JPH06275207A - Slot type shadow mask and color cathode-ray tube fitted with the mask - Google Patents

Abstract

PURPOSE:To prevent the generation of a mechanical change between the effective surface of a slot type shadow mask and the part other than this, and eliminate the breakage of a bridge by providing a recessed part situated in parallel to the bridge to weaken the mechanical strength on the effective surface, or providing a through-hole in addition to this. CONSTITUTION:Grills 2, for example, having a width of 0.225mm and a length of 280mm are connected to each other with bridges 3 having a width of 0.1mm and a pitch of 1.0mm. The positions of the bridges 3 are shifted by the half pitch to the adjacent grills 2, their transverse directions are situated in the same position every other grill, and the thickness of the bridge 3 is set to about 0.008mm. To avoid the breakage of the bridge 3 on the slot line on the lateral most outside circumference of an effective surface, a groove 4 parallel to the slot line and having a transverse pitch of 0.3mm which is the same as the slot line and a length of 293mm slightly longer than the grill 2 is provided further on the outside of the most outside slot line. The groove 4 is set to a width of 0.1-0.2mm and a depth of 0.05-0.02mm. The collection of bridge breakage is thus eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask type color cathode ray tube, and more particularly to improvement of performance of a slot type shadow mask.

[0002]

2. Description of the Related Art Color cathode ray tubes currently in practical use are generally of shadow mask type. In FIG. 5, the function of the shadow mask 25 is that the three electron beams Bc and Bs emitted from the electron gun 31 are applied to the inner surface (image display surface) of the panel 21 in a divided manner. This is to selectively control the path of each electron beam so as to selectively hit each of the phosphor screens 24 made of phosphors of three colors.

In FIG. 5, Bc is a center beam, Bs is a side beam, 22 is a funnel, 23 is a glass neck, 26 is a magnetic shield, 27 is a deflection yoke,
Reference numeral 28 is a reinforcing band, 29 is a spring for supporting the shadow mask, and 30 is a pin embedded in the skirt of the panel and fitted with the spring.

The shadow mask 25 is generally a thin plate of iron or an iron-nickel alloy having a small expansion coefficient, and has round holes, rectangular holes, or long rectangular holes continuous from the top to the bottom of the image display surface. . A shadow mask with round holes is called a dot-type shadow mask, a shadow mask with rectangular holes is called a slot-type shadow mask, and a shadow mask with long rectangular holes continuous from the top to the bottom of the image display surface is called a grill-type shadow mask. I will decide.
The slot type shadow mask can be thought of as a structure in which there are bridges connecting the grills in places where the grill type shadow masks are arranged in parallel. Generally, the dot type shadow mask and the slot type shadow mask are often shaped into a spherical shape, and the grill type shadow mask is held in a cylindrical shape by applying vertical tension. Since the electron beam collides with the shadow mask, the temperature rises and thermal expansion occurs. In recent years, as the definition of image display has increased, the displacement due to the thermal expansion of the shadow mask becomes an obstacle, and in order to avoid thermal expansion, the dot-shaped shadow mask and the slot-shaped shadow mask that are spherically shaped are the materials of the shadow mask. The iron-nickel alloy having a small expansion coefficient is used as the grill type shadow mask, and tension is applied to the shadow mask to hold it. However, iron-nickel alloy is expensive, and when holding the grill type shadow mask in a cylindrical shape by applying tension in the vertical direction of the image display surface, the frame for holding can withstand the tension of the shadow mask. It has a drawback that it requires mechanical rigidity and becomes heavy. If you try to raise the definition of the image further,
In either case, it is necessary to reduce the pitch of the holes in the shadow mask and reduce the diameter of the holes. If the plate is thick, it will be very difficult to make small holes, so we want to reduce the plate thickness. However, the dot-shaped shadow mask and the slot-shaped shadow mask that are shaped spherically cannot reduce the thickness of the shadow mask plate beyond a certain amount because the shadow mask needs to maintain its shape. The grill type shadow mask, which has a long rectangular hole that runs from the top to the bottom of the image display surface, is deformed by the grille being entangled during manufacturing, so the thickness of the plate cannot be reduced beyond a certain level. Therefore, it is very difficult to further increase the definition of image display only by extending the current technology.

[0005]

The following method can be considered as one of means for overcoming the above technical barriers. First, it is very difficult to form a shadow mask hole in a thin plate, for example, an iron plate having a thickness of 0.025 mm, and the grill type is very difficult. Therefore, the slot type is adopted. But,
With this thickness, it is very difficult to shape and hold the spherical surface as in the conventional case. Instead, choose a tension-holding method like a grill-type shadow mask. Then, another problem occurs. That is, when the slot-type shadow mask is held by applying vertical tension parallel to the grill, the horizontal tension generated by the Poisson's ratio is transmitted by the bridge, and as the shadow mask grill moves away from the center to the left and right, it becomes not a straight line in the vertical direction. The problem is that it bends in the direction. As one of the methods to solve this, it is possible to make the bridge with reduced width and thickness. Then, the mechanical strength of the bridge becomes weak and the bridge may break. In particular, the phenomenon of disconnection is concentrated on the bridges in the outermost rows on the left and right of the effective surface having the slots. This is because the mechanical strengths of the effective surface having the slot at this location and the other portions are significantly changed.

The present invention provides a color cathode ray tube which solves the problems caused when the above-mentioned slot type shadow mask is used. In other words, the phenomenon that the bridge of the slot type shadow mask for high-definition display in which the plate thickness is thinned and small holes are cut is concentrated on the bridges in the outermost rows on the left and right of the effective surface with slots. There is provided a shadow mask plate for a color cathode ray tube which solves the above problem and a color cathode ray tube having the shadow mask plate mounted thereon.

[0007]

SUMMARY OF THE INVENTION The present invention addresses the above-mentioned problems in the outermost portions of the outermost rows on the left and right of the effective surface of a slotted shadow mask, particularly in the direction orthogonal to the grill, that is, in the direction parallel to the bridge. The recess is provided so that the plate thickness is partially reduced so that the mechanical strength becomes weak.
Further, as a substitute for this recess, or in addition to this recess, a through hole is provided outside in the direction parallel to the grill, which is substantially equal to or slightly longer than the length of the grill.

[0008]

By the above means, it is possible to prevent the mechanical strength from changing remarkably between the effective surface having the slot and the portion other than the effective surface and prevent the phenomenon that the bridge is broken.

[0009]

EXAMPLES A slot type shadow mask in a color cathode ray tube according to the present invention will be specifically described below with reference to examples.

FIG. 1 is a plan view of a slot type shadow mask plate according to the present invention. A portion is enlarged and shown. The slot type shadow mask plate 1 is a 0.025 mm thick iron plate with 0.075 mm wide, 0.9 mm long rectangular slots with a vertical pitch of 1.0 mm and a horizontal pitch of 0.3 mm, and a vertical length of about 280 mm. The width is about 380 mm and the surface is full. In other words, the grill 2 having a width of 0.225 mm and a length of 280 mm is connected by the bridge 3 having a width of 0.1 mm and a pitch of 1.0 mm. As shown in FIG. 4, the positions of the bridges 3 are deviated by half a pitch between adjacent grills, and every other one is at the same position in the horizontal direction. The bridge thickness is about 0.008 millimeters. As described above, the phenomenon that the bridges of the outermost slot rows on the left and right of the shadow mask effective surface in which the slots are conventionally formed is broken, so that the present invention is effective as shown in FIGS. 1 and 2. In order to alleviate the concentration of stress on the bridges 3 of the outermost row of slots, the lateral pitch parallel to the outermost row of slots is 0.3 mm, which is the same as the slot array. The groove 4 of 293 mm whose length is slightly longer than that of the grill is provided. It is effective that the groove has a width of 0.1 to 0.2 mm and a depth of 0.05 to 0.020 mm. Since the groove 4 is outside the effective surface, it does not penetrate. Although two grooves are shown in FIGS. 1 and 2, the number of grooves can be increased or decreased as necessary. As shown in FIG. 3, it is possible to further provide a groove on the back side. In FIG. 3, the lateral pitch is shifted by a half pitch from the front side, and the same groove as the front side is also provided on the back side. Further, as shown in FIGS. 1, 2 and 3, stress concentration can be further alleviated by providing a through groove 5 having a width of 1 mm and a length of 293 mm on the outer side of the groove 4 by 0.3 mm. This through groove 5
The purpose is to prevent stress from concentrating on the bridges of the outermost slot rows and causing bridge breakage during handling before mounting the shadow mask plate 1 shown in FIG. 1 on the color cathode ray tube. Therefore, the through groove 5 can be used as a part of the outermost peripheral cutting line for the shadow mask assembly to be mounted on the color cathode ray tube. The width of the through hole 5 is about 0.5 mm. The shadow mask shown in FIG. 1 is manufactured not by itself but by etching a continuous sheet by a well-known etching method,
The outer periphery is cut off and finally stretched on the frame to form a shadow mask assembly. The bridge disconnection described above occurs during handling during that time.

In the above embodiment, the through groove 5 is formed together with the groove 4 in which the thickness of the shadow mask is simply reduced. However, during the handling before mounting the shadow mask plate 1 on the color cathode ray tube. For the purpose of only preventing the bridge from breaking due to stress concentration, it goes without saying that the groove 4 having only the reduced plate thickness may be omitted and only the through groove 5 may be formed.

Next, a method of assembling the slot type shadow mask of the present invention will be described with reference to examples.

FIG. 4 is a perspective view of a slot type shadow mask assembly mounted on a color cathode ray tube according to the present invention.
1 is a slot-type shadow mask described with reference to FIG. 1, and the frame 12 is an L-shaped 2 having a material of 13 chrome steel and a cross section of 5 mm thick and a side length of 10 mm.
The two opposing bars 13 are supported by two U-shaped opposing arms 14 of 10 mm square each made of the same material. The upper and lower bars 13 of the frame 12 are compressed and held so that they are closer to each other by 1.0 mm than a predetermined distance, the shadow mask 1 is heated to 150 ° C., and the long side is welded to the bar 13 by laser light. When the temperature of the shadow mask 1 returns to room temperature, tension is applied to the shadow mask 1. Set the upper and lower bars 13 of the frame 12 to 1.0
The reason why the shadow mask 1 is compressed and held so that it approaches the millimeter is that the frame 12 is expected to deform when tension is applied to the shadow mask 1. This shadow mask 1
The assembly of the frame 12 and the frame 12 is shown in FIG.
Springs 71, 72, 73 and the like are used to hold the value at zero. Springs (not visible in FIG. 4) are provided at positions vertically and horizontally symmetrical with respect to the springs 71, 72, 73. The springs 71, 72, 73 are each made of stainless steel 0.4 mm thick, 10 mm wide and 90 mm long. As shown in FIG. 4, the springs 71, 72, 73 are welded at one end to the bar 13 or the arm 14. The tip of the pin 30 of the panel 21 is made of a part of a conical shape having a diameter of 4.0 mm, a height of 3.0 mm and a root diameter of 7.0 mm. Spring 7
1 has a diameter of 5.6 to fit at one end with a 5.6 millimeter diameter portion of the conical middle of the pin 30.
A round hole of millimeter is provided. Spring 72
The diameter of the conical middle part of the pin 30 at one end thereof.
A long hole with a shape in which circular holes with a diameter of 5.6 mm are placed in parallel with the fluorescent screen stripe (usually the vertical direction) with their centers offset by 1 mm so that they fit together in a 6 mm portion is provided. Has been. The spring 73 has at one end a diameter 5.6 of the conical middle part of the pin 30.
A long hole having a shape in which circular holes having a diameter of 5.6 mm are arranged with their centers displaced by 1 mm in a direction parallel to the tube axis so as to be fitted in a portion of mm is provided.

[0014]

As described above, according to the present invention, the phenomenon in which the bridge of the slot type shadow mask for high definition display in which the plate thickness is made thin and small holes are opened is solved is realized. It is possible to provide an inexpensive slot-type shadow mask capable of high-definition display, which was not possible.

[Brief description of drawings]

FIG. 1 is a plan view of a slotted shadow mask plate according to the present invention.

FIG. 2 is an enlarged plan view of an essential part of a slotted shadow mask according to the present invention.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a fully assembled shadow mask using the slotted shadow mask plate according to the present invention.

FIG. 5 is a sectional view illustrating the structure of a shadow mask type color cathode ray tube.

[Explanation of symbols]

1 ... Shadow mask, 2 ... Grill, 3 ... Bridge, 4 ...
Groove, 5 ... through groove.

Claims (4)

[Claims] 1. A slot-type shadow mask, characterized in that grooves having a reduced plate thickness are provided in parallel to the outermost left and right outermost slot rows of the effective surface of the slot-type shadow mask. Board. 2. A slot-type shadow mask plate, characterized in that through-grooves are provided in parallel to the outermost slots on the left and right of the effective surface of the slot-type shadow mask plate in parallel with the slots. 3. The slot type shadow mask plate according to claim 1, wherein a through groove is provided in a portion outside the groove in parallel with the slot row. 4. A color cathode ray tube comprising a panel having a striped phosphor screen and a slot-type shadow mask disposed in the panel with a predetermined gap from the phosphor screen. A color cathode ray tube, characterized in that grooves formed by reducing the thickness of the shadow mask are provided parallel to the outermost slot rows on the left and right of the effective surface of the shadow mask, in parallel with the slot rows.