Abstract: A band elimination filter 35 that eliminates or reduces a low frequency noise superposed on resolver signals S1 and S2 is provided between a synchronous detection circuit 34 that performs synchronous detection by referring to an excitation signal and a controller 36 that controls a digital angle output ? to make a deviation (sin(???)), which is the output of the synchronous detection circuit, zero.

Abstract: A reference signal generation circuit generates a reference signal used in synchronous detection for removing an excitation signal component in an angle calculation section that converts a detection angle ? obtained from two-phase resolver detection signals output from a resolver, to a digital output angle ?. The reference signal generation circuit includes a first multiplier, a second multiplier, and an adder. The first multiplier multiplies one of the resolver detection signals sin ? sin(?t+??) by the sine value sin ? of the digital output angle ? obtained from the angle calculation section. The second multiplier multiplies the other resolver detection signal cos ? sin(?t+??) by the cosine value cos ? of the digital output angle ? obtained from the angle calculation section. The adder adds the output of the first multiplier and the output of the second multiplier to output the sum signal sin(?t+??) as the reference signal.

Abstract: Potentials at both ends of an exciter coil to which an exciting signal is sent by a push-pull method are compared, and at least one of a short circuit to ground and a short circuit to a power supply of a signal line for the exciting signal is detected based on the duty cycle of a rectangular-wave signal indicating the result of comparison. Alternatively, a predetermined reference potential is compared with a potential of at least one of two phase detection signals before detection, and at least one of a short circuit to the ground and a short circuit to the power supply of a signal line for the at least one of the detection signals is detected based on the duty cycle of a rectangular-wave signal indicating the result of comparison.

Abstract: An electrostatic developer comprising a mixture of (1) a toner component containing image-forming particles, and (2) particles obtained by subjecting inorganic oxide or organic particles to a hydrophobic treatment with a dimethyl cyclopolysiloxane.