Patent GB-786036-A (GB)
Title: Improvements in storage means for digital data signals
IPC: H01J31/62
Filed: 1950-06-23
Abstract: 786,036. Digital-data-storage apparatus. DIRKS, G. June 23, 1950 [Oct. 1, 1948], No. 37217/54. Divided out of 786,021. Class 106 (1). [Also in Group XL (c)] A cathode-ray tube data store comprises means for scanning the beam in succession over each of a plurality of digit-storage areas on the screen, and means operating in synchronism with the scanning means and adapted to generate a signal for varying the intensity of the beam at a time representative of the value of the digit to be stored. As described, two double-beam C.R.T.'s are employed, one tube 56, Fig. 3, being used as a control tube for the storage tube 43, Fig. 1. Input and output means comprise multi-track magnetic tapes, but a magnetic drum or disc, or opticallysensed surfaces, may be substituted. Synchronizing signals picked up from one track of a first magnetic tape by a head 158, Fig. 7b, are amplified and applied to a phase shifting network 159a to give waveforms via terminals 57, 58, which, applied to the X and Y plates respectively controlling the C.R. beam 75, Fig. 3, cause a circular scan over secondary emission areas 109, 110, 111 ... 170 of the screen, Fig. 4, in synchronism with the sensing of the tape. At the beginning of the first quadrant of the circular scan the impingement of the beam on a target element 110 causes a signal at a terminal q, Fig. 7a, which fires a gas tube 94 and raises the screen potential of a pentode 83 to start a constant-current charging of a capacitor 89a. Arrival of the beam on an element 115, Fig. 4, causes a signal at terminal n, Fig. 7a, which, after amplification, fires a gas tube 89 and discharges the capacitor 89a. A similar sequence occurs during each 90 degrees movement of the beam 75 and the sawtoothed waveform available at the anode of valve 83 is applied to the X- plates 44 and 46, Fig. 1, controlling a " sensing " beam 99 and " recording beam 135 respectively. The " Y " plates 47 of beam 135 and 60 of beam 76, Fig. 3, are subjected to a stepped waveform derived from a self-extinguishing gas tube 93, Fig. 7a, which is fired each time the beam 75, Fig. 3, passes over the element 109 (sensing-switch 126<SP>3</SP>, Fig. 7a, in position shown) or element 118. (recording-switch 126<SP>3</SP> in upper position). During each brief period of conduction of tube 93, a constant-current pentode 81 steps up the charge on a capacitor 85 across which the stepped Y-scan waveform is developed. The beam 76, Fig. 3, is thus moved step-by-step over a column of targets 125<SP>1</SP> to 125101 in one hundred rotations of the beam 75, and when target 125<SP>101</SP> is reached the signal developed is applied to terminal e, Fig. 7a, firing a gas tube 88, discharging the capacitor 85, and thus restoring the Y-scan to its initial condition. Instead of a single column of one hundred steps, four-column and other arrangements are mentioned, controlled by a further group of targets (Fig. 4b, not shown). Operation. The value of a digit signal may be represented by its position on the magnetic track relative to a datum, as described in Specification 786,034. The arrival of the circular scanning beam 75 at target element 116, Fig. 4, may be used as a datum, the resulting signal at terminal f raising the control grid voltage of an amplifier 78 whose screen grid has just been raised by the firing of a gas tube 90 by a signal from target element 115. The amplified signal fires a gas tube 91 whereby current starts to flow through a constant-current pentode 79 to charge a capacitor 84 until the digit signal, picked up by a head 69 and amplified by a valve 80, fires a gas tube 92 which increases the current in the cathode load of the pentode 79 and cuts off the charging current. The voltage across capacitor 84 now represents the sensed digit and determines the vertical deflection of the beam 99. As the beam 99 is scanned horizontally on a line selected by the sensed digit in synchronism with the horizontal movement of the beam 135 which is to record the digit on the screen, it first passes a vertical datum element 22, Fig. 2, which causes a signal at the grid of a pentode 139, Fig. 7a, which, after amplification, operates through a transformer 141 to brighten the recording beam 135 and so record a corresponding datum mark in the recording area 50. Similarly, the arrival of the beam 99 at an element 19n in the area 53 causes a corresponding recording in the area 50 which represents the digit sensed in the magnetic tape. As the recording beam 135 moves to successive horizontal lines under control of the step-by-step charging of the capacitor 88, successive digits from the magnetic tape are recorded on the C.R.T. screen. The reading out and magnetic recording on a second tape of digits thus represented on the screen of the C.R.T. 43 is controlled from the first tape, the synchronizing signals being recorded on the second tape at the same time. The signals detected by a pick-up plate as the beam is scanned across each digit area, are applied to the grid of an amplifier 156, Fig. 7b, which drives a recording head 160 for the second tape through a transformer which also has a winding for intensifying the C.R.T. beam. Apart from the C.R.T. control voltages described above, further D.C. potentials controlled by gas tubes 94a, 94b, 94c and 94d, enable the switching of beams 99 and 1-35 to scan desired areas of the screen 49. Further details of these operations are described in Specification 786,051. Specification 786,033 also is referred to.