Abstract: An electric apparatus has a plurality of electric parts and a casing made of electrically conductive material for accommodating therein or mounting thereon a plurality of electric parts. The casing, which has a cavity therein, is provided with a plurality of projections for radiating heat generated by the electric parts in the cavity. The casing is provided with openings for allowing a heat conductive medium to flow into and out of the casing. Further, an electric apparatus has a plurality of electric parts and a casing made of electrically conductive material for accommodating therein or mounting thereon a plurality of electric parts. The casing is provided with openings for allowing a heat conductive medium to flow into and out of the casing. The casing is provided therein with a partition wall which is made of electrically conductive material for dividing the interior of the casing into a plurality of zones along a direction of a flow of the heat conductive medium.

Abstract: An encoder for indicating a position of a movable member and for generating at least two signals which are offset in phase from one another in accordance with movement of the movable member. The encoder includes a position detector and a presettable counter. The position detector generates a position reference signal indicating at least one reference position during movement of the movable member, and the presettable counter is preset for an absolute position of the encoder during movement of the movable member when the position reference signal is generated. The encoder can be constructed in a small size enabling use in servo systems and in industrial robots.

Abstract: A PWM inverter includes a plurality of arms connected in parallel with a d.c. power source. Each arm is constituted by an upper arm and a lower arm each having a switching element. A plurality of switching control signals are continuously and alternately applied to one and the other of the two switching elements constituting the same arm respectively. In the PWM inverter, shunt resistors are connected between a minus terminal of the d.c. power source and the lower arms respectively. The PWM inverter further comprises a waveform command generating circuit generating commands representative of current waveforms to be supplied to a load, a carrier wave generating circuit and sample-hold circuits. Each of the sample-hold circuits samples and holds a terminal voltage of the associated shunt resistor in synchronism with the period of the carrier wave generated from the carrier wave generating circuit and at specific timing in a conduction period of the associated switching element.