Hitachi, Ltd.

Hitachi Device Engineering Co., Ltd.

Hitachi Mizusawa Electronics Co.

Hitachi Mizusawa

Kazuo Majima

Shoji Shirai

Hidemasa Komoro

Kouji Kitou

Masakazu Fukushima

Michitaka Ohsawa

Soichi Sakurai

Nobutaka Okuyama

Masao Obara

Isao Yoshimi

Yukihiro Izumida

Hiroki Oguro

Yoshio Yoshiwara

Kouji Fukuma

Minoru Furuya

Yoshiaki Takahashi

Atsushi Yoshida

Masaaki Yamauchi

Toshio Asano

Hiroshi Takano

Jun Mochizuki

Mamoru Ikeda

Daisuke Katsuta

Kinuyo Hagimae

Masao Taniguchi

Akio Yamaguchi

Teruo Matsuo

Tohru Sano

Masakatsu Horiuchi

A cathode-ray tube apparatus capable of reducing a high frequency electric field radiated from the deflection yoke and the deflection and high voltage circuit to the outside of the cathode-ray tube apparatus. Mounted on the deflection yoke or on the cathode-ray tube are an induction coil for generating a pulse voltage opposite in polarity to a high pulse voltage applied to the h and an electric field cancellation electrode made of a conductive wire to which the opposite polarity pulse voltage is applied. When the opposite polarity pulse voltage is applied to the electric field cancellation electrode, the electric field cancellation electrode radiates an electric field opposite in polarity to the high frequency electric field radiated from the deflection yoke to the outside of the cathode-ray tube apparatus to reduce the intensity of the high frequency electric field.

Cathode-ray tube apparatus and yoke

An apparatus for identifying positions of pixel defects on a display screen, such as a cathode-ray tube or a liquid crystal display, operates to pick up an image signal of a display screen representing a predetermined image with an imaging camera, shift the image signal of the imaging camera by one pixel in one and another directions with respect to the display screen, and obtain a difference of a signal level between a defective portion and a normal portion on the screen, based on the signals obtained when the image signal of the imaging camera is shifted in one and another directions. The apparatus also serves to calculate a relative inclination between the imaging camera and the display screen for obtaining a difference of a signal level between a defective portion and a normal portion of each pixel. The results make it possible to clearly identify the difference of the signal level between the defective portion and the normal portion.

Method and apparatus for checking defect on display screen

In a shadow mask type color cathode-ray tube, the coercive force of the shadow mask frame, internal magnetic shield, shadow mask and reinforcing band is limited to a specific value when they are magnetized at specific magnetic field, in order to eliminate any adverse influences of environmental magnetic field.

Color cathode-ray tube

An electron gun for a color picture tube has at least a cathode, a control grid, an accelerating grid, a focus grid and an anode, each of which has three apertures aligned in line. The focus grid and the anode made of elongated plates serves as main lens electrodes, and the apertures of the focus grid and the anode constitute a main lens assembly. The three apertures of each of the elongated plates has a central aperture defined by two first curves arcuated outward, two side apertures each of which is defined by a second curve as an inner half arcuated inward and a third curve as an outer half arcuated outward, the first and second curves being less arcuated than the third curve. The three apertures are aligned such that the major axes thereof are parallel to a shorter axis of the elongated plate and are located at equal intervals. The three apertures are spaced apart from each other through corresponding bridge portions. The third curve of each of the two side apertures is apart from a corresponding end of the elongated plate along the longitudinal direction.

Electron gun for color picture tubes having uniquely formed lens

An electron gun for a color picture tube consists of a triode that generates a plurality of electron beams and a main lens which focuses and converges the electron beams. The main lens can be divided into two types, i.e., a pair of bi-potential focusing electron lenses and a combination of the bi-potential focusing electron lens and a uni-potential focusing electron lens. The electrodes constituting the main lens have apertures for permitting the transmission of a plurality of electron beams. The center axes of apertures are deviated toward the center axis of the embodiment of electron gun away from the axes of initial paths of the electron beams emitted from the triode.

Electron gun structure for converging electron beams

An electron gun for color picture tube has a focusing electrode and an anode electrode respectively formed of an oval thick plate for forming main focusing lenses. Each of the focusing electrode and anode is formed with three electron beam passing holes arranged in line in a direction orthogonal to a tube axis of the picture tube. The focusing electrode and the anode are arranged to oppose each other with a distance therebetween such that their corresponding electron beam passing holes oppose each other. When predetermined voltages are applied to the focusing electrode and anode, main lenses are formed between the respective opposing holes. As viewed along the tube axis, the in line electron beam passing holes of each electrode include two outer electron beam passing holes each having an outer half in the form of a semi-circle and an inner half in the form of a semi-ellipse having a diameter of the semi-circle as its major axis and a central electron beam passing hole in the form of an ellipse having a major axis which is equal to the diameter of the semi-circle and which extends in a direction orthogonal to the direction of arrangement of the electron beam passing holes.

Electron gun for color picture tube with electrostatic focussing lens

An electron gun used in a color picture tube having means for emitting three electron beams toward the fluorescent screen, and main lenses for focusing the electron beams on the fluorescent screen. The main lenses are constituted by two envelopes spaced out from each other and adapted to surround the electron beams, and two electrode plates located on the confronting end surfaces of the envelopes and provided with three apertures aligning on a line for conducting the three electron beams. At least one of the two electrode plates is recessed relative to another electrode plate and disposed inside the envelope, and the recessed electrode plate is structured such that non-rotational symmetry of the lens caused by the recess of the electrode is corrected.

Electron gun for color picture tube

Growing community of inventors

Mobara, Japan

Kazuo Majima