# Патент USA US2404387

код для вставкиJuly 23, 1946. ‘ 1c. A. LOVE‘LL ET-AL ‘ 2,404,387 ELECTRICAL COMPUTING SYSTEM Filed May 1, 1941 .REI’fRS/IYG PoLAk/rr RL'PEATER 2 Sheets-Sheet 2 2,404,387 "112/ I UNITED sTATEs ’ OFFICE ‘s " 2,404,387 ‘ . , . - ' . , ; , -- v. é ' l I. w. 'EFLECTRICAL COMPUTING SYSTEM Clarence A. Lovell and David B. Parkinson, Maplewood, N. .L, and Bruce T. Weber, New . York, N. Y., assignors .to Bell Telephone Labo Y» v . g ratories, Incorporated, New York, N. Y., a cor poration of New York - Application May 1, 1941, Serial No. 391,439 , ~ "4 Claims. (c1. 235—61) _ r This invention relates to electrical computing > - 2 , . , the vacuum tubes, the impedance of the anode cathode circuits of the vacuum tubes is balanced against the resistance of the resistor 34, and both clutches are disengaged. As the patentee is pri systems, and particularly to systems including comparison circuits associated with servo-motors. The object of the invention is the solution of an equation, or a system of simultaneous equa . marily interested in measuring electrical power, tions, in which the data are represented by elec~ which is inherently a positive quantity, he has chosen the position of balance so that, in the A feature of the invention is a system in which absence of any signal voltage, the wiper of the electric elements and mechanical motions are potentiometer will be in one extreme position. If combined to form representations of mathemat 10 a voltage e be applied to the input circuit, a vari ical functions whose arguments are indicated by able fraction K of this voltage will be selected the mechanical motions. by the potentiometer and supplied to the ampli ‘,‘Another feature of the invention is a compari ?er. This voltage is balanced against the volt trical quantities. i ' ' 'son circuit, associated with a servo-motor, which continuously compares a plurality of input volt age E in the control circuit to produce a devia 15 tion voltage 6e, thus ' . ages and supplies a voltage equal to the deviation of the sum of the input voltages from zero to control the servo-motor in reducing the devia The shaft of the servo-motor is coupled by the tion to any desired small value. clutches to the brush of the potentiometer so that -,_An important form of the invention is a de 20 its motion under the control of ac tends to set v vice which, when supplied with electrical volt the wipers of the potentiometer to make 8e=0. ages proportional to two sides of a triangle, will set itself to indicate an angle of the triangle and to produce a voltage proportional to the other Inthis condition ' ' . ~ .Ke—E=0 (2) 25' The patented device thus can solve a linear equation, having the right-hand member equal Another form of the invention is a device which, when supplied with voltages proportional to zero, by varying one term, K, of the equation. side of the triangle. ‘ ' to the rectangular coordinates of a point, will set In using a device of this character in accord ance with the present invention where the input '30 voltages may be positive or negative, the biasing voltage preferably is adjusted so that the clutches ‘Other modi?cations, features and advantages are in the released position in the middle of the of the invention will be apparent from the fol lowing description, and the drawings, in which range, thus establishing a virtual zero value, and Fig. l is a partly diagrammatioal elevation of any deviation from this value will operate the ‘a system embodying the invention; * -, clutches to move the potentiometer wipers to re Figs. 2A and 2B show a potentiometer card duce this deviation to a small value, or zero. itself to indicate the polar coordinates of‘ the point. -' used in the system; -- ' ' " ' ‘ ‘ ' ' ~ Fig. 3 is a geometrical ?gure illustrating one ' application of the invention; . ' Fig. 4 diagrammatically and schematically 40 ‘ shows an embodiment of the invention for solv ing the equations involved in Fig. 3; and v“Fig. 5 schematically shows a summing re peater. ‘ From one point of view, the present invention may be considered as an extension and elabora tion of the system disclosed in U. S. Patent ' The nature of the extensions made in the ?eld of use of the patented device by the present in vention may be expressed in a generalized for mula. , f v In the present invention, a single servo-motor may be controlled by a deviation voltage having the form I; - _ ~ I 1| 6e=§fi<® +1) (3) where 6/ is any argument in a form which may be controlled by the shaft 01’ the servo-motor 2,003,913, June 4, 1935, E. C. Wente. While the disclosure of this patent has been selected for and b is any constant. The servo-motor will the purpose of illustration, the invention is not 50 thus simultaneously solve any number of equa limited to this speci?c device, but may be adapt tions all having the same argument. ed for use with many other forms of servo-mo »A clearer understanding of the nature and advantages of the ?rst extension in the ?eld of tors. - In .U. S. Patent : 2,003,913, . 1‘ 7 for ~ 4 some r Predeter use will be obtained from the following descrip ‘ininedvalue of biasing voltage on they grids of 1 tion, which isintencled only as an illustration of 2,404,387 ~' 3 the use of the invention and not as any limita tion thereon. conveniently be arranged so that the potentiom eter is grounded by the leads 61, 68, though such In Fig. 1, the motor I, differential gears 2, 3, 4, magnetic clutches 5, 6, and control circuit 1, for the purposes of discussion of the invention, may be generally similar to the corresponding parts in U. S. Patent 2,003,913. As the present device may be operated on slowly varying voltages, the a connection is not essential, and other connec tions may be used if desired. The control volt recti?ers may be omitted, and, if desired, a single vacuum tube 10 used. The control voltages are applied to the input circuit of the vacuum tube ‘Ill. The control electrode of .the vacuum tube 10 is biased by the source of voltage ‘H applied through resistor 12. The resistor 13 corresponds to the load resistor 34 disclosed in Patent 15 the potentiometer must be reversed. 2,003,913. Theclutch coils 5, 6, and associated unilateral devices 14, ‘I5, operate in a similar manner to the corresponding devices in United age is supplied directly to the leads 65, 65 of the potentiometer shown in Fig. 2B, but, owing to the inversion of sign in the function, the po larity of the voltage supplied to the lead 66 of The potentiometer 9 may have a uniform winding connected to leads l6, 11, or may have a winding with resistance per unit length vary ing in accordance with any desired function, or varying in accordance with a set of values em pirically determined. The leads ‘[8, 19 connect ed to the wipers may supply the selected volt ages to any desired circuit. In, Fig. 3, the rectangular coordinates, x, y, o States Patent 2,003,913. Any desired standard of a point T with respect to a point D have been voltage, which may be zero, is applied to the in 20 determined in the form of voltages proportional put of vacuum tube 10, and the bias voltage from to the coordinates. The problem is to determine the source ‘ll adjusted to make the anode-cathode the angles of azimuth a and elevation e, and to resistance of vacuum tube 10 equal to the resistor produce a voltage proportional to the slant dis 13. The clutch coils 5, 5 are thus connected to tance r from D to T. The line of zero azimuth substantially eqm'potential points and are not op 25 may be assumed along the :2: axis. This is the erated. If any other voltage be applied to the type of problem frequently encountered in the input of vacuum tube 79, this balance will be up control of anti-aircraft artillery, though the in set and the appropriate coil 5 or 6 will be ener vention is not limited to this speci?c use. gized. The shaft 8 is extended to carry the Designating the hypotenuse of the ivy triangle wipers of several potentiometers which are in 30 by h, the horizontal range, from simple trigo sulated from the shaft, and from each other, il nometry, we have ' lustrated by the potentiometers 9, l0. While only two potentiometers are shown, it is apparent that many more potentiometers may be operat ed by the one shaft. These potentiometers may 35 have one or more wipers as desired. '- Thus, > y Y _ I , , Some of the potentiometers may be directly concerned in con trolling the voltages supplied to the control ‘cir cuit 1, while other potentiometers may control independent circuits in accordance with the mo 40 tion of the shaft 8 as set by the voltages supplied to the control circuit 1. .r==h cos a ' _'y=h sin a ' r :csin a=h COSaSina .- (6) ' 2] 5111 12:12 sin2 a > 1 ‘.~ Y ' . . '1: sin a—_1/ cos a=0 . (4) v<5) ' y cos m='h sin 0: cos a I1! COS 11:71. 0082 a i From which . ' _ . (7) (8) (9) . 1 {(10) ' 7' i 1 In many cases, the, solution of geometrical . I A; 1: cos d-l-y sin m=h ‘ (11)‘ problems involves the use of functions of the In 'Fig. 4a source of ‘voltage 91 is connected geometrical quantities concerned, such as the 45 across the winding of a potentiometer 98 and the trigonometrical functions of the angles con _ wiper of potentiometer 98 is adjusted to select a cerned. The potentiometer H! has a winding voltage proportional to a: which is supplied varying in resistance per unit length in accord through an isolating repeater H of unit gain, to ance with the sine function of an angle to il lustrate this feature of the invention. The po 50 the lower diametrical point 65 of the potentiom eter winding l2, of the type shown in Fig. 2B. tentiometers may conveniently be of the known Voltage is also supplied through the polarity re form in which resistance wire is wound around versing repeater l3 of unit gain to the upper di a flat strip, which is subsequently formed into a ametrical point 66 of the Winding l2. FOr clar circle. The wire on the top edge of the strip is bared, and the wiper arranged, When rotated; 65 ity of illustration, a single line isusedto desig nate a circuit, the grounds shown on the various to rub over the bare wires. The ?at strip is repeaters signifying that one side of both the in shaped to produce the desired variation of resist put and the output circuits are grounded, thus ance with movement of the wiper. Tolinsure completing the return paths of the various cir good contact at all positions between the wiper cuits through the ground. -; ‘ and the winding, the upper edge of the card 60 Assume the voltage proportional to r, sup should be straight. Now, as shown in Fig. 2A, plied to the repeater II, is positive, that the re a normal sinusoidal function has a positive peater 'I l reverses or inverts the polarity to make variation from 0 to 180 degrees, with a positive it negative, and that the repeater I3 again in maximum at 90 degrees, and a negative varia tion from 180 to 360 degrees with a negative 65 verts or reverses the polarity. The voltage sup plied to the point 65 will be proportional to —-:n, maximum at 270 degrees' Such a card does not and the voltage supplied to the point 66 will be provide a‘ straight surface for the wiper, and will proportional to +0.‘. As the resistance of the po introduce 'suoh mechanical difficulties as to rein tentiometer l2 varies per unit length in accord der it impracticable. Preferably, the'potentiom eter is made as shown in Fig. 2B, in which the 70 ance with a sinusoidal function, the :voltage above ground ofthe winding of the potentiom~ wire may be wound on a single card of the shape eter l2 will vary as a ‘sinusoidal function. i Iiaero shown, or on two similar cards, each having the shape of one half of the card shown in Fig. 2A angle be at the point 61, and/ the wiper I4 ro-i and the wiper is in contact with a straight sur tates in a counter-clockwise direction, the spe ‘ face throughout ‘the revolution; ‘The circuit may 75 tential of the wiper 14 with respect to ground 2,404,387 5 '6 will vary from zero to positive maximum to zero with respect to ground will vary from zero to negative maximum to zero to positive maximum suitable networks may be used, depending upon the frequency range to be repeated. Positive voltage from the source 89 is supplied through re sistors 83, 86 to the anodes of vacuum tubes 80, 8|. Negative voltage from the source 89 is sup plied through resistors 85,88 to the control elec trodes of repeaters 8|, 82. An intermediate tap back to zero‘ and this is a variation which may of, the source 89 is connected to connection 90 to negative maximum back to zero, and thisis the variation of a positive sine. Iizero angle be at the point 61 and the wiper l4 rotates in a clockwise direction, the potential of the wiper M b'ete'rmed a negative sine. If the polarities of the potentials applied to the points 65, 68 be reversed, the sign of the functional variation of The may control be grounded. grid of the _ vacuum ' tube 89 -, may . be 10 and self-biased in the usual manner‘by the cathode the potential of the wiper l4 will‘also be re resistor9l. ‘ versed. If zero angle be at the point 88, and the ' ' " , I x . For conveniencein securing a high gain, 'so wiper l4 rotates in a clockwise direction, the po as to provide a large amount of feedback, the tential of the wiper H with respect to ground 15 vacuum tubes 80, 8|, 82 may be screen grid tubes, vary as a positive sine, whereas, if the wiper the screen grids being connected to suitable taps l4 rotates in a counter-clockwise direction, the of the source 89. _' potential of the wiper I4 with respect to ground a Negative voltage is supplied from the source will vary as a negative 'sine. Also, reversing the 89 to the cathode of the vacuum tube 82, and direction of the wiper l4 through 180 degrees will 20 positive voltage is supplied from the source 89 ‘reverse the sign of the function. Thus, any odd number of the following changes will reverse the sign of the function, reverse the direction of ro tation, reverse the polarities of the applied volt~ ages, vreverse the location of the zero angle, re ' verse the direction of the wiper. ' through resistor 92 to the anode of the vacuum tube 82. By suitably proportioning the circuit elements, the voltages applied to the cathode, control grid and anode of the vacuum tube 82 maybe made of such value that the current ?ow ing in the resistor 92 produces a voltage drop equal to the positive voltage from the source 89. Thus, in the absence of a signal voltage, the anode of the vacuum tube 82, and the terminal . ' ,If zero angle be at the point 61, and vthe wiper I4 rotates counter-clockwise, as the potential of the wiper M with respect to ground varies as a positive sine, the potential of the wiper 22, which leads the wiper M by 90 degrees, will vary from positive maximum, to zero, to negative maximum to zero to positive maximum and this is'the vari ation of a positive cosine. If the direction of the 30 98 have the same potential as the wire 99 and no potential is supplied to the output circuit. The negative potential from the source 89 maintains the anode-cathode current in the vacuum tube 82. Assume that a signal voltage is applied to’ the wiper 22 be reversed, so that the wiper 22 lags - behind the wiper‘ [4 by 90'degrees, the poten control grid of vacuum tube 80, so as to make the control grid more negative. The control grid of vacuum tube 8| will become more positive, thus causing the control grid of vacuum tube 82 to ' tial of the wiper 22 with respect toground will vary as what may be termed a negative cosine. .Thus, if a cosine wiper leads a sine wiper by 90 become more negative, decreasing the anode degrees, the cosine has the same sign as the sine; 40 cathode current of the vacuum tube 82 and the whereas, if a'cosine wiper lags behind a sine voltage drop in resistor 92 and causing the ter- wiper by 90 degrees, the cosine has the opposite minal 93 to become more positive with respect to . ‘sign to the sine. the wire 90. The repeater thus reverses the ‘The wiper I4 is moved me counter-clockwise polarity of the applied signal voltage. ' direction from the point 61 from ground through 45 A large value of reverse feedback is supplied the angle a, as yet undetermined, thus the volt through resistor 94 from the anode of vacuum " “age supplied by the wiper lgto the summing ref tube 82 to the control grid of vacuum tube 80. peater |5is proportional to ~ _ As is well known a reverse feedback of this type . A source of voltage 99 is connected across the reduces the apparent input impedance of the winding of a potentiometer I80 and the wiper 50 vacuum tube 80, as viewed from the input cir of the potentiometer I08 is adjusted to select a cuit, to a very low value. Thus, a plurality of voltage proportional to y which is supplied input voltages, respectively connected from the through the isolating repeater l6, and them grounded wire 90 through individual resistors 95, larity reversing repeater l‘! to the diametrical 96 to the signal grid of vacuum tube 88 will each points of .the winding of the potentiometer l8 55 individually a?ect the vacuum tube 80 without of the type shown in Fig. 2B. As :1; is to be mul interaction, and the resultant effect will be the tiplied by the negative cosine of a, and the neg algebraic sum of the applied voltages. ative cosine function is the same as a sine func As a large value of feedback is used, the volt tion displaced by 90 degrees, the wiper l9 is age gain of the repeater is largely controlled by mounted on the shaft 8, on which wiper I4 is also ' 60 the feedback loop. Thus, for each input, the ‘ mounted, at an angle of lag of 90 degrees com-_ voltage gain is proportional to the ratio of the pared’to the Wiper I4; ‘The voltage from the resistance of the resistor 94 to the resistance of wiper |9 supplied to the summing repeater I5 is the input resistor, such as 95 or 96. If these re , then proportional to —1/ cos a. Thus the volt sistances are equal, the voltage gain of the re age supplied to the comparison circuit has the the form 6e=m sin a-y cos or and this is an illus tration of the ?rst extension. ' The summing re , peater I5, which may be of the type shown in Fig. 5, is a thermionic repeater comprising three vac '; 65 peater is unity. 'l'hew'i?tggeférorn/the SW e control circuit , and causes the excitationtoof one or the other 0 e clutch magnets 5, 8 rotating the shaft 8 to such an ‘angle a as will make the input uum tubes80, 8|, 82. As this repeater may op voltage, 86 to the control circuit ‘I equal to zero, erate with low frequency or slowly varying volt 70 I that is, a: sin a-g cos 11:0. The position of the ; ages, the 'interstage networks, formed by re wipers then indicates the angle a. As there is , sistors 83, 84, 85 and resistors 88, 81, 88, may be no theoretical limitation on the size of the mo 01' the type shown in United States Patent tor | or gears 2, and the accuracy and sensitivity of the control by the clutch magnets is not af ‘1,751,527, March v25, 1930, HrNyquist. Any other 2,404,387 7 ,- '8 - . corresponding to ‘the same angular value of sai _fected by the power controlled, the drive may be "made powerful enough to directly control some function, means for obtaining the algebraic sum ‘device, such as an anti-aircraft gun, rotating the ‘ of said selected voltages means for comparing the gun in azimuth to the angle indicated by the co sum of said voltages with a standard voltage ordinates a: and y. ' '- ' e- and a device actuated by the deviation of said . The wiper 2! is parallel to the wiper i4'and algebraic sum from said standard voltage to simultaneously adjust said selection points for will thus supply a voltage 1/ sin a to the summing repeater 62. The wiper 22 is 90 degrees from the wiper l4 and will thus supply a‘voltage :0 cos (1,, and, as wiper 22 is 180 degrees from wiper I9, 10 this voltage will be of opposite polarity, that is, . the-voltage supplied to the summing repeater 62 will be +0: cos a. The ‘voltage produced in the output of the repeater 62, say, across the re sistor 23, will be proportional to ‘n: cos a+y sin a=h successive angular values until said deviation is reduced to zero and the position of the wipers in dicates said angle. - v . “ . ' " , 2. In combination, a source of voltage varying in magnitude with one side of a right triangle, a ‘?rst potentiometer having a winding varying in resistance per unit length with a complete sinusoidal function and a ?rst wiper, a ?rst 'po-‘ larity reversing repeater, means for connecting one pole of said source to the points in said wind the horizontal range. If h wereneeded as a mo . tion a second servo-motor could be used to gen ing where said function passes through zero, and ---''0 cos e, and the sum of these voltages 6e, sup function is a maximum, means for simultaneously erate the desired motion by associating with the 20 the other pole of said source to one point where said function is a maximum, and through said motion a variable voltage to compare with the repeater to the other point where said function voltage h. ' r . I is a maximum, a second source of voltage varying If the repeater 62 reverses the sign of the po in magnitude with the other side of said triangle, tential representing It, so that the sign of this a second potentiometer having a winding Varying potential is opposite to the sign of the potential 25 in resistance per unit length with a complete representing 0, then, when these potentials are sinusoidal function and a second wiper, a‘second applied to the device shown in Fig. 4, the po polarity reversing repeater, means for connect tential reversing repeater H, or l6, as required, ing one pole of said second source to the points may be omitted, so that the applied potentials in the Winding of said second potentiometer ' will be of the same sign as a and y. 30 where said function passes through zero, and the If we now apply the voltage h in place of a: to other pole of said second source to one point in a second system as shown in Fig. 4, and apply the winding of said second potentiometer where the voltage 11 in place of y, the wiper M will se said function is a maximum and through said lect a voltage proportional to h sin e, and the second repeater to the other point where said wiper l9 will select a voltage proportional to plied to the control circuit 1, will cause the shaft driving said wipers, said second wiper lagging 90 Thus, given :13, ‘y, and o, the two steps have wiper contacting the winding of said ?rst poten-v tiometer and a fourth wiper contacting the wind, degrees behind said ?rst wiper, and means for 8 to rotate to indicate the angle 6. At the same adding the voltages selected by said wipers and time the wiper 2! will select a voltage propor controlling said driving means by the sum of 40 tional to 1) sin e, and the wiper 22 will select a said voltages, whereby the displacement of said voltage proportional to it cos. c, and the sum of wipers indicates one angle of said triangle; V345, these voltages will be a voltage in the output of 3. The combination of claim 2 ‘with a third the ‘ampli?er 62 equal to it cos 5+1; Sin e, that is, r. solved the equations - ing of said second potentiometer, said wipers being driven by said driving means, said third J (12) wiper leading said ?rst wiper and said fourth . wiper leading said second wiper by -90 degrees, to produce the angles a and e physically and to produce a voltage proportional to r. The two systems may Work simultaneously to produce the and means for adding the voltages selected by ‘4 w. said third and said fourth wipersto produce a voltage proportional to the hypotenuse ofv said triangle. ?nal result. I - . , ' ' j, . As discussed above, the second servo-motor may be powerful enough to directly elevate an 4. In a computer, a source of voltage propor tional to one side of a right triangle, potentiomi anti-aircraft gun to the angle 6. The voltage 1‘ may be supplied to some device which will indi cate the appropriate fuse setting for this range. I eter means for selecting from said source a voltage porportional to the sine of an angle of said ber of equations by using more of the devices braically adding said selected voltages and motor triangle, a second source of voltage proportional to another side of said triangle, other poten By the use of two of the devices disclosed in Fig. 4, a set of three equations having three un 605 =tiometer means for selecting from said second ‘ source a voltage proportional to the negative of knowns has been solved. Evidently, this use of the cosine of said angle, electrical means for alge the invention may be extended to solve any num showninFig.4. What is claimed is: . . — Y _ ._\ g - .. - _ 1. In combination, resistance means to attenu means controlled by the deviation of the sum of said selected voltages from zero .to ‘adjust both said selecting means to reduce said deviation to ate a ?rst voltage in accordance with a sinusoidal zero, whereby the displacement of saidmotor function, wiper means to select an attenuated voltage corresponding to an angular value of said means indicates said angle. i u function, resistance means to attenuate a second voltage in accordance with a cosinusoidal func tion, wiper means to select an attenuated voltage : ; .DAVID CLARENCE B. PARKINSON , ,, ~- BRUCE T. WEBER. > v

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