Layer-jumping and focusing control method

A layer-jumping and focusing control method for use in a disc reading apparatus to read an optical disc having first and second recording layers, the disc reading apparatus comprising an optical pickup head, a radio-frequency amplifier and an actuator, and the method comprising steps of:

• the optical pickup head generating first electric signals and second electric signals in response to light intensities reflected by the optical disc and received by a main region and a subordinate region of the optical pickup head, respectively;
• the radio-frequency amplifier generating a first focusing error signal by operating said first electric signals and said second electric signals when the optical pickup head is focusing on the first or the second recording layer;
• the actuator adjusting the focusing position of the optical pickup head according to said first focusing error signal;
• the radio-frequency amplifier generating a second focusing error signal by operating said first electric signals only when the optical pickup head is being moved by the actuator to shift the focusing position from the first recording layer to the second recording layer or from the second recording layer to the first recording layer;
• and
• the radio-frequency amplifier generating said first focusing error signal by operating said first electric signals and said second electric signals again when said second focusing error signal complies with a predetermined condition.