Patent GB-844306-A (GB)
Title: Improvements in record card reading devices
IPC: G06K7/10
Filed: 1957-02-18
Abstract: 844,306. Photo-electric record reading. INTERNATIONAL BUSINESS MACHINES CORPORATION. Feb. 18, 1957 [Feb. 21, 1956], No. 5393/57. Class 40(3). [Also in Group XIX]. Sensing record cards: In a record card sensing device the cards 10 are fed in the direction of the columns past a transfer station, an image of the card is transferred at this station on to a phosphorescent surface 12 moving at right angles to the card path, and the image is sensed by a column of photo-cells PM in column by column order. The phosphorescent surface may be carried on a drum or band, the delay time of the light images formed thereon being such that they will be only detectable by the photo-cells. An erasing device can be used to cancel the phosphorescent images after sensing but this is not normally necessary. In the form shown in Fig. 1 the phosphorescent surface is in substantially the same plane as the card so that no lenses are necessary to project a sharp image. The lamp 14 is designed to emit a short period flash of light having a very small source area. To enable the signals induced in the photo-cells to be interpreted a timing track is projected on to the phosphorescent surface from a fixed mask 16 having 80 apertures, one for each column. This track is read by a photo-cell P-T and the resulting signals are used to operate an 80-stage counter. Each stage of the counter is used to gate the photo-cell signals from the corresponding card column so as to give an output for each column on one or more of twelve lines corresponding to the twelve row positions. Since the parts of the image remote from the column of photocells take longer to arrive in reading position, they will have decayed in intensity to a greater extent than the image parts nearer the photocells. To make the photo-cell response substantially constant in spite of this a mask may be provided registering with the card, and having holes coinciding with the perforation positions of the card. These holes are graded from left to right along the mask so that the amount of light passing through the card on the side near the photo-cells is reduced. The timing track may be formed on this mask. In operation the card 18 is fed into register with the mask 26 Fig. 2, the light from the flash lamp 22 being directed by a reflector 24 on to the card and mask. The light which passes through card perforations is directed by a mirror 28 and lens 30 on to the phosphorescent surface of a drum 20. Light from the transferred image is projected by lens 34 and mirror 36 on to the line of photo-cells PM. The cards are fed one by one from a stack by a card picker in the usual way and forwarded by slipping rollers to the transfer position. The card is held stationary in this position by a card gate while the lamp is flashed and is then released for movement to the stacker magazine. The card may be imaged on to the phosphorescent surface more than once if desired. It may alternatively be imaged in motion, the operation of the lamp being synchronized with the card feeding mechanism. Instead of having the photo-cells PM crowded into a line as shown in Fig. 1, light guides in the form of transparent rods may co-operate with the phosphorescent surface and conduct the light to a group of photo-cells mounted in a more spaced arrangement. Alternatively the phosphorescent image may be projected by a mirror and lens system on to a line of spaced photo-cells. Specifications 686,986 and 819,466 are referred to.