JPH065255A - Mercury vapor discharge lamp - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a mercury vapor discharge lamp that prevents impurities from being generated from porous pellets and prevents an increase in starting voltage and blackening of a bulb. In a mercury vapor discharge lamp in which a mercury carrier 8 made by impregnating inorganic porous pellets 81 with liquid mercury is sealed in a bulb 1, the inorganic porous pellets have a higher density than silica such as alumina ceramics. Hydroxyl group (O
It is characterized in that it is made of ceramics having a low content of H group). When the porous pellets are made of ceramics having a low hydroxyl group (OH group) content, the adsorption of water is small, so that the generation of impurities in the valve can be reduced, the starting voltage is increased, and the valve Blackening can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mercury vapor discharge lamp in which mercury is contained by using a mercury carrier obtained by impregnating liquid mercury in an inorganic porous pellet when mercury is enclosed in a bulb.

[0002]

2. Description of the Related Art Conventionally, when mercury is sealed in an arc tube of a mercury vapor discharge lamp typified by a fluorescent lamp or the like, liquid mercury is weighed using a Mercury Dozer, and this weighed liquid mercury is discharged into an arc tube through an exhaust pipe. Had been thrown into. However, since liquid mercury has a large surface tension, it is difficult to accurately weigh a small amount of mercury, and it is unavoidable that the amount of enclosed mercury varies. However, in the mercury vapor discharge lamp, the minimum filling amount of the enclosed mercury amount is determined from the viewpoint of the lamp characteristics, and if it is less than this limit, the lamp output is significantly reduced and the life is shortened. For this reason,
In the conventional case, considering the variation of weighed mercury, the minimum required amount of mercury can be secured even if the variation becomes the lower limit.
The average filling amount was increased. However, if excessive mercury is filled in the lamp, many mercury particles will adhere to the inner surface of the bulb, and in the case of fluorescent lamps, etc., it will be visible from the outside during lighting, and the appearance will be significantly degraded. There are also problems such as the amount of mercury wasted in vain.

For this reason, there has been conventionally known a technique of encapsulating mercury in the form of amalgam or an intermetallic compound in a lamp. Any of the amalgam and intermetallic compound of mercury is advantageous in that it is easy to handle since it is a solid at room temperature and can be accurately weighed, so that the variation in the filling amount in the lamp can be reduced. However, since amalgam has a low mercury vapor pressure, it is effective for fluorescent lamps with a high tube wall load and lamps used under high ambient conditions, but the starting characteristics are good for lamps used under normal conditions. In particular, it is difficult to start especially in a low temperature environment, the light output during lighting is low, and there is a concern that it may go out.

Therefore, recently, a technique has been proposed in which inorganic porous pellets are impregnated with liquid mercury to form a mercury carrier, and the impregnated liquid mercury is brought into the lamp by accommodating such mercury carrier in the lamp. There is.

Inorganic porous pellets are wholly continuous 1
It consists of individual lumps, and micropores of microscopic size are continuously formed in the lumps to form continuous pores, or a large number of fine particles are locally fused. It is known that voids formed between particles are continuous with each other to form continuous pores throughout.

Such inorganic porous pellets are heated in a vacuum to remove air and water remaining in the continuous pores, and are poured into liquid mercury to pressurize the pores. Liquid mercury is allowed to infiltrate into it, and thereby a mercury carrier impregnated with mercury is formed.

In such a mercury carrier, since the liquid mercury in the continuous pores communicates with the outside world through the pores, the mercury vapor pressure in the surrounding environment becomes equal to that of the liquid mercury in the pores and equilibrates. Come to do. Therefore, if such a mercury carrier is enclosed in a lamp, the amount of filled mercury can be accurately controlled, the handling is easy, and the mercury vapor pressure is the same as the vapor pressure of liquid mercury. Even in the atmosphere, there is an advantage that the mercury vapor pressure in the lamp can be maintained in a relatively optimum state.

[0008]

However, in the lamp using the mercury carrier as described above, the starting voltage of the lamp may increase or blackening may occur at the end of the bulb.

When the cause of such a defect was investigated,
It has been found that in this type of mercury carrier, moisture is generated in the bulb, and this moisture raises the starting voltage of the lamp and causes blackening of the bulb. It has also been found that such a lamp that induces an increase in the starting voltage and blackening of the bulb tends to occur in a large proportion in a lamp using silica as the porous pellet.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a mercury vapor discharge lamp capable of preventing impurities from being generated in a bulb and preventing an increase in starting voltage and blackening of the bulb. To do.

[0011]

SUMMARY OF THE INVENTION The present invention has the following features in a valve:
In a mercury vapor discharge lamp in which a mercury carrier obtained by impregnating inorganic porous pellets with liquid mercury is sealed, the inorganic porous pellets are ceramics having a smaller content of hydroxy (OH) groups than silica, such as alumina ceramics. It is characterized in that it is configured by.

[0012]

The present inventors have conducted various studies on the case of a lamp using silica as a porous pellet. In the case of silica ceramics, the surface has a hydroxyl group (OH group), and the OH group adsorbs water. It is presumed that the adsorbed water causes impurities to increase the starting voltage and causes blackening of the valve.

Therefore, if the porous pellets are made of ceramics having a small content of hydroxyl groups (OH groups) such as alumina ceramics, the amount of water brought in is reduced and impurities are not generated in the valve. It is possible to prevent rising and blackening of the valve.

[0014]

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

FIG. 3 shows a ring-shaped fluorescent lamp. The inner surface of the bulb 1 made of a ring-shaped glass tube is shown in FIG.
As shown in FIG. 3, a phosphor coating 2 is formed, and the open end of the bulb 1 is closed by the flare stem 3. An exhaust thin tube 4 is connected to the flare stem 3,
The thin exhaust tube 4 communicates with a discharge space inside the bulb 1 through a communication hole 5. Lead wires 6 and 6 are sealed to the stem 3, and a filament electrode 7 is provided on the inner ends of the lead wires 6 and 6. A rare gas for starting such as argon is sealed in the valve 1.

A mercury carrier 8 is contained in the exhaust pipe 4. The mercury carrier 8 is an inorganic porous pellet 8
1 is impregnated with liquid mercury (not shown),
The inorganic porous pellet 81 has a hydroxyl group (OH) as compared with silica such as α-alumina or γ-alumina.
Ceramics with few bases are used to form a continuous pore structure.

In the mercury carrier 8 of the present invention, the inorganic porous pellet 81 has a small spherical shape, as schematically shown in FIG. Although not shown, the inorganic porous pellet 81 actually has continuous pores like ant nests throughout, and the pores are impregnated with liquid mercury throughout. A method of manufacturing such a mercury carrier 8 will be described.

An appropriate amount of organic powder, carbon powder or the like is mixed with fine powder of α-alumina or γ-alumina and mixed, and this is molded into small spheres, which are then fired to scatter the organic powder. Or by further calcination in steam or wet hydrogen to remove residual carbon.

This is because the fine alumina powder as a raw material is in intimate contact with each other, and these adjacent particles are fused to each other at their contact points to form a continuous agglomerate from the beginning, and Existing voids and voids generated by removing the organic powder and the carbon powder form mesh-like voids that are continuous with each other, forming continuous voids such as so-called ant nests. .

The above ceramic porous pellet 81
Is heated in vacuum to remove residual water and eliminate air in the pores. Then, the porous pellet 81 is cooled in a vacuum, immersed in a pool of liquid mercury and pressurized. Then, the liquid mercury 82 enters the continuous pores of the porous pellet 81 by the external pressure.

The mercury content of the mercury carrier 8 thus obtained is determined by the degree of vacuum when the porous pellet 81 is evacuated and the pressure when the liquid mercury is immersed, in addition to the porosity.

As shown in FIG. 2, such a mercury carrier 8 is housed in an exhaust thin tube 4, the inside of the valve 1 is exhausted through this thin tube 4, an inert gas is sealed therein, and then the exhaust thin tube 4 is placed.
Cut off. When the mercury carrier 8 is heated from the outside of the exhaust capillary 4 by a burner flame or high-frequency heating, the mercury impregnated in the mercury carrier 8 is evaporated,
This evaporated mercury condenses in other low temperature parts.

When the ring-shaped fluorescent lamp having the above-mentioned structure is turned on, the mercury condensed by the heat radiation from the filament electrode 7 and the mercury impregnated in the mercury carrier 8 are heated and evaporated, and the discharge current increases, and the mercury increases. The light output increases as the vapor pressure increases. When mercury is evaporated from the mercury carrier 8 and becomes excessive, the excessive mercury is condensed in the coldest portion, and the inside of the discharge space is maintained at a predetermined mercury vapor pressure.

In such a structure, the liquid mercury 8 is applied to the inorganic porous pellet 81, which is a solid mercury carrier 8.
Since it is configured to be impregnated with 2, it is easy to handle, and the content of mercury can be controlled relatively easily.
Variations in the amount of mercury enclosed are reduced. For this reason, even if the average enclosed amount is reduced, the required enclosed amount can be secured, and mercury can be significantly saved.

Further, since the mercury in the mercury carrier 8 is ordinary liquid mercury, the mercury vapor pressure is equal to that of pure water silver, and therefore the startability of the lamp and the low temperature lighting characteristics are good.

Moreover, in the mercury carrier 8 of this embodiment, since the inorganic porous pellet 81 is made of ceramics having less hydroxyl groups (OH groups) than silica such as α-alumina or γ-alumina, it does not adsorb water. Even if it is housed in the bulb 1 and heated to release mercury, the generation of H ₂ O is reduced. Therefore, no impurities are generated in the bulb 1, so that the starting characteristics are good, and the blackening of the light-carrying optical coating 2 does not occur.

Since the OH group is negatively charged, ionized evaporated mercury is attracted and sucked into the mercury carrier 8 to gradually lower the mercury vapor pressure in the bulb 1, and as a result, the luminous flux decreases with the lighting time. And the luminous flux maintenance factor decreases with the blackening of the bulb.

On the other hand, since the porous pellet 81 made of α-alumina or γ-alumina has no OH group, it takes a small amount of mercury and prevents the mercury vapor pressure from decreasing, and the luminous flux is changed with the lighting time. It can be prevented from falling. (Experimental Example) The results of experiments on the present invention will be described below.

The present inventors have made porous pellets (A) made of silica ceramics, porous pellets (B) made of α-alumina ceramics, and porous pellets (C) made of γ-alumina ceramics, respectively. The particle size d of was set to 2.4 mm. Each of these porous pellets (A), (B), and (C) was impregnated with 10 mg of liquid mercury to prepare a mercury carrier. Separately, 10 mg of pure mercury silver liquid mercury was prepared as in the conventional case (D). Each of these mercury carriers and pure water silver was enclosed in a ring fluorescent lamp of 30 W to complete the lamp, and each lighting test was conducted. Table 1 below shows the measured starting voltage of each lamp.

[0030]

[Table 1]

As is apparent from the above measured values, in the case of conventional pure water silver, no mercury carrier, which causes impurities to be brought in, is used, so that no impurities are generated in the bulb 1, and therefore the starting voltage is lowered. can do.

On the other hand, when the porous pellets (A) made of silica ceramics are used, since the surface has hydroxyl groups (OH groups), the generation of water is promoted, and this water becomes impurities, so that it is started. The voltage becomes high.

However, in the case of the porous pellets (B) made of α-alumina ceramics and the porous pellets (C) made of γ-alumina ceramics, since the hydroxyl groups (OH groups) are small, the generation of impurities is small, The starting voltage can be lowered. Since the particle size of γ-alumina is smaller than that of α-alumina, the number of pores is large and the surface area including the inner surface of continuous pores is large.
Therefore, the area where the impure gas adheres increases and the amount of residual gas increases. Therefore, the use of α-alumina is more advantageous than γ-alumina in both the starting characteristics and the luminous flux maintenance factor.

FIG. 4 shows the luminous flux maintenance factor (luminous flux range) of the conventional pure silver and the mercury carrier using the porous pellet (B) made of α-alumina ceramics of the present invention. It is a thing.

As described above, the luminous flux maintenance factor is affected by the decrease in the mercury vapor pressure due to the decrease in mercury and the light-shielding effect due to the blackening of the bulb. When pure water silver is used, impurities are generated and mercury is reduced. Since there is no factor that causes
It shows a high luminous flux maintenance factor.

On the other hand, when the porous pellet (B) made of α-alumina ceramics of the present invention is used,
Since the impregnated mercury is liquid mercury, it has the same mercury vapor pressure as pure water silver, no impurities are generated, and less mercury is adsorbed. Indicates the rate.

The present invention is not limited to the above embodiment, and the mercury carrier 8 is not limited to being housed in the exhaust thin tube 4 of the lamp 1, but may be attached to the stem 3 or the lead wire. The structure may be fixed to 6 or the like,
Therefore, the shape of the mercury carrier 8 is not limited to a spherical shape, and various forms such as a circular or square rod, a disc, and an annular plate can be implemented. Further, the present invention is not limited to the case of being applied to a fluorescent lamp, but can be applied to a lamp such as a high pressure mercury lamp, that is, a lamp in which mercury is sealed.

[0038]

As described above, according to the present invention, since the porous pellets are made of ceramics having a smaller hydroxyl group (OH group) content than silica such as alumina ceramics, the moisture content of the pellets themselves is reduced. The amount of adsorption is reduced, the generation of H ₂ O as an impurity in the lamp is reduced, and the rise of the starting voltage and the blackening of the bulb can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a sectional structure of a mercury carrier according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an end portion of the annular fluorescent lamp of the same embodiment.

FIG. 3 is a side view of the annular fluorescent lamp of the same embodiment.

FIG. 4 is a characteristic diagram showing a luminous flux maintenance factor.

[Explanation of symbols]

1 ... Bulb, 2 ... Fluorescent film, 3 ... Stem, 4 ... Exhaust tube, 6 ... Lead wire, 7 ... Filament electrode, 8 ... Mercury carrier, 81 ... Inorganic porous pellet.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Kanemaru 1-7-2 Otemachi, Chiyoda-ku, Tokyo Nomura Kosan Co., Ltd.

Claims (3)

[Claims] 1. A mercury vapor discharge lamp having a bulb filled with a mercury carrier obtained by impregnating inorganic porous pellets with liquid mercury, wherein the inorganic porous pellets have hydroxyl groups (O
A mercury vapor discharge lamp characterized in that it is made of ceramics having a low content of (H group). 2. The mercury vapor discharge lamp according to claim 1, wherein the inorganic porous pellets are made of alumina ceramics having continuous pores. 3. The mercury vapor discharge lamp according to claim 2, wherein the alumina ceramic is made of α-alumina.