Abstract: A current limiter used for stable control of an electric power system, and particularly applied to a high voltage of the electric power system, has a reduced voltage for suppressing the overcurrent of the electric power system. The current limiter is not enlarged so that the current limiter secures the insulation of the voltage withstanding level, and the current limiter is easy to be introduced to the system. A limiting device is inserted between a low potential terminal of a winding of a star-connection of a three-phase transformer that has at least one winding of the star-connection and a ground point.

Abstract: A visual axis detecting device includes an image sensor for imaging an eyeball image and a visual axis detector for detecting a Purkinje image from the eyeball image imaged by the image sensor as well as for extracting pupil edges from a plurality of pupil edge candidates contained in the eyeball image and detecting the visual axis of a user using the Purkinje image and the pupil edges. The visual axis detector defines a reference point from the position of the Purkinje image, determines the distances from the reference point to the plurality of pupil edge candidates, respectively, and extracts the pupil edges from the plurality of pupil edge candidates by statistically processing the distances. With this arrangement, the visual axis detecting device can correctly extract the pupil edges at a high speed.

Abstract: An optical apparatus includes a signal output device which outputs an analog signal corresponding to a position of an operation member and a determination device which determines the position of the operation member in accordance with at least first and second determinations. In the first determination, the determination device determines the position of the operation member during movement of the operation member by comparing the analog signal of the signal output device with a plurality of predetermined values. In the second determination, the determination device determines the position of the operation member after the operation member has stopped by using a manner different from a manner of the first determination.

Abstract: A current limiter used for stable control of an electric power system, and particularly applied to a high voltage of the electric power system, has a reduced voltage for suppressing the overcurrent of the electric power system. The current limiter is not enlarged so that the current limiter secures the insulation of the voltage withstanding level, and the current limiter is easy to be introduced to the system. A limiting device is inserted between a low potential terminal of a winding of a star-connection of a three-phase transformer that has at least one winding of the star-connection and a ground point.

Abstract: An electric power flow controller for controlling an electric power flow of a power system includes a semiconductor switch for controlling a series reactance of the power system. The electric power flow controller includes a first winding having at least one Y-connection, a second winding mating with the first winding, an electric power flow compensator connected in series to the Y-connection of the first winding and for compensating a transmission state of the electric power system. The electric power flow compensator provides a compensating capacitor inserted onto an electric power line. The compensation of the capacitor is controlled by the semiconductor switch. The semiconductor switch keeps an application of a voltage that is equal to or lower than a voltage to ground of the electric power line.

Abstract: A plurality of solid-state switches are provided in parallel with a main circuit switch. A main circuit current is detected by a first current detecting device. A current flowing in each of the plurality of solid-state switches is detected by a second current detecting device. Based on the detected currents of the first and second current detecting devices, the main circuit switch is commanded to open and each solid-state switch is commanded to close by a control circuit, when a fault is detected by a fault detecting circuit. At this point of the process when the main circuit switch is opened, when a commutation anomaly is detected by a commutation detecting circuit, the conducting status of each solid-state switch is maintained. When the commutation achieves a normal status, each solid-state switch is interrupted and circuit breaking, at the point the capability of each solid-state switch is exceeded, is prevented.

Abstract: A ground fault current limiter, in which reactors are connected in series to a neutral point for compensating for capacitances to ground of a power switches capable of turning ON/OFF at a high speed are connected in parallel with respective reactors, occurrence of a ground fault is detected from a phase difference between a zero-phase sequence current and a zero-phase sequence voltage at time of sampling, an optimal compensation quantity of capacitances to ground is computed based on the zero-phase sequence current and the zero-phase sequence voltage at time of occurrence of a ground fault, and ON/OFF of the switches are controlled thereby to alter the reactor quantity so as to correspond to the compensation quantity.

Abstract: Apparatus for delaying a camera extendible lens from being automatically withdrawn into the camera body by the camera lens driver when the camera mode setting switch is set to or through a camera OFF setting includes control structure for (i) determining that the camera mode setting switch has been set to the camera OFF setting, (ii) causing a predetermined time to be counted after it has been determined that the camera mode setting switch has been set to the camera OFF setting, (iii) again determining that the camera mode setting switch has been set to the camera OFF setting after the predetermined time has finished being counted, and (iv) causing the camera lens driver to withdraw the lens into the camera body only if it has been again determined that the camera mode setting switch has been set to the camera OFF setting. Preferably, this prevents the extendible lens from being automatically withdrawn into the camera body every time the mode setting switch is turned through the OFF setting.

Abstract: An apparatus for controlling a switching device provided for breaking or closing a power line connecting a power source to a load in an electric power system includes a switching timing control unit for controlling the timing to apply a breaking signal to said switching device in response to a breaking signal externally applied thereto so that the contacts of said switching device are opened during a period of time when the current flowing through said power line first reaches its peak value from a zero value and for controlling the timing of applying a closing signal to said switching device in response to a closing command preferably externally applied thereto so that the contacts of said switching device are closed when the voltage of said power source becomes a predetermined value depending upon whether said load is capacitive or inductive, and an operating unit for opening and closing said contacts of said switching device in response to said breaking and closing signals, respectively.

Abstract: A solid-state switch has a plurality of gate turn-off thyristors connected in the rungs of a ladder circuit and a plurality of diodes connected in the side rails of the ladder circuit. The anode of the first gate turn-off thyristor is connected to the cathodes of the first and second diodes, the cathode of the first gate turn-off thyristor is connected to the anodes of the third and fourth diodes. The cathode of the second gate turn-off thyristor is connected to the anode of the second diode and the anode of the fifth diode, the anode of the second gate turn-off thyristor is connected to the cathode of the fourth diode and the cathode of the sixth diode. The anode of the first diode and the cathode of the third diode are connected together at a common point, which is selected to be one terminal of the switch.

Abstract: An electrical power system protection device includes a circuit breaker and a switch connected in series to a power line. The protection device also has a current limiting element connected in parallel to the circuit breaker. When the level of electrical current flowing in the power line, detected by a current detector, has exceeded a predetermined first set level, a first over-current detector delivers immediately a trip command to the circuit breaker. As a consequence, fault current is commutated to the current limiting element so that any drop of voltage in the power line upstream of the circuit breaker is greatly suppressed. When a state in which a predetermined second set level is exceeded by the detected current level is continued beyond a predetermined period, a second over-current detector delivers an off command to the switch, thus protecting the upstream portion of the power line against the fault in this power line.

Abstract: A camera includes an electronic zooming feature to selectively transform an image actually received at an image sensor into a displayed image at a photographing plane according to different angles of view corresponding to different zooming ratios. The image actually received is converted to binary data and stored in memory according to address coordinates. Electronic zooming is performed without affecting the optical system of the camera by reading stored data from memory to obtain an area defined by selected address coordinates and displaying an image corresponding to a desired focal length.

Abstract: This invention discloses a camera capable of being remote-controlled by a remote control signal, comprising a memory for storing a distance information in response to the operation of an operating member, and a control circuit for permitting the memory to hold the distance information stored in the memory in response to the setting to enable remote control by the remote control signal even after the operation of the operating member was cancelled.

Abstract: A vacuum switch apparatus has an electrically insulating vacuum enclosure which is evacuated to a vacuum degree of 2.times.10.sup.-2 Torr or less. One set of anode and cathode electrodes is arranged in the vacuum enclosure, having capacity which permits the flow of a discharge current of at least 1 KA therebetween and being operable to switch the discharge current at least 10.sup.6 shots. A high voltage power supply applies a high voltage of at least 20 KV across the anode and cathode electrodes. An electron beam irradiation unit irradiates an electron beam on the anode electrode through the cathode electrode. A control electrode is arranged between the beam irradiation unit and the cathode electrode, for controlling passage and interception of the electron beam. A control voltage power supply applies a control voltage to the control electrode.