Rotating field transformer and tape recording system using same

Claim 2

A tape recorder head, comprising magnetically unsaturated elongated core means of substantially uniform permeability having coil slots therein and having a narrow airgap therein to accommodate the passage of a magnetic tape, coil means including coil sides in said slots and including exciting means to provide in said airgap, a narrow traveling m.m.f. beam substantially perpendicular to the plane of said coil slots and being directed across the narrow dimension of said airgap acting on only one point on a transverse tape track at a given instant, said coil means and exciting means including circuit means to provide interacting magnetic fields to move said m.m.f. beam along the air gap.

Claim 3

A tape recorder head comprising first elongated core means having coil slots therein, second core means adjacent said first core means covering said slots and defining a narrow airgap to allow passage of a magnetic tape therebetween, first and second stator coils mounted in said slots in respective orthogonal relationship, main m.m.f. beam producing means including signal source means applying first and second orthogonally related main sawtooth signals to said first and second stator primary coils respectively, stator traveling field transformer means including primary and first and second auxiliary coils inductively coupled to said respective first and second stator coils, said stator coils, and transformer primary and auxiliary coils having a substantially sinusoidal distribution, signal means providing first and second sawtooth signals to respective transformer primary coils.

Claim 4

A tape recorder head comprising first elongated core means having coil slots therein, second core means adjacent said first core means covering said slots and defining a narrow airgap to allow passage of a magnetic tape therebetween, first and second stator coils mounted in said slots in respective orthogonal relationship, main m.m.f. beam producing means including signal source means applying first and second orthogonally related main sawtooth signals to said first and second stator primary coils respectively, stator traveling field transformer means including primary and first and second auxiliary coils inductively coupled to said respective first and second stator coils, said stator coils, and transformer primary and auxiliary coils having a substantially sinusoidal distribution, signal means providing first and second sawtooth signals to respective transformer primary coils.

Claim 5

The tape recorder head of claim 2 including a playback winding positioned in said slots.

Claim 6

The tape recorder head of claim 3 in which the auxiliary coils provide phase modulating signals, the main m.m.f. distributions from said first and second stator coils being subtractive resulting in minimal m.m.f. in the absence of said phase modulating signals, said phase modulating signals being equal and oppositely applied to respective auxiliary coils to provide an alternating m.m.f. beam.

Claim 7

A traveling field tape recorder head for recording on tape comprising a slotted magnetic core, said core being magnetically unsaturated and of substantially uniform permeability, two phase sinusoidally distributed stator windings in said slots, a core piece bridging said slots and defining a narrow, elongated airgap constituting tape slot, exciting means coupled to said stator windings to producE a slender alternating traveling wave m.m.f. beam into said airgap passing along said slots and perpendicular to the plane of said tape, acting on only one point on a transverse tape track at a given instant, said exciting means and said sinusoidally distributed stator windings providing traveling wave action as a result of interacting magnetic fields.

Claim 8

A traveling field tape recorder head for recording on tape comprising a slotted magnetic core, said core being magnetically unsaturated and of substantially uniform permeability, two phase sinusoidally distributed stator windings in said slots, a core piece bridging said slots and defining a narrow, elongated airgap constituting tape slot, exciting means coupled to said stator windings to producE a slender alternating traveling wave m.m.f. beam into said airgap passing along said slots and perpendicular to the plane of said tape, acting on only one point on a transverse tape track at a given instant, said exciting means and said sinusoidally distributed stator windings providing traveling wave action as a result of interacting magnetic fields.

Claim 9

The recorder head of claim 5 in which said exciting means include sawtooth exciting current source means.

Claim 10

A tape-recording system comprising tape-recording head means including means to provide a narrow traveling m.m.f. beam perpendicular to the plane of a magnetic tape, said head including first and second orthogonally related stator coils disposed to provide a sinusoidally varying current distribution, a playback coil, first traveling field transformer means including first and second orthogonally related primary coils, and secondary coil means, said secondary coil means being coupled to said first stator coil, second traveling field transformer means including first and second orthogonally related primary coils, and secondary coil means, said secondary coil means being coupled to said second stator coil, sawtooth generating means exciting the first and second primaries of the first and second traveling field transformer means with 90* phase displaced sawtooth signals respectively, first auxiliary transformer means comprising first and second orthogonally related primary coils magnetically coupled respectively to the first and second primary coils of said first traveling field transformer means, second auxiliary transformer means comprising first and second orthogonally related primary coils magnetically coupled respectively to the first and second primary coils of the said second traveling field transformer means, modulating means to excite the said primary coils of said first and second auxiliary transformer means respectively with signals at r+s and r-s frequencies respectively, where r is a carrier frequency and s is the frequency of the sawtooth signals, and information signal means to modulate said r+s and r-s signals respectively with desired input signals, and playback circuit means coupled to said playback coil to derive signals from said playback coil.

Claim 11

A tape-recording system comprising tape-recording head means including means to provide a narrow traveling m.m.f. beam perpendicular to the plane of a magnetic tape, said head including first and second orthogonally related stator coils disposed to provide a sinusoidally varying current distribution, a playback coil, first traveling field transformer means including first and second orthogonally related primary coils, and secondary coil means, said secondary coil means being coupled to said first stator coil, second traveling field transformer means including first and second orthogonally related primary coils, and secondary coil means, said secondary coil means being coupled to said second stator coil, sawtooth generating means exciting the first and second primaries of the first and second traveling field transformer means with 90* phase displaced sawtooth signals respectively, first auxiliary transformer means comprising first and second orthogonally related primary coils magnetically coupled respectively to the first and second primary coils of said first traveling field transformer means, second auxiliary transformer means comprising first and second orthogonally related primary coils magnetically coupled respectively to the first and second primary coils of the said second traveling field transformer means, modulating means to excite the said primary coils of said first and second auxiliary transformer means respectively with signals at r+s and r-s frequencies respectively, where r is a carrier frequency and s is the frequency of the sawtooth signals, and information signal means to modulate said r+s and r-s signals respectively with desired input signals, and playback circuit means coupled to said playback coil to derive signals from said playback coil.

Claim 12

The system of claim 7, where r is high relative to s.

Claim 13

The tape-recording system of claim 7, in which said playback circuit means and said modulating means are in a control loop, including a frequency demodulator and means to compare the signal derived from the playback circuit with the input signal recorded in said tape.

Claim 14

A tape-recording system comprising, stationary outer core means, stationary inner core means, one of said core means having an airgap slot through which magnetic tape may pass, said core being magnetically unsaturated and of substantially uniform permeability, means for moving said tape in a first direction through said core means, means to establish a magnetic field of narrow width from the inner core means to the outer core means in a direction perpendicular to the tape surface, means to modulate said magnetic field with information signals, means to move said magnetic field in a direction transverse to the direction of tape movement, said magnetic field acting upon only one point on a transverse tape track at a given instant.

Claim 15

A tape-recording system comprising, stationary outer core means, stationary inner core means, one of said core means having an airgap slot through which magnetic tape may pass, said core being magnetically unsaturated and of substantially uniform permeability, means for moving said tape in a first direction through said core means, means to establish a magnetic field of narrow width from the inner core means to the outer core means in a direction perpendicular to the tape surface, means to modulate said magnetic field with information signals, means to move said magnetic field in a direction transverse to the direction of tape movement, said magnetic field acting upon only one point on a transverse tape track at a given instant.

Claim 16

A magnetic recording head comprising a magnetic core structure, including an inner and outer core and an airgap therebetween, said core structure being magnetically unsaturated and of substantially uniform permeability, part of said core structure defining said gap further defining an elongated aperture through which a magnetizable medium passes; two stator windings mounted in said core; each winding producing recurrent m.m.f. distributions across the airgap, the distributions moving along the gap as traveling waves caused by the interaction of magnetic fields, produced by the stator windings, the resultant m.m.f. of The two waves magnetizes the medium passing through the aperture, means providing quadrature current flowing in the two phases of said stator windings, said stator windings being mutually orthogonal and sinusoidally distributed in space along the airgap, whereby said traveling waves are provided.

Claim 17

A magnetic recording head comprising a magnetic core structure, including an inner and outer core and an airgap therebetween, said core structure being magnetically unsaturated and of substantially uniform permeability, part of said core structure defining said gap further defining an elongated aperture through which a magnetizable medium passes; two stator windings mounted in said core; each winding producing recurrent m.m.f. distributions across the airgap, the distributions moving along the gap as traveling waves caused by the interaction of magnetic fields, produced by the stator windings, the resultant m.m.f. of The two waves magnetizes the medium passing through the aperture, means providing quadrature current flowing in the two phases of said stator windings, said stator windings being mutually orthogonal and sinusoidally distributed in space along the airgap, whereby said traveling waves are provided.

Claim 18

The recorder of claim 11 further comprising first and second traveling field transformer means coupled to respective stator windings.

Claim 19

The head of claim 11, said quadrature currents in the two stator windings being substantially sawtooth functions of time, two narrow traveling m.m.f. beams being formed across the airgap from the instantaneous difference between the two sawtooth functions.

Claim 20

The head of claim 13, in which the m.m.f. beams alternate in polarity at approximately a sinusoidal rate in response to phase modulation impressed on the constituent sawtooth functions, means to produce the said phase modulations on each sawtooth function, whereby a beam can write information into a magnetizable medium by alternating at a modulated frequency as it travels along the aperture thereby leaving FM remnant tracks in the tape.

Claim 21

The recording head of claim 13 in which the stator windings have a high-resonant frequency, whereby for a given beam velocity, the bandwidth of the recording system is determined by the spacial width of the m.m.f. beam in the direction of beam velocity fixed by the retrace time of the sawtooth currents exciting the stator windings.

Claim 22

The recording head of claim 11 including an additional two-phase sinusoidally distributed winding mounted in the core structure to span the aperture portion of the airgap to provide a playback winding thereby permitting information recorded in the tape to be recovered as an electrical signal.

Claim 23

The recording head of claim 16 in further combination, an external feedback loop coupled to said playback winding, whereby traveling beams of reduced intensity can be used to track and read information previously recorded in the tape.