Abstract: A frequency abnormality detecting circuit for detecting the frequency abnormality of an AC power source, comprises a waveform shaping circuit for shaping an output waveform (detection waveform) of the AC power source, which is an object to be detected; a frequency demultiplier for demultiplying an output of the waveform shaping circuit at least by one period of the dection waveform; a counter for counting an output pulse of a reference oscillator by the leading edge of an output pulse of the demultiplier; a memory circuit such as a read only memory (ROM) for storing bit data using output data of the counter as an address; an OR gate for performing an OR operation of an output of the memory circuit; a switch device for inputting the output of the memory circuit into the OR gate; and a flip-flop for operating in synchronism with the output pulse of the frequency demultiplier using an output of the OR gate as data input.

Abstract: A synchronism detector circuit wherein it is arranged so that two a.c. voltages the synchronism of which is to be determined are converted, respectively, into rectangular pulses, which pulses trigger a pair of one-shot multivibrators, respectively, the logical product of the outputs from these one-shot multivibrators is provided, and the thus provided logical product causes signals indicating the states of synchronism between the a.c. voltages to be output.

Abstract: An inverter control circuit for a power supply source comprising an inverter and a commercial power source (reserve power source) and adapted to connect the inverter normally to a load and to change the inverter with the commercial power source uninterruptedly by means of a thyristor switch to supply power uninterruptedly to the load in case the inverter malfunctions. The inverter control circuit comprises a digital PLL circuit for synchronism control, a bias signal, and a parallel connection of a synchronism control circuit and a synchronism detecting circuit, and is capable of uniterruptedly changing the inverter to the commercial power source by being switched to biasing signals by means of the switch at the timing of the synchronism detecting of the synchronism detecting circuit in case the synchronism control circuit malfunctions.

Abstract: In an inverter circuit composed of arms of at least one pair, connected between positive and negative lines of DC power source and turned on or off alternately, an abnormal state detecting circuit compares the neutral potential of the pair of arms with the neutral potential of the DC power source, and discriminates the abnormal state of the switching operation of the arms if the comparison result becomes less than a prescribed value.

Abstract: A linear pulse motor includes a stationary body having two ridges on both sides, the two ridges extending substantially in parallel with each other along the lengthwise direction of the stationary body; a movable body; at least two axles fixed to the movable body; rolling bearings supported on both end portions of the two axles respectively, one of the rolling bearings being fixed to one of the end portions of the respective axle at its inner race, and the other of the rolling bearings being slidably fitted to the other of the end portions of the respective axle at its inner race; and coil springs arranged between the movable body and the other of the rolling bearings so as to press outer races of the ones of the rolling bearings to one side surface of one of the two ridges and outer races of the others of the rolling bearings to one side surface of the other of the two ridges, the one side surface of the one of the two ridges being destined for regulating the movement of the movable body.

Abstract: A cleaner drive assembly used for driving a belt cleaning device such as a shower pipe unit provided in a papermaking apparatus having a sheet forming station including an endless belt to forwardly carry a wet web of paper thereon, the belt cleaning device being used to clean the endless belt by applying streams of liquid to the belt and being movable in opposite directions substantially parallel with the direction of width of the belt. The cleaner drive assembly is adapted to drive the belt cleaning device alternately in the aforesaid opposite directions and comprises a drive unit to produce rotary motions in alternately opposite directions, a rotary-to-axial motion converting unit to convert the rotary motions into reciprocating axial motions, the directions of the reciprocating axial motions being aligned with the opposite directions in which the belt cleaning device is movable.

Abstract: A synchronism detector circuit wherein it is arranged so that two a.c. voltages the synchronism of which is to be determined are converted, respectively, into rectangular pulses, which pulses trigger a pair of one-shot multivibrators, respectively, the logical product of the outputs from these one-shot multivibrators is provided, and the thus provided logical product causes signals indicating the states of synchronism between the a.c. voltages to be output.