1,163,257. Control of D.C. motors. RADIO CORPORATION OF AMERICA. 25 June, 1968 [26 June, 1967], No. 30211/68. Heading H2J. [Also in Division G3] A tape transport system includes a first motor 1 providing constant mechanical power to drive the tape and a second motor 2 acting as a brake and providing a torque proportional to changes in speed of the tape so as to stabilize the speed. The drive motor 1 is a serieswound motor fed from a constant voltage source source 9; the brake motor 2 is a shunt wound motor connected across the armature 5 of the drive motor 1. The motor 2 has large armature reactance and therefore provides a braking torque which is independent of its speed (Fig. 3, not shown) but dependent on the applied voltage Vg which varies with the speed of motor 1; the system thus maintains constant speed and tension in the tape 8. The motor 2 may have an additional series field coil or the field coil may be separately energized (Figs. 5, 6, not shown) to provide suitable characteristics. Switching may be introduced to reverse the roles of the two motors (Figs. 7, 8, not shown) and thus reverse the direction of movement of the tape.
展开▼
