Hitachi, Ltd.

Hitachi Media Electronics Co., Ltd.

Kikuo Tomita

Tomohiko Douken

Kazuo Kato

Takashi Sase

Kazuyoshi Takizawa

Isao Kizuya

Kazuyoshi Sasaki

Shuzo Oshima

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

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 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.

Image display apparatus with a deflection circuit having function for

A comparator detects a set-up voltage superimposed on a video signal. The detected set-up voltage is input to a timing information detection circuit to detect the display start timings and display end timings of a video signal or a single line and a single picture, respectively. Then, the detected timing information is input to an arithmetic operation means to determine the display period of the video signal for the single line and single picture and further determine the ratios thereof with respect to predetermined reference values. Further, the amounts of dislocation of the timing relationship between the display periods for the single line and single screen and a horizontal synchronizing signal and vertical synchronizing signal from predetermined reference relative relationships are determined, respectively. A picture display area adjustment means corrects the amplitudes of a horizontal deflection current and vertical deflection current corresponding to each other in accordance with the ratios determined by the arithmetic operation means, respectively and the level or phase of the horizontal deflection current and the level of the vertical deflection current corresponding to each other in accordance with the dislocations of the relative timing relationships of the determined display periods, respectively. As a result, even if an input video signal has a different timing specification, the size and position of a picture display area can be automatically adjusted to predetermined references.

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Hitachiota, Japan

Kikuo Tomita