Kabushiki Kaisha Toshiba

Mitsuaki Yamazaki

Yasuhisa Ohtake

Hiroshi Tanaka

Seiji Sagou

Seiji Sago

Yasushi Magaki

Sachiko Muramatsu

A color cathode ray tube has a face panel, a phosphor screen formed on an inner surface of the face panel, an electron gun for emitting electron beams toward the phosphor screen, and a shadow mask arranged between the electron gun and the face panel to oppose the phosphor screen. The shadow mask has a large number of electron beam apertures through which the electron beams pass. Each of the electron beam apertures has a small opening open to a first surface of the shadow mask and a large opening open to a second surface of the shadow mask and communicating with the small opening. The large opening has a center axis and a diameter larger than that of the small opening. A wall surface of the shadow mask which defines the large opening of each of the electron beam apertures located at a peripheral portion of the shadow mask includes a bulged portion. The bulged portion is located on the opposite side of a mask center with respect to the center axis of the large opening, and is bulged outward in the radial direction.

Color cathode ray tube and method of manufacturing shadow mask

An aperture pattern printing plate for manufacturing a shadow mask having an opaque layer form in parts on a surface of a transparent plate. The parts of the opaque layer corresponding to apertures in an effective area of the shadow mask. The opaque layer projecting from the transparent plate, and having a thickness of 30 to 50 .mu.m.

Aperture pattern printing plate

A method of manufacturing an aperture pattern printing plate in a limited number of steps using only one original printing plate. The method produces transparent portions on a portion of the printing plate corresponding to a non-effective area of a shadow mask, and opaque portions on a portion of the printing plate corresponding to an effective area of a shadow mask. The method has the steps of bringing a transparent plate having an unexposed transparent photosensitive layer formed on at least one of its principal surfaces into contact with an original plate having opaque areas corresponding to apertures in a to be constructed shadow mask. A first exposure is performed on the photosensitive layer through the original plate. The photosensitive layer is then developed to render exposed portions of the photosensitive layer opaque. These opaque portions are then etched away. A portion of the photosensitive layer corresponding to the non-effective area of a shadow mask is then covered to prevent exposure. A second exposure of the photosensitive layer is then performed; thereby achieving exposure of only the portion of the photosensitive layer corresponding to an effective area of a shadow mask. The photosensitive layer is then developed to render the exposed portions of the photosensitive layer opaque. By etching away the opaque portions produced after development of the first exposure, air passages are produced on the whole surface of the transparent plate.

Growing community of inventors

Fukaya, Japan

Mitsuaki Yamazaki