JPS6220656B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a fluorescent lamp, particularly to an improvement in a method for thermally decomposing an electron-emitting substance in an evacuation process.

Recently, bulbs have been developed as a method for thermally decomposing electron-emitting materials (hereinafter referred to as electrode materials) made of composite carbonates of alkaline earth metals including barium carbonate (BaCO ₃ ) deposited on the electrodes of fluorescent lamps. When it is installed on an exhaust stand and the exhaust inside the valve starts, the first thermal decomposition is performed while the valve is heated to nearly 300℃ in the heating furnace, and the valve reaches its maximum temperature in the heating furnace. JP-A-53-9082 proposed a method in which the electrode material is heated again after being heated to perform a second thermal decomposition. This device is designed to release most of the decomposed gas released by the decomposition of the electrode material during the first thermal decomposition, and is effective in shortening the exhaust time.

However, in the above method, in the first decomposition of the electrode material, in order to avoid the influence of impure gas in the bulb, the pressure of impure gas in the bulb is reduced to several torr, and the impurity gas is deposited on the inner surface of the bulb. This is done for a very limited period of time until the bulb is heated to 250-300°C, when gas release from the phosphor is relatively low, so the hot electrode material is exposed to the high pressure of the decomposition gas released by itself. By the way, it is further thermally decomposed, and as a result, some of the electrode materials, e.g.
BaCO ₃ forms a solid solution such as BaOBaCO ₃ or BaxWOy, which is produced by the reaction of BaCO ₃ with the tungsten filament coil of the electrode.
It had the disadvantage of producing a large amount of intermediate layer compounds as shown in the figure below. This solid solution, expressed as BaOBaCO ₃ , sinteres the surface of the electrode material, which prevents the second decomposition of the electrode material and reduces the electron radioactivity of the electrode material after it is turned into a product.
Further, the intermediate layer compound causes oxygen gas to be emitted into the bulb during lighting, impairing the blackening properties and the like. For this reason, during the first decomposition of the electrode material, it was not possible to raise the temperature of the electrode to the desired heating temperature, and it was not always possible to obtain a satisfactory decomposition schedule.

The present invention has been made in view of the above circumstances, and is designed to stop energization heating at an intermediate position among a plurality of energization positions for energizing the electrode during thermal decomposition of the electrode material performed in the first stage of the bulb heating process. , the heating of the one-carrying electrode material is interrupted, and during this time flash exhaust is performed using an inert gas, and the electrode material is heated to the maximum temperature by applying electricity immediately after the heating is interrupted, thereby preventing sintering of the electrode material, Another object of the present invention is to provide a method for manufacturing a fluorescent lamp, which can appropriately generate an intermediate layer compound, improve lamp characteristics, and shorten evacuation time.

The details of this invention will be explained below with reference to the drawings. Figure 1 shows the state of the exhaust schedule after the valve is attached to the exhaust stand. The horizontal axis of the figure is the exhaust time, 1 on the vertical axis is the exhaust process, 2 is the valve heating process, and A is the valve temperature. represents the point at 300℃, and b represents the point heated to the highest temperature.
Further, C indicates the front stage of this valve heating step 2, and D also indicates the rear stage. 3 is a flash exhaust process in which argon gas is injected into the valve and exhausted again; 4 is a thermal decomposition process of the electrode material; the first decomposition process 41 is carried out in the first stage C of the above-mentioned valve heating process 2, and the subsequent stages are the subsequent stages. and a second decomposition step 42 carried out in the first decomposition step 4.
In the middle of 1, there is a decomposition stop part 4b that interrupts the heating.
have. Reference numeral 5 is a filler filling step in which a predetermined amount of argon gas and mercury are sealed in the valve, and 6 is a tip-off step in which the exhaust pipe is melted.

Next, one embodiment of the present invention will be described. First, attach the valve to the exhaust stand. Next, when the pressure of the impure gas inside the valve is reduced to 4 Torr by the exhaust step 1 in which the inside of the valve is evacuated, thermal decomposition of the electrode material is started in the first decomposition step 41.
At this time, in the first heating position 4a, the electrode material is thermally decomposed at a heating temperature of 70 to 80% of the maximum temperature at which the electrode material is thermally decomposed. Next, the thermal decomposition of the electrode material is interrupted in the decomposition stop section 4b, and immediately a flash exhaust step 3 is performed in which several torr of argon gas is injected into the valve and exhausted again. After this, the electrode material is thermally decomposed again, but the highest heating temperature is set at position 4c. In this case, the change in impure gas pressure within the valve becomes as shown in A of FIG. In other words, the pressure of the decomposed gas released in the first thermal decomposition 4a is such that the next position is the decomposition stop part 4.
B, the electrode material is not decomposed, and the heating temperature is set to 70 to 80% of the maximum temperature, so compared to the conventional schedule B in which thermal decomposition is performed continuously, the heating temperature is about 80%. It can be suppressed. Furthermore, when flush exhaust 3 is performed using argon gas, the apparent pressure inside the valve draws a high pressure curve as shown by the chain line C. However, since impure gases such as cracked gas are discharged outside when the pumping speed of the vacuum pump is high, even if the maximum thermal decomposition temperature is set immediately after flash pumping 3, the impure gas pressure inside the valve will remain the same as before. It doesn't increase. Next, valve heating step 2
After heating and degassing the phosphor deposited inside the bulb, a second decomposition step 42 is carried out as in the conventional method.
At the same time, flash evacuation is performed during the second decomposition step 42, and then mercury and argon gas are filled in the filler filling step 5, and after a tip-off step 6, the evacuation treatment step is completed.

According to such an evacuation step, the impure gas pressure inside the valve during the first decomposition step 41 can be kept low;
Even if the electrode material is thermally decomposed at the highest decomposition temperature, not only will the electrode material not be sintered, but it can also be prevented from producing an excessive amount of the intermediate layer compound.
Therefore, a fluorescent lamp with good lamp characteristics can be obtained. In addition, since the electrode material does not need to be heated to the maximum temperature in the second decomposition step 42, the pressure of decomposed gas from the electrode material released during the second decomposition step 42 can be lowered, and the exhaust time can be further shortened. .

Note that the decomposition stop part 4b is a pre-stage part 41 of the decomposition process.
By providing it midway, the decomposed gas of the electrode material can be efficiently exhausted by entangling it with the flash exhaust, and even in the front stage 41, at the beginning and end, the pressure of impure gas including the decomposed gas of the electrode material in the valve is reduced. The effect of reducing this is small.

The inventors believe that the lamp of this invention is significantly more effective than conventional methods in reducing lamp starting characteristics, which had been a problem in the past, and in preventing blackening of the edges (yellow band), which rapidly develops after 2,000 hours of lighting. I confirmed that there is.

As explained above, in the present invention, when decomposing an electrode material through a plurality of energized heating positions performed in the first stage of the bulb heating process, the heating is temporarily stopped in the middle of the decomposition, and during this period, flash exhaust is performed, Furthermore, since the electrode material is heated to the maximum temperature at the heating electrode position immediately after the heating stop section, sintering of the electrode material and excessive generation of intermediate layer compounds can be prevented.
A fluorescent lamp with improved lamp characteristics can be provided. Furthermore, since it is not necessary to increase the pressure of the cracked gas released during the decomposition process after the latter part of the valve heating process, there is also an effect that the exhaust time can be further shortened.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a time schedule of an embodiment of the present invention, and FIG. 2 is a diagram showing changes in impure gas pressure within a valve. 1 is an exhaust process, 2 is a valve heating process, 3 is a flash exhaust process, 4 is an electrode material thermal decomposition process, 4
b is a decomposition stop part. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. The electrodes are sequentially energized and heated to decompose the electrode material using a plurality of energization heating positions that are installed separately in the front and rear stages of the valve heating process in which the bulb is heated while the inside of the bulb is evacuated. In the method for manufacturing a fluorescent lamp, an intermediate position of the energization heating position disposed at the front stage of the bulb heating process is used as a decomposition stop section where the energization heating is temporarily stopped, and in this decomposition stop section, flash exhaust by inert gas is performed. A method for manufacturing a fluorescent lamp, characterized in that the electrode material is heated to a maximum temperature in an energized heating position immediately after the flash exhaust.