Accurate-return back locking knob for lockset panel

The back locking knob comprises a frame body, the front face of the frame body is connected with a lock column in a rotating mode, the front end of the lock column penetrates through the front face of the frame body and is connected with a back locking knob body in a bolting mode, clamping grooves are formed in the four corners of the surface of the lock column, and a hollow plate is arranged on the surface of the lock column. The clamping block corresponds to the clamping groove in the surface of the lock column, when the back locking knob body is rotated, the lock column extrudes the clamping block to extrude the reset spring in the groove body until the clamping block and the clamping groove are clamped and fixed, and therefore positioning is accurate, a user can see whether back locking is conducted or not at a glance, the back locking knob is more attractive, and convenience is improved; the infrared device detects, indicates and starts the motor at the same time, the motor drives the gear to rotate, the