JPS594817B2 - How to manufacture fluorescent lamps - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a fluorescent lamp, and more particularly to an improvement in a method for exhausting a fluorescent lamp. The aim is to reduce fluctuations in the amount of mercury vapor and to prevent environmental pollution around the exhaust device due to mercury vapor.

A conventional evacuation process for fluorescent lamps is known as shown in plan view in FIG.

That is, in the exhaust device 1 having a plurality of exhaust heads (not shown) that rotate in a counterclockwise direction, the pulp is connected to the exhaust system via the exhaust pipe at position 2.

As the exhaust head rotates, the air in the pulp starts to be discharged and then enters the heating furnace 3.

The pulp is heated to around 400°C in this heating furnace 3,
Gases such as water, 0°, and CO3 contained in the phosphor coated on the inner wall of the pulp are discharged, and then the pulp leaving the heating furnace 3 enters an electrode treatment device 4.4'.

At this point, electricity is applied to the electrode filaments at both ends of the pulp to heat the carbonate, which is the electrode material, and activate the decomposition.

During this time, for the purpose of quickly discharging gases such as C021 CO and 0° generated from the electrode material, a small amount of mercury particles were dropped into the inner bottom of the pulp in position 5 and vaporized, and the diffusion effect caused the pulp to evaporate. After increasing the degree of vacuum by promoting gas discharge, an appropriate amount of mercury particles are dropped again in position 6.

Next, the pulp is isolated from the exhaust system and filled with an inert gas such as argon gas at the position of the inert gas filling device 1, which is placed following the electrode processing devices 4 and 4'. The exhaust pipe is sealed by the exhaust pipe sealing device 8, and the pulp is taken out from the exhaust device at position 9.

However, in recent years, environmental pollution caused by mercury has begun to attract attention, and it has been realized that this conventional method contains fundamental drawbacks.

In other words, mercury is dripped during the electrode processing equipment, vaporized, and discharged outside the bulb, which ultimately requires 2 to 4 times the amount of mercury needed for the fluorescent lamp, and also reduces the amount of mercury used in the pulp. A huge amount of cost is required to collect the mercury discharged outside from the exhaust system and to install a trap device to prevent mercury vapor from diffusing into the atmosphere from the exhaust system.

Another disadvantage is that the amount of mercury vaporized and discharged outside the valve varies depending on changes such as the temperature of the pulp, the surface area of the mercury particles, the evacuation time, and the resistance of the evacuation system. Some of the mercury vapor condenses on the inner wall of the exhaust pipe, where the temperature is relatively low, and this drops into the valve again due to shocks such as mechanical vibrations, which eventually causes the mercury remaining in the pulp to condense. Amounts varied over a wide range.

Moreover, if a large amount of mercury is used, the appearance of the lamp may be impaired due to a mercury aggregation layer during lighting, or the lamp may not be turned on quickly due to insufficient mercury.

Recently, as a method to compensate for these drawbacks, a mercury supply element such as a capsule made of a mercury alloy, a mercury compound and a getter agent, or glass sealed with mercury is installed near the electrodes in the bulb, and after the evacuation process is completed, the element is supplied with mercury. A method of heating and destroying the mercury and extracting the mercury inside the bulb has begun to be put into practical use.

However, these methods also have drawbacks: firstly, the cost of materials increases due to the provision of mercury supply elements near the electrodes, and secondly, the electrodes with these elements attached have a complicated shape, making it difficult to assemble the fluorescent lamp. This significantly increases the manufacturing cost of the lamp, as it lowers the yield of the process and requires a device to discharge mercury into the bulb after the evacuation process is completed.

Another drawback is that in these exhaust processes, inert gas such as argon is filled in instead of the conventional mercury in order to promote the discharge of impure gas inside the valve, and then the valve is exhausted again. It is necessary to repeat this several times, and in order to create a high vacuum inside the valve, it is necessary to increase the pressure of the above-mentioned inert gas such as argon. There were drawbacks such as the phosphor on the inner wall being prone to peeling off, impairing the appearance.

The present invention was developed in view of the above circumstances, and reduces the amount of mercury handled in the exhaust process without increasing the manufacturing cost of fluorescent lamps, and prevents excess mercury from scattering around the exhaust system. The purpose of the present invention is to provide a method for preventing mercury from occurring and enclosing a fixed amount of mercury within a lamp.

First, to explain the present invention in detail, the thermal decomposition activation treatment of the electrode material is carried out by dividing it into a pre-stage part and a post-stage part of the exhaust process for degassing the inside of the valve.

That is, in the first half of the heating furnace, most of the gases such as Co2aO3 and CO generated during the thermal decomposition of carbonate, which is the electrode material, are discharged together with the gas contained in the phosphor, and the heating After leaving the furnace, the surface of the electrode material, which has mostly become an oxide, is reheated to activate it, allowing the gas inside the valve to be efficiently discharged in a short time. After the pulp exits the heating furnace, when the pulp is cooled, it prevents the gas from being re-adsorbed onto the phosphor, thereby maintaining a good degree of vacuum inside the bulb.

Next, the present invention will be explained with reference to the drawings. Fig. 2 is a plan view of an exhaust system showing an embodiment of the present invention, and the parts indicated by the same numbers as in Fig. 1 are exactly the same as the conventional exhaust system. 10.10' is a first electrode processing device installed in the first half of the interior of the heating furnace 3, that is, in the front stage of the exhaust process.

Further, 4° 4' is a second electrode processing device similar to the conventional one, which is installed at the latter stage of the exhaust process where gas removal from the valve is completed from the terminal end of the heating furnace 3.

In the figure, in position 2 of the exhaust device 1 having a plurality of wiping heads (not shown) rotating in a counterclockwise direction,
The pulp is connected to an exhaust system via an exhaust pipe installed at one end.

Then, by rotating the exhaust head, the air inside the valve starts to be discharged, and then the pulp enters the heating furnace 3, and forced heating from the outside starts. The first electrode treatment device 10, 10' starts supplying electricity to the electrode filaments at both ends of the pulp, and thermal decomposition of the electrode material begins.

However, according to experiments, it is important to start the thermal decomposition of the electrode material after the pressure inside the pulp has been reduced to 4 Torr or less in order to prevent oxidation of the electrode filaments.

As the temperature of the pulp rises, gases such as water, CO2, etc. contained in the phosphor coated on the inner wall of the pulp are released into the pulp, and CO2m is released from the electrodes as the electrode materials such as carbonates are thermally decomposed. Gases such as O3 and CO are released into the pulp, and these gases are simultaneously exhausted out of the pulp by the exhaust system through the exhaust pipe.

The electrode treatment by the first electrode treatment device 10.10' achieves its purpose by converting carbonate into oxides by the time the pulp temperature rises to about 300°C, but heating of the pulp is not continued. 400 to 450°C near the outlet of the heating furnace 3
becomes.

Next, a second electrode processing device 4, 4 connected to the heating furnace 3
When the pulp enters ', the electrode filament is energized again and the electrode material is processed.

This treatment is carried out in the first electrode treatment apparatus 10.10' by heating the electrode material that has changed to zooxide to activate the surface, and until the inert gas filling step described later. This is done to prevent the electrode from adsorbing impure gas again.

Next, at the position of the inert gas filling device 1 which is arranged in series with the second electrode processing device 4, 4', the pulp is cut off from the exhaust system and filled with an inert gas such as argon gas at a pressure of several Torr. The pulp is sealed, and several tens of square meters of mercury are dropped onto the bottom of the pulp by a mercury dropping device installed in the exhaust head through the jet of argon gas during the filling.

Next, the exhaust pipe of the pulp is sealed by the exhaust pipe sealing device 8 disposed following the inert gas filling device 1, and then at position 9, the pulp is taken out from the exhaust device 1 and sent to the next process. Sent.

The evacuation process according to the embodiment having the above configuration and the evacuation process according to the conventional method were compared by tracking and measuring the degree of vacuum inside the pulp.

FIG. 3 shows the degree of vacuum inside the pulp during the evacuation process, with the vertical axis representing the relative value of the vacuum degree and the horizontal axis representing the elapsed time of the evacuation process.

Curve A is for the vertical method, and when the air in the pulp and the gas from the phosphor begin to be discharged from the position A, and the decomposition and activation of the electrode material begins at the mouth position, CO2 from the electrode material begins to flow.
, CO10°, etc. due to the release of gases, the degree of vacuum deteriorates rapidly.

By continuing the evacuation, the degree of vacuum gradually improves, and when mercury is dropped into the pulp at position C, the degree of vacuum rapidly improves due to the diffusion effect caused by its evaporation.

Curve B shows the degree of vacuum inside the pulp according to the present invention, and the exhaust of air and phosphor gas from the pulp starts at the position A, and the first electrode treatment starts at the position E. The degree of vacuum decreases once due to the release of gases such as CO2, C0, 02 from the electrode material, but these gases are discharged out of the pulp along with the gases released from the phosphor, and the degree of vacuum gradually decreases. gets better.

When electrode processing starts again at the mouth position, the degree of vacuum decreases slightly, but it is very small compared to the conventional method, and the degree of vacuum increases immediately, and at position 2, where inert gas is filled, it is better than the conventional method. This indicates that there is little impurity gas remaining in the pulp.

This is almost at the same time that degassing in the pulp begins.
In other words, most of the decomposition gas emitted from the electrode material is discharged in the first stage of the exhaust process, and from the second stage of the exhaust process onwards, degassing continues in a high vacuum area, so the exhaust process ends. By this time, the degree of vacuum was extremely high.

In contrast, in the conventional method in which the first decomposition treatment of the electrode material is performed at the latter stage of the exhaust process, the degree of vacuum inside the bulb, which has been increased over time, is significantly lowered at the latter stage of the exhaust process, resulting in the flushing. Even if exhaust is added to assist the exhaust, the final degree of vacuum will be lower than that of the above embodiments due to the time constraints of the exhaust process.

In addition, in the latter part of the exhaust process, the pulp comes out of the heating furnace 3 and is rapidly cooled, and the degassed phosphor is in a state where it is easy to re-adsorb impurity gas. Since the emission of is extremely small, re-adsorption of impure gases onto the phosphor can also be prevented.

This makes it possible to lower the lighting start voltage of the lamp, and it goes without saying that this also provides good results in terms of appearance deterioration such as lamp blackening during lighting, and characteristics such as residual luminous flux rate.

In the evacuation process according to the above-described embodiment, no mercury particles are dropped into the fluorescent lamp during the gas evacuation from the pulp, meaning that the amount of mercury used is the amount that should ultimately be sealed in the fluorescent lamp. Furthermore, there is no need to perform any gas evacuation operation due to the diffusion effect of mercury vapor during electrode processing, which was performed in the conventional method.

Therefore, the amount of mercury required in the exhaust process is reduced to 25 to 50% of the amount of mercury in the conventional method, and since no mercury vapor is emitted, the exhaust system is not contaminated with mercury vapor, and the exhaust system is not contaminated with mercury vapor. There is no diffusion of mercury vapor from the system into the atmosphere.

Furthermore, the mercury sealed in the lamp is not sealed with the gas exhausted as in the past, but is sealed simultaneously with an inert gas such as argon, and is sealed in a jet of this inert gas. Since the mercury is sealed in the lamp very easily and reliably, and the exhaust pipe is sealed immediately after the mercury is filled, it does not evaporate outside the lamp. can be obtained.

This eliminates the problem of deterioration in lamp characteristics due to excess or deficiency in the amount of mercury sealed.

Next, a 40 watt fluorescent lamp was fabricated by applying the evacuation process of the embodiment described above, and compared with a conventional 40 watt fluorescent lamp, the following effects were confirmed.

1 at random from the lamps produced in large quantities according to the example.
When 00 lamps were extruded and the amount of mercury sealed in the lamp was measured, the standard deviation, which shows variation from the average value of 22 cm, was 1.6.

In the lamps manufactured by the conventional method, the standard deviation was 6 to 7, so it was confirmed that fluctuations in the amount of mercury could be significantly reduced.

In addition, after producing lamps for a certain period of time, the amount of mercury recovered from inside equipment such as exhaust equipment piping and vacuum pumps was 40 to 50 times less than in the case of conventional methods, and the equipment was contaminated with mercury. It was confirmed that there were significantly fewer

As explained above, in the present invention, the thermal decomposition activation treatment of the electrode material deposited on the electrode is performed separately in the front stage and the rear stage of the exhaust process for degassing the pulp. This makes it possible to obtain a fluorescent lamp with good characteristics and less fluctuation in the amount of mercury without making major changes to conventional equipment or increasing lamp manufacturing costs.Furthermore, it reduces contamination of the equipment with mercury and improves the working environment. This contributes to the improvement of

[Brief explanation of the drawing]

Figure 1 is a plan view illustrating a conventional exhaust system, and Figure 2 is a
FIG. 3 is a plan view showing the evacuation apparatus for explaining the method of the present invention, and a drawing showing the transition of the degree of vacuum of the lamp during the evacuation process. 1 is an exhaust device, 2 is a pulp mounting position, 3 is a heating furnace, 4.4' and 10, 10' are electrode processing devices, 5 and 6
1 is the mercury dripping position, 1 is the inert gas filling device, 8 is the exhaust pipe sealing device, and 9 is the pulp extraction position.

Claims (1)

[Claims] 1. A method for venting gas inside a pulp for a fluorescent lamp having a phosphor coated on the inner surface, an electrode provided at the inner end, and an exhaust pipe through the exhaust pipe. an evacuation step to be carried out, a step of enclosing an inert gas at a predetermined pressure into the pulp after the evacuation step, a step of enclosing a predetermined amount of mercury into the pulp, and a step after enclosing the inert gas and mercury into the pulp. and a step of sealing the exhaust pipe, and an electrode treatment step is provided in which the electrode material deposited on the electrode is subjected to thermal decomposition activation treatment in a pre-stage part and a post-stage part of the evacuation process. A method for manufacturing a fluorescent lamp. 2 The start of the electrode treatment process in the first stage of the exhaust process is as follows:
The pressure inside the pulp is 4 torr or less, the end of the electrode treatment process in the first stage of the evacuation process is done at a point where the temperature of the pulp does not exceed 300°C, and the electrode treatment process in the latter part of the exhaust process The process is started after the temperature is heated to the maximum temperature, and the mercury is encapsulated in the pulp only after the electrode treatment process in the latter part of the exhaust process is completed, and the mercury is not encapsulated. 2. The method for manufacturing a fluorescent lamp according to claim 1, characterized in that the process is carried out through a jet of active gas.