Hitachi, Ltd.

Hitachi Medical Corporation

Takanobu Hatakeyama

Yasunori Katayama

Sadao Hokari

Kazuo Kaneko

Seiya Shima

Hirofumi Hino

Tomiaki Kurihara

Katsu Komuro

Kazuo Yamamoto

Hideki Uemura

Toshio Meguro

Hiroyuki Takeuchi

Hiromi Inaba

Kenji Yoneda

Takeki Ando

Toshiaki Kurosawa

Hisakatsu Kiwaki

Kazuhiro Sakata

Nobuo Mitsui

Hiroshi Takano

Takuya Domoto

Takamasa Hori

Yasuyuki Maeda

Kanji Yoneda

Tadao Kameyama

Yuzaburo Iwasa

Hiroshi Okubo

Takeshi Ohira

Kayo Shimada

Chihiko Honzyo

Keiichi Chabata

Toshiro Narita

Toshiroo Narita

Noboru Arahori

A power source apparatus distributes a current command value to be supplied to a load to a plurality of output current amplifiers connected in parallel with the load, and each of the output current amplifiers supplies an output current corresponding to the current command value so distributed. This power source apparatus prevents a circulating current between the output current amplifiers by controlling each output current amplifier so that the difference between the output current from each output current amplifier and the distributed current command value becomes zero, or by inserting current limiting devices into the output line of each output current amplifier.

Power source apparatus including a plurality of output current

In an inverter type X-ray apparatus comprising an inverter including a plurality of switching elements operated alternately to generate an AC voltage having a rectangular waveform, a high voltage transformer transforming the AC voltage of rectangular waveform into a high AC voltage, a high voltage rectifier circuit rectifying the high AC voltage into a DC voltage, and an X-ray tube to which the DC voltage is applied as a tube voltage, the switching elements are driven to make chopping operation at a frequency high than the inverter drive frequency, and a pattern signal is generated for gradually increasing the duty cycle of the chopping operation in synchronism with the timing of switching over the switching elements.

Inverter type X-ray apparatus

Disclosed is a resonant DC-DC converter which comprises an inverter for converting DC power into AC power, a rectifier connected to the AC output of the inverter through a resonant transformer for rectifying AC output power of the transformer to obtain DC power to be applied to a load, means for determining respective operation phases of a first, a second, a third and a fourth switching elements constituting the inverter in accordance with set signals indicating a voltage and a current to be supplied to the load, and a phase control circuit for controlling the respective operation phases of the first, second, third and fourth switching elements on the basis of an output signal of the phase determining means in a manner so that the first and second switching elements are alternately turned on with a phase difference of 180 degrees with respect to an operation frequency of the inverter, the third and fourth switching elements are alternately turned on with a phase difference of 180 degrees with respect to the operation frequency of the inverter, while varying a phase difference from turn-on of the first switching element to turn-on of the fourth switching element and a phase difference from turn-on of the second switching element to turn-on of the third switching element to thereby control or feed-back control the DC power to be supplied to the load.

Resonant DC-DC converter

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

Disclosed is an inverter type X-ray apparatus comprising a DC-DC converter for converting a DC voltage into a different DC voltage, an inverter for inverting an output voltage of the DC-DC converter into an AC voltage, a high voltage transformer for transforming an output voltage of the inverter into a higher voltage, a rectifier for converting an AC output voltage of the transformer into a DC voltage, and an X-ray tube to which an output voltage of the rectifier is applied. In the apparatus, the DC-DC converter includes a reactor, a switching element and a capacitor which are interconnected so that the DC-DC converter can generate an output voltage higher or lower than an input voltage.

Controller for AC elevator

An elevator controller which uses an acceleration command signal that has as its initial value a start shock compensation torque which will offset the unbalance torque caused at the time of starting. From the completion of elevator car acceleration to the start of deceleration, the acceleration command is gradually increased or decreased to control the motor so as to provide a smoother motion of the car. After the inception of the car deceleration a velocity command is issued which decreases with the reducing distance between the car and the destination floor.

Controller for elevator

In an AC elevator system employing a three-phase induction motor for driving an elevator car, the primary voltage supplied to the induction motor is controlled to control the motoring torque in the acceleration mode and in the rated-speed running mode, while, in the deceleration mode, a power converter unit supplies AC power of low frequency to the induction motor to apply regenerative braking.

AC Elevator control system

A pulse generator is coupled to a car drive motor directly coupled to a sheave, over which a rope suspending an elevator car is passed, and the position of the car is calculated through the counting of pulses produced from the pulse generator. First and second car position detectors for detecting respective first and second car positions are provided within a hatchway, and the number of pulses produced during a period from the actuation of the first car position detector till the actuation of the second car position detector is detected. A count value for calculating the car position is corrected according to the difference between the detected pulse number and a reference pulse number corresponding to the distance between the first and second car position detectors, thereby effecting the compensation for the wear of the sheave and rope to improve the precision of the car position detection.

Method and apparatus for detecting elevator car position

An abnormal speed detector for an elevator system having an elevator car for servicing a plurality of floors, means for driving the elevator car in response to a speed command and a speed detector for detecting a running speed of the elevator car is disclosed. The abnormal speed detector comprises means for storing a set of speed data indicating a predetermined abnormal speed checking pattern as a function of running time or running distance of the elevator car, means for reading out of the storage means one of the set of speed data corresponding to an instant value of the running time or running position of the elevator car after the start of run, and means for comparing an actual speed of the elevator car with the readout speed data to determine if the speed of the elevator car is normal or not.

Abnormal elevator speed detector

An elevator car control apparatus is disclosed in which a three-phase AC tachometer generator is coupled to a motor for driving an elevator car, and the AC output of the tachometer generator is full-wave rectified for use as a speed feedback voltage. A waveform-shaping circuit generates one pulse for each cycle of the output of the AC tachometer generator. A counter counts such pulses after the car has passed a deceleration-initiating point, thereby producing the number of counts proportional to a car running distance after the passage of the deceleration-initiating point. From this number of counts, a deceleration command voltage decreasing progressively in accordance with car positions is obtained by a decoder and a digital-analog converter. During deceleration, the car-drive motor is subjected to feedback control in accordance with the difference between the speed feedback voltage and the deceleration command voltage, thus effecting deceleration control of the elevator car.

Elevator control apparatus

Growing community of inventors

Katsuta, Japan

Takanobu Hatakeyama