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    • 4. 发明授权
    • Diffraction grating for an optical pickup device
    • 用于光学拾取器件的衍射光栅
    • US5065380A
    • 1991-11-12
    • US397189
    • 1989-08-23
    • Taizo Yokota
    • Taizo Yokota
    • G11B7/09G11B7/095G11B7/13G11B7/135
    • G11B7/13G11B7/0956G11B7/1353G11B7/0916
    • An optical pickup device for focusing an irradiating ray from a light emitting element on a recording medium and letting a reflected ray reflected from this recording medium focus on a light receiving element is characterized in comprising a diffracting element disposed before the light emitting element and the light receiving element, at least a first diffraction region included in the diffracting element for separating the irradiating ray from the light emitting element into a main beam and sub-beams shifted from the main beam in a direction perpendicular to a track direction of the track where the main beam is focused, a second diffraction region included in the diffracting element for directing a reflected ray of the main beam reflected from the recording medium onto a main light receiving element and directing reflected rays of the sub-beams onto sub-light receiving elements, and an arithmetic circuit for detecting a tilt error signal showing the sub-beam's focusing condition according to the output of the sub-light receiving elements, whereby an optical pickup device does not require installment of any separate tilt sensor for detection of a tilt signal, and also enables prevention of increasing the number of components and the increase of cost as a result of increased assembly steps and/or the required man-hours.