Abstract: A transmission system transmits a signal from a transmission terminal to a reception terminal via a pair of transmission lines. The transmission terminal side of the transmission lines is connected to a first resistor having a predetermined resistance value depending on the characteristic impedance of the transmission lines.

Abstract: This transmission input circuit is provided with an adjustment processing section which turns ON a switch at an empty timing where transmission current from a slave device is not flowing, to allow a reference current to flow from a constant current circuit to a current detection resistor, generates in the current detection resistor a target adjustment voltage, in which a threshold voltage corresponding to the reference current is added to a load current detection voltage corresponding to the load current, and adjusts a digital value so that a reference voltage output from a digital variable resistor matches with the target adjustment voltage.

Abstract: A transmission input circuit of the present invention is provided with: a current detection resistor which receives an input of a line current flowing through a transmission line and generates a line current detection voltage; a constant current circuit which generates a predetermined reference current; a first switch which performs a switching operation at an empty timing where a transmission current is not flowing, to thereby allow the reference current to flow from the constant current circuit to the current detection resistor, and generate a reference voltage, in which a threshold voltage corresponding to the reference current is added to a load current detection voltage corresponding to the load current; a capacitor which is connected to the current detection resistor via the first switch; a second switch which performs a switching operation in synchronization with the first switch to thereby sample-hold the reference voltage generated by the current detection resistor in the capacitor; and a comparator

Abstract: A transmission input circuit of the present invention is provided with: a current detection resistor which receives an input of a line current flowing through a transmission line and generates a line current detection voltage; a constant current circuit which generates a predetermined reference current; a first switch which performs a switching operation at an empty timing where a transmission current is not flowing, to thereby allow the reference current to flow from the constant current circuit to the current detection resistor, and generate a reference voltage, in which a threshold voltage corresponding to the reference current is added to a load current detection voltage corresponding to the load current; a capacitor which is connected to the current detection resistor via the first switch; a second switch which performs a switching operation in synchronization with the first switch to thereby sample-hold the reference voltage generated by the current detection resistor in the capacitor; and a comparator

Abstract: This transmission input circuit is provided with an adjustment processing section which turns ON a switch at an empty timing where transmission current from a slave device is not flowing, to allow a reference current to flow from a constant current circuit to a current detection resistor, generates in the current detection resistor a target adjustment voltage, in which a threshold voltage corresponding to the reference current is added to a load current detection voltage corresponding to the load current, and adjusts a digital value so that a reference voltage output from a digital variable resistor matches with the target adjustment voltage.

Abstract: A transmission system transmits a signal from a transmission terminal to a reception terminal via a pair of transmission lines. The transmission terminal side of the transmission lines is connected to a first resistor having a predetermined resistance value depending on the characteristic impedance of the transmission lines.

Abstract: A power switching device includes a switching relay for supplying power to a main circuit by switching between power from a main power supply and power from a supplementary power supply, and a control unit for controlling the switching relay. The control unit includes a voltage detecting unit for detecting a voltage value of the power supplied by either the main power supply or the supplementary power supply. The power switching device includes a first switch assisting unit, composed of semiconductor switching elements, for feeding the power from the main power supply to the main circuit when the voltage detecting unit detects that the voltage value of the power is above a predetermined value, and a second switch assisting unit, composed of semiconductor switching elements, for feeding the power from the supplementary power supply to the main circuit when the voltage detecting unit detects that the voltage value of the power is below the predetermined value.

Abstract: A detected information display system in a fire detecting system of the present invention which is equipped with detectors arranged in a warning area and a control panel and achieves a specified information display on a physical quantity detected by the detectors, includes a secondary conversion part to convert the physical quantity detected by the detector to the specified level, a conversion level storage part to store the converted level, an extraction part to extract the maximum level from the levels stored in the conversion level storage part, and a display part which is equipped with level display parts, and keeps the level display part corresponding to the converted level and the level display part corresponding to the maximum extracted level in a visually different condition from each other. The maximum detected physical quantity and the set value to indicate the abnormal level can be rapidly grasped, and the displays of a plurality of detectors can be displayed in an integrated and related manner.

Abstract: The present invention relates to an emergency supervisory system which comprises a plurality of supervisory apparatus provided for respective supervisory regions and connected in parallel with each other to signal lines derived from a central signal station; and switching devices which are provided at positions for separate the supervisory apparatus from each other and adapted to be closed normally and opened upon detection of short-circuiting to separate the supervisory apparatus adjacent thereto from the lines, thereby to supervise an emergency such as a fire through one or both of the signal lines.