Patent GB-751923-A (GB)
Title: Method and apparatus for automatically reading data representative markings applied to statistical record carriers
Inventor: BALDE ULYSSE
Filed: 1954-08-19
Abstract: 751,923. Statistical apparatus. MITHRA AKT.-GES. Aug. 19, 1954, No. 24174/54. Class 106 (1). Record cards are marked in predetermined data representing areas with electrically conducting material and are subsequently exposed to a high-frequency electromagnetic field so that the temperature of the markings is raised above the ambient temperature, the marks are then detected with heat radiation detectors which bias electric circuits for evaluating the results. The cards are then fed to a marking device which provides markings of a different nature, e.g. punching or magnetic marks. The cards are stacked in a magazine 20, Fig. 1, from which they are removed and transported by pairs of rolls in known manner. The cards pass over a plate 23 provided with openings through which dogs 24, 25, project and retain the cards in two definite positions when the dogs are projecting through the openings. Intermediate the dogs 24, 25 is disposed a slider 27 of insulating material. The slider is substantially the size of the record card and is provided on its short side with guide slots, and is arranged to occupy one of two definite positions. The slider has openings 29 formed therein and in one position of the slider the openings 29 are above the markings on the card to be read and in the other position the slider 27 covers these card points. The slider 27 thus serves as an orifice plate or diaphragm. A metallic rail 30 runs across the card conveyer and has a continuous groove 30a. A carriage 46 is movably guided on the rail 30 and associated beam and comprises a rotatably mounted pin 47 of which a portion 47a is engageable in the groove 30a and which carries a knob 48 on top. By turning knob 48 the carriage 46 may be moved on rail 30. An insulating block 52 is provided with a plurality of linear conduits 53 running at right angles to the plate 23. The block 52 also comprises a number of heatradiation detectors 54 corresponding to the number of conduits 53. The detectors 54 comprise an evacuated glass vessel in which is housed an electrical temperature-responsive resistor 55 of the thermistor type. These comprise a mixture of various metallic oxides and have a high negative temperature coefficient. Each resistor 55 is connected to terminals 57 on plate 58. An inductor 62 is supported on holders 61 above plate 23 for heating the marks and is in the form of a hollow tube to allow a coolant to pass through. The H.F. fields set up by the inductor cause eddy currents to be set up in the electrically conducting marks on the cards sufficient to cause an appreciable temperature rise to take place in the marks, for example 30 C. above the ambient temperature of the card material which is not itself made appreciably hotter. The frequency used is of the order of one megacycle. After a predetermined period sufficient for the desired temperature rise the dogs 24 are withdrawn and the card is fed under the slider 27 for detection of the markings. When the card is in position the slider 27 is moved to expose the marks to the detectors, thereby increasing their resistance. The apparatus shown in Figs. 1 and 2 also comprises a conveyer and perforating device consisting of a plurality of punches 70 disposed in rows and actuated by pawls 77 under the control of electromagnets 82 which are responsive to the readings of the heat-sensitive elements. In this manner the original markings which may be applied manually to the cards are converted into perforations suitable for use with known punched card marking. The system may be adapted for use with tapes in place of the cards, and the additional markings may consist of magnetic markings instead of the punching operation.