US Patent 7835242 Optical disk recording and reproducing device

A system controller of an optical disk recording and reproducing device makes a display portion display a precaution message for recommending a user to back up data recorded on the optical disk when it is determined that one or more values including a jitter value, a variation quantity of the jitter value, a block error rate and a block error rate at a particular position have exceeded precaution reference values. In addition, it makes a display portion display an urgent message for instructing a user to back up data recorded on the optical disk quickly when it is determined that one or more of the values have exceeded limit reference values.