Patent GB-811065-A (GB)
Title: Electrical counting and scaling devices
Inventor: BANE WILLIAM THOMAS
IPC: H03M1/00
Filed: 1956-05-01
Abstract: 811,065. Electronic counting-apparatus. NATIONAL RESEARCH DEVELOPMENT CORPORATION. July 23, 1957 [May 1, 1956], No. 13438/56. Class 106 (1). A counter comprises means whereby the count of recurrent events may be scaled by a desired factor. The events may be the passing by marks on a moving member of a fiducial line, or voltage pulses or light signals. For measuring the displacement of a moving member past a fixed member, a moving member of length L, Fig. 1, is provided with five rows a, b, c, d, e of 1, 2, 4, 8, 16 marks respectively, each mark, except those of row e, being midway between two marks of the superior row, the marks being sensed as they pass the fiducial line xy, the sensing being by electric contacts when the marks are conducting areas of an insulating plate or vice versa, each row having a separate contact brush which may be made operative or inoperative at will. The rows may be staggered from the positions shown if the brushes are correspondingly staggered. To sense the direction of motion a further row of contacts (not shown) arranged so that a make or break is achieved between every possible make or break of the counting contacts is provided or alternatively a second set of contact brushes may be provided for each row. The marks may alternatively be transparent on an opaque plate, a narrow slit of light being projected from the fixed member to a photo-cell, and for selecting the rows required for operating the counter an optical mask such as a punched card may be used, or alternatively separate selectively operable light sources may be provided for the rows. Detection may also be by reflected light. The count may be made a non-linear function of the displacement by approximating the required function by a series of linear segments. Angular displacements may be measured by marks on the surface of a cylinder, or radially on a flat disc. In a second form of the invention, only a single row of equidistant markings is used and the scaling is effected by eliminating or interpolating pulses. This form may also be used for scaling pulses from sources other than a marked plate. In the embodiment shown in Fig. 2, pulses from a lead M pass to a counter comprising triggers T1-T6 through a circuit K which ensures that just one incoming pulse on the lead M is prevented from entering the counter after a pulse has been received on the line L. The required scaling factor is obtained by closing appropriate ones of the switches a, b, c, d, e, f. Thus if no switches are closed, 63 pulses will fill the counter, whereas if switches c, d, f are closed, 107 pulses will be required since each time a trigger goes on it adds one to the number of pulses required to fill the counter if its corresponding switch is closed. The counter may be zeroized by reset pulses applied to all the triggers. In the variation of Fig. 3 (not shown) return pulses from the counter stages are used to add additional pulses into the counter thereby decreasing the number of pulses required to fill the counter. A third form of the invention, Fig. 4, employs a multiplying factor for each pulse and a reversible counter. Pulses on the line " + " represent an increase and pulses on the line " - " represent a decrease in the count. A scaling value varying in steps of 1/64 between 1/64 and 1 may be obtained by a suitable derangement of the switches a to f. In a further modification, Fig. 5 (not shown), an arrangement is described to modify the scaling factor when certain counts have been attained. Specification 717,114 is referred to.