JPH0574416A - Low pressure mercury vapor discharge lamp - Google Patents

Abstract

PURPOSE:To provide a low pressure mercury vapor discharge lamp, which can control the mercury vapor pressure in a tube to an optimal value close to approximately 6X10-3mmHg for a long time, and which can prevent the falling off of amalgam without inducing a failure such as breaking of a fine tube. CONSTITUTION:An emission tube 8, the end of which is sealed by a mount 13 for supporting an electrode 17, is housed in an envelop provided with a lighting circuit along with a base, and the tube is thus used. A mercury amalgam 19 of bismuth.indium, the atomic ratio of bismuth versus indium of which is 0.45:0.55-0.60:0.40, and the atomic ratio of mercury versus the sum of bismuth and indium is 0.038:0.962-0.005:0.995, is housed in a fine tube 18 extending from the mount, while the amalgam is separated from the sealed point of the end of the fine tube.

Description

Detailed Description of the Invention

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low pressure mercury vapor discharge lamp in which the mercury vapor pressure in a tube is controlled by an amalgam.

[0003]

2. Description of the Related Art In a low-pressure mercury vapor discharge lamp generally typified by a fluorescent lamp, when the tube wall temperature is around 40 ° C. and the mercury vapor pressure is about 6 × 10 −3 mmHg, the supplied electric power is converted into ultraviolet rays. For example, when this fluorescent lamp is housed in a ball bulb-shaped envelope and turned on, the mercury vapor pressure exceeds the above value as the ambient temperature rises, and the light output is increased. There are problems such as deterioration.

When the fluorescent lamp is lit and used under severe temperature conditions, the mercury vapor pressure in the fluorescent lamp is kept within an appropriate range by using an amalgam having a vapor pressure lower than that of pure silver. The method of controlling to is effective.

Conventionally, this type of amalgam is often attached to the wall surface of the stem at the end of the lamp. However, the present inventors have taken into consideration the workability when enclosing the amalgam, and have this amalgam inside a thin tube extending from the stem. It is attempted to hold the thin tube so that it cannot be removed by a narrowed portion provided in the middle of the thin tube.

On the other hand, as the amalgam, bismuth
Indium alloy with mercury added is the most suitable,
Particularly in this case, as shown in Japanese Utility Model Publication No. 58-21067, the atom ratio of bismuth to indium is
0.45: 0.55 to 0.60: 0.40, and the atom ratio of the sum of mercury to bismuth indium is 0.0
It is known that when it is set to 4: 0.96 to 0.10: 0.90, the mercury vapor pressure can be stabilized at around 6 × 10 −3 mmHg over a wide temperature range.

However, as a result of various experiments conducted by the present inventors, as in the fluorescent lamp according to the present invention, the fluorescent lamp according to the present invention is housed in a substantially sealed envelope together with a heat source such as a ballast, so that an existing incandescent lamp can be obtained. For the purpose of replacing it, the ambient temperature becomes extremely higher than that of general fluorescent lamps.Therefore, if the composition of the amalgam is specified as in the above prior art, the amalgam will be lit while the temperature is high. It has been found that it becomes molten and easily flows out.

In order to reduce such outflow, if the amalgam is disposed on the tip side of the sealing portion of the thin tube, the temperature of that portion is lowered, but the difference in thermal expansion between the amalgam and the glass as the thin tube material. As a result, problems such as breakage of a thin tube in which internal strain remains during sealing are likely to occur.

[0009]

The present invention has been made under these circumstances, and the mercury vapor pressure in a tube can be controlled to an optimum value in the vicinity of 6 × 10 −3 mmHg for a long period of time. Moreover, it is an object of the present invention to provide a low-pressure mercury vapor discharge lamp capable of preventing the amalgam from falling off without inducing troubles such as breakage of a thin tube.

[Constitution of Invention]

[0011]

In order to solve the above-mentioned problems, the low-pressure mercury vapor discharge lamp of the present invention comprises an arc tube whose end is sealed by a mount supporting electrodes, and a base together with a lighting circuit. It is housed in an envelope and used for lighting, and the atom ratio of bismuth to indium is 0.4.
5: 0.55 to 0.60: 0.40, and the atom ratio of the sum of mercury to bismuth and indium is 0.038: 0.96.
The bismuth-indium mercury amalgam having a relationship of 2 to 0.005: 0.995 was housed in a thin tube extending from the mount, and was placed apart from the sealing portion at the tip of the thin tube. It is a feature.

[0012]

According to the present invention, the atom ratio of mercury to the sum of bismuth-indium of the amalgam contained in the thin tube is 0.038: 0.962 to 0.005: 0.995, and the atom ratio of bismuth to indium is 0.45: 0.55
Since it is specified to be 0.60: 0.40, a stable alloy of bismuth and indium can be obtained, and further, since the content of mercury is reduced, the melting point of the amalgam is correspondingly increased, which shortens the life of the lamp. Without this, the mercury vapor pressure in the tube can always be controlled to the optimum value until the end of this life.

In addition, since the amalgam is disposed apart from the sealing portion at the tip of the thin tube, it is possible to reduce troubles such as breakage of the thin tube due to residual strain caused by sealing the thin tube.

[0014]

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

In FIG. 1, reference numeral 1 denotes a cover made of synthetic resin, and a cap 2 is attached to the top of one end of the cover 1.
A substantially spherical globe 3 is fitted in the opening at the other end of the cover 1, and the cover 1 and the globe 3 constitute an envelope 4 which is similar to a ball-shaped incandescent lamp.

In this envelope 4, a fluorescent lamp 5 which is a typical low pressure mercury vapor discharge lamp, and this fluorescent lamp 5 are provided.
The lighting tube 6 as a starting element and the choke coil type ballast 7 as a lighting circuit element are integrally housed.

As shown in FIG. 2, the arc tube 8 of the fluorescent lamp 5 has a straight tube-shaped glass bulb bent in a substantially U-shape at the center between both ends 9, 9. Between the bent portion 10 and both end portions 9, 9 is bent in a substantially U-shape in a direction substantially orthogonal to the plane including the U-shape, and both end portions 9, 9 and the bent portion 10 are formed. They are in the shape of a saddle, which are adjacent to each other in the same direction.

The inner surface of the arc tube 8 is coated with a phosphor coating 12, and flare portions 14 of a mount 13 are respectively sealed to both ends 9 and 9 as shown in FIG. ing.

Internal lead wires 16 and 16 are sealed in the stem tube 15 connected to the flare portion 14, and these lead wires 16 and 16 are sealed.
A filament 17 as an electrode is connected between them. In addition, the thin tube 18 extended from the stem tube 15 of each mount 13,
The stem tube 15 is opened at the tip end thereof, and the thin tube 18 is used to exhaust the inside of the arc tube 8 and to enclose a predetermined amount of inert gas.

In addition, such a fluorescent lamp 5 is housed in the envelope 4 with both ends 9, 9 and the bent portion 10 facing the base 2 side, and the filament 17 thereof is turned on. The tube 6 is of course connected to the base 2 via a ballast 7.

By the way, in the thin tube 18 of the arc tube 8,
Amalgam 19 that controls the mercury vapor pressure in the tube during steady lighting
Is installed. This amalgam 19 is bismuth (B
i) A compound of an alloy of indium (In) and mercury (Hg) is formed into one substantially spherical lump, and such an amalgam 19 is sealed with a narrowed portion 20 provided in the middle of the thin tube 18. It is held so as not to fall off from the toe and is arranged to be separated from the sealing end of the thin tube 18.

The amalgam 19 has an atom ratio of bismuth to indium of 0.45: 0.55.
60: 0.40, and the atom ratio of the sum of mercury and indium bismuth is 0.038; 0.962-0.00.
5: 0.995, and the reason for this will be described below with reference to FIGS.

That is, FIG. 4 shows the transition of mercury vapor pressure with respect to temperature. In FIG. 4, the curve indicated by A is the vapor pressure curve of pure water silver, and B is the conventionally known amalgam of indium-mercury (5%). Of the indium-mercury (10%) amalgam.

From FIG. 4, it can be seen that the higher the content ratio of mercury in the amalgam, the closer the vapor pressure curve becomes to the vapor pressure curve of pure water silver. To obtain the desired mercury vapor pressure at a certain temperature, We find that it is necessary to specify the amount.

Therefore, the present inventors conducted a more detailed experiment based on this point of view. That is, in this experiment, an amalgam having a bismuth-indium-mercury atom ratio of 0.512: 0.454: 0.033 (64.5: 31.5: 4.0 in weight%) and also bismuth- Indium-mercury atom ratio is 0.51
7: 0.459: 0.025 (65.2: 3 by weight%)
Amalgams of 1.8: 3.0) were produced, and the transition of mercury vapor pressure with respect to the temperature of both amalgams was examined. The curve indicated by D in FIG. 4 shows the vapor pressure curve of the former amalgam, and E shows the vapor pressure curve of the latter amalgam. As a result, in the amalgam in which the atom ratio of bismuth-indium-mercury is defined as described above, the temperature is about 80 ° C to 10 ° C.
In the temperature range of 0 ° C, the vapor pressure curves D and E are flat near the optimum value of the mercury vapor pressure of about 6 x 10 -3 mmHg, clearly controlling the mercury vapor pressure in the high temperature range. I know that The temperature range of 80 ° C. to 100 ° C. substantially coincides with the ambient temperature in the envelope 4 during steady lighting. Therefore, if the amalgam having the above composition is used, the fluorescent lamp 5 will not be included in the envelope 4. It is possible to control the mercury vapor pressure in the tube to an optimum value even when the lamp is turned on under severe temperature conditions.

Further, the present inventors further examined the amount of mercury in the amalgam and investigated how this amount of mercury affects the control characteristics of mercury vapor pressure.
The results shown in FIG. 5 were obtained. From FIG. 5, the atom ratio of mercury to the sum of bismuth-indium is 0.03.
When it exceeds 8, the range where the vapor pressure curve becomes flat near about 6 × 10 −3 mmHg becomes gradually narrow, that is, 80 ° C.
It can be seen that the mercury vapor pressure cannot be controlled stably in the high temperature range of 100 ° C. Therefore, in the case of the fluorescent lamp 5 used for lighting in a high temperature atmosphere inside the envelope 4, it is necessary to specify the upper limit of the atom ratio of mercury to 0.038.

On the other hand, when the content ratio of mercury is lowered,
Although the temperature range in which the mercury vapor pressure can be controlled to about 6 × 10 −3 mmHg is widened, on the other hand, as shown in FIG. 6, it has been found that the light output significantly decreases as the lighting time elapses. That is, in this experiment, the life of the fluorescent lamp 5 is defined as the time when the light output at the time of 6000 hours is less than 70% of the light output at the time of 100 hours,
Therefore, it is found that the lower limit of the atom ratio of mercury needs to be set to 0.005 in order to satisfy the desired life.

From the above, the atom ratio of mercury to the sum of bismuth-indium is 0.038: 0.9.
If it is defined as 62 to 0.005: 0.995, the mercury vapor pressure in the tube can always be controlled to an optimum value until the end of the life of the fluorescent lamp 5 without shortening the life of the fluorescent lamp 5.

As a result of various experiments, the atom ratio of bismuth to indium is in the range where bismuth and indium can easily form a stable alloy, that is, the bismuth-indium eutectic point or 0.45 near this eutectic point. : 0.5
It was concluded that 5 to 0.60: 0.40 is desirable.

Further, since the operating temperature of the amalgam 19 is higher than usual, the atom ratio of mercury to the sum of bismuth-indium may be smaller than that of the prior art, which results in a lower mercury content. Therefore, the melting point of amalgam 19 becomes higher accordingly. As a result, amalgam 19
If the amalgam is housed in the thin tube 18, the amalgam does not drop into the high-temperature discharge space during lamp lighting, and the mercury vapor pressure in the tube can be reliably controlled.

Further, since the amalgam 19 is arranged apart from the sealing portion at the tip of the thin tube 18 where the distortion due to sealing remains, even if the amalgam 19 adheres to the inner wall of the thin tube 18, It is possible to significantly reduce troubles such as breakage of thin tubes due to the difference in thermal expansion between amalgam and thin glass.

In the above-described embodiment, the envelope has a ball-bulb shape, but may have an elongated cylindrical shape, and the fluorescent lamp is not limited to the curved tube shape but may be a straight tube shape. ..

[0033]

According to the present invention described above, the mercury vapor pressure in the tube can be controlled to an optimum value in the vicinity of about 6 × 10 −3 mmHg until the end of the life of the lamp without shortening the life of the lamp. Since the operating temperature of this amalgam is higher than usual, the atom ratio of mercury to the sum of bismuth-indium may be small, so that the content of mercury is small and the melting point of the amalgam is correspondingly high. As a result, even if the amalgam is housed in the thin tube, the amalgam does not drop into the high-temperature discharge space during lamp lighting, and the mercury vapor pressure in the tube can be reliably controlled.

Further, since the amalgam is arranged apart from the sealing portion at the tip of the thin tube, troubles such as breakage of the thin tube can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of the entire low-pressure mercury vapor discharge lamp according to the present invention.

FIG. 2 is a perspective view showing a fluorescent lamp according to this embodiment in a partial cross section.

FIG. 3 is a sectional view of the tube end portion of the fluorescent lamp shown in FIG.

FIG. 4 is a characteristic diagram showing characteristics when the amalgam composition is changed.

FIG. 5 is a characteristic diagram showing characteristics when the amalgam composition is changed.

FIG. 6 is a characteristic diagram showing characteristics when the amalgam composition is changed.

[Explanation of symbols]

2 ·· Base, 4 ·· Envelope, 7 ·· Lighting circuit (ballast), 8 ·· Arc tube,
13 ... Mounts 17 ... Electrodes (filaments), 18 ...
... Amalgam

Claims (1)

[Claims] 1. A low-pressure mercury vapor discharge lamp in which an arc tube whose end is sealed by a mount supporting an electrode is housed in an envelope equipped with a lighting circuit and is used for lighting.
Atom ratio of bismuth to indium is 0.45: 0.5
5 to 0.60: 0.40, and the atom ratio of the sum of mercury to bismuth and indium is 0.038: 0.962 to 0.0.
A bismuth-indium mercury amalgam having a relationship of 05: 0.995 is housed in a thin tube extending from the mount and is arranged apart from the sealing portion at the tip of the thin tube. Low pressure mercury vapor discharge lamp.