Tape transport reel servo system

Claim 1

In a tape transport system: first and second rotatable tape storage reels having tape wound thereon and extending therebetween; first and second bidirectional motors being drivingly connected to said first and second reels, respectively; means associated with said first reel for storing a supply of said extended tape, said supply falling within a predetermined range occurring between a first and a second valve; first means for energizing said first motor in either the forward or reverse direction to control said tape supply within said predetermined range, said first means comprising: tape supply storing means comprising: a rotatable multiple loop tape storage arm having associated therewith a tape loop supply which varies with the arm''s angular position; means for detecting the angular position of said arm including: a cam located at the center of rotation of said arm and rotatable therewith, and first and second microswitches responsive to the motion of said cam, each switch including normally open and normally closed contacts, said first and second microswitches being actuated by said cam when said tape supply reaches said first and second predetermined values, respectively, and means rotatably biasing said arm in a direction which tends to cause said tape loop supply to increase; means--including a forward energizing conduction path comprising the series combination of a first reference potential, a first forward-biased diode, the normally closed contact of said second microswitch, the operated contact of said first microswitch, and a second reference potential less than said first reference potential--responsive to said tape supply storing means for forwardly energizing said first motor when the supply is below said first predetermined value; means--including a reverse energizing conduction path comprising the series combination of said first reference potential, a second forward-biased diode, the normally closed contact of said first microswitch, the operated contact of said second microswitch, and said second reference potential-for reversely energizing said first motor when the supply is above said second predetermined value greater than said first value; said first motor being deenergized and therefore allowed to continue coasting in the forward direction when the supply is within said first and second predetermined values; means associated with said first reel for maintaining tape tension and a substantially constant value independent of tape supply; and second means for continuously energizing said second motor in a forward direction only to rapidly transfer tape from said first reel to said second reel.