JPS63150832A - Manufacture of explosion-proof type cathode-ray tube - Google Patents

Abstract

PURPOSE:To correctly fit a metal band having a patch welding section and manufacture an explosion-proof type cathode-ray tube easily and reliably by holding the metal band for a fixed time after heating it and shrinkage-fitting it to the envelope of the cathode-ray tube. CONSTITUTION:When an enclosed circular metal band welded with a patch 21 at its end 20 is held for a fixed time after being heated, the band-shaped section of the band and the welding section of the patch 21 are made almost the same temperature. When this band uniformly expanded over the whole periphery is shrinkage-fitted to the envelope of a cathode-ray tube, the envelope is not brought into contact with the band, and the explosion-proof type cathode- ray tube is manufactured easily and reliably.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a method of manufacturing an explosion-proof cathode ray tube.

(#: Previous technology) A cathode ray tube such as a color picture tube, which has an envelope made of glass and has a large oil surface, is shown by the dashed line (1) in Figure 3.
As shown in , since the envelope (2) is evacuated to a high vacuum, the center of the panel (3) is depressed due to atmospheric pressure, and the side wall is deformed to protrude outwards, causing a slight deformation. May implode due to thermal or mechanical shock. In order to prevent this implosion, it is well known that such cathode ray tubes are provided with explosion-proof means.

As shown in Figures 4 and 5, one type of explosion-proofing means is to wrap glass cloth tape or the like around the outer surface of the panel (3) of the color picture tube (5), which is evacuated to a high vacuum. A heat insulating layer (6) is provided, and a metal band (7) formed in a closed ring shape made of a band-like metal member is provided on the heat insulating layer (6).
There is one in which the metal band (7) is installed by heating and expanding, and the outer surface of the panel (3) is tightened by cooling and shrinking the metal band (7). In this case, the circumference of the metal band (7) at room temperature before heating is.

It is shorter than the circumference of the outer surface of the panel (3) and is configured to be expanded at least to the yield point when it is attached to the outer surface of the panel (3) and shrinks when cooled. In FIG. 5, (8) is a lug plate welded to the metal band (7) used when attaching the color picture tube to the cabinet.

FIG. 6 shows a mounting device for this metal band (7).

This metal band mounting device includes a bulb support stand (10) provided with a pad-like support part (9) for supporting a color picture tube (5), and a color picture tube placed on the bulb support stand (10). A vacuum suction device (12) having a vacuum chuck (11) that suctions the front surface of the panel (3) of the picture tube (5) and fixes the color picture tube (5) on the support part (9).
, a high frequency heating coil (13) disposed below the valve support stand (10), and this high frequency heating coil (13).
) for holding the metal band (7) so as to be heated from the inside, and a metal band chuck device (14) that is driven by a drive device so as to be freely raised and lowered.

In this device, the metal band (7) is attached by suctioning the color picture tube (5), on which the insulation layer (6) is previously provided on the outer surface of the panel (3), using the vacuum chuck (11). 9) Fix it on top. On the other hand, a metal band (
7) is supported, and the metal band (7) is heated from the inside to about 400 to 500°C by a high frequency heating coil (13). After this heating is stopped, the operating speed of the device is usually 0.5~
After 1 second, the drive device releases the metal band chuck device (14
) is raised as shown by the arrow, and the heated metal band (7) is positioned outside the heat insulating layer (6) on the outer surface of the panel (3) as shown by the dashed line. After this metal band (7) cools and contracts and tightens the side surface of the panel (3) from above the heat insulating layer (6), the metal band (7)
Cancel support for.

By the way, this method allows the metal band (7) to be attached to the panel (
When attached to the outer surface of 3), often a metal band (7)
may hit the panel (3) etc., making it impossible to install it correctly.

(Problems to be Solved by the Invention) As mentioned above, conventional methods for manufacturing explosion-proof cathode ray tubes include heating and expanding a metal band that has been previously formed into a closed ring shape, and attaching it to the outside of the front surface of the envelope. There is a method that tightens the outside of the front surface of the envelope by cooling contraction of the metal band, but if this is done using the conventional method, the heated metal band may hit the envelope, making it impossible to attach it correctly.

This invention was made to solve the above-mentioned problems, and when a metal band formed in a closed ring shape is heated and expanded and attached to the outside of the front surface of the cathode ray tube envelope,
The purpose is to make it possible to correctly and easily attach a metal band.

[Structure of the invention]

(Means for solving the problem) A metal band formed in a closed ring shape is heated and expanded by abutting the ends of band plate-like metal members and welding a patch plate to the abutted end portions. In the method for manufacturing an explosion-proof cathode ray tube, the expanded metal band is attached to the outside of the front surface of the cathode ray tube envelope, and the metal band is cooled and contracts to tighten the outside of the front surface of the cathode ray tube envelope, in which the metal band is heated. Thereafter, this metal band was held for a certain period of time to bring the band plate-like part and the welded part of the backing plate to almost the same temperature, and then it was attached to the outside of the front surface of the cathode ray tube envelope.

(Function) After heating the closed ring-shaped metal band as described above, and holding it for a certain period of time to bring the band plate-like part and the welded part of the patch plate to almost the same temperature, the front surface of the cathode ray tube envelope is heated. When attached to the outside, the metal band expands uniformly over its entire circumference, avoiding contact with the cathode ray tube envelope and allowing proper attachment.

(Example) The present invention will be described below based on an example with reference to one drawing.

In general, the metal band used in the manufacturing method of explosion-proof cathode ray tubes, in which a metal band formed in a closed ring shape is heated and expanded, and then cooled and contracted to tighten the outside of the front surface of the cathode ray tube envelope, is as shown in Fig. 2. A band-shaped metal member is formed into a predetermined shape by bending, the ends (20) are butted together, and a patch plate (2I) is placed on the outside of the butted end portions.
It is formed by welding. In the illustrated example, there is only one welded part of the caul plate, but multiple strips are formed by bending, their ends are abutted, and a caul plate is welded to each end abutment. , some have caul plate welds at multiple locations. As described above, the circumference of this closed annular metal band at room temperature is formed to be a predetermined dimension shorter than the circumference of the outer surface of the front surface of the cathode ray tube envelope to which it is attached.

Now, in the method for manufacturing an explosion-proof cathode ray tube of this example, first, the closed ring-shaped metal band is heated to about 400 to 500° C., for example, by disposing a high-frequency heating coil inside the metal band. Typically, this heating takes about 20-30 seconds. Next, after this heating is stopped, the metal band is held for a certain period of time, which will be described later. Thereafter, this metal band is placed on the outer surface of the front surface of the cathode ray tube envelope on which a heat insulating layer is formed by wrapping a glass cloth tape, etc., and as it shrinks on cooling, the metal band is placed on the outer surface of the cathode ray tube envelope from above this heat insulating layer. Tighten the outside of the front part of the container.

By the way, when the metal band formed into a closed ring shape by welding the caul plate (21) is heated, as shown in FIG. The changes in thermal expansion over time are different. In other words, the strip-shaped portion is
As shown in curve (23), the annular shape is displaced toward the outside as it is heated, but the welded part of the patch plate has a larger heat capacity than the strip-shaped part, and in particular, the metal band is heated from the inside with a high-frequency heating coil. When heating, use a patch plate (21)
Due to the attenuation of the high-frequency current that reaches , as shown by the curve (24), it is displaced inward at the initial stage of heating, and then reversed and rapidly displaced outward. Moreover, heating stop (SV
After 0FF), the displacement of the strip plate gradually decreases, but the displacement of the caul plate weld continues to increase thereafter.

As can be seen from the intersection (25) of both lines (23) and (24), after a certain period of time has elapsed after the heating has stopped, the temperature of the strip-like part and the welded part of the patch plate becomes almost the same, and the entire metal band is in thermal equilibrium. It was found that the mixture was in a uniformly expanded state. Note that the time required for this thermal equilibrium state to occur after heating is stopped varies depending on the design of the metal band, but for a normal metal band, it is within a range of 5 to 20% of the heating time.

Therefore, after heating the metal band, the metal band is not immediately attached to the outside of the front surface of the cathode ray tube envelope as in the conventional case, but is held for a certain period of time within the range of 5 to 20% of the heating time. If the plate part and the end butt part are brought to almost the same temperature before being attached to the cathode ray tube, the entire metal band expands uniformly.
It can be installed correctly without hitting the cathode ray tube envelope, etc., and the required explosion-proof cathode ray tube can be easily manufactured.

〔Effect of the invention〕

The ends of the strip-like metal members are butted together and a patch plate is welded to the end butts to heat and expand the metal band, which is formed into a closed ring. In the method for manufacturing an explosion-proof cathode ray tube, which is attached to the outside of the front surface of the CRT envelope and tightens the front outside of the CRT envelope by cooling shrinkage, when a metal band is heated and held for a certain period of time, the band plate-like part By attaching the metal band to the cathode ray tube with the welded part of the backing plate at almost the same temperature and the entire metal band expanded uniformly, the metal band can be attached correctly without hitting the cathode ray tube envelope, etc. explosion-proof cathode ray tubes can be easily manufactured.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining the present invention in detail, with FIG. 1 being a diagram showing changes in thermal expansion of a metal band over time, and FIG. 2 being a perspective view of the metal band. Fig. 3 is a diagram showing the deformation of a color picture tube due to atmospheric pressure, Fig. 4 is a front view showing the structure of an explosion-proof cathode ray tube, Fig. 5 is a plan view thereof, and Fig. 6 is a diagram showing a metal band on a color picture tube. FIG. 2 is a diagram showing the configuration of a mounting device for mounting. (21)...Packing plate

Claims (2)

[Claims] (1) A metal band formed into a closed ring shape by butting the ends of the band plate-like metal members and welding a patch plate to the butted end portions is heated and expanded, and the expanded metal band is heated and expanded. In a method for manufacturing an explosion-proof cathode ray tube, the metal band is attached to the outside of the front surface of the cathode ray tube envelope, and the metal band is tightened on the outside of the front surface of the cathode ray tube envelope by cooling contraction. A method for manufacturing an explosion-proof cathode ray tube, which comprises holding the metal band for a period of time to bring the band plate-shaped portion of the metal band and the welded portion of the backing plate to approximately the same temperature, and then mounting the metal band on the outside of the front face of the cathode ray tube envelope. (2) The method for manufacturing an explosion-proof cathode ray tube according to claim 1, wherein after heating the metal band, the metal band is held for a period of 5 to 20% of the heating time.