Includes both grating type and code disc.

Grating sensor using grating to form moire fringe to convert the angular displacement of photoelectric signal grating has two pieces, one for a fixed grating, the other for loading on the dial shaft moving grating. Analyte added on the bearing through the force transmission lever system make the dial shaft rotation, driven in a moving grating, the moire fringe also move. Using photocell, converting circuit and display instrument, can calculate the shift number of moire fringe, measure the size of the grating Angle of rotation, so as to determine the quality of analyte and read.

Code disc sensor encoder (symbol) is a piece of transparent glass on the dial shaft, bearing according to certain coding method of black and white code. Analyte added on the bearing of a leverage force through the dial shaft rotates, encoder has turned a certain Angle. Photovoltaic cells will receive light signals into electrical signals through the encoder, and then by the digital processing circuit, finally on the display shows the number of measured quality representative. Photoelectric sensor was mainly used in mechanical and electrical combination scales.