Automatic magnetic tape information retrieval system with speed and position tape drive control

Claim 2

In a magnetic tape information retrieval system, the combination of: a magnetic tape having segments of recorded information on at least one information track and a control track on the tape coextensive with said information track, said control track having consecutively numbered control pulses, said control pulses having a distinguishable portion occurring at regular intervals recorded thereon and defining a succession of address segments along the control track, tape drive means for moving said magnetic tape in either direction, means for reproducing said control pulses, a tape drive control connected to said tape drive means including means producing a train of periodic reference pulses, a speed control circuit operative in the run mode including means for detecting differences in frequency between said reproduced control pulses and the train of periodic reference pulses, and means for generating a difference signal to vary the speed of said tape drive means whereby the positions of said control and reference pulses are synchronized, and a position control circuit operative in the search mode including means producing timing pulses synchronized with tape speed, means responsive to said synchronized timing pulses for decoding said reproduced control pulses independently of the tape speed, and means for comparing the decoded control pulses with the next selected address segment number, and means for generating a difference signal of a polarity and magnitude related to the direction and distance respectively to said next selected address segment number on said magnetic tape.

Claim 3

In a magnetic tape retrieval system according to claim 1 wherein said reference pulses are generated by a clock.

Claim 4

In a magnetic tape retrieval system according to claim 1 wherein said control track pulses are width-modulated with different widths to represent binary numbers ZERO and ONE.

Claim 5

In a magnetic tape retrieval system according to claim 1 wherein said timing pulses are produced by a timing disk driven by the motion of the tape.

Claim 6

In a magnetic tape retrieval system according to claim 4 wherein said position control circuit includes circuit means for counting the timing pulses during the duration of each control pulse so that the control pulses are decoded independently of the tape speed.

Claim 7

In a magnetic tape information retrieval system as set forth in claim 1 including a cue signal recorded on a segment of each information track to identify the exact beginning of each information recording.

Claim 8

In a magnetic tape information retrieval system as set forth in claim 1 wherein said speed control circuit includes frequency divider circuits to change the frequency of the control track pulses and the reference pulses to the same frequency and a frequency and phase comparator circuit to compare the phase and frequency relationships.

Claim 9

In a magnetic tape information retrieval system as set forth in claim 1 wherein said position control circuit includes means for counting the timing pulses during the interval of each control track pulse.

Claim 10

In a magnetic tape information retrieval system the combination of: a magnetic tape having segments of information recordings on information tracks and control pulse recordings on a control track coextensive with the information tracks, said control pulses being coded using two pulse characters representing binary numbers ZERO and ONE to consecutively number uniform address segments arranged along the control track for position control and a third pulse character which together with said binary characters are arranged with equally spaced leading edges for speed control, a control head to reproduce the recorded control track pulses from the tape, tape drive means to move the tape past the control head in either direction, control means connected to said tape drive means for regulating the speed and position of the tape driven by said drive means in response to the control track pulses being reproduced from the tape, said control means including means producing a train of periodic reference pulses, a speed control circuit operative in the run mode and including means for comparing the phase and frequency of the control track pulses and the train of reference pulses and means responsive to said comparing means for adjusting the tape drive to synchronize the phase and frequency of the control and reference pulses; said control means also including a position control circuit operative in the search mode including means producing timing pulses synchronized with tape speed, means responsive to said timing pulses for decoding said reproduced control track pulses independently of tape speed, means for comparing each successive decoded control track address number with a next selected address number and means for generating a difference signal of a polarity and magnitude related to the direction and distance respectively to the next selected number.

Claim 11

In a magnetic tape information retrieval system the combination of: a magnetic tape having segments of information recordings on information tracks and control pulse recordings on a control track coextensive with the information tracks, said control pulses being coded using two pulse characters representing binary numbers ZERO and ONE to consecutively number uniform address segments arranged along the control track for position control and a third pulse character which together with said binary characters are arranged with equally spaced leading edges for speed control, a control head to reproduce the recorded control track pulses from the tape, tape drive means to move the tape past the control head in either direction, control means connected to said tape drive means for regulating the speed and position of the tape driven by said drive means in response to the control track pulses being reproduced from the tape, said control means including means producing a train of periodic reference pulses, a speed control circuit operative in the run mode and including means for comparing the phase and frequency of the control track pulses and the train of reference pulses and means responsive to said comparing means for adjusting the tape drive to synchronize the phase and frequency of the control and reference pulses; said control means also including a position control circuit operative in the search mode including means producing timing pulses synchronized with tape speed, means responsive to said timing pulses for decoding said reproduced control track pulses independently of tape speed, means for comparing each successive decoded control track address number with a next selected address number and means for generating a difference signal of a polarity and magnitude related to the direction and distance respectively to the next selected number.

Claim 12

In a magnetic tape information retrieval system the combination of: a magnetic tape having segments of information recordings on information tracks and a control track coextensive with the information tracks, said control track being divided into tape address segments of equal length, and having a succession of control pulses recorded on the control track, the control pulses being coded using two pulse characteristics representing binary numbers ZERO and ONE to number the tape segments consecutively along the tape and having uniformly spaced leading edges, a control head to reproduce the control pulses from the tape, tape drive means to move the tape past the control head in either direction, clock means to produce periodic reference pulses, timing disk means synchronized with the speed of the tape to generate periodic timing pulses, control circuit means connected to said tape drive means for selectively regulating the movement of said tape drive means in response to the control pulses reproduced from the tape, said control circuit means including a speed logic circuit operable in the run mode and a position control logic circuit operable in the search mode; said speed logic circuit including means for comparing the phase and frequency of the reproduced control pulses with the reference pulses and means responsive to said comparing means for producing an output voltage proportional to any differences between the phase and frequency of the control and reference pulses to control the speed of the tape drive means; said position control logic circuit operable independently of said speed logic circuit including a gate controlled by the reproduced control track pulses to gate the timing disk pulses during each control track pulse, decoder means for counting the timing pulses gated during each timing disk pulse so that the control track pulses are decoded independently of tape speed, a bi-directional shift register loaded by the decoded control track pulses, an address register loaded by the shift register, a selection register loaded by a selected address number corresponding to a particular information recording on the tape, and a comparator logic circuit responsive to the selection register and the address register for generating a difference signal of a polarity and magnitude related to the direction and distance respectively to the next selected address number on said magnetic tape.

Claim 13

In a magnetic tape information retrieval system the combination of: a magnetic tape having segments of information recordings on information tracks and a control track coextensive with the information tracks, said control track being divided into tape address segments of equal length, and having a succession of control pulses recorded on the control track, the control pulses being coded using two pulse characteristics representing binary numbers ZERO and ONE to number the tape segments consecutively along the tape and having uniformly spaced leading edges, a control head to reproduce the control pulses from the tape, tape drive means to move the tape past the control head in either direction, clock means to produce periodic reference pulses, timing disk means synchronized with the speed of the tape to generate periodic timing pulses, control circuit means connected to said tape drive means for selectively regulating the movement of said tape drive means in response to the control pulses reproduced from the tape, said control circuit means including a speed logic circuit operable in the run mode and a position control logic circuit operable in the search mode; said speed logic circuit including means for comparing the phase and frequency of the reproduced control pulses with the reference pulses and means responsive to said comparing means for producing an output voltage proportional to any differences between the phase and frequency of the control and reference pulses to control the speed of the tape drive means; said position control logic circuit operable independently of said speed logic circuit including a gate controlled by the reproduced control track pulses to gate the timing disk pulses during each control track pulse, decoder means for counting the timing pulses gated during each timing disk pulse so that the control track pulses are decoded independently of tape speed, a bi-directional shift register loaded by the decoded control track pulses, an address register loaded by the shift register, a selection register loaded by a selected address number corresponding to a particular information recording on the tape, and a comparator logic circuit responsive to the selection register and the address register for generating a difference signal of a polarity and magnitude related to the direction and distance respectively to the next selected address number on said magnetic tape.

Claim 14

In a magnetic tape information retrieval system as set forth in claim 10 wherein said position control logic circuit includes a shift register control connected between the decoder means and the bi-directional shift register to orient the information loaded into the shift register in the proper sequence independently of the direction of the tape movement.

Claim 15

In a magnetic tape information retrieval system as set forth in claim 10 including dump circuit means to control the loading of the address register by the shift register when the shift register and address register are not in step.

Claim 16

In a magnetic tape information retrieval system as set forth in claim 10 wherein a count of selected numbers of timing pulses represents a particular address character.

Claim 17

In a magnetic tape information retrieval system as set forth in claim 10 wherein said speed logic circuit and position logic circuit are arranged in parallel with the tape drive means and are alternately connected thereto by an electric switch.

Claim 18

In a magnetic tape information retrieval system as set forth in claim 10 including cue signals recorded on the information track to identify the exact beginning of each recorded information segment and means to reproduce the cue signals coupled to the control means to stop the tape drive means at the beginning of a selected information recording.

Claim 19

A magnetic tape information retrieval system comprising: a magnetic tape, tape drive means for moving the tape in either direction, means for recording information on information tracks on the tape and reproducing the recorded information from the tape during the movement thereof, means for recording control track pulses on a control track of the tape coextensive with the information tracks and reproducing the control track pulses from the tape during movement thereof, said control track pulses being coded using two pulse characters representing binary numbers ZERO and ONE and arranged to consecutively number address segments of uniform lengths along the control track and a third character which together with the binary characters are recorded with equally spaced leading edges, control circuit means connected to said tape drive means for regulating the speed and position of the tape drive means, said control circuit means including a speed control circuit operable in the run mode having means for comparing the reproduced control pulses with the periodic reference pulses and means responsive to said comparing means for adjusting the speed of the tape drive means so that the positions of the control and reference pulses are synchronized; said control circuit means also including a position control circuit operable in the search mode having means for decoding the control track pulses independently of tape speed, means for comparing each successive decoded control track address number with a next selected address number and means for deriving a difference signal of a polarity and magnitude related to the direction and distance to the next selected address number on said magnetic tape.

Claim 20

A magnetic tape information retrieval system comprising: a magnetic tape, tape drive means for moving the tape in either direction, means for recording information on information tracks on the tape and reproducing the recorded information from the tape during the movement thereof, means for recording control track pulses on a control track of the tape coextensive with the information tracks and reproducing the control track pulses from the tape during movement thereof, said control track pulses being coded using two pulse characters representing binary numbers ZERO and ONE and arranged to consecutively number address segments of uniform lengths along the control track and a third character which together with the binary characters are recorded with equally spaced leading edges, control circuit means connected to said tape drive means for regulating the speed and position of the tape drive means, said control circuit means including a speed control circuit operable in the run mode having means for comparing the reproduced control pulses with the periodic reference pulses and means responsive to said comparing means for adjusting the speed of the tape drive means so that the positions of the control and reference pulses are synchronized; said control circuit means also including a position control circuit operable in the search mode having means for decoding the control track pulses independently of tape speed, means for comparing each successive decoded control track address number with a next selected address number and means for deriving a difference signal of a polarity and magnitude related to the direction and distance to the next selected address number on said magnetic tape.

Claim 21

Method for locating information segments on a storage medium movable relative to information and control transducers at various search speeds whereby an information segment defined by a predetermined address may be located rapidly relative to the information transducer, said medium having a control track carrying control information for controlling the relative speed and relative position between the transducers and the medium and wherein the position information in the control track has a predetermined positional relationship to an information segment it is associated with, said method comprising the steps of: transducing the control track decoding the position information transduced from the control track irrespective of the relative speed between the medium and the control transducer so as to be able to determine the present position of the control transducer while the search speed is being adjusted; comparing the present position of the control transducer with the predetermined address; adjusting the search speed of the medium relative to the control transducer as a function of the distance between the present position and the predetermined address so that as the predetermined address approaches the control transducer the speed of the medium relative to the control transducer is adjusted towards a run speed at which the information transducer may read the information segment associated with the predetermined address.

Claim 22

Method for locating information segments on a storage medium movable relative to information and control transducers at various search speeds whereby an information segment defined by a predetermined address may be located rapidly relative to the information transducer, said medium having a control track carrying control information for controlling the relative speed and relative position between the transducers and the medium and wherein the position information in the control track has a predetermined positional relationship to an information segment it is associated with, said method comprising the steps of: transducing the control track decoding the position information transduced from the control track irrespective of the relative speed between the medium and the control transducer so as to be able to determine the present position of the control transducer while the search speed is being adjusted; comparing the present position of the control transducer with the predetermined address; adjusting the search speed of the medium relative to the control transducer as a function of the distance between the present position and the predetermined address so that as the predetermined address approaches the control transducer the speed of the medium relative to the control transducer is adjusted towards a run speed at which the information transducer may read the information segment associated with the predetermined address.

Claim 23

The method of claim 17, and in addition, the steps of: detecting the actual run speed of the medium relative to the control transducer after the control transducer has reached the predetermined address by monitoring the signals transduced from the control track; comparing the actual run speed with a predetermined desired run speed; adjusting the run speed of the medium relative to the control transducer so that the actual run speed becomes the predetermined desired run speed.

Claim 24

The method of claim 17 wherein said decoding step comprises the steps of: detecting the duration of address signals recorded at each address segment on the medium; detecting the speed of movement of the medium relative to the control transducer; determining the present position from the width of the address signal in each address segment by analyzing the duration of the address signal in view of the speed of the medium relative to the control transducer.