JPH06162929A - Manufacture of color cathode ray tube - Google Patents

Abstract

PURPOSE:To increase vacuum degree of a color cathode ray tube, and improve cathode electron emission characteristics by holding a specific temperature between processes of sealing, closing, and gas discharge. CONSTITUTION:A panel having a phosphor screen on an inner surface and a shadow mask facing the phosphor screen, and a funnel having a conductive film mainly comprising carbon on an inner surface are set in a sealing furnace 40 to be heated, and the panel and the funnel are sealed to each other by frit glass applied on sealing surfaces of the funnel. This is introduced into a sealer 41 on a transfer conveyer 43 as it is held at 100 deg.C or more, an electron gun is inserted into a bulb comprising the panel and the funnel, and a stem installed on the electron gun is welded inside a neck of the bulb to seal the electron gun. This is then introduced into an exhaust gas furnace 42 by a transfer conveyor 44 as it is held at 100 deg.C or more, and gas is discharged while it is heated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a color CRT, and more particularly to a method for manufacturing a color CRT capable of obtaining a color CRT having stable quality.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 4, a color cathode ray tube has a bulb composed of a glass panel 1 and a glass funnel 2 integrally joined to the panel 1, and the inner surface of the panel 1 has three colors. A phosphor screen 3 composed of a phosphor layer is formed, and a shadow mask 4 is mounted inside the phosphor screen 3 so as to face the phosphor screen 3. On the other hand, 3 electron beams 6 in the neck 5 of the funnel 2.
The electron gun 7 that emits is sealed, and the inner surface conductive film 9 containing carbon as a main component is formed from the inner surface of the large-diameter portion 8 of the funnel 2 to the inner surface of the portion adjacent to the large-diameter portion 7 of the neck 5. There is. Then, a deflection yoke mounted on the outside of the funnel 2 for the three electron beams 6 emitted from the electron gun 7
The phosphor screen 3 is deflected by a magnetic field generated by 11 and horizontally and vertically scanned to form a structure for displaying a color image.

Conventionally, such a color cathode ray tube is manufactured as follows.

A phosphor screen is formed on the inner surface of the panel, and a shadow mask is attached to the panel on which the phosphor screen is formed. On the other hand, an inner conductive film is formed by coating from the inner surface of the large-diameter portion of the funnel to the inner surface of the portion adjacent to the large-diameter portion of the neck. Next, frit glass is applied to the sealing surface (end surface on the large-diameter portion side) of the funnel on which the inner conductive film is applied, and the funnel to which the frit glass is applied and the phosphor screen are formed and The mounted panel is combined and heated, and the panel and the funnel are integrally sealed (bonded) with frit glass to form a valve composed of the panel and the funnel (sealing step). Next, an electron gun is inserted into the neck of the funnel, the stem attached to the electron gun is heat-welded to the neck, and the electron gun is sealed in the neck (sealing step). After that, the sealed valve of this electron gun is heated and exhausted while promoting gas release from the valve and the member inside the tube. Then, when the degree of vacuum in the bulb is sufficiently increased, the cathode of the electron gun is activated (exhaust step) to manufacture the device.

FIG. 5 shows an example of each of the steps of sealing, sealing and exhausting. In the figure, 13 is a sealing furnace in the sealing step, 14 is an inspection device for the sealed valve, 15 is a sealing machine in the sealing step, and 16 is a sealing machine.
Is an exhaust furnace in the exhaust process, 17 is a transfer conveyor between the sealing and sealing processes, and 18 is a transfer conveyor between the sealing and exhaust processes.

As described above, in the conventional method for manufacturing a color cathode ray tube, heating is performed in each step of sealing, sealing, and exhausting, but there is no heating between these steps and natural cooling occurs. CRTs are manufactured by repeating heating and cooling. However, if it is manufactured by repeating heating and cooling in this way, the valve and the pipe inner member will repeat gas release and adsorption each time.

In this case, most of the adsorbed and released gas is the inner conductive film containing carbon as a main component formed on the inner surface of the funnel. For example, the released gas amount is about 90% of the total released gas amount. is occupying. Moreover, the gas release peaks at around 150 to 180 ° C., as shown by the curve 20 in FIG. Of these, H ₂ O poisoning the cathode
Has a peak near 160 ° C. as shown by the curve 21.
Regarding CO _2, there are peaks near 150 ° C. and around 280 to 300 ° C. as shown by the curve 22. A curve 23 is a gas release curve for H ₂ and a curve 24 is a gas release curve for CO.

Further, from the glass such as the bulb, gas is released as shown by a curve 25 in FIG. This outgassing curve 26
As shown in, H ₂ O from the glass surface is the main, and
There is a primary peak near 0 to 170 ° C. Note that the curve
27 is CO ₂ and curve 28 is a release curve of other gases.

Therefore, in order to obtain a color CRT having a predetermined electron emission characteristic and a long life, it is necessary to sufficiently remove each gas emitted from the valve and various tube members in the exhaust step. If heating and cooling are repeated during manufacturing, the gas released from the valve and various internal members of the tube becomes unstable. For example vacuum technology:
According to Ryoji Ueda, Iwanami Zensho 204, p131-132, Fig. 8
The exhaust efficiency changes as shown in. That is, when the glass is baked at 400 ° C., then brought into contact with dry air for 3 minutes and then evacuated, as shown by a curve 29,
When it is baked at 400 ° C. and then left in the atmosphere for 15 hours and then exhausted, the exhaust efficiency decreases as shown by the curve 30.

Therefore, in the exhaust, it is necessary to set the heating temperature of the valve to 280 to 310 ° C. which is the second peak of CO ₂ or more, and to hold the time for a sufficient period of time, which reduces the exhaust efficiency. Repeated heating and cooling
This leads to cracks due to thermal stress during heating, which lowers the quality and yield of color CRT.

[0011]

As described above, the conventional color cathode ray tube is manufactured by heating in each step of sealing, sealing, and exhausting, but cooling is performed between these steps, and heating and cooling are repeated during manufacture. Has been done. However, if the glass is manufactured by repeating heating and cooling in this manner, the gas released from the glass bulb and the member inside the tube becomes unstable. Therefore, in the exhaust, the heating temperature of the valve is set to C
It is necessary to set the temperature to 280 to 310 ° C. or higher, which is the second peak of O ₂ , and to hold the time for a sufficient period of time, which reduces the exhaust efficiency. Repeated heating and cooling
There is a problem that it leads to cracks due to thermal stress at the time of heating, and the quality and yield of the color CRT deteriorate.

The present invention has been made in view of the above problems, and provides a method for manufacturing a color cathode ray tube which can stabilize the gas release characteristics from the valve and the member inside the tube and reduce cracks due to thermal stress during heating. The purpose is to

[0013]

A panel having a phosphor screen formed on the inner surface thereof and a shadow mask being mounted facing the phosphor screen, and a funnel having a conductive film containing carbon as a main component formed on the inner surface thereof. A sealing process for sealing the electron gun in the neck of the sealed funnel, and an exhaust process for exhausting the sealed valve of the electron gun. In the color cathode ray tube manufacturing method, the temperature of the bulb is maintained at about 100 ° C. or higher between the sealing step, the sealing step, and the exhaust step.

[0014]

As described above, when the temperature of the valve is maintained at about 100 ° C. or higher between the sealing, sealing, and exhausting steps, the carbon mainly applied to the inner surfaces of the valve and the tube inner member, especially the funnel, is mainly formed. Gas release from the conductive film as a component can be stabilized, and cracks in the valve due to thermal stress during heating can be reduced.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

As shown in FIG. 1, a phosphor screen is formed on the inner surface of a glass panel by a photo printing method. For example, for a phosphor screen having a light absorption layer, a photosensitive film containing polyvinyl alcohol (PVA) and ammonium dichromate (ADC) as main components is applied and formed on the inner surface of the panel, and the photosensitive film is passed through a shadow mask. After exposure and development, a resist film having a pattern corresponding to the electron beam passage holes of the shadow mask is formed on the inner surface of the panel. Next, a black light absorbing paint layer is applied and formed on the resist film, and then the light absorbing paint applied and formed on the resist film is peeled off to form a light absorbing layer having a pattern in which the resist film is inverted. To do. After that, the phosphor, PVA and the PVA were formed on the inner surface of the panel having the light absorbing layer formed thereon.
Then, a phosphor slurry layer containing ADC as a main component is formed by coating, and this phosphor slurry layer is exposed through a shadow mask and developed to form a phosphor layer of any one color. By repeating the formation of this phosphor layer for the three-color phosphor,
A three-color phosphor layer is formed. Further, the light absorbing layer and 3
A vapor deposition film of aluminum is deposited on the color phosphor layer to form a phosphor screen. A phosphor screen having no light absorption layer is formed by the steps after the formation of the three-color phosphor layer.

On the other hand, on the inner surface of the funnel-shaped funnel made of glass having a large diameter and on the inner surface adjacent to the large diameter of the neck,
A conductive film containing carbon as a main component is formed by coating. Further, frit glass is applied to the sealing surface (end surface on the large diameter portion side) of the funnel.

Next, the panel on which the phosphor screen is formed and the funnel on which the conductive film is formed are combined and placed in a sealing furnace for heating, and a panel is formed by frit glass applied to the sealing surface of the funnel. Sealing (joining) with the funnel (sealing process). Next, insert a separately assembled electron gun into the neck of the valve consisting of the panel and funnel sealed by the frit glass, and weld the neck and the stem attached to the electron gun to the electron gun. Seal (sealing step). Next, the sealed valve of this electron gun is put into an exhaust furnace and heated and exhausted (exhaust step). The cathode of the electron gun is activated when the inside of the valve reaches a high degree of vacuum in the latter stage of exhaust. Thereafter, the exhausted color CRT is subjected to getter flash, aging of the cathode, withstand voltage treatment, test adjustment, etc. to obtain a product.

In particular, FIG. 2 shows the flow of valves during the steps of sealing, sealing and exhausting in the above manufacturing method. In this figure, 40 is a sealing furnace, 41 is a sealing machine for sealing an electron gun, 42 is an exhaust furnace, and a valve is a transfer conveyor 43 from a sealing step to a sealing step, and a transfer conveyor 44 is used. It is transported from the sealing process to the exhaust process. In this case, in the manufacturing method of this example, a heating device is installed along the transfer conveyors 43 and 44, and after the heating device is taken out from the sealing furnace, it is supplied to the sealing machine, and by the sealing machine. The valve conveyed by the conveyors 43 and 44 is kept at 100 to 150 ° C. until it is put into the exhaust furnace after being sealed.

Table 1 shows the temperatures of various valves (59 cm, 66 cm, 68 cm flat square tubes) when the valves were transported while being kept at 100 ° C. between the sealing and sealing steps and the sealing and exhausting steps. For comparison, Table 2 shows the valve temperature in the conventional case which was performed without keeping the temperature between the steps. Measurement points a in Tables 1 and 2,
b and c are the temperatures of the outer surface of the valve 46 shown in FIG. 3, respectively, where point a is the point on the center of the panel 47 and point b is the panel 47.
And the point on the seal between the funnel 48 and the point c is the funnel 28
Is a point on the large-diameter portion 49 of.

[0021]

[Table 1]

[Table 2] As shown in Table 1, the temperature of the outer surface of the valve is slightly different depending on the position. Generally, the panel has the highest temperature and the seals and funnel flanks are lower. Even when the valve is transported while keeping the temperature between 100 ° C. between the sealing and sealing process and the sealing and exhausting process, the temperature of the outer surface of the valve is
It slightly decreases as the process progresses. However, if the valve is transported while keeping the temperature between 100 ° C. between the sealing and sealing step and between the sealing and exhausting step, the valve can be kept at a higher temperature than the conventional case shown in Table 2, and the temperature is the highest. Even at the decreasing exhaust furnace inlet, the temperature can be maintained close to 100 ° C.

When the valve is maintained at a temperature close to 100 ° C. in this manner, the conductive film having the largest amount of gas release is formed from the inner surface of the large diameter portion of the funnel and the inner surface of the portion adjacent to the large diameter portion of the neck. The outgassing is reduced and stabilized. Next, the amount of gas released from the inner surface of the valve, which releases a large amount of gas, is reduced and stabilized. In addition, the amount of gas released from the other members inside the pipe is reduced, and it is stabilized. As a result, in the exhausting process, the gas released from the valve and various in-tube members can be effectively removed, and the in-tube vacuum degree can be easily increased. This is because when the temperature of the valve is kept higher than that of the outside air, the inside of the valve becomes + pressure, which prevents entry of gases such as H ₂ O and CO _{2 which} have an adverse effect on the electron emission characteristics of the outside air, especially at high temperature. Therefore, the gas adsorption to various pipe members is reduced. As a result, an electron emission characteristic of the cathode is improved and a long-life color CRT can be obtained.

Furthermore, by keeping the temperature between 100 ° C. between the steps of sealing-sealing and sealing-exhaust as described above, the temperature change in the sealing step after sealing and the exhaust step after sealing can be reduced. ,
The effect of reducing cracks in the valve due to the temperature difference can be obtained.

[0024]

INDUSTRIAL APPLICABILITY In the method for manufacturing a color cathode ray tube,
The valve temperature is 100 ° C between the sealing, sealing, and exhaust processes.
When the above is maintained, it is possible to stabilize the gas release from the valve and the inner member of the tube, particularly the conductive film containing carbon as a main component formed by coating on the inner surface of the funnel. As a result, in the evacuation process, it is possible to effectively eliminate the gas emitted from the valve and various members inside the tube, easily increase the degree of vacuum inside the tube, and have a good cathode electron emission characteristic.
In addition, it can be a long-life color CRT. Further, it is possible to reduce the cracks of the valve due to the thermal stress caused by the temperature difference during heating.

[Brief description of drawings]

FIG. 1 is a flow chart for explaining a method for manufacturing a color CRT which is an embodiment of the present invention.

FIG. 2 is a diagram showing a flow of a valve during each process of sealing, sealing, and exhausting.

FIG. 3 is a diagram showing temperature measurement points on the outer surface of a bulb of a color cathode ray tube.

FIG. 4 is a diagram showing a configuration of a color CRT.

FIG. 5 is a diagram showing the flow of valves during each step of sealing, sealing, and exhausting in the conventional method for manufacturing a color CRT.

FIG. 6 is a diagram showing gas release characteristics of an inner conductive film formed by coating on the inner surface of a funnel.

FIG. 7 is a diagram showing gas release characteristics of a glass bulb.

FIG. 8 is a diagram showing a change in exhaust efficiency due to a change in gas release from a valve and a member inside a pipe.

[Explanation of symbols]

 43 ... transport conveyor 44 transport conveyor 46 ... valve 47 ... panel 48 ... funnel

Claims (1)

[Claims] 1. A panel on which a phosphor screen is formed on the inner surface and a shadow mask is mounted so as to face the phosphor screen, and a funnel on which an electrically conductive film containing carbon as a main component is formed is sealed on the inner surface. Color cathode ray tube comprising a sealing step of forming a bulb by means of a sealing process, a sealing step of sealing the electron gun in the neck of the sealed funnel, and an exhausting step of exhausting the sealed valve of the electron gun. The method for manufacturing a color CRT, characterized in that the temperature of the valve is maintained at about 100 ° C. or higher between the steps of sealing, sealing, and exhausting.