Optical disk drive and method for determining disk type

A method of determining a disk type of an optical disk comprising steps of:

• using a first light path for forming an incident beam;
• moving an objective lens system corresponding to the first light path from a start position towards the optical disk;
• receiving a sensor output signal during the movement of the objective lens system, wherein the sensor output signal includes a central aperture signal;
• determining a first position of the central aperture signal where the central aperture signal crosses a first threshold in an upward direction;
• determining a second position the central aperture signal where the central aperture signal crosses a second threshold in an downward direction;
• setting a pre-determined time width;
• determining a time width of the central aperture signal between the first position and the second position;
• and
• determining the disk type of the optical disk by comparing the time width of the central aperture signal with the pre-determined time width.

A method of determining a disk type of an optical disk comprising steps of:

• selecting a first light path from a BD-light path, a DVD-light path and a CD-light path for forming an incident beam;
• moving an objective lens system corresponding to the first light path from a start position towards the optical disk;
• changing to another light path at least once during the same movement of the objective lens system;
• receiving a focus error signal during the movement of the objective lens system, wherein the focus error signal is analyzed to a BD-laser channel corresponding to the BD-light path, a DVD-laser channel corresponding to the DVD-light path, and a CD-laser channel corresponding to the CD-light path;
• if two consecutive S-curve of the focus error signal appear on the CD-laser channel followed by two other S-curve of the focus error signal on the DVD-laser channel during the same movement of the objective lens system, indicating the disk type as a BD-type disk;
• if a S-curve of the focus error signal appears on the CD-laser channel followed by an other S-curve of the focus error signal on the DVD-laser channel, and an another S-curve of the focus error signal appears on the CD-laser channel after a relatively short time during the same movement of the objective lens system, indicating the disk type as a DVD-type disk;
• and
• if a S-curve of the focus error signal appears on the CD-laser channel followed by an other S-curve of the focus error signal on the DVD-laser channel, and no S-curve of the focus error signal appears on any channels after a relatively long time during the same movement of the objective lens system, indicating the disk type as a CD-type disk.