Apparatus for recording and/or reproducing data signal on or from disk shaped recording medium at a variably selected constant linear velocity

Claim 1

In an apparatus for recording and/or reproducing a data signal on or from a disc shaped recording medium having substantially spiral successive tracks arranged in series and in each of which a respective plurality of sectors are formed, said sectors having recorded therein respective address codes numbered in series from one to the other end of said series of successive tracks, said disc shaped recording medium including a special track in which at least control information is recorded indicative of a desired constant linear velocity of said recording medium during reproduction of said data signal within a CLV recording area on said recording medium and used for controlling the rotation of said recording medium in a CLV reproducing mode of said apparatus, said desired constant linear velocity being one of a plurality of values within a predetermined range, said control information recorded in said special track including a parameter indicating the inclination of the increase of the number of sectors from one to another of said successive tracks, said apparatus comprising: a recording and/or reproducing head; means for initially reproducing the control information from said special track on said recording medium; memory means; means for writing the initially reproduced control information in said memory means; means operative in a reproducing mode of the apparatus for reading said control information which has been written in said memory means; means for separating from the signal reproduced by said head the address code associated with each of said sectors scanned by said head; control signal generating means supplied with the control information read from said memory means and the separated address code for generating a control signal based on said control information and said address code, and including an arithmetic unit for generating reference frequency information from each separated address code and said parameter in the control information read from said memory means; and rotation control circuit means supplied with said control signal for controlling the rotation of said recording medium while in said CLV reproducing mode such that the linear velocity of the rotation of said recording medium is maintained at said desired constant value indicated by said control information, said recording medium thereby being controllable to any one of said plurality of values in response to the particular control information recorded on that particular recording medium.