Patent ID: 7808870

Claim:
An optical disk recording/reproducing device comprising: an objective lens for recording and reproducing information on a recording surface of the optical disk; a focus drive device for driving the objective lens in a focus direction; a focus controlling device for controlling the focus drive device to perform a continuous on-focus of a focal point of the objective lens on the recording surface of the optical disk; a disk determining device for determining one kind of disk from two or more kinds of disks having different substrate thicknesses by comparing a focus drive value, when the focal point at the recording surface is detected during a focus search of the optical disk, with a threshold value, or comparing a focus drive value during an on-focus state with a threshold value; a spin-up device for performing a spin-up processing for making the two or more kinds of disks having different substrate thicknesses recordable and reproducible corresponding to the kind of disk; a focus drive value integrating device for acquiring a value obtained by integrating the focus drive value by one-cycle unit of the optical disk when the focus controlling device continues the on-focus state of the focal point of the objective lens to the recording surface of the one kind of disk from the two or more kinds of disks having different substrate thicknesses by controlling the focus drive device after the spin-up processing of the spin-up device is completed and the kind of disk is confirmed; a threshold value deciding device for deciding the threshold value for the disk determining device by using an average value of the focus drive values derived from the values obtained by integrating the focus drive value for the one kind of disk from the two or more kinds of disks having different substrate thicknesses; and a nonvolatile storing unit for storing the average value of the focus drive value as a disk determination drive value after the kind of disk has been determined on the basis of the threshold value.