered.