Abstract: An information processing device is connected via a communication network to a different information processing device. In the information processing device, a periodic message is received as a learning periodic message from the different information processing device. A reception interval is calculated between (i) a one message of the learning periodic message and (ii) a different message that is received immediately before the one message. A reference value of the reception interval of the periodic message is judged based on the calculated reception interval. The reference value is used as a judgment reference to judge whether or not a judgment target periodic message is normal. The judgment target periodic message is the periodic message transmitted by the different information processing device after the reference value is determined.

Abstract: An ultrasonic motor includes an oscillation drive circuit for generating an oscillation wave by self-excited oscillation of an oscillator bonded with a piezoelectric element, and a start/stop signal generating circuit for generating a signal for controlling the starting and stopping of the ultrasonic motor by bringing the oscillation drive circuit into an active state and a stop state, respectively. The oscillation drive circuit includes a power amplifier for amplifying an excitation signal, a capacitive circuit for adjusting a frequency of the excitation signal, and a switching circuit connected to a capacitive element of the capacitive circuit for short-circuiting terminals of the capacitive element based on an output signal of the start/stop signal generating circuit.

Abstract: A cutter for a welding apparatus for cutting a welding workpiece upon welding. In order to facilitate the positioning of the cutter during the movement of the cutter for the cutting operation and to make the entire apparatus small-sized, a shear frame is formed with substantially the shaped of a C, and the opposing portions of the C-shaped shear frame are connected by a connecting rod, enabling the reaction force during the cutting operation to be resisted by the shear frame itself.

Abstract: A time division multiplexing amplifier having a differential amplifier, such as a dynamic bridge amplifier, which has a predetermined gain accurately provided by means of operational network resistors. The differential amplifier is used to amplify differential signals containing a common-mode voltage. Prior to amplification of the differential signals, a common-mode voltage is applied in common to two input terminals of the differential amplifier, and then the differential amplifier is adjusted to provide a zero offset voltage. After that, the differential signals are applied to the differential amplifier, so that the differential signals can be amplified without having any adverse effect of a common-mode voltage.

Abstract: In measuring analog input voltages through isolation transformers, an analog input voltage V.sub.in is applied across a primary winding of the isolation transformer, voltages V.sub.A and V.sub.B developing across the secondary winding of lapses of time T.sub.A and T.sub.B (T.sub.A < T.sub.B) from application of the analog input voltage are detected, and by using measured times T.sub.A and T.sub.B and secondary winding voltages V.sub.A and V.sub.B, the analog input voltage V.sub.in is calculated in accordance with an expression ##EQU1## whereby influence of sag due to the isolation transformer is compensated for.

Abstract: A DC-to-DC converter for providing a DC output voltage proportional to a DC voltage applied to the primary winding of a transformer by turning on and off the applied DC voltage by means of a switching element connected in series with the primary winding. The voltage developed across the secondary winding of the transformer upon the turning on and off of the applied DC voltage is rectified and smoothed by means of a circuit including a rectifying diode, a choke coil and a capacitor. The transformer has a core which exhibits a rectangular hysteresis characteristic. When the switching element is turned off, the current flowing through the choke coil when the switching element is conductive is caused to flow as a reset current through a part of the secondary winding of the transformer so that the level of the magnetic flux of the core of the transformer may be restored to its initial value.