JP2003045355A - Color cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color cathode ray tube having light image at the whole part of an image surface by preventing the lowering of lightness at the peripheral part of a panel. SOLUTION: The width of a black matrix Sbmn of a black matrix BM is made to scatter as shown in the equation: Sbmn=Sbm0×(τp0/τpc)=Sbm0×((1-R)<2> ×e<-> KT<c> /(1-R)<2> ×e<-> KT<0> ), where, Sbm0 is the width of a black matrix BM in the direction of long axis at the center of a panel, Sbmn is the width of the black matrix BM in the direction of long axis at the peripheral part of the panel, τp0 is the transmission coefficient at the center of the panel, T0 is the wall thickness of the panel at the central part, τpc is the transmission coefficient at the peripheral part of the panel, Tc is the wall thickness of the panel at the peripheral part, R is the reflection coefficient of the panel, k is the light absorption coefficient of the panel.

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, and more particularly to a difference in light transmittance between the central portion and the peripheral portion of the panel having a flat face without changing the thickness of the central portion and the peripheral portion. The present invention relates to a color cathode ray tube with reduced power consumption.

[0002]

2. Description of the Related Art The color cathode ray tube widely used as a display device for information terminals and television receivers tends to have a large screen size. The face plate of the color cathode ray tube that has been conventionally used is a so-called round face type in which the surface of the panel portion forming the screen is curved, but in recent years, the so-called flat face in which the panel portion forming the screen is flattened. Molds have become popular. The color cathode ray tube currently in widespread use has a color selection electrode such as a shadow mask installed close to the inner surface of a panel on which phosphor pixels of three colors are formed, and three electron beams emitted from an electron gun. Is configured to be individually projected to each phosphor pixel by the color selection electrode to reproduce an image.

FIG. 8 is a side view showing a comparison of the shapes of the panel portions of the flat face type color cathode ray tube and the round type color cathode ray tube. In the figure, 6A shows the shape of the panel portion of the flat face type color cathode ray tube, and 6B shows the shape of the panel portion of the round face type color cathode ray tube. Further, reference numeral 7 is a funnel, reference numeral 8 is a neck, reference numeral 10 is an electron gun housed in the neck, reference numeral 11 is a deflection yoke mounted on a transition region between the funnel and the neck, and 14
Is a reinforced band. The hatched portion in the figure is the exterior conductive film.

As the above-mentioned color selection electrode, a thin plate member having a large number of holes (electron beam passage holes) such as round holes (dot holes) or elongated holes (slots) formed in accordance with the curvature of the inner surface of the panel portion. A so-called press mask that is press-formed into a curved shape, a tension mask in which a thin plate member having a large number of holes is stretched on a frame-shaped member (frame), or a large number of thin strips arranged in a blind shape are formed into a frame. What is called an aperture grill which is stretched across opposite sides of a strip-shaped member is used. The above-mentioned press mask and tension mask are also called a shadow mask.

In this type of color cathode ray tube, a panel having a fluorescent surface coated on its inner surface, a neck accommodating an electron gun, and a funnel-shaped funnel connecting the panel and the neck are integrated to form a vacuum envelope. is doing. As for the structure of the perforated region in which the electron beam passage hole of the shadow mask is arranged, for example, JP-A-9-82234 can be cited.

[0006]

Generally, a flat face type color cathode ray tube panel has flat inner and outer surfaces, and a conventional round face type panel for ensuring mechanical strength such as implosion resistance. The thickness of the glass is thicker than the panel portion of the color cathode ray tube. The above-mentioned tension mask is generally used as a shadow mask installed in such a flat face type cathode ray tube.

In addition to this, as a panel of a flat face type color cathode ray tube, the outer surface (outer surface) is made closer to flat, and the inner surface (inner surface) is thicker in the peripheral portion than in the central portion. There is one that is curved so as to have a concave shape on the outer surface side so as to be meat. As a shadow mask installed in such a flat face type cathode ray tube,
Many press masks are press-molded into a shape that substantially follows the curvature of the inner surface of the panel.

The panel forming the vacuum envelope of the color cathode ray tube uses a clear panel having a high panel transmittance and a surface treatment film on the inner and outer surfaces of the panel in order to realize a high brightness and high contrast image display. It is generally dealt with by applying it or forming a film having a low transmittance. However, the surface treatment and the formation of the surface treatment film of such a panel require a process therefor, and the manufacturing cost is high. Further, there is a problem in the fading property (change in density and change in color tone) of the surface-treated film. Therefore, tint panels, which have a lower light transmittance than a clear panel, a semi-clear panel, or a gray panel and can achieve high contrast without surface treatment of the panel, are often used for color cathode ray tubes. However, the color cathode ray tube using this tint panel has lower brightness than that using a clear panel, a semi-clear panel or a gray panel.

On the other hand, in the case of a panel in which the radius of curvature is extremely larger on the outer surface than on the inner surface and the outer surface is close to a flat surface, the thickness of the panel is considerably thicker in the peripheral portion than in the central portion, and the light transmittance of the peripheral portion ( The permeation amount) is much lower than that of the central part. When a tint panel having a low light transmittance as a whole is applied to a panel close to the flat panel, the light transmittance of the peripheral portion is particularly noticeable, and the uniformity of luminance in the entire screen of the cathode ray tube is impaired. Therefore, if the light emission amount of the phosphor is the same in the entire panel, that is, if the electron beam passage amount of the color selection electrode is the same in the entire area, the brightness of the peripheral portion is lowered. This difference in light transmittance can be corrected by changing the electron beam transmission amount of the color selection electrode.

Further, in a flat face type color cathode ray tube using a panel whose inner and outer surfaces are close to flat, especially when the screen size is large, the color selection electrode is deformed by thermal expansion at the time of electron beam bombardment. Difficult tension masks and aperture grills are suitable. However, tension masks and aperture grills require proper tensioning work that considers material strength and the amount of relaxation due to temperature changes when the color selection electrode is stretched over the frame,
Moreover, since a mechanically strong structure is required as the frame, the manufacturing cost is high.

On the other hand, since the press mask is manufactured by press-molding in a shape substantially following the curve of the inner surface of the panel, it is easy to manufacture itself. On the other hand, however, the curvature of the central portion of the inner surface of the panel is large, for example, the larger the diagonal length of the effective screen area is 76 cm or more, the less the curvature of the central portion is (the radius of curvature is large. become). When applied to a color cathode-ray tube having a panel whose outer surface of this press mask is close to flat, in order to improve the uniformity of brightness in the entire screen of the color cathode-ray tube, the center and peripheral parts of the panel should be as much as possible. It is necessary to reduce the difference in wall thickness.

That is, it is necessary to reduce the degree of curvature of the panel inner surface and the press mask as much as possible, and set the radius of curvature of the panel inner surface and the press mask to a predetermined value or more. In general, in a press mask composed of a thin plate of iron-based material, the greater the degree of bending, the greater the shape-retaining capacity, and conversely, the smaller the degree of bending, the lower the mechanical strength and the smaller the shape-retaining capacity. Become.

In particular, when a press mask is used for a flat face type color cathode ray tube having an ultra-large screen size as described above, the strength of the press mask at the central portion having a large radius of curvature becomes small and the mechanical strength (curved surface shape) (Holding capacity) tends to decrease, and shape deformation occurs due to external impact during the manufacturing process or transportation, or due to heating during operation, resulting in a large decrease in color reproducibility, resulting in deterioration of image quality. There is a fear.

The curvature of this kind of press mask is small in the central part and large in the peripheral part, and is bent in a direction parallel to the tube axis of the color cathode ray tube at the outermost peripheral part and fixed to the frame member. . The range of the central portion exists in a width of about 1/3 to 2/3 of the center of the perforated region, which is a region including a portion having the largest radius of curvature of the press mask, in the longitudinal direction. for that reason,
The peripheral part can acquire the mechanical strength necessary for shape retention,
It is difficult to obtain sufficient strength in the central part. For this reason, when a press mask is used for a flat face type color cathode ray tube, it has been a problem to ensure the mechanical strength of the central portion of the press mask. Hereinafter, this press mask will be described simply as a shadow mask.

FIG. 9 is a schematic diagram for explaining the difference in wall thickness in the peripheral portion of the panel of the color cathode ray tube in the peripheral portion along the diagonal axis.
9A is a quarter of the panel 6, and FIG. 9B is a sectional view taken along line AA of the portion (a). In the figure, reference numeral 6A indicates a flat face panel, reference numeral 6B indicates a cross section of the round face panel, and the outer surface of the round face panel is indicated by a broken line. The thickness of the central part of the panel is T0 And the wall thickness at the corner of the round face panel is Tc ', The thickness of the corner of the flat face panel is Tc And Here, the thickness of the corner portion on the diagonal axis C will be described as a representative of the thickness of the peripheral portion of the panel.

The major axis (usually in the horizontal direction) of panel 6 (6A, 6B) is X, and the minor axis (usually in the vertical direction) is Y.
The tube axis direction is indicated by Z. The thickness of the corner portion B on the diagonal axis C as the peripheral portion of the panel 6 in FIG.
As shown in FIG. 9 (b), the thickness of the central part of the panel is T0. In this case, the round face panel 6B is thin and the flat face panel 6A is thick. The thickness of the central part of panel 6 is T0 And the wall thickness T0 at the center of the round face panel 6B Peripheral wall thickness T against
c 'Is Tc '/ T0 = About 1.2. In contrast,
Thickness T0 at the center of the flat face panel 6A Peripheral wall thickness Tc Is Tc / T0 = 1.7, the peripheral portion is considerably thicker than the round face panel 6B.

For example, in the case of a nominal 29-inch panel, the wall thickness T0 at the center is And peripheral wall thickness Tc Is about 10 mm to 20
mm. For this reason, the light transmittance of the peripheral portion drops by about 40% at the maximum with respect to the central portion of the panel, which is flat face compared to the round-face type luminance characteristic (ratio of peripheral luminance to central luminance, that is, brightness grading). The mold brightness grading is degraded.

FIG. 10 is an explanatory view of the brightness grading of the panel of the color cathode ray tube, FIG. 10A shows a flat face panel and b shows a round face panel grading. As shown in the figure, in the corner portion 300 mm away from the center of the panel on the diagonal axis C, the light transmittance of the flat face panel is about 40% lower than that of the round face panel. This characteristic is further deteriorated by using a tint or dark tint for the panel material (clear ← semi-clear ← gray ← tint ← dark tint, the light transmittance is high in the order of the direction of the arrow) in order to improve the contrast.

11A and 11B are explanatory views of a fluorescent screen formed on the inner surface of the panel of a conventional color cathode ray tube. FIG. 11A shows four halves of the panel 6, and FIG. 11B shows the central portion O of the panel of FIG. 3A is a configuration diagram of a phosphor screen in FIG. 3A, and FIG. 3C is a configuration diagram of the phosphor screen at point B in the panel peripheral portion of FIG. The phosphor screen has stripe-shaped three-color phosphors R, G, B and each phosphor R, G, B
It is composed of a black matrix BM interposed between. The panel 6 may be either a flat face type or a round face type.

Here, when the widths of the phosphors R, G, B in the central part O of the panel are Sbm0 and the widths of the phosphors R, G, B at the point B in the peripheral part of the panel are S'bmn,
S′bmn / Sbm0 ≦ 1, that is, the width of the black matrix BM in the periphery becomes large, and the phosphor R,
The widths S′bmn of G and B are narrowed. This is due to the influence of the earth's magnetism, etc., because it can be seen on the phosphor screen in which the displacement of the relative position of the electron beam and the phosphor has been added in advance, the amount of light emitted from the phosphor in the peripheral area of the panel is less than that in the central area,
The brightness of the peripheral area decreases.

It is an object of the present invention to provide a color cathode ray tube capable of reducing the above-mentioned decrease in brightness in the peripheral portion of the panel and displaying a bright image on the entire screen.

[0022]

The brightness of a cathode ray tube is expressed by the following equation. That is, the brightness of the cathode ray tube is BT, the panel transmittance is τP, and the black matrix transmittance is τb.
mt = τP × τbm × K, where m is the emission rate of the phosphor, and K is the constant determined by the drive voltage, current, raster size, etc. of the cathode ray tube. From this relationship, it is possible to reduce the luminance drop in the peripheral portion of the panel by correcting the amount of the drop in the peripheral portion with respect to the central portion of the panel transmittance τP. For that purpose, the width of the phosphor in the peripheral portion of the panel may be made wider than that in the central portion.

The phosphor is formed by an exposure process through a slot which is an electron beam passage hole of a shadow mask.
Therefore, in order to make the width of the phosphor in the peripheral portion of the panel wider than that in the central portion, the width and the pitch of the slots of the shadow mask are gradually increased toward the peripheral portion of the panel in accordance with the change in the thickness of the panel. Change to. When the slot width and pitch of the shadow mask for forming the black matrix on the phosphor screen are set to the above distribution, the obtained black matrix is as follows.

The major axis width of the black matrix in the central part of the panel is Sbm0, and the major axis width of the black matrix in the peripheral part of the panel is Sbmn,
The transmittance in the central part of the panel is τp0, the central thickness of the panel is T0, the transmittance in the peripheral part of the panel is τpc, the peripheral thickness of the panel is Tc, the reflection coefficient of the panel is R, and the panel is Where the extinction coefficient of is Sbmn = Sbm0 × (τp0 / τpc) = Sbm0 ×
The width Sbmn of the black matrix is distributed such that ((1-R) ² * e- ^KTc / (1-R) ² * e- ^KT0 ). The distribution of such a black matrix is a grading opposite to the grading of the thickness distribution of the panel. By using the black matrix having such an inverse grading distribution, the brightness of the peripheral portion of the panel is improved and the entire screen is bright. Images can be obtained. The typical configuration of the present invention is as follows.

(1) A substantially rectangular outer surface flat shape having a long axis and a short axis, curved so that the equivalent radius of curvature becomes smaller than the outer surface, and forming a fluorescent screen of a plurality of colors divided by a black matrix on the inner surface. Then, a vacuum envelope is constituted by a panel having an inner surface whose peripheral portion is gradually thicker than the central portion, a neck accommodating an electron gun, and a funnel connecting the panel and the neck. Of a perforated region having a plurality of slots formed by having a curved curvature so as to be convex toward the phosphor screen side in the vicinity of the inner surface and having a longitudinal direction in the minor axis direction and connecting the longitudinal direction with a bridge. A color cathode ray tube in which a shadow mask having the same is arranged, wherein the major axis direction pitch of the black matrix is applied from the central portion to the peripheral portion of the panel in response to the change in the thickness of the panel. It was gradually large.

In (2) and (1), the slot width in the long axis direction of the shadow mask is gradually increased from the central portion to the peripheral portion of the panel in accordance with the change in the wall thickness of the panel. .

In (3), (1) or (2), the width in the major axis direction of the black matrix at the central portion of the panel is Sbm0, and the width in the major axis direction at the peripheral portion of the panel of the black matrix is Sbmn. , Τp0 is the transmittance in the central portion of the panel, T0 is the central thickness of the panel, and τpc is the transmittance in the peripheral portion of the panel.
Sbmn = Sbm0 × (τp0 / τpc) = Sbm0 ×, where Tc is the peripheral thickness of the panel, R is the reflection coefficient of the panel, and k is the extinction coefficient of the panel.
It was ^{((1-R) 2 ×} e -KTc / (1-R) 2 × e -KT0).

In any one of (4) and (1) to (3), the equivalent radius of curvature in the diagonal direction of the outer surface of the panel in the effective area of the phosphor screen is Rd (mm), and the diagonal of the phosphor screen is When the effective diameter in the direction is V (inch), Rd ≧
10 (42.5V + 45.0), and the thickness in the tube axis direction of the diagonal end in the effective area of the phosphor screen is T.
c, When the thickness of the central tube in the axial direction is T0, 0.3≤ (Tc-T0) /T0≤1.5.

With the above structure, even in a super-large flat face type color cathode ray tube whose effective display area has a diagonal size of more than 76 cm, the brightness around the panel is improved and the entire screen is bright. Images can be obtained.

The present invention is not limited to a flat face type color cathode ray tube having a large or super large screen size, but a flat face type color cathode ray tube having a relatively small screen size or a round face type color cathode ray tube. The same applies to a pipe. Furthermore, it is needless to say that the present invention is not limited to the above-mentioned constitution and the constitution of the embodiments to be described later, and various modifications can be made without departing from the technical idea of the present invention.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings of the embodiments. FIG. 1 is a schematic diagram of a phosphor screen structure for explaining one embodiment of a color cathode ray tube of the present invention. (A) shows four half of panel 6 (upper right half of panel), (b) shows (a). 3A is a configuration diagram of a phosphor screen in a panel central portion O of FIG. 4C, and FIG. 7C is a configuration diagram of a phosphor screen at a point B in the panel peripheral portion of FIG. The phosphor screen has stripe-shaped three-color phosphors R, G, B and each phosphor R, G, B
It is composed of a black matrix BM interposed between. The panel 6 may be either a flat face type (denoted by reference numeral 6A) or a round face type (denoted by reference numeral 6B).

Here, the width in the major axis direction of the black matrix in the central portion of the panel is Sbm0, and the width in the major axis direction of the peripheral portion of the panel of the black matrix is Sbm0.
bmn, the transmittance in the central portion of the panel is τp0,
When the central thickness of the panel is T0, the transmittance in the peripheral portion of the panel is τpc, the peripheral thickness of the panel is Tc, the reflection coefficient of the panel is R, and the extinction coefficient of the panel is k, Sbmn = Sbm0 × (τp0 / τpc) = Sbm0 ×
((1-R) ² * e- ^KTc / (1-R) ² * e- ^KT0 ).

That is, the inverse grading distribution is set so as to increase the width of the phosphor from the panel central portion to the panel peripheral portion in correspondence with the rate (grading) in which the transmittance from the panel central portion to the panel peripheral portion decreases. Further, the width of the black matrix BM is gradually increased from the central portion to the peripheral portion to secure the contrast in the peripheral portion.

FIG. 2 is a schematic view of a shadow mask structure for explaining one embodiment of the color cathode ray tube of the present invention.
Shows four halves of the shadow mask 1 (corresponding to the upper right half of the panel 6 in FIG. 1), (b) is a block diagram of the slot in the shadow mask central portion O ′ of (a), and (c) is of (a). It is a block diagram of a shadow mask at a point B'in the shadow mask peripheral portion. The central portion O ′ of the shadow mask 1 and the point B ′ of the shadow mask peripheral portion correspond to the phosphors at the panel central portion O and the panel peripheral portion point B of FIG. 1A, respectively.

The slot SL corresponding to the central portion O'of the shadow mask 1 and the slot SL corresponding to the point B'in the peripheral portion.
Are different in size (width in the short axis Y direction). Here, the width of the slot SL shown in FIG. 2B is Sm0 and the long axis (X)
The pitch of the slots SL adjacent in the direction is Phm0, as shown in FIG.
The width of the slot SL in (c) is Smc, and the pitch of the slots SL adjacent in the major axis (X) direction is Phmc.
And

At this time, the ratio of Phmc to Phm0 is equal to the ratio of Smc to Sm0, and Phmc / P
hm0 = Smc / Sm0. The ratio τPn / (τP0-τP) of the transmittance τpn in the peripheral portion of the panel to the transmittance τp0 in the central portion of the panel described above.
n) and Phmc / Phm0 = Smc / Sm0 =
The relationship is set to τPn / (τP0-τPn).

That is, as an inverse grading distribution for increasing the width of the slot SL from the central portion of the shadow mask 1 to the peripheral portion thereof in accordance with the rate (grading) in which the transmittance from the central portion of the panel to the peripheral portion of the panel decreases. is there. Black matrix BM formed on panel 6
Is formed by the exposure light passing through the slot SL of the shadow mask 1. Therefore, by setting the width and pitch of the slots SL provided in the shadow mask to the above relationship, the reverse grading described in FIG. The black matrix BM is formed.

The black matrix is obtained by applying a negative type photosensitive resist mixed with a light absorbing agent on the inner surface of the panel, exposing through the slot SL of the shadow mask 1, and developing to remove the exposed portion. Further, as a phosphor, a step of applying a positive type photosensitive resist mixed with phosphors (usually pigments) of each color on the inner surface of the panel on which the black matrix BM is formed, exposing through the slot SL of the shadow mask 1, and developing By repeating the process for the number of colors, the phosphors of the respective colors are embedded in the openings of the black matrix BM.

According to this embodiment, the black matrix BM
The phosphor screen composed of the phosphors R, G, and B has the inverse grading distribution shown in FIGS. 1B and 1C, and particularly, the flesh in the central portion and the peripheral portion of the flat face type panel. With the same panel as in the case of using the conventional tint glass without changing the thickness distribution, it is possible to improve the luminance of the peripheral portion of the panel and obtain a bright image over the entire screen.

Table 1 shows an example of luminance and brightness distributions in the central portion and the peripheral portion of the panel of the color cathode ray tube of the present embodiment in comparison with the color cathode ray tube for comparison. Table 1 shows that the completed color cathode-ray tube has an anode voltage Eb of 30 kV and an anode current Ib of 1.9 mA (a full-screen white pattern display),
This is a case where the raster size is 540.8 mm × 405.6 mm. In the color cathode ray tube of the comparative product, the pitch Ph0 of the phosphors of the same color in the central portion of the screen in the longitudinal direction is
The constant conditions are 0.75 mm, the width Sbm0 of the holes of the black matrix BM in the central portion is 0.165 mm, and the pitch interval Pv between the beams in the minor axis direction of the screen is 0.65 mm.

[0041]

[Table 1]

As shown in Table 1, in the color cathode ray tube of the present embodiment, the peripheral luminance is improved by 16% as compared with the color cathode ray tube of the comparative product, and the grading of the brightness from the central portion to the peripheral portion is also achieved. It can be seen that it has improved from 54% to 62%.

Next, an example of the structure of the shadow mask used in the color cathode ray tube of this embodiment, the structure of the completed color cathode ray tube and its panel will be described. FIG. 3 is a plan view for explaining the shape of the intermediate member before shaping the shadow mask. In the intermediate member 1'of this shadow mask, that is, the press mask, a large number of slots SL are formed in the perforated region 2 of a thin iron-based metal plate by etching. The bridge width of the central slot SL and the bridge width of the peripheral slot SL are arranged in the distribution described in the above embodiment.

FIG. 4 is an explanatory view of a shadow mask structure in which the intermediate member shown in FIG. 3 is press-formed into a curved shape and fixed to a mask frame. FIG. 4A is a plan view seen from the side facing the fluorescent screen. , (B) is a side view of the short side of (a), (c)
Shows a side view of the long side of (a). The shadow mask 1 is formed by pressing so that its perforated region is curved so as to be convex toward the phosphor screen side, and its peripheral edge is bent in a direction parallel to the tube axis of the color cathode ray tube.

The bent peripheral edge is welded to the inner wall of the mask frame 3 which is a frame-shaped member, and the suspension spring 4 for mounting in the panel of the color cathode ray tube is welded and fixed to the outer wall of the corner portion thereof. The mask frame 3 is appropriately provided with concave grooves 4a and 4b for reinforcing the mechanical strength of the mask frame 3. The mechanical strength reinforcing means is not limited to that shown in FIG. 4, and known reinforcing means can be applied.

FIG. 5 is an explanatory view of a main structure of the press mask assembly structure shown in FIG. 4, and FIG. 5A is a view taken along line X'-X "or Y'-Y" in FIG. 4A. Cross section,
5B is a partial view illustrating a combined structure of a shadow mask and a mask frame at a corner portion along C′-C ″ in FIG. 4. In FIG. It is fitted into the inner wall and welded at the welding points shown by X in the figure.The welding points are present at a plurality of places around the mask frame 3, the number and position of which are the size of the press mask assembly structure and the radius of curvature of the curve. , Is set under other conditions.

The corner portion of the shadow mask structure has a wall surface 3a as shown in FIG. 5 (b).
The suspension spring 4 (see FIG. 4) is welded to a. The shadow mask structure assembled in this manner is installed close to the phosphor screen coated on the inner surface of the panel of the color cathode ray tube. The shadow mask structure is installed on the panel by engaging the suspension spring 4 shown in FIG. 4 with the stud pin that is erected on the inner surface of the side wall of the panel. In the above description, assuming that a relatively large size shadow mask is used, the suspension spring 4 is attached to the corner portion of the mask frame of the shadow mask structure as an example. It is also known that suspension springs are attached at three or four locations near the center in a direction orthogonal to the tube axis.

FIG. 6 is a sectional view for schematically explaining an example of the overall constitution of the color cathode ray tube of the present invention. This color cathode ray tube is a type in which suspension springs of a shadow mask structure are attached at four locations near the central portion of the mask frame in a direction orthogonal to the tube axis. This color cathode ray tube includes a panel 6 having a substantially rectangular display surface and an electron gun 1 for emitting three electron beams B.
It has a neck 8 for accommodating 0 and a vacuum envelope constituted by a funnel 7 having a funnel shape connecting the panel 6 and the neck 8. The outer surface, that is, the display surface of the panel 6 which constitutes this vacuum envelope is a flat surface or a so-called flat face type which has a very large radius of curvature and is slightly curved.

FIG. 7 is a partial sectional view for explaining the detailed shape of the panel in the diagonal direction. When the curved outer surface of the panel has an aspherical shape, its radius of curvature varies depending on an arbitrary position of the outer surface of the panel. Therefore, the curvature of the outer surface of the panel can be defined as the equivalent curvature radius Rd (mm) as follows.

Rd = (Zd ² + Dd ² ) / 2Zd where Dd is the distance (mm) in the direction perpendicular to the tube axis from the center of the panel outer surface to the edge of the fluorescent screen effective area, and Zd is the fluorescent screen effective area edge. Is the amount of depression (mm) in the tube axis direction from the center of the panel outer surface in the section. It should be noted that the same can be defined by replacing the outer surface of the panel with the inner surface of the panel or a shadow mask (press mask). Further, the diagonal direction can be replaced with the major axis direction or the end axis direction, and the same definition can be made.

Depending on the size of the screen of the cathode ray tube,
The flatness is different even if the radius of curvature of the outer surface of the panel is the same. Therefore, as an evaluation of this flatness, the standard outer radius of curvature Ro (m
m) and the inner surface radius of curvature Ri (mm) are defined as follows.

Ro = 42.5V + 45.0 Ri = 40.0V + 40.0 where V is the effective diameter (inch) in the diagonal direction of the screen.
Then, the degree of flatness of the panel can be expressed by a multiple of the standardized outer surface radius of curvature Ro or the inner surface radius of curvature Ri. The "inch" that represents the effective diameter is a term that is commonly used to represent the screen size of a cathode ray tube, and is generally "○○".
It is a notation such as "inch type cathode ray tube". In the present invention, the equivalent radius of curvature of the outer surface of the panel is set to 10 Ro.
By doing so, the screen looks almost flat. At 20Ro, the screen looks almost flat.

Further, in the present invention, since the press mask 1 in which the perforated region is curved in a convex shape is used as the shadow mask, the inner surface of the panel 6 cannot be a flat face type like the outer surface, It is curved with a considerably larger curvature than this outer surface. The inner surface of the panel 6 has a curved surface such that the tube axial thickness Tc at the effective screen corner (diagonal end) of the panel 6 is thicker than the central tube axial thickness T0. It is concave.

In order to reduce the brightness unevenness at the center and the periphery of the screen of the cathode ray tube and to improve the contrast of the image at the same time, the thickness difference Tc-T0 (diagonal direction) between the panel effective screen corner (diagonal end) and the center It is desirable to make the wedge amount Wc) as small as possible. The curved surface of the perforated region of the press mask 1 is preferably formed so as to follow the inner surface of the panel 6 as much as possible in order to easily land the electron beam B on the phosphor screen 13.

In the present invention, the equivalent curvature radius of the shadow mask 1 is 4000 mm or more in the diagonal direction of the perforated area. This is a considerably larger radius of curvature than the press mask of the conventional round face type color cathode ray tube,
This is the direction in which the mechanical strength of the central portion of the press mask decreases. However, by adopting the press mask of the above-described embodiment of the present invention, it is possible to suppress the decrease in mechanical strength. On the inner surface of the panel 6, a phosphor screen 13 having phosphor matrices of three colors and having a black matrix of the reverse grading distribution described in the above embodiment is formed.

The shadow mask structure 30 in which the shadow mask 1 is welded to the mask frame 3 is attached by engaging the suspension spring 4 welded to the mask frame 3 with the stud pin 9 which is set up on the inner surface of the side wall of the panel 6. There is. Further, on the electron gun side of the shadow mask structure 30, a magnetic shield 5 for shielding the electron beam B from an external magnetic field such as geomagnetism is attached.

On the neck 8 side of the funnel 7, the electron gun 1
The three electron beams B emitted from 0 are horizontal (long-axis direction, XX direction, lateral direction) and vertical (short-axis direction, Y-).
A deflection yoke 11 for deflecting in the Y direction and the vertical direction is mounted. An auxiliary magnetic device 12 is mounted on the outer circumference of the neck 8 to correct the color purity and beam concentration deviation (misconvergence) by acting on the intervals and mutual positions of electron beams and the direction of travel.

An image signal is supplied to the electron gun 8 from an external circuit (not shown). The three electron beams are modulated by this image signal, and the modulated electron beam B is emitted in the direction of the fluorescent screen 13 and is deflected by the horizontal magnetic field and the vertical magnetic field generated by the deflection yoke on the way to The two-dimensional image is reproduced.

The above-described color cathode ray tube of the present invention is provided with the shadow mask and the phosphor screen described in the above embodiment, so that the decrease in brightness in the peripheral portion of the panel is reduced and a bright image can be displayed on the entire screen. It is possible to obtain a color cathode ray tube. It is needless to say that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the technical idea of the present invention described in the claims.

[0060]

As described above, according to the present invention,
It is possible to improve the brightness of the peripheral area of the flat face type panel without changing the thickness distribution of the central part and the peripheral part and to obtain a bright image in the entire screen with the same panel as when using conventional tint glass. It is possible to provide a color cathode ray tube capable of performing the above.

[0061]

[Brief description of drawings]

FIG. 1 is a schematic view of a phosphor screen structure for explaining an embodiment of a color cathode ray tube of the present invention.

FIG. 2 is a schematic view of a shadow mask structure for explaining one embodiment of the color cathode ray tube of the present invention.

FIG. 3 is a plan view illustrating the shape of an intermediate member before shaping a shadow mask.

FIG. 4 is an explanatory view of a shadow mask structure in which the intermediate member shown in FIG. 3 is press-formed into a curved shape and fixed to a mask frame.

5 is an explanatory diagram of a main part structure of the press mask assembly structure shown in FIG.

FIG. 6 is a cross-sectional view schematically illustrating an example of the overall configuration of the color cathode ray tube of the present invention.

FIG. 7 is a partial cross-sectional view illustrating a detailed shape of a panel in a diagonal direction.

FIG. 8 is a side view showing a comparison of the shapes of the panel portions of the flat-face type color cathode ray tube and the round type color cathode ray tube.

FIG. 9 is a schematic diagram for explaining the difference in wall thickness of the peripheral portion of the panel of the color cathode ray tube at the peripheral portion along the diagonal axis.

FIG. 10 is an explanatory diagram of brightness grading of a panel of a color cathode ray tube.

FIG. 11 is an explanatory view of a phosphor screen formed on the inner surface of the panel of a conventional color cathode ray tube.

[Explanation of symbols]

1 ... Shadow mask (press mask), 2 ...
・ Perforated area, 3 ... Mask frame, 4 ... Suspension spring, 5 ... Magnetic shield, 6 ... Panel, 7 ... Panel, 8 ... Neck, 9 ...
・ Stud pin, 10 ・ ・ ・ ・ Electron gun, 11 ・ ・ ・ ・ ・ ・ Deflection yoke, 12 ・ ・ ・ ・ Auxiliary magnetic device, 13 ・ ・ ・ ・ Fluorescent screen, 30 ・ ・ ・ ・ Shadow mask structure, SL ・ ・ ・・
Slot, BM ... Black matrix, R, G,
B ... Phosphor.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuzo Ota             Hitachi Device, 3681 Hayano, Mobara-shi, Chiba             Engineering Co., Ltd. F-term (reference) 5C031 EG03 EG08                 5C036 CC14

Claims (4)

[Claims] 1. A flat rectangular outer surface having a major axis and a minor axis, curved so that the equivalent radius of curvature becomes smaller than the outer surface, and forming a fluorescent screen of a plurality of colors partitioned by a black matrix on the inner surface. , A panel having an inner surface whose peripheral portion is gradually thicker than the central portion, and a neck accommodating an electron gun,
A vacuum envelope is configured with the funnel connecting the panel and the neck, and has a curved curvature such that the panel is close to the inner surface of the panel and convex toward the phosphor screen side, and the longitudinal direction in the minor axis direction. A color cathode ray tube in which a shadow mask having a perforated region in which a number of slots are connected by a bridge in the longitudinal direction is arranged, wherein the longitudinal pitch of the black matrix is the wall thickness of the panel. The color cathode ray tube is characterized in that it gradually increases in size from the central portion of the panel to the peripheral portion thereof in response to the change. 2. The slot width of the shadow mask in the long axis direction is gradually increased from the central portion to the peripheral portion of the panel in accordance with the change in the wall thickness of the panel. 1. The color cathode ray tube according to 1. 3. The width of the black matrix in the major axis direction at the central portion of the panel is Sbm0, and the width of the black matrix at the peripheral portion of the panel in the major axis direction is Sbm0.
n, the transmittance in the central part of the panel is τp0, the central thickness of the panel is T0, the transmittance in the peripheral part of the panel is τpc, the peripheral thickness of the panel is Tc, and the reflection coefficient of the panel is R, When the extinction coefficient of the panel is k, Sbmn = Sbm0 × (τp0 / τpc) = Sbm0 ×
The color cathode ray tube according to claim 1, wherein the color cathode ray tube is ((1-R) ² × e ^-KTc / (1-R) ² × e ^-KT0 ). 4. When the diagonal equivalent radius of curvature of the panel outer surface in the effective area of the phosphor screen is Rd (mm) and the effective diameter of the phosphor screen in the diagonal direction is V (inch), Rd ≧ 10 (42.5V + 45.0), where 0.3 is the tube axial thickness of the diagonal end in the effective area of the phosphor screen, and T0 is the central tube axial thickness. 4. The color cathode ray tube according to claim 1, wherein ≤ (Tc-T0) /T0≤1.5.