Abstract: Disclosed is a servo motor with a built-in drive circuit according to the present invention in which, when power is off, positional data including multiple-rotation counting values is stored in a nonvolatile memory to thereby eliminate battery back-up, and in which the CPU of a drive control circuit portion is in charge of the multiple-rotation counting itself to thereby eliminate the circuit for multiple-rotation counting. Due to a reduction in the number of lines involved and an elimination of battery back-up, a reduction in size is achieved. A servo motor with a built-in drive circuit according to the present invention includes an absolute encoder (30) for detecting rotation of a servo motor portion (100) and an electromagnetic mechanical brake (20), in which, when the power is off, the positional data (30A) at that time is stored in a nonvolatile memory.

Abstract: Disclosed is a method of driving a servo motor with a built-in drive circuit in which a common rectifying circuit is provided on a distribution board to which a plurality of the servo motors with built-in drive circuits are connected, to thereby achieve a reduction in size of each servo motor. In this method, there is used a common distribution board for distributing power to be supplied to a plurality of servo motors with built-in drive circuits and for distributing a communication line, an external communication signal and external input power are supplied through the distribution board.

Abstract: Disclosed is a servo motor with a built-in drive circuit in which a sensor circuit portion, a drive control circuit portion, and a motor drive circuit are collectively provided on two boards, thereby achieving simplification and a reduction in size of circuit configuration. In the servo motor with the built-in drive circuit according to the present invention, the sensor circuit portion and the drive control circuit portion are formed on a sensor circuit board, and the motor drive circuit is formed on a motor drive board, thereby achieving a reduction in size.

Abstract: An improved optical fiber gyroscope is provided to determine the angular velocity of an optical system. A beam of light emitted from a coherent light source are split into first and second light components. The first light component is further split into third and fourth light components while the second light component is further split into fifth and sixth components. The third and fifth light components are passed through a coil-like optical fiber in opposite directions to each other while the fourth and sixth light components are passed through an optical modulator in opposite directions to each other. The third and fourth light components are made to be interfered in a photodetector while the fifth and sixth light components are made to be interfered in another photodetector. From the outputs of the photodetectors, the above angular velocity is determined.