Failsafe system for energizing the capstan motor of a magnetic tape transport system

Claim 2

In a magnetic tape transport system, the combination comprising: a. at least one relatively high inertia reel means adapted for receiving or dispensing a roll of magnetic tape; b. voltage generating means coupled to said reel means for producing a voltage varying according to the velocity of rotation of said reel means; c. a relatively low inertia capstan motor for controlling the velocity of the magnetic tape passing over a magnetic head; and d. switching means intercoupled between said voltage generating means and said capstan motor, said switching means being adapted to automatically couple said voltage varying according to the velocity of rotation of said reel means to said capstan motor upon the loss of power being supplied to said capstan motor for causing said capstan motor to continue to rotate in the same direction as prior to the loss of power with a velocity of rotation in accordance with the voltage varying according to the velocity of rotation of said reel means.

Claim 3

The magnetic tape transport system as defined by claim 1 wherein said voltage generating means is a reel motor for rotating said reel means, and said voltage varying according to the velocity of rotation of said reel means is the back electromotive force generated by said rotating reel motor when said reel motor is de-energized.

Claim 4

The magnetic tape transport system as defined by claim 1 further comprising dissipating means coupled to said switching means, said dissipating means being automatically coupled to said voltage generating means upon the loss of power being supplied to said capstan motor.

Claim 5

The magnetic tape transport system as defined by claim 3 wherein said dissipating means is a resistor, and wherein said switching means automatically couples said resistor across said voltage generating means upon the loss of power being supplied to said capstan motor.

Claim 6

The magnetic tape transport system as defined by claim 1 wherein said switching means intercoupled between said voltage generating means and said capstan motor is an electromagnetic relay having first and second movable contacts and a relay coil, said relay coil being normally energized by the source of power for suppLying said capstan motor and being deenergized upon the loss of power being supplied to said capstan motor, said voltage varying according to the velocity of rotation of said reel means being coupled through the first and second movable contacts of said electromagnetic relay to said capstan motor when said relay coil is de-energized.

Claim 7

In a tape transport system, the combination comprising: a. at least one reel means adapted for receiving or dispensing a roll of magnetic tape; b. reel motor means mechanically coupled to said reel means for rotating said reel means; c. a capstan motor for transporting the tape from said reel means at a controlled velocity, said reel means and said reel motor means possessing an appreciably higher moment of inertia than the moment of inertia of said capstan motor; and d. switching means electrically coupled to said reel motor means and said capstan motor means, said switching means being responsive to a source of electrical power for supplying electrical power to said reel motor means and said capstan motor means during normal operation of said tape transport system, said switching means being further responsive to a loss of electrical power from said source for automatically coupling the back electromotive force generated by said rotating reel motor to said capstan motor, said back electromotive force being coupled to said capstan motor so that said capstan motor is caused to continue to rotate in the same direction as prior to the loss of power with a velocity of rotation in accordance with the velocity of rotation of said reel means.

Claim 8

In a tape transport system, the combination comprising: a. at least one reel means adapted for receiving or dispensing a roll of magnetic tape; b. reel motor means mechanically coupled to said reel means for rotating said reel means; c. a capstan motor for transporting the tape from said reel means at a controlled velocity, said reel means and said reel motor means possessing an appreciably higher moment of inertia than the moment of inertia of said capstan motor; and d. switching means electrically coupled to said reel motor means and said capstan motor means, said switching means being responsive to a source of electrical power for supplying electrical power to said reel motor means and said capstan motor means during normal operation of said tape transport system, said switching means being further responsive to a loss of electrical power from said source for automatically coupling the back electromotive force generated by said rotating reel motor to said capstan motor, said back electromotive force being coupled to said capstan motor so that said capstan motor is caused to continue to rotate in the same direction as prior to the loss of power with a velocity of rotation in accordance with the velocity of rotation of said reel means.

Claim 9

The tape transport system as defined by claim 6 further comprising a resistor means coupled to said switching means, said switching means automatically coupling said resistor means to said reel motor means upon a loss of electrical power from said source to provide dynamic braking of said reel motor means.

Claim 10

The tape transport system as defined by claim 6 wherein said reel motor means is a permanent-magnet direct current motor and said capstan motor is a low-inertia direct current motor.

Claim 11

The tape transport system as defined by claim 8 wherein said reel motor means and said capstan motor each include an electrical winding, and wherein said switching means responsive to a loss of electrical power from said source automatically couples the electrical winding of said reel motor means to the electrical winding of said capstan motor.

Claim 12

The tape transport system as defined by claim 6 wherein said tape is magnetic, and wherein said capstan motor operates to transport the magnetic tape from said reel means over the face of a magnetic head at a controlled velocity.