Mitsubishi Electric Assigned Patent

Mitsubishi Electric Corporation, Tokyo, Japan, has been assigned a patent (8,942,074) developed by Nakahara, Hironori, Takeshita, Nobuo, and Ogawa, Masaharu, Tokyo, Japan, for a “optical disc and optical disc device.”

The abstract of the patent published by the U.S. Patent and Trademark Office states: “In a multilayer optical disc having information layers conforming to a plurality of different optical disc standards, because the type of each information layer is not recorded in the other information layers, in read and write operations by a compatible optical disc device conforming to a plurality of optical disc standards, every time the information layer being accessed changes, it has been necessary to read the type of the information layer and select a method of generating a tracking error signal adapted to the type of information layer, so access has taken time. In order to solve the above problem, in the optical multilayer disc according to the present invention, having information layers conforming to a plurality of different optical disc standards, in an area in one of the information layers, information about the other information layers is recorded. The time required to access the other information layers can be reduced by using this information to select a tracking error signal generating method.“

The patent application was filed on October 25, 2013 (14/063,826).