KR20000073438A - Shadow mask for color CRT - Google Patents

Abstract

PURPOSE: A shadow mask for a color cathode ray tube is provided to maintain a sufficient strength even when the radius of curvature of the mask is increased due to flatness of cathode ray tube and to improve vibration and falling characteristics. CONSTITUTION: In a color cathode ray tube including a panel constructing a vacuumed housing and a shadow mask(70) having a greatly large number of holes with a dot or slot shape through which electron beam passes to inside a funnel, the shadow mask includes at least one longer bead(71) and shorter bead(72) perpendicular to each other in the effective plane of the mask. The width of the shorter bead is less than (the length of the longer side of the effective plane)/15.

Description

Shadow mask for color cathode ray tube {Shadow mask for color CRT}

The present invention relates to a color cathode ray tube, and more particularly, to a shadow mask for color cathode ray tube to cope with an increase in curvature due to the planarization by securing the structural strength of the shadow mask.

In general, color cathode ray tubes are the most widely used display devices for observation of oscilloscopes, radars, etc., including television receivers.

In addition, the color cathode ray tube includes red, green, and blue phosphor pixels having three primary color emission spectra of light, which is an all-optical device that converts image information received as an electrical signal into visual information, graphite as a light absorbing material, and It is a device that plays a role of delivering color images to human vision through a fluorescent film made of aluminum film for improving brightness.

Such a color cathode ray tube includes an apparatus as shown in FIG. 1.

The apparatus shown in FIG. 1 will be described as an example of a color cathode ray tube according to the prior art.

As shown, a panel 2 having red, green, and blue fluorescent films 1 formed on the inner side, a funnel-shaped funnel 3 fused to the rear end of the panel 2, and a neck of the funnel 3 The electron gun 6 enclosed in (4) to emit the electron beam 5, the shadow mask 7 and the shadow mask 7 which are separated from the fluorescent film 1 by a predetermined distance to serve as the color selection of the electron beam 5, and the shadow mask 7 ) Is mounted to the frame 8 supporting the panel 2 to be spaced apart from the inner surface of the panel 2 and the outer edge of the neck 4 so that the electron beam 5 is deflected to the entire area of the screen by the horizontal deflection field and the vertical deflection field. It consists of a deflection yoke (9).

In this state, when power is applied, the electron beam 5 is emitted from the electron gun 6, and the electron beam 5 is deflected at a predetermined angle by the horizontal deflection magnetic field and the vertical deflection magnetic field by the deflection yoke 9, thereby providing a shadow mask. After passing through the opening in (7), an image is realized by hitting the fluorescent film 1 on the inner surface of the panel 2.

In this case, as shown in FIG. 2, the inner surface of the panel 2 and the shadow mask 7 have almost the same curvature. When the radius of curvature of the inner surface of the panel 2 is Rp and the radius of curvature of the shadow mask 7 is Rm, It is common to have a relationship of 0.70 < Rm / Rp based on each axis.

In this case, given the radius of curvature of the inner surface of the panel 2, the radius of curvature and the shape of the curvature of the shadow mask 7 form a geometric structure with the curvature of the inner surface of the panel 2, and the radius of curvature of the shadow mask 7 is the panel (2) The structure is dependent on the curvature radius of the inner surface.

FIG. 3 illustrates the dimensions of each part of the cathode ray tube. In order to improve the purity characteristics of the cathode ray tube, the arrangement of the electron beam 5 in the entire effective surface area of the shadow mask 7 is designed with G / R = 1.0 (Just). This has the relationship as shown in Equation 1 below.

[Equation 1]

Beam Grouping Rate = (3 × S × Q) / (Ph × L)

Here, Beam Grouping Rate: three electron beam spacing (beam array), S: scanning line spacing, Q: distance from the slot 7a of the shadow mask 7 to the inner surface of the panel 2, Ph: of the shadow mask 7 The horizontal distance from the center of the slot 7a to the center of the adjacent slot 7a, L: The distance from the electron beam deflection center of the deflection yoke 9 to the inner surface of the panel 2.

4 shows the arrangement of the electron beam 5 according to the G / R value described above. When G / R = 1.0 (Just) is not set, the position of the electron beam 5 is shifted and the purity characteristics deteriorate. It can be seen that.

On the other hand, in recent years, a high-quality cathode ray tube is required, and according to this trend, attempts to enlarge and planarize screens have been made.

Therefore, the curvature of the inner surface of the panel 2 is planarized, and the curvature of the shadow mask 7 is also increased according to the curvature of the inner surface of the panel 2 so that the structural strength of the shadow mask 7 itself is weakened.

As such, when the structural strength of the shadow mask 7 is weakened, there is a problem that vibration and dropping characteristics due to external force are significantly reduced.

Therefore, it is necessary to reduce the radius of curvature of the shadow mask 7 itself, and the change of the radius of curvature is possible by the change of the pitch Ph of the shadow mask 7 when the beam arrangement G / R is constant.

That is, when the curvature of the inner surface of the panel 2 is determined, the incident angle of the electron beam for each position is determined according to the S value, which is the deflection yoke component, and the limit horizontal pitch Ph of the shadow mask 7 to satisfy the resolution of the screen suitable for a given image signal. Is determined.

Further, when the positions of the panel 2, the funnel 3, and the deflection yoke 9 of the color cathode ray tube are determined, the distance L from the deflection center of the deflection yoke 9 to the inner surface of the panel 2 is determined.

In this case, since L and S are determined as constants, in order to change the size and shape of the curvature radius of the shadow mask 7, the pitch Ph of the shadow mask 7 must be changed, and the curvature radius of the shadow mask 7 is reduced. It can be seen that the pitch Ph of the shadow mask 7 should be large in the above-described Beam Grouping Rate equation.

FIG. 5 illustrates a pitch change of the shadow mask 7, and as shown in FIG. 5A, the radius of curvature of the shadow mask 7 is increased by increasing the pitch Ph from the horizontal direction from the center of the shadow mask 7. It can be designed small.

That is, in the drawing, Ph ₀ <Ph ₁ <Ph ₂ ... The pitch of the shadow mask 7 is set so as to satisfy the relationship of <Ph _n .

Here, since the effective surface size of the shadow mask 7 is determined, in the pitch development in the vertical direction, as shown in Fig. 5B, Ph _{0 0} > Ph _{0 n} , Ph _{n / 2 0} ≒ Ph _{n / 2 n} , Ph _{n 0} < It can be seen that an appropriate pitch change is required to satisfy the relationship of Ph _nn .

However, the change in the curvature radius size and shape of the shadow mask requires precise work, which lowers workability and makes it very difficult to set an appropriate reference value. As the panel is flattened, there is a limit in changing the curvature of the shadow mask. It becomes difficult to preserve.

In order to solve this problem, a conventional method of using a double curvature such as a bead 10 on the left and right sides of the screen from the top to the bottom of the shadow mask 7 is proposed as shown in FIG. Since the light source of the exposure machine is a linear light source and the exposure machine is driven in the short axis direction of the screen, the width of the phosphors R, G, and B gradually decreases as shown in FIG. When the white pattern is floated while driving the cathode ray tube, the place where the bead 10 is inserted into the effective screen is darkened, thereby degrading the white uniformity.

Accordingly, the present invention has been proposed in view of such a point, and an object thereof is to provide a shadow mask for color cathode ray tube, which improves the purity characteristics and vibration characteristics of the color cathode ray tube by reinforcing the rigidity of the shadow mask.

1 is a configuration diagram of a general color cathode ray tube,

Figure 2 is a detailed view of the panel portion of a typical color cathode ray tube,

3A and 3B are dimensional explanatory diagrams of a general color cathode ray tube,

4 is a view showing the arrangement of each electron beam according to the beam grouping rate of a general color cathode ray tube,

5 is a pitch development view of a conventional shadow mask,

5A is a horizontal development view;

5B is a vertical development view,

6 is a state diagram when forming a vertical bead in a conventional shadow mask,

6A is a front view,

FIG. 6B is a cross-sectional view taken along line AA ′ of FIG. 6A;

7 is a view comparing arrays of phosphors;

Figure 7a is the case of normal arrangement,

FIG. 7B is a case where FIG. 6 is applied.

8 is a configuration diagram of a shadow mask according to the present invention,

8A is a front view,

FIG. 8B is a cross-sectional view taken along line BB ′ of FIG. 8A;

8C is a cross-sectional view taken along line C-C 'of FIG. 8A;

9 is a detailed view of the panel unit according to the present invention;

10 is a comparison of the buckling strength according to the curvature of the shadow mask,

10a illustrates a case where the curvature is constant,

10b is a case according to the invention,

11 is a graph according to the change in the buckling strength,

12 is a detailed view of the exposure apparatus.

*** Explanation of symbols for main parts of drawing ***

70: shadow mask 70a: slot

70b: Bridge 71: Long axis bead

72: unidirectional bead 73: exposure machine

74: light source 75: light source overlapping section

The shadow mask for a color cathode ray tube according to the present invention for achieving the above object is a color cathode ray tube provided with a shadow mask having a myriad of openings of a dot or slot type to pass an electron beam inside the panel and the funnel forming the vacuum outer container. A shadow mask comprising: (1) at least one long axial bead orthogonal to any uniaxial central portion in its effective plane; And (2) at least one uniaxial bead orthogonal to any of the major axis centers in the effective plane.

Preferably, the depth of each bead is Where k = (3 * S) / (Ph-L), q: bead depth, S: deflection yoke component, Q: distance from the shadow mask slot to the inner surface of the panel, Ph: shadow The distance from the slot center of the mask to the center of the adjacent slot, L: The distance from the deflection yoke's electron beam deflection center to the inner surface of the panel.

Optionally, when the q value is + around Q, each bead is formed in the funnel direction, and when the q value is-around Q, each bead is formed in the panel direction.

Preferably, the width of the uniaxial bead is less than (effective surface major axis size) / 15 or less.

In this way, even when the shadow mask is flattened and its radius of curvature increases, it is possible to maintain a constant rigidity at all times, thereby smoothly adapting to the flattening trend, and improving vibration and drop characteristics due to external force.

And, there may be a plurality of embodiments of the present invention, hereinafter will be described in detail with respect to the most preferred embodiment.

This preferred embodiment allows for a better understanding of the objects, features and advantages of the present invention.

Hereinafter, preferred embodiments of the shadow mask for color cathode ray tube according to the present invention with reference to the accompanying drawings will be described in detail.

In addition, in drawing used for description, about the component same as FIG. 1 thru | or 7, the same code | symbol may be attached | subjected, and the overlapping description may be abbreviate | omitted.

8 is a configuration diagram of a shadow mask according to the present invention, FIG. 8A is a front view, FIG. 8B is a sectional view taken along line BB 'of FIG. 8A, FIG. 8B is a sectional view taken along line CC ′ of FIG. 8A, and FIG. 9 is a panel according to the present invention. FIG. 10 is a comparison of buckling strength according to the curvature of the shadow mask, FIG. 10A is a case where the curvature is constant, FIG. 10B is a case according to the present invention, and FIG. 11 is a graph according to the change of the buckling strength. 12 is a detailed view of the exposure apparatus.

The present embodiment is to form a shadow mask 70 in accordance with the flattening trend of the color cathode ray tube, as shown in FIG. 8 in the center of the effective surface of the shadow mask 70 in a short axis direction and a long axis direction, that is, cross-shaped beads ( 71) 72 is formed.

At this time, each of the beads 71 and 72 should have an appropriate depth, and if the depth is too deep, the beam grouping rate determined by the position of the shadow mask 70 becomes large and the amount of mislanding is increased, thereby deteriorating the purity characteristics. do.

The proper depth of each bead 71, 72 derived through the experiment is shown in Equation 2 below.

[Equation 2]

Where k = (3 * S) / (Ph-L), q: bead depth, S: scan line spacing, Q: distance from the shadow mask's slot to the inner surface of the panel, Ph: center of the slot adjacent to the shadow mask's slot center Distance, L: Distance from deflection yoke's electron beam deflection center to inner surface of panel.

At this time, if q is positive with respect to Q, the direction of each bead 71, 72 will be the funnel 3 direction, and if q value is-around Q, the direction of each bead 71, 72 will be It becomes the panel 2 direction.

In addition, in setting the width of each of the beads 71 and 72, the long axis bead 71 has no width limitation due to the vertical driving principle of the exposure machine, but the short axis bead 72 is directly related to the white uniformity. Therefore, the width setting is very important.

The proper width of the uniaxial bead 72 derived through the experiment is shown in Equation 3 below.

[Equation 3]

Referring to the operation of the shadow mask for color cathode ray tube according to the present invention configured as described above are as follows.

In general, when the curvature value of the inner surface of the panel 2 is greater than or equal to the curvature radius representative value 4R (1R = 1.767 × diagonal length), the curvature of the shadow mask 70 is determined according to the curvature of the inner surface of the panel 2. Has been described above.

For example, as shown in FIG. 9, when the diagonal length of the panel 2 is 676 mm, the shadow mask is formed between the inner curvature of the panel 2 and the curvature of the shadow mask 70 because a relationship such as 0.7 <Rm / Rp is established. The radius of curvature of the 70 is Rm> 3300, but the radius of curvature at the center of the shadow mask 70 is about 1.5 times the size of the representative radius of curvature, which is about Rm ≒ 5000, so that the radius of curvature is almost flat.

The buckling strength Pcr in this case is as shown in FIG.

That is, the ideal case for the strength is a spherical shape as shown in Figure 10a, the smaller the radius of curvature, the greater the buckling strength. That is, it means having a curvature structure that can withstand strong forces.

On the contrary, FIG. 10B is a general tendency according to the flattening of the shadow mask 70. Since the center curvature radius of the shadow mask 70 is formed about 1.5 times larger than the periphery, stress is generated only in the vertical direction even when a small load is applied. Therefore, a counter stress of a given load is required.

Expressing such a buckling strength (Pcr) is the same as Equation 4 below.

[Equation 4]

here, , to be.

In the present invention, cross-shaped beads 71 and 72 are formed in the center of the effective surface of the shadow mask 70 in order to secure the counter stress according to the shape of the substantially flat shadow mask 70 as described above.

That is, the formation of the beads (71) 72 is to act in the direction of increasing the counter stress against the load concentration phenomenon in the center according to the planarization of the curvature radius of the shadow mask (70).

At this time, in the case of the planarized cathode ray tube having a radius of curvature of more than 3000 mm connecting three points within the effective surface of the shadow mask 70, a plurality of beads 71 and 72 in the short axis direction and the long axis direction to maintain the strength thereof. ) May be formed, but it is preferable to form one bead 72 at the center in consideration of phosphor coating characteristics in the short axis direction.

FIG. 11 is a graph comparing the strength of the general shadow mask 7 with the cross-shaped beads 71 and 72 formed in the center of the effective surface of the shadow mask 70. As shown in FIG. If it becomes larger, the buckling strength decreases exponentially, but it can be seen that the strength of the shadow mask 70 in which the cross-shaped beads 71 and 72 are formed is excellent when compared to the other.

Here, in forming the cross-shaped beads 71 and 72 in the center of the effective surface of the shadow mask 70, the application characteristics of the phosphor or the quality of the screen must be considered. For example, the unidirectional direction of the shadow mask 7 When the beads 10 are formed only, the width of the phosphors R (G) and (B) is narrowed, and the quality of the screen is deteriorated.

In the case of a color cathode ray tube, the pattern of the fluorescent film 1 is largely divided into a dot shape and a stripe shape. Among these, the shadow mask for forming the striped fluorescent film 1 has a bridge in the vertical direction and employs a mask forming method. There is a slotted shadow mask and a grille shadow mask welded to the frame using tension without a bridge in the vertical direction.

As a shadow mask 70 according to the present invention, a method of forming the striped fluorescent film 1 by using the slotted shadow mask as an example is as follows.

First, as shown in FIG. 12, in the case of the exposure machine 73, the light source 74 uses a linear light source in a short axis direction, and the driving direction of the light source 74 is also driven in the short axis direction so that the slot 70a of the shadow mask 70 is used. Since the overlap section 75 is generated by the overlapping of the light source 74 passing through the light source 74 passing through the adjacent slot 70a, it may be generated by the vertical bridge 70b of the shadow mask 70. A uniform striped fluorescent film 1 can be formed regardless of the shadow present.

At this time, the use of the linear light source is because the effect of improving the straightness of the stripe is obtained by driving in the shorter direction than the fixed light source in forming the stripe-shaped fluorescent film 1 on the screen.

As described above, even if the long axis beads 71 are formed in the effective surface of the shadow mask 70 by using the exposure light source in the short direction, the vertical bridge 70b as described above does not affect the screen. In the same principle as that of the present invention, it is possible to form a uniform spherical fluorescent film 1.

However, since the shadow mask 70 according to the present invention not only has the long axis beads 71 but also the short axis beads 72, the shadow mask 70 may affect the exposure light source driven in the short axis direction, but the bead 10 may be affected. Rather than being located at the left and right sides of the effective surface center portion, only one unidirectional bead 72 according to the present invention is located at the effective surface center portion, so that it is easier to manage white uniformity than the conventional structure.

That is, since the center of the effective surface of the shadow mask 70 coincides with the center of the exposure light source 74, the reduction of the black matrix shrinkage that may be caused by the short axis driving of the light source 74 is very small, and the short axis bead ( Since the width of 72 is set to (Effective surface major axis size) / 15 or less as in Equation 3, the dispersion angle is very small at the center of the exposure light source 74, so that the light intensity decrease can be ignored.

For example, in the case of a 29 "color cathode ray tube, the center of the exposure light source 74 is formed when the width of the uniaxial bead 72 is formed to be 30 mm (15 mm each on the left and right sides) at the center of the effective surface of the shadow mask 70. Since the dispersion angle is about 3 °, the light intensity decreases slightly.

In addition, when the unidirectional bead 72 is a problem, it is possible to solve the problem of lowering the white uniformity by the unidirectional bead 72 by adjusting the filter transmittance in the uniaxial direction of the exposure machine 73.

On the other hand, as a comparative example, unlike the prior art, that is, a plurality of beads are formed in the short axis direction of the shadow mask, and the width of the phosphor is narrowed when forming the fluorescent film, the purity of the screen is deteriorated and the quality of the screen is deteriorated. It can be seen that the invention forms a cross-shaped bead in the center of the effective surface of the shadow mask to reinforce the strength of the shadow mask itself without deterioration of the screen.

As a result, according to the present invention, sufficient rigidity can be maintained even when the curvature radius of the mask is increased due to the planarization of the cathode ray tube, and there is an advantage of improving vibration characteristics, that is, howling characteristics due to external force.

In addition, although specific embodiments of the present invention have been described and illustrated above, it is obvious that the present invention may be variously modified and implemented by those skilled in the art.

Such modified embodiments should not be individually understood from the technical spirit or the prospect of the present invention, and such modified embodiments should fall within the appended claims of the present invention.

It is clear from the above description that the present invention can maintain sufficient rigidity even when the curvature radius of the mask increases due to the planarization of the cathode ray tube, thereby improving the vibration characteristic and the drop characteristic by external force.

Claims (5)

In a color cathode ray tube with a shadow mask having a myriad of openings in the form of dots or slots through which an electron beam passes through a panel forming a vacuum outer container and: The shadow mask is, (1) at least one long axial bead orthogonal to any short axis central portion in its effective plane; And (2) A shadow mask for color cathode ray tubes, characterized in that it comprises at least one uniaxial bead orthogonal to any of the major axis centers in the effective plane. The method of claim 1, The depth of each bead, Shadow mask for color cathode ray tube, characterized by satisfying the following relationship [Relationship] Where k = (3 * S) / (Ph-L), q: bead depth, S: deflection yoke component, Q: distance from the shadow mask's slot to the inside of the panel, Ph: adjacent slot from the shadow mask's center of the slot Distance to center, L: distance from deflection yoke's electron beam deflection center to inner surface of panel). The method of claim 2, When the q value is + centered on Q, the respective beads are formed in the funnel direction; If the q value is-around Q, each bead is formed in the panel direction, the shadow mask for color cathode ray tube. The method of claim 1, The width of the uniaxial bead, (Effective surface major axis size) / 15 or less shadow mask for color cathode ray tube. The method of claim 1, The shadow mask for color cathode ray tube, characterized in that if the radius of curvature connecting any three points in the shadow mask effective surface exceeds 3000mm, a single axial bead is formed and a plurality of long axial beads are formed.