Signal reproducing apparatus for optical recording and reproducing equipment with compensation of crosstalk from nearby tracks and method for the same

• US 5,181,161 A
• Filed: 04/23/1990
• Issued: 01/19/1993
• Est. Priority Date: 04/21/1989
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Hirose, Yutaka, Yamanaka, Yutaka, Okanoue, Kazuhiro
• Primary Examiner(s): Chin, Tommy P.
• Assistant Examiner(s): TRAN, THAI Q
• Application Number:
  US07/513,451
• Time in Patent Office: 1,002 Days
• Field of Search: 369/44.25, 369/44.26, 369/44.27, 369/44.28, 369/44.29, 369/44.31, 369/44.32, 369/44.33, 369/44.34, 369/44.35, 369/44.36, 369/44.37 , 369/44.41, 369/48, 369/49, 369/50, 369/44.11, 369/106, 369/111, 369/112, 369/109, 369/32, 369/124, 358/328, 358/342
• US Class Current: 369/47.26
• CPC Class Codes: G11B 11/10515 Reproducing compensating pit shift G11B11/1053
• CPC Class Codes: G11B 11/10543 using optical beam of radiation
• CPC Class Codes: G11B 11/10595 Control of operating function
• CPC Class Codes: G11B 7/005 Reproducing G11B7/0065 takes precedence
• CPC Class Codes: G11B 7/13 Optical detectors therefor
• CPC Class Codes: G11B 7/14 specially adapted to record on, or to reproduce from, more than one track simultaneously

Abstract

An apparatus and a method for reproducing a signal, free of cross-talk and intersymbol interference, from an optical recording medium. The signal reproducing apparatus and method is for use in combination with an optical source for emitting a plurality of light beams directed to a center track, which contains the information to be reproduced, and the tracks adjacent to the center track on a recording medium. The signals received from the reflections of the light beams from the adjacent tracks are processed by a frequency characteristic converter and then added to the signal from the center track to eliminate the cross-talk in the signal from the center track created by the signals from the adjacent tracks.

Claims

1. A signal reproducing apparatus for use in combination with an optical source for emitting a plurality of light beams directed to a desired track and neighboring tracks on a recording medium and a photodetector means for receiving reflections of said light beams from said desired and neighboring tracks on said recording medium and for producing first and second signals, said desired track being between said neighboring tracks, said desired track storing information to be reproduced, said first signal being delivered from said desired track, said second signals being delivered from said neighboring tracks, said signal reproducing apparatus comprising:

a plurality of filtering means respectively receiving said first and second signals for varying frequency characteristics of said first and second signals to produce first and second characteristic-converted signals;

signal adding means for adding said first characteristic-converted signal and said second characteristic-converted signals to deliver a reproduced signal; and

characteristic control means for controlling a frequency characteristic of a said plurality of filtering means in accordance with said reproduced signal.

2. A signal reproducing apparatus as claimed in claim 1, wherein said filtering means is constructed by a transversal filter.

3. A signal reproducing apparatus as claimed in claim 2, wherein predetermined preamble signals are recorded in said desired and neighboring tracks on said recording medium;

and

said filtering means operates in response to detection of said preamble signal contained in said reproduced signal.

4. A signal reproducing apparatus as claimed in claim 3, wherein said characteristic control means comprises:

means for generating a reference signal corresponding to said preamble signal associated with said desired track;

means for detecting an error between said reference signal and said preamble signal contained in said reproduced signal; and

means for controlling tap coefficients in said transversal filter in response to said error.

5. A signal reproducing apparatus as claimed in claim 2, further comprising decision means receiving said reproduced signal from said signal adding means for delivering a binary signal representative of said information recorded in said desired track, wherein said characteristic control means comprises:

means for calculating an error between said reproduced signal and said binary signal, and

means for controlling tap coefficients in said transversal filter in response to said error.

6. A signal reproducing method for an optical recording and reproducing system which uses an optical head for emitting a light beam onto successive adjacent three tracks on a recording disk and delivering a first signal from a first track storing information to be reproduced and two second signals from second tracks adjacent to said first track, said first and second tracks corresponding to said successive adjacent tracks, said first track being between said second tracks, comprising:

filtering said first signal by a first transversal filter to produce a first filtered signal;

filtering said two second signals by a second transversal filter to produce two second filtered signals;

adding said first and two second filtered signals to an added signal;

binarizing said added signal into a binary signal representative of said information;

comparing said binary signal with said added signal to produce an error signal; and

controlling characteristics of said first and second transversal filters in response to said error signal.

7. A signal reproducing method for an optical recording and reproducing system which uses an optical head for emitting a light beam onto successive adjacent tracks including a center track and two side tracks and delivering a first signal from said center track and two second signals from said two side tracks, said center and side tracks storing respective preamble signals, comprising:

filtering said first signal by a first transversal filter to produce a first filtered signal;

filtering said two second signals by a second transversal filter to produce two second filtered signals;

adding said first and two second filtered signals to produce an added signal;

generating a reference signal corresponding to the preamble signal stored in said center track;

comparing a picked-up preamble signal contained in said added signal with said reference signal to produce an error, said picked-up preamble signal being delivered when said optical head scans said respective preamble signals stored in said center and side tracks; and

controlling characteristics of said first and second transversal filters in accordance with said error.

8. A signal reproducing apparatus for optical recording and reproducing systems which uses an optical head for emitting a plurality of light beams onto three different tracks including a central track and two neighboring tracks on a recording medium and having a plurality of photodetectors for producing first and second signals corresponding to reflections from said central track and said neighboring tracks independently of each other, said apparatus comprising:

a plurality of filtering means each for varying a frequency characteristic of respective one of said first and second signals from said photodetectors independently of each other;

combining means for combining outputs of said plurality of filtering means;

deciding means for executing decision of a signal state on an output of said combining means;

preamble signal detecting means for detecting a preamble signal in said first signal associated with said center track;

reference signal outputting means for outputting a reference signal in response to an output of said preamble signal detecting means;

switch means coupled to said reference signal outputting means and said deciding means for delivering the reference signal when said preamble signal detecting means detects the preamble signal and an output of said deciding means when said preamble signal detecting means does not detect the preamble signal;

error signal outputting means for detecting an error signal out of an output of said switch means and an output of said combining means; and

control means for controlling characteristics of said plurality of filtering means.