Information recording medium, information supply system, and optical information device

An optical information device, comprising:

• an optical head device, the optical head device including
• a blue light source,
• a red light source,
• a light collection optical system configured to converge light emitted from the blue light source onto a first-type information recording layer of an optical disk that is provided at a distance in a range of 0.06 mm to 0.11 mm from a surface of the optical disk, and converge light emitted from the red light source onto a second-type information recording layer of the optical disk that is provided at a distance in a range of 0.54 mm to 0.65 mm from the surface of the optical disk, and
• a light detector configured to receive light reflected by the first-type information recording layer and/or the second-type information recording layer of the optical disk and perform photoelectric conversion converting the received light into an electric signal;
• a motor that rotates the optical disk;
• and
• an electric circuit configured and arranged to receive the electric signal from the optical head device, and control and drive the motor, the light collection optical system, and/or the light sources based on the signal,
• wherein the optical information device reproduces information from an optical disk having both of the first-type information recording layer and the second-type information recording layer,
• the blue light source of the optical head device emits light upon an instruction for optical disk reproduction being outputted from the electric circuit,
• the distance from the surface of the optical disk to an adjacent recording information layer is measured,
• when it is determined that a reflective layer is present at a distance in the range of 0.06 mm to 0.11 mm from the surface of the optical disk, the reflective layer is determined to be the first-type information recording layer, a focus servo is applied to the first-type information recording layer, and reproduction of the first-type information recording layer is commenced,
• when it is determined that a reflective layer is not present at the distance in the range of 0.06 mm to 0.11 mm from the surface of the optical disk, the red light source is switched from the blue light source and emits light, and the distance from the surface of the optical disk to an adjacent recording layer is measured by the emission of the light from the red light source that has been switched from the blue light source, and
• when it is determined that a reflective layer is present at a distance in the range of 0.54 mm to 0.65 mm from the surface of the optical disk based on the light emitted from the red light source that has been switched from the blue light source, the reflective layer is determined to be the second-type information recording layer, a focus servo is applied to the second-type information recording layer, and reproduction of the second-type information recording layer is commenced.

An information reproduction method executed by an optical information device comprising:

• an optical head device which includes
• a blue light source,
• a red light source,
• a light collection optical system configured to converge light emitted from the blue light source onto a first-type information recording layer of an optical disk that is provided at a distance in a range of 0.06 mm to 0.11 mm from a surface of the optical disk, and converge light emitted from the red light source onto a second-type information recording layer of the optical disk that is provided at a distance in a range of 0.54 mm to 0.65 mm from the surface of the optical disk, and
• a light detector configured to receive light reflected by the first-type information recording layer and/or the second-type information recording layer of the optical disk and perform photoelectric conversion converting the received light into an electric signal;
• a motor that rotates the optical disk;
• and
• an electric circuit configured and arranged to receive the electric signal from the optical head device, and control and drive the motor, the light collection optical system, and/or the light sources based on the signal,
• wherein the optical information device reproduces information from an optical disk having both of the first-type information recording layer and the second-type information recording layer, said method comprising:
• emitting light from the blue light source of the optical head device upon an instruction for optical disk reproduction being outputted from the electric circuit;
• measuring the distance from the surface of the optical disk to an adjacent recording information layer;
• when it is determined that a reflective layer is present at a distance in the range of 0.06 mm to 0.11 mm from the surface of the optical disk, determining that the reflective layer is the first-type information recording layer, applying a focus servo to the first-type information recording layer, and commencing reproduction of the first-type information recording layer;
• when it is determined that a reflective layer is not present at the distance in the range of 0.06 mm to 0.11 mm from the surface of the optical disk, switching from the blue light source to the red light source such that the red light source emits light, and measuring the distance from the surface of the optical disk to an adjacent recording layer;
• and
• when it is determined that a reflective layer is present at a distance in the range of 0.54 mm to 0.65 mm from the surface of the optical disk based on the light emitted from the red light source that has been switched from the blue light source, determining that the reflective layer is the second-type information recording layer, applying a focus servo to the second-type information recording layer, and commencing reproduction of the second-type information recording layer.