U.S. Philips Corporation

Yvonne A Boersma

Cornelis M Van Uijen

James H Coombs

The disclosed information reading system comprises a record carrier (1) having at least two parallel tracks (2a, 2b) whose mutual distance is so small that the radiation beam (10) is modulated by the information patterns of the two tracks (2a, 2b) when the tracks are scanned by a focused radiation beam (10) along a line (18) indicating the center between the tracks (2a, 2b). The tracks comprise elementary areas, with the positions of the boundaries (80) of the elementary areas of the two tracks, viewed in the track direction, corresponding to each other. The information patterns in the tracks comprise elementary areas occupied by a mark and unoccupied elementary areas. The occupied elementary areas have a different influence on the radiation than the unoccupied elementary areas. When the two tracks (2a, 2b) are scanned, the center (17) of the scanning spot (14) is directed onto a line (18) which is located centrally between the tracks (2a, 2b). A radiation beam modulated by the scanned information pattern is projected onto a detection system (12). The information (I1, I2, I) which has been read is at least partly derived on the basis of one or more detection signals (Vt, Vppr, Vppt, Vppd) which are supplied by the detection system (12) at the instants when the radiation beam passes the boundaries (80) of the elementary areas.

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Eindhoven, Netherlands

Yvonne A Boersma