Patent GB-675032-A (GB)
Title: Improvements in electronic impulse counters and accumulators
IPC: G06F7/74
Filed: 1950-01-02
Abstract: 675,032. Digital electric calculating-apparatus. NATIONAL CASH REGISTER CO. Jan. 2, 1950 [Jan. 15, 1949], No. 53/50. Class 106 (i). An electric-impulse counting device includes a plurality of digit-representing electron tubes connected in series so as to conduct one after another in response to input pulses applied in common to all the tubes, the tubes being arranged in groups of adjacent tubes in the series, the first tube in each group being a controlling tube to which anode potential is continuously applied and which supplies anode potential to the remaining tubes of the group only when it is itself conducting, and the controlling tubes being so interconnected that when any controlling tube is rendered conducting the previously-conducting controlling tube is rendered non - conducting. The arrangement enables a high rate of pulse counting to be achieved even with a majority of cold-cathode tubes since the de-ionization conditions are applied to the tubes for the duration of five pulses. Accumulator. Each denomination comprises a ring of ten gas-filled triodes divided into two groups corresponding with the digits 0-4 and 5-9, respectively. The " 0 " and " 5 " tubes have indirectly heated cathodes and the other tubes have cold cathodes. Positive impulses to be counted are applied, via terminals 48, 49 and a line 50 in the case of the units denomination, to the control electrodes of the ten tubes simultaneously. When the accumulator registers "0," the " 0 " tube only is conducting. The cathode of this tube is connected via a low resistance 35 to +75 v. and via high resistances 41, 39 to - 150 v. The anode is connected via low resistances 23, 25 to +180 v. Thus, when the tube is conducting, its cathode is at a high potential and, since the anodes of the "1" to " 4 " tubes are connected thereto, they are at a sufficiently high potential for conduction to occur when their control electrodes are raised to the striking potential. The grid of the "1" tube is also connected to the cathode of the " 0 " tube through a resistance 65 so that, when the "0" tube is conducting, the "1" tube is primed. The first pulse to be applied to the line 50 will thus fire the "1" tube. Its cathode is connected to earth via a resistance 68 and to the control electrode of the "2" tube and the consequent rise in its potential primes the "2" tube. Similarly the following pulses will fire the " 2," " 3 " and " 4 " tubes. The " 4 " tube, when conducting, primes the " 5 " tube and, on receipt of the fifth pulse, this tube will fire. The anodes of the " 0 " and " 5 " tubes are connected and the sudden drop in their potential when the " 5 " tube is fired extinguishes the " 0 " tube since a condenser 53 in its cathode circuit temporarily maintains its cathode at a high potential while a similar condenser 54 in the cathode circuit of the " 5 " tube temporarily maintains its cathode potential at a low value. When the " 0 " tube is extinguished, the "1" to " 4 " tubes are also extinguished since their common anode potential is reduced. The ensuing pulses fire the " 6 " to " 9 " tubes in turn. The " 9 " tube, when conducting, primes the " 0 " tube so that the tenth pulse fires the " 0 " tube and, by virtue of the condensers 53, 54, extinguishes the " 5 " to " 9 " tubes. Transfer arrangements. When the " 0 " tube fires, the rise in its cathode potential is transmitted as an impulse through a diode 130 to the input pulse line 134 of the next higher denomination. Zeroizing. Depression of a key 140 cuts off the anode supply to the " 0 ' and " 5 " tubes and thus extinguishes whichever is conducting and, in consequence, any of the " 1" to "4" or " 6 " to " 9 " tubes which are conducting. A solenoid 142 is also energized and closes contacts 146 in each denomination to connect the control electrode of the " 0 " tube to the +75 v. supply. When the key is released, the contacts 146 open sufficiently slowly to enable the " 0 " tube to be fired as its anode supply is restored. Indicating. Associated with each tube of a ring is a pair of contacts, e.g. 77, 78, so connected to the cathode circuit of the tube that, when the tube conducts, their potential is raised. The contacts are scanned by a stepping rotary switch arm carrying brushes 85, 86 which at any moment respectively engage the contact 77 of one tube and the contact 78 of the next higher tube. The brushes 85, 86 are respectively connected to the grids of a double triode 92 so that, when they engage the contacts of the highest conducting tube of the ring and the lowest non-conducting tube, the potential of the anode 94 of the tube 92 will decrease due to the corresponding half of the tube becoming conducting. A current will thus flow between the two anodes of the tube 92 via a rectifier 100 and a solenoid 101. The solenoid opens contacts 102 in the circuit of the stepping drive solenoid 104 so that the switch arm ceases to rotate. A dial carried by the switch arm shaft indicates the value registered. Contacts 107 in the circuit of the solenoid 104 are closed by operation of a solenoid 144 due to the closing of contacts 143 by the solenoid 142 when the zeroizing key 140 is depressed. The solenoid 144 also closes contacts 145 which maintain its circuit when the key 140 is released. The indicator may be rendered inoperative by temporarily opening a switch 150 to break the holding circuit of the solenoid 144. Specification 675,060 is referred to.