JPS59165341A - Color cathode ray tube - Google Patents

Abstract

PURPOSE:To reduce displaced colors due to doming occurring on a shadow mask, by arranging the through holes in a shadow mask in a plurality of vertical columns running perpendicularly to the plane including the electron guns and by setting the pithes between the columns to be maximum or the largest at the center of the shadow mask and at the end portions thereof and to be minimum at the middle portion of them. CONSTITUTION:The through holes in a shadow mask 10 are arranged in plurality of columns running perpendicularly to the plane including the electron guns, and the pitches a between the columns are set to be maximum or the largest at the center O of the shadow mask and at the end portions thereof + or -XM in the direction perpendicular to the columns and to be minimum at the middle portions of them. The pitches are also set in such a way that the pitches are monotonously decreasing from the center O to the middle portions and monotonously increasing from the middle portions to the end portions + or -XM. If, for example, a graph is made taking the horizontal pitches a of the shadow mask 10 on the axis of ordinate and the positions on the shadow mask on the axis of abscissa, the pitches a are represented by a waveform as shown in the soid line h, in which there are formed two shapes with a small radius of curvature on both sides of the center, whereby formation of the doming on the both sides can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color cathode ray tube having a shadow mask.

Generally, in this type of color cathode ray tube, during operation, a part of the electron beam from the electron gun passes through the hole in the shadow mask and hits the phosphor screen, causing it to emit light; The electron beam impinges on the shadow mask and increases its temperature. Therefore, the shadow mask thermally expands and undergoes thermal deformation. Among these thermal deformations, one that is difficult to solve is when a particularly bright still image is projected onto a relatively small area (approximately 20 to 100 mm), the temperature of the shadow mask increases locally, and only this part There is so-called local doming, where thermal expansion occurs significantly compared to other parts and bulges out locally towards the flannel side. This local doming is
This occurs because, although the locally heated portion of the shadow mask formed in a spherical shape undergoes thermal expansion, the surrounding area does not.

By the way, considering the shadow mask as an approximate pitch sphere,
Further, assuming that the shape area and temperature rise of the portion where the temperature locally increases are constant, the amount of doming, that is, the amount of locally protruding the shadow mask is proportional to the radius of curvature of the shadow mask. Therefore, to reduce local doming, it is necessary to reduce the radius of curvature. Even in the case of a shadow mask that cannot be approximated by a spherical surface, local doming can be reduced by reducing one of the curvature radii when the shadow mask is approximated by two mutually orthogonal radii of curvature.

The above relationship will be explained below with reference to FIG. In the figure, (2) is a panel having a fluorescent screen (3) (see Figure 2), (4) is a funnel part joined to this panel (2), and (5) is a panel joined to funnel part (4). (8) is a plurality of electron guns arranged in a line on a plane inside the neck part (5); (10) is arranged inside the panel (2), and a plurality of regular This is a shadow mask provided with a slot-shaped (elongated rectangular) through hole (11). The through holes (11) are arranged in rows in the vertical direction, and arranged at regular intervals in the horizontal direction.

As shown in FIGS. 2 and 3, the phosphor screen (3) has three parallel phosphor stripes (3B), (3G), (3
R) are repeated in the X direction, and the through holes (11) of the shadow mask (10) shown in FIG. 1 are formed in one set to face each other.

Next, the operation will be explained according to FIG.

Now, each electron gun (SR), (8G), (8B)
The electron beam (10OR), (100G), (1
00B) is deflected by a deflection yoke (not shown) near the connection between the funnel part (4) and the neck part (5),
It travels straight, drawing a trajectory that looks like it was suddenly deflected at a certain angle on the virtual center plane of deflection (110). Here, at the deflection center plane (110), three electron beams (100R),
The distance between (100G) and (100B) is S, which is parallel to the tangential plane on the panel on which this beam strikes, and is parallel to the deflection center plane (1
Let S' be the distance to the electron beam on the plane (111) passing through 1G), then S' is from the figure.

CO8θ s'= s ... [11CO
It is expressed as S (θ−α). However, θ is the deflection angle, α is the center plane of deflection (
110) and the plane (111). Also, if the distance between the phosphor screen (3) and the shadow mask (10) is q, and the distance between the shadow mask (10) and the point where the electron beam passes through the center of the central plane of deflection (jlO) is p, then the phosphor stripe From the arrangement condition, -p On the other hand, if the horizontal interval of the through holes (11) of the shadow mask (1o) with respect to the pitch P is a, then as is clear from the figure, P+(IP=a... [3]p
− Substitute [3] into [2] and get P+q q” a aφ... [4・]33
There is a relationship.

Therefore, P+q is constant at the point of the fluorescent screen (3),
Since S' is also a constant that is determined regardless of the shape of the shadow mask (10), the distance q is determined in proportion to the distance a between the through holes (11) of the shadow mask (lO). In other words, while changing the interval a arbitrarily, the shadow mask (
It is conceivable that local doming can be reduced by changing the shape of io).

This invention was made in view of the above circumstances, and focuses on the relationship between the through holes of the shadow mask and the shape, and by changing the pitch of the through holes and the shape of the shadow mask depending on the position of the shadow mask, doming can be prevented. The purpose of the present invention is to provide a color cathode ray tube with reduced effects.

An embodiment of the present invention will be described below with reference to the drawings.

The feature of this invention is that the through holes of the shadow mask are formed in a plurality of rows, and the interval between these rows is set to be maximum at the center and both ends of the shadow mask, and minimum between these, and The radius of curvature is smaller on both sides than in the center.

To explain this with Figure 6, the vertical axis shows the pitch a of the shadow mask in the horizontal direction, and the horizontal axis shows the position of the shadow mask. As is clear from the above, in the conventional shadow mask, the pitch a in the horizontal direction is constant, whereas in this embodiment, x=o at the center of the shadow mask and Xm above both ends.
The maximum value of pitch a is set at the point , and the minimum value is set between -1. On the other hand, as shown in FIG. 7, the shape of the shadow mask is a circular arc that can be approximated by a constant radius of curvature in the conventional shadow mask (10a), whereas in the Shaton mask (1o) of this embodiment, It is formed in a wavy shape and has two shapes with large radii of curvature on both sides of the central portion.

The reason why the pitch a and shape of the shadow mask (1o) are set as described above is as follows. Pitch a of the shadow mask and distance q between the shadow mask and the panel
The relationship is as shown in equation [5] above. According to this, since the pitch a is proportional to the distance q, by setting the pitch a long, the distance q can be made long, that is, the shadow mask (lO) can be placed far from the panel (2). Focusing on this point, the center part of the shadow mask (1o) is formed to have a concave radius of curvature with respect to the panel, while
Set the radius of curvature on both sides to be large. This increases the influence of local doming at the center, but increases the radius of curvature at both sides, making it possible to reduce the influence of doming at both sides. In other words, the above-mentioned doming at the center has a small deflection angle at the center, so even if local thermal deformation of the shadow mask occurs, there is little effect such as color shift, so the effect in this range can be ignored. This reduces doming in areas where the deflection angle is large.

At this time, the value at which the pitch is minimum is less than 0,0
, oslxnl<lxaml<0.81Xnl, preferably 0.051Xnl<lXaml<0.5
It is set to Xn. Here, the reason why Xam is relatively biased towards x-value 0 is that the pitch in the center of the screen becomes significantly large, impairing image quality, and the influence of doming does not have a large effect on areas where the deflection angle is large. It's for a reason.

Note that in the above embodiment, the arrangement and shape of the through holes (11) in the shadow mask (10) in the vertical direction (Y direction) are not described, but the phosphor stripes in the Y direction are provided vertically. Generally, the deviation of the phosphor screen due to doming appears in this direction, so that no adverse effects such as deviation of one color occur. Therefore, firstly, it is necessary to set the pitch of the through holes in the horizontal direction and the shape of the shadow mask, and secondly, the pitch in the vertical direction and the like need to be considered.

In the above embodiment, the center portion of the shadow mask is formed to protrude toward the electron gun, but the present invention is not limited to this.
As shown in FIG. 8, the same effect as in the above embodiment can be obtained even if the radius of curvature of the central portion is formed to be almost infinite.

As explained above, according to the present invention, the through holes of the shadow mask are formed in a plurality of rows perpendicular to the plane,
Set this column spacing so that it is maximum at the center and both ends of the shadow mask, and minimum between these,
By forming both sides of the shadow mask into a wave shape so as to protrude toward the panel from the center, it is possible to provide a color cathode ray tube with less color shift due to doming.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway view showing a conventional color cathode ray tube, Fig. 2 is a front view showing the phosphor screen of Fig. 1, and Fig. 3 is an enlarged view of part A shown in Fig. 2. 4 is an explanatory diagram showing the operation of the cathode ray tube in FIG. 1, FIG. 5 is an enlarged view of part B shown in FIG. 4, and FIG. 6 is according to the conventional example shown in FIG. 1 and an embodiment of the present invention. A characteristic diagram showing the characteristics of a cathode ray tube, FIG. 7 is a schematic sectional view illustrating the shape of the shadow mask in the conventional example and the embodiment shown in FIG. 1, and FIG. 8 is a schematic diagram showing another embodiment. . (2)・Fist・Panel, (3)e・・Fluorescent screen, (4)・・・
・Funnel part, (5)... Neck part, (8)...
Electron gun, (10)...Shadow mask, (11)...
・Through hole, a...Q pitch. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent Makoto Kuzuno (1 other person) Figure 1 Figure 2 Figure 7 Figure 8 Figure 0 Commissioner of the Japan Patent Office 1, Indication of the case Patent Application No. 1983-040332 2,
Title of the invention: Color cathode ray tube 3; Person making the amendment Representative: Hitoshi Katayama 5; Full text of the specification to be amended and drawings. 6. Contents of Supplementary IE A, Specification: (1) The entire text of the specification will be amended as shown in the attached sheet. Drawing 30: (1) In order to correct the symbol a in Fig. 4, we will resubmit Fig. 4 as shown in the attached sheet. (2) Resubmit Figure 6 as attached. Above amended specification ■1 Name of invention color cathode ray tube? , Claims (1) A panel having a fluorescent screen, a funnel portion and a neck portion joined to the panel, a shadow mask disposed inside the panel and provided with a plurality of through holes, and a shadow mask provided inside the neck portion. and a plurality of electron guns arranged in a row on a plane, the shadow mask has a plurality of through holes formed in a plurality of rows perpendicular to the plane, and the row spacing is set at the center of the shadow mask. In addition, the key should be the largest and the smallest in this east plate 1 & 6.
Color cathode ray tube. 3. Detailed Description of the Invention The present invention relates to a color cathode ray tube having a shadow mask. Generally, in this type of color cathode ray tube, during operation, a part of the electron beam from the electron gun passes through the hole in the shadow mask and hits the phosphor screen, causing it to emit light; The electron beam impinges on the shadow mask and increases its temperature. Therefore, the shadow mask thermally expands and undergoes thermal deformation. Among these thermal deformations, one that is difficult to solve is that when a particularly bright still image is projected onto a relatively small area (about 20 to 10 G-size), the temperature of the shadow mask increases locally, causing There is so-called local doming, in which only one part of the panel undergoes significant thermal expansion compared to other parts and locally bulges out toward the panel. This local doming occurs because, although the locally heated portion of the shadow mask formed in a spherical shape undergoes thermal expansion, the surrounding area does not expand. By the way, if we assume that the shadow mask is approximately a spherical surface, and that the shape area and temperature of the portion where the temperature locally increases is constant, then the doming 1,), that is, the amount of local protrusion of the shadow mask. is proportional to the radius of curvature of the shadow mask. Therefore, to reduce local doming, curvature. The radius needs to be reduced. Even in the case of a shadow mask that cannot be approximated by a spherical surface, local doming can be reduced by reducing one of the curvature radii when the shadow mask is approximated by two mutually orthogonal radii of curvature. The above relationship will be explained below with reference to FIG. In the figure, (2) is a panel having a fluorescent screen (3) (see Figure 2), (0 is a funnel part that is joined to this panel (2), and (5) is a panel that is joined to the funnel part (4). (8) is a plurality of electron guns arranged in a line on a plane inside the neck part (5); (lO) is arranged inside the panel (2), and a plurality of regular Slot shape (long rectangular)
This is a shadow mask provided with a through hole (11). The through holes (11) are arranged in rows with the longitudinal direction extending in the vertical direction, and are generally arranged at regular intervals in the horizontal direction. As shown in FIGS. 2 and 3, the phosphor screen (3) has phosphor stripes (3B), (3G), (3
R) are repeated in the X direction, and the through holes (, 11) of the shadow mask (10) shown in FIG. 1 are formed in one set to face each other. Next, the operation will be explained according to FIG. Now, each electron gun ([lR), (EIG), (8
B) Electron beam emitted from (100R), (100G),
(100B) is deflected by a deflection yoke (not shown) near the connection between the 77 flannel portion (4) and the neck portion (5), and is suddenly at a certain angle at the imaginary deflection center plane (110)-H. Draw a trajectory that looks like it was deflected by the arrow and go straight ahead. Here, 1, % Te, and three electron beams (
10OR), (100G), (100B) (7) The distance is S, and the electron beam in the plane (III) that is parallel to the tangential plane on the panel on which this beam strikes and passes through the center of the deflection center plane (110). If the distance is So, from the figure, So is CO8θ S'= S ・ ・ ・
[1] It is expressed as C05(θ-α). However, θ is the deflection angle, α is the center plane of deflection (
110) and the plane (111). Also, the distance between the phosphor screen (3) and the shadow mask (10) is q, and the distance between the shadow mask (10) and the point where the electron beam passes through the center of the deflection center plane (110) is p (where q, P are measured along the electron beam (100G)), then from the condition of the phosphor stripe arrangement, P・p q= □ ...Fist [2] 3S' On the other hand, the shadow mask for the pitch P (10 ) is the horizontal interval of the through holes (11), as is clear from the figure, there is a relationship of 3S' by substituting [3] into [2]. Here, p + q is constant depending on the point of the fluorescent screen (3), and So
Since it is a constant that is determined regardless of the shape of the shadow mask (10), the distance q is determined in proportion to the distance a between the through holes (11) of the shadow mask (10). In other words, while changing the interval a appropriately, the shadow mask (1
It is conceivable that local doming can be reduced by changing the shape of 0). This invention was made in view of the above circumstances, and focuses on the relationship between the through holes of the shadow mask and the shape, and by changing the pitch of the through holes and the shape of the shadow mask depending on the position of the shadow mask, doming can be prevented. The purpose of the present invention is to provide a color cathode ray tube with reduced effects. An embodiment of the present invention will be described below with reference to the drawings. The feature of this invention is that the through holes of the shadow mask are formed in a plurality of rows, and the interval between these rows is set so that it is maximum or maximum at the center and the end of the shadow mask in the X direction, and is minimum between these rows. At the same time, the distance between the shadow mask and the panel, that is, the radius of curvature of the shadow mask, is determined and formed so as to satisfy the relationships in each of the above equations. To explain this with reference to FIG. 6, the vertical axis shows the pitch a of the shadow mask in the horizontal direction, and the horizontal axis shows the position of the shadow mask, where the dashed line j shows the conventional example and the solid line shows the embodiment of this invention. As is clear from the figure, in the conventional shadow mask, the pitch a in the horizontal direction is constant, whereas in this embodiment, x=0 at the center of the shadow mask and XM above both ends.
The local maximum value or the maximum value of the pitch a is set at the point , and the minimum value is set between them. On the other hand, the shape of the shadow mask is, as shown in FIG. , is formed in a wave shape, and is formed with two shapes with small radii of curvature on both sides of the center part. The reason why the pitch a and shape of the shadow mask (10) are set as described above is as follows. Pitch a of the shadow mask and distance q between the shadow mask and the panel
The relationship is as shown in the Kitagi equation [5]. According to this, since the pitch a is proportional to the distance q, by setting the pitch a long, the distance q can be made long, that is, the shadow mask (10) can be installed far from the panel (2). Focusing on this point, the center of the shadow mass (lO) is formed with a curvature that is not necessarily convex toward the panel (concave in the example in Figure 7), but instead deviates from the center and Therefore, it is possible to set the radius of curvature small near both ends (referred to as both sides), and as a result,
The occurrence of doming on both sides can be reduced. In addition, the radius of curvature cannot necessarily be said to be small near the center based on the above explanation alone, especially when the shadow mask (10) is concave toward the panel as shown in Figure 7. There is an inflection point, that is, a point where the radius of curvature becomes infinite, and there is a possibility that the occurrence of doming will be rather large. Since the amount of damage caused by the color shift on the image is small, actual damage can be almost eliminated. Furthermore, even if the radius of curvature becomes infinite at an inflection point, the radius of curvature of the cross section is determined in the conventional manner in the vertical direction, that is, parallel to the Y axis, so doming actually becomes infinite. It won't happen. At this time, the position Xam where the pitch is minimum is at least 0.051 XM l <1xaxl<o, e
l X M l desirably 0.05 l X M l < lx aM 0.5
1 XM It is set to 1. Here, XM is the X coordinate of the edge of the screen. The reason why XaM is relatively biased toward x = 0 is because the pitch at the center of the screen becomes significantly large, which impairs image quality, and because doming does not have a large effect on areas where the deflection angle is large. It is. Although the above embodiment does not describe the arrangement and shape of the (lO) through-holes (11) in the vertical direction (Y direction) of the shadow mask, the phosphor stripes in the Y direction are provided vertically. In principle, the row of through holes (11) is Y.
In principle, they are parallel to the direction, but within a range of substantially 4L lines, for example, it is possible to make them completely parallel to each other, taking into consideration the outline and appearance around the phosphor screen. In the above embodiment, the center portion of the shadow mask is formed to protrude toward the electron gun. However, as shown in FIG.
Alternatively, the same effect can be obtained by forming it so that it protrudes toward the panel side as in the conventional example but has a larger radius of curvature than the conventional example. Even in the case of fJ, the distribution of pinch a still has a minimum value between the center and the ends, as explained in connection with FIG. As described above, according to the present invention, the transparent electron guns of the shadow mask are arranged in a plurality of rows perpendicular to the plane, and the intervals between the rows are set at the center and end portions of the shadow mask. A color cathode ray tube with less color fading due to doming can be provided by setting the shadow mask to be maximum or maximum and minimum between these and forming the shadow mask in a cross-sectional shape suitable for one row interval. 4. Brief explanation of the drawings Fig. 1 is a partially cutaway perspective view showing a conventional color cathode ray tube, Fig. 2 is a front view showing the phosphor screen of Fig. 1, and Fig. 3 is the A shown in Fig. 2. 4 is an operation explanatory diagram showing the operation of the cathode ray tube shown in FIG. 1, FIG. 5 is an enlarged view of 8 parts shown in FIG. 4, and FIG. A characteristic diagram showing the characteristics of a cathode ray tube according to an embodiment of the invention, FIG. 7 is a schematic sectional view illustrating the shape of the shadow mask in the conventional example of FIG. 1 and the embodiment, and FIG. 8 is a diagram showing another embodiment. FIG. (2)... Panel, (3) Fist... Fluorescent screen, (4)...
・Funnel part, (5)・War/Neck part, (6)...
Electron gun, (10)...φ shadow mask, (11) fist...
・Through hole, all...pitch. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent Masuo Oiwa

Claims (1)

[Claims] (1) A panel having a phosphor screen, a funnel part and a neck part joined to this panel, a shadow mask arranged inside the panel and having a plurality of through holes, and a shadow mask provided on a plane inside the neck part. The shadow mask includes a plurality of electron guns arranged in rows, and the shadow mask has a plurality of through holes formed in a plurality of rows perpendicular to the plane, and the distance between the rows is set at the center and both ends of the shadow mask. A color cathode ray tube characterized in that the shadow mask is set to have a maximum value and a minimum value between the two, and both sides of the shadow mask are formed in a wave shape so as to protrude from the center part toward the panel side.