Each component of a modular encoder can be formed so as to be fixed to a rotary shaft of a rotating unit in a horizontal direction (a direction of a shaft line of a rotary shaft). Consequently, the modular encoder can easily be assembled and fixed, and reliability of fixation can be enhanced at the same time. In addition, the modular encoder has an elliptical shape so that a size thereof can be reduced in a direction in which a dimension should be decreased. Furthermore, if the holding member is rotatably fitted in the locking member in such a manner that the holding member can be rotated around the rotary shaft of the rotating unit, a sign plate can easily be aligned.
An encoder detects angular movement between a shaft and support about a rotational axis. A base mounts a signal emitter and sensor. A fitting is mountable to the shaft, coaxial with the rotational axis. A signal interrupting disk on the fitting is positioned in spaced relation to the emitter and sensor. An alignment bracket may be mounted to the base for relative axial movement. A yieldable member axially biases the base and alignment bracket to a pre-mounting relationship. A fastener secures at least one of the base or alignment bracket to the support, deflecting the yieldable member and positioning the emitter sensor, in a prescribed operative position on the support. The yieldable member will return the base and alignment bracket to the pre-mounting relationship when the encoder is removed from the support.
