Hitachi, Ltd.

Hitachi Medical Corporation

Hisakatsu Kiwaki

Masahiko Ibamoto

Kiyoshi Nakamura

Hiroshi Narita

Yoshimitsu Onoda

Hiroshi Okubo

Masato Suzuki

Yoshio Sakai

Hiroshi Sato

Hiromi Inaba

Shotaro Naito

Kazuo Kaneko

Takeki Ando

Toshiaki Kurosawa

Yoshio Tsutsui

Takanobu Hatakeyama

Akiteru Ueda

Kyozo Tachibana

Hiroaki Ishikawa

Shigeru Kuriyama

Akio Sasaki

Tatsuo Horie

Akira Kimura

Shozuchi Miura

Fumio Ogata

Jinichi Toyama

Katsuaki Suzuki

Tetsuji Hirotsu

Hajime Nakashima

Kiyoteru Kuwabara

Syozi Kasai

Kayo Shimada

An X-ray generator with current measuring device has an X-ray tube, a power supply unit for feeding high voltage to the X-ray tube, a high voltage cable for connecting the X-ray tube and power supply unit. The high voltage cable is comprised of a core conductor, an insulating layer surrounding the core conductor and a covered shield surrounding the insulating layer and the covered shield is disconnected near one end of the cable connected to the X-ray tube so as to be divided into a major shield portion adjacent to the power supply unit and a minor shield portion adjacent to the X-ray tube. An insulating member is provided for electrically insulating the major and minor shield portions, and a magnetic sensor sensitive to a magnetic field generated by a current flowing through the high voltage cable is positioned around the minor shield portion. The X-ray generator can measure the X-ray tube current accurately and readily under electrical insulation.

X-ray generator with current measuring device

From the peripheral velocity v.sub.M of a driving wheel and vehicle velocity v, the changing rate .DELTA.v.sub.s /.DELTA.t of the relative velocity v.sub.s therebetween with respect to time is obtained. The changing rate .DELTA.f/.DELTA.t of the traction force f produced in the driving wheel at that time is obtained from a detected armature current of a motor driving the driving wheel. A driving torque produced by the motor is so controlled as to be decreased when polarities of the changing rate in the relative velocity and that in the traction force are different from each other.

Control system for maintaining traction of rolling stock

In an elevator wherein an elevator cage is repeatedly run among a plurality of floors by controlling a cage driving motor in accordance with a velocity command; a floor arrival error involved when the elevator cage has arrived at the floor is detected, and the velocity command for the subsequent operation is corrected in accordance with the floor arrival error, thereby to enhance the floor arrival precision.

Elevator control apparatus

In an apparatus having a saturable magnetic core, a control winding wound on the magnetic core and supplied with a D.C. voltage in accordance with a desired phase angle, and an output winding wound on the magnetic core and supplied with an A.C. voltage through a load resistor, whereby the firing phase of a thyristor is controlled by a voltage across the load resistor, an additional winding is wound on the saturable magnetic core to detect the saturation of the saturable magnetic core by a rapid drop of a voltage across the additional winding. When the saturation is detected, the magnitude of the A.C. voltage applied to the output winding is increased. The phase angle characteristic of the magnetic phase shifter is determined under a low voltage condition prior to the saturation of the magnetic core, and after the saturation a high voltage is applied to the load resistor.

Magnetic amplifying apparatus

The two secondary windings of a transformer the primary winding of which is connected to an AC power supply are each provided with a controlled rectifying circuit. The DC sides of the rectifying circuits are connected in series to supply power to DC motors. One of the secondary windings is detachably connected with a capacitor bank. The capacity of the capacitor bank is selected so that the power factor of the converter can be improved to a satisfactory value when the two rectifying circuits are both controlled to produce output voltages. The capacitor bank becomes connected in response to the fact that the current in the primary winding of a transformer has arrived at a predetermined value.

Power factor improving apparatus for power converter

A direct current detecting device is disclosed in which two pairs of saturable cores are provided so as to enclose a conductor carrying a direct current to be measured. On each of the saturable cores, a bias winding, a feedback winding and an output winding are wound. First and second output circuits are provided, each connected with a pair of output windings and each including two closed current paths consisting of the output winding, a common load, a common A.C. supply source and a diode. The diodes function to allow the greater one of current flows of the two closed paths to be passed through the common load. An amplifier is connected to receive the difference between output signals of the two output circuits. The output of the amplifier is supplied to the feedback winding whereby the magnitude of the feedback current becomes a function of the magnitude of the current flowing through the conductor.

Direct current detecting device using saturable reactors

A system for detecting an output of a controllable semiconductor device includes a controllable semiconductor device, a magnetic amplifier to which an output of the semiconductor device is fedback to control the semiconductor device, and a monitor device for monitoring an output of the magnetic amplifier. The monitor device serves for determining that the output of said semiconductor device exceeds a predetermined level, when the output of the magnetic amplifier is in a remanent output region of the magnetic amplifier.

System for detecting output of controllable semiconductor device

A magnetic phase shifter control system comprises a magnetic phase shifter for producing an output signal in accordance with a control command at a predetermined amplification degree, a circuit for suppressing the output signal of the magnetic phase shifter to a level lower than a predetermined level on command, and a circuit for reducing the amplification degree of the magnetic phase shifter when the suppressing circuit is operative, whereby a delay for response due to a dead time which the magnetic phase shifter inherently has is eliminated.

Magnetic phase shifter control system

In cases of subjecting an electric motor operated vehicle to electric braking, regenerative braking is performed during the first stage of the braking operation thereby supplying the armature current to the battery as a load, and a plugging operation is performed during the last stage thereof to complete the braking operation, whereby the efficiency of operation is enhanced by conserving the armature current to extend the traveling distance of the vehicle per charge of the vehicle battery, and the generation of excessive heat in the motor is suppressed.

Braking control apparatus for an electric motor operated vehicle

In a chopper control device in which a magnetic phase shifter is used for providing chopper turn-on and turn-off signals, an external magnetic field is applied to the core of the magnetic phase shifter so as to carry out the notching control of a motor by regulating the residual phase angle of the output of the magnetic phase shifter.

Chopper control device

There is provided an exciter arrangement for generators comprising an internal combustion engine, a generator coupled with the internal combustion engine and driven thereby, an exciter for regulating excitation of the exciter, a detector for detecting a value responsive to a revolution number of the internal combustion engine, and a controller for controlling the exciter in response to an output of the detector.

Exciter arrangement for generators

A signaling system for cars having wheels adapted for running along a track, in which a signal wire is disposed to extend along the track, a pantograph is provided on each car to make sliding engagement with the signal wire, and a detector apparatus responsive to the sliding movement of the pantograph along the signal wire is provided to detect the relative interval between the cars.

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Katsuta, Japan

Hisakatsu Kiwaki