Patent ID: 6882600

Claim:
A carriage servo control system for servo-controlling a movement of a carriage device in a vertical direction to a track formed on a recording medium, in which the carriage device has a detecting device mounted thereon for transmitting an optical beam to the track so as to perform at least one of recording and reproduction of information on and from the track, said carriage servo control system comprising: an error signal producing device for producing an error signal showing an error between a radiated position of the optical beam on the recording medium and a position of the track; a periodic signal producing device for producing a periodic signal of which period is constant and previously determined so as to correspond to a movement accuracy of the carriage device; a duty ratio control device for changing a duty ratio of the periodic signal on a basis of characteristic of the error signal produced to produce a changed periodic signal having the duty ratio changed; a drive signal producing device for producing a drive signal to move the carriage device on a basis of both the changed periodic signal produced and the error signal produced; and a supplying device for supplying the drive signal produced to a moving device configured to move the carriage device in the vertical direction so as to move said carriage device by the moving device on a basis of the drive signal supplied, wherein said duty ratio control device changes the duty ratio based on a difference between a maximum value and a minimum value of the error signal to produce the changed periodic signal.