Mitsubishi Denki Kabushiki Kaisha

Tohoku University

Takeo Fujimura

Hiroshi Sugahara

Hiroshi Nasuno

Akira Haga

Tatsuo Uesaka

A cathode ray tube includes a panel having a fluorescent screen formed on an inner surface thereof, a stem, and a neck between the panel and the stem. An electron gun is supported by a supporting structure in coaxial alignment with the neck. The electron gun has a focusing electrode which includes a first cylinder and a second cylinder having a larger diameter than the first diameter. The first cylinder has a first opening which opens toward the stem and the second cylinder has a second opening which opens toward the panel. A conductive layer is deposited on the inner surface of the cathode ray tube and receives a high voltage. An annular holder is mounted to the supporting structure so that the annular holder surrounds the first cylinder in coaxial alignment with the focusing electrode. The annular holder is a first predetermined radial distance away from the first cylinder and a second predetermined axial distance from second cylinders. A plurality of springs are mounted on the outer circumferential surface of the annular holder. The springs extend to electrically contact the conductive layer and hold the annular holder so that the annular holder is in coaxial alignment with the longitudinal axis of the cathode ray tube.

Cathode ray tube having annular holding member

A display device with shadowmask CRT comprises an offset scanning means for imparting an offset to the scanning lines. The offset is a shift that gently changes the position of the scanning lines in the Y-axis direction. The offset scanning means imparts the offset in such a way that an interval between neighboring scanning lines is gently changed in accordance with a position in the X-axis direction. The scanning line offset produces some loss in resolution in the Y-axis direction, but since the area which Moire pattern is strongly present coincides with the area of good resolution, even if the offset is imparted in this area, sufficiently high resolution can be obtained.

Display device with shadowmask CRT

An apertured shadow mask is curved so that the curvature is concave on the back surface. The front surface generally follows the curvature of the back surface but has an undulating profile with ribs separated by troughs. The local thickness of the shadow mask is greatest in the ribs, and becomes gradually thinner toward the center lines of the troughs. The ribs and the center lines of the troughs have a zig-zag configuration. As a result, the front surface and neutral plane of the shadow mask have both convex and concave areas, which reduces localized doming.

Varible-thickness shadow mask for color cathode-ray tubes

In a color cathode-ray tube having a shadow mask disposed to face a phosphor screen and having apertures for passage of an electron beam, and a frame for reinforcing tile periphery of the shadow mask, a magnetic shield comprises strips of magnetic material each having a first end fixed to the frame and a second end disposed closer to the electron gun. Because of the elongated shape, the strips are magnetized easily only in the direction of their length. As a result, an external magnetic field parallel to the strips, and hence with the tube axis, is reduced or canceled. Moreover, if each strip is bent near its second end so that the second end is directed toward a horizontal plane containing the tube axis, an external magnetic field in the direction in which the second end is directed is enhanced. This will further reduce deviation of the electron beam path In the horizontal direction.

Color cathode-ray tube

A shadow mask type color CRT has a plurality of electron beam holes and a plurality of bridges for dividing the holes in the axial direction thereof. The electron beam projected from an electron gun passes the electron beam holes and stimulates the fluorescent screen behind the holes so as to cause the fluorescent screen to emit light. By the arrangement of the bridges in such a manner as to deviate the position of each bridge by the distance U from the intersection of an imaginary lattice, the defect such as fringes including a Moire on the screen caused by the regular arrangement of the bridges in the prior art is eliminated. The distance U is determined by a probability distribution function Q(U) which satisfies Moire regulating conditions. The shadow mask type CRT is used as a CRT commonly for two different systems using a different number of scanning lines.

Shadow mask type color CRT

Disclosed are a correction lens system used in the process of producing the fluorescent screen of a color picture tube in order to reduce the positional deviation (mislanding) of the landing point of an electron beam projected to form a picture from the position of the corresponding fluorescent substance in the mosaic of the fluorescent screen, and a method of manufacturing the correction lens system. The correction lens system includes a first correction lens provided with a smooth curved surface for correcting the optical path of exposure rays for producing the fluorescent mosaic and a second correction lens provided with a discontinuous curved surface. The optical path of the exposure rays is corrected to the desired optical path by the refraction of the rays through the first and second correction lenses. The discontinuous curved surface of the second correction lens is produced by dividing a lens having a smooth curved surface into a plurality of ribbon like elements along division lines which are parallel to each other in one direction, rearranging the ribbon like elements with the respective ends reversed without changing the original arranging order between adjacent ribbon like elements, and re-bonding the ribbon like elements at the respective cut surfaces.

Correction lens system used in production of fluorescent screen of color

A tensed shadow mask assembly for a cathode ray tube having a phosphor-deposited screen, which comprises a generally rectangular perforated plate having four corners and correspondingly four peripheral edge portions and a four-sided frame member similar in shape to the contour of the perforated plate having four fitting faces to which the respective peripheral edge portions of the perforated plate is rigidly secured while the perforated plate is held under tension. The perforated plate is generally scalloped with respect to the center thereof such that corners of the perforated plate occupy respective positions on one side away from an imaginary plane touching the center of the perforated plate and being perpendicular to the longitudinal sense of the cathode ray tube, while substantially intermediate region of peripheral edge positions between the neighboring corners occupy respective positions on the other side away from the imaginary plane.

Tensed shadow mask assembly

A display device which comprise a color cathode ray tube including a finely perforated shadow mask having a multiple of minute apertures defined therein in a predetermined pattern in a vertical direction relates to scanning lines depicted by electron beams, a horizontal deflecting unit for causing the scanning lines to sweep in a horizontal direction, a vertical deflecting unit for displacing the scanning lines of the electron beams in a vertical direction to permit the scanning lines to assume equally spaced relationship with each other, and a scanning line position adjusting unit for displacing every other scanning line from the total number of the scanning lines in the vertical direction in a quantity required to minimize the appearance of Moire pattern.

Display device using shadowmask CRT

A shadow mask for a color cathode ray tube has grooves formed in the curved surface in such a manner that the bending strength within the plane having a larger radius of curvature becomes greater than the bending strength within the plane having a smaller radius of curvature, thereby increasing the effective radius of curvature of the curved surface.

Shadow mask for color cathode ray tube shaped to minimize doming

A barium ferrite layer is disposed around an external surface of neck portion of a color cathode ray tube to have a magnetic easy axis radially of the longitudinal axis of the neck portion. An electromagnet is revolved around the layer to magnetically charge it so as to correct static convergence and color purity of three electron beams generated in the color cathode ray tube.

Growing community of inventors

Nagaokakyo, Japan

Takeo Fujimura