Hitachi, Ltd.

Hitachi Media Electronics Co., Ltd.

Tomohiko Douken

Kikuo Tomita

Kazuo Kato

Takashi Sase

Fumio Tajima

Kazuyoshi Takizawa

Isao Kizuya

Shuzo Oshima

Hidefumi Antoku

Moritoshi Yoshida

Muneo Chiba

A CRT display device having a housing which includes a ground terminal and an opening, and a CRT (cathode-ray tube) which includes a shadow mask, a tube face of the CRT being irradiated with an electron beam through the shadow mask, thereby displaying a picture in a whole region of the opening; comprising an electrically conductive shield which confronts a part of the CRT display device which extends from a peripheral edge of the shadow mask to a peripheral edge of the tube face. The shield is connected to the ground terminal. The shield makes it possible to readily fabricate a CRT display device which can prevent alternating electric fields and electromagnetic waves from leaking out of the tube face without degrading the display performance of the CRT.

CRT display device

A horizontal synchronizing frequency f.sub.H and a vertical synchronizing frequency f.sub.V are detected, a moire adjusting signal (af.sub.H +bf.sub.V) is calculated, and then the position of displayed picture is alternatingly shifted in the horizontal direction by the distance proportional to (af.sub.H +bf.sub.V) every cycle of the vertical synchronizing frequency. Therein, a and b are coefficients depending on the CRT display device.

An electrostrictive revolution type ultrasonic motor includes a piezoelectric ceramic disk shaped stator and a rotor. The piezoelectric ceramic disk shaped stator has an eccentric movement via excitation by two phase pulse like voltage. The rotor is fitted around the circumference of the stator and is transmitted by a rotating torque due to the eccentric movement via frictional contact therebetween. The rotor is formed of a plastic material by injection molding to achieve a reduction of a size variation of the rotor and a stable contact with the stator. A high and stable rotating torque is thereby obtained with a reduced production cost. Further, a driving device for the ultrasonic motor which varies the frequency of a voltage applied to the ultrasonic motor in a stepped manner discriminates the magnitude of the corresponding motor currents and drives the ultrasonic motor with the frequency which causes the maximum motor current. In this manner, a simple structured and low cost driving device which operates at a high speed and at a high resolution with a high efficiency is achieved.

Ultrasonic motor and driving for the ultrasonic motor

A CRT display apparatus equipped with a control apparatus for performing a focusing control and a brightness control by changing a grid voltage by means of a potentiometer. The control apparatus includes a motor for driving the potentiometer in response to an externally supplied control signal, and the motor is mechanically arranged with the potentiometer in an integrated form. Both of a plurality of potentiometers and motors for driving the plural potentiometers are formed on the same substrate in an integrated form. Also, the control apparatus is molded with a flyback transformer for constituting the CRT display apparatus. The motor is constructed of either an ultrasonic motor, or a plastic geared motor.

CRT display apparatus

A first modulating wave current synchronized with a vertical sync signal and, having the same period as the vertical sync signal, is superposed on a horizontal deflection current caused to flow through a horizontal deflection coil of a CRT, and a second modulating wave current synchronized with a horizontal sync signal and, having the same period as the horizontal sync signal, is superposed on a vertical deflection current caused to flow through a vertical deflection coil of the CRT. The polarity and the amplitude of each of the first and second modulating wave currents are controlled by an adjustment circuit to correct a rotational distortion of a display area with respect to the displayed position of this area.

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Hitachi, Japan

Tomohiko Douken