JPS6141094B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a light-reflecting metal thin film on the inner surface of a fluorescent surface of a color picture tube.

The phosphor surface of a normal color picture tube is a phosphor film attached to the inner surface of a glass face plate that forms part of the tube body, and the light emitted from this phosphor film is used to effectively receive color images. A so-called metal back structure in which a light-reflecting metal thin film is formed to take the light out to the front of the tube is common. The phosphor surface of this metal back structure has the advantage of increasing the brightness of the color picture tube and preventing the phenomenon of ion burning of the phosphor film. The manufacturing process will be explained with reference to FIG.

In FIG. 1, 1 is a face plate, 2 is a phosphor film coated on the inner surface of the face plate 1, and 3 is a phosphor film mainly composed of an organic substance to smooth the surface of the phosphor film 2. An intermediate film 4 formed of a lacquer material for filming is a light-reflective metal thin film, for example, an aluminum (Al) thin film. This Al thin film A is formed by depositing Al on the intermediate film 3 in a vacuum, and then the intermediate film 3 is removed by baking treatment.

Conventionally, in order to form the Al thin film 4 by vapor deposition,
As shown in FIG. 2, one or more evaporation sources 5 are formed by forming a face plate 1 with a phosphor film 2 and an intermediate film 3 into a basket shape using three to four twisted tungsten wires. vacuum envelope 6 with
in a vacuum of 10 ^-4 Torr.
A method has been used in which Al is evaporated onto the intermediate film 3, but since a tungsten wire coil is used as the evaporation source 5, the tungsten wire surface becomes alloyed with Al and deteriorates, resulting in a short service life. .

In order to eliminate the above drawbacks, a method of using a resistance heating element in place of the tungsten wire coil has been proposed and put into practical use. As this resistance heating element, one whose main component is boron nitride is generally used. As shown in FIG. 3, this type of resistance heating element has a so-called board-like structure in which a recess 7a serving as a deposition material placement part is formed on the upper surface of the rectangular parallelepiped resistance heating element 7. Note that there is also one in which the concave portion 7a is not particularly provided and is made flat.

A method for producing a vapor deposited film when this board-shaped resistance heating body (hereinafter abbreviated as boron nitride heating body) 7 containing boron nitride as a main component is used as an evaporation source will be described with reference to FIG.

In FIG. 4, 1 to 4 and 7 indicate the same parts as in FIGS. 1 to 3, and 8 is a vacuum envelope, which is composed of an inlet chamber 8a, an Al vapor deposition chamber 8b, and an outlet chamber 8c. Reference numeral 9 denotes an automatic inserter for automatically inserting a vapor deposition material, 10 a vapor deposition material such as an Al wire (described below using an Al wire), and 11 and 12 gate valves, respectively.

The face plate 1 with the interlayer film 3 formed thereon is carried into the inlet chamber 8a of the vacuum envelope 8, and the inlet chamber 8a and outlet chamber 8c are heated to a pressure of 0.05 to 0.01 Torr using an evacuation device such as a vacuum pump (not shown). The Al vapor deposition chamber 8b is brought to a vacuum of 1 to 2×10 ⁻⁴ Torr. Next, open only the gate valve 12 and open the face plate 1.
is transported to a predetermined position in the Al deposition chamber 8b, and the gate valve 12 is closed. Next, the inlet chamber 8a and the outlet chamber 8c are set to atmospheric pressure, the gate valve 11 is opened, and another face plate 1 on which the interlayer film 3 is formed is carried into the inlet chamber 8a, and the pressure in the inlet chamber 8a and the outlet chamber 8c is 0.05. ~
The vacuum of 0.01 Torr. and the Al deposition chamber 8b are 1 to 2
Create a vacuum of ×10 ^-4 Torr. The boron nitride heating element 7 installed at a predetermined position at the bottom of the Al deposition chamber 8b is
Al
When the wire 10 is inserted into the recess 7a of the boron nitride heating body 7 using the automatic inserter 9, the Al wire 10 evaporates and scatters upward due to the temperature rise due to the heat generated by the boron nitride heating body 7. This evaporation forms an Al thin film 4 on the intermediate film 3. When the vapor deposition is completed, the gate valve 12 is opened, the face plate 1 of the Al deposition chamber 8b is transferred to the outlet chamber 8c, and the face plate 1 waiting in the inlet chamber 8a is transferred to the Al vapor deposition chamber 8b, and the gate valve 12 is opened. After closing, the inlet chamber 8a and the outlet chamber 8
c is set to atmospheric pressure, and the face plate 1 in the outlet chamber 8c is carried out to the outside of the vacuum envelope 8 to complete the vapor deposition process. At the same time, another face plate 1 is carried into the entrance chamber 8a, and the above steps are repeated in sequence.

In the above process, the degree of vacuum in the Al vapor deposition chamber 8b is always maintained at 0.05 Torr or higher, so even when transporting the face plate 1 that has been vapor-deposited or carrying in the face plate 1 that has not been vapor-deposited, the vacuum level in the Al vapor deposition chamber 8b is always maintained at 0.05 Torr. It is not necessary to lower the temperature of the boron heating element 7 to near room temperature; rather, in order to shorten the heating time, it is preferable to supply power even during non-evaporation to maintain a constant temperature. Therefore, in practice, the boron nitride heating element 7 is always heated to a temperature of about 1000 DEG C., and then raised to about 1350 DEG C. to 1500 DEG C. during vapor deposition.

On the other hand, the recess 7a of the boron nitride heating body 7 is
The Al wire 10 is supplied to the automatic inserter 9 at the same time as the temperature is raised.
The feeding was started from the point where the vapor deposition was completed and the temperature started to drop, and then the feeding was stopped.

However, the temperature of the boron nitride heating element 7 is 1350~
It takes more than ten seconds for the temperature to drop from 1500°C to around 1000°C, and during this time evaporation continues and the concave portion 7a
The Al will be gone. Then, even if the Al wire 10 is inserted into the recess 7a at the start of the next vapor deposition, it will not melt immediately, but will slide over the surface of the boron nitride heating element 7 and protrude from the boron nitride heating element 7, making it impossible to perform vapor deposition. Something happens that disappears. When such a situation occurs, the apparatus must be disassembled and readjusted, and therefore time is wasted for adjustment and return to vacuum.

This invention was made in order to eliminate the above-mentioned drawbacks. When a boat-shaped resistance heating element mainly composed of boron nitride is used as an evaporation source, the Al wire can be easily melted and the evaporation process can be ensured. The present invention aims to provide a method for forming a vapor-deposited film for a color picture tube. This invention will be explained below using FIG. 4.

The reason for the above-mentioned problem is that when the dissolved Al on the surface of the boron nitride heating element 7 is exhausted, the contact area of the inserted Al wire 10 with the surface of the boron nitride heating element 7 becomes smaller. Sufficient heat to melt Al is not provided to the Al side, and the dissolution rate and Al
This is because the insertion speeds do not match.

Therefore, in the present invention, the Al wire 10 fed out from the automatic inserter 9 penetrates into the molten Al of the boron nitride heating element 7, leaving the molten Al in the recess 7a of the boron nitride heating element 7 at all times. Dissolved Al
By increasing the contact area between the Al wire 10 and the Al wire 10,
It is designed to increase the temperature quickly.

Specifically, in this vapor deposition process, when the amount of Al vapor required for the fluorescent surface is reached, the temperature of the boron nitride heating element 7 is rapidly lowered to about 1000°C, but during this time, the Al wire 10 is also inserted into the automatic inserter. 9, insert until just before it stops dissolving and stop. Then, when forming the Al thin film 4 on the next face plate 1, the current value is increased again to raise the heating temperature to 1350 to 1500°C.

However, even if the above-mentioned process is repeated, since there is a solution of the Al wire 10 in the recess 7a of the boron nitride heating element 7, even if the Al wire 10 is automatically inserted during vapor deposition again, the boron nitride heating element 7 will be smoothly heated. It dissolves in the recess 7a, spreads and evaporates.

Although the above embodiment describes the case of the vapor deposition method of the Al thin film 4, this method can also be applied to vapor deposition film formation in which a blackened Al film is vapor-deposited in a low vacuum using the boron nitride heating element 7 as the evaporation source. Is possible.

As explained above, according to the present invention, the heating temperature of the boron nitride heating body is set to a heating temperature lower than that during evaporation except during evaporation, and the heating temperature of the boron nitride heater is set to a heating temperature lower than that during evaporation.
Although it is a simple method of inserting the wire into the boron nitride heating element, the Al wire and the heated boron nitride heating element become compatible, eliminating the waste of readjustment time and vacuum return time required in the conventional method. Therefore, there are advantages such as improved operating efficiency of the apparatus and stable deposition film thickness distribution.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view for explaining the manufacturing process of the fluorescent surface part of a color picture tube, Fig. 2 is a schematic diagram of a conventional vapor deposition apparatus, and Fig. 3 is a boat-shaped film mainly composed of boron nitride. FIG. 4 is a perspective view of the resistance heating element, and is a schematic configuration diagram of an example of a vapor deposition apparatus used to explain an embodiment of the present invention. In the figure, 1 is the face plate, 2 is the fluorescent film, and 3 is the face plate.
is an intermediate film, 4 is an Al thin film, 7 is a boron nitride heating element,
7a is a recess, 8 is a vacuum envelope, 8a is an entrance chamber, 8
b is an Al vapor deposition chamber, 8c is an outlet chamber, 9 is an automatic inserter, 10 is an Al wire, and 11 and 12 are gate valves.
Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A light-reflecting metal thin film is placed on the intermediate film of the fluorescent surface of a color picture tube that is intermittently carried into a deposition chamber by a vacuum device that uses a resistance heating element as an evaporation source and has a flat or concave deposition material placement section. In the vapor deposition film production method of vacuum vapor depositing, the temperature of the resistance heating body is selected during vapor deposition and non-evaporation, and the metal material of the light reflective metal thin film is supplied onto the resistance heating body during vapor deposition to complete the vapor deposition. Accordingly, the temperature of the resistance heating body is lowered to the non-vapor deposition temperature, and the supply of the metal material is continued until the temperature reaches the non-vapor deposition temperature. Method.