GB737839A - Apparatus for reading digital information from a punched tape, card or the like - Google Patents

Abstract

737,839. Digital electric calculating-apparatus; statistical apparatus. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Nov. 26, 1953 [Dec. 2, 1952], No. 31243/53. Divided out of 737,801. Class 106 (1). [Also in Group XL (b)] Apparatus for reading digital information from a punched or similarly marked member, comprises an optical system, for passing a light beam through holes in the punched member one at a time to a light-sensitive cell, and means for continuously moving the light beam so that the holes representing a word are read sequentially, the rate of movement being such that each word of information is repeatedly read from the member. The apparatus may be used for introducing data into an electronic computor. A beam of light from a source 10 is repeatedly scanned along a length of tape 1 by a rotating polygonal mirror drum 23, and signals are picked up by a photo-cell 9 which correspond to the information punched in the tape. The beginning of each scan is detected by a photo-cell 24, a signal from which is used, in conjunction with a signal from the computer to gate the succeeding series of data signals into the computer. A third photo-cell 20 detects punchings separating each section of information on the tape, and can be used to control the operation of the feeding winch 4 or, if the tape is arranged to move continuously, to determine the operative periods of scanning, i.e. when the information section on the tape is correctly positioned. In another embodiment (Fig. 3, not shown) the light source is located within a transparent cylinder over which the data tape is passed. A concentric slotted drum rotating within the cylinder in a direction opposite to the movement of the tape provides for the scanning action and the resulting signals are picked up by three photo-cells as before. In yet another embodiment light is concentrated by a lens system 11, Fig. 4, on the punched strip 1, and an image of the punched data is focused by a lens 36 on a screen 38 having a slit 40 behind which is a photo-cell 9. The image is swept across the slit by a mirror drum 23. In a modification, by converging the rays through the punched strip a smaller mirror drum may be used. In all cases the tape may contain several columns of perforations and the beam of light may extend across the tape for simultaneous reading of the columns by a row of photo-cells. Moreover, the digits from the various lines may be read in time multiplex by (1) punching the tape so that corresponding holes across it are on a line not perpendicular to its length, or (2) using separate optical systems relatively displaced in the direction of scanning, or (3) using a staggered row of photo-cells. A combination of holes in a line may be used to define a single digit of a number. In all cases perforated cards may be used instead of punched tape. Specification 717,114 is referred to.