JP2002270109A - Shadow mask structure body, cathode-ray tube and method of manufacturing cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shadow mask structure body that can improve a purity drift quantity by reducing thermal expansion of a support bar of a shadow mask, and to provide a cathode-ray tube and a method of manufacturing the cathode-ray tube. SOLUTION: An aperture grille structure body 3 is provided with an aperture grille 7 wherein plural rows of stripe-like slits 70 divided at a grille 71 are arranged at almost equal spaces in an almost perpendicular direction to the longitudinal direction; a frame 8 for supporting the aperture grille 7; and metal bodies 14 fixed to the frame 8. The frame 8 comprises the support bars 8a respectively jointed to pair of opposed end parts 17 of the aperture grille 7 to span the aperture grille 7, and a pair of elastic support bodies 8b for connecting both support bars 8a. Recessed parts or groove parts are formed on the surface 80 of the support bar 8a, and the support bar 8a is curved corresponding to the horizontal screen curved surface of a color CRT.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube, in particular, a color cathode ray tube (hereinafter, referred to as "color CRT") and a shadow mask structure used as a color selection electrode thereof, for example, an aperture grill type shadow mask structure (hereinafter, referred to as "color CRT"). "Aperture grill structure").

[0002]

2. Description of the Related Art FIG. 12 is a cross-sectional view schematically showing a structure of a color CRT according to a first prior art.
Since T has a symmetrical structure with respect to the central axis 1CA, FIG. 12 shows only the cross-sectional structure on the right side. FIG. 13 is a perspective view showing a structure of an aperture grille structure 3 provided in a color CRT according to the first conventional technique.

[0003] As shown in FIG.
A panel 2 having a phosphor screen 130 provided with (red), G (green), and B (blue) phosphor stripes 13 on an inner surface thereof, and an aperture grille structure 3 mounted inside the panel 2. And a funnel 5 joined to the panel 2 via a frit seal portion 4 and an electron gun 6 sealed in the neck of the funnel 5. Among these, the aperture grille structure 3 selectively passes the electron beam e for each color emitted from the electron gun 6 and is a kind of a color CRT shadow mask. As shown in FIG. 13, the aperture grille structure 3 includes an aperture grille 7 having a plurality of striped slits 70 arranged in a pattern, and a frame 8 supporting the aperture grille 7. The frame 8 is composed of a pair of support rods 8a for bridging the aperture grille 7 and a pair of elastic supports 8b connecting the two support rods 8a. The slit 70 is arranged substantially perpendicular to the longitudinal direction, and the direction in which the support rod 8a extends is also substantially perpendicular to the longitudinal direction of the slit 70. The extending direction of the slit 70 substantially matches the extending direction of the phosphor stripe 13 in FIG. Then, the elastic support 8b applies a tension to the aperture grill 7 by the elastic force. Further, the holding member 10 is a member for mounting the aperture grille structure 3 on the panel 2 of FIG. 12, and resistance welding is performed by interposing the mounting plate 9 between the support rod 8a or the elastic support 8b of the frame 8. A fitting hole 11 is provided at one end of the holding member 10 (the end on the side where the mounting plate 9 is not joined).

In the color CRT according to the first prior art having the above-mentioned structure, a portion corresponding to about 80% of the electron beam e collides with a grill 71 defining a slit 70 during operation, and the aperture grill 7 generates heat. I do.
Then, as a result of the heat being transmitted to the frame 8, the frame 8 itself thermally expands and mislanding occurs. That is, as shown in FIG. 12, when the shadow mask is of the aperture grill type, the end of the support rod 8a located in a direction three-dimensionally orthogonal to the extending direction of the phosphor stripe 13 formed on the inner surface of the panel 2 However, when thermal expansion occurs from the position F to the position G along the substantially longitudinal direction, the aperture grill 7 is deformed following the thermal expansion. As a result, the slit 70 at an arbitrary position of the aperture grill 7 is displaced from the position M to the position N. Electron beam e is phosphor screen 1
The route to reach on 30 is when the operation of the color CRT starts,
That is, before the thermal expansion of the support rod 8a, the slit 70 at the position M
, And the electron beam e passes through the fluorescent screen 1.
30 collides with a predetermined position S. However, after the color CRT operates and the support rod 8a thermally expands, the path through which the electron beam e reaches the phosphor screen 130 becomes the path 101 passing through the slit 70 displaced to the position N.
The position on the phosphor screen 130 where the electron beam e collides is displaced from position S to position T. This position T is a predetermined position S
On the phosphor stripes 13 adjacent to the phosphor stripes 13 or on a black matrix (not shown) formed between the phosphor stripes 13.

As described above, since the electron beam e mislandes, there is a problem that the color purity is reduced due to the thermal expansion of the frame 8. Hereinafter, this phenomenon is referred to as purity drift, and the amount of displacement (S → T) of the electron beam e collision position on the phosphor screen 130 is referred to as purity drift.

FIG. 14 shows a color C according to the second prior art.
FIG. 15 is a sectional view schematically showing the structure of the RT, and FIG.
14 is a cross-sectional view schematically showing a structure of a color CRT according to the related art, in which the aperture grille structure 3 shown in FIG. 13 is adopted. In FIGS. 14 and 15 and FIG. 16 to be described later, the illustration of the phosphor stripe 13 is omitted.

As shown in FIG. 14, a support rod 8a is provided on the aperture grille 7 in a direction perpendicular to the plane of the drawing, and a mounting plate 9 fixed to each support rod 8a includes a high thermal expansion material 9a and a low thermal expansion material 9b. Are formed to form a bimetal structure. A support rod 8a is attached to the low thermal expansion material 9b, and a holding member 10 is attached to the high thermal expansion material 9a. A protruding fixing pin 12 is provided on the inner peripheral surface of the panel 2, and the fixing pin 12 is attached to the holding member 1.
The aperture grille structure 3 is mounted inside the panel 2 by being fitted into the fitting hole 11 of No. 0. FIG.
As shown in FIG. 5, a support rod 8a is provided on the aperture grill 7.
Are provided in parallel with the paper surface, and a holding member 10 fixed to each support rod 8a via a mounting plate 9 is a high thermal expansion material 10
a and a low-thermal-expansion material 10b are juxtaposed to form a bimetal structure. The high thermal expansion material 10a is located on the support rod 8a side. The grill surface 7A is a surface facing the fluorescent screen 130 in the aperture grill 7.

[0008] The second prior art having the above structure and the third prior art
In the related art, when the color CRT is operated, the electron beam e collides with the grill 71 of the aperture grill 7, and the heat generated by the collision is transmitted to the mounting plate 9 and the holding member 10 via the support rod 8a. Then, the holding member 10
The bimetal structure is curved with the fitting hole 11 as a fulcrum, and the position of the grill surface 7A is displaced toward the phosphor screen 130 side.
The state of this bending is shown by broken lines in FIGS.

FIG. 16 shows a color C according to the fourth prior art.
It is sectional drawing which shows the structure of RT typically. As shown in FIG. 16, in the fourth prior art, a metal body 14 is attached to the surface of the bottom 8bB of the elastic support 8b opposite to the surface of the aperture grill 7 in the structure shown in FIG. ing. The coefficient of thermal expansion of the metal body 14 is larger than that of the elastic support 8b, and the elastic modulus is almost the same as that of the elastic support 8b.
The width of the metal member 14 in the short direction (perpendicular to the paper surface) is the same as the width of the bottom portion 8bB of the elastic support 8 in the short direction, and the width in the longitudinal direction (the left-right direction of the paper surface) is equal to that of the bottom portion 8bB. It is almost equal to the length in the longitudinal direction. Also in this fourth technique, the elastic support 8
The bimetal structure composed of the bottom 8bB of b and the metal body 14 is curved with the fitting hole 11 as a fulcrum, and the position of the grill surface 7A is displaced toward the phosphor screen 130 side.

As described above, the bimetal structure is curved,
By displacing the position of the grill surface 7A toward the phosphor 130, the purity drift, which is a problem in the first related art, is corrected. FIG. 17 is a diagram showing how the purity drift is corrected by adopting the bimetal structure. The broken line in the figure shows the displacement of the position of the grill surface 7A in the first prior art which does not employ the bimetal structure, and the two-dot chain line shows the grill in the second to fourth prior arts employing the bimetal structure. The displacement of the position of the surface 7A is shown.

In the color CRT according to the first prior art, after the support rod 8a thermally expands, the slit 70 is displaced from the position M to the position N, and the trajectory of the electron beam e colliding with the phosphor screen 130 changes. However, in the second to fourth prior arts, the slit 70 can be displaced from the position M to the position L by using the displacement of the position of the grill surface 7A due to the bending of the bimetal structure. Therefore, CR
The trajectory 101 of the electron beam e after the T operation can be made coincident with the trajectory 100 at the start of the CRT operation.
Drift is corrected.

Further, in addition to the correction of the purity drift by the bimetal structure, the aperture grill 7
And the frame 8 is subjected to a blackening process to improve the emissivity of the aperture grille 7 and the frame 8 so that the purity
The drift amount can be reduced. For example, after the aperture grill 7 is stretched over the frame 8, the blackening process is performed in a modified gas atmosphere at about 500 ° C. As a result, the surface of the aperture grill 7 and the frame 8 having the emissivity of about 0.2 (the emissivity of a perfect black body is assumed to be 1.0) is
A blackened film containing ₃ O ₄ as a main component is generated, and each emissivity can be improved to about 0.45 to 0.5. When the emissivity is improved, the thermal expansion of the aperture grill 7 and the frame 8 is reduced, and the purity drift amount of the electron beam e passing through the slit 70 is reduced.

[0013]

However, there has been a problem that the purity drift amount cannot be sufficiently reduced only by the bimetal structure and the blackening treatment as described above, and the color purity of the color CRT becomes unsatisfactory.

Accordingly, the present invention has been made to solve the above-mentioned problems, and has been made in order to reduce the thermal expansion of a support rod and improve the amount of purity drift, a shadow mask assembly, a cathode ray tube, and An object of the present invention is to provide a method for manufacturing a cathode ray tube.

[0015]

Means for Solving the Problems Claim 1 of the present invention
The shadow mask structure described in (1) includes a shadow mask, and support rods respectively joined to a pair of opposite ends of the shadow mask, and the support rod has a plurality of concave portions on a surface.

According to a second aspect of the present invention, there is provided a shadow mask assembly according to the first aspect, wherein the recesses are connected to each other to form a groove.

According to a third aspect of the present invention, there is provided a cathode ray tube, wherein the shadow mask assembly according to any one of the first and second aspects, and the shadow mask assembly is mounted, and at least faces the support rod. And a radiation film formed on the side surface of the panel and arranged to face the support bar.

The cathode ray tube according to a fourth aspect of the present invention is the cathode ray tube according to the third aspect, wherein an aluminum film is formed on the panel, and the radiation film is the aluminum film. It is formed by oxidizing the film.

The cathode ray tube according to a fifth aspect of the present invention is the cathode ray tube according to the third aspect, wherein the radiation film is made of graphite.

The cathode ray tube according to claim 6 of the present invention is the cathode ray tube according to claim 5, wherein a black matrix is formed on the panel, and the radiation film is formed of the black film. It is part of the matrix.

According to a seventh aspect of the present invention, there is provided a method of manufacturing a cathode ray tube, comprising: (a) a shadow mask; and a plurality of concave portions formed on a surface of the shadow mask. Preparing a shadow mask structure including a support rod; and (b) having a front surface on which the shadow mask structure is mounted, facing the shadow mask and on which a phosphor is formed, and a side surface facing the support rod. And (c) after the step (b), preparing an aluminum film on the panel from the front surface of the panel to a portion of the side surface facing the support rod so as to cover the phosphor. And (d) after the step (c), oxidizing at least a portion of the aluminum film facing the support rod.

According to a eighth aspect of the present invention, there is provided a method for manufacturing a cathode ray tube, comprising: (a) a shadow mask; and a pair of opposite ends of the shadow mask, the surface having a plurality of concave portions. Preparing a shadow mask structure including a support rod; and (b) having a front surface on which the shadow mask structure is mounted, facing the shadow mask and on which a phosphor is formed, and a side surface facing the support rod. (C) forming a black matrix on the panel after the step (b), from the front surface of the panel to a portion of the side surface facing the support rod, and (d) After the step (c), an aluminum film is formed on the black matrix from the front surface of the panel to a portion of the side surface facing the support bar. In which and forming.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a cross-sectional view schematically showing the structure of the color CRT according to the first embodiment, which is a cross-sectional view near the panel on the front surface of the color CRT. FIG. 2 is a perspective view schematically showing the structure of the aperture grille structure 3 provided in the color CRT shown in FIG.

As shown in FIG. 1, the color CRT according to the first embodiment includes a panel 2 having a front surface 19 and a side surface 20, and an aperture grille structure 3 mounted inside the panel 2. On the front surface 19 of the panel 2 is formed a phosphor screen 130 provided with phosphor stripes (not shown).

Next, the structure of the aperture grille structure 3 according to the first embodiment will be described in detail. As shown in FIG. 2, in the aperture grille structure 3 according to the first embodiment, a plurality of rows of striped slits 70 partitioned by the grille 71 are substantially perpendicular to the longitudinal direction (hereinafter, referred to as “slit direction”). An aperture grill 7 is provided at substantially equal intervals in the direction, a frame 8 supporting the aperture grill 7, and a metal body 14 fixed to the frame 8. The frame 8 includes a support rod 8a that is joined to a pair of ends 17 facing each other in the slit direction of the aperture grille 7 and spans the aperture grille 7, and a pair of elastic supports 8b that connect the support rods 8a.

The support rod 8a is composed of a vertical plate 8aA and a horizontal plate 8aB made of steel having a thickness of about 5 mm. The vertical plate 8aA and the horizontal plate 8aB are connected at their short ends, and have a substantially L-shaped cross section perpendicular to the longitudinal direction as a whole. Then, the end in the short direction of the vertical plate 8aA opposite to the short end connected to the horizontal plate 8aB is substantially perpendicular to the slit direction so that the aperture grill 7 and the horizontal plate 8aB face each other. The aperture 17 is joined to the end 17 of the aperture grill 7.

The vertical plate 8a opposite to the horizontal plate 8aB
A surface 80 (the vertical plate 8aA is a part of the support rod 8a, so the “surface 80 of the vertical plate 8aA” may be referred to as the “surface 80 of the support rod 8a”). 16 are formed. And the vertical plate 8aA
The horizontal plate 8aB is curved in a plane perpendicular to the slit direction in accordance with the horizontal screen curved surface of the color CRT. Therefore, the aperture grill 7 joined to the support rod 8a is also curved according to the curved surface of the screen.

The elastic support 8b includes a pair of arms 8bA and a bottom 8bB. The bottom 8bB has substantially the same length as the end of the aperture grille 7 in the slit direction and extends in the slit direction. One end of each arm 8bA is connected to both ends of the bottom 8bB. The other end of each arm 8bA is joined to the horizontal plate 8aB of each support rod 8a, and the arm 8bA is curved from the bottom 8bB to the support rod 8a. The elastic support 8b having such a structure applies tension to the aperture grill 7 in the slit direction by its elastic force.

The metal member 14 is formed on the bottom 8b of the elastic support 8b.
B is attached to the surface opposite to the aperture grille 7 and forms a bimetal structure together with the elastic support 8b. Specifically, the coefficient of thermal expansion of the metal body 14 is larger than that of the elastic support 8b, and the elastic modulus is substantially the same as that of the elastic support 8b. The width of the metal member 14 in the short direction is the same as the width of the bottom portion 8bB of the elastic support member 8 in the short direction (vertical direction in FIG. 1), and in the longitudinal direction (right and left in FIG. 1). Direction) is substantially equal to the longitudinal length of the bottom 8bB.

The holding member 10 is a vertical plate 8aA of the support rod 8a.
And, it is fixed to the bottom portion 8bB of the elastic support member 8b through a mounting plate 9 by resistance welding or the like. A fitting hole 11 is provided at one end of each holding member 10 (the end on the side where the mounting plate 9 is not joined).
Is provided.

A fixing pin 12 projecting inward is provided on a side surface 20 of the panel 2 of FIG.
Is inserted into the fitting hole 11 of the holding member 10 in the aperture grille structure 3, whereby the aperture grille structure 3 is mounted inside the panel 2. The front surface 19 of the panel 2 faces the aperture grille 7 of the aperture grille structure 3, and the side surface 20 of the panel 2 faces the support rod 8a of the aperture grille structure 3. In a color CRT having such a structure, an electron beam emitted from an electron gun (not shown) mounted on a neck portion (not shown) passes through a slit 70 of the aperture grill 7 and has a fluorescent screen. At 130, the phosphor stripe emits light and an image is displayed on the screen.

Next, the concave portion 15 or the groove 1 formed on the surface 80 of the vertical plate 8aA of the support rod 8a, which is a feature of the present invention.
6 will be described. 3 and 5 show the portion 50 in FIG.
3 is an enlarged view when the concave portion 15 is formed on the surface 80 of the vertical plate 8aA, and FIG. 5 is an enlarged view when the groove portion 16 is formed on the surface 80 of the vertical plate 8aA. It is. 4 is a cross-sectional view taken along line AA of FIG. 3, and FIG. 6 is a cross-sectional view taken along line BB of FIG.

As shown in FIG. 2, the surface 8 of the vertical plate 8aA
At 0, a plurality of concave portions 15 are formed in a staggered manner. Specifically, as shown in FIGS. 4A to 4C, the hemispherical concave portion 1 is formed.
5a, cylindrical recess 15b or conical recess 15c
Are formed in a zigzag pattern. In FIGS. 3 and 4, the recesses 15 are arranged in a staggered manner, but they may be arranged at equal intervals in the vertical and horizontal directions. Further, the shape of the recess 15 may be a rectangular parallelepiped.

On the other hand, as shown in FIG. 5, the groove 16 may be formed on the surface 80 of the vertical plate 8aA. In particular,
As shown in FIGS. 6A to 6C, the rectangular grooves 15a, U
The groove 15b of the mold or the groove 15c of the V-shape extends in the vertical and horizontal directions and is formed on the surface 80 of the vertical plate 8aA. Here, FIGS.
When the recesses 15 are connected vertically and horizontally, the recesses 15 form a groove structure. Therefore, it can be said that the groove 16 shown in FIGS. 5 and 6 is formed by connecting the plurality of recesses 15 shown in FIGS. The above-mentioned concave portion 15 and groove portion 16 can be formed by mechanical working such as coining or cutting by pressing or rolling.

The aperture grille structure 3 according to the first embodiment having the above-described structure includes the vertical plate 8a of the support rod 8a.
Since the concave portion 15 or the groove portion 16 is formed on the surface 80 of A, the apparent surface area of the support rod 8a increases,
The radiation surface of heat expands. Therefore, the heat radiation characteristics of the frame 8 having the support rod 8a are improved, and the thermal expansion can be reduced. As a result, the deformation of the aperture grille 7 due to the thermal expansion of the frame 8 is suppressed, and the purity drift amount of the electron beam passing through the slit 70 is improved.

FIG. 7 is a diagram showing the emissivity of the frame 8 of the aperture grille structure 3 according to the first embodiment.
The emissivity after the blackening treatment is shown. The ambient temperature when measuring the emissivity is from room temperature to 100 ° C. In general, the higher the emissivity, the better the heat radiation characteristics. The item of “shape” in the figure is
This corresponds to the shape of the recess 15 or the groove 16 shown in FIGS. The items of “pitch (P)”, “width (W)”, and “depth (D)” in the drawings correspond to the dimensions indicated by P, W, and D in FIGS. Further, “None” described in the item of “Shape” in the figure indicates that the concave portion 15 and the groove 16 are not formed on the surface 80 of the vertical plate 8aA, and is described in the column of “None”. The emissivity used is the emissivity of the frame 8 of the aperture grille structure 3 subjected to the blackening process in the first prior art.

As shown in FIG. 7, the surface 8 of the vertical plate 8aA
By forming the concave portion 15 or the groove portion 16 at 0,
The emissivity of the frame 8 which was 0.45 to 0.50 was 0.60 to 0.70 when the recess 15 was formed,
Is increased to 0.65 to 0.75. Therefore, it can be said that the heat radiation characteristics of the frame 8 are improved. The emissivity of the frame 8 is higher when the groove 16 is formed than when the recess 15 is formed on the surface 80 of the vertical plate 8aA. This is because the support rod 8a having the groove 16 has a larger apparent surface area than the support rod 8a having the recess 15, so that the heat radiation surface is enlarged.

FIG. 8 shows a color CRT according to the first embodiment.
FIG. 6 is a diagram showing the amount of purity drift of the data. The solid line in the figure indicates the amount of purity drift of the color CRT equipped with the aperture grille structure 3 in which the hemispherical concave portion 15a shown in FIG. 7 is formed on the surface 80 of the vertical plate 8aA,
The broken line in the figure indicates the amount of purity drift of the color CRT according to the fourth prior art shown in FIG. The purity drift amount shown in FIG. 8 is an actually measured value near the screen corner where the normal drift amount is large.

The horizontal axis indicates the elapsed time of the operation of the color CRT, and the vertical axis indicates the value when the purity drift amount at the start of the operation of the color CRT is set to zero, that is, the drift amount over time. ing.

As shown in FIG. 8, the surface 8 of the vertical plate 8aA
By forming the hemispherical concave portion 15a at 0, the amount of purity drift is reduced. Note that even in the case of a color CRT including the aperture grille structure 3 in which the recesses 15 or the grooves 16 of other shapes shown in FIG. 7 are formed, the characteristic of the purity drift amount is almost the same as the characteristic shown by the solid line in FIG. There is no difference.

As described above, the color C according to the first embodiment is
According to RT, the recess 15 or the groove 16 is formed in the support rod 8a.
, The amount of purity drift of the electron beam is reduced. As a result, the color purity of the color CRT can be improved.

In the first embodiment, the vertical plate 8aA
The concave portion 15 or the groove portion 16 was formed on the surface 80 of
The recess 15 or the groove 16 may be formed on the surface of the vertical plate 8aA opposite to the surface 80, or may be formed on the surface of the horizontal plate 8aB.

If the recess 15 or the groove 16 is formed on the entire surface of the vertical plate 8aA, it becomes difficult to attach the mounting plate 9 to the vertical plate 8aA by resistance welding. The concave portion 15 or the groove portion 16 may not be provided on the surface.

Embodiment 2 FIG. 9 is a sectional view schematically showing the structure of a color CRT according to the second embodiment.
FIG. 2 is a cross-sectional view near the panel on the front surface of the color CRT, similarly to FIG. As shown in FIG. 9, in the color CRT according to the second embodiment, an aluminum film 21 called a metal back is formed on the front surface 19 and the side surface 20 of the panel 2 in the color CRT according to the first embodiment. Then, graphite 30 as a radiation film is formed on a portion of the aluminum film 21 facing the support rod 8a.

Specifically, from the front surface 19 of the panel 2 to the portion of the side surface 20 facing the support rod 8a, aluminum is covered so as to cover the phosphor stripes (not shown) formed on the front surface 19 of the panel 2. A film 21 is formed on the panel 2 by vapor deposition. Then, graphite 30 is formed by spraying on a portion of the aluminum film 21 facing the support rod 8a. The aluminum film 21 is called a metal back, and for example, can reflect light emitted by the luminous body stripe to the front surface, and can increase luminous brightness. The other structure is the same as that of the color CRT according to the first embodiment, and the description is omitted here.

In the conventional color CRT, since the graphite 30 which is a radiation film is not formed on the aluminum film 21, the support rod 8a faces the aluminum film 21 having an emissivity of about 0.02. Since the emissivity of ordinary graphite is about 0.8, it is higher than the emissivity of the aluminum film 21. According to Kirchhoff's law, at a constant temperature, the ratio between the emissivity and the absorptivity of heat is constant, so that the graphite 30 having a higher emissivity than the aluminum film 21 absorbs heat better than the aluminum film 21. Since the graphite 30 is formed at a position facing the support rod 8a, the support rod 8a
The heat radiated from a is absorbed by the graphite 30 and the frame 8
The overall heat radiation characteristics are improved. As a result, deformation of the aperture grill 7 is suppressed, and the amount of purity drift of the electron beam passing through the slit 70 is reduced.

FIG. 10 shows a color CR according to the second embodiment.
FIG. 10 is a diagram showing a purity drift amount of T. The two-dot chain line in the figure indicates the aperture grille structure 3 in which the hemispherical recess 15a shown in FIG. 7 is formed on the surface 80 of the support rod 8a.
Indicates the amount of purity drift of a color CRT having a color CRT therein, and the broken line in the figure indicates the amount of purity drift of the color CRT according to the fourth prior art shown in FIG. 16, and the solid line in the figure indicates the embodiment. 6 shows the amount of purity drift of the color CRT according to No. 1. The purity drift amount shown in FIG. 10 is an actually measured value near the screen corner where the drift amount is usually large.

The horizontal axis shows the elapsed time of the operation of the color CRT, and the vertical axis shows the value when the purity drift amount at the start of the operation of the color CRT is set to zero, that is, the drift amount over time. ing.

As shown in FIG. 10, the surface 8 of the support rod 8a is
0, a hemispherical concave portion 15a is formed, and the aluminum film 2
By forming the graphite 30 in a portion facing the first support rod 8a, the amount of purity drift can be reduced by the conventional color CR.
T and the color CRT according to the first embodiment are reduced. In addition, the time (time constant) required for the amount of purity drift to reach the stable range is also reduced. It should be noted that even if the color CRT includes the aperture grille structure 3 in which the concave portion 15 or the groove portion 16 having the other shape shown in FIG. 7 is formed, the characteristic of the purity drift amount is as shown in FIG.
There is almost no difference from the characteristics indicated by the two-dot chain line in FIG.

As described above, the color C according to the second embodiment
According to RT, the recess 15 or the groove 16 is formed in the support rod 8a.
Is formed, and the graphite 30 is formed in a portion of the aluminum film 21 facing the support rod 8a, so that the purity drift amount of the electron beam is further reduced. as a result,
The color purity of the color CRT can be further improved.

The color CRT according to the second embodiment
In the above, the graphite 30 is formed on the portion of the aluminum film 21 facing the support rod 8a. However, the purity drift amount can be reduced by oxidizing the portion of the aluminum film 21 facing the support rod 8a. Specifically, the emissivity of the aluminum film 21 is improved from about 0.02 to about 0.4 by oxidizing. Therefore, similarly to the above-described graphite 30, the heat released from the support rod 8a is absorbed by the oxidized portion of the aluminum film 21, and the heat radiation characteristics of the entire frame 8 are improved. As a result, the purity drift amount is substantially the same as the characteristic indicated by the two-dot chain line in FIG. The aluminum film 2
1 may be oxidized not only in the portion facing the support rod 8a but also in the entire surface.

The emissivity of the portion facing the support rod 8a can be improved only by oxidizing the aluminum film 21 which is usually formed as a metal back. The material cost can be reduced as compared with the structure further provided in the device.

Embodiment 3 FIG. 11 is a cross-sectional view schematically showing the structure of the color CRT according to the third embodiment, and is a cross-sectional view near the panel on the front surface of the color CRT, similarly to FIGS. As shown in FIG.
The color CRT according to the first embodiment is the same as the color CRT according to the first embodiment described above, except that
A black matrix (also referred to as a “black stripe”) 31 is formed thereon, and an aluminum film 21 is formed on the black matrix 31 except for a portion facing the support bar 8a.

Specifically, a black matrix 31 formed between a plurality of phosphor stripes (not shown) on the front surface 19 of the panel 2 is
0 extends to a portion opposed to the support rod 8a. That is, the black matrix 31 is formed on the panel 2 from the front surface 19 of the panel 2 to the portion of the side surface 20 facing the support bar 8a. Then, the front surface 19 of the panel 2
To a portion of the side surface 20 that faces the support bar 8a,
An aluminum film 21 is formed on a black matrix. The other structure is the same as that of the color CRT according to the first embodiment, and the description is omitted here.

Since the black matrix 31 is usually formed of graphite (also called “graphite”), the heat radiated from the support rods 8a is transferred to the black matrix 31 similarly to the color CRT according to the second embodiment. Absorbed. Therefore, the heat radiation characteristics of the entire frame 8 are improved, and the deformation of the aperture grill 7 is suppressed. As a result, the purity drift amount of the electron beam passing through the slit 70 exhibits substantially the same characteristics as those indicated by the two-dot chain line in FIG.

In the above-described first to third embodiments, the aperture grill type shadow mask is used as the shadow mask of the color CRT. The effects of the present invention described in each of the embodiments are obtained even when a slot-type shadow mask having a rectangular hole through which a beam passes is used.

[0057]

According to the shadow mask structure according to the first aspect of the present invention, since the support rod joined to the shadow mask has a plurality of recesses on the surface thereof, heat is radiated from the support rod. The surface is enlarged and the thermal expansion of the support rod is reduced. Therefore, thermal deformation of the shadow mask is suppressed, and the amount of purity drift of the electron beam passing through the hole of the shadow mask is improved.

According to the shadow mask structure of the second aspect of the present invention, since the recesses of the support rod are connected to each other to form a groove, the heat radiation area of the support rod further increases, and Thermal expansion is further reduced.

According to the shadow mask structure of the third aspect of the present invention, since the radiation film is formed facing the support rod, the radiant heat from the support rod is absorbed by the radiation film. Therefore, the thermal expansion of the support rod is further reduced.

According to the cathode ray tube according to claim 4 of the present invention and the method for manufacturing a cathode ray tube according to claim 7,
Since an aluminum film usually provided for improving the brightness of the cathode ray tube can be used, it is not necessary to further provide a radiation film. Therefore, the material cost is reduced as compared with the cathode ray tube according to the third aspect.

According to the cathode ray tube according to the fifth aspect of the present invention, graphite usually has a higher emissivity than that obtained by oxidizing an aluminum film. Thermal expansion is reduced.

Further, according to the cathode ray tube according to claim 6 and the method for manufacturing a cathode ray tube according to claim 8 of the present invention,
Because the black matrix usually provided for improving the brightness of the cathode ray tube can be used as the radiation film,
There is no need to provide additional graphite. Therefore, the material cost is lower than that of the cathode ray tube according to claim 6.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a color CRT according to a first embodiment.

FIG. 2 is a perspective view showing a structure of an aperture grille structure 3 according to the first embodiment.

FIG. 3 is an enlarged view showing the structure of the aperture grille structure 3 according to the first embodiment.

FIG. 4 is a sectional view showing the structure of the aperture grille structure 3 according to the first embodiment.

FIG. 5 is an enlarged view showing the structure of the aperture grille structure 3 according to the first embodiment.

FIG. 6 is a sectional view showing a structure of the aperture grille structure 3 according to the first embodiment.

FIG. 7 is a diagram showing the emissivity of the frame 8 of the aperture grille structure 3 according to the first embodiment.

FIG. 8 is a diagram showing a purity drift amount of the color CRT according to the first embodiment.

FIG. 9 is a sectional view showing a structure of a color CRT according to the second embodiment.

FIG. 10 is a diagram showing a purity drift amount of the color CRT according to the second embodiment.

FIG. 11 is a sectional view showing a structure of a color CRT according to a third embodiment.

FIG. 12 is a cross-sectional view illustrating a structure of a color CRT according to a first related art.

FIG. 13 is a perspective view showing the structure of an aperture grille structure 3 according to the first conventional technique.

FIG. 14 is a sectional view showing the structure of a color CRT according to a second conventional technique.

FIG. 15 is a sectional view showing the structure of a color CRT according to a third conventional technique.

FIG. 16 is a sectional view showing a structure of a color CRT according to a fourth conventional technique.

FIG. 17 is a diagram showing how the purity drift is corrected.

[Explanation of symbols]

2 panel, 3 aperture grille structure, 7 aperture grille, 8a support rod, 15 recess, 16 groove,
19 front, 20 side, 21 aluminum film, 30
Graphite, 31 black matrix.

Claims (8)

[Claims] 1. A shadow mask structure comprising: a shadow mask; and support rods respectively joined to a pair of opposite ends of the shadow mask, wherein the support rod has a plurality of concave portions on a surface. 2. The shadow mask structure according to claim 1, wherein the recesses are connected to each other to form a groove. 3. The shadow mask structure according to claim 1, wherein the shadow mask structure is mounted, and a panel has at least a side surface facing the support rod. A cathode ray tube comprising: a radiation film formed on a side surface and arranged to face the support rod. 4. The cathode ray tube according to claim 3, wherein an aluminum film is formed on the panel, and the radiation film is formed by oxidizing the aluminum film. 5. The cathode ray tube according to claim 3, wherein said radiation film is made of graphite. 6. A black matrix is formed on the panel, and the radiation film is a part of the black matrix.
A cathode ray tube according to claim 5. 7. (a) a shadow mask, joined to a pair of opposite ends of the shadow mask,
Providing a shadow mask structure comprising: a support bar having a plurality of recesses on its surface; and (b) a front surface on which the shadow mask structure is mounted, facing the shadow mask and on which a phosphor is formed; and the support bar. (C) after the step (b), covering the phosphor from the front surface of the panel to a portion of the panel facing the support bar after the step (b). A method for manufacturing a cathode ray tube, comprising: a step of forming an aluminum film on the panel; and (d) after the step (c), oxidizing at least a portion of the aluminum film facing the support rod. 8. (a) a shadow mask; and a pair of opposed ends of the shadow mask,
Providing a shadow mask structure comprising: a support rod having a plurality of recesses on its surface; and And (c) after the step (b), a black matrix is formed on the panel from the front surface of the panel to a portion of the panel facing the support bar. And (d) after the step (c), forming an aluminum film on the black matrix from the front surface of the panel to just before a portion of the side surface facing the support bar. A method for manufacturing a cathode ray tube.