JPH0468741B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a low-pressure mercury vapor discharge lamp in which the mercury vapor pressure inside the tube is controlled by an amalgam.

[Technical background of the invention and its problems]

In general, in low-pressure mercury vapor discharge lamps such as fluorescent lamps, the efficiency of converting supplied electricity into ultraviolet light is low when the tube wall temperature is around 40°C and the mercury vapor pressure is approximately 6 × 10 ^-3 mmHg. The lamp ambient temperature at this time is approximately 20-25℃.
It is said that Therefore, when the ambient temperature significantly exceeds this value, the conversion efficiency of ultraviolet rays deteriorates rapidly, causing problems such as a decrease in light output.

By the way, in recent years, as the output of fluorescent lamps has increased and they have been used in closed lighting equipment, the operating temperature of fluorescent lamps may become higher, so the ambient temperature of the fluorescent lamp may exceed the above value. There are many opportunities for this, and the problem is that the light output and ultraviolet conversion efficiency decrease.

When a fluorescent lamp is operated under such severe temperature conditions, a method is used to control the mercury vapor pressure within the fluorescent lamp within an appropriate range using an amalgam.

However, this method uses the property that the vapor pressure of amalgam is lower than that of pure mercury to control the mercury vapor pressure. If the ambient temperature of the light lamp is low, the temperature of the amalgam will be slow to reach the temperature most desirable for its operation, and the rate of release of mercury will be slow. Therefore, there arises a problem that the rise of the optical output is slow and it takes a long time until it stabilizes to a steady state.

For this reason, conventionally, for example,
As shown in Publication No. 30387, in addition to the main amalgam that controls mercury vapor pressure during steady lighting, mercury vapor is temporarily released at the initial stage of lighting, including when starting, and when the lights are turned off, floating mercury in the tube is released. It is known that a small amount of auxiliary amalgam that adsorbs light is placed in a high-temperature part near the electrode to improve the rise characteristics of optical output.

This prior art auxiliary amalgam is configured to release mercury only upon receiving heat from the electrode, but to increase the rate of mercury release, the inventors have combined the auxiliary amalgam with an electrode and an electric current. The idea was to make the auxiliary amalgam itself function as an electrode by connecting it to the same potential. In this way, the auxiliary amalgam is subjected to ion bombardment by the discharge in addition to the radiant heat from the electrodes, so the temperature rises rapidly compared to that of the prior art, and as a result, mercury is actively released. It has become clear that the optical output rises more quickly.

However, if the auxiliary amalgam is electrically connected to the electrode, ion bombardment will continue even after the lamp starts, so if indium, which has a low melting point, is used as the auxiliary amalgam, it will be severely consumed by spatter, and this will cause the auxiliary amalgam to be There is a problem that the amalgam has a short lifespan and the rise of the optical output deteriorates as the number of blinks increases.

[Purpose of the invention]

The present invention was developed based on these circumstances, and the rise of the light output upon relighting is almost instantaneous, and the rise characteristics can be greatly improved, and the consumption of the auxiliary amalgam is small, so it can be used for a long period of time. The object of the present invention is to provide a low-pressure mercury vapor discharge lamp that can maintain stable startup characteristics over a long period of time.

[Summary of the invention]

That is, as a result of various experiments, the present inventors discovered that among metals that have a mercury adsorption effect, aluminum is particularly resistant to spatter, and a thin film of this aluminum was deposited on the surface of a substrate. .

[Embodiments of the invention]

The present invention will be explained below based on an embodiment shown in the drawings.

In the figure, 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 into the opening at the other end of the cover 1, and the cover 1 and the globe 3 constitute an envelope 4 that approximates a ball-shaped incandescent light bulb. .

Inside the envelope 4, a fluorescent lamp 5, which is a typical low-pressure mercury vapor discharge lamp, a lighting tube 6 as a starting element of the fluorescent lamp 5, and a chiyoke coil type ballast 7 as a discharge stabilizing element are integrated. is accommodated. The luminous tube 8 of the fluorescent lamp 5 is made by bending a straight glass bulb into a substantially U-shape at the center between the two ends 9, 9, and the curved part 10 and the two ends 9, 9. The space between the two ends is curved into a substantially U-shape in a direction substantially orthogonal to the plane containing the U-shape, and both end portions 9, 9 and the curved portion 10 are located adjacent to each other in the same direction. A phosphor coating 12 is coated on the inner surface of the arc tube 8, and flare portions 14 of a mount 13 are sealed to both ends 9, as shown in FIG. Internal lead wires 16, 16 are sealed in the stem tube 15 connected to the flared portion 14, and a filament 17 as an electrode is inserted between these internal lead wires 16, 16.
is connected. Further, a capillary tube 18 led out from each mount 13 is opened at the tip of the stem tube 15 close to the filament 17, and through this capillary tube 18, exhaust gas inside the arc tube 8 and inert gas as an ionizable medium are discharged. Encapsulation takes place.

The fluorescent lamp 5 is housed in the envelope 4 with both ends 9 and the curved part 10 facing the base 2, and the filament 17 is placed in the lighting tube 6. Of course, it is connected to the base 2 via the stabilizer 7.

Incidentally, an amalgam 19 is housed in the thin tube 18 located closer to the tube end than the filament 17. In this case, amalgam 19
Alternatively, the amalgam-forming metal and mercury may first be separately sealed in the capillary tube 18 and the arc tube 8, and then the amalgam-forming metal may be amalgamated within the capillary tube 18.

The amalgam 19 is for controlling the mercury vapor pressure inside the tube during steady lighting, and in the case of this embodiment, it is made of indium (In), bismuth (Bi), tin (Sn), lead (Pb), and these. Mercury (Hg) is added to an alloy made by mixing various metals in appropriate proportions.

Also, filament 17 is better than amalgam 19.
A mercury getter 20 is installed in a high-temperature part close to the filament 17, that is, in this embodiment, located between the filament 17 and the open end of the thin tube 18. The mercury getter 20 is made by pressing aluminum with a thickness of, for example, 5 μm onto the surface of a heat-resistant base 21 such as a metal plate such as nickel, iron, or stainless steel or a ceramic plate. covered by. The base body 21 of the mercury getter 20 is welded to one of the internal lead wires 16, and this welding establishes electrical continuity between the filament 17 and the mercury getter 20. Such a mercury getter 20 adsorbs floating mercury inside the arc tube 8 when the temperature inside the arc tube 8 is low, such as when the lamp is turned off, and conversely releases the adsorbed mercury into the tube when the lamp is turned on. .

In such a configuration, when the cap 2 is inserted into the socket on the power supply side and the power supply voltage is applied to the arc tube 8 to start it, a trace amount of mercury vapor and inert gas remaining in the arc tube 8 will be released. A discharge is started between the filaments 17, 17. At this time, since mercury has not yet been adsorbed to the mercury getter 20 in the lamp immediately after manufacture, as the temperature of the wall of the arc tube 8 increases due to the discharge, the temperature of the amalgam 19 in the thin tube 18 gradually increases. An amount of mercury vapor corresponding to this temperature passes through the thin tube 18 to the arc tube 8.
released within. After the optical output reaches a steady state, the mercury vapor pressure inside the tube is controlled to a vapor pressure determined by the temperature of the part where the amalgam 19 is installed.

On the other hand, when the fluorescent lamp 5 in such an operating state is turned off, the arc tube 8 and the amalgam 1
As the temperature of the installation portion of arc tube 9 decreases, floating mercury within arc tube 8 begins to be adsorbed by amalgam 19 within capillary tube 18 . In this case, since the opening of the capillary tube 18 is relatively small, the rate at which the amalgam 19 adsorbs floating mercury is slow, and this floating mercury flows toward the opening of the capillary tube 18, so the mercury getter 20 located near the opening will adsorb most of the above floating mercury.

Therefore, when the fluorescent lamp 5 is restarted by applying a power supply voltage to the arc tube 8 after being turned off, the mercury getter 20 that has absorbed the mercury is thermally affected by the adjacent filament 17, and this mercury Since the getter 20 itself is electrically connected to the filament 17 and functions as an electrode, it is bombarded with ions due to discharge. As a result, mercury getta 20
Since the temperature of the lamp rapidly rises and mercury is actively released, a sufficient amount of mercury is supplied into the arc tube 8 within a short period of time, and the light output can be increased almost instantaneously.

By the way, there are many known mercury adsorbing metals used in the above-mentioned mercury getter 20, such as copper (Cu), aluminum (Al), silver (Ag), and gold (Au). As a result of various experiments, they found that among the above metals, aluminum is particularly resistant to ion spatter. Therefore, the present inventors proposed that in the above-described fluorescent lamp 5, the aluminum thin film 22 applied to the base 21
The thickness of the lamp was varied within the range of 100μ to 0.5μ, and each lamp was blinked 5000 times, then 30 seconds after restarting.
When we examined the light output after seconds had elapsed, we found that the 6th
The results shown in the figure were obtained. The light output in this lighting experiment was evaluated as a relative value when the light output during steady lighting was taken as 100%, and as is clear from FIG. 6, the thickness of the aluminum thin film 22 was approximately 0.5%. μ
It was found that within the range of ~20μ, more than 70% of the light output during steady lighting could be obtained 30 seconds after startup. When we investigated the reason for this, we found that
As mentioned above, aluminum is resistant to ion spatter, so it is presumed that this is because the amount of thin film 22 deposited is small, that is, even if the film thickness is thin, wear is suppressed to a small extent, making it ideal for its mercury adsorption and release effects. It is considered that the film thickness is within the above range. By the way, when we investigated the rise characteristics when brass steel, nickel, and stainless steel were used instead of aluminum, we found that the middle lines A, B, and C in Figure 6 above
As shown in this order, the light output 30 seconds after startup is low, about 30% of that of steady lighting.
It turns out that it cannot be put to practical use.

In general, aluminum easily combines with oxygen and forms an oxide film of alumite on its surface. Therefore, until this oxide film is removed by the ion sputter, the mercury adsorption capacity may be slightly reduced. Therefore, in carrying out the present invention, it is necessary to prevent the mercury adsorption capacity from decreasing. In order to compensate for this, it is desirable to further deposit a small amount of indium thin film 23 on the surface of aluminum thin film 22 as shown in FIG. As a result of experiments conducted by the present inventors, the indium thin film 23
It has been found that the most desirable film thickness is approximately 3μ to 0.1μ.

According to the configuration described above, since the mercury getter 20 is subjected to ion bombardment in addition to the thermal influence from the filament 17, the adsorbed mercury is quickly released into the arc tube 8, so that the rise of the optical output is substantially reduced. This is done instantaneously, and the rise characteristics can be greatly improved. Furthermore, since aluminum is resistant to ion spatter, there is little wear and tear, and the original function of the mercury getter can be maintained satisfactorily until the end of the lamp's life.

In the above embodiment, the base of the mercury getter is directly welded to the internal lead wire, but it may be electrically connected to the electrode only at the time of starting, for example, via a bimetal or a shape memory alloy.

Furthermore, the low-pressure mercury vapor discharge lamp according to the present invention is not limited to one that is housed in a bulb-shaped envelope and used for lighting, but can also be used externally such as a high-output straight or curved fluorescent lamp. It can be similarly applied as a light source for a copying machine that is lit by direct exposure to the side, or a light source for a copier that blinks frequently.

〔Effect of the invention〕

According to the present invention described above, since the mercury getter is subjected to ion bombardment in addition to the thermal influence from the electrodes, the adsorbed mercury is quickly released into the arc tube.
Therefore, the optical output rises almost instantaneously,
The rise characteristics can be significantly improved. Moreover, since aluminum is resistant to ion spatter, there is less wear and tear, and there is an advantage that the original function of the mercury getter can be maintained satisfactorily until the end of the lamp's life.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is an overall sectional view, FIG. 2 is a partially sectional perspective view of a fluorescent lamp, FIG. 3 is a sectional view of a tube end, and FIG. FIG. 5 is a cross-sectional view of the mercury getter, and FIG. 6 is a rise characteristic diagram of the optical output. 8... Arc tube, 17... Electrode (filament),
19...Amalgam, 20...Mercury goose, 21
. . . Substrate, 22 . . . Aluminum thin film.

Claims (1)

[Scope of Claims] 1. In an arc tube having electrodes at both ends and enclosing an ionizable medium containing a predetermined amount of mercury, the mercury inside the tube is located closer to the end of the tube than the electrodes, and the mercury inside the tube during steady lighting. A low-pressure mercury vapor discharge lamp is provided with an amalgam for controlling vapor pressure, and a mercury getter that is located in a higher temperature part near the electrode than the amalgam and adsorbs floating mercury in the arc tube when the light is turned off, the mercury getter A low-pressure mercury vapor discharge lamp, characterized in that it consists of a base body with a thin aluminum film coated on its surface, and is electrically connected to the electrodes at least during startup. 2 The thickness of the aluminum thin film above is 20μ to 0.5μ.
A low-pressure mercury vapor discharge lamp according to claim 1, characterized in that the lamp is defined within the range of . 3. The low-pressure mercury vapor discharge lamp according to claim 1 or 2, characterized in that a thin indium film is superimposed on the surface of the aluminum thin film.