Kabushiki Kaisha Toshiba

Shoichi Yokoyama

Kazumasa Hirayama

Fujio Takahashi

Yoshio Suzuki

Tatsuya Yamazaki

Maki Yoshida

Tadashi Ite

Akira Shoda

Osamu Takahashi

A laser beam is emitted form one side to a pair of square holes, while an electron gun assembly is being rotated on the tube axis of a color cathode-ray tube. The resulting diffraction pattern is sensed. When diffraction images included in the diffraction pattern are processed and a zero-order diffraction image and at least a first-order diffraction image are sensed in the pattern, the distance between the center of the zero-order diffraction image and the center of the first-order diffraction image is measured. The rotational position at which the distance is the smallest is sensed. The electron gun assembly is rotated to the position and held in place. Consequently, high-speed positioning is done with high rotation accuracy, which helps manufacture high-quality color cathode-ray tubes.

Method of and apparatus for sealing color cathode-ray tube

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.

Shadow mask having a curved surface with compressed, strengthening dents

A shadow mask of a color cathode ray tube includes a mask body having a rectangular effective area with a large number of electron beam apertures, a non-effective area surrounding the effective area, and a skirt portion extending from a peripheral portion of the non-effective area. The mask body has a belt-shaped reinforcing bead extending between two end edges of the mask body, which are in parallel to the vertical axis, through a central portion of the mask body and projecting from the effective area toward a phosphor screen. The reinforcing bead is formed such that a projecting height thereof is gradually decreased from the central portion of the mask body toward the two end edges of the mask body and such that the projecting height thereof at boundaries between the effective and non-effective areas becomes about not more than 2/3 the height of the reinforcing bead at the central portion of the mask body.

Color cathode-ray tube

Growing community of inventors

Hanyu, Japan

Shoichi Yokoyama