Kabushiki Kaisha Toshiba

Tadashi Ite

Masatsugu Inoue

Norio Shimizu

Fujio Takahashi

Nobuhiko Akoh

Shoichi Yokoyama

A color cathode ray tube has a shadow mask. The shadow mask is composed of an almost rectangular mask body and an almost rectangular mask frame. The mask body has an effective surface facing a fluorescent screen, a non-aperture section surrounding the effective surface, and a bent skirt section formed on the periphery of the non-aperture section. The mask frame has a sidewall section provided on the skirt section of the mask body. In the shadow mask of such a configuration, a step section having a step in the direction perpendicular to the skirt section of the mask body is formed. With this configuration, the strength with which the curved surface of the effective surface of the shadow mask is enhanced, which prevents the color purity from deteriorating due to deformation and facilitates the formation of the shadow mask.

Color cathode ray tube having a shadow mask of improved strength

A shadow mask including a perforated portion that has a desired curved surface shape is obtained by pressing a flat mask having electron beam apertures. The press-molded perforated portion of the shadow mask is compressed in its thickness direction in a manner such that it is sandwiched between a first compression mold, having a convex surface that faces a concave surface of the perforated portion in which smaller holes of the electron beam apertures open and a plurality of projections on the convex surface, and a second compression mold, having a smooth concave surface that faces the convex surface of the perforated portion in which larger holes of the electron beam apertures open. In doing this, the perforated portion is locally compressed by means of the projections of the first compression mold, whereby a plurality of recesses are formed on the concave surface side of the perforated portion.

Growing community of inventors

Himeji, Japan

Tadashi Ite