READING METHOD OF OPTICAL MEMORY MEDIUM

摘要

PURPOSE:To attain the reading of a signal of high density without using the laster light for detection by irradiating the reflected or transmitted light to sensors arranged linearly as well as to a light shielding mask after branching said light into two streaks of light via a semitransparent mirror and then detecting the maximum or minimum light quantity via a photodetector. CONSTITUTION:Tracks 2 are arrayed in the same pitch to form track trains 2' on a card 1. These trains 2' are arrayed in the traveling direction of the card 1. The light delivered from a light emitting diode 3 is condensed by a lens 4 and branched into two streaks of light by a semitransparent mirror 6. One of these two streaks of light is put into sensors 7 arrayed linearly; while the other streak is branched toward the side way and irradiated to a light shielding mask 8. The transparent streaks 9 have the same pattern as a geometric distribution of the tracks 2 and transmit the light. The peripheral area 10 of the streaks 9 cuts off the light. Therefore the quantity Q of the light received by a photodetector 11 has large and small changes toward a time base (t) as the card 1 advances toward an arrow (x). A signal reading circuit 18 reads assuredly digital signals by the signal delivered from a position detecting circuit 12.