Patent ID: 8253366

Claim:
A device for diagnosing signal status of a driven object, in which a drive voltage signal for driving the driven object is inputted via an insulation means, the driven object is driven by electric drive power corresponding to the inputted voltage, and concurrently signal status of the driven object is diagnosed, wherein the device comprising: an insulation transformer having an intermediate tap at a midpoint of its primary winding as said insulation means, to the secondary side of which is connected said driven object, a signal generating means for generating periodically vibrating voltage including a rectangular wave pulse voltage and alternating voltage having an amplitude corresponding to that of said inputted drive voltage signal for driving the driven object connected to the primary side of the insulation transformer, a current measuring means connected to the intermediate tap of the primary winding of the insulation transformer to measure a current generated in the primary side caused by the current flowing in the driven object connected to the secondary side of the insulation transformer, a feedback means for converting the current flowing from the intermediate tap of the primary side to a voltage corresponding to the drive voltage driving the driven object and feeding back the converted voltage to the input drive voltage signal, and a voltage measuring means for measuring the voltage added with the feedback voltage, whereby diagnosis of signal state of the driven object is performed based on measurement results of the current measuring means and voltage measuring means.