Abstract: Aiming at the problem that the signal in the measurement of the backEMF coefficient of galvanometer scanner is difficult to be obtained, a method was proposed that make the galvanometer rotor produce velocity fluctuation in its limited angle and through the position feedback voltage signal output by the position detector to obtain the rotor angular velocity indirectly. Experiments were carried out on domestic galvanometer scanner, oscilloscopes were used to collect position feedback signals with shortterm stable angular velocity and backEMF signals in stator coils. The signal was processed to obtain the value of rotor angular velocity and the back EMF effective value. Finally, the backEMF coefficients was calculated. The results show that the obtained backEMF coefficient is stable at different angular velocities, and the final result is ke=0.007 8 V/(rad/s). The feasibility of the measurement method is verified by experiments.
Key words: galvanometer scanner; position detector;  RMS value of the backEMF; backEMF coefficient