Automatic detecting and controlling apparatus for polaroid rotating angle

The utility model relates to an automatic detecting and controlling apparatus for a rotating angle of a polaroid sheet, which is mainly formed by that a mounting supporting frame, a shaft angle encoder, a motor, a driving gear wheel, a driven gear wheel, a driving wheel shaft, a driven wheel shaft, a seat for a polaroid sheet, a polaroid sheet, a light shielding sheet, an optical coupler and an interface circuit of a computer are jointly connected. The device of the utility model can automatically detect an actual rotating angle of the polaroid sheet in real time, and enables the polaroid sheet to be accurately positioned at a certain rotating angle; the utility model has higher detecting precision and positioning precision.