JPS6221215B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a shadow mask type color cathode ray tube,
In particular, the present invention relates to an improvement in a shadow mask holding structure for holding and fixing a shadow mask to the inner surface of a panel.

As is well known, in a shadow mask type color cathode ray tube, a shadow mask assembly consisting of a shadow mask and a frame is removably disposed on the inner surface of the panel by a shadow mask holding structure. Generally, a bimetal spring is used as the shadow mask holding structure, one end of which is fixed to the shadow mask assembly, and a panel hole provided at the other end is engaged with a panel pin implanted on the inner surface of the panel, thereby controlling the temperature of the shadow mask. When the shadow mask assembly rises due to the impact of the electron beam, the shadow mask assembly is moved toward the screen to compensate for thermal expansion of the shadow mask assembly.

Observing the thermal expansion of the shadow mask assembly, after the color cathode ray tube starts operating, the temperature of the effective surface of the shadow mask increases due to the impact of electron beams. In this initial state, the temperature of the end surface (mask skirt portion) has not increased, so only the effective surface of the shadow mask thermally expands and assumes the convex cross-sectional shape shown in FIG. This is generally called doming. Next, the end surface 1a of the shadow mask 1 and the frame 2 also expand due to heat conduction from the effective surface 1b of the shadow mask 1, and the entire shadow mask assembly 3 expands as shown in FIG.
The convex deformation of is reduced. In addition, the shadow mask 1 is moved to the panel 5 by the action of the bimetal spring 4.
The shadow mask 1 is brought closer to the screen direction to correct thermal expansion of the shadow mask 1 and prevent mislanding. In addition, in FIG. 2, 6 indicates a panel pin.

However, since the temperatures of the shadow mask end surface 1a and the frame 2 do not rise to the same temperature as the shadow mask effective surface 1b, and because the bimetal spring 4 acts in a direction to prevent the shadow mask end surface 1a and the frame 2 from expanding, a steady state is reached. However, doming as shown by the dotted line in FIG. 1 is not resolved and the state does not return to its original state. For this reason, mislanding could not be completely prevented.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and provides a shadow mask type color cathode ray tube that can perform correction to bring the thermally expanded shadow mask closer to the screen direction, eliminate doming of the shadow mask, and completely prevent mislanding. The purpose is to

Hereinafter, the present invention will be explained with reference to illustrated embodiments.

FIG. 3 is a perspective view of essential parts showing an embodiment of a shadow mask type color cathode ray tube according to the present invention.
The shadow mask holding structure 10 includes a plate-shaped metal body 1
A bimetal structure 14 in which bar-shaped metal bodies 12 and 13 having a coefficient of thermal expansion smaller than that of the metal body 11 are bonded on opposite diagonals to each other on both sides of the metal body 11, and a shadow mask assembly 3 welded to the edge of this bimetal structure 14. It consists of a spring piece 15 of a metal band elastically extending from the side wall side to the inner surface side of the panel. The wing portion 16 of the bimetal structure 14 is fixed to the shadow mask assembly 3, and the panel hole 18 provided in the end portion 17 of the spring piece 15 is fitted into the panel pin 6 implanted in the panel 5.

Next, the function of the bimetal structure 14 will be explained with reference to FIG. When the bimetal structure 14 formed as described above is fixed at one end to the fixing plate 19 and heated, the metal body 1 is separated from the metal bodies 12 and 13 as described above.
1 has a larger coefficient of thermal expansion, the end of one metal body 12 at the free end of the bimetal structure 14 is displaced in the upward direction of arrow B around the center line A, and the end of the other metal body 13 is It is displaced about the center line C in the downward direction D of the arrow, contrary to the above. Therefore, the free end undergoes twisting deformation in the direction of arrow E.

Therefore, as shown in Fig. 3, the bimetal structure 1
In addition to the operation of correcting the landing error of the electron beam due to the expansion of the effective surface 1b of the shadow mask due to thermal expansion by moving the shadow mask 1 toward the screen, the shadow mask holding structure 10 having As a result, the shadow mask effective surface 1b undergoes convex deformation (doming) as shown by the dotted line in Fig. 5.
is completely removed.

As is clear from the above description, according to the shadow mask type color cathode ray tube according to the present invention, the shadow mask holding structure brings the thermally expanded shadow mask closer to the screen and is twisted in a direction that prevents doming of the shadow mask, so that mislanding is prevented. It is completely prevented and the quality is excellent.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the thermal expansion state of a shadow mask, FIG. 2 is an explanatory diagram showing a thermal expansion correction state using a conventional shadow mask holding structure, and FIG. 3 is a shadow mask used in a shadow mask type color cathode ray tube according to the present invention. FIG. 4 is a perspective view showing an embodiment of the holding structure, FIG. 4 is an explanatory diagram of the operating principle of the bimetal structure, and FIG. 5 is an explanatory diagram showing a thermal expansion correction state by the shadow mask holding structure shown in FIG. 3. 1... Shadow mask, 2... Frame, 3...
...Shadow mask assembly, 5...Panel, 6...
Panel pin, 10...Shadow mask holding structure,
11, 12, 13...metal body, 14...bimetal structure, 15...spring piece, 16...wing part, 18...
...Panel hole.

Claims (1)

[Claims] 1. In a shadow mask type color cathode ray tube in which the shadow mask assembly is supported on the inner surface of the panel via a shadow mask holding structure which has one end fixed to the shadow mask assembly and the other end fitted to a panel pin implanted in the panel, the shadow mask holding structure In order to bring the thermally expanded shadow mask closer to the screen direction of the panel and to twist it in a direction that prevents doming of the shadow mask, rod-shaped metal bodies with a coefficient of thermal expansion smaller than that of the metal body are placed on opposite sides of the plate-shaped metal body in opposite diagonal directions. A shadow mask-shaped color cathode ray tube with a bimetal structure bonded to the top.