Patent GB-780659-A (GB)
Title: Ferroelectric counter
IPC: H03K21/00
Filed: 1954-09-28
Abstract: 780,659. Electronic counting apparatus; pattern-movement stepping registers. INTERNATIONAL BUSINESS MACHINES CORPORATION. Sept. 28, 1954 [Oct. 1, 1953], No. 27961/54. Class 106 (1). [Also in Group XXXIX] A counter circuit comprises a series of ferroelectric storage elements each capable of assuming two alternate stable states of polarization, means for initially causing one of the elements to assume one of the table states, selectively activated switch means coupling adjacent elements in the series, and advancing means comprising a pair of conductors connected respectively to alternate storage elements and alternately subjected to the pulses to be counted. The switching means comprise gas-filled tubes SO ... S9 of the type described in Specification 752,566, wherein conduction occurs between internal electrodes a and b when an RF signal is applied to an external electrode d. All the ferroelectric elements FO ... F9 are initially in a state of polarization represented by the point " b " in Fig. 1. A negative setting pulse applied at a terminal 3 changes the state of polarization of the ferroelectric element FO from b to c and, upon termination of the pulse, leaves it in state a. The pulses to be counted are applied to a trigger unit 23 which delivers corresponding output pulses alternately to blocking oscillators 21 and 22 giving rise to alternate negative pulses on lines A and B respectively. Line A is connected to even-numbered elements FO, F2, F4, F6, F8, while line B is connected to odd-numbered elements F1 F3, F5, F7, F9. Similarly, switching tubes S1, S3, S5, S7, S9 are connected to points in a coaxial line L at even multiples of quarter wavelength distances from a source of radio frequency energy 5, while tubes SO, S2, 84, S6, S8 are connected to points at odd multiples of quarter wavelengths from the source and the termination. When tubes T1 and T2 are non-conductive the line L is terminated by an open circuit and a standing wave of energy developed by the source 5 has maximum voltage points at the connections to oddnumbered tubes S1, S3 ... , &c. A positive counting pulse on the line 24 renders the tube T1 conductive and short-circuits the termination of line L so that maximum voltage points are now at the connections to even-numbered tubes SO, S2 ... , &c. As a negative pulse from the blocking oscillator 21 drives the element FO from state a to d it provides a low resistance path for the negative pulse to be applied through the conductive switch SO to the next element F1 driving this from point b to c. When the counting pulse terminates the element F0 returns to its " clear " state b while the element F1 returns from c to a. The second counting pulse is delivered to line B alone so that the switch tubes S1, S3 ... , &c. are now conductive and the " marked " state of element F 1 is transferred through tube S to the element F2. This process continues until tube F9 becomes marked and the tenth pulse transfers this state back to the element FO and also to a carry pulse storage element Fc. A negative carry testing pulse applied to terminal 30 at an appropriate time, serves to transfer the carry to the next higher order. If no " carry " has been registered in the element Fc, the latter presents a relatively high impedance to the testing pulse and thus prevents operation of the AND gate 31. - Resetting of the counter is performed by moving a switch 15 to apply negative potential to both lines A and B simultaneously. Movement of the switch also removes negative bias from the grid of a valve T2 allowing it to become conductive and form, with the cathode resistor RL a characteristic impedance terminating the coaxial line L. Thus all the switches SO ... S9 are rendered conductive and all ferroelectric elements FO ... F9 are cleared to state b. The apparatus could also be used as a shifting register, the terminal 3 then forming the data entry point.