Matsushita Electric Industrial Co., Ltd.

Matsushita Electronics Corporation

Shigeo Nakatera

Ryuichi Murai

Hiroshi Iwamoto

Tetsuro Ozawa

Tomohisa Mikami

Shin-ichiro Hatta

Masaki Kawasaki

Shinichiro Hatta

Takayuki Yonezawa

Mitsuhiro Otani

Masahiko Konda

Hideharu Omae

Kazuaki Hirabayashi

A cathode ray tube is provided, in which the flatness of a tension mask constituting a color-selection mechanism is maintained by a suitable stretching force, while with the tension mask, the influence of external magnetic fields, such as the terrestrial magnetism is suppressed, and the shifting of the electron beam is reduced. A tension mask made of a magnetostrictive material is used, the tension mask is stretched by a stretching force in a range maintaining the flatness of the tension mask, and the direction and strength of the stretching force are set such that vertical magnetic permeability of the tension mask increases, due to a magnetoelastic effect caused by the stretching force in the magnetostrictive material of the tension mask.

Cathode ray tube tension mask made of magnetostrictive material with compensation for terrestrial magnetism

A color cathode-ray tube apparatus having: a glass bulb including a face panel, a funnel, and a neck; a deflection yoke attached to the funnel to surround thereof; and a color-selection electrode disposed inside the face panel. A pair of degaussing coils are wound around the upper and lower portions of the glass bulb, respectively. A loop coil, which is disposed around the glass bulb between the color-selection electrode and the deflection yoke, includes: a first portion including two extending portions of the loop coil positioned over and below the glass bulb respectively, each center of the extending portions being substantially in a plane perpendicular to a tube axial of the glass bulb; and a second portion including two bent portions that are formed by bending right and left sides of an original form of the loop coil toward the neck.

Cathode-ray tube, cathode-ray tube apparatus, image display apparatus, and coil unit

A color cathode ray tube having a striped phosphor screen is provided, in which color displacements due to the tube axis (Z-axis) component of the terrestrial magnetism can be decreased at low cost. A positive temperature coefficient thermistor and a degaussing coil are connected in series to an AC power source (AC 100V) via a switch. A rectifier/smoothing circuit is provided in parallel to the positive temperature coefficient thermistor. When the switch is turned on, an ordinary degaussing process due to the AC attenuating magnetic field interlinked to the degaussing coil is performed, and the DC magnetic field in the Y-axis direction interlinked to the degaussing coil decreases the influence of the terrestrial magnetism in the tube axis direction (Z-axis direction).

Color cathode ray tube having DC magnetic field during degaussing process

In the structure of the present invention, there can be provided a cathode ray tube in which deviation in the trajectory of the electron beams by the leakage magnetic field from the mask frame ( ) is decreased by using a polygonal mask frame ( ) in which the relative magnetic permeability of longer side members ( ) out of two side members adjacent to each other at the joint portion of the mask frame ( ) is the same as or larger than the relative magnetic permeability of the other side members ( ). Thus, the significance of the present invention in industrial terms is large.

Cathode-ray tube

An inner magnetic shield is provided that reduces mislanding lengths due to electron beam distortion caused by external magnetic fields such as terrestrial magnetism, thereby reducing the occurrence of drifted or uneven color throughout an entire display screen. The inner magnetic shield is of a tube with a plurality of side surfaces, and is provided with at least one skirt ( ) that extends to the vicinity of a spanning member ( ) at a location where the inner magnetic shield is not in contact with a holding member ( ). The skirt ( ) is magnetically coupled with the spanning member ( ).

Cathode ray tube

An internal magnetic shield includes a pair of opposing long side walls ( ), a pair of opposing short side walls ( ), and an opening ( ) enclosed by these side walls in the center. The short side walls ( ) are provided with notches ( ) having a substantially home-plate shape. This configuration can reduce mislanding of an electron beam on the entire screen and easily balance the amount of mislanding due to geomagnetism in the tube-axis direction and in the horizontal direction perpendicular to the tube axis. As a result, a cathode ray tube capable of displaying images without displacement and unevenness of colors can be provided.

Inner magnetic shield and cathode-ray tube

A cathode ray tube including an internal magnetic shield in the shape of a hollow rectangular frustum including two long sides opposite to each other and two short sides opposite to each other, having an opening at its top and bottom attached to a mask and a frame. Each long side has a long side extension at a horizontal center located at the top of the internal magnetic shield where an electron beam enters the internal magnetic shield. The long side extensions enable the magnetic shield to reduce the deviation of an electron beam within the magnetic shield caused by an external magnetic field such as that caused by terrestrial magnetism.

Growing community of inventors

Hirakata, Japan

Shigeo Nakatera