Three motor tape drive mechanism

Claim 2

In a tape transport mechanism operable in any of several operational modes and having a d.c. forward drive motor coupled between a source of d.c. operating potential and a reference potential for driving an associated take-up reel to transport a tape coupled thereto in an arbitrarily designated forward direction and further having a d.c. rewind motor coupled between said d.c. source and said reference potential for driving an associated rewind reel to transport said tape in the opposite direction and rewind said tape onto said rewind reel, apparatus comprising: motor control means for selectively varying the current through said forward drive motor and said rewind motor to correspondingly vary the respective torques developed by said motors and applied to said reels, said motor control means including a first semiconductor device shunting said forward drive motor and a second semiconductor device interposed in series with the parallel combination of said first semiconductor device and said forward drive motor between said d.c. source and said reference potential and further including a third semiconductor device shunting said rewind motor and a fourth semiconductor device interposed in series with the parallel combination of said third semiconductor device and said rewind motor between said d.c. source and said reference potential, said first and third semiconductor devices normally conductive to respectively shunt said forward drive motor and said rewind motor with a low impedance current path during a first mode of operation so that substantially all of said current flows through said first and third transistors rather than through said forward drive and rewind motors to disable said motors; and switch means coupled to said semiconductor devices for selectively varying the conduction level of said semiconductor devices during a second mode of operation, including means for selectively reducing the conduction level of said first and third semiconductor devices so as to enable said current to flow through said motors and means for simultaneously selectively varying the impedance of said second and fourth semiconductor devices to correspondingly vary the respective currents through said motors so that one of said motors is more fully conducting than the other of said motors, said motor which is more fully conducting being dominant over said other motor to transport said tape in the direction determined by said dominant motor and said other motor opposing the direction of travel of said tape to properly tension said tape between said take-up reel and said rewind reel and braking a respective one of said reels whenever said mechanism is switched from the second operational mode to the first operational mode.

Claim 3

Apparatus in accordance with claim 1 including remote control means comprising transmitter means generating control signals at a location remote from said mechanism and receiver means coupled to said switch means and responsive to said transmitter control signals for generating a particular output signal corresponding to each of the several modes of operation for controlling said switch means to selectively switch said mechanism between the several modes of operation.

Claim 4

Apparatus in accordance with claim 2 wherein said switch means comprises a logic control means having a plurality of drivers which are coupled to said remote control receiver means and a diode switching network interposed between said drivers and said semiconductor devices, said logic control means being responsive to said receiver output signals to selectively enable a different one of said drivers during each particular mode of operation, said enabled driver controlling said diode switching network to selectively vary the bias applied to said semiconductor devices.

Claim 5

Apparatus in accordance with claim 3 wherein each of said semiconductor devices includes a corresponding input electrode and said diode switching network comprises a plurality of diodes, each of said drivers being coupled to said input electrode of each of said semiconductor devices by a corresponding one of said diodes, said enabled driver switching the corresponding ones of said diodes to conduction so as to couple said semiconductor input electrodes to said reference potential to selectively vary the bias applied to said semiconductor devices and corresondingly vary the respective currents conducted therethrough.

Claim 6

Apparatus in accordance with claim 4 wherein said diode switching network includes a resistive element interposed in series with said diode which is coupled to the input electrode of said semiconductor device coupled in series with said other motor during a first particular mode of operation and wherein the input electrodes of the others of said semiconductor devices are coupled directly to said reference potential to cause said dominant motor to be fully conductive while said other motor is only partially conductive to exert a force on said tape in the direction of travel opposite to that of said dominant motor.

Claim 7

Apparatus in accordance with claim 4 wherein said diode switching network includes a plurality of resistive elements, each of said resistive elements being interposed in series with a corresponding one of said diodes during a second particular mode of operation to resistively couple said semiconductor inputs to said reference potential, said semiconductor devices being biased so that said dominant motor is more conductive than said other motor, said other motor exerting a force on said tape in the direction of travel opposite to that of said dominant motor.

Claim 8

Apparatus in accordance with claim 3 wherein said receiver means comprises a plurality of remotely controlled switch devices, each of said switches being selectively enabled to produce an output signal corresponding to a particular one of the several modes of operation, and wherein said logic control means comprises a corresponding plurality of AND logic gate means interposed between corresponding ones of said remotely controlled switch devices and corresponding ones of said drivers to selectively enable said drivers, each of said AND gate means having an output coupled to said corresponding driver and an input coupled to the outputs of the others of said AND gate means to prevent the enablement of said AND gate means and said corresponding driver whenever a different one of said AND gate means is already enabled.

Claim 9

Apparatus in accordance with claim 7 wherein said logic control means includes a plurality of NOR logic gate means, each of said NOR gate means being associated with a corresponding one of said AND gate means and having inputs coupled to the respective outputs of the others of said AND gate means and an output coupled to said corresponding AND gate means to maintain said corresponding AND gate means in a disabled state as long as any of said other AND gate means is enabled.

Claim 10

Apparatus in accordance with claim 8 wherein said logic control means includes delay means interposed between said NOR gate means output and said corresponding AND gate means to delay the enabling of said corresponding AND gate means for a predetermined time interval after all of said other AND gate means are disabled.

Claim 11

In a tape transport mechanism operable in any of several operational modes and having a d.c. forward drive motor coupled between a source of d.c. operating potential and a reference potential for driving an associated take-up reel to transport a tape coupled thereto in an arbitrarily designated forward direction and further having a d.c. rewind motor coupled between said d.c. source and said reference potential for driving an associated rewind reel to transport said tape in the opposite direction and rewind said tape onto said rewind reel, apparatus comprising: motor control means for selectively varying the current through said forward drive motor and said rewind motor to correspondingly vary the respective torques developed by said motors and applid to said reels, said motor control means including a first semiconductor device shunting said forward drive motor and a second semiconductor device interposed in series with the parallel combination of said first semiconductor device and said forward drive motor between said d.c. source and said reference potential and further including a third semiconductor device shunting said rewind motor and a fourth semiconductor device interposed in series with the parallel combination of said third semiconductor device and said rewind motor between said d.c. source and said reference potential, said first and third semiconductor devices normally conductive to respectively shunt said forward drive motor and said rewind motor with a low impedance current path during a first mode of operation so that substantially all of said current flows through said first and third transistors rather than through said forward drive and rewind motors to disable said motors; remote control means including transmitter means generating control signals at a location remote from said mechanism and receiver means responsive to said transmitter control signals to selectively switch said mechanism between several modes of operation, said receiver means comprising a plurality of remotely controlled switch devices, each of said switches being selectively enabled to produce an output signal corresponding to a particular one of the several modes of operation; logic control means comprising a plurality of drivers and a corresponding plurality of AND logic gate means interposed between corresponding ones of said remotely controlled switch devices and corresponding ones of said drivers to selectively enable said drivers responsive to one of said switches being enabled, each of said AND gate means having an output coupled to said corresponding driver and an input coupled to the outputs of the others of said AND gate means to prevent the enablement of said AND gate means and said corresponding driver whenever a different one of said AND gate means is already enabled; and diode switching means comprising a plurality of diodes, each of said drivers being coupled to each of said semiconductor devices by a corresponding one of said diodes, said enabled driver switching the corresponding ones of said diodes to conduction so as to couple said semiconductor to said reference potential to selectively vary the bias applied to said semiconductor devices and correspondingly vary the respective currents conducted therethrough.

Claim 12

In a tape transport mechanism operable in any of several operational modes and having a d.c. forward drive motor coupled between a source of d.c. operating potential and a reference potential for driving an associated take-up reel to transport a tape coupled thereto in an arbitrarily designated forward direction and further having a d.c. rewind motor coupled between said d.c. source and said reference potential for driving an associated rewind reel to transport said tape in the opposite direction and rewind said tape onto said rewind reel, apparatus comprising: motor control means for selectively varying the current through said forward drive motor and said rewind motor to correspondingly vary the respective torques developed by said motors and applid to said reels, said motor control means including a first semiconductor device shunting said forward drive motor and a second semiconductor device interposed in series with the parallel combination of said first semiconductor device and said forward drive motor between said d.c. source and said reference potential and further including a third semiconductor device shunting said rewind motor and a fourth semiconductor device interposed in series with the parallel combination of said third semiconductor device and said rewind motor between said d.c. source and said reference potential, said first and third semiconductor devices normally conductive to respectively shunt said forward drive motor and said rewind motor with a low impedance current path during a first mode of operation so that substantially all of said current flows through said first and third transistors rather than through said forward drive and rewind motors to disable said motors; remote control means including transmitter means generating control signals at a location remote from said mechanism and receiver means responsive to said transmitter control signals to selectively switch said mechanism between several modes of operation, said receiver means comprising a plurality of remotely controlled switch devices, each of said switches being selectively enabled to produce an output signal corresponding to a particular one of the several modes of operation; logic control means comprising a plurality of drivers and a corresponding plurality of AND logic gate means interposed between corresponding ones of said remotely controlled switch devices and corresponding ones of said drivers to selectively enable said drivers responsive to one of said switches being enabled, each of said AND gate means having an output coupled to said corresponding driver and an input coupled to the outputs of the others of said AND gate means to prevent the enablement of said AND gate means and said corresponding driver whenever a different one of said AND gate means is already enabled; and diode switching means comprising a plurality of diodes, each of said drivers being coupled to each of said semiconductor devices by a corresponding one of said diodes, said enabled driver switching the corresponding ones of said diodes to conduction so as to couple said semiconductor to said reference potential to selectively vary the bias applied to said semiconductor devices and correspondingly vary the respective currents conducted therethrough.