Self correcting recording/reproducing apparatus for an optical card

An optical card recording/reproducing apparatus for recording/reproducing information onto/from an optical card formed with a plurality of track guides which are arranged in parallel with each other with a predetermined pitch, comprising: a light source for emitting light; a photo detector including a photo sensitive element for focusing control; and an optical system for converging said light emitted from said light source onto said optical card and for forming an image of reflected light onto said photo detector, the image including an image of said track guides of said optical card; wherein said photo sensitive element has a detection area, and a width of said detection area in the direction perpendicular to said track guides is set to a length integer times a pitch of said track guides in said image formed on said photo detector.

An optical card recording/reproducing apparatus for recording/reproducing information onto/from an optical card having a plurality of tracks provided thereon, comprising: a light source for emitting light; a photo detector for focusing control comprising a first pair of front and rear photo sensitive elements and a second pair of front and rear photo sensitive elements, said two pairs of photo sensitive elements being arranged apart from each other at a predetermined distance in a direction perpendicular to the direction of said tracks on said optical card and said front and rear photo sensitive elements of each said pair being arranged adjacent to each other along the direction of said tracks on said optical card; and an optical system for converging light emitted from said light source onto said optical card and for forming an image of light reflected from said optical card onto said photo detector.

An optical card recording/reproducing apparatus for recording/reproducing information onto/from an optical card formed with tracks thereon and with a series of pits representing the information arranged along and within each of said tracks, comprising: a light source for emitting light; a photo detector including a photo sensitive element for reproducing the information; and an optical system for converting the light emitted from said light source onto said optical card and for forming an image of the reflected light onto said photo detector, the image including an image of the pits of the optical card; wherein said photo sensitive element has a detection area, and a width of said detection area in the direction along the tracks is equal to or smaller than a minimum distance interval between said pits in said image formed on said photo detector.

A method for reproducing/recording information onto/from an optical card formed with a plurality of track guides which are arranged in parallel with each other with a predetermined pitch, comprising the steps of: emitting light from a light source onto said optical card; converging said light emitted from said light source onto said optical card and said light reflected from said optical card; forming an image of said reflected light onto a photo detector having a detection area, said image including an image of said track guides of said optical card; and setting a width of said detection area of said photo detector which is in the direction perpendicular to said track guides to a length integer times a pitch of said track guides in said image formed on said photo detector.

A method for focusing an optical card recording/reproducing apparatus for recording/reproducing information onto/from an optical card having a plurality of tracks providing thereon, comprising the steps of: emitting light from a light source; converging light emitted from said light source onto said optical card; forming an image of light reflected from said optical card onto a photo detector which comprises a first pair of front and rear photo sensitive elements and a second pair of front and rear photo sensitive elements, said two pairs of photo sensitive elements being arranged apart from each other at a predetermined distance in a direction perpendicular to a direction of tracks on said optical card and said front and rear photo sensitive elements of each said first and second pair being arranged adjacent to each other along a direction of said tracks on said optical card; first adding together light detection signals output from said front photo sensitive elements; second adding together light detection signals output from said rear photo sensitive elements; and calculating a difference between said outputs of said first and said second adding step's sum to produce a focusing error signal.