GB814753A - Improvements in or relating to electronic recording apparatus - Google Patents

Abstract

814,753. Recording-apparatus. DOBBIE McINNES Ltd. May 10, 1957 [May 14, 1956] No. 14864/56. Class 106 (4). [Also in Group XX] Electronic recording - apparatus, wherein voltage responsive motors 26, 26a drive a gantry 12 along an X-axis and a marking- head carrier 13 along the gantry 12 parallel to a Y-axis, comprises electronic means 29. to control the operating voltage to each motor 26, 26a in response to registered input valves and a plurality of selectively actuable markers in the head 14 adapted to mark different symbols, with voltage shift means 24 for modifying the operating voltage to each motor 26, 26a to compensate for the co-ordinate location of the selected marker relative to a predetermined datum on the head 14. In order to plot a curve on the fixed chart 11, the X and Y co-ordinates of each point are fed successively to a digital-analogue converter 19, alternatively from a keyboard 20 or tape reader 21, and the corresponding stored voltages are fed to separate summing networks 25, 25a, to which are also fed, by a shift unit 24, voltages corresponding to the " position error " of the marker selected, either manually at 23 or automatically at 22, according to whether the co-ordinates were entered by the keyboard 20 or tape reader 21. X and Y feed-back voltages from potentiometers 28, 28a are also fed to the networks 25, 25a, and the resultant voltages are passed through servo-amplifiers 27, 27a to the motors 26, 26a. When a state of balance is reached and after a time lag a control circuit 29 transmits a pulse to the coil 17, Fig. 4, of the electromagnet, of which the selected marker 15 forms the core, and the marker 15 is actuated against a return spring, to press an ink ribbon against the chart 11. The shift unit 24, for a marker head carrying an array of three rows and columns of markers with quarter inch spacing, comprises two similar voltage dividers comprising similar resistances 30, 31; 30a, 31a, each pair being in series with a variable resistance 36, 36a, the second series also including a larger resistance 37. If a corner marker is chosen as the datum, shifts of zero, a quarter or a half an inch in the X and Y directions will be required according to which marker is selected either manually through banks 44 to 46 of a selector switch or automatically over lines 47 to 50, the selection causing appropriate combinations of the solenoids 34b, 35b, 34c, 35c to be energized to operate switches 34, 35, 34a, 35a for appropriately tapping the voltage dividers, which, when suitably adjusted, feed into the summing networks 25, 25a voltages to cause the required shifts. In order to locate the datum marker at the origin of the chart a sighting block with cross-lines offset one inch in the X-direction is provided on the head 14 and during sighting the head is shifted this distance by adding the resistance 37 to the network 25 by operating a set-up solenoid 38b. It is stated that the apparatus may be used for analogue recording by providing a time switch or interrupter circuit to allow the selected marker to operate continuously.