Appeal No. 1997-2681
Application No. 08/211,414
concentric circles partitioned into sectors. Each sector has
a first region with recorded servo data of one frequency and a
second region with recorded information data of different
frequencies. The read out circuit has a filter for the servo
data frequency, and several filters for the different
frequencies of the information data.
Representative independent claim 1 is reproduced as
follows:
1. A circuit for reading out data from a disk having a
plurality of tracks forming concentric circles partitioned
into a plurality of sectors, each sector consisting of a first
region recorded with servo data of the same frequency and a
second region recorded with information data of different
frequencies, said circuit comprising:
pickup means (20) for picking up said data written on
said disk and converting said data into an electrical signal;
first filter means (23) for filtering signal frequencies
corresponding only to the frequencies of said servo data in
said picked-up electrical signal;
second filter means (24) consisting of a plurality of
filters for filtering signal frequencies corresponding to each
frequency of said information data in said picked-up
electrical signal; and
filter selection control means (25) responsive to the
outputs of said first and said second filter means for
recognizing each of the different frequency bands of said data
and for providing a servo signal to said first filter means to
allow said first filter means (23) to be active when said
picked-up electrical signal corresponds to said servo data and
to allow a corresponding one of said filters in said second
2
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