JPH0246629A - Shadow mask for color picture tube - Google Patents

Abstract

PURPOSE:To prevent the deformation owing to a welding distortion and the thermal deformation owing to the striking of electron beams by making one side mask as a large thickness of mask with no bridge while the other side mask as a mask with a thin bridge, and providing circular grooves not penetrated around the welding connections of both masks. CONSTITUTION:Circular grooves 30 and 31 not penetrated yet are provided very close to a welding part 29, and thereby, the expansion of the welding stress is shielded and absorbed, the distortion is restricted at the periphery of the welding part insulating from the other parts, and a deformation of the shadow masks is prevented. Since a shadow mask B22 is made into a plate thickness less than that of a shadow mask A21, a penetration hole 23 of a narrow width can be produced easily, and bridges 33A, 33B and 33C to separate each penetration hole 23 can be made in a narrow widths, improving the permeability of electron beams thereby. The penetration hole 23 is provided at the position to prevent the striking of the electron beams passing through the hole 23 against the side walls 24 and 26, and the thermal deformation is minimized. Consequently, wrinkles, a separation, and a position slippage resulting from a welding distortion can be prevented, and a thermal deformation of the mask owing to the striking of electron beams can be also prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a shadow mask for a color picture tube.

[Conventional technology]

Conventionally, a shadow mask type color picture tube has a funnel-shaped funnel L, a panel 2 sealed to the funnel 1, a phosphor screen 3 coated on the inner surface of the panel 2, and a panel as shown in FIG. A plurality of pins 4 provided on the inner wall of 2;
A shadow mask structure 5 is provided which faces the phosphor screen 3 and is supported by pins 4.

The shadow mask structure 5 has an electron beam 6A.

6B, 6C selectively pass through a perforated surface having a large number of openings, and a non-porous surface formed around the periphery of this perforated surface, and having a spherical surface approximately equal to the inner surface shape of the panel 2. A mask 7 and a skirt 8 that is bent to adhere the shadow mask 7 to a frame to be described later.
A frame 9 is welded to the entire circumference of the mask skirt 8 at, for example, 8 to 16 points, and a frame 9 is welded to the frame 9 to compensate for thermal expansion of the shadow mask 7 that occurs during operation of the color picture tube. , and a spring 11 that is welded to the bimetal 10 and engages with the pin 4 to hold the shadow mask 7 in a position relative to the panel 2.

In the shadow mask type color picture tube having such a structure, the electron beams 6A, 6B, 6C emitted from the electron guns 12A, 12B, 12C pass through the aperture 13 provided at the opening of the shadow mask 7. The phosphors emit light in red, green, and blue colors applied to the phosphor screen 3 and emit light.
The total area of 13 is 15 of the surface area of the shadow mask 7.
% to about 25%, and most of the electron beams 6A, 6B6C collide with non-opening parts and heat the shadow mask 7. For example, as a result of measuring the temperature of the shadow mask structure 5 with a 21-inch color picture tube, the 8th The temperature increased as shown by the curve in the figure. That is, under the conditions of high voltage 28 ν and beam current 1 mA, the temperature at the center of shadow mask 7 increases significantly in the first 5 minutes, and saturates in 30 minutes, as shown by the characteristic direction 1s14. , the temperature increased by about 40°C. However, the temperature of the frame 9, which has a large heat capacity, gradually increased, showing a course as shown in the characteristic curve 15 in FIG. 8, and reached a saturated state in about - hours. Due to such a temperature rise, the mask 7 thermally expands and protrudes toward the phosphor screen 3, which causes color shift. That is, as shown in FIGS. 9 and 10, the shadow mask 7, which was in the state shown by the solid line before the start of operation, undergoes thermal expansion due to the rise in temperature and is displaced to the state shown by the dotted line. Therefore, on the phosphor screen 3, the electron beam 6A passing through the aperture 13 is
, 6B, and 6C move toward the center by a distance T in FIG.
This causes adjacent phosphors of other colors to emit light, making it impossible to reproduce a normal color image. When this was measured using a 21-inch color picture tube with a panel inner radius of 1350wm, the distance was 150mm from the center of the face of panel 2.
It is most noticeable on the long sleeves of
Color shift occurs due to movement.

On the other hand, when the temperature of the frame 9 gradually increases and approaches a saturated state, the frame 9 expands and displaces to the position 9A shown in FIG. 9 due to thermal expansion. Therefore, the shadow mask surface joined to the frame 9 shifts to the state 117B in FIG. 9. As a result, the electron beams 6A, 6B, and 6C passing through the apertures move outward by a distance S, causing the phosphors to emit light in the opposite direction to the phenomenon that appears at the beginning of the operation of the color picture tube. Color images cannot be reproduced. This phenomenon continues to appear as the color picture tube continues to operate, and it is necessary to correct it. Therefore, by the operation of the bimetal 10 (FIG. 7) attached to the frame 9, the frame 9 is displaced to 1f9B as shown in FIG. 9 so that the shadow mask 7 approaches the panel 2, and the beam trajectory changes to the fluorescent screen. The amount of color shift is corrected so that it matches.

However, in a screen where the local brightness of the screen increases, it has been impossible to correct the color shift due to thermal deformation of the shadow mask 7 facing the local area because it is hardly expected that the temperature of the bimetal 10 will increase. .

In order to solve these problems, it is theoretically possible to increase the thickness of the shadow mask as shown in the theoretical study on the local doming phenomenon of shadow mask tubes published in the Journal of the Television Society of Japan. has been proven. However, the shadow mask 7 is -111u
Generally speaking, it is usually manufactured using a chemical method, for example, an etching method as disclosed in Japanese Patent Publication No. 51-9264.

In this manufacturing method, there is a difference between the plate thickness and the size s of the shadow mask hole through which the electron beam passes.
There is a relationship as shown in the following equation, and it has been impossible to make small holes in a thick plate.

On the other hand, reducing the pitch of the phosphor screen in order to improve the resolution of CRT means that the shadow mask hole becomes smaller, and in order to maintain color purity due to thermal deformation of the shadow mask □. is in a contradictory relationship that requires a thick shadow mask. Therefore, as mentioned above, it is difficult to make the shadow mask hole small, so for example, as shown in Japanese Patent Application Laid-Open No. 57-138746, a large number of thin through-slots are connected by a bridge. A method of using a plurality of shadow masks 7 by welding them one on top of the other has been considered.

[1i81 to be solved by the invention However, shadow masks that are assembled by stacking multiple sheets are usually made of aluminum killed steel with a thickness of 0.3 mm or less, and have a large number of through holes through bridges in the short direction. Therefore, when the thickness of the shadow mask is increased, the width of the bridge becomes wider, which increases the rate at which the transmission of the electron beam is obstructed, which is a major obstacle to improving the brightness of the phosphor screen. Furthermore, when joining a plurality of shadow masks by laser welding or the like, if the incident direction of the laser beam is set to the A side as shown in FIG. 6, the molten part 38 of the metal will start from the A side. , reaches the mutually contacting surfaces B of the shadow masks, melts the other shadow mask by the amount necessary for fusion, and then blocks the incident energy,
The fused portion 38 is solidified to complete the bonding. In this type of welding joining method, the molten volume is relatively large, so
The molten part condenses during solidification, attracting nearby materials, deforming the hole shape and the entire shadow mask, which is facilitated by the press work to form it into a spherical shape, and CR
It could not be used as a shadow mask for T.

This invention was made to solve the above-mentioned problems, and in addition to preventing deformation of the shadow mask due to welding distortion, it also prevents the shadow mask from being heated by electron beams by manufacturing a thick shadow mask. An object of the present invention is to obtain a shadow mask for a color picture tube that prevents deformation.

[Means to solve the problem]

A shadow mask for a color picture tube according to the present invention includes: a shadow mask disposed facing a phosphor screen on the inner surface of a panel; a frame fixing the outer peripheral surface of the shadow mask;
In a shadow mask type color picture tube which is fixed to a frame and has a thermal correction mechanism for correcting thermal expansion of the shadow mask, the shadow mask is laminated and bonded, and one of the masks has a thick Fi thickness without a bridge. The other mask is thinner than the above mask and has a bridge, and a non-penetrating annular groove is provided around the welded joint of both masks.

[For production]

In this invention, since the volume of the mutually fused portions of the joints of the plurality of shadow masks can be reduced,
The amount of distortion that occurs when the molten part solidifies can be reduced to the necessary minimum, and by providing a non-penetrating annular groove in the center of the molten part of each shadow mask, the welding distortion caused by welding can be reduced. It is possible to prevent strain force from reaching areas other than the melted part.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a cross-sectional view taken along line I-1 in FIG. 2 of the shadow mask according to the present invention, FIG. 2 is a plan view showing a part of the shadow mask seen from the phosphor screen, and FIG. 3 is a - 4 is a plan view of the entire bonded shadow mask, and FIG. 5 is a perspective view of the press-molded shadow mask.

In Figures 1 to 3, 21 is located on the electron gun side, has a relatively thick plate thickness of 0.20 m+, and is a door-shaped plate without a bridge that reinforces the other shadow mask and is the main body of heat conduction. The shadow mask A122 is in contact with the shadow mask A21, is thinner than the shadow mask A21, and has a thickness of 0.1
The shadow mask B123 on the phosphor screen side, which is composed of a plate thickness of 3 mm and has holes for controlling the electron beam, is a door-shaped through hole provided in the shadow mask A21 for the electron beam to pass through, and 24 is a shadow mask hole 23. A side wall 25 is provided on the side of the shadow mask B22 that is in contact with the shadow mask A21, and is made slightly smaller than the shadow mask hole 23, and a through hole opening 26 is connected to the bridge.
27 is an unpierced hole provided in the shadow mask B22, and 28 is a through hole 27.
29 is the melted joint of shadow mask A21 and B22, 3° is the melted joint 2 of shadow mask B22
A non-penetrating annular groove provided around 9, 31 a side wall of the shadow mask hole 23 in contact with the shadow mask A21, 33
A, 33B, and 33C are bridges provided to connect the holes 25 provided in the shadow mask B22, FIGS.
In Fig. 5, 35 is a perforated part having through holes 23°25;
36 is a non-porous part without through holes 23 and 25, and 37 is almost perpendicular to the perforated part 35 forming a curved surface and a part of the non-porous part 36 when the shadow mask is press-molded into a shell shape. The shaped skirts 42A, 42B, and 42C are alignment holes for accurately aligning the shadow masks A21 and 822.

Next, in order to easily understand the present invention, an outline of a method for manufacturing a shadow mask will be explained. First, shadow mask A
A resist layer of a predetermined thickness is coated on both sides of each of 21 and B22, and one side of each shadow mask is coated with a resist layer of a predetermined thickness.
After each image drawn by a corresponding automatic drawing device is printed on the resist layer, unnecessary portions of the resist layer are removed. Thereafter, a chemical etching method is used to corrode and remove only the metal corresponding to the predetermined holes, thereby obtaining a desired shadow mask. During this etching, alignment holes 42A, 42B, 42C are provided to accurately align the shadow mask A21 and the shadow mask B22.
The shadow mask A21 and the shadow mask B22 are provided so as to be located other than the opening surfaces facing the phosphor screen, preferably at the skirt 37 of the formed shadow mask.

After that, shadow mask A21 and shadow mask B
22 are accurately aligned and attached to a predetermined jig (not shown) using the alignment holes 42A, 42B, 42C so that the desired surfaces of each are in contact with each other. In this way, the shadow mask A21 and the shadow mask B22 at the predetermined positions are connected to the shadow mask A21 and the shadow mask B22 at predetermined positions by an electron beam welding machine having a mechanism that can accurately measure the melting amount of the incident energy to melt the melted joint 29 and perform precise positioning. They are melted and joined at a predetermined fusion joint.

When the molten part of the shadow mask solidifies, the welding strain that occurs causes shrinkage stress around the welding point, and since the shadow mask has a thin plate thickness, the internal stress can easily cause shadow Transform the mask board. In order to prevent the internal stress that has such a negative effect from affecting areas outside the molten part of the shadow mask, the unpenetrated annular grooves 30 and 31 are provided very close to the welding part to spread the welding stress. By blocking and absorbing the distortion, it is possible to stop the distortion around the welded area and insulate it from the outside, thereby preventing the shadow mask from deforming.

When the annular groove is provided on the surface in contact with the shadow mask 21, 22, it is cut off from the inside of the tube, envelops impure gas, and gradually releases it into the tube during operation of the picture tube, shortening the life of the picture tube. In order to solve this problem, in the present invention, a part of the annular groove 30 is connected to the hole 2 of the shadow mask A21.
3, and has an opening 31 into the pipe. Shadow mask B22 is shadow mask A2
Since the bridge 33A is made thinner than the bridge 33A, narrow through holes 23 can be easily manufactured, and each of the through holes 23 is separated from each other.

33B and 33C are provided on the side where the plate thickness is thinner, so the width is narrower, so the transmittance of the electron beam can be improved, and the brightness of the phosphor screen can be increased. Regarding the relative positional relationship between the holes 23 and 25, the passage of the electron beam is restricted by the through hole 23,
The electron beam that has passed through the through hole 23 is placed in a position where it will not collide with the side walls 24 and 26, and is placed along the electron beam trajectory so as to minimize thermal deformation and maximize the weight of the shadow mask. Providing the through hole 25 in relation to the through hole 23 is the same as in the conventional shadow mask. In addition, since no bridge is provided on the thicker side of the shadow mask B22, when the welded shadow mask is press-formed, no shift deformation stress is applied to the shadow mask A21, resulting in a stable press shape. Can be molded.

〔Effect of the invention〕

As explained above, according to the present invention, wrinkles due to welding distortion, separation of shadow masks from each other, and displacement of the shadow masks can be prevented when the shadow masks are formed into a predetermined shape by press work, etc. A shadow mask with a fine pitch (and a thick plate) for high resolution can be manufactured, which prevents thermal deformation of the mask due to local impact of the electron beam on the shadow mask, and allows color picture tubes with high color purity to be produced. In addition, the transmittance of the electron beam can be increased, resulting in a bright screen image.

[Brief explanation of the drawing]

Fig. 1 is a sectional view taken along line 1-1M in Fig. 2 showing the assembled state of a plurality of shadow masks according to the present invention, and Fig. 2 is a part of the shadow mask in the direction away from the center as seen from the phosphor screen side. FIG. 3 is a cross-sectional view taken along line 11 in FIG. 2, FIG. 4 is a plan view schematically showing the bonded shadow mask, and FIG. 5 is a perspective view of the press-molded shadow mask. , FIG. 6 is a sectional view showing a conventional welded joint state, FIG. 7 is a partially cutaway perspective view of a shadow mask type color picture tube, and FIG. 8 is a diagram showing the frame and shadow mask in a shadow mask type color picture tube. A characteristic diagram showing the temperature rise course with respect to the elapsed operating time. Figure 9 is an explanatory diagram of the deformation state due to temperature changes in the main parts of the color picture tube. Figure 10 is a diagram showing the deformation phenomenon of the shadow mask structure in the color picture tube. It is an explanatory diagram. 21...Shadow mask A, 22...Shadow mask B, 29...Welded portion, 30...Unpierced annular groove, 3
3a-33c...Bridge. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa Fig. 1 Fig. 3 Fig. 33a N33c:) “Ridge Fig. Fig. Fig. Fig. Fig. Tatsumi Hotaru E Procedural amendment (voluntary) November 6, 1999 2, Name of the invention Color Shadow Mask 3 for Picture Tubes, Relationship with the Amendment Case Patent Applicant Address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Corporation Representative Shiki
Moriya 4, substitution 6, contents of amendment (1) "7A" is added next to "state indicated by dotted line" on page 4, line 8 of the specification. (2) On page 8, line 4, next to “by breath work”, “
"Because both masks have a bridge" is added. (3) "To be able to do it" on page 9, line 13 has been changed to "To be able to do so", and the bridge can prevent molding distortion caused by the difference in the position of the neutral line of the plate thickness of both masks during press molding from one mask to the other. Because it does not have it, it can be reduced. ” he corrected. (4) Figure 8 is corrected as shown in the attached sheet. 7. Corrected drawings for the list of attached documents (Figure 8) Detailed description of the invention in the specification to be amended in one copy and drawings (Figure 8) onwards
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Claims (1)

[Claims] A shadow mask disposed facing the fluorescent screen on the inner surface of the panel, a frame that fixes the outer peripheral surface of this mask, and a shadow that is fixed to the frame and has a thermal correction mechanism for correcting thermal expansion of the shadow mask. In a mask-type color picture tube, the shadow masks are stacked and bonded, one mask is a thick mask without a bridge, the other mask is thinner than the above mask and has a bridge, and both shadow masks are stacked and bonded. A shadow mask for a color picture tube, characterized in that a non-penetrating annular groove is provided around a welded joint of the color picture tube.