Information recording and retrieval apparatus

An information retrieval or reproducing apparatus comprising:

• a. means for causing rotation of a rotary recording medium, said rotary recording medium having an information signal and a standard signal recorded in superposed relation on a plurality of information tracks wobbling along concentric circles or a spiral line, said standard signal having a frequency varying depending on the recorded position, wherein the frequency of the wobbling is equal to and synchronized with the standard signal frequency;
• b. means for directing a reproducing radiation beam toward said information tracks on said rotary recording medium to produce a beam spot thereon;
• c. beam-electrical converter means for converting into an electrical signal the radiation beam directed from said beam directing means toward one of said information tracks and passing therethrough or reflected therefrom;
• d. first detecting means for detecting a signal including information relating to deviation of the radiation beam spot from said information track in response to the application of the output signal thereto from said beam-electrical converter means;
• e. demodulator means for reproducing the information signal and standard signal from the output signal of said beam-electrical converter means to separate the standard signal from the information signal;
• f. retrieval instructing means capable of generating a plurality of signals having the same frequencies as those of the standard signal recorded together with the information signal to be reproduced;
• g. comparator means for comparing the reproduced standard signal applied from said demodulator means with the output signal of said retrieval instructing means;
• h. second detecting means for detecting the amount and direction of the deviation of said beam spot from said information track by comparing the reproduced standard signal applied from said demodulator means with the output signal of said first detecting means;
• i. means responsive to the output signal of said comparator means for controlling the relative position between said radiation beam directing means and said rotary recording medium;
• j. radiation beam deflecting means for deflecting the direction of the radiation beam obtained by said radiation beam directing means;
• and
• k. fine tracking control means responsive to the output of said second detecting means for driving said radiation beam deflecting means so as to compensate for the deviation of said beam spot from said information track.