Disc reproducing method and apparatus with multiple heads

Claim 1

A disc reproducing apparatus for reproducing data stored on a plurality of disc surfaces at a constant linear density comprising: (a) rotating means for rotating said disc surfaces at a constant rotational speed; (b) a plurality of heads for reproducing said data on said plurality of disc surfaces at the same time respectively; (c) position detection means for detecting positions of said plurality of heads to produce position signals; (d) position control means for controlling radial positions of said plurality of heads such that a total of data rates of data reproduced by said plurality of heads in accordance with said position signals is constant, each of said disc surfaces being divided into N circumference zones, wherein said N is a natural number; (e) N signal processing circuits for processing said reproduced data respectively, said N signal processing circuits having N processing speeds corresponding to N data rate ranges corresponding to said N circumference zones; (f) switch means for supplying said reproduced data to said N signal processing circuits in accordance with at least one of said position signals such that data reproduced by each of said plurality of heads is supplied to a respective one of said N signal processing circuits corresponding to a respective one of said N circumference zones at which said each of plurality of heads is located; and (g) combining means for combining said processed data signals from said N signal processing circuits into a combined serial data signal of which data rate corresponds to said total of data rates.