US2381733A - Adjustable network - Google Patents

Description

Aug. 7, 1945.

Filed Oct. 16, 1941 F. E FISCHER ADJUS TABLE NETWORK 2 Sheets-Sheet l 4 Fig.1 7 E 5 6 3 8 l ga 6 4 Fig.3 2 7 Fig.4

/NV E/ /TO Aug. 7, 1945. F. E. FISCHER 7 2,381,733

ADJUS TABLE NETWORK Filed Oct. .16; 1941 2 Sheets-Sheet 2 A77- RIYCYS Patented Aug. 7, 1945 Friedrich Ernst Fischer, Zurich, Switzerland Application October 16, 1941, Serial No. 415,332

' In Switzerland June 15, 1940 3 Claims. ((1201-55) The present invention relates to adjustable networks, and more particularly to devices for representing electrically the value of any given function wtih one variable by the method of gradual approach, using at least one large or coarse step and one small or fine step. I

It is the general object of the invention to pro-' vide, in a network containing meansior varying the electrical characteristics of the network in both coarse and fine steps,-as by resistances variable by relatively large and by relatively small units, a device or mechanism between the coarse and fine steps whereby a common drive is effected which operates to determine the number of coarse steps or pitches automatically on switching of the fine steps or pitches. Other objects of the invention will appear from the description hereinafter. Y

It is known that with the assistance of electrical networks functions combined by any given additive and multiplicative connections may be represented. The function valueis in the process taken out of the network in form of electrical voltage.

When using this method it is, however, not pos sible to attain absolute continuity in the realization of the function, in view of the fact that all electrical circuit elements of the network, such as resistances and the like, can only be made adjustable (variable) within certain limits. It is therefore the general practice to adopt gradual division by steps for evaluating given functions.

Should it, however, be found necessary to represent a given function with very close approximation it will generally not be possible to divide up the function throughout into steps of the same size. In such a case the function value will rather be realized with the help of coarse and fine steps which may be graduated according to the decimal system or any other system. Such arrangements are more particularly known for damping members in which, for instance, coarse steps of one neper each and fine steps of neper each are connected in series.

As a matter of principle, almost any function may be resolved into additive and multiplicative connections, either by means of a development in series or by other mathematical operation.

in which there is The following examples may serve to illustrate a: shall be represented by n coarse pitches and m fine pitches, therefore I =1L$g+m$j The function is then expressed by:

y=A(n.x +m.x1)

or such like, orin case a more accurate realiza tion is required-in the form 3. The function y=sin a: shall be represented:

y=sin a:

may be resolved into I y=sin nm .c0s mw +cos nx sin mm;

and can be realized electrically in this form.

Now, if there exists for any given function one additive and multiplicative connection it can always be represented electrically with the help of a network.

The individual function value is made up of values of coarse and fine pitches of which there is a definite number, when the dimensions of the coarse and fine pitches are defined.

The lay-out of a network for representing a function thus resolved into additive and multiplicative connections is known and requires no further explanation. Such arrangements hitherto known have, however, in common that the coarse stepsand likewise the fine stepsmust be adjusted separately according to an appended scale inscribed with the step weights. The drawback of this known arrangement lies in the fact that both coarse and fine steps requires separate adjustment and that consequently for each function value the number of coarse and fine steps required for reproduction according to the degree of accuracy desired-and likewise of the pitches required within these stepsmust be determined beforehand, before adjustment can be carried out. The present invention now solves the problem of connecting coarse and fine steps in such a manner that adrive common to both steps is on the calculated value of the fine step is auto- 2 matically switched back at the extent of the calculated value of one pitch of the coarse step.

The device according to the present invention is controlled from the fine step which is driven continuously, and includes a casing with a num- I ber of spring-loaded pawls by which a rodding actuating the pitch switch gear of the coarse step is held back; the casing containin thepawls is moved to and fro by the common drive of the coarse and fine step, in such-amanner that each time the rod system actuating the pitch switch gear of the coarse step is released at the extent of one pitch by the pawl Holding back the rod systern for switching on the coarse stepthe calculated value of the fine step is automatically switchedb'ack at an extent-corresponding to one pitch of the coarse step.

Generally a function value can be evaluated with sufficient accuracy by one coarse and one fine adjustment. Cases, however; are conceivable in which a greater degree of accuracy may be required, and consequently the evaluation of the function value may require several steps.

The device according to the present invention may of course also find its application in the same manner with several coarse and fine steps.

The nature of the invention will now be more fully explained Vvithlth help of the appended drawings.

Fig; .1 shows the. schematic lay-out of the simplest arrangement for representing a function value by means of one coarse and one fine step.

Fig. 2 shows the connections and method of working of the arrangement according to Fig. 1.

Fig. 3 shows an arrangement in which multilicative connections are additionally inserted between coarse andfine step.

Figure it-finally shows an arrangement with three accuracy steps.

In Fig. 1 one coarse step and one fine step are arranged in the network terminated by the decoupling six-poles I and 2. The rectangle 3 represents the coarse step, rectangle 4, the fine step. A device according to the present invention is inserted between coarse and fine step. As already shown on the schematic figure both the coarse and the fine step have a common drive from the hand-wheel 6. I

Fig. 2 shows more elaborately the complete arrangementaccording to Fig. 1. Here again, I and 2 designate the two decoupling sixpoles l and 2 from Fig. 1. To make things plainer, both the coarse 4-pole and the fine 4-p0le areincluded-in a rectangle anddesignated with 3 and 4. The fine 4-pole-consists of a number of resistances 1 and contacts -8, the size of the resistances being selected in accordance with the functions to be evaluated. In this example of execution the resistances are arranged in concentric circles round a central point in which is located the drive; In this particular examplethere are four circles; on the contact; 8 there'nin current collectors and a er ranged on one common axis I0. On the axis I0 is fitted the cog-wheel H driven from the handwheel 6 over shaft l2 and pinion 13. On shaft I2 is fitted a further cog-wheel I4 which is in engagement with the cog-Wheel I6 fitted on shaft 15. Shaft I5 is connected with shaft l9 over the pair of cog-Wheels l1, l8. Shaft 19 now serves for driving the device according to the present invention and the coarse step switch gear. The device according to the present invention consists of a casing 20 in which are arranged several pawls 2| which under the action of springs 22 are pressed against stops 23. The casing 20 is provided with guides 24' which prevent any lateral displacement, while permitting of a movement up and down. Rods25 are articulated on casing 20; these rods, under the rotatory action of shaft i9, impel casirig iii! upward and downward with the assistance of cog-wheels 26 and 21 and act in this example in the manner of a crank-mechanasm. A rod 29 bearing on its one end a disc 30 is led into the easing 20 through the opening 28. Disc 30 engages behind the pawls 2| and isthereby locked. The rod 29 stands connected through levers3 I, 32 with a slide 33 which is displaced by the action of the threaded section 34 of rod 19, when the latter is rotated, Slide 33 is provided with rod 39 gliding to and fro within the clearances ill-38; this rod 39 is maintained in a medium position by the springs 40-4 I. Rod 39 is connected with slide 23 by means of the mobile rods 42-43 arranged on both sides. Finally, there is a rigid connection be tween rod 39 and rod 46 -which latter leads to the 4-pole 3 and to the switch-gear of 4-pole 4. On rod 46 are fitted current collectors H and 0 running on contact segments 49 and 50 respectively. 1

The purpose of the various parts having thus been explained, the functioning of the arrangement will now be described as follows:

a, the function of which is to be taken on at the sixpole 2 is set at the hand-wheel B. By rotating hand-wheel B the cog-wheel H is first caused to rotate over shaft l2 and cog-wheel la; the, current collectors 9 and 9 mounted on the shaft Ill now start travelling on the concentrically arranged contact segments 8. At the same time, however, the rotatory movement of hand-wheel 6 communicates itself to shaft II, and consequently over cog-wheels l1 and ii-to shaft is as well. According to the position occupied by the casing 20 as the rotatory movement starts, it will now be shifted either upward or downward under the action of the cog-wheels 25--2l and rods 25. In any position the disc 20 is supported by one pawl 2! and is maintained in position by another pawl 2|. If, for instance, the casing is shifted upward out of the position shown on Fig. ;2;-'-one of the pawls 2| supporting the disc 30 will be impelled downward against the pressure exerted by the corresponding spring 22. With the casing in its topmost position the one pawl supporting the disc will be pressed to one side to such an extent that the disc will be enabled to glide past the lock pawl and to move up to the next pawl. Here again, the disc is maintained in position until the casing shall have reached the opposite extreme position, i. e., the lowermost position, whereupon the process Just described again takes place.

Owing to the rotation of shaft ill the slide 88 has now likewise moved to the left 'or to the right respectively. Since "disc 10 was held fast, the consequence of this movement was to compress spring 4! and 40 respectively. At the moment of release of disc 30 the whole rod system 29,:-3l, 32, 42, 43, and also 46, will returnto themedium position under the action of the compressed springs 4| and 40 respectively. This means in other words that the current collectors 41 and 48 are transferred from one contact of the seg ments 49-50 to an adjoining contact. w l

As a result of this mechanical process the-following happenings have taken place in the electrical switch gear. As a consequence of the rotation of hand-wheel Bthe current collectors 9 have now adjusted themselves to one contact 8', in doing whichthe' sum of the resistance 1 set assigned a definite electrical value to the movement of hand-wheel B. 1

The arrangement has now been set up insuch a way that at the moment in which the sum of the resistances I set corresponds to one coarse pitch, this coarse pitch is being actuated in the manner described. The total value, however, would now correspond to the coarse pitch plus the various fine pitches. The fine pitches must therefore be cancelled when switching .a coarse pitch.

This is effected by the displacement of rod 46 which causes the current collectors 48 to come to rest on a contact adjoining contact segments 50. Contacts adjoining segments 50, however, are in each case connected with the diametrically opposed current collectors 9 and 9 respectively. The total fine step, i. e., the total transmission value of the fine 4-pole approximately corressponds in value to 2 coarse pitches. The switching over of the diametrically opposed current collectors 9 and 9 corresponds in each position to one coarse pitch, i. e., by switching over the current collectors 9 and 9 the total transmission value of the network is altered to the extent of the transmission value of one coarse pitch.

As already mentioned, as soon as the fine step is switched to such an extent that the transmission value corresponds to one coarse pitch, this coarse pitch is actuated, while at the same time the fine step is switched back in its transmission value to the extent of one coarse pitch, so that the resulting transmission value remains unaltered just before and after switching over.

The toothed gearing for driving the fine 4-pole and the casing 20 of the device according to the present invention, as well as the corresponding push drives (the crank-mechanism 25-21 shown as examples) are so designed that the movement of the disc 30 always takes place as and when the current collectors 9 or 9 are lying in either one of the intervals in or 102. The strokes of the crank drives 25-21 have been selected so that the switching on of the coarse steps, for example with forward rotation of hand-wheel 6, always takes place at the spots Ia and 11a, corresponding to the interval In at the fine -pole. If, on the contrary, the hand-wheel 6 is rotated back, for example after overstepping the switch position IIa, the next switching back of the coarse steps will already take place at switch position Ib and then after further rotation at IIb, then again at Ib, and so on, i. e., for this sense of rotation the switching over of the current collectors 9 and 9 of the fine 4-pole always takes place in interval L62 of the fine 4-pole.

In order'to make the switching-over process more clearly visible, the course of the current for the switching position as drawn is indicated by thick lines on the drawings.

Fig. 3 shows the arrangement in which multiplicative connections exist between coarse and fine steps, as described above for Example 3. The

device according to the present invention. can of. course find its application with this arrangement in exactly the same manner as with the arrangement according to Fig. 1 as fully described.

The two fine steps 3 and 4 together are driven from hand-wheel l; and likewise thetwo- coarse steps 5 and 6, the common drive of which, how.- ever, takes place from the hand-wheel over a device 2 according to the present invention. 1 and 8 are the two decoupling six-poles. With reference to the problem 3 given as example the following functions may for instance be attributed to the individual l-poles. sents sin (mug) and coarse step 6, cos (mu while the realization of cos (mm) is effected by fine step 3 and the realization of sin (may) by fine step 4. The function values of the two coarsefine ranges 5-'3 and 6-4 respectively received as electrical voltages are thereupon connected additively in the six-pole 8, so that at its outlet there appears the result y=sin (nmg+n:c

It is easy to see that. in itself, the number of the accuracy steps does not play any part, sinceinprinciple-even with severa1 accuracy steps (for instance coarse, medium, fine)-the device as represented may be used for driving the next coarser accuracy step from the neXt finer one, thus solving the problem of actuating the coarse adjustment by a continuous drive of the fine adjustment.

As an example of execution of such an application of the device accordin to the present invention Fig. 4 shows the principle of the switching arrangement of one coarse, medium and fine step each, the function values of which are additively connected. The fine step 6 is actuated by the drive I. From this step is effected-over a device 2 according to the present invention-the drive of the medium step 5, and from this latterover a device 3 according to the present invention-the drive of the coarse step 4. The sixpoles 1, 8, 9 and I0 serve for decoupling, and respectively additively connecting the individual accuracy steps.

What I claim and desire Patent is:

1. Apparatus for evaluating the function values of a given function with one variable according to the method of gradual approach pitch by pitch to the continuously changing real course of the function, comprising an electrical network including a series of coarse and of fine steps for altering the transmission value of the network to yield, in the form of an electrical value, the function values to be ascertained, a common drive for the coarse and'fine steps, a control device between the coarse and fine steps which simultaneously with the continuous drive of the fine step periodically switches the coarse step pitch by pitch, and means whereby each time one coarse pitch is switched on the calculated value of the fine step is automatically switched back to an extent corresponding to one pitch of the coarse step.

2. Apparatus for evaluating the function values of a given function with one variable according to the method of gradual approach pitch by pitch to the continuously changing real course of the function, comprising an electrical network including a series of coarse and of fine steps. for altering the transmission value of the network to yield, in the form of an electrical value, the function values to be ascertained, a common drive for the coarse and fine steps, and a control device to secure by Letters Coarse step 5 repre-' between the coarse and fine steps which simultaneously with the continuous drive of the fine step periodically switches the coarse step pitch by pitch; said control device comprising a casing, a plurality of spring loaded pawls within said caslng, movable rod mechanism controlled by said pawls, a switch gear for the coarse step actuated by said rod mechanism, said casing being oscillatable to release the rod mechanism from control by one pawl and thereby enabling said mechanism to move into position for control by the next adjacent pawl, means actuated by the common drive of the coarse and fine steps for oscillating the casing whereby each time the rod mech anism is released to the extent of one pitch by the pawl which had been holding back the same so as to switch on the coarse step, the calculated value of the fine step is automatically switched back to an extent corresponding to the value of one pitch of the coarse step.

3. Apparatus for evaluating the function values of a given function with one variable according to the method of gradual approach pitch by pitch to the continuously changing real course of the function, comprising an electrical network including a series of coarse and of fine steps for altering the transmission value of the network to yield, in the form of an electrical value, the function values to be ascertained, said fine step comprising a series of contacts arranged side-byside, current collectors associated with the fine step, a common drivefor the coarse and fine steps, a control device between the coarse and iine steps which simultaneously with the continuous drive of the fine step periodically switches the coarse step pitch by pitch, and means whereby each time one coarse pitch is switched on the calculated value of the fine step is automatically switched back to an extent corresponding to one pitch of the coarse step, the side-by-side contacts of the fine step switch gear driven from the coarse step being in each case connected with the current collectors in the fine step, said collectors yielding a transmission value of the fine step differing to the extent of the transmission value of one coarse pitch.

FRIEDRICH ERNST FISCHER.

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