| US 7,558,170 B2 | ||
| Optical pick-up head, optical information apparatus, and optical information reproducing method | ||
| Shin-ichi Kadowaki, Sanda (Japan); Kousei Sano, Osaka (Japan); Akihiro Arai, Souraku-gun (Japan); Katsuhiko Yasuda, Neyagawa (Japan); Tomotada Kamei, Neyagawa (Japan); Hiroaki Yamamoto, Kawabe-gun (Japan); and Fumitomo Yamasaki, Nara (Japan) | ||
| Assigned to Panasonic Corporation, Osaka (Japan) | ||
| Filed on Oct. 31, 2007, as Appl. No. 11/981,366. | ||
| Application 11/789078 is a division of application No. 10/646602, filed on Aug. 22, 2003, granted, now 7,227,819. | ||
| Application 11/981366 is a continuation of application No. 11/789078, filed on Apr. 23, 2007, granted, now 7,463,561. | ||
| Claims priority of application No. 2002-243059 (JP), filed on Aug. 23, 2002; application No. 2003-048932 (JP), filed on Feb. 26, 2003; application No. 2003-050846 (JP), filed on Feb. 27, 2003; application No. 2003-052828 (JP), filed on Feb. 28, 2003; and application No. 2003-052829 (JP), filed on Feb. 28, 2003. | ||
| Prior Publication US 2008/0084798 A1, Apr. 10, 2008 | ||
| Int. Cl. G11B 7/00 (2006.01) | ||
| U.S. Cl. 369—44.41 [369/44.34; 369/44.29; 369/44.28; 369/112.01] | 4 Claims |
| 1. An optical information apparatus, comprising:
an optical pick-up head including:
a light source emitting a light beam;
a condensing unit receiving beams from the light source and condensing the beams onto an optical recording medium;
a beam splitter receiving the beams reflected from the optical recording medium and splitting the beams; and
a photodetector receiving the beams split by the beam splitter in at least four light-receiving portions and outputting signals
in accordance with amounts of the received beams; and
a tracking error signal generator generating a tracking error signal for irradiating a desired track with a beam,
the optical recording medium having tracks at a track pitch of tp,
wherein assuming that a signal proportional to a difference between light amounts of two regions divided by a dividing line
that passes through a center of the beam and is parallel to the track is a push-pull signal, and
an amplitude of the push-pull signal is fluctuated when the light beam is scanned in a direction orthogonal to the track of
the optical recording medium,
the tracking error signal generator obtains a tracking error signal by an arithmetic operation: (I1−I2)−k(I3−I4), where assuming that outputs of the four light-receiving portions receiving the beam are I1 to I4, and k is a real number, signals I1 and I2 output from the light-receiving portions are signals output from the light-receiving portions which have received a region
where 0th order diffracted light that is simply reflected from the optical recording medium and 1st order diffracted light that is diffracted by tracks at the track pitch of to of the optical recording medium are overlapped
with each other, and signals I3 and I4 output from the light-receiving portions are signals output from the light-receiving portions which have received most of
a region where the 0th order diffracted light that is simply reflected from the optical recording medium and the 1st order diffracted light that
is diffracted by the tracks at the track pitch of tp of the optical recording medium are not overlapped with each other.
|