Hitachi, Ltd.

Takamasa Hori

Toshiaki Okuyama

Mitsuyuki Honbu

Masahiko Ibamoto

Hiroshi Sato

Sanshiro Obara

Hiroshi Nagase

Korefumi Tashiro

Yasunori Katayama

Yuzuru Kubota

Sadao Hokari

Hiroshi Hayashida

Hideki Asano

Takanobu Hatakeyama

Katsu Komuro

Hajime Yokota

Kunio Saito

Toshiroo Narita

Noboru Arahori

Hiroyuki Okamoto

A plurality of optical guide paths are built in a guide path plate. A plurality of optical guide posts are erected on the guide path plate so that each may oppose to one end of the corresponding optical guide path. The other end of at least one of the optical guide paths is optically connected to a light projecting portion, and the other end of at least another of the optical guide paths is optically connected to a light receiving portion. A part to-be-sensed which is movable is located between the distal ends of the optical guide posts whose base ends are connected to the corresponding optical guide paths. The presence of the part to-be-sensed is detected in such a way that the part to-be-sensed interrupts or transmits light which passes between the distal ends of the optical guide posts.

Photosensor employing optical guide posts to detect an object in the path

Controller for AC elevator

A time division multiplex data transmission system. A particular time slot among those for data transmission is placed with alternation of different data modes such as '1' and '0' in a commanding station destined for issuing commands. The alternation of data modes is supplied to receiver stations together with other data. When alternation of data modes is detected at the particular time slot in the receiver station, the reception of one command signal from the commanding station is confirmed, while detection of disappearance of the alternation of data modes indicates other command. Since a fault in the data transmission system results in generation of a fixed data mode or level such as '1' or alternatively '0', the alternation of data modes and disappearance thereof can define the commands discriminatively from the state brought about by the fault. Fail-safe feature can thus be realized.

Time division multiplex data transmission system

An AC motor has polyphase stator windings connected to an AC bus and has polyphase rotor windings connected directly or through impedances to capacitors. The capacitances of the capacitors are selected so as to be such that the AC motor exhibits a small input impedance for a specific frequency to be eliminated, thereby preventing the power factor from being since the fundamental frequency is not affected in any way under a light load. As a result, harmonics can be eliminated without causing any excessive AC source voltage.

Harmonic eliminating apparatus

A speed control system for an induction motor controlled by a converting arrangement coupled with a commutatorless motor which operates without commutation failure notwithstanding wide variations in the speed of the commutatorless motor. The speed control system includes an arrangement for maintaining the value of a direct current signal of the converting arrangement less than the maximum current value for ensuring proper operation of the converting arrangement.

Kramer system utilizing a commutatorless motor

A control system for a brushless motor is disclosed which comprises an AC power supply, a rectifier circuit including controlled rectifier elements for converting the alternating current supplied by the AC power supply into a direct current, an inverter circuit including controlled rectifier elements for converting the direct current produced by the rectifier circuit into an alternating current, a motor driven by the inverter circuit and a position detector for detecting a signal representing rotational positions of the motor. The controlled rectifier elements of the inverter circuit are fired in predetermined sequence in response to detection signals from the position detector, while the DC output current of the rectifier is continually controlled at each commutation of the inverter circuit at low motor speeds. A predetermined number of signals in synchronism with each commutation of the inverter circuit are included in one cycle, so that the DC output current of the rectifier circuit is controlled for continual operation by the use of signals with different delay times behind the aforementioned signals concurrent with the commutation of the inverter.

Control system for brushless motor

Growing community of inventors

Ibaraki, Japan

Takamasa Hori