JPS6139699B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a vapor-deposited film for a color picture tube, and more particularly to a method for forming a light-reflecting metal thin film on the fluorescent surface of a color picture tube having a metal back structure by vacuum deposition. .

The phosphor surface of a normal color picture tube is a glass face plate that forms part of the tube body of the picture tube. This is generally achieved by forming a light-reflecting metal film to effectively extract the light to the front of the color picture tube, and this is called a metal back structure.

This metal pack fluorescent surface has the advantage of increasing the brightness of the color picture tube and preventing the phenomenon of ion burnout, and its manufacturing process will be described with reference to FIG.

FIG. 1 is a sectional view for explaining the manufacturing process of a fluorescent surface portion of a color picture tube. In Figure 1,
1 is a glass face plate, 2 is a phosphor film adhered to the inner surface of the plate 1, and 3 is a film lacquer material mainly composed of an organic substance for smoothing the surface of the phosphor film 2. The intermediate film 4 formed by the above is an aluminum thin film. The phosphor film 2 is applied to the inner surface of the plate 1 to a uniform thickness,
It is formed by drying this. Also,
The aluminum thin film 4 is formed by depositing aluminum on the intermediate film 3 in a vacuum, and the intermediate film 3 is then removed by baking treatment.

FIG. 2 shows an example of a conventional vapor deposition apparatus. As shown in FIG. 2, conventionally, in order to form an aluminum thin film by vapor deposition, a glass face plate 1 on which an intermediate film 3 is formed is placed in a supported state at a predetermined position within a vacuum envelope 6. . Vacuum envelope 6
The evaporation source is provided with one or more basket-shaped evaporation sources made of three or four strands of tungsten wire and maintained at a vacuum of 10 ^-4 torr.
Although a method of vapor depositing aluminum on the intermediate film 3 has been used in this manner, a coil made of tungsten wire is used as the evaporation source 5, which has the drawback of short life.

In order to eliminate this drawback, a method of using a resistance heating element instead of a tungsten wire coil has been proposed and has already been put into practical use. As the resistance heating element, one whose main component is boron nitride is generally used. An example of this type of resistance heater is shown in perspective view in FIG. As shown in FIG. 3, a recess 7a is formed on the upper surface of the rectangular parallelepiped resistance heating element 7, forming a so-called board-like structure. Note that the recess 7a is not provided,
Some are just flat surfaces. This boat-shaped resistance heating evaporation source (hereinafter referred to as
It is called a "boron nitride heating element." ) will be described with reference to FIG. 4.

FIG. 4 is a block diagram schematically showing an example of a vapor deposition apparatus using a boron nitride heating element. In FIG. 4, parts corresponding to those shown in each of the figures described above are given the same reference numerals, and their explanations will be omitted. The vapor deposition apparatus shown here includes a direct air envelope comprising an inlet chamber 6a, an aluminum vapor deposition chamber 6b and an outlet chamber 6c. An aluminum wire automatic inserter 8 is provided in the vapor deposition chamber 6b, and an aluminum wire 9 is supplied by it. Additionally, a gate valve 1 is provided between the inlet chamber 6a and the outlet chamber 6c to separate the external atmosphere from the inlet chamber 6a and the outlet chamber 6c.
0 and 10 are provided, and gate valves 11 and 11 are provided to partition off the aluminum deposition chamber 6b and the inlet chamber 6a and outlet chamber 6c.

In the above configuration, the glass face plate 1 on which the interlayer film 3 is formed is carried into the inlet chamber 6a of the vacuum envelope, and the inlet chamber 6a and the outlet chamber of the vacuum envelope are removed by an evacuation device such as a vacuum pump (not shown). 6c is evacuated to 0.05 to 0.01 torr, and aluminum deposition chamber 6b is evacuated to 1 to 2×10 ⁻⁴ torr. Next, the gate valve 11 is opened, the glass face plate 1 is transported to a predetermined position in the aluminum receiving chamber 6b, and the gate valve 11 is closed. Next, the inlet chamber 6a is brought to atmospheric pressure, the gate valve 10 is opened, another glass face plate 1 on which the interlayer film 3 has been formed, that is, the glass face plate 1 to be vapor-deposited next, is carried in, and the inlet chamber 6a and the outlet chamber are opened again. 6c has a vacuum of 0.05 to 0.01 torr, and aluminum deposition chamber 6b has a vacuum of 1 to 2×10 ^-4 torr.
is made into a vacuum.

The boron nitride heating element 7 is installed at a predetermined position at the bottom of the aluminum deposition chamber 6b, and is heated to about 1350 to 1500 DEG C. by electricity.
Concave portion of this boron nitride heating body 7 (vapor deposition material placement portion)
An aluminum wire 9, which is a vapor deposition material, is inserted into the tube 7a by an automatic inserter 8, and the aluminum wire 9 is evaporated by the temperature rise caused by the heat generated by the heating element 7, and the aluminum wire 9 is scattered upward. Due to this evaporation, an aluminum thin film 4 is formed on the intermediate film 3.
At this time, the boron nitride heating element 7 is constantly heated (1350~
1500℃), the automatic aluminum wire inserter 8 is stopped except during vapor deposition, and the aluminum wire 9 is
is not inserted. In order to control the amount of aluminum evaporated to the amount necessary for the picture tube, the speed and time of automatic insertion of the aluminum wire 9 are controlled. In this way, the aluminum thin film 4 is formed.

Next, the gate valves 11, 11 are opened, and the glass face plate 1 of the aluminum deposition chamber 6b is transferred to the outlet chamber 6c, and the glass face plate 1 of the inlet chamber 6a is transferred to the outlet chamber 6c.
is transported to the aluminum deposition chamber 6b. Further, the inlet chamber 6a and the outlet chamber 6c are set to atmospheric pressure, and the glass face plate 1 in the outlet chamber 6c is carried out of the vacuum envelope to complete the vapor deposition process. At the same time, another glass face plate 1 is carried into the entrance chamber 6a, and the steps described above are repeated.

The above-described process has problems as described below. That is, this is caused by the fact that the boron nitride heating element 7 is constantly heated. To be more specific, except when depositing on the glass face plate 1 which is the object to be deposited,
In the method of stopping the insertion of the aluminum wire 9 and controlling the amount of vapor deposition by the speed and time at which the aluminum wire 9 is inserted, the aluminum wire 9 is in a stopped state when the glass face plate 1 is being transported. Therefore, due to the heat of the heating body 7, the tip of the aluminum wire 9 is melted into a bead shape as shown in FIG. In addition, since the heating element 7 is constantly heated,
No molten aluminum remains in the recess 7a of the heating body 7. Therefore, when the glass face plate 1, which is the next object to be deposited, is carried in, the aluminum wire 9 is again inserted into the recess 7a of the heating element 7, but the beaded tip of the aluminum wire 9 is immediately removed. Since it is difficult to melt and there is no molten aluminum remaining in the recess 7a, heat is difficult to be transferred to the aluminum wire 9, which also makes it difficult for the aluminum wire 9 to melt quickly. For this reason, even if the aluminum wire 9 is inserted into the recess 7a of the heating element 7, it may slip through the recess 7a and come off to the front of the heating element 7 without melting and vapor deposition, making it impossible to perform vapor deposition. In such a case, each time such a situation occurs, the vacuum state of the vapor deposition apparatus must be returned to atmospheric pressure and readjusted.
Therefore, a lot of time is spent on adjustment and returning to vacuum. Furthermore, since the boron nitride heating element 7 is continuously heated, there is also a drawback that the lifespan is shortened.

This invention was made in view of the above-mentioned drawbacks, and in the production of a vapor deposited film by vacuum evaporation using a resistance heating element as an evaporation source, for example, an aluminum wire as a vapor deposition material can be easily melt-deposited.
The present invention aims to provide a method for producing a vapor-deposited film for a color picture tube.

To summarize, this invention is a method for producing a vapor deposited film for a color picture tube, characterized in that the heating temperature of a resistance heating element is set lower than the heating temperature during vapor deposition except during vapor deposition.

Other objects and features of the present invention will become more apparent from the detailed description given below with reference to the drawings.

One embodiment of the present invention can be described with reference to FIG. 4 mentioned above. In Figure 4,
The steps of applying a phosphor to the inner surface of the glass face plate 1, drying it to form a phosphor film 2, and then forming an intermediate film 3 thereon are the same as in the conventional case. Further, the transportation of the glass face plate 1 to be vapor-deposited and the timing of setting the vacuum or pressure conditions in the vacuum envelope are the same as in the conventional case. The characteristic process conditions of this invention that are different from the conventional case will be described below.

In the aluminum deposition chamber 6b, the amount of aluminum deposited necessary for the picture tube is controlled by the speed and time of automatic insertion of the aluminum wire 9, as in the past. However, just before the automatic insertion of the aluminum wire 9 is stopped, the current value of the boron nitride heating element 7, which is heated to 1350 to 1500°C by electricity, is suddenly lowered to, for example, bring the heating temperature to about 900°C. It can be done. FIG. 6 is a diagram for explaining one embodiment of the present invention, and is a diagram showing the heating temperature change of the boron nitride heating body 7 in the order of steps. This sixth
As is clear from the figure, during the transfer of the glass face plate 1, the value of the current applied to the boron nitride heating element 7 is low, and therefore the heating temperature is approximately 900°C.
°C and maintain that state. Then, when forming the aluminum thin film 4 on the next glass face plate 1, the current value is increased again and the heating temperature is raised to 1350 to 1500°C. In this way, by controlling the heating temperature of the heating element 7,
Even if the vapor deposition process is repeated, there is always a residual amount of the molten aluminum wire 9 in the recess 7a of the heating element 7, so even when the aluminum wire 9 is automatically inserted during vapor deposition again, the recess 7a of the heating element 7 can be smoothly removed. It is understood that it melts, spreads, and evaporates. Also, when transporting the glass face plate 1,
Since the heating temperature of the boron nitride heating element 7 is actively lowered, the tip of the aluminum wire does not become beaded as shown in FIG. 5, and even smoother aluminum evaporation can be performed.

In the above embodiment, the heating temperature of the boron nitride heating element 7 was set to 900°C except when aluminum was deposited on the intermediate film 3 on the inner surface of the glass face plate 1. Needless to say, it's a good thing. However, considering the time it takes to restore the temperature when depositing again, it takes 900
It is desirable that the temperature be around ℃.

As described above, according to the present invention, although it is a simple means of keeping the heating temperature of the resistance heating element lower than the heating temperature during vapor deposition except during vapor deposition,
The inserted evaporation material and the heated resistance heating element become compatible, and therefore the time for readjustment and the associated time for return to vacuum can be significantly reduced. Furthermore, since the heating of the resistance heating element is not continuous, its lifespan can be extended by approximately 1.5 times.

[Brief explanation of the drawing]

FIG. 1 is a sectional view for explaining the manufacturing process of a fluorescent surface portion of a color picture tube. FIG. 2 shows an example of a conventional evaporation apparatus, and is a schematic configuration diagram when a tungsten coil is used as an evaporation source. FIG. 3 is a perspective view of a board-shaped resistance heating body containing boron nitride as a main component. FIG. 4 is a block diagram schematically showing an example of an evaporation apparatus using a board-shaped low resistance heating element containing boron nitride as a main component as an evaporation source. FIG. 5 shows the tip of the aluminum wire melted into a bead shape by the heat generated by the resistance heating element. FIG. 6 is a diagram for explaining an embodiment of the present invention, and is a diagram sequentially showing the heating temperature change of a boat-shaped resistance heating body containing boron nitride as a main component. In the figure, 1 is a glass face plate, 2
3 is a phosphor film, 3 is an intermediate film, 4 is an aluminum thin film, 6a is a vacuum envelope entrance chamber, 6b is a vapor deposition chamber, 6
c is an exit chamber, 7 is a boat-shaped resistance heating body mainly composed of boron nitride, 7a is a recess as a deposition material placement part, 8 is an aluminum wire automatic inserter, 9 is an aluminum wire as a deposition material, 10, 11 is a gate valve.

Claims (1)

[Scope of Claims] 1. A method for producing a vapor deposited film in which a light reflective metal thin film is vacuum vapor deposited on an intermediate film of a fluorescent surface portion of a color picture tube using a low heating resistance body having a vapor deposition material placement portion as an evaporation source, A method for producing a vapor deposited film for a color picture tube, characterized in that the heating temperature of the low resistance heating element is set to a temperature lower than the heating temperature during vapor deposition except during vapor deposition.