JP3835728B2 - Cathode ray tube - Google Patents

Description

[0001]
BACKGROUND 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]
[Prior art]
A cross-sectional view of an example of a conventional color cathode ray tube is shown in FIG. The color cathode ray tube 1 shown in the figure includes a substantially rectangular face panel 2 having a phosphor screen surface formed on the inner surface, a funnel 3 connected to the back of the face panel 2, and a neck portion of the funnel 3. An electron gun 4 built in 3a, 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 the mask 6 are provided. Further, a deflection yoke 5 is provided on the outer peripheral surface of the funnel 3 in order to deflect and scan the electron beam.
[0003]
The shadow mask 6 plays a role of color selection for the three electron beams emitted from the electron gun 4. A indicates an electron beam trajectory. Hereinafter, the shadow mask 6 will be described as a slot type shadow mask. In the slot type shadow mask, a large number of slot holes, which are substantially rectangular electron beam passage holes, are formed on a flat plate by etching.
[0004]
In a color cathode ray tube, the electron beam passage hole is displaced due to thermal expansion due to electron beam absorption, so that the electron beam passing through the electron beam passage hole does not correctly hit a predetermined phosphor, and color dosing occurs. Arise. For this reason, tension (tension) that can absorb thermal expansion due to 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 stretching and holding, even if the temperature of the shadow mask rises, it is possible to reduce the shift of the mutual position between the slot hole of the shadow mask and the phosphor stripe on the phosphor screen surface.
[0005]
FIG. 5 shows a plan view of 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 horizontal screen direction, and the arrow y direction is the vertical screen direction. The slot holes 8 are formed at a constant pitch. A portion between the slot holes 8 indicated by 9 is called a bridge. The bridge width affects the mechanical strength of the shadow mask. When the bridge width is narrowed, 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 is reduced, so that the luminance characteristics are deteriorated.
[0006]
As described above, the bridge width is related to the mechanical strength and the luminance characteristic, 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 pulled in the vertical direction, and the thermal expansion in the vertical direction is absorbed by the tension, but the thermal expansion in the horizontal direction is transmitted laterally by the bridge.
[0007]
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.
[0008]
[Problems to be solved by the invention]
However, the conventional color cathode ray tube as described above has the following problems. If the vertical pitch of the bridge is increased, the amount of doming can be reduced, and the luminance characteristics are improved by increasing the opening area of the slot hole. However, in this case, moire fringes that are mutual interference fringes between the scanning lines (bright lines) of the electron beams arranged at regular intervals and the regular patterns of the electron beam passage holes of the shadow mask are likely to occur, which is a cause of image quality degradation. It was.
[0009]
In addition, when the vertical pitch of the bridge is increased, there also arises a problem that the bridge itself appears scattered on the screen. In some cases, the bridge is recognized as a stacked pattern (brick pattern).
[0010]
Conversely, if the bridge pitch is made small, moire fringes are sufficiently suppressed and the bridge itself does not stand out. However, the shielding area of the scanning line is increased, the luminance characteristic is deteriorated, and the doming amount is increased. That is, it is difficult to achieve both suppression of the doming amount and suppression of the occurrence of moire fringes.
[0011]
The present invention solves the above-described conventional problems, and in the tension type shadow mask, by forming protruding portions facing each other in the slot hole, the doming amount is suppressed and the occurrence of moire fringes is suppressed. It aims at providing the cathode ray tube which made it compatible.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the first cathode ray tube of the present invention has a mask frame formed in a frame shape and a shadow mask having a large number of slot holes formed in a flat plate is applied with a tensile force in the vertical direction. The shadow mask has a bridge that connects the slot holes adjacent in the vertical direction, and the slot holes have both ends in the lateral direction of the slot holes. To the slot hole and projecting portions 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 doming amount due to thermal expansion.
[0013]
Next, a second cathode ray tube according to the present invention is a frame mask-shaped mask frame in which a shadow mask having a large number of slot holes formed in a flat plate is stretched in a state in which a tensile force is applied in the vertical direction. The shadow mask is formed with a bridge that connects the slot holes adjacent to each other in the vertical direction, and the slot holes are formed in the slot holes from both lateral ends of the slot holes. Projecting portions that are opposed to each other are formed, and the projecting portions are arranged at a vertical pitch of 1 mm or less within the slot holes, and the vertical pitch of the bridge is within a range of 1.5 to 30 mm. It is characterized by.
If the vertical pitch of the protrusions is within 1 mm, it is possible to suppress the occurrence of moire fringes for each broadcasting system with a single shadow mask structure even in the case of a plurality of broadcasting systems. In addition, 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 luminance of the shadow mask and the mechanical strength can be ensured while the shadow mask is vibrated. Can be kept within the practical range.
In the first or second cathode ray tube, the bridge and the protrusion between the rows of the slot holes adjacent in the lateral direction are displaced in the vertical direction, and the displacement of the bridge is the slot. It is preferably within a range of 1/2 to 1/5 of the vertical pitch of the holes. According to the cathode ray tube as described above, the generation of moire fringes can be further suppressed, and the moire fringes in the oblique direction due to the positional displacement of the bridge in the vertical direction can be suppressed to an inconspicuous level.
[0015]
Moreover, it is preferable that the area of a pair of protrusion part which adjoins the horizontal direction in the said slot hole exists in the range of 20 to 120% with respect to the area for the said 1 bridge | bridging. According to the cathode ray tube as described above, it is possible to secure luminance characteristics while suppressing the occurrence of moire fringes.
[0016]
Moreover, it is preferable that the vertical pitch of the protrusions varies depending on the portion of the shadow mask. In this way, it is possible to increase the moire suppression effect according to the portion where moire fringes are likely to occur.
[0017]
Moreover, it is preferable that the vertical pitch of the bridge differs depending on the portion of the shadow mask. Thereby, the mechanical strength of the shadow mask and the amount of heat transfer can be changed according to the part of the shadow mask.
[0018]
Moreover, it is preferable that the vertical width of the bridge differs depending on the portion of the shadow mask. In this way, the strength of the bridge can be changed as necessary in consideration of the tension distribution of the shadow mask.
[0019]
Moreover, it is preferable that the vertical width of the protruding portion varies depending on the portion of the shadow mask. Thereby, the beam shielding effect by the protrusion can be changed according to the beam incident angle to the shadow mask, and the luminance can be ensured.
[0020]
Then the third of the cathode ray tube of the present invention is stretched held in a mask frame formed in a frame shape, a flat plate a number of shadow mask slot hole is formed tensile vertically force is applied The shadow mask is formed with a bridge connecting the slot holes adjacent in the vertical direction, and the slot hole is formed in the vertical direction near the periphery of the shadow mask rather than near the center. The slot hole in the vicinity of the periphery has a long length and is formed with protruding portions that protrude into the slot hole from both lateral ends of the slot hole and face each other. According to the cathode ray tube as described above, the strength of the shadow mask can be ensured in the central portion serving as a reference for applying the tensile force, and thermal doming that tends to occur in the peripheral portion can be suppressed.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Since each configuration of the color cathode ray tube described with reference to FIG. 3 is the same in this embodiment, the description thereof is omitted.
[0022]
FIG. 1A shows a perspective view of one embodiment of a color selection electrode. The mask frame 10 is a rectangular frame, and a pair of elastic members 12 that are short-side frames are fixed to a pair of opposing supports 11 that are long-side frames. The shadow mask 13 has a slot type slot hole 14 that is a slot type and has a number of substantially rectangular electron beam passage holes formed by etching. In this figure, a tension method is used, and the shadow mask 13 is stretched and held between the supports 11 with a tensile force applied mainly in the direction of the arrow Y. FIG. 1B shows an enlarged view of the slot hole 14. Although omitted in FIG. 1A, the slot holes 14 are formed with projecting portions 14 a and 14 b.
[0023]
In addition, in FIG.1 (b), although the shape of the slot hole 14 and protrusion part 14a, 14b has shown the rectangular example, not only this but the slot hole 23 and protrusion part 24a, as shown in FIG. The corners of 24b may be rounded, or the protrusions 26a and 26b of the slot hole 25 may gradually protrude as shown in FIG. In particular, the shape as shown in FIG. 7 is practical and easy to realize by an etching method mainly used in manufacturing a shadow mask. Details of the protrusion will be described later.
[0024]
FIG. 2 shows a plan view of an embodiment of the slot type shadow mask. FIG. 2B is an enlarged view of a part of FIG. The vertical direction in the figure is the screen vertical direction, and the horizontal direction is the screen horizontal direction. The slot holes 20 adjacent in the vertical direction are connected by a bridge 21. Protrusions 22 a and 22 b are formed in the slot hole 20. These protrusions 22a and 22b protrude from both ends of the slot hole 20 in the lateral direction, and the tip ends of the protrusions 22a and 22b face each other. Since the protrusions 22a and 22b are separated from each other, the slot hole 20 is narrowed at the portion where the pair of protrusions 22a and 22b is formed.
[0025]
If a shadow mask like this embodiment is used, generation | occurrence | production of a moire fringe can be suppressed, suppressing especially the amount of doming by the thermal expansion to a horizontal direction. The reason will be specifically described below. As can be seen from the relationship between the vertical pitch of the bridge and the amount of doming shown in FIG. 4, the amount of doming can be reduced by increasing the vertical pitch of the bridge. Further, if the vertical pitch of the bridge is increased, the opening area of the slot hole is also increased, so that the luminance characteristics are improved.
[0026]
However, if the bridge pitch is increased in this case, moire fringes are generated, and it is necessary to reduce the bridge pitch in order to suppress the generation of moire fringes.
[0027]
For example, if the area of the bridge is reduced in order to suppress the deterioration of the luminance characteristics, the mechanical strength is insufficient, and the bridge is broken by the lateral stress accompanying the longitudinal stress in particular, causing the wrinkle of the shadow mask. Become.
[0028]
The pair of protrusions 22a and 22b solves this problem. By forming the protrusions 22a and 22b, an effect of substantially cutting the scanning line can be obtained. In addition, since the protrusions 22a and 22b are separated from each other, not only the longitudinal stress but also the lateral stress accompanying the longitudinal stress is not applied, so there is no problem in terms of mechanical strength.
[0029]
Furthermore, the protrusions 22a and 22b do not completely block the slot holes in the lateral direction, and are not subjected to stress as described above. For example, the width in the vertical direction can be reduced, and the luminance characteristics can be degraded. Can be suppressed. That is, according to the present embodiment, it is possible to achieve both suppression of the doming amount of the shadow mask that applies tension mainly in the vertical direction and suppression of generation of moire fringes while ensuring mechanical strength and luminance.
[0030]
In order to suppress the occurrence of moire fringes, it is preferable to shift the position of the bridge and the protruding portion in the horizontal direction between the slot hole rows adjacent in the horizontal direction. By shifting the position as described above, mutual interference between the scanning line and the slot hole pattern can be suppressed, which is more effective in suppressing the occurrence of moire fringes. The smaller the shift amount d (FIG. 2) of the positions of adjacent bridges, the longer the distance between adjacent bridges on the same horizontal line, which is effective in suppressing the occurrence of horizontal moire fringes. However, when the amount of positional deviation becomes too small, moire fringes in an oblique direction become conspicuous. For this reason, the positional shift amount d is preferably in the range of 1/2 to 1/5 of the vertical pitch P of the slot holes 20 (vertical pitch of the bridge 21).
[0031]
Further, as shown in FIG. 2B, the vertical pitch e of the protrusions 22a and 22b is preferably 1 mm or less, and the vertical pitch P of the slot holes 20 is preferably in the range of 1.5 to 30 mm. The reason for this is as follows.
[0032]
In a cathode ray tube having no protrusion in the slot hole, assuming that the moire wavelength is λ, the bridge vertical pitch is a, the scanning line interval is s, and the moire mode order is n.
λ = 1 / (n / 2s-s / a)
There is a relationship.
[0033]
In the case of multiple broadcasting systems, the s / a value is 9/8 for NTSC and 11/8 for PAL, so that the suppression of moiré fringes can be achieved with a single shadow mask structure for each broadcast format. Value. For this reason, if the bridge vertical pitch a is 1 mm or less, it is possible to find a solution for suppressing the occurrence of moire fringes with a single shadow mask structure even in the case of a plurality of broadcasting systems.
[0034]
That is, if the bridge vertical pitch a is replaced with the vertical pitch e of the protrusions 22a and 22b of the present invention, the vertical pitch e is preferably 1 mm or less in order to suppress the occurrence of moire fringes.
[0035]
Further, if the vertical pitch P of the slot holes 20 is in the above range, the doming amount can be made smaller than about 90 μm as shown in FIG. Furthermore, it is possible to suppress the vibration of the shadow mask within a practical range while ensuring a certain luminance characteristic and mechanical strength.
[0036]
That is, if the vertical pitch P is too small, the doming amount is large and the luminance characteristics cannot be ensured. Conversely, if the longitudinal pitch P is too large, the doming amount is small, but the mechanical strength is insufficient and the vibration becomes large. If it is in the above ranges, vibration can be suppressed to the level of a conventional press mask by press molding.
[0037]
Furthermore, it is preferable that the area of one pair of the protrusions 22a and 22b is in the range of 20 to 120% of the area of one bridge 20. Such a range is preferable because if the area of the protruding portion is too small relative to the bridge, the occurrence of moire fringes is not sufficiently suppressed, and conversely if too large, the luminance characteristics deteriorate.
Further, it is preferable that the vertical pitch values of the protrusions are different partially or in regions of the shadow mask. For example, if the vertical pitch of the protrusions is made finer in the surrounding area of the shadow mask where moire fringes tend to appear, and the vertical pitch of the protrusions is designed to be coarser in the vicinity of the center, where the moire fringes are hardly affected, the effect of suppressing moire fringes can be further enhanced. A cathode ray tube can be realized.
[0038]
In addition, it is preferable that the value of the vertical pitch of the bridge is different partially or regionally in the shadow mask. For example, the bridge has a vertical pitch p as shown in FIG. 2B of about 15 mm near the center of the shadow mask and about 5 to 10 mm near the lateral end. In this way, since 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, the shadow mask can be prevented from being broken. .
[0039]
As another example, the bridge may have a structure in which the vertical pitch p of the bridge is gradually changed so as to be about 5 to 10 mm in the center of the shadow mask and about 10 to 15 mm in the periphery in the horizontal direction. In this way, it is possible to suppress the amount of thermal doming in the mask lateral direction that is likely to be accumulated around the shadow mask lateral direction. In this case, the number of bridges in the periphery in the lateral direction is reduced, so that the strength is likely to be insufficient.For example, if the longitudinal width of the bridge in the periphery is set wide, the stress applied to the bridge can be reduced. Mask tearing can be prevented.
[0040]
Furthermore, it is good also as a structure which has these two structures together. 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 again decreased near the left and right ends. In this way, it is possible to suppress both the thermal doming amount and the tearing of the shadow mask due to the intensity difference between the non-porous region and the perforated region.
[0041]
In addition, it is preferable that the vertical width of the protruding portion is made different partially or regionally in the shadow mask. The incident angle of the electron beam incident on the shadow mask differs depending on the portion of the shadow mask. In particular, since the angle around the shadow mask is a sharp angle, the rate at which the electron beam is blocked by the bridge and protrusion includes not only the width of the bridge and protrusion but also the shadow mask thickness. In the peripheral portion, the luminance tends to decrease. For this reason, the brightness | luminance of a peripheral part can be improved by narrowing the vertical direction width | variety of a protrusion part in a peripheral part.
[0042]
Further, the protruding portion may be provided only in the peripheral portion without being provided in the central portion of the shadow mask. For example, at the center of the shadow mask, it is configured to have an ordinary substantially rectangular aperture and a bridge, and the vertical pitch of the aperture is gradually increased by gradually increasing the vertical pitch of the bridge as it goes to the periphery of the shadow mask. In addition to increasing the length, a protrusion is provided in the opening, and the number of protrusions is gradually increased.
[0043]
By doing so, the strength of the shadow mask can be ensured in the central portion, which is a reference for applying tension to the shadow mask, and the thermal doming amount does not particularly accumulate in the peripheral portion that is easily affected by thermal doming. Can be. At this time, since the vertical pitch of the bridge in the shadow mask peripheral portion becomes large, the peripheral portion tends to be insufficient in strength, but for this, the bridge stress can be relaxed by widening the vertical width of the bridge. Can be dealt with.
[0044]
In this embodiment, the projecting portions 22a and 22b are formed separately, and the tip portions are disposed so as to face each other. This provides the above-mentioned effects and improves the geomagnetic characteristics. Another effect is obtained.
[0045]
The improvement of the geomagnetic characteristics will be described below. The cathode ray tube blocks external magnetism using components such as a magnetic shield so that the electron beam does not greatly deviate from the original orbit due to external magnetism such as geomagnetism. In general, the fact that color shift occurs when an electron beam is acted on by geomagnetism is called geomagnetic characteristics. The shadow mask that performs color selection also has the role of improving the geomagnetic characteristics by blocking the magnetism from the outside. In particular, the geomagnetism that goes almost vertically to the panel of the cathode ray tube passes through the shadow mask in the creeping direction. In this way, it is prevented from acting directly on the electron beam.
[0046]
Here, when the bridge pitch of the shadow mask is large, in the shadow mask having no protrusion in the slot, the geomagnetism tends to flow in the vertical direction of the shadow mask, but since there are few bridges, in the horizontal direction Difficult to flow. For this reason, especially in the vicinity where the frame and the shadow mask are close, the geomagnetism accumulated in the shadow mask may float in the tube direction, or the area of the slot hole is large, and the geomagnetism may directly pass through the hole. Many of these change the trajectory of the electron beam and cause color misregistration.
[0047]
On the other hand, in the present embodiment, by providing the projecting portions that face each other close to the slot hole, the projecting portions facing each other (22a and 22b in FIG. 2B) play a role of passing geomagnetism. In addition to the geomagnetic flow in the vertical direction, geomagnetism flows not only in the bridge portion but also in the protruding portion in the horizontal direction. For this reason, the geomagnetism does not float and there is an effect of picking up the geomagnetism that tries to pass through the slot hole by this projecting portion, so that the adverse effect of the electron beam on the geomagnetism is small. Therefore, it is possible to obtain a cathode ray tube with little color shift due to geomagnetism.
[0048]
【The invention's effect】
As described above, according to the cathode ray tube of the present invention, the protrusion is formed in the slot hole in the tension type shadow mask, so that the mechanical strength and the luminance are ensured, the doming amount is suppressed, and the moire fringes are obtained. It is possible to achieve both suppression of occurrence and further improve geomagnetic characteristics.
Further, by making the vertical pitch of such shadow mask bridges and protrusions different depending on the position of the shadow mask, it is possible to obtain effects such as ensuring the strength of the shadow mask, reducing the amount of thermal doming, and suppressing luminance deterioration. .
[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 an embodiment of the present invention. FIG. 4 is a view showing 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 slot hole and a protrusion according to an embodiment of the invention. FIG. 7 is a plan view of a slot hole and a protrusion according to another embodiment of the present invention.
DESCRIPTION OF SYMBOLS 10 Mask frame 11 Support body 12 Elastic member 13 Shadow mask 14, 20, 23, 25 Slot hole 21 Bridge 14a, 14b, 22a, 22b, 24a, 24b, 26a, 26b Protrusion part

Claims (9)

A cathode ray tube in which a shadow mask having a number of slot holes formed on a flat plate is stretched and held in a state in which 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 slot holes adjacent in the vertical direction,
A cathode ray tube, wherein the slot hole is formed with protruding portions that protrude into the slot hole from both lateral ends of the slot hole and face each other. A cathode ray tube in which a shadow mask having a number of slot holes formed on a flat plate is stretched and held in a state in which 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 slot holes adjacent in the vertical direction,
The slot holes are formed with projecting portions that project from both lateral ends of the slot holes into the slot holes and face each other.
Cathode ray tube wherein the protrusions, the the slot downhole are arranged at the longitudinal pitch within 1 mm, the vertical pitch of the bridge, which is a range of 1.5～30Mm. The bridges and the protrusions between the rows of the slot holes adjacent in the horizontal direction are displaced in the vertical direction, and the displacement of the bridge position is 1/2 to 1/5 of the vertical pitch of the slot holes. The cathode ray tube according to claim 1 or 2 , wherein the cathode ray tube is within the range of. 3. The cathode ray tube according to claim 1, wherein an area of a pair of projecting portions adjacent in the lateral direction in the slot hole is in a range of 20 to 120% with respect to an area of one bridge. 3. The cathode ray tube according to claim 1, wherein a vertical pitch of the protrusions varies depending on a portion of the shadow mask. The cathode ray tube according to claim 1 or 2 , wherein a vertical pitch of the bridge varies depending on a portion of the shadow mask. 3. The cathode ray tube according to claim 1, wherein a vertical width of the bridge differs depending on a portion of the shadow mask. 3. The cathode ray tube according to claim 1, wherein a vertical width of the protruding portion varies depending on a portion of the shadow mask. A cathode ray tube in which a shadow mask having a number of slot holes formed on a flat plate is stretched and held in a state in which 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 slot holes adjacent in the vertical direction, and the slot hole is 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 in the vicinity of the periphery is formed with protruding portions that protrude into the slot hole from both lateral ends of the slot hole and face each other.

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