Patent ID: 6742641
Filing Date: 2004-06-01
Classification: F16D,G11B

Abstract:
A rotational driving apparatus of a magnetic tape device comprising:a clutch mechanism; a rotation transmission path change-over gear; a feed reel; and a take-up reel, wherein a rotation of a motor is transmitted to the clutch mechanism and a rotation of the clutch mechanism is selectively transmitted to the feed reel or the take-up reel via the rotation transmission path change-over gear, the clutch mechanism can be selectively provided with a first clutch mechanism adapted to decelerate the rotation of the motor at a first reduction ratio and transmit the resultant rotation to the change-over gear, and a second clutch mechanism adapted to decelerate the rotation of the motor at a second reduction ratio and transmit the resultant rotation to the change-over gear, the first clutch mechanism comprises: a first shaft; a first pulley supported rotatably on the first shaft and adapted to receive the rotation of the motor; a first clutch output gear supported rotatably on the first shaft and meshed with the change-over gear; a first constant torque transmission member provided between the first pulley and first clutch output gear and adapted to transmit torque of the first pulley lower than a predetermined level to the first clutch output gear; and a clutch member adapted to transmit a rotation of the first pulley to the first clutch output gear directly or via the first constant torque transmission member, and the second clutch mechanism comprises: a second shaft; a second pulley supported rotatably on the second shaft; a second clutch output gear supported rotatably on the second shaft and meshed with the change-over gear; a second constant torque transmission member provided between the second pulley and second clutch output gear and adapted to transmit torque of the second pulley lower than a predetermined level to the second clutch output gear; and a speed change clutch member provided close to the second shaft and adapted to transmit a rotation of the second pulley to the second clutch output gear directly or via the second constant torque transmission member with a speed of the rotation changed.