JPH0365613B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a cathode ray tube, and particularly to a glass panel thereof.

[Technical background of the invention and its problems]

Generally, the envelope of a cathode ray tube consists of a glass panel with a phosphor screen on its inner surface, a funnel and a net connected to this glass panel, and an electron beam emitted from an electron gun placed inside the net facing the phosphor screen. The fluorescent screen is made to emit light by impact by deflection scanning. As shown in FIGS. 1 and 2, the glass panel of such a cathode ray tube is formed to have a substantially rectangular frame for transmitting a fluorescent screen, and its inner and outer surfaces face outward. It is composed of a face portion 2 which has a curved surface shape that protrudes from the side, and a skirt portion 3 which extends from the end of the face portion in the tube axis direction and is connected to a funnel (not shown). Note that FIG. 1 is a front view of the glass panel 1, and FIG. 2 is a side view of only the inner surfaces of the face portion 2 and skirt portion 3, and the right side of the center line is a vertical axis (V-
V) and the diagonal axis (D-D), and the horizontal axis (H-
H) are shown together. The radii of curvature in the vertical axis direction, horizontal axis direction, and diagonal axis direction of the inner and outer surfaces of the glass panel 1 are respectively R _V ,
R _H and R _D , and R _VO , R _HO and R _DO on the outer surface, to facilitate the design, R _V = R _H = R _D = R and R _VO =
It is common to have R _HO = R _DO = R _O , ie, a single radius of curvature. In addition, the end of the face part on the inner surface of the face part forms a substantially rectangular outer periphery (hereinafter referred to as the rectangular outer periphery of the inner face part), and such a rectangular outer periphery has four sides and these sides. Consists of smoothly continuous corner parts. The four sides are actually slightly curved to form a curved line. Now, when viewed from the viewer's side, such a face part should be as flat as possible, and should be 1/1/2 of the maximum effective length including the vertical axis of the rectangular outer periphery of the inner surface of the face part.
2. 1/2 of the maximum effective length including the horizontal axis and 1/2 of the maximum effective length including the diagonal axis are S _V , S _H and S _D , respectively.
It is said that it is most preferable that S _V :S _H :S _D =3:4:5, that is, the vertical, horizontal, and diagonal ratios of the screen are 3:4:5. However, when the cathode ray tube envelope is evacuated to a high vacuum, the face part receives strong stress inward due to the pressure difference with the outside atmospheric pressure. There is a danger that it could easily implode as the origin. The simplest means to prevent this implosion is to increase the wall thickness of the glass panel, but excessive increase in wall thickness is undesirable as it increases weight and cost. Therefore, the conventional face part has no choice but to have a radius of curvature that projects further outward, and the rectangular face part, including the corner parts, has a rounded shape as a whole, which is not visually desirable. It was hot. for example
An example of the design of the face section of a 14-inch cathode ray tube (the maximum diameter of the diagonal axis of the rectangular outer circumference of the inner surface of the face section is 13 inches) is as follows: R _V = R _H = R _D = R551mm, R _VO = R _H.O.
= R _DO = R _O = 575 mm, S _V = 105.3 mm, S _H = 140.4 mm and S _D = 166.7 mm are adopted. An example of the design of the face section of a 26-inch cathode ray tube (the maximum diameter of the diagonal axis of the rectangular outer periphery of the inner surface of the face section is 25 inches) is as follows: R _V = R _H = R _D = R = 1034 mm, R _VO = _RHO =
R _DO = R _O = 1100 mm, S _V = 197.9 mm, S _H = 263.9 mm and S _D = 313.2 mm are adopted. both of them
The ratio of S _V :S _H :S _D is 3:4:4.75 in all cases, and the diagonal in particular has to be shortened, giving a striking visual sense.

[Purpose of the invention]

The present invention provides a cathode ray having a face portion which flattens the radius of curvature of the face portion as much as possible to give the most visually favorable impression when the vertical, horizontal and diagonal ratios of the face portion are substantially 3:4:5. The purpose is to provide pipes.

[Summary of the invention]

In the present invention, the radius of curvature of the inner surface of the face portion including the vertical axis direction, horizontal axis direction, and diagonal axis direction is
R _V , R _H and R _D , and 1/1/2 of the maximum effective length including the substantially vertical axis of the rectangular outer periphery of the inner surface of the face portion.
2. 1/2 of the maximum effective length including the horizontal axis and 1/2 of the maximum effective length including the diagonal axis are S _V , S _H and S _D , respectively.
Then, the rate of change of the curved surface from the center of the face part to the end of the diagonal axis, from the center of the face part to the end of the horizontal axis, and from the center of the face part to the end of the vertical axis is 0.06R _D −√(R _D ) ² −(S _D ) ² /S _D 0.12 and 0.05R _H −√(R _H ) ² −(S _H ) ² /S _H 0.10 0.04R _V −√(R _V ) ² −(S _V ) ² /S _V 0.08 This is a cathode ray tube in which the ratio of S _V , S _H and S _D is substantially 3:4:5, and the face portion is made flatter.

[Embodiments of the invention]

The present invention will be explained in detail below. 3 to 7 are for conceptually explaining the present invention, and FIG. 3 corresponds to FIG. 1, and FIG. 4 corresponds to FIG. 2. This figure is shown for comparison of the curvature radii of FIG. 2 and FIG. Further, in FIGS. 3 and 4, all the symbols indicating the radius of curvature and length corresponding to FIGS. 1 and 2 are indicated by the same symbols as used in FIGS. 1 and 2. FIG. 5 is a perspective view of only the inner surfaces of the face portion 2 and skirt portion 3, and FIGS. 6a to 6c correspond to FIGS. 4 and 5, and extend from the center of the face portion to each axial end. It shows the cross section of the face part of. Further, FIG. 7 is a schematic diagram for explaining the rate of change of the curved surface of the inner surface of the face portion.

In carrying out the present invention, the face part
The S _V , S _H and S _D ratios should be substantially 3:4:5, and the areas that should be used as indicators for making the curve of the face part flatter are from the center of the face part to each axial end. It is the rate of change of the curved surface. That is, as shown by ΔD', ΔH', and ΔV' in FIG. 5, the screen gradually dips and becomes rounded from the center of the face section to each axial end, giving a visually striking sense of discomfort. Generally, as shown in Figure 7, the intersection between a point (Q) where a circle with radius R intersects with an axis (Z) passing through the center (O) and a point (P) on the circumference that is a distance x away from the axis (Z) is The distance h along the axis (Z) can be expressed as:

h=R−√ ² − ² (1) Therefore, as shown in Fig. 5, the amount of depression ΔD′, ΔH′, and ΔV along the tube axis (Z) from the center of the inner surface of the face part to each axial end ' is shown in Figure 6a,
R _D − along the diagonal axis (D) as shown in b, c
√ _D ² − _D ² , R _H −√ _H ² − along the horizontal axis (H)
S _H ² , along the vertical axis (V) can be expressed as R _V −√ _V ² − _V ² . Here, the rate of change of the curved surface from the inner surface of the face part to the ends in the diagonal axis, horizontal axis, and vertical axis directions is ΔD, ΔH, and ΔV, and ΔD′, ΔH′, and ΔV′ are S Defined as the value divided by _D , S _H and S _V , their correlation is ΔD=R _D −√(R _D ) ² −(S _D ) ² /S _D (2) ΔH=R _H −√ (R _H ) ² − (S _H ) ² /S _H (3) ΔV=R _V −√(R _V ) ² −(S _V ) ² /S _V (4)

That is, the question is what state of S _V , S _H and S _D and ΔV, ΔH and ΔD is visually preferable. Therefore, in this case, when the ratio of S _V , S _H and S _D is substantially 3:4:5 and the face portion is more flattened, which is close to the so-called visually preferable state, the above ( ΔV shown by equations 2) to (4),
The problem is what values ΔH and ΔD should be set to. In addition, the so-called explosion-proof property that prevents implosion at this time also becomes a problem.

As a result of various considerations and studies from the above viewpoint, the inventor first determined the ratio of the length and width of the face portion, that is,
When the ratio of S _V and S _H is 3:4 and it is horizontally long, ΔD contributes to the flattening of the face portion visually, and the maximum degree of contribution is that flatness can be achieved just by satisfying this ΔD. It was confirmed that the contribution of ΔV was the smallest, followed by ΔH.

In this state, when the ratio of S _V , S _H and S _D is substantially 3:4:5 and the radius of curvature of the face is made larger and flatter than before, ΔD is within 0.12 and ΔH is It has been found that when ΔV is within 0.10 and ΔV is within 0.08, the face portion visually feels flat and gives a favorable impression. Specifically, we first fabricated a color picture tube using a glass panel with varying screen shapes ΔD, ΔH, and ΔV, and 10 observers (A ~
J) conducted a subjective evaluation experiment. The experiment was conducted with an observer hanging a 28-inch color picture tube on a chair at a distance of 2 m. The evaluation category is the conventional 26-inch screen (R _V = R _H = R _D = 1034 mm)
Based on this, the following was established.

I don't feel flatness 0 points I feel a little flatness 1 point I feel quite flatness 2 points I feel very flatness 3 points First, ΔD, which has a large contribution to flatness, is changed, and ΔH and ΔV are changed from the conventional values. They were evaluated in the same way.
As a result, in the case of a design in which ΔD was set to 0.14 by making R _D slightly larger than the conventional design (R _D =1200 mm), as many as four observers did not feel flatness.
(The total score was 8 points), whereas the design made ΔD 0.12 by further increasing R _D (R _D =
1390mm), all of them felt that it was a little flat (total score was 16 points), and ΔD of 0.12 or less, which is the majority of points out of 30, was considered good.

Next, change ΔH and set ΔD to the upper limit of 0.12 (R _D =
1390mm), and ΔV was kept the same as before. ΔD
When changing ΔH within 0.12, everyone feels that it is a little flat (everyone has 1 point or more), so when ΔH is changed in addition to ΔD, quite a few everyone one rank higher feels that it is a little flat. The design was good, with a feeling of fairly flatness (everyone scored 2 or more). As a result, everyone felt that the design with R _H of 1325 mm and ΔH of 0.100 was fairly flat (total score was 23 points), and the design with ΔH of 0.10 or less was even better.

Further change ΔV, and set ΔD to the upper limit of 0.12 (R _D =
1390 mm), and ΔH was evaluated with the upper limit of 0.10 (R _H =1325 mm). In this case, since ΔD and ΔH have good values, it can be determined that a design in which most of the people one rank higher feel extremely flat (most of them score 3 points) is good. As a result, most observers felt that the design with R _V of 1240 mm and ΔV of 0.080 was very flat (total score was 27 points), and the design with ΔV of 0.08 or less was extremely good.

Incidentally, in the aforementioned 14-inch and 26-inch cathode ray tubes, the ratio of S _V : S _H : S _D is 3:4:4.75, and the values of equations (2) to (4) above are is 14 inch type, ΔD≒
0.155, ΔH≒0.130, ΔV≒0.097, and the 26-inch model shows ΔD≒0.155, ΔH≒0.130, and ΔV≒0.097, respectively, giving a remarkable sense of discomfort. Visually, the rectangular outer circumference of the inner surface of the face part is 3:4:
5 ratio and safe flat state, i.e. ΔD=ΔH=
The case where ΔV=0 is most preferable, but from the viewpoint of explosion protection, it is necessary to significantly increase the thickness of the glass panel including the face portion. In other words, it is possible to create a completely flat glass panel by making the wall thickness of the glass panel extremely thick, especially at the face part, but this is clearly not practical considering the manufacturing conditions due to increased weight, cost, and the optical properties of the face part. is not desirable.
From this point of view, in order to avoid deteriorating the explosion-proof properties without significantly increasing the wall thickness of the glass panel,
The limits for ΔD are 0.06, 0.05 for ΔH, and 0.04 for ΔV. That is, from the above considerations, ΔD, ΔH, and ΔV need to be 0.06ΔD0.12 (5), 0.05ΔH0.10 (6), and 0.04ΔV0.08 (7).

From an explosion-proof perspective, the stress applied to the envelope of a cathode ray tube by atmospheric pressure is applied toward the inside of the envelope at the face and funnel sections, and conversely toward the outside of the envelope near the rectangular outer periphery of the face. Adds stress. Therefore, since the vicinity of the rectangular outer periphery of the face portion is the area where the greatest stress and strain is applied, it is also effective to tighten the skirt portion more strongly with a metal band or the like.
It is also effective to mainly strengthen the vicinity of the rectangular outer periphery of the face portion, and therefore it is also effective to increase the wall thickness toward the ends of the face portion. For this purpose, the values of R _VO , R _HO and R _DO should be made larger than R _V , R _H and _RD . In this case, the outer surface of the face portion becomes more flattened when viewed from the viewer's side, giving a more favorable effect.

In addition, in the above explanation, R _V , R _H , R _D and
R _VO , R _HO , and R _DO are all expressed by a single radius of curvature, but in the present invention, one radius of curvature, for example, _R Needless to say, this also includes the case of a compound radius of curvature. In such a case, for example, the value of the approximate average radius of curvature when the composite radius of curvature is approximately expanded into a series may be used as one radius of curvature in the present invention. In other words, as shown in Fig. 8, the radius of curvature changes by R ₁ in the center of the face portion 2, that is, in the area from the tube axis (Z) to the end of the face portion and close to the tube axis (Z), and as it approaches the end of the face portion, the curvature changes to a different radius. When a curved surface is formed with a radius of R ₂ , the tube axis (Z) between the center point (Q) of the face part and the point (P) corresponding to 1/2 of the maximum effective length of the face part.
The average radius of curvature R obtained from equation (1) may be taken as the radius of curvature in the present invention.

Example 1 R _V , R _H and R _D of a 15-inch cathode ray tube (the maximum diameter of the diagonal axis of the rectangular outer circumference on the inner surface of the face is 14 inches)
Let R _VO , R _HO and R _DO all have the same radius of curvature,
S _V , S _H and S _D were set as shown below.

R _V = R _H = R _D = R = 1300mm R _VO = R _HO = R _DO = R _O = 1400mm S _V = 106.7mm S _H = 142.2mm S _D = 177.8mm In the above case S _V (106.7): S _H (=142.2): S _D (=
177.8) = 3:4:5, and the above formula (2) to
ΔD, ΔH, and ΔV shown in equation (4) are ΔD≒0.069 ΔH≒0.055 ΔV≒0.041, which are within the lower limit range of the above-mentioned equations (5) to (7). Regarding explosion-proof properties, the radius of curvature R _O of the outer surface of the face part is made larger than the radius of curvature R of the inner surface, and the wall thickness distribution of the face part is made larger toward the ends. It was possible to make the stress values in the vicinity equivalent to the conventional ones.
Therefore, in this example, explosion-proof characteristics equivalent to those of the conventional glass panel were obtained with a slight increase in the weight of the glass panel.

Example 2 As in Example 1, each value of the face portion of a cathode ray tube of 28 inch type (the maximum diameter of the diagonal axis of the rectangular outer periphery of the inner surface of the face portion is 26 inch type) was selected as follows.

R _V = 1300mm R _H = 1435mm R _D = 1490mm R _VO = R _HO = R _DO = R _O = 1700mm S _V = 197.1mm S _H = 262.8mm S _D = 328.5mm In the above case S _V , S _H and S The ratio of _D is 3:4:5 as in Example 1, and ΔD, ΔH, and ΔV shown in equations (2) to (4) above are ΔD≒0.112 ΔH≒0.092 ΔV≒0.076, and as described above. is within the upper limit range of equations (5) to (7). In addition, from the perspective of explosion-proof properties, the face part is made flatter and R _V , R _H and R _D are made different.
Moreover, it is advantageous because the wall thickness at the end of the face in the vertical axis direction is the largest.As a result, by increasing the wall thickness of the entire face by about 1 mm, the same explosion-proof properties as before can be achieved. I was able to get it.

〔Effect of the invention〕

As described above, according to the present invention, the vertical, horizontal and diagonal effective dimensions of the face portion are substantially 3:4:5.
In addition, the curved surface of the face portion can give an extremely flattering visual impression,
A useful cathode ray tube having a substantially rectangular face including a color picture tube can be provided.

[Brief explanation of drawings]

1 and 2 are schematic diagrams showing the front and side cross sections of a glass panel of a cathode ray tube, and FIGS.
5 is a perspective view of the inner surface of the glass panel, and FIG.
Figures a to 6c are cross-sectional views of the glass panel in the diagonal, horizontal, and vertical axis directions, Figure 7 is a schematic diagram for explaining the rate of change of the curved surface of the inner surface of the face, and Figure 8 is the curvature. It is a schematic diagram for explaining a radius. 1...Glass panel, 2...Face portion, 3...
…Skirt portion, R _V … Radius of curvature including the vertical axis direction of the inner surface of the face portion, R _H … Radius of curvature including the horizontal axis direction of the inner surface of the face portion, R _D … Including the diagonal axis direction of the inner surface of the face portion Radius of curvature, S _V ... 1/2 of the maximum length of the rectangular outer periphery of the inner surface of the face section, including the substantially vertical axis, S _H ... The maximum length of the rectangular outer periphery of the inner surface of the face section, including the substantially horizontal axis 1/2 length, S _D
... 1/2 of the maximum length of the rectangular outer periphery of the inner surface of the face section, including the diagonal axis.

Claims (1)

[Scope of Claims] 1. Consisting of a curved face portion having a substantially rectangular shape and having a fluorescent screen on at least the inner surface, and a skirt portion extending from the end of the face portion,
In a cathode ray tube having a glass panel in which each side of the rectangular outer periphery formed by the end of the face part and each corner part connecting each side part are each formed into a curved surface, the vertical axis direction of the inner surface of the face part , the radius of curvature including the horizontal axis direction and the diagonal axis direction is R _V , R _H and R _D respectively, and includes the substantially vertical axis of the rectangular outer periphery formed by the end of the face portion of the inner surface of the face portion. 1/ of maximum effective length
2. When 1/2 of the maximum effective length including the horizontal axis and 1/2 of the maximum length including the diagonal axis are S _V , S _H and S _D , respectively, 0.06R _D −√(R _D ) A cathode ray tube characterized by having the following relationship: ² − (S _D ) ² /S _D 0.12. 2. The cathode ray according to claim 1, wherein R _H and S _H of the glass panel have the following relationship: 0.05R _H −√(R _H ) ² −(S _H ) ² /S _H 0.10 tube. 3. Claim 1 or 2, characterized in that RV _and S _V of the glass panel have a relationship of 0.04R _V −√(R _V ) ² −(S _V ) ² /S _V 0.08 Cathode ray tube as described in section. 4. The cathode ray tube according to claim 1, wherein S _V , S _H and S _D of the glass panel have a substantially 3:4:5 relationship. 5. Claim 4, characterized in that the value of the radius of curvature of the outer surface of the face portion including each axial direction is larger than the value of the radius of curvature of the inner surface of the face portion including each axial direction. cathode ray tube. 6. Claim 5, characterized in that the wall thickness near the end of the face portion in the vertical axis direction is larger than the wall thickness near the end portion of the face portion in the horizontal axis direction and the diagonal axis direction. The cathode ray tube described.