Abstract: An angle detector for detecting an amount of angular change due to the rotation of a rotary body. The angle detector is provided with a rotary body rotating around a rotation axis, a graduated scale having a plurality of graduations along the circumference of the rotary body in a rotation direction, and a plurality of sensors disposed along the circumference. Each of the sensors outputs a signal according to an amount of angular change on the basis of the plurality of graduations. The output signal includes a fundamental wave component having one of the plurality of graduations as a first period first order, and a harmonic wave component having an order that is an integer multiple of at least two times the fundamental wave component. An amount of angular displacement calculated from the output signal includes an angular error component that is due to the harmonic wave component and has an order component that is an integer multiple of the one graduation that is the first period first order.

Abstract: A bearing rotatably supported by a housing. The bearing having one radial and two axial parts all including a plurality of rolling elements. The rolling elements of the radial bearing part contact an outer peripheral surface of an output shaft. The rolling elements of one or two of the axial bearing parts contact the outer peripheral surface of the output shaft. The rolling elements of the other axial bearing part contact a first ring-shaped part fixed to the output shaft to form an output-shaft side raceway surface. The rolling elements of the radial bearing part and of the two axial bearing parts contact the surface of a second ring-shaped part disposed on the output shaft, or the rolling elements of the radial bearing part and of one of the axial bearing parts directly contacts the inner surface of the housing to form an outer raceway surface.

Abstract: The present invention provides a method for detecting a positional change amount due to a movement of a moving body by reading, with a sensor, a plurality of gradations disposed along the direction of the movement.

Abstract: An angle detector for detecting an amount of angular change due to the rotation of a rotary body. The angle detector is provided with a rotary body rotating around a rotation axis, a graduated scale having a plurality of graduations along the circumference of the rotary body in a rotation direction, and a plurality of sensors disposed along the circumference. Each of the sensors outputs a signal according to an amount of angular change on the basis of the plurality of graduations. The output signal includes a fundamental wave component having one of the plurality of graduations as a first period first order, and a harmonic wave component having an order that is an integer multiple of at least two times the fundamental wave component. An amount of angular displacement calculated from the output signal includes an angular error component that is due to the harmonic wave component and has an order component that is an integer multiple of the one graduation that is the first period first order.

Abstract: The present invention uses a bearing having one radial bearing part and two axial bearing parts, each bearing part having a plurality of rolling elements retained in a retainer. The row of rolling elements of the radial bearing part contacts the outer peripheral surface of an output shaft, and the row of rolling elements of the two axial bearing parts or of one of the axial bearing parts contacts the outer peripheral surface of the output shaft and the row of rolling elements of the other axial bearing part contacts a first ring-shaped part fixed to the output shaft, so as to form an output-shaft side raceway surface.

Abstract: The present invention provides a method for detecting a positional change amount due to a movement of a moving body by reading, with a sensor, a plurality of gradations disposed along the direction of the movement.