JPS60112225A - Method for forming metallic film on fluorescent screen - Google Patents

Abstract

PURPOSE:To make up a high quality vapor coating film with high reflectivity by forming an vapor coating film on a fluorescent screen at a low vacuum by rotating a vapor coating source at the time other than doing necessary vacuum vapor coating. CONSTITUTION:At the time when a glass face plate 1 is conveyed into an aluminum vapor coating chamber 6b, a heating surface 7a of a resistance heat element 7 is turned toward the direction not facing to the fluorescent screen of the plat 1. Therefore, even if the remaining aluminum molten liquid is vaporized it does not vaporized toward the fluorescent screen. When the vacuum of the vapor coating chamber 6b becomes high and approaches to a vaporization starting value a high level voltage is applied to the resistance heat element 7 and its heating surface 7A is turned to the condition to face the fluorescent screen and vapor coating is carried out under a high vacuum for a predetermined hours. When the vapor coating is completed the voltage applied to the heat element 7A is lowered, the supply of an aluminum wire is stopped, and the heat element 7A is rotated to return to the original condition. By these operations a high quality vapor coating film with high reflectivity is formed.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a method for forming a metal film on a fluorescent surface by vapor deposition, and particularly relates to a method for forming a metal film on a fluorescent surface of a color picture tube having a metal back structure. The present invention relates to a method for forming a film by vacuum evaporation.

[Prior art]

The phosphor surface of a normal color picture tube is formed on a phosphor film attached to the inner surface of a glass face plate (spring) that forms part of the tube body of the picture tube. By fully forming a light-reflective metal thin film to effectively extract the light to the front of the color picture tube! 2 is commonly realized, and this is called a metal back structure.

This metal back phosphor screen 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 explained 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, (υ is a glass face plate, (2) is a phosphor film attached to the inner surface of the dot plate (1), and (3) is a phosphor film of this phosphor film (2). The interlayer film (4) formed of a film lacquer material mainly composed of an organic material for smooth V rubbing is an aluminum thin film.The phosphor film (2) is a plate (υ
It is applied to the inner surface of the body to a uniform thickness and is dried to form a multilayered coating. Further, the aluminum thin film (, 4) is formed on the intermediate film (3) by depositing aluminum in vacuum, and then the intermediate film (3) is removed by baking.

FIG. 2 shows an example of a conventional vapor deposition apparatus. As shown in this figure, conventionally, in order to form a thin aluminum film by vapor deposition, a glass face group (v-)(
1) is placed in a supported state at a predetermined position within the vacuum envelope (6). Vacuum envelope (61 is made of 3 or 4 stranded tungsten wires)
one or more evaporation sources (5) are provided, 10'
A vacuum of Torr is maintained.

In this way, a method of vapor depositing aluminum on the intermediate film (3) has been used, but since a coil made of tungsten wire is used as the evaporation source (5), there is a drawback that the service life is short.

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 used in Tenkawa. As the resistance heating element, one whose main component is boron oxide is generally used. An example of this type of resistance heater is shown in perspective view in FIG. As shown in this figure, a recess (7a) is formed on the upper surface of the rectangular parallelepiped-shaped resistance heating element (7), forming a so-called port-like structure. In addition, there is also one that does not have the recessed portion (7a) and is simply a flat surface. A method for producing a deposited film using a boat-shaped resistance heating evaporation source (hereinafter referred to as a "boron nitride heating element") containing boron nitride as a main component will be described with reference to FIG.

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 has an entrance chamber (6a
), aluminum deposition chamber (1) and outlet chamber (6 (d)
Including the prefectural air envelope with.

In the vapor deposition chamber (6b), an aluminum shim wire automatic inserter (8) is installed.
is provided, thereby supplying the aluminum wire (9). In addition, in the entrance chamber (6a) and the exit chamber (6C),
Gate valves (IQ, Q
l is provided, and an aluminum deposition chamber (6b) and an inlet chamber (6b) are provided.
6a) and the outlet chamber (6C), a gate valve Oυ.

Ql) is provided.

In the above configuration, the glass face plate (11) on which the intermediate film (3) is formed is connected to the inlet chamber (6) of the vacuum envelope.
ε,), and the Makabe envelope entrance chamber (6a,) and outlet chamber (6a,
60) Makabe of k 0.05-0.01 Torr,
Aluminum deposition chamber (6b) k 1-2 x 10-'
Torr<D vacuum is maintained respectively. Suddenly,
Open only the gate valve 0υ and remove the glass face plate (υ
? The aluminum evaporation chamber (61) is transported to a predetermined position I-, and the gate valve αυ is closed.

At the same time, the inlet chamber (6a) is brought to full atmospheric pressure, the gate valve Q is opened, and another layer of the interlayer film (3)' (!l-formed, that is, the glass face plate V- to be vapor-deposited next) is opened. (υ
is carried in, and the inlet mold (6a) and outlet chamber (6C) are set to 0.
The aluminum deposition chamber (6b) is maintained at a vacuum degree of 1 to 2 x 10'rorr at each time of 05 to Q, Q l'rorr.

A boron nitride heating element (7) is installed at a predetermined position at the bottom of the circle of the aluminum deposition chamber (6b), and the groove is heated to about 1350 to 150 FC by energization. Four parts (evaporation material placement part) (7) of this boron nitride heating body (7)
In a), the aluminum wire (9), which is the vapor deposition material, is inserted into the automatic inserter (8), and the aluminum wire (9) is evaporated by the temperature rise caused by the heat generated by the heating element (7). Scatter upward. As a result of this evaporation, an aluminum thin film (4) is formed on the intermediate film (3J).

When the vapor deposition is completed, the gate valve aυ, L11) is opened, and the aluminum vapor deposition chamber (60) is opened.
) is transported to the exit room (6C), and the gala 77 Aisne plate (υ is transported to the aluminum ffi arrival room (6b)) waiting in the entrance room (6a). Also, the entrance room (6a) and exit note (6c) The glass face plate (υ) in the outlet chamber (6C) is brought out of the vacuum envelope to complete the vapor deposition process.At the same time, another glass face plate (υ) is placed in the inlet chamber (6a). A second tel is brought in and the process as described above is repeated.

In the above process, the degree of vacuum in the evaporation chamber (6b) is always maintained at 0.05 Torr or higher, so the glass face plate (υ) that has been evaporated is transported or the glass face plate that has not yet been evaporated (υ) is transported. There is no need to lower the temperature of the heating element (7) to near room temperature even during delivery.
Rather, in order to shorten the temperature rise time, it is preferable to supply a "forming force" to maintain a constant temperature even during non-evaporation. Therefore,
In practice, the boron nitride heating element (7) is always heated at 100 o-c.
It is heated to a temperature after i+1, and at the time of vapor deposition it is about 13
A method of raising the temperature to 50-1500'C is used.

On the other hand, the aluminum wire (9λ) is supplied to the recess (7a,) of the sword mouth heat sink (7) at the same time as the temperature is raised.
), and when the amount of aluminum deposited necessary for the fluorescent surface is reached, the temperature of the boron nitride heating element (7) is rapidly lowered to approximately 1000°C, but during this time, the aluminum wire (9) is The aluminum wire (9) is inserted into the automatic wire inserter (8) while the heating temperature of the boron oxide heating element (7) is decreasing until just before it stops melting, and then it is once pulled back slightly. This is to allow the aluminum melt to remain in the four parts (7υ) of the heating body so that the aluminum wire (9) can be easily melted by the boron nitride heating body (7) during vapor deposition again.

However, when the temperature of the resistance heating element (7) is set at two levels, high and low during vapor deposition and during non-evaporation, the electrified boron heating occurs in the process of decreasing from the theoretical thermal temperature during vapor deposition to the heated thermal temperature during non-evaporation. The aluminum melt remaining in the body recess (7a) evaporates. Further, if the heating temperature during non-evaporation is set to 1000 to 1150°C in order to shorten the reheating time from the non-evaporation period to the time of evaporation, the aluminum melt evaporates little by little during the non-evaporation period. In the latter case, if the vacuum is not sufficient between the time of non-deposition and the time of deposition, that is, the degree of vacuum is not sufficient before starting the deposition, the deposited film will be colored brown, which is an undesirable symptom for a light-reflecting film. There was C.

In addition, a deposition chamber (60
), which resulted in the formation of a vapor-deposited film of poor quality over a wide area of the ceiling, which was also undesirable in terms of maintenance of the equipment. Therefore, conventional methods have drawbacks in film quality, equipment maintenance, and the like.

[Summary of the invention]

This invention was made in view of the above-mentioned drawbacks, and it is possible to form a high-quality vapor deposited film with good reflectivity in order to increase the light output of a fluorescent surface when a resistance heating element is used as an evaporation source. To provide a method for forming a metal film on a fluorescent surface, which minimizes the scattering of unnecessary vapor deposited substances due to low-level heating, and facilitates maintenance of the apparatus, that is, maintenance of the degree of vacuum, internal maintenance, etc. The purpose is to

The above-mentioned problem IIIJ is a secondary problem that arises because heating is always performed, albeit at a somewhat low temperature, for the purpose of increasing the efficiency of heating the resistance heating element, even at times and under conditions that do not originally require vapor deposition. Various methods can be considered to further overcome this problem. The most common method would be to use a shutter, but according to the results of the inventors' implementation, there were various problems such as overheating caused by separation due to driving, falling of adhered substances, and restrictions on shape. As a result of continued studies and experiments, the inventors came up with a method in which the resistance heating element is rotated except during necessary deposition, and is directed toward a limited part of the deposition chamber, and has confirmed that it is extremely effective. This invention was completed.

[Next example of the invention]

Embodiments of the present invention will be described below with reference to all the drawings.

Fig. 5 is a front view schematically showing an example of the apparatus necessary for carrying out the present invention, and Fig. 6 is a plan view of the same. ), there is a concave part (7a) on the top surface of the tab heating surface (7A) as before.
is formed and has a boat-like structure. Both ends thereof are supported by support electrodes @, and a conductive wire (transfer), u3, is electrically connected to the support electrode port and @.

The resistance heating element (7) and the support electrode u2. @ is support member 0
4, (14) is rotatably supported within the aluminum deposition chamber (6b) of the vacuum envelope (6), and connected to a drive motor (IQ) via a gear train αef.

On the other hand, a shield Uη is detachably attached to the side of the resistance heating element (7), and a shield support plate (7) is arranged.

(2) Remove the cover of the drive unit.

The vacuum deposition of the light-reflecting metal, aluminum 4, used in this example is done by the same conventional procedure, except that the glass face plate to be deposited (
At the time when υ is carried into the aluminum deposition chamber (6b), the degree of vacuum in the deposition chamber (6b) is low, and the resistance heating element (
The temperature of 7) is around 1 ooo'c. Even though the degree of vacuum is not sufficient, the heating surface (7A) of the resistance heating element (7), which is the evaporation source (5), is oriented toward the fluorescent surface of the glass 7 ace plate (υ). , heating surface (7A
) The aluminum melt remaining in the recess (7a) is deposited on the inner surface of the intermediate film (3), forming an undesirable deposited film as described above.

Therefore, when the glass face plate (υ) is transported into the aluminum deposition chamber (6b), the resistance heating element (7) is rotated by the drive motor ul, and the heating element is rotated as shown by the imaginary line (A) in FIG. state, i.e. - resistance heating element (7
) heating lII] (7A) is directed toward the shield aη direction,
It is oriented in a direction that does not face the glass face plate (the fluorescent surface of υ, the laminate phosphor film (2), and the intermediate film +31. Therefore, the aluminum melt remaining in the recess (7a) is evaporated. Even if it is, it will be deposited on the shield u7) and will not be deposited on the fluorescent surface.

When the wall thickness of the aluminum evaporation chamber (60) approaches the evaporation start value, a high level voltage is applied to the resistance heating element (7) through the conductive wire port 04 to raise the temperature. Next, the drive motor is activated to direct the resistance heating element (7) to the state shown by the solid line in FIG. 5, that is, the heating surface (7A) of the resistance heating element (7) faces the fluorescent surface. and hold it. Then,
Supply of the aluminum wire (9) is started, and the aluminum wire (9) is appropriately deposited for a predetermined period of time under high vacuum.

When the vapor deposition is completed, first, the voltage applied to the resistance heating element (7) is lowered to a low level voltage, and the supply of the aluminum wire (9) is stopped. Then, the drive motor μQ is operated to rotate the resistance heating element (7) again to the state shown by the imaginary line (A) in FIG. After that, the degree of vacuum in the aluminum vapor deposition chamber (6b) is lowered, and the processed glass face plate (υ is moved to the exit chamber (6C), and the glass face plate +1 to be processed next).
It will be transported to. Thereafter, the same operations as described above are repeated.

According to the examples, it was possible to sufficiently avoid vapor deposition in a low vacuum, which is the object of the present invention, and thus it was possible to form an aluminum vapor deposited film with good reflectivity. Moreover, there was no fall of molten aluminum due to the inclination (80° to 110°) of the resistance heating element (7), and the heat efficiency could be maintained at the same level as before. Furthermore, each device could be fixed in close contact with the water-cooled main body, so there were no particular problems.

Another advantage is that unnecessary evaporation can now be concentrated in one direction, making maintenance less of a burden.

Although the above embodiments have been described with respect to vapor deposition of aluminum, the method of the present invention can also be applied to other types of vapor W using a resistance heating element as an evaporation source.

〔Effect of the invention〕

As explained above, according to the present invention, the evaporation source is rotated except during necessary evaporation, and the evaporation film at low vacuum (at low vacuum) is prevented from being formed on the fluorescent surface. It is possible to obtain a phosphor screen having a high-quality vapor deposited film with good phosphor brightness, and it is also effective in saving labor on maintenance of vapor deposition equipment.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view illustrating the manufacturing process of the fluorescent surface part of a color picture tube, and FIG. 2 shows an example of a conventional vapor deposition apparatus.
A schematic configuration diagram when a tungsten coil is used as an evaporation source. Figure 3 is a perspective view of a port-shaped resistance heating element whose main component is boron nitride. Figure 4 is a diagram showing a port whose main component is electrified boron as an evaporation source. FIG. 5 is a front view schematically showing an example of the device necessary for the deposition of the present invention, and FIG. 6 is a plan view of the same. be. +1)...Glass 7 ace plate, (2)...phosphor film, (3)...intermediate film, (4)...aluminum thin film, (5)...evaporation source, (6b )...deposition chamber,
(7 units...Resistance heating element, (7A)...Heating surface. In addition, the same reference numerals in the figures indicate the same or corresponding parts. Fig. 1 Fig. 2 Fig. 3v!J Fig. 5 Fig. 6

Claims (1)

[Claims] (1) A method for forming a metal film on a fluorescent surface by vacuum-depositing a light-reflective metal thin film on the fluorescent surface of a picture tube that is intermittently transported into a deposition chamber using a plate-shaped resistance heating element as an evaporation source. The heating surface for melting and pooling the light-reflecting metal of the evaporation source faces the fluorescent surface of the picture tube only when the light-reflecting metal can be vapor-deposited at an appropriate pressure on the fluorescent surface of the picture tube; A method for forming a metal film on a fluorescent surface, characterized in that the evaporation source is directed in a direction in which the heated surface does not face the fluorescent surface of the picture tube, except when proper vapor deposition is possible.