JPS6124780B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a color cathode ray tube.

Generally, a color cathode ray tube consists of a panel section, a funnel section, and a neck section.
As shown in the figure, a shadow mask 1 is disposed and engaged with the inner surface of a panel 7, and a fluorescent film 8 is coated and formed on the inner surface of the panel in opposition to this shadow mask.

Conventionally, a shadow mask is manufactured by first cleaning a press-molded frame 3 and then blackening the atmosphere to form a blackened film 6 of triiron tetroxide on the surface. Panel clip 4 was made by press forming, cleaning and welding in the same manner as above.
Combine and weld the panel pins and the frame facing each other. Next, a flat mask having a large number of pores is press-molded into a spherical surface and cleaned, and then the shadow mask main body 2, which has a blackened film 6 of triiron tetroxide formed on its surface by blackening the atmosphere, is placed at a constant distance from the inner surface of the panel. The frames were combined and welded, and finally a completed shadow mask was obtained by passing through a strain relief heat treatment furnace to remove each weld strain.

However, at present, welding of the spring clip, welding of the spring clip to the frame, and welding of the frame to the shadow mask body is performed by electric resistance welding. Furthermore, a heat treatment furnace is required to remove welding distortion after combination welding before coating the fluorescent film. Furthermore, in order to remove press molding distortion, prevent rust during the cathode ray tube manufacturing process, and improve radiance, the frame and shadow mask body are separately atmosphere-blackened, and the surface is blackened with triiron tetroxide. After the film is formed, the frame and the shadow mask body are welded, so the blackened film near welding point 5 has already peeled off at the initial stage, and a large amount of welding splash is generated due to the blackened film. It was extremely difficult to hold back.

The generation of welding splash or the peeling off of the blackened film not only causes clogging of the shadow mask having a large number of pores, but also becomes a major factor in reducing the withstand voltage characteristics of color cathode ray tubes.

Further, individual atmosphere blackening and post-assembly strain relief heat treatment require large equipment and large amounts of power, and their proportion in the manufacturing cost of color cathode ray tubes cannot be ignored.

The present invention provides a high-quality color cathode ray tube that is free from the generation of welding splash and peeling off of the black film, and at the same time simplifies the cutting process and provides an inexpensive manufacturing method.

Hereinafter, one embodiment of the invention will be described with reference to the process diagram of FIG. 4 and FIG. 5.

In the present invention, in the manufacturing process of color cathode ray tubes, we have focused on the fact that the set temperature of the atmosphere blackening furnace is close to the set temperature of the heat treatment furnace for removing distortion of the shadow mask, which is performed before coating and forming the fluorescent film, and we It was decided that they should be carried out at the same time.

Specifically, frame 3 after press molding and cleaning
The spring clip 4, which was press-formed, cleaned, and welded, was assembled and welded facing the panel pin.
Next, the shadow mask main body 2 press-molded into a spherical surface is cleaned, combined with the frame and welded, and then the surfaces of the shadow mask main body 2 and the frame 3 are coated with four A blackened film 6 of iron trioxide is formed to obtain a completed shadow mask 1. This shadow mask 1 can be immediately incorporated into the inner surface of the panel and proceed to the fluorescent film coating and forming process. According to this method, welding and assembly are performed with no oxide film (blackened film) formed on the surface, so not only is there no welding splash, but also a blackened film is formed on the 5 welding points afterwards. Since it is sufficiently formed, there is no peeling off, and it is also easier to manage welding conditions (4 electrode replacement, welding strength, etc.). Furthermore, the atmosphere can be blackened by combining the atmosphere blackening and heat treatment to remove welding distortion and welding distortion after forming the unit, which is conventionally done by individually blackening the atmosphere and heat treating it after welding distortion. As shown in the figure, the blackened film does not become red rust due to the welding strain relief heat treatment, and the processing capacity of the atmosphere blackening furnace is approximately twice that of the conventional one.
In addition, a welding strain relief heat treatment furnace is not required, which greatly simplifies the manufacturing process and reduces costs.

As a result of various experiments, it has been found that there is an optimum temperature for the furnace setting during atmosphere blackening according to the present invention, and the range is from 440° to 560°C. If the temperature is below this temperature, the blackened film that is formed will not be sufficiently thick as required in the subsequent process, and the distortion of the shadow mask will not be completely removed. If so, the spring clip and the shadow mask body will be deformed, and the shadow mask will not be able to be properly positioned and engaged with the inner surface of the panel when the tube is completed.

The atmosphere referred to here may be any atmosphere in which a blackened film of triiron tetroxide is formed, and the types of atmosphere include steam, combustion gas, CO ₂ gas, N ₂ gas containing residual oxygen, and the like. There are mixed gases, etc.

A shadow mask treated at the above temperature is placed and engaged with the inner surface of the panel, and a fluorescent film is directly formed.After that, when a finished tube is made through the normal color cathode ray tube manufacturing process, there is no loss of characteristics, and rather durability. It has been proven that the voltage characteristics and mask clogging are good.

As described above, according to the present invention, there is an advantage that not only a high quality color cathode ray tube can be obtained, but also costs can be reduced by simplifying the process.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a panel section to explain a color cathode ray tube, Fig. 2 is a process diagram showing a conventional method, Fig. 3 is an assembly diagram of a conventional shadow mask, and Fig. 4 is an embodiment of the present invention. FIG. 5 is a block diagram showing a shadow mask according to an embodiment of the present invention. In the figure, 1 is a shadow mask, 2 is a shadow mask body, 3 is a frame, 4 is a spring clip, 5 is a welding point, 6 is a black film, 7 is a panel, and 8 is a fluorescent film. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In a method for manufacturing a color cathode ray tube comprising a fluorescent film coated on the inner surface of a panel and a shadow mask disposed and engaged with the inner surface of the panel opposite to the fluorescent film, each component of the shadow mask is press-molded, The process of cleaning and assembling, the process of blackening the atmosphere at 440°C to 560°C after assembly to form a completed shadow mask with a blackened film of triiron tetroxide, and the process of placing the shadow mask on the inner surface of the panel. A method for manufacturing a color cathode ray tube comprising the steps of coating and forming a fluorescent film on the inner surface of the panel.