JPS57169875A - Card reader - Google Patents

Abstract

PURPOSE:To prevent the erroneous operation of reading due to shift in position by providing a means for counting data width by the number of clock pulses proportional to a card feeding speed, then judging[presence]only when the count value is greater than a prescribed value. CONSTITUTION:The set value of a binary counter BC is set about one third as great as the number of clock pulses generated between the front and rear edges of a punch hole. Since a signal S3 generated by AND of a detection signal S1 for the front edge of a punch hole P1 and data sample signal S2 has a level H, the BC starts counting the clock pulses. When detections progresses up to a point T which is at one third as wide as the width of the punch hole on a column C1, a terminal CA is held at a level L and the Q terminal of a flip-flop F is held at the level H, so that a data reading circuit DR judges the[presence]of data. When the detection progresses up to the rear edge of the punch hole, the terminal CA returns to the level H. At the rear edge of the column C1, a differentiating circuit DF triggers a terminal R and the terminal Q returns to the level L.