Data reproduction apparatus for optical disc system

Details Data reproduction apparatus for optical disc system Data reproduction apparatus for optical disc system

1999-11-18

2001-10-23

Huber, Paul W. (Department: 2651)

Dynamic information storage or retrieval

Control of storage or retrieval operation by a control...

Control of information signal processing channel

C369S059210, C360S032000

Reexamination Certificate

active

06307822

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Application No. 98-49542, filed Nov. 18, 1998, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a data reproduction apparatus for an optical disc system.
2. Description of the Related Art
FIG. 1
is a block diagram showing a data reproduction apparatus for a conventional optical disc system. In the
FIG. 1
apparatus, a radio frequency (RF) signal read from an optical disc is input to an analog-to-digital converter (ADC)
11
and a binarization circuit
14
. The binarization circuit
14
binarizes the RF signal and outputs the binarization signal to a phase locked loop (PLL)
15
. The PLL
15
receives the binarization signal and generates a clock signal PLCK synchronized with the RF signal. The clock signal PLCK is supplied to the ADC
11
, a waveform equalizer
12
and a Viterbi decoder
13
. The ADC
11
converts the input analog RF signal into a digital RF signal and outputs the digital RF signal to the waveform equalizer
12
. The waveform equalizer
12
receives the digital RF signal and waveform-equalizes the received digital RF signal into a form which is appropriate for the Viterbi decoder
13
. The Viterbi decoder
13
receives the waveform equalized signal to then be Viterbi decoded and outputs the result as a reproduction signal (VITO). The Viterbi decoding can restore the damaged signal when the RF signal is damaged due to noise interference in a channel, such as that which is widely used in a hard disc drive (HDD).
However, if in the input RF signal in the conventional data reproduction apparatus is asymmetrical, the Viterbi decoder does not restore the RF signal, thereby degenerating the quality of the reproduced data.
SUMMARY OF THE INVENTION
To solve the above problems, it is an object of the present invention to provide a data reproduction apparatus for an optical disc system which corrects asymmetry of an RF signal to improve the quality of the reproduced data.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
To accomplish the object of the present invention, a data reproduction apparatus is provided for an optical disc system in which a radio frequency (RF) signal detected from an optical recording medium is decoded to reproduce data, the data reproduction apparatus comprising: an analog-to-digital converter (ADC) for sampling the input RF signal and outputting the sampled result; an adder for adding the sampled signal and an asymmetry correction signal and outputting the added signal; a blank/defect detector for generating a blank detection signal if no change in data is detected from the added signal during a predetermined interval of time; a correction signal generator for calculating a digital sum value (DSV) from the received added signal, generating an asymmetry correction signal based on the calculated DSV, and outputting the generated asymmetry correction signal to the adder; a waveform equalizer for waveform-equalizing the added signal; and a decoder for decoding the waveform-equalized signal and outputting the result. Here, if a blank detection signal is output, the correction signal corrector temporarily stops a DSV calculation operation with respect to the interval of the corresponding added signal.


REFERENCES:
patent: 5333126 (1994-07-01), Fukuda et al.
patent: 5721548 (1998-02-01), Choe et al.
patent: 5737371 (1998-04-01), Jaquette
M. Tobita et al.; “Viterbi Detection of Partial Response on a Magneto-Optical Recording Channel”; 1992; vol. 1663, pp. 166-173.
Patent Abstracts of Japan; Japanese Publication No. 10106160, published Apr. 24, 1998.

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