System for recording information on a rotatable storage disc, in a substantially uniform recording density

Claim 1

Apparatus for recording information on a rotatable information storage disc, wherein the information is recorded in plurality of substantially circular and concentrically arranged information tracks, said apparatus comprising: transducer means movable radially relative to the disc to be positioned in a prescribed relationship relative to a selected one of the information tracks; velocity signal means for producing a velocity signal having an instantaneous frequency substantially inversely proportional to the radius of the selected track, said velocity signal means including means for producing a voltage signal substantially inversely proportional to the radius of the selected information track, said means including a potentiometer coupled to said radially movable transducer means, and oscillator means, responsive to said voltage signal, for producing the velocity signal; servo means for rotating the disc at an angular velocity synchronized with the instantaneous frequency of the velocity signal, said servo means including motor means for rotating the disc; tachometer means coupled to said motor means for producing a tachometer signal having a frequency proportional to the angular velocity of said motor means, and phase detector means for comparing the respective phase angles of the tachometer signal and the velocity signal, and for producing a control signal indicative of the phase difference thereof, said control signal being coupled to said motor means to appropriately control its angular velocity, whereby the selected information track is moved at a substantially constant linear velocity relative to said transducer means and a substantially uniform information recording density is achieved; and means, responsive to the velocity signal, for moving said transducer means radially relative to the disc at a corresponding radial velocity, whereby information is recorded on the plurality of information tracks in a sequential fashion and the tracks are substantially evenly spaced with respect to each other.

Claim 10

A method of rotating an information storage disc relative to a transducer, wherein said disc has a plurality of substantially circular and concentrically arranged information tracks, and wherein said transducer is radially movable relative to said disc to be positioned in a prescribed relationship relative to a selected one of the information tracks, said method comprising the steps of: coupling a potentiometer to the radially movable transducer, to produce a voltage signal indicative of the radius of the selected information track; producing a velocity signal in accordance with the voltage signal, said velocity signal having a frequency substantially inversely proportional to the radius of the selected information track; and rotating the disc at an angular velocity synchronized with the frequency of the velocity signal, whereby the selected information track is moved at a prescribed, constant linear velocity relative to the transducer.

Claim 11

A method of rotating an information storage disc relative to a transducer, wherein said disc has a plurality of substantially circular and concentrically arranged information tracks, and wherein said transducer is radially movable relative to said disc to be positioned in a prescribed relationship relative to a selected one of the information tracks, said method comprising the steps of: coupling a potentiometer to the radially movable transducer, to produce a voltage signal indicative of the radius of the selected information track; producing a velocity signal in accordance with the voltage signal, said velocity signal having a frequency substantially inversely proportional to the radius of the selected information track; and rotating the disc at an angular velocity synchronized with the frequency of the velocity signal, whereby the selected information track is moved at a prescribed, constant linear velocity relative to the transducer.

Claim 13

A method of driving a motor to controllably rotate an information storage disc relative to a transducer, wherein said disc has a plurality of substantially circular and concentrically arranged information tracks, and wherein said transducer is radially movable relative to said disc to be positioned in a prescribed relationship relative to a selected one of the information tracks, said method comprising the steps of: producing a velocity signal in accordance with the radial position of the transducer, said velocity signal having a frequency substantially inversely proportional to the radius of the selected information track; producing a tachometer signal having a frequency proportional to the angular velocity of the motor; and comparing the respective phase angles of the tachometer signal and the velocity signal, to produce a control signal for coupling to the motor, to controllably adjust its angular velocity and thereby to synchronize the respective phase angles, whereby the selected information track is moved at a prescribed constant linear velocity relative to the transducer.

Claim 14

A method of driving a motor to controllably rotate an information storage disc relative to a transducer, wherein said disc has a plurality of substantially circular and concentrically arranged information tracks, and wherein said transducer is radially movable relative to said disc to be positioned in a prescribed relationship relative to a selected one of the information tracks, said method comprising the steps of: producing a velocity signal in accordance with the radial position of the transducer, said velocity signal having a frequency substantially inversely proportional to the radius of the selected information track; producing a tachometer signal having a frequency proportional to the angular velocity of the motor; and comparing the respective phase angles of the tachometer signal and the velocity signal, to produce a control signal for coupling to the motor, to controllably adjust its angular velocity and thereby to synchronize the respective phase angles, whereby the selected information track is moved at a prescribed constant linear velocity relative to the transducer.