JPS62223949A - Color picture tube - Google Patents

Abstract

PURPOSE:To strengthen the spherical surface strength of the peripheral portion of a shadow mask with a pushing pressure caused by the insertion of a projecting part into a frame to prevent the local vibration of the shadow mask by providing the projecting part toward outside on the skirt portion of the shadow mask. CONSTITUTION:A shadow mask assembly for a color picture tube is constructed by inserting the skirt portion 7c of a shadow mask 7 made of a low thermal expansion material such as invar alloy or the like into the inside of a frame 10 and welding them at respective points on the horizontal, vertical and diagonal line. And projecting parts 12 toward outside are provided at least on the short sides of the skirt portion 7c, and the total length of the projecting parts is decided to be 35-85% of that of the short side. Thus when the skirt portion 7c is inserted into the frame 10, by the pushing pressure of the projecting parts 12 the spherical surface strength of the peripheral portion 7b of the shadow mask is increased. Therefore the local vibration of the shadow mask 7 due to the sound signal or the like can be prevented to eliminate the deterioration of the color purity.

Description

DETAILED DESCRIPTION OF THE INVENTION (Object of the Invention) (Industrial Application Field) The present invention relates to a shadow mask type color picture tube, and particularly to its shadow mask structure.

(Prior Art) In general, a shadow mask type color picture tube has a fluorescent screen formed on the inner surface of the face of the picture tube with light-emitting areas of each color, and a shadow mask having a curved effective surface with many through holes. It includes a frame that welds and supports the mask and shadow mask bodies at a plurality of locations, and an electron gun that generates a plurality of electron beams. A color image is displayed by passing the electron beam through a hole in the effective surface of the shadow mask so that the electron beam impinges on a predetermined light emitting area of the fluorescent screen. Furthermore, inexpensive iron is generally used as the material for the shadow mask and frame.

Due to the structure of such a color picture tube, approximately 80% of the electron beam collides with the shadow mask, causing thermal expansion of the shadow mask, which shifts the landing position of the electron beam onto the light-emitting area and causes deterioration of color purity. Various proposals have been made to suppress this so-called doming phenomenon. For example, Japanese Patent Publication No. 42-25446,
JP-A-50-58977 and JP-A-50-68
As disclosed in Japanese Patent No. 650, a proposal has been made to use a low thermal expansion material having a lower coefficient of thermal expansion than iron, such as an amber alloy containing iron and nickel as main components, for the shadow mask. By using a shadow mask made of a low thermal expansion material such as an amber alloy, the deterioration of color purity due to mislanding caused by the doming phenomenon became negligible.

Furthermore, since umber alloy is generally more expensive than iron materials, using umber alloy for the heavy frame as well as the shadow mask leads to a significant increase in cost. For this reason, it is desirable to use an amber alloy only for the shadow mask and to use iron for the frame. However, when using amber material for the shadow mask and iron material for the frame, if the entire shadow mask groove body is exposed to high temperatures (e.g. 400'C) during the color picture tube manufacturing process, the frame made of iron material will change due to thermal expansion. However, the shadow mask made of amber material hardly changes. Usually, the skirt part of a shadow mask is welded to the outside of the frame at multiple points, so if only the frame experiences thermal expansion and the shadow mask hardly changes, the entire frame will pull the shadow mask skirt part outward. The periphery of the effective surface of the shadow mask is plastically deformed. For this reason, in Japanese Patent Application No. 59-917931, shadow masks made of low thermal expansion materials such as Oite and Amber are welded together at multiple locations inside a frame made of iron, and the tensile force of the frame is transferred to the areas near the welded joints. It has been proposed to prevent plastic deformation of the shadow mask by limiting it to a narrow range.

On the other hand, a low thermal expansion metal such as an amber alloy containing 36% nickel is difficult to plastically work compared to iron due to its material properties, and therefore is difficult to press-form during the shadow mask manufacturing process. When this shadow mask is press-molded, deformation in which the spherical surface is depressed tends to occur in the periphery of the shadow mask, and this deformation is particularly large in the periphery of the short side of the shadow mask. Due to such deformation, the spherical strength of the peripheral portion of the shadow mask is weakened, and local vibrations are likely to occur in the deformed portion around the short side.

For example, when a strong audio signal is input when a color picture tube is in operation, vibrations from the speaker are transmitted to the shadow mask through the frame, causing local vibrations in the deformed part of the shadow mask.This local vibration is caused by Particularly large bar rsersv*sm;y in the periphery.

(Problems to be Solved by the Invention) As described above, by using a shadow mask made of a low thermal expansion material such as an amber alloy, mislanding due to doming can be almost sufficiently suppressed. However, localized imaging tends to occur due to the deformation of the short side that occurs during shadow mask molding, and, for example, vibrations from a speaker during operation of a color picture tube do not cause local vibrations in the deformed portion of the shadow mask. When this local vibration of the shadow mask occurs, the relative positional relationship with the phosphor changes over time, so the landing position of the electron beam also changes over time, causing deterioration of color purity. An object of the present invention is to prevent deterioration of color purity due to local vibration of a shadow mask of a color picture tube.

[Structure of the invention]

(Means for Solving the Problems) The present invention has been made to solve the above problems.
Since the frame is made of a metal with a small thermal expansion coefficient, it is necessary to create an outward protrusion on the skirt on the short side of the shadow mask when pressing, and the total length of this protrusion is set relative to the total length of the short side. 35% or more and 85% or less. Further, it is effective to set the protrusion width of the protrusion to 0.2# or more and 1.0# or less.

(Function) By providing a protrusion that protrudes outward on the skirt on the short side of the shadow mask, the length between the short sides of the protrusion on the shadow mask skirt can be reduced relative to the length between the short sides of the frame. Part 1 has a protrusion when inserting the shadow mask into the frame because the length is the same or a little longer.
The mask skirt part is pushed inward by the protrusion, and the force of the shadow mask deformation part moves toward the screen, increasing the spherical strength and making it difficult for local vibrations to occur. From this effect,
Deterioration of color purity caused by local vibrations caused by sounds or the like can be prevented.

(Example) Hereinafter, one example of the present invention will be described in detail using the drawings. As shown in Fig. 3, the shadow mask type color picture tube consists of an envelope consisting of a panel (■) and a funnel (■), an electron gun (3) is housed in the small diameter portion of the funnel (■), and a coating is applied to the inner surface of the panel. The phosphor G) that emits light in three colors plays a role of color selection for the three electron beams emitted from the electron gun It is composed of a shadow mask structure (5). The shadow mask structure (
5) has a large number of slit-shaped or circular pores for electron beam passage, and has a shadow mask effective part (7a) which is the main surface, and a shadow mask outside the effective part (7a), as shown in FIG. The non-porous shadow mask peripheral part (7b), the peripheral part (7
In contrast to b), the shadow mask skirt part (7C) is bent at a right angle, has a relatively strong structure, and is a holder fixed to the frame 0Φ in order to attach the shadow mask (7) at multiple locations at internal intervals. It is composed of (6). In a color picture tube having such a configuration, FIG. 1 (2) shows an example of preventing local 1-phase movement when an amber alloy is used for the shadow mask (7), which is applied to the present invention. A schematic cross-sectional view of the shadow mask structure in the horizontal axis direction, υ shows a schematic plan view. 1st
In Figures (2) and υ, the shadow mask (7) and the frame (1Φ) are welded together on the horizontal, vertical, and diagonal axes indicated by the X mark.The shadow mask skirt (7)
C) is provided with a projection 02) which projects outwardly in the middle of the welded connection point on the short side. The protruding part θ is connected to the shadow mask skirt part (
7C), so that when the shadow mask ■ is inserted into the frame 0, the protruding portion 02) and the frame 0Φ come into contact, and the shadow mask skirt portion (7C) is formed as shown in ■ in Fig. 2 (2). The force shown pushes the shadow mask ω inward. Therefore, the force (■) acts on the peripheral part (7b) of the shadow mask, and the shadow mask ω changes from the position shown by the solid line to the position shown by the dotted line in the figure.
Ru. Due to the above action, the peripheral part of the shadow mask (7b)
Because the force (2) is constantly moving in the deformed part, the spherical strength increases and local vibrations become less likely to occur. Generally, at the welded joint location on the horizontal axis, the outer diameter of the shadow mask is the same as or slightly larger than the inner diameter of the frame. For this reason, near the welded joint (=j) on the horizontal axis, the same force as shown in ■ and ■ in Figure 2 (2) is acting before the protrusion is provided, and the welded joint near the short side Local vibration is less likely to occur than other parts.Therefore, the shadow mask skirt part (7C
) By providing a protrusion θ on the shadow mask, it is possible to suppress local vibrations around the short side, where deformation is most likely to occur when pressing the shadow mask, and increase the spherical strength of the short side, which improves the sound quality, etc. Deterioration of color purity due to vibration can be prevented.

In fact, in a 21-inch 90° deflection color picture tube,
When four protrusions with a protrusion width of 0.8# and a length of about 90 mm are provided between the center part and part of the corner of the skirt part on the short side of the shadow mask, local vibrations of the shadow mask due to sound vibrations are caused by electron beams. The change in landing position was improved by 40%. Further, in this embodiment, the case where the protrusion part 0 is provided on the short side skirt part (7C) of the shadow mask has been described, but even when the protrusion part is provided on the long side skirt part (7C), as shown in FIG. ) has the same effect as the movements of ■ and ■ shown in ). However, since the deformation of the shadow mask (2) during press molding usually occurs the most around the short side, the improvement effect is greatest when the protrusion 0 is provided on the short side skirt (IC). Also, in the shadow mask having the shape shown in FIG. 20, the shadow mask skirt portion (IC) is similar to the shadow mask having the shape shown in FIG.
■ By providing a protrusion (to) on.

(2) works to increase the spherical strength of the peripheral portion (7b) of the shadow mask.

Note that even if a protrusion is provided between the center of the skirt on the short side of the shadow mask and a part of the corner, there is no protrusion near the corner of the short side because there is enough space between the shadow mask and the frame. Compared to the case where a shadow mask is inserted into a frame, the workability is not deteriorated at all. Regarding this workability, the total length of the protrusion should be 85% of the total length of the short side.
If the length is as follows and no protrusion is provided near a part of the corner, there will be no problem, but if the length exceeds 85% of the short side, the workability of inserting the shadow mask into the frame will deteriorate significantly.

Furthermore, with respect to local vibrations of the shadow mask, a sufficient suppressing effect cannot be obtained unless the total length of the protrusion is 35% or more of the total length of the short side. For example, in the case of the aforementioned 21-inch color picture tube, the total length of the protrusion is approximately 60% of the total length of the short side.
It has become. The protrusion width of the protrusion should be 0.2 in order to sufficiently improve the local vibration of the shadow mask.
8 or more is necessary, and if it exceeds 1 s, the force that pushes the skirt portion of the shadow mask inward when inserting the shadow mask into the frame is too strong, causing deformation of the shadow mask. Therefore, the protrusion width is 0.2 seconds or more and 1 m.
The following is good.

In the above embodiment, four protruding parts are provided outwardly between the center part of the skirt part on the short side and a part of the corner. However, as another embodiment, as shown in FIG. In the case where six protrusions are provided toward the outside at the center of the skirt portion (7C) on the short side and between the center and a part of the corner, or as shown in Fig. 6, the skirt portion (7C) on the short side Even if the protruding portion (32) is provided outward from the center of the skirt portion (7C) and the middle of a part of the corner to the middle of the center of the same short side and a part of the corner on the opposite side, the above-mentioned It is possible to obtain 1q of effects similar to the above, and to achieve the object of the present invention.

〔Effect of the invention〕

As described above, according to the present invention, by providing a protruding portion on the skirt portion of the shadow mask to prevent local vibrations caused by shadow mask audio signals, etc., it is possible to improve workability and eliminate significant cost increases and design changes. Deterioration of color purity due to local vibration of the shadow mask can be prevented.

[Brief explanation of drawings]

Fig. 1 (Q and 0 are a schematic cross-sectional view and a schematic front view showing one embodiment of the present invention, Fig. 2 is a schematic diagram of a shadow mask showing the principle of local imaging countermeasures, Fig. 3 is a shadow mask FIG. 4 is a partially cutaway perspective view showing a schematic configuration of a color picture tube having a color picture tube, FIG. 4 is a partially cutaway perspective view showing a shadow mask structure, and FIGS. 5 and 6 are shadow mask structures showing other embodiments. This is a schematic front view of: ■...Panel, ■...) 7-channel ■...Electron gun, (a)...Phosphor 0...Shadow mask structure, ■...Pore■・・・
・Shadow mask effective part■...Shadow mask peripheral part (9)...Shadow mask skirt part 0Φ...Frame Oo...Protruding part of holder 0 Agent Patent attorney Norihiro Chika Ken Yudo Dai Hu Dianfu<b) Figure 4 Figure 5 Figure 6

Claims (3)

[Claims] (1) consisting of a rectangular shadow mask consisting of a main surface having a large number of through holes and a skirt section bent around the periphery of this main surface, and a rectangular frame supporting the shadow mask with the skirt section, The shadow mask is made of a metal having a coefficient of thermal expansion smaller than that of the frame, and the color picture tube includes a shadow mask structure in which the shadow mask is welded to the inside of the frame at a plurality of locations. A color picture tube, characterized in that a protrusion projecting outward is provided on at least the short side of the skirt portion, and the total length of the protrusion is set to 35% or more and 85% or less of the total length of the short side. (2) The color picture tube according to claim 1, wherein the protruding portion is located between the center portion and the corner portion on at least the short side of the skirt portion of the shadow mask. (3) The protrusion has a protrusion width of 0.2 mm or more and 1.0 m.
2. The color picture tube according to claim 1, wherein the color picture tube is less than m.