Multilayer information recording medium, information recorder, and information reproducer

A multi-layered information recording medium used in an information recording/reproducing apparatus applicable to both a single-layer information recording medium having a single recording layer on one side of that medium and an arbitrary multi-layered information recording medium having two or more recording layers on one side of that medium, the multi-layered information recording medium comprising:

• a plurality of recording layers, each recording layer having a guiding groove and recording marks formed in the guiding groove wherein said recording marks have a minimum mark length that is a quadratic function of a disk thickness of the associated recording layer;
• wherein the plural recording layers include a reference recording layer that has the disk thickness closest to that of the single-layer information recording medium, and the minimum mark length of the recording marks of the reference recording layer is the smallest amongst the plural recording layers.

A multi-layered information recording medium used in an information recording/reproducing apparatus applicable to both a single-layer information recording medium having a single recording layer on one side of that medium and an arbitrary multi-layered information recording medium having two or more recording layers on one side of that medium, the multi-layered information recording medium comprising:

• multiple recording layers, each of the recording layers having a guiding groove and recording marks formed in the guiding groove, the guiding groove having a track pitch determined by a quadratic function of the disk thickness of the associated recording layer, and recording marks having a minimum mark length determined by a quadratic function of the disk thickness of the associated recording layer;
• wherein the multiple recording layers include a reference layer that has a disk thickness closest to that of the single-layer information recording medium, and the track pitch of the guiding groove and the minimum mark length of the recording marks of the reference recording layer are the smallest amongst the multiple recording layers.

An information recording apparatus operative for both a single-layer information recording medium having a single recording layer on one side of the medium and a multi-layered information recording medium having multiple recording layers on one side of the medium, the apparatus comprising:

• a pickup device configured to read data about a currently processed recording layer from the recording medium;
• and
• a writing unit configured to write information in a multi-layered information recording medium by forming recording marks in each of multiple recording layers of the multi-layered information recording medium wherein said recording marks formed in each of the recording layers have a minimum mark length that is a quadratic function of a disk thickness of the associated recording layer, wherein the multiple recording layers include a reference recording layer having a disk thickness closest to that of the single-layer information recording medium, and the recording mark having a minimum mark length formed in the reference layer becomes the smallest amongst the multiple recording layers of the multi-layered information recording medium.