Abstract: The present invention relates to a shaft encoder device, comprising magnetic sensor means designed to detect the magnetic field of a magnetic field generating means stationary with respect to the shaft, a light source, optical sensor means designed to detect light emitted from the light source and reflected or transmitted by an encoder disk stationary with respect to the shaft, and signal processing means designed to receive first data from the magnetic sensor means and second data from the optical sensor means, and to determine an angle of rotation of the shaft from the received first data and/or to determine the angle of rotation of the shaft from the received second data.