JPH065248A - Aperture type low voltage discharge lamp - Google Patents

Abstract

PURPOSE:To prevent a blackening of the aperture and to prevent a reduction of a light flux and a deterioration of the light distribution property. CONSTITUTION:In an aperture type low voltage discharge lamp in which an aperture 3 is formed at one side of a bulb 1 a discharge gas is sealed; a filament 6 is sealed at the end of the bulb 1 through wells 5a and 5b; and auxiliary electrodes 7a and 7b are connected to the wells; the tips of the auxiliary electrodes 7a and 7b are displaced to the opposite side of the aperture 3 making the bulb center axis as the center. As a result, since the tips of the auxiliary electrodes 7a and 7b are separated from the aperture 3, the rate of attaching the electrode substance to the aperture 3 is reduced even though such a substance from the auxiliary electrodes is scattered, and the blackening of the aperture 3 can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low pressure discharge lamp such as a fluorescent lamp or a rare gas discharge lamp, and more particularly to a low pressure discharge lamp having an aperture portion for transmitting light formed on one side of a bulb.

[0002]

2. Description of the Related Art Conventionally, in a low-pressure discharge lamp such as a fluorescent lamp containing mercury and a rare gas discharge lamp containing rare gas such as xenon, a light transmitting opening for transmitting light to one side of a bulb, That is, there is known an aperture type low pressure discharge lamp in which an aperture portion is formed. In this type of aperture type low pressure discharge lamp, a phosphor coating or a reflecting film is formed only on a predetermined area in the circumferential direction on the inner surface of the bulb so that light can pass through the other side region through the phosphor coating or the phosphor coating. Light is emitted only from this aperture portion, or strong light is transmitted from the aperture portion, so that the effective utilization rate of light is high and the efficiency is excellent.

By the way, generally, in a low pressure discharge lamp,
When one filament electrode is in the anode mode, it receives electrons emitted from the other electrode, and in the cathode mode, it receives cations. Due to such a discharge phenomenon, the temperature of the filament electrode rises, and the electron emitting substance (emitter) made of BaO—SrO—CaO carbonate coated on the filament tends to evaporate. As a result, the emitter is depleted early and the startability of the lamp deteriorates, the emission of thermoelectrons is not smooth, it becomes impossible to light early, and the evaporated emitter adheres to the bulb and blackens. There is a problem that causes it.

As a measure for reducing such an increase in electrode temperature, there is known a means for attaching an antenna-shaped auxiliary electrode extending to the discharge space side of the filament electrode, and such an auxiliary electrode is installed. Then, when the filament electrode is in the anode mode, the auxiliary electrode captures electrons that have jumped in, and in the cathode mode, the cation is received, so that the current can be bypassed through the auxiliary electrode. Therefore, the current flowing through the filament electrode can be shared, the heat load on the filament electrode can be reduced, the temperature of the filament electrode can be lowered, and evaporation of the emitter can be prevented.

Also in the above-mentioned aperture type low pressure discharge lamp, an auxiliary electrode is attached to the filament electrode in order to reduce the temperature rise of the filament electrode and suppress the evaporation of the emitter to prevent early exhaustion of the emitter and blackening of the bulb. There is a case where a structure to be adopted is adopted.

That is, an aperture type fluorescent lamp having a conventional auxiliary electrode is shown in FIG. 4, in which 1 is a glass bulb. As shown in FIG. 4C, the phosphor coating 2 is formed on the inner surface of the bulb 1. In this case, the phosphor film 2 is formed only on one side of the inner surface of the bulb 1, and the other side, that is, the predetermined angle range θ.
Therefore, a portion through which the phosphor coating 2 is not formed is formed with a transparent portion, that is, an aperture portion 3.

The end of the valve 1 is closed by a stem 4, and the stem 4 has a pair of wells 5a, 5a.
b is airtightly penetrated and sealed. Wells 5a, 5
The filament 6 is hung between b. The filament 6 is composed of a single or double coil, and an emitter (not shown) made of BaO—SrO—CaO carbonate is applied on the surface.

Auxiliary electrodes 7a and 7b are connected to the wells 5a and 5b, respectively. These auxiliary electrodes 7
Reference characters a and 7b each have a rod shape made of a heat-resistant conductive metal such as tungsten. The roots are welded to the wells 5a and 5b, and the tips extend beyond the filament 6 toward the discharge space. And is bent in an L shape, for example. The bulb 1 is filled with a predetermined amount of mercury and a rare gas such as argon.

In the aperture type fluorescent lamp having such a structure, when the filament 6 is in the anode mode, the auxiliary electrodes 7a and 7b capture electrons that jump in,
Further, in the cathode mode, cations are received, and therefore, the current is bypassed through these auxiliary electrodes 7a and 7b, so that the current flowing through the filament electrode 6 is reduced and the heat load on the filament electrode 6 is reduced. Since the temperature of the filament electrode 6 is lowered, evaporation of the emitter can be prevented.

[0010]

However, in the case of the conventional aperture type low-pressure discharge lamp, as can be understood from FIG. 4, the pair of auxiliary electrodes 7a and 7b have their tip portions sandwiching the bulb central axis OO. They are arranged so that they are symmetrically positioned to the left and right. That is, one auxiliary electrode 7
The tip portion of a is close to the aperture portion 3, and the tip portion of the other auxiliary electrode 7b sandwiches the valve center axis OO,
It was placed away from the aperture section 3.

As described above, the auxiliary electrodes 7a and 7b capture electrons when the filament 6 is in the anode mode and receive cations when the filament 6 is in the cathode mode, so that the current flowing through the filament 6 is absorbed. Although it has a reducing effect, the auxiliary electrodes 7a, 7b themselves may be scattered by being hit by electrons or ions. That is, in the anode mode, electrons collide with the auxiliary electrodes 7a and 7b, and in the cathode mode, cations collide, so that the auxiliary electrodes 7a and 7b themselves are bombarded by the electrons and ions and scattered. The scattered auxiliary electrode material adheres to the bulb wall and causes the bulb to blacken.

Particularly, in the conventional case, the tip portion of one auxiliary electrode 7a is close to the aperture portion 3, and the electrode material scattered from this auxiliary electrode 7a is directly exposed to the aperture portion 3.
And the aperture portion 3 is blackened.

When the aperture portion 3 is blackened, not only is the appearance unsightly, but also when light is emitted only through the aperture portion 3, when the vicinity of the electrodes of the aperture portion 3 is blackened, the transmitted light is blocked. As a result, there is a problem that the luminous flux is deteriorated and the light distribution characteristics are significantly deteriorated as compared with a non-aperture type lamp.

The present invention has been made in view of the above circumstances. An object of the present invention is to prevent the occurrence of blackening in the aperture portion and prevent a decrease in light quantity and deterioration of light distribution characteristics. It is intended to provide a discharge lamp.

[0015]

According to the present invention, an aperture portion is formed on one side of a bulb filled with a discharge gas, and a filament is sealed at the end portion of the bulb through a wells, and the tip portion is provided in the wells. In an aperture type low-pressure discharge lamp in which an auxiliary electrode protruding toward the discharge space side from the filament is connected, the tip of the auxiliary electrode is offset to the side opposite to the aperture part around the bulb central axis. To do.

[0016]

According to the present invention, since the tip of the auxiliary electrode is displaced away from the aperture part, even if the electrode material scatters from the auxiliary electrode, the ratio of adhering to the aperture part becomes small, and the black part of the aperture part is reduced. Can be reduced.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the first embodiment shown in FIG.

In FIG. 1, a lamp similar to the aperture type fluorescent lamp shown in FIG. 4 is shown, the same members as those in FIG. 3 are denoted by the same reference numerals, and the description thereof will be omitted. Only the points different from FIG. 3 will be described. .

That is, in FIG. 1, 1 is a bulb, 2 is a phosphor film, 3 is an aperture portion, 4 is a stem, 5a,
5b is wells and 6 is a filament. Wells 5
Auxiliary electrodes 7a and 7b are connected to a and 5b, respectively, and in the case of this embodiment, the respective tips of the auxiliary electrodes 7a and 7b welded to the wells 5a and 5b are kept away from the aperture portion 3 and the filament 6a. Is located on the opposite side of. That is, the tips of the auxiliary electrodes 7a and 7b are arranged so as to be offset to the side opposite to the aperture section 3 with the valve center axis OO as the center.

The bulb 1 is filled with a predetermined amount of mercury and a rare gas such as argon, and the lamp is turned on by a high frequency power source of 1 kHz or more. The operation of the aperture type fluorescent lamp having such a structure will be described.

While the lamp is on, a high-frequency voltage is applied between the filaments 6, 6 sealed at both ends of the bulb 1, and a high-frequency discharge is generated between the filaments 6, 6. This discharge excites the mercury vapor enclosed in the bulb 1 to emit ultraviolet rays, which are converted into visible light by the phosphor coating 2. This visible light is emitted to one side of the bulb 1 through the aperture portion 3.

In such discharge, the filament 6
In the anode mode, electrons come in, and in the cathode mode, they receive cations. At this time, the auxiliary electrodes 7a and 7b capture electrons and also receive cations, and the auxiliary electrodes 7a and 7b bear the discharge current flowing in the filament 6 to bypass the wells 5a and 5b. 6
The heat load on the filament 6 is reduced, and the temperature of the filament 6 can be lowered. Therefore, evaporation of the emitter coated on the filament 6 can be suppressed.

Then, the auxiliary electrodes 7a, 7b as described above are used.
Since electrons and ions jump into the auxiliary electrodes 7a and 7b themselves, the auxiliary electrodes 7a and 7b themselves are impacted by the electrons and ions and scattered. The scattered auxiliary electrode material adheres to the bulb wall and causes the bulb to blacken.

However, in the case of this embodiment, the tip ends of the pair of auxiliary electrodes 7a and 7b are the central axis O of the valve.
Since it is arranged so as to be displaced from -O in the direction away from the aperture section 3, even if the electrode substances are evaporated and scattered from these auxiliary electrodes 7a and 7b, the rate of attachment to the aperture section 3 is reduced.

Therefore, it is possible to prevent the blackening of the aperture part 3 early and prevent the deterioration of the appearance, and to reduce the deterioration of the luminous flux emitted through the aperture part 3 and the deterioration of the light distribution characteristics. can do.

It should be noted that, when high frequency lighting is performed, the anode drop voltage can be essentially lowered, the luminous efficiency can be increased, and the temperature rise of the filament 6 can be suppressed, so that evaporation of the emitter can be suppressed. It is advantageous in terms. In addition to this point, the auxiliary electrodes 7a, 7
The use of b is effective in reducing heat generation of the filament 6 and preventing evaporation of the emitter. Therefore, if both high frequency lighting and using the auxiliary electrodes 7a and 7b are adopted at the same time, it is effective to prevent evaporation of the emitter. The present invention is not limited to the above embodiment.

That is, in the above embodiment, the auxiliary electrode 7
The a and 7b are rod-shaped L-shaped ones so as to have an antenna function, and the area for receiving electrons and ions is increased by making them L-shaped. However, as shown in FIG. 2, the auxiliary electrodes 70a and 70b are flat plate strips. The auxiliary electrodes 70a and 70b may have a tip shape, and the tips of the auxiliary electrodes 70a and 70b may be arranged at positions apart from the aperture section 3 with the valve center axis OO interposed therebetween. In this case, since the surface areas of the auxiliary electrodes 70a and 70b are large, the area for receiving electrons and ions is large, the concentration of electrons and ions is relieved, and the scattering is reduced.

The auxiliary electrodes are not limited to being provided in two pieces for each filament, but may be attached one piece for one filament. In this case as well, the tip of the auxiliary electrode is attached from the aperture portion. It should be placed away from each other.

When the aperture portion 3 is formed, it is not limited to the non-coated portion of the phosphor coating 2, and as shown in FIG. 3, the reflection film 10 is formed on the inner surface of the bulb 1 at a predetermined angle. The structure may be such that it is formed in a range and the phosphor coating 2 is formed on the inner surface thereof over the reflective film 10 and the inner surface of the bulb. Furthermore, the present invention is not limited to fluorescent lamps, but can be implemented in rare gas discharge lamps that do not contain mercury, and is not limited to high frequency lighting.

[0030]

As described above, according to the present invention, since the tip of the auxiliary electrode attached to the electrode is arranged away from the aperture portion, even if the electrode substance is scattered from this auxiliary electrode, the auxiliary electrode is attached to the aperture portion. The rate of adhesion is reduced,
It is possible to reduce the blackening of the aperture portion, and prevent a decrease in luminous flux and deterioration of light distribution characteristics.

[Brief description of drawings]

FIG. 1 shows a main part of an aperture type fluorescent lamp according to a first embodiment of the present invention, FIG. 1 (A) is a side view of one end of the aperture type fluorescent lamp, and FIG. ,
(C) figure is sectional drawing which follows CC line of (B) figure.

FIG. 2 shows a main part of an aperture type fluorescent lamp according to a second embodiment of the present invention, (A) is a side view of one end of the aperture type fluorescent lamp, and (B) is a front view thereof. ,
(C) figure is sectional drawing which follows CC line of (B) figure.

FIG. 3 is a sectional view of an aperture type fluorescent lamp according to a third embodiment of the present invention.

4A and 4B show a main part of a conventional aperture type fluorescent lamp, FIG. 4A is a side view of one end of the aperture type fluorescent lamp, FIG. 4B is a front view thereof, and FIG. ) C in the figure
-C sectional drawing which follows the C line.

[Explanation of symbols]

1 ... Bulb, 2 ... Fluorescent film, 3 ... Aperture part, 4
… Stem, 5a, 5b… Wells, 6… Filament,
7a, 7b ... Auxiliary electrodes.

Claims (2)

[Claims] 1. An aperture portion is formed on one side of a bulb filled with a discharge gas, and a filament is sealed at the end of the bulb through a well so that the tip of the well is closer to the discharge space than the filament. An aperture-type low-pressure discharge lamp connected with a protruding auxiliary electrode, wherein the tip of the auxiliary electrode is offset to the side opposite to the aperture part around the bulb central axis. 2. The aperture type low pressure discharge lamp according to claim 1, wherein the auxiliary electrode has a rod shape.