Abstract: The present invention relates to a fail-safe on-delay circuit which uses an an electronic circuit. An input signal higher than a power source potential is input to a PUT oscillating circuit and a pulse signal generated with a predetermined time constant, is once changed in a level conversion circuit to a level within a range of the power source potential, and then is phase inverted and a rising differential signal of the phase inverted signal is formed. The input signal to the PUT oscillation circuit is applied to one input terminal of a fail-safe two input window comparator, and the differential signal is input to the other input terminal, and self held. After a predetermined delay time an output of logic value 1 is generated from the window comparator. As a result a fail-safe on-delay circuit can be made wherein, in the event of a fault in the elements of the circuit the delay time is not shortened.

Abstract: The present invention relates to a warning apparatus which can continuously monitor a normal condition wherein an alarm sound can be produced. When a high level judgement signal (W) indicating safety is input, an inaudible frequency signal is supplied from a V-F converter (11) to a speaker (13) so that a warning sound of an inaudible frequency is generated, while when a low level (zero) judgement signal (W) indicating danger is input, an audible frequency signal is supplied from the V-F converter (11) to the speaker (13) so that a warning sound of an audible frequency which can be heard by personnel is generated. Furthermore, when an output current of an inaudible frequency or an audible frequency is supplied to the speaker (13), the output current is sampled by a current transformer (21) of a monitoring circuit (20), and amplified and rectified to give a direct current output signal (SN), thereby enabling verification that the warning apparatus is normal.

Abstract: The present invention relates to a safety ensuring apparatus for ensuring the safety of an operator.A mechanical moving part is surrounded by a safety enclosure with a door of the safety enclosure provided with a door lock device constructed such that the door lock device releases a door lock when a current is supplied from outside to excite a solenoid incorporated therein. The apparatus is constructed such that a lock is released when the mechanical moving part is stopped. Moreover, the construction incorporates a moving part monitoring sensor which monitors if the mechanical moving part is stopped. When mechanical moving part is stopped, the moving part monitoring sensor generates, without a negative operation, an output signal of logic value 1 corresponding to a high energy condition, and the solenoid of the door lock device is excited by this output signal.As a result, the lock of the door lock device is released once the mechanical moving part has stopped.

Abstract: A monitoring apparatus for an alarm device for situations wherein the alarm device is provided at a location remote from the alarm device drive side, which can verify from the alarm device drive side if an audible alarm has sounded. The drive of the alarm device (1) is stopped by switching off a drive switch (12) on the alarm device drive side (A). After stopping the drive of the alarm device (1) an audible alarm generation sensed signal from the response device (2) on the alarm device side (B)is received at the alarm device drive side (A) though the feeder (a). Then, after the audible alarm generation sensed signal has stopped, and on receipt of a verification signal verifying that the alarm device drive side (B) has returned to the original condition, a verification output (F3) for the audible alarm generation is generated at the alarm device drive side (A).

Abstract: The invention relates to a load drive circuit which is able to detect an "on" fault of a switch element for controlling power to a load, and reliably interrupt the load current. A monitoring sensor is provided which generates an output when energy is supplied to the switch element of the switch circuit from outside the circuit, and a received signal level of the energy is a high level with the switch element "off", but does not generate an output when a received signal level of the energy is a low level with the switch element "on". Through logical processing of the output of the monitoring sensor and a load drive signal for driving the switch element, using a logical sum operating circuit and a self-hold circuit, the relay contact points can be prevented, at the time of an "on" fault of the switch element, from following the load drive signal, and from "hunting".

Abstract: The present invention relates to a judgement circuit for determining rotation or non-rotation of a motor, and to a motor stopped verification apparatus using such judgement circuit. A signal from a rotation sensor which detects rotation of the motor is input to the judgement circuit and a threshold value judgement made using a fail-safe two input window comparator. That is, respective predetermined threshold value ranges (windows) are set for each terminal of the window comparator, so that when the motor is stopped and the judgement circuit and the sensor are normal, the level of the signal input to each terminal comes within the range of the window, and an output of logic value 1 is generated from the window comparator.

Abstract: The present invention relates to a current sensor for detecting current flowing in a current line, and a motor rotation sensor which utilizes this current sensor. A first transformer is inserted in a current line which is connected in parallel with a motor, so that a high frequency signal generated by a signal generator is transmitted to the current line by means of the first transformer. This high frequency signal is extracted by a second transformer inserted into another current line, and is transmitted to a receiver.

Abstract: This invention relates to a load driving circuit having a fail-safe breaking mechanism for breaking a primary power source when a failure occurs. This invention also relates to a load driving circuit capable of saving electricity in driving an inductive load and reducing a delay in stopping the load. The breaking mechanism for breaking the primary power source has no contact. The load driving circuit includes a power supply circuit involving a semiconductor switching element that turns ON and OFF the supply of power to the load. There is arranged a detector for detecting a failure in the semiconductor switching element. When detecting a failure, the detector provides an output signal to activate the breaking mechanism. To drive the inductive load, the power supply circuit may have two power supply sources. In response to a load driving instruction signal, the two power supply sources together apply a high voltage to the load.

Abstract: The present invention relates to an airplane detection system to surely detect an airplane moving along a runway or a taxiway. The system employs a wheel detection sensor for providing a wheel detected output when emitted electromagnetic waves are blocked by the wheels of the airplane and a fuselage detection sensor for providing a fuselage detected output when receiving the reflection of the emitted electromagnetic waves from the fuselage of the airplane. According to the output signals from both the sensors, the system detects the airplane.

Abstract: A fail-safe scan circuit sequentially and periodically drives and scans objective devices. The scan circuit has a failure detector that provides, upon detecting a failure, a signal of logical value 0 to inform of the failure. Adjacent input signals to the failure detector have a phase difference of .pi.. This phase difference results in simplifying the structure of the failure detector. The fail-safe scan circuit is employable to drive and scan many photosensors of a fail-safe multibeam sensor.

Abstract: A fail-safe logic circuit employs a transformer (T) and a level tester (1). The transformer receives input signals each representing a binary logic variable and provides the sum of magnetic flux based on the input signals. The level tester tests the level of the sum of the magnetic flux and provides a binary output (y) representing a logic value of 1 or 0. This circuit is simple and capable of lowering an output level.

Abstract: The present invention provides a fail safe scanning circuit incorporating a fault detection circuit (30) for detecting if the scanning output condition of a scanning output generating circuit (20) for continuously generating a scanning output signal for application to a driven object, is normal or abnormal. It has a fail-safe construction such that the output from the fault detection circuit (30) is stopped when an abnormality is detected in the scanning output, and also when the fault detection circuit is faulty.The invention also provides a multi-axis light beam-type sensor as a fail-safe human sensor for a system wherein a machine and a human work in the same space, by having a construction using two such fail-safe scanning circuits (41, 42), with pairs of light emitting elements and light receiving elements scan driven synchronously.

Abstract: A safety apparatus wherein a sensor (10.sub.n through 15.sub.n, 16) for transmitting object (M) detection information as a reduction in the output signal energy, is used as a human detection sensor, while a sensor (21-26) for transmitting object (M) detection information as an increase in the output signal energy is used as a work piece detection sensor, and drive of a mechanical moving portion is permitted only when the logical OR output of both sensors has a logical value of "1" corresponding to the high energy condition, thereby reliably ensuring excellent operator safety in a fail-safe manner.

Abstract: A method for assuring a safe work space operates so that a work enable signal is generated only when absence of workers from the work space where the workers work in cooperation with a machine is detected. The work enable signal has a logical value of 1 corresponding to a high energy state and only this signal can initiate activation of the machine sharing the subject work space thereby assuring safe environments for workers.

Abstract: The present invention is to provide a fail-safe slide operation control device for a press of simple structure when the electronic circuit by fail-safe signal processing as a circuit for monitoring overrun and confirming the OFF condition of an operation button, which is important function to control the slide, is used instead of a contact circuit composed of relays.

Abstract: A detecting device can centrally monitor and detect a lamp failure of one or more lamps connected in series such as guide lamps in the runway of an airfield. A core (12) is disposed on a power line (P.sub.1) of each lamp (L.sub.1 -L.sub.n). The power line (P.sub.1) is wound on the core (12) as a first winding (N.sub.1). A second winding (N.sub.2) for extracting the power of the power line (P.sub.1) is wound on the core (12). An oscillator (13) is provided which uses the output voltage of the second winding (N.sub.2) as the power supply to generate a frequency corresponding to each lamp (L.sub.1 -L.sub.n). The output signal from this oscillator (13) is fed back to the power line (P.sub.1) through a third winding (N.sub.3). Accordingly, a signal consisting of a frequency which represents each lamp flows through the lamp circuit and any failed lamp or lamps can be detected by checking this feedback signal.

Abstract: A ground guidance system for airplanes in which loop coils of a predetermined shape are continuously buried in a specific section of a taxiway for airplanes, an airplane is continuously detected based on changes of self-inductances of the loop coils with movement of the airplane while discriminating airplanes from other objects and admission or inhibition of advance in the specific section to a subsequent airplane according to the presence or absence of the airplane in the specific section and which has a fail-safe structure not generating an output at the time of a system or circuit failure or accident.

Abstract: In an "AND" logic operation-oscillation circuit in which an oscillating output is produced when a signal of a voltage higher than the voltage of a circuit power source is applied a diffused resistor is used for a resistor to which a voltage lower than the circuit power source is applied and a non-diffused resistor is used for a resistor to which a voltage higher than the voltage of the circuit power source is applied, whereby there is constructed a fail-safe circuit in which a short circuit trouble is not caused even if an input signal of a level higher than the voltage of the circuit power source is applied and a phenomenon that an oscillating output is produced even in the absence of an input signal is prevented.

Abstract: Disclosed is a monitoring system for a load-driving switch circuit, in which a switch circuit arranged in a circuit for driving an electrical load is controlled and opened or closed by a fail-safe input signal Si, the conduction state or non-conduction state of the switch circuit is detected by taking out a high voltage or low voltage from terminals of the switch circuit, and logical addition of this terminal voltage and the input signal Si is performed to detect whether or not the terminal voltage is in agreement with the input signal Si, whereby malfunction of the load owing to trouble in the switch circuit is monitored.

Abstract: In an apparatus for counting enumeration input pulses according to the present invention, an enumeration input pulse is put in parallel in a plurality of stages of logical product computing oscillator means, and counting in the logical product computing oscillator means of the subsequent stage is advanced on condition that an output of termination of counting is put out from the logical product computing oscillator means of the precedent stage. For this purpose, delay means is arranged after the logical product computing oscillator means to set the time from the point of output of the logical product computing oscillator means of the precedent stage to the point of termination of a predetermined delay time so that this time is longer than the width of the enumeration input pulse and shorter than the frequency thereof.