Dynamic skew correction for rotating head magnetic recorder

In a rotating head magnetic recording device having head-to-track alignment detecting means for detecting the pitch or positional error and the skew error between the data track and the head path, and having means for moving the tape in response to the pitch error from said detecting means to center the head path with the data track, apparatus for dynamically changing the data track angle relative to the head path in response to the skew error, said apparatus comprising:

• a soft bearing mandrel flanking both sides of the rotating head for supporting the tape in the region of the head path;
• entry and exit guides adjacent the region of the head path for guiding the tape as the tape enters and exits the region of the head path;
• means responsive to the skew error for changing the lateral separation of said entry and exit guides without changing the mandrel axis angle relative to said entry and exit guides whereby the angle of the tape is changed in the region of the head path and the data track is aligned with the head path;
• said soft bearing mandrel distributing tape tension uniformly across the tape width, when lateral separation of said entry and exit guides is changed by said changing means, whereby the data track can be aligned with the head path without introducing distortion in the data track.

Method for dynamically correcting skew error between the data track on magnetic tape helically wrapped about the path of a rotating head with entry and exit guides at the entry and exit of the helical wrap comprising the steps of:

• detecting misalignment between the head path and the previous data track;
• calculating the skew error from the detected misalignment;
• adjusting the entry and exit guides in response to the skew error to change the helix angle of the tape about the head path, said adjusting step being performed during the portion of the rotating cycle when the magnetic head is between data tracks whereby the present data track is dynamically adjusted for skew error based upon detected misalignment between the head path and the previous data track;
• said adjusting step further comprising the steps of:
• holding one of the guides at a fixed position;
• moving the other guide laterally to change the guide spacing between the entry and exit guide reference edges so that the helix angle of the tape about the head path is changed without changing the head path axis angle relative to said entry and exit guides.