JPS6147057A - Low pressure mercury vapor discharge lamp - Google Patents

Abstract

PURPOSE:To accurately prevent an anode side from becoming dark due to insufficient mercury when lighting a low pressure mercury vapor discharge lamp using direct current by adsorbing intra-tube mercury within a luminous tube at lighting off and providing amalgam that emits mercury during lighting, on the anode side of the a luminous tube. CONSTITUTION:When lighting a low pressure mercury vapor discharge lamp using direct current, the mercury discharged in a luminous tube 1 changes into + ion, the mercury is drawn slowly to a preheating cathode 7 side that is a -side. As a result, the amount of mercury on an anode 6 side is reduced sharply and the mercury vapor pressure on the anode 6 side starts decreasing. In this case, since amalgam 9 is housed in the capillary 8 on the anode 6 side, the amount of mercury corresponding to the reduction is discharged from the amalgam 9 and mercury is resupplied in the vicinity of the anode 6. As a result, since the inner part of the luminous tube 1 is kept in a state where mercury is discharged almost equally in appearance, a cataphoresis event in which the anode 6 side becomes dark is prevented.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a low-pressure mercury vapor discharge lamp operated with direct current.

[Technical background of the invention and its problems]

In general, when low-pressure mercury vapor discharge lamps, such as fluorescent lamps, are lit with direct current, electrode loss is kept to a minimum compared to when lit with alternating current, the luminous efficiency with respect to the lamp input is increased, and flickering is reduced. There are advantages.

On the other hand, in the case of direct current lighting, the mercury atoms inside the tube become positive ions, so much of the mercury vapor sealed inside the tube is drawn toward the cathode, and as a result, the mercury on the anode side is significantly reduced. There is a problem that the anode side becomes dark over time after lighting (a so-called cataphoresis phenomenon occurs).

(Object of the invention) The present invention was made based on the above circumstances, and
When direct current is lit, I! To provide a low-pressure mercury vapor discharge lamp which can reliably prevent darkness due to lack of mercury on the 1tffi side and can also eliminate uneven brightness.

[Summary of the invention]

That is, in order to achieve the above object, the present invention installs an amalgam on the R pole side of the arc tube, which adsorbs mercury in the tube when the light is off and releases mercury when the light is on. It is characterized by the fact that the amount of mercury is supplied from the amalgam.

[Embodiments of the invention]

A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, reference numeral 1 denotes a straight arc tube made of soft glass, and the inner surface of this arc tube 1 is coated with a phosphor coating 2. As shown in FIG. Mounts 3a and 3b are sealed to both ends of the arc tube 1, and the stem tube 4a of one mount 3a has internal leads Ii5. A coiled filament-shaped anode 6 is connected to the stem tube 4b of the other mount 3b via internal lead wires 5.-, 5.
A preheated cathode 7 in the form of a coiled filament is connected via the wire 5 . In addition, inside the arc tube 1, there are stem tubes 4a and 4b.
is exhausted through a capillary tube 8 extending outward from the
An inert gas as an ionizable medium is sealed through this thin tube 8, and after that, the thin tube 8 is hermetically sealed by melting. In the thin tube 8 on the side of the anode 6, an amalgam 9 is housed for controlling the mercury vapor pressure inside the tube during steady lighting. This amalgam 9 is made of, for example, an alloy of bismuth (B + > and indium (In)) and mercury (Hg).
) is used, and when the lamp is on, mercury is released into the arc tube 1 under the influence of heat from the anode 6, and when the lamp is off, it adsorbs floating mercury inside the tube. . Note that instead of the amalgam 9, the amalgam-forming metal and mercury are first separated into the capillary tube 8 and the arc tube 1.
Alternatively, the amalgam-forming metal may be encapsulated in the thin tube 8 and then amalgamated in the thin tube 8.

Further, in the case of this embodiment, a small volume of auxiliary amalgam 10.10 is installed near the anode 6 and the cathode 7. Although not shown in detail, the auxiliary amalgam 10.10 is made by depositing an amalgam-forming metal such as indium on the surface of a metal substrate such as nickel in a III-shape, and is supported by the internal lead wire 5. Then, such auxiliary amalgam 10°10 is used to protect the arc tube 1 as when the light is turned off.
When the temperature inside the tube is low, it adsorbs floating mercury inside the tube, and when the lamp is turned on, the adsorbed mercury is released into the arc tube 1 due to the ion bombardment caused by the discharge and the thermal influence from the poles 6.7. ing.

In a low-pressure mercury vapor discharge lamp having such a structure, both poles 6, 7 are connected to an alternating current voltage [13] via a circuit 20 as shown in FIG. 2, for example. That is, one end of both poles 6.7 is connected to an AC power source 13 via a capacitor 11 and a rectifier bridge circuit 12, and a resistance ballast as a current reducing element is connected between the rectifier bridge circuit 12 and the anode 6. 14 are connected. A primary winding 17 of a pulse transformer 16 is connected between the other ends of the two poles 6.1 via a lighting tube 15.
The secondary winding 18 is connected to a proximal conductor 19 attached to the tube wall of the arc tube 1. Therefore, the output voltage of AC 1fl13 is converted to DC by the rectifier bridge circuit 12 and outputted, and when this DC voltage is applied to both poles 6.7 via the capacitor 11 and the resistor ballast 14,
A current change caused by the lighting tube 15 is converted into a high voltage pulse by a pulse transformer 16 and applied to the wall of the arc tube 1. As a result, a glow discharge is generated within the arc tube 1, and DC lighting is started.

By the way, when lighting is started in this manner, first the auxiliary amalgam 10.10 close to the bipolar pole 6.7 is connected to the bipolar pole 6.7.
In addition to being affected by heat from the arc tube 7, the temperature rapidly rises due to the impact of ions caused by the discharge, and mercury is actively released into the arc tube 1. Therefore, a sufficient amount of mercury is supplied into the arc tube 1 within a short period of time, resulting in a good rise in light output.

As the temperature of the wall of the arc tube 1 rises due to the above-mentioned discharge, the temperature of the amalgam 9 in the capillary tube 8 gradually rises, and an amount of mercury corresponding to this temperature passes through the opening of the capillary tube 8 and enters the arc tube. released within.

After the light output reaches the steady lighting state, the mercury vapor pressure inside the tube is controlled to a vapor pressure determined by the temperature of the part where the amalgam 9 is installed.

On the other hand, when a low-pressure mercury vapor discharge lamp is lit with direct current, the mercury released into the arc tube 1 becomes + ions, so they are gradually drawn toward the negative side of the preheated cathode 1. As a result, the amount of mercury on the anode 6 side is significantly reduced,
The mercury vapor pressure on the anode 6 side begins to decrease. In this case, since the amalgam 9 is housed in the thin tube 8 on the anode 6 side, when the mercury vapor pressure starts to decrease as described above, an amount of mercury corresponding to the decrease is released from the amalgam 9. Mercury is supplied near the anode 6. Therefore, the mercury is apparently maintained in a state in which mercury is released almost evenly inside the light tube 1, so the cataphoresis phenomenon in which the anode 6 side becomes dark is prevented, and as a result, there is no reduction in brightness or unevenness. The entire arc tube 1 emits light evenly.

According to lighting tests conducted by the present inventor, in conventional low-pressure mercury vapor discharge lamps, a cataphoresis phenomenon occurred approximately 30 minutes after lighting started. In the low-pressure mercury vapor discharge lamp equipped with the amalgam 9, no cataphoresis phenomenon occurred even after 10 hours or more had elapsed after lighting started, and the imbalance of mercury in the arc tube 1 was prevented by the release of mercury from the amalgam 9. It became clear that there was.

Note that when a low-pressure mercury vapor discharge lamp in the operating state as described above is turned off, a large amount of mercury is concentrated on the preheated cathode 7 side, but as the temperature of the arc tube 1 and the amalgam installation part decreases, The floating mercury in 1 gradually begins to be adsorbed by the amalgam 9 and the auxiliary amalgam 10. At this time, since the capacity of the auxiliary amalgam 10°10 is small, most of the floating mercury in the arc tube 1 will be adsorbed by the amalgam 9 on the anode 6 side, thus returning to the same state as before starting lighting. When the light is turned on again, the same operation as above is repeated.

Note that the present invention is not limited to the first embodiment described above, and FIG. 3 shows a second embodiment of the present invention.

In this second embodiment, the arc tube 3 is bent into a roughly saddle shape.
1 is housed in an incandescent bulb-shaped envelope 33 equipped with a cap 32 together with the rotary rli 20 of the first embodiment, and applied to an incandescent fluorescent lamp that can be used in place of an existing incandescent bulb. As shown by am in FIG. 2, the base 32 is connected to the input side of the rectifying bridge circuit 12. In this second embodiment, a small incandescent light bulb is used as the resistance ballast 14.

According to the second embodiment, in the case of direct current lighting, the circuit 20 is made smaller, so the weight of the entire valve device can be reduced, and there is no flickering, so it can be used in place of an incandescent light bulb. It will be convenient for those who do.

Further, in the above-described embodiments, the amalgam is housed in the thin tube, but depending on the case, it may be installed on the tube wall of the stem tube, and the structure of the cathode does not have to be of the preheating type.

Roughly speaking, the present invention relates to a low-pressure mercury vapor discharge lamp disclosed in Japanese Patent Application Laid-Open No. 44-44370, in which an inner tube as a discharge path regulator is provided in an outer tube filled with mercury or an inert gas. It can also be applied to the case where a low-pressure mercury vapor discharge lamp, so-called a so-called separated inner tube method, is lit with direct current. , an inner tube is provided as a discharge path regulating body so that a plurality of discharge paths are formed within the outer tube, one cathode is provided within the inner tube, and a plurality of anodes are provided within the outer tube and outside the inner tube. It can also be applied to DC discharge lamps equipped with That is, the structure of the low-pressure mercury vapor discharge lamp according to the present invention is not specified as long as it is lit with direct current.

(Effects of the Invention) According to the present invention described in detail above, when the mercury vapor pressure on the anode side begins to decrease during lighting, mercury in an amount corresponding to the decrease is released from the amalgam and is distributed near the Fi electrode. Since mercury is replenished, the appearance of mercury being released almost evenly inside the light tube is maintained, and therefore the cataphoresis phenomenon in which the anode side becomes dark over time is prevented, and the mercury is released over a long period of time. This has the advantage that the entire arc tube can emit bright and even light over the entire arc.

[Brief explanation of the drawing]

1 and 2 show a first embodiment of the present invention;
The figure is a sectional view, FIG. 2 is a circuit diagram, and FIG. 3 is a sectional view showing a second embodiment of the present invention. 1... Arc tube, 6... Anode, 7... Preheated cathode, 9
···amalgam.

Claims (1)

[Scope of Claims] The arc tube is equipped with an arc tube in which an ionizable medium containing a predetermined amount of mercury is sealed, and an anode and a preheated cathode provided in the arc tube, and a DC voltage is applied between the two electrodes. A low-pressure mercury vapor discharge lamp that is lit with direct current, characterized in that an amalgam is installed on the anode side of the arc tube to adsorb mercury in the tube when the lamp is turned off, and to release mercury when the lamp is turned on. .