Plural motor tension controlled tape drive

Claim 2

Apparatus for driving a tape-shaped record carrier between first and second tape reels comprising, two direct-current motors which each serve to drive a tape reel, a source of supply voltage having a pair of terminals, circuit means coupling said motors to the supply source for controlling said motors for rapid and simultaneous unwinding of the record carrier from one reel and winding it on to the other reel and vice versa such that the torque produced by the motor of the take-up reel is opposed by the torque produced by the motor of the take-off reel, said circuit means including means connecting one end of each of the two motor windings together and to one oF the terminals of said supply source via a common impedance during a fast forward and rewind cycle and the other end of the winding of the take-up motor to the other terminal of the supply source and the other end of the winding of the take-off motor to said other terminal of the supply source via a voltage-dependent element so that the voltage across said voltage-dependent element is equal to the sum of the voltages across the two motor windings, said element having an impedance characteristic which, at least above a given voltage level, decreases with increasing voltage.

Claim 3

Apparatus as claimed in claim 1 wherein the voltage-dependent element comprises a Zener diode.

Claim 4

Apparatus as claimed in claim 2, further comprising a second Zener diode connected in series opposition with the first Zener diode, the said circuit means directly connecting the series-opposition combination of Zener diodes to the other ends of the windings of the two motors.

Claim 5

Apparatus as claimed in claim 3 wherein the two Zener diodes are connected with their polarities arranged so that the Zener diode coupled to the winding of the take-off motor is connected in the forward direction for the voltage set up across the two motor windings.

Claim 6

Apparatus as claimed in claim 4, wherein the junction point of the two Zener diodes is connected via a switch to the one ends of the two motor windings connected to the common impedance, and means for selectively closing the switch to provide a short-circuit path across the winding of the take-off motor via the switch and one Zener diode for rapidly braking the movement of the record carrier.

Claim 7

Apparatus as claimed in claim 4 further comprising means connecting the junction point of the two Zener diodes to a point of constant potential via a resistor and a switch which is closed during a play operation.

Claim 8

Apparatus as claimed in claim 1 wherein the common impedance comprises a resistor.

Claim 9

Apparatus as claimed in claim 7 further comprising a rectifying element, and means connecting said one end of the motor windings to a point of constant potential via said rectifying element so that for a play operation the supply current for the take-up motor winding is supplied from said point of constant potential via the rectifying element and so that during the wind operation the rectifying element is normally cut off and begins conduction only if the voltage across the winding of the take-up motor drops below a given minimium value whereby the rectifying element passes a supply current for the take-up motor winding.

Claim 10

A tape drive apparatus comprising, a source of supply voltage having first and second output terminals, first and second motors having first and second windings, respectively, and adapted to drive first and second tape reels, respectively, means connecting a first end of the first winding to a first end of the second winding to form a junction point therebetween, second means connecting the junction point to the first terminal of the supply source via a common impedance means, voltage dependent means, and switching means coupled to the voltage dependent means and to the second ends of the first and second windings and having first and second states, said first state connecting the second end of the first winding to the second terminal of the supply source and the second end of the second winding to the second terminal of the supply source via said voltage dependent means, said second state connecting the second end of the second winding to the second terminal of the supply source and the second end of the first winding to the second terminal of the supply source via said voltage dependent means, whereby the sum of the voltages across said first and second windings is held constant and is applied across said voltage dependent means to maintain the sum of the speeds of the first and second motors constant.

Claim 11

A tape drive apparatus comprising, a source of supply voltage having first and second output terminals, first and second motors having first and second windings, respectively, and adapted to drive first and second tape reels, respectively, means connecting a first end of the first winding to a first end of the second winding to form a junction point therebetween, second means connecting the junction point to the first terminal of the supply source via a common impedance means, voltage dependent means, and switching means coupled to the voltage dependent means and to the second ends of the first and second windings and having first and second states, said first state connecting the second end of the first winding to the second terminal of the supply source and the second end of the second winding to the second terminal of the supply source via said voltage dependent means, said second state connecting the second end of the second winding to the second terminal of the supply source and the second end of the first winding to the second terminal of the supply source via said voltage dependent means, whereby the sum of the voltages across said first and second windings is held constant and is applied across said voltage dependent means to maintain the sum of the speeds of the first and second motors constant.

Claim 12

Apparatus as claimed in claim 9 wherein said voltage dependent means comprises a zener diode.

Claim 13

Apparatus as claimed in claim 9 wherein said voltage dependent means comprises first and second zener diodes connected in series opposition between the second ends of said first and second windings.

Claim 14

Apparatus as claimed in claim 11 wherein said common impedance means comprises a resistor.

Claim 15

Apparatus as claimed in claim 11 further comprising a switch connected between the junction point of the first and second zener diodes and said junction point between the first and second windings, and means for selectively operating the switch to an open condition during the play and wind operations and to a closed condition to initiate a motor braking operation to stop the movement of the tape.

Claim 16

Apparatus as claimed in claim 9 further comprising diode means coupled to the second ends of said first and second windings and to the second terminal of said supply source via said switching means during a stop condition of the tape thereby to provide paths for currents of opposite polarities to flow through said first and second windings to provide opposed motor torques for maintaining tension in the tape.

Claim 17

Apparatus as claimed in claim 9 wherein said second connecting means comprises a controlled switch coupled between the junction point and the common impedance means.

Claim 18

Apparatus as claimed in claim 15 further comprising a diode connecting said junction point to a point of constant voltage, means for selectively operating the controlled switch into a closed condition during a wind operation and into an open condition during a play operation, said diode being normally conductive during a play operation to supply current to said motor windings and being normally cut-off during a wind operation until the voltage across the winding of the take-up motor drops below a given level whereupon the diode conducts to supply additional current to the take-up motor winding from said point of constant voltage.

Claim 19

Apparatus as claimed in claim 16 wherein said voltage dependent means comprises first and second zener diodes connected in series opposition between the second ends of said first and second windings.

Claim 20

Apparatus as claimed in claim 17 further comprising diode means coupled to the second ends of the said first and second windings, a second controlled switch, and means including said second controlled switch for coupling said diode means to the second terminal of the supply source, said controlled switch being selectively operated into cut-off during a wind or play operation and into conduction during a stop operation to provide current paths to allow the flow of opposed currents through said first and second windings.