JP2001084918A - Cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress both doming amount and moire fringe generation at the same time by forming projections inside slot holes in a tension-type shadow mask. SOLUTION: In this cathode-ray tube, a shadow mask having a plurality of slot holes 20 formed in a plate is stretched and held on a frame-shaped mask frame, with a tensile force applied in the vertical direction. In the shadow mask, bridges 21 are formed joining the vertically adjacent slot holes 20 to each other. In each slot hole 20, projections 22a, 22b are formed projecting inward, by from both its horizontal edges and opposing to each other. This can suppress both doming amount and moire fringe generation and at same time ensuring mechanical strength and brightness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask type cathode ray tube used for a television receiver, a computer display and the like.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing an example of a conventional color cathode ray tube. The color cathode ray tube 1 shown in FIG. 1 has a substantially rectangular face panel 2 having a phosphor screen surface formed on an inner surface thereof, a funnel 3 connected to the rear of the face panel 2, and a neck portion of the funnel 3. An electron gun 4 built in 3a and a shadow mask 6 provided inside the face panel 2 so as to face the phosphor screen surface 2a.
And a mask frame 7 for fixing this.
In addition, a funnel 3 is used to deflect and scan the electron beam.
A deflection yoke 5 is provided on the outer peripheral surface of the.

[0003] The shadow mask 6 plays a role of color selection for three electron beams emitted from the electron gun 4. A indicates the electron beam trajectory. Less than,
The shadow mask 6 will be described as a slot type shadow mask. In the slot type shadow mask, a large number of substantially rectangular slot holes, which are electron beam passage holes, are formed in a flat plate by etching.

In a color cathode ray tube, the electron beam passage hole is displaced by thermal expansion due to the electron beam absorption, and the electron beam passing through the electron beam passage hole does not properly hit a predetermined phosphor, resulting in color unevenness. The doming phenomenon occurs. For this reason, tension (tension) that can absorb the thermal expansion due to the temperature rise of the shadow mask is applied in advance, and the shadow mask is stretched and held on the mask frame. According to such a stretch holding, even if the temperature of the shadow mask rises, it is possible to reduce the displacement between the slot holes of the shadow mask and the phosphor stripes on the phosphor screen surface.

FIG. 5 is a plan view showing an example of a slot type shadow mask as a shadow mask for applying tension mainly in the vertical direction of the screen. The arrow x direction in the figure is the screen horizontal direction, and the arrow y direction is the screen vertical direction. The slot holes 8 are formed at a constant pitch. The portion between the slot holes 8 indicated by 9 is called a bridge. The bridge width affects the mechanical strength of the shadow mask, and when the bridge width is reduced, the bridge width is particularly vulnerable to horizontal tension. If the bridge width is increased in order to improve the mechanical strength, the opening area of the slot hole becomes narrower, so that the luminance characteristics are reduced.

[0006] As described above, the bridge width is related to the mechanical strength and the luminance characteristics, but the vertical pitch of the bridge is also related to the doming amount of the shadow mask. This is because the shadow mask is mainly stretched in the vertical direction, and thermal expansion in the vertical direction is absorbed by the tension, but thermal expansion in the horizontal direction is transmitted laterally by the bridge.

FIG. 4 shows an example of the relationship between the bridge pitch and the doming amount (here, an example of a cathode ray tube for a 25-inch television). From this figure, it can be seen that the larger the bridge pitch, the smaller the doming amount can be.

[0008]

However, the above-mentioned conventional color cathode ray tube has the following problems. If the vertical pitch of the bridge is increased, the amount of doming can be suppressed to a small value, and the luminance characteristics are improved by increasing the opening area of the slot hole. In this case, however, moiré fringes, which are mutual interference fringes between scanning lines (bright lines) of electron beams arranged at regular intervals and regular patterns of electron beam passage holes in a shadow mask, are likely to occur, which is one of the causes of image quality deterioration. Had become.

Further, when the vertical pitch of the bridge is increased, there is also a problem that the bridge itself appears to be scattered on the screen. Further, the bridge may be recognized as a stacked pattern (brick-shaped pattern).

Conversely, when the bridge pitch is reduced, moire fringes are sufficiently suppressed, and the bridge itself is not noticeable. However, the shielding area of the scanning line is increased, the luminance characteristic is reduced, and the doming amount is also increased.
That is, it has been difficult to achieve both suppression of the doming amount and suppression of moiré fringe generation.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems. In the tension type shadow mask, by forming projecting portions opposed to each other in a slot hole, the amount of doming can be suppressed and the moire fringes can be suppressed. It is an object of the present invention to provide a cathode ray tube in which the generation is suppressed.

[0012]

In order to achieve the above object, a first cathode ray tube according to the present invention is a shadow mask having a frame-shaped mask frame in which a large number of slot holes are formed in a flat plate. Is a cathode ray tube stretched and held in a state where a tensile force is applied in the vertical direction, wherein the shadow mask is formed with a bridge connecting the vertically adjacent slot holes, and the slot holes are It is characterized in that projecting portions projecting into the slot hole from both lateral ends of the slot hole and facing each other are formed. According to the cathode ray tube as described above, it is possible to suppress the occurrence of moire fringes while suppressing the amount of doming due to thermal expansion.

In the first cathode ray tube, the bridge and the protrusion between the rows of the slot holes adjacent in the horizontal direction are displaced in the vertical direction. Preferably, it is in the range of 1/2 to 1/5 of the vertical pitch of the holes. According to the above-described cathode ray tube, generation of moiré fringes can be further suppressed, and moiré fringes in an oblique direction due to displacement of the bridge in the vertical direction can be suppressed to an inconspicuous degree.

It is preferable that the protrusions are arranged in the slot hole at a vertical pitch of 1 mm or less, and the vertical pitch of the bridge is in a range of 1.5 to 30 mm. If the vertical pitch of the protruding portions is within 1 mm, it is possible to suppress the generation of moire fringes for each broadcasting system with one shadow mask structure even in the case of a plurality of broadcasting systems. Further, by setting the vertical pitch of the bridge within the range of 1.5 to 30 mm, the doming amount can be suppressed to a certain value or less, and the vibration of the shadow mask can be maintained while maintaining a certain luminance characteristic and mechanical strength. Can be suppressed within a practical range.

The area of a pair of laterally adjacent protrusions in the slot hole is preferably in the range of 20 to 120% of the area of one bridge. According to the cathode ray tube as described above, it is possible to secure the luminance characteristics while suppressing the generation of moire fringes.

Further, it is preferable that the vertical pitch of the protruding portion differs depending on the portion of the shadow mask. By doing so, the moiré suppression effect can be improved in accordance with the portion where moiré fringes are likely to occur.

It is preferable that the vertical pitch of the bridge differs depending on the position of the shadow mask. Thus, the mechanical strength and the amount of heat transfer of the shadow mask can be changed according to the location of the shadow mask.

Further, it is preferable that the longitudinal width of the bridge differs depending on the position of the shadow mask. With this configuration, the bridge strength can be changed as necessary in consideration of the tension distribution of the shadow mask.

Further, it is preferable that the vertical width of the protruding portion differs depending on the portion of the shadow mask. Thereby, the brightness can be ensured by changing the beam blocking effect by the projection according to the beam incident angle on the shadow mask.

Next, a second cathode ray tube according to the present invention is arranged such that a shadow mask in which a large number of slot holes are formed in a flat plate is applied with a tensile force in a vertical direction to a mask frame formed in a frame shape. A cathode ray tube which is stretched and held, wherein the shadow mask is formed with a bridge connecting the slot holes adjacent to each other in the longitudinal direction, and the slot holes are near the periphery of the shadow mask and near the center. The longitudinal length is long, and the slot hole near the periphery is formed with protrusions projecting into the slot hole from both lateral ends of the slot hole and facing each other. . According to the above-described cathode ray tube, the strength of the shadow mask can be ensured in the central portion serving as a reference for applying the tensile force, and the thermal doming that tends to occur in the peripheral portion can be suppressed.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. Each configuration of the color cathode-ray tube described with reference to FIG. 3 is the same in the present embodiment, and a description thereof will be omitted.

FIG. 1A is a perspective view of one embodiment of a color selection electrode. The mask frame 10 is a rectangular frame, and a pair of opposed supports 1 which are long side frames.
A pair of elastic members 12 which are short side frames are fixed to 1. The shadow mask 13 is formed by etching a large number of slot-shaped slot holes 14, which are slot-shaped electron beam passage holes. The one shown in this figure is
The tension method is used, and the shadow mask 13 is used.
Is a state where a tensile force is applied mainly in the direction of arrow Y,
It is stretched and held between one. FIG. 1B shows an enlarged view of the slot hole 14. Although not shown in FIG. 1A, the slot holes 14 are formed with protrusions 14a and 14b.

FIG. 1B shows an example in which the shape of the slot hole 14 and the projections 14a and 14b is rectangular. However, the shape is not limited to this, and as shown in FIG. The corners of the portions 24a, 24b may be rounded, and as shown in FIG.
6b may have a gradually projecting shape. In particular, FIG.
Such a shape is easy to realize by an etching method mainly used in manufacturing a shadow mask, and is practical. Details of the protruding portion will be described later.

FIG. 2 is a plan view of one embodiment of the slot type shadow mask. FIG.
It is the figure which expanded a part of (a). The vertical direction in the figure is the screen vertical direction, and the horizontal direction is the screen horizontal direction. The vertically adjacent slot holes 20 are connected by a bridge 21. Projections 22a and 22b are formed in the slot hole 20. These protruding portions 22a and 22b protrude from both ends of the slot hole 20 in the horizontal direction.
The tip portions 2a and 22b face each other. Projection 22a
And 22b are separated from each other, so that the pair of protrusions 2
In the portions where 2a and 22b are formed, the slot holes 20 are narrowed.

The use of the shadow mask according to the present embodiment makes it possible to suppress the occurrence of moire fringes while suppressing the amount of doming due to thermal expansion in the horizontal direction. The reason will be specifically described below. As can be seen from the relationship diagram between the vertical pitch of the bridge and the amount of doming shown in FIG. 4, it is possible to suppress the amount of doming by increasing the vertical pitch of the bridge. Also, if the vertical pitch of the bridge is increased, the opening area of the slot hole is increased, so that the luminance characteristics are also improved.

However, in this case, if the bridge pitch is increased, moire fringes may be generated, and it is necessary to reduce the bridge pitch in order to suppress moire fringes.

For example, if the area of the bridge is reduced in order to suppress the deterioration of the luminance characteristic, the mechanical strength becomes insufficient. In particular, the bridge is broken by the horizontal stress accompanying the vertical stress, and the shadow mask is damaged. It causes wrinkles.

To solve this problem, a pair of protrusions 2
2a and 22b. By forming the protruding portions 22a and 22b, an effect of substantially cutting the scanning line can be obtained. In addition, the protruding portions 22a and 22b are separated from each other, so that not only the vertical stress but also the horizontal stress accompanying the vertical stress is not applied, so that there is no problem in terms of mechanical strength.

Further, since the projections 22a and 22b do not completely close the slot holes in the horizontal direction and do not apply stress as described above, the width in the vertical direction can be reduced, for example. Can also be suppressed. That is, according to the present embodiment, it is possible to achieve both the suppression of the doming amount of the shadow mask that applies tension mainly in the vertical direction and the suppression of the occurrence of moiré fringes while securing the mechanical strength and luminance.

Further, in order to suppress the generation of moire fringes, it is preferable that the positions of the bridges and the protrusions be shifted in the horizontal direction between the row of slot holes adjacent in the horizontal direction. Such a shift in the position can suppress the mutual interference between the scanning line and the slot hole pattern, which is more effective in suppressing the occurrence of moire fringes. Amount of displacement d between adjacent bridges
In FIG. 2, the smaller the distance, the longer the distance between adjacent bridges on the same horizontal line, which is effective in suppressing the occurrence of moire fringes in the horizontal direction. However, if the amount of displacement is too small, the moire fringes in the oblique direction become conspicuous. For this reason, the positional deviation amount d is from 1/2 to 1 of the vertical pitch P of the slot hole 20 (the vertical pitch of the bridge 21).
/ 5 is preferable.

As shown in FIG. 2B, the vertical pitch e of the projecting portions 22a and 22b is 1 mm or less, and the vertical pitch P of the slot hole 20 is in the range of 1.5 to 30 mm. Is preferred. The reason is as follows.

In a cathode ray tube having no protruding portion in the slot hole, when the moiré wavelength is λ, the bridge vertical pitch is a, the scanning line interval is s, and the moiré mode order is n, λ = 1 / (n / 2s− s / a).

In the case of a plurality of broadcasting systems, the value of s / a should be 9/9 in NTSC in order to suppress the occurrence of moire fringes with one shadow mask structure for each broadcasting format.
For 8, PAL, 11/8 is a compromise value. For this reason, if the bridge vertical pitch a is 1 mm or less, a solution for suppressing the generation of moiré fringes with one shadow mask structure can be found even in the case of a multiple broadcasting system.

That is, if the bridge vertical pitch a is replaced with the vertical pitch e of the projecting portions 22a and 22b of the present invention, the vertical pitch e is 1 m in order to suppress the generation of moire fringes.
m or less is preferable.

As for the vertical pitch P of the slot holes 20 within the above range, the doming amount can be made smaller than about 90 μm as shown in FIG. Further, the vibration of the shadow mask can be suppressed within a practical range while securing a certain luminance characteristic and mechanical strength.

That is, if the vertical pitch P is too small, the doming amount is large and the luminance characteristics cannot be secured. Conversely, if the vertical pitch P is too large, the doming amount is small, but the mechanical strength is insufficient and the vibration increases. Within the above range, the vibration can be suppressed to about the same level as a conventional press mask formed by press molding.

The area of a pair of the protrusions 22a and 22b is 20 to 120% of the area of one bridge 20.
Is preferably within the range. The reason why such a range is preferable is that if the area of the protruding portion is too small with respect to the bridge, the generation of moiré fringes is not sufficiently suppressed, and if the area is too large, the luminance characteristics deteriorate. Further, it is preferable that the value of the vertical pitch of the protruding portion is partially or regionally different from the shadow mask. For example, if the vertical pitch of the protruding portion is made finer in the vicinity of the shadow mask where moiré fringes are likely to appear, and the vertical pitch of the protruding portion is designed roughly in the vicinity of the center that hardly affects the moiré fringe, the effect of suppressing moiré fringes will be further enhanced A cathode ray tube can be realized.

It is preferable that the value of the vertical pitch of the bridge is partially or regionally different from that of the shadow mask. For example, the vertical pitch p of the bridge as shown in FIG.
mm, and the structure is such that it is about 5 to 10 mm near the lateral end. By doing so, the stress applied to the bridge can be reduced in the lateral direction where the stress tends to concentrate on the bridge due to the difference in strength between the non-porous region and the perforated region, so that the shadow mask can be prevented from being broken. .

As another example, the vertical pitch p of the bridge is about 5 to 10 mm at the center of the shadow mask.
A structure in which the width is gradually changed to about 10 to 15 mm around the lateral direction may be adopted. In this manner, the amount of thermal doming in the mask lateral direction, which is likely to be accumulated in the vicinity of the shadow mask in the lateral direction, can be suppressed. In this case, the number of bridges is reduced around the horizontal direction, so that the strength tends to be insufficient.For example, if the width of the bridge in the vertical direction is set to be large, the stress applied to the bridge can be reduced, so that the shadow can be reduced. The mask can be prevented from being broken.

Further, a structure having both of these two structures may be adopted. That is, the value of the vertical pitch p of the bridge is gradually increased from the center to the periphery in the horizontal direction, and is reduced again near the left and right ends. In this way, both the amount of thermal doming and the breaking of the shadow mask due to the difference in intensity between the non-porous region and the perforated region can be suppressed.

Further, it is preferable that the vertical width of the protruding portion be partially or regionally different from that of the shadow mask. The incident angle of the electron beam incident on the shadow mask differs depending on the position of the shadow mask. In particular, since the angle around the shadow mask is sharp, the proportion of the electron beam blocked by the bridge and protrusions includes not only the width of the bridges and protrusions but also the thickness of the shadow mask. In the peripheral part, the brightness tends to decrease. For this reason, the brightness of the peripheral portion can be improved by reducing the vertical width of the protruding portion at the peripheral portion.

Further, the projecting portion may be provided only at the peripheral portion without being provided at the central portion of the shadow mask. For example, in the central part of the shadow mask, a structure having a normal substantially rectangular opening and a bridge is provided. In addition to increasing the length, a projecting portion is provided in the opening, and the number of projecting portions is gradually increased.

In this manner, the strength of the shadow mask can be ensured in the central portion, which serves as a reference for applying tension to the shadow mask, and the accumulation of the thermal doming amount is particularly large in the peripheral portion which is easily affected by the thermal doming. Can be prevented from occurring. At this time, since the vertical pitch of the bridge in the peripheral portion of the shadow mask becomes large, the strength of the peripheral portion is likely to be insufficient, but the stress of the bridge can be relaxed by setting the longitudinal width of the bridge to be wide. , It is possible to deal with.

In this embodiment, the protruding portions 22a and 22b are formed separately from each other, and are arranged so that the tips are opposed to each other. Another effect that characteristics are improved is obtained.

The improvement of the geomagnetic characteristics will be described below. The cathode ray tube uses a component such as a magnetic shield to block external magnetism so that the electron beam does not deviate greatly from the original orbit due to external magnetism such as terrestrial magnetism. Generally, the occurrence of color misregistration caused by the action of an electron beam by geomagnetism is called geomagnetic characteristics. The shadow mask that performs color selection also has the role of blocking the external magnetism and improving the terrestrial magnetism characteristics.Especially, the terrestrial magnetism, which travels almost vertically to the cathode ray tube panel, flows along the creepage direction through the shadow mask. By that
It does not act directly on the electron beam.

Here, when the pitch of the bridge of the shadow mask is large, in a shadow mask having no projection in the slot, the terrestrial magnetism easily flows in the vertical direction of the shadow mask, but since there are few bridges, the geomagnetism is small. It is hard to flow in the direction. For this reason, especially in the peripheral area where the frame and the shadow mask come close to each other, geomagnetism accumulated in the shadow mask may float in the pipe direction, and geomagnetism may pass directly through the hole due to the large area of the slot hole. In many cases, the trajectory of the electron beam changes to cause color shift.

On the other hand, in the present embodiment, by providing the protruding portions that approach each other and approach the slot hole, the opposing protruding portions (22a in FIG. 2B) are provided.
And 22b) serve to pass the geomagnetism, so that in addition to the flow of the geomagnetism in the vertical direction, the geomagnetism flows not only in the bridge portion but also in the protruding portion in the horizontal direction. Therefore, the geomagnetism does not float, and there is also an effect that the geomagnetism that tries to pass through the slot hole is picked up by this protrusion,
The electron beam is less affected by geomagnetism. Therefore, it is possible to obtain a cathode ray tube with less color shift due to terrestrial magnetism.

[0048]

As described above, according to the cathode ray tube of the present invention, the projections are formed in the slot holes in the tension type shadow mask, so that the mechanical strength and luminance can be ensured while the doming amount can be reduced. It is possible to achieve both suppression and suppression of moiré fringe generation, and it is also possible to improve geomagnetic characteristics. Further, by making the vertical pitch of the bridges and protrusions of such a shadow mask different depending on the position of the shadow mask, it is possible to obtain the effects of securing the strength of the shadow mask, reducing the amount of thermal doming, and suppressing luminance degradation. .

[Brief description of the drawings]

FIG. 1 is a perspective view of a color selection electrode according to an embodiment of the present invention.

FIG. 2 is a plan view of a slot type shadow mask according to one embodiment of the present invention.

FIG. 3 is a sectional view of an example of a conventional color cathode ray tube.

FIG. 4 is a diagram illustrating an example of a relationship between a bridge pitch and a doming amount;

FIG. 5 is a plan view of an example of a conventional slot type shadow mask.

FIG. 6 is a plan view of a slot hole and a protrusion according to an embodiment of the present invention.

FIG. 7 is a plan view of a slot hole and a protrusion according to another embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 10 mask frame 11 support 12 elastic member 13 shadow mask 14, 20, 23, 25 slot hole 21 bridge 14a, 14b, 22a, 22b, 24a, 24b, 2
6a, 26b Projection

Claims (9)

[Claims] 1. A cathode ray tube having a shadow mask having a plurality of slot holes formed in a flat plate stretched and held in a state where a tensile force is applied in a longitudinal direction on a mask frame formed in a frame shape. In the shadow mask, a bridge is formed to connect the vertically adjacent slot holes, and the slot holes are formed with protruding portions projecting into the slot holes from both lateral ends of the slot holes and facing each other. A cathode ray tube characterized by being made. 2. The bridge and the projecting portion between rows of the slot holes adjacent to each other in the horizontal direction are displaced in the vertical direction, and the displacement of the bridge position is 1/1 of the vertical pitch of the slot holes. 2. The cathode ray tube according to claim 1, wherein the value is in the range of 2 to 1/5. 3. The projecting portion has a length of 1 m in the slot hole.
2. The cathode ray tube according to claim 1, wherein the bridges are arranged at a vertical pitch within m, and a vertical pitch of the bridge is in a range of 1.5 to 30 mm. 4. The cathode ray tube according to claim 1, wherein an area of a pair of laterally adjacent protrusions in the slot hole is in a range of 20 to 120% with respect to an area of one bridge. 5. The cathode ray tube according to claim 1, wherein a vertical pitch of the projecting portion varies depending on a position of the shadow mask. 6. The cathode ray tube according to claim 1, wherein a vertical pitch of the bridge differs depending on a position of the shadow mask. 7. The cathode ray tube according to claim 1, wherein a longitudinal width of the bridge varies depending on a position of the shadow mask. 8. The cathode ray tube according to claim 1, wherein a vertical width of the protrusion is different depending on a position of the shadow mask. 9. A cathode ray tube in which a shadow mask in which a number of slot holes are formed in a flat plate is stretched and held in a state where a tensile force is applied in a vertical direction on a mask frame formed in a frame shape. The shadow mask is formed with a bridge connecting the vertically adjacent slot holes, and the slot holes are longer in the vertical direction near the periphery of the shadow mask than in the vicinity of the center; The cathode ray tube according to claim 1, wherein the slot hole has projections projecting into the slot hole from both lateral ends of the slot hole and facing each other.