US2887552A - Punched card resistance matrix function generator - Google Patents

Description

I y 1959 H. E. LUSTIG ETAL 2,887,552

PUNCHED CARD RESISTANCE MATRIX FUNCTION GENERATOR Filed 001:. 29, 1956 v 5 S heet 1 5 I CONDUCT/N6 INSULAf/O/ CARD zAr/f INVENTOR Z HOW/4E0 5 LUST/G.

w/ uAME W5 ER 2 BY J ATTORNEY y 19, 1959 H. E. LUSTIG EIAL PUNCHED CARD RESISTANCE MATRIX FUNCTION GENERATOR 3 Sheets-Sheet 2 Filed Oct. 29, 1956 m M RTE Y 055 E if May 19, 1959 H. EfLusTlG ETYAL R 2,887,552

PUNCHED CARD RESISTANCE MATRIX FUNCTION GENERATOR -sn n Filed Oct. 29, 1956 5 S-heets ee 3 31 W I 22 we EUR/9 1??? HO ARD E A 05 776-. W. L IA M E W585i? ATTORNEY United States Patent PUNCHED CARD RESISTANCE MATRIX FUNCTION GENERATOR Howard E. Lustig, Flushing, and William F. Weber, Huntington, N.Y., assignors to Sperry Rand Corporation, Ford Instrument Company Division, Long Island City, N.Y., a corporation of Delaware Application October 29, 1956, Serial No. 619,064

1 Claim. (Cl. 201-48) This invention relates to a resistance generator which provides means for generating circuit values by means of a single input having particular application to and utility in connection with function generating devices.

Computers including function generating devices frequently require a plurality of inputs which have fixed values as determined by reference to a preselected base factor. When the base factor is'known the input analogs may be set into the computer after their determination is made by separate mechanical computation or by mental processes. Their introduction may be simplified by employing electrical means for modifying circuit values on the input side of the computer in accordance with the known relationship between the selected base factor and each of the desired analogs. According to this invention the base factor represents a single input which by its introduction automatically makes available to the computer the required analogs in voltage form. In effect, this input comprises a punched card by means of which resistances are placed in a circuit. The values of these resistances are changed in accordance with the known relationship between the selected base factor and each of the desired analog voltages. The value of each resistance inserted in the circuit is determined by the location of the holes in the punched card, which select and combine fixed resistances in a matrix in such a manner as to produce the desired resistance value within predetermined accuracy limits. Each matrix, by means of the card, thus becomes aneliective single resistance. By exciting each matrix with a fixed reference voltage, placing it in series with either another matrix ora fixed resistor whose other terminal is returned to ground or to a second reference voltage supply, the junction between the two matrices or between the matrix and the fixed resistor will assume a voltage potential which is controlled by the matrices or by the matrix and fixed resistor. Each of these voltages is of desired analog output. Several matrices can be arranged in an array so that their individual effective resistance values are all determined by a single punched card. In this manner, the base factor (punched card) selects a number of desired analog voltages simultaneously.

The following discussion refers to a single card-controlled matrix, which forms the basis of this invention. It has been found that, because the number of preselected resistors is of necessity limited, many resistance values especially in the upper ranges cannot be reproduced within any feasible degree of approximation and that where the values for the individual resistors are selected at random the equivalent resistance output cannot be uniformly generated within the desired limits, the usable range being confined to, the low end. This ettect is called granulation which is particularly pronounced when the resistors are arranged in parallel which is normally a cheaper and simpler arrangement than a series resistor arrangement.

A principal advantage of the invention is the minimization of granulation effect in resistance generators which employ resistance controlled circuits whether the resistors are disposed in parallel or series arrangements. Generally this is accomplished by providing a plurality of resistors having successive values in increments of a binary series and improved means for selecting the resistors for insertion in the input side of a computer circuit. Output error will still depend on the number of resistors in use and the value of the lowest resistor, but for any given number of resistors and value of lowest resistor employed, the error is significantly smaller than for any other than a binary series resistor arrangement that might be used in known devices.

It is therefore an object of the invention to provide a variable resistance generator for simultaneously generating input quantities for computers.

Another object of the invention is the provision of a resistance generator which is capable of generating input quantities uniformly over a desired range.

Other objects and advantages of the invention may be appreciated on reading the following detailed description in conjunction with the accompanying drawings in which Fig. 1 shows schematically a resistance generator with the resistors arranged in parallel in the matrix;

Fig. 2 shows schematically a resistance generator with the resistors arranged in series in the matrix;

Fig. 3 shows in side section a practical embodiment of a parallel resistance generator in closed position;

Fig. 4 is the same as Fig. 3 showing the generator in open position for insertion of the punched card; and

Fig. 5 is a front section of the resistance generator on the line 5-5, of Fig. 3.

As shown in Fig. l the resistance generator comprises generally a circuit with its input lead 4 connected to a square matrix 5, which includes a plurality of resistors 6-21 arranged in parallel in four rows of four resistors in each row and contactors 6a-21a connected separately to the respective resistors and mounted on an insulator plate 22, and a conductor plate 24 connected to the generator output lead 27 in the circuit. A punched card 25 having holes 26 is provided to prevent contact between the contactors and the conductor plate when the two elements are brought into adjacency while the holes permit contact between the plate 24 and the preselected contactors which correspond to the resistors that are desired in the circuit.

Because the resistances are in parallel any equivalent resistance for the circuit may be determined by the addition of admittances corresponding to the resistances which are employed. If, for example, a four resistance circuit were provided with the values of 1, 10, and 1000 ohms respectively, a few resistances in the higher range such as 1000, 100, 90.9091 and 10 ohms could be generated with the remaining generated resistances values below 10 ohms for the most part below 1 ohm. This unevenness in distribution of values may be substantially eliminated by assigning binary increments to the resistances. Thus, resistor 6 is 1 ohm, resistor 7 is 2 ohms, resistor 8 is 4 ohms, resistor 9 is 8 ohms, resistor 10 is 16 ohms, etc.

Within limits, discussed below, any desired resistance can be generated by addition of admittances. For ex- 3 ample, assume that it is desired to obtain a resistance of 5 ohms. The corresponding admittance is 0.2 ohm. We now subtract from this the largest admittance which is equal or smaller. In this case, this is an admittance of .125 ohm, corresponding to the 8 ohm resistor. This leaves 0.2.l25, .075 ohm. From this value we subtract, in turn, the admittances corresponding to 16, 128, 256, 2048, 4096, ohms. If we stop at 4096 ohms, we find that we have generated a resistance of 5.001 ohms.

When the resistors of the function generator are disposed in series, i.e. resistors 6-15 inclusive, as shown in Fig. 2, any value of resistance may be generated'from zero to twice the highest value resistor provided the resistors are disposed in binary series and the lowest value resistor is 1 ohm. With higher lowest value resistors, resistances are generated in steps of the lowest value resistance. Except for single contactor 6a the contactors are mounted in the insulator plate 22 in vertically disposed sets 7a and 7a, 8a and 8a, 2a and 9a, 10a and 10a, 11a and 11a, 12a and 12a, 13a and 13a, 14a and 14a, 15a and 15a and 16a and 16a, which are connected, respectively, to each side of the resistors 6-15 in the circuit. The conductor plate 28 is composed of top and bottom rows of plates, each row being insulated from the other with adjacent plates insulated from each other in the rows the insulated joints of which are broken or staggered so that successive plates in the rows correspond with successive pairs of horizontally adjacent contactors from 6a to 16:1 inclusive for the top row of plates and contactors 7a and 16a inclusive for the bottom row of plates. Any one or more resistors can thereby be effectively shunted as desired.

Thus by choosing successive resistors in binary increments, it may be seen that we can generate any resistance value between zero (input connected directly to output) and two times the highest resistance value K ohms (all resistors in series), in steps of K ohms, where K is the common multiplier of the resistance values 1, 2, 4, 8, etc. Thus, if we use resistances of 5, 10, 20, and 40 ohms, we can generate zero to 75 ohms in steps of 5 ohms. The table below gives pertinent data for various order matnces:

Strips No. of Resolution No. of Resistors per contac- Resistange Range in percent Plate tors 2 3 K( and 1) 100 3 6 Km to 3).-- 33. 3

4 10 K(0 to 7) l4. 3

15 K(0 to 15).- 6. 67

6 21 K(0 to 31) 3. 23

7 28 K(0 to 63) 1. 59

8 36 K(0 to 127 .787

9 45 Km to 255 392 55 K 0 to 511 196 11 66 K(0 to 1,023) 0978 12 78 K(0 to 2,047) 0489 13 91 Km to 4,095) .0244

14 105 K01 to 8,191) 0122 120 K(0 to 16,383).- 00610 16 136 K(0 to 32,76 00305 The final column gives the resolution, i.e., the ratio of the value of the multiplier K to the maximum obtainable resistance in a binary series resistor arrangement. The accuracy to which a given function may be generated is one half the resolution. To illustrate, when using six resistors, each step is 1.59%. As a result, we can obtain any resistance value between 0 and XX 63 ohms to an accuracy of .787%. The six resistor matrix is therefore sufficient for 1% mechanization, while nine resistors are required for .1%.

Referring to Figs. 3, 4 and 5 a bed plate 30 has mounted thereon a vertical back plate 31 and a bracket 32 located on one side of the bed plate and a bracket 33 located on the other side thereof. A pair of guide rods 36 and 37 are horizontally supported in the plate 31 and brackets 32 and 33 respectively. A second pair of guide rods 38 and 39 are horizontally supported by the plate 31 in apertures disposed near its top portion. A vertical member 40 is slidably mounted on the guide rods 36 and 38 and vertical 41 is similarly mounted on guide rods 37 and 39. The insulator plate 22 is supported by and between the vertical members 40 and 41. Contactor holders 43 are received and supported in threaded apertures in the insulator plate 22, the holders being bored to receive cylindrical contactors 45 which are biased by springs in the direction of the interior of the device. The inner side of the holders are apertured to receive axial extensions 47 of the contactors 45 which are in conductive connection with resistors 50, one of which is connected to each holder.

The conductor plate 24 is supported by sleeve bearings 52 slidably carried on the guide rods. The conductor plate 24 has an enlargement 53 at the top which provides a funnelled elongated entrance for the card and flanges 54 with grooves communicating with the entrance. A stop 55 limits the downward movement of the card assuring the proper alignment of the card holes and their respective contactors. The vertical members 40 and 41 are urged against collars on the guide rods by means of springs 56, 57, 58 and 59 as shown in Fig. 4, the springs being carried on the guide rods between the vertical members and the outer ends of the rods.

The extensions 47 of the contactors 45 are adapted to enter the holes in the punched card and contact the conductor plate 24 when the latter is in closed position as shown in Fig. 3. The conductor plate 24 is opened and closed by a toggle arrangement comprising a pair of jointed links 60 and 61 forming a knuckle, the link 60 being pivotally connected to a web 63 secured to a sliding plate 64 on which the conductor plate 24 is mounted, insulation being interposed between the plates, the conductor plate is positioned against the insulator plate when pressure is applied to the links 60 and 61 by lever 65 which is pivotally connected to the knuckle of the toggle. The lever 65 is supported in a ball and socket joint 68 which is connected to the back plate 31 in supporting relation thereto by means of socket plate 70. The back plate 31 is provided with a projection member 71 below the toggle connection serving with the compression springs to lock the conductor plate in closed position.

Instead of a spring back contactor there may be provided between the matrix and the conductor plate a metal cloth which is of sufiicient fineness and resiliency to penetrate the holes of the punched card and establish the desired contact between the two elements under pressure. It may be necessary to print the resistor circuit to obtain the desired binary increment values. Other modifications may occur to one skilled in the art without sacrificing the advantages of the invention or departing from its scope as defined by the following claim.

What is claimed is:

A resistance generator by which selected resistance elements may be connected into an electric circuit, said generator comp-rising; an insulated supporting plate, a plurality of electrically conductive contactors carried by said supporting plate, means yieldingly biasing said contactors outwardly through apertures in said supporting plate, a single imperforate unitary conductor plate to which all of said contactors are adapted to be selectively brought into electrical contact, an electric circuit having a single input conductor and a single output conductor, said output conductor being permanently connected directly to said conductor plate, a plurality of individual resistance elements, the input ends of said resistance elements being permanently connected directly to said single input conductor in parallel with each other, the output ends of each of said resistance elements being permanently connected directly to an associated one of said conductive contactors, a non-conductive card removably mounted between said supporting plate and said conductor plate with the opposite faces thereof in contact with the opposed faces of said supporting plate and said conductor plate, and a plurality of punched aper- 5 tures through said card in alignment with pre-selected contactors through which said selected contactors extend into electrical contact with said conductor plate, and by which card the non-selected contactors are held out of contact with said conductor plate by means of their en- 10 gagement with imperforate sections of said card.

References Cited in the file of this patent UNITED STATES PATENTS Johnson Feb. 9, Johnson Aug. 3, Oldenboom July 4, Paris June 8, Johnson Apr. 4, Betts May 27, Schuck Aug. 16,

Cobb Aug. 12,

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