Tuned oscillator circuit for providing a rotating in-plane magnetic field

Claim 2

An oscillator circuit comprising: a tuned circuit, first means for storing a first predetermined amount of energy, second means for storing a second predetermined amount of energy, first means for transferring said first predetermined amount of energy to said first storing means, second means for transferring from said first storing means to said tuned circuit an amount of energy sufficient to initiate an oscillatory current of a predetermined frequency, amplitude and phase in said tuned circuit, and third means for transferring from said tuned circuit to said second storing means an amount of energy sufficient to terminate said oscillatory current at a predetermined phase point without producing undesirable transient ringing effects.

Claim 3

The oscillator circuit in accordance with claim 1 in which said tuned circuit includes a capacitor and a coil, said first storing means includes a first capacitor for storing said first predetermined amount of electrical energy, said second storing means includes a second capacitor for storing at least the amount of electrical energy sufficient to terminate said oscillatory current without producing transient ringing effects, said first transferring means includes a bias voltage source and a first resistor for charging said first capacitor, said second transferring means includes a first switch for connecting said first capacitor and said tuned circuit in a loop, and said third transferring means includes a second resistor and a second switch for connecting said tuned circuit and said second capacitor to said bias voltage source.

Claim 4

The oscillator circuit in accordance with claim 2 in which said tuned circuit capacitor has a value which is n times the value of said first capacitor, where n is a predetermined positive number, said tuned circuit capacitor has a value which is (n+1) times the value of said second capacitor, and said bias voltage source provides a bias voltage which is (n+1) times the peak voltage amplitude produced across said tuned circuit capacitor by said oscillatory current.

Claim 5

The oscillator circuit in accordance with claim 2 in which said first resistor and said first switch are serially connected in a first circuit path, said second switch and said second resistor are serially connected in a second circuit path which is connected in parallel with said first path between said bias voltage source and a point of reference potential, said first capacitor and said second capacitor are serially connected in a third circuit path which is connected between a circuit point in said first path located between said first resistor and said first switch and a circuit point in said second path located between said second resistor and said second switch, and said tuned circuit capacitor and said tuned circuit coil are connected in parallel between said point of reference potential and a circuit point in said third path located between said first and second capacitors.

Claim 6

The tuned oscillator circuit in accordance with claim 4 in which said second switch is connected between said bias voltage source and said second resistor, and said first resistor is connected between said bias voltage source and said first switch.

Claim 7

The tuned oscillator circuit in accordance with claim 2 in which said first and second switches are electronic switches which are biased in normally nonconducting states, said oscillatory current is initiated by rendering said first switch conducting, and said oscillatory current is terminated after an integral number of oscillation cycles by rendering said second switch conducting when The oscillatory voltage developed across said tuned circuit capacitor by said oscillatory current reaches its peak amplitude and has a polarity which is opposite that of said bias voltage.

Claim 8

A rotating field drive circuit comprising a first oscillator circuit which includes a first tuned circuit comprising a capacitor and a field coil, first means for storing a first predetermined amount of energy, second means for storing a second predetermined amount of energy, first means for transferring said first predetermined amount of energy to said first storing means, second means for transferring from said first storing means to said first tuned circuit an amount of energy sufficient to initiate a first oscillatory current of a predetermined frequency, amplitude and phase in said first tuned circuit, and third means for transferring from said first tuned circuit to said second storing means an amount of energy sufficient to terminate said first oscillatory current at a predetermined phase point without producing transient ringing effects, and a second oscillator circuit which includes a second tuned circuit comprising a capacitor and a field coil, third means for storing a third predetermined amount of energy, fourth means for transferring said third predetermined amount of energy to said third storing means, fifth means for transferring from said third storing means to said second tuned circuit an amount of energy sufficient to initiate a second oscillatory current of a predetermined frequency, amplitude and phase in said second tuned circuit and for transferring an amount of energy from said second tuned circuit to said third storing means sufficient to terminate said second oscillatory current without producing substantial transient ringing effects.

Claim 9

A rotating field drive circuit comprising a first oscillator circuit which includes a first tuned circuit comprising a capacitor and a field coil, first means for storing a first predetermined amount of energy, second means for storing a second predetermined amount of energy, first means for transferring said first predetermined amount of energy to said first storing means, second means for transferring from said first storing means to said first tuned circuit an amount of energy sufficient to initiate a first oscillatory current of a predetermined frequency, amplitude and phase in said first tuned circuit, and third means for transferring from said first tuned circuit to said second storing means an amount of energy sufficient to terminate said first oscillatory current at a predetermined phase point without producing transient ringing effects, and a second oscillator circuit which includes a second tuned circuit comprising a capacitor and a field coil, third means for storing a third predetermined amount of energy, fourth means for transferring said third predetermined amount of energy to said third storing means, fifth means for transferring from said third storing means to said second tuned circuit an amount of energy sufficient to initiate a second oscillatory current of a predetermined frequency, amplitude and phase in said second tuned circuit and for transferring an amount of energy from said second tuned circuit to said third storing means sufficient to terminate said second oscillatory current without producing substantial transient ringing effects.

Claim 10

The rotating field drive circuit in accordance with claim 7 in which said first storing means includes a first capacitor for storing said first amount of energy, said second storing means includes a second capacitor for storing at least the amount of energy which is transferred from said first tuned circuit to terminate said first oscillatory current, said third storing means includes a third capacitor for storing at least said third predetermined amount of energy, said first transferring means includes a bias voltage source and a first resistor for charging said first capacitor, said second transferring means includes a first switch for connecting said first capacitor and said first tuned circuit in a loop, said third transferring means includes a second resistor and a second switch for connecting said first tuned circuit and said second capacitor to said bias voltage source, said fourth transferring means includes a third resistor for connecting said bias voltage source to said third capacitor, and said fifth transferring means includes a third switch for connecting said third capacitor and said second tuned circuit in a loop.

Claim 11

The field drive circuit in accordance with claim 8 in which said first tuned circuit capacitor has a value which is n1 times the value of said first capacitor, where n1 is a predetermined positive number, said second tuned circuit capacitor has a value which is n2 times the value of said third capacitor, where n2 is a predetermined positive number, said first tuned circuit capacitor has a value which is (n1+1) times the value of said second capacitor, and said bias voltage source provides a bias voltage which is (n1+1) times the peak voltage amplitude produced across said first tuned circuit capacitor by said first oscillatory current and which is (n2+1) times the peak voltage amplitude produced across said second tuned circuit capacitor by said second oscillatory current.

Claim 12

The field drive circuit in accordance with claim 9 in which n1 equals n2.

Claim 13

The field drive circuit in accordance with claim 8 in which the oscillation frequencies of said first and second oscillatory currents are substantially the same.

Claim 14

The field drive circuit in accordance with claim 11, such circuit further comprising regenerating means, connected between said first and second tuned circuits, for maintaining said first and second oscillatory currents at a constant amplitude and for insuring that said first current trails said second current by one quarter cycle.

Claim 15

The field drive circuit in accordance with claim 11 in which the axes of said field coils in said first and said second tuned circuits are arranged in a plane to produce two orthogonal magnetic field components which comprise an in-plane magnetic field that rotates at the frequency of said oscillatory currents.

Claim 16

The field drive circuit in accordance with claim 13 in which said first, second and third switches are electronic switches which are biased in normally nonconducting states, said second oscillatory current is initiated by rendering said third switch momentarily conducting, said first oscillatory current is initiated one quarter cycle after the initiation of said second current by rendering said first switch momentarily conducting, said first current is terminated after an integral number of oscillation cycles by rendering said second switch momentarily conducting when the oscillatory voltage across said first tuned circuit capacitor, measured with respect to said bias voltage, reaches its peak amplitude and has a polarity which is opposite that of said bias voltage, and said second current is terminated after an odd number of half oscillation cycles by rendering said third switch momentarily conducting one quarter cycle after the termination of said first current when the oscillatory voltage across said second tuned circuit capacitor, measured with respect to said bias voltage, reaches its peak amplitude and has the same polarity as said bias voltage, whereby the resultant rotating in-plane magnetic field terminates itself at its initial phase point without a static component after an integral number of rotation cycles.

Claim 17

The field drive circuit in accordance with claim 8 in which said first resistor and said first switch are serially connected in a first circuit path, said second resistor and said second switch are serially connected in a second circuit path which is connected in parallel with said first path between said bias voltage source and a point of reference potential, said first and second capacitors are serially connected in a third circuit path which is connected between a circuit point in said first path located between said first resistor and said first switch and a circuit point in said second path located between said second resistor and said second switch, said first tuned circuit capacitor and said first tuned circuit coil are connected in parallel between said point of reference potential and a circuit point in said third path located between said first and second capacitors, said third resistor and said third switch are serially connected in a fifth circuit path which is connected between said bias voltage source and said point of reference potential, and said third capacitor and a parallel combination of said second tuned circuit capacitor and said second tuned circuit coil are serially connected in a sixth circuit path which is connected between said point of reference potential and a circuit point in said fifth path located between said third resistor and said third switch.

Claim 18

The field drive circuit in accordance with claim 15 in which said first resistor is connected in said first path between said bias voltage source and said first switch, said second switch is connected in said second path between said bias voltage source and said second resistor, and said third resistor is connected in said fifth path between said bias voltage source and said third switch.

Claim 19

THe field drive circuit in accordance with claim 15, such circuit further comprising first and second regenerating circuits, said first regenerating circuit, connected from said point of reference potential to a circuit point in said sixth path located between said third capacitor and said second tuned circuit, including a first amplifier circuit and a transformer, and said second regenerating circuit, connected from a circuit point in said sixth path located between said third capacitor and said second tuned circuit to a circuit point in said third path located between said first and second capacitors, including a second amplifier circuit and a high pass filter.