Patent ID: 6151280
Filing Date: 2000-11-21
Classification: G11B

Abstract:
A focus jump control apparatus comprising:reading means for irradiating read light to a disc having information recording surfaces formed on at least two layers, respectively;a focusing servo loop for allowing an optimum light converging position of said read light to trace said recording surface in response to a focusing error signal generated based on return light from said disc by using a focusing actuator for displacing the optimum light converging position of said read light in the optical axial direction; anda tracking servo loop for allowing the optimum light converging position of said read light to trace tracks formed on said disc; andloop opening/closing control means for opening said focusing servo loop in response to a n instruction and for closing said focusing servo loop when a movement of the optimum light converging position of said read light from one of said recording surfaces to the other is finished, wherein a closed state of said tracking servo loop is maintained during the movement of the optimum light converging position of said read light.