Focusing bias adjusting apparatus and method in optical recording medium playing apparatus

A focusing bias adjusting apparatus in an optical recording medium playing apparatus, comprising:

• an optical pickup having an optical system for irradiating a laser beam onto an optical recording medium and detecting light reflected from said optical recording medium by a split type photodetector;
• focusing servo control means for generating a focusing error signal on the basis of each output signal of said photodetector and moving an objective lens in said pickup in an optical axial direction of said laser beam in accordance with said focusing error signal;
• focusing bias adjusting means for making a focusing bias adjustment in order to remove an offset component in said focusing error signal;
• tilt servo control means for adjusting said optical system so as to maximize a read signal as a sum signal of each output signal of said photodetector in order to compensate a tilt angle which is defined by a normal at the irradiating position of said laser beam on a recording surface of said optical recording medium and the optical axial direction of said laser beam;
• discriminating means for discriminating whether a starting condition of said focusing bias adjustment is satisfied or not when said tilt servo control means executes the adjusting operation of said optical system after completion of said focusing bias adjustment by said focusing bias adjusting means;
• and
• readjustment control means for controlling said focusing bias adjusting means so as to execute said focusing bias adjustment again when said discriminating means determines that the starting condition of said focusing bias adjustment is satisfied.

A focusing bias adjusting method in an optical recording medium playing apparatus, comprising the steps of;

• making a focusing bias adjustment to remove an offset component in a focusing error signal based on each output signal of a split type photodetector in an optical pickup;
• and
• thereafter, making a tilt adjustment of an optical system so as to maximize a read signal as a sum signal of each output signal of said photodetector in order to compensate a tilt angle which is defined by a normal at an irradiating position of a laser beam from said optical pickup on a recording surface of an optical recording medium and an optical axial direction of said laser beam,
• wherein said focusing bias adjustment is executed again when the tilt adjusting operation of the optical system of said optical pickup is performed after completion of the focusing bias adjustment.

A focusing bias adjusting method in an optical recording medium playing apparatus, comprising the steps of:

• making a focusing bias adjustment to remove an offset component in a focusing error signal based on each output signal of a split type photodetector in an optical pickup;
• and
• thereafter, making a tilt adjustment of an optical system so as to maximize a read signal as a sum signal of each output signal of said photodetector in order to compensate a tilt angle which is defined by a normal at an irradiating position of a laser beam from said optical pickup on a recording surface of an optical recording medium and an optical axial direction of said laser beam,
• wherein when the tilt adjusting operation of the optical system of said optical pickup is performed after completion of said focusing bias adjustment, whether a starting condition of said focusing bias adjustment is satisfied or not is discriminated, and
• when it is determined that said starting condition of said focusing bias adjustment is satisfied, said focusing bias adjustment is executed again.