JP2003016955A - Color cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color cathode-ray tube that can improve a focusing property of electron beams over the whole region of a screen and improve the brightness of the whole region of the screen. SOLUTION: A shadow mask is provided with a plurality of aperture trains 19 arranged in parallel. Each aperture train 19 is composed of a plurality of apertures 34 arranged in a line with prescribed spaces. Striped dielectric layers 50 charged by the irradiation of electron beams to focus the electron beams on the aperture side are formed on both sides of each aperture train 19 on the electron gun structure side surface of the shadow mask 12. The average surface roughness of the dielectric layer is 0.2 μm or less, the dielectric constant is 3 or more, and the volume resistivity is 1.0E+12 to 1.0E+15 Ω.cm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube having a shadow mask, and more particularly to a shadow mask having a structure for improving brightness over the entire screen.

[0002]

2. Description of the Related Art Generally, a color cathode ray tube includes a vacuum envelope having a substantially rectangular panel and a funnel. A phosphor screen is formed on the inner surface of the effective portion of the panel. In the vacuum envelope, a substantially rectangular shadow mask is arranged so as to face the phosphor screen. The shadow mask has a substantially rectangular effective surface facing the phosphor screen, and a large number of electron beam passage apertures are formed in a predetermined array on the effective surface.

On the other hand, in the neck of the funnel, an electron gun assembly for emitting an electron beam is arranged. The three electron beams emitted from the electron gun assembly are deflected by a deflection magnetic field generated from a deflection yoke mounted on the outside of the funnel, and horizontally and vertically pass through the phosphor screen through the electron beam passage opening of the shadow mask. Scan in the direction.
As a result, a color image is displayed. At this time, each of the openings of the shadow mask selects the three electron beams emitted from the electron gun structure and makes them enter the desired three-color phosphor layer forming the phosphor screen.

The shape of the electron beam passage opening of the shadow mask is roughly classified into two types, a circular shape and a rectangular shape. In a display tube for displaying characters and figures, a shadow mask mainly having a circular opening is used. Is used. Further, in a consumer color picture tube used in a general household, a shadow mask mainly having a rectangular opening is used. In any case, each opening basically communicates with a large hole opened on the surface of the shadow mask facing the phosphor screen and a small hole opened on the surface facing the electron gun structure. It is composed of holes.

The brightness of the screen is one of the important characteristics of the color cathode ray tube. Various techniques have been studied to improve the brightness of the color cathode ray tube, but the techniques that are currently inherited include the use of a metal back layer arranged on the electron gun structure side of the phosphor screen and various types of high Examples include the use of brightness phosphors.

Further, in recent years, in order to cope with a large screen, a method of increasing the brightness by increasing a high voltage called Eb of the color cathode ray tube has been adopted. This Eb
Is a voltage applied to the phosphor screen of the color cathode ray tube, the shadow mask, and the inner surface of the funnel.
By increasing b, the speed of the electron beam can be increased and the energy of collision with the phosphor can be increased. As a result, the brightness of the phosphor is improved.

However, when Eb is raised, the transit time of the electron beam passing through the deflection magnetic field generated from the deflection yoke is shortened, and the deflection range of the electron beam is reduced accordingly. Therefore, in this case, it is necessary to increase the deflection power, which is not desirable from the viewpoint of energy saving.

Further, although it has not been put to practical use, attempts have been made to improve the brightness by a method called a focus mask. The principle of the focus mask will be described below.

The color cathode ray tube currently in the mainstream is
As described above, the shadow mask functioning as a color selection electrode is provided inside. Then, the electron beam emitted from the electron gun assembly is deflected by the deflection magnetic field, and then a part thereof passes through the aperture of the shadow mask and collides with the phosphor. At this time, of the electron beams emitted from the electron gun assembly, about 20% of the electron beams pass through the apertures of the shadow mask, and about 80% of the remaining electron beams only collide with the shadow mask and the brightness of the screen increases. Does not contribute to.
The focus mask is intended to cause a part of the electron beam that collides with such a shadow mask to reach the phosphor screen.

Specifically, in the focus mask, the electrodes are arranged on the surface of the shadow mask on the electron gun assembly side. Then, a potential different from that of the shadow mask is applied to this electrode to form a quadrupole lens with the shadow mask and the electrode. The quadrupole lens changes the trajectory of the electron beam impinging on the shadow mask and guides the electron beam to the phosphor. Is configured.

The structure of this focus mask is, for example,
JP-A-52-87970, JP-A-52-8797
No. 2, JP-A-52-89068, JP-A-56.
As disclosed in U.S. Pat. No. 3,951, and U.S. Pat. No. 4,427,918, a structure is proposed in which an insulating layer is disposed on the surface of the shadow mask on the side of the electron gun assembly and electrodes are formed on the insulating layer. The manufacturing method thereof is disclosed in JP-A-63-6.
No. 2129 is disclosed.

[0012]

However, JP-A-52-87970, JP-A-52-89772, JP-A-52-89068, and JP-A-56-39.
In the configuration shown in Japanese Patent Publication No. 51, since both electrodes are formed of a metal plate, it is difficult to accurately position these two electrodes over the entire screen.

Further, in the above-mentioned publicly known document, as another structure, the aperture of the shadow mask is formed by arranging two interdigital electrodes orthogonally to each other, but in such a structure, the shadow mask is formed. It becomes difficult to form the curved surface. At the same time, it is substantially impossible to form the apertures of the shadow mask in a staggered pattern in which the apertures are displaced by 1/2 pitch in the vertical direction of the apertures. If the apertures cannot be arranged in a staggered pattern, interference fringes called moire will occur on the screen,
The display quality of the screen is greatly deteriorated, and the feasibility is low.

Further, in the structure shown in US Pat. No. 4,427,918, a portion called a ridge in which the height of the non-perforated portion extending in the direction of the row of apertures of the shadow mask is made higher than that of the other portion. And the electrode is formed on it. With such a structure, it is virtually impossible to partially change the shape of the electrode. Therefore, it is difficult to dispose different electrodes in the central portion of the screen and in the peripheral portion of the screen, and when used in a color cathode ray tube, it is unlikely that a good electron beam focusing effect can be obtained over the entire screen.

Further, in such a structure, this is the same as in the case of using a shadow mask material having a plate thickness thicker than the conventional one, and a part of the electron beam deflected to the peripheral portion of the screen is a ridge portion of the shadow mask. May collide with. In this case, a shadow due to the thickness of the shadow mask, which is generally called vignetting, occurs. Therefore, it can be expected that the improvement of the brightness around the screen will be reduced.

As described above, in the conventionally proposed focus mask, high precision is required for electrode formation, and it is difficult to shape the shadow mask surface into a desired shape. Further, there is a problem that the degree of freedom of forming the electrodes is low and the electron beam cannot be controlled substantially.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to improve the focus characteristic of an electron beam over the entire screen and to improve the brightness over the entire screen. It is to provide a color cathode ray tube capable of performing the above.

[0018]

In order to solve the above-mentioned problems, a color cathode ray tube according to the present invention is provided with an envelope having a panel having a phosphor screen arranged on its inner surface, and an envelope provided inside the envelope. An electron gun structure for emitting an electron beam toward the phosphor screen and a large number of electron beams arranged to face the phosphor screen and for selecting the electron beam emitted from the electron gun structure. A shadow mask having an aperture, and an electron lens located on both sides of the aperture on the surface of the shadow mask on the side of the electron gun structure, which is charged by irradiation of the electron beam and acts on the electron beam. A patterned dielectric layer is formed which has an average surface roughness of 0.2 μm or less, a dielectric constant of 3 or more, and a volume resistivity of Is 1.0 +12 more than 1.0E + 15Ω · cm
It is characterized by the following.

According to the color cathode ray tube of the present invention, when the dielectric layers are irradiated with an electron beam during operation, each dielectric layer has an appropriate average surface roughness and dielectric constant, so that the dielectric layers can be efficiently used. It becomes negatively charged. This causes the dielectric layer to
Form an electron lens that acts on the electron beam. When passing through the aperture of the shadow mask, the electron beam passes through the dielectric layers provided on both sides of the aperture, receives a repulsive force from both sides by these dielectric layers, and is focused on the aperture side. This makes it possible to focus a part of the electron beam heading for the aperture, which has collided with the shadow mask, on the aperture side and allow it to pass through the aperture. Therefore, the amount of electron beams passing through the openings is increased, the density of electron beams reaching the phosphor screen is increased, and the brightness of the screen can be improved.

Since each dielectric layer has an appropriate volume resistivity, it can be charged by an amount corresponding to the change of the electron beam, and the acting force on the electron beam can be adjusted. It is possible to easily control the focused state of the electron beam.

Further, according to the color cathode ray tube of the present invention, appropriate average surface roughness, dielectric constant, and
Further, since the electron beam is focused by the dielectric layer having volume resistivity, it is not necessary to provide electrodes as in the conventional case, and it is not necessary to align these electrodes with each other.

Therefore, it is possible to obtain a color cathode ray tube which can be manufactured easily, can obtain a good focus state over the entire screen, and have improved brightness.

[0023]

DETAILED DESCRIPTION OF THE INVENTION A color cathode ray tube according to an embodiment of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, the color cathode ray tube includes a vacuum envelope 10. This vacuum envelope 10 has a skirt portion 2 on the periphery thereof and a panel 1 having an approximately rectangular outer surface.
And the funnel 4 connected to the skirt portion 2 of the panel 1.
And a cylindrical neck 3 connected to the small diameter portion of the funnel 4.

The phosphor screen 6 is arranged on the inner surface of the panel 1. The deflection yoke 7 is attached to the outer circumference from the neck 3 to the funnel 4, and a horizontal deflection coil,
And a vertical deflection coil.

The in-line type electron gun assembly 9 is arranged inside the neck 3. This electron gun structure 9 includes three electron beams 8 (B, G, R) that are arranged in a line in the horizontal axis X direction and are composed of a center beam 8G passing through the same horizontal plane and a pair of side beams 8B, 8R on both sides thereof. Emit in the tube axis Z direction. An inner shield 11 that shields an external magnetic field is arranged inside the connecting portion between the panel 1 and the funnel 4.

The shadow mask 12 is arranged in the vacuum envelope 10 so as to face the phosphor screen 6 and is attached to a rectangular mask frame 14. As will be described later, the shadow mask 12 includes a mask main surface 20 in which a large number of electron beam passage openings for color selection (hereinafter referred to as openings) are formed, and a pipe axis Z from the periphery of the mask main surface 20. Mask frame 1 extending along the direction
4 and a skirt portion 18 to be described later, which is formed by press molding. The shadow mask 12 is
The elastic support 15 fixed to the mask frame 14 is provided on the inner surface of the skirt portion 2 of the panel 1 so as to project therefrom.
By engaging with 7, the panel 1 is detachably supported.

The vacuum envelope 10 and the shadow mask 12 including the panel 1 have a tube axis Z extending through the center of the panel 1 and the electron gun assembly 9 and a long axis (horizontal axis) extending orthogonal to the tube axis Z. ) X and a short axis (vertical axis) Y extending orthogonally to the tube axis Z and the long axis X.

In the color cathode ray tube having the above-mentioned structure, the three electron beams 8 emitted from the electron gun assembly 9 are emitted.
B, 8G, and 8R are deflected in the horizontal axis X direction and the vertical axis Y direction by the deflection magnetic field generated by the deflection yoke 7.
A color image is displayed by scanning the phosphor screen 6 horizontally and vertically through the electron beam passage holes of the shadow mask 12.

As shown in FIG. 2, the phosphor screen 6
Are a plurality of stripe-shaped black light absorbing layers 40 extending in the minor axis Y direction of the panel 1 and arranged in parallel with a predetermined gap in the major axis X direction, and the gaps between the respective light absorbing layers 40. And stripe-shaped three-color phosphor layers 42B, 42G, and 42R extending in the short axis Y direction.

As shown in FIGS. 1 and 3A and 3B, the shadow mask 12 is formed by press molding, and has a substantially rectangular mask main surface 20 formed into a smooth dome shape. A skirt portion 18 extending from the peripheral edge 21 of the mask main surface 20 along the tube axis Z direction substantially perpendicular to the mask main surface 20 is integrally provided over the entire circumference of the mask main surface 20. . The mask main surface 20 has a large number of aperture rows 1
9 has a substantially rectangular perforated portion 20a formed at a predetermined arrangement pitch, and a rectangular frame-shaped non-perforated portion 20b surrounding the perforated portion 20a.

A plurality of aperture rows 1 provided in the perforated portion 20a
9 extend substantially parallel to the minor axis Y and are arranged in parallel in the major axis X direction at a predetermined arrangement pitch. Further, each opening row 19 is configured by arranging a plurality of openings 34 in a row via the bridge 32.

Each of the openings 34 is formed in an elongated rectangular shape so that its width direction is parallel to the major axis X direction of the shadow mask 12 and its longitudinal direction is parallel to the minor axis Y direction of the shadow mask 12. Is formed. Further, each opening 34 is constituted by a communication hole formed by connecting a large hole opened on the surface of the shadow mask 12 on the phosphor screen side and a small hole opened on the surface of the electron gun structure side to each other. There is.

Further, the holes 34 of one hole array 19 are
The holes are arranged in a so-called staggered pattern, being displaced by 1/2 pitch in the short axis Y direction with respect to the openings 34 of another adjacent opening row 19. In addition, the array pitch of the aperture rows 19 is the perforated portion 2
0a and the peripheral portion in the major axis X direction are set to different values, and in particular, gradually increase from the central portion of the perforated portion 20a toward the peripheral portion in the major axis X direction.

In this embodiment, the shadow mask 12 is made of amber (Fe-36% N) having a plate thickness of 0.22 mm.
i alloy). The aperture pitch in the minor axis Y direction in each aperture row 19 is 0.6 mm, and the array pitch along the major axis X direction of the aperture row 19 is 0.75 mm near the minor axis Y, and the major axis The variable pitch was 0.82 mm in the peripheral portion in the X direction, and increased as the distance from the central portion of the mask to the peripheral portion in the long axis X direction increased. The size of the large holes forming the openings 34 in the width direction is 0.46 mm for the openings 34 on the short axis Y, and the openings 34 at the peripheral portion in the long axis X direction.
Is 0.50 mm, and the aperture size in the width direction of the small hole is 0.18 mm for the aperture on the short axis Y and the aperture 3 in the peripheral portion in the long axis X direction.
4 was 0.20 mm. Furthermore, the electron beam has a long axis X
When the light enters the aperture 34 in the peripheral portion in the directional direction at a deflection angle of 46 °, the aperture 34 in the peripheral portion in the major axis X direction has a shape in which the large hole is eccentric by 0.06 mm with respect to the small hole.

On the other hand, according to this embodiment, the shadow mask 12 is provided with a plurality of striped dielectric layers 50 provided on the surface of the perforated portion 20a on the electron gun assembly side. The dielectric layer 50 has an average surface roughness of 0.2 μm.
m or less (preferably 0.15 μm or less), and
Its dielectric constant is 3 or more (preferably 5 or more), and its volume resistivity is 1.0E + 12 or more and 1.0E + 1.
5Ω · cm or less (preferably 5.0E + 12 or more and 7.5
E + 14 Ω · cm or less).

The average surface roughness was measured with a surface roughness meter SE-30H manufactured by Kosaka Seisakusho Co., Ltd. to find that the cutoff was 0.08 m.
It was measured under the condition of m. Further, the dielectric constant and the volume resistivity were measured based on JIS C2141 "Ceramic material test method for electrical insulation".

More specifically, as shown in FIGS. 4 to 6, on the surface of the perforated portion 20a on the side of the electron gun assembly, between the adjacent aperture rows 19, that is, on both sides of each aperture row 19. Each has a striped dielectric layer 50 formed thereon,
It extends along a direction substantially parallel to the minor axis Y of the shadow mask 12.

Each dielectric layer 50 has a substantially semicircular cross-sectional shape, and for example, has a width along the major axis X direction of about 0.25.
mm, and the height is about 0.03 to 0.05 mm. The cross-sectional shape of the dielectric layer 50 is not limited to a semicircle, but may be another shape such as a rectangle.

Each dielectric layer 50 is formed by sintering an insulator containing glass as a main component. A preferred material is a lithium-based alkali borosilicate glass powder, which is screen-printed with a glass paste obtained by kneading the glass powder with a cellulose-based binder and a solvent.
The dielectric layer 50 is formed by drying and sintering.

If the surface roughness, the dielectric constant, and the volume resistivity are appropriate, it is possible to use bismuth-based borosilicate glass, lead glass glass, etc. in addition to the lithium-based alkali borosilicate glass powder. . These glasses may contain an adjusting agent such as a pigment for adjusting the surface roughness, the dielectric constant, and the volume resistivity.

The disposition positions of the dielectric layer 50 with respect to the aperture array 19 are different between the central portion of the perforated portion 20a and the peripheral portion of the perforated portion 20a in the long axis X direction.

That is, as shown in FIG. 6A, in the central portion of the perforated portion 20a, each dielectric layer 50 is arranged substantially in the center between two adjacent rows of apertures 19. At the central portion of the perforated portion 20 a, the electron beam 8 is incident on the surface of the shadow mask 12 substantially perpendicularly, so that the dielectric layers 50 located on both sides of each of the apertures 34 are formed in the aperture 34. On the other hand, it is desirable that they are provided symmetrically.

Further, as shown in FIG. 6B, the dielectric layer 50 provided on the peripheral portion of the perforated portion 20a in the long axis X direction.
Are arranged closer to the center of the aperture array 20 than to the dielectric layer 50 provided at the center of the perforated portion 20a. That is, the two adjacent
The dielectric layer 50 provided between the two aperture rows 19 is arranged close to the aperture row on the central side of the mask.

According to the color cathode ray tube constructed as described above, as shown in FIG. 7, at the beginning of the operation, a part of the electron beam 8 emitted from the electron gun assembly collides with the dielectric layer 50, Each dielectric layer 50 is negatively charged. And
By charging the dielectric layer 50, the potential of the dielectric layer 50 becomes a voltage lower than Eb described above. As a result, a potential difference occurs between the shadow mask 12 and the dielectric layer 50. Then, this potential difference, the dielectric layer 50, and the rectangular opening 34 of the shadow mask 12 form a quadrupole lens as an electron lens.

As shown in FIGS. 4 and 7, this quadrupole lens has an aperture 3 through between two adjacent dielectric layers 50.
4 has a function of converging the electron beam 8 directed to the No. 4 in a vertically elongated shape in which the width direction of the opening 34 is smaller than the actual opening diameter and the longitudinal direction of the opening 34 is longer than the actual opening diameter. .

By thus focusing the electron beam 8 in a vertically elongated shape, a part of the electron beam hitting the shadow mask 12 in the past can be passed through the opening 34 and guided to the phosphor screen 6. Become. Then, in the longitudinal direction of the opening 34, that is, in the short axis Y direction of the shadow mask 12, the phosphor layer portion that was shadowed by the bridge 32 of the conventional shadow mask 12 is caused to emit light, and in the long axis X direction. The density of the electron beam spot can be increased. This makes it possible to improve the emission brightness of the phosphor layer.

In addition, by providing the dielectric layer 50 near the aperture row side on the central side of the shadow mask, the same effect as described above is obtained in the peripheral portion of the shadow mask perforated portion 20a in the direction of the long axis X. It becomes possible. As a result, good focus characteristics can be obtained in the entire screen area.

That is, the electron beam 8 is obliquely incident on the surface of the shadow mask in the peripheral portion of the perforated portion 20a in the long axis X direction. Therefore, as shown by the chain double-dashed line in FIG. 6B, if the dielectric layers 50 provided on both sides of the opening 34 are located symmetrically with respect to the opening 34,
The electron beam 8 is applied to the dielectric layer 5 on the central side of the shadow mask.
It passes near 0 and is greatly affected by the dielectric layer 50 on the central side of the shadow mask. Therefore, as shown by the chain double-dashed line, the amount of deflection of the electron beam 8 toward the peripheral side of the shadow mask perforated portion 20a increases, and it becomes difficult to reach a predetermined position on the phosphor screen.

Therefore, as in the above-described embodiment, the dielectric layer 50 is formed in the peripheral portion of the perforated portion 20a in the long axis X direction.
The electron beam 8 can be focused on a desired phosphor layer by arranging the electron beam 8 close to the aperture array 19 on the central side of the shadow mask.

Such an effect is obtained by the dielectric layer 50 with respect to the aperture array 19 in the central portion and the peripheral portion of the shadow mask perforated portion.
Can be obtained by changing the disposition position of the shadow mask, but by adjusting the width, height, or dielectric constant of the dielectric layer 50 at the center and the peripheral portion of the shadow mask hole portion 20a,
The same effect as described above can be obtained. Then, as described above, the focusing characteristics of the electron beam can be controlled by adjusting only the dielectric layer 50, and good focus characteristics can be obtained in the entire screen.

In the experiment conducted by the inventors of the present invention, when the color cathode ray tube was operated under the above-mentioned conditions, the brightness could be improved by about 20% as compared with the conventional case. Also,
According to this embodiment, by providing the dielectric layer 50 having a height of several tens of μm with respect to the plate thickness of the shadow mask 12, that is, as shown in FIG. 5, the dielectric layer 50 has a maximum film thickness of 10 μm or more. By forming to have the thick portion 50H,
A sufficient effect can be obtained. When the film thickness of the dielectric layer 50 is less than 10 μm, the dielectric layer 50 is charged by irradiation with an electron beam, but an electron lens having sufficient lens strength to act on the electron beam cannot be formed. . Therefore, it is not necessary to increase the plate thickness of the shadow mask 12, and there is no fear of vignetting as described above. The lower limit of the thickness of the dielectric layer must be determined in consideration of the dielectric constant of the dielectric material, the volume resistivity, and the workability of forming the dielectric layer. The higher the dielectric constant or the higher the volume resistivity, the same effect can be obtained even if the thickness of the dielectric layer is reduced.

By the way, the dielectric layer 50 has three or more,
More preferably, it is formed to have a dielectric constant of 5 or more. If the permittivity is less than 3, the particles are charged by irradiation with an electron beam, but an electron lens having a sufficient lens strength that acts on the electron beam cannot be formed.

The dielectric layer 50 is formed so as to have an average surface roughness of 0.2 μm or less, more preferably 0.15 μm or less. FIG. 11 is a diagram showing the relationship between the average surface roughness and the relative brightness on the screen. Here, the relative brightness is a relative value with respect to the brightness when the dielectric layer is not provided. As shown in FIG. 11, it can be seen that the relative luminance can be dramatically improved by setting the average surface roughness of the dielectric layer 50 to 0.2 μm or less.

The dielectric layer 50 is 1.0E + 1.
5Ω · cm or less, more preferably 7.5E + 14Ω · c
It is formed to have a volume resistivity of m or less. FIG. 12 is a diagram showing the relationship between the volume resistivity and the afterimage time of the image displayed on the screen. As shown in FIG. 12, when the volume resistivity of the dielectric layer 50 exceeds 1.0E + 15 Ω · cm, the electric charge charged in the dielectric layer 50 travels through the shadow mask 12 and becomes difficult to be removed, and Body layer 50
It takes a long time to charge and discharge, and the afterimage time becomes dramatically long. Further, when the irradiation amount of the electron beam is changed, the landing position of the beam on the phosphor is likely to change, which may cause deterioration in color purity. On the other hand, the volume resistivity of the dielectric layer 50 is 1.0
By setting E + 15 Ω · cm or less, the afterimage time can be suppressed to 0.8 seconds or less.

The dielectric layer 50 is 1.0E + 1.
2Ω · cm or more, more preferably 5.0E + 12Ω · c
It is formed to have a volume resistivity of m or more. FIG. 13 is a diagram showing the relationship between the volume resistivity and the relative brightness on the screen. As shown in FIG. 13, when the volume resistivity of the dielectric layer 50 is less than 1.0E + 12 Ω · cm, the dielectric layer 50 is charged by the electron beam irradiation, but the charged electrons are easily removed. Therefore, the lens strength of the electronic lens cannot be sufficiently achieved. Therefore, the effect of focusing the electron beam cannot be sufficiently obtained, and the brightness cannot be sufficiently improved. On the other hand, the dielectric layer 5
It can be seen that by setting the volume resistivity of 0 to 1.0E + 12 Ω · cm or more, it becomes possible to form an electron lens having sufficient lens strength, and the relative luminance on the screen can be dramatically improved.

Next, a method of manufacturing the shadow mask in the method of manufacturing the color cathode ray tube having the above structure will be described.

First, as shown in FIG. 8, a rectangular plate-shaped mask substrate (flat mask) 52 is prepared, and a large number of openings 34 are formed in a region to be the perforated portion 20a by etching as in the conventional case. Form. Subsequently, stripe-shaped insulating material layers are formed on both sides of each aperture array 19 on the surface of the mask base 52 on the electron gun assembly side.

In this embodiment, a glass paste obtained by kneading a lithium-based alkali borosilicate glass powder with a cellulosic binder and a solvent such as carbite acetate is applied to the mask substrate 52 by a screen printing method. After printing a predetermined pattern on the surface, about 10
Dry at a temperature of 0 to 150 ° C. At this stage, the stripe-shaped insulating material layer is composed of a glass component and a binder component, and it is necessary to select a component that does not cause deformation, peeling or cracking of the shape during the subsequent pressing. Also, the amber material is pressed by 150 to 300.
Since it is carried out at a temperature of 0 ° C., the binder must have the above-mentioned characteristics at these temperatures and must not decompose. As such a binder, an acrylic resin can be used in addition to the cellulose resin.

Subsequently, the mask base material 52 on which the insulating material layer is formed is mounted on a press die and press-molded at a temperature of 150 to 300.degree. As a result, the shadow mask 1 having the mask main surface 20 and the skirt portion 18 having a desired shape is formed.
Form 2. During this press molding, generally, heat-resistant oil such as silicon is applied as a lubricant for prolonging the life of the mold, but these lubricants permeate into the dried insulating material layer, and Inhibits sintering. For this reason, thermal decomposition is performed without applying a lubricant, or as shown in FIG. 9, at a lower temperature than the binder in the insulating material layer on the entire surface of the perforated portion 20a of the mask substrate 52 or only on the insulating material layer 53. It is desirable to apply the overcoat layer 54 made of resin and press-mold it. As the overcoat material, a cellulose resin, an acrylic resin, or the like can be used.

Subsequently, the binder in the insulating material layer is burned off and the binder removal treatment of thermally decomposing the overcoat layer is performed, and then the entire shadow mask 12 is subjected to about 50.
By firing at about 0 to 650 ° C., the insulating material layer is sintered to form the dielectric layer 50, and the shadow mask surface is blackened.

Through the above steps, the shadow mask 12 having a predetermined shape having the striped dielectric layer 50 on the surface on the electron gun assembly side is obtained.

According to such a manufacturing method, since the stripe-shaped insulating material layers are formed before the mask substrate 52 is formed into a curved surface, these insulating material layers can be accurately formed at predetermined positions. it can. Further, there is no positional deviation of the insulating material layer during press molding, and no positional deviation occurs after molding. Therefore, the finally formed dielectric layer 50
The position accuracy of can be sufficiently increased. Furthermore, by using screen printing, it is possible to easily control the formation position, width, height, etc. of the dielectric layer 50.

The present invention is not limited to the above-described embodiments, but can be variously modified within the scope of the present invention. For example, in the above-described embodiment, one dielectric layer 50 is provided on each side of each aperture row, but as shown in FIG. 10, a plurality of dielectric layers 50 may be provided on each side of each aperture row.
A configuration may be adopted in which two dielectric layers 50 are arranged.

With such a structure, it is possible to shorten the time for charging and discharging the dielectric layer 50. That is, the electrons charged in the dielectric layer 50 must be immediately discharged after the end of the operation of the color cathode ray tube in order to shorten the afterimage time. Then, in order to increase the speed of charge removal, it is necessary to immediately move the electrons to the shadow mask after the end of the electron beam collision and reduce the number of electrons on the dielectric layer 50. If the time required for static elimination is extremely long,
An unwanted afterimage is generated on the screen, which is not preferable.

Therefore, when a plurality of dielectric layers 50 are provided on both sides of the row of holes as described above, the width of each dielectric layer 50 is larger than that when only one dielectric layer 50 is provided. Even if the height is reduced, the same focusing action can be obtained.
Then, by reducing the width, height, etc. of each dielectric layer 50, the distance that electrons charged on the surface of the dielectric layer 50 travel on the surface and reach the shadow mask is reduced. It is possible to shorten the static elimination time.
Therefore, it is possible to reduce the generation of unnecessary afterimages.

The openings formed in the shadow mask may be circular instead of rectangular, and the phosphor layer on the phosphor screen side may be dot-shaped instead of stripe-shaped. Further, the dielectric layer 50 is formed in each opening 3
It suffices that it is provided on both sides of 4 and arranged so as to form a quadrupole lens, and the pattern is not limited to the stripe shape, and may be patterned into a desired shape such as an island shape or a dot shape. Similarly, the dimensions of each part shown in the above embodiment,
The shape is an example, and can be variously modified as necessary.

Further, in the present invention, the shadow mask, which is the color selection mechanism, is not limited to the press-molding mask, but may be a tension-type mask for applying tension.

[0069]

As described above, according to the present invention, it is possible to improve the focus characteristics of the electron beam over the entire screen and to improve the brightness over the entire screen. A tube can be provided.

[Brief description of drawings]

FIG. 1 is a horizontal sectional view schematically showing the structure of a color cathode ray tube according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view showing a part of a phosphor screen in the color cathode ray tube shown in FIG.

3 (a) is a perspective view schematically showing the structure of a shadow mask in the color cathode ray tube shown in FIG. 1, and FIG. 3 (b) is an enlarged view of a part of the shadow mask. FIG.

FIG. 4 is a shadow mask, a phosphor screen,
It is a figure which shows typically the relationship of an electron beam.

FIG. 5 is a perspective view schematically showing a structure of a surface of an electron gun assembly side of a shadow mask on which a dielectric layer is formed.

6 (a) is a diagram showing a cross-sectional structure in the central portion of the perforated portion of the shadow mask, and FIG.
FIG. 6 is a diagram showing a cross-sectional structure in a peripheral portion in the long axis direction of a shadow mask effective portion.

FIG. 7 is a diagram schematically showing a focused state of an electron beam passing through a central portion of a perforated portion of a shadow mask.

FIG. 8 is a plan view showing a mask base material used for manufacturing a shadow mask.

FIG. 9 is a view showing a shadow mask manufacturing process,
FIG. 5 is a cross-sectional view showing a state in which an overcoat layer is formed on the surface of the mask base material on the electron gun assembly side.

FIG. 10 is an enlarged sectional view showing a part of a shadow mask applicable to a color cathode ray tube according to a modification of the present invention.

FIG. 11 is a diagram showing the relationship of the relative intensity on the screen to the average surface roughness of the dielectric layer.

FIG. 12 is a diagram showing a relationship between a volume resistivity of a dielectric layer and an afterimage time of a display image on a screen.

FIG. 13 is a diagram showing a relationship between relative volume on the screen and volume resistivity of a dielectric layer.

[Explanation of symbols]

1 ... panel 3 ... neck 4 ... Funnel 6 ... Phosphor screen 9 ... Electron gun 10 ... Vacuum envelope 12 ... Shadow mask 18 ... skirt 19 ... Opening row 20 ... Mask main surface 20a ... perforated part 32 ... Bridge 34 ... Electron beam passage opening 42R, 42G, 42B ... Phosphor layer 50 ... Dielectric layer 52 ... Mask base material 53 ... Insulating material layer 54 ... Overcoat layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hitoshi Shiozawa             2 shares, 1-9-1 Harara-cho, Fukaya City, Saitama Prefecture             Company Toshiba Fukaya Factory (72) Inventor Akiyoshi Nakamura             2 shares, 1-9-1 Harara-cho, Fukaya City, Saitama Prefecture             Company Toshiba Fukaya Factory F-term (reference) 5C031 EE06

Claims (14)

[Claims] 1. An envelope having a panel having a phosphor screen arranged on an inner surface thereof, and an electron gun assembly arranged in the envelope and emitting an electron beam toward the phosphor screen. A shadow mask which is arranged so as to face the phosphor screen and has a large number of apertures for selecting an electron beam emitted from the electron gun assembly; and the electron gun assembly side of the shadow mask. On the surface of, the patterned dielectric layer that is located on both sides of the opening and forms an electron lens that is charged by the irradiation of an electron beam and acts on the electron beam is provided, and the dielectric layer is The average surface roughness is 0.2 μm or less, the dielectric constant is 3 or more, and the volume resistivity is 1.0E + 12 or more and 1.0E + 15Ω · c.
A color cathode ray tube characterized by being m or less. 2. The shadow mask has a plurality of aperture rows arranged substantially in parallel, and the dielectric layer is formed in a stripe shape extending substantially parallel to the aperture rows. The color cathode ray tube according to claim 1. 3. The color cathode ray tube according to claim 1, wherein the dielectric layer has a maximum film thickness portion of 10 μm or more. 4. The shadow mask is provided with a substantially rectangular mask perforated portion, in which the apertures are formed and which has a long axis and a short axis which are orthogonal to each other and which pass through a tube axis. Is formed by arranging a plurality of substantially rectangular openings whose width direction is the major axis direction of the perforated mask portion along the minor axis direction of the perforated mask portion.
The color cathode ray tube described in. 5. The color cathode ray tube according to claim 4, wherein the phosphor screen is provided with a plurality of stripe-shaped phosphor layers extending substantially parallel to the minor axis of the shadow mask. 6. The color cathode ray tube according to claim 2, wherein a plurality of the striped dielectric layers are provided on both sides of each aperture row. 7. A disposition position of the dielectric layer with respect to the array of holes is different between a central portion of the perforated mask portion and a peripheral portion of the mask effective portion in the long axis direction. The color cathode ray tube according to claim 2. 8. The dielectric layer provided on the peripheral portion in the major axis direction of the mask perforated portion is closer to the aperture row than the dielectric layer provided on the central portion of the mask perforated portion. The color cathode ray tube according to claim 7, wherein the color cathode ray tube is arranged so as to be closer to the center. 9. The dielectric layer provided in the central portion of the perforated mask portion and the dielectric layer provided in the peripheral portion in the major axis direction of the perforated mask portion have different widths. The color cathode ray tube according to claim 1, wherein 10. The color cathode ray tube according to claim 1, wherein the dielectric layer is formed of an insulating material containing glass as a main component. 11. The dielectric layer according to claim 10, wherein at least one of lithium-based alkali borosilicate glass, bismuth-based borosilicate glass, and lead glass is formed as a main component. Color cathode ray tube. 12. The surface roughness of the dielectric layer is 0.15 μm.
The color cathode ray tube according to claim 1, wherein the color cathode ray tube has a thickness of m or less. 13. The color cathode ray tube according to claim 1, wherein the dielectric constant of the dielectric layer is 5 or more. 14. The volume resistivity of the dielectric layer is 5.0E.
The color cathode ray tube according to claim 1, wherein the color cathode ray tube is +12 or more and 7.5E + 14 Ω · cm or less.