Patent ID: 6851639
Filing Date: 2005-02-08
Classification: G11B

Abstract:
1. A tape medium running device, for reducing a first winding speed to a second speed lower than said first speed as a function of a winding diameter of a magnetic recording tape wound around a reel, at a position near an end of such magnetic recording tape being wound from one reel to another reel at the first speed, the device comprising: a motor; a rotation detecting unit for detecting a signal of a frequency proportionate to a rotation speed of the motor; a take-up reel which is wound with one end of such magnetic recording tape and rotates in synchronization with a rotation speed of the motor; a supply reel which is wound with the other end of such magnetic recording tape; a winding diameter detecting unit for detecting a winding diameter of such magnetic recording tape wound around the supply reel; a reference high speed calculating unit for outputting a first reference speed for setting the rotation speed of the motor at the first speed; a reference low speed calculating unit for outputting a second reference speed for setting the rotation speed of the motor at the second speed; a winding diameter comparing unit for comparing an output from the winding diameter detecting unit and a winding diameter comparison reference value previously set in the winding diameter comparing unit; an abnormality detecting unit for detecting abnormality based on an output from the winding diameter detecting unit; a reference speed setting unit for outputting an output from the low reference speed calculating unit as a third reference speed when an output from the abnormality detecting unit indicates abnormality or when an output from the winding diameter detecting unit is detected to be smaller than the winding diameter comparison reference value, and outputting an output from the high reference speed calculating unit as a fourth reference speed in other cases; a speed control unit for outputting a rotation instruction signal based on an output from the rotation detecting unit and an output from the reference speed setting unit, and a drive unit for rotating the motor in response to the rotation instruction signal, the abnormality detecting unit comprising: a winding diameter change detecting unit for detecting a change in winding diameter on a basis of a winding diameter detected by the winding diameter detecting unit; and an abnormal winding diameter change judging unit for judging whether the winding diameter detected by the winding diameter detecting unit is correct or not on a basis of a winding diameter change comparison reference and a change in diameter detected by the winding diameter change detecting unit, and notifying the reference speed setting unit of an occurrence of abnormality.