A rotary head cylinder of a rotary head assembly includes a first projection for reducing jitter. The first projection is smoothly formed in the vicinity of a point where a tape is separated from a fixed cylinder and is extended in a lengthwise direction of the tape. A second projection is provided for increasing a restricting force on an upper edge of the tape in a direction toward a surface of the fixed cylinder. The second projection is smoothly formed in the vicinity of a lower edge of the tape at the same point on the fixed cylinder and is extended in the lengthwise direction of the tape.

A head drum assembly for a tape recorder includes a stationary drum, a rotary drum, a magnetic head installed in the rotary drum for scanning a traveling magnetic tape, and at least one vibration absorbing unit installed in the stationary drum for absorbing vibrations associated with the traveling magnetic tape. The head drum assembly absorbs vibrations via a vibration absorbing element elastically biased to protrude toward the outer circumferential surface of the stationary drum by a spring installed in an opening of a portion of the stationary drum such that the vibration absorbing element makes contact with the magnetic tape. As the vibration absorbing element makes contact with the traveling magnetic tape, it gives appropriate tension to the magnetic tape to dampen any vibration created therefrom.

To lower the coefficient of static friction of the circumferential surface of the guide or drum constituting the magnetic tape apparatus. A flat portion is formed between peak portions. The peak portions and flat portion are formed so that the relationship: a'<a is satisfied, where "a" represents a distance between the ridges of the peak portions, i.e., pitch of the peak portions, and "a'" represents a bottom width of the peak portions. When this relationship is satisfied between the peak portions and the flat portion, the total area of the meniscuses formed between the magnetic tape and the peak portions can be reduced, thus making it possible to lower the coefficient of static friction.

Disclosed herein is a magnetic tape unit having a magnetic head for reading and writing data from and onto a magnetic tape. The magnetic tape is traveled in contact with the magnetic head during a read/write operation of the magnetic head. During a rest period where the read/write operation of the magnetic head is not performed, a reciprocating motion of the magnetic tape by a small distance is performed with a predetermined period. A temperature in the vicinity of the magnetic head is detected by a temperature sensor. The predetermined period is changed according to the temperature detected by the temperature sensor. Accordingly, the adhesion of the magnetic tape to the magnetic head can be well prevented irrespective of the temperature inside the tape unit.