Optical pickup apparatus for optical record media and identification apparatus for identifying the type of optical record media

An information reproducing apparatus adapted to reproduce one of at least first and second type optical record media which is loaded on said information reproducing apparatus, said first and second type optical record media having distances from surfaces to information record planes different from each other, said information reproducing apparatus comprising:

• (a) an optical pickup apparatus including:
• a light emission means for emitting a reading light,
• an objective lens for focusing the emitted reading light onto the information record plane of said loaded one of said first and second type optical record media,
• a focus coil for driving said objective lens in a focusing direction such that a focus condition of the focused reading light is optimum with respect to said first type optical record medium,
• a correction means for correcting a spherical aberration of the focused reading light with respect to said second type optical record medium due to a difference in the distances from the surfaces to the information record planes between said first and second type optical record media when said second type optical record medium is loaded, and
• a light receiving means for receiving a reflection light of the focused reading light from the information record plane of said loaded one of said first and second optical record media and for outputting a light detection signal corresponding to the received reflection light;
• (b) an identification apparatus including:
• a detection means for detecting a voltage corresponding to a current which flows through the focus coil when a focusing condition is optimum, and outputting a voltage signal indicating the detected voltage,
• a low pass filter for passing a low frequency component of the voltage signal and outputting a low frequency component signal, and
• a comparison means for comparing a voltage of the low frequency component signal with at least one standard voltage, which is set in advance based on the distances from the surfaces to the information record planes of said first and second optical record media, and for outputting a disc identification signal, which indicates the type of said loaded optical record medium, on the basis of a result of comparing;
• and
• (c) a signal processing apparatus for processing the light detection signal outputted from said optical pickup apparatus.