Disk storage apparatus including a single power supply hysteresis comparator having a symmetrical characteristic

A disk storage apparatus comprising

• an optical scanning system movable with respect to a disk-shaped medium, said optical scanning system generating an electric read signal obtained by optically scanning the disk-shaped medium;
• reproducing means, coupled to said optical scanning system, for reproducing information from the electric read signal;
• and
• seek control means, coupled to said optical scanning system, for generating a seek control signal from said electric read signal,
• said seek control means comprising:
• position error signal generating means for generating a position error signal from said electric read signal, said position error signal indicating an error in a position of tracking by means of said optical scanning system;
• and
• a rectangular wave generator,
• said rectangular wave generator comprising:
• a comparator having a first input terminal receiving said position error signal, a second input terminal, and an output terminal, the comparator sliding the position error signal at a hysteresis voltage so that a rectangular wave corresponding to said seek control signal is output via the output terminal;
• and
• a feedback circuit connected between the output terminal and the second input terminal, said feedback circuit comprising feedback control means for changing a feedback quantity of said feedback circuit in accordance with variations in a frequency of the position error signal.