JP2005322622A - Color picture tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color picture tube having favorable screen quality. <P>SOLUTION: A curve 20 comprised by an inner surface of a face panel 31 is defined in a cross section including a tube axis of the color picture tube. The face panel 31 is provided with at least one cross section wherein the curve 20 has an inflection point 21 in a space from a center P<SB>O</SB>of the face panel 31 to a circumference of an effective display area 25. In the curve 20 having the inflection point 21, when a maximum value of an angle between a tangent line 23 of the curve 20 and a plane 29 orthogonal to the tube axis in the space between the center P<SB>O</SB>of the face panel 31 and the inflection point 21 is θA, and a minimum value of an angle between the tangent line 23 of the inflection point 20 and the plane 29 orthogonal to the tube axis in a space between the inflection point 21 and the circumference of the effective display area is θB, 0.6≤θB/θA<1.0 is satisfied. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a color picture tube.

  In general, as shown in FIG. 2, a color picture tube has an envelope made up of a substantially rectangular face panel 31 and a funnel 32 integrally joined to the face panel 31. On the inner surface of the face panel 31, a phosphor screen 33 made of phosphor layers of three colors of stripes or dots that respectively emit blue, green, and red is formed in a substantially rectangular shape. Opposing to the phosphor screen 33, a substantially rectangular shadow mask 34 having a large number of apertures (apertures) formed in a substantially rectangular area corresponding to a substantially rectangular effective display area of the screen is a face panel. 31 is mounted on the inner wall. On the other hand, an electron gun 37 that emits three electron beams 36R, 36G, and 36B is disposed in the neck 35 of the funnel 32. The three electron beams 36R, 36G, 36B emitted from the electron gun 37 are deflected by a horizontal deflection magnetic field and a vertical deflection magnetic field generated by a deflection yoke 38 mounted outside the funnel 32, and are selected by the shadow mask 34. A part thereof passes through the aperture and scans the phosphor screen 33 in the horizontal direction and the vertical direction, whereby a color image is displayed.

The inner shape of the face panel 31 of the color picture tube is the transmittance of the glass, the outer shape of the face panel 31, the uniformity of brightness, the color uniformity, the visibility, the inner reflection of the face panel 31, the deflection distortion, and the shadow mask 34. In general, as shown in FIG. 3, the periphery is displaced in a direction approaching the electron gun side with respect to the center P ₀ of the inner surface of the face panel 31 through which the tube axis passes. It has a concave shape (see, for example, Patent Document 1).

For the convenience of the following description, the amount of displacement in the direction parallel to the tube axis at each position of the inner surface of the face panel 31 with respect to the center P ₀ is referred to as “sag amount”. An axis perpendicular to the tube axis and parallel to the short side of the face panel 31 is referred to as a short axis, and the intersection of the surface including the short axis and the tube axis and the periphery of the effective display area of the face panel 31 is defined as the short axis direction. I will call it the end. An axis perpendicular to the tube axis and parallel to the long side of the face panel 31 is referred to as a long axis, and the intersection of the surface including the long axis and the tube axis and the periphery of the effective display area of the face panel 31 is the long axis direction. I will call it the end. Further, the intersection of the surface including the diagonal axis and the tube axis of the rectangular effective display area and the peripheral edge of the effective display area of the face panel 31 is referred to as the diagonal direction end.

Since the effective display area of the face panel 31 has a substantially rectangular shape, the distances from the center P ₀ of the inner surface of the face panel 31 to the short axis direction end, the long axis direction end, and the diagonal axis direction end are different from each other. In accordance with the difference in distance, when the amount of depression with respect to the center P ₀ at the minor axis direction end, the major axis direction end, and the diagonal axis direction end is different from each other, that is, as the distance from the center P ₀ becomes farther, When the amount is increased, the sagging amount of the inner surface of the face panel 31 along the short axis, the long axis, and the diagonal axis changes in a quadratic function.

However, when the sagging amounts with respect to the center P ₀ at the minor axis direction end, the major axis direction end, and the diagonal axis direction end are equal to each other, the sagging amount of the inner surface of the face panel 31 along the diagonal axis is particularly large. It does not change in a quadratic function, and the sagging amount change curve has an inflection point in the region 51 in the vicinity of the end in the diagonal axis direction that is the farthest from the center P _{0 as} shown in FIG.

In recent years, tint glass having a low visible light transmittance may be used in order to improve the contrast by reducing the reflection of external light on the inner surface of the face panel 31. In the face panel 31 in which the tint glass is used (such a face panel is referred to as a “tint panel”), the luminance uniformity is significantly lowered if the glass thickness is different in the effective display area. Therefore, it is preferable that the difference in the amount of depression is as small as possible in the tint panel. For this reason, the amount of sagging at the end of the diagonal axis that is far from the center P ₀ cannot be increased. As a result, in the tint panel, the sagging amount change curve has an inflection point as shown in FIG. It becomes easy to do.

Furthermore, today, the outer surface of the face panel 31 tends to be flattened. In a conventional face panel having a convex curved outer surface, it is relatively easy to reduce the difference in the glass thickness with respect to the center P ₀ within the effective display area, and therefore, luminance uniformity when using tint glass is ensured. It was relatively easy to do. However, in order to flatten the outer surface of the face panel while maintaining the same thickness at each position in the effective display area as that of the face panel having a convex curved surface, the outer surface is located around the center P ₀ of the inner surface of the face panel. It is necessary to reduce the amount of depression. As a result, in the face panel having a flat outer surface, the sagging amount change curve tends to have an inflection point as shown in FIG.

  As shown in FIG. 4, when the change curve of the amount of sagging on the inner surface of the face panel 31 has an inflection point, the phosphor screen 33 formed on the inner surface of the face panel 31 compared to the case where there is no inflection point. The state of the film changes. This will be described below.

  Generally, in a color picture tube, an exposure / development method is used as means for forming a film on the inner surface of the face panel. In this method, a film material is applied to the inner surface of the rotated face panel to form a thin film on the entire surface, and exposure is performed using a shadow mask as an exposure mask, and development is usually performed.

  When forming a coating film in this exposure / development method, if the change curve of the amount of sagging on the inner surface of the face panel does not have an inflection point, a coating film in which the film thickness gradually changes from the center to the periphery can be obtained. On the other hand, in the case of having an inflection point, the film thickness changes irregularly at the inflection point, and in general, an irregularly thin film is formed on the peripheral side of the inflection point. Will be.

  Although this irregular change in film thickness can be corrected by changing the exposure system settings, such as adjusting the exposure amount, there are also limitations, and in some cases, overexposure due to the film being too thin, etc. A phenomenon occurs, and the screen quality is significantly deteriorated.

  As a specific example, consider a case where a black matrix, which is a black non-light-emitting substance applied mainly for improving the tube surface color, is fixed in a color picture tube. In general, in order to fix the black matrix, a process of applying a resist film to the inner surface of the face panel, mask exposure through a shadow mask, developing a resist film, applying a black matrix, and removing a resist development portion is performed. In this step, if an irregularly thin portion exists in the applied resist film, the exposed area becomes large in the thin portion, and the amount of black matrix adhering at that portion irregularly decreases. As a result, the size of the phosphor region (phosphor size) formed in the non-fixed portion of the black matrix increases.

  Alternatively, an excessively thin portion of the applied resist film causes a resist overexposure phenomenon, resulting in resist burn-in, and the resist in that portion is finally developed despite being developed. Will not be removed. Therefore, the black matrix on the resist is not removed, and as a result, the black matrix adheres to an undesired portion, and the phosphor size is reduced.

Thus, an irregular change in the film thickness, particularly a change in which the film thickness becomes irregularly thin, causes a significant deterioration in the screen quality and consequently the image quality.
JP 55-28269 A

  The present invention solves the above-mentioned problems of the conventional color picture tube, and even when the change curve of the amount of depression on the inner face of the face panel has an inflection point, the defect of the film formed on the inner face of the face panel is reduced. It is an object of the present invention to provide a color picture tube having good screen quality.

  The color picture tube of the present invention includes a face panel, a phosphor screen provided on the inner surface of the face panel, an electron gun facing the phosphor screen and emitting an electron beam incident on the phosphor screen, A shadow mask that is disposed between the phosphor screen and the electron gun and has a plurality of apertures for selecting the electron beam in a substantially rectangular area corresponding to an effective display area of the screen. And have.

When a curve formed by the inner surface of the face panel is defined in a section including the tube axis of the color picture tube, the section has an inflection point between the center of the face panel and the periphery of the effective display area. The face panel includes at least one. The curve having the inflection point has a maximum value of an angle between a tangent to the curve and a plane perpendicular to the tube axis between the center of the face panel and the inflection point, θA, and the inflection point. 0.6 ≦ θB / θA <1.0, where θB is the minimum value of the angle formed between the tangent line of the curve and the plane orthogonal to the tube axis
Satisfied.

  According to the present invention, it is possible to provide a color picture tube having good screen quality and, as a result, good display image quality.

  In the color picture tube of the present invention, it is preferable that the outer surface of the face panel is substantially flat. Specifically, the curvature radius of the outer surface is preferably 10,000 mm or more. Thereby, the visibility of a display screen can be improved. Moreover, according to the present invention, even if the face panel has such a flat outer surface, a high-quality phosphor screen can be formed on the inner surface.

  The face panel is preferably made of tint glass. Accordingly, it is possible to prevent a decrease in contrast caused by external light reflected from the inner surface of the face panel and visually recognized, so that the visibility of the display screen can be improved. Moreover, according to the present invention, a high-quality phosphor screen can be formed on the inner surface of a face panel made of tint glass and having a small change in thickness in order to ensure luminance uniformity. In the present invention, “tint glass” refers to glass having a light transmittance of 60% or less when the thickness is 10.16 mm.

  Moreover, it is preferable that 0.8 ≦ θB / θA <1.0 is satisfied. Thereby, better screen quality can be obtained.

  The color picture tube of the present invention will be described below with reference to the drawings.

  The color picture tube of the present invention is not particularly limited except for the shape of the inner surface of the face panel. For example, the color picture tube may be the same as the conventional color picture tube shown in FIG. Therefore, the overlapping description is omitted.

FIG. 1A is a perspective view of an embodiment of a color picture tube face panel 31 according to the present invention. In FIG. 1A, P ₀ is the intersection of the inner surface of the face panel 31 and the tube axis of the color picture tube, and is the center of the face panel 31.

Here, in the cross section of the face panel 31 on a plane including the diagonal axis of the substantially rectangular effective display area 25 and the tube axis of the color picture tube (hereinafter referred to as “diagonal axial direction cross section”), the face panel 31. Focus on the curve 20 formed by the inner surface of. In the face panel 31 of the present embodiment, the curved line 20 has an inflection point 21 between the center P ₀ and the end in the diagonal axis direction in the cross section in the diagonal axis direction. That is, in the diagonal cross section, the tangent of the curve 20 at the point above the curve 20 is located on the opposite side of the electron gun from the curve 20 in the range between the center P ₀ and the inflection point 21. In the range between the inflection point 21 and the diagonal end, it is located on the electron gun side with respect to the curve 20.

Further, as shown in FIG. 1 (B) showing a cross section in the diagonal direction in the vicinity 1B of the inflection point 21 in FIG. 1 (A), on the curve 20 between the center P ₀ and the inflection point 21. The maximum value of the angle formed by the tangent line 23 and the plane 29 perpendicular to the tube axis is θA (where θA <90 °). In the present embodiment, the maximum value θA is obtained at the inflection point 21. In addition, as shown in FIG. 1C showing a cross section in the diagonal direction in the portion 1C on the diagonal end side from the inflection point 21 in FIG. 1A, the inflection point 21 and the diagonal axis are shown. The minimum value of the angle formed by the tangent 23 at the point on the curve 20 between the direction end and the plane 29 perpendicular to the tube axis is defined as θB (where θB <90 °). In the present embodiment, the value is the minimum value θB at the end in the diagonal axis direction. In this embodiment,
0.6 ≦ θB / θA <1.0
Is satisfied. More preferably,
0.8 ≦ θB / θA <1.0
Satisfied. In FIGS. 1B and 1C, the vertical axis indicating the amount of depression on the inner surface of the face panel is exaggerated.

  In the present embodiment, since the inner surface of the face panel 31 has the shape as described above, even if the curve 20 has the inflection point 21, the inflection point is included in the coating film formed on the inner surface. Occurrence of an irregular change in film thickness due to 21 is prevented, and as a result, good screen quality can be obtained.

  This will be described with reference to Table 1. Table 1 summarizes the evaluation of the obtained phosphor screen when the phosphor screen is formed on the inner surface of the face panel 31 by variously changing θB / θA.

  As can be seen from Table 1, when θB / θA is less than 0.6, the variation in phosphor size increases and the phosphor size decreases. This is due to the following reason. As described in the background art section, in this case, the thickness of the resist film becomes thinner in the region on the diagonal end side than the inflection point 21, and resist burn-in is likely to occur. As a result, the size of the black matrix differs greatly between the portion where resist image sticking occurs and the portion where no resist image sticking occurs, resulting in large variations in phosphor size. In addition, the resist and the black matrix on the resist cannot be removed at the portion where baking has occurred, and the phosphor size is significantly reduced. Therefore, in this case, it is difficult to obtain a good screen quality.

  On the other hand, when θB / θA is 0.6 or more and less than 0.8, the phosphor size tends to increase, but the variation is small. This is due to the following reason. Also in this case, the thickness of the resist film is reduced in the region on the diagonal end side with respect to the inflection point 21, but the resist film is not thin enough to cause image sticking due to overexposure, rather the resist exposure region is enlarged, The black matrix area becomes smaller. As a result, the phosphor size tends to increase, but the size variation is relatively small. This enlargement of the phosphor size can be corrected by adjusting the exposure system. Therefore, in this case, good screen quality can be obtained.

  Furthermore, when θB / θA is 0.8 or more and less than 1.0, the desired phosphor size is almost the same as when curve 20 has no inflection point without adjusting the exposure system. The variation is also very small. Therefore, in this case, it is possible to obtain a very good screen quality substantially equivalent to the case where the curve 20 has no inflection point.

  As described above, if θB / θA is 0.6 or more and less than 0.8, good screen quality can be obtained, and if it is 0.8 or more and less than 1.0, extremely excellent screen quality can be obtained. Can do.

  In the above embodiment, the case where the curve 20 formed by the inner surface of the face panel 31 in the diagonal axial section has the inflection point 21 has been described. However, the present invention is not limited to this, and in at least one of the cross sections including the tube axis of the color picture tube, that is, the cross section including the tube axis and the short axis, the cross section including the tube axis and the long axis, or In at least one of the cross sections including the tube axis other than these, the curve formed by the inner surface of the face panel 31 may have an inflection point. However, if the curve has an inflection point, θB / θA defined for the curve needs to be within the specific numerical range. Thereby, it is possible to obtain a good screen quality as in the above embodiment.

  The invention is further illustrated by specific examples.

(Example 1, Comparative Example 1)
As Example 1, an example in which the present invention is applied to a color picture tube having a diagonal size of 68 cm will be described. The face panel 31 of this color picture tube is made of tint glass, and its outer surface is substantially flat.

Further, as described in the background art section, the inner surface shape of the face panel 31 is set so that the difference in the wall thickness of the glass from the center P ₀ is reduced even at the end in the diagonal axis direction. In the diagonal direction cross section, the curve 20 formed by the inner surface of the face panel has an inflection point 21 between the center P ₀ and the diagonal direction end. Further, the maximum value θA = 4.00 ° between the tangent line at the point on the curve 20 between the center P ₀ and the inflection point 21 and the plane perpendicular to the tube axis is 4.00 °, The minimum value θB = 2.86 ° between the tangent at the point on the curve 20 between the ends in the angular axis direction and the plane perpendicular to the tube axis was 2.86 °. Therefore, θB / θA = 0.71. Among various cross sections including the tube axis, a cross section in which the curve formed by the inner surface of the face panel 31 has an inflection point was present in addition to the cross section in the diagonal axis direction. θA <1.0 was satisfied. Of these various curves, the value of θB / θA was the smallest in the curve 20 in the above-described diagonal axis section.

  A phosphor screen was formed on the inner surface having such a shape. As a result, a phosphor having a desired size could be obtained by optimizing the exposure system without causing the resist film to be burned. Therefore, good screen quality could be obtained.

On the other hand, as Comparative Example 1, the same face panel as in Example 1 except that the shape of the inner surface was different was prepared, and a phosphor screen was formed on the inner surface in the same manner as in Example 1. In Comparative Example 1, although the curve formed by the inner surface of the face panel in the diagonal axial section has an inflection point between the center P ₀ and the diagonal axial end, θA = 4. 04 °, θB = 2.04 °, and θB / θA = 0.50.

  In Comparative Example 1, the size of the phosphor varies due to resist burn-in, and a small phosphor of about 70 to 90% of the desired size is obtained in some regions. Therefore, it was difficult to obtain good screen quality in Comparative Example 1.

(Example 2)
As Example 2, an example in which the present invention is applied to a color picture tube having a diagonal size of 76 cm will be described. Similar to Example 1, the face panel 31 of the color picture tube is also made of tint glass, and its outer surface is substantially flat.

In addition, the inner surface shape of the face panel 31 is set so that the difference in glass thickness from the center P ₀ at the end in the diagonal axis direction becomes small as in the first embodiment, and as a result, in the cross section in the diagonal axis direction. The curve 20 formed by the inner surface of the face panel has an inflection point 21 between the center P ₀ and the end in the diagonal axis direction. Further, the maximum value θA = 3.33 ° between the tangent at the point on the curve 20 between the center P ₀ and the inflection point 21 and the plane orthogonal to the tube axis is 3.33 °, The minimum value θB = 3.17 ° between the tangent at the point on the curve 20 between the ends in the angular axis direction and the plane perpendicular to the tube axis was 3.17 °. Therefore, θB / θA = 0.95. Among various cross sections including the tube axis, a cross section in which the curve formed by the inner surface of the face panel 31 has an inflection point was present in addition to the cross section in the diagonal axis direction. θA <1.0 was satisfied. Of these various curves, the value of θB / θA was the smallest in the curve 20 in the above-described diagonal axis section.

  A phosphor screen was formed on the inner surface having such a shape. As a result, the resist film was not seized, and a phosphor having a desired size could be obtained without adjusting the exposure system. Therefore, extremely excellent screen quality could be obtained.

  The field of application of the present invention is not particularly limited, and can be used for color picture tubes used for various purposes. However, the color picture tube of the present invention has a good display quality even when the outer surface of the face panel is flat or when the face panel is made of tint glass. This is particularly useful for color picture tubes used in televisions or computer displays that are required.

FIG. 1A is a perspective view showing an embodiment of the inner shape of the face panel of the color picture tube of the present invention, and FIG. 1B is a diagonal view of a portion 1B near the inflection point in FIG. FIG. 1C is a diagram showing a curve formed by the inner surface of the face panel in the axial section, and FIG. 1C is a face in the diagonal section of the portion 1C on the diagonal end side from the inflection point in FIG. It is the figure which showed the curve which the inner surface of a panel makes. It is sectional drawing which showed the whole structure of an example of a color picture tube. It is the perspective view which showed an example of the inner surface shape of the face panel of the conventional color picture tube. It is the perspective view which showed an example of the inner surface shape of the conventional face panel in which the amount of sagging in the short-axis direction end, long-axis direction end, and diagonal-axis direction end of an inner surface is mutually equal.

Explanation of symbols

20 Curve formed by the plane including the tube axis and the inner surface of the face panel 21 Inflection point 23 Curve tangent line 25 Effective display area 29 Plane orthogonal to the tube axis 31 Face panel 32 Funnel 33 Phosphor screen 34 Shadow mask 35 Neck 36R, 36G, 36B Electron beam 37 Electron gun 38 Deflection yoke

Claims (4)

A face panel; a phosphor screen provided on an inner surface of the face panel; an electron gun facing the phosphor screen and emitting an electron beam incident on the phosphor screen; the phosphor screen and the electron gun And a shadow mask provided with a plurality of apertures for selecting the electron beam in a substantially rectangular area corresponding to the effective display area of the screen. And
When a curve formed by the inner surface of the face panel is defined in a cross section including the tube axis of the color picture tube,
The face panel includes at least one cross section in which the curve has an inflection point between the center of the face panel and the periphery of the effective display area;
The curve having the inflection point has a maximum value of an angle between a tangent to the curve and a plane perpendicular to the tube axis between the center of the face panel and the inflection point, θA, and the inflection point. 0.6 ≦ θB / θA <1.0, where θB is the minimum value of the angle formed between the tangent line of the curve and the plane orthogonal to the tube axis
A color picture tube characterized by satisfying   2. The color picture tube according to claim 1, wherein an outer surface of the face panel is substantially flat.   2. A color picture tube according to claim 1, wherein the face panel is made of tint glass. 0.8 ≦ θB / θA <1.0
The color picture tube according to claim 1, which satisfies the following conditions.

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