Kabushiki Kaisha Toshiba

Takuya Mashimo

Masatsugu Inoue

Norio Shimizu

Shinichiro Nakagawa

Hiroyuki Oda

Tohru Takahashi

Takeshi Nakayama

Nobuhiko Akoh

A shadow mask has a main mask and an auxiliary mask overlapped on the main mask. Electron beam passage apertures formed in the main mask and the auxiliary mask are arranged at given pitches in the direction of a major axis. Each electron beam passage aperture of the auxiliary mask is a communicating hole, which is formed of a smaller hole in that surface of the auxiliary mask which is in contact with the main mask and a larger hole opening in the opposite surface of the auxiliary mask. The smaller and larger holes of each electron beam passage aperture of the auxiliary mask have their respective central axes extending coaxially with each other and substantially at right angles to the surface of the auxiliary mask in the direction of the major axis.

Color cathode ray tube

A panel () of a vacuum envelope includes a substantially rectangular effective portion () having a substantially flat outer surface and also having a phosphor screenformed on an inner surface, and a skirt portion () provided along a peripheral part of the effective portion and extended substantially perpendicularly to the effective portion. A funnel () is bonded to the skirt portion. A reinforcing band for fastening the skirt portion is attached round an outer surface of the skirt portion. When a distance in a direction of the tube axis from a bonding part between the panel and the funnel to an end of the reinforcing band on the outer surface side of the effective portion is represented byand a distance in the direction of the tube axis from the bonding part to a central position of the outer surface of the effective portion is represented by, the reinforcing band is arranged to satisfy a &#x2267;0.9h.

Cathode-ray tube with a reinforcing band

A shadow mask is formed by lapping a main mask and an auxiliary mask on each other. The auxiliary mask includes a porous portion having electron beam passage holes, nonporous portions situated individually at the opposite ends of the porous portion, a pair of skirt portions extending individually from the nonporous portions and lapped on the skirt portion of the main mask, and second beads formed individually on the skirt portions and overlapping first beads of the main mask. The height or width of the first beads and the second beads in a superposed portion in which the main mask and the auxiliary mask are lapped on each other is differentiated from that of the beads in non-superposed portions outside the superposed portion.

Color cathode ray tube and method of manufacturing the same

An inner surface of the panel is formed to satisfy at least one of the following relationships: ZPH/LPH&lE;0.0050, and ZPV/LPV&lE;0.050 where LPH represents a distance from a center of the effective section to a long axis end of the effective section. LPV represents a distance from the center to a short axis end of the effective section, ZPH represents a fall of the effective section at the long axis end along the tube axis, and ZPV presents a fall of the effective section at the short axis end along the axis of the tube axis. At least one of each long side and each short side of a mask surface is curved such that a central portion thereof projects outwardly, and satisfies at least corresponding one of the following relationships: YML/LML&lE;0.015, and XMS/LMS&lE;0.015 where LML represents a distance from the short axis to each corner of an effective portion of the mask surface, LMS represents a distance from the long axis to each corner of the effective portion, YML represents a fall, along the short axis, between a point of each long side on the short axis and a corner of the long side, and XMS represents a fall, along the long axis, between a point of each short side on the long axis and a corner of the short side.

In a color cathode ray tube in which the external surface of an effective portion of a panel has a flat surface or a slight curvature, the shadow mask is set such that the layout distance between electron beam through hole array near the long side of an effective surface of the shadow mask is larger in the vicinity of the short axis than the layout distance at the center of the effective surface. Further, the layout distance becomes gradually smaller in direction away from the short axis, and thereafter, the layout distance changes to an increase. In the vicinity of the short side of the effective surface, the layout distance becomes equal to or larger than the layout distance near the short axis. Therefore, the curvature of the shadow mask and the electron beam through hole array are set in proper condition, and mislanding of beam landing due to deformation or oscillation of the shadow mask can be reduced. At the same time, howling of the phosphor screen can be minimized.

Color cathode ray tube having particular arrangement of electron beam through hole arrays

A shadow mask of a color cathode-ray tube has a substantially rectangular mask main body and a substantially rectangular mask frame fixed to a skirt portion of the mask main body. The mask main body has a curved effective surface formed with a large number of electron-beam passage apertures and opposing the phosphor screen, a non-aperture portion surrounding the outer periphery of this effective surface, and a skirt portion formed in a bent on the outer periphery of the non-aperture portion. The mask main body has a long axis extending in a horizontal direction and crossing with a tube axis, and a short axis extending in a vertical direction and crossing with both the tube axis and the long axis. The effective surface and the non-aperture portion of the mask main body are formed in a curved surface having a radius of curvature in the short axis direction. At each long side of the mask main body, each end portion of the short axis of the effective surface and the non-aperture portion is recessed from any other adjacent part, in a direction leaving from the phosphor screen along the tube axis. The radius of curvature in a short axis direction near the short axis of the effective surface and the non-aperture portion of the mask main body is smaller than the radius of curvature in the short axis direction at other parts.

Color cathode ray tube with curved shadow mask having central recessed portions

A color cathode ray tube having a reinforcing band, which constricts the outer periphery of a skirt portion of a vacuum envelope, arranged so as to fulfill a relation, b&gE;2.0a, where a is the distance between first and second planes along a tube axis, the first plane intersecting an end edge of the skirt portion and extending perpendicular to the tube axis, the second plane containing the central axis of stud pins supporting a shadow mask and extending perpendicular to the tube axis, and b is the distance between the first plane and a third plane along the tube axis, the third plane intersecting a side edge of the reinforcing band facing a vacuum envelope funnel.

Color cathode ray tube having reinforcing band arranged in a particular position relative to the position of stud pin

A shadow mask has a mask body and a substantially rectangular mask frame attached to a peripheral portion of the mask body. The mask body has a substantially rectangular curved effective surface opposed to a phosphor screen formed on an inner surface of a panel. The effective surface has a number of electron beam passage apertures. The effective surface of the mask body has a curvature in a direction of the long axis, which is set within a range of about 0 to 2&times;10,(1/mm) over an area from a center of the effective surface to a middle portion of the effective surface in the direction of the long axis. A curvature at a peripheral portion in the direction of the long axis is set to be greater than that at the middle portion. A curvature on the short axis in the direction of the short axis successively increases over a distance equal to at least two thirds of a distance between the center and an effective end of the short axis.

Color cathode-ray tube

In a color cathode ray tube comprising a panel with a substantially rectangular effective portion whose outside face is almost flat or slightly curved and whose inside face has a curvature in the direction of minor axis near the short sides of the portion, and a fluorescent substance screen having a substantially rectangular effective region formed on the inside face of the effective portion of the panel, the short sides in the outer circumference of the effective region of the fluorescent substance screen are projected toward the center of the effective region. This improves the flatness of images appearing on the fluorescent substance screen provided on the inside face of the effective portion in the color cathode ray tube with the outside face of the effective portion of the substantially rectangular panel being almost flat and the inside face having a curvature in the direction of minor axis at least near the short sides.

Growing community of inventors

Fukaya, Japan

Takuya Mashimo