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;
• 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 equal to an integer times a pitch of said track guides in said image formed on said photo detector, wherein said integer is greater than or equal to two, and
• a mask provided on said photo sensitive element formed with a window defining said detection area.

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 and said optical card, said photo detector further comprising a plurality of recorded information reproducing photo sensitive elements, said plurality of recorded information reproducing photo sensitive elements being positioned at the intermediate position of said first and second pairs of photo sensitive elements for focusing control;
• first means for adding light detection signals output from said front photo sensitive elements;
• second means for adding light detection signals output from said rear photo sensitive elements;
• and
• third means for calculating a difference between outputs of said first and second means to produce a focusing error signal.

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 equal to an integer times a pitch of said track guides in said image formed on said photo detector, wherein said integer is greater than or equal to two, and
• wherein said photo sensitive element is divided into two parts by a division line that extends in a direction perpendicular to said plurality of track guides.

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;
• a mask provided on said photo sensitive element;
• 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 smaller than a minimum distance interval between said pits in said image formed on said photo detector, and said mask provided on said photo sensitive element forms a window defining said detection area.