JPS6343242A - Color picture tube - Google Patents

Abstract

PURPOSE:To increase the strength of a shadow mask structure, by fixing a shadow mask comprising a low temperature expansion material with a frame comprising a high temperature expansion member through a spring-shaped metal piece to increase a number of welding points. CONSTITUTION:A shadow mask 11 comprising a low temperature expansion member is welded to a spring-shaped metal piece 13 at a welding point 14-a. Then, the shadow mask 11 is fixed at a prescribed position and the spring- shaped metal piece 13 is welded to a frame 12 at a welding point 14-b. With the arrangement, the deformation of the mask 11 caused by the thermal expansion of the frame 12 is adsorbed byre spring-shaped metal piece 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shadow mask type color picture tube, and particularly to a shadow mask structure thereof.

[Conventional technology]

-i The shadow mask structure consists of a shadow mask in which electron beam passage holes are provided in the form of slits or dots, a frame fixed at the skirt portion of this shadow mask, and a spring that engages this frame with the panel. It has become. An electron beam emitted from an electron gun passes through a shadow mask and hits a fluorescent surface to display a predetermined color image.

The electron beam transmittance of the shadow mask is low, and most of it (approximately 80 to 85%) hits the shadow mask and becomes heat, causing thermal expansion of the shadow mask, resulting in mislanding of the electron beam. Color purity deteriorates. This is generally called doming. On the other hand, similar to the shadow mask, thermal expansion occurs in the frame due to the impact of the electron beam, but since the frame has a larger heat capacity than the shadow mask, the change is more gradual than in the previous doming. This is also a factor in degrading the color purity of the color picture tube.

In order to suppress this deterioration of color purity, F, -N.

Shadow mask structures using low thermal expansion materials such as alloys and co-Fe alloys have been put into practical use. If a low thermal expansion material is used for the shadow mask, mislanding due to doming can be reduced, and this effect is remarkable in flat-face tubes in which the radius of curvature of the panel exceeds 1000 mm. - For example, in a 12-inch 90° flat-face tube, the shadow mask made of a low thermal expansion material reduces the maximum landing movement of the electron beam by 11% compared to conventional iron-based materials such as aluminum quilted low carbon steel.
It has been kept below 5. However, this value is the amount of movement at the middle part on the horizontal axis (70 m+a from the center).

Since low thermal expansion materials are expensive, using low-m tensile materials for both the shadow mask and the frame increases the cost of the color picture tube, and mass production is not easy due to problems such as weldability. Therefore, a shadow mask structure is used in which the frame is made of ordinary pure iron and only the shadow mask is made of a low-expansion material. This shadow mask structure has a 7145'5 tensile coefficient of 0 to 100℃ between the shadow mask and the frame.
There is a difference of about one order of magnitude. Therefore, if there are many welding points with the frame, as with conventional iron-based shadow masks, it will not work when the color picture tube is sealed or passed through an exhaust furnace in the manufacturing process, or when the color picture tube is overscanned. When this occurs, the shadow mask is pulled by the frame at the welding point of the skirt portion due to the difference in the amount of thermal expansion, resulting in partial deformation. This phenomenon is noticeable at the periphery of the shadow mask, resulting in mislanding of the electron beam and degrading color purity. Up until now, this has been dealt with by reducing the number of welding points between the shadow mask and the frame, such as only on the horizontal, vertical, and diagonal axes.

[Problem that the invention seeks to solve]

As described above, by reducing the number of welding points between the shadow mask and the frame, partial deformation of the shadow mask due to differences in thermal expansion can be suppressed. However, reducing the number of welding points weakens the vibration resistance and also weakens the mechanical strength of the shadow mask structure. Therefore, in the manufacture of color picture tubes, partial deformation of the shadow mask is likely to occur due to external forces other than heat, and even after the color picture tube is manufactured, there is a problem in that the screen shakes significantly due to external shocks and vibrations.

[Means for solving problems]

The color picture tube of the present invention has a shadow mask structure with a spring-like metal piece interposed at a fixed point between the shadow mask and the frame to absorb the difference in thermal expansion between the shadow mask and the frame.

〔Example〕

The present invention will be explained with reference to the drawings. FIG. 1 shows one embodiment of the present invention, in which a shadow mask 11 made of a low thermal expansion material and a frame 12 made of a high thermal expansion material are fixed via a metal piece 13 having an N-shaped cross section. FIG. 3 is a cross-sectional view of the structure.

Weld the shadow mask 11 and the spring-like metal piece 13 at a welding point 14-
After welding in step a, the shadow mask 11 and the spring-like metal piece 13 are welded to the frame 12 at a welding point 14-b using a jig that allows the panel and shadow mask structure to be spaced at a predetermined distance. As the material of the spring-like metal piece, for example, stainless steel or the like can be used.

Figures 2 (a), (b), and (c) show other embodiments of the present invention, in which the spring-like metal pieces are V-shaped in cross section (a>, (c) and L-shaped). The shape of these spring-like metal pieces can be arbitrary as long as it works to absorb the stretching of the shadow mask 11 due to thermal expansion of the frame 12. be.

〔Effect of the invention〕

As explained above, the present invention provides a shadow mask structure in which the shadow mask is made of a low thermal expansion material and the frame is made of a material with a larger coefficient of thermal expansion than the shadow mask.
The shadow mask and frame are fixed via a spring-like metal piece that absorbs the difference in thermal expansion.

Therefore, since the shadow mask is not pulled by the frame due to thermal expansion, the number of welding points can be increased and the strength of the shadow mask structure can be increased. Furthermore, since the skirt portion of the shadow mask is relatively free, deformation of the shadow mask due to impact in the tube axis direction is less likely to occur, and external vibrations are also less likely to be transmitted to the shadow mask.

[Brief explanation of the drawing]

1 and 2 (a>, (b), and (c) are embodiments of the present invention, and both are sectional views of essential parts of the shadow mask structure. 11...Shadow mask, 12... frame, 13
゜2], 22.23... Spring-shaped metal piece. Brown / Figure (a+ (J-n)
(c) I 2I ¥]

Claims (1)

[Claims] In a color picture tube having a shadow mask structure constituted by a shadow mask made of a low thermal expansion material and a frame made of a material having a larger coefficient of thermal expansion than the shadow mask, the shadow mask and the frame are fixed using a spring-like metal piece. A color picture tube characterized by the fact that