Matsushita Electric Industrial Co., Ltd.

Hiroyuki Miyachi

Ryusuke Horibe

Toshiyuki Shimada

Hiromichi Ishibashi

Mitsurou Moriya

Yasuaki Edahiro

Hiromiti Ishibashi

A phase error between an information signal including a reference signal that can be detected asynchronously and a synchronized signal that is synchronously produced from the information signal is detected, and a signal in response to an absolute value of the phase error is produced. Further, a defect detecting signal is produced in response to the absolute value of the phase error. Therefore, whether a pulse signal exceeding a maximum value of the pulse width of the information signal, that is, a pulse signal exceeding the pulse width of the reference signal, is detected or not, it is possible to detect that the signal reproduction enters a defect region immediately after the entry. Accordingly, a defect with noise or a track jumping can be detected rapidly. Furthermore, an information transition interval of the information signal is measured for a prescribed period of time, and the defect detecting signal is terminated in response to a measured value of a time length of the reference signal that is detected in the prescribed period of time, in other words, the passing of the signal reproduction through the defect region is detected with reference to the synchronization of the reference signal. Therefore, pseudo locking of a PLL is avoided when it is operated again, and the PLL can be accurately re-locked.

Optical disk device

A reproduced signal is digitized so as to count a time interval of a specified pattern simultaneously with the count of a clock period of a phase lock loop circuit. A phase lock loop clock frequency is subjected to a feedback control based on the information indicated the difference between the time interval and the clock period. In this manner, a frequency loop performs a feedback operation so that a frequency of the reproduced signal falls within a capture range of a phase lock-in, thereby increasing the speed of phase lock-in.

Data detection apparatus

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Nagaokakyo, Japan

Hiroyuki Miyachi