US 5,475,665 AGranted

Optical information writing and reading apparatus having two light sources

AssigneeOlympus Optical Co., Ltd.

InventorsNaoaki Tani, Mitsuo Oshiba

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Abstract

An apparatus for writing and reading information on and from an optical card by projecting a writing light beam and at least two reading light beams onto the optical card includes a first semiconductor laser for emitting a writing laser beam, a second semiconductor laser for emitting a reading laser beam, a diffraction grating for diffracting the reading laser beam into multiple reading laser beams, and an objective lens for projecting the writing laser beam and the reading laser beams onto the optical card. A reading laser beam spot is formed on the optical card at a middle point between two reading laser beam spots. Images of the reading laser beam spots are received by first and second light receiving elements, respectively. By processing output signals from the first and second light receiving elements, it is possible to verify the recorded condition of pits immediately after recording in regardless of a direction in which the optical card is moved. It is also possible to check the condition of the information track immediately before the writing. In this manner, the writing operation can be performed at a high speed in a suitable and reliable manner.

Claims10

Dependent claims

An apparatus for writing and reading information on and from an optical record medium comprising:

a first light emitting means for emitting a writing light beam;
a second light emitting means for emitting a reading light beam;
an optical system for producing, from said reading light beam, at least first and second reading light beams for reading information written on the optical record medium by the writing light beam and projecting the writing light beam and said first and second reading light beams onto the optical record medium such that a writing light spot formed on the optical record medium by the writing light beam is positioned between a first reading light spot formed on the optical record medium by the first reading light beam and a second reading light spot formed on the optical record medium by the second reading light beam;
a first photoelectric converting means for receiving an image of the first reading light spot to produce a first reproduced signal;
and
a second photoelectric converting means for receiving an image of the second reading light spot to produce a second reproduced signal;
said second light emitting means comprising means for diverging said reading light beam in such a direction that said first and second reading light spots are elongated in a direction perpendicular to a track direction of information tracks on said optical record medium to illuminate a plurality of said information tracks simultaneously.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/273,140Filed 14 Jul 1994 · continuation
Priority: JP 3-2607558 Oct 1991
Granted: 12 Dec 1995
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G11B 7/1353
Means for guiding the beam from the source to the record carrier or from the record carrier to the detector: diffractive elements, e.g. holograms…
G11B 7/0033
Recording, reproducing or erasing systems characterised by the shape or form of the carrier: with cards or other card-like flat carriers, e.g.…
G11B 7/0045
Recording, reproducing or erasing methods; Read, write or erase circuits therefor: recording
G11B 7/14
Heads, e.g. forming of the optical beam spot or modulation of the optical beam: specially adapted to record on, or to reproduce from, more than…