PURPOSE: To miniaturize the rotary cylinder and to prevent disconnection of its coil and to enhance the production efficiency and reliability by drawing out a transformer coil into a groove on a bottom surface provided on an outside transformer core of the rotary cylinder without bulging out and positioning and fixing an FP substrate in a groove on an outside the core.

CONSTITUTION: The FP substrate 2 is positioned and wound and stuck to an FP substrate fitting groove provided on the outside transformer core 1 of the rotary cylinder 4, and lands 41 and 42 are soldered and connected with each other. A coil end of the transformer coil 3 is drawn out through a transformer coil drawing groove 16 provided on the bottom surface of the core 1, so as not to bulge out of the end surface 10. This is connected via a transformer coil of the substrate 2, HP substrate connecting lands 8 and 14 and a conductive body 18 to a head coil 11 by soldering, etc., through a head coil of an HP substrate 6 and FP substrate connecting transfomers 13 and 12. By this method, the coil 3 is not cut off by friction with a fixed cylinder due to rotation of the cylinder 4, and the rotary cylinder is miniaturized, and the substrates 2 and 6 are easily and securely fitted and connected, thereby the production efficiency and the reliability are enhanced.