GB705495A - Improvements in or relating to electronic information-storing devices - Google Patents

Abstract

705,495. Digital electric calculating-apparatus. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Nov. 1, 1950 [Nov, 22, 1949], No. 29945/49. Class 106 (1). [Also in Group XL(c)] In a cathode-ray tube storage system of the kind described in Specification 705,474 in which a positive charge is generated at a selected region of the insulated screen by bombardment with the C.R. beam, the beam is deflected at the region in order to generate a positive charge along a strip of the screen and is subsequently directed to bombard a spot on or near to the strip in order to reduce the positive charge on the strip, the bombardment being prevented or permitted in dependence upon the nature of the information to be stored. Fig. 4 shows a C.R. storage system in which pulses from a master pulse generator 20 are divided down in unit 21 to provide synchronizing signals from the X and Y scanning circuits and also control the dot and dash waveform generators 24, 26, the former of which generates a waveform as shown in Fig. 3(a). The X deflection is periodically paused by the use of a waveform as shown in Fig. 3(f). The waveform from dash generator 26 is combined with a pulse from the meditation pulse generator 32 to produce a dash and meditation waveform as shown in Fig. 3(b). The pulses from units 24, 26, 32 and from a strobe pulse generator 28 are applied to control a gate circuit 25 as described in Specification 705,482 so that normally the dot waveform is applied to the control grid 13 of the C.R. storage tube 10 to represent storage of the quantity "0." When it is required to record the quantity "1" a suitable write voltage applied at 29 changes the control grid waveform to that of Fig. 3(b). Regeneration of the stored information is effected by the voltage at the pick-up plate 19 which is amplified in unit 27, strobed by pulses from generator 28 to produce a positive or negative pulse in dependence upon the stored information at that instant, the polarity of the pulse then determining which of the " dot " or " dash " waveforms shall be applied to control grid 13. The stored information may be read-off at terminal 30. The first bombardment of a strip of the storage screen 11, i.e. the recording of a "dot" unit of information produces a charge distribution as shown at 3 in Fig. 2; subsequent bombardment of the central region of the strip to record a "dash" unit causes the outer regions to be "filled-in" by secondary emission electrons so that a charge distribution as shown at 6 in Fig. 2 is obtained. The Y scanning waveform has superimposed upon it from unit 33 a deflecting voltage as shown in Fig. 3(c) which is obtained for example by combination of waveforms as shown in Fig. 3(d) and (e), this deflects the beam during the period t0-t1 of Fig. 3 when it is switched on. When the dash waveform is applied at the control grid of the C.R. storage tube the beam is switched on during the period t0-t1 and whilst the beam is paused in the X direction it is deflected by the voltage of Fig. 3(c) to produce a charge distribution as shown in Fig. 2 at 3. When the dash waveform is to be recorded the dot charge pattern is modified by switching on the beam again during period t2-t3 whilst the beam is held stationary in the X direction thus " filling-in " part of the strip so that the charge pattern shown at 6 in Fig. 2 is produced. The slope of the deflecting wave of Fig. 3(c) during the period t0-t1 is such that the beam velocity is sufficiently great to prevent the positive charge pattern from being filled-in " by secondary emission behind the path of the beam. The strips of charge may be generated at an angle to the X axis other than in the direction of the Y axis. Specifications 582,758, 587,364, [both in Group XL], 657,591, 682,156 and 705,483 also are referred to.