Light spot shaping device and method,light pickup device, and optical disk apparatus
OwnerYoshiyuki Teraoka, Tamotsu Ishii +1inventors
InventorsYoshiyuki Teraoka, Tamotsu Ishii, Goro Fujita
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Abstract
A laser beam for reproduction emitted from an LD (41) at the time of reproduction passes through an As correction board (42) and a grating (43) and becomes incident on a beam splitter (44). The beam splitter (44) transmits the laser beam and causes the laser beam to be incident on a liquid crystal unit (45). Then, at the time of reproduction, a light spot shaping device provides aberration to the laser beam transmitted through the liquid crystal unit (45) in accordance with the type of a magneto-optical disc and thus shapes a light spot on the magneto-optical disc. Therefore, optimum light spots for different media can be shaped.
Claims36
A light spot shaping device for shaping a spot of light cast onto a plurality of types of removable media from the same light source through the same optical path, in accordance with the type of the medium, the device comprising:
- liquid crystal means having a split pattern electrode formed along the direction of a recording track of the medium;
- and
- control means for changing a voltage to be applied to the split pattern electrode of the liquid crystal means in accordance with the type of the medium and thus changing the optical characteristic of the light spot.
A light spot shaping method for shaping a spot of light cast onto a plurality of types of removable media from the same light source through the same optical path, in accordance with the type of the medium, the method comprising
- a control step of providing liquid crystal means having a split pattern electrode formed along the direction of a recording track of the medium and changing a voltage to be applied to the split pattern electrode of the liquid crystal means in accordance with the type of the medium, thus changing the optical characteristic of the light spot.
A light spot shaping device for separately shaping an incident laser beam in recording and in reproduction to a spot of light cast onto a medium for recording and/or reproducing an information signal, the device comprising:
- liquid crystal means having a split pattern electrode formed along the direction of a recording track of the medium;
- and
- control means for changing a voltage to be applied to the split pattern electrode of the liquid crystal means between the recording and the reproduction and thus changing the optical characteristic of the light spot.
A light spot shaping method for separately shaping an incident laser beam in recording and in reproduction to a spot of light cast onto a medium for recording and/or reproducing an information signal, the method comprising
- a control step of providing liquid crystal means having a split pattern electrode formed along the direction of a recording track of the medium and changing a voltage to be applied to the split pattern electrode of the liquid crystal means between the recording and the reproduction, thus changing the optical characteristic of the light spot.
An optical pickup device for forming a spot of light adapted to a plurality of types of removable optical discs having at least different track pitches, onto the optical disc, thus reading an information signal, the device comprising:
- a light source for emitting light;
- an optical system for casting the light emitted from the light source onto a signal recording surface of the optical disc and passing return light reflected by the signal recording surface of the optical disc;
- photodetection means for detecting the return light passed by the optical system;
- liquid crystal means provided in the optical system and having a split pattern electrode stacked in a radial direction of the optical disc;
- and
- light spot shaping means for changing a voltage to be applied to the split pattern electrode of the liquid crystal means for each type of the optical disc and thus changing the optical characteristic of the light spot.
An optical pickup device for casting recording light and/or reproducing light for recording and/or reproducing an information signal to an optical disc, the device comprising:
- a light source for emitting light;
- an optical system for casting the light emitted from the light source onto a signal recording surface of the optical disc and passing return light reflected by the signal recording surface of the optical disc;
- photodetection means for detecting the return light passed by the optical system;
- liquid crystal means provided in the optical system and having a split pattern electrode stacked in a radial direction of the optical disc;
- and
- light spot shaping means for changing the optical characteristic of the light spot between when casting the recording light and when casting the reproducing light.
An optical disc device having a reproducing part for forming a spot of light adapted to a plurality of types of removable optical discs having at least different track pitches, onto the optical disc, thus reading an information signal from each optical disc,
- the reproducing part comprising:
- a light source for emitting light;
- an optical system for casting the light emitted from the light source onto a signal recording surface of the optical disc and passing return light reflected by the signal recording surface of the optical disc;
- photodetection means for detecting the return light passed by the optical system;
- liquid crystal means provided in the optical system and having a split pattern electrode formed along a radial direction of the optical disc;
- and
- light spot shaping means for changing a voltage to be applied to the split pattern electrode of the liquid crystal means in accordance with the type of the optical disc and thus changing the optical characteristic of the light spot;
- the optical disc device reproducing the information signal on the basis of the quantity of the return light detected by the photodetection means.
An optical disc device for casting recording light and/or reproducing light to an optical disc so as to record and/or reproduce an information signal, the device comprising:
- a light source for emitting light;
- an optical system for casting the light emitted from the light source onto a signal recording surface of the optical disc and passing return light reflected by the signal recording surface of the optical disc;
- photodetection means for detecting the return light passed by the optical system;
- liquid crystal means provided in the optical system and having a split pattern electrode stacked in a radial direction of the optical disc;
- and
- light spot shaping means for changing the optical characteristic of the light spot between when casting the recording light and when casting the reproducing light.
Dependencies are inferred from the claim text.