Optical medium reproducing apparatus, optical medium reproducing method, and optical medium

Patent metadata

Field	Value
Publication number	US-10014023-B2
Application number	US-201515505442-A
Country	US
Kind code	B2
Filing date	Nov 9, 2015
Priority date	Nov 10, 2014
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

Provided is an optical medium reproducing apparatus including: a detection unit that divides a luminous flux into a plurality of regions including a first region and a second region which are different in a position in a radial direction and/or a tangential direction, and combines a plurality of detection signals in correspondence with the amount of light that is incident to each of the plurality of regions with combination patterns which are selected to form signals of a plurality of channels; a multi-input equalizer unit that includes a plurality of equalizer units to which the signals of the plurality of channels are respectively supplied, computes outputs of the plurality of equalizer units, and outputs the resultant value as an equalization signal; and a binarization unit that performs binarization processing with respect to the equalization signal to obtain binary data. An addition signal channel including a constant multiplication of detection signals of the first region and the second region is included in at least one of the combination patterns.

First claim

The invention claimed is:

1. An optical medium reproducing apparatus, comprising:
a light source;
an objective lens that allows a light beam emitted from the light source to condense onto an optical medium;
a detection unit that divides a luminous flux of light beams reflected from the optical medium into a plurality of regions including a first region and a second region which are different in a position in a radial direction and/or a tangential direction, and combines a plurality of detection signals in correspondence with the amount of light that is incident to each of the plurality of regions with combination patterns which are selected to form signals of a plurality of channels;
a multi-input equalizer that includes a plurality of equalizer circuits to which the signals of the plurality of channels are respectively supplied, computes outputs of the plurality of equalizer circuits, and outputs the resultant value as an equalization signal; and
a binarization circuit configured to perform binarization processing with respect to the equalization signal to obtain binary data,
wherein an addition signal channel including a constant multiplication of a detection signal of the first region and a detection signal of the second region is included in at least one of the combination patterns.

2. The optical medium reproducing apparatus according to claim 1 ,
wherein the first region and the second region are disposed at positions different in the tangential direction.

3. The optical medium reproducing apparatus according to claim 2 ,
wherein a sum signal channel of the detection signal of the first region and the detection signal of the second region, and a difference signal channel of the detection signal of the first region and the detection signal of the second region are included in at least one of the combination patterns.

4. The optical medium reproducing apparatus according to claim 1 ,
wherein the multi-input equalizer is set to a configuration of a multi-input adaptive equalizer, and
an initial value of a filter coefficient is changed in conjunction with change of the combination patterns.

5. The optical medium reproducing apparatus according to claim 1 ,
wherein the multi-input equalizer is set to a configuration of a multi-input adaptive equalizer, and
the optical medium reproducing apparatus further comprises an equalization error computation circuit that obtains an equalization error from an equalization target signal obtained on the basis of a binarization detection result in the binarization circuit, and the equalization signal output from the multi-input adaptive equalizer, and supplies the equalization error to the multi-input adaptive equalizer as a control signal for adaptive equalization.

6. The optical medium reproducing apparatus according to claim 5 ,
wherein the multi-input adaptive equalizer performs partial response equalization processing with respect to an output signal,
the binarization circuit performs maximum likelihood decoding processing as binarization processing with respect to the equalization signal of the multi-input adaptive equalizer, and
the equalization error computation circuit obtains an equalization error through computation using an equalization target signal obtained through convolution processing of a binarization detection result obtained by the maximum likelihood decoding, and an equalization signal output from the multi-input adaptive equalizer.

7. The optical medium reproducing apparatus according to claim 5 ,
wherein the multi-input adaptive equalizer performs partial response equalization processing with respect to an output signal, and selects a class of the partial response equalization processing in correspondence with setting of the combination patterns.

8. The optical medium reproducing apparatus according to claim 1 ,
wherein the detection unit includes detectors which are divided in correspondence with the plurality of regions, and
detection signals of the plurality regions are fetched from the photodetectors.

9. The optical medium reproducing apparatus according to claim 1 ,
wherein an optical path conversion element for separation into the plurality of regions is disposed on an optical path that passes through the objective lens and reaches a detector, and a plurality of beams separated by the optical path conversion element are respectively input to detectors different from each other.

10. The optical medium reproducing apparatus according to claim 1 ,
wherein in the optical medium, a land and a groove are alternately formed, and
an optical signal, which is recorded in the land and the groove as information, is reproduced.

11. The optical medium reproducing apparatus according to claim 1 ,
wherein the combination patterns are set in correspondence with a linear density of the optical medium.

12. The optical medium reproducing apparatus according to claim 10 ,
wherein the combination patterns are set in reproduction of the land and reproduction of the groove.

13. The optical medium reproducing apparatus according to claim 1 ,
wherein the optical medium is a multi-layer optical medium, and the combination patterns are set in correspondence with a reproduction layer.

14. The optical medium reproduction apparatus according to claim 1 ,
wherein the combination patterns are set in accordance with a state of a tap coefficient that is optimized by the adaptive equalizer.

15. The optical medium reproducing apparatus according to claim 14 ,
wherein in a system in which a sum or a difference of the detection signal of the first region and the detection signal of the second region is used, the first region and the second region being located in the tangential direction among the plurality of regions, an amplitude of a tap coefficient corresponding to a signal composed of the difference is set as an index.

16. An optical medium reproducing method, comprising:
dividing a luminous flux of light beams reflected from an optical medium into a plurality of regions including a first region and a second region which are different in a position in a radial direction and/or a tangential direction;
combining a plurality of detection signals in correspondence with the amount of light that is incident to each of the plurality of regions by a detection unit with combination patterns which are selected to form signals of a plurality of channels;
computing outputs of a plurality of equalizer circuits by a multi-input equalizer including the plurality of equalizer circuits to which the signals of the plurality of channels are respectively supplied, and outputting the resultant value as an equalization signal; and
performing binarization processing with respect to the equalization signal by a binarization circuit to obtain binary data,
wherein a sum signal channel of the detection signal of the first region and the detection signal of the second region is included in at least one of the combination patterns.

17. The optical medium reproducing method according to claim 16 ,
wherein the first region and the second region are disposed at positions different in the tangential direction.

18. The optical medium reproducing method according to claim 16 ,
wherein a sum signal channel of the detection signal of the first region and the detection signal of the second region, and a difference signal channel of the detection signal of the first region and the detection signal of the second region are included in at least one of the combination patterns.

Assignees

• Sony Corp

Inventors

• Nishi Noriaki
• Saito Kimihiro
• Ando Nobuhiko
• Shiraishi Junya
• Tentaku Yutaka

Classifications

• G11B7/1381

  Non-lens elements for altering the properties of the beam, e.g. knife edges, slits, filters or stops (G11B7/1353 - G11B7/1369 take precedence) · CPC title

• B29D17/005

  Producing optically read record carriers, e.g. optical discs · CPC title

• G11B23/281

  by changing the physical properties of the record carrier · CPC title

• G11B23/284

  on the record carrier · CPC title

• G11B7/263

  Preparing and using a stamper, e.g. pressing or injection molding substrates (production of optical record carriers, e.g. optical discs B29D17/005) · CPC title