DATA REPRODUCING APPARATUS BRIEF DESCRIPTION OF THE DRAWINGS
This a divisional of application Ser. No. 08/290.233, filed Aug. 15, 1994, now abandoned.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a data reproducing apparatus, and more particularly to an improvement of optical disc device which is utilized as an auxiliary memory unit for a computer.
2. Description of the Related Art
Heretofore, there is an optical disc device which is used as an auxiliary memory unit for a computer, etc. 15
In this optical disc device, there are optical disc devices for reproducing only which use-read-only optical discs and optical disc devices which use writable optical discs, such as magnetic optical discs and the like.
In these types of optical, disc devices, the content of an 20 optical disc can be copied easily. Thus, a problem occurs regarding the protection of a copyrighted data.
Also, data representing the data structure of disc, DDS (Disc Definition Structure), is recorded in the optical disc. For example, the information for sector interchange- 25 processing, etc. is recorded in the DDS.
The DDS is such important data as to be recorded twice each in the innermost and the outermost of an optical disc. If one DDS becomes impossible to error correct, the data structure can be obtained from another DDS recorded in another area.
However, even though the DDS is recorded four times, it may prove to be insufficient in some cases. This is a problem in that the optical disc can not be used when all DDS become 35 impossible to error correct.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of this invention is to provide a data reproducing apparatus for solving the above 40 problems.
More specifically, this invention provides a driving apparatus for driving a disc recording medium on which a plurality of sets of user data and a plurality of unique data, each of which is related to each set of the user data, are 45 recorded. The disc driving apparatus comprises reproducing means for reproducing the unique data and the user data recorded on the disc recording medium, error correction means for correcting errors in the data reproduced by the reproducing means and detecting an error rate of me data 50 reproduced by the reproducing means, and data replacement means for recording the unique data which is error-corrected by the error correction means in a replacement area of the disc recording medium when the error rate of the unique data is higher than a first reference error rate and for recording the 55 user data which is error-corrected by the error correction means in the replacement area of the disc recording medium when the error rate of the user data is higher than a second reference error rate which second reference error rate is different from the first reference error rate. In the preferred 60 embodiment the first reference error rate is less than the second reference error rate.
The nature, principle and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying draw- 65 ings in which like parts are designated by like reference numerals or characters.
In the accompanying drawings:
FIG. 1 is a block diagram showing the whole construction of an optical disk device according to mis invention;
FIG. 2 is a schematic diagram explaining a sector format of the optical disc which is used in this invention;
FIG. 3 is a flow chart explaining the first embodiment of this invention;
FIG. 4 is a schematic diagram explaining an optical disc which is applied to the second embodiment of this invention;
FIG. 5 is a schematic diagram explaining the operation of the optical disc device according to the second embodiment of this invention;
FIG. 6 is a flow chart explaining the second embodiment of this invention;
FIG. 7 is a flow chart explaining the third embodiment of this invention; and
FIG. 8 is a flow chart explaining the fourth embodiment of this invention.
DETAILED DESCRIPTION OF THE
Preferred embodiments of this invention will be described with reference to the accompanying drawings:
In FIG. 1,1 denotes an optical disc device, which records and/or reproduces the desired data by utilizing an optical disc 2 capable of recording and/or reproducing, and also reproduces the desired data from a reproduction only optical disc 2.
In this optical disc device 1, an optical-magnetic disc which is able to record and/or reproduce the desired data by applying the thermomagnetic recording scheme and a ROM (read only memory) disc for reproduction which has been produced by applying the same scheme as the compact disc, are applicable.
A spindle motor S is driven by a spindle motor control circuit 3, so that an optical disc 2 is rotated with a predetermined rotating speed.
In mis state, a laser control circuit 4 is caused to project a light beam from an optical pick-up 5 to the optical disc 2, by driving a laser diode which is included in the optical pick-up 5.
The optical pick-up 5 receives a reflected light of this light beam on the light-receiving element, and then outputs the result of the light-receiving to an RF signal processing circuit 6.
The RF signal processing circuit 6 performs a currentvoltage transforming process of this result of the lightreceiving and then performs an add-subtract processing at the stated matrix circuit, in order to generate a tracking error signal TE and a focus error signal FE, and then outputs the tracking error signal TE and the focus error signal FE to a servo control circuit 7.
The servo control circuit 7 positions the optical pick-up 5 and an object lens which is included in the optical pick-up 5, based on the tracking error signal TE and the focus error signal FE, so as to perform tracking control and a focus control.
In addition, the servo control circuit 7 causes the optical pick-up 5 to seek in the radial direction of the optical disc, in response to a control command which is output from a system control circuit 9, so as to access the optical disc 2.
Further, the RF signal processing circuit 6 generates a reproduced sum signal in which the signal level changes in