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Motor Control Circuit

IP.com Disclosure Number: IPCOM000075462D
Original Publication Date: 1971-Sep-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Lucero, JC: AUTHOR [+2]

Abstract

A single capstan reel-to-reel tape drive includes a motor control circuit providing a first acceleration in the first direction of rotation and a slower acceleration exponentially changing to the first acceleration in the reverse direction. The differing accelerations accommodate reel inertia. This arrangement is particularly advantageous when tape 30 is being pushed over head 31 toward reel 32. A slow or soft accelerating capstan 33 enables reel 32 to maintain tension in tape 30 by accelerating faster than the capstan. Such tension maintains the tape in transducing relationship to head 31 during acceleration.

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Motor Control Circuit

A single capstan reel-to-reel tape drive includes a motor control circuit providing a first acceleration in the first direction of rotation and a slower acceleration exponentially changing to the first acceleration in the reverse direction. The differing accelerations accommodate reel inertia. This arrangement is particularly advantageous when tape 30 is being pushed over head 31 toward reel 32. A slow or soft accelerating capstan 33 enables reel 32 to maintain tension in tape 30 by accelerating faster than the capstan. Such tension maintains the tape in transducing relationship to head 31 during acceleration.

Motor 10 is driven at a constant velocity after starting by amplifier 11. Control voltage is supplied through terminal 12 as a velocity set point for motor 10. First feedback circuit 13 determines acceleration of motor 10 in the first direction of motion.

When motor 10 is to be accelerated in the opposite direction, logic circuits 14 supply a step voltage signal 15 to acceleration controlling circuit 16. Capacitor 17 differentiates the step providing signal 18 to the base of switching transistor 19. The voltage on the base of transistor 19 exponentially decays to discharge path including resistors 20, 21, base-emitter portion of transistor 19, and the input portion of amplifier 11. When voltage 18 has decayed to a certain point, switching transistor 19 turns off. Elapsed time between the peak of voltage 18 and the switch-off point is t...