| 摘要 |
PURPOSE:To reduce the power consumption of a circuit in case of the occurrence of an accident and the consumption of a battery after the accident, and to obtain a controller for a phase detection type displacement amount detection system by a magnetic scale system, by providing a level converting circuit and switching a normal operation state wherein an exciting current is high and an abnormal state wherein the exciting current is low on the basis of a signal which controls the operation state. CONSTITUTION:The control signal PWF of the level converting circuit is at a low level in a backup state, i.e. when power source abnormality occurs and at a high level in the normal operation state, and a synchronous differentiating circuit 26 generates a pulse output STRT which goes up to the high level only for a period 2/fc as long as one cycle of the clock signal fc/2 of the circuit synchronously with the rise and fall of the signal PWF. A count control circuit 27 controls the count direction of an (n)-bit up/down counter 28 according to the change state of the PWF to generate a signal STP when a maximum or minimum value is attained to, holding the state. |
