Guide-layer separated optical recording medium, optical recording medium drive apparatus, and recording layer access method

An optical recording medium drive apparatus for driving a guide-layer separated optical recording medium including a guide layer with a guide track formed therein and a plurality of recording layers, the guide layer and the plurality of recording layers being deposited separately from each other, wherein:

• a layer position information region for indicating position information of each of the recording layers, is formed on the guide track within a different range of the guide layer for each of the recording layers;
• each of the recording layers includes a preformat region having a predetermined signal written on a record track along the guide track;
• and the preformat region on each of the recording layers is provided in a region corresponding to the layer position information region,
• the drive apparatus comprising:
• a servo optical system which irradiates the optical recording medium with a first laser beam for a servo via an objective lens to detect a reflected beam from the guide layer;
• a read/write optical system which irradiates the optical recording medium with a second laser beam for reading or writing via the objective lens to detect a reflected beam from one of the plurality of recording layers;
• a reproduced-signal determination portion which determines whether a reproduced signal has been obtained, based on a detection level of a reflected beam from the preformat region by the read/write optical system;
• an information read portion which acquires position information of one of the plurality of recording layers based on a detection level of a reflected beam from the layer position information region by the servo optical system;
• and
• a controller which allows the second laser beam to access a desired one of the plurality of recording layers in accordance with a determination result by the reproduced-signal determination portion and the read position information by the information read portion.

A recording layer access method of an optical recording medium drive apparatus for driving a guide-layer separated optical recording medium including a guide layer with a guide track formed therein and a plurality of recording layers, the guide layer and the plurality of recording layers being deposited separately from each other, wherein:

• a layer position information region for indicating position information of each of the recording layers, is formed on the guide track within a different range of the guide layer for each of the recording layers;
• each of the recording layers includes a preformat region having a predetermined signal written on a record track along the guide track;
• and the preformat region on each of the recording layers is provided in a region corresponding to the layer position information region, and wherein the drive apparatus includes:
• a servo optical system for irradiating the optical recording medium with a first servo laser beam for a servo via an objective lens to detect a reflected beam from the guide layer;
• and a read/write optical system for irradiating the optical recording medium with a second laser beam for reading or writing via the objective lens to detect a reflected beam from one of the plurality of recording layers,
• the method comprising:
• a reproduced-signal determination step of determining whether a reproduced signal has been obtained, based on a detection level of a reflected beam from the preformat region by the read/write optical system;
• an information read step of acquiring position information of one of the plurality of recording layers based on a detection level of a reflected beam from the layer position information region by the servo optical system;
• and
• a control step of allowing the second laser beam to access a desired one of the plurality of recording layers in accordance with a determination result from the reproduced-signal determination step and the read position information from the information read step.