HEAD DRUM OF VIDEO TAPE RECORDER

摘要

PURPOSE:To obtain a revolving position signal of double phases and to decrease the number of component parts to obtain a simple constitution for a head drum of a video tape recorder, by forming a projected part with a 180 deg. pitch at the outer circumferential part of a rotor yoke and providing a projected part detecting means at a fixed side opposed to the projected part. CONSTITUTION:A fixed side 7-1 and a stator yoke 5' are formed into a monolithic structure with a ferrite magnetic matter and set opposedly to a rotary side 7-2 of a rotary transformer 7. A stator armature consisting of an armature coil group 6 is fixed to the lower surface of the yoke 5' and set as opposed to the surface of a field magnet 10. Projected parts 9'a and 9'b are formed in a body at the outer circumferential part of a rotor yoke 9' with a 180 deg. pitch. A detecting element 16 for parts 9'a and 9'b is provided at the inner surface part of a recess part 2a of a lower drum 2 forming a fixed side opposed to the part 9'a or 9'b. As a result, a revolving position signal of double phases A and B is obtained.