Patent ID: 7035196

Claim:
An optical head device that is configured to carry out reproduction or recording with respect to a plurality of optical information recording media of various types of pit rows or guide grooves, comprising: a plurality of semiconductor lasers that are disposed on one substrate and that are provided so as to correspond respectively to the plurality of optical information recording media of various types of pit rows or guide grooves; optical elements disposed on an optical path between the plurality of semiconductor lasers and an optical information recording medium; and a plurality of photodetectors where returning light from the optical information recording medium enters, wherein the plurality of semiconductor lasers are disposed so that beam spots, formed on the optical information recording medium, of light beams emitted from the plurality of semiconductor lasers are aligned in a substantially same direction as a pit-row direction or a guide groove direction, wherein the pit-row direction and the guide groove direction are both aligned along a tangential direction in the optical information recording medium, wherein the optical elements and the plurality of photodetectors are disposed so that part of returning light from the optical information recording medium, which originates in each of the light beams emitted from the plurality of semiconductor lasers, enters one of the plurality of photodetectors at a time, and wherein each of the plurality of photodetectors includes a light-receiving region divided into two parts in a direction that is substantially parallel to or substantially perpendicular to the pit-row direction or the guide groove direction in the optical information recording medium, part of returning light from the optical information recording medium being detected therein irrespective of which of the plurality of semiconductor lasers emits light beams.