Servo system for magnetic recording and reproducing apparatus

Claim 2

A servo system for a magnetic recording and reproducing apparatus comprising a rotating magnetic head assembly, a synchronous motor for driving said head assembly, oscillator means for generating a drive voltage which drives said motor, means for supplying a reference signal, synchronous signal means for generating a signal which is synchronous with the rotation of the motor, first phase comparator means for producing a first control signal responsive to the phase difference between the output of said synchronous signal means and the reference signal, second phase comparator means for producing a second control signal responsive to the phase difference between the drive voltage and the reference signal, adding meaNs for adding said first and said second control signals, and means for controlling the frequency and phase of the drive voltage responsive to the output signal of said adding means.

Claim 3

A servo system for a magnetic recording and reproducing apparatus comprising a rotational magnetic head assembly, a synchronous motor for driving said head assembly, oscillator means for generating a drive voltage which drives said motor, means for supplying a reference signal, synchronous signal means for generating a signal which is synchronous with the rotation of the motor, first phase comparator means for producing an output signal responsive to the phase difference between the output of said synchronous signal means and the reference signal, means including a low-pass filter for integrating the output signal of said first phase comparator means, second phase comparator means for producing a control signal responsive to the phase difference between the drive voltage and the reference signal, adding means for adding the output of said low-pass filter means to said control signal, and means for controlling the frequency and phase of the drive voltage responsive to the output signal of said adding means.

Claim 4

A servo system for a magnetic recording and reproducing apparatus comprising a rotational magnetic head assembly, a synchronous motor for driving said head assembly, oscillator means for generating a drive voltage which drives said motor, means for supplying a reference signal, synchronous signal means for generating a signal which is synchronous with the rotation of the motor, first phase comparator means for producing an output signal responsive to the phase difference between the output of said synchronous signal means and the reference signal, means including a low-pass filter for integrating the output signal of said first phase comparator means, second phase comparator means for producing a control signal responsive to the phase difference between the drive voltage and the reference signal, adding means for adding the output of said low-pass filter means to said control signal, and means for controlling the frequency and phase of the drive voltage responsive to the output signal of said adding means.

Claim 5

A servo system for a magnetic recording and reproducing apparatus comprising a rotational magnetic head assembly, a synchronous motor for driving said head assembly, oscillator means for generating a drive voltage which drives said motor, means for supplying a reference signal, synchronous signal means for generating a signal which is synchronous with the rotation of the motor, first phase comparator means for producing an output signal responsive to the phase difference between the output of said synchronous signal means and the reference signal, integrator means for integrating said output signal of the phase comparator means and producing a first control signal in the form of a digital signal responsive to the level of the integrated signal, second phase comparator means for producing a second control signal responsive to the phase difference between the drive voltage and the reference signal, adding means for adding said first and said second control signals, and means for controlling the frequency and phase of the drive voltage responsive to the output signal of said adding means.

Claim 6

A servo system for a magnetic recording and reproducing apparatus comprising a rotational magnetic head assembly, a synchronous motor for driving said head assembly, oscillator means for generating a drive voltage which drives said motor, means for supplying a reference signal, synchronous signal means for generating a signal which is synchronous with the rotation of the motor, first phase comparator means for producing an output signal responsive to the phase difference between the output of said synchronous signal means and the reference signal, integrator means for integrating said output signal of the phase comparator means and producing a first control signal in the form of a digital signal responsive to the level of the integrated signal, second phase comparator means for producing a second control signal responsive to the phase difference between the drive voltage and the reference signal, adding means for adding said first and said second control signals, and means for controlling the frequency and phase of the drive voltage responsive to the output signal of said adding means.

Claim 7

a servo system for a magnetic recording and reproducing apparatus comprising a rotational magnetic head assembly, a synchronous motor for driving said head assembly, oscillator means for generating a drive voltage which drives said motor, means for supplying a reference signal, synchronous signal generating means for generating a signal which is synchronous with the rotation of the motor, means comprising a first flip-flop circuit for generating a symmetrical rectangular waveform signal responsive to the signal of said synchronous signal generating means, means comprising a first delay circuit for delaying the trailing edge of the symmetrical rectangular waveform signal. means comprising a pulse forming circuit for differentiating the output signal of said first delay circuit means to produce a pulse signal, means comprising a second delay circuit for producing a delayed pulse signal which is delayed for a predetermined time interval after said pulse signal, means comprising a second flip-flop circuit which is driven to its set state responsive to said delayed pulse and to its reset state responsive to said reference signal, integrator means responsive to the level of the output signal of the second flip-flop circuit means for integrating the output signal of the second flip-flop circuit means to produce a first control signal in the form of a digital signal, means comprising a phase comparator circuit for producing a second control signal responsive to the phase difference between said drive voltage and the reference signal, adding means for adding said first control and said second control signals, and means responsive to the output signal of said adding means for controlling the frequency anD phase of said drive voltage.

Claim 8

a servo system for a magnetic recording and reproducing apparatus comprising a rotational magnetic head assembly, a synchronous motor for driving said head assembly, oscillator means for generating a drive voltage which drives said motor, means for supplying a reference signal, synchronous signal generating means for generating a signal which is synchronous with the rotation of the motor, means comprising a first flip-flop circuit for generating a symmetrical rectangular waveform signal responsive to the signal of said synchronous signal generating means, means comprising a first delay circuit for delaying the trailing edge of the symmetrical rectangular waveform signal. means comprising a pulse forming circuit for differentiating the output signal of said first delay circuit means to produce a pulse signal, means comprising a second delay circuit for producing a delayed pulse signal which is delayed for a predetermined time interval after said pulse signal, means comprising a second flip-flop circuit which is driven to its set state responsive to said delayed pulse and to its reset state responsive to said reference signal, integrator means responsive to the level of the output signal of the second flip-flop circuit means for integrating the output signal of the second flip-flop circuit means to produce a first control signal in the form of a digital signal, means comprising a phase comparator circuit for producing a second control signal responsive to the phase difference between said drive voltage and the reference signal, adding means for adding said first control and said second control signals, and means responsive to the output signal of said adding means for controlling the frequency anD phase of said drive voltage.