Patent ID: 7706232
Filing Date: 2010-04-27
Classification: G11B

Abstract:
1. An information recording medium having at least a read only area and a recording and reproducing area comprising at least: a substrate; a first recording layer formed on the substrate so as to record and reproduce information; a first light transmitting layer having transparency formed on the first recording layer; a second recording layer formed on the first light transmitting layer so as to record and reproduce information; and a second light transmitting layer having transparency formed on the second recording layer, the information recording medium further comprising a wobbling groove corresponding to the read only area and another wobbling groove corresponding to the recording and reproducing area formed on the substrate without overlapping each other, wherein the first and second recording layers and the first and second light transmitting layers are continuously adhered over at least two areas of the read only area and the recording and reproducing area respectively, and wherein a push-pull signal output T wherein each of the wobbling groove corresponding to the read only area and the other wobbling groove corresponding to the recording and reproducing area contains a wobbling groove modulated by any one of the frequency-shift keying method, the phase-shift keying method, and the amplitude-shift keying method, and wherein a track pitch of the wobbling groove corresponding to the read only area is P wherein a wavelength of a reproducing light beam is λ and a numerical aperture of an objective lens for reproducing is NA, and further wherein P