Patent GB-745403-A (GB)
Title: Automatic computing apparatus
IPC: G06J1/00
Filed: 1953-07-01
Abstract: 745,403. Electric analogue calculating systems. SCHLUMBERGER WELL SURVEYING CORPORATION. July 1, 1953 [July 1, 1952], No. 18245/53. Addition to 732,878, [Group XL (b)]. Class 37. [Also in Group XL (b)] In a computer of the kind described in the parent Specification for determining the value of a function f(x, y), the electronic timing and gating circuits, for establishing the interval of time over which the electric pulses corresponding to the intersection of the successive families of function curves with the light beam traversible in correspondence with the instantaneous value of one unknown variable-are admitted to the electronic pulse counter and indicator, are dispensed with by the use of an opaque belt 10 (Figs. 1, 2) rotatable over sprockets 11, 12 by a constant-speed motor 13 and divided longitudinally into plural frames 27 which are slotted to represent families of curves 20a to 20n of a predetermined function u=f(x,y) referred to a a transverse x axis and a longitudinal y axis. The curves in each family correspond to different values of the function, and may alternatively be recorded as reflecting lines or as opaque lines on a transparent belt. A small intense first light spot is deflected transversely of frames 27 of the belt by a mirror galvanometer 16 energized by a signal proportional to the variable x, and a second light spot is deflected transversely of a series of frames 44 of the belt disposed parallel to and in lateral registry with the corresponding frames 27, by a mirror galvanometer 21 energized by a signal proportional to the variable y. Frames 44 are recorded with triangular window portions (or alternatively opaque triangular portions on a transparent belt) and the light traversing each pair of frames 27, 44 falls on a linear photo-cell 17 transversely of the belt, whose output is received by a pulse amplifier 24, biased to pass signals produced by the first spot only for the duration of signals produced by the second spot, which supplies an electronic pulse counter 25 and output indicator 26. Fig. 4A shows against a time axis the output waveform of the photo-cell due to the interaction of the first spot and the successive families of curves on frames 27, which comprises trains of pulses 42 determined in number and timing by the variable x, and Fig. 4B shows pulses 41 due to the interaction of the second spot with the windows of frames 44, which commence at the passage of the x axis of each frame and terminate at an instant corresponding to the instantaneous value of the variable y. Pulse amplifier 24 energizes the counter 25 only during the persistence of the latter pulses to pass trains of pulses 43 (Fig. 4C) representing in number the instantaneous value of the function u=f(x, y) for the instantaneous values of x, y over the corresponding frame, as described in the parent Specification, and the functional value is accordingly registered by indicating device 26. The curves on frames 27, 44 may be recorded against non-linear or logarithmic axes, and separate photo-cells. The function u =#(x, y) may be determined experimentally, e.g. by electrically logging the geological formation traversed by a borehole.