ROTATION DETECTION DEVICE FOR MAGNETIC RECORDING/ REPRODUCING DEVICE

摘要

PURPOSE: To surely detect rotation of a reel base with simple constitution related to a rotation detection device for a magnetic recording/reproducing device running a magnetic tape housed in a cassette and performing recording/ reproducing. CONSTITUTION: Projections 8 are formed at even intervals on the same circumference on a bottom surface of a reel base 6. A light emitting part 10 and a light receiving part 11 are disposed to face oppositely while holding a path through which the projections 8 pass therebetween, and when the reel base 6 is rotated, since light from the light emitting part 10 is shielded by the projections 8 periodically, the rotation of the reel base 6 is detected surely.