Information recording and/or reproducing method and apparatus in which a servo process of a light beam is interrupted between input/output control of data at predetermined periods

An information recording and/or reproducing apparatus for recording data onto and/or reproducing data from a recording medium by irradiating a light beam emitted from a light source onto a desired track of the recording medium through an optical system, said apparatus comprising:

• a single processor for executing an input/output control of the data for said apparatus and a servo process of the light beam such that the input/output control of the data and the servo process of the light beam are alternately switched at a predetermined period;
• an actuator for moving the light beam on the basis of the servo process of said processor;
• and
• means for detecting an amount of an external disturbance of the servo process and for determining when the amount of external disturbance is larger than a predetermined amount,
• wherein the precision of the servo process is changed so that the precision is increased when a detected amount of external disturbance is larger than the predetermined amount.