JPS6057176B2 - Cathode ray tube manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a color picture tube, and particularly to a heat treatment step.

In general, a color picture tube is composed of a glass envelope consisting of a panel section, a funnel section, and a neck section, and the inside thereof is evacuated to a high vacuum.

The inner surface of the face plate of the panel section is coated with regularly arranged phosphors that emit light in two or more colors, and a color selection electrode having a large number of holes is arranged at a predetermined distance from the phosphors. There is. The neck also houses an electron gun that fires multiple electron beams. Usually, a color picture tube having such a structure is subjected to heat treatment several times during its manufacturing process for various reasons as described below. (1) Since various organic materials (for example, PVA, acrylic solution) are used when applying the phosphor and as a base for the metal back, it is necessary to thermally decompose and remove these materials.

(2) Since the manufacturing method for color picture tubes is complicated, the panel and funnel parts are processed separately, and then they are bonded together using solder glass (also called frit glass, hereinafter referred to as low-melting glass) by heating. What you need to do.

(3) When sealing the electron gun in the neck part, it is necessary to melt and weld a part of the neck part.

(4) In order to release the gas adsorbed on the inner wall of the glass as the envelope and other parts such as the shadow mask, the inside of the envelope is heated while being evacuated to a high vacuum. exhaust. What you need to do.

In these plurality of heat treatment steps, if heating and cooling are performed too rapidly, local distortion will occur within the glass, resulting in damage to the glass due to internal stress.

On the other hand, the envelope of the color picture tube! The constituent glass is thick and weighs 5 to 20 kilograms, so it has a large heat capacity. Therefore, in order to perform the heat treatment while suppressing the strain within the glass to the extent that the glass is not damaged, it is necessary to raise and lower the temperature extremely slowly. For this reason, some of the longer heat treatment steps, such as the top and various heat treatment steps, require as long as 4 to 5 hours. In addition, the maximum temperature of various heating processes is 400℃, except for the electron gun sealing process.
The temperature is around 0C, and the cost of energy (gas/electricity), tap water, etc. consumed by a furnace capable of heating to such high temperatures is extremely high, and is a major obstacle to reducing manufacturing costs. ing. Furthermore, as mentioned above, the rate of temperature rise and fall is slow, so the index of the production line is slow, and it is necessary to add several furnaces for mass production, and these capital investments cause increased production costs. At the same time, the amount of energy and tap water used also increases, resulting in an even higher cost. Figure 1 is a process diagram showing the conventional method for manufacturing color picture tubes. After metal backing, panel baking is carried out in step 2, frit baking in step 3, sealing of the electron gun in step 4, exhaust in step 5, aging in step 6, and reinforcement with a rim band, tension band, etc. in step 7.

Among these steps 1 to 7, steps 2 to 5 are all heat treatment steps. Particularly, steps 2, 3, and 5 require a long time since it is necessary to uniformly heat almost the entire envelope. Process 4
Sealing can be accomplished in a relatively short time because only the neck portion of the electron gun needs to be heated. Figure 2 A and b are from step 2
This shows the relationship between the time in 5 and the temperature of the envelope.
Figure a corresponds to steps 2, 3, and 5, and figure b corresponds to step 4.

As is clear from the figure a, the temperature changes in steps 2, 3, and 5 consist of a temperature rising section U, a steady temperature section V1, and a temperature falling section W, and are specifically as follows. Therefore, the panel baking in step 2 will be in the oven for about 3 hours, the frit baking in step 3 will be in the oven for about 4 hours, and the exhaust in step 5 will be in the oven for 2 hours. Moreover, the temperature of the envelope immediately after opening the furnace is 70 to 8.
Since the temperature is 0°C, it is common to leave it to return to room temperature, perform some inspection and processing, and then use it for the next process. Moreover, even in the case of sealing in step 4, the material of the electron gun is oxidized due to the long heating time, even if it is a relatively short time, as the neck part of the envelope, which has once returned to room temperature, is heated again. There are disadvantages such as Furthermore, the conventional method for manufacturing color picture tubes has the following critical flaw.

That is, after completing each step of panel baking in Step 2, frit baking in Step 3, and sealing in Step 4, the envelope is always returned to approximately room temperature. However, this includes the following problem. First, when the panel portion is returned to room temperature after panel baking is completed, the gas released during baking and adsorbed on the glass surface is adsorbed again. This significantly reduces the life characteristics of the color picture tube. Furthermore, although the phosphor after baking is highly hygroscopic, the moisture adsorbed here remains without being sufficiently evacuated in the subsequent evacuation process, degrading the life characteristics. Furthermore, as is well known, moisture is adsorbed to the metal back layer during a period of time after baking, and the metal back layer is corroded by this moisture, resulting in a defective product. Furthermore, returning the envelope to room temperature after frit baking is also inconvenient due to the characteristics of color picture tubes. Regarding the panel section, there is a problem similar to that at the end of the panel baking described above, and there is also the problem of gas being adsorbed by the graphite film coated on the inner surface of the funnel section. That is, the gas adsorbed by the graphite film from the air at room temperature remains without being sufficiently exhausted due to baking during subsequent exhausting, significantly deteriorating the life characteristics. Furthermore, as the temperature of the entire envelope decreases, the volume of air inside the envelope decreases, and the outside air is absorbed through the open end of the neck, which also absorbs dust floating in the air. This may cause stray or spark generation during the operation of the picture tube. Further, it is also inconvenient due to the characteristics of color picture tubes that the envelope is returned to room temperature after the sealing process is completed. In other words, in the sealing process, a part of the neck tube is heated to a high temperature of about 800 to 900°C, but other parts of the envelope also become quite high temperature, and the air inside the envelope also becomes high temperature. . For this reason, as the temperature of the envelope decreases, air from outside is absorbed through the mouth of the exhaust pipe extending from the open end of the neck portion, causing stray and sparks. This point is similar to the problem that occurs at the end of frit baking. Furthermore, when the air outside the exhaust pipe is absorbed, moisture is adsorbed onto the cathode, resulting in deterioration of cathode characteristics. Therefore, an object of the present invention is to shorten each heating process and reduce the energy consumption, thereby lowering costs, and also making it possible to manufacture a color picture tube with excellent characteristics. This will be explained in detail below using examples.

FIG. 3 is a schematic diagram of the manufacturing process showing the method for manufacturing a color picture tube according to the present invention, and FIG. 4 is a diagram showing the relationship between the heating time and the temperature of the envelope during the heat treatment step of step 2. .

As is clear from FIG. 3, the present invention involves performing a series of heat treatment steps from step 2 to step 5 in a continuous manner in the conventional process explained in FIG. 1, and this will be explained in detail below. do. In FIG. 3, a panel portion and a funnel portion on which a fluorescent film is formed on the inner surface of the face plate and a metal back is applied in step 1 are placed in a furnace and subjected to a heat treatment step in step 2.

In this case, the panel part 11 and the funnel part 12 are joined in the state shown in FIG. Also, a piece of solid low-melting glass 14 protruding from the low-melting glass 14 is deposited. The panel section 11 is placed on top of the low melting point glass 15, and there is an air permeability gap corresponding to the thickness of the low melting point glass 15 between the low melting point glass 15 and the panel section 11. It is formed. In addition, 16 is Juanne Le part 1
This is a neck portion that protrudes from the small opening end of No. 2. The funnel portion and neck portion assembled in such a state are desirably heated at a rate of about 9 to 10° C./min in accordance with the schedule shown in temperature rising portion U in FIG. 4 in a furnace. Next, panel part 1
1 and the funnel section 12 are subjected to the schedule shown in steady temperature section 1. This steady temperature section ■1 is 4 as an example.
There are 3 powders at 00℃. This schedule corresponds to the panel baking step, and during this step V1, the organic material in the fluorescent film (on the inner surface of the face plate of the panel portion 11) is thermally decomposed and removed. Thermal decomposition in this case is performed satisfactorily through the above-mentioned ventilation gap, and no defective thermal decomposition occurs due to the fact that the panel portion 11 and the funnel portion 12 are joined. This ensures that the organic material in the fluorescent film is removed. Note that the important thing about this V1 schedule is that it must be set at a temperature at which the low melting point glass 14 does not crystallize. Following the schedule of the steady temperature section V1, the panel section 11 and the funnel section 12 are subjected to the steady temperature section V2. The steady temperature section V2 is, for example, 430° C. and 6 powders.
This process is equivalent to the frit baking process.
In this step, the spacer 15 made of low melting point glass is softened, integrated with the low melting point glass 14, and crystallized to airtightly fix the two. Following the steady-state temperature section V2, only a portion of the neck section 16 is subjected to the schedule indicated by V3.
As an example of the schedule for V3, the temperature rising section V''311.
5° C./sec, temperature decreasing part ■″″35.8 parts C/sec. This schedule corresponds to the sealing process. Therefore, the electron gun is housed at a predetermined position in the neck portion 16 of the envelope that has finished the steady temperature section V2. At this time, it is desirable to set the electron gun to approximately the same temperature as the envelope, particularly the neck portion 16, in advance. Furthermore, in order to prevent oxidation of the getter or other electron gun parts in an electron gun whose temperature has increased, it is desirable to create a non-oxidizing atmosphere around the electron gun. One example is to use a nitrogen atmosphere. As a method of sealing according to schedule V3, the neck portion to be sealed may be heated with a gas burner, as is conventionally known, or may be heated with electric heating. During this schedule, it is preferable that the remaining portions except a portion of the neck portion 16 smoothly transition from the steady temperature portion V2 to the steady temperature portion V4. The sealed envelope is then subjected to the steady temperature section V4 schedule and is evacuated. An example of the schedule for the steady temperature section V4 is 4.
It is one powder at 00℃. The envelope continues to follow the cooling section W schedule while being evacuated. This temperature decreasing part W is, for example, 3 to 5° C./min. The envelope, whose temperature has been lowered according to the schedule of the temperature lowering section W, will not implode even if it is taken out to room temperature when the temperature drops to below 10 degrees Celsius.For example, when the temperature reaches 80 degrees Celsius, the electron gun used for exhaust After the glass tubes are welded airtight, they are cut and used for aging in step 3. Here, in order to obtain the schedule as explained in Fig. 4, if picture tubes are manufactured in large quantities, the envelope should be placed on a conveyor that moves through a furnace with an appropriate temperature distribution. .

Further, when subjecting the panel portion and the funnel portion to the heat treatment process, they are not limited to being placed with spacers interposed therebetween as shown in FIG. 5, but may be placed in parallel in the same furnace.

That is, the panel section and the funnel section are heated by a conveyor moving in the furnace according to a temperature schedule as shown in FIG. * may be placed on the funnel portion having only the low melting point glass 4, and then the method described above may be followed. Further, in the present invention, the V3 schedule may be omitted.

In other words, the V3 schedule corresponds to the sealing process, but instead of the conventional method of sealing the electron gun by melting the neck, it is possible to weld the neck and the electron gun with low-melting glass or the like. good. In this case, when subjecting to the heat treatment process, the panel section, funnel section, and electron gun are assembled from the beginning, and the electron gun is placed at a predetermined position in the neck section with a low melting point glass interposed therebetween. At this time, since the sealing is performed by welding the low melting point glass, the sealing can be performed almost simultaneously with the welding of the panel portion and the funnel portion, that is, the frit baking step. Therefore, temperature schedule V3 becomes unnecessary. In this step as well, it is desirable that the area around the getter be in a non-oxidizing atmosphere, such as a nitrogen atmosphere, so that the metallic barium constituting the getter does not become barium oxide. Further, in the present invention, it is conceivable that only the neck portion 16 of the envelope is returned to room temperature in the sealing process. Supplying an electron gun to the neck portion 16 at approximately the same temperature as frit baking has various problems, such as the need to preheat the electron gun and the need to control the atmosphere to prevent oxidation. In order to avoid this, it is conceivable to provide the furnace 17 with an opening as shown in FIG. 6, and to allow only the neck portion 16 to come out of the furnace through the opening at an appropriate time during the sealing process. An electron gun is supplied to the neck portion 16, which has been taken out of the furnace 17 and has reached approximately room temperature, and is sealed. Neck part 16
Since the heat capacity of the electron gun is relatively small, an electron gun is supplied to the neck part 16, which has been taken out of the furnace and has reached approximately room temperature, and is sealed.
Since the heat capacity of the neck tube is relatively small, it is possible to seal it with about 2 powders after taking it out of the furnace. You can also blow cold air to cool it down even faster. The electron gun may be sealed in the neck portion, which has thus reached approximately room temperature, in the same manner as in the conventional method. Furthermore, the method for manufacturing a cathode ray tube according to the present invention is not limited to the shape of the envelope for general picture tubes; Of course, this can also be applied to enclosures. The method for manufacturing a cathode ray tube according to the present invention has the following effects.

First, the cost of energy (gas, electricity) and tap water required to manufacture one color picture tube can be significantly reduced. That is, conventionally, dedicated furnaces were used for panel baking, frit baking, and exhaust, but according to the present invention, a common furnace can be used for all, which reduces the cost of energy and tap water. This means that the manufacturing cost per color picture tube is about 30% of the conventional manufacturing method. Second, the color picture tube 1
It takes less time to produce a book. By eliminating the repetition of the temperature lowering section and the temperature lowering section when inputting to the next process in the conventional manufacturing method, the heat treatment process which conventionally required more than 9 hours can be completed in about 4 hours according to the present invention.
Third, the defective rate is significantly reduced. Glass envelopes are prone to cracking when the temperature is lowered or lowered, but with conventional manufacturing methods, there is a high probability that the envelope will crack during the manufacturing process as there are several heating and cooling steps. However, according to the present invention, the temperature is raised and lowered once each, which has the effect of significantly reducing the probability of cracking.

[Brief explanation of the drawing]

FIG. 1 is a process diagram for explaining a conventional cathode ray tube manufacturing method, FIGS. 2A and b are diagrams showing temperature schedules in the conventional cathode ray tube manufacturing method, and FIG. FIG. 4 is a diagram showing a temperature schedule in the method for manufacturing a cathode ray tube according to the present invention, and FIGS. 5 and 6 are process diagrams for explaining the method for manufacturing a cathode ray tube according to the present invention. FIG. 11... Panel part, 12... Funnel part, 13... Conductive coating, 14, 15...
...Low melting point glass, 16...Neck part, 17
・・・・・・Furnace.

Claims (1)

[Claims] 1. An envelope formed by at least a neck portion in which an electron gun is housed, a substantially funnel-shaped funnel portion, and a panel portion having a fluorescent film containing an organic material on the inner surface of the face plate. In the method for manufacturing a cathode ray tube, the temperature of the panel part and the funnel part is lowered following a panel baking process in which the temperature of the panel part and the funnel part is raised and the organic material on the inner surface of the face plate of the panel part is thermally decomposed and removed. A frit baking process is carried out in which the solder glass is melted and the two are bonded together, and then the temperature of the entire envelope is shifted from this frit baking process to the temperature of the exhaust process, and the inside of the envelope is evacuated. A method for manufacturing a cathode ray tube. 2. Manufacture of a cathode ray tube having an envelope formed by at least a neck part in which an electron gun is housed, a substantially funnel-shaped funnel part, and a panel part having a fluorescent film containing an organic material on the inner surface of the face plate. In this method, the solder glass is melted without lowering the temperature of the panel and funnel parts, following a panel baking process in which the temperature of the panel part and the funnel part is raised to thermally decompose and remove the organic material on the inner surface of the face plate of the panel part. Then, a sealing process is performed to heat a part of the neck part and seal the electron gun. During the frit baking process, the temperature of the entire envelope is lowered by the exhaust process. A method for manufacturing a cathode ray tube, in which an evacuation step is performed to evacuate the inside of the envelope at a temperature of 3. The method of manufacturing a cathode ray tube according to claim 2, wherein the electron gun is maintained at a temperature for a frit baking process before being sealed in the neck portion. 4. The method of manufacturing a cathode ray tube according to claim 2, wherein the neck portion is taken out of the furnace, and after only this neck portion is brought to room temperature, the electron gun is housed and the sealing process is performed. 5. Manufacture of a cathode ray tube having an envelope formed by at least a neck portion in which an electron gun is housed, a substantially funnel-shaped funnel portion, and a panel portion having a fluorescent film containing an organic material on the inner surface of the face plate. In this method, the solder glass is melted without lowering the temperature of the panel and funnel parts, following a panel baking process in which the temperature of the panel part and the funnel part is raised to thermally decompose and remove the organic material on the inner surface of the face plate of the panel part. At the same time, a frit baking process is carried out to join the two together, and a sealing process is carried out in which the solder glass is melted at the temperature of this frit baking process to seal the electron gun in the neck part. A method for manufacturing a cathode ray tube, in which an evacuation process is carried out in which the temperature of the entire vessel is shifted to the temperature of the evacuation process and the inside of the envelope is evacuated.