US 6,982,127 B2
Information recording medium, and apparatuses for reproducing, recording, and recording and reproducing thereof, and methods for reproducing, recording, and recording and reproducing thereof
Tetsuya Kondo, Yokohama (Japan); and Kenji Oishi, Yokohama (Japan)
Assigned to Victor Company of Japan, Ltd., Yokohama (Japan)
Filed on Jun. 04, 2003, as Appl. No. 10/453,653.
Claims priority of application No. 2002-162591 (JP), filed on Jun. 04, 2002.
Prior Publication US 2003/0224215 A1, Dec. 04, 2003
Int. Cl. G11B 5/65 (2006.01)
U.S. Cl. 428—836 6 Claims
OG exemplary drawing
 
1. An information recording medium at least comprising:
a substrate;
a second recording layer formed on the substrate for recording information;
a second light transmitting layer formed on the second recording layer;
a first recording layer formed on the second light transmitting layer for recording different information from that recorded in the second recording layer, and
a first light transmitting layer formed on the first recording layer;
the second recording layer being formed with a second continuous microscopic pattern of a plurality of raised portions and recessed portions formed alternately viewed from the first light transmitting layer side; and
the first recording layer being formed with a first continuous microscopic pattern of a plurality of raised portions and recessed portions formed alternately viewed from the first light transmitting layer side and different from the second microscopic pattern;
both the first microscopic pattern and the second microscopic pattern satisfying a relation of P≤λ/NA, wherein P is a pitch of the raised portion, λ is a wavelength of reproducing light for reproducing the first recording layer and the second recording layer, and NA is a numerical aperture of an objective lens; and
a sidewall of the raised portion of the first microscopic pattern and the raised portion of the second microscopic pattern being continuously wobbled in alternating sections corresponding to auxiliary information and a reference clock, wherein the auxiliary information is a frequency-shift keying modulation wave having two different frequencies and the reference clock is a sinusoidal wave having a single frequency respectively, and
wherein both sidewalls of the raised portion are parallel with each other.