JP2003229071A - Shadow mask and color cathode-ray tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shadow mask superior in a deformation preventive effect, improving curved surface holding strength, and improving manufacturing stability and operational stability. <P>SOLUTION: This shadow mask 15 has an almost rectangular effective surface 28a bored with a large number of electron beam passing holes 26, and a skirt part 27 bent and formed over the whole outer peripheral part in an outer peripheral part of this effective surface 28a, and having a top part 30 projecting in the tube axis direction orthogonal to the effective surface a center, and has a first bending part 32 for forming the skirt part 27, and a second bending part 31 between this first bending part 32 and the effective surface 28. When a tube axis directional distance between the first bending part 32 and the second bending part 31 is set to a skirt projecting quantity, the skirt projecting quantity is smoothly changed so as to become minimum in both end parts of the respective sides and maximum in a central part on the short side and the long side in the outer peripheral part of the effective surface 28a. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask and a color cathode ray tube, and more particularly to a shadow mask capable of improving manufacturing stability and operation stability, and a color cathode ray tube using the shadow mask.

[0002]

2. Description of the Related Art In general, a color cathode ray tube is a vacuum envelope comprising a substantially rectangular panel having a skirt portion formed around a curved effective surface and a funnel-shaped funnel joined to the skirt portion. And a phosphor screen formed of an inner surface of the effective surface of the panel and facing the phosphor screen made of a black non-luminous substance, from a curved surface having a large number of electron beam passage holes formed therein. A shadow mask structure composed of a substantially rectangular shadow mask and a substantially rectangular mask frame attached to the peripheral portion of the shadow mask is arranged.

On the other hand, an electron gun for emitting three electron beams is arranged in the neck portion of the funnel. Then, the three electron beams emitted from this electron gun are deflected by a magnetic field generated by a deflection device mounted outside the funnel,
It has a structure for displaying a color image by horizontally and vertically scanning the phosphor screen through a shadow mask.

The shadow mask described above is one of the important members having a color selecting function. An example of a conventional shadow mask is shown in FIG. The conventional shadow mask 50 shown in FIG. 8 has a rectangular effective surface 51 having a large number of electron beam passage holes 52 formed therein, and a skirt portion 53 formed on the entire outer periphery of the effective surface 51. This shadow mask 5
0 is arranged inside a curved panel provided with a phosphor screen in which phosphors emitting light of multiple colors are separately coated. The electron beams of three colors from the electron gun arranged at the neck are focused, accelerated, and deflected to scan the area of the rectangular effective surface 51, and the electron beam passage hole 52 is formed.
The corresponding phosphors in the phosphor screen are made to project and emit light by passing through each other to display a color image. Therefore, in order to display an image without color shift on the phosphor screen of the color cathode ray tube, the shadow mask 5
The relative positional relationship between the zero electron beam passage hole 52 and the corresponding phosphor group is important, and this relative relationship must be kept constant during the operation of the color cathode ray tube. More specifically, the distance (q value) between the shadow mask 50 and the phosphor.
Must always be within certain tolerances.

Further, during the operation of the shadow mask type color cathode ray tube, the electrons passing through the electron beam passage holes of the shadow mask 50 and reaching the phosphor screen are 1/3 of all electron beams emitted from the electron gun. The following is the rest, and the rest collides with a portion other than the electron beam passage hole 52 of the shadow mask 50 to generate thermal energy, which heats the shadow mask 50. As a result, the shadow mask 50 causes a doming phenomenon in which the shadow mask 50 bulges toward the phosphor screen side due to thermal expansion.
If the distance between the phosphor screen and the shadow mask 50 exceeds the allowable range due to this doming phenomenon, the beam landing with respect to the phosphor is deviated and the color purity is deteriorated. The magnitude of the deviation of the beam landing due to the thermal expansion of the shadow mask greatly differs depending on the brightness of the image pattern and the duration of the pattern.

[0006] Deterioration of color purity has become more serious due to the increase in deflection angle and the flattening of the screen accompanying the recent enlargement of the screen, and in order to suppress this, in a flatter large tube, Invar material having a low coefficient of thermal expansion is often used for the shadow mask 50. If the shadow mask 50 is made of Invar and the mask frame is made of normal cold-rolled steel plate, and if there is a difference in the coefficient of thermal expansion between the two, it will take sufficient time from the start of operation of the color cathode ray tube that the shadow mask When the heat of 50 is conducted to the mask frame to cause thermal expansion of the mask frame, the mask frame pulls the shadow mask 50 outward due to the difference in thermal expansion.

Further, the color cathode ray tube passes through a high temperature heating step in its manufacturing process, and the tensile deformation due to the difference in thermal expansion between the shadow mask 50 and the mask frame at this time is even more serious. In order to reduce this, many such shadow masks 50 have a structure in which a skirt portion 53, which is usually formed by bending the outer periphery of the shadow mask 50, is fixed inside the mask frame. When the shadow mask 50 is pulled, the tongue portion or the like provided on the fixed portion of the skirt portion 53 elastically deforms and functions as a cushion, so that the effective surface 51 of the shadow mask 50 is pulled and deformed. It prevents it from being affected.

[0008]

Recently, a color cathode ray tube in which the outside of the screen is a flat surface has become mainstream, and in this case, the inner surface of the panel is also considerably flat. The larger the screen, the more flatness is required. Therefore,
The corresponding curved surface of the shadow mask is becoming flatter and has a smaller curvature. Such a shadow mask having a small curvature has a weak curved surface holding strength. The deterioration of the curved surface holding strength is directly related to the deformation of the shadow mask easily due to the vibration or shock received during the manufacturing process of the color cathode ray tube or during the transportation of the product after the product is manufactured.

As described above, the distance between the shadow mask and the funnel needs to be strictly regulated, and if the above-mentioned deformation occurs, the phosphor screen formed by exposure will not be formed correctly during manufacturing, resulting in a serious defect. Further, after the product is manufactured, the electron beam does not reach a predetermined phosphor, which causes deterioration of color purity.

On the other hand, when the screen becomes large and the lengths of the long side and the short side of the shadow mask become large, the difference in the amount of extension due to the difference in thermal expansion also becomes large, and the pulling force becomes proportionally large, which causes deformation. Becomes even more serious.

Further, in the color cathode ray tube having a flat screen, the shadow mask is also flattened in accordance with it, and the curved surface holding strength is relatively smaller than that of the conventional shadow mask having a large curvature. Against
There is a high possibility that it will lead to a large deformation of the curved surface.

Particularly in recent years, the demand for higher image quality has increased, and the pitch of the phosphors of the phosphor screen has been made as small as possible in order to improve the resolution, so that the margin for deviation of the beam landing has become small. The accuracy of beam landing has been required more than ever.

The present invention has been made in view of the above circumstances, has an excellent effect of preventing deformation, improves curved surface holding strength,
An object of the present invention is to provide a shadow mask capable of improving manufacturing stability and operation stability, and to provide a color cathode ray tube capable of producing an image with stable beam landing and good color purity by using the shadow mask. To do.

[0014]

In order to solve the above problems, the present invention provides a substantially rectangular effective surface having a large number of electron beam passage holes, and an outer peripheral portion of the effective surface. A skirt portion having first and second bent portions and extending in the pipe axis direction is formed by the first bent portion, and the second bent portion is between the effective surface and the first bent portion. In the shadow mask, which is bent in the opposite direction to the first bent portion, the second bent portion position in the direction along the tube axis is the first bent portion and the skirt portion. Is located between the end of the skirt and the first bent portion and the second bent portion in the tube axial direction, and the skirt protrusion amount is the outer peripheral portion of the effective surface. For the short side and the long side, , Those that changes smoothly such that the maximum at the central portion.

According to the shadow mask of the present invention, the skirt protrusion amount is smoothly changed so that the short side and the long side in the outer peripheral portion of the effective surface are minimum at both ends of the side and maximum in the central portion. Since it is configured to, the curved surface holding strength of the effective surface is increased under the action of load due to shock and vibration during the manufacturing process, and when the tensile force due to the thermal expansion difference with the mask frame during actual operation is applied. Also, deformation can be prevented.

Further, the color cathode ray tube of the present invention includes a vacuum envelope formed by joining a panel and a funnel, a phosphor screen substantially formed on the inner surface of the panel, and a phosphor screen in the panel. The present invention is characterized in that it has a shadow mask having the above-mentioned configuration arranged facing each other, and a mask frame supporting the shadow mask and having a thermal expansion coefficient larger than that of the shadow mask.

According to the color cathode ray tube of the present invention, deformation of the shadow mask curved surface due to impact or vibration during operation or during the manufacturing process is prevented, and the pulling due to the difference in thermal expansion from the mask frame during actual operation is performed. Deformation is prevented even when a force is applied, and the deviation of the beam landing is reduced to effectively suppress the deterioration of the color purity, and a higher quality image can be displayed.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG.
It will be described in detail with reference to FIGS.

In FIG. 1, the color cathode ray tube of the present embodiment has a glass vacuum envelope, which is composed of a substantially rectangular panel 12, a funnel 13 and a neck portion 19. Has become. The inner surface of the panel 12 is a concave surface having an asphericity, and a rectangular phosphor screen 14 in which phosphor stripes of three colors are regularly arranged is provided on the inner surface.

The phosphor stripes of the phosphor screen 14 are formed by alternately arranging red, green and blue light emitting bodies alternately. Usually, the phosphor stripe direction is the vertical direction (Y axis). A shadow mask structure 15 is mounted in the vacuum envelope in proximity to the phosphor screen 14. The shadow mask structure 15 is composed of a mask frame 29 having a rectangular frame shape and a shadow mask 28 having a rectangular curved surface having a large number of electron beam passage holes 26, and is elastic by the stud pin 17 embedded in the skirt portion of the panel 12. It is elastically supported via the support member 16.

The shadow mask structure 15 has a tube axis (Z
(Axis) is the center axis of the phosphor screen 14 in the direction perpendicular to the phosphor screen 14, the tube axis is supported at a position passing vertically through the center of the shadow mask 28. The electron beam passage hole 26 of the shadow mask 28 is formed as a slot substantially corresponding to the phosphor stripe of the phosphor screen 14 along the minor axis direction.

The neck portion 19 has an in-line type electron gun 2
1 is attached, and three electron beams 20R, 20G, and 20B are emitted from the electron gun 21, pass through the electron beam passage hole 26 of the shadow mask 28, and are projected onto the phosphor screen 14 as shown in FIG. Make it hit.

These electron beams 20R, 20G, 20B
Is a deflection device 2 attached to the outer wall of the funnel 13.
The shadow mask 28 and the phosphor screen 14 are scanned by being deflected by 3. The electron beams 20R, 20G, and 20B that have passed through the region of the shadow mask 28 where the electron beam passage holes 26 are formed are converted into the phosphor screen 14.
When it hits, the phosphor is caused to emit light and an image is displayed.

The shadow mask structure 15 is shown in FIGS.
As shown in FIG. 2, the effective surface 28 a facing the phosphor screen 14 provided on the inner surface of the panel 12 is the panel 12 described above.
Has a curved surface shape corresponding to the inner surface of the effective portion, and a large number of electron beam passage holes 26 are provided in the effective surface 28a.
A substantially rectangular shadow mask 28 having a plate thickness of about 0.1 to 0.3 mm in which a skirt portion 27 is bent and formed on the outer circumference of the effective surface 28a, and is attached to the outer circumference of the skirt portion 27 of the shadow mask 28. And a substantially rectangular mask frame 29.

The mask frame 29 has a thickness of about 0.5 mm.
It is formed by punching out a plate-shaped material having a thickness of about 1.5 mm. An invar material is used for the shadow mask 28, and a normal cold-rolled steel plate is used for the mask frame 29.

On the outer peripheral portion of the shadow mask 28 constituting the shadow mask structure 15, as shown in an enlarged view in FIGS. 3 and 6, the skirt portion 2 is provided with two bent portions.
7 is provided.

Of the two bent portions, the first bent portion 32 is a portion obtained by bending the outer peripheral portion of the effective surface 28a substantially along the tube axis direction, and constitutes the top portion 30 of the skirt portion 27. . The second bent portion 31 has an effective surface 28a.
Between the first bending portion 32 and the first bending portion 32, and the bending direction is opposite to that of the first bending portion 32, and the bending is performed at an appropriate angle toward the phosphor screen 14 side. Therefore, the top portion 30 of the skirt portion 27 is in a state of protruding toward the phosphor screen 14 side from the portion where the extension surface of the effective surface 28 a of the shadow mask 28 intersects the skirt portion 27.

Assuming that the distance between the first bent portion 32 and the second bent portion 31 in the tube axis direction is the skirt protrusion amount (mm) as shown in FIG. 6, this skirt protrusion amount is as shown in FIG. , The shadow mask 2 as shown in FIGS.
In the short side and the long side in the outer peripheral portion of the effective surface 28a of No. 8, the smooth change is made so that it becomes maximum at the central portion of each side and minimum at both ends (diagonal portions) of the side.

The dimension from the first bent portion 32 to the end of the skirt joined to the mask frame 29 is the skirt length (mm). Table 1 below shows a comparison of the skirt protrusion amount and the skirt length of the present embodiment and the conventional example.

[0030]

[Table 1]

In the present embodiment, at the center of the long side (X-axis direction) and the center of the short side (Y-axis direction), this skirt protrusion amount is 5 mm larger than the diagonal portion, and during this period,
They are connected by a continuous change corresponding to an arc. On the other hand, in the case of the conventional example, the skirt protrusion amount is constant for the entire circumference,
0 mm, Conventional Example 2 is 3 mm, Conventional Example 3 is 8 mm
As compared with these three types.

According to the structure of this embodiment, the curved surface holding strength of the effective surface 28a of the shadow mask 28 is improved as compared with the prior art examples 1 to 3 in which the skirt protrusion amount is constant over the entire circumference. A uniform load is applied to the effective surface 28a of the shadow mask 28, and the maximum withstand load during deformation is measured.
Shown in.

[0033]

[Table 2]

Here, the curved surface shape of the effective surface 28a has exactly the same specifications as in the present embodiment and the conventional examples 1 to 3. still,
In the conventional example, the skirt protrusion amount is 0 m in the conventional example 1.
In the conventional example 2, the one having a constant circumference of 3 mm and the conventional example 3 having a constant circumference of 8 mm were used.

As is clear from Table 2, it was found that the present embodiment has a larger maximum load capacity that can withstand deformation as compared with the conventional examples 1 to 3.

The maximum load capacity means that the larger the value, the higher the curved surface holding strength of the shadow mask 28.
Therefore, it can be said that the present embodiment is superior in curved surface holding strength to the conventional examples 1 to 3. Shadow mask 28
The improvement of the curved surface holding strength greatly contributes to the stability at the time of manufacturing, the yield improvement, and the product quality stability.

Next, regarding the tensile force generated due to the difference in thermal expansion between the shadow mask 28 and the mask frame 29, the amount of deformation of the curved surface region of the shadow mask 28 when this tensile force is generated will be considered.

Shadow mask 28 and mask frame 29
Are fixed at the center of the short side, at the center of the long side, and at the diagonal portion, and a tensile force according to the difference in thermal expansion acts on this portion. Here, the amount of deformation of the curved surface area of the shadow mask 28 is determined by the long side of the effective surface 28 a of the shadow mask 28,
It is the maximum displacement in the tube axis (Z axis) direction on each of the short side and the diagonal part. It is preferable that the amount of deformation due to the pulling force is small. Regarding the amount of deformation due to the pulling force, it can be said that it is effective to increase the amount of skirt protrusion. Even if the entire circumference is constant, the amount of deformation can be reduced by increasing the amount of skirt protrusion. This can be easily understood from the fact that increasing the skirt protrusion amount means extending the skirt length substantially.

Next, focusing on the relationship between the amount of protrusion of the skirt at the diagonal portion, the center of the short side and the center of the long side and the amount of deformation due to the pulling force, from the shape of the rectangular shadow mask 28,
It is presumed that the sensitivity due to the increase in the skirt protrusion amount is higher (the deformation prevention effect is higher) at the center of the short side and the center of the long side than the diagonal part.

Further, in the manufacturing process of the shadow mask 28, press molding is adopted, but in this case, a strong pressing force acts especially on the diagonal portion. Forming a large protruding portion in the direction opposite to the bending direction of the skirt portion 27 in this diagonal portion further increases the pressing force, and during the manufacturing process, this portion is perforated by cutting, breaking, etc. This makes it easier to generate tears and the like.

Therefore, the skirt protrusion amount at the diagonal portion is not so large (minimized), and the skirt protrusion amount at the center of the short side and the center of the long side, which has a high deformation prevention effect, is made larger (maximum) than the diagonal portion. However, even with the configuration of the present embodiment, if the substantial skirt protrusion amount increases in the center of the short side and the center of the long side, it is disadvantageous for tensile deformation. It can not be said that.

As described above, according to this embodiment,
The shadow mask 28 is improved in the curved surface holding strength against a load, and the shadow mask 2 is pulled by a tensile force due to a difference in thermal expansion.
8 can be prevented, and as a result, the stability of the color cathode ray tube using this shadow mask 28 during manufacturing and operation is improved.

Also, in a super-large color cathode ray tube and a color cathode ray tube whose screen has become flat and whose curved surface strength has deteriorated,
By using the shadow mask 28 in the form of the present paper, it is possible to prevent the effective surface 28a of the shadow mask 28 from being deformed due to impact or vibration during the operation or during the manufacturing process, and improve the manufacturing stability in the phosphor screen forming process. It is possible to improve the yield and further improve the quality stability and reduce the deviation of the beam landing to reduce the color purity even in a color cathode ray tube having a shadow mask with a small aperture pitch for high quality. Can be effectively suppressed, and a higher quality image can be displayed.

[0044]

As described above, according to the present invention,
Effective surface 2 under the load of shock and vibration during the manufacturing process
It is possible to provide a shadow mask in which the curved surface holding strength of 8a is increased, and deformation can be prevented even when a tensile force due to a thermal expansion difference from the mask frame during actual operation is applied.

Further, according to the present invention, the deformation of the shadow mask curved surface is prevented, and the deviation of the beam landing is reduced to effectively suppress the deterioration of the color purity and display a higher quality image. It is possible to provide a color cathode ray tube capable of performing the above.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a color cathode ray tube according to an embodiment of the present invention.

FIG. 2 is a schematic plan view showing the configuration of the shadow mask structure of the color cathode ray tube according to the present embodiment.

FIG. 3 is a schematic cross-sectional view showing the configuration of the shadow mask structure according to the present embodiment.

FIG. 4 is a side view of the shadow mask according to the present embodiment viewed from the long side.

FIG. 5 is a side view of the shadow mask according to the present embodiment viewed from the short side.

FIG. 6 is a partially enlarged explanatory view showing the configuration of the skirt portion of the shadow mask according to the present embodiment.

FIG. 7 is a schematic perspective view showing a four-divided portion of the shadow mask of the present embodiment.

FIG. 8 is a schematic plan view showing a conventional shadow mask.

[Explanation of symbols]

12 panels 13 funnel 14 phosphor screen 15 Shadow mask structure 16 Elastic support member 17 Stud pin 19 neck 20R electron beam 21 electron gun 23 Deflection device 26 Electron beam passage hole 27 Skirt 28 Shadow Mask 28a Effective surface 29 mask frames 30 top 31 Second bent portion 32 First bent portion

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshiaki Ito             2 shares, 1-9-1 Harara-cho, Fukaya City, Saitama Prefecture             Company Toshiba Fukaya Factory F term (reference) 5C031 EE03 EE04 EF05 EH04 EH06

Claims (4)

[Claims] 1. A substantially rectangular effective surface having a large number of electron beam passage holes formed therein, and first and second bent portions on an outer peripheral portion of the effective surface. A skirt portion extending substantially along the tube axis direction is formed by the portion,
Is a shadow mask that is bent between the effective surface and the first bent portion in a direction opposite to that of the first bent portion, and The second bent portion position is located between the first bent portion and the end of the skirt portion, and the first bent portion and the second bent portion are disposed.
When the skirt protrusion amount is the distance from the bent portion in the tube axis direction, the skirt protrusion amount is minimum at both ends of the short side and long side at the outer peripheral portion of the effective surface and maximum at the center portion. A shadow mask characterized by a smooth transition to. 2. The amount of protrusion of the skirt smoothly changes so that the short side and the long side of the outer peripheral portion of the effective surface have a minimum of 3 mm at both ends of the side and a maximum of 8 mm at the center. The shadow mask according to claim 1, wherein: 3. A vacuum envelope formed by joining a panel and a funnel, a phosphor screen formed on the inner surface of the panel by a plurality of phosphor rows substantially connected in the minor axis direction, and a plurality of electronic windows. A substantially rectangular effective surface having a hole through which holes are formed, and first and second bent portions on an outer peripheral portion of the effective surface, the first bent portion extending substantially along the axial direction of the pipe. A shadow mask in which an extending skirt portion is formed, the second bent portion is between the effective surface and the first bent portion, and is bent in a direction opposite to the first bent portion; A color cathode ray tube having a mask frame having a coefficient of thermal expansion larger than that of the shadow mask supporting the shadow mask, wherein the second bent portion position in the direction along the tube axis of the shadow mask is One The skirt protrusion amount is located between the bent portion and the end of the skirt portion, and the skirt protrusion amount is a skirt protrusion amount that is a pipe axial direction distance between the first bent portion and the second bent portion. The color cathode ray tube is characterized in that, in the short side and the long side in the outer peripheral portion of the effective surface, there is a smooth change such that the short side and the long side have a minimum at both ends and a maximum at the center. 4. The skirt protrusion amount smoothly changes so that the short side and the long side in the outer peripheral portion of the effective surface have a minimum of 3 mm at both ends of the side and a maximum of 8 mm at the central portion. The color cathode ray tube according to claim 3, wherein: