should be noted that r1 and r2 represent the too far region and too near region respectively for example in the reproduction mode of the disc information the auto focus focus servo controller 22 is made operative when the actuator 12a is sufficiently spaced from the rotating disc 10 this controller 22 first supplies a focus servo stop signal s1 and a search start signal s2 to the two analog switches 24 and 38 respectively in response to these signals s1 and s2 analog switch 24 is rendered open while the other switch 38 is rendered closed at this time the controller 22 supplies a search on command signal s3 to the miller integrator 32 thus the integrator 32 starts the charging operation in waveform diagrams of fig3 t1 indicates a charge start time point at this integrator 32 before time t1 miller integrator 32 has the given output at time t1 output voltage v1 of the miller integrator drops by a small amount thereby applying a negative voltage having the effect of initially moving the lens from its equilibrium position away from the disk surface output voltage v1 of the miller integrator 32 gradually increases at a constantly increasing rate as denoted by a reference numeral 42 of fig3 a after this time.