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US 5,856,965 AGranted
Optical disc readout apparatus for different types of optical discs
AssigneeSanyo Electric Co., Ltd.
InventorsYoichi Tsuchiya, Seiji Kajiyama, Yasuyuki Kanou
Life of this patent
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Abstract
An optical disc readout apparatus having an optical system which guides a laser beam onto a signal recording surface of a loaded disc through an objective lens and guides a reflected laser beam onto a photo detector. An effective numerical aperture of the objective lens is adjusted according to the thickness between a substrate surface of the loaded disc and the signal recording surface, and the laser spot with a diameter suitable to a recording density of the loaded disc is focused on the signal recording surface. Therefore, the data recorded in a plurality of optical discs with different thickness or recording densities can be read out.
Claims15
An optical disc readout apparatus comprising:
- a first laser source for emitting a laser beam of plane-polarized light when a disc of first type is loaded;
- second laser source for emitting a laser beam of plane-polarized light when a disc of second type different from the first type is loaded, the polarization plane of the laser beam emitted from the second laser source being orthogonal to the polarization plane of the laser beam emitted from the first laser source;
- an optical system for guiding the laser beam emitted from either the first or the second laser source onto a signal recordind surface of a loaded optical disc and guiding a reflected laser beam therefrom onto a photo detector;
- and
- selective stopping down means for transmitting the laser beam emitted from the first laser source to focus onto the signal recording surface of the loaded optical disc without stopping down and for transmitting the laser beam emitted from the second laser source to focus onto the signal recording surface of the loaded optical disc with stopping down.
2 more elements
An optical disc readout apparatus comprising:
- a first laser source for emitting a laser beam of plane-polarized light when a disc of first type is loaded;
- a second laser source for emitting the laser beam of plane-polarized light when a disc of second type different from the type is loaded, the polarization plane of the laser beam emitted from the second laser source being orthogonal to the polarization plane of the laser beam emitted from the first laser source;
- an optical system for guiding the laser beam emitted from either the first or the second laser source onto a signal recording surface of a loaded optical disc and guiding a reflected laser beam therefrom onto either a first photo detector or a second photo detector;
- selective stopping down means for transmitting the laser beam emitted from the first laser source to focus onto the signal recording surface of the loaded optical disc without stopping down and for transmitting the laser beam emitted from the second laser source to focus onto the signal recording surface of the loaded optical disc with stopping down;
- and
- controlling means for controlling the optical system to guide the reflected laser beam onto the first photo detector when a disc of the first type is loaded and to guide the reflected laser beam onto the second photo detector when a disc of the second type is loaded.
3 more elements
An optical disc readout apparatus comprising:
- a first laser source for emitting a laser beam of plane-polarized light when a disc of first type is loaded;
- a second laser source for emitting the laser beam of plane-polarized light when a disc of second type different from the first type is loaded, the polarization plane of the laser beam emitted from the second laser source being orthogonal to the polarization plane of the laser beam emitted from the second laser source;
- an optical system for guiding a laser beam emitted from either the first or the second laser source onto a signal recording surface of a loaded optical disc and guiding a reflected laser beam therefrom onto either a first photo detector or on a second photo detector and a second photo detector;
- selective stopping down means for transmitting the laser beam emitted from the first laser source to focus onto the signal recording surface of the loaded optical disc without stopping down and for transmitting a laser beam emitted from the second laser source to focus onto the signal recording surface of the loaded optical disc with stopping down;
- and
- switching means for sending the readout signal output from the first photo detector to a readout signal processing circuit when a disc of the first type is loaded and sending the readout signal output from the second photo detector to the readout signal processing circuit when a disc of the second type is loaded.
3 more elements
An optical disc readout apparatus comprising:
- a first laser source for emitting a laser beam of plane-polarized light;
- a second laser source for emitting the laser beam of plane-polarized light, the polarization plane of the laser beam emitted from the second laser source being orthogonal to the polarization plane of the laser beam emitted from the first laser source;
- an optical system for guiding a laser beam emitted from either the first or the second laser source onto a signal recording surface of a loaded optical disc and guiding a reflected laser beam therefrom onto a photo detector;
- selective stopping down means for transmitting the laser beam emitted from the first laser source to focus onto the signal recording surface of the loaded optical disc without stopping down and for transmitting the laser beam emitted from the second laser source to focus onto the signal recording surface of the loaded optical disc with stopping down;
- and
- driving means for driving the first laser source when a disc of first type is loaded and driving the second laser source when a disc of second type is loaded.
3 more elements
Dependencies are inferred from the claim text.