JPH0722003B2 - Picture tube - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a color picture tube device used in a television receiver, a computer terminal, or the like.

[Conventional technology]

FIG. 3 is a partially cutaway view showing the internal structure of a picture tube having a rectangular screen which has been generally used as a shadow mask type color picture tube. In the figure, (2)
Is a glass panel, which is composed of a front glass panel section (2A) and a side glass panel section (2B). A fluorescent screen (3) is provided on the inner surface of the front glass panel portion (2A) of the glass panel (2), and a shadow mask (6) having a plurality of holes is arranged facing the fluorescent screen (3).
A funnel-shaped funnel (4) is separably sealed and adhered to an end face of the side glass panel portion (2B) of the glass panel (2) via a frit seal portion (7) made of frit glass. (5) is a neck portion including an electron gun (not shown).

In the picture tube (1) having the glass panel (2), the funnel (4) and the neck portion (5) in the shape of a glass vacuum container, scratches and the like on the glass panel (2) spread and are destroyed. It may lead to so-called implosion. As a means for preventing such implosion, a paper tape (8) is usually wound around the outer surface of the side glass panel (2B), and a metal band (10) is placed over the tape.
The mounting ear (9) was wound in a state of being clamped and tightened, and an explosion-proof treatment was performed to prevent the crack generated in the front glass panel (2A) from extending toward the frit seal (7).

FIG. 4 is a front view of the above-mentioned picture tube (1), which is used to define the X, Y, Z, and D axes for convenience of the following description.
Is a tube axis of the picture tube (1), and is a fluorescent screen (3)
It coincides with the center O.

Further, FIGS. 5 and 6 show a structure of a band-reinforcing type with a rim that has been generally adopted in a large-sized picture tube in the past. (11) in FIG. It consists of a rim part (11A) bent to the glass panel part (2A) side and a side rim part (11B) that covers the front glass panel part (2B). This reinforcing metal rim (11) is used as a glass panel (2). It is wound and filled with an adhesive (12) such as an epoxy resin between the outer surface of the side glass panel portion (2B), and a metal band (10) is wound and tightened, as shown in FIG. 3 above. It has a superior structure in terms of explosion-proof property. Incidentally, (21) is a glass cloth tape.
FIG. 7 shows an example applied to a 37-inch picture tube.

FIG. 8 illustrates the shrink-fitting method that is becoming more popular recently, replacing the tension band method described above. Each cross section of the X, Y, and D axes is shown as a single sheet. Shown in the figure. Here, the metal band (10) and the reinforcing metal rim (11) described above are replaced by an annular reinforcing body (20) made of, for example, an 0.8 mm-thick aluminum plated steel plate in the shrink fitting method. Side glass panel (2B) and annular reinforcement (2
0), for example, a glass cloth tape (not shown)
And protects the glass. The mounting ear (9) is welded to the annular reinforcement (20). The figure shows a typical one with mounting ears (9) at the corners.

The state in which the side glass panel portion (2B) is tightened by the tension band method or the shrink fitting method will be generally described below.

FIG. 9 shows the shape of the mold match line showing the maximum portion in the cross section perpendicular to the Z axis of the front glass panel portion (2B). Usually, the mold match line is a metal band (1
This is the part that can be tightened with (0). The figure shows only the first quadrant (upper right part of the fluorescent screen (3)). As shown in the figure, the upper part (lower part) has a radius of curvature RL, and the right (left) side part has a radius of curvature RS, and the corner part has a smaller radius of curvature r than RL and RS. They are smoothly connected, and the center of their radius of curvature is (x ₀ , y ₀ ). 10th
The figure shows only the corner part on an enlarged scale, RS and r
Is the contact point of D ₁ and the contact point of RL and r is D ₂ . Also the ninth
In the figure, the maximum positions of the front glass panel (2B) in the x and y axis directions are xM and yM, and the maximum diameter is d.

FIG. 11 illustrates the surface pressure that the front glass panel section (2B) receives when the side glass panel section (2B) is tightened with, for example, the metal band (10). In the figure, the magnitude of the surface pressure P is shown in the direction perpendicular to the surface of the side glass panel portion (2B). The surface pressure between yM and D ₂ is PL, the surface pressure from D ₁ to D ₂ is PD, and the surface pressure from D ₁ to xM is PS
And each has a constant load. That is, yM
Between and to D ₂ the metal band (10) clamps the part where the radius of curvature is constant at RL, and the other parts have the same reason.

The following is an example of a 37-inch picture tube. To give a concrete example, xM = 391.
8mm, yM = 0.309mm, (xo, yo) = (350.40mm, 262.80mm), R
L = 5521.9mm, RS = 5433.8mm, r = 35.0mm, θ ₁ ≈5.1 °, θ
₁ ≒ 3.6 °, PL = 5.060 × 10 ^-3 kgf / mm ² , PD = 7.983 × 10 ^- kgf
/ mm ² , PS = 5.142 × 10 ^-3 kgf / mm ² What should be noted here is that RL, RS >> r, so that the influence of the metal band (10) is that the corner portion is almost dominant. The above idea is basically the same regardless of the tension band method or shrink fitting method. Metal rims for reinforcement (11)
And only the metal bands (10) and annular reinforcements (20) are different.

By the way, in a picture tube having a normal design, the front glass panel portion (2A) is deformed inwardly by applying a vacuum. The deformation is such that a contour line having substantially the same shape (rectangular shape) as the rectangular fluorescent screen (3) is drawn. The broken line in FIG. 12 shows the contour line. As a result, the principal stress (tension) on the outer surface near the center of the square side (the direction along the X and Y axes in the front glass panel (2A)) is the diagonal axis direction of the fluorescent screen (3). It becomes larger than that of (D). The shaded area in Fig. 13 indicates the location where the principal stress is large. That is, FIG. 13 shows the principal stress on the outer surface of the picture tube when the picture tube (1) is evacuated. However, it is only in the first quadrant. A line along the tube wall of the picture tube in the Y-axis cross section including the tube axis Z is defined as SA, a line in the X-axis cross section is similarly defined as LA, and a line in the diagonal axis cross section is defined as DA. As can be seen in the figure, the peripheral portion of the front glass panel portion (2A), the front glass panel portion (2B), the vicinity of the frit seal portion (7), etc. are problems in terms of the strength of the picture tube. By the way, in the picture tube in a vacuum state, as described above, as a result of the front glass panel portion (2A) being mainly distorted inward, the sides of the rectangular screen are further expanded. as a result,
The inner surface of the corner as shown by the mesh in FIG. 14 receives tension. When the side glass panel (2B) is tightened with a metal ring (10) on the picture tube in such a vacuum state, as shown in FIG. 11, the side glass panel (2B) is The surface pressure is applied only to the corner portion in the diagonal axis direction (D), and the stress is hardly reduced in the high stress portion in the shaded portion shown in FIG. When the glass panel (2) of the picture tube (1) that is not in a vacuum state is tightened with a metal band such as a metal band (10) and an annular reinforcing body (20), the corners shown by the mesh in Fig. 14 are also shown. Tension is generated on the inner surface of the part. This is because the sides of the rectangular screen can be expanded.

Thus, in the past, the design of cathode ray tubes has been designed paying attention to the high level of stress on the outer surface of the cathode ray tube because its peak is almost the same as the stress due to the vacuum of the cathode ray tube even when considering the explosion-proof structure. It was

This is reasonable because the outer surface of the picture tube is predominantly scratched in the picture tube manufacturing process.

[Problems to be Solved by the Invention]

By the way, the recent technology of the picture tube has been focused on the realization of the enlargement. With the increase in size of the picture tube, the following inconveniences have been revealed.

That is, the ratio of the glass panel (2), the funnel (4) and the shadow mask (6) to the cost of the color picture tube as a whole is extremely high. For that reason, salvage is done when it becomes bad and anything that can be reused is reused. It is a fact that the defect rate generally increases as the size increases, but it is true that when salvaging the parts, the salvaged panel of a large picture tube of 27 ″ or more must be reused. It turns out that I can't stand the process of making a picture tube.
If the salvage of the above panel is reused, it will be destroyed in the manufacturing process of the picture tube.

What is important here is that the effect of the tightening force by the metal band (10) determined to satisfy the explosion-proof test of the safety standard is that a strong tension is applied to the inner surface of the cross section (DA) of the front glass panel (2B). Give birth. This tension is
Side glass panel part (2B) caused by vacuum shown in Fig. 13
About 60% larger than the tension value of the principal stress generated in the Y-axis cross section (SA) and X-axis cross section (LA); that principal stress is concentrated on the inner surface and at the corners (see Fig. 14). Is.

Further, as described above, the place where the tension is generated on the inner surface of the picture tube when the picture tube is evacuated is the corner portion as shown in FIG. This tension caused by the vacuum is
It is about 75% larger than the high stress area on the outer surface shown in Fig. 13.

Thus, on the inner surface of the corner portion, the stress due to the vacuum and the stress due to the tightening overlap each other, resulting in the highest tension.

In reality, the fact that the glass panel (2) tightened with the metal band (10) or the annular reinforcing body (20) cannot be reused by salvaging is a problem in the manufacturing process, for example, in the shadow mask (6). It is considered that the inner surface has smaller scratches due to attachment / detachment or the creation of the fluorescent screen (3), and as a result, the inner surface of the corner is likely to be damaged.

[Means for Solving the Problems]

In the present invention, in order to solve the problems described above,
The inner surface of the diagonal part of the side glass panel is protected by a protective layer that can be removed later to prevent scratches.

[Action]

The generation of stress (tension) on the inner surface of the corner of the side glass panel (2B) due to the tightening force of a metal band or the like, and to the vacuum is not a level at which it breaks by itself. In the manufacturing process, the thermal stress particularly in the heat treatment process is not at a level at which it is destroyed. In any case, it is not a level at which glass breakage occurs alone or by adding the above-mentioned three elements.

On the other hand, it is known that if there is a scratch on the glass surface, the glass breaks with a little tension.

Therefore, in the present invention, the above-mentioned three types of stresses cannot be eliminated, and therefore measures have been taken to reduce the occurrence of scratches that are highly effective in breaking glass.

〔Example〕

FIG. 1 shows an embodiment of the present invention and is a view of only the glass panel (2) as seen from the electron gun side. On the inner surface of the front panel glass part (2A) in the figure, a fluorescent screen (3) shown by a chain line can be seen. The shaded portion is a strengthening treatment portion (30) for scratches provided on the inner surface of the corner portion of the side glass panel portion (2B).

The strengthening treatment section (30) is a protective layer formed by brushing a material such as polyvinyl alcohol (PVA) on the inner surface of the corner before assembling the fluorescent screen (3), which is likely to scatter in the subsequent heat treatment step. Is.

In another embodiment, as shown in FIG. 2, a protective layer made of a silicone rubber cover (31) having a thickness of, for example, about 2 mm, which is detachable only at the corners, is provided before the screen manufacturing process, and the screen (3) is provided. It may be removed after the completion of the above and before the heat treatment step.

〔The invention's effect〕

According to the present invention, particularly in a large-sized picture tube, the picture tube is manufactured by reinforcing the inner corner portion of the side glass panel section (2B) which is likely to be scratched when the fluorescent screen (3) is created. For this reason, it is possible to reduce the occurrence of scratches in the main part even when salvaging or in a virgin picture tube, and enhance the reliability of the picture tube as a glass vacuum container.

[Brief description of drawings]

FIG. 1 is a view showing an inner surface of a corner portion of a side glass panel part showing an embodiment of the present invention, FIG. 2 is a view showing another embodiment of the present invention, and FIG. A side view of a partially broken picture tube, FIG. 4 is a view for explaining the coordinates of the front glass panel portion, FIG. 5 is a cross-sectional view for explaining the rim reinforcement type, and FIG. 6 is the reinforcement used in FIG. Fig. 7 shows a metal rim for use in a picture, Fig. 7 is a completed view of a picture tube reinforced by the metal rim for reinforcement shown in Fig. 6, Fig. 8 is a view for explaining a shrink fitting type, and Figs. 9 to 11 are tensions. Fig. 12 shows that the reinforcement of the band method and the shrink fitting method substantially applies the surface pressure to the front glass panel only at the corners, and Fig. 12 shows the deformation of the front glass panel when a vacuum is applied. FIG. 13 is a diagram for explaining the high stress portion of the outer surface of the picture tube in vacuum, FIG. Is a diagram illustrating the high places of the stress of the inner surface of the picture tube during the vacuum and during tightening. In the figure, (2) is a glass panel, (2A) is a front glass panel portion, (2B) is a side glass panel portion, (9) is a mounting ear, (10) is a metal band, and (11) is a reinforcing metal rim. , (20) is an annular reinforcement, (21) is a glass cloth tape, (30) is a strengthening treatment part, (31) is a rubber cover, and (Z).
Is the tube axis, and (P) is the surface pressure. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A picture tube having a glass panel composed of a front glass panel portion forming a rectangular screen on the inner surface thereof and a side glass panel portion forming a skirt,
A picture tube characterized in that an inner surface of a diagonal part of the side glass panel section is protected by a protective layer which can be removed in an appropriate manufacturing process of the picture tube.