GB924993A - Improvements of and relating to photo-electric scanners for punched tapes - Google Patents

Abstract

924,993. Sensing punched-tapes. O. VIERLING. March 15, 1960 [March 28, 1959], No. 9064/60. Class 106 (1). Punched tape 4, Fig. 1, is sensed photoelectrically in motion and column-by-column by a rotating drum 7 having a slot 13 for each column position which co-operates with a stationary perforated mask 5 to present each position of a column in turn to the photo-cell 3. The drum makes a revolution to sense each column of the tape and the line of holes 10a, 10b in the mask 5 may be inclined to compensate for the movement of the tape. Light from lamp 1 passes through lenses 2, 2<SP>1</SP>, through the holes in the tape column being sensed, through holes 10a, 10b and lens 22<SP>11</SP>, through one of the slots 13, a slotted plate 6, and a final lens 2<SP>111</SP> to photo-cell 3. Instead of inclining the line of holes 10a, 10b the lens 2<SP>11</SP> may be set at an angle to achieve the same result. The slots 13, shown in Fig. 2, are of parallelogram form the end of one slot and the beginning of the next being on the same inclined line. This inclination is the same as the inclination of holes 10a, 10b compensating for the movement of the tape during a rotation of the drum. There are seven slots, the first receives light passing beneath the tape so as to produce a start pulse at the beginning of a column read out. The next six slots allow light from the six column positions of the tape to pass in turn to the photo-cell. In practice, the slots are spaced to exclude the sprocket holes. After the uppermost position has been sensed there is a blank portion of the drum giving a space before the sensing of the next column. Instead of providing a start pulse slot, the drum may be completely interrupted between column-sensing positions. In another form, Fig. 4, the slots 13 are all in the same angular position of the drum and there are six photo-cells 3 so that the positions of a column are read simultaneously when the coil 28 produces a timing pulse from the passage of magnet 29. The lamp may be associated with means which gives a warning when the filament breaks. The tape is fed through the machine by a spool consisting of a number of vertical rods arranged in a circle, the end of the tape passing between the rods and gripped thereby as the spool rotates.