Information reading and recording apparatus
AssigneeMinebea Co., Ltd.
InventorsMizuki Nakamura, Atsushi Kitamura, Kozo Matsumoto
Life of this patent
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Abstract
An information reading and recording apparatus includes a super-resolution cut-off filter having an annular metal reflection film at its center portion and disposed immediately before one of two objective lenses with a higher NA. When reading DVD, the one objective lens with a higher NA with the super-resolution cut-off filter disposed therebefore is positioned at the optical path. When reading CD, the other objective lens with a lower NA is positioned at the optical path. The laser beam reflected by a disk follows backward the incoming optical path to pass through a half mirror, and is received by a photo-detector to be converted into an electrical signal.
Claims3
An information reading and recording apparatus comprising:
- a semiconductor laser;
- a collimating lens adapted to converge a divergence angle of a laser beam emitted from the semiconductor laser;
- two objective lenses having respective numeral apertures suitable for reading and recording two types of recording media each having a recording density different from other, and adapted to converge the laser beam onto respective recording media;
- a super-resolution cut-off filter comprising a light-transmissible substrate, having an annular reflecting means at a center portion of the substrate, and disposed immediately before one objective lens of the two corresponding to one recording medium of the two types with a higher recording density;
- and
- a photo-detector adapted to detect a reflected laser beam from any one of the two types of recording media,
- whereby information is read and recorded compatibly in the two types of recording media.
Dependencies are inferred from the claim text.