JPH0365612B2 - - 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 (hereinafter referred to as a curved line around the rectangular periphery). Now, when viewed from the viewer's side, such a face part should be as flat as possible, and should be 1/2 of the maximum effective length including the vertical axis of the rectangular outer periphery of the inner surface of the face part, and 1/2 of the maximum effective length including the horizontal axis. When 1/2 and 1/2 of the maximum effective length including the diagonal axis are S _V , S _H and S _D , respectively,
It is considered 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 inside of 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 protrudes further outward, and the rectangular face part, including the corner parts, has a rounded shape as a whole, which is visually undesirable. It was hot. For example, as an example of the design of the face part of a 20-inch cathode ray tube, R _V =
R _H = R _D = R = 792 mm, S _V = 151.7 mm, S _H = 202.2 mm
is adopted, and in this case the ratio of S _V : S _H : S _D is
The ratio is 3:4:4.75, and the diagonal in particular has to be shortened, giving a striking visual sense of discomfort.

[Purpose of the invention]

The present invention provides a cathode ray having a face part that flattens the curved surface of the face part as much as possible to give the most visually favorable impression when the vertical, horizontal and diagonal ratios of the face part 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.
When, the rate of change of the curve of the rectangular outer circumference of the inner surface of the face portion from the vertical axis end to the diagonal axis end, and the rate of change of the curve of the rectangular outer circumference of the inner surface of the face portion from the horizontal axis end to the diagonal axis end are , 0.04R _V × (S _D ) ² −R _D × (S _V ) ² /2 × S _H ×R _V ×R _D
0.08 and 0.03R _H × (S _D ) ² −R _D × (S _H ) ² /2 × S _V × R _H × R _D
By setting the ratio to 0.06, the ratio of S _V , S _H and S _D is substantially 3:4:5, and the cathode ray tube has a flattened face portion curved surface.

[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 are set to substantially 3:4:5, and the portion that should be used as an index for flattening the curve of the face portion forms the rectangular outer periphery of the inner surface of the face portion. This is the curved state of each side. In other words, since the screen gradually falls from the center of the face part to the end of each axis (ΔD', ΔH', ΔV'), each side forming the rectangular outer periphery of the inner surface of the face part also has a slope of ΔL',
As shown by ΔS', each side is curved and rounded from the vertical axis end to the diagonal axis end and from the horizontal axis end to the diagonal axis end, giving a visually striking sense of discomfort. Generally, as shown in Figure 7, the point (Q) and axis (Z) where a circle with radius R intersects with the axis (Z) passing through the center (O)
The distance h along the axis (Z) from a point (P) on the circumference that is a distance x away from the point (P) can be expressed as follows.

h=R- ^√2-2 Therefore, as shown in Fig. 5, the amount of depression of the inner surface of the face along the tube axis (Z) from the center of the inner surface of the face to each axial ^end is ΔD', ΔH', and ΔV ' is R _D −√ _D ² − D 2 along the diagonal axis (D) and R _H −√ _H ² − ^H along the horizontal axis ( _H ), as shown in Figure 6 a _, b, and c. ² , along the vertical axis (V)
It can be expressed as R _V −√ _V ² − _V ² .

Therefore, the changes in the curve from the vertical axis end to the diagonal axis end and from the horizontal axis end to the diagonal axis end, that is, the drop amounts ΔL' and ΔS' of this curve can be expressed respectively as follows.

ΔL′=ΔD′−ΔV′ ΔS′=ΔD′−ΔH′ Here, the rate of change of the curve from the vertical axis end to the diagonal axis end and from the horizontal axis end to the diagonal axis end, that is, the drop rate ΔL of this curve , and ΔS are defined as ΔL′ and ΔS′ divided by S _D , S _H and S _V , they become S _D /R _D <<1, S _H /R _H <<1 and
Since S _V /R _V <<1, approximately, ΔL=ΔL′/S _H = [{R _D −(R _D ² −S _D ² ) ^1/2 }−{R _V
−(R _V ² −S _V ² ) ^1/2 }]/S _H = [{R _D −R _D (1−(S _D /R _D ) ² ) ^1/2 }−{R _V −R _V
(1−(S _V /R _V ) ² ) ^1/2 }] / S _H ≒ [{R _D −R _D (1−(1/2)(S _D /R _D ) ² )}−{R _V −
R _V (1−(1/2)(S _V /R _V ) ² )}]/S _H = {(S _D ² /2R _D )−(S _V ² /2R _V )}/S _H = (R _V ×S _D
² −R _D ×S _V ² )/(2×S _H ×R _V ×R _D )……(1) Similarly, ΔS=ΔS′/S _V = [{R _D −(R _D ² −S _D ² ) ^1/2 }−{R
_H − (R _H ² − S _H ² ) ^1/2 }] / S _V ≒ (R _H × S _D ² − R _D × S _H ² ) / (2 × S _V × R _H × R _D )…
…(2) It can be expressed as:

That is, the question is ΔS, in other words, what state of the curve of each side including the corner of the rectangular outer periphery of the inner surface of the face portion 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 ( ΔL shown by equations 1) and (2),
The problem is what value ΔS 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 to S _H is 3:4 in the horizontal direction, it was confirmed that ΔL contributes more to flattening the face portion than ΔS visually.

In this state, the vertical, horizontal and diagonal ratio of the face portion, that is, the ratio of S _V , S _H and S _D is substantially 3:4:
5, and when the radius of curvature of the face part is made larger and flatter than before, ΔL is 0.08 or less and ΔS is 0.06.
It has been determined that the following cases give a visually pleasing impression that the face portion is flat. Specifically, we first manufactured a color picture tube using a glass panel with different screen shapes, ΔL and ΔS.
A subjective evaluation experiment was conducted by 10 observers (A to J) to determine what kind of value would indicate flatness. The experiment is
The observer hung a 21-inch color picture tube on a chair at a distance of 1.5 m. The evaluation category is the conventional 20-inch screen (R _V = R _H = R _D =
792mm) as the standard, and was determined as follows.

I don't feel flatness 0 points I feel a little flatness 1 point I feel a lot of flatness 2 points I feel very flatness 3 points First, we change ΔL, which has a large contribution to flatness, and keep ΔS the same as before. It was evaluated. As a result, by making R _V slightly smaller than before, ΔL
In the case of the design with R V = 0.105 (R _V = 600 mm), as many as 4 observers did not feel the flatness (total score was 8 points), whereas the design with ΔL of 0.08 by further reducing R _V (R _V = 475 mm), all of them felt that it was somewhat flat (total score was 16 points), and a ΔL of 0.08 or less, which is the majority of points out of 30, is considered good. Ta.

Next, change ΔS and set ΔL to the upper limit of 0.08 (R _V = 475
mm, R _D = 792 mm (same as conventional)).
When ΔL is changed, if it is within 0.08, everyone feels that it is a little flat (everyone has 1 point or more), so when ΔS is changed in addition to ΔL, everyone one rank above It can be judged that the design is good as it feels quite flat (everyone scored 2 or more). As a result, when R _H is 655 mm, ΔS
For designs with a value of 0.060, everyone felt that the design was fairly flat (total score was 23 points), and those with ΔS of 0.06 or less were even better.

By the way, the conventional R = 792mm, S _V = 151.7mm, S _H
= 202.2mm and S _D = 240.0mm, S _V : S _H : S _D =
At 3:4:475, ΔL=0.108 and ΔS=0.070.

Visually, the face part is a perfect rectangle,
That is, the case where ΔL=ΔS=0 is most preferable, but from the viewpoint of explosion protection, it is necessary to significantly increase the thickness of the glass panel. In other words, it is possible to create a completely rectangular glass panel by making the face part particularly thick, but this is clearly not practical due to manufacturing conditions such as increased weight, cost, and the light scattering properties of the face part. 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, ΔL should be
The limit for 0.04 and ΔS is 0.03. That is, from the above considerations, ΔL and ΔS need to be 0.04ΔL0.08 (3) 0.03ΔS0.06 (4).

From an explosion-proof perspective, the stress applied to the cathode ray sensitive envelope due to 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 area near 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 this area 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.

Furthermore, in order to facilitate the design of the face part,
The radius of curvature of each axis on the inner surface of the face part is all the same, that is, R _V = R _H = R _D = R, and S _V , S _H and
When the ratio of S _D is 3:4:5, it is expressed as 0.22S _D /R0.4 (5), and the ratio of the effective diagonal dimension of the face part to the radius of curvature of the inner surface of the face part is given by equation (5). As shown, the radius of curvature of the outer surface of the face portion may be appropriately selected in accordance with this R and the diagonal dimension (2S _D ).

The above equation (5) can be derived as follows.

In equation (1), R _V = R _D = R and S _V = (3/5) S _D , S _H =
(4/5) When S _D is substituted, ΔL=2S _D /5R. If this ΔL is substituted into equation (3) and rearranged, it becomes 0.22S _D /R0.4.

On the other hand, the same solution can be obtained from equation (2). That is,
In equation (2), R _H = R _D = R and S _H = (4/5) S _D , S _V =
Substituting (3/5) S _D gives ΔS=3S _D /10R. If this ΔS is substituted into equation (4) and rearranged, it becomes 0.22S _D /R0.4.

In the above explanation, the radius of curvature of the inner and outer surfaces including the vertical axis direction, horizontal axis direction, and diagonal axis direction of the face part is R _V , R _H , R _D and R _VO , R _HO , R _DO
Although all of these are expressed as a single radius of curvature, the present invention also includes cases where one radius of curvature, for example R _V , is a so-called compound radius of curvature in which the radius of curvature gradually changes from the center of the face part to the end of the face part. Needless to say. 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 in the center of the face part 2, that is, in the area from the pipe axis (Z) to the end of the face part and close to the pipe axis (Z), is
When a curved surface is formed with a radius of curvature R ₁ that changes at R ₁ and further changes as it approaches the end of the face,
Pipe axis (Z) between the point (Q) at the center of the face part and the point (P) corresponding to 1/2 of the maximum effective length of the face part
Find the distance h along the line and use the formula h=R-√ from this h and S.
The average radius of curvature R obtained from R ² −S ² may be used as the radius of curvature in the present invention.

Example 1 R _V , R _H and R _D and R _VO , R _HO and R _DO all had the same radius of curvature, and S _V , S _H and S _D were set as shown below.

R _V = R _H = R _D = R = 1275mm R _VO = R _HO = R _DO = R _O = 1800mm S _V = 152.4mm S _H = 203.2mm S _D = 254.0mm In the above case S _V (152.4): S _H (=203.2): S _D (=
254.0)=3:4:5, and the above formula (1) and
ΔL and ΔS shown in equation (2) are ΔL≒0.080 and ΔS≒0.060, which are within the upper limit range of equations (3) and (4) above. 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 was selected as follows.

R _V = 1450mm R _H = 1690mm R _D = 1790mm R _VO = R _HO = R _DO = R _O = 2000mm S _V = 152.4mm S _H = 203.2mm S _D = 254.0mm In the above case S _V , S _H and S The ratio of _D is 3:4:5 as in Example 1, and ΔL and ΔS shown in the above formulas (1) and (2) are ΔL≒0.049 ΔS≒0.038, and the above formula (3) and is within the range near the lower limit of equation (4). That is, in this example, the inner and outer surfaces of the face portion are made flatter than in Example 1, giving a more favorable impression visually. In addition, from the perspective of explosion-proof properties, it is advantageous because the face part is made flatter, R _V , R _H and R _D are made different, and the wall thickness at the end of the face part in the vertical axis direction is the largest. As a result, it was possible to obtain the same explosion-proof characteristics as the conventional product by increasing the wall thickness of the entire face portion by approximately 1 mm.

〔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, 0.04R _V × (S _D ) ² −R _D ×(S _V ) ² /2×S _H ×R _V ×R _D
A cathode ray tube characterized by having a relationship of 0.08. 2 R _V , R _H and R _D , S _V , S _H of the glass panel
and S _D is 0.03R _H × (S _D ) ² −R _D × (S _H ) ² /2 × S _V × R _H × R _D
The cathode ray tube according to claim 1, wherein the cathode ray tube has a relationship of 0.06. 3. 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. 4. Claim 3, characterized in that when the radius of curvature of the inner surface of the face portion including each axial direction is R _V =R _H =R _D =R, the relationship is 0.22S _D /R0.4. Cathode ray tube as described in section. 5. Claim 3, characterized in that the value of the radius of curvature of the outer surface of the face portion including each axis direction is larger than the value of the radius of curvature including each axis direction of the inner surface of the face portion 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.