Abstract: A rotational angle detecting device includes a rotatable plate attached to a shaft of a rotatable motor having a plurality of windows located at a first angular pitch and at a selected circumference with respect to the shaft, a light source, a stationary plate including first and second photoelectric detecting elements at a second pitch and the selected circumference, and electrical conductors connecting the first detecting elements in parallel and the second detecting elements in parallel such that the sum of the electrical signals produced by the photoelectric detecting elements are used to generate digital signals describing the rotational movement of the shaft with respect to the stationary plate.