Recording apparatus

Patent metadata

Field	Value
Publication number	US-2016284375-A1
Application number	US-201615049424-A
Country	US
Kind code	A1
Filing date	Feb 22, 2016
Priority date	Mar 23, 2015
Publication date	Sep 29, 2016
Grant date	—

Abstract

A recording device of the present disclosure includes a light source, an objective lens, a beam splitter, an optical element, a detector and an operation circuit. The optical element divides a light beam into a first main region, a second main region, a first main end region, a second main end region, a first sub-region, and a second sub-region. The operation circuit generates a main signal in which a first main end region signal is multiplied by a coefficient a and added to the first main region signal, and a second main signal in which a second main end region signal is multiplied by the coefficient α and added to the second main region signal.

First claim

What is claimed is:

1 . A recording apparatus comprising:
a light source configured to emit a light beam; an objective lens configured to focus the light beam on a recording medium having a groove-shaped track capable of recording information; a beam splitter configured to split the light beam reflected and diffracted by the recording medium from a light path of the light source; an optical element configured to divide the light beam split by the beam splitter into desired regions; a detector configured to receive a light of each region of the desired regions divided by the optical element; and a first operation circuit configured to calculate a signal received from the detector and output the signal, wherein the optical element divides the light beam split by the beam splitter, into a first main region mainly including a region in which a zero-order light and a plus first-order diffracted light of the track overlap with each other, a second main region mainly including a region in which the zero-order light and a minus first-order diffracted light of the track overlap with each other, a first main end region mainly including both ends in a track tangential direction of the region in which the zero-order light and the plus first-order diffracted light of the track overlap with each other, a second main end region mainly including both ends in the track tangential direction of the region in which the zero-order light and the minus first-order diffracted light of the track overlap with each other, a first sub-region located at both ends outside of the first main end region in the track tangential direction, and a second sub-region located at both ends outside of the second main end region in the track tangential direction, and the first operation circuit generates a first main signal in which a signal from the first main end region is multiplied by a coefficient α that is greater than 1 and added to a signal from the first main region, and a second main signal in which a signal from the second main end region is multiplied by the coefficient α and added to a signal from the second main region.

2 . The recording apparatus according to claim 1 , further comprising,
a second operation circuit configured to receive a signal from the first operation circuit to generate a tracking error signal, and an actuator configured to move a position of a focus spot of the light beam on the recording medium, wherein the second operation circuit generates a main difference signal of a difference signal between the first main signal and the second main signal, and generates a sub-difference signal of a difference signal between a signal from the first sub-region and a signal from the second sub-region, and, multiplies the sub-difference signal by k, where k is a variable gain, and outputs a signal obtained by subtracting the sub-difference signal multiplied by k from the main difference signal, and the actuator receives the signal output from the second operation circuit to move the focus spot of the light beam on the recording medium.

3 . The recording apparatus according to claim 1 , wherein
the optical element further divides the light beam split by the beam splitter into a dummy region corresponding to the central portion of the light beam, and the second operation circuit calculates without a light of the dummy region.

4 . The recording apparatus according to claim 1 , wherein
the first main region and the second main region divided from the optical element exclude near the center portion of the region in which the zero-order light and the plus first-order diffracted light of the track overlap with each other, and near the center portion of the region in which the zero-order light and the minus first-order diffracted light of the track overlap with each other.

5 . The recording apparatus according to claim 1 , wherein
the optical element is a diffraction element configured to guide the light beam diffracted to desired different regions.

6 . The recording apparatus according to claim 1 , wherein
the coefficient α of the first operation circuit is equal to or greater than 3.

7 . The recording apparatus according to claim 1 , wherein
the coefficient α of the first operation circuit is equal to or greater than 5.

8 . The recording apparatus according to claim 1 , wherein
a shape of each end of the both ends in the track tangential direction of the first main end region is a shape that overlaps the region in which the zero-order light and the plus first-order diffracted light of the track overlap with each other, and a shape of each end of the both ends in the track tangential direction of the second main end region is a shape that overlaps the region in which the zero-order light and the minus first-order diffracted light of the track overlap with each other.

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Sano Kousei
• Komma Yoshiaki
• Yamasaki Fumitomo
• Wakabayashi Kanji

Classifications

• G11B7/0943

  Methods and circuits for performing mathematical operations on individual detector segment outputs · CPC title

• G11B7/1353 Primary

  Diffractive elements, e.g. holograms or gratings {(diffraction gratings per se G02B5/18; holograms per se G02B5/32; grating systems G02B27/44)} · CPC title

• G11B7/0901

  for track following only (G11B7/0925, G11B7/094, G11B7/0941, G11B7/0943, G11B7/0945, G11B7/0946, G11B7/0948 take precedence) · CPC title

• G11B7/131

  Arrangement of detectors in a multiple array · CPC title

• G11B7/0904

  Dithered tracking systems · CPC title