Patent ID: 7710673

Claim:
A phase locking apparatus which, when data is recorded on a recording medium as an RLL recording code where d>0 is read therefrom as data in asynchronous relation with a predetermined frequency, generates synchronous data in synchronism with said predetermined frequency from the asynchronous data, said phase locking apparatus comprising phase error information detecting means for detecting phase error information indicating a phase error in said synchronous data, wherein said phase error information detecting means includes: phase position determining means determines, based on run length limited information, whether or not phase positions of a first value and a second value contiguous to said first value from among sampling values constituting said synchronous data are under a reverse phase condition in effect when only one of said first and said second values is in excess of a predetermined threshold; and phase error information calculating means calculates said phase error information in each of two cases determined, one with said reverse phase condition found to be in effect by said phase position determining means and the other without said reverse phase condition found to be in effect; wherein said run length limited information is information based on a minimum run length where d is at least 1; and wherein said run length limited information is information indicating transitions of partial responses based on the limit of said minimum run length to said synchronous data; wherein said partial responses based on the limit of said minimum run length to said synchronous data occur where d=1 and PR(1, −1; and wherein said phase position determining means determines that said reverse phase condition is in effect if the transitions of the patterns occurring where d=1 and PR(1, −1) form a pattern which exist under said reverse phase condition and which does not exist without said reverse phase condition, said phase position determining means further determining that said reverse phase condition is not in effect if said transitions form any other pattern.